A method for preparing styrene oxide

Abstract

The present invention relates to a method for preparing ethylene oxide, which comprises: S1, using nano-carbon materials as catalysts to carry out direct dehydrogenation reaction of ethylbenzene, and performing gas-liquid separation on the mixture obtained after the direct dehydrogenation reaction to obtain a gas phase product and a liquid phase product; S2, in the presence of a titanium silicon catalyst and an optional solvent, contacting the liquid phase product with hydrogen peroxide to carry out an epoxidation reaction. The method of the present invention prepares ethylene oxide from ethylbenzene, and has a high ethylbenzene conversion rate and ethylene oxide selectivity.

Description

Technical Field

[0001] The present invention relates to a method for preparing styrene oxide. Background Art

[0002] Epoxides, such as styrene oxide, are chemically active and widely used. They are primarily used in the production of polyethers, non-polyether polyols, surfactants, and other applications in the chemical, light, pharmaceutical, food, and textile industries, profoundly impacting the development of the chemical industry and the national economy. However, existing technologies for preparing styrene oxide suffer from low conversion rates and poor selectivity, necessitating improvements. Summary of the Invention

[0003] The object of the present invention is to provide a method for preparing styrene oxide, which has high ethylbenzene conversion rate and styrene oxide selectivity.

[0004] In order to achieve the above object, the present invention provides a method for preparing styrene oxide, which comprises:

[0005] S1. Using nanocarbon materials as catalysts, performing a direct dehydrogenation reaction of ethylbenzene, and performing gas-liquid separation on the mixture obtained after the direct dehydrogenation reaction to obtain a gas phase product and a liquid phase product;

[0006] S2. In the presence of a titanium-silicon catalyst and an optional solvent, contacting the liquid product with hydrogen peroxide to carry out an epoxidation reaction.

[0007] Optionally, in step S1, the conditions for the direct dehydrogenation reaction include: temperature of 250-700° C., pressure of 0.1-2.5 MPa, and time of 1-10 h.

[0008] Optionally, the gas-liquid separation of the mixture obtained after the direct dehydrogenation reaction includes: exchanging heat and cooling the mixture obtained after the direct dehydrogenation reaction with the epoxidation product obtained by the epoxidation reaction.

[0009] Optionally, in step S1, the liquid product contains ethylbenzene and styrene; based on the total weight of the liquid product, the content of ethylbenzene is 5-95% by weight, preferably 10-60% by weight.

[0010] Optionally, in step S2, the epoxidation reaction conditions include: temperature of 0-80°C, pressure of 0.1-3.0 MPa, and time of 1-18 h.

[0011] Optionally, in step S2, the molar ratio of the liquid phase product to the amount of hydrogen peroxide is 1:(0.1-2), preferably 1:(0.2-1.0), and the liquid phase product is calculated as styrene;

[0012] The weight ratio of the solvent to the liquid product is 100:(1-500), preferably 100:(5-200).

[0013] Optionally, in step S2, the solvent is selected from one or more of water, alcohol, ketone and nitrile;

[0014] Preferably, the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol and isobutanol; the ketone is acetone and / or butanone; and the nitrile is acetonitrile.

[0015] Optionally, in step S2, the titanium silicon catalyst contains titanium silicon molecular sieve, and the content of the titanium silicon molecular sieve is 50-100% by weight based on the total weight of the titanium silicon catalyst, and the silicon-titanium molar ratio of the titanium silicon molecular sieve is 15-100.

[0016] Optionally, in step S1, the nano-carbon material is prepared by a method comprising the following steps: calcining a biomass carbon material at 800-1300° C. for 2-10 h in an ammonia atmosphere to obtain the nano-carbon material;

[0017] Based on the total weight of the nano-carbon material, the carbon content of the nano-carbon material is 80-99.9% by weight, the nitrogen content is 0.1-10% by weight, and the balance is oxygen;

[0018] The ammonia atmosphere contains ammonia and nitrogen, and the content of ammonia is 0.1-10% by volume;

[0019] The biomass carbon material is selected from one or more of cellulose, hemicellulose, lignin, sucrose and starch.

[0020] Optionally, the method is a continuous operation, and in step S1, the volume space velocity of ethylbenzene is 0.1-1000h -1 , preferably 10-100h -1 In step S2, the total volume space velocity of the epoxidation reaction is 0.1-100h -1 , preferably 1-20h -1 .

[0021] Through the above technical solution, the method of the present invention uses nanocarbon materials to catalyze the direct dehydrogenation reaction of ethylbenzene, which is beneficial to reducing the production cost of styrene oxide. The method of the present invention can also improve the conversion rate of ethylbenzene and the selectivity of styrene oxide.

[0022] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0023] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0024] The present invention provides a method for preparing styrene oxide, which comprises:

[0025] S1. Using nanocarbon materials as catalysts, performing a direct dehydrogenation reaction of ethylbenzene, and performing gas-liquid separation on the mixture obtained after the direct dehydrogenation reaction to obtain a gas phase product and a liquid phase product;

[0026] S2. In the presence of a titanium-silicon catalyst and an optional solvent, contacting the liquid product with hydrogen peroxide to carry out an epoxidation reaction.

[0027] The method of the present invention has a simple and easy process. The method uses nano-carbon materials to catalyze the direct dehydrogenation reaction of ethylbenzene. The reaction temperature is low, and the nano-carbon materials as catalysts do not have problems such as combustion and over-oxidation. The service life of the catalyst is effectively guaranteed. At the same time, the requirements for the structure and strength of the nano-carbon materials are greatly reduced, which is beneficial to reducing the production cost of styrene oxide and also beneficial to improving the conversion rate of ethylbenzene and the selectivity of styrene oxide.

[0028] In one embodiment of the present invention, the gas-liquid separation of the mixture obtained after the direct dehydrogenation reaction comprises: exchanging heat between the mixture after the direct dehydrogenation reaction and the epoxidation product obtained by the epoxidation reaction to cool the mixture. Exchanging heat between the mixture after the direct dehydrogenation of ethylbenzene and the epoxidation product facilitates gas-liquid separation of the mixture after the direct dehydrogenation reaction and separation and purification of the oxidation product, ethylene oxide. Furthermore, the temperature of the mixture after the direct dehydrogenation of ethylbenzene is reduced by the epoxidation product stream. The reduced temperature of the liquid product after the direct dehydrogenation of ethylbenzene after the heat exchange facilitates the epoxidation reaction in step S2 and improves heat utilization.

[0029] According to the present invention, in step S1, the conditions for the direct dehydrogenation reaction may include: temperature of 250-700°C, pressure of 0.1-2.5 MPa, and time of 1-10 h; preferably, temperature of 300-600°C, pressure of 0.1-2 MPa, and time of 2-8 h.

[0030] According to the present invention, in step S1, the ethylbenzene dehydrogenation reaction is preferably carried out continuously, and the volume space velocity of ethylbenzene can be varied within a large range. In order to allow ethylbenzene and the nanocarbon material to fully contact and react, in a preferred embodiment, the volume space velocity of the ethylbenzene dehydrogenation reaction is 0.1-1000h -1 , preferably 10-100h -1When the volume space velocity of ethylbenzene is within the above range, the dehydrogenation reaction can be carried out more efficiently, which is also beneficial to further improve the ethylbenzene conversion rate and the selectivity of styrene oxide.

[0031] According to the present invention, in step S1, the liquid product mainly contains ethylbenzene and styrene; based on the total weight of the liquid product, the content of ethylbenzene can be 5-95% by weight, preferably 20-60% by weight.

[0032] According to the present invention, in step S2, the epoxidation reaction conditions may include: temperature of 0-80°C, pressure of 0.1-3.0 MPa, and time of 1-18 h; preferably, temperature of 20-60°C, pressure of 0.1-2 MPa, and time of 2-12 h.

[0033] In a specific embodiment of the present invention, in step S2, the molar ratio of the liquid product to the amount of hydrogen peroxide is 1:(0.1-2), preferably 1:(0.2-1.0), and the liquid product is calculated as styrene; the weight ratio of the solvent to the amount of the liquid product is 100:(1-500), preferably 100:(5-200).

[0034] According to the present invention, in step S2, the solvent can be selected from one or more of water, alcohol, ketone and nitrile. In a preferred embodiment, the alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol and isobutanol; the ketone is acetone and / or butanone; and the nitrile is acetonitrile.

[0035] According to the present invention, in step S2, the titanium silicon catalyst contains titanium silicon molecular sieve, which is well known to those skilled in the art. For example, it can be one or more of titanium silicon molecular sieves having an MFI structure, a MOR structure, a BEA structure, etc. The content of titanium silicon molecular sieve in the titanium silicon catalyst can vary within a large range. For example, based on the total weight of the titanium silicon catalyst, the content of titanium silicon molecular sieve is 50-100% by weight, preferably 70-100% by weight. The silicon-titanium molar ratio of the titanium silicon molecular sieve can also vary within a large range, for example, it can be 15-100, preferably 20-50.

[0036] According to the present invention, in step S1, there is no restriction on the source of the nano-carbon material, and the nano-carbon material can be purchased commercially or prepared by the user.

[0037] In one embodiment, the nanocarbon material is preferably ammonia-nitrogen-modified biomass carbon particles, prepared by a method comprising the following steps: calcining the biomass carbon material at 800-1300° C. for 2-10 hours in an ammonia atmosphere to obtain the nanocarbon material. The biomass carbon material is commonly used by those skilled in the art, and can be, for example, selected from one or more of cellulose, hemicellulose, lignin, sucrose, and starch.

[0038] According to the present invention, in step S1, in order to prepare nanocarbon materials with good catalytic performance, the ammonia atmosphere also contains nitrogen as a balance gas. The ammonia content can vary within a wide range, for example, 0.1-10% by volume, preferably 0.5-5% by volume.

[0039] According to the present invention, in step S1, based on the total weight of the nano-carbon material, the carbon content of the nano-carbon material can be 80-99.9% by weight, the nitrogen content can be 0.1-10% by weight, and the balance is oxygen; preferably, the carbon content of the nano-carbon material is 90-99% by weight, the nitrogen content is 0.2-5% by weight, and the balance is oxygen.

[0040] According to the present invention, the method of the present invention can be a continuous operation. In step S2, the total volume space velocity of the epoxidation reaction is 0.1-100h -1 Considering the comprehensive performance such as process energy consumption, 1-20h is preferred. -1 .

[0041] The present invention is further illustrated below by way of examples, but the present invention is not limited thereto.

[0042] The reagents used in the examples and comparative examples are all commercially available chemically pure reagents.

[0043] The nanocarbon material is biomass carbon particles modified with ammonia and nitrogen. The specific preparation method is: cellulose is calcined at 1100°C for 6 hours in a 2% by volume ammonia atmosphere, with the balance gas being nitrogen. The carbon content in the nanocarbon material is 93% by weight, the nitrogen content is 2.1% by weight, and the balance is oxygen.

[0044] Titanium silicate molecular sieve (TS-1) is a calcined molecular sieve (TS-1) prepared according to the method described in the prior art Zeolites, 1992, Vol. 12, pp. 943-950. The silicon to titanium molar ratio of titanium silicate molecular sieve (TS-1) is 27.

[0045] In the comparative examples and examples:

[0046] Ethylbenzene conversion (%) = (molar amount of ethylbenzene in feed - molar amount of unreacted ethylbenzene) / molar amount of ethylbenzene in feed × 100%;

[0047] Epoxy styrene selectivity (%) = molar amount of epoxy styrene in the product / molar amount of total ethylbenzene conversion × 100%.

[0048] Example 1

[0049] S1, at atmospheric pressure, 500℃, ethylbenzene volume space velocity of 20h -1ethylbenzene is first subjected to a direct dehydrogenation reaction for 6 hours over a bed containing a nanocarbon material as a catalyst, the mixture obtained after the direct dehydrogenation reaction is heat exchanged with an epoxidation product, and then cooled, followed by gas-liquid separation to obtain a gaseous product and a liquid product; wherein the ethylbenzene content in the liquid product is 46% by weight, with the remainder being styrene;

[0050] S2, at a temperature of 60 ° C, a pressure of 0.5 MPa, and a total volume space velocity of 10 h -1 The liquid product was contacted with hydrogen peroxide, methanol, and TS-1 for 3 hours to carry out an epoxidation reaction to obtain an epoxidation product. The molar ratio of the liquid product (calculated as styrene) to hydrogen peroxide was 1:1, and the weight ratio of the liquid product to methanol was 2:1. The reaction results are shown in Table 1.

[0051] Example 2

[0052] S1, at atmospheric pressure, 400℃, ethylbenzene volume space velocity of 60h -1 Under the conditions of 100 nm, ethylbenzene was first subjected to a direct dehydrogenation reaction for 8 hours through a bed containing a nanocarbon material as a catalyst. The mixture obtained after the direct dehydrogenation reaction was subjected to heat exchange cooling with the epoxidation product, and then gas-liquid separation was performed to obtain a gas phase product and a liquid phase product; wherein the ethylbenzene content in the liquid phase product was 71% by weight, and the balance was styrene;

[0053] S2, at a temperature of 40 ° C, a pressure of 2.5 MPa, and a total volume space velocity of 2 h -1 The liquid product was contacted with hydrogen peroxide, methanol, and TS-1 for 3 hours to carry out an epoxidation reaction to obtain an epoxidation product, wherein the molar ratio of the liquid product (calculated as styrene) to hydrogen peroxide was 2:1, and the weight ratio of the liquid product to methanol was 1:20.

[0054] Example 3

[0055] S1, at atmospheric pressure, 550℃, ethylbenzene volume space velocity of 150h -1 Under the conditions of 100 nm, ethylbenzene was first subjected to a direct dehydrogenation reaction for 8 hours through a bed containing a nanocarbon material as a catalyst. The mixture obtained after the direct dehydrogenation reaction was subjected to heat exchange cooling with the epoxidation product, and then gas-liquid separation was performed to obtain a gas phase product and a liquid phase product; wherein the ethylbenzene content in the liquid phase product was 52% by weight, and the balance was styrene;

[0056] S2, at a temperature of 50°C, a pressure of 1.5 MPa, and a total volume space velocity of 100 h -1 The liquid product was contacted with hydrogen peroxide, tert-butyl alcohol, and TS-1 for epoxidation for 2 hours to obtain an epoxidation product, wherein the molar ratio of the liquid product (calculated as styrene) to hydrogen peroxide was 20:1, and the weight ratio of the liquid product to tert-butyl alcohol was 1:5.

[0057] Example 4

[0058] Epoxystyrene was prepared by the same method as in Example 1, except that in step S1, the volume space velocity of ethylbenzene was 250h -1 The content of ethylbenzene in the liquid product is 58% by weight, and the balance is styrene.

[0059] Example 5

[0060] Epoxystyrene was prepared by the same method as in Example 1, except that in step S1, the direct dehydrogenation reaction time was 2 h, the temperature was 700° C., and the ethylbenzene content in the liquid product was 9 wt %, with the remainder being styrene.

[0061] Example 6

[0062] Epoxystyrene was prepared by the same method as in Example 1, except that the nanocarbon material used in step S1 was different. The preparation method was as follows: cellulose was calcined at 700° C. for 6 h in a 5 vol % ammonia atmosphere with nitrogen as the balance gas. The carbon content in the nanocarbon material was 91 wt %, the nitrogen content was 1.3 wt %, and the balance was oxygen.

[0063] The content of ethylbenzene in the mixed liquid in step S1 is 36% by weight, and the balance is styrene.

[0064] Example 7

[0065] Epoxystyrene was prepared by the same method as in Example 1, except that the molar ratio of the liquid product (calculated as styrene) to hydrogen peroxide in step S2 was 1:0.1.

[0066] Example 8

[0067] Epoxystyrene was prepared by the same method as in Example 1, except that the weight ratio of the liquid product to methanol in step S2 was 4:1.

[0068] Example 9

[0069] Epoxystyrene was prepared by the same method as in Example 1, except that the epoxidation reaction in step S2 was carried out at a temperature of 100° C., a pressure of 0.2 MPa, and a time of 3 h.

[0070] Example 10

[0071] Epoxystyrene was prepared by the same method as in Example 1, except that in step S2, the total volume space velocity was 55h -1 .

[0072] Comparative Example 1

[0073] Epoxystyrene was prepared using the same method as in Example 1, except that no nanocarbon material was used in step S1.

[0074] Comparative Example 2

[0075] Epoxystyrene was prepared by the same method as in Example 1, except that catalyst TS-1 was not used in step S2.

[0076] Comparative Example 3

[0077] Epoxystyrene was prepared by the same method as in Example 1, except that no nanocarbon material was used in step S1 and no catalyst TS-1 was used in step S2.

[0078] Table 1

[0079] Ethylbenzene conversion rate (%) Epoxystyrene selectivity (%) Example 1 54 82 Example 2 29 77 Example 3 48 89 Example 4 42 80 Example 5 91 74 Example 6 36 81 Example 7 54 72 Example 8 54 78 Example 9 54 39 Example 10 54 81 Comparative Example 1 6 78 Comparative Example 2 54 3 Comparative Example 3 4 2

[0080] As can be seen from Table 1, the method provided by the present invention can prepare styrene oxide from ethylbenzene, and has a high ethylbenzene conversion rate and styrene oxide selectivity.

[0081] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0082] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0083] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing styrene oxide, the method comprising: S1. Using nano-carbon materials as catalysts, direct dehydrogenation of ethylbenzene is performed, and the mixture obtained after the direct dehydrogenation reaction is subjected to gas-liquid separation to obtain a gas phase product and a liquid phase product; S2, in the presence of a titanium-silicon catalyst and an optional solvent, contacting the liquid product with hydrogen peroxide to carry out an epoxidation reaction; The nano-carbon material is prepared by a method comprising the following steps: in an ammonia atmosphere, a biomass carbon material is roasted at 800-1300° C. for 2-10 hours to obtain the nano-carbon material; the ammonia atmosphere contains ammonia and nitrogen, and the ammonia content is 0.1-10% by volume; the biomass carbon material is selected from one or more of cellulose, hemicellulose, lignin, sucrose and starch.

2. The method according to claim 1, wherein: In step S1, the conditions for the direct dehydrogenation reaction include: temperature of 250-700°C, pressure of 0.1-2.5 MPa, and time of 1-10 h.

3. The method according to claim 1, wherein: The gas-liquid separation of the mixture obtained after the direct dehydrogenation reaction comprises: heat exchanging and cooling the mixture obtained after the direct dehydrogenation reaction and the epoxidation product obtained by the epoxidation reaction.

4. The method according to claim 1, wherein: In step S1, the liquid phase product contains ethylbenzene and styrene; based on the total weight of the liquid phase product, the content of ethylbenzene is 5-95% by weight.

5. The method according to claim 4, wherein: Based on the total weight of the liquid phase product, the content of ethylbenzene is 10-60% by weight.

6. The method according to claim 1, wherein: In step S2, the conditions of the epoxidation reaction include: temperature of 0-80°C, pressure of 0.1-3.0 MPa, and time of 1-18 h.

7. The method according to claim 1, wherein: In step S2, the molar ratio of the liquid phase product to the amount of hydrogen peroxide is 1:(0.1-2), and the liquid phase product is calculated in terms of styrene; The weight ratio of the solvent to the liquid product is 100:(1-500).

8. The method according to claim 7, wherein: The molar ratio of the liquid phase product to the amount of hydrogen peroxide is 1:(0.2-1.0); The weight ratio of the solvent to the liquid product is 100:(5-200).

9. The method according to claim 1, wherein: In step S2, the solvent is selected from one or more of water, alcohol, ketone and nitrile.

10. The method according to claim 9, wherein: The alcohol is selected from one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol and isobutanol; the ketone is acetone and / or butanone; and the nitrile is acetonitrile.

11. The method according to claim 1, wherein: In step S2, the titanium silicon catalyst contains titanium silicon molecular sieve, and based on the total weight of the titanium silicon catalyst, the content of the titanium silicon molecular sieve is 50-100% by weight, and the silicon-titanium molar ratio of the titanium silicon molecular sieve is 15-100.

12. The method according to claim 1, wherein: Based on the total weight of the nano-carbon material, the carbon content of the nano-carbon material is 80-99.9% by weight, the nitrogen content is 0.1-10% by weight, and the balance is oxygen.

13. The method according to claim 1, wherein: The method is a continuous operation. In step S1, the volume space velocity of ethylbenzene is 0.1-1000h -1 In step S2, the total volume space velocity of the epoxidation reaction is 0.1-100h -1 .

14. The method according to claim 13, wherein: The volume space velocity of ethylbenzene is 10-100h -1 The total volume space velocity of the epoxidation reaction is 1-20h -1 .