CN116532137A - Spherical esterification catalyst, preparation method thereof and application of spherical esterification catalyst in n-butyl acetate synthesis reaction - Google Patents

Spherical esterification catalyst, preparation method thereof and application of spherical esterification catalyst in n-butyl acetate synthesis reaction Download PDF

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CN116532137A
CN116532137A CN202210090090.2A CN202210090090A CN116532137A CN 116532137 A CN116532137 A CN 116532137A CN 202210090090 A CN202210090090 A CN 202210090090A CN 116532137 A CN116532137 A CN 116532137A
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spherical
catalyst
composite carrier
mcm
alumina
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刘红梅
张蓝溪
刘东兵
徐向亚
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Sinopec Beijing Chemical Research Institute Co ltd
China Petroleum and Chemical Corp
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Sinopec Beijing Chemical Research Institute Co ltd
China Petroleum and Chemical Corp
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/50—Catalysts, in general, characterised by their form or physical properties characterised by their shape or configuration
    • B01J35/51—Spheres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J27/00—Catalysts comprising the elements or compounds of halogens, sulfur, selenium, tellurium, phosphorus or nitrogen; Catalysts comprising carbon compounds
    • B01J27/14—Phosphorus; Compounds thereof
    • B01J27/186—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J27/188—Phosphorus; Compounds thereof with arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium with chromium, molybdenum, tungsten or polonium
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    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/7038—MWW-type, e.g. MCM-22, ERB-1, ITQ-1, PSH-3 or SSZ-25
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J29/00—Catalysts comprising molecular sieves
    • B01J29/04—Catalysts comprising molecular sieves having base-exchange properties, e.g. crystalline zeolites
    • B01J29/06—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof
    • B01J29/70—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65
    • B01J29/78—Crystalline aluminosilicate zeolites; Isomorphous compounds thereof of types characterised by their specific structure not provided for in groups B01J29/08 - B01J29/65 containing arsenic, antimony, bismuth, vanadium, niobium, tantalum, polonium, chromium, molybdenum, tungsten, manganese, technetium or rhenium
    • B01J29/7876—MWW-type, e.g. MCM-22, ERB-1, ITQ-1, PSH-3 or SSZ-25
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/61—Surface area
    • B01J35/617—500-1000 m2/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/63—Pore volume
    • B01J35/635—0.5-1.0 ml/g
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/64—Pore diameter
    • B01J35/643—Pore diameter less than 2 nm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/64—Pore diameter
    • B01J35/647—2-50 nm
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J35/00—Catalysts, in general, characterised by their form or physical properties
    • B01J35/60—Catalysts, in general, characterised by their form or physical properties characterised by their surface properties or porosity
    • B01J35/66—Pore distribution
    • B01J35/69—Pore distribution bimodal
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C67/00—Preparation of carboxylic acid esters
    • C07C67/08—Preparation of carboxylic acid esters by reacting carboxylic acids or symmetrical anhydrides with the hydroxy or O-metal group of organic compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J2229/00—Aspects of molecular sieve catalysts not covered by B01J29/00
    • B01J2229/30—After treatment, characterised by the means used
    • B01J2229/42—Addition of matrix or binder particles

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Abstract

The invention relates to the field of fine chemical engineering, and discloses a spherical esterification catalyst, a preparation method thereof and application thereof in n-butyl acetate synthesis reaction. The spherical esterification catalyst comprises a spherical composite carrier, alumina and an MCM-22 molecular sieve which are loaded on the spherical composite carrier, wherein the content of the spherical composite carrier is 40-80 wt% and the content of phosphotungstates is 20-60 wt% based on the total weight of the spherical esterification catalyst. The catalyst is used for the synthesis reaction of n-butyl acetate, and can obtain higher acetic acid conversion rate and n-butyl acetate selectivity.

Description

Spherical esterification catalyst, preparation method thereof and application of spherical esterification catalyst in n-butyl acetate synthesis reaction
Technical Field
The invention relates to the field of fine chemical engineering, in particular to a spherical esterification catalyst, a preparation method thereof and application thereof in n-butyl acetate synthesis reaction.
Background
N-butyl acetate is an important organic chemical product, and has good solubility to ethyl cellulose, polyvinyl acetate, polyvinyl chloride, chlorinated rubber, gutta percha, polyacrylate, polymethyl methacrylate and many natural resins such as rosin, tannin extract, manila gum, dammar resin and the like. The n-butyl acetate can be used as an excellent organic solvent, and can be widely used in the fields of collodion, nitrocellulose, varnish, artificial leather, medicine, plastic processing and the like, and can also be used as industrial spice or edible essence. Along with the enhancement of environmental awareness, acetate becomes a substitute for benzene, toluene, methyl hexanone and other organic solvents. The traditional industrial process for producing n-butyl acetate uses concentrated sulfuric acid as a catalyst to catalyze the esterification reaction of acetic acid and n-butanol to produce n-butyl acetate. The concentrated sulfuric acid catalyst has the advantages of low price, but the use of the concentrated sulfuric acid as the catalyst has serious environmental pollution, high requirements on equipment materials, more side reactions, more byproducts and difficult separation and purification of the obtained product. Thus, the use of inorganic acid catalysts for esterification reactions is gradually eliminated. In recent years, the production process of acetate in China is continuously developed, the production capacity of acetate is continuously improved, solid acid or cation exchange resin is used as a catalyst for the synthesis reaction of n-butyl acetate, and the catalyst is greatly developed and is widely applied to industrial production. The solid catalyst has the advantages of good stability, high selectivity, low cost, easy separation and the like in the esterification reaction. However, such catalysts have a relatively slow reaction rate and a relatively low ester yield. The cation exchange resin has the advantages of good stability, high selectivity, low cost, easy separation and the like in the esterification reaction. However, the cation exchange resin itself has poor heat resistance (generally suitable for esterification reactions at temperatures below 150 ℃), small specific surface area and pore volume, and is susceptible to swelling, poor in reactivity as an esterification catalyst, and low in ester yield.
Compared with the resin catalyst, the hydrogen zeolite molecular sieve (such as H beta molecular sieve) has a certain pore canal structure and surface acidity, and is suitable for catalyzing esterification reaction of small molecules. However, the zeolite molecular sieve has small pore size (0.5-0.7 nm), and can inhibit the diffusion of macromolecular products in the reaction; and the zeolite molecular sieve has less acid sites on the surface and lower catalytic esterification efficiency. Therefore, it is not practical to directly apply the hydrogen form zeolite molecular sieve material to the synthesis reaction of n-butyl acetate. Along with the increasing demand of n-butyl acetate, the environment-friendly process for synthesizing n-butyl acetate has wide prospect. For researchers, developing a catalyst for n-butyl acetate synthesis reaction with excellent performance, improving the reaction efficiency and inhibiting the generation of byproducts is an important working direction in the future.
Disclosure of Invention
The invention aims to solve the problems of excessive side reaction and serious environmental pollution of an inorganic acid catalyst used in the n-butyl acetate production process in the prior art, and the problems of poor catalytic activity, low ester selectivity and the like of a solid acid catalyst and an acidic cation exchange resin catalyst. Provides a spherical esterification catalyst, a preparation method thereof and application thereof in n-butyl acetate synthesis reaction. The catalyst is used for the synthesis reaction of n-butyl acetate, and can obtain higher acetic acid conversion rate and n-butyl acetate selectivity.
In order to achieve the above object, a first aspect of the present invention provides a spherical esterification catalyst, wherein the spherical esterification catalyst comprises a spherical composite carrier and phosphotungstates supported on the spherical composite carrier, and the content of the spherical composite carrier is 40 to 80% by weight and the content of the phosphotungstates is 20 to 60% by weight based on the total weight of the spherical esterification catalyst.
The second aspect of the invention provides a preparation method of the spherical esterification catalyst, wherein the preparation method comprises the following steps:
(S1) contacting a spherical composite carrier with an aqueous solution of metal salt for a first reaction, separating for the first time to obtain a solid product, and drying and roasting for the first time to obtain a catalyst intermediate;
and (S2) contacting the catalyst intermediate with an aqueous solution of phosphotungstic acid for a second reaction, separating for the second time to obtain a solid product, and washing, drying and roasting for the second time the solid product to obtain the spherical esterification catalyst.
The third aspect of the invention provides an application of the spherical esterification catalyst in the synthesis reaction of n-butyl acetate.
Through the technical scheme, the technical scheme of the invention has the following advantages:
(1) The spherical esterification catalyst provided by the invention is spherical, uniform in size, smooth in surface, high in mechanical strength, stable in structure, good in high temperature resistance, and free from deformation and swelling in the reaction process.
(2) The spherical esterification catalyst provided by the invention has the advantages of easily available raw materials, simple preparation method and process, easily controlled conditions and good product repeatability.
(3) The spherical esterification catalyst provided by the invention is used for the synthesis reaction of the acetate, and has mild process conditions and low requirements on reaction devices. The acetic acid conversion rate is high, and the selectivity of acetate is high.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
FIG. 1 is an XRD spectrum of a spherical composite carrier A prepared in example 1 of the present invention;
FIG. 2 is a photograph of the spherical composite support A prepared in example 1.
Detailed Description
The endpoints and any values of the ranges disclosed herein are not limited to the precise range or value, and are understood to encompass values approaching those ranges or values. For numerical ranges, one or more new numerical ranges may be found between the endpoints of each range, between the endpoint of each range and the individual point value, and between the individual point value, in combination with each other, and are to be considered as specifically disclosed herein.
As described above, the first aspect of the present invention provides a spherical esterification catalyst, wherein the spherical esterification catalyst comprises a spherical composite carrier and phosphotungstates supported on the spherical composite carrier, and the content of the spherical composite carrier is 40 to 80% by weight, and the content of the phosphotungstates is 20 to 60% by weight, based on the total weight of the spherical esterification catalyst.
The inventors of the present invention found that: in the prior art, esterification catalysts used to produce n-butyl acetate fall into two categories, homogeneous and heterogeneous. Wherein, the homogeneous catalyst mainly comprises inorganic acid solution and organic acid, and the heterogeneous catalyst mainly comprises solid acid and cation exchange resin. The homogeneous catalyst has the advantages of low cost and good catalytic activity, but the defects of difficult separation of products and the catalyst, more side reactions, easy corrosion to equipment and the like are eliminated. Although the solid acid esterification catalyst solves the problems of difficult product separation and serious equipment corrosion, the catalyst is rarely applied to industrial production due to the defects of poor catalytic activity, higher reaction temperature, lower product selectivity and the like. Compared with the catalyst, the resin catalyst has the advantages of high selectivity, low cost, easy separation and the like, but has low ester yield and poor high temperature resistance in the process of synthesizing n-butyl acetate. The resin is an organic polymer material, is easy to swell in an organic solvent, is easy to deform and even decompose in a high-temperature environment, and is a main reason for poor temperature resistance of the resin catalyst.
The phosphotungstate is a good esterification catalyst, has stable structure, is not easy to absorb moisture, is easy to store and convenient to use, has low price, does not corrode equipment in the use process, and is a very promising green esterification catalyst. However, phosphotungstates tend to agglomerate during the catalytic esterification reaction, resulting in reduced catalytic efficiency. If a proper carrier can be selected to disperse the phosphotungstate catalyst well, the problems can be solved, and the efficiency of the catalyst can be improved. Compared with a resin catalyst, the MCM-22 molecular sieve has a certain pore channel structure and surface acidity, and is suitable for catalyzing esterification reaction of small molecules. However, the pore canal of the molecular sieve has smaller size, and the diffusion of macromolecular products can be inhibited in the reaction; and the number of acid sites on the surface of the MCM-22 molecular sieve is small, the efficiency of the catalytic esterification reaction is low, and the catalyst is not suitable for being directly used as a catalyst for catalyzing the synthesis reaction of n-butyl acetate. In addition, in industrial production, the solid-phase esterification catalyst is shaped to be applicable, for example: the resin catalyst is generally spherical. The spherical catalyst has the advantages of high bulk density, large loading capacity, low abrasion, small dust during loading, fast mass transfer, high reaction efficiency and the like.
The inventor of the invention finds that if the MCM-22 molecular sieve and the aluminum-containing material with better viscosity are mixed according to a certain proportion in the development process of the esterification catalyst, the spherical alumina-MCM-22 composite carrier is prepared by a unique molding method. The carrier belongs to an inorganic structure, can not be swelled and deformed in an organic solvent, and has good temperature resistance. The esterification catalyst with better mechanical strength can be obtained after the phosphotungstate is loaded on the spherical composite carrier. The catalyst can show good catalytic activity and n-butyl acetate selectivity when being used for acetic acid esterification reaction.
According to the present invention, preferably, the content of the spherical composite carrier is 48 to 73 wt% and the content of the phosphotungstates is 27 to 52 wt% based on the total weight of the spherical esterification catalyst; more preferably, the content of the spherical composite carrier is 58.5 to 66.3 wt% and the content of the phosphotungstates is 33.7 to 41.5 wt% based on the total weight of the spherical esterification catalyst. In the invention, the prepared catalyst has better catalytic activity and ester selectivity when being used for acetic acid esterification reaction by adopting the content of the specific spherical composite carrier and the content of phosphotungstates.
According to the invention, the phosphotungstates are alkali metal salts of phosphotungstic acid, preferably one or more of potassium phosphotungstate, rubidium phosphotungstate and cesium phosphotungstate.
According to the invention, the specific surface area of the spherical composite carrier is 400-900m 2 The pore volume is 0.3-0.9ml/g, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.3-1nm, and the second most probable pore diameter is 8-25nm; the average particle diameter is 1.0-3.0mm, and the average particle strength is 20-70N; preferably, the specific surface area of the spherical composite carrier is 450-750m 2 The pore volume is 0.4-0.7ml/g, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.4-0.8nm, and the second most probable pore diameter is 10-20nm; the average particle diameter is 1.2-2.7mm, and the average particle strength is 25-60N; more preferably, the specific surface area of the spherical composite carrier is 508-634m 2 The pore volume is 0.51-0.62ml/g, the average particle diameter is 1.5-2.4mm, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.5-0.7nm, and the second most probable pore diameter is 12-16nm; the average particle strength is 28.1-52.6N. In the invention, the spherical composite carrier with the specific parameters is adopted, so that the prepared catalyst has better catalytic activity and ester selectivity when being used for acetic acid esterification reaction.
According to the invention, the preparation method of the spherical composite carrier comprises the following steps:
(1) Mixing an alumina precursor, an MCM-22 molecular sieve, an acidic aqueous solution and an extrusion aid to obtain a mixture, and performing pellet pelleting treatment on the mixture to obtain a spherical alumina-MCM-22 precursor;
(2) And drying and roasting the spherical alumina-MCM-22 precursor to obtain the spherical alumina-MCM-22 composite carrier.
In the present invention, the pseudo-boehmite may be commercially available or prepared, and in the present invention, specifically, the pseudo-boehmite comprises: de model SBPseudo-boehmite powder (available from Beijing Asia Taiao chemical auxiliary agent Co., ltd., specific surface area of 241 m) 2 Per gram, pore volume of 0.53cm 3 Per g), pseudo-boehmite powder (model P-DF-09-LSi, manufactured by Shandong aluminum company Limited liability company, having a specific surface area of 286m 2 Per gram, pore volume of 1.08cm 3 Per g) and macroporous pseudo-boehmite powder (manufactured by Zibo constant Ji Fen New Material Co., ltd., specific surface area: 327 m) of type PB-0101 2 Per gram, pore volume of 1.02cm 3 /g).
According to the invention, in the step (1), the MCM-22 molecular sieve can be selected from one or more of MCM-22 molecular sieves with different silicon-aluminum ratios, and is preferably MCM-22 molecular sieves with low silicon-aluminum ratios; the MCM-22 molecular sieve SiO with low silicon-aluminum ratio 2 With Al 2 O 3 The molar ratio of (2) is 10-50:1. in the present invention, MCM-22 molecular sieves (500 m 2 /g，SiO 2 /Al 2 O 3 =25) was purchased from nanjing front nano-technology materials limited.
According to the present invention, the acidic aqueous solution may be an aqueous organic acid solution or an aqueous inorganic acid solution, preferably, the acidic aqueous solution is one or more selected from an aqueous formic acid solution, an aqueous acetic acid solution, an aqueous citric acid solution, an aqueous nitric acid solution and an aqueous hydrochloric acid solution, more preferably, the acidic aqueous solution is an aqueous nitric acid solution or an aqueous citric acid solution; in the present invention, the mass concentration of the acidic aqueous solution is 1 to 20%, preferably 2 to 10%.
According to the invention, the extrusion aid is selected from one or more of sesbania powder, polyethylene glycol, polyvinyl alcohol, polyacrylamide and cellulose; preferably, the auxiliary agent is sesbania powder.
Preferably, the weight ratio of the alumina precursor, the MCM-22 molecular sieve, the extrusion aid and the acidic aqueous solution is 1: (0.2-1): (0.02-0.5): (0.2-5); preferably, the weight ratio of the alumina precursor, the MCM-22 molecular sieve, the extrusion aid and the acidic aqueous solution is 1: (0.3-0.5): (0.07-0.12): (0.6-0.8).
According to the present invention, in step (1), an alumina precursor, the MCM-22 molecular sieve, an acidic aqueous solution, and an extrusion aid are mixed under conditions including: the stirring speed is 50-300r/min, the temperature is 20-60 ℃ and the time is 0.5-6h; preferably, the stirring speed is 150-250r/min, the temperature is 20-40 ℃ and the time is 0.5-1h.
According to the present invention, in step (2), the drying conditions include: the temperature is 70-150 ℃ and the time is 3-24 hours; preferably, the temperature is 100-130 ℃ and the time is 6-12h.
According to the present invention, in step (2), the conditions of the firing include: the temperature is 400-700 ℃ and the time is 2-30h; preferably, the temperature is 550-700 ℃ and the time is 12-15h.
According to the present invention, in step (1), the method of pelleting the pellets comprises:
(1-1) extruding the mixture into a strip, and then cutting and extruding into raw material balls;
(1-2) shaping the raw material ball to obtain a standard ball;
(1-3) screening the standard spheres to obtain spherical precursors.
According to the invention, in the step (1-1), after uniformly mixing an alumina precursor, the MCM-22 molecular sieve, an acidic aqueous solution and an extrusion aid, transferring the obtained mixture into a miniature ball making machine to extrude a strip with a circular section, and then extruding the strip into raw material balls after cutting; wherein the conditions of extrusion into a strip include: the extrusion speed is 0.5-5m/min, and the diameter of the circular section of the strip is 1.0-3.0mm; the conditions of the cutting include: the cutting speed is 100-3500 grains/min.
According to the invention, in the step (1-2), the raw material balls are put into a pellet shaper for shaping, so that the raw material balls become standard spherical balls; wherein the shaping conditions include: the rounding time is 0.5-10 min/time, the number of times of rounding is 1-5 times, and the rotating speed of the sample cavity is 50-1400r/min.
According to the invention, in step (1-3), the standard spheres are placed in a pellet screening machine to screen out spherical precursors of suitable size.
The second aspect of the invention provides a preparation method of the spherical esterification catalyst, wherein the preparation method comprises the following steps:
(S1) contacting a spherical composite carrier with an aqueous solution of metal salt for a first reaction, separating for the first time to obtain a solid product, and drying and roasting for the first time to obtain a catalyst intermediate;
and (S2) contacting the catalyst intermediate with an aqueous solution of phosphotungstic acid for a second reaction, separating for the second time to obtain a solid product, and washing, drying and roasting for the second time the solid product to obtain the spherical esterification catalyst.
According to the present invention, in step (S1), the metal salt is selected from one or more of carbonate, chloride, sulfate and nitrate of alkali metal; preferably, the alkali metal is selected from one or more of potassium, rubidium and cesium.
According to the invention, the concentration of the aqueous solution of the metal salt is 0.05 to 2.0mol/L, preferably 0.1 to 1.0mol/L.
According to the invention, the weight ratio of the spherical composite carrier to the aqueous solution of the metal salt is 1: (2-100), preferably 1: (5-50).
According to the present invention, the conditions under which the spherical composite support is contacted with the aqueous solution of the metal salt to perform the first reaction include: the reaction temperature may be 30-120 ℃, preferably 40-90 ℃; the time may be 0.5 to 20 hours, preferably 2 to 10 hours. Preferably, in order to achieve better mixing effect, the reaction efficiency can be improved by rapid stirring or by means of ultrasonic means in the process of contact reaction of the spherical composite carrier and the metal salt aqueous solution.
According to the present invention, the conditions for the first firing include: the temperature is 250-400 ℃ and the time is 3-10h.
According to the present invention, in step (S1), the first separation method is not particularly required, and may be a method known in the art, for example: the water is removed using a rotary evaporator or by evaporation with heating during stirring.
According to the invention, in step (S2), the concentration of the aqueous solution of phosphotungstic acid is 1 to 30%, preferably 5 to 20%.
According to the invention, the weight ratio of the spherical composite carrier to the aqueous solution of phosphotungstic acid is 1: (5-50), preferably 1: (10-30).
According to the invention, the conditions under which the contact of the catalyst intermediate with the aqueous solution of the metal salt carries out the second reaction include: the reaction temperature may be 30-120 ℃, preferably 40-90 ℃; the time may be 0.5 to 20 hours, preferably 2 to 10 hours. Preferably, in order to achieve better contact reaction effect, the contact reaction efficiency can be improved by rapid stirring or by means of ultrasonic means during the contact reaction of the catalyst intermediate with the aqueous metal salt solution.
According to the invention, the separation method in step (S2) is not particularly required, for example: the liquid may be removed using filtration or suction filtration to give a solid product.
According to the present invention, in step (S2), the method of washing the solid product is not particularly required, for example: the solid product may be washed with deionized water, the volume ratio of deionized water to solid product may be 5-20, and the number of washes may be 2-8.
According to the present invention, in step (S1) and step (S2), the conditions for drying the solid product are preferably: drying at 80-130 deg.C for 3-20 hr.
According to the present invention, the conditions for the second firing include: the temperature is 250-400 ℃ and the time is 3-10h; the first firing conditions and the second firing conditions may be the same or different.
The third aspect of the invention provides an application of the spherical esterification catalyst in the synthesis reaction of n-butyl acetate.
The application method of the catalyst comprises the following steps: acetic acid and n-butanol are simultaneously contacted with a spherical esterification catalyst.
In the present invention, the contact conditions of the acetic acid and the n-butanol with the catalyst include: the temperature of contact may be 50-160 ℃, preferably 70-130 ℃; the contact pressure may be 0.01 to 5.0MPa, preferably 0.1 to 3.0MPa; the mass space velocity of acetic acid can be 0.01-30h -1 Preferably 0.1-10h -1 The method comprises the steps of carrying out a first treatment on the surface of the The molar ratio of acetic acid to n-butanol is 1:0.1-20, preferably 1:0.5-10.
The present invention will be described in detail by examples.
In the following examples and comparative examples:
XRD testing of the samples was performed on an X' Pert MPD X-ray powder diffractometer, philips company, netherlands, cu ka target, scan range 2θ=5-90 °.
The pore structure parameter analysis of the samples was performed on an ASAP2020-M+C type adsorber available from Micromeritics, inc. The sample was vacuum degassed at 350 ℃ for 4 hours prior to measurement, the specific surface area of the sample was calculated using the BET method, and the pore volume was calculated using the BJH model.
Elemental analysis experiments of the samples were performed on an Eagle III energy dispersive X-ray fluorescence spectrometer manufactured by EDAX, inc. of America.
The rotary evaporator is manufactured by IKA corporation of Germany and has the model RV10 digital.
The drying oven is manufactured by Shanghai-Heng scientific instrument Co., ltd, and the model is DHG-9030A.
The muffle furnace is available from CARBOLITE company under the model CWF1100.
The kneader is an FN-NH2 kneader manufactured by Tianshuihua round pharmaceutical equipment science and technology Co., ltd; the miniature ball making machine is a HWJ-100 miniature ball making machine manufactured by Tianshuihua round pharmaceutical equipment science and technology Co., ltd; the pellet shaper is an FN-XZXJ pellet shaper manufactured by Tianshuihua round pharmaceutical equipment science and technology Co., ltd; the micropill screening machine is SWP-1200 micropill screening machine produced by Tianshuihua round pharmaceutical equipment science and technology Co.
Example 1
This example illustrates a spherical esterification catalyst prepared according to the present invention.
(1) Preparation of spherical alumina-MCM-22 composite carrier
120g of pseudo-boehmite powder of type P-DF-09-LSi, 50g of MCM-22 molecular sieves (SiO 2 /Al 2 O 3 =25), 85g of dilute nitric acid with the concentration of 5% and 10g of sesbania powder are mixed, and the mixture is transferred into a kneader to be stirred and mixed uniformly. Kneading temperature is 35 ℃, kneadingThe rotational speed of the main shaft of the mixing machine is 150r/min, and the kneading time is 1h. Putting the uniformly mixed raw materials into a hopper of a miniature ball making machine, selecting a strip extruding die with the aperture of 2.1mm, adjusting the strip extruding speed to be 2m/min and the cutting speed to be 1200 grains/min, extruding the raw materials into strips and extruding and cutting the strips into round small grains. Putting the round small particles into a pellet shaper for shaping, wherein shaping conditions are as follows: the rounding time is 3 minutes/time, the rounding times are 3 times, and the rotating speed of the sample cavity is 300r/min. And (5) placing the shaped standard spherical raw material balls into a pellet screening machine to screen out spherical precursors with the size of 2.1 mm. Drying the spherical precursor at 110 ℃ for 8 hours, and roasting at 600 ℃ for 15 hours to obtain the spherical alumina-MCM-22 composite carrier A.
The alumina content in the spherical alumina-MCM-22 composite carrier A is 62.7 weight percent, and the MCM-22 molecular sieve content is 37.3 weight percent.
The spherical alumina-MCM-22 composite carrier A was characterized and its structural parameters are shown in Table 1.
FIG. 1 is an XRD spectrum of spherical alumina-MCM-22 composite carrier A. Fig. 1 is an XRD spectrum of spherical composite carrier a. The spectrum shows that the x-ray diffraction angle of the sample is mainly: 2θ=7.2 °, 8.1 °, 10.0 °, 12.8 °, 14.4 °, 15.9 °, 20.2 °, 21.7 °, 22.6 °, 23.7 °, 24.9 °, 25.9 °, 27.0 °, 33.5 °, 37.4 °, 39.5 °, 45.8 °, and 66.8 °, wherein the fourteen diffraction signals at 2θ=7.2 °, 8.1 °, 10.0 °, 12.8 °, 14.4 °, 15.9 °, 20.2 °, 21.7 °, 22.6 °, 23.7 °, 24.9 °, 25.9 °, 27.0 °, and 33.5 ° are consistent with the MCM-22 molecular sieve diffraction pattern; four diffraction signals and γ -Al at 2θ=37.4°, 39.5 °, 45.8 ° and 66.8 ° 2 O 3 The diffraction patterns are identical, which shows that the spherical alumina-MCM-22 composite carrier A has no obvious change of MCM-22 molecular sieve crystal phase after roasting at 600 ℃, and typical gamma-Al is presented after pseudo-boehmite dehydration 2 O 3 A crystalline phase.
FIG. 2 is a photograph of a spherical alumina-MCM-22 composite support A. It can be seen that the carrier has the appearance of white sphere, good sphericity, smooth sphere and uniform particle size.
(2) Preparation of spherical esterification catalyst
10g of spherical alumina-MCM-22 composite carrier A and 260g of aqueous solution of potassium carbonate with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 175g of a 10% strength aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst A.
The content of the spherical alumina-MCM-22 composite carrier A is 61.3 weight percent and the content of the potassium phosphotungstate is 38.7 weight percent based on the total weight of the catalyst A.
(3) Evaluation of catalyst reactivity
The esterification performance of catalyst a was evaluated on a fixed bed reactor. 5.0 g of the catalyst was charged into a stainless steel fixed bed reactor having an inner diameter of 8mm, a reaction temperature of 110℃and a reaction pressure of 0.3MPa and a weight space velocity of acetic acid of 3.0h were adjusted by nitrogen gas -1 The molar ratio of n-butanol to acetic acid was 5:1 and the reaction time was 20 hours. After cooling the product was analyzed by Agilent 7890A gas chromatograph equipped with FFAP capillary chromatography column and hydrogen flame detector (FID), and quantitative analysis was performed using a calibration factor with programmed temperature. The acetic acid conversion was 96.8% and the selectivity to n-butyl acetate was 99.6%.
Example 2
This example illustrates a spherical esterification catalyst prepared according to the present invention.
(1) Preparation of spherical composite carrier
100g of pseudo-boehmite powder of model SB, 50g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 =25), 80g of an aqueous acetic acid solution with a concentration of 10% and 12g of sesbania powder were mixed, and transferred to a kneader to be stirred and mixed uniformly. The kneading temperature was 35℃and the main shaft rotation speed of the kneader was 150r/min, and the kneading time was 1h. Putting the uniformly mixed raw materials into a hopper of a miniature ball making machine, and selectingAnd (3) adjusting the extrusion speed of the extrusion die to be 5m/min and the cutting speed of the extrusion die to be 2000 grains/min, extruding the raw materials into strips and cutting the strips into round small grains. Putting the round small particles into a pellet shaper for shaping, wherein shaping conditions are as follows: the rounding time is 0.5 min/time, the number of times of rounding is 2, and the rotating speed of the sample cavity is 500r/min. And (5) placing the shaped standard spherical raw material balls into a pellet screening machine to screen out spherical precursors with the size of 1.6 mm. Drying the spherical precursor at 130 ℃ for 6 hours, and roasting at 700 ℃ for 12 hours to obtain the spherical alumina-MCM-22 composite carrier B.
The alumina content in the spherical alumina-MCM-22 composite carrier B is 60.0 wt% and the MCM-22 molecular sieve content is 40.0 wt%.
The spherical alumina-MCM-22 composite carrier B was characterized and its structural parameters are shown in Table 1.
(2) Preparation of spherical esterification catalyst
10g of spherical alumina-MCM-22 composite carrier B and 515g of cesium carbonate aqueous solution with the concentration of 0.2mol/L are mixed and stirred at 90 ℃ for reaction for 2 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 130℃for 3h and calcined at 280℃for 8h to give a catalyst intermediate. The catalyst intermediate was mixed with 310g of 5% aqueous solution of phosphotungstic acid and reacted at 90℃for 2 hours with stirring. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 130 ℃ for 5 hours, and roasting at 380 ℃ for 4 hours to obtain the short rod-shaped all-silicon mesoporous material supported catalyst B.
The content of the spherical alumina-MCM-22 composite carrier B was 58.5 wt% and the content of cesium phosphotungstate was 41.5 wt% based on the total weight of the catalyst B.
(3) Evaluation of catalyst reactivity
The esterification reaction performance test of catalyst B was conducted in the same manner as in step (3) of example 1. The acetic acid conversion was 97.0% and the selectivity to n-butyl acetate was 99.4%.
Example 3
This example illustrates a spherical esterification catalyst prepared according to the present invention.
(1) Preparation of spherical composite carrier
130g of pseudo-boehmite powder of model PB-0101 and 40g of MCM-22 molecular sieve (SiO 2 /Al 2 O 3 =25), 85g of a 20% aqueous solution of citric acid and 8g of sesbania powder were mixed, and transferred to a kneader to be stirred and mixed uniformly. The kneading temperature was 20℃and the main shaft rotation speed of the kneader was 200r/min, and the kneading time was 0.5h. Putting the uniformly mixed raw materials into a hopper of a miniature ball making machine, selecting a strip extruding die with the aperture of 2.5mm, adjusting the strip extruding speed to be 1m/min and the cutting speed to be 500 grains/min, extruding the raw materials into strips and extruding and cutting the strips into round small grains. Putting the round small particles into a pellet shaper for shaping, wherein shaping conditions are as follows: the rounding time is 2 minutes/time, the number of times of rounding is 4, and the rotating speed of the sample cavity is 200r/min. And (5) placing the shaped standard spherical raw material balls into a pellet screening machine to screen out spherical precursors with the size of 2.5 mm. Drying the spherical precursor at 90 ℃ for 10 hours, and roasting at 500 ℃ for 30 hours to obtain the spherical alumina-MCM-22 composite carrier C.
The alumina content in the spherical alumina-MCM-22 composite carrier C is 71.0 wt% and the MCM-22 molecular sieve content is 29.0 wt%.
The spherical alumina-MCM-22 composite carrier C was characterized and its structural parameters are shown in Table 1.
(2) Preparation of spherical esterification catalyst
10g of spherical alumina-MCM-22 composite carrier C and 115g of aqueous solution of potassium carbonate with the concentration of 1.0mol/L are mixed and stirred at 40 ℃ for reaction for 10 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 80℃for 20h and calcined at 300℃for 6h to give a catalyst intermediate. The catalyst intermediate was mixed with 75g of a 20% strength aqueous solution of phosphotungstic acid and reacted at 60℃with stirring for 8 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 80 ℃ for 20 hours, and roasting at 350 ℃ for 4 hours to obtain the short rod-shaped all-silicon mesoporous material supported catalyst C.
The content of the spherical alumina-MCM-22 composite carrier C was 66.3 wt% and the content of potassium phosphotungstate was 33.7 wt% based on the total weight of the catalyst C.
(3) Evaluation of catalyst reactivity
The esterification reaction performance test of catalyst C was conducted in the same manner as in step (3) of example 1. The acetic acid conversion was 96.5% and the selectivity to n-butyl acetate was 99.7%.
TABLE 1
Example 4
This example illustrates a spherical esterification catalyst prepared according to the present invention.
A spherical esterification catalyst D was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 170g of aqueous solution of potassium carbonate with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 114g of a 10% strength aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst D.
The content of the spherical alumina-MCM-22 composite carrier A was 70.7 wt% and the content of potassium phosphotungstate was 29.3 wt% based on the total weight of the catalyst D.
Catalyst D was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 95.7% and the selectivity to n-butyl acetate was 99.0%.
Example 5
This example illustrates a spherical esterification catalyst prepared according to the present invention.
A spherical esterification catalyst E was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 446g of aqueous solution of potassium carbonate with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 300g of a 10% aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst E.
The content of the spherical alumina-MCM-22 composite carrier A was 48 wt% and the content of potassium phosphotungstate was 52 wt% based on the total weight of the catalyst E.
Catalyst E was tested for its catalytic performance according to the esterification performance evaluation method of step (3) in example 1. The acetic acid conversion was 95.4% and the selectivity to n-butyl acetate was 98.7%.
Example 6
This example illustrates a spherical esterification catalyst prepared according to the present invention.
A spherical esterification catalyst F was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 136g of potassium carbonate aqueous solution with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 91g of a 10% strength aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst F.
The content of the spherical alumina-MCM-22 composite carrier A was 75.1 wt% and the content of potassium phosphotungstate was 24.9 wt% based on the total weight of the catalyst F.
Catalyst F was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 94.2% and the selectivity to n-butyl acetate was 98.1%.
Example 7
This example illustrates a spherical esterification catalyst prepared according to the present invention.
A spherical esterification catalyst G was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 618g of aqueous solution of potassium carbonate with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 415g of a 10% strength aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst G.
The content of the spherical alumina-MCM-22 composite carrier A is 40 weight percent and the content of the potassium phosphotungstate is 60 weight percent based on the total weight of the catalyst G.
Catalyst G was tested for its catalytic performance according to the esterification performance evaluation method of step (3) in example 1. The acetic acid conversion was 93.9% and the selectivity to n-butyl acetate was 97.8%.
Comparative example 1
A spherical esterification catalyst D1 was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 52g of aqueous solution of potassium carbonate with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 35g of a 10% aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst D1.
The content of the spherical alumina-MCM-22 composite carrier A was 88.8 wt% and the content of potassium phosphotungstate was 11.2 wt% based on the total weight of the catalyst D1.
Catalyst D1 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 73.2% and the selectivity to n-butyl acetate was 92.9%.
Comparative example 2
A spherical esterification catalyst D2 was prepared in the same manner as in example 1, except that: step (1) of example 1 was omitted, and the "spherical alumina-MCM-22 composite support A" of step (2) of example 1 was replaced with "commercially available silica (from Qingdao Seawamori silica gel desiccant plant, specific surface area 329 m) 2 /g, average particle diameter 1.5 mm) ", to give catalyst D2.
The commercially available silica content was 61.3% by weight and the potassium phosphotungstate content was 38.7% by weight, based on the total weight of catalyst D2.
Catalyst D2 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 87.6% and the selectivity to n-butyl acetate was 95.3%.
Comparative example 3
A spherical esterification catalyst D3 was prepared in the same manner as in example 1, except that: step (1) in example 1 was omitted, and "10g of spherical alumina-MCM-22 composite carrier A" in step (2) in example 1 was replaced with "14g of pseudo-boehmite with the model of P-DF-09-LSi", to obtain catalyst D3.
The content of alumina was 61.3% by weight and the content of potassium phosphotungstate was 38.7% by weight, based on the total weight of catalyst D3.
Catalyst D3 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 90.1% and the selectivity to n-butyl acetate was 95.1%.
Comparative example 4
A spherical esterification catalyst D4 was prepared in the same manner as in example 1, except that: step (1) in example 1 was omitted, and "10g of spherical alumina-MCM-22 composite carrier A" in step (2) in example 1 was replaced with "10g of MCM-22 molecular sieve", to obtain catalyst D4.
The MCM-22 molecular sieve content was 61.3 wt.% and the potassium phosphotungstate content was 38.7 wt.% based on the total weight of catalyst D4.
Catalyst D4 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 92.8% and the selectivity to n-butyl acetate was 96.4%.
Comparative example 5
An esterification catalyst D5 was prepared in the same manner as in example 1, except that: in step (1), 70g of pseudo-boehmite powder of type P-DF-09-LSi and 98g of MCM-22 molecular sieve were used to obtain catalyst D5.
The content of the spherical composite carrier was 61.3% by weight and the content of potassium phosphotungstate was 38.7% by weight, based on the total weight of the catalyst D5.
Catalyst D5 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 93.1% and the selectivity to n-butyl acetate was 97.3%.
Comparative example 6
An esterification catalyst D6 was prepared in the same manner as in example 1, except that: the preparation conditions of the catalyst of step (2) in example 1 were changed, specifically:
10g of spherical alumina-MCM-22 composite carrier A and 1060g of aqueous potassium carbonate solution with the concentration of 0.6mol/L are mixed and stirred at 70 ℃ for reaction for 6 hours. After the reaction, the stirring was stopped, and the solvent water was removed by using a rotary evaporator to obtain a solid product. The solid product was dried at 100℃for 8 hours and calcined at 320℃for 6 hours to give a catalyst intermediate. The catalyst intermediate was mixed with 713g of a 10% strength aqueous solution of phosphotungstic acid and reacted at 70℃with stirring for 6 hours. After the reaction is finished, liquid is removed by suction filtration, and a solid product is obtained. Washing the solid product with distilled water for 4 times, drying the solid product at 100 ℃ for 12 hours, and roasting at 320 ℃ for 6 hours to obtain the spherical esterification catalyst D6.
The content of the spherical alumina-MCM-22 composite carrier A was 28 wt% and the content of potassium phosphotungstate was 72 wt% based on the total weight of the catalyst D6.
Catalyst D6 was tested for its catalytic performance according to the method for evaluating the performance of esterification reaction in step (3) of example 1. The acetic acid conversion was 74.3% and the selectivity to n-butyl acetate was 93.5%.
From the results, the spherical esterification catalyst provided by the invention can directly convert acetic acid and n-butyl alcohol into n-butyl acetate, so that higher acetic acid conversion rate and n-butyl acetate selectivity are obtained.
In comparative example 1, too high content of spherical alumina-MCM-22 composite carrier A, low acetic acid conversion rate and low selectivity of n-butyl acetate are caused by too low content of active component phosphotungstate on the catalyst and insufficient active site in the reaction process.
In comparative example 2, the spherical composite support specifically defined in the present invention was not employed, but commercially available silica was employed, and the conversion of acetic acid was low and the selectivity of n-butyl acetate was low due to irregular pore structure of commercially available silica and uneven dispersion of active components on the surface of the support.
In comparative example 3, the spherical composite carrier specifically defined by the present invention is not adopted, but a single alumina carrier is adopted, and the dispersion of the active components on the surface of the carrier is not facilitated due to the uneven size distribution of alumina pore channels, and the diffusion of raw materials and products in the reaction process is also not facilitated, so that the acetic acid conversion rate is low and the selectivity of n-butyl acetate is low.
In comparative example 4, the spherical composite carrier specially limited by the invention is not adopted, but a single MCM-22 molecular sieve is adopted, and the pore size of the MCM-22 molecular sieve is smaller, so that the prepared catalyst has uneven rear surface and poor dispersion of active components, thus the acetic acid conversion rate is low, and the selectivity of n-butyl acetate is low.
In comparative example 5, the weight ratio of the contents of alumina and MCM-22 molecular sieve in the spherical composite carrier was 1:2 (because the pseudo-boehmite with the model of P-DF-09-LSi contains about 30 percent of water and the alumina obtained after the finished product is prepared has only 70 percent of weight), the MCM-22 molecular sieve is too high, and because the proportion of the MCM-22 molecular sieve in the spherical composite carrier is not in the specific requirement range of the invention, the prepared catalyst has poor strength, uneven surface and poor dispersion of active components, thereby further leading to low acetic acid conversion rate and low selectivity of n-butyl acetate.
In comparative example 6, the content of the spherical alumina-MCM-22 composite carrier A is too low, and the active component phosphotungstate on the catalyst is too high, so that the active component is unevenly dispersed on the carrier, and the utilization efficiency of the active center in the reaction process is low, thereby causing low acetic acid conversion rate and low selectivity of n-butyl acetate.
The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, a number of simple variants of the technical solution of the invention are possible, including combinations of the individual technical features in any other suitable way, which simple variants and combinations should likewise be regarded as being disclosed by the invention, all falling within the scope of protection of the invention.

Claims (11)

1. The spherical esterification catalyst is characterized by comprising a spherical composite carrier and phosphotungstates loaded on the spherical composite carrier, wherein the spherical composite carrier comprises alumina and MCM-22 molecular sieves, the content of the spherical composite carrier is 40-80 wt% based on the total weight of the spherical esterification catalyst, and the content of the phosphotungstates is 20-60 wt%.
2. The catalyst according to claim 1, wherein the content of the spherical composite carrier is 48 to 73 wt% and the content of the phosphotungstate is 27 to 52 wt%, based on the total weight of the spherical esterification catalyst;
preferably, the content of the spherical composite carrier is 58.5 to 66.3 wt% and the content of the phosphotungstates is 33.7 to 41.5 wt%, based on the total weight of the spherical esterification catalyst.
3. The catalyst of claim 1 or 2, wherein the phosphotungstates are alkali metal salts of phosphotungstates;
preferably, the phosphotungstates are selected from one or more of potassium phosphotungstate, rubidium phosphotungstate, and cesium phosphotungstate.
4. The catalyst according to claim 1 or 2, wherein the specific surface area of the spherical composite carrier is 400-900m 2 The pore volume is 0.3-0.9ml/g, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.3-1nm, and the second most probable pore diameter is 8-25nm; the average particle diameter is 1.0-3.0mm, and the average particle strength is 20-70N;
preferably, the specific surface area of the spherical composite carrier is 450-750m 2 The pore volume is 0.4-0.7ml/g, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.4-0.8nm, and the second most probable pore diameter is 10-20nm; the average particle diameter is 1.2-2.7mm, and the average particle strength is 25-60N;
more preferably, the specific surface area of the spherical composite carrier is 508-634m 2 The pore volume is 0.51-0.62ml/g, the pore size distribution is bimodal, the first most probable pore diameter corresponding to the bimodal is 0.5-0.7nm, and the second most probable pore diameter is 12-16nm; the average particle diameter is 1.5-2.4mm, and the average particle strength is 28.1-52.6N.
5. The catalyst of claim 1 or 4, wherein the alumina is present in an amount of 50-80 wt% and the MCM-22 molecular sieve is present in an amount of 20-50 wt%, based on the total weight of the spherical composite support;
preferably, the content of the alumina is 60-71 wt% and the content of the MCM-22 molecular sieve is 29-40 wt% based on the total weight of the spherical composite carrier.
6. The catalyst according to any one of claims 1 to 5, wherein the preparation method of the spherical composite carrier comprises:
(1) Mixing an alumina precursor, an MCM-22 molecular sieve, an acidic aqueous solution and an extrusion aid to obtain a mixture, and performing pellet processing on the mixture to obtain a spherical alumina-MCM-22 precursor;
(2) And drying and roasting the spherical alumina-MCM-22 precursor to obtain the spherical alumina-MCM-22 composite carrier.
7. The catalyst of claim 6, wherein the alumina precursor is selected from one or more of pseudo-boehmite, aluminum hydroxide gel, aluminum sol, gibbsite, and boehmite;
and/or the specific surface area of the MCM-22 molecular sieve is 400-600m 2 Per gram, pore volume of 0.4-0.7cm 3 /g；
And/or the weight ratio of the alumina precursor, the MCM-22 molecular sieve, the extrusion aid and the acidic aqueous solution is 1: (0.2-1): (0.02-0.5): (0.2-5).
8. A process for preparing a spherical esterification catalyst according to any one of claims 1 to 7, characterized in that the process comprises:
(S1) contacting a spherical composite carrier with an aqueous solution of metal salt for a first reaction, separating for the first time to obtain a solid product, and drying and roasting for the first time to obtain a catalyst intermediate;
and (S2) contacting the catalyst intermediate with an aqueous solution of phosphotungstic acid for a second reaction, separating for the second time to obtain a solid product, and washing, drying and roasting for the second time the solid product to obtain the spherical esterification catalyst.
9. The method of claim 8, wherein the metal salt is selected from one or more of alkali metal carbonates, chlorides, sulfates, and nitrates;
and/or the concentration of the aqueous solution of the metal salt is 0.05-2.0mol/L;
and/or the weight ratio of the spherical composite carrier to the aqueous solution of the metal salt is 1: (2-100);
and/or, the conditions of the first reaction include: the temperature is 30-120 ℃ and the time is 0.5-20h;
And/or, the conditions of the first firing include: the temperature is 250-400 ℃ and the time is 3-10h.
10. The method of claim 8, wherein the concentration of the aqueous solution of phosphotungstic acid is 1-30%;
and/or the weight ratio of the spherical composite carrier to the aqueous solution of the phosphotungstic acid is 1: (5-50);
and/or, the conditions of the second reaction include: the temperature is 30-120 ℃ and the time is 0.5-20h;
and/or, the conditions of the second firing include: the temperature is 250-400 ℃ and the time is 3-10h.
11. Use of the spherical esterification catalyst according to any one of claims 1 to 7 in a synthesis reaction of n-butyl acetate.
CN202210090090.2A 2022-01-25 2022-01-25 Spherical esterification catalyst, preparation method thereof and application of spherical esterification catalyst in n-butyl acetate synthesis reaction Pending CN116532137A (en)

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