CN113828323A - Supplementary catalyst for acrylonitrile production, preparation method and application - Google Patents

Supplementary catalyst for acrylonitrile production, preparation method and application Download PDF

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CN113828323A
CN113828323A CN202010590862.XA CN202010590862A CN113828323A CN 113828323 A CN113828323 A CN 113828323A CN 202010590862 A CN202010590862 A CN 202010590862A CN 113828323 A CN113828323 A CN 113828323A
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molybdenum oxide
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molybdenum
acrylonitrile
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CN113828323B (en
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张顺海
吴粮华
李静霞
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China Petroleum and Chemical Corp
Sinopec Shanghai Research Institute of Petrochemical Technology
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Sinopec Shanghai Research Institute of Petrochemical Technology
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/70—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper
    • B01J23/76—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/84—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of the iron group metals or copper combined with metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36 with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/85—Chromium, molybdenum or tungsten
    • B01J23/88—Molybdenum
    • B01J23/887—Molybdenum containing in addition other metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
    • B01J23/8876—Arsenic, antimony or bismuth
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    • B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
    • B01J23/16—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00 of arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J23/24—Chromium, molybdenum or tungsten
    • B01J23/28—Molybdenum
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    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C253/00—Preparation of carboxylic acid nitriles
    • C07C253/24—Preparation of carboxylic acid nitriles by ammoxidation of hydrocarbons or substituted hydrocarbons
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    • Y02P20/00—Technologies relating to chemical industry
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    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

Abstract

The invention provides a supplementary catalyst for acrylonitrile production, a preparation method and application thereof. The supplementary catalyst for acrylonitrile production provided by the invention comprises molybdenum oxide and a composition; the weight ratio of the composition to the molybdenum oxide is 4-50; the mass content of silicon in the molybdenum oxide is 1-3%; and the particle size of the molybdenum oxide is 10-50 microns; according to the XRD spectrogram of the molybdenum oxide, the molybdenum oxide has a strongest peak when the 2 theta of a crystalline phase of the molybdenum oxide is 25.8 +/-1 degrees, a second strongest peak when the 2 theta of the crystalline phase of the molybdenum oxide is 12.8 +/-1 degrees and a third strongest peak when the third strongest peak is 39.1 +/-1 degrees. The supplemented catalyst provided by the invention is used for propylene ammoxidation, can obtain higher acrylonitrile yield under higher propylene load, and can keep stability for a long time.

Description

Supplementary catalyst for acrylonitrile production, preparation method and application
Technical Field
The invention relates to a fluidized bed catalyst for producing acrylonitrile by propylene ammoxidation, in particular to a supplementary catalyst for producing acrylonitrile, a preparation method and application thereof.
Background
Acrylonitrile is an important organic chemical raw material, and at present, more than 95 percent of acrylonitrile is produced by propylene ammoxidation. In order to obtain a fluidized bed catalyst with high activity and high selectivity, people continuously explore and perform a series of improvements. The improvements relate to catalyst active components, and the collocation of the catalyst active components is emphasized to improve the activity and the selectivity of the catalyst, so that the one-way yield of the acrylonitrile is improved, and the production load is improved. At present, the single-pass yield of fresh acrylonitrile catalyst can reach more than 80%, the activity of the catalyst can be gradually reduced after the industrial device is used for a long time, and the single-pass yield of the acrylonitrile catalyst is reduced by more than 1 percentage point after the industrial device is generally used for two years, so that the economic benefit of the device is influenced. Because the catalyst is expensive, the whole tower is replaced less frequently for economic reasons. It is common practice in the industry to maintain reaction performance by replenishing the catalyst or regenerating the catalyst with reduced activity.
The fluidized bed catalyst for producing acrylonitrile by propylene ammoxidation in the field adopts Mo-Bi-Fe system catalyst. Wherein the necessary component Mo is easy to be sublimated and lost under the action of high temperature and reaction atmosphere, especially water vapor, so that the composition of the catalyst formula is changed and deviates from the optimal formula. In addition, in long-term operation, the performance of the ammonia oxidation catalyst is reduced due to factors such as excessive reduction of certain components with redox properties in the catalyst, change of the active phase structure of the catalyst, change of the fluidization state caused by change of the particle size distribution of the catalyst, carbon deposition of catalyst pore channels and the like.
For example, CN201210412584.4 discloses a fluidized bed catalyst for preparing unsaturated nitrile by ammoxidation, a preparation method and an application catalyst thereof, wherein the catalyst is Mo12Bi1.2Fe2.2Ni6.6Co1.0Ce0.7Sm0.2Sb0.01K0.07+46％SiO2The method is used for ammoxidation reaction, and the obtained alkene nitrile has high one-way yield. However, in long-term operation of the catalyst, the loss of the Mo component still exists, so that the activity of the catalyst is reduced, and the long-term stability is influenced.
Currently, one of the ways to maintain the acrylonitrile yield is by a method of catalyst regeneration. CN1110193A regenerated the catalyst by replenishing ammonium molybdate and under a nitrogen air mixed atmosphere. US4609635 and US4052332 both regenerate the catalyst by impregnating the reduced activity catalyst with a solution containing certain components of the catalyst followed by calcination. CN200910056808.0 introduces a method for maintaining catalyst activity through regeneration, which comprises the steps of supplementing corresponding molybdenum content, roasting at 550-700 ℃, and roasting under the condition that roasting atmosphere is selected from at least two of air, nitrogen or water vapor to obtain a regenerated catalyst, but the maintenance time of the regenerated catalyst cannot be lasting, so that the stable operation of a production device is influenced. In addition, only external regeneration of the reactor can be adopted, which affects production.
Another method is to employ a method of replenishing the catalyst. CN1061163A discloses a supplementary catalyst for maintaining the activity of a molybdenum-based catalyst of an acrylonitrile fluidized bed to be stable, wherein the element composition of the supplementary catalyst is the same as or close to that of the original molybdenum-based catalyst, and only the molybdenum content is higher than that of the original molybdenum-based catalyst.
Disclosure of Invention
One of the technical problems to be solved by the invention is to provide a new supplementary catalyst for acrylonitrile production, which can maintain the stable performance of the catalyst for a long time in the acrylonitrile production process and improve the production efficiency and economic benefit of a device.
The second technical problem to be solved by the present invention is to provide a method for preparing the additional catalyst described in the first technical problem.
The present invention also provides the use of the above-mentioned supplemental catalyst in the ammoxidation of propylene to produce acrylonitrile.
In a first aspect, the present invention provides a supplemental catalyst for the production of acrylonitrile comprising molybdenum oxide and a composition; the weight ratio of the composition to the molybdenum oxide is 4-50;
wherein the mass content of silicon in the molybdenum oxide is 1-3%; and the particle size of the molybdenum oxide is 10-50 microns; the XRD spectrum information of the molybdenum oxide is shown in the following table:
2θ(°) relative intensity, (I/I)0)×100
12.8±1 70-93
23.3±1 15-38
25.8±1 100
27.3±1 18-32
39.1±1 45-65
。
As shown in the table, the molybdenum oxide crystal phase 2 theta is the strongest peak at 25.8 +/-1 degrees, the secondary strong peak at 12.8 +/-1 degrees and the third strong peak at 39.1 +/-1 degrees.
In the supplementary catalyst, the composition contains a carrier and an active component, wherein the active component is a Mo-Bi-Fe system catalyst, and the mass ratio of Mo in the composition to Mo in the bulk catalyst for preparing the unsaturated nitrile by olefin ammoxidation is 2.0-1.0.
Further, the XRD spectrum information of the molybdenum oxide is shown in the following table:
Figure BDA0002555462040000021
Figure BDA0002555462040000031
further, the chemical general formula of the active components of the composition in terms of atomic ratio can be as follows:
AaQbFecNidBieMo12Ox
in the formula: a is selected from at least one of Li, Na, K, Rb and Cs elements; q comprises at least one element selected from Be, Mg, Ca, Sr and Ba;
wherein, the value range of a is 0.01-2.50; the value range of b is 0.01-15.00; the value range of c is 0.01-5.00; the value range of d is 1.00-10.00; the value range of e is 0.01-5.00; x is the total number of oxygen atoms required to satisfy the valences of the elements in the catalyst.
Further, the carrier of the composition in the additional catalyst may be present in an amount of 30 to 70 wt% by weight, and the active component may be present in an amount of 30 to 70 wt% by weight. The carrier in the composition may include at least one selected from the group consisting of silica, alumina, titania and zirconia.
Further, in the composition of the supplementary catalyst, the active component Q may also preferably Be B and L, wherein B is selected from at least one of Be, Mg, Ca, Sr and Ba elements, and L is selected from at least one of Nb, Pr, Yb, Tm and Er elements, when the active component may Be represented by the following general chemical formula in terms of atomic ratio:
AaBmLnFecNidBieMo12Ox
wherein:
b is selected from at least one of Be, Mg, Ca, Sr and Ba elements;
l is at least one of Nb, Pr, Yb, Tm and Er elements;
the value range of m is 0.10-10.00;
the value range of n is 0.01-5.00.
Further, a preferably ranges from 0.05 to 1.50, and non-limiting specific values of a in this range may be 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, and the like. Further, non-limiting specific point values for m may be 0.20, 0.40, 0.60, 0.80, 1.00, 1.50, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, 3.00, 3.20, 3.40, 3.80, 4.20, 4.80, 5.20, 5.80, 6.20, 6.80, 7.20, 7.80, 8.20, 8.40, 8.60, 8.80, 9.20, 9.60, 9.80, and so forth. Further, non-limiting specific point values for n may be 0.05, 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.60, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, 3.00, 3.20, 3.40, 4.20, 4.60, 4.80, and so forth. Further, the value range of c is preferably 0.05-3.50, and non-limiting specific points of c in this value range may be 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.60, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, 3.00, 3.20, 3.40, etc. Further, d preferably ranges from 1.50 to 9.00, and non-limiting specific values of d within this range can be 1.60, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, 3.00, 3.20, 3.40, 3.80, 4.20, 4.80, 5.20, 5.80, 6.20, 6.80, 7.20, 7.80, 8.20, 8.80, and so on. Further, the value range of e is preferably 0.05-3.00, and non-limiting specific values of e in this value range may be 0.10, 0.20, 0.30, 0.40, 0.50, 0.60, 0.70, 0.80, 0.90, 1.00, 1.10, 1.20, 1.30, 1.40, 1.60, 1.80, 2.00, 2.20, 2.40, 2.60, 2.80, and so on.
Further, the average particle size of the composition in the supplemental catalyst is 20 to 80 microns.
Further, the weight ratio of the composition to the molybdenum oxide in the supplemental catalyst preferably ranges from 6 to 45, with non-limiting specific values being 7.0, 9.0, 11.0, 15.0, 20.0, 25.0, 30.0, 35.0, 40.0, and the like.
The bulk catalyst for producing unsaturated nitrile by ammoxidation of olefin used in the present invention is a catalyst for producing unsaturated nitrile by ammoxidation of olefin conventionally used in the art, and for example, the Mo-Bi-Fe-based catalyst is not limited to Mo-Bi-Fe, and the catalyst may contain at least one of an alkali metal element, an alkaline earth metal element, a lanthanoid metal and the like. The conventional preparation method of the bulk catalyst comprises the following steps: respectively dissolving compounds of corresponding component elements in water, mixing and stirring uniformly, mixing with the carrier sol to obtain catalyst slurry, spray-drying the slurry, and roasting in an oxidizing atmosphere to obtain the bulk catalyst. The average particle size of the bulk catalyst is typically in the range 25 to 75 microns.
Further, the bulk catalyst for the ammoxidation of olefin to produce unsaturated nitrile used in the present invention may be the same as or different from the composition used in the additional catalyst.
In a second aspect, the present invention provides a method for preparing a supplemental catalyst, comprising the steps of:
uniformly mixing the composition and the molybdenum oxide to obtain the supplemented catalyst;
the preparation steps of the composition in the supplementary catalyst are as follows: respectively dissolving compounds of corresponding component elements in water, mixing and stirring uniformly, mixing with the carrier sol to obtain catalyst slurry, spray-drying the slurry, and roasting in an oxidizing atmosphere to obtain a composition;
the preparation steps of the molybdenum oxide in the supplemented catalyst are as follows: performing desulfurization treatment on the silicon-containing molybdenum concentrate, then performing reduction treatment, cooling, and oxidizing under a temperature programming condition and an oxidizing atmosphere to obtain a molybdenum oxide precursor; and roasting the molybdenum oxide precursor in an inert atmosphere, and screening the roasted molybdenum oxide particles by 10-50 microns to prepare the molybdenum oxide.
Further, the preparation method of the composition comprises the following steps:
(a) dissolving the raw material A to obtain a material I; dissolving the raw material of molybdenum to obtain a material II; dissolving the raw material of Q and the raw materials of Fe, Bi and Ni to obtain a material III;
(b) mixing the material I and the carrier sol, adding the material II and the material III in sequence under stirring to obtain catalyst slurry, and spray-drying the catalyst slurry to obtain a composition precursor;
(c) the composition precursor is calcined in an oxidizing atmosphere to obtain the composition.
Further, the preparation method of the composition, after the preparation of the catalyst slurry and before the spray drying, preferably further comprises: a step of heat-treating the catalyst slurry; the temperature of the heat treatment is 80-150 ℃; the heat treatment time is 1-50 minutes.
Further, in the preparation method of the composition, the process conditions of the spray drying are not particularly limited, and those skilled in the art can reasonably select and do not need to exert creative efforts.
Further, in the preparation method of the composition, the roasting temperature is 500-700 ℃, and the roasting time is 0.25-4 hours.
Further, in the preparation method of the composition, the raw material of molybdenum in the composition is preferably at least one of molybdenum oxide or ammonium molybdate; the raw materials of A, B, L, Fe, Ni and Bi are nitrates, oxalates, hydroxides, oxides or salts which can be decomposed into oxides.
Further, in the preparation method of molybdenum oxide, the desulfurization treatment method comprises the following steps: the molybdenum concentrate containing silicon is firstly roasted for 2 to 6 hours at the temperature of 500-650 ℃ in the oxygen-enriched or air atmosphere until the sulfur content can not be detected.
Further, in the preparation method of the molybdenum oxide, the cooling is to cool the materials to room temperature-300 ℃.
Further, in the preparation method of molybdenum oxide, the reducing atmosphere may adopt a gas with reducing property commonly used in the art, such as but not limited to, a gas derived from CO, pure hydrogen, and the like, the reducing atmosphere is preferably a mixed gas of hydrogen and an inert gas, and the reducing temperature is preferably 800-.
Further, in the preparation method of the molybdenum oxide, the programmed temperature rise is 1 ℃/min-30 ℃/min, preferably 5 ℃/min-20 ℃/min, the temperature of the oxidation process is 500-.
Further, in the preparation method of molybdenum oxide, the inert gas atmosphere may be inert gas commonly used in the art, such as, but not limited to, inert gas derived from nitrogen, helium, etc. or their mixture. The firing temperature is preferably in the range of 650-700 ℃. The calcination time is preferably in the range of 0.5 to 3 hours.
Further, in the preparation method of the composition and the preparation method of the molybdenum oxide, the oxidizing atmosphere can adopt a gas which is commonly used in the field and has oxidizing property, such as but not limited to a gas which is derived from oxygen enrichment, pure oxygen, air and the like, and preferably air.
The third aspect of the invention provides the use of the above-mentioned supplementary catalyst in the preparation of acrylonitrile by ammoxidation of propylene.
Furthermore, the application comprises the step of supplementing the supplementary catalyst into the reaction system for preparing the acrylonitrile by propylene ammoxidation. The reaction system for preparing acrylonitrile by propylene ammoxidation is preferably a fluidized bed reaction system.
Further, in the application, the supplemented catalyst is continuously supplemented in the presence of the bulk catalyst for preparing unsaturated nitrile by olefin ammoxidation, and the supplementing mode is a continuous supplementing mode.
Further, in the application, the supplemented catalyst is supplemented at the rate of 0.3-0.7 kg/ton acrylonitrile, and the catalyst is supplemented to control the density of the catalyst in the bed layer to be 330-520kg/m3。
Further, in the application, the reaction temperature is 410-460 ℃; in terms of molar ratio, the ratio of propylene, ammonia and oxygen is 1 (1.05-1.35) to 1.7-2.5; the catalyst load WWH can be 0.04-0.12h-1(ii) a The reaction pressure is 30-100 KPa.
Further, in the application, the oxygen is not particularly limited, and oxygen-containing gas commonly used in the art, such as but not limited to, oxygen-enriched gas, pure oxygen, air, etc., can be used.
The specifications of propylene, ammonia and molecular oxygen required for producing acrylonitrile by the additional catalyst of the present invention are the same as those of acrylonitrile produced by other ammoxidation catalysts. Although the content of low-molecular saturated hydrocarbons in the raw material propylene does not affect the reaction, the propylene concentration is preferably more than 85 mol% from the economical viewpoint. The ammonia may be fertilizer-grade liquid ammonia. The molecular oxygen required for the reaction may be pure oxygen, oxygen-enriched oxygen or air from a technical point of view, but air is preferably used from economical and safety points of view.
The product recovery and refining process for preparing acrylonitrile by adding the catalyst can use the existing production process without any modification. The effluent gas from the fluidized bed reactor is neutralized in a neutralizing tower to eliminate unreacted ammonia and low temperature water is used to absorb all organic product. And (3) carrying out extractive distillation, dehydrocyanation and dehydration on the absorption liquid to obtain a high-purity acrylonitrile product.
According to the technical scheme, the initial activity of the bulk catalyst is high, but the problem that molybdenum is easy to sublimate exists, and the like, the supplemented catalyst effectively utilizes the selection of the active components of the composition, the proportion of the composition to the molybdenum oxide and the crystalline phase structure of the molybdenum oxide, has a comprehensive effect, can maintain the stable performance of the catalyst for a long time in the production process of acrylonitrile, reduces the loss speed of molybdenum element in the bulk catalyst for preparing unsaturated nitrile by olefin ammoxidation, and improves the production efficiency and the economic benefit of a device. Particularly, the adopted supplementary catalyst contains silicon-containing molybdenum oxide with specific crystalline phase and performance, a small amount of silicon oxide and molybdenum oxide form a chemically stable structure to form Mo-Si-O chemical bonds to change the performance of the molybdenum oxide, and the molybdenum oxide has a granular structure with certain strength and has the characteristics of maintaining stable production of an acrylonitrile device, high acrylonitrile yield and the like. The use of the supplemental catalyst of the present invention for propylene ammoxidation enables higher acrylonitrile yields to be obtained at higher propylene loadings and remain stable over a long period of time.
Drawings
FIG. 1 is an XRD diffraction pattern of molybdenum oxide prepared in EXAMPLE 1;
FIG. 2 is an XRD diffraction pattern of molybdenum oxide prepared in comparative example 1.
Detailed Description
The propylene conversion, acrylonitrile selectivity and once-through yield are defined in the present invention as follows:
Figure BDA0002555462040000061
Figure BDA0002555462040000071
Figure BDA0002555462040000072
in the present invention, XRD analysis was performed on a BRUKER D8ADVANCE diffractometer using a Cu ka radiation source (λ 0.15406nm), Ni monochromator. The working condition is that the pipe pressure is 40kV, the pipe flow is 250mA, the scanning speed is 12 degrees/min, and the test 2 theta range is 5-80 degrees.
The present invention is further illustrated by the following examples, which are not intended to limit the scope of the present invention.
[ example 1 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g MirabilitumCalcium Ca (NO)3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 56.6 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 600 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 950 ℃ in a mixed gas atmosphere of hydrogen and nitrogen to prepare granular molybdenum powder with the silicon content of 1.8 percent; heating the molybdenum powder cooled to 200 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 675 ℃ for 1 hour in a nitrogen atmosphere, cooling, and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst.
Wherein the structure of the prepared molybdenum oxide crystal phase is shown in figure 1. The XRD spectrogram information of molybdenum oxide is shown in the following table, and according to the table, the molybdenum oxide has the strongest peak when the 2 theta of the crystalline phase of the molybdenum oxide is 25.8 degrees, the secondary intensity peak is 12.8 degrees, and the third intensity peak is 39.1 degrees.
2θ(°) Relative intensity, (I/I)0)×100
12.8 78.2
23.3 20.3
25.8 100
27.3 18.2
39.1 50.7
2. Catalyst evaluation
The performance evaluation of the replenished catalyst was carried out in a fluidized bed reactor of an acrylonitrile plant on a scale of 8 ten thousand tons/year. The reaction conditions are as follows:
the reaction temperature is 435 DEG C
Reaction pressure 70kPa
Catalyst loading 140 tons
Catalyst propylene load (WWH)0.080 hours-1
Raw material ratio (mol) C3H6/NH3Oxygen 1/1.15/1.9.
The bulk catalyst for preparing unsaturated nitrile by olefin ammoxidation is as follows: 50% K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo11.8Ox+50％SiO2. Catalyst particlesThe diameter was 58.1 microns.
The industrial device supplements the supplementary catalyst described in the embodiment 1 by a continuous supplementary mode, supplements the catalyst at the rate of 0.4 kg/ton acrylonitrile, and controls the density of the catalyst in the bed layer to be 400kg/m3。
The composition and properties of the added catalyst are shown in Table 1, and the catalytic performance results are shown in Table 2.
[ example 2 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 57.5 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 620 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 850 deg.C in mixed gas atmosphere of hydrogen and nitrogen to obtain granular molybdenum powder with silicon content of 1.2%; heating the molybdenum powder cooled to 150 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 695 ℃ for 1 hour in a nitrogen atmosphere, cooling and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
(3) 380 grams of the catalyst composition was mixed uniformly with 20 grams of molybdenum oxide to provide additional catalyst. The catalyst composition and properties are shown in Table 1.
The XRD spectrogram of the prepared molybdenum oxide is the same as that of example 1, the information of the XRD spectrogram of the molybdenum oxide is shown in the following table, and according to the table, the molybdenum oxide is the strongest peak when the 2 theta of the crystalline phase of the molybdenum oxide is 25.8 degrees, the secondary strong peak is 12.8 degrees, and the third strong peak is 39.1 degrees. The evaluation conditions were the same as in example 1, and the performance results are shown in Table 2.
2θ(°) Relative intensity, (I/I)0)×100
12.8 72.2
23.3 22.5
25.8 100
27.3 19.8
39.1 52.4
[ example 3 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 60.1 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 610 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 980 ℃ in the mixed gas atmosphere of hydrogen and nitrogen to obtain granular molybdenum powder with the silicon mass content of 3%; heating the molybdenum powder cooled to 200 ℃ to 700 ℃ at the programmed heating rate of 10 ℃ per minute in the air atmosphere, keeping the temperature for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 655 ℃ for 1 hour in a nitrogen atmosphere, cooling, and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst. The catalyst composition and properties are shown in Table 1.
Wherein, the XRD spectrogram information of the prepared molybdenum oxide is shown in the following table, wherein the maximum intensity peak is obtained when the 2 theta of the molybdenum oxide crystal phase is 25.8 degrees, the secondary intensity peak is obtained when the 12.8 degrees, and the third intensity peak is 39.1 degrees.
2θ(°) Relative intensity, (I/I)0)×100
12.8 78.5
23.3 25.8
25.8 100
27.3 23.5
39.1 50.6
[ example 4 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
3.60 g of potassium nitrate and 4.65 g of cesium nitrate were dissolved in 15 g of water by heating to obtainMaterial I; 512.6 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 500 g of 80 ℃ hot water to obtain a material II; adding 11.6 g of bismuth nitrate Bi (NO)3)3·5H2O, 84.9 g calcium nitrate Ca (NO)3)2·4H2O, 387.5 g Nickel nitrate Ni (NO)3)2·6H2O, 146.8 g of ferric nitrate Fe (NO)3)3·9H2O, 258.2 g praseodymium nitrate Pr (NO)3)3·6H2O, 139.6 g cobalt nitrate Co (NO)3)2·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 750 g of silica sol with the weight concentration of 40%, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 55.8 microns, wherein the catalyst composition comprises the following components:
70％K0.15Cs0.1Fe1.5Ni5.5Co2.0Ca1.5Pr2.5Bi0.1Mo12.0Ox+30％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 600 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 950 ℃ in a mixed gas atmosphere of hydrogen and nitrogen to prepare granular molybdenum powder with the silicon content of 1.9 percent; heating the molybdenum powder cooled to 200 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 675 ℃ for 1 hour in a nitrogen atmosphere, cooling, and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
(3) 350 grams of the catalyst composition and 50 grams of molybdenum oxide were uniformly mixed to provide additional catalyst. The catalyst composition and properties are shown in Table 1.
Wherein the XRD spectrum of the prepared molybdenum oxide is the same as that of example 1.
[ COMPARATIVE EXAMPLE 1 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 56.6 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
reducing 800 g of ammonium molybdate in the mixed gas atmosphere of hydrogen and nitrogen at 900 ℃ to prepare powdery molybdenum powder; and oxidizing the molybdenum powder cooled to 200 ℃ for 1 hour at 450 ℃ in an air atmosphere, and cooling to obtain the molybdenum oxide.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst. The catalyst composition and properties are shown in Table 1.
Wherein, the structure of the molybdenum oxide crystal phase is shown in figure 2. The XRD spectrum of molybdenum oxide is shown in the following table, the highest intensity peak is at 12.8 degrees of molybdenum oxide crystal phase 2 theta, the second intensity peak is at 25.8 degrees, and the third intensity peak is at 39.1 degrees.
2θ(°) Relative intensity, (I/I)0)×100
12.8 105.5
23.3 12.4
25.8 100
27.3 10.5
39.1 49.2
2. Catalyst evaluation the same as in example 1
The performance results are shown in Table 2.
[ COMPARATIVE EXAMPLE 2 ]
1. Supplementary catalyst preparation
Roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 600 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 950 ℃ in a mixed gas atmosphere of hydrogen and nitrogen to prepare granular molybdenum powder with the silicon content of 1.8 percent; heating the molybdenum powder cooled to 200 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 675 ℃ for 1 hour in a nitrogen atmosphere, cooling, and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
Only 400 grams of molybdenum oxide was used as the supplemental catalyst. The catalyst composition and properties are shown in Table 1.
Wherein the XRD spectrum of the prepared molybdenum oxide is the same as that of example 1.
2. Catalyst evaluation the same as in example 1
Molybdenum oxide is only supplemented without adding the composition, and the molybdenum oxide alone does not have catalytic activity and cannot keep stable after long-term operation. After 3 months, the conversion rate of propylene is reduced to 96.7 percent from 98.5 percent in the initial stage, the selectivity of acrylonitrile is reduced to 81.5 percent from 84.1 percent in the initial stage, the reduction trend is obvious, and the stability can not be maintained for a long time.
[ COMPARATIVE EXAMPLE 3 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 56.6 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 880 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 1000 deg.c in the mixed gas atmosphere of hydrogen and nitrogen to obtain granular molybdenum powder with silicon content of 10%; heating the molybdenum powder cooled to 200 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 600 ℃ for 1 hour in a nitrogen atmosphere, cooling and screening to obtain the molybdenum oxide with the particle size of 10-50 microns.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst. The composition and properties of the supplemental catalyst are shown in Table 1.
The XRD spectrogram information of molybdenum oxide is shown in the following table, and according to the table, the molybdenum oxide has the strongest peak when the 2 theta of the crystalline phase of the molybdenum oxide is 25.8 degrees, the secondary intensity peak is 12.8 degrees, and the third intensity peak is 39.1 degrees.
2θ(°) Relative intensity, (I/I)0)×100
12.8 67
23.3 40
25.8 100
27.3 38
39.1 43
2. The catalyst was evaluated as in example 1, and the performance results are shown in Table 2.
[ COMPARATIVE EXAMPLE 4 ]
1. Supplementary catalyst preparation
(1) The preparation method of the composition comprises the following steps:
adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 56.6 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate for 3 hours at 610 ℃ in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystalline phase; reducing at 950 ℃ in a mixed gas atmosphere of hydrogen and nitrogen to prepare granular molybdenum powder with the silicon content of 1.8 percent; heating the molybdenum powder cooled to 200 ℃ to 680 ℃ at a programmed heating rate of 10 ℃ per minute in an air atmosphere for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 675 ℃ for 1 hour in a nitrogen atmosphere, cooling and screening to obtain the molybdenum oxide with the particle size of 0.01-9 microns.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst. The catalyst composition and properties are shown in Table 1.
Wherein the XRD spectrum of the prepared molybdenum oxide is the same as that of example 1. The evaluation conditions were the same as in example 1.
Because the molybdenum oxide in the supplemented catalyst has a fine particle size, the subsequent system is easy to be blocked due to the easy loss, and the particle size distribution in the bed layer of the reactor is poor and the fluidization effect is poor. After 3 months, the conversion rate of propylene is reduced to 97.3% from 98.5% in the initial stage, the selectivity of acrylonitrile is reduced to 81.1% from 84.1% in the initial stage, the reduction trend is obvious, and the stability can not be maintained for a long time.
[ COMPARATIVE EXAMPLE 5 ]
1. Supplementary catalyst preparation
(1) Process for preparing a composition
Adding 15 g of water into 8.12 g of potassium hydroxide, heating and dissolving to obtain a material I; 319.1 g of ammonium heptamolybdate (NH)4)6Mo7O24·4H2Dissolving O in 300 g of 80 ℃ hot water to obtain a material II; 109.1 g of bismuth nitrate Bi (NO)3)3·5H2O, 177.0 g of Ca (NO) nitrate3)2·4H2O, 242.2 g of Ni (NO) nitrate3)2·6H2O, 110.1 g of iron nitrate Fe (NO)3)3·9H2O, 162.8 g Nd (NO) nitrate3)3·6H2And O, mixing, adding 120 g of water, and heating to dissolve to obtain a material III.
Mixing a material I with 1250 g of silica sol with the weight concentration of 40 percent, adding a material II and a material III in turn under stirring, fully stirring to obtain slurry, carrying out heat treatment on the slurry at 100 ℃ for 25 minutes, then carrying out microspherical molding on the heat-treated slurry in a spray dryer according to a conventional method, and finally roasting in a rotary roasting furnace with the inner diameter of 89 mm and the length of 1700 mm (phi 89 x 1700 mm) at 585 ℃ for 2.0 hours to prepare a catalyst composition with the average particle size of 56.6 microns, wherein the catalyst composition comprises the following components:
50％K0.80Ca5.00Nd2.50Fe1.80Ni5.50Bi1.50Mo12.0Ox+50％SiO2
(2) the preparation method of the molybdenum oxide comprises the following steps:
roasting 800 g of silicon-containing molybdenum concentrate in a rotary oxidation furnace at 670 ℃ for 3 hours in air atmosphere, and performing desulfurization treatment until XRD cannot detect a molybdenum sulfide crystal phase; reducing at 800 ℃ in the mixed gas atmosphere of hydrogen and nitrogen to prepare granular molybdenum powder with the silicon content of 1.8 percent; heating the molybdenum powder cooled to 150 ℃ to 660 ℃ at a temperature programming rate of 10 ℃ per minute in air atmosphere, keeping the temperature for 1h, and oxidizing the molybdenum powder into a molybdenum oxide precursor; and roasting the molybdenum oxide precursor at 675 ℃ for 1 hour in a nitrogen atmosphere, cooling and screening to obtain the molybdenum oxide with the particle size of 50-1000 microns.
(3) 360 grams of the catalyst composition and 40 grams of molybdenum oxide were uniformly mixed to provide the supplemental catalyst. The catalyst composition and properties are shown in Table 1.
Wherein the XRD spectrum of the prepared molybdenum oxide is the same as that of example 1. The evaluation conditions were the same as in example 1.
Because the molybdenum oxide in the supplemented catalyst has coarse granularity, the granularity distribution in the bed layer of the reactor is poor, and the fluidization effect is poor. After 3 months, the conversion rate of propylene is reduced to 96.5% from 98.5% in the initial stage, the selectivity of acrylonitrile is reduced to 81.8% from 84.1% in the initial stage, the reduction trend is obvious, and the stability can not be maintained for a long time.
TABLE 1 examples and comparative examples each supplemented catalyst composition and Properties
Figure BDA0002555462040000151
TABLE 2 Performance results for each of the examples and comparative examples
Figure BDA0002555462040000161

Claims (15)

1. A supplemental catalyst for acrylonitrile production comprising molybdenum oxide and a composition; the weight ratio of the composition to the molybdenum oxide is 4-50;
wherein the mass content of silicon in the molybdenum oxide is 1-3%; and the particle size of the molybdenum oxide is 10-50 microns; the XRD spectrum information of the molybdenum oxide is shown in the following table:
2θ(°) relative intensity, (I/I)0)×100 12.8±1 70-93 23.3±1 15-38 25.8±1 100 27.3±1 18-32 39.1±1 45-65
。
2. The supplemental catalyst according to claim 1, wherein the supplemental catalyst comprises a support and an active component, and the active component is a Mo-Bi-Fe-based catalyst, wherein the mass ratio of Mo in the composition to Mo in the bulk catalyst for the ammoxidation of olefins to unsaturated nitriles is from 2.0 to 1.0.
3. The supplemental catalyst of claim 1, wherein the molybdenum oxide XRD spectrum information is in the following table:
2θ(°) relative intensity, (I/I)0)×100 12.8±1 75-92 23.3±1 18-33 25.8±1 100 27.3±1 19-27 39.1±1 47-60
。
4. The supplemented catalyst according to claim 1, characterized in that the active components of the composition can have the following general chemical formula in atomic ratio:
AaQbFecNidBieMo12Ox
in the formula: a is selected from at least one of Li, Na, K, Rb and Cs elements; q comprises at least one element selected from Be, Mg, Ca, Sr and Ba;
wherein the value range of a is 0.01-2.50; the value range of b is 0.01-15.00; the value range of c is 0.01-5.00; the value range of d is 1.00-10.00; the value range of e is 0.01-5.00; x is the total number of oxygen atoms required to satisfy the valences of the elements in the catalyst.
5. The supplemental catalyst according to claim 1, wherein in the supplemental catalyst, the carrier of the composition is present in an amount of 30 to 70 wt% by weight, and the active component is present in an amount of 30 to 70 wt% by weight; the carrier in the composition comprises at least one selected from the group consisting of silica, alumina, titania and zirconia.
6. A method of preparing a supplemental catalyst according to any of claims 1 to 5, comprising the steps of:
uniformly mixing the composition and the molybdenum oxide to obtain the supplemented catalyst;
in the additional catalyst, the preparation steps of the composition are as follows: respectively dissolving compounds of corresponding component elements in water, mixing and stirring uniformly, mixing with the carrier sol to obtain catalyst slurry, spray-drying the slurry, and roasting in an oxidizing atmosphere to obtain a composition;
in the supplemented catalyst, the preparation steps of the molybdenum oxide are as follows: performing desulfurization treatment on the silicon-containing molybdenum concentrate, then performing reduction treatment, cooling, and oxidizing under a temperature programming condition and an oxidizing atmosphere to obtain a molybdenum oxide precursor; and roasting the molybdenum oxide precursor in an inert atmosphere, and screening the roasted molybdenum oxide particles by 10-50 microns to prepare the molybdenum oxide.
7. The method of claim 6, wherein the composition is prepared by spray-drying the catalyst slurry, and further comprising: a step of heat-treating the catalyst slurry; the temperature of the heat treatment is 80-150 ℃; the heat treatment time is 1-50 minutes.
8. The method as claimed in claim 6, wherein the composition is prepared at a calcination temperature of 500-700 ℃ for 0.25-4 hours.
9. The method according to claim 6, wherein the desulfurization treatment in the method for producing molybdenum oxide is: the molybdenum concentrate containing silicon is firstly roasted for 2 to 6 hours at the temperature of 500-650 ℃ in the oxygen-enriched or air atmosphere until the sulfur content can not be detected.
10. The method according to claim 6, wherein in the molybdenum oxide production method, a reducing gas, preferably a mixed gas of hydrogen and an inert gas, is used as the reducing atmosphere; the reduction temperature is 800-1000 ℃.
11. The preparation method of claim 6, wherein the temperature programming is performed at 1 ℃/min-30 ℃/min, preferably 5 ℃/min-20 ℃/min, the temperature of the oxidation process is 500-.
12. Use of the supplemental catalyst according to any one of claims 1 to 5 in the ammoxidation of propylene to acrylonitrile.
13. The use according to claim 12, which comprises adding the additional catalyst to the reaction system for producing acrylonitrile by ammoxidation of propylene, wherein the additional catalyst is continuously added.
14. The use as claimed in claim 12, wherein the additional catalyst is added at a rate of 0.3-0.7 kg/ton acrylonitrile, and the additional catalyst controls the catalyst density in the bed to be 330-520kg/m3。
15. The use as claimed in claim 12, wherein the reaction temperature is 410-; in terms of molar ratio, the ratio of propylene, ammonia and oxygen is 1 (1.05-1.35) to 1.7-2.5; WWH of catalyst load is 0.04-0.12h-1(ii) a The reaction pressure is 30-100 KPa.
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