WO2018016155A1 - Process for producing metal oxide catalyst - Google Patents

Process for producing metal oxide catalyst Download PDF

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Publication number
WO2018016155A1
WO2018016155A1 PCT/JP2017/017430 JP2017017430W WO2018016155A1 WO 2018016155 A1 WO2018016155 A1 WO 2018016155A1 JP 2017017430 W JP2017017430 W JP 2017017430W WO 2018016155 A1 WO2018016155 A1 WO 2018016155A1
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metal oxide
oxide catalyst
mass
acrylic acid
stage
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PCT/JP2017/017430
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French (fr)
Japanese (ja)
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正治 横幕
若山　敏之
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東亞合成株式会社
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Priority to JP2018528412A priority Critical patent/JPWO2018016155A1/en
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/02—Sulfur, selenium or tellurium; Compounds thereof
    • B01J27/057—Selenium or tellurium; Compounds thereof
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/08—Heat treatment
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J37/00—Processes, in general, for preparing catalysts; Processes, in general, for activation of catalysts
    • B01J37/16—Reducing
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
    • C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
    • C07C51/215—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of saturated hydrocarbyl groups
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07B—GENERAL METHODS OF ORGANIC CHEMISTRY; APPARATUS THEREFOR
    • C07B61/00—Other general methods

Definitions

  • the present invention relates to a method for producing a metal oxide catalyst suitably used for the production of acrylic acid by vapor phase catalytic oxidation of propane and the production of acrylonitrile by ammoxidation of propane.
  • Acrylic acid is produced by a two-step oxidation reaction in which acrolein is produced by contact reaction of propylene and oxygen in the presence of a catalyst, and the resulting acrolein is further contacted with oxygen.
  • a method for producing acrylic acid in one stage using propane as a starting material has been studied.
  • Patent Document 1 a method for producing a metal oxide catalyst by a slurry method using metal tellurium as a raw material
  • Patent Document 2 A method for producing a metal oxide catalyst to be subjected to sonication (Patent Document 2) has been proposed.
  • the metal oxide mixture obtained by the slurry method or hydrothermal synthesis method is converted into a crystal structure having catalytic performance through drying and calcination.
  • the calcination is generally divided into two or more steps. For example, the first stage is treated for 2 to 20 hours in the temperature range of 250 ° C. to 380 ° C.
  • the second stage is 500 in the absence of oxygen.
  • examples thereof include a method in which the treatment is carried out at a temperature range of from 0 to 660 ° C. for 0.5 to 6 hours.
  • a firing method a method has been proposed in which an index called a reduction rate is introduced into the second-stage firing process to adjust the firing process in the presence of the first-stage oxygen (Patent Document 3).
  • the present inventors have intensively studied. As a result, in a method for producing a metal oxide catalyst having a specific composition formula, the material obtained by performing the firing in two stages and the first stage firing. Is included in the range of specific analysis values, it has been found that a metal oxide catalyst in which variation in catalyst performance is suppressed can be obtained, and the present invention has been completed.
  • the first invention of the present invention is a step of reducing a Te 4+ compound or a Te 6+ compound in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium, unreacted from the reduced product.
  • Composition formula MoV i Te j A k O y
  • A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements
  • i and j are each 0.01 to 1.5
  • j / i 0.3 to 1.0
  • k is 0.001 to 3.0
  • y is an oxidation state of another element.
  • Is a number determined by Analytical value A: The mass change rate defined by the following formula 1 is 1.2 to 4.0%. Mass change rate (%) [(mass before heating ⁇ mass after heating) / mass before heating] ⁇ 100 (formula 1)
  • Analysis value B The nitrogen content in the elemental analysis of carbon, hydrogen and nitrogen by the combustion method is 0.8 to 1.5 mass%.
  • the step of obtaining the reactant comprises reacting a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V and water, It is a manufacturing method of the metal oxide catalyst as described in 1st invention which is the process of mixing and reacting with the compound to contain, and obtaining a reaction material.
  • the third invention of the present invention is the method for producing a metal oxide catalyst according to the first invention or the second invention, wherein the substance obtained by the first-stage calcination is included in the following analysis value C.
  • Analytical value C The number of moles of oxygen consumed per 1 g of the sample obtained by subjecting the solution in which the sample is dispersed in the sulfuric acid aqueous solution to oxidation-reduction titration with heating using an oxidizing agent is 3.4 to 5.5 mmol. .
  • the fourth invention of the present invention is the metal oxide catalyst according to any one of the first to third inventions, wherein the second stage calcination is performed in the temperature range of 500 ° C. to 660 ° C. in the absence of oxygen. It is a manufacturing method.
  • the fifth invention of the present invention is a method for producing acrylic acid in which propane is oxidized by a gas phase catalytic reaction using the metal oxide catalyst obtained by any one of the first to fourth inventions.
  • the firing state of the first stage can be grasped in a short time by an inspection method of thermal mass spectrometry or elemental analysis, so that there is little variation in catalyst activity.
  • a metal oxide catalyst can be produced.
  • the metal oxide catalyst in the present invention is a metal oxide represented by the following composition formula.
  • Composition formula: MoV i Te j A k O y (In the formula, A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements.
  • the metal oxide is a reduced product containing metal tellurium by reducing a Te 4+ compound or a Te 6+ compound (a compound in which the tellurium valence is 4 or 6) with a reducing agent in the presence of water or an organic solvent. Then, the unreacted reducing agent is removed from the reduced product, and then the reduced product containing metal tellurium from which the unreacted reducing agent has been removed is reacted in the presence of Mo, V, A element and water. Then, it is dried and fired to produce. Furthermore, it is necessary that the calcination is performed in two stages and a substance obtained by the first calcination is included in at least one analysis value of the analysis value A and the analysis value B.
  • steps (1) to (5) a specific manufacturing method will be described in steps (1) to (5).
  • methods such as heat treatment, coprecipitation, drying and calcination, and crystal formation using hydrothermal synthesis, which are known techniques in the catalyst technical field, can be used without limitation.
  • the method for producing a metal oxide catalyst of the present invention is a step of reducing a Te 4+ compound or a Te 6+ compound in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium (step (1)). )including.
  • a Te 4+ compound or a Te 6+ compound is reduced in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium as a raw material component of the catalyst.
  • Te 4+ compound and Te 6+ compound used for the raw material can be used without any particular limitation.
  • tellurium dioxide tellurium trioxide, tellurium tetrachloride, orthotelluric acid, metatelluric acid, polymetatelluric acid, ammonium tellurate
  • Examples include alkali metal tellurates, zinc tellurates, calcium tellurates, silver tellurates, thallium tellurates, copper tellurates and magnesium tellurates, among which tellurium dioxide or ortho telluric acids are preferred.
  • the reducing agent is a reducing substance (atom, molecule, or ion having a property of easily giving electrons to other molecules) having a redox potential of 0.53 V or less (the potential of tellurium dioxide is around 0.53 V) with respect to the standard electrode.
  • Hydrazine, hydrazinium salts, hydroxylamine, and the like are preferable. Specific examples include hydrazine acetate, hydrazine dihydrobromide, hydrazine dioxide, hydrazine monohydrochloride, hydrazine monohydrate, hydrazine sulfate, hydroxylamine, hydroxylammonium chloride, and hydroxylammonium sulfate.
  • the amount of reducing agent used varies depending on the type of reducing agent and reaction conditions.
  • the molar ratio of hydrazine to tellurium is preferably 0.5 to 4.0, and 1.0 to 3.0. More preferred. If the amount of hydrazine used is 0.5 or more, the remaining amount of tellurium dioxide is small, and if the amount used is 4.0 or less, the advantage of increasing the amount used is sufficiently obtained, which is extra for the removal of unreacted hydrazine. Reduces the amount of labor and cleaning liquid that is unnecessary or required. The same applies to a reducing agent other than hydrazine.
  • the reduction reaction is carried out in a liquid such as water or an organic solvent.
  • a liquid such as water or an organic solvent.
  • organic solvent alcohols, hydrocarbons and the like are preferable.
  • the presence of the liquid disperses the tellurium compound and facilitates the reduction reaction, so that the metal tellurium particles obtained are uniform.
  • the reduction conditions for the tellurium compound can be appropriately selected in consideration of the solubility of the tellurium compound used in water or an organic solvent and the reactivity of the reducing agent.
  • the reduction reaction proceeds only by adding hydrazine to an aqueous solution of telluric acid, and metal tellurium particles are formed in water.
  • tellurium dioxide which is a tellurium compound having poor solubility in an organic solvent
  • the reduction reaction proceeds slowly. In this case, it is necessary to promote the reaction by stirring and heating over time.
  • the reaction is preferably performed at a temperature of 40 ° C. to 100 ° C. and a stirring speed of 100 to 500 times / minute for 1 to 20 hours.
  • a method for promoting the reduction reaction there is a method of wet pulverization in the presence of a tellurium compound, a reducing agent, water or an organic solvent instead of heating and stirring.
  • the organic solvent used for pulverization is not particularly limited, but is preferably an organic solvent that is liquid at room temperature and can be easily removed in a subsequent process. Specifically, alcohols such as methanol, ethanol, and propanol, hexane, Hydrocarbons such as cyclohexane and toluene are preferred.
  • the mixing ratio of the tellurium compound and water or organic solvent during pulverization is preferably 10 to 1,000 parts by mass of water or organic solvent, more preferably 30 to 300 parts by mass per 100 parts by mass of the tellurium compound.
  • the water or organic solvent is 10 parts by mass or more, the pulverized product is less likely to adhere to the pulverization container and is easily pulverized.
  • the water or organic solvent is 1,000 parts by mass or less, the water or the organic solvent is pulverized. Suppresses impact absorption and excels in grinding efficiency.
  • the pulverizer is preferably of a type that pulverizes by driving the container itself containing the material to be crushed. Specific examples include a ball mill, a vibration mill, and a planetary ball mill.
  • the grinding time is preferably 0.5 to 24 hours.
  • the size of the primary particles of metal tellurium obtained by the reduction reaction is preferably 4.0 ⁇ m or less, more preferably 2.0 ⁇ m or less in at least one direction. There is no particular lower limit on the size of the primary particles, but 10 nm or more is preferable from the viewpoint of ease of operation. When the size of the primary particles is 4.0 ⁇ m or less, the dispersibility of the metal tellurium particles in water or an organic solvent is excellent.
  • Step (2) The manufacturing method of the metal oxide catalyst of this invention includes the process (process (2)) which removes an unreacted reducing agent from the said reduced material.
  • process (2) unreacted reducing agent remaining in the reduced product containing metal tellurium obtained in step (1) is removed, and when an organic solvent is used as the medium for the reduction reaction, the solvent is added to water. It is preferable that the step is a step of obtaining an aqueous dispersion of a reduced product by replacing with.
  • a method of redispersing the reduced product in water can be exemplified.
  • an aqueous dispersion of a reduced product containing metal tellurium from which the unreacted reducing agent and organic solvent have been removed is obtained.
  • the amount of water required for replacement is preferably 1.0 to 8.0 times, more preferably 2.0 to 4.0 times in volume ratio with respect to the reduced product dispersion.
  • Step (3) is a step of mixing an aqueous dispersion of a reduced product containing metal tellurium obtained in Step (2) above, a Mo 6+ compound and a V 5+ compound, and reacting them at a temperature of 40 ° C. or higher for 1 hour or longer. It is.
  • the aqueous dispersion may be further diluted by adding water in order to improve operability.
  • the reaction temperature is preferably 40 ° C. to 100 ° C.
  • the reaction time is preferably 1 to 10 hours, more preferably 2 to 5 hours.
  • Mo 6+ compound examples include ammonium molybdate, molybdenum oxide, and molybdic acid. Among these, ammonium molybdate is preferable because it is water-soluble. As the V 5+ compound, ammonium metavanadate and vanadium pentoxide are preferable.
  • the addition amount of the Mo 6+ compound and the V 5+ compound is such that the atomic ratio (i and j) of V and Te to this is 0.01 to 1.5 based on Mo, respectively, and the atomic ratio of Te to V ( j / i) is 0.3 to 1.0.
  • Step (4) the reaction solution obtained in the step (3) and a compound containing the metal element A (hereinafter referred to as A-containing compound) are mixed.
  • the A-containing compound is preferably mixed in the form of an aqueous solution or an aqueous dispersion. By this mixing operation, fine precipitates are generated in the reaction solution.
  • the reaction temperature is not particularly limited, but it is preferable to mix at room temperature (10 ° C. to 35 ° C.).
  • the step (4) can be performed simultaneously with the step (3). That is, in the step (3), an A-containing compound can be present at the same time.
  • the metal element A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements, and A Examples of the contained compound include these oxides, nitrates, carboxylates, oxoacid salts, and oxalates.
  • the A-containing compound When the A-containing compound is insoluble, it may be dispersed and mixed in water, but it can be dissolved in water by using oxalic acid or the like in combination.
  • the mixing amount of the A-containing compound is the atomic ratio of the metal in the obtained metal oxide catalyst.
  • Mo is 1, the metal element A is 0.001 to 3.0.
  • the ratio of the metal element A is less than 0.001, the obtained catalyst may be deteriorated, and when it exceeds 3.0, the activity of the catalyst may be lowered.
  • nitric acid or ammonium nitrate may be added to the mixed solution in which the reaction solution obtained in the step (3) and the A-containing compound are mixed to produce a precipitate, and the resulting metal oxide catalyst Can be expected to improve performance and physical strength.
  • a preferable addition amount of nitric acid or ammonium nitrate is preferably 0.7 to 2.1, more preferably 0.5 to 1.7 in terms of molar ratio to metal Te.
  • the mixing of the reaction solution obtained in the step (3) and the compound containing the metal element A is preferably performed in 15 minutes or less, more preferably in 10 minutes or less. It is more preferable to carry out in 5 minutes or less, and it is particularly preferable to carry out in 1 minute or less.
  • the acrylic acid selectivity and acrylic acid yield are excellent when acrylic acid is produced by propane oxidation using the resulting metal oxide catalyst.
  • the method for producing a metal oxide catalyst of the present invention includes a step (step (5)) in which the obtained reactant is dried and calcined to obtain a metal oxide catalyst represented by the above composition formula.
  • step (5) it is preferable that the mixed solution (slurry) obtained through the step (4) is evaporated to dryness, and the dried product obtained is dried and then fired.
  • the above mixed solution contains a large amount of water.
  • known evaporation to dryness, spray drying, and the like can be used.
  • the liquid mixture may be simply heated to evaporate the water, but it can be efficiently dried by blowing an inert gas such as nitrogen or air during evaporation to dryness.
  • the temperature for evaporation to dryness is preferably 50 ° C to 130 ° C.
  • the first stage firing is preferably carried out at a temperature of 250 ° C. to 380 ° C. in the presence of oxygen using a rotary furnace, specifically preferably a batch or continuous rotary kiln, and more preferably 280 ° C. ⁇ 330 ° C.
  • the firing time is preferably 5 minutes to 20 hours, more preferably 10 minutes to 3 hours. It is necessary that the substance obtained by the first stage baking is included in the range of at least one of the following analysis values A and B.
  • the firing temperature is preferably 500 ° C. to 660 ° C. in the absence of oxygen, and more preferably 570 ° C. to 640 ° C.
  • the firing time is preferably 0.5 to 6 hours, more preferably 1 to 3 hours.
  • the second stage baking is preferably performed in a muffle furnace.
  • Mass change rate [(mass before heating ⁇ mass after heating) / mass before heating] ⁇ 100 (formula 1)
  • the mass change rate is measured by sampling a sample that has been baked in the first stage, measuring the mass before heating, and then subjecting it to a heat treatment at 500 ° C. to 650 ° C. for 10 minutes to 90 minutes in the muffle furnace. And measure the mass after heating.
  • data can be acquired after the inside of the muffle furnace is replaced with nitrogen, loss of replacement time and variation in the state of replacement in the furnace are anxious materials, so they are not indispensable.
  • FIG. 1 shows the relationship between the firing time and the mass change rate of the substance obtained by heating the first stage baking at 310 ° C. for 2 to 240 minutes. According to FIG. 1, it can be seen that the firing state progresses as the firing time becomes longer, and the mass change rate changes in correlation with the firing time.
  • Analysis value B (elemental analysis)
  • the nitrogen content in the elemental analysis of carbon, hydrogen and nitrogen by the combustion method is 0.8 to 1.5% by mass.
  • elemental analysis elemental analysis of carbon, hydrogen and nitrogen is performed by a combustion method which is a general method.
  • the relationship between the baking time (2 to 240 minutes) and the nitrogen content by elemental analysis when baking at 310 ° C. with a tabletop rotary kiln (manufactured by Takasago Industry Co., Ltd.)
  • FIG. According to FIG. 2, it can be seen that the firing state proceeds as the firing time becomes longer, and the nitrogen content changes in correlation with the firing time.
  • the substance obtained by the first stage baking is included in the range of the analytical value C below.
  • Analysis value C The number of moles of oxygen consumed per 1 g of the sample obtained by oxidation-reduction titration with an oxidizing agent under heating of a solution in which the sample is dispersed in an aqueous sulfuric acid solution is 3.4 to 5.5 mmol.
  • a dispersion obtained by adding a sample after the first stage baking to an aqueous sulfuric acid solution is analyzed at 40 to 90 ° C., preferably 50 to 70 ° C.
  • the reducing agent is not particularly limited, a commercially available N / 40 potassium permanganate aqueous solution is preferable.
  • firing time (2 to 90 minutes) when firing at 310 ° C. using a tabletop rotary kiln (manufactured by Takasago Industry Co., Ltd.) and redox titration of the first-stage fired product The relationship with the quantity is shown in FIG. According to FIG. 3, it can be seen that the redox titer of each sample changes in correlation with the firing time.
  • FIG. 4 shows the results of investigating the performance of the metal oxide catalyst produced by firing the second-stage calcined product under various conditions under the same conditions.
  • the horizontal axis indicates the propane conversion
  • the vertical axis indicates the acrylic acid selectivity
  • the acrylic acid yield is indicated by a broken line.
  • the curve of the catalyst performance has a maximum point of the acrylic acid yield, and the first stage calcination state greatly affects. Therefore, in order to reduce variation in catalyst performance, it is important to grasp the first stage firing state.
  • the mass change rate, the nitrogen content, and the redox titration analysis values change in correlation with the firing state of the first stage. Therefore, the first stage firing product is analyzed by the above analysis method. It is possible to determine the firing state of the stage.
  • the second stage baking is performed in the absence of oxygen.
  • the baking apparatus include, but are not limited to, a muffle furnace and a rotary kiln.
  • the second stage baking temperature is preferably 500 ° C. to 660 ° C., more preferably 570 ° C. to 640 ° C.
  • the baking time is preferably 0.5 to 6 hours, and preferably 1 to 3 hours. More preferred.
  • the metal oxide catalyst obtained by the above steps (1) to (5) can be used as it is, but it is preferable to use it by pulverizing to an appropriate particle size to increase the surface area of the catalyst.
  • a known dry pulverization method and wet pulverization method can be used.
  • Specific examples of the pulverizer include a mortar and a ball mill.
  • examples of the solvent used as a grinding aid include water and alcohols.
  • the particle size is preferably 20 ⁇ m or less, more preferably 5 ⁇ m or less.
  • the metal oxide catalyst can be used without a carrier, but can also be used by being supported on a known carrier such as silica, alumina, silica alumina, silicon carbide or the like having an appropriate particle size.
  • a known carrier such as silica, alumina, silica alumina, silicon carbide or the like having an appropriate particle size.
  • the carrying amount is not particularly limited and conforms to the conventional carrying amount.
  • propane and oxygen gas as raw materials into the reactor filled with the metal oxide catalyst, propane is vapor-phase contact oxidized by the metal oxide catalyst to generate acrylic acid.
  • propane and oxygen gas may be separately introduced into the reactor and mixed in the reactor, or may be introduced into the reactor in a state where both are mixed beforehand.
  • oxygen gas examples include pure oxygen gas and air, and gas obtained by diluting these with nitrogen, steam, carbon dioxide gas, or the like.
  • propane and air are used as raw materials, the use ratio of air to propane is preferably 30 times or less in volume ratio, more preferably 0.2 to 20 times.
  • the reaction temperature is preferably 300 ° C. to 600 ° C., more preferably 350 ° C. to 500 ° C.
  • the space velocity (hereinafter referred to as SV) of the source gas is suitably 1,000 to 8,000 hr ⁇ 1 . When the space velocity is at 1,000 hr -1 or more, to improve the yield of acrylic acid as the target compound, if it is 8,000Hr -1 or less, to improve the reaction rate.
  • Unreacted raw propane present in the reaction gas discharged from the reactor outlet and propylene as an intermediate product can be used as fuel as they are, but they are separated from other components in the reaction gas before being sent to the reactor. It can be returned and reused.
  • the metal oxide catalyst produced according to the present invention can also be applied to propane ammoxidation, and acrylonitrile can be produced in high yield.
  • the ammoxidation conditions are the same as those for the above-mentioned vapor-phase catalytic oxidation of propane.
  • each raw material was blended so that the ratio of each metal constituting the obtained metal oxide catalyst was the following value.
  • Mo / V / Te / Nb 1.0 / 0.25 / 0.13 / 0.12 (molar ratio)
  • the production test of acrylic acid in each example was performed as follows. 1.1 ml (1.0 g) of the metal oxide catalyst obtained in each example was filled in a 10 mm ⁇ quartz reaction tube, the reaction tube was heated to 400 ° C., 6.4 vol% propane, oxygen Acrylic acid was produced by feeding a mixed gas of 9.6 vol%, nitrogen 36.1 vol% and water vapor 47.7 vol% at a space velocity of 3,924 / hr- 1 . Perform composition analysis of each product component in the reaction product, and calculate the propane conversion, acrylic acid selectivity and acrylic acid yield shown in the following formula on a molar basis, and evaluate the performance of the metal oxide catalyst. Are listed in Tables 2-5.
  • Propane conversion (%) [(feed propane-unreacted propane) / feed propane] ⁇ 100 (formula 2)
  • Acrylic acid selectivity (%) [produced acrylic acid / (feed propane-unreacted propane)] ⁇ 100 (formula 3)
  • Acrylic acid yield (%) (propane conversion ⁇ acrylic acid selectivity) / 100 (formula 4)
  • the metal tellurium aqueous dispersion was added to the resulting solution, heat-treated for 1 hour, and then cooled to 30 ° C. with ice water.
  • 8.82 g of oxalic acid and 3.48 g of niobic acid were dissolved in 140 ml of distilled water to prepare a room temperature aqueous solution.
  • This aqueous solution was added to the reaction solution over 10 seconds.
  • the resulting mixture was vigorously stirred for 10 minutes, and then 5.0 g of ammonium nitrate was mixed with this mixture. Thereafter, the mixture was concentrated by heating and further evaporated to dryness at 120 ° C.
  • the obtained distilled and dried product was fired at 310 ° C.
  • the second stage calcination was performed in an inert atmosphere in which nitrogen gas was circulated in a muffle furnace at 600 ° C. for 2 hours to obtain a metal oxide catalyst.
  • the obtained catalyst was tableted and the molded product was pulverized to 16-30 mesh and used for the acrylic acid production reaction.
  • the propane conversion was 69% and acrylic acid selectivity was obtained.
  • FIG. 4 it is expected that acrylic acid selectivity is improved when the first stage baking is performed a little longer, as shown in FIG.
  • Example 1 The evaporated and dried product obtained in Test Example 1 was baked at 310 ° C. for 90 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process as Test Example 1 After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace for inspection, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 2.1%.
  • the second stage calcination was performed in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 60 %, Acrylic acid selectivity was 73%, and acrylic acid yield was 44%. It was confirmed that the first stage baking was in an appropriate range and the acrylic acid selectivity was improved as compared with Test Example 1.
  • Test Example 2 The evaporated and dried product obtained in Test Example 1 was baked at 330 ° C. for 90 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process as Test Example 1 After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace for inspection, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.1%.
  • the second stage calcination was carried out in the same manner as in Test Example 1, and the resulting catalyst was subjected to tableting, and the molded product was pulverized to 16-30 mesh and used in the acrylic acid production reaction.
  • Example 2 The evaporated and dried product obtained in Test Example 1 was baked at 330 ° C. for 60 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating at 600 ° C. for 10 minutes in the air in a small muffle furnace, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.9%.
  • the second stage calcination was carried out in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16-30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 61 %, Acrylic acid selectivity was 73%, and acrylic acid yield was 44%. Compared with Test Example 2, the heating time was shortened so that the first stage firing was in an appropriate range, so the propane conversion increased to 60%.
  • Test Example 3 The evaporated and dried product obtained in Test Example 1 was baked at 350 ° C. for 60 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating at 600 ° C. for 10 minutes in the air in a small muffle furnace for use, cooling to 100 ° C. or lower in a desiccator and weighing again, the weight change rate was 0.7%. The second stage calcination was carried out in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction.
  • the propane conversion was 13 %, Acrylic acid selectivity 62%, and acrylic acid yield 8%.
  • the first stage of calcination was outside the proper range and entered the region where the calcination was excessive. This affected the propane conversion, and the acrylic acid yield was lowered.
  • Example 3 The evaporated and dried product obtained in Test Example 1 was baked at 350 ° C. for 30 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.4%.
  • the second stage calcination was performed in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used for the acrylic acid production reaction. %, Acrylic acid selectivity was 70%, and acrylic acid yield was 42%. From the result of Test Example 3, since the time was shortened so that the first stage firing was in an appropriate range, the propane conversion was recovered to 61%.
  • Test Example 4 The same evaporated and dried product as in Test Example 1 was baked at 310 ° C. for 15 minutes in the air using a batch rotary kiln. As a result of measuring the nitrogen content of the obtained sample with an elemental analyzer, it was 1.6% by mass. Next, the second calcination was performed under the same conditions as in Test Example 1, the obtained catalyst was tableted, the molded product was pulverized to 16-30 mesh, and used in the acrylic acid production reaction. The propane conversion was 69%, the acrylic acid selectivity was 64%, and the acrylic acid yield was 44%.
  • Example 5 Compared to Test Example 4, the first stage baking time was changed to the time shown in Table 3. In Example 4 where the firing time was 30 minutes, the nitrogen content was 1.2% by mass, the second stage of firing was performed under the same conditions as in Test Example 1, and the resulting catalyst was tableted and molded. As a result of pulverizing the product to 16-30 mesh and using it for the production reaction of acrylic acid, the propane conversion was 66%, the acrylic acid selectivity was 71%, and the acrylic acid yield was 47%, and the catalyst performance could be improved.
  • Example 5 was fired in the same manner as in Example 4 except that the firing time was 60 minutes, and Example 6 was fired for 120 minutes. As a result, the nitrogen content was 0.9% by mass and 0.8%, respectively.
  • the redox titer was 21 ml each. (Mole oxygen conversion: 3.3 mmol / sample 1 g) and 18 ml (oxygen mole conversion: 2.8 mmol / sample 1 g).
  • the second stage of calcination was performed, the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. It was as follows.
  • Example 9 In Test Example 1, the addition time of niobium oxalate was changed from 10 seconds to 3 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
  • Example 10 In Test Example 1, the addition time of niobium oxalate was changed from 10 seconds to 6 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
  • Example 11 In Test Example 1, niobium oxalate and the reaction solution were mixed using a static mixer T4-21R (trade name, manufactured by Noritake Co., Ltd.), which is an industrial continuous mixer, a static mixer, to prepare a slurry, The dried product obtained in the same manner as in Example 1 was baked and used for the reaction for producing acrylic acid.
  • a static mixer T4-21R trade name, manufactured by Noritake Co., Ltd.
  • Test Example 1 the addition time of niobium oxalate was changed from 10 seconds to 20 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
  • the firing state of the first stage can be grasped in a short time by an inspection method of thermal mass spectrometry or elemental analysis, so that there is little variation in catalyst activity.
  • a metal oxide catalyst can be produced.
  • the produced metal oxide catalyst exhibits excellent catalytic activity in terms of propane conversion, acrylic acid selectivity and acrylic acid yield, so it can be used as a catalyst for the production of acrylic acid by vapor phase catalytic oxidation of propane. it can.

Abstract

The problem to be solved by the present invention is to produce, with satisfactory reproducibility, a metal oxide catalyst having excellent catalyst performance. The process for producing a metal oxide catalyst according to the present invention includes performing burning in two stages, a substance obtained in the first-stage burning satisfying analysis value A and/or analysis value B. Empirical formula: MoViTejAkOy Analysis value A: The value of mass change defined by equation 1 is 1.2-4.0%. Mass change (%) = {[(mass before heating)-(mass after heating)]/(mass before heating)}×100 (equation 1) Analysis value B: The nitrogen content, as determined by elemental analysis for carbon, hydrogen, and nitrogen by a combustion method, is 0.8-1.5 mass%.

Description

金属酸化物触媒の製造方法Method for producing metal oxide catalyst
　本発明は、プロパンの気相接触酸化によるアクリル酸の製造およびプロパンのアンモ酸化によるアクリロニトリルの製造に好適に使用される金属酸化物触媒の製造方法に関する。 The present invention relates to a method for producing a metal oxide catalyst suitably used for the production of acrylic acid by vapor phase catalytic oxidation of propane and the production of acrylonitrile by ammoxidation of propane.
　アクリル酸は、触媒の存在下でプロピレンと酸素とを接触反応させてアクロレインを製造し、得られたアクロレインを、さらに酸素と接触反応させる二段階の酸化反応により製造されている。
　一方、プロパンとプロピレンとの価格差、および二段階の酸化に伴う工程の複雑さ等の問題を解消する目的で、プロパンを出発原料として一段階でアクリル酸を製造する方法が検討されており、その際に使用される触媒に関する提案も多数なされている。その代表例として〔Ｖ、Ｐ、Ｔｅ〕系、〔Ｍｏ、Ｔｅ、Ｖ、Ｎｂ〕系および〔Ｍｏ、Ｓｂ、Ｖ、Ｎｂ〕系等の複合金属酸化物からなる触媒が挙げられる。 Acrylic acid is produced by a two-step oxidation reaction in which acrolein is produced by contact reaction of propylene and oxygen in the presence of a catalyst, and the resulting acrolein is further contacted with oxygen.
On the other hand, for the purpose of solving the problems such as the price difference between propane and propylene and the complexity of the process associated with the two-stage oxidation, a method for producing acrylic acid in one stage using propane as a starting material has been studied. Many proposals have been made regarding the catalyst used in this case. Typical examples thereof include catalysts composed of complex metal oxides such as [V, P, Te], [Mo, Te, V, Nb], and [Mo, Sb, V, Nb].
　さらに、上記の金属酸化物触媒の改良に関する発明が数多く特許出願されていて、例えば、金属テルルを原料に用いるスラリー法による金属酸化物触媒の製造方法（特許文献１）、水熱合成法において超音波処理を施す金属酸化物触媒の製造方法（特許文献２）などが提案されている。
　スラリー法や水熱合成法で得られる金属酸化物混合物は、乾燥および焼成を経て触媒性能を有する結晶構造に変換される。該焼成は、一般的に２工程以上に分割され、例えば、１段目は酸素存在下で２５０℃～３８０℃の温度範囲で２～２０時間処理され、２段目は酸素不存在下で５００℃～６６０℃の温度範囲で０．５～６時間処理される方法などが挙げられる。
　また、焼成方法に関して、２段目の焼成工程に還元率という指標を導入して、１段目の酸素存在下での焼成工程を調整する方法が提案されている（特許文献３）。 Furthermore, many inventions related to the improvement of the above metal oxide catalyst have been filed. For example, in a method for producing a metal oxide catalyst by a slurry method using metal tellurium as a raw material (Patent Document 1), in a hydrothermal synthesis method, A method for producing a metal oxide catalyst to be subjected to sonication (Patent Document 2) has been proposed.
The metal oxide mixture obtained by the slurry method or hydrothermal synthesis method is converted into a crystal structure having catalytic performance through drying and calcination. The calcination is generally divided into two or more steps. For example, the first stage is treated for 2 to 20 hours in the temperature range of 250 ° C. to 380 ° C. in the presence of oxygen, and the second stage is 500 in the absence of oxygen. Examples thereof include a method in which the treatment is carried out at a temperature range of from 0 to 660 ° C. for 0.5 to 6 hours.
Further, regarding a firing method, a method has been proposed in which an index called a reduction rate is introduced into the second-stage firing process to adjust the firing process in the presence of the first-stage oxygen (Patent Document 3).
特開２００４－３１３９５６号公報Japanese Patent Laid-Open No. 2004-313956 特開２００７－０４４６６８号公報JP 2007-046668 A 特開２００３－１７００４４号公報JP 2003-170044 A
　しかしながら、再現性良く優れた性能を有する金属酸化物触媒を製造するためには、上記焼成工程における１段目、２段目およびそれ以降の焼成において、バラツキを抑えて安定した製造を行うことが重要であるが、途中の焼成状態を把握する簡易な手段がなく、また、特許文献３のようにリアルタイムで焼成状態を監視するという方法では、１時間以上の作業が必要であり、生産効率が悪いという問題がある。
　本発明が解決しようとする課題は、特定な組成式で表される金属酸化物触媒の焼成工程において、簡易な方法で、触媒性能のバラツキを抑制する焼成条件を把握することにより、優れた触媒性能を有する金属酸化物触媒を、再現性良く製造することを目的とする。 However, in order to produce a metal oxide catalyst having excellent performance with good reproducibility, it is necessary to perform stable production while suppressing variations in the first, second and subsequent firings in the firing step. Although it is important, there is no simple means for grasping the firing state in the middle, and the method of monitoring the firing state in real time as in Patent Document 3 requires work for one hour or more, and the production efficiency is high. There is a problem of being bad.
The problem to be solved by the present invention is to obtain an excellent catalyst by grasping the firing conditions for suppressing variation in catalyst performance by a simple method in the firing step of the metal oxide catalyst represented by a specific composition formula. An object is to produce a metal oxide catalyst having performance with good reproducibility.
　上記課題を解決するために、本発明者らは、鋭意検討した結果、特定な組成式の金属酸化物触媒を製造する方法において、焼成を２段階で行い、１段目の焼成で得られる物質が特定な分析値の範囲に含まれていると、触媒性能のバラツキが抑制された金属酸化物触媒が得られることを見出し、本発明を完成するに至った。 In order to solve the above-mentioned problems, the present inventors have intensively studied. As a result, in a method for producing a metal oxide catalyst having a specific composition formula, the material obtained by performing the firing in two stages and the first stage firing. Is included in the range of specific analysis values, it has been found that a metal oxide catalyst in which variation in catalyst performance is suppressed can be obtained, and the present invention has been completed.
　すなわち、本発明の第１発明は、還元剤と水または有機溶剤との存在下で、Ｔｅ４＋化合物またはＴｅ６＋化合物を還元して金属テルルを含む還元物を得る工程、前記還元物から未反応の還元剤を除去する工程、Ｍｏ、Ｖ、Ａ元素および水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させ反応物を得る工程、ならびに、得られた反応物を乾燥および焼成し下記組成式で表される金属酸化物触媒を得る工程を含み、前記焼成を２段階で行い、１段目の焼成で得られる物質が下記分析値Ａおよび下記分析値Ｂのうち少なくとも１つの分析値に含まれる金属酸化物触媒の製造方法である。
組成式：ＭｏＶｉＴｅｊＡｋＯｙ
　式中、Ａは、Ｎｂ、Ｔａ、Ｗ、Ｔｉ、Ｚｒ、Ｒｅ、Ｆｅ、Ｎｉ、Ｃｏ、Ｓｎ、Ｔｌ、Ｃｕ、希土類元素およびアルカリ金属元素よりなる群から選ばれる少なくとも１種の元素であり、ｉおよびｊは、各々０．０１～１．５で、かつｊ／ｉ＝０．３～１．０であり、ｋは０．００１～３．０であり、ｙは他の元素の酸化状態によって決定される数である。
分析値Ａ：下記式１で定義される質量変化率の値が１．２～４．０％である。
質量変化率（％）＝［（加熱前の質量－加熱後の質量）／加熱前の質量］×１００（式１）
分析値Ｂ：燃焼法による炭素、水素および窒素の元素分析における窒素含有量が０．８～１．５質量％である。 That is, the first invention of the present invention is a step of reducing a Te 4+ compound or a Te 6+ compound in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium, unreacted from the reduced product. A step of removing a reducing agent, a step of reacting a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V, A element and water to obtain a reaction product, and Including a step of drying and calcining the reaction product to obtain a metal oxide catalyst represented by the following compositional formula, the calcination is performed in two stages, and substances obtained by the first-stage calcination include the following analytical value A and the following analytical value This is a method for producing a metal oxide catalyst included in at least one analytical value of B.
Composition formula: MoV i Te j A k O y
In the formula, A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements, i and j are each 0.01 to 1.5, and j / i = 0.3 to 1.0, k is 0.001 to 3.0, and y is an oxidation state of another element. Is a number determined by
Analytical value A: The mass change rate defined by the following formula 1 is 1.2 to 4.0%.
Mass change rate (%) = [(mass before heating−mass after heating) / mass before heating] × 100 (formula 1)
Analysis value B: The nitrogen content in the elemental analysis of carbon, hydrogen and nitrogen by the combustion method is 0.8 to 1.5 mass%.
　本発明の第２発明は、前記反応物を得る工程が、Ｍｏ、Ｖおよび水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させ、その後、Ａ元素を含有する化合物と混合して反応させ反応物を得る工程である第１発明に記載の金属酸化物触媒の製造方法である。 In the second invention of the present invention, the step of obtaining the reactant comprises reacting a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V and water, It is a manufacturing method of the metal oxide catalyst as described in 1st invention which is the process of mixing and reacting with the compound to contain, and obtaining a reaction material.
　また、本発明の第３発明は、さらに１段目の焼成で得られる物質が下記分析値Ｃに含まれる第１発明または第２発明に記載の金属酸化物触媒の製造方法である。
分析値Ｃ：試料を硫酸水溶液に分散した溶液を、加熱下で、酸化剤を用いて酸化還元滴定して得られる試料１ｇ当たりの消費される酸素モル数が３．４～５．５ｍｍｏｌである。 The third invention of the present invention is the method for producing a metal oxide catalyst according to the first invention or the second invention, wherein the substance obtained by the first-stage calcination is included in the following analysis value C.
Analytical value C: The number of moles of oxygen consumed per 1 g of the sample obtained by subjecting the solution in which the sample is dispersed in the sulfuric acid aqueous solution to oxidation-reduction titration with heating using an oxidizing agent is 3.4 to 5.5 mmol. .
　本発明の第４発明は、２段目の焼成を、酸素不存在下で、５００℃～６６０℃の温度範囲で行う第１発明～第３発明のいずれか１つに記載の金属酸化物触媒の製造方法である。 The fourth invention of the present invention is the metal oxide catalyst according to any one of the first to third inventions, wherein the second stage calcination is performed in the temperature range of 500 ° C. to 660 ° C. in the absence of oxygen. It is a manufacturing method.
　本発明の第５発明は、第１発明～第４発明のいずれか１つの方法で得られた金属酸化物触媒を用いて、プロパンを気相接触反応により酸化するアクリル酸の製造方法である。 The fifth invention of the present invention is a method for producing acrylic acid in which propane is oxidized by a gas phase catalytic reaction using the metal oxide catalyst obtained by any one of the first to fourth inventions.
　本発明における金属酸化物触媒の製造方法によれば、熱質量分析または元素分析の検査方法により短時間で１段目の焼成状態を把握することができるため、触媒活性のバラツキが少ない高活性な金属酸化物触媒が製造できる。 According to the method for producing a metal oxide catalyst in the present invention, the firing state of the first stage can be grasped in a short time by an inspection method of thermal mass spectrometry or elemental analysis, so that there is little variation in catalyst activity. A metal oxide catalyst can be produced.
１段目の焼成における加熱時間と質量変化率の関係を示すグラフである。It is a graph which shows the relationship between the heating time and mass change rate in the 1st stage baking. １段目の焼成における加熱時間と窒素含有量の関係を示すグラフである。It is a graph which shows the relationship between the heating time in 1st step | paragraph baking, and nitrogen content. １段目の焼成における加熱時間と酸化還元滴定の関係を示すグラフである。It is a graph which shows the relationship between the heating time and oxidation-reduction titration in 1st-stage baking. １段目の焼成条件による触媒性能の相違を示すグラフである。It is a graph which shows the difference in the catalyst performance by the 1st-stage baking conditions.
　以下、本発明について詳細に説明する。
　本発明における金属酸化物触媒は、下記の組成式で表される金属酸化物である。
組成式：ＭｏＶｉＴｅｊＡｋＯｙ
（式中、Ａは、Ｎｂ、Ｔａ、Ｗ、Ｔｉ、Ｚｒ、Ｒｅ、Ｆｅ、Ｎｉ、Ｃｏ、Ｓｎ、Ｔｌ、Ｃｕ、希土類元素およびアルカリ金属元素よりなる群から選ばれる少なくとも１種の元素であり、ｉおよびｊは、各々０．０１～１．５で、かつｊ／ｉ＝０．３～１．０であり、ｋは０．００１～３．０であり、ｙは他の元素の酸化状態によって決定される数である。） Hereinafter, the present invention will be described in detail.
The metal oxide catalyst in the present invention is a metal oxide represented by the following composition formula.
Composition formula: MoV i Te j A k O y
(In the formula, A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements. , I and j are each 0.01 to 1.5 and j / i = 0.3 to 1.0, k is 0.001 to 3.0, and y is the oxidation of other elements (The number is determined by the state.)
　また、上記金属酸化物は、Ｔｅ４＋化合物またはＴｅ６＋化合物（テルルの原子価が４または６である化合物）を水または有機溶剤の存在下に還元剤で還元することにより金属テルルを含む還元物を得た後、この還元物から未反応の還元剤を除去し、次いで、Ｍｏ、Ｖ、Ａ元素および水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させた後、乾燥および焼成して製造する。
　さらに、上記焼成を２段階で行い、１段目の焼成で得られる物質が前記分析値Ａおよび前記分析値Ｂのうち少なくとも１つの分析値に含まれることが必要である。 The metal oxide is a reduced product containing metal tellurium by reducing a Te 4+ compound or a Te 6+ compound (a compound in which the tellurium valence is 4 or 6) with a reducing agent in the presence of water or an organic solvent. Then, the unreacted reducing agent is removed from the reduced product, and then the reduced product containing metal tellurium from which the unreacted reducing agent has been removed is reacted in the presence of Mo, V, A element and water. Then, it is dried and fired to produce.
Furthermore, it is necessary that the calcination is performed in two stages and a substance obtained by the first calcination is included in at least one analysis value of the analysis value A and the analysis value B.
　以下、具体的な製造方法について、工程（１）～（５）に分けて説明する。なお、製造方法に関して、触媒技術分野における公知な技術である加熱処理、共沈、乾燥および焼成を経由する方法や水熱合成を利用する結晶形成などの方法が制限なく使用できる。 Hereinafter, a specific manufacturing method will be described in steps (1) to (5). In addition, regarding the manufacturing method, methods such as heat treatment, coprecipitation, drying and calcination, and crystal formation using hydrothermal synthesis, which are known techniques in the catalyst technical field, can be used without limitation.
工程（１）
　本発明の金属酸化物触媒の製造方法は、還元剤と水または有機溶剤との存在下で、Ｔｅ４＋化合物またはＴｅ６＋化合物を還元して金属テルルを含む還元物を得る工程（工程（１））を含む。
　この工程では、還元剤と水または有機溶剤の存在下で、Ｔｅ４＋化合物またはＴｅ６＋化合物を還元し、触媒の原料成分である金属テルルを含む還元物を得る。
　原料に使用するＴｅ４＋化合物およびＴｅ６＋化合物は特に限定がなく使用可能であり、具体的には、二酸化テルル、三酸化テルル、四塩化テルル、オルトテルル酸、メタテルル酸、ポリメタテルル酸、テルル酸アンモニウム、テルル酸アルカリ金属、テルル酸亜鉛、テルル酸カルシウム、テルル酸銀、テルル酸タリウム、テルル酸銅およびテルル酸マグネシウムなどが挙げられ、これらの中でも二酸化テルルまたはオルトテルル酸が好ましい。 Process (1)
The method for producing a metal oxide catalyst of the present invention is a step of reducing a Te 4+ compound or a Te 6+ compound in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium (step (1)). )including.
In this step, a Te 4+ compound or a Te 6+ compound is reduced in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium as a raw material component of the catalyst.
Te 4+ compound and Te 6+ compound used for the raw material can be used without any particular limitation. Specifically, tellurium dioxide, tellurium trioxide, tellurium tetrachloride, orthotelluric acid, metatelluric acid, polymetatelluric acid, ammonium tellurate, Examples include alkali metal tellurates, zinc tellurates, calcium tellurates, silver tellurates, thallium tellurates, copper tellurates and magnesium tellurates, among which tellurium dioxide or ortho telluric acids are preferred.
　還元剤としては、標準電極に対する酸化還元電位が０．５３Ｖ以下（二酸化テルルの電位は０．５３Ｖ付近）の還元性物質（他の分子に電子を与えやすい性質をもつ原子、分子、イオンである）が使用でき、還元反応の円滑性や水と作用しないことから、ヒドラジン、ヒドラジニウム塩、ヒドロキシルアミン等が好ましい。
　具体的には、ヒドラジン酢酸塩、ヒドラジン二臭化水素酸塩、ヒドラジン二酸化塩、ヒドラジン一塩酸塩、ヒドラジン一水和物、硫酸ヒドラジン、ヒドロキシルアミン、塩化ヒドロキシルアンモニウムおよび硫酸ヒドロキシルアンモニウムなどが挙げられる。 The reducing agent is a reducing substance (atom, molecule, or ion having a property of easily giving electrons to other molecules) having a redox potential of 0.53 V or less (the potential of tellurium dioxide is around 0.53 V) with respect to the standard electrode. Hydrazine, hydrazinium salts, hydroxylamine, and the like are preferable.
Specific examples include hydrazine acetate, hydrazine dihydrobromide, hydrazine dioxide, hydrazine monohydrochloride, hydrazine monohydrate, hydrazine sulfate, hydroxylamine, hydroxylammonium chloride, and hydroxylammonium sulfate.
　還元剤の使用量は、還元剤の種類や反応条件により異なるが、例えば、ヒドラジンを用いる場合、ヒドラジンとテルルのモル比で０．５～４．０が好ましく、１．０～３．０がより好ましい。ヒドラジンの使用量が０．５以上であると、二酸化テルルの残存量が少なく、使用量が４．０以下であると、使用量を増やす利点が十分得られ、未反応ヒドラジンの除去に余分な手間や洗浄液が不要または必要になる量が少なくすむ。ヒドラジン以外の還元剤の場合も同様である。 The amount of reducing agent used varies depending on the type of reducing agent and reaction conditions. For example, when hydrazine is used, the molar ratio of hydrazine to tellurium is preferably 0.5 to 4.0, and 1.0 to 3.0. More preferred. If the amount of hydrazine used is 0.5 or more, the remaining amount of tellurium dioxide is small, and if the amount used is 4.0 or less, the advantage of increasing the amount used is sufficiently obtained, which is extra for the removal of unreacted hydrazine. Reduces the amount of labor and cleaning liquid that is unnecessary or required. The same applies to a reducing agent other than hydrazine.
　還元反応は、水や有機溶剤などの液体中で行い、有機溶剤としてはアルコール類、炭化水素類などが好ましい。液体の存在によりテルル化合物が分散され、還元反応が進行しやすくなるため、得られる金属テルルの粒子が均一になる。 The reduction reaction is carried out in a liquid such as water or an organic solvent. As the organic solvent, alcohols, hydrocarbons and the like are preferable. The presence of the liquid disperses the tellurium compound and facilitates the reduction reaction, so that the metal tellurium particles obtained are uniform.
　テルル化合物の還元条件は、使用するテルル化合物の水または有機溶剤に対する溶解性や還元剤の反応性を考慮して適宜選択できる。例えば、水溶性のテルル酸を原料とし、ヒドラジンを還元剤として用いる場合、テルル酸の水溶液にヒドラジンを添加するだけで還元反応が進行し、金属テルルの粒子が水中に形成される。
　有機溶剤に対する溶解性が乏しいテルル化合物である二酸化テルルを原料にして、ヒドラジンを還元剤に用いる場合は、還元反応の進行速度は遅い。この場合は、時間をかけて撹拌し、加熱することにより反応を促進させる必要がある。具体的には、４０℃～１００℃の温度、１００～５００回／分の撹拌速度で１～２０時間反応させるのが好ましい。 The reduction conditions for the tellurium compound can be appropriately selected in consideration of the solubility of the tellurium compound used in water or an organic solvent and the reactivity of the reducing agent. For example, when water-soluble telluric acid is used as a raw material and hydrazine is used as a reducing agent, the reduction reaction proceeds only by adding hydrazine to an aqueous solution of telluric acid, and metal tellurium particles are formed in water.
When tellurium dioxide, which is a tellurium compound having poor solubility in an organic solvent, is used as a raw material and hydrazine is used as a reducing agent, the reduction reaction proceeds slowly. In this case, it is necessary to promote the reaction by stirring and heating over time. Specifically, the reaction is preferably performed at a temperature of 40 ° C. to 100 ° C. and a stirring speed of 100 to 500 times / minute for 1 to 20 hours.
　また、還元反応を促進させる方法として、加熱、撹拌の代わりに、テルル化合物、還元剤、水または有機溶剤の共存下で湿式粉砕する方法がある。湿式粉砕をすることにより、還元反応と粉砕とが同時に進行し、さらに粒子の金属テルルが得られ、その結果、得られる触媒性能に好ましい影響を与える。
　粉砕する際に使用する有機溶剤としては特に制限はないが、常温で液体であり、且つ後工程で容易に除去できる有機溶剤が好ましく、具体的にはメタノール、エタノール、プロパノールなどのアルコール、ヘキサン、シクロヘキサン、トルエンなどの炭化水素が好ましい。粉砕時において、水や有機溶剤を共存させることにより、粉砕に伴う表面エネルギーの増大が緩和され、粉砕効率が高まる。 Further, as a method for promoting the reduction reaction, there is a method of wet pulverization in the presence of a tellurium compound, a reducing agent, water or an organic solvent instead of heating and stirring. By performing wet pulverization, the reduction reaction and pulverization proceed simultaneously, and metal tellurium particles are obtained, and as a result, the obtained catalyst performance is favorably affected.
The organic solvent used for pulverization is not particularly limited, but is preferably an organic solvent that is liquid at room temperature and can be easily removed in a subsequent process. Specifically, alcohols such as methanol, ethanol, and propanol, hexane, Hydrocarbons such as cyclohexane and toluene are preferred. By coexisting water or an organic solvent at the time of pulverization, an increase in surface energy accompanying pulverization is mitigated, and pulverization efficiency is increased.
　粉砕時のテルル化合物と水または有機溶剤との混合割合は、テルル化合物１００質量部当たり、水または有機溶剤が１０～１，０００質量部であることが好ましく、３０～３００質量部がより好ましい。水または有機溶剤が１０質量部以上であると、粉砕物が粉砕容器に付着することが少なく、粉砕が容易であり、１，０００質量部以下であると、水または有機溶剤が粉砕の際の衝撃を吸収することを抑制し、粉砕効率に優れる。 The mixing ratio of the tellurium compound and water or organic solvent during pulverization is preferably 10 to 1,000 parts by mass of water or organic solvent, more preferably 30 to 300 parts by mass per 100 parts by mass of the tellurium compound. When the water or organic solvent is 10 parts by mass or more, the pulverized product is less likely to adhere to the pulverization container and is easily pulverized. When the water or organic solvent is 1,000 parts by mass or less, the water or the organic solvent is pulverized. Suppresses impact absorption and excels in grinding efficiency.
　粉砕機としては、被粉砕物を収容した容器自体を駆動させて粉砕する形式のものが好ましい。具体的にはボールミル、振動ミルおよび遊星ボールミル等が挙げられる。粉砕時間は０．５～２４時間が好ましい。 The pulverizer is preferably of a type that pulverizes by driving the container itself containing the material to be crushed. Specific examples include a ball mill, a vibration mill, and a planetary ball mill. The grinding time is preferably 0.5 to 24 hours.
　上記の還元反応により得られる金属テルルを含む還元物を乾燥して得られる粉末を粉末Ｘ線回折分析すると、二酸化テルルの結晶相は認められず、純粋な六方晶系金属テルルの結晶相に帰属される。 When the powder obtained by drying the reduction product containing metal tellurium obtained by the above reduction reaction is analyzed by powder X-ray diffraction, no crystal phase of tellurium dioxide is observed, and it belongs to the crystal phase of pure hexagonal metal tellurium. Is done.
　また、上記還元物の乾燥粉末を電子顕微鏡で観察すると、一次粒子の外観は還元方法の違いに応じて球状と針状のものが観察されるが、いずれの一次粒子も粒径分布は非常に狭い。また、観察試料によっては、一次粒子の凝集が見られるものもあるが、これは試料の乾燥時に生じる現象であり、触媒の製造および得られる触媒の性能には影響がない。 In addition, when the dried powder of the reduced product is observed with an electron microscope, the appearance of primary particles is observed to be spherical or needle-like depending on the difference in the reduction method. narrow. In addition, some observation samples show aggregation of primary particles, but this is a phenomenon that occurs when the sample is dried, and does not affect the production of the catalyst and the performance of the obtained catalyst.
　上記還元反応により得られる金属テルルの一次粒子の大きさは、少なくとも一方向で好ましくは４．０μｍ以下、より好ましくは２．０μｍ以下の範囲である。一次粒子の大きさの下限は特にないが、操作のしやすさの観点から１０ｎｍ以上が好ましい。一次粒子の大きさが４．０μｍ以下であると、水または有機溶剤中の金属テルル粒子の分散性に優れる。 The size of the primary particles of metal tellurium obtained by the reduction reaction is preferably 4.0 μm or less, more preferably 2.0 μm or less in at least one direction. There is no particular lower limit on the size of the primary particles, but 10 nm or more is preferable from the viewpoint of ease of operation. When the size of the primary particles is 4.0 μm or less, the dispersibility of the metal tellurium particles in water or an organic solvent is excellent.
工程（２）
　本発明の金属酸化物触媒の製造方法は、前記還元物から未反応の還元剤を除去する工程（工程（２））を含む。
　工程（２）は、工程（１）で得られる金属テルルを含む還元物に残存する未反応の還元剤を除去し、さらに還元反応の媒体に有機溶剤を用いている場合は、その溶剤を水で置き換えて還元物の水性分散液を得る工程であることが好ましい。未反応の還元剤および有機溶剤を除去し、あるいは還元剤および有機溶剤を還元物分散液から減圧下で留去する方法や、遠心分離やろ過操作により還元剤および有機溶剤を分離除去した後、還元物を水に再分散させる方法が例示できる。 Step (2)
The manufacturing method of the metal oxide catalyst of this invention includes the process (process (2)) which removes an unreacted reducing agent from the said reduced material.
In step (2), unreacted reducing agent remaining in the reduced product containing metal tellurium obtained in step (1) is removed, and when an organic solvent is used as the medium for the reduction reaction, the solvent is added to water. It is preferable that the step is a step of obtaining an aqueous dispersion of a reduced product by replacing with. After removing the unreacted reducing agent and the organic solvent, or by removing the reducing agent and the organic solvent from the reductant dispersion under reduced pressure, or separating and removing the reducing agent and the organic solvent by centrifugation or filtration, A method of redispersing the reduced product in water can be exemplified.
　上記の操作により、未反応の還元剤および有機溶剤を除去した金属テルルを含む還元物の水性分散液を得る。置き換えに必要な水量は、還元物分散液に対して体積比で１．０～８．０倍が好ましく、２．０～４．０倍がより好ましい。
　水量が１．０倍以上であると、未反応の還元剤が残存し難く、次の工程で残存する還元剤が還元作用を引き起こすことを抑制できる。 By the above operation, an aqueous dispersion of a reduced product containing metal tellurium from which the unreacted reducing agent and organic solvent have been removed is obtained. The amount of water required for replacement is preferably 1.0 to 8.0 times, more preferably 2.0 to 4.0 times in volume ratio with respect to the reduced product dispersion.
When the amount of water is 1.0 times or more, the unreacted reducing agent hardly remains, and the reducing agent remaining in the next step can be prevented from causing a reducing action.
工程（３）
　本発明の金属酸化物触媒の製造方法は、Ｍｏ、Ｖ、Ａ元素および水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させ反応物を得る工程（工程（３）および工程（４））を含む。
　工程（３）は、上記工程（２）で得られる金属テルルを含む還元物の水性分散液と、Ｍｏ６＋化合物およびＶ５＋化合物とを混合し、４０℃以上の温度で１時間以上反応させる工程である。水性分散液には、操作性を改良するために更に水を加えて希釈しても良い。
　反応温度は４０℃～１００℃であることが好ましく、反応時間は１～１０時間が好ましく、２～５時間であることがより好ましい。 Process (3)
The method for producing a metal oxide catalyst of the present invention comprises a step of obtaining a reactant by reacting a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V, A element and water (step). (3) and step (4)).
Step (3) is a step of mixing an aqueous dispersion of a reduced product containing metal tellurium obtained in Step (2) above, a Mo 6+ compound and a V 5+ compound, and reacting them at a temperature of 40 ° C. or higher for 1 hour or longer. It is. The aqueous dispersion may be further diluted by adding water in order to improve operability.
The reaction temperature is preferably 40 ° C. to 100 ° C., and the reaction time is preferably 1 to 10 hours, more preferably 2 to 5 hours.
　Ｍｏ６＋化合物としては、モリブデン酸アンモニウム、酸化モリブデンおよびモリブデン酸等を例示できる。これらの中でも水溶性である点でモリブデン酸アンモニウムが好ましい。
　また、Ｖ５＋化合物としては、メタバナジン酸アンモニウムおよび五酸化バナジウムなどが好ましい。 Examples of the Mo 6+ compound include ammonium molybdate, molybdenum oxide, and molybdic acid. Among these, ammonium molybdate is preferable because it is water-soluble.
As the V 5+ compound, ammonium metavanadate and vanadium pentoxide are preferable.
　Ｍｏ６＋化合物およびＶ５＋化合物の添加量は、Ｍｏを基準にしてこれに対するＶおよびＴｅの原子比（ｉおよびｊ）が各々０．０１～１．５であり、かつＶに対するＴｅの原子比（ｊ／ｉ）が０．３～１．０である。 The addition amount of the Mo 6+ compound and the V 5+ compound is such that the atomic ratio (i and j) of V and Te to this is 0.01 to 1.5 based on Mo, respectively, and the atomic ratio of Te to V ( j / i) is 0.3 to 1.0.
　Ｍｏ６＋化合物およびＶ５＋化合物と金属Ｔｅの粒子とを水に分散させた状態で加熱することにより、粒径が１００ｎｍ以下のＴｅ粒子が安定に水に分散した濃青色の反応液が得られる。
　加熱温度または加熱時間が上記範囲であると、金属Ｔｅの粒子が過剰反応することを抑制できる。過剰反応の例としては、不溶性の二酸化テルルが生成し、その結果、得られる金属酸化物触媒の性能に影響を与える場合がある。 By heating the Mo 6+ compound and V 5+ compound and metal Te particles dispersed in water, a dark blue reaction liquid in which Te particles having a particle size of 100 nm or less are stably dispersed in water is obtained.
When the heating temperature or the heating time is in the above range, the metal Te particles can be prevented from excessively reacting. An example of an excess reaction is the formation of insoluble tellurium dioxide, which can affect the performance of the resulting metal oxide catalyst.
工程（４）
　工程（４）では、上記工程（３）で得られた反応液と金属元素Ａを含有する化合物（以下、Ａ含有化合物という）とを混合する。Ａ含有化合物は水溶液または水分散液の状態で混合することが好ましい。この混合操作により、反応液中に微細な沈殿が生成する。反応温度に特に制限はないが、室温（１０℃～３５℃）で混合することが好ましい。
　なお、工程（４）は前記工程（３）と同時に行うことが出来る。すなわち、工程（３）において、Ａ含有化合物も同時に存在させることが可能である。 Step (4)
In the step (4), the reaction solution obtained in the step (3) and a compound containing the metal element A (hereinafter referred to as A-containing compound) are mixed. The A-containing compound is preferably mixed in the form of an aqueous solution or an aqueous dispersion. By this mixing operation, fine precipitates are generated in the reaction solution. The reaction temperature is not particularly limited, but it is preferable to mix at room temperature (10 ° C. to 35 ° C.).
The step (4) can be performed simultaneously with the step (3). That is, in the step (3), an A-containing compound can be present at the same time.
　金属元素Ａは、Ｎｂ、Ｔａ、Ｗ、Ｔｉ、Ｚｒ、Ｒｅ、Ｆｅ、Ｎｉ、Ｃｏ、Ｓｎ、Ｔｌ、Ｃｕ、希土類元素およびアルカリ金属元素よりなる群から選ばれる少なくとも１種の元素であり、Ａ含有化合物としては、これらの酸化物、硝酸塩、カルボン酸塩、オキソ酸塩およびシュウ酸塩などが挙げられる。
　Ａ含有化合物が不溶性である場合は水に分散させて混合しても良いが、シュウ酸等を併用することにより水に溶解させることができる。 The metal element A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements, and A Examples of the contained compound include these oxides, nitrates, carboxylates, oxoacid salts, and oxalates.
When the A-containing compound is insoluble, it may be dispersed and mixed in water, but it can be dissolved in water by using oxalic acid or the like in combination.
　Ａ含有化合物の混合量は、得られる金属酸化物触媒中における金属の原子比で、Ｍｏを１としたとき、金属元素Ａが０．００１～３．０である。金属元素Ａの割合が０．００１未満の場合は、得られる触媒の劣化が起こる恐れがあり、３．０を超える場合は触媒の活性が低くなる恐れがある。 The mixing amount of the A-containing compound is the atomic ratio of the metal in the obtained metal oxide catalyst. When Mo is 1, the metal element A is 0.001 to 3.0. When the ratio of the metal element A is less than 0.001, the obtained catalyst may be deteriorated, and when it exceeds 3.0, the activity of the catalyst may be lowered.
　工程（４）において、上記工程（３）で得られた反応液とＡ含有化合物とを混合して沈殿を生成した混合液に、硝酸または硝酸アンモニウムを添加しても良く、得られる金属酸化物触媒の性能向上や物理的強度の向上が期待できる。
硝酸または硝酸アンモニウムの好ましい添加量は、金属Ｔｅに対してモル比で０．７～２．１であることが好ましく、さらに好ましくは０．５～１．７である。
　また、工程（４）において、上記工程（３）で得られた反応液と金属元素Ａを含有する化合物との混合は、１５分以下で行うことが好ましく、１０分以下で行うことがより好ましく、５分以下で行うことが更に好ましく、１分以下で行うことが特に好ましい。上記範囲であると、得られる金属酸化物触媒を用いてプロパンの酸化によりアクリル酸を製造した場合におけるアクリル酸選択性およびアクリル酸収率に優れる。 In the step (4), nitric acid or ammonium nitrate may be added to the mixed solution in which the reaction solution obtained in the step (3) and the A-containing compound are mixed to produce a precipitate, and the resulting metal oxide catalyst Can be expected to improve performance and physical strength.
A preferable addition amount of nitric acid or ammonium nitrate is preferably 0.7 to 2.1, more preferably 0.5 to 1.7 in terms of molar ratio to metal Te.
In the step (4), the mixing of the reaction solution obtained in the step (3) and the compound containing the metal element A is preferably performed in 15 minutes or less, more preferably in 10 minutes or less. It is more preferable to carry out in 5 minutes or less, and it is particularly preferable to carry out in 1 minute or less. Within the above range, the acrylic acid selectivity and acrylic acid yield are excellent when acrylic acid is produced by propane oxidation using the resulting metal oxide catalyst.
工程（５）
　本発明の金属酸化物触媒の製造方法は、得られた反応物を乾燥および焼成し上記組成式で表される金属酸化物触媒を得る工程（工程（５））を含む。
　工程（５）では、上記工程（４）を経由して得られる混合液（スラリー）を蒸発乾固させ、得られた乾固物を乾燥した後、焼成を行うことが好ましい。上記混合液は多量に水を含むが、この水を除去する方法としては、公知の蒸発乾固、噴霧乾燥などが利用できる。
　蒸発乾固させる場合、混合液を単に加熱して水分を蒸発させても良いが、蒸発乾固中に窒素や空気などの不活性ガスを吹き付けることにより効率的に乾固できる。蒸発乾固の温度は、５０℃～１３０℃であることが好ましい。 Process (5)
The method for producing a metal oxide catalyst of the present invention includes a step (step (5)) in which the obtained reactant is dried and calcined to obtain a metal oxide catalyst represented by the above composition formula.
In the step (5), it is preferable that the mixed solution (slurry) obtained through the step (4) is evaporated to dryness, and the dried product obtained is dried and then fired. The above mixed solution contains a large amount of water. As a method for removing this water, known evaporation to dryness, spray drying, and the like can be used.
In the case of evaporating to dryness, the liquid mixture may be simply heated to evaporate the water, but it can be efficiently dried by blowing an inert gas such as nitrogen or air during evaporation to dryness. The temperature for evaporation to dryness is preferably 50 ° C to 130 ° C.
　次に、上記操作によって得られる乾固物を２段階で焼成を行う。１段目の焼成は、回転炉、具体的には、好ましくはバッチ式または連続式のロータリキルンを用いて、酸素存在下で温度２５０℃～３８０℃で行うことが好ましく、さらに好ましくは２８０℃～３３０℃である。焼成時間は５分～２０時間が好ましく、さらに好ましくは１０分～３時間である。
　上記１段目の焼成で得られる物質が、下記分析値Ａおよび下記分析値Ｂのうち少なくとも１つの分析値の範囲に含まれていることが必要である。
　次いで、２段目の焼成条件として、焼成温度が酸素不存在の状態で５００℃～６６０℃であることが好ましく、さらに好ましくは５７０℃～６４０℃である。焼成時間は０．５～６時間であることが好ましく、さらに好ましくは１～３時間である。
　また、２段目の焼成は、マッフル炉により行われることが好ましい。 Next, the dried product obtained by the above operation is fired in two stages. The first stage firing is preferably carried out at a temperature of 250 ° C. to 380 ° C. in the presence of oxygen using a rotary furnace, specifically preferably a batch or continuous rotary kiln, and more preferably 280 ° C. ~ 330 ° C. The firing time is preferably 5 minutes to 20 hours, more preferably 10 minutes to 3 hours.
It is necessary that the substance obtained by the first stage baking is included in the range of at least one of the following analysis values A and B.
Next, as the second stage firing condition, the firing temperature is preferably 500 ° C. to 660 ° C. in the absence of oxygen, and more preferably 570 ° C. to 640 ° C. The firing time is preferably 0.5 to 6 hours, more preferably 1 to 3 hours.
The second stage baking is preferably performed in a muffle furnace.
分析値Ａ（質量変化率）
　下記式１で定義される質量変化率の値が１．２～４．０％である。
質量変化率（％）＝［（加熱前の質量－加熱後の質量）／加熱前の質量］×１００（式１）
　質量変化率の測定方法は、１段目の焼成を終えた試料をサンプリングし、加熱前の質量を測定した後、マッフル炉にて大気下５００℃～６５０℃で１０分～９０分加熱処理を行い、加熱後の質量を測定する。なお、マッフル炉内を窒素置換してからデータを取得できるが、置換時間のロス、炉内置換状態のバラツキが不安材料となるので、必要不可欠ではない。 Analysis value A (mass change rate)
The value of mass change rate defined by the following formula 1 is 1.2 to 4.0%.
Mass change rate (%) = [(mass before heating−mass after heating) / mass before heating] × 100 (formula 1)
The mass change rate is measured by sampling a sample that has been baked in the first stage, measuring the mass before heating, and then subjecting it to a heat treatment at 500 ° C. to 650 ° C. for 10 minutes to 90 minutes in the muffle furnace. And measure the mass after heating. Although data can be acquired after the inside of the muffle furnace is replaced with nitrogen, loss of replacement time and variation in the state of replacement in the furnace are anxious materials, so they are not indispensable.
質量変化率の測定方法の条件について、具体的に説明する。上記工程（１）～工程（５）により得られた混合液の蒸発乾固品について、卓上ロータリーキルン(高砂工業株式会社製)を用いて、３１０℃で３０分の条件で焼成した試料について、加熱温度および加熱時間と、質量変化率の関係を下記表１に示した。
　表１によれば、４２０℃および７００℃の加熱温度では、加熱時間１０分から９０分の間で重量変化率のバラツキがあるが、５００℃から６５０℃の範囲ではほとんどバラツキがなく、加熱時間１０分から９０分の範囲ではほぼ一定であり、大気下５００℃～６５０℃で１０分～９０分加熱処理する条件で質量変化率を測定することが好ましい。 The conditions of the mass change rate measurement method will be specifically described. For the evaporated and dried product of the mixed solution obtained in the above steps (1) to (5), a sample calcined at 310 ° C. for 30 minutes using a tabletop rotary kiln (manufactured by Takasago Industry Co., Ltd.) is heated. The relationship between temperature and heating time and mass change rate is shown in Table 1 below.
According to Table 1, there are variations in the rate of change in weight between heating times of 10 minutes and 90 minutes at heating temperatures of 420 ° C. and 700 ° C., but there is almost no variation in the range of 500 ° C. to 650 ° C. It is almost constant in the range from 90 minutes to 90 minutes, and it is preferable to measure the rate of mass change under conditions of heat treatment at 500 to 650 ° C. for 10 to 90 minutes in the atmosphere.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　次に、質量変化率により、１段目の焼成状態を把握できることについて、１例を挙げて説明する。上記１段目の焼成を、３１０℃で２分～２４０分加熱して得られた物質について、焼成時間と質量変化率との関係を図１に示す。
　図１によれば、焼成時間が長くなるほど焼成状態は進行して、質量変化率は焼成時間に相関して変化することがわかる。 Next, the fact that the firing state of the first stage can be grasped from the mass change rate will be described with an example. FIG. 1 shows the relationship between the firing time and the mass change rate of the substance obtained by heating the first stage baking at 310 ° C. for 2 to 240 minutes.
According to FIG. 1, it can be seen that the firing state progresses as the firing time becomes longer, and the mass change rate changes in correlation with the firing time.
分析値Ｂ（元素分析）
　燃焼法による炭素、水素および窒素の元素分析における窒素含有量が０．８～１．５質量％である。
　元素分析としては、一般的な方法である燃焼法により、炭素、水素および窒素の元素分析を行う。上記分析値Ａと同様な試料を用いて、卓上ロータリーキルン(高砂工業株式会社製)により、３１０℃で焼成した場合の焼成時間(２分～２４０分)と元素分析による窒素含有量との関係を図２に示す。
　図２によれば、焼成時間が長くなるほど焼成状態は進行して、窒素含有量は焼成時間に相関して変化することがわかる。 Analysis value B (elemental analysis)
The nitrogen content in the elemental analysis of carbon, hydrogen and nitrogen by the combustion method is 0.8 to 1.5% by mass.
As elemental analysis, elemental analysis of carbon, hydrogen and nitrogen is performed by a combustion method which is a general method. Using a sample similar to the above analysis value A, the relationship between the baking time (2 to 240 minutes) and the nitrogen content by elemental analysis when baking at 310 ° C. with a tabletop rotary kiln (manufactured by Takasago Industry Co., Ltd.) As shown in FIG.
According to FIG. 2, it can be seen that the firing state proceeds as the firing time becomes longer, and the nitrogen content changes in correlation with the firing time.
　さらに、１段目の焼成で得られる物質が、下記分析値Ｃの範囲に含まれることが好ましい。
分析値Ｃ
　試料を硫酸水溶液に分散した溶液を加熱下で、酸化剤を用いて酸化還元滴定して得られる試料１ｇ当たりの消費される酸素モル数が３．４～５．５ｍｍｏｌである。 Furthermore, it is preferable that the substance obtained by the first stage baking is included in the range of the analytical value C below.
Analysis value C
The number of moles of oxygen consumed per 1 g of the sample obtained by oxidation-reduction titration with an oxidizing agent under heating of a solution in which the sample is dispersed in an aqueous sulfuric acid solution is 3.4 to 5.5 mmol.
　酸化還元滴定は、硫酸水溶液に１段目の焼成を終えた試料を加えた分散液を４０～９０℃、好ましくは５０～７０℃で分析する。還元剤は特に限定しないが市販のＮ／４０の過マンガン酸カリウム水溶液が好ましい。
　上記分析値Ａと同様な試料を用いて、卓上ロータリーキルン(高砂工業株式会社製)を用いて３１０℃で焼成した場合の焼成時間(２分～９０分)と１段目焼成品の酸化還元滴定量との関係を図３に示す。
　図３によれば、各試料の酸化還元滴定量は、焼成時間に相関して変化することがわかる。 In the oxidation-reduction titration, a dispersion obtained by adding a sample after the first stage baking to an aqueous sulfuric acid solution is analyzed at 40 to 90 ° C., preferably 50 to 70 ° C. Although the reducing agent is not particularly limited, a commercially available N / 40 potassium permanganate aqueous solution is preferable.
Using a sample similar to the above analysis value A, firing time (2 to 90 minutes) when firing at 310 ° C. using a tabletop rotary kiln (manufactured by Takasago Industry Co., Ltd.) and redox titration of the first-stage fired product The relationship with the quantity is shown in FIG.
According to FIG. 3, it can be seen that the redox titer of each sample changes in correlation with the firing time.
　また、図４に、各種の条件で行った１段目の焼成物を、同一の条件で２段目の焼成を行い製造した金属酸化物触媒の性能を調べた結果を示す。横軸にプロパン転化率、縦軸にアクリル酸選択性を示し、アクリル酸収率を破線で示す。
　図４に示すように、触媒性能のカーブはアクリル酸収率の極大点を持っており、１段目の焼成状態が大きく影響する。そのため、触媒性能のバラツキが少なくするためには、１段目の焼成状態を把握することが重要である。 FIG. 4 shows the results of investigating the performance of the metal oxide catalyst produced by firing the second-stage calcined product under various conditions under the same conditions. The horizontal axis indicates the propane conversion, the vertical axis indicates the acrylic acid selectivity, and the acrylic acid yield is indicated by a broken line.
As shown in FIG. 4, the curve of the catalyst performance has a maximum point of the acrylic acid yield, and the first stage calcination state greatly affects. Therefore, in order to reduce variation in catalyst performance, it is important to grasp the first stage firing state.
　前記のとおり、質量変化率、窒素含有量および酸化還元滴定の分析値は、１段目の焼成状態と相関して変化するため、１段目の焼成物を上記分析方法で分析することで１段目の焼成状態を判別することが可能である。 As described above, the mass change rate, the nitrogen content, and the redox titration analysis values change in correlation with the firing state of the first stage. Therefore, the first stage firing product is analyzed by the above analysis method. It is possible to determine the firing state of the stage.
　さらに、１段目焼成で得られた試料を用いて、酸素不存在下で２段目の焼成を行う。焼成装置としてはマッフル炉やロータリーキルン等が挙げられるがこれらに限定するものではない。
　２段目の焼成温度は５００℃～６６０℃が好ましく、さらに好ましくは５７０℃～６４０℃であり、焼成時間は、０．５～６時間であることが好ましく、１～３時間であることがより好ましい。 Further, using the sample obtained by the first stage baking, the second stage baking is performed in the absence of oxygen. Examples of the baking apparatus include, but are not limited to, a muffle furnace and a rotary kiln.
The second stage baking temperature is preferably 500 ° C. to 660 ° C., more preferably 570 ° C. to 640 ° C., and the baking time is preferably 0.5 to 6 hours, and preferably 1 to 3 hours. More preferred.
　上記工程（１）～（５）により得られる金属酸化物触媒は、そのままの形態で使用できるが、適当な粒度に粉砕して触媒の表面積を増大させて使用することが好ましい。粉砕方法としては、公知の乾式粉砕法および湿式粉砕法などが利用できる。
　粉砕装置の具体例としては、乳鉢、ボールミル等が挙げられる。湿式粉砕の場合に、粉砕の助剤として使用する溶媒としては、水、アルコール類などが挙げられる。本触媒を粉砕する場合、その粒度は、２０μｍ以下とすることが好ましく、５μｍ以下がより好ましい。
　金属酸化物触媒は、無担体の状態でも使用できるが、適当な粒度を有するシリカ、アルミナ、シリカアルミナ、シリコンカーバイド等の公知の担体に担持させて使用することもできる。担持量も特に制限が無く、従来の担持量に準じる。 The metal oxide catalyst obtained by the above steps (1) to (5) can be used as it is, but it is preferable to use it by pulverizing to an appropriate particle size to increase the surface area of the catalyst. As the pulverization method, a known dry pulverization method and wet pulverization method can be used.
Specific examples of the pulverizer include a mortar and a ball mill. In the case of wet grinding, examples of the solvent used as a grinding aid include water and alcohols. When the catalyst is pulverized, the particle size is preferably 20 μm or less, more preferably 5 μm or less.
The metal oxide catalyst can be used without a carrier, but can also be used by being supported on a known carrier such as silica, alumina, silica alumina, silicon carbide or the like having an appropriate particle size. The carrying amount is not particularly limited and conforms to the conventional carrying amount.
　上記方法により製造した金属酸化物触媒を用いて、アクリル酸を製造するプロパンの気相接触酸化の方法について説明する。
　金属酸化物触媒を充填した反応器に、原料であるプロパンおよび酸素ガスを導入することで、プロパンは金属酸化物触媒により気相接触酸化されてアクリル酸が生成する。
　プロパンおよび酸素ガスは、別々に反応器に導入して反応器内で両者を混合してもよく、また、予め両者を混合した状態で反応器に導入してもよい。 A method of vapor phase catalytic oxidation of propane for producing acrylic acid using the metal oxide catalyst produced by the above method will be described.
By introducing propane and oxygen gas as raw materials into the reactor filled with the metal oxide catalyst, propane is vapor-phase contact oxidized by the metal oxide catalyst to generate acrylic acid.
Propane and oxygen gas may be separately introduced into the reactor and mixed in the reactor, or may be introduced into the reactor in a state where both are mixed beforehand.
　酸素ガスとしては、純酸素ガスおよび空気、これらを窒素、スチームおよび炭酸ガス等で希釈したガスが例示できる。
　原料としてプロパンおよび空気を使用する場合、空気のプロパンに対する使用割合は、容積比率で３０倍以下が好ましく、０．２～２０倍がより好ましい。 Examples of the oxygen gas include pure oxygen gas and air, and gas obtained by diluting these with nitrogen, steam, carbon dioxide gas, or the like.
When propane and air are used as raw materials, the use ratio of air to propane is preferably 30 times or less in volume ratio, more preferably 0.2 to 20 times.
　反応温度は３００℃～６００℃であることが好ましく、３５０℃～５００℃がより好ましい。
　原料ガスの空間速度（以下ＳＶという）は１，０００～８，０００ｈｒ－１が適当である。空間速度が１，０００ｈｒ－１以上であると、目的化合物であるアクリル酸の収率が向上し、８，０００ｈｒ－１以下であると、反応率が向上する。 The reaction temperature is preferably 300 ° C. to 600 ° C., more preferably 350 ° C. to 500 ° C.
The space velocity (hereinafter referred to as SV) of the source gas is suitably 1,000 to 8,000 hr −1 . When the space velocity is at 1,000 hr -1 or more, to improve the yield of acrylic acid as the target compound, if it is 8,000Hr -1 or less, to improve the reaction rate.
　反応器出口から排出される反応ガス中に存在する未反応の原料プロパンや、中間生成物のプロピレンはそのまま燃料とすることもできるが、反応ガス中の他の成分と分離してから反応器へ返送して再利用することもできる。
　なお、本発明により製造される金属酸化物触媒は、プロパンのアンモ酸化にも適用でき、高収率でアクリロニトリルを製造することができる。アンモ酸化条件は、上記プロパンの気相接触酸化の条件に準じる。 Unreacted raw propane present in the reaction gas discharged from the reactor outlet and propylene as an intermediate product can be used as fuel as they are, but they are separated from other components in the reaction gas before being sent to the reactor. It can be returned and reused.
The metal oxide catalyst produced according to the present invention can also be applied to propane ammoxidation, and acrylonitrile can be produced in high yield. The ammoxidation conditions are the same as those for the above-mentioned vapor-phase catalytic oxidation of propane.
　以下、実施例、試験例および参考例を挙げて、本発明をさらに具体的に説明する。
実施例、試験例および参考例において、得られる金属酸化物触媒を構成する各金属の割合が以下の値となるように、各原料を配合した。
Ｍｏ／Ｖ／Ｔｅ／Ｎｂ＝１．０／０．２５／０．１３／０．１２（モル比） Hereinafter, the present invention will be described more specifically with reference to examples, test examples, and reference examples.
In Examples, Test Examples, and Reference Examples, each raw material was blended so that the ratio of each metal constituting the obtained metal oxide catalyst was the following value.
Mo / V / Te / Nb = 1.0 / 0.25 / 0.13 / 0.12 (molar ratio)
　各例におけるアクリル酸の製造試験は以下のとおりに実施した。
　各例で得られた金属酸化物触媒１．１ｍｌ（１．０ｇ）を１０ｍｍφの石英製の反応管に充填し、反応管を４００℃に加熱し、反応管内にプロパン６．４容積％、酸素９．６容積％、窒素３６．１容積％および水蒸気４７．７容積％の混合ガスを３，９２４／ｈｒ－１の空間速度で供給することにより、アクリル酸を製造した。
　反応生成物中の各生成成分の組成分析を行い、組成分析結果により、下式に示すプロパン転化率、アクリル酸選択性およびアクリル酸収率をモル基準で算出し、金属酸化物触媒の性能評価を表２～表５に記載した。
プロパン転化率（％）＝［（供給プロパン－未反応プロパン）／供給プロパン］×１００（式２）
アクリル酸選択性（％）＝［生成アクリル酸／（供給プロパン－未反応プロパン）］×１００（式３）
アクリル酸収率（％）＝（プロパン転化率×アクリル酸選択性）／１００（式４） The production test of acrylic acid in each example was performed as follows.
1.1 ml (1.0 g) of the metal oxide catalyst obtained in each example was filled in a 10 mmφ quartz reaction tube, the reaction tube was heated to 400 ° C., 6.4 vol% propane, oxygen Acrylic acid was produced by feeding a mixed gas of 9.6 vol%, nitrogen 36.1 vol% and water vapor 47.7 vol% at a space velocity of 3,924 / hr- 1 .
Perform composition analysis of each product component in the reaction product, and calculate the propane conversion, acrylic acid selectivity and acrylic acid yield shown in the following formula on a molar basis, and evaluate the performance of the metal oxide catalyst. Are listed in Tables 2-5.
Propane conversion (%) = [(feed propane-unreacted propane) / feed propane] × 100 (formula 2)
Acrylic acid selectivity (%) = [produced acrylic acid / (feed propane-unreacted propane)] × 100 (formula 3)
Acrylic acid yield (%) = (propane conversion × acrylic acid selectivity) / 100 (formula 4)
＜試験例１＞
　５００ｍｌのガラス製フラスコに、二酸化テルル３．６４ｇおよび蒸留水６０ｍｌ を加え、８０℃で３００回転／分の速度で撹拌しながら、ヒドラジン一水和物（ヒドラジンとして８０質量％）２．８ｇを添加し、この条件で１２時間維持した。時間経過に伴い最初の白色粉末は灰色を経て、最終的に黒色の懸濁物に変化し、その分散液が得られた。
　濾紙を用いて、得られた分散液を黒色の固形物と透明無色の濾液とに濾別した。濾紙の上の固形物を２００ｍｌの蒸留水で洗浄した。蒸留水が濾紙を通過した後、濾紙に残っている固形物を蒸留水で薄めながら、サンプル瓶に集め、テルルの水性分散液を得た。
　５００ｍｌのガラス製フラスコに、メタバナジン酸アンモニウム５．１２ｇ、モリブデン酸アンモニウム３０．９ｇ、および蒸留水１００ｍｌを加え、水の沸点温度下、撹拌しながら溶解させた。 <Test Example 1>
To a 500 ml glass flask, add 3.64 g of tellurium dioxide and 60 ml of distilled water, and add 2.8 g of hydrazine monohydrate (80% by mass as hydrazine) while stirring at a rate of 300 rpm at 80 ° C. And maintained under these conditions for 12 hours. With the passage of time, the first white powder turned gray and finally turned into a black suspension, and its dispersion was obtained.
Using the filter paper, the obtained dispersion was separated into a black solid and a transparent colorless filtrate. The solid on the filter paper was washed with 200 ml of distilled water. After distilled water passed through the filter paper, the solid matter remaining on the filter paper was collected in a sample bottle while being diluted with distilled water to obtain an aqueous dispersion of tellurium.
To a 500 ml glass flask, 5.12 g of ammonium metavanadate, 30.9 g of ammonium molybdate, and 100 ml of distilled water were added and dissolved under stirring at the boiling point of water.
　得られた溶液に前記の金属テルルの水性分散液を加え、１時間加熱処理した後、氷水で３０℃に冷却した。
　一方、蓚酸８．８２ｇおよびニオブ酸３．４８ｇを１４０ｍｌの蒸留水に溶解して常温の水溶液を調製した。この水溶液を前記反応液に１０秒かけて添加した。
　得られた混合液を１０分間激しく撹拌した後、この混合液に硝酸アンモニウム５．０ｇを混合した。その後、加熱濃縮し、さらに１２０℃で蒸発乾固させた。
　得られた蒸留乾固品を、バッチ式ロータリーキルン（装置名：デスクトップ型ロータリーキルン、高砂工業株式会社製）を用いて、大気下で、３１０℃で１５分間焼成を行った。
　得られた試料１．０ｇをルツボに秤量し、工程検査用の小型マッフル炉（装置名：ガス置換マッフル炉、アズワン株式会社製）にて、大気下、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却して、再度秤量した。重量変化率は前記式１で計算して４．６％であった。 The metal tellurium aqueous dispersion was added to the resulting solution, heat-treated for 1 hour, and then cooled to 30 ° C. with ice water.
On the other hand, 8.82 g of oxalic acid and 3.48 g of niobic acid were dissolved in 140 ml of distilled water to prepare a room temperature aqueous solution. This aqueous solution was added to the reaction solution over 10 seconds.
The resulting mixture was vigorously stirred for 10 minutes, and then 5.0 g of ammonium nitrate was mixed with this mixture. Thereafter, the mixture was concentrated by heating and further evaporated to dryness at 120 ° C.
The obtained distilled and dried product was fired at 310 ° C. for 15 minutes in the air using a batch type rotary kiln (device name: desktop rotary kiln, manufactured by Takasago Industrial Co., Ltd.).
1.0 g of the obtained sample was weighed in a crucible, heated in a small muffle furnace for process inspection (device name: gas replacement muffle furnace, manufactured by AS ONE Corporation) at 600 ° C. for 10 minutes in the atmosphere, and then desiccator The sample was cooled to 100 ° C. or less and weighed again. The rate of change in weight was 4.6% as calculated by Equation 1 above.
　２段目の焼成は、マッフル炉において窒素ガスを流通させた不活性雰囲気中６００℃で２時間行い、金属酸化物触媒を得た。
　この触媒の成分の原子比は、蛍光Ｘ線分析による組成分析により、Ｍｏ／Ｖ／Ｔｅ／Ｎｂ＝１．０／０．２５／０．１３／０．１２（モル比）であった。
　得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用し、結果は表２に示したとおり、プロパン転化率６９％、アクリル酸選択性６４％、アクリル酸収率４４％であり、図４に示すように、もう少し長く１段目の焼成を行うとアクリル酸選択性が向上すると予想される。 The second stage calcination was performed in an inert atmosphere in which nitrogen gas was circulated in a muffle furnace at 600 ° C. for 2 hours to obtain a metal oxide catalyst.
The atomic ratio of the components of this catalyst was Mo / V / Te / Nb = 1.0 / 0.25 / 0.13 / 0.12 (molar ratio) by composition analysis by fluorescent X-ray analysis.
The obtained catalyst was tableted and the molded product was pulverized to 16-30 mesh and used for the acrylic acid production reaction. As shown in Table 2, the propane conversion was 69% and acrylic acid selectivity was obtained. As shown in FIG. 4, it is expected that acrylic acid selectivity is improved when the first stage baking is performed a little longer, as shown in FIG.
＜実施例１＞
　試験例１で取得した蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下で、３１０℃で９０分間焼成し、得られた試料１．０ｇをルツボに秤量し、試験例１と同じ工程検査用の小型マッフル炉にて、大気下、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却し再度秤量した結果、重量変化率は２．１％であった。
　２段目の焼成を試験例１と同様に行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率６０％、アクリル酸選択性７３％、アクリル酸収率４４％であった。
　１段目の焼成が適正な範囲であり、試験例１に比べてアクリル酸選択性が向上していることを確認できた。 <Example 1>
The evaporated and dried product obtained in Test Example 1 was baked at 310 ° C. for 90 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process as Test Example 1 After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace for inspection, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 2.1%.
The second stage calcination was performed in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 60 %, Acrylic acid selectivity was 73%, and acrylic acid yield was 44%.
It was confirmed that the first stage baking was in an appropriate range and the acrylic acid selectivity was improved as compared with Test Example 1.
＜試験例２＞
　試験例１で取得した蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下で、３３０℃で９０分間焼成し、得られた試料１．０ｇをルツボに秤量し、試験例１と同じ工程検査用の小型マッフル炉にて、大気下、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却して、再度秤量した結果、重量変化率は１．１％であった。
　２段目の焼成を試験例１と同様に行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率４０％、アクリル酸選択性７４％、アクリル酸収率３０％であった。
　図４に示すとおり、１段目の焼成が適正な範囲を外れ過剰焼成の領域に入ったので、プロパン転化率が低下した。この影響でアクリル酸収率が下がった。 <Test Example 2>
The evaporated and dried product obtained in Test Example 1 was baked at 330 ° C. for 90 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process as Test Example 1 After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace for inspection, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.1%.
The second stage calcination was carried out in the same manner as in Test Example 1, and the resulting catalyst was subjected to tableting, and the molded product was pulverized to 16-30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 40 %, Acrylic acid selectivity was 74%, and acrylic acid yield was 30%.
As shown in FIG. 4, since the first stage calcination was outside the proper range and entered the overcalcination region, the propane conversion decreased. This effect lowered the acrylic acid yield.
＜実施例２＞
　試験例１で取得した蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下、３３０℃で６０分間焼成し、得られた試料１．０ｇをルツボに秤量し、試験例１と同じ工程検査用の小型マッフル炉にて、大気下で、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却して、再度秤量した結果、重量変化率は１．９％であった。
　２段目の焼成を試験例１と同様に行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率６１％、アクリル酸選択性７３％、アクリル酸収率４４％であった。
　試験例２と比較して、１段目の焼成が適正な範囲に入るように加熱時間を短くしたので、プロパン転化率は６０％に上昇した。 <Example 2>
The evaporated and dried product obtained in Test Example 1 was baked at 330 ° C. for 60 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating at 600 ° C. for 10 minutes in the air in a small muffle furnace, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.9%.
The second stage calcination was carried out in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16-30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 61 %, Acrylic acid selectivity was 73%, and acrylic acid yield was 44%.
Compared with Test Example 2, the heating time was shortened so that the first stage firing was in an appropriate range, so the propane conversion increased to 60%.
＜試験例３＞
　試験例１で取得した蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下、３５０℃で６０分間焼成し、得られた試料１．０ｇをルツボに秤量し、試験例１と同じ工程検査用の小型マッフル炉にて、大気下、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却して、再度秤量した結果、重量変化率は０．７％であった。
　２段目の焼成を試験例１と同様に行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率１３％、アクリル酸選択性６２％、アクリル酸収率８％であった。
　図４に示すように、１段目の焼成が適正な範囲を外れ、焼成過剰の領域に入ったので、これがプロパン転化率に影響してアクリル酸収率が下がった。 <Test Example 3>
The evaporated and dried product obtained in Test Example 1 was baked at 350 ° C. for 60 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating at 600 ° C. for 10 minutes in the air in a small muffle furnace for use, cooling to 100 ° C. or lower in a desiccator and weighing again, the weight change rate was 0.7%.
The second stage calcination was carried out in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 13 %, Acrylic acid selectivity 62%, and acrylic acid yield 8%.
As shown in FIG. 4, the first stage of calcination was outside the proper range and entered the region where the calcination was excessive. This affected the propane conversion, and the acrylic acid yield was lowered.
＜実施例３＞
　試験例１で取得した蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下、３５０℃で３０分間焼成し、得られた試料１．０ｇをルツボに秤量し、試験例１と同じ工程検査用の小型マッフル炉にて、大気下、６００℃で１０分間加熱した後、デシケータ内で１００℃以下に冷却して、再度秤量した結果、重量変化率は１．４％であった。
　２段目の焼成を試験例１と同様に行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用したところ、プロパン転化率６１％、アクリル酸選択性７０％、アクリル酸収率４２％であった。
　試験例３の結果より、１段目の焼成が適正な範囲に入るように時間を短くしたので、プロパン転化率は６１％まで回復した。 <Example 3>
The evaporated and dried product obtained in Test Example 1 was baked at 350 ° C. for 30 minutes in the air using a batch rotary kiln, and 1.0 g of the obtained sample was weighed in a crucible, and the same process inspection as Test Example 1 was performed. After heating for 10 minutes at 600 ° C. in the air in a small muffle furnace, the sample was cooled to 100 ° C. or lower in a desiccator and weighed again. As a result, the weight change rate was 1.4%.
The second stage calcination was performed in the same manner as in Test Example 1, and the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used for the acrylic acid production reaction. %, Acrylic acid selectivity was 70%, and acrylic acid yield was 42%.
From the result of Test Example 3, since the time was shortened so that the first stage firing was in an appropriate range, the propane conversion was recovered to 61%.
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
＜試験例４＞
　試験例１と同様な蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下、３１０℃で１５分間焼成した。得られた試料を元素分析装置にて、窒素含有量を測定した結果、１．６質量％であった。
　次に、試験例１と同じ条件で２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０ メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率６９％、アクリル酸選択性６４％、アクリル酸収率４４％であった。 <Test Example 4>
The same evaporated and dried product as in Test Example 1 was baked at 310 ° C. for 15 minutes in the air using a batch rotary kiln. As a result of measuring the nitrogen content of the obtained sample with an elemental analyzer, it was 1.6% by mass.
Next, the second calcination was performed under the same conditions as in Test Example 1, the obtained catalyst was tableted, the molded product was pulverized to 16-30 mesh, and used in the acrylic acid production reaction. The propane conversion was 69%, the acrylic acid selectivity was 64%, and the acrylic acid yield was 44%.
＜実施例４～６、試験例５＞
　試験例４に比較して、１段目の焼成時間を表３に記載の時間に変更した。
　焼成時間を３０分間とした実施例４は、窒素含有量は１．２質量％であり、試験例１と同じ条件で２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率６６％、アクリル酸選択性７１％、アクリル酸収率４７％であり、触媒性能を改善できた。
　実施例５は焼成時間を６０分間に、実施例６は焼成時間を１２０分間にした以外は実施例４と同様に焼成を行った結果、窒素含有量はそれぞれ０．９質量％、０．８質量％であり、実施例４と同様にアクリル酸の製造反応に使用したところ、表３に記載のとおり高いアクリル酸選択性を示した。
　一方、１段目の焼成時間を２４０分間にした試験例５は、窒素含有量が０．７質量％であり、アクリル酸の製造反応に使用したところ、アクリル酸収率が４０％より低かった。 <Examples 4 to 6, Test Example 5>
Compared to Test Example 4, the first stage baking time was changed to the time shown in Table 3.
In Example 4 where the firing time was 30 minutes, the nitrogen content was 1.2% by mass, the second stage of firing was performed under the same conditions as in Test Example 1, and the resulting catalyst was tableted and molded. As a result of pulverizing the product to 16-30 mesh and using it for the production reaction of acrylic acid, the propane conversion was 66%, the acrylic acid selectivity was 71%, and the acrylic acid yield was 47%, and the catalyst performance could be improved.
Example 5 was fired in the same manner as in Example 4 except that the firing time was 60 minutes, and Example 6 was fired for 120 minutes. As a result, the nitrogen content was 0.9% by mass and 0.8%, respectively. When used for the production reaction of acrylic acid in the same manner as in Example 4, it showed high acrylic acid selectivity as shown in Table 3.
On the other hand, in Test Example 5 in which the first stage baking time was 240 minutes, the nitrogen content was 0.7% by mass, and the acrylic acid yield was lower than 40% when used for the production reaction of acrylic acid. .
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
＜比較参考例１＞
　試験例１と同じ蒸発乾固品を、バッチ式ロータリーキルンを用いて、大気下、３１０℃で５分間焼成し、得られた試料０．４ｇをスパーテルで粗粉砕した後、６０℃に加熱した７８％硫酸水／純水＝１０／５０の入ったビーカーに加え、マグネティックスターラーで均一に分散した。加熱を継続しながら、酸化還元滴定装置（装置名：電位差自動滴定装置ＡＴ－５１０、京都電子工業株式会社製）で、還元剤として１／４０規定の過マンガン酸カリウム水溶液を用いて、当量点に達するまでの滴定量を求めたところ、３９ｍｌ（酸素モル数換算：６．１ｍｍｏｌ／試料１ｇ）であった。
試験例１と同様に２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、表４に示すように、プロパン転化率４５％、アクリル酸選択性４５％、アクリル酸収率２０％であった。 <Comparative Reference Example 1>
The same evaporated and dried product as in Test Example 1 was calcined in the atmosphere at 310 ° C. for 5 minutes using a batch rotary kiln, and 0.4 g of the obtained sample was coarsely pulverized with a spatula and then heated to 60 ° C. 78 In addition to a beaker containing% sulfuric acid / pure water = 10/50, the mixture was uniformly dispersed with a magnetic stirrer. While continuing the heating, using an oxidation-reduction titrator (device name: automatic potentiometric titrator AT-510, manufactured by Kyoto Denshi Kogyo Co., Ltd.), using a 1/40 normal potassium permanganate aqueous solution as the reducing agent, the equivalence point The titration amount until reaching the value of 39 was 39 ml (in terms of molar number of oxygen: 6.1 mmol / sample 1 g).
As in Test Example 1, the second stage of calcination was performed, the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. Thus, propane conversion was 45%, acrylic acid selectivity was 45%, and acrylic acid yield was 20%.
＜参考例１＞
　比較参考例１に対して、１段目の焼成時間を９０分間にした結果、酸化還元滴定量は２２ｍｌ（酸素モル数換算：３．４ｍｍｏｌ／試料１ｇ）であった。試験例１と同様に２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、表４に示すとおり、プロパン転化率６０％、アクリル酸選択性７３％、アクリル酸収率４４％であった。 <Reference Example 1>
As a result of setting the first stage baking time to 90 minutes with respect to Comparative Reference Example 1, the redox titer was 22 ml (in terms of molar number of oxygen: 3.4 mmol / sample 1 g). As in Test Example 1, the second stage of calcination was performed, the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. As shown, the propane conversion was 60%, the acrylic acid selectivity was 73%, and the acrylic acid yield was 44%.
＜参考例２、３、比較参考例２、３＞
　比較参考例１に対して、参考例２は１段目の焼成を３３０℃で６０分間行い、参考例３は３５０℃で３０分間行った結果、酸化還元滴定量はそれぞれ２３ｍｌ（酸素モル数換算：３．６ｍｍｏｌ／試料１ｇ）、３１ｍｌ（酸素モル数換算：４．８ｍｍｏｌ／試料１ｇ）であった。
　試験例１と同様に２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、表４に示すとおりであった。 <Reference Examples 2 and 3, Comparative Reference Examples 2 and 3>
Compared to Comparative Reference Example 1, Reference Example 2 performed the first stage firing at 330 ° C. for 60 minutes, and Reference Example 3 performed 30 minutes at 350 ° C. As a result, the redox titer was 23 ml (in terms of moles of oxygen). : 3.6 mmol / sample 1 g) and 31 ml (in terms of moles of oxygen: 4.8 mmol / sample 1 g).
As in Test Example 1, the second stage of calcination was performed, the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. It was as follows.
　また、比較参考例１に対して、１段目の焼成を３３０℃で９０分間（比較参考例３）および３５０℃で６０分間（比較参考例４）行った結果、酸化還元滴定量はそれぞれ２１ｍｌ（酸素モル数換算：３．３ｍｍｏｌ／試料１ｇ）、１８ｍｌ（酸素モル数換算：２．８ｍｍｏｌ／試料１ｇ）であった。
　試験例１と同様に２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、表４に示すとおりであった。 Further, as a result of performing the first stage baking at 330 ° C. for 90 minutes (Comparative Reference Example 3) and at 350 ° C. for 60 minutes (Comparative Reference Example 4) with respect to Comparative Reference Example 1, the redox titer was 21 ml each. (Mole oxygen conversion: 3.3 mmol / sample 1 g) and 18 ml (oxygen mole conversion: 2.8 mmol / sample 1 g).
As in Test Example 1, the second stage of calcination was performed, the obtained catalyst was tableted and molded, and the molded product was pulverized to 16 to 30 mesh and used in the acrylic acid production reaction. It was as follows.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　上記の各例では、１段目の焼成状態の調整について、焼成温度と焼成時間を変更したが、次に、焼成装置内の通気量を変更した実施例を記載する。 In each of the above examples, the firing temperature and the firing time were changed for the adjustment of the first stage firing state. Next, examples in which the air flow rate in the firing apparatus was changed will be described.
＜比較例５＞
　試験例１と同じ蒸発乾固品を、卓上ロータリーキルンを用いて、大気下、３１０℃で９０分間焼成する条件において、炉内にＳＶ＝６９２の大気を吹き込んだ。得られた試料の質量変化率と酸化還元滴定を行ったところ、重量変化率は１．２％、酸化還元滴定量は２０ｍｌ（酸素モル数換算：３．１ｍｍｏｌ／試料１ｇ）であった。
　試験例１と同様に２段目の焼成を行い、得られた触媒を打錠成形し、成型物を１６～３０メッシュに粉砕して、アクリル酸の製造反応に使用した結果、プロパン転化率３３％、アクリル酸選択性７６％、アクリル酸収率２５％であった。 <Comparative Example 5>
Under the condition that the same evaporated and dried product as in Test Example 1 was baked at 310 ° C. for 90 minutes in the atmosphere using a tabletop rotary kiln, the atmosphere of SV = 692 was blown into the furnace. When the mass change rate and oxidation-reduction titration of the obtained sample were performed, the weight change rate was 1.2% and the oxidation-reduction titration amount was 20 ml (in terms of moles of oxygen: 3.1 mmol / sample 1 g).
As in Test Example 1, the second stage of calcination was performed, the resulting catalyst was tableted, and the molded product was pulverized to 16-30 mesh and used in the acrylic acid production reaction. As a result, the propane conversion was 33 %, Acrylic acid selectivity was 76%, and acrylic acid yield was 25%.
＜実施例７、８＞
　比較例５の重量変化率と酸化還元滴定量より、１段目の焼成が過剰に行われていたので、焼成温度と焼成時間は変えないで、実施例７は通気量をＳＶ＝３０に、実施例８は通気量をＳＶ＝３１４に変更した結果、重量変化率と酸化還元滴定量は適正な範囲となり、触媒性能は、アクリル酸収率が４０％台に回復しており、通気量による焼成状態の改善を確認できた。 <Examples 7 and 8>
From the weight change rate and redox titration amount of Comparative Example 5, since the first stage baking was performed excessively, the baking temperature and the baking time were not changed, and in Example 7, the air flow rate was set to SV = 30. In Example 8, as a result of changing the aeration amount to SV = 314, the weight change rate and the oxidation-reduction titration amount were in an appropriate range, and the catalyst performance recovered to the acrylic acid yield in the 40% range. The improvement of the firing state was confirmed.
Figure JPOXMLDOC01-appb-T000005
Figure JPOXMLDOC01-appb-T000005
＜実施例９＞
　試験例１において、蓚酸ニオブの添加時間を１０秒から３分に変え、スラリーを作製し、実施例１と同じ方法にて得られた乾固品を、焼成し、アクリル酸の製造反応に使用した。 <Example 9>
In Test Example 1, the addition time of niobium oxalate was changed from 10 seconds to 3 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
＜実施例１０＞
　試験例１において、蓚酸ニオブの添加時間を１０秒から６分に変え、スラリーを作製し、実施例１と同じ方法にて得られた乾固品を、焼成し、アクリル酸の製造反応に使用した。 <Example 10>
In Test Example 1, the addition time of niobium oxalate was changed from 10 seconds to 6 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
＜実施例１１＞
　試験例１において、蓚酸ニオブと反応液を、工業用連続混合装置スタチックミキサーであるスタティックミキサーＴ４－２１Ｒ（商品名、（株）ノリタケカンパニーリミテド製）を用いて混合し、スラリーを作製し、実施例１と同じ方法にて得られた乾固品を、焼成し、アクリル酸の製造反応に使用した。 <Example 11>
In Test Example 1, niobium oxalate and the reaction solution were mixed using a static mixer T4-21R (trade name, manufactured by Noritake Co., Ltd.), which is an industrial continuous mixer, a static mixer, to prepare a slurry, The dried product obtained in the same manner as in Example 1 was baked and used for the reaction for producing acrylic acid.
＜参考例４＞
　試験例１において、蓚酸ニオブの添加時間を１０秒から２０分に変え、スラリーを作製し、実施例１と同じ方法にて得られた乾固品を、焼成し、アクリル酸の製造反応に使用した。 <Reference Example 4>
In Test Example 1, the addition time of niobium oxalate was changed from 10 seconds to 20 minutes to produce a slurry, and the dried product obtained by the same method as in Example 1 was baked and used for the production reaction of acrylic acid did.
Figure JPOXMLDOC01-appb-T000006
Figure JPOXMLDOC01-appb-T000006
　本発明における金属酸化物触媒の製造方法によれば、熱質量分析または元素分析の検査方法により短時間で１段目の焼成状態を把握することができるため、触媒活性のバラツキが少ない高活性な金属酸化物触媒が製造できる。
　製造された金属酸化物触媒は、プロパン転化率、アクリル酸選択率およびアクリル酸収率に優れた触媒活性を発現するため、プロパンの気相接触酸化によるアクリル酸の製造用の触媒として用いることができる。 According to the method for producing a metal oxide catalyst in the present invention, the firing state of the first stage can be grasped in a short time by an inspection method of thermal mass spectrometry or elemental analysis, so that there is little variation in catalyst activity. A metal oxide catalyst can be produced.
The produced metal oxide catalyst exhibits excellent catalytic activity in terms of propane conversion, acrylic acid selectivity and acrylic acid yield, so it can be used as a catalyst for the production of acrylic acid by vapor phase catalytic oxidation of propane. it can.

Claims (5)

  1. 　還元剤と水または有機溶剤との存在下で、Ｔｅ４＋化合物またはＴｅ６＋化合物を還元して金属テルルを含む還元物を得る工程、
    　前記還元物から未反応の還元剤を除去する工程、
    　Ｍｏ、Ｖ、Ａ元素および水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させ反応物を得る工程、ならびに、
    　得られた反応物を乾燥および焼成し下記組成式で表される金属酸化物触媒を得る工程を含み、
    　前記焼成を２段階で行い、
    　１段目の焼成で得られる物質が下記分析値Ａおよび下記分析値Ｂのうち少なくとも１つの分析値に含まれる
    　金属酸化物触媒の製造方法。
    組成式：ＭｏＶｉＴｅｊＡｋＯｙ
    　式中、Ａは、Ｎｂ、Ｔａ、Ｗ、Ｔｉ、Ｚｒ、Ｒｅ、Ｆｅ、Ｎｉ、Ｃｏ、Ｓｎ、Ｔｌ、Ｃｕ、希土類元素およびアルカリ金属元素よりなる群から選ばれる少なくとも１種の元素であり、ｉおよびｊは、各々０．０１～１．５で、かつｊ／ｉ＝０．３～１．０であり、ｋは０．００１～３．０であり、ｙは他の元素の酸化状態によって決定される数である。
    分析値Ａ：下記式１で定義される質量変化率の値が１．２～４．０％である。
    質量変化率（％）＝［（加熱前の質量－加熱後の質量）／加熱前の質量］×１００（式１）
    分析値Ｂ：燃焼法による炭素、水素および窒素の元素分析における窒素含有量が０．８～１．５質量％である。     Reducing the Te 4+ compound or Te 6+ compound in the presence of a reducing agent and water or an organic solvent to obtain a reduced product containing metal tellurium;
    Removing unreacted reducing agent from the reduced product,
    Reacting a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V, A element and water, to obtain a reaction product; and
    Including a step of drying and calcining the obtained reaction product to obtain a metal oxide catalyst represented by the following composition formula,
    Performing the firing in two stages;
    A method for producing a metal oxide catalyst, wherein a substance obtained by the first-stage calcination is contained in at least one analysis value of the following analysis value A and the following analysis value B.
    Composition formula: MoV i Te j A k O y
    In the formula, A is at least one element selected from the group consisting of Nb, Ta, W, Ti, Zr, Re, Fe, Ni, Co, Sn, Tl, Cu, rare earth elements and alkali metal elements, i and j are each 0.01 to 1.5, and j / i = 0.3 to 1.0, k is 0.001 to 3.0, and y is an oxidation state of another element. Is a number determined by
    Analytical value A: The mass change rate defined by the following formula 1 is 1.2 to 4.0%.
    Mass change rate (%) = [(mass before heating−mass after heating) / mass before heating] × 100 (formula 1)
    Analysis value B: The nitrogen content in the elemental analysis of carbon, hydrogen and nitrogen by the combustion method is 0.8 to 1.5 mass%.
  2. 　前記反応物を得る工程が、Ｍｏ、Ｖおよび水の存在下で、前記未反応の還元剤を除去した金属テルルを含む還元物を反応させ、その後、Ａ元素を含有する化合物と混合して反応させ反応物を得る工程である請求項１に記載の金属酸化物触媒の製造方法。 The step of obtaining the reactant reacts with a reduced product containing metal tellurium from which the unreacted reducing agent has been removed in the presence of Mo, V and water, and then mixed with a compound containing element A and reacted. The method for producing a metal oxide catalyst according to claim 1, wherein the method is a step of obtaining a reaction product.
  3. 　さらに１段目の焼成で得られる物質が下記分析値Ｃに含まれる請求項１または請求項２に記載の金属酸化物触媒の製造方法。
    分析値Ｃ：試料を硫酸水溶液に分散した溶液を、加熱下で、酸化剤を用いて酸化還元滴定して得られる試料１ｇ当たりの消費される酸素モル数が３．４～５．５ｍｍｏｌである。     Furthermore, the manufacturing method of the metal oxide catalyst of Claim 1 or Claim 2 in which the substance obtained by 1st step | paragraph baking is contained in the following analysis value C.
    Analytical value C: The number of moles of oxygen consumed per 1 g of the sample obtained by subjecting the solution in which the sample is dispersed in the sulfuric acid aqueous solution to oxidation-reduction titration with heating using an oxidizing agent is 3.4 to 5.5 mmol. .
  4. 　２段目の焼成を、酸素不存在下で、５００℃～６６０℃の温度範囲で行う請求項１～請求項３のいずれか１項に記載の金属酸化物触媒の製造方法。 The method for producing a metal oxide catalyst according to any one of claims 1 to 3, wherein the second stage calcination is performed in the temperature range of 500 ° C to 660 ° C in the absence of oxygen.
  5. 　請求項１～請求項４のいずれか１項に記載の方法で得られた金属酸化物触媒を用いて、プロパンを気相接触反応により酸化するアクリル酸の製造方法。 A method for producing acrylic acid, wherein propane is oxidized by a gas phase catalytic reaction using the metal oxide catalyst obtained by the method according to any one of claims 1 to 4.
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Publication number Priority date Publication date Assignee Title
CN108325533A (en) * 2018-02-01 2018-07-27 上海东化环境工程有限公司 Modified support, O composite metallic oxide catalyst and method for producing acrylic acid

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