CN110724036A - Method for preparing benzenediol - Google Patents
Method for preparing benzenediol Download PDFInfo
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- CN110724036A CN110724036A CN201810783007.3A CN201810783007A CN110724036A CN 110724036 A CN110724036 A CN 110724036A CN 201810783007 A CN201810783007 A CN 201810783007A CN 110724036 A CN110724036 A CN 110724036A
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- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C37/00—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring
- C07C37/60—Preparation of compounds having hydroxy or O-metal groups bound to a carbon atom of a six-membered aromatic ring by oxidation reactions introducing directly hydroxy groups on a =CH-group belonging to a six-membered aromatic ring with the aid of other oxidants than molecular oxygen or their mixtures with molecular oxygen
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- B01J29/00—Catalysts comprising molecular sieves
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
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- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P20/00—Technologies relating to chemical industry
- Y02P20/50—Improvements relating to the production of bulk chemicals
- Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts
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Abstract
The invention relates to the field of benzenediol, and discloses a method for preparing benzenediol, which comprises the following steps: under the condition of oxidation reaction, phenol, at least one oxidant and a catalyst are contacted in a fixed bed reactor, wherein the catalyst contains a vanadium-titanium-silicon molecular sieve. The method provided by the invention not only can obtain high phenol conversion rate, effective utilization rate of the oxidant and selectivity of hydroquinone, but also can prolong the service life of the catalyst.
Description
Technical Field
The invention relates to the field of phenol oxidation, in particular to a method for preparing benzenediol.
Background
Hydroquinone and catechol are two important chemical raw materials and chemical intermediates, and have wide application. Catechol is useful as a rubber hardener, a plating additive, a skin antiseptic, a hair dye, a photographic developer, a color antioxidant, a fur dye developer, a paint and a varnish anti-skinning agent. Hydroquinone is mainly used as developer, anthraquinone dye, azo dye, synthetic ammonia cosolvent, rubber antioxidant, polymerization inhibitor, stabilizer for paint and essence, and antioxidant.
In the prior art, benzoquinones are formed primarily by oxidizing an aromatic hydroxy compound (e.g., phenol) with oxygen or an oxygen-containing gas, a copper-containing catalyst, and optionally a promoter, followed by a reduction reaction to form hydroquinone, but this process does not produce both benzoquinones and benzenediols.
In the early eighties of the last century, Taramasso, italy, in USP4410501, disclosed a novel catalytic oxidation material called titanium silicalite molecular sieve (TS-1) which has a very good selective oxidation effect on hydrocarbons, alcohols, phenols and the like.
The titanium silicalite molecular sieve is used as a catalyst to catalyze and oxidize phenol to obtain hydroquinone and catechol simultaneously. However, there is still room for improvement in the conversion of phenol by this production method, and the catalyst stability is poor.
Disclosure of Invention
The invention aims to overcome the defects of further improvement of the conversion rate of phenol and poor stability of a catalyst in the prior art, and provides a method for preparing benzenediol. The method for preparing the hydroquinone has higher phenol conversion rate, effective utilization rate of the oxidant and selectivity of the hydroquinone.
In order to overcome the above-mentioned disadvantages in the preparation of hydroquinone from phenol by an oxidation process, the present invention provides a method for preparing hydroquinone, comprising: under the condition of oxidation reaction, phenol, at least one oxidant and a catalyst are contacted in a fixed bed reactor, wherein the catalyst contains a vanadium-titanium-silicon molecular sieve.
The method provided by the invention not only can obtain high phenol conversion rate, effective utilization rate of the oxidant and selectivity of hydroquinone, but also can prolong the service life of the catalyst.
Detailed Description
The following describes in detail specific embodiments of the present invention. It should be understood that the detailed description and specific examples, while indicating the present invention, are given by way of illustration and explanation only, not limitation.
The invention provides a method for preparing benzenediol, which comprises the following steps: under the condition of oxidation reaction, phenol, at least one oxidant and a catalyst are contacted in a fixed bed reactor, wherein the catalyst contains a vanadium-titanium-silicon molecular sieve.
According to one embodiment of the invention, a catalyst bed is arranged in the fixed bed reactor, and phenol and at least one oxidant are fed into the fixed bed reactor and are contacted with a catalyst (containing a vanadium-titanium-silicon molecular sieve) arranged in the catalyst bed.
According to one embodiment of the present invention, phenol, at least one oxidant, may be fed into the fixed bed reactor from the bottom thereof.
According to a preferred embodiment of the present invention, the catalyst is a vanadium titanium silicalite. The inventor of the invention finds that in the process of preparing the hydroquinone, the vanadium-titanium-silicon molecular sieve is used as the catalyst, so that the high phenol conversion rate, the high effective utilization rate of the oxidant and the high selectivity of the hydroquinone can be obtained, and the service life of the catalyst can be prolonged.
In order to further improve the activity, selectivity and stability of the catalyst, preferably, the vanadium-titanium-silicon molecular sieve comprises: vanadium, titanium, silicon and oxygen, wherein the molecular sieve satisfies X1-1.8/X0.4-0.9＝C，0.2<C<1，X0.4-0.9The ratio of the pore diameter of the micropores of the molecular sieve in the range of 0.4-0.9nm to the distribution quantity of the total pore diameter, X1-1.8Is the proportion of the pore diameter of the micropores of the molecular sieve in the range of 1-1.8nm in the distribution quantity of the pore diameter of the total micropores. The inventor finds that the vanadium-titanium-silicon molecular sieve with a special physicochemical characteristic structure is used for phenol oxidation reaction, so that the selectivity of a target product (hydroquinone) is favorably regulated, and the conversion rate of phenol and the effective utilization rate of an oxidant are improved. Even more preferably, 0.25<C<0.85。
The preferred vanadium-titanium-silicon molecular sieve of the invention has pore size distribution not only in the range of 0.4-0.9nm, but also in the range of 1-1.8nm, and in the range of 1-1The ratio of the micropore diameter in the range of 8nm to the total micropore diameter distribution to the micropore diameter in the range of 0.4-0.9nm to the total micropore diameter distribution is C, 0.2<C<1, preferably, 0.25<C<0.85, further preferably 0.3<C<0.8. In the present invention, the pore size of the micropores can be measured by a conventional method, and the method of the present invention has no particular requirement and is well known to those skilled in the art, for example, by using N2Static adsorption and the like.
It is to be noted that, in particular, if the proportion of the pore size distribution of the micropores to the total pore size distribution of the micropores is in the range of 1 to 1.8nm<At 1%, the pore distribution of the micropores is negligible, i.e. no micropore distribution in the range of 1-1.8nm is considered, as known to the person skilled in the art. Thus, the invention is described in N2The pore diameter of the micropores in the range of 1-1.8nm in the static adsorption test refers to the proportion of the pore diameter distribution of the micropores in the range of 1-1.8nm to the total pore diameter distribution>1 percent. The microporous molecular sieve prepared by conventional direct hydrothermal synthesis has the ratio of the micropore size distribution to the total micropore size distribution in the range of 1-1.8nm<1 percent of microporous molecular sieve which is treated and modified by a common treatment and modification method and has a lower proportion of the distribution of the pore diameters of the micropores in the range of 1-1.8nm in the distribution of the pore diameters of the total micropores, namely<10%, typically<1％。
According to the invention, preferably, the molecular sieve satisfies nV/nTi ═ a, I960/I800B ═ i (a +1) nTi, where 0.1<A<10，0.2<B<1，0<I, nV is the molar weight of vanadium element in the molecular sieve, nTi is the molar weight of titanium element in the molecular sieve, I960The infrared absorption spectrum of the molecular sieve is 960cm-1Absorption intensity in the vicinity, I800The infrared absorption spectrum of the molecular sieve is 800cm-1Absorption intensity in the vicinity, preferably, 0.2<A<5，0.3<B<0.8. Therefore, the method is more favorable for the diffusion of reactant and product molecules in the catalytic oxidation reaction, not only can further improve the effective utilization rate of the oxidant, but also can more effectively modulate the selectivity of the target product.
According to the invention, it is preferred that the molecular sieve satisfies Tw/Tk＝D，0.2<D<0.5, further preferably 0.25<D<0.45, wherein, TwIs the micropore volume of the molecular sieve, TkIs the total pore volume of the molecular sieve.
According to the invention, preferably, the silicon element: titanium element: the molar ratio of the vanadium element is 100: (0.1-10): (0.01-5), more preferably silicon element: titanium element: the molar ratio of the vanadium element is 100: (0.2-5): (0.2-2.5), further preferably silicon element: titanium element: the molar ratio of the vanadium element is 100: (0.5-4): (0.5-2), more preferably 100: (1-4): (0.5-2).
According to the invention, preferably, the surface silicon-titanium ratio of the molecular sieve is not lower than the bulk silicon-titanium ratio, wherein the silicon-titanium ratio refers to the molar ratio of silicon oxide to titanium oxide; further preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2 or more; more preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2-5; still more preferably, the ratio of the surface silicon to titanium ratio to the bulk silicon to titanium ratio is 1.5 to 4.5. The surface silicon-titanium ratio is measured by adopting an X-ray photoelectron spectroscopy, and the bulk silicon-titanium ratio is measured by adopting an X-ray fluorescence spectroscopy.
The vanadium-titanium-silicon molecular sieve has the advantages of micropore size distribution in the range of 1-1.8nm, and preferably, the surface silicon-titanium ratio is not lower than the bulk silicon-titanium ratio. The invention has no special requirements on the preparation method of the vanadium-titanium-silicon molecular sieve, as long as the vanadium-titanium-silicon molecular sieve with the structure can be prepared. Preferably, the preparation method of the vanadium-titanium-silicon molecular sieve comprises the following steps:
(1) mixing a catalyst containing a titanium silicalite molecular sieve with an acid solution, carrying out first heat treatment on the obtained mixture, and separating to obtain a first solid;
(2) and mixing the first solid, the vanadium source, the alkali source and the water, and then carrying out second heat treatment.
According to the invention, the catalyst containing the titanium silicalite molecular sieve can contain fresh titanium silicalite molecular sieve and can also contain a titanium silicalite molecular sieve discharging agent. However, from the viewpoint of cost control, etc., it is preferable that the catalyst containing the titanium silicalite molecular sieve is a titanium silicalite discharging agent in order to save cost.
The titanium silicalite discharging agent may be discharged from various apparatuses using a titanium silicalite as a catalyst, for example, from an oxidation reaction apparatus using a titanium silicalite as a catalyst. The oxidation reaction may be various oxidation reactions, for example, the discharging agent of the reaction apparatus using the titanium silicalite molecular sieve as the catalyst may be one or more of a discharging agent of an ammoximation reaction apparatus, a discharging agent of a hydroxylation reaction apparatus and a discharging agent of an epoxidation reaction apparatus, specifically, may be one or more of a discharging agent of a cyclohexanone ammoximation reaction apparatus, a discharging agent of a phenol hydroxylation reaction apparatus and a discharging agent of an epoxidation reaction apparatus, and preferably, the discharging agent is a catalyst deactivated by reaction in an alkaline environment, and therefore, for the present invention, it is preferable that the discharging agent of the titanium silicalite molecular sieve is a discharging agent of a cyclohexanone ammoximation reaction apparatus (for example, deactivated titanium silicalite TS-1, powdery molecular sieve having a particle size of 100-500 nm).
In the present invention, the discharging agent is a deactivated catalyst whose activity cannot be restored to 50% of the initial activity by a conventional regeneration method such as solvent washing or calcination (the initial activity is the average activity of the catalyst within 1 hour under the same reaction conditions; for example, in the actual cyclohexanone oximation reaction, the initial activity of the catalyst is generally 95% or more).
The activity of the discharging agent varies depending on its source. Generally, the activity of the discharging agent can be 5-95% of the activity of the titanium silicalite when fresh (i.e., the activity of the fresh agent). Preferably, the activity of the discharging agent can be less than 50% of the activity of the titanium silicalite molecular sieve in a fresh state, and more preferably, the activity of the discharging agent can be 10-40% of the activity of the titanium silicalite molecular sieve in a fresh state. The activity of the titanium silicalite molecular sieve freshener is generally more than 90%, and usually more than 95%.
In the present invention, the discharging agent may be derived from an industrial deactivator or a deactivated catalyst after reaction in a laboratory.
In the invention, the discharging agent of each device is respectively measured by adopting the reaction of each device, and the discharging agent is the discharging agent provided that the activity of the discharging agent is lower than that of a fresh catalyst in the same device under the same reaction condition. As mentioned before, the activity of the discharging agent is preferably less than 50% of the activity of the fresh catalyst.
In the present invention, taking the discharging agent of the cyclohexanone ammoximation reaction device as an example, the activity is measured by the following method:
taking a TS-1 molecular sieve (prepared by the method described in Zeolite, 1992, Vol.12: 943-950), TiO22.1%) was placed in a 100mL slurry bed reactor with continuous feed and membrane separation means, and a mixture of water and 30 wt% hydrogen peroxide (water to hydrogen peroxide volume ratio of 10: 9) a mixture of cyclohexanone and tert-butanol was added at a rate of 10.5mL/h (the volume ratio of cyclohexanone to tert-butanol was 1: 2.5) adding 36 wt% ammonia water at the speed of 5.7mL/h, simultaneously adding the three material flows, continuously discharging at the corresponding speed, maintaining the reaction temperature at 80 ℃, sampling the product after the reaction is stable, analyzing the liquid phase composition by using a gas chromatography method every 1 hour, calculating the conversion rate of cyclohexanone by using the following formula, and taking the conversion rate as the activity of the titanium-silicon molecular sieve. Conversion of cyclohexanone [ (molar amount of cyclohexanone charged-molar amount of unreacted cyclohexanone)/molar amount of cyclohexanone charged]X 100%. Wherein the result of 1h is taken as the initial activity.
According to the present invention, the heat treatment is generally carried out under autogenous pressure in the case of sealing, unless otherwise specified.
According to a preferred embodiment of the present invention, the temperature of the first heat treatment is preferably 40 to 200 ℃, more preferably 50 to 180 ℃, and still more preferably 60 to 180 ℃.
According to the present invention, the time of the first heat treatment can be determined as required, and for the present invention, the time of the first heat treatment is preferably 0.5 to 360 hours, preferably 1 to 240 hours, and more preferably 2 to 120 hours.
According to the present invention, the temperature of the second heat treatment is preferably 100-.
According to the invention, the time of the second heat treatment can be determined according to requirements, and for the invention, the time of the second heat treatment is 0.5-96h, preferably 2-48h, and more preferably 6-24 h.
According to the invention, it is preferred that the method of the invention further comprises: the catalyst containing the titanium silicalite molecular sieve is roasted before being mixed with the acid solution. Preferred conditions for the firing for the present invention include: the roasting temperature is 300-800 ℃, preferably 550-600 ℃; the roasting time is 2-12h, preferably 2-4h, and the roasting atmosphere comprises air atmosphere.
According to the invention, the concentration of the acid solution is preferably >0.1mol/L, more preferably ≧ 1mol/L, further preferably 1-15 mol/L. In the invention, the main solvent of the acid solution is water, and other solvent auxiliaries can be added according to the requirement. The vanadium-titanium-silicon molecular sieve prepared in the way has more obvious characteristics such as pore volume, micropore distribution of 1-1.8nm and the like.
According to the invention, catalysts containing titanium silicalite are preferred: a vanadium source: acid: alkali source: the mass ratio of water is 100: (0.1-10): (0.005-50): (0.5-50): (20-1000), more preferably 100: (0.5-2.0): (1-15): (1-20): (100-800) the catalyst containing the titanium silicalite molecular sieve is SiO2Measured as H, acid+The alkali source is N or OH-More preferably, the mass ratio of the catalyst containing the titanium silicalite molecular sieve to the acid is 100: (2-15).
In the present invention, the titanium silicalite molecular sieve can be common titanium silicalite molecular sieves with various topological structures, and preferably, the titanium silicalite molecular sieve is selected from a titanium silicalite molecular sieve with an MFI structure, a titanium silicalite molecular sieve with an MEL structure, and a titanium silicalite molecular sieve with a BEA structure. More preferably, the titanium silicalite molecular sieve is a titanium silicalite molecular sieve of MFI structure, such as TS-1 molecular sieve.
According to the invention, the acid can be selected from a wide range of types, and can be an organic acid and/or an inorganic acid, preferably an inorganic acid; wherein, the inorganic acid can be one or more of HCl, sulfuric acid, perchloric acid, nitric acid and phosphoric acid, and is preferably phosphoric acid; the organic acid can be C1-C10 organic carboxylic acid, preferably one or more of formic acid, acetic acid, propionic acid, naphthenic acid peroxyacetic acid and peroxypropionic acid.
According to the method of the present invention, the variety of the alkali source is wide, and the alkali source can be an organic alkali source and/or an inorganic alkali source, wherein the inorganic alkali source can be ammonia, or alkali whose cation is alkali metal or alkaline earth metal, such as sodium hydroxide, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, barium hydroxide, etc., and the organic alkali source can be one or more of urea, aliphatic amine compound, aliphatic alcohol amine compound, and quaternary ammonium base compound.
In the invention, the quaternary ammonium base can be various organic quaternary ammonium bases, and the aliphatic amine can be various NH3In which at least one hydrogen is substituted with an aliphatic hydrocarbon group (preferably an alkyl group), which may be a variety of NH3Wherein at least one hydrogen is substituted with a hydroxyl-containing aliphatic hydrocarbon group (preferably an alkyl group).
Specifically, the quaternary ammonium base may be a quaternary ammonium base represented by formula II, the aliphatic amine may be an aliphatic amine represented by formula III, and the aliphatic alcohol amine may be an aliphatic alcohol amine represented by formula IV:
in the formula II, R5、R6、R7And R8Each is C1-C4Alkyl of (2) including C1-C4Straight chain alkyl of (2) and C3-C4Branched alkyl groups of (a), for example: r5、R6、R7And R8Each may be methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl or tert-butyl.
R9(NH2)n(formula III)
In the formula III, n is an integer of 1 or 2. When n is 1, R9Is C1～C6Alkyl of (2) including C1～C6Straight chain alkyl of (2) and C3-C6Such as methyl, ethyl, n-propyl, isopropyl, n-butyl, sec-butyl, isobutyl, tert-butyl, n-pentyl, neopentyl, isopentyl, tert-pentyl and n-hexyl. When n is 2, R9Is C1-C6Alkylene of (2) including C1～C6Linear alkylene of (A) and (C)3～C6Such as methylene, ethylene, n-propylene, n-butylene, n-pentylene or n-hexylene. More preferably, the aliphatic amine compound is one or more of ethylamine, n-butylamine, butanediamine and hexamethylenediamine
(HOR10)mNH(3-m)(formula IV)
In the formula IV, m are R10Are the same or different and are each C1-C4Alkylene of (2) including C1-C4Linear alkylene of (A) and (C)3-C4Branched alkylene groups of (a), such as methylene, ethylene, n-propylene and n-butylene; m is 1, 2 or 3. More preferably, the aliphatic alcohol amine compound is one or more of monoethanolamine, diethanolamine and triethanolamine.
According to a preferred embodiment of the present invention, in order to further improve the pore order of the synthesized vanadium-titanium-silicon molecular sieve, the alkali source is preferably one or more of sodium hydroxide, ammonia water, ethylenediamine, n-butylamine, butanediamine, hexamethylenediamine, monoethanolamine, diethanolamine, triethanolamine, tetraethylammonium hydroxide and tetrapropylammonium hydroxide.
Wherein, when the alkali source contains ammonia water, the mol ratio of the alkali source includes NH in molecular form3And NH in ionic form4 +The presence of ammonia.
According to the process of the present invention, preferably the alkali source is provided in the form of an alkali solution, more preferably an alkali solution having a pH > 9.
According to a preferred embodiment of the present invention, the vanadium source is preferably an oxide of vanadium, a halide of vanadium, vanadic acid (HVO)3) Orthovanadic acid (H)3VO4) Pyrovanadic acid (H)4V2O7、H3V3O9) Vanadate (corresponding salt of the aforementioned vanadate), carbonate of vanadium, nitrate of vanadium, sulfate of vanadium, phosphate of vanadium, and hydroxide of vanadium. Including but not limited to sodium vanadate, ammonium metavanadate, vanadium pentoxide, vanadium oxytrichloride, potassium metavanadate, vanadyl sulfate, vanadium acetylacetonate, vanadium tetrachloride, and the like.
The advantages of the invention are illustrated by the use of vanadium tetrachloride, vanadium phosphate salts as examples in the examples of the invention.
In a more preferred embodiment of the invention, the process of mixing the catalyst containing the titanium silicalite molecular sieve with the acid solution with the molar concentration of more than 0.1mol/L is carried out under the condition of refluxing the acid solution, and the titanium silicalite molecular sieve obtained under the condition has more obvious characteristic physicochemical characteristics.
According to the present invention, it is preferred that the method of the present invention further comprises a step of recovering a product from the heat-treated material of step (2), the step of recovering the product being a conventional method familiar to those skilled in the art, and generally means a process of filtering, washing, drying and calcining the product, without particular requirement. Wherein the drying process can be carried out at a temperature between room temperature and 200 ℃, and the roasting process can be carried out at a temperature between 300 ℃ and 800 ℃ in a nitrogen atmosphere for 0.5-6 hours and then in an air atmosphere for 3-12 hours.
According to a preferred embodiment of the invention, a titanium source is also added during the second heat treatment.
The titanium source may be selected conventionally in the art according to the process of the present invention, and for the purposes of the present invention it is preferred that the titanium source is selected from inorganic titanium salts and/or organic titanates.
In the present invention, the inorganic titanium salt is selected from various hydrolyzable titanium salts, and may be selected from TiX, for example4、TiOX2Or Ti (SO)4)2And the like, wherein X is halogen, preferably chlorine, wherein preferably the inorganic titanium salt is selected from TiCl4、Ti(SO4)2And TiOCl2One or more of。
In the present invention, the organic titanate is preferably of the formula M4TiO4Wherein M is preferably an alkyl group having 1 to 4 carbon atoms, and 4M's may be the same or different, preferably the organotitanate is selected from one or more of isopropyl titanate, n-propyl titanate, tetrabutyl titanate and tetraethyl titanate.
Titanium sulfate, tetrabutyl titanate, are used as examples in the specific embodiments of the present invention, but do not limit the scope of the present invention accordingly.
When a titanium source is added during the second heat treatment, it is preferable that the step (2) is performed as follows: and mixing a vanadium source, an alkali source and water to obtain a mixture, and mixing the mixture, a titanium source and the first solid to perform the second heat treatment.
According to the method of the invention, the mass ratio of the catalyst containing the titanium silicalite molecular sieve to the titanium source can be 100: (0.1-10), preferably 100: (0.2-5) catalyst containing titanium silicalite molecular sieve is SiO2The titanium source is calculated as TiO2And (6) counting. By adopting the preferred embodiment, the surface silicon-titanium ratio of the obtained molecular sieve material is not lower than that of bulk silicon-titanium ratio, and in addition, the obtained molecular sieve material has more micropore size distribution in the range of 1-1.8nm, and is particularly favorable for phenol oxidation reaction.
According to the method of the present invention, the catalyst may be used in an amount of a catalyst capable of performing a catalytic function. Specifically, the liquid hourly volume space velocity of the phenol can be 0.01-20h-1Preferably 0.1 to 10h-1E.g. 1-5h-1。
The oxidizing agent may be any of a variety of materials commonly used in the art that are capable of oxidizing phenol to form benzenediols. The method is particularly suitable for the occasion of oxidizing phenol by taking peroxide as an oxidant so as to prepare the benzenediol, thereby obviously improving the effective utilization rate of the peroxide and reducing the production cost of the benzenediol. The peroxide is a compound containing an-O-O-bond in the molecular structure, and can be selected from hydrogen peroxide, hydroperoxide and peracid. The hydroperoxide is a substance obtained by substituting one hydrogen atom in a hydrogen peroxide molecule with an organic group. The peracid refers to an organic oxyacid having an-O-O-bond in the molecular structure. Specific examples of the peroxide may include, but are not limited to: hydrogen peroxide, tert-butyl hydroperoxide, cumene peroxide, cyclohexyl hydroperoxide, peracetic acid and propionic acid. Preferably, the oxidizing agent is hydrogen peroxide, which further reduces the separation cost. The hydrogen peroxide may be hydrogen peroxide in various forms commonly used in the art.
From the viewpoint of further improving the safety of the method of the present invention, it is preferable to use hydrogen peroxide in the form of an aqueous solution. According to the process of the invention, when the hydrogen peroxide is provided in the form of an aqueous solution, the concentration of the aqueous hydrogen peroxide solution may be a concentration conventional in the art, for example: 20-80 wt%. Aqueous solutions of hydrogen peroxide at concentrations meeting the above requirements may be prepared by conventional methods or may be obtained commercially, for example: can be 30 percent by weight of hydrogen peroxide, 50 percent by weight of hydrogen peroxide or 70 percent by weight of hydrogen peroxide which can be obtained commercially.
According to the process of the present invention, preferably, the molar ratio of phenol to oxidant is 1: (0.1-10), more preferably 1: (0.2-5), more preferably 1: (1-4).
According to the process of the present invention, preferably, said contacting is carried out in the presence of at least one solvent. Generally, the solvent may be selected from at least one of water, C1-C6 alcohols, C3-C8 ketones, C2-C8 nitriles, and C2-C8 carboxylic acids. Specific examples of the solvent may include, but are not limited to: water, methanol, ethanol, acetic acid, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone and acetonitrile. Preferably, the solvent is acetic acid, acetone, methanol and water, more preferably methanol and/or water. By adopting the preferred embodiment, the mixing degree of reactants in the reaction system can be improved, the diffusion can be enhanced, and the intensity of the reaction can be adjusted more conveniently.
Generally, the mass ratio of solvent to phenol may be (1-100): 1, preferably (1-25): 1, e.g. (7-20): 1.
according to the process of the present invention, the solvent may be fed into the fixed bed reactor by various methods commonly used in the art so that the contacting of the phenol and the oxidant with the catalyst is carried out in the presence of the solvent. For example: the phenol, solvent and oxidant may be fed into the fixed bed reactor at the same location.
According to the process of the present invention, preferably, the process further comprises feeding at least one acid to the fixed bed reactor, said acid being added in an amount such that the pH of the liquid mixture in contact with the catalyst is between 3 and 5.5, preferably between 4 and 5.5. Thus, the selectivity of hydroquinone can be obviously improved, and higher phenol conversion rate and effective utilization rate of an oxidant can be obtained; and, compared with no acid addition, under the same conditions, even at lower temperature, high phenol conversion rate, oxidant effective utilization rate and hydroquinone selectivity can be obtained. The pH of the liquid mixture means the pH of the liquid mixture measured at 25 ℃ and 1 atm.
The type of acid may be conventionally selected so long as the acid does not chemically interact with the components of the reaction system (including the reactants, optional solvent, and reaction products) under the oxidation reaction conditions. Generally, the acid may be an inorganic acid and/or an organic acid, such as one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, formic acid, and acetic acid, and is preferably hydrochloric acid and/or sulfuric acid. Either pure acid or an aqueous acid solution may be used. The mixing of the acid with the phenol and the oxidizing agent and other components of the liquid mixture (e.g., solvent) can be carried out either in a fixed reactor or outside the fixed reactor.
According to the method of the present invention, the oxidation reaction conditions are not particularly limited and may be conventionally selected in the art. Generally, the oxidation reaction conditions include: the temperature may be from 10 to 180 ℃, preferably from 20 to 150 ℃, more preferably from 30 to 90 ℃; the pressure may be in the range of 0 to 2MPa, preferably 0.1 to 1.5MPa, in terms of gauge pressure.
The process according to the invention may also comprise a step of separating the benzenediol from the mixture obtained. The hydroquinone can be separated from the resulting mixture by various methods commonly used in the art, and the present invention is not particularly limited.
The present invention will be described in detail with reference to examples.
In the following examples and comparative examples, the reagents used were all commercially available analytical grade reagents, and the pressures were measured as gauge pressures.
The discharging agents of the following preparation examples and preparation examples were obtained as follows, and the activity of titanium silicalite molecular sieves (including the discharging agent of titanium silicalite molecular sieves and the freshness agent of titanium silicalite molecular sieves) was measured by the following method.
Taking a TS-1 molecular sieve (prepared by the method described in Zeolite, 1992, Vol.12: 943-950), TiO22.1%) was placed in a 100mL slurry bed reactor with continuous feed and membrane separation means, and a mixture of water and 30 wt% hydrogen peroxide (water to hydrogen peroxide volume ratio of 10: 9) a mixture of cyclohexanone and tert-butanol was added at a rate of 10.5mL/h (the volume ratio of cyclohexanone to tert-butanol was 1: 2.5) adding 36 wt% ammonia water at the speed of 5.7mL/h, simultaneously adding the three material flows, continuously discharging at the corresponding speed, maintaining the reaction temperature at 80 ℃, sampling the product after the reaction is stable, analyzing the liquid phase composition by using a gas chromatography method every 1 hour, calculating the conversion rate of cyclohexanone by using the following formula, and taking the conversion rate as the activity of the titanium-silicon molecular sieve. Conversion of cyclohexanone [ (molar amount of cyclohexanone charged-molar amount of unreacted cyclohexanone)/molar amount of cyclohexanone charged]×100％。
The cyclohexanone conversion, measured for the first time, i.e. 1h, was its initial activity, which was 99.5%. After a period of about 168 hours, the cyclohexanone conversion rate is reduced from the initial 99.5% to 50%, the catalyst is separated and regenerated by roasting (roasting at 570 ℃ for 4 hours in air atmosphere), and then the catalyst is continuously used in cyclohexanone ammoximation reaction, the step is repeatedly carried out until the activity after regeneration is lower than 50% of the initial activity, at the moment, the inactivated ammoximation catalyst sample is used as the discharging agent of the invention, and the discharging agents SH-1 (the activity is 50%), SH-2 (the activity is 40%), SH-3 (the activity is 25%) and SH-4 (the activity is 10%) are sequentially obtained according to the method.
The pore volume and pore size distribution of the sample were measured on a Micromeritics ASAP2405 static nitrogen adsorption apparatus, and the specific data are shown in Table 1.
The elemental compositions of the samples, such as vanadium and silicon, were measured on a 3271E model X-ray fluorescence spectrometer, manufactured by Nippon chemical and mechanical Co., Ltd., and the data are shown in Table 1.
In the present invention, the surface Si/Ti ratio was measured by an ESCALB 250 type X-ray photoelectron spectrometer manufactured by Thermo Scientific, and the bulk Si/Ti ratio was measured by a 3271E type X-ray fluorescence spectrometer manufactured by Nippon chemical industries, Ltd., and the surface Si/Ti ratio/bulk Si/Ti ratio is shown in Table 1.
The Fourier transform infrared absorption spectrum of the sample is measured on a Nicolet 8210 type Fourier infrared spectrometer, KBr tablets are adopted under vacuum (the sample accounts for 1wt percent), and the test range is 400--1。
In the following examples and comparative examples, the composition of the reaction mixture obtained by the contact was measured by gas chromatography, and on the basis of this, the phenol conversion, the effective utilization of the oxidizing agent and the selectivity for hydroquinone were calculated by the following formulas, respectively.
Phenol conversion (%) × 100 [ (% by mole of phenol added-mole of unreacted phenol)/mole of phenol added ];
the effective oxidant utilization ratio (%) × 100% of molar amount of diphenol produced by the reaction/(molar amount of oxidant added-molar amount of unreacted oxidant);
hydroquinone selectivity (%) × 100% in terms of molar amount of hydroquinone produced by the reaction/(molar amount of phenol added-molar amount of unreacted phenol).
Preparation examples 1-15 are illustrative of the molecular sieves of the present invention and the methods for their preparation.
Preparation of example 1
The deactivated cyclohexanone oximation catalyst SH-2 and 1m are firstly used for oximation at normal temperature (20 ℃, the same for the other preparation examples and preparation examples) and normal pressure (0.1MPa, the same for the other preparation examples and preparation examples)Mixing and pulping the ol/L hydrochloric acid aqueous solution, and then mixing and stirring the mixed pulp at 80 ℃ for 12 hours; after solid-liquid separation, mixing the solid, vanadium source ammonium metavanadate, titanium source titanium sulfate and sodium hydroxide aqueous solution (pH is 12), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at 170 ℃, wherein the material quality composition is inactivated cyclohexanone oximation catalyst: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 1: 1: 10: 5: 250, deactivated cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-The titanium source is calculated as TiO2And (6) counting. And filtering the obtained product, washing with water, drying at 110 ℃ for 120min, and then roasting at 550 ℃ for 3h to obtain the molecular sieve S-1, wherein an XRD (X-ray diffraction) crystal phase diagram of the molecular sieve S-1 is consistent with that of preparation example 1, which indicates that the obtained molecular sieve has an MFI structure.
Preparation of example 2
Firstly, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-3 and 5mol/L hydrochloric acid solution at normal temperature and normal pressure, and then mixing and stirring the mixed slurry at 60 ℃ for 1 h; after solid-liquid separation, mixing solid, vanadium tetrachloride as a vanadium source, tetrabutyl titanate as a titanium source and tetrapropyl ammonium hydroxide aqueous solution (pH is 10), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at 150 ℃, wherein the material comprises the following components in mass: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 2: 0.5: 15: 15: 200 deactivated cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-The titanium source is calculated as TiO2And (6) counting. The product was then recovered according to the procedure of preparation example 1 to obtain molecular sieve S-2, the XRD crystallography of which is consistent with that of preparation example 1.
Preparation of example 3
Under normal temperature and normal pressure, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-4 and 8mol/L nitric acid aqueous solution, and then mixing and stirring the mixed slurry at 100 ℃ for 2 hours; after solid-liquid separation, mixing the solid, vanadium source sodium vanadate, titanium source titanium sulfate and sodium hydroxide aqueous solution (pH is 14), putting the mixed solution into a stainless steel sealed reaction kettle, and carrying out hydrothermal treatment for 18h at 140 ℃, wherein the material quality composition is an inactivated cyclohexanone oximation catalyst:a titanium source: a vanadium source: acid: alkali: 100 parts of water: 5: 2: 10: 15: 600 deactivated Cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-The titanium source is calculated as TiO2And (6) counting. The product was then recovered according to the procedure of preparation example 1 to obtain molecular sieve S-3, the XRD crystal phase diagram of which was identical to that of preparation example 1.
Preparation of example 4
Firstly, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-1 and 5mol/L sulfuric acid aqueous solution at normal temperature and normal pressure, and then mixing and stirring the mixed slurry at 120 ℃ for 1 h; after solid-liquid separation, mixing the solid, vanadium source ammonium metavanadate, titanium source titanium sulfate and n-butylamine aqueous solution (pH is 12.0), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at 170 ℃, wherein the material composition by mass is inactivated cyclohexanone oximation catalyst: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 1: 1: 2: 2: 50, deactivated Cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated by alkali in N and titanium source in TiO2And (6) counting. And filtering the obtained product, washing with water, drying at 110 ℃ for 120min, and then roasting at 550 ℃ for 3h to obtain the molecular sieve S-4, wherein an XRD crystal phase diagram of the molecular sieve S-4 is consistent with that of preparation example 1.
Preparation of example 5
Firstly, mixing and pulping deactivated cyclohexanone oximation catalyst SH-2 and 2mol/L perchloric acid aqueous solution at normal temperature and normal pressure, and then mixing and stirring the mixed pulp at 70 ℃ for 5 hours; after solid-liquid separation, mixing the solid, vanadium source ammonium metavanadate, titanium source titanium sulfate and ammonia water (pH is 11), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 12 hours at 170 ℃, wherein the material quality composition is inactivated cyclohexanone oximation catalyst: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 10: 1: 5: 20: 100, deactivated Cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated by alkali in N and titanium source in TiO2And (6) counting. And filtering the obtained product, washing with water, drying at 110 ℃ for 120min, and then roasting at 550 ℃ for 3h to obtain the molecular sieve S-5, wherein an XRD crystal phase diagram of the molecular sieve S-5 is consistent with that of the preparation example 1.
Preparation of example 6
Firstly, mixing and pulping the inactivated cyclohexanone oximation catalyst SH-2 and 15mol/L phosphoric acid aqueous solution at normal temperature and normal pressure, and then mixing and stirring the mixed slurry at 180 ℃ for 3 hours; after solid-liquid separation, mixing the solid, vanadium source potassium metavanadate, titanium source titanium sulfate and sodium hydroxide aqueous solution (pH is 14), putting the mixed solution into a stainless steel sealed reaction kettle, and treating for 6 hours at 150 ℃, wherein the material quality composition is inactivated cyclohexanone oximation catalyst: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 5: 2: 10: 15: 600 deactivated Cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-The titanium source is calculated as TiO2And (6) counting. The product was then recovered according to the procedure of preparation example 1 to obtain molecular sieve S-6, the XRD crystallography of which is consistent with that of preparation example 1.
Preparation of example 7
Molecular sieves were prepared according to the method of preparative example 3, except that in the material mass composition, the deactivated cyclohexanone oximation catalyst: acid 100: 5, obtaining the molecular sieve S-7, wherein the XRD crystal phase diagram of the obtained sample is consistent with that of the preparation example 1.
Preparation of example 8
Molecular sieves were prepared according to the method of preparative example 3, except that in the material mass composition, the deactivated cyclohexanone oximation catalyst: acid 100: 100, obtaining the molecular sieve S-8, wherein the XRD crystal phase diagram of the obtained sample is consistent with that of the preparation example 1.
Preparation of example 9
The molecular sieve was prepared according to the method of preparation example 2, except that the discharging agent SH-3 was calcined and then subjected to subsequent pulping, heat treatment processes, wherein the calcination conditions included: and (3) roasting for 4 hours at 570 ℃ in an air atmosphere to obtain the molecular sieve S-9, wherein the XRD crystal phase diagram of the obtained sample is consistent with that of preparation example 1, and the XRD crystal phase diagram of the obtained sample is consistent with that of preparation example 1.
Preparation of example 10
A molecular sieve was prepared according to the method of preparation example 2 except that SH-1 was used as a discharging agent and the other conditions were the same, to obtain molecular sieve S-10, and the XRD crystal phase diagram of the obtained sample was identical to that of preparation example 1.
Preparation of example 11
A molecular sieve was prepared according to the method of preparation example 2, except that the order of addition of the starting materials was changed:
mixing and pulping inactivated cyclohexanone oximation catalyst SH-3 and 5mol/L hydrochloric acid solution at normal temperature and normal pressure, then mixing and stirring the mixed slurry at 60 ℃ for 1h, carrying out solid-liquid separation to obtain a solid, mixing vanadium source ammonium metavanadate and tetrapropyl ammonium hydroxide aqueous solution (the pH value is 10) to obtain a mixed solution, mixing the solid, tetrabutyl titanate and the mixed solution, putting the mixed solution into a stainless steel sealed reaction kettle, and treating the mixed solution at 150 ℃ for 12h, wherein the material composition by mass is the inactivated cyclohexanone oximation catalyst: a titanium source: a vanadium source: acid: alkali: 100 parts of water: 2: 0.5: 15: 15: 200 deactivated cyclohexanone oximation catalyst with SiO2Measured as H, acid+Calculated as OH, base-The titanium source is calculated as TiO2And (6) counting. The product was then recovered according to the procedure of preparation example 1 to obtain molecular sieve S-11, the XRD crystal phase diagram of which was identical to that of preparation example 1.
Preparation of example 12
A molecular sieve was prepared by the method of preparation example 2, except that tetrabutyl titanate of titanium source was not added during the second heat treatment. The product was then recovered according to the procedure of preparation example 1 to obtain molecular sieve S-12, the XRD crystallography of which is consistent with that of preparation example 1.
Preparation of comparative example 1
The preparation comparative example illustrates the process of preparing a titanium silicalite molecular sieve sample without vanadium by using the conventional silicon ester as a silicon source through hydrothermal crystallization.
Tetraethyl orthosilicate, titanium isopropoxide and tetrapropylammonium hydroxide are mixed, and proper amount of distilled water is added for stirring and mixing, wherein the molar composition in a reaction system is tetraethyl orthosilicate: titanium isopropoxide: tetrapropylammonium hydroxide: 100 parts of water: 5: 10: 200, wherein tetraethyl orthosilicate is SiO2Counting; hydrolyzing at normal pressure and 60 deg.C for 1.0h, stirring at 75 deg.C for 3h, placing the mixed solution in a stainless steel sealed reaction kettle, and standing at 170 deg.C for 3d to obtain crystallized product mixture; filtering the mixture, washing with water, and drying at 110 deg.C for 60min to obtain molecular sieve powderAnd roasting at 550 ℃ for 3h to obtain the titanium silicalite molecular sieve D-1 which is directly crystallized by hydrothermal method, wherein the XRD crystal phase of the titanium silicalite molecular sieve D-1 is MFI structure.
Preparation of example 13
This preparation example illustrates the conventional process for preparing a sample of a titanium silicalite molecular sieve containing vanadium by hydrothermal crystallization using a silicalite as a silicon source.
Tetraethyl orthosilicate, ammonium metavanadate, titanium isopropoxide and tetrapropylammonium hydroxide are mixed, and a proper amount of distilled water is added for stirring and mixing, wherein the molar composition in a reaction system is tetraethyl orthosilicate: titanium isopropoxide: ammonium metavanadate: tetrapropylammonium hydroxide: 100 parts of water: 5: 2: 10: 200, wherein tetraethyl orthosilicate is SiO2Counting; hydrolyzing at normal pressure and 60 deg.C for 1.0h, stirring at 75 deg.C for 3h, placing the mixed solution in a stainless steel sealed reaction kettle, and standing at 170 deg.C for 3d to obtain crystallized product mixture; filtering the mixture, washing with water, drying at 110 ℃ for 60min to obtain molecular sieve raw powder, and roasting at 550 ℃ for 3h to obtain the vanadium-titanium-silicon molecular sieve S-13 which is directly crystallized by hydrothermal method, wherein an XRD (X-ray diffraction) crystal phase diagram of the vanadium-titanium-silicon molecular sieve S-13 is consistent with that of preparation example 1 and has an MFI structure.
Preparation of example 14
This preparation example illustrates the impregnation of a vanadium-loaded sample using the titanium silicalite molecular sieve prepared in preparation comparative example 1.
Mixing the titanium silicalite molecular sieve prepared in the preparation comparative example 1 with an ammonium metavanadate aqueous solution, wherein the mass ratio of the titanium silicalite molecular sieve to the ammonium metavanadate to the water is 10:2:25, stirring for 6 hours at normal pressure and 60 ℃, filtering the mixture, washing with water, drying for 60 minutes at 110 ℃, and roasting for 3 hours at 550 ℃ to obtain the titanium silicalite molecular sieve S-14 loaded with vanadium, wherein the XRD crystalline phase of the titanium silicalite molecular sieve S-14 is of an MFI structure.
Preparation of example 15
This preparation illustrates the impregnation of a vanadium-loaded sample with the discharging agent SH-2.
Mixing the discharging agent SH-2 with an ammonium metavanadate aqueous solution, wherein the mass ratio of the titanium silicalite molecular sieve to the ammonium metavanadate to water is 10:0.5:10, stirring for 12h at normal pressure and 40 ℃, then filtering the mixture, washing with water, drying for 60min at 110 ℃, and roasting for 3h at 550 ℃ to obtain the titanium silicalite molecular sieve S-15 loaded with vanadium, wherein the XRD crystalline phase of the titanium silicalite molecular sieve S-15 is of an MFI structure.
TABLE 1
In table 1:
a is nV/nTi, nV is the amount of vanadium element of the molecular sieve, and nTi is the amount of titanium element of the molecular sieve;
B＝I960/I800，I960the infrared absorption spectrum of the molecular sieve is 960cm-1Absorption intensity in the vicinity, I800The infrared absorption spectrum of the molecular sieve is 800cm-1Absorption strength in the vicinity;
C＝X1-1.8/X0.4-0.9，X0.4-0.9the ratio of the pore diameter of the micropores of the molecular sieve in the range of 0.4-0.9nm to the distribution quantity of the total pore diameter, X1-1.8The proportion of the micropore diameter of the molecular sieve in the range of 1-1.8nm to the total micropore diameter distribution amount is adopted;
D＝Tw/Tk，Twis the micropore volume of the molecular sieve, TkIs the total pore volume of the molecular sieve;
silicon: titanium: vanadium refers to the silicon element: titanium element: molar ratio of vanadium element.
Example 1
The molecular sieve S-1 prepared in preparation example 1 was pelletized into 10-20 mesh particles, and charged into a catalyst bed of a stainless steel fixed bed microreactor (a reactor containing a layer of catalyst, with a loading of 10mL, and a reactor height to diameter ratio of 15), phenol, an oxidant, and methanol as a solvent were fed into the reactor from the bottom of the reactor to contact the catalyst bed at a temperature of 60 ℃ and a pressure of 0.5MPa, and a reaction mixture was obtained from the top of the reactor. Wherein the oxidant is 30 weight percent of hydrogen peroxide, and the molar ratio of phenol to the oxidant calculated by hydrogen peroxide is 1: 1.5, the mass ratio of phenol to methanol as solvent is 1: 7, the liquid hourly space velocity of the phenol is 2.5h-1。
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 2
The molecular sieve S-2 prepared in preparation example 2 was formed into 10-20 mesh particles by tabletting, and charged into a catalyst bed layer of a stainless steel fixed bed microreactor (a reactor containing a layer of catalyst, the loading was 10mL, and the reactor height-diameter ratio was 15), and phenol, an oxidant and methanol as a solvent were fed into the reactor from the bottom of the reactor to contact the catalyst bed layer under a temperature of 50 ℃ and a pressure of 1MPa, to obtain a reaction mixture from the top of the reactor. Wherein the oxidant is 30 weight percent of hydrogen peroxide, and the molar ratio of phenol to the oxidant calculated by hydrogen peroxide is 1: 1, the mass ratio of phenol to methanol as a solvent is 1: 20, the liquid hourly space velocity of the phenol is 5h-1。
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 3
The molecular sieve S-3 prepared in preparation example 3 was formed into 10-20 mesh particles by tabletting, and charged into a catalyst bed layer of a stainless steel fixed bed microreactor (a reactor containing a layer of catalyst, the loading was 10mL, and the reactor height-diameter ratio was 15), and phenol, an oxidant and methanol as a solvent were fed into the reactor from the bottom of the reactor to contact the catalyst bed layer under a temperature of 65 ℃ and a pressure of 0.6MPa, to obtain a reaction mixture from the top of the reactor. Wherein the oxidant is 30 weight percent of hydrogen peroxide, and the molar ratio of phenol to the oxidant calculated by hydrogen peroxide is 1: and 4, the mass ratio of the phenol to the methanol used as the solvent is 1: 14, the liquid hourly space velocity of the phenol is 1h-1。
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Examples 4 to 12
The procedure of example 1 was followed, except that the molecular sieve S-1 obtained in production example 1 was replaced with the molecular sieves S-4 to S-12 obtained in production examples 4-12, respectively, of equal mass.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Comparative example 1
The procedure of example 1 was followed except that the molecular sieve S-1 obtained in production example 1 was replaced with the molecular sieve D-1 obtained in production comparative example 1 of equal mass.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Examples 13 to 15
The procedure of example 1 was followed, except that the molecular sieve S-1 obtained in production example 1 was replaced with the molecular sieves S-13 to S-15 obtained in production examples 13 to 15, respectively, of equal mass.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 16
The process of example 1 was followed except that hydrochloric acid (28 wt% aqueous solution) was fed into the reactor from the bottom thereof in such an amount that the pH of the liquid-phase mixture of phenol, oxidizing agent and solvent was 5.5 (6.8).
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 17
The process of example 16 was followed except that hydrochloric acid was used in an amount such that the pH of the liquid-phase mixture formed from phenol, the oxidizing agent and the solvent was 4.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 18
The process of example 16 was followed except that hydrochloric acid was used in an amount such that the pH of the liquid-phase mixture formed from phenol, the oxidizing agent and the solvent was 2.5.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
Example 19
The procedure was followed as in example 16, except that hydrochloric acid was replaced with aqueous ammonia (concentration of 30% by weight) in an amount such that the pH of the liquid-phase mixture formed from phenol, the oxidizing agent and the solvent was 8.5.
And (3) carrying out gas chromatography analysis on reaction mixtures obtained 0.5h and 12h after the reaction starts, and calculating the conversion rate of phenol, the effective utilization rate of an oxidant and the selectivity of hydroquinone. The results are listed in table 2.
TABLE 2
It can be seen from the results in table 2 that the method for preparing hydroquinone provided by the present invention can improve the conversion rate of phenol, the effective utilization rate of the oxidant, the selectivity of hydroquinone and the stability of the catalyst. In addition, the optimized vanadium-titanium-silicon molecular sieve can further improve the conversion rate of phenol, the effective utilization rate of an oxidant, the selectivity of hydroquinone and the stability of a catalyst; by adopting the scheme of adjusting the pH of the liquid mixture by adding acid, the conversion rate of phenol, the effective utilization rate of the oxidant, the selectivity of hydroquinone and the stability of the catalyst can be further improved.
The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, numerous simple modifications can be made to the technical solution of the invention, including combinations of the specific features in any suitable way, and the invention will not be further described in relation to the various possible combinations in order to avoid unnecessary repetition. Such simple modifications and combinations should be considered within the scope of the present disclosure as well.
Claims (10)
1. A process for preparing a benzenediol, the process comprising: under the condition of oxidation reaction, phenol, at least one oxidant and a catalyst are contacted in a fixed bed reactor, wherein the catalyst contains a vanadium-titanium-silicon molecular sieve.
2. The method of claim 1, wherein the contacting is performed in the presence of at least one solvent; the mass ratio of the solvent to the phenol is (1-100): 1;
preferably, the solvent is at least one selected from water, C1-C6 alcohol, C3-C8 ketone, C2-C8 nitrile and C2-C8 carboxylic acid, and further preferably acetic acid, acetone, methanol and water.
3. The method of claim 1 or 2,
the molar ratio of phenol to oxidant is 1: (0.1-10), preferably 1: (0.2-5); and/or
The liquid hourly space velocity of the phenol is 0.01-20h-1。
4. The process according to any one of claims 1 to 3, further comprising feeding at least one acid to the fixed bed reactor in an amount such that the pH of the liquid mixture in contact with the catalyst is in the range of from 3 to 5.5, preferably from 4 to 5.5.
5. The method of any one of claims 1 to 4, wherein the vanadium titanium silicalite molecular sieve comprises: vanadium, titanium, silicon and oxygen, wherein the molecular sieve satisfies X1-1.8/X0.4-0.9＝C，0.2<C<1, preferably 0.25<C<0.85，X0.4-0.9The ratio of the pore diameter of the micropores of the molecular sieve in the range of 0.4-0.9nm to the distribution quantity of the total pore diameter, X1-1.8The proportion of the micropore diameter of the molecular sieve in the range of 1-1.8nm to the total micropore diameter distribution amount is adopted;
preferably, the molecular sieve satisfies nV/nTi ═ a, I960/I800B ═ i (a +1) nTi, where 0.1<A<10，0.2<B<1，0<I, nV is the molar weight of vanadium element in the molecular sieve, nTi is the molar weight of titanium element in the molecular sieve, I960The infrared absorption spectrum of the molecular sieve is 960cm-1Absorption intensity in the vicinity, I800The infrared absorption spectrum of the molecular sieve is 800cm-1Absorption intensity in the vicinity, preferably, 0.2<A<5，0.3<B<0.8；
Preferably, the molecular sieve satisfies Tw/Tk＝D，0.2<D<0.5，TwIs the micropore volume of the molecular sieve, TkIs the total pore volume of the molecular sieve, further preferably, 0.25<D<0.45；
Preferably, the molecular sieve has a silicon element: titanium element: the molar ratio of the vanadium element is 100: (0.1-10): (0.01-5), more preferably 100: (0.2-5): (0.2-2.5);
preferably, the surface silicon-titanium ratio of the molecular sieve is not lower than the bulk silicon-titanium ratio, which means the molar ratio of silicon oxide to titanium oxide, and further preferably, the ratio of the surface silicon-titanium ratio to the bulk silicon-titanium ratio is 1.2-5, preferably 1.5-4.5.
6. The method of claim 5, wherein the vanadium-titanium-silicon molecular sieve is prepared by a method comprising the following steps:
(1) mixing a catalyst containing a titanium silicalite molecular sieve with an acid solution, carrying out first heat treatment on the obtained mixture, and separating to obtain a first solid;
(2) mixing the first solid, a vanadium source, an alkali source and water, and then carrying out second heat treatment;
preferably, the catalyst containing the titanium silicalite molecular sieve is a discharging agent of an ammoximation reaction device;
preferably, the temperature of the first heat treatment is 40-200 ℃; the temperature of the second heat treatment is 100-200 ℃;
preferably, the time of the first heat treatment is 0.5-360 h; the time of the second heat treatment is 0.5-96 h.
7. The method of claim 6, wherein the concentration of the acid solution>0.1 mol/L; catalyst containing titanium silicalite: a vanadium source: acid: alkali source: the mass ratio of water is 100: (0.1-10): (0.005-50): (0.5-50): (20-1000) in which the catalyst containing titanium-silicon molecular sieve is SiO2Measured as H, acid+The alkali source is N or OH-Counting;
preferably, the acid is an organic acid and/or an inorganic acid; the alkali source is one or more of ammonia, aliphatic amine, aliphatic alcohol amine and quaternary ammonium hydroxide; the vanadium source is one or more of vanadium oxide, vanadium acid, vanadate, vanadium halide, vanadium carbonate, vanadium nitrate, vanadium sulfate, vanadium phosphate and vanadium hydroxide.
8. The method according to claim 6 or 7, wherein a titanium source is added in the second heat treatment process, and the titanium source is selected from inorganic titanium salt and/or organic titanate;
preferably, step (2) is performed as follows: mixing a vanadium source, an alkali source and water to obtain a mixture, and mixing the mixture, a titanium source and the first solid to perform the second heat treatment;
further preferably, the mass ratio of the catalyst containing the titanium silicalite molecular sieve to the titanium source is 100: (0.1-10), wherein the catalyst containing titanium silicalite molecular sieve is SiO2The titanium source is calculated as TiO2And (6) counting.
9. The method of any one of claims 6 to 8, wherein the catalyst comprising the titanium silicalite is a discharge agent of an ammoximation reaction apparatus.
10. The method of any of claims 1-9, wherein the oxidation reaction conditions comprise: the temperature is 10-180 ℃, and the pressure is 0-2MPa in gauge pressure.
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| CN107986294A (en) * | 2016-10-27 | 2018-05-04 | 中国石油化工股份有限公司 | A kind of Titanium Sieve Molecular Sieve containing vanadium and its synthetic method and application |
| CN110316739A (en) * | 2018-03-30 | 2019-10-11 | 中国石油化工股份有限公司 | Vanadium Titanium Sieve Molecular Sieve and its preparation method and application and phenol hydroxylation method |
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- 2018-07-17 CN CN201810783007.3A patent/CN110724036B/en active Active
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107986294A (en) * | 2016-10-27 | 2018-05-04 | 中国石油化工股份有限公司 | A kind of Titanium Sieve Molecular Sieve containing vanadium and its synthetic method and application |
| CN110316739A (en) * | 2018-03-30 | 2019-10-11 | 中国石油化工股份有限公司 | Vanadium Titanium Sieve Molecular Sieve and its preparation method and application and phenol hydroxylation method |
Non-Patent Citations (1)
| Title |
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| PAULA BRANDÃO ET AL.: "Synthesis, characterization and catalytic activity of vanadium-containing ETS-10", 《STUDIES IN SURFACE SCIENCE AND CATALYSIS》 * |
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