A surface-modified silicate titanium silicon molecular sieve catalyst and preparation method thereof and its application in epoxidation preparation of epichlorohydrin

Abstract

The present invention provides a surface-modified silicate titanium silicon molecular sieve catalyst and a preparation method thereof and its application in the epoxidation preparation of epichlorohydrin. The preparation method of the catalyst comprises the following steps: 1) mixing an organic structure directing agent with water, stirring evenly, then adding tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS), performing a hydrolysis reaction under stirring to obtain a gel, then heating under high pressure to perform a crystallization reaction, separating a solid, washing with water, washing with alcohol, and calcining to obtain a titanium silicon molecular sieve raw powder; 2) mixing the titanium silicon molecular sieve raw powder with melamine, octyl, and aniline, reacting, then filtering, and drying to obtain a surface-modified silicate titanium silicon molecular sieve. The catalyst used in the present invention is combined with a structure directing agent, and the surface of the catalyst is treated, so that while increasing the active sites of the catalyst, the mass transfer effect between the oil and water phases can also be improved, thereby obtaining a higher hydrogen peroxide conversion rate.

Description

Technical Field

[0001] The present invention relates to a production method of epichlorohydrin. Specifically, it relates to a modified titanium silicalite molecular sieve catalyst, and a method for continuously reacting in a bubble column using titanium silicalite molecular sieve as a catalyst and hydrogen peroxide as an oxidant to directly epoxidize allyl chloride with the catalyst to produce epichlorohydrin, belonging to the technical field of organic chemical industry. Background Art

[0002] Epichlorohydrin (ECH) is an important bulk organic chemical raw material and fine chemical product, and is the third largest epoxide after ethylene oxide and propylene oxide in terms of output. It is widely used in the synthesis of epoxy resins, glycerol, chlorohydrin rubber, etc.

[0003] Currently, epichlorohydrin is produced from propylene. The main production method is the chlorohydrin method, which involves obtaining dichloropropanol from allyl chloride through hypochlorination and saponifying dichloropropanol to obtain epichlorohydrin. This method belongs to an indirect synthesis method of epichlorohydrin, and the synthesis route is long. This method has the characteristics of large-scale, continuous, and automated production, and the process is mature and the operation is stable. However, due to some of its own disadvantages such as high material consumption, serious equipment corrosion, many by-products, and a large amount of sewage generated during the production process, it causes serious environmental pollution. In order to overcome these defects, researchers have carried out research on the direct epoxidation of allyl chloride to prepare epoxychlorohydrin.

[0004] With the continuous development of epoxy resins and related products, the domestic demand for epichlorohydrin is increasing. In addition, the degree of attention to environmental protection is also getting higher and higher. The green preparation method of epichlorohydrin has attracted more and more attention. The method of using a titanium silicalite molecular sieve catalyst to catalyze the epoxidation of allyl chloride to produce epichlorohydrin, H 2 O 2 is a green oxidizing substance. The catalyst is a powder catalyst, which can be separated and recycled, and there is no other solvent during the reaction process, and the process environment is friendly and economically reasonable.

[0005] Reaction equation:

[0006]

[0007] In summary, the existing methods for continuously preparing epichlorohydrin have the following problems:

[0008] 1. To achieve continuous production of materials using a fixed bed or trickle bed reactor, it is necessary to make the reaction liquid phase materials homogeneous. Therefore, the solvent consumption is large and the separation energy consumption is high. Allyl chloride and epichlorohydrin are directly separated by atmospheric distillation with a large amount of methanol and water. Above 50 °C, it will lead to an increase in by-products 3-chloro-1-methoxy-2-propanol and 1,3-dichloropropanol, and the separation yield of epichlorohydrin is low.

[0009] 2. The reaction effect of the ordinary titanium silicate molecular sieve catalyst is poor under the phase separation condition, and it is difficult to ensure a low conversion rate of hydrogen peroxide.

[0010] 3. The number of active sites of the catalyst is small, and the catalyst cannot meet the activity requirements. SUMMARY OF THE INVENTION

[0011] In view of the above problems existing in the prior art, the present invention firstly provides a surface-modified silicate titanium silicate molecular sieve catalyst and a preparation method thereof.

[0012] Secondly, the present invention also provides a method for producing epichlorohydrin by epoxidation of allyl chloride using the above catalyst. This method has a stable reaction temperature, a simple process flow, and the catalyst has more Ti sites, and at the same time has a good oil-water mass transfer effect, which can strengthen the mass transfer between hydrogen peroxide and allyl chloride, resulting in a high yield of epichlorohydrin and a high utilization rate of hydrogen peroxide, overcoming the problems of long process flow, a large amount of three wastes, and high energy consumption in the existing epichlorohydrin production process.

[0013] To achieve the above object, the present invention adopts the following technical solutions:

[0014] The present invention provides a preparation method of a surface-modified silicate titanium silicate molecular sieve catalyst, and the steps include:

[0015] 1) Mix the organic structure-directing agent with water, stir evenly, then add tetrabutyl titanate (TBOT) and tetraethyl orthosilicate (TEOS), carry out a hydrolysis reaction under stirring to obtain a gel, then raise the temperature under high pressure for a crystallization reaction, separate out the solid, wash with water, wash with alcohol, and calcine to obtain the titanium silicate molecular sieve raw powder;

[0016] 2) React the titanium silicate molecular sieve raw powder with melamine, octyl (C8-10-alkyl glycidyl ether), and aniline, then filter and dry to obtain the surface-modified silicate titanium silicate molecular sieve.

[0017] In step 1) of the present invention, the organic structure-directing agent is selected from at least one of N,N,N,N',N',N'-hexaethyl-4,4'-bis(methyl)-1,1'-biphenyl ammonium hydroxide and N,N'-dicyclohexyl-N,N,N',N'-tetramethyl-1,4-dimethylphenyl ammonium hydroxide.

[0018] In step 1) of the present invention, the molar ratio of tetraethyl orthosilicate to tetrabutyl titanate, organic structure-directing agent, and water is 1.0:0.02 - 0.20:0.20 - 0.50:10 - 30, preferably 1:0.025 - 0.20:0.25 - 0.5:12 - 30.

[0019] In step 1) of the present invention, the stirring time is 30 - 60 min.

[0020] In step 1) of the present invention, for the hydrolysis reaction, the temperature is 30 - 90°C, preferably 35 - 75°C, and the time is 5 - 9 h, preferably 5 - 8 h.

[0021] In step 1) of the present invention, for the crystallization reaction, the pressure is 0.3 - 4 Mpa, preferably 0.5 - 2 Mpa, the temperature is 130 - 250°C, preferably 150 - 220°C, and the time is 5 - 9 h, preferably 5 - 8 h.

[0022] In step 1) of the present invention, for the calcination, the temperature is 400 - 700°C, preferably 450 - 650°C, and the time is 4 - 9 h, preferably 4 - 8 h.

[0023] In step 1) of the present invention, the separation of the solid, water washing, and alcohol washing are all conventional operations in the preparation process of titanium silicalite molecular sieve, and the present invention does not make specific limitations.

[0024] In step 2) of the present invention, the mass ratio of the titanium silicalite molecular sieve raw powder to melamine is 1:0.01 - 0.1, preferably 1:0.01 - 0.05.

[0025] In step 2) of the present invention, the molar ratio of melamine to octyl is 1:5 - 200, preferably 1:50 - 200.

[0026] In step 2) of the present invention, the concentration of the titanium silicalite molecular sieve raw powder in aniline is 0.1 - 1 g / ml, preferably 0.2 - 0.8 g / ml.

[0027] In step 2) of the present invention, for the reaction, the temperature is 80 - 150°C, preferably 90 - 140°C, and the time is 3 - 9 h, preferably 3 - 7 h.

[0028] In step 2) of the present invention, for the drying, the temperature is 30 - 90°C, preferably 30 - 80°C, and the time is 1 - 10 h, preferably 2 - 8 h.

[0029] The surface - modified silicate titanium silicalite molecular sieve catalyst prepared by the method of the present invention has a particle size of 100 - 500 μm, preferably 100 - 350 μm, and a bulk density of 0.5 g / mL - 1.5 g / mL, preferably 0.5 g / mL - 1.3 g / mL.

[0030] The present invention also simultaneously provides the application of the above - mentioned catalyst in the preparation of epichlorohydrin.

[0031] In some embodiments, the present invention provides a continuous method for producing epichlorohydrin by epoxidation of allyl chloride. The device used in this method includes a bubble - column reactor, an oil - water separator, and a condenser. The outlet of the bubble - column reactor is connected to the inlet of the oil - water separator. The specific steps include:

[0032] (1) Mix fresh allyl chloride and allyl chloride entraining the surface-modified silicate titanium silicalite molecular sieve catalyst, and then transport the mixture to the bottom of the bubble column reactor. At the same time, transport the aqueous hydrogen peroxide solution and the auxiliary agent NH 3 ·H 2 O to the bottom of the bubble column reactor, and continuously introduce nitrogen gas from the bottom of the bubble column reactor to maintain the internal pressure of the system at 0.1 - 4 Mpa, preferably 0.2 - 1 Mpa for the epoxidation reaction. The reaction temperature is 10 - 70 °C, preferably 20 - 50 °C, and the residence time is 0.5 - 6 h, preferably 0.5 - 3 h;

[0033] (2) The reaction materials in the bubble column reactor enter the oil-water separator through the top outlet. At the same time, the catalyst slowly falls back to the bottom of the bubble column reactor from the side line of the bubble column reactor by free sedimentation, so as to separate the catalyst from the liquid phase;

[0034] (3) The unreacted allyl chloride is cooled by a condenser at the top of the bubble column reactor and then returned to step (1) to be mixed with the raw materials;

[0035] (4) After the materials entering the oil-water separator are separated, the aqueous phase flows out from the upper end of the oil-water separator, and the oil phase containing the product epichlorohydrin flows out from the lower end of the oil-water separator.

[0036] In the present invention, the bubble column reactor contains sieve plates inside, and the number is 10 - 50, preferably 15 - 43; the inner diameter of the sieve plate is 50 - 300 mm, preferably 70 - 280 mm.

[0037] In the present invention, the catalyst content in the reaction liquid of the bubble column reactor is 1 - 20 wt%, preferably 5 - 18 wt%;

[0038] The molar ratio of hydrogen peroxide contained in the aqueous hydrogen peroxide solution added to the reactor to the molar ratio of allyl chloride is 1:4 - 10, preferably 1:4 - 8;

[0039] The mass concentration of the aqueous hydrogen peroxide solution is 27.5 - 60%, preferably 27.5 - 50%;

[0040] The concentration of the auxiliary agent NH 3 ·H 2 O in the system is 50 - 150 ppm.

[0041] In the method for producing epichlorohydrin by epoxidation of allyl chloride in the present invention, the conversion rate of hydrogen peroxide is as high as over 90%, the selectivity of epichlorohydrin is as high as over 96%, and the selectivity of the by-product 1,3-dichloropropanol is less than 0.05%.

[0042] Compared with the prior art, the beneficial effects of the technical solution of the present invention are as follows:

[0043] (1) The reactor has a large volume, can operate at high load, and does not require a solvent. It can achieve sufficient contact between two phases relying on sieve plates and gas, which is beneficial to the catalytic reaction. Compared with the reaction, the present invention reduces the energy consumption of mixing materials, the reaction is stable, and the equipment for separating the solvent is reduced, resulting in a significant reduction in cost.

[0044] (2) The catalyst can settle by its own gravity without using a filter for filtration, reducing the risk of possible blockage and lowering the investment cost.

[0045] (3) The modified titanium silicalite molecular sieve has a strong mass transfer effect between oil and water phases, and is modified using a structure-directing agent, enabling the catalyst to obtain more open molecular sieve structures. This structure can greatly improve the mass transfer efficiency and the accessibility of active sites. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 It is a schematic process flow diagram for the production of epichlorohydrin by epoxidation of allyl chloride according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] The following examples are used to further illustrate the specific implementation of the present method. However, the present invention is not limited to the listed examples, and should also include any other known changes within the scope of the rights required by the present invention.

[0048] In the examples and comparative examples of the present invention, the sources of the main raw materials are as follows. Unless otherwise specified, other raw materials and reagents are obtained through ordinary commercial channels:

[0049] N,N,N,N',N',N'-Hexaethyl-4,4'-bis(methyl)-1,1'-biphenylammonium hydroxide: Prepared according to the method disclosed in the reference Bai R, Navarro M T, Song Y, et al. Titanosilicate zeolite precursors for highly efficient oxidation reactions[J]. Chemical science, 2020(45):11. The specific steps are as follows: Dissolve 17.0 g (50 mmol) of 4,4'-bis(bromomethyl)biphenyl and 11.13 g (110 mmol) of triethylamine in 100 mL of ethanol, and reflux at 80 °C for 96 hours. Then remove the residual solvent in the flask by a rotary evaporator. Wash the product alternately with 100 mL of ethyl acetate and 100 mL of acetone, and dry the obtained white solid under vacuum to obtain the bromide salt form of the organic structure-directing agent. Dissolve 15 g of the product in 75 mL of water, add 70 g of anion exchange resin, stir overnight at room temperature, and separate the resin to obtain an aqueous solution of the hydroxide of the organic structure-directing agent. Titrate it with phenolphthalein and dilute hydrochloric acid to determine the content of the organic structure-directing agent in the aqueous solution;

[0050] N,N'-Dicyclohexyl-N,N,N',N'-tetramethyl-1,4-dimethylphenylammonium hydroxide: Prepared according to the method disclosed in the reference Bai R, Navarro M T, Song Y, et al. Titanosilicate zeolite precursors for highly efficient oxidation reactions[J]. Chemical science, 2020(45):11. The specific steps are as follows: Dissolve 27.21 g (100 mmol) of 1,4-bis(bromomethyl)benzene and 28.56 g (220 mmol) of N,N-dimethylcyclohexylamine in 200 mL of ethanol, and reflux at 80 °C for 96 hours. Remove the residual solvent in the flask by a rotary evaporator. Wash the product alternately with 200 mL of ethyl acetate and 200 mL of acetone, and then dry the obtained white solid under vacuum to obtain the bromide salt form of the organic structure-directing agent. Dissolve 26 g of the product in 100 mL of water, add 125 g of anion exchange resin, stir overnight at room temperature, and separate the resin to obtain an aqueous solution of the hydroxide of the organic structure-directing agent. Titrate it with phenolphthalein and dilute hydrochloric acid to determine the content of the organic structure-directing agent in the aqueous solution;

[0051] Tetrabutyl titanate: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0052] Tetraethyl orthosilicate: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0053] Melamine: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0054] Octyl: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0055] Aniline: Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0056] Allyl chloride: purity 99.5 wt%, Shanghai Aladdin Biochemical Technology Co., Ltd.

[0057] The main analysis method in the examples of the present invention: Agilent gas chromatography.

[0058] Example 1

[0059] Prepare a surface-modified silicate titanium silicalite molecular sieve catalyst:

[0060] 1) Mix 2469 g (3 mol) of the organic structure-directing agent N,N,N,N',N',N'-hexaethyl-4,4'-bis(methyl)-1,1'-biphenyl ammonium hydroxide with 2700 g (150 mol) of ultrapure water and stir at room temperature for 15 minutes. Then add 126.12 g (1 mol) of tetrabutyl titanate (TBOT) and 2642.6 g (10 mol) of tetraethyl orthosilicate (TEOS) to the system, and stir and hydrolyze at 50 °C for 6 hours to obtain a gel. Introduce the gel into a stainless-steel autoclave with a polytetrafluoroethylene liner, and carry out a static crystallization reaction at a pressure of 0.75 Mpa and 180 °C for 8 hours. Separate the solid, and wash the solid product thoroughly with ultrapure water and absolute ethanol. Calcinate the obtained white powder product in an air atmosphere at 550 °C for 8 hours to remove the organic structure-directing agent, and obtain the titanium silicalite precursor powder.

[0061] 2) Take 20 g of the titanium silicalite precursor powder, add 0.252 g (2 mmol) of melamine and 20 mmol of octyl, add 50 ml of aniline as a solvent, stir and reflux in an oil bath at 110 °C for 5 h, filter the catalyst, and then dry it in a vacuum oven at 40 °C for 5 h. The surface-modified silicate titanium silicalite molecular sieve catalyst is obtained by ball milling, with a particle size of 150 μm and a bulk density of 0.75 g / ml.

[0062] The continuous production of epichlorohydrin from allyl chloride (the process is as Figure 1 shown):

[0063] The device adopted by this method includes a bubble column reactor R1001, an oil-water separator V1001, and a condenser C1001. The outlet of the bubble column reactor is connected to the inlet of the oil-water separator. Inside the bubble column reactor, there are sieve plates, with a quantity of 38 and an inner diameter of 120 mm. The specific steps are as follows:

[0064] (1) Fresh allyl chloride and allyl chloride entraining the surface-modified silicate titanium silicalite molecular sieve catalyst prepared above are pumped into the first mixer M1001 through a metering pump. After being mixed evenly, they are transported to the bottom of the bubble reactor R1001. The aqueous hydrogen peroxide solution and the auxiliary agent NH 3 ·H 2 O are transported to the bottom and middle of the reactor through a metering pump, and nitrogen is continuously introduced into the bottom of the bubble column reactor to maintain the internal pressure of the system at 0.68 Mpa for the epoxidation reaction. The reaction temperature is 35 °C, and the residence time is 0.8 h. The percentage of the catalyst weight solid content in the reaction liquid in the reactor is 15%; the molar ratio of hydrogen peroxide contained in the aqueous hydrogen peroxide solution added to the reactor to the molar ratio of allyl chloride is 1 / 8; the mass concentration of the aqueous hydrogen peroxide solution is 50%. The feeding speed is 10 L / h, nitrogen is introduced into the bottom of the reactor to maintain the system pressure at 0.8 Mpa, and the concentration of the auxiliary agent NH 3 ·H 2 O in the system is 70 ppm, and it is pumped into the reactor together with hydrogen peroxide after being mixed.

[0065] (2) The material passing through the reactor R1001 enters the side line through the top side outlet, the reaction product overflows into the oil-water separator V1001, and the catalyst returns to the bottom of the reactor by sedimentation.

[0066] (3) The unreacted allyl chloride enters the condenser C1001 from the top of the reactor R1001, and the cooled allyl chloride enters the allyl chloride mixing tank M001 and returns to the reactor R1001 again.

[0067] (4) The reaction product overflowing into the oil-water separator V1001 separates into an oil phase containing epichlorohydrin and an aqueous phase. The aqueous phase returns to the water storage tank and is mixed with hydrogen peroxide for reuse. The oil phase product is taken out from the lower part of the oil-water separator.

[0068] The reaction is continuously carried out for 800 hours, and the selectivity of epichlorohydrin, the conversion rate of hydrogen peroxide, and the selectivity of the by-product 1,3-dichloropropanol are obtained by analyzing the separated clear liquid.

[0069] Table 2 Catalyst Evaluation Results

[0070]

[0071]

[0072] Example 2

[0073] 1) Mix 1028.75g (1.25mol) of organic structure-directing agent N,N'-dicyclohexyl-N,N,N',N'-tetramethyl-1,4-dimethylphenylammonium hydroxide with 1800g (100mol) of ultrapure water and stir at room temperature for 15 minutes. Then add 126.12g (1mol) of tetrabutyl titanate (TBOT) and 1321.3g (5mol) of tetraethyl orthosilicate (TEOS) to the system, stir and hydrolyze at 60℃ for 6 hours to obtain gel, introduce the gel into a stainless steel autoclave lined with polytetrafluoroethylene, and statically crystallize for 8 hours at a pressure of 0.5Mpa and 180℃. Separate the solid, wash the solid product thoroughly with ultrapure water and anhydrous ethanol, and calcine the obtained white powder product at 550℃ for 7 hours in an air atmosphere to remove the organic structure-directing agent to obtain the original titanium silicon molecular sieve powder.

[0074] 2) Take 20g of titanium silicate molecular sieve powder, add 0.378g (3mmol) of melamine and 18mmol of octyl, add 40ml of aniline as solvent, react at 90℃ in oil bath reflux and stirring for 5h, filter the catalyst and dry it in a vacuum oven at 50℃ for 6h to obtain a surface-modified silicate titanium silicate molecular sieve catalyst, and then ball mill to obtain a particle size of 170μm and a bulk density of 0.83g / ml.

[0075] Continuous production of epichlorohydrin from allyl chloride (process as Figure 1 shown):

[0076] The device used in this method includes a bubble tower reactor R1001, an oil-water separator V1001, and a condenser C1001. The outlet of the bubble tower reactor is connected to the inlet of the oil-water separator. The bubble tower reactor contains 35 sieve plates with an inner diameter of 180 mm. The specific steps are:

[0077] (1) Fresh propylene chloride and propylene chloride carrying the surface-modified silicate titanium silicon molecular sieve catalyst prepared above are pumped into the first mixer M1001 through a metering pump, mixed evenly and then transported to the bottom of the bubbling reactor R1001, and the aqueous hydrogen peroxide solution and the auxiliary agent NH 3 ·H 2O is pumped to the bottom and middle of the reactor through a metering pump, and nitrogen is continuously introduced from the bottom of the bubble column reactor to maintain the internal pressure of the system at 0.72 Mpa. The epoxidation reaction is carried out at a reaction temperature of 20 °C and a residence time of 0.9 h. The percentage of the catalyst weight solid content in the reaction liquid in the reactor is 15%; the molar ratio of hydrogen peroxide contained in the hydrogen peroxide aqueous solution added to the reactor to the molar ratio of allyl chloride is 1 / 8; the mass concentration of the hydrogen peroxide aqueous solution is 50%. The feeding rate is 10 L / h, nitrogen is introduced at the bottom of the reactor to keep the system pressure at 0.8 Mpa, and the concentration of the auxiliary agent NH 3 ·H 2 O in the system is 80 ppm, and it is pumped into the reactor together with hydrogen peroxide after mixing.

[0078] (2) The material passing through the reactor R1001 enters the side line through the top side outlet, the reaction product overflows into the oil-water separator V1001, and the catalyst returns to the bottom of the reactor by sedimentation.

[0079] (3) The unreacted allyl chloride enters the condenser C1001 from the top of the reactor R1001, and the cooled allyl chloride enters the allyl chloride mixing tank M001 and returns to the reactor R1001 again.

[0080] (4) The reaction product overflowing into the oil-water separator V1001 separates out the oil phase containing epichlorohydrin and the water phase. The water phase returns to the water storage tank and is mixed with hydrogen peroxide for reuse. The oil phase product is taken out from the lower part of the oil-water separator.

[0081] The reaction is continuously carried out for 800 hours, and the selectivity of epichlorohydrin, the conversion rate of hydrogen peroxide, and the selectivity of the by-product 1,3-dichloropropanol are obtained by analyzing the separated clear liquid.

[0082] Table 3 Catalyst Evaluation Results

[0083]

[0084] Example 3

[0085] 1) 329.2g (0.4mol) of N,N'-dicyclohexyl-N,N,N',N'-tetramethyl-1,4-dimethylphenylammonium hydroxide and N,N,N,N',N',N'-hexaethyl-4,4'-bis(methyl)-1,1'-biphenylammonium hydroxide mixture (molar ratio 1:1) were mixed with 450g (25mol) of ultrapure water and stirred at room temperature for 15 minutes. Then 18.918g (0.15mol) of tetrabutyl titanate (TBOT) and 264.26g (1mol) of tetraethyl orthosilicate (TEOS) were added to the system, stirred and hydrolyzed at 75°C for 8 hours to obtain a gel, which was introduced into a stainless steel autoclave lined with polytetrafluoroethylene and subjected to static crystallization reaction at a pressure of 2Mpa and 220°C for 5 hours. The solid was separated and washed thoroughly with ultrapure water and anhydrous ethanol. The obtained white powder product was calcined at 650°C for 4 hours in an air atmosphere to remove the organic structure directing agent and obtain the titanium silicon molecular sieve raw powder.

[0086] 2) Take 20g of titanium silicate molecular sieve powder, add 0.504g (4mmol) of melamine and 19mmol of octyl, add 45ml of aniline as solvent, stir and react in oil bath reflux at 120℃ for 7h, filter the catalyst and dry it in a vacuum oven at 70℃ for 3h to obtain a surface-modified silicate titanium silicate molecular sieve catalyst. After ball milling, the particle size is 200μm and the bulk density is 0.61g / ml.

[0087] Continuous production of epichlorohydrin from allyl chloride (process as Figure 1 shown):

[0088] The device used in this method includes a bubble tower reactor R1001, an oil-water separator V1001, and a condenser C1001. The outlet of the bubble tower reactor is connected to the inlet of the oil-water separator. The bubble tower reactor contains 43 sieve plates with an inner diameter of 210 mm. The specific steps are:

[0089] (1) Fresh propylene chloride and propylene chloride carrying the surface-modified silicate titanium silicon molecular sieve catalyst prepared above are pumped into the first mixer M1001 through a metering pump, mixed evenly and then transported to the bottom of the bubbling reactor R1001, and the aqueous hydrogen peroxide solution and the auxiliary agent NH 3 ·H 2O is delivered to the bottom and middle of the reactor through a metering pump, and nitrogen is continuously introduced from the bottom of the bubble column reactor to maintain the internal pressure of the system at 0.94 Mpa. The epoxidation reaction is carried out at a reaction temperature of 15 °C and a residence time of 1 h. The percentage of the catalyst weight solid content in the reaction liquid in the reactor is 18%; the molar ratio of hydrogen peroxide contained in the aqueous hydrogen peroxide solution added to the reactor to the molar ratio of allyl chloride is 1:4; the mass concentration of the aqueous hydrogen peroxide solution is 50%. The feeding rate is 10 L / h, nitrogen is introduced at the bottom of the reactor to keep the system pressure at 0.94 Mpa, and the concentration of the promoter NH 3 ·H 2 O in the system is 80 ppm, and it is mixed with hydrogen peroxide and then pumped into the reactor together.

[0090] (2) The material passing through the reactor R1001 enters the side line through the top side outlet, the reaction product overflows into the oil-water separator V1001, and the catalyst returns to the bottom of the reactor by sedimentation.

[0091] (3) The unreacted allyl chloride enters the condenser C1001 from the top of the reactor R1001, and the cooled allyl chloride enters the allyl chloride mixing tank M001 and then returns to the reactor R1001 again.

[0092] (4) The reaction product overflowing into the oil-water separator V1001 separates into an oil phase containing epichlorohydrin and an aqueous phase. The aqueous phase returns to the water storage tank and is mixed with hydrogen peroxide for reuse. The oil phase product is taken out from the lower part of the oil-water separator.

[0093] The reaction is continuously carried out for 800 hours, and the epichlorohydrin selectivity, hydrogen peroxide conversion rate, and by-product 1,3-dichloropropanol selectivity are obtained by analyzing the separated clear liquid.

[0094] Table 3 Catalyst Evaluation Results

[0095] Running time / h Conversion rate of hydrogen peroxide / % Selectivity of epichlorohydrin / % Selectivity of 1,3-dichloropropanol / % 10 90.07％ 99.50％ 0.02％ 50 90.12％ 96.47％ 0.03％ 100 90.13％ 99.67％ 0.01％ 200 90.27％ 99.61％ 0.03％ 300 90.21％ 99.58％ 0.02％ 400 90.13％ 99.53％ 0.03％ 500 90.28％ 99.27％ 0.04％ 600 90.08％ 99.42％ 0.02％ 700 90.27％ 99.45％ 0.03％ 800 90.34％ 99.67％ 0.04％

[0096] Comparative Example 1

[0097] Referring to the method of Example 1, the difference is only that: in step 1) of the catalyst preparation, an organic structure directing agent is not used, and other operations remain unchanged, and the catalyst is prepared.

[0098] Epichlorohydrin is continuously produced from allyl chloride, and the method is the same as that of Example 1, and the results are shown in Table 4.

[0099] Comparative Example 2

[0100] Referring to the preparation method of Example 1, the difference is only that: in step 2) of the catalyst preparation, melamine is not added, and other operations remain unchanged, and the catalyst is prepared.

[0101] Epichlorohydrin is continuously produced from allyl chloride by the same method as in Example 1, and the results are shown in Table 4.

[0102] Comparative Example 3

[0103] Referring to the preparation method of Example 1, the only difference is that in step 2) of the catalyst preparation, melamine is replaced by ammonium chloride, and other operations remain unchanged to obtain the catalyst.

[0104] Epichlorohydrin is continuously produced from allyl chloride by the same method as in Example 1, and the results are shown in Table 4.

[0105] Comparative Example 4

[0106] Referring to the preparation method of Example 1, the only difference is that in step 2) of the catalyst preparation, octyl group is not added, and other operations remain unchanged to obtain the catalyst.

[0107] Epichlorohydrin is continuously produced from allyl chloride by the same method as in Example 1, and the results are shown in Table 4.

[0108] Table 4 Evaluation Results of Catalysts in Comparative Examples 1-4

[0109] Conversion rate of hydrogen peroxide / % Selectivity of epichlorohydrin / % Selectivity of 1,3-dichloropropanol / % Comparative example 1 60.68％ 93.15％ 6.23％ Comparative example 2 59.31％ 92.45％ 7.03％ Comparative example 3 71.23％ 92.17％ 7.34％ Comparative example 4 24.74％ 91.63％ 8.06％

[0110] From the results of the comparative examples and examples, it can be seen that after using the modified catalyst, the conversion rate of hydrogen peroxide of the catalyst can reach 90%, and the conversion rate of epichlorohydrin also reaches 99%; after continuous reaction for 800 h, the selectivity of epichlorohydrin remains above 99%, and the conversion rate of hydrogen peroxide is always greater than 90%, indicating that the catalyst has high activity and stability. The by-product 1,3-dichloropropanol can also ensure a small production amount under high activity, indicating that the catalyst has high selectivity.

[0111] The above is only the best embodiment of the present invention and does not impose any formal restrictions on the present invention.

Claims

1. A method for preparing a surface-modified silicate titanium silicon molecular sieve catalyst, characterized in that the steps include: 1) Mix the organic structure directing agent with water, stir evenly, then add tetrabutyl titanate and tetraethyl orthosilicate, and perform hydrolysis reaction under stirring to obtain gel, then increase the temperature under high pressure to perform crystallization reaction, separate the solid, wash with water, wash with alcohol, and calcine to obtain titanium silicon molecular sieve raw powder; 2) Mixing titanium silicate molecular sieve powder with melamine, C8-10-alkyl glycidyl ether and aniline, reacting at 80-150° C., filtering and drying to obtain surface-modified silicate titanium silicate molecular sieve; In step 1), the organic structure directing agent is selected from at least one of N,N,N,N',N',N'-hexaethyl-4,4'-bis(methyl)-1,1'-biphenylammonium hydroxide and N,N'-dicyclohexyl-N,N,N',N'-tetramethyl-1,4-dimethylphenylammonium hydroxide.

2. The preparation method according to claim 1, characterized in that: In step 1), the molar ratio of tetraethyl orthosilicate to tetrabutyl titanate, organic structure directing agent and water is 1.0: 0.02-0.20: 0.20-0.50: 10-30.

3. The preparation method according to claim 2, characterized in that: The molar ratio of tetraethyl orthosilicate to tetrabutyl titanate, organic structure directing agent and water is 1:0.025-0.20:0.25-0.5:12-30.

4. The preparation method according to claim 1, characterized in that: In step 1), the stirring time is 30-60 min; In step 1), the hydrolysis reaction is carried out at a temperature of 30-90°C and a time of 5-9h; In step 1), the crystallization reaction is carried out at a pressure of 0.3-4 MPa, a temperature of 130-250° C., and a time of 5-9 h; In step 1), the calcination temperature is 400-700° C. and the time is 4-9 hours.

5. The preparation method according to claim 4, characterized in that: The hydrolysis reaction is carried out at a temperature of 35-75°C and a time of 5-8 hours.

6. The preparation method according to claim 4, characterized in that: The crystallization reaction has a pressure of 0.5-2 MPa, a temperature of 150-220° C., and a time of 5-8 h.

7. The preparation method according to claim 4, characterized in that: The calcination temperature is 450-650° C. and the calcination time is 4-8 hours.

8. The preparation method according to claim 1, characterized in that: In step 2), the mass ratio of the titanium silicon molecular sieve raw powder to melamine is 1:0.01-0.1; In step 2), the molar ratio of melamine to C8-10-alkyl glycidyl ether is 1:5-200; In step 2), the concentration of the titanium silicon molecular sieve raw powder in aniline is 0.1-1 g / ml.

9. The preparation method according to claim 8, characterized in that: The mass ratio of the titanium silicon molecular sieve raw powder to melamine is 1:0.01-0.

05.

10. The preparation method according to claim 8, characterized in that: The molar ratio of melamine to C8-10-alkyl glycidyl ether is 1:50-200.

11. The preparation method according to claim 8, characterized in that: The concentration of the titanium silicon molecular sieve raw powder in aniline is 0.2-0.8 g / ml.

12. The preparation method according to claim 1, characterized in that: In step 2), the reaction time is 3-7h; In step 2), the drying temperature is 30-90° C. and the time is 1-10 h.

13. The preparation method according to claim 12, characterized in that: The reaction temperature is 90-140°C and the reaction time is 3-7h.

14. The preparation method according to claim 12, characterized in that: The drying temperature is 30-80°C and the time is 2-8h.

15. A surface-modified silicate titanium silicon molecular sieve catalyst prepared by the method according to any one of claims 1 to 14, characterized in that: The particle size is 100-500μm and the bulk density is 0.5g / mL-1.5g / mL.

16. The surface-modified silicate titanium silicon molecular sieve catalyst according to claim 15, characterized in that: The particle size is 100-350 μm, and the bulk density is 0.5-g / mL-1.3 g / mL.

17. Use of the surface-modified silicate titanium silicon molecular sieve catalyst prepared by the method according to any one of claims 1 to 14 in the preparation of epichlorohydrin.

18. A continuous process for producing epichlorohydrin by epoxidation of allyl chloride, characterized in that: The device used in the method includes a bubbling tower reactor, an oil-water separator, and a condenser, wherein the outlet of the bubbling tower reactor is connected to the inlet of the oil-water separator, and the specific steps include: (1) fresh allyl chloride and allyl chloride carrying the surface-modified silicate titanium silicon molecular sieve catalyst prepared by the method according to any one of claims 1 to 14 are mixed and transported to the bottom of a bubbling column reactor, and an aqueous hydrogen peroxide solution and an auxiliary agent NH3·H2O are transported to the bottom of the bubbling column reactor, and nitrogen is continuously introduced from the bottom of the bubbling column reactor to maintain the internal pressure of the system at 0.1-4 MPa for epoxidation reaction, the reaction temperature is 10-70°C, and the residence time is 0.5-6h; (2) The reaction materials in the bubble column reactor enter the oil-water separator through the top outlet, and the catalyst slowly falls from the side line of the bubble column reactor to the bottom of the bubble column reactor by free sedimentation, so that the catalyst is separated from the liquid phase; (3) The unreacted allyl chloride is cooled by a condenser from the top of the bubble tower reactor and then returned to step (1) to be mixed with the raw materials; (4) After the materials entering the oil-water separator are separated, the water phase flows out from the upper end of the oil-water separator, and the oil phase containing the product epichlorohydrin flows out from the lower end of the oil-water separator.

19. The continuous process according to claim 18, characterized in that: In step (1), the internal pressure of the system is maintained at 0.2-1 MPa for epoxidation reaction, the reaction temperature is 20-50°C, and the residence time is 0.5-3h.

20. The continuous process according to claim 18, characterized in that: The bubble column reactor contains 10-50 sieve plates inside; the inner diameter of the sieve plates is 50-300 mm; The catalyst content of the reaction liquid in the bubble column reactor is 1-20wt%; The ratio of the mole number of hydrogen peroxide to the mole number of allyl chloride contained in the aqueous hydrogen peroxide solution added to the reactor is 1:4-10; The mass concentration of the aqueous hydrogen peroxide solution is 27.5-60%; The concentration of the auxiliary agent NH3·H2O in the system is 50-150ppm.

21. The continuous process according to claim 20, characterized in that: The number of the sieve plates is 15-43; the inner diameter of the sieve plates is 70-280 mm.

22. The continuous process according to claim 20, characterized in that: The catalyst content of the reaction liquid in the bubble tower reactor is 5-18 wt %.

23. The continuous process according to claim 20, characterized in that: The ratio of the mole number of hydrogen peroxide to the mole number of allyl chloride contained in the aqueous hydrogen peroxide solution added to the reactor is 1:4-8.

24. The continuous process according to claim 20, characterized in that: The mass concentration of the aqueous hydrogen peroxide solution is 27.5-50%.

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