A catalyst for preparing methacrylonitrile from n-propyl aldehyde by one-step method, its preparation method and application
The one-step preparation of methacrylonitrile in a fixed bed using FeMxQyMnzXaPmOn catalyst solves the problems of complex preparation methods and high costs in existing technologies, and realizes efficient and low-cost preparation of methacrylonitrile, which has green economic and industrial application prospects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN INSTITUTE OF CHEMICAL PHYSICS CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2024-12-02
- Publication Date
- 2026-06-02
AI Technical Summary
In the existing technology, the preparation methods of methacrylonitrile have problems such as high raw material costs, large equipment investment, complicated steps and environmental pollution. In particular, the method of preparing methacrylonitrile from n-propionaldehyde has not yet achieved an efficient one-step reaction.
Methacrylonitrile was prepared by a one-step reaction of propanal with carbon dioxide and ammonia in a fixed bed using a FeMxQyMnzXaPmOn catalyst. The catalyst consisted of Fe, M, Q, Mn, X and P, and was prepared in multiple steps and applied in a fixed bed. The reaction conditions were controlled to achieve high selectivity and yield.
This method enables the efficient one-step preparation of methacrylonitrile from n-propionaldehyde, maintaining high yield and selectivity while reducing raw material costs. It possesses both green economic value and industrial application potential.
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Abstract
Description
Technical Field
[0001] This invention relates to the field of improved catalyst preparation technology, and specifically to a catalyst preparation method and application for the one-step preparation of methacrylonitrile from n-propionaldehyde. Background Technology
[0002] Methacrylonitrile (MAN) is an important chemical raw material. Due to its inherent properties, it can be homopolymerized or copolymerized with other monomers to obtain a series of polymer materials. Furthermore, methacrylonitrile can also be used as an intermediate product to prepare downstream products, such as polymethacrylimide and methyl methacrylate. It has wide applications in aerospace, transportation, acrylic glass, coatings, and other fields.
[0003] There are several methods for preparing methacrylonitrile, including ammoxidation of methacryl alcohol or methacrylaldehyde, methyl methacrylate, and methacrylic acid. All these methods require raw materials derived from upstream products. Directly purchasing these raw materials is costly, while preparing them requires significant upfront investment. Tomoya Inoue et al. prepared methacrylonitrile using isobutylene (Reference: Inoue T, Tomishige K, Iwasawa Y. Catalytic synthesis of unsaturated nitriles from NO–alkane or NO–alkene on Pt–Sn / SiO2[J]. Journal of the Chemical Industry). Society, Chemical Communications, 1995(3):329-330.), using Pt-Sn / SiO2 as catalyst and NO as nitrogen source, although its yield is high, reaching over 90%, NO as reactant may cause environmental pollution. At the same time, the catalyst uses Pt as raw material, which leads to a high cost of catalyst; Patent CN114907233A also uses isobutylene to prepare methacrylonitrile, using fluidized bed process and catalysts containing V, Mo, P, and Co and silicon oxide as support. Through ammonia oxidation, its yield can reach over 85%, which is high. Moreover, the nitrogen source is changed to ammonia, which reduces environmental pollution. However, the price of raw material isobutylene is also relatively high, which will increase its cost; Patent US20030135071 Patents A1, WO2001019511A1, WO2000046185A1, and EP945432A1 use slightly cheaper isobutane as the product, but its conversion rate is low, less than 30%, and its selectivity is also low. Although the large amount of byproducts is useful, it is not a good choice for the preparation of methacrylonitrile.
[0004] Propanal is relatively inexpensive and has potential as a raw material for the production of methacrylonitrile. Currently, industrially, using propanal as a raw material for methacrylonitrile requires a two-step process: first, propanal and formaldehyde undergo a condensation reaction to obtain methacrolein, and then methacrolein is ammoniated to yield methacrylonitrile. While this method yields high yields, the two-step reaction requires two separate sets of equipment, making the process relatively cumbersome and increasing equipment costs. Therefore, it is necessary to design a catalyst and reaction that allows for a one-step reaction of propanal to produce methacrylonitrile while maintaining high yield and selectivity.
[0005] A catalyst was developed that can produce methacrylonitrile from n-propaldehyde in one step while maintaining high yield and selectivity. Summary of the Invention
[0006] A catalyst for the one-step preparation of methacrylonitrile from n-propionaldehyde, having a composition of FeM x Q y Mn z X a P m O n Its preparation method consists of the following three steps:
[0007] Step 1: First, the precursor of X is mixed with 5 mol / L-15 mol / L phosphoric acid, preferably 10 mol / L-12 mol / L, and refluxed at 80℃-120℃ for 8h-36h. Then, it is cooled to room temperature and filtered, and washed several times with 0.01 mol / L-1 mol / L phosphoric acid. After that, it is washed with deionized water until neutral, and dried at 80℃-150℃ for 8h-48h, preferably 100℃-120℃ for 12h-36h, to obtain solid A.
[0008] Step 2: Prepare aqueous solutions of soluble salts of M and Q, soluble salts containing divalent manganese, and soluble salts containing divalent iron, respectively, wherein the molar ratio of M, Q, Mn, and Fe is x:y:z:1; disperse solid A in deionized water and stir continuously, then add the four solutions dropwise to the dispersion of A, and reflux at 80℃-120℃ for 2-5 days; filter the mixture while hot, wash the solid with deionized water until colorless, and then dry it at 80℃-150℃ for 8-48 hours, preferably at 100℃-120℃ for 12-36 hours; then cool to room temperature to obtain solid B.
[0009] Step 3: Grind the solid B obtained in Step 2 for 10-60 minutes, preferably 15-30 minutes; then calcine it in a muffle furnace at a temperature of 150℃-350℃, preferably 200℃-300℃, for 2-24 hours, preferably 4-18 hours; then cool it to room temperature and add an aqueous solution of 0.05 mol / L-5 mol / L acid, preferably 0.1 mol / L-3 mol / L; stir thoroughly for 15-120 minutes and then filter, preferably 30-90 minutes; then repeat the stirring and filtration process 2-3 times; finally, wash the obtained solid three times with deionized water and dry it at 80℃-150℃ for 8-48 hours, preferably 100℃-120℃, for 12-36 hours, then grind or ball mill it to obtain the final catalyst C, which is used in a fixed bed.
[0010] In the catalyst composition, x takes the value of 0.25-3, preferably 0.5-2; y takes the value of 1-10, preferably 1.5-8; z takes the value of 0.25-15, preferably 0.5-10; a takes the value of 6-27, preferably 8-24; m takes the value of 4-27, preferably 6-25; and n takes the value of oxygen atoms required for the oxidation state of the metal.
[0011] In the catalyst preparation method, X is one or more of magnesium, aluminum, titanium, zirconium, etc. Specifically, the precursor for magnesium is one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, etc.; the precursor for aluminum is one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, etc.; the precursor for titanium is one or more of titanium tetrachloride, titanium oxysulfate, titanium oxychloride, titanium nitrate, etc.; and the precursor for zirconium is one or more of zirconium nitrate, zirconium oxychloride, zirconium sulfate, etc.
[0012] In the catalyst preparation method, M and Q are one or more of vanadium, chromium, cobalt, molybdenum, niobium, tungsten, rhenium, etc. The soluble salts of vanadium include one or more of the following: vanadium oxysulfate, vanadium oxynitrate, and vanadium trichloride; the soluble salts of chromium include one or more of the following: chromium(III) nitrate, chromium(III) sulfate, and chromium trichloride; the soluble salts of cobalt include one or more of the following: cobalt(II) nitrate, cobalt(II) sulfate, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) bromide; the soluble salts of molybdenum include one or more of the following: molybdenum nitrate, molybdenum dioxide, sodium molybdate, potassium molybdate, and ammonium molybdate; the soluble salts of niobium include one or more of the following: niobium tetrachloride, niobium pentachloride, niobium trichloride, and ammonium niobate oxalate; the soluble salts of tungsten include one or more of the following: tungsten dioxide, sodium tungstate, potassium tungstate, and ammonium tungstate; and the soluble salts of rhenium include one or more of the following: ammonium perrhenate and sodium perrhenate.
[0013] The catalyst preparation method includes one or more of the following: soluble salts containing divalent manganese, such as manganese(II) nitrate, manganese(II) sulfate, manganese(II) chloride, manganese(II) acetate, and manganese(II) bromide; soluble salts containing divalent iron, such as ferrous sulfate, ferrous nitrate, ferrous chloride, and ferrous acetate; and aqueous solutions of the acid, such as nitric acid, hydrochloric acid, sulfuric acid, glacial acetic acid, and phosphoric acid.
[0014] The final catalyst C used in the fixed bed has a catalyst equivalent diameter of 100-2000 μm, preferably 200-1500 μm.
[0015] A method for the one-step preparation of methacrylonitrile from n-propanal is as follows: After filling the fixed bed with the catalyst, the entire fixed bed is first filled with nitrogen gas; then, n-propanal and water are heated to 140℃-200℃ for vaporization, and pressurized to 0.2MPa-0.6MPa, preferably 150℃-180℃, 0.3MPa-0.5MPa; carbon dioxide and ammonia are pressurized to the same pressure and then heated to the same temperature; after thoroughly mixing n-propanal vapor, water vapor, carbon dioxide, and ammonia, the mixture is introduced into the fixed bed, with a system pressure of 0.2MPa-0.6MPa, a reaction temperature of 150℃-300℃, a contact time of 0.1s-30s, preferably 0.3MPa-0.5MPa, 180℃-250℃, and 1s-20s. The molar ratio of n-propanal vapor, water vapor, carbon dioxide, and ammonia is 1:1:1:1.7-5, preferably 1:1:1:2-3.
[0016] Compared to other methods, this method can produce methacrylonitrile from propionaldehyde in one step while consuming CO2, and has great industrial application value and prospects.
[0017] Advantages of this invention:
[0018] The multiphase metal catalyst used in this invention has a simple metal composition, good fluidization properties, strong water resistance, wear resistance, and stable operation over a long period (the catalyst activity remains essentially unchanged after 200 hours of continuous operation). Simultaneously, the raw material cost is low, the reaction is a one-step process, with high selectivity and yield, and it is green and economical, consuming only carbon dioxide, thus possessing significant industrial application value and prospects. Detailed Implementation
[0019] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention includes, but is not limited to, the following embodiments. Any modifications to the details and form of the technical solution of the present invention without departing from the meaning and scope of this application shall fall within the scope of protection of the present invention.
[0020] Example 1
[0021] The catalyst was prepared as follows:
[0022] Step 1: First, add 40g of magnesium nitrate hexahydrate to 80mL of 10mol / L phosphoric acid aqueous solution and mix. Then, reflux at 100℃ for 24h. After cooling to room temperature and filtering, wash with 0.1mol / L phosphoric acid until no nitrate ions are present. Then wash with deionized water until neutral and dry at 100℃ for 24h to obtain solid Al.
[0023] Step 2: Dissolve 35.69g of cobalt(II) chloride hexahydrate in 200ml of deionized water, 145.17g of sodium molybdate dihydrate in 300ml of deionized water, 118.75g of manganese(II) chloride tetrahydrate in 200ml of deionized water, and 19.88g of ferrous chloride tetrahydrate in 300ml of deionized water to prepare aqueous solutions. Take out 105.14g of solid A1 and disperse it in 300ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A1 simultaneously and reflux at 80℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B1.
[0024] Step 3: Grind the solid B1 obtained in Step 2 for 15 min; then calcine it in a muffle furnace at 200℃ for 12 h; cool it to room temperature and add it to 100 ml of 1 mol / L hydrochloric acid solution; stir thoroughly for 30 min and filter; repeat the process of adding hydrochloric acid, stirring, and filtering twice more; finally, wash the obtained solid three times with deionized water, dry it at 120℃ for 24 h, grind it to pass through a 20-mesh sieve (particle size range of approximately 0.5 mm-1.2 mm) to obtain the final catalyst C1, which is used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, cobalt, manganese, molybdenum, and magnesium in C1 were 2.20%, 3.49%, 13.01%, 22.73%, and 11.51%, respectively.
[0025] Comparative Example 1
[0026] The first two steps of catalyst preparation (process and conditions) are the same as in Example 1. The difference is that the third step of catalyst preparation, which involves "adding to a 1 mol / L hydrochloric acid solution; stirring thoroughly for 30 min and then filtering; repeating the stirring and filtering process twice more; finally washing the obtained solid three times with deionized water and drying at 120℃ for 24 h," is removed. This yields solid B1, which is then ground and calcined, and then directly ground to pass through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C. 1-1 According to atomic absorption spectroscopy, C 1-1The mass fractions of iron, cobalt, manganese, molybdenum, and magnesium were 2.19%, 3.51%, 13.03%, 22.70%, and 11.53%, respectively.
[0027] Comparative Example 2
[0028] The first step of catalyst preparation (process and conditions) is the same as in Example 1.
[0029] Step 2: Dissolve 35.690g of cobalt(II) chloride hexahydrate in 200ml of deionized water, 145.17g of sodium molybdate dihydrate in 300ml of deionized water, and 19.81g of ferrous chloride tetrahydrate in 300ml of deionized water to prepare aqueous solutions. Take 105.14g of solid A1 and disperse it in 300ml of deionized water with continuous stirring. Add the three solutions dropwise to the dispersion of A1 simultaneously and reflux at 80℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B. 1-2 .
[0030] The third step of catalyst preparation (process and conditions) is the same as in Example 1, yielding the final catalyst C. 1-2 According to atomic absorption spectroscopy, C 1-2 The mass fractions of iron, cobalt, molybdenum, and magnesium were 2.65%, 4.19%, 27.32%, and 13.84%, respectively.
[0031] Comparative Example 3
[0032] The first step of catalyst preparation (process and conditions) is the same as in Example 1.
[0033] Step 2: Dissolve 35.690g of cobalt(II) chloride hexahydrate in 200ml of deionized water, 145.17g of sodium molybdate dihydrate in 300ml of deionized water, and 118.75g of manganese(II) chloride tetrahydrate in 200ml of deionized water to prepare aqueous solutions. Take 105.14g of solid A1 and disperse it in 300ml of deionized water with continuous stirring. Add the three solutions dropwise to the dispersion of A1 simultaneously and reflux at 80℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B. 1-3 .
[0034] The third step of catalyst preparation (process and conditions) is the same as in Example 1, yielding the final catalyst C. 1-3 According to atomic absorption spectroscopy, C 1-3 The mass fractions of cobalt, manganese, molybdenum, and magnesium were 3.60%, 13.44%, 23.47%, and 11.89%, respectively.
[0035] Example 2
[0036] The catalyst was prepared as follows:
[0037] Step 1: First, mix 460g of aluminum nitrate nonahydrate with 100ml of 12mol / L phosphoric acid aqueous solution, reflux at 90℃ for 28h, then cool to room temperature and filter. Wash with 0.2mol / L phosphoric acid until no nitrate ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A2.
[0038] Step 2: Dissolve 43.66g of cobalt(II) nitrate hexahydrate in 200ml of deionized water, 191.60g of molybdenum(II) nitrate pentahydrate in 300ml of deionized water, 150.61g of manganese(II) nitrate tetrahydrate in 200ml of deionized water, and 17.99g of ferrous nitrate in 300ml of deionized water to prepare aqueous solutions. Take out 146.34g of solid A2 and disperse it in 300ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A2 and reflux at 90℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B2.
[0039] Step 3: Grind the solid B2 obtained in Step 2 for 15 min; then calcine it in a muffle furnace at 180℃ for 15 h; cool it to room temperature and add 1 mol / L nitric acid solution; stir thoroughly for 30 min and filter; repeat the stirring and filtration process twice more; finally, wash the obtained solid three times with deionized water, dry it at 100℃ for 28 h, grind it to pass through a 20-mesh sieve (particle size range of approximately 0.5 mm-1.2 mm) to obtain the final catalyst C2, which is used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, cobalt, manganese, molybdenum, and aluminum in C2 were 1.90%, 3.00%, 11.19%, 19.55%, and 11.00%, respectively.
[0040] Example 3
[0041] The catalyst was prepared as follows:
[0042] Step 1: First, mix 230g of aluminum chloride hexahydrate and 750ml of 12mol / L phosphoric acid aqueous solution, reflux at 80℃ for 18h, then cool to room temperature and filter, wash with 0.2mol / L phosphoric acid until no chloride ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A3.
[0043] Step 2: Dissolve 59.48g of cobalt(II) chloride hexahydrate in 200ml of deionized water, 106.58g of chromium(II) chloride hexahydrate in 300ml of deionized water, 118.75g of manganese(II) chloride tetrahydrate in 200ml of deionized water, and 19.88g of ferrous(II) chloride tetrahydrate in 300ml of deionized water to prepare aqueous solutions. Take out 109.76g of solid A3 and disperse it in 250ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A3 and reflux at 80℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B3.
[0044] Step 3: The solid B3 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 220℃ for 12 h; after cooling to room temperature, a 1 mol / L hydrochloric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 18 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C3, which was used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, cobalt, manganese, chromium, and aluminum in C3 were 2.67%, 7.03%, 15.73%, 9.93%, and 11.60%, respectively.
[0045] Example 4
[0046] The catalyst was prepared as follows:
[0047] Step 1: First, mix 700g of aluminum sulfate octadechydrate and 1000ml of 10mol / L phosphoric acid aqueous solution, and reflux at 120℃ for 24h. Then cool to room temperature and filter, and wash with 0.2mol / L phosphoric acid until no sulfate ions are present. Then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A4.
[0048] Step 2: Dissolve 42.17g of cobalt(II) sulfate heptahydrate in 200ml of deionized water, 97.54g of sodium metavanadate in 500ml of deionized water, 135.21g of manganese(II) sulfate monohydrate in 200ml of deionized water, and 27.80g of ferrous sulfate heptahydrate in 300ml of deionized water to prepare aqueous solutions. Take out 121.953g of solid A4 and disperse it in 200ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A4 and reflux at 100℃ for 5 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B4.
[0049] Step 3: The solid B4 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 240℃ for 10 h; after cooling to room temperature, a 0.5 mol / L sulfuric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C4, which was used in a fixed bed reactor. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, cobalt, manganese, vanadium, and aluminum in C4 were 2.06%, 3.27%, 16.24%, 15.05%, and 9.97%, respectively.
[0050] Example 5
[0051] The catalyst was prepared as follows:
[0052] Step 1: First, mix 200g of titanium oxysulfate and 1600ml of 10mol / L phosphoric acid aqueous solution, and reflux at 120℃ for 24h. Then cool to room temperature and filter, and wash with 0.2mol / L phosphoric acid until no sulfate ions are present. Then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A5.
[0053] Step 2: Dissolve 12.19g of sodium metavanadate in 200ml of deionized water, 145.17g of sodium molybdate in 300ml of deionized water, 169.01g of manganese(II) sulfate monohydrate in 200ml of deionized water, and 27.81g of ferrous sulfate in 300ml of deionized water to prepare aqueous solutions. Take out 209.40g of solid A5 and disperse it in 300ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A5 and reflux at 100℃ for 4.5 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B5.
[0054] Step 3: Grind the solid B5 obtained in Step 2 for 15 min; then calcine it in a muffle furnace at 250℃ for 15 h; cool it to room temperature and add 0.5 mol / L sulfuric acid solution; stir thoroughly for 30 min and filter; repeat the stirring and filtration process twice more; finally, wash the obtained solid three times with deionized water, dry it at 120℃ for 24 h, grind it to pass through a 20-mesh sieve (particle size range of approximately 0.5 mm-1.2 mm) to obtain the final catalyst C5, which is used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, titanium, manganese, vanadium, and molybdenum in C5 were 1.53%, 15.76%, 15.07%, 1.40%, and 15.79%, respectively.
[0055] Example 6
[0056] The catalyst was prepared as follows:
[0057] Step 1: First, mix 250g of titanium oxychloride and 2000ml of 12mol / L phosphoric acid aqueous solution, reflux at 80℃ for 18h, then cool to room temperature and filter, wash with 0.2mol / L phosphoric acid until no chloride ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A6.
[0058] Step 2: Dissolve 39.77g of molybdenum dichloride in 200ml of deionized water, 235.06g of sodium tungstate in 300ml of deionized water, 197.91g of manganese chloride (II) tetrahydrate in 200ml of deionized water, and 19.88g of ferrous chloride in 300ml of deionized water to prepare aqueous solutions. Take out 314.09g of solid A6 and disperse it in 300ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A6 and reflux at 80℃ for 3.5 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B6.
[0059] Step 3: The solid B6 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 250℃ for 15 h; after cooling to room temperature, a 1 mol / L hydrochloric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range of approximately 0.5 mm-1.2 mm) to obtain the final catalyst C6, which was used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, tungsten, manganese, titanium, and molybdenum in C6 were 0.92%, 24.25%, 9.058%, 14.21%, and 3.16%, respectively.
[0060] Example 7
[0061] The catalyst was prepared as follows:
[0062] Step 1: First, mix 360g of titanium nitrate and 1600ml of 10mol / L phosphoric acid aqueous solution, reflux at 90℃ for 20h, then cool to room temperature and filter, wash with 0.2mol / L phosphoric acid until no nitrate ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A7.
[0063] Step 2: Dissolve 44.34g of molybdenum nitrate in 200ml of deionized water, 119.98g of niobium ammonium oxalate in 300ml of deionized water, 251.01g of manganese(II) nitrate in 200ml of deionized water, and 17.99g of ferrous nitrate in 300ml of deionized water to prepare aqueous solutions. Take 209.40g of solid A7 and disperse it in 300ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A7 and reflux at 120℃ for 3 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B7.
[0064] Step 3: The solid B7 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 250℃ for 15 h; after cooling to room temperature, a 1 mol / L nitric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C7, which was used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, niobium, manganese, molybdenum, and titanium in C7 were 1.57%, 10.47%, 15.47%, 2.70%, and 16.18%, respectively.
[0065] Example 8
[0066] The catalyst was prepared as follows:
[0067] Step 1: First, mix 180g of zirconium nitrate pentahydrate with 1600ml of 10mol / L phosphoric acid aqueous solution, reflux at 120℃ for 18h, then cool to room temperature and filter. Wash with 0.2mol / L phosphoric acid until no nitrate ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A8.
[0068] Step 2: Dissolve 11.70g of ammonium metavanadate in 200ml of deionized water, 214.59g of ammonium perrhenate in 300ml of deionized water, 150.61g of manganese(II) nitrate in 200ml of deionized water, and 17.99g of ferrous nitrate in 300ml of deionized water to prepare aqueous solutions. Take 261.42g of solid A8 and disperse it in 250ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A8 and reflux at 100℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until it is colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B8.
[0069] Step 3: The solid B8 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 200℃ for 24 h; after cooling to room temperature, a 1 mol / L nitric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C8, which was used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, rhenium, manganese, vanadium, and zirconium in C8 were 1.08%, 28.93%, 6.40%, 0.99%, and 21.26%, respectively.
[0070] Example 9
[0071] The catalyst was prepared as follows:
[0072] Step 1: First, mix 60g of zirconium oxychloride octahydrate with 200ml of 12mol / L phosphoric acid aqueous solution, reflux at 90℃ for 18h, then cool to room temperature and filter. Wash with 0.2mol / L phosphoric acid until no chloride ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A9.
[0073] Step 2: Dissolve 3.569g of cobalt(II) chloride hexahydrate in 20ml of deionized water, 16.39g of sodium perrhenate in 30ml of deionized water, 15.833g of manganese(II) chloride tetrahydrate in 20ml of deionized water, and 1.988g of ferrous chloride tetrahydrate in 30ml of deionized water to prepare aqueous solutions. Take out 39.213g of solid A9 and disperse it in 30ml of deionized water and stir continuously. Add the four solutions dropwise to the dispersion of A9 and reflux at 100℃ for 4 days. Filter the mixture while hot and wash the solid with deionized water until colorless. Dry it at 120℃ for 24 hours. Then cool it to room temperature to obtain solid B9.
[0074] Step 3: The solid B9 obtained in Step 2 was ground for 15 min; then calcined in a muffle furnace at 210℃ for 22 h; after cooling to room temperature, a 1 mol / L hydrochloric acid solution was added; the mixture was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C9, which was used in a fixed bed. Atomic absorption spectroscopy analysis showed that the mass fractions of iron, cobalt, manganese, zirconium, and rhenium in C9 were 0.88%, 1.39%, 9.52%, 25.87%, and 17.60%, respectively.
[0075] Example 10
[0076] The catalyst was prepared as follows:
[0077] Step 1: First, mix 65g of zirconium sulfate and 200ml of 12mol / L phosphoric acid aqueous solution, and reflux at 100℃ for 24h. Then cool to room temperature and filter, wash with 0.2mol / L phosphoric acid until no sulfate ions are present, then wash with deionized water until neutral, and dry at 120℃ for 24h to obtain solid A. 10 .
[0078] Step 2: Dissolve 3.920g ammonium molybdate in 20ml of deionized water, 21.459g ammonium perrhenate in 30ml of deionized water, 13.527g manganese sulfate monohydrate (II) in 20ml of deionized water, and 2.780g ferrous sulfate heptahydrate in 30ml of deionized water to prepare aqueous solutions; take out solid A. 10 39.213g was dispersed in 30ml of deionized water and stirred continuously. The four solutions were then added dropwise to solution A. 10 The mixture was refluxed at 95°C for 4 days in a dispersion; the mixture was filtered while hot, and the solid was washed with deionized water until colorless and then dried at 120°C for 24 hours; then cooled to room temperature to obtain solid B. 10 .
[0079] Step 3: Take the solid B obtained in step 2... 10 The sample was ground for 15 min; then calcined in a muffle furnace at 200℃ for 24 h; subsequently cooled to room temperature and a 0.5 mol / L sulfuric acid solution was added; the sample was stirred thoroughly for 30 min and then filtered; this stirring and filtration process was repeated twice; finally, the obtained solid was washed three times with deionized water, dried at 120℃ for 24 h, and ground until it passed through a 20-mesh sieve (particle size range approximately 0.5 mm-1.2 mm) to obtain the final catalyst C. 10 It is used in fixed beds. Atomic absorption spectroscopy analysis showed that C... 10 The mass fractions of iron, molybdenum, manganese, zirconium, and rhenium were 0.82%, 2.83%, 6.48%, 24.20%, and 21.95%, respectively.
[0080] Example 11
[0081] After the catalysts prepared in Comparative Examples 1-3 and Examples 1-10 were packed into a fixed bed, the entire fixed bed was first filled with nitrogen. Then, propanal and water were heated to 150°C and vaporized, pressurized to 0.3 MPa, and the flow rates of propanal and water vapor were controlled at 0.2 ± 0.05 ml / min and 0.2 ± 0.05 ml / min, respectively. Carbon dioxide and ammonia were pressurized to the same pressure of 0.3 MPa and then heated to the same temperature of 150°C, with the flow rates controlled at 0.2 ± 0.05 ml / min and 0.4 ± 0.1 ml / min, respectively. After thoroughly mixing propanal vapor, water vapor, carbon dioxide, and ammonia, the mixture was introduced into the fixed bed. The system pressure was 0.3 MPa, the reaction temperature was 200°C, and the contact time was 1 s. The molar ratio of propanal vapor, water vapor, carbon dioxide, and ammonia was 1:1:1:2. The gas obtained after passing through the fixed bed was dried and collected online by gas chromatography to determine the yield and conversion of methacrylonitrile.
[0082]
[0083] Example 12
[0084] After the catalysts prepared in Comparative Examples 1-3 and Examples 1-10 were packed into a fixed bed, the entire fixed bed was first filled with nitrogen. Then, propanal and water were heated to 180°C and vaporized, pressurized to 0.5 MPa, and the flow rates of propanal and water vapor were controlled at 0.5 ± 0.05 ml / min and 0.5 ± 0.05 ml / min, respectively. Carbon dioxide and ammonia were pressurized to the same pressure of 0.5 MPa and then heated to the same temperature of 180°C, with the flow rates controlled at 0.5 ± 0.05 ml / min and 1.25 ± 0.1 ml / min, respectively. After thoroughly mixing propanal vapor, water vapor, carbon dioxide, and ammonia, the mixture was introduced into the fixed bed. The system pressure was 0.5 MPa, the reaction temperature was 200°C, and the contact time was 0.5 s. The molar ratio of propanal vapor, water vapor, carbon dioxide, and ammonia was 1:1:1:2.5. The gas obtained after passing through the fixed bed was dried and collected online by gas chromatography to determine the yield and conversion of methacrylonitrile.
[0085]
[0086]
[0087] Example 13
[0088] After the catalyst prepared in Example 1 was packed into a fixed bed, it was continuously run for 200 hours according to the steps and conditions of Example 12, and the yield and conversion rate were determined by online gas chromatography at regular intervals.
[0089]
[0090] As can be seen from the above examples, the catalyst metal used in this invention has strong water resistance, wear resistance, and stable operation over a long period of time (Example 13: continuous operation for 200 hours, the catalyst activity remained basically unchanged), and has great industrial application value. At the same time, the reaction uses carbon dioxide as a raw material, which has broad application prospects.
[0091] This invention uses relatively inexpensive substances such as propionaldehyde and carbon dioxide as raw materials. Its yield and selectivity can be maintained at a high level for a long time. The route is simple and the reaction is relatively mild, which has great industrial application value and broad application prospects.
Claims
1. A catalyst for the one-step preparation of methacrylonitrile from n-propionaldehyde, having a composition of FeM x Q y Mn z X a P m O n M refers to one or more of vanadium, chromium, cobalt, molybdenum, niobium, tungsten, etc., and X (uppercase X, X a In this context, X) refers to one or more of magnesium, aluminum, titanium, zirconium, etc.; Q refers to one or more of vanadium, chromium, cobalt, molybdenum, niobium, tungsten, etc. In the catalyst composition, x (lowercase x, M) x In this context, x) takes values of 0.25-2, preferably 0.5-1.5; y takes values of 1-8, preferably 1.5-6; z takes values of 0.25-15, preferably 0.5-10; a takes values of 6-27, preferably 9-24; m takes values of 4-27, preferably 6-25; and n takes values that satisfy the oxygen atom ratio required for the oxidation state of the preceding element. These values represent the number of atoms of the corresponding element in the oxide, with Fe being 1.
2. A method for preparing the catalyst according to claim 1, characterized in that, The catalyst preparation method consists of the following three steps: The first step is: First, change X (uppercase X, X...) a The precursor of X in the mixture is mixed with 5 mol / L-15 mol / L (preferably 10 mol / L-12 mol / L) of phosphoric acid and refluxed at 80℃-120℃ for 8h-36h. After cooling to room temperature and filtering, the mixture is washed with 0.01 mol / L-1 mol / L of phosphoric acid, then washed with water until neutral, and dried at 80℃-150℃ for 8h-48h, preferably 100℃-120℃ for 12h-36h, to obtain solid A. The second step is as follows: Soluble salts of M and Q, soluble salts containing divalent manganese, and soluble salts containing divalent iron are prepared into aqueous solutions, wherein the molar ratio of M, Q, Mn, and Fe is x:y:z:1, yielding a four-element solution; solid A is dispersed in water and stirred continuously; the four-element solution is added dropwise to the dispersion of A, and refluxed at 80℃-120℃ for 2-5 days; the mixture is filtered while hot, and the solid is washed with water until colorless, then dried at 80℃-150℃ for 8-48 hours (preferably 100℃-120℃, 12-36 hours); then cooled to room temperature to obtain solid B; The third step is to grind the solid B obtained in the second step for 10-60 minutes (preferably 15-30 minutes); then place it in a muffle furnace for calcination at a temperature of 150℃-350℃ (preferably 200℃-300℃) for 2-24 hours (preferably 4-18 hours); and then cool it to room temperature. Add an aqueous solution of acid to a concentration of 0.05 mol / L to 5 mol / L (preferably 0.1 mol / L to 3 mol / L); stir thoroughly for 15 min to 120 min (preferably 30 min to 90 min) and then filter; repeat the process of adding acid, stirring, and filtering 1 to 3 times. Finally, the obtained solid is washed with water and dried at 80℃-150℃ for 8h-48h (preferably 100℃-120℃, 12h-36h), and then ground or ball-milled to obtain the final catalyst C.
3. The preparation method according to claim 2, characterized in that: In the second step, the concentration of Fe in the reaction solution is 0.01 mol / L to 1 mol / L, preferably 0.1 mol / L to 0.8 mol / L.
4. The preparation method according to claim 2, characterized in that: In the catalyst preparation method, X is one or more of magnesium, aluminum, titanium, zirconium, etc.; wherein the precursor of magnesium is one or more of magnesium chloride, magnesium nitrate, magnesium sulfate, etc.; the precursor of aluminum is one or more of aluminum chloride, aluminum sulfate, aluminum nitrate, etc.; the precursor of titanium is one or more of titanium tetrachloride, titanium oxysulfate, titanium oxychloride, titanium nitrate, etc.; and the precursor of zirconium is one or more of zirconium nitrate, zirconium oxychloride, zirconium sulfate, etc. The molar ratio of the precursor of X to phosphoric acid is 0.2-2, preferably 0.4-4.
5. The preparation method according to claim 2, characterized in that: In the catalyst preparation method, M refers to one or more of vanadium, chromium, cobalt, molybdenum, niobium, tungsten, etc., and Q refers to one or more of vanadium, chromium, cobalt, molybdenum, niobium, tungsten, etc. The soluble salts of vanadium include one or more of the following: vanadium oxysulfate, vanadium oxynitrate, and vanadium trichloride; chromium includes one or more of the following: chromium(III) nitrate, chromium(III) sulfate, and chromium trichloride; cobalt includes one or more of the following: cobalt(II) nitrate, cobalt(II) sulfate, cobalt(II) chloride, cobalt(II) acetate, and cobalt(II) bromide; molybdenum includes one or more of the following: molybdenum nitrate, molybdenum dioxide, sodium molybdate, potassium molybdate, and ammonium molybdate; niobium includes one or more of the following: niobium tetrachloride, niobium pentachloride, niobium trichloride, and niobium oxalate; tungsten includes one or more of the following: tungsten dioxide, sodium tungstate, potassium tungstate, and ammonium tungstate; and rhenium includes one or more of the following: ammonium perrhenate and sodium perrhenate.
6. The preparation method according to claim 2, characterized in that: The catalyst preparation method includes one or more of the following: divalent manganese soluble salts: manganese nitrate (II), manganese sulfate (II), manganese chloride (II), manganese acetate (II), manganese bromide (II); divalent iron soluble salts: ferrous sulfate, ferrous nitrate, ferrous chloride, ferrous acetate; and aqueous solutions of the following: nitric acid, hydrochloric acid, sulfuric acid, glacial acetic acid, phosphoric acid.
7. The preparation method according to claim 2, characterized in that: The catalyst is used in a fixed bed, and the catalyst equivalent diameter is 100-2000 μm, preferably 200-1500 μm.
8. The application of the catalyst according to claim 1 in the one-step catalytic preparation of methacrylonitrile from n-propanal, characterized in that, The process is as follows: After the catalyst is filled into the fixed bed, the entire fixed bed is first filled with nitrogen gas; then, propanal and water are heated to 140℃-200℃ to vaporize, and pressurized to 0.2MPa-0.6MPa (preferably 150℃-180℃, 0.3MPa-0.5MPa); carbon dioxide and ammonia are pressurized to the same pressure as propanal and water, and then heated to the same temperature as propanal and water; after thoroughly mixing propanal vapor, water vapor, carbon dioxide and ammonia, they are introduced into the fixed bed, with a system pressure of 0.2MPa-0.6MPa, a reaction temperature of 150℃-300℃, and a contact time with the catalyst of 0.1s-30s (preferably 0.3MPa-0.5MPa, 180℃-250℃, 1s-20s).
9. The application according to claim 8, characterized in that: The molar ratio of propionaldehyde vapor, water vapor, carbon dioxide, and ammonia is 1:0.1-10:0.1-10:1.7-5, preferably 1:0.5-5:0.5-5:2-3.