Catalyst and production method thereof, preparative acetonitrile and production method thereof

Abstract

The invention relates to the field of acetonitrile preparation, aims to solve the problems of complexity and energy consumption of an acetonitrile impurity removal process, and provides a production method of a catalyst for acetonitrile preparation, which comprises the following steps: S100, mixing 25-45 parts by weight of pseudo-boehmite, 10-15 parts by weight of activated carbon, 5-7 parts by weight of chromium sesquioxide and 2-8 parts by weight of P123, aging at 30-55 DEG C for 3-8 hours, and granulating to obtain a preform, the particle size of the preform is 50-80 nm; s200, sintering the preform for 2 to 4 hours at the temperature of 500 to 550 DEG C, and sintering for 6 to 8 hours at the temperature of 1100 to 1200 DEG C, so as to obtain a carrier; and S300, mixing 100-150 parts by weight of a carrier, 1-3 parts by weight of a noble metal precursor, 12-18 parts by weight of chitosan and 600-800 parts by weight of deionized water to obtain a mixed solution, heating and refluxing the mixed solution at 100-130 DEG C for 5-8 hours in a stirring state, and evaporating and drying at 115-135 DEG C for 0.5-2 hours to obtain the catalyst. The catalyst provided by the invention can effectively inhibit the occurrence of side reactions and reduce the use amount of ammonia gas, and can also 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 simpler when the catalyst is regenerated.

Description

Technical Field

[0001] The invention relates to the field of acetonitrile preparation, and in particular to a catalyst and a production method thereof, and preparation-grade acetonitrile and a production method thereof. Background Art

[0002] Preparation-grade acetonitrile refers to acetonitrile with high purity and stable quality. It is widely used in many fields, such as in high performance liquid chromatography. Preparation-grade acetonitrile is an innovative, environmentally friendly high-purity reagent with a purity of more than 99.9%, extremely low moisture content and good batch stability. Currently, common methods for preparing acetonitrile include acetylene amination, propylene ammoxidation by-product method, and acetic acid amination. Among them, the acetic acid amination method is to vaporize acetic acid and ammonia and put them into a reactor, and then an amination reaction occurs under the action of a catalyst with aluminum oxide as the carrier to obtain acetonitrile. When using existing catalysts, the acetonitrile impurity removal process is relatively long, the equipment occupies a large area, and the energy consumption is high.

[0003] The patent with publication number CN116173942A discloses a novel acetonitrile catalyst and a preparation method thereof, which uses nano-scale porous carbon as a carrier and supports metal compounds by an impregnation method, so that the catalyst can maintain high activity and selectivity for a long time.

[0004] The patent with publication number CN113457661A discloses a catalyst for synthesizing acetonitrile by ammoniation of acetic acid and a preparation method thereof. By adding a small amount of additives such as transition metals and rare earth metals, the catalyst stability is improved, the catalytic reaction temperature is greatly reduced, the catalyst coking is improved, the catalyst life is extended, and the catalyst activity and selectivity are improved.

[0005] The above patents all load catalytically active metals on the carrier skeleton to improve the catalytic effect, but do not consider the cumbersome and energy-consuming processes of subsequent catalyst regeneration and impurity removal. For example, the crude product of a reactor often requires 2 absorption towers and 2-3 distillation towers to achieve the production of preparative-grade acetonitrile. Summary of the invention

[0006] The object of the present invention is to provide a production method and a catalyst for preparing acetonitrile, so as to solve the problems of cumbersome and energy consumption of the acetonitrile impurity removal process.

[0007] The present invention also aims to provide a method for producing preparative-grade acetonitrile and acetonitrile, so as to solve the problems of large amount of existing ammonia and difficulty in impurity removal, and at the same time utilize the impurity removal process to regenerate the catalyst, thereby realizing the linkage between catalyst regeneration and acetonitrile preparation.

[0008] The embodiments of the present invention are implemented by the following technical solutions:

[0009] A method for producing a catalyst for preparing acetonitrile, comprising:

[0010] S100, by weight, 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, aged at 30-55° C. for 3-8 hours, and then granulated to obtain a preform, wherein the particle size of the preform is 50-80 nm;

[0011] S200, sintering the preform at 500-550° C. for 2-4 hours, and then sintering at 1100-1200° C. for 6-8 hours to obtain a carrier;

[0012] S300, by weight, 100-150 parts of a carrier, 1-3 parts of a precious 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° C. for 5-8 hours under stirring, and then evaporated to dryness at 115-135° C. for 0.5-2 hours to obtain a catalyst.

[0013] The present invention provides a catalyst that can reduce the water content in an acetonitrile product, and can also utilize the water in the catalyst after the reaction to achieve catalyst regeneration. Chromium trioxide reacts with activated carbon to generate chromium and carbon monoxide, and the metal chromium is loaded on the activated carbon. Pseudoboehmite is further dehydrated at high temperature to obtain aluminum trioxide. The temperature of the reaction of aluminum trioxide with carbon is above 1450°C, and the theoretical reaction temperature of carbon monoxide and aluminum trioxide is over 10,000°C, so the aluminum trioxide generated by the reaction in the present invention will not react further, and the metal chromium is also loaded on the aluminum trioxide. Pseudoboehmite has good adhesion and is conducive to the molding of preforms. P123 is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, which has good water-clearing properties. The propylene oxide block is hydrophobic, similar to an alkyl chain, and the ethylene oxide block is a hydrophilic head group, and 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°C, under the action of P123, pseudo-boehmite generates alumina with a worm-like channel structure, and the generated chromium after the secondary sintering can be loaded on the alumina. The viscosity of P123 also contributes to the molding of the preform. The thermal decomposition temperature of polyethylene oxide increases with the increase of molecular weight. During the sintering process of the present invention, the polyethylene oxide obtained after thermal decomposition of P123 no longer decomposes, and its polyhydroxy structure makes the catalyst have good water absorption. During the regeneration of the catalyst, the evaporation of water between the carbon deposit layer and the catalyst pore wall can more effectively peel off the carbon deposit layer than the added water vapor. The weight of the precious metal precursor refers to the weight of the precious metal in the precursor.

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

[0015] Palladium can further increase the catalytic effect of the catalyst, effectively inhibit the occurrence of side reactions, reduce the impurity content of the product, and increase the yield of acetonitrile, which can reach 96%. Chitosan can be loaded on the carrier. Chitosan contains coordination groups amino and hydroxyl groups, which have good coordination ability with metal ions. Palladium can be stably loaded on chitosan. At the same time, the hydrophilicity of chitosan is also conducive to the regeneration process of the catalyst.

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

[0017] Preferably, the mixed solution in S300 further comprises 16-28 parts of sodium silicate by weight.

[0018] With sodium silicate as the silicon source and pseudo-boehmite as the aluminum source, the catalyst can form a pore size of about 0.3 nm to further increase the catalyst's adsorption effect on water.

[0019] A catalyst is prepared by a production method of a catalyst for preparing acetonitrile.

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

[0021] Passing vaporized acetic acid and ammonia into a reactor loaded with the catalyst, the product of the reactor is subjected to an impurity removal process to obtain finished acetonitrile, the molar ratio of acetic acid to ammonia is 1:1.05-1:1.1, and the reaction temperature is 280-330°C;

[0022] The impurity removal process includes:

[0023] D100, passing the product of the reactor into an absorption tower to obtain a neutral pre-product, the absorption liquid of the absorption tower is an acid solution, the temperature of the absorption tower is 150-180° C., and the absorption tower carries the partially or completely deactivated catalyst;

[0024] D200, the pre-product is passed into an azeotropic distillation tower. During distillation, the tower top temperature is 65-85°C, the tower bottom temperature is 95-110°C, and the distillation pressure is 0.25-0.58MPa.

[0025] The absorption tower can remove ammonia in the product, and sulfuric acid can be selected as the absorption liquid. The azeotropic distillation tower can remove water in the product, and the purity of the final product acetonitrile is above 99.97%. In addition, the present invention can also regenerate the catalyst with the help of water adsorbed by the catalyst and high-temperature steam in the absorption tower. After the catalyst is improved, the amount of acetonitrile secondary reaction is reduced, so that although ammonia is still excessive, the amount used is much less than the prior art, so only one absorption tower is needed to complete the ammonia absorption. After adopting the catalyst provided by the present invention, the optimal reaction temperature is reduced and the energy consumption is reduced. After the chitosan system is changed, the thermal decomposition temperature is increased, and the chitosan will not be decomposed due to high temperature during the reaction process in conjunction with the decrease in reaction temperature.

[0026] Preferably, after the catalyst is taken out 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 can clean impurities on the catalyst surface, reduce the degree of catalyst blockage, and expose active sites. The regeneration sintering process can reduce the oxidized chromium again. The frequency of the ultrasonic oscillation process can be selected from 35-45kHz, the time can be selected from 5-8min, and the oscillation liquid can be selected from deionized water.

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

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

[0030] In the regeneration sintering process, there is no need to add additional reducing agents, such as using a reducing atmosphere CO, to achieve the reduction of the oxidized metals in the catalytic process.

[0031] Preferably, the absorption tower is provided with a transverse microporous membrane, the microporous membrane is permeable to air but not to liquid, the catalyst is located below the microporous membrane, the product of the reactor enters the absorption tower from the bottom, and the absorption liquid enters from the top.

[0032] The microporous membrane can be made of PTFE resin, and the pore size can be selected to be 0.5-1μm. PTFE resin has good acid and alkali resistance and high temperature resistance. The microporous membrane can be tilted to facilitate the timely recovery of the absorption liquid on the microporous membrane for recycling and avoid affecting the passage of gas through the microporous membrane. Since chitosan is used in the catalyst of the present invention, and chitosan may be hydrolyzed under the action of acidic absorption liquid, the present invention uses a microporous membrane to isolate the absorption liquid and the catalyst.

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

[0034] A method for producing preparative-grade acetonitrile to obtain acetonitrile.

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

[0036] The catalyst provided by the present invention can effectively inhibit the occurrence of side reactions, reduce the amount of ammonia used, and can also utilize the hydrophilic properties of the catalyst to make it easier to remove impurity layers on the catalyst surface, such as carbon deposits, when the catalyst is regenerated; the linkage between the impurity removal process and the catalyst regeneration reduces the energy consumption and water consumption of the catalyst regeneration. DETAILED DESCRIPTION

[0037] In order to make the purpose, method scheme and advantages of the embodiments of the present invention clearer, the method scheme in the embodiments of the present invention is clearly and completely described. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0038] Example 1

[0039] A method for producing a catalyst for preparing acetonitrile, comprising:

[0040] S100, in parts by weight, 25 parts of pseudo-boehmite, 10 parts of activated carbon, 5 parts of chromium trioxide and 2 parts of P123 were mixed, aged at 30° C. for 3 h, and then granulated to obtain a preform, wherein the particle size of the preform was 50 nm;

[0041] S200, sintering the preform at 500° C. for 2 h, and then sintering at 1100° C. for 6 h to obtain a carrier;

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

[0043] Example 2

[0044] A method for producing a catalyst for preparing acetonitrile, comprising:

[0045] S100, by weight, 45 parts of pseudo-boehmite, 15 parts of activated carbon, 7 parts of chromium trioxide and 8 parts of P123 were mixed, aged at 55° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 80 nm;

[0046] S200, sintering the preform at 550°C for 4 hours, and then sintering at 1200°C for 8 hours to obtain a carrier;

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

[0048] Example 3

[0049] A method for producing a catalyst for preparing acetonitrile, comprising:

[0050] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0051] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

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

[0053] Example 4

[0054] A method for producing a catalyst for preparing acetonitrile, comprising:

[0055] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0056] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

[0057] S300, by weight, 130 parts of a carrier, 2 parts of palladium chloride, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixed solution, the mixed solution is heated to reflux at 120° C. for 6 h under stirring, and then evaporated to dryness at 125° C. for 1 h to obtain a catalyst.

[0058] Example 5

[0059] A method for producing a catalyst for preparing acetonitrile, comprising:

[0060] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0061] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

[0062] S300, by weight, 130 parts of a carrier, 2 parts of tetraamminepalladium sulfate, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixed solution, the mixed solution is heated to reflux at 120° C. for 6 h under stirring, and then evaporated to dryness at 125° C. for 1 h to obtain a catalyst.

[0063] Example 6

[0064] A method for producing a catalyst for preparing acetonitrile, comprising:

[0065] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0066] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

[0067] S300, by weight, 130 parts of a carrier, 2 parts of tetraamminepalladium sulfate, 16 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixed solution, which is heated to reflux at 120° C. for 6 h under stirring, and then evaporated to dryness at 125° C. for 1 h to obtain a catalyst.

[0068] Example 7

[0069] A method for producing a catalyst for preparing acetonitrile, comprising:

[0070] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0071] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

[0072] S300, in parts by weight, 130 parts of a carrier, 2 parts of tetraamminepalladium sulfate, 28 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixed solution, the mixed solution is heated to reflux at 120° C. for 6 h under stirring, and then evaporated to dryness at 125° C. for 1 h to obtain a catalyst.

[0073] Example 8

[0074] A method for producing a catalyst for preparing acetonitrile, comprising:

[0075] S100, in parts by weight, 30 parts of pseudo-boehmite, 12 parts of activated carbon, 6 parts of chromium trioxide and 5 parts of P123 were mixed, aged at 45° C. for 8 hours, and then granulated to obtain a preform, wherein the particle size of the preform was 65 nm;

[0076] S200, sintering the preform at 530° C. for 3 h, and then sintering at 1150° C. for 7 h to obtain a carrier;

[0077] S300, by weight, 130 parts of a carrier, 2 parts of tetraamminepalladium sulfate, 22 parts of sodium silicate, 15 parts of chitosan and 700 parts of deionized water are mixed to obtain a mixed solution, which is heated to reflux at 120° C. for 6 h under stirring, and then evaporated to dryness at 125° C. for 1 h to obtain a catalyst.

[0078] Example 9

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

[0080] Passing vaporized acetic acid and ammonia into a reactor loaded with the catalyst of claim 4, the product of the reactor is subjected to an impurity removal process to obtain finished 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 comprises:

[0082] D100, the product of the reactor is fed into an absorption tower to obtain a neutral pre-product, the absorption liquid of the absorption tower is an acid solution, the temperature of the absorption tower is 150° C., and the absorption tower carries the partially or completely deactivated catalyst;

[0083] D200, the pre-product is passed into an azeotropic distillation tower. During distillation, the tower top temperature is 65°C, the tower bottom temperature is 95°C, and the distillation pressure is 0.2MPa.

[0084] Example 10

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

[0086] Passing vaporized acetic acid and ammonia into a reactor loaded with the catalyst of claim 4, the product of the reactor is subjected to an impurity removal process to obtain finished 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 comprises:

[0088] D100, the product of the reactor is fed into an absorption tower to obtain a neutral pre-product, the absorption liquid of the absorption tower is an acid solution, the temperature of the absorption tower is 180° C., and the absorption tower carries the partially or completely deactivated catalyst;

[0089] D200, the pre-product is passed into an azeotropic distillation tower. During distillation, the tower top temperature is 85°C, the tower bottom temperature is 110°C, and the distillation pressure is 0.58MPa.

[0090] Embodiment 11

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

[0092] Passing vaporized acetic acid and ammonia into a reactor loaded with the catalyst of claim 4, and obtaining finished acetonitrile through a product removal process from the reactor, wherein the molar ratio of acetic acid to ammonia is 1:1.07, and the reaction temperature is 300°C;

[0093] The impurity removal process comprises:

[0094] D100, the product of the reactor is introduced into an absorption tower to obtain a neutral pre-product, the absorption liquid of the absorption tower is an acid solution, the temperature of the absorption tower is 160° C., and the absorption tower carries the partially or completely deactivated catalyst;

[0095] D200, the pre-product is passed into an azeotropic distillation tower. During distillation, the tower top temperature is 75°C, the tower bottom temperature is 100°C, and the distillation pressure is 0.36MPa.

[0096] Test Example 1-8

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

[0098] Test Example 9-16

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

[0100] Test Examples 17-24

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

[0102] Experiment 1:

[0103] The purity of acetonitrile obtained in each test example was determined by gas chromatography, and the test conditions were as follows:

[0104] The carrier gas is nitrogen, the auxiliary gas is hydrogen, and the stationary liquid is polyethylene glycol and β,β'-dipropionitrile oxide. The carrier is 70 mesh Chromosorb WAW-DMCS, and the capillary column is FFAP bonded stationary phase quartz elastic capillary column, 50m long, 0.32mm inner diameter, and 0.52μm liquid film thickness. Column temperature: 54℃ constant temperature for 20min, increase to 200℃ at 10℃ / min and keep constant temperature for 20min. The injection port temperature is 160℃, and the detector temperature is 200℃. The carrier gas flow rate is 0.9mL / min, the split ratio is 100:1, and the injection volume is 0.4μL. Both butanone and acetone are chromatographically pure, the purity of acrylonitrile is 99.6%, and the purity of acetonitrile is 99.6%.

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

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

[0107] Where: A s Indicates the peak area of ​​the internal standard in the standard sample, mm 2 or integral value;

[0108] m i Indicates the mass of component i added to the standard sample, g;

[0109] A i It represents the peak area of ​​component i in the standard sample minus the peak area of ​​the component in the acetonitrile base solution, cm 2 or integral value;

[0110] m s Indicates the mass of the internal standard, g.

[0111] Sample determination: Use a clean, dry 50mL volumetric flask to weigh about 40g of acetonitrile to be tested on an analytical balance, accurate to 0.0001g. Then weigh 0.0200g of butanone, mix thoroughly, and perform chromatographic analysis under the same operating conditions as above to obtain the peak areas of each component and 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] Where: A i Indicates the peak area of ​​component i in the sample, mm 2 or integral value;

[0114] f iIt indicates the mass correction factor of component i in the sample relative to the internal standard butanone. The relative mass correction factor of the heavy component (including propyl ester) is 1.00.

[0115] m s Indicates the mass of internal standard butanone, g;

[0116] A s Indicates the peak area of ​​the internal standard butanone, mm 2 or integral value;

[0117] M represents the mass of the sample, g.

[0118] Acetonitrile purity X% (m / m) is calculated by X=100.0-(X 1 +X 2 +X 3 +X 4 +X 5 +X 6 )calculate:

[0119] Where: X 1 Indicates the total amount of organic impurities, % (m / m);

[0120] X 2 Indicates moisture content, % (m / m);

[0121] X 3 Indicates acidity, % (m / m);

[0122] X 4 Indicates the content of hydrocyanic acid, % (m / m);

[0123] X 5 Indicates ammonia content, % (m / m);

[0124] X 6 Indicates copper and iron content, % (m / m).

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

[0126] Table 1

[0127]

[0128] From the test results of test examples 1-24, it can be seen that the purity of acetonitrile provided by the present invention is greater than 99.95%, and the purity of acetonitrile is significantly increased after sodium silicate is added to the catalyst component. Under the condition of adding sodium silicate, the production conditions of Example 10 are better, and under the condition of not adding sodium silicate, the production conditions of Example 11 are better.

[0129] Experiment 2:

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

[0131] Table 2

[0132]

[0133] From the test results of Test Examples 1-24, it can be seen that acetonitrile has good low ultraviolet absorbance.

[0134] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for producing a catalyst for preparing acetonitrile, characterized in that: include: S100, by weight, 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, aged at 30-55° C. for 3-8 hours, and then granulated to obtain a preform, wherein the particle size of the preform is 50-80 nm; S200, sintering the preform at 500-550° C. for 2-4 hours, and then sintering at 1100-1200° C. for 6-8 hours to obtain a carrier; S300, by weight, 100-150 parts of a carrier, 1-3 parts of a precious 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° C. for 5-8 hours under stirring, and then evaporated to dryness at 115-135° C. for 0.5-2 hours to obtain a 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: In parts by weight, the mixed solution in S300 also includes 16-28 parts of sodium silicate.

4. A catalyst prepared by the production method of the catalyst for preparing acetonitrile according to any one of claims 1 to 3.

5. A method for producing preparative-grade acetonitrile, characterized in that: include: Passing vaporized acetic acid and ammonia into a reactor loaded with the catalyst of claim 4, and obtaining finished acetonitrile through a de-impurity process, wherein the molar ratio of acetic acid to ammonia is 1:1.05-1:1.1, and the reaction temperature is 280-330°C; The impurity removal process comprises: D100, the product of the reactor is fed into an absorption tower to obtain a neutral pre-product, the absorption liquid of the absorption tower is an acid solution, the temperature of the absorption tower is 150-180° C., and the absorption tower carries the partially or completely deactivated catalyst; D200, the pre-product is passed into an azeotropic distillation tower. During distillation, the tower top temperature is 65-85°C, the tower bottom temperature is 95-110°C, and the distillation pressure is 0.25-0.58MPa.

6. The method for producing preparative-grade acetonitrile according to claim 5, wherein After the catalyst is taken out from the absorption tower, it is sequentially subjected to an ultrasonic oscillation process and a regeneration sintering process to obtain a regenerated catalyst.

7. The method for producing preparative-grade acetonitrile according to claim 6, wherein The sintering temperature of the regeneration sintering process is 1000-1100° C., and the sintering time is 1-2 hours.

8. The method for producing preparative-grade acetonitrile according to claim 7, wherein The absorption tower is provided with a transverse microporous membrane, which is air-permeable but liquid-impermeable. The catalyst is located below the microporous membrane. The product of the reactor enters the absorption tower from the bottom, and the absorption liquid enters from the top.

9. The method for producing preparative-grade acetonitrile according to claim 8, wherein After the catalyst has been regenerated 120-150 times, it can no longer be used as a catalyst.

10. An acetonitrile obtained by the method for producing preparative-grade acetonitrile according to any one of claims 5 to 9.

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