A catalyst and a method for producing the same, acetonitrile of preparation grade and a method for producing the same

Abstract

The application relates to the field of acetonitrile preparation, and aims to solve the problems of complicated acetonitrile impurity removal process and energy consumption, and provides a production method of a catalyst for acetonitrile preparation, which comprises the following steps: S100, 25-45 parts of pseudo-boehmite, 10-15 parts of activated carbon, 5-7 parts of chromium trioxide and 2-8 parts of P123 are mixed, then aging is carried out at 30-55 DEG C for 3-8 h, granulation is carried out to obtain a preform, and the particle size of the preform is 50-80 nm; S200, the preform is sintered at 500-550 DEG C for 2-4 h and sintered at 1100-1200 DEG C for 6-8 h to obtain a carrier; S300, 100-150 parts of the carrier, 1-3 parts of a noble metal precursor, 12-18 parts of chitosan and 600-800 parts of deionized water are mixed to obtain a mixed solution, the mixed solution is heated to reflux at 100-130 DEG C for 5-8 h under stirring, and then evaporative drying is carried out at 115-135 DEG C for 0.5-2 h to obtain the catalyst. The catalyst provided by the application can effectively inhibit the occurrence of a side reaction, reduce the ammonia gas consumption, and also can utilize the hydrophilic property of the catalyst to make the removal of an impurity layer, such as a carbon deposition layer, on the surface of the catalyst more simple during catalyst regeneration.

Description

Technical Field

[0001] This invention relates to the field of acetonitrile preparation, and more specifically, to a catalyst and its production method, and a preparative acetonitrile and its production method. Background Technology

[0002] Preparative-grade acetonitrile refers to acetonitrile with high purity and stable quality, and it has wide applications in many fields, such as high-performance liquid chromatography (HPLC). Preparative-grade acetonitrile is an innovative, environmentally friendly, high-purity reagent with a purity exceeding 99.9%, extremely low moisture content, and good batch stability. Common methods for preparing acetonitrile include acetylene ammoniation, propylene ammoxidation as a byproduct, and acetic acid ammoniation. In the acetic acid ammoniation method, acetic acid and ammonia are vaporized and added to a reaction vessel, where an ammoniation reaction occurs under the action of a catalyst supported on aluminum oxide to obtain acetonitrile. However, when using existing catalysts, the acetonitrile impurity removal process is lengthy, requires large equipment footprint, and has high energy consumption.

[0003] The patent with publication number CN116173942A discloses a novel acetonitrile catalyst and its preparation method. It uses nano-sized porous carbon as a support and impregnates metal compounds to maintain high activity and selectivity for a long time.

[0004] The patent with publication number CN113457661A discloses a catalyst for the synthesis of acetonitrile by ammoniation of acetic acid and its preparation method. The addition of a small amount of transition metals and rare earth metals as auxiliaries improves the stability of the catalyst, significantly reduces the catalytic reaction temperature, improves the coking of the catalyst, extends the catalyst life, and enhances the catalyst activity and selectivity.

[0005] The aforementioned patents all involve loading catalytically active metals onto a support framework to improve catalytic performance, but they do not consider the complexities and energy consumption associated with subsequent catalyst regeneration and impurity removal processes. For example, the crude product from a single reactor often requires two absorption towers and two to three distillation towers to produce preparative-grade acetonitrile. Summary of the Invention

[0006] The purpose of this invention is to provide a production method and catalyst for acetonitrile preparation, thereby solving the problems of cumbersome acetonitrile removal process and energy consumption.

[0007] The present invention also aims to provide a method for producing preparative acetonitrile and acetonitrile, which solves the problems of large ammonia consumption and difficulty in impurity removal in existing methods. At the same time, the method utilizes the impurity removal process to regenerate the catalyst, thereby achieving the linkage between catalyst regeneration and acetonitrile preparation.

[0008] The embodiments of the present invention are achieved through the following technical solutions:

[0009] A method for producing a catalyst for acetonitrile preparation includes:

[0010] S100, by weight, 25-45 parts of boehmite, 10-15 parts of activated carbon, 5-7 parts of chromium trioxide and 2-8 parts of P123 are mixed and aged at 30-55℃ for 3-8 hours, and then granulated to obtain a preform with a particle size of 50-80 nm.

[0011] S200: Sinter the preform at 500-550℃ for 2-4 hours, and then sinter at 1100-1200℃ for 6-8 hours to obtain the carrier;

[0012] S300: By weight, 100-150 parts of support, 1-3 parts of noble metal precursor, 12-18 parts of chitosan and 600-800 parts of deionized water are mixed to obtain a mixture. The mixture is heated under stirring and refluxed at 100-130℃ for 5-8 hours, and then evaporated and dried at 115-135℃ for 0.5-2 hours to obtain the catalyst.

[0013] This invention provides a catalyst that can reduce the water content in acetonitrile products, while simultaneously utilizing the water in the catalyst after the reaction to achieve catalyst regeneration. Chromium trioxide reacts with activated carbon to produce chromium and carbon monoxide, with metallic chromium supported on the activated carbon. Boehmite is further dehydrated at high temperature to obtain aluminum oxide. The reaction temperature of aluminum oxide with carbon is above 1450℃, and the theoretical reaction temperature of carbon monoxide with aluminum oxide is tens of thousands of degrees Celsius. Therefore, the aluminum oxide produced in this invention will not react further, and metallic chromium is also supported on the aluminum oxide. Boehmite has good adhesion, which is beneficial for the molding of preforms. P123 is a poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) triblock copolymer with good water-repellent properties. The propylene oxide blocks are hydrophobic, similar to alkyl chains, while the ethylene oxide blocks act as hydrophilic head groups. The entire molecule is similar to a copolymer with hydrophilic head groups at both ends and a hydrophobic chain in the middle. During the primary sintering process at 500-550℃, under the action of P123, boehmite forms alumina with a worm-like channel structure. After secondary sintering, chromium is generated and can be supported on the alumina. The viscosity of P123 also facilitates the formation of the preform. The thermal decomposition temperature of polyethylene oxide increases with increasing molecular weight. In this invention, during the sintering process, P123 decomposes upon heating to obtain polyethylene oxide, which does not decompose further. Its polyhydroxy structure gives the catalyst good water absorption. During catalyst regeneration, the evaporation of water located between the carbon deposit layer and the catalyst pore walls is more effective at stripping the carbon deposit layer than externally added water vapor. The weight percentage of the noble metal precursor refers to the weight of the noble metal in the precursor.

[0014] Preferably, the noble metal precursor comprises tetraamminepalladium sulfate.

[0015] Palladium can further enhance the catalytic effect of the catalyst, effectively suppress side reactions, reduce product impurity content, and increase the yield of acetonitrile, which can reach 96%. Chitosan can be supported on the carrier. Chitosan contains coordinating amino and hydroxyl groups, which have good coordination ability with metal ions. Palladium can stably support chitosan. At the same time, the hydrophilic properties of chitosan are also beneficial to the catalyst regeneration process.

[0016] Tetraamminepalladium sulfate is readily soluble in water and does not require acidic or alkaline solutions for dissolution, thus avoiding the degradation of chitosan.

[0017] Preferably, the mixture in S300 further includes 16-28 parts by weight of sodium silicate.

[0018] When sodium silicate is used as the silicon source and boehmite is used as the aluminum source, the catalyst can form pores with a diameter of about 0.3 nm, which further increases the catalyst's adsorption effect on water.

[0019] A catalyst prepared by a method for producing a catalyst for acetonitrile preparation.

[0020] A method for producing preparative grade acetonitrile, comprising:

[0021] Vaporized acetic acid and ammonia are introduced into a reactor containing the catalyst. The product from the reactor is purified to obtain acetonitrile. The molar ratio of acetic acid to ammonia is 1:1.05-1:1.1, and the reaction temperature is 280-330℃.

[0022] The impurity removal process includes:

[0023] D100. After the product from the reactor is passed into the absorption tower, a neutral pre-product is obtained. The absorbent in the absorption tower is an acidic solution, and the temperature of the absorption tower is 150-180℃. The absorption tower carries the catalyst that has been partially or completely deactivated.

[0024] D200. The preproduct is fed into an azeotropic distillation column. During distillation, the top temperature of the column is 65-85℃, the bottom temperature is 95-110℃, and the distillation pressure is 0.25-0.58MPa.

[0025] The absorption tower removes ammonia from the product, and sulfuric acid can be used as the absorbent. An azeotropic distillation tower removes water from the product, resulting in a final acetonitrile purity of over 99.97%. Furthermore, this invention utilizes water adsorbed by the catalyst and high-temperature steam in the absorption tower to regenerate the catalyst. The improved catalyst reduces the amount of secondary acetonitrile reaction, thus, although ammonia is still present in excess, the amount used is far less than in existing technologies, requiring only one absorption tower to complete ammonia absorption. Using the catalyst provided by this invention lowers the optimal reaction temperature and reduces energy consumption. The modified chitosan system increases the thermal decomposition temperature, which, combined with the decreased reaction temperature, prevents chitosan from decomposing due to high temperatures during the reaction.

[0026] Preferably, after the catalyst is removed from the absorption tower, it is sequentially subjected to an ultrasonic oscillation process and a regeneration sintering process to obtain a regenerated catalyst.

[0027] The ultrasonic oscillation process cleans impurities from the catalyst surface, reduces catalyst blockage, and exposes active sites. The regeneration sintering process reduces oxidized chromium again. The ultrasonic oscillation frequency can be selected from 35-45 kHz, the duration from 5-8 minutes, and the oscillation solution can be deionized water.

[0028] Since some of the impurities on the surface of the catalyst in the absorption tower have been cleaned, and the binding force between the remaining impurities and the catalyst has been reduced, the ultrasonic oscillation time is relatively short.

[0029] Preferably, the sintering temperature of the regeneration sintering process is 1000-1100℃, and the sintering time is 1-2h.

[0030] In the regeneration sintering process, no additional reducing agent is needed. For example, the reduction of oxidized metals during the catalytic process can be achieved by using a reducing atmosphere of CO.

[0031] Preferably, the absorption tower is provided with a transverse microporous membrane, the microporous membrane is permeable to air but impermeable to liquid, the catalyst is located below the microporous membrane, the product of the reactor enters from the bottom of the absorption tower, and the absorption liquid enters from the top of the absorption tower.

[0032] The microporous membrane can be made of PTFE resin with a pore size of 0.5-1 μm. PTFE resin has good acid and alkali resistance and high temperature resistance. The microporous membrane can be tilted to facilitate timely recovery of the absorbent liquid on the membrane for recycling and to prevent it from affecting gas passage. Since chitosan is used in the catalyst of this invention, and chitosan may hydrolyze under the action of acidic absorbent liquid, this invention uses a microporous membrane to separate the absorbent liquid from the catalyst.

[0033] Preferably, the catalyst is no longer used as a catalyst after being regenerated 120-150 times.

[0034] Acetonitrile produced by a method for preparing grade acetonitrile.

[0035] The present invention has at least the following beneficial effects:

[0036] The catalyst provided by this invention can effectively suppress the occurrence of side reactions and reduce the amount of ammonia used. Furthermore, the hydrophilic properties of the catalyst make it easier to remove impurity layers, such as carbon deposits, from the catalyst surface during regeneration. The linkage between the impurity removal process and catalyst regeneration reduces the energy consumption and water usage during catalyst regeneration. Detailed Implementation

[0037] To make the objectives, methods, and advantages of the embodiments of the present invention clearer, the methods in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.

[0038] Example 1

[0039] A method for producing a catalyst for acetonitrile preparation includes:

[0040] S100. By weight, 25 parts of pseudoboehmite, 10 parts of activated carbon, 5 parts of chromium trioxide and 2 parts of P123 are mixed and aged at 30°C for 3 hours, and then granulated to obtain a preform with a particle size of 50 nm.

[0041] S200. The preform is sintered at 500°C for 2 hours, and then sintered at 1100°C for 6 hours to obtain the carrier.

[0042] S300, by weight, 100 parts of carrier, 1 part of rhodium chloride, 12 parts of chitosan and 600 parts of deionized water are mixed to obtain a mixture. The mixture is heated under stirring and refluxed at 100°C for 5 hours, and then evaporated and dried at 115°C for 0.5 hours to obtain the catalyst.

[0043] Example 2

[0044] A method for producing a catalyst for acetonitrile preparation includes:

[0045] S100. By weight, 45 parts of pseudoboehmite, 15 parts of activated carbon, 7 parts of chromium trioxide and 8 parts of P123 are mixed and aged at 55°C for 8 hours, and then granulated to obtain a preform with a particle size of 80 nm.

[0046] S200. The preform is sintered at 550°C for 4 hours, and then sintered at 1200°C for 8 hours to obtain the carrier.

[0047] S300, by weight, 150 parts of carrier, 3 parts of rhodium chloride, 18 parts of chitosan and 800 parts of deionized water are mixed to obtain a mixture. The mixture is heated under stirring and refluxed at 130°C for 8 hours, and then evaporated and dried at 135°C for 2 hours to obtain the catalyst.

[0048] Example 3

[0049] A method for producing a catalyst for acetonitrile preparation includes:

[0050] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0051] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0052] S300, by weight, 130 parts of carrier, 2 parts of rhodium chloride, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixture. The mixture is heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0053] Example 4

[0054] A method for producing a catalyst for acetonitrile preparation includes:

[0055] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0056] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0057] S300, by weight, 130 parts of support, 2 parts of palladium chloride, 15 parts of chitosan and 700 parts of deionized water were mixed to obtain a mixture. The mixture was heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0058] Example 5

[0059] A method for producing a catalyst for acetonitrile preparation includes:

[0060] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0061] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0062] S300, by weight, 130 parts of support, 2 parts of tetraamminepalladium sulfate, 15 parts of chitosan and 700 parts of deionized water were mixed to obtain a mixture. The mixture was heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0063] Example 6

[0064] A method for producing a catalyst for acetonitrile preparation includes:

[0065] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0066] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0067] S300, by weight, 130 parts of support, 2 parts of tetraamminepalladium sulfate, 16 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water were mixed to obtain a mixture. The mixture was heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0068] Example 7

[0069] A method for producing a catalyst for acetonitrile preparation includes:

[0070] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0071] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0072] S300, by weight, 130 parts of support, 2 parts of tetraamminepalladium sulfate, 28 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water were mixed to obtain a mixture. The mixture was heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0073] Example 8

[0074] A method for producing a catalyst for acetonitrile preparation includes:

[0075] S100. By weight, 30 parts of boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 are mixed and aged at 45°C for 8 hours, and then granulated to obtain a preform with a particle size of 65 nm.

[0076] S200. The preform is sintered at 530°C for 3 hours, and then sintered at 1150°C for 7 hours to obtain the carrier.

[0077] S300, by weight, 130 parts of support, 2 parts of tetraamminepalladium sulfate, 22 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water were mixed to obtain a mixture. The mixture was heated under stirring and refluxed at 120°C for 6 hours, and then evaporated and dried at 125°C for 1 hour to obtain the catalyst.

[0078] Example 9

[0079] A method for producing preparative grade acetonitrile, comprising:

[0080] Vaporized acetic acid and ammonia are introduced into a reactor containing the catalyst. The product from the reactor is purified to obtain acetonitrile. The molar ratio of acetic acid to ammonia is 1:1.05, and the reaction temperature is 280°C.

[0081] The impurity removal process includes:

[0082] D100. After the product from the reactor is fed into the absorption tower, a neutral pre-product is obtained. The absorbent in the absorption tower is an acidic solution, and the temperature of the absorption tower is 150°C. The absorption tower carries the catalyst that has been partially or completely deactivated.

[0083] D200. The preproduct is fed into an azeotropic distillation column. During distillation, the top temperature of the column is 65℃, the bottom temperature is 95℃, and the distillation pressure is 0.2MPa.

[0084] Example 10

[0085] A method for producing preparative grade acetonitrile, comprising:

[0086] Vaporized acetic acid and ammonia are introduced into a reactor containing the catalyst. The product from the reactor is purified to obtain acetonitrile. The molar ratio of acetic acid to ammonia is 1:1.1, and the reaction temperature is 330°C.

[0087] The impurity removal process includes:

[0088] D100. After the product from the reactor is fed into the absorption tower, a neutral pre-product is obtained. The absorbent in the absorption tower is an acidic solution, and the temperature of the absorption tower is 180°C. The absorption tower carries the catalyst that has been partially or completely deactivated.

[0089] D200. The preproduct is fed into an azeotropic distillation column. During distillation, the top temperature of the column is 85℃, the bottom temperature is 110℃, and the distillation pressure is 0.58MPa.

[0090] Example 11

[0091] A method for producing preparative grade acetonitrile, comprising:

[0092] Vaporized acetic acid and ammonia are introduced into a reactor containing the catalyst. The product from the reactor is purified to obtain acetonitrile. The molar ratio of acetic acid to ammonia is 1:1.07, and the reaction temperature is 300°C.

[0093] The impurity removal process includes:

[0094] D100. After the product from the reactor is fed into the absorption tower, a neutral pre-product is obtained. The absorbent in the absorption tower is an acidic solution, and the temperature of the absorption tower is 160°C. The absorption tower carries the catalyst that has been partially or completely deactivated.

[0095] D200. The preproduct is fed into an azeotropic distillation column. During distillation, the top temperature of the column is 75℃, the bottom temperature is 100℃, and the distillation pressure is 0.36MPa.

[0096] Experimental Examples 1-8

[0097] Acetonitrile was prepared using the production method of Example 9. Test Example 1 used the catalyst prepared in Example 1, Test Example 2 used the catalyst prepared in Example 2, and so on.

[0098] Experimental Examples 9-16

[0099] Acetonitrile was prepared using the production method of Example 10. Test Example 9 used the catalyst prepared in Example 1, Test Example 10 used the catalyst prepared in Example 2, and so on.

[0100] Experimental Examples 17-24

[0101] Acetonitrile was prepared using the production method of Example 11, and the catalyst prepared in Example 17 was used in Example 1, the catalyst prepared in Example 2 was used in Example 18, and so on.

[0102] Experiment 1:

[0103] The purity of the acetonitrile prepared in each test example was determined by gas chromatography under the following conditions:

[0104] Nitrogen was used as the carrier gas, hydrogen as the auxiliary gas, and polyethylene glycol and β,β'-dipropionitrile oxide as the stationary phase. The support was a 70-mesh Chromosorb WAW-DMCS column, and the capillary column was an FFAP-bonded quartz flexible capillary column, 50 m long, 0.32 mm inner diameter, and with a film thickness of 0.52 μm. Column temperature: 54℃ for 20 min, increased to 200℃ at a rate of 10℃ / min, and held for 20 min. Injector temperature: 160℃, detector temperature: 200℃. Carrier gas flow rate: 0.9 mL / min, split ratio: 100:1, injection volume: 0.4 μL. Butanone and acetone were of chromatographic purity, acrylonitrile purity: 99.6%, and acetonitrile purity: 99.6%.

[0105] Determination of relative mass correction factor: Using a clean, dry 50 mL volumetric flask, weigh 40 g of acetonitrile as the base solution on an analytical balance, accurate to 0.0002 g. Then add 0.0030 g of acetone, 0.0040 g of acrylonitrile, and 0.0200 g of butanone, mix thoroughly to obtain the prepared quantitative standard sample. Inject this standard sample and the acetonitrile base solution three times each, and obtain six sets of data with similar areas. Calculate the average area of ​​each component in the two samples, and calculate the relative mass correction factor (f) of each component according to formula (1). i ).

[0106] f i =A s m i / (A i m s )

[0107] In the formula: A s This indicates the peak area of ​​the internal standard in the standard sample, in mm. 2 Or integral value;

[0108] m i This represents the mass of component i added to the standard sample, in grams.

[0109] A i This represents the difference between the peak area of ​​component i in the standard sample and the peak area of ​​the same component in the acetonitrile-based solution, in cm⁻¹. 2 Or integral value;

[0110] m s The mass of the internal standard is expressed in grams (g).

[0111] Sample determination: Using a clean, dry 50 mL volumetric flask, weigh approximately 40 g of acetonitrile (accurate to 0.0001 g) onto an analytical balance. Then weigh in 0.0200 g of butanone (methyl ethyl ketone), mix thoroughly, and perform chromatographic analysis under the same operating conditions as above. Obtain the peak areas of each component and the internal standard. Repeat the determination twice and calculate the mass percentage X of each component i. i %.

[0112] X i =A i f i m s / (A s m) x100

[0113] In the formula: A i The peak area of ​​component i in the sample is represented in mm. 2 Or integral value;

[0114] f iThe mass correction factor for component i in the sample relative to the internal standard methyl ethyl ketone is given; the mass correction factor for heavy components (including propyl acetate) is 1.00.

[0115] m s The mass of the internal standard, butanone, is expressed in grams.

[0116] A s The peak area of ​​the internal standard methyl ethyl ketone (MEK) is expressed in mm. 2 Or integral value;

[0117] M represents the mass of the sample, in grams.

[0118] The purity of acetonitrile, X % (m / m), is calculated as X = 100.0 - (X1 + X2 + X3 + X4 + X5 + X6):

[0119] In the formula: X1 represents the total amount of organic impurities, % (m / m);

[0120] X2 represents the moisture content, % (m / m);

[0121] X3 indicates acidity, % (m / m);

[0122] X4 indicates the hydrocyanic acid content, % (m / m);

[0123] X5 indicates the ammonia content, % (m / m);

[0124] X6 indicates the copper and iron content, % (m / m).

[0125] Each test case was repeated 10 times. The purity of acetonitrile was taken as the average of the 10 test results. The process stability was judged by the fluctuation of the 10 test results (the fluctuation should not exceed 0.02%). The results are shown in Table 1.

[0126] Table 1

[0127]

[0128] The experimental results of Examples 1-24 show that the purity of the acetonitrile provided by this invention is greater than 99.95%. The purity of acetonitrile significantly increases after adding sodium silicate to the catalyst component. Under the condition of adding sodium silicate, the production conditions of Example 10 are better; under the condition of not adding sodium silicate, the production conditions of Example 11 are better.

[0129] Experiment 2:

[0130] The absorbance of acetonitrile prepared in each experimental example was measured by ultraviolet spectrophotometry, and the results are shown in Table 2.

[0131] Table 2

[0132]

[0133] The test results of Examples 1-24 show that acetonitrile has good low UV absorbance.

[0134] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for producing preparative grade acetonitrile, characterized in that, include: Vaporized acetic acid and ammonia are introduced into a reactor carrying a catalyst. The product from the reactor is purified to obtain acetonitrile. The molar ratio of acetic acid to ammonia is 1:1.05-1:1.1, and the reaction temperature is 280-330℃. The impurity removal process includes: D100, the product from the reactor enters the absorption tower to obtain a neutral pre-product. The absorbent in the absorption tower is an acidic solution, and the temperature of the absorption tower is 150-180℃. The absorption tower carries the catalyst that has been partially or completely deactivated. D200. The preproduct is fed into an azeotropic distillation column. During distillation, the top temperature of the column is 65-85℃, the bottom temperature is 95-110℃, and the distillation pressure is 0.25-0.58MPa. The method for producing the catalyst includes: S100, by weight, 25-45 parts of boehmite, 10-15 parts of activated carbon, 5-7 parts of chromium trioxide and 2-8 parts of P123 are mixed and aged at 30-55℃ for 3-8 hours, and then granulated to obtain a preform with a particle size of 50-80 nm. S200: Sinter the preform at 500-550℃ for 2-4 hours, and then sinter at 1100-1200℃ for 6-8 hours to obtain the carrier; S300: By weight, 100-150 parts of support, 1-3 parts of noble metal precursor, 12-18 parts of chitosan and 600-800 parts of deionized water are mixed to obtain a mixture. The mixture is heated under stirring and refluxed at 100-130℃ for 5-8 hours, and then evaporated and dried at 115-135℃ for 0.5-2 hours to obtain the catalyst.

2. The production method according to claim 1, characterized in that, The noble metal precursor includes tetraamminepalladium sulfate.

3. The production method according to claim 1 or 2, characterized in that, The mixture in S300 also includes 16-28 parts by weight of sodium silicate.

4. The production method according to claim 3, characterized in that, After the catalyst is removed from the absorption tower, it undergoes an ultrasonic oscillation process and a regeneration sintering process in sequence to obtain a regenerated catalyst.

5. The production method according to claim 4, characterized in that, The sintering temperature of the regeneration sintering process is 1000-1100℃, and the sintering time is 1-2h.

6. The production method according to claim 3, characterized in that, The absorption tower is equipped with a transverse microporous membrane that is permeable to air but impermeable to liquid. The catalyst is located below the microporous membrane. The product from the reactor enters the absorption tower from the bottom, and the absorbent enters from the top of the absorption tower.

7. The production method according to claim 6, characterized in that, After being regenerated 120-150 times, the catalyst is no longer used as a catalyst.

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