Preparation method and application of catalyst for synthesizing cyclohexanone oxime through ammoxidation of cyclohexanone

Abstract

The invention discloses a preparation method and application of a catalyst for synthesizing cyclohexanone oxime through ammoxidation of cyclohexanone, and belongs to the technical field of molecular sieve synthesis and catalysis. The preparation method comprises the following steps: uniformly mixing a silicon source, a tetrapropylammonium hydroxide aqueous solution and deionized water to obtain estersil hydrolysate A; adding a titanium source into the low-carbon alcohol to obtain a titanium ester hydrolysate B, and then adding a crystallization auxiliary agent; uniformly mixing the obtained estersil hydrolysate A with the titanium ester hydrolysate B, heating to remove alcohol, and crystallizing for 24-96 hours at the temperature of 150-180 DEG C under self-generated pressure to obtain titanium silicalite molecular sieve mother liquor; the method comprises the following steps: adding a ferric salt aqueous solution and aluminum sol or silica sol or silicon-aluminum sol into a titanium silicalite molecular sieve mother solution, aging for 10-72 hours at 60-80 DEG C under a stirring condition, carrying out spray molding, drying the obtained titanium silicalite molecular sieve, and roasting for 8-24 hours at 500-650 DEG C to obtain the TS-1 molecular sieve. The TS-1 molecular sieve prepared by the method can be used for preparing cyclohexanone-oxime under relatively mild reaction conditions, and the conversion rate of raw materials and the selectivity of products are effectively improved.

Description

Technical Field

[0001] The invention belongs to the technical field of molecular sieve synthesis and catalysis, and relates to a preparation method and application of a catalyst for synthesizing cyclohexanone oxime through ammoxidation of cyclohexanone. Background Art

[0002] Cyclohexanone oxime is an extremely critical intermediate in the chemical industry, especially in the production of caprolactam. The traditional preparation method has problems such as harsh reaction conditions, low selectivity, and environmental pollution. Since the 1980s, the cyclohexanone ammoxidation process has been developed, using cyclohexanone, ammonia and hydrogen peroxide as raw materials and titanium silicon molecular sieve TS-1 as a catalyst to carry out ammoxidation reaction to prepare cyclohexanone oxime. Compared with the traditional process, the cyclohexanone ammoxidation process has obvious advantages, such as low reaction temperature and reduced energy consumption.

[0003] As a special titanium silicon molecular sieve, TS-1 catalyst has a relatively high production cost. Although the production environment of cyclohexanone ammoxidation to cyclohexanone oxime is relatively friendly, the high production cost and the relatively low reaction activity and cyclohexanone oxime selectivity of existing catalysts limit its large-scale production and application. TS-1 has significant activity in catalyzing cyclohexanone ammoxidation to cyclohexanone oxime due to the presence of a unique four-coordinated Ti center. Therefore, it is of utmost importance to fully consider the preparation of skeleton titanium in the synthesis process. Research and development of catalysts with high catalytic activity and cyclohexanone oxime selectivity is an important topic that needs to be studied urgently. Summary of the invention

[0004] In view of this, the purpose of the present invention is to provide a preparation method and application of a catalyst for synthesizing cyclohexanone oxime by ammoxidation of cyclohexanone. In the process of preparing TS-1, the present invention strictly controls the hydrolysis conditions of titanium source and silicon source in the synthesis mother liquor. At the same time, by adding a crystallization aid, the soluble titanium species formed by hydrolysis is promoted to undergo a condensation reaction with the silicon species to form Si-O-Ti. The metal iron activity is introduced during the molding process of the titanium silicon molecular sieve catalyst to further improve the catalyst ammoxidation activity and cyclohexanone oxime selectivity. The catalyst prepared by the present invention has good sphericity, uniform particle size distribution, low wear rate, is suitable for producing cyclohexanone oxime using a slurry bed reactor, and has important industrial application value.

[0005] In order to achieve the above object, the present invention provides the following technical solutions:

[0006] The present invention provides a method for preparing a catalyst for synthesizing cyclohexanone oxime by ammoxidation of cyclohexanone, comprising the following steps:

[0007] (1) mixing a silicon source, a tetrapropylammonium hydroxide aqueous solution and deionized water uniformly and hydrolyzing them to obtain a silicon ester hydrolyzate A;

[0008] (2) adding a titanium source to a low-carbon alcohol, hydrolyzing to obtain a titanium ester hydrolyzate B, and then adding a crystallization aid;

[0009] (3) uniformly mixing the silicon ester hydrolyzate A obtained in step (1) and the titanium ester hydrolyzate B obtained in step (2), heating to remove alcohol, and crystallizing the obtained titanium silicalite sol at 150-180° C. under autogenous pressure for 24-96 hours to obtain a titanium silicalite mother liquor;

[0010] (4) Adding an aqueous solution of iron salt and aluminum sol or silica sol or silica-alumina sol to the titanium silicate mother liquor obtained in step (3), aging at 60-80° C. for 10-72 hours under stirring conditions, spray-forming, drying the spray-formed titanium silicate, and calcining at 500-650° C. for 8-24 hours to obtain a TS-1 molecular sieve.

[0011] Based on the above technical solution, further, the silicon source described in step (1) is one or a mixture of two or more of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate; and the concentration of the tetrapropylammonium hydroxide aqueous solution is 10 to 50 wt%.

[0012] Based on the above technical solution, further, the mass ratio of the silicon source, tetrapropylammonium hydroxide and water in step (1) is (2-10):1:(3-15).

[0013] Based on the above technical scheme, further, the titanium source in step (2) is one of tetraethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, titanium trichloride, and titanium tetrachloride, or a mixture of two or more thereof; the low-carbon alcohol is one of isopropanol, tert-butanol, n-butanol, and n-pentanol.

[0014] Based on the above technical solution, further, the mass ratio of the titanium source to the low-carbon alcohol in step (2) is 1:5-10.

[0015] Based on the above technical scheme, further, the crystallization aid described in step (2) is one or a mixture of two or more of EDTA, ethylenediamine, glycine, and lactic acid, and the molar ratio of the added amount to the titanium source is (0.05-0.2):1.

[0016] Based on the above technical solution, further, the heating alcohol removal in step (3) is to remove alcohol at 80-90° C. for 4 to 10 hours.

[0017] Based on the above technical scheme, further, the concentration of the aluminum sol or silica sol or silica-alumina sol described in step (4) is 10-50wt%, the concentration of iron ions in the iron salt aqueous solution is 5-20wt%, the mass ratio of the aluminum sol or silica sol or silica-alumina sol to the titanium silicate molecular sieve mother liquor is (0.1-0.8):1, and the mass ratio of the iron salt aqueous solution to the molecular sieve mother liquor is (0.01-0.1):1.

[0018] Another aspect of the present invention provides a catalyst prepared by the above preparation method.

[0019] The present invention also provides the use of the catalyst in catalyzing the reaction of synthesizing cyclohexanone oxime by ammoxidation of cyclohexanone.

[0020] Based on the above technical scheme, further, the catalytic cyclohexanone ammoxidation reaction to synthesize cyclohexanone oxime is specifically as follows: cyclohexanone, hydrogen peroxide, ammonia water and solvent are added into a reactor, a catalyst with a mass concentration of 0.5-5% is added, the reaction temperature is 35-80°C, the pressure is 0-0.8MPa, and after the reaction is completed, cyclohexanone oxime is separated.

[0021] Based on the above technical solution, further, the mass concentration of ammonia water is 20-30wt%, the concentration of hydrogen peroxide is 30-60wt%; the molar ratio of ammonia to cyclohexanone is (1.60-3.10):1, the molar ratio of hydrogen peroxide to cyclohexanone is (1.05-1.2):1, the solvent is tert-butanol, the mass ratio of the solvent to cyclohexanone is (5-30):1, the stirring speed is 150-600r / min, and the reaction time is 1-6 hours.

[0022] Compared with the reported method for preparing cyclohexanone oxime by molecular sieve catalysis, the present invention has the following beneficial effects:

[0023] The present invention is directed to the ammoxidation reaction of cyclohexanone. The tetracoordinated titanium in the titanium silicon molecular sieve framework is the active center of ammoxidation. During the synthesis process, framework titanium can only be formed when the hydrolysis rates of the silicon precursor and the titanium precursor are consistent. Otherwise, non-framework titanium or TiO 2 Therefore, in the process of preparing TS-1, the present invention strictly controls the hydrolysis conditions of the titanium source and the silicon source in the synthesis mother liquor, and adds a crystallization aid to promote the soluble titanium species formed by hydrolysis to react with the silicon species to form Si-O-Ti. At the same time, the present invention also introduces the activity of metallic iron in the process of forming the titanium silicon molecular sieve catalyst to further improve the catalyst ammoxidation activity and cyclohexanone oxime selectivity. The catalyst prepared by the present invention has good sphericity, uniform particle size distribution, low wear rate, is suitable for the production of cyclohexanone oxime using a slurry bed reactor, and has important industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1This is a scanning electron microscope image of the titanium silicon molecular sieve raw powder synthesized in Comparative Example 1.

[0025] Figure 2 This is a scanning electron microscope image of the titanium silicon molecular sieve raw powder synthesized in Example 1.

[0026] Figure 3 This is a scanning electron microscope image of the titanium silicon molecular sieve catalyst synthesized in Example 1. DETAILED DESCRIPTION

[0027] The present invention is specifically described below with reference to examples:

[0028] The calculation formulas for the conversion of cyclohexanone and the selectivity of cyclohexanone oxime are as follows:

[0029] Cyclohexanone conversion rate (%) = (C 0 -C 1 ) / C 0 ×100%;

[0030] Cyclohexanone oxime selectivity (%) = C 2 / (C 0 -C 1 )×100%;

[0031] C 0 , C 1 and C 2 They are the concentration of cyclohexanone before the reaction, the concentration of cyclohexanone after the reaction and the concentration of cyclohexanone oxime.

[0032] Comparative Example 1

[0033] This comparative example provides a method for preparing a conventional titanium silicon molecular sieve, comprising the following steps:

[0034] Take 20g of deionized water and add it to 22.5g of silica sol (30%wt), stir for 15min, then add 2.08g of tetrapropylammonium bromide to the sol, continue stirring for 30min to obtain a raw silicon solution; mix tetrabutyl titanate and acetylacetone in a mass ratio of 1:1, stir for 10min, and obtain a raw titanium solution; take 1.54ml of the obtained titanium solution and add it dropwise to the raw silicon solution for 6 hours, then stir for 30min to obtain a silicon-titanium solution, add 5.2ml of n-butylamine and supplement with 14.5g of deionized water, continue stirring for 60min to obtain a uniform titanium-silicon solution; then add the obtained solution to a 200ml stainless steel reactor, crystallize under autogenous pressure and 170°C to obtain a titanium-silicon molecular sieve.

[0035] Embodiment 1:

[0036] This embodiment provides a method for preparing TS-1 molecular sieve-1, comprising the following steps:

[0037] (1) 90 g of a 25 wt% tetrapropylammonium hydroxide aqueous solution and 75 ml of deionized water were added to 100 g of tetraethyl orthosilicate to hydrolyze the tetraethyl orthosilicate to obtain a silicone ester hydrolyzate A;

[0038] (2) 4.5 g of tetrabutyl titanate was added to 36 ml of isopropanol and hydrolyzed at room temperature to obtain titanium ester hydrolyzate B, and then 1.8 g of EDTA was added;

[0039] (3) The silicon ester hydrolyzate A and the titanium ester hydrolyzate B are mixed, and the reaction is continued at 85° C. to remove alcohol for 6 hours, and 240 g of the obtained clarified titanium silicalite is placed in a stainless steel sealed reactor with a polytetrafluoroethylene liner, and crystallized at 170° C. under autogenous pressure for 24 hours to obtain a titanium silicalite mother liquor;

[0040] (4) Take 200 g of the above-mentioned titanium silicalite mother liquor, add 30 g of 30% aluminum sol and 10 g of 10% ferric nitrate aqueous solution, age at 70°C for 24 hours under stirring conditions, use a small spray molding machine to spray mold, dry the spray-molded catalyst at 100°C for 12 hours, and calcine at 540°C for 12 hours to obtain spray-molded TS-1 molecular sieve-1.

[0041] Figure 1 This is a scanning electron microscope image of the titanium silicon molecular sieve raw powder synthesized in Comparative Example 1. Figure 2 This is a scanning electron microscope image of the titanium silicon molecular sieve raw powder synthesized in Example 1. Figure 3 This is a scanning electron microscope image of the titanium silicon molecular sieve catalyst synthesized in Example 1. By comparing the scanning electron microscope images of the catalysts prepared in Comparative Example 1 and Example 1, it can be found that the titanium silicon molecular sieve obtained by the method of Comparative Example 1 has a grain size of about 8μm, while the titanium silicon molecular sieve prepared by the synthesis method used in Example 1 is nanoscale, has a grain size of about 200nm, and is very uniform. The obtained titanium silicon molecular sieve catalyst has good sphericity and uniform particle size distribution.

[0042] Embodiment 2:

[0043] This embodiment provides a method for preparing TS-1 molecular sieve-2, comprising the following steps:

[0044] (1) adding 100 g of a 25 wt% tetrapropylammonium hydroxide aqueous solution and 100 ml of deionized water to 120 g of tetraethyl orthosilicate to hydrolyze the tetraethyl orthosilicate to obtain a silicone ester hydrolyzate A;

[0045] (2) 5 g of tetrabutyl titanate was added to 40 ml of isopropanol and hydrolyzed at room temperature to obtain titanium ester hydrolyzate B, and then 3.5 g of ethylenediamine was added;

[0046] (3) The silicon ester hydrolyzate A and the titanium ester hydrolyzate B are mixed, and the reaction is continued at 85° C. to remove alcohol for 6 hours, and 220 g of the obtained clarified titanium silicalite is placed in a stainless steel sealed reactor with a polytetrafluoroethylene liner, and crystallized at 170° C. under autogenous pressure for 72 hours to obtain a titanium silicalite mother liquor;

[0047] (4) Take 200 g of the above-mentioned titanium silicalite mother liquor, add 30 g of 30% aluminum sol and 10 g of 10% ferric nitrate aqueous solution, age at 70°C for 24 hours under stirring conditions, use a small spray molding machine to spray mold, dry the spray-molded catalyst at 100°C for 12 hours, and calcine at 540°C for 12 hours to obtain spray-molded TS-1 molecular sieve-2.

[0048] Embodiment 3:

[0049] This embodiment provides a method for preparing TS-1 molecular sieve-3, comprising the following steps:

[0050] (1) adding 60 g of a 25 wt% tetrapropylammonium hydroxide aqueous solution and 60 ml of deionized water to 75 g of tetraethyl orthosilicate to hydrolyze the tetraethyl orthosilicate to obtain a silicone ester hydrolyzate A;

[0051] (2) 3.2 g of tetrabutyl titanate was added to 17 ml of isopropanol and hydrolyzed at room temperature to obtain titanium ester hydrolyzate B, and then 4.2 g of glycine was added;

[0052] (3) The silicon ester hydrolyzate A and the titanium ester hydrolyzate B are mixed, and the reaction is continued at 85° C. to remove alcohol for 6 hours, and 210 g of the obtained clarified titanium silicalite is placed in a stainless steel sealed reactor with a polytetrafluoroethylene liner, and crystallized at 170° C. under autogenous pressure for 72 hours to obtain a titanium silicalite mother liquor;

[0053] (4) Take 200 g of the above-mentioned titanium silicalite mother liquor, add 30 g of 30% silica sol and 10 g of 10% ferric nitrate aqueous solution, age at 70°C for 24 hours under stirring conditions, use a small spray molding machine to spray mold, dry the spray-molded catalyst at 100°C for 12 hours, and calcine at 540°C for 12 hours to obtain spray-molded TS-1 molecular sieve-3.

[0054] Embodiment 4:

[0055] This embodiment provides a method for preparing TS-1 molecular sieve-4, comprising the following steps:

[0056] (1) 150 g of a 25 wt% tetrapropylammonium hydroxide aqueous solution and 150 ml of deionized water were added to 200 g of tetraethyl orthosilicate to hydrolyze the tetraethyl orthosilicate to obtain a silicone ester hydrolyzate A;

[0057] (2) 8 g of tetrabutyl titanate was added to 60 ml of isopropanol and hydrolyzed at room temperature to obtain titanium ester hydrolyzate B, and then 13 g of lactic acid was added;

[0058] (3) The silicon ester hydrolyzate A and the titanium ester hydrolyzate B are mixed, and the reaction is continued at 85° C. to remove alcohol for 6 hours, and 500 g of the obtained clarified titanium silicalite is placed in a stainless steel sealed reactor with a polytetrafluoroethylene liner, and crystallized at 170° C. under autogenous pressure for 72 hours to obtain a titanium silicalite mother liquor;

[0059] (4) Take 200 g of the above-mentioned titanium silicalite mother liquor, add 30 g of 30% aluminum sol and 10 g of 10% ferric nitrate aqueous solution, age at 70°C for 24 hours under stirring conditions, use a small spray molding machine to spray mold, dry the spray-molded catalyst at 100°C for 12 hours, and calcine at 540°C for 12 hours to obtain spray-molded TS-1 molecular sieve-4.

[0060] Embodiment 5:

[0061] This embodiment provides a method for preparing TS-1 molecular sieve-5, comprising the following steps:

[0062] (1) 90 g of a 25 wt% tetrapropylammonium hydroxide aqueous solution and 90 ml of deionized water were added to 100 g of tetraethyl orthosilicate to hydrolyze the tetraethyl orthosilicate to obtain a silicone ester hydrolyzate A;

[0063] (2) 5 g of tetrabutyl titanate was added to 40 ml of isopropanol and hydrolyzed at room temperature to obtain titanium ester hydrolyzate B, and then 4.3 g of lactic acid was added;

[0064] (3) The silicon ester hydrolyzate A and the titanium ester hydrolyzate B are mixed, and the reaction is continued at 85° C. to remove alcohol for 6 hours, and 250 g of the obtained clarified titanium silicalite is placed in a stainless steel sealed reactor with a polytetrafluoroethylene liner, and crystallized at 175° C. under autogenous pressure for 72 hours to obtain a titanium silicalite mother liquor;

[0065] (4) Take 200 g of the above-mentioned titanium silicalite mother liquor, add 30 g of 30% aluminum sol and 10 g of 20% ferric nitrate aqueous solution, age at 80°C for 24 hours under stirring conditions, use a small spray molding machine to spray mold, dry the spray-molded catalyst at 100°C for 12 hours, and calcine at 600°C for 12 hours to obtain spray-molded TS-1 molecular sieve-5.

[0066] Embodiment 6:

[0067] The catalyst prepared in Comparative Example 1 or Examples 1-5 catalyzes the ammoxidation of cyclohexanone to synthesize cyclohexanone oxime. The specific process is as follows: 3 g of the catalyst prepared in Comparative Example 1 or Examples 1-5 is weighed and placed in a three-necked flask, and 4.7 g of cyclohexanone, 13.5 g of 25% ammonia water, 3.9 g of 50% hydrogen peroxide and 66.3 g of tert-butanol are added in sequence, 0.5 MPa, the reaction temperature is 80° C., the rotation speed is 400 r / min, and the contact is fully stirred for 1 hour. The conversion rate of cyclohexanone and the selectivity of cyclohexanone oxime are analyzed by gas chromatography. The results are shown in Table 1.

[0068] Table 1 Conditions and results of synthesizing cyclohexanone oxime from cyclohexanone catalyzed by the catalysts of Comparative Example 1 or Examples 1-5

[0069]

[0070] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited to the specific details of the above embodiments. Within the technical concept of the present invention, the technical scheme of the present invention can be subjected to a variety of simple variations and combinations, all of which fall within the protection scope of the present invention.

Claims

1. A method for preparing a catalyst for synthesizing cyclohexanone oxime by ammoxidation of cyclohexanone, characterized in that: The steps include: (1) mixing a silicon source, a tetrapropylammonium hydroxide aqueous solution and deionized water uniformly and hydrolyzing them to obtain a silicon ester hydrolyzate A; (2) adding a titanium source to a low-carbon alcohol, hydrolyzing to obtain a titanium ester hydrolyzate B, and then adding a crystallization aid; (3) uniformly mixing the silicon ester hydrolyzate A obtained in step (1) and the titanium ester hydrolyzate B obtained in step (2), heating to remove alcohol, and crystallizing the obtained titanium silicalite sol at 150-180° C. under autogenous pressure for 24-96 hours to obtain a titanium silicalite mother liquor; (4) Adding an aqueous solution of iron salt and aluminum sol or silica sol or silica-alumina sol to the titanium silicate mother liquor obtained in step (3), aging at 60-80° C. for 10-72 hours under stirring conditions, spray-forming, drying the spray-formed titanium silicate, and calcining at 500-650° C. for 8-24 hours to obtain a TS-1 molecular sieve.

2. The preparation method according to claim 1, characterized in that: The silicon source described in step (1) is one or a mixture of two or more of tetraethyl orthosilicate, tetramethyl orthosilicate, tetrapropyl orthosilicate and tetrabutyl orthosilicate; the concentration of the tetrapropylammonium hydroxide aqueous solution is 10-50wt%; the mass ratio of the silicon source, tetrapropylammonium hydroxide and water is (2-10):1:(3-15).

3. The preparation method according to claim 1, characterized in that: The titanium source in step (2) is one of tetraethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, titanium trichloride, titanium tetrachloride, or a mixture of two or more thereof; the low-carbon alcohol is one of isopropanol, tert-butanol, n-butanol, and n-pentanol; and the mass ratio of the titanium source to the low-carbon alcohol is 1:5-10.

4. The preparation method according to claim 1, characterized in that: The crystallization aid described in step (2) is one or a mixture of two or more of EDTA, ethylenediamine, glycine, and lactic acid, and the molar ratio of the added amount to the titanium source is (0.05-0.2):

1.

5. The preparation method according to claim 1, characterized in that: The heating and alcohol removal in step (3) is to remove alcohol at 80-90° C. for 4 to 10 hours.

6. The preparation method according to claim 1, characterized in that: The concentration of the aluminum sol or silica sol or silica-alumina sol described in step (4) is 10-50wt%, the concentration of iron ions in the iron salt aqueous solution is 5-20wt%, the mass ratio of the aluminum sol or silica sol or silica-alumina sol to the titanium silicon molecular sieve mother liquor is (0.1-0.8):1, and the mass ratio of the iron salt aqueous solution to the molecular sieve mother liquor is (0.01-0.1):

1.

7. A catalyst obtained by the preparation method according to any one of claims 1 to 6.

8. Use of the catalyst according to claim 7 in catalyzing the ammoxidation reaction of cyclohexanone to synthesize cyclohexanone oxime.

9. The use according to claim 8, characterized in that: The catalytic cyclohexanone ammoxidation reaction to synthesize cyclohexanone oxime is specifically as follows: cyclohexanone, hydrogen peroxide, ammonia water and solvent are added into a reaction kettle, a catalyst with a mass concentration of 0.5-5% is added, the reaction temperature is 35-80°C, the pressure is 0-0.8MPa, and after the reaction is completed, cyclohexanone oxime is separated.

10. The use according to claim 9, characterized in that: The mass concentration of ammonia water is 20-30wt%, the concentration of hydrogen peroxide is 30-60wt%; the molar ratio of ammonia to cyclohexanone is (1.60-3.10):1, the molar ratio of hydrogen peroxide to cyclohexanone is (1.05-1.2):1, the solvent is tert-butyl alcohol, the mass ratio of the solvent to cyclohexanone is (5-30):1, the stirring speed is 150-600r / min, and the reaction time is 1-6 hours.

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