A method for ethylbenzene oxidation

Abstract

The present invention relates to a method for oxidizing ethylbenzene, which comprises: S1, contacting ethylbenzene and oxygen with nano-carbon materials to carry out oxidative dehydrogenation reaction, separating the obtained oxidative dehydrogenation reaction product into gas and liquid to obtain gas phase product and liquid phase product, and then separating the liquid phase product into layers to obtain oil phase product and water phase product; S2, contacting the oil phase product with hydrogen peroxide in the presence of titanium silicon catalyst and optional solvent to carry out epoxidation reaction. The method of the present invention has high ethylbenzene conversion rate and selectivity of ethylene oxide.

Description

Technical Field

[0001] The present invention relates to a method for ethylbenzene oxidation. Background Art

[0002] Epoxides such as styrene oxide have very active chemical properties and are widely used. They are mainly used to produce polyethers, non-polyether polyols, surfactants, etc. They are widely used in chemical, light industry, medicine, food, textile and other industries, and have a profound impact on the development of the chemical industry and the national economy. However, the existing technology has problems such as low conversion rate and poor selectivity in the process of preparing styrene oxide, which urgently need to be improved. Summary of the invention

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

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

[0005] S1, contacting ethylbenzene and oxygen with the nano-carbon material to carry out oxidative dehydrogenation reaction, separating the obtained oxidative dehydrogenation reaction product into gas and liquid to obtain a gas phase product and a liquid phase product, and then separating the liquid phase product into layers to obtain an oil phase product and a water phase product;

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

[0007] Optionally, in step S1, the conditions of the oxidative dehydrogenation reaction include: temperature of 250-700°C, pressure of 0.1-2.5 MPa, time of 1-10 h, and a molar ratio of oxygen in the oxygen-containing atmosphere to ethylbenzene of (0.1-10):1.

[0008] Optionally, the gas-liquid separation of the obtained oxidative dehydrogenation reaction product comprises: exchanging heat between the mixture after the oxidative dehydrogenation reaction and the epoxidation product obtained by the epoxidation reaction.

[0009] Optionally, in step S1, the oil phase product contains ethylbenzene and styrene; based on the total weight of the oil phase product, the content of ethylbenzene is 5-95% by weight, preferably 20-60% by weight.

[0010] Optionally, in step S2, the conditions of the epoxidation reaction include: temperature of 10-70° C., pressure of 0.5-2.5 MPa, and time of 1-18 h.

[0011] Optionally, in step S2, the molar ratio of the oil phase product to the amount of hydrogen peroxide is 1:(0.5-2.5), preferably 1:(0.6-1), and the oil phase product is calculated in terms of styrene;

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

[0013] Optionally, the oxidant is hydrogen peroxide;

[0014] The solvent is selected from one or more of water, alcohol, ketone and nitrile;

[0015] 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.

[0016] Optionally, 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.

[0017] Optionally, the nano-carbon material is prepared by a method comprising the following steps: roasting the biomass carbon material at 800-1300° C. for 2-10 h in an ammonia atmosphere to obtain the nano-carbon material;

[0018] 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;

[0019] The ammonia atmosphere contains ammonia and nitrogen, and the content of ammonia is 0.1-10% by volume;

[0020] The biomass carbon material is selected from one or more of cellulose, hemicellulose, lignin, sucrose and starch.

[0021] Optionally, the method is a continuous operation, and the volume space velocity of ethylbenzene is 0.1-1000h -1 The total volume space velocity of the epoxidation reaction is 0.1-100h -1 , preferably 1-20h -1 .

[0022] Through the above technical scheme, the method of the present invention uses nano-carbon materials to catalyze the oxidative dehydrogenation reaction of ethylbenzene, the reaction temperature is reduced, and the requirements for the structure and strength of the nano-carbon materials are greatly reduced, which is conducive to reducing the preparation or procurement cost of the nano-carbon materials. The method of the present invention can also improve the conversion rate of ethylbenzene and the selectivity of styrene oxide.

[0023] Other features and advantages of the present invention will be described in detail in the following detailed description. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention are described in detail below. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention, and are not used to limit the present invention.

[0025] The present invention provides a method for oxidizing ethylbenzene, the method comprising:

[0026] S1, contacting ethylbenzene and oxygen with the nano-carbon material to carry out oxidative dehydrogenation reaction, separating the obtained oxidative dehydrogenation reaction product into gas and liquid to obtain a gas phase product and a liquid phase product, and then separating the liquid phase product into layers to obtain an oil phase product and a water phase product;

[0027] S2. In the presence of a titanium-silicon catalyst and an optional solvent, the oil phase product is contacted with hydrogen peroxide to carry out an epoxidation reaction.

[0028] The method of the present invention mainly separates the liquid phase product into layers to obtain an oil phase product and an aqueous phase product, and contacts the oil phase product with hydrogen peroxide to carry out an epoxidation reaction. The process is simple and easy to operate, and the aqueous phase product does not enter the step of the epoxidation reaction, which reduces the load of subsequent separation and purification, is conducive to reducing the device size of the subsequent separation and purification unit, and reduces the land occupation and fixed investment. In addition, the method adopts nano-carbon materials to catalyze the oxidative dehydrogenation reaction of ethylbenzene, the reaction temperature is low, and the requirements on the structure and strength of the nano-carbon materials are greatly reduced, which is conducive to reducing the production cost of styrene oxide.

[0029] In a specific embodiment of the present invention, in step S1, the conditions of the oxidative dehydrogenation reaction include: the molar ratio of oxygen to ethylbenzene in the oxygen-containing atmosphere is (0.1-10):1, the temperature is 250-700°C, the pressure is 0.1-2.5MPa, and the time is 1-10h. Preferably, the molar ratio of oxygen to ethylbenzene in the oxygen-containing atmosphere is (0.2-5):1, the temperature is 300-500°C, the pressure is 0.1-2MPa, and the time is 2-8h.

[0030] According to the present invention, in step S1, the oxygen-containing atmosphere may contain inert gases such as nitrogen and helium in addition to oxygen. In a preferred embodiment, ethylbenzene is contacted with the nano-carbon material in air to carry out oxidative dehydrogenation reaction to save costs and simplify the operation.

[0031] According to the present invention, in step S1, the volume space velocity of ethylbenzene can vary within a wide range. In order to allow ethylbenzene and the nano-carbon 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 -1 When the volume space velocity of ethylbenzene is within the above range, the dehydrogenation reaction can be carried out more fully, which is beneficial to further improve the ethylbenzene conversion rate and the selectivity of styrene oxide.

[0032] In a specific embodiment of the present invention, the gas-liquid separation of the obtained oxidative dehydrogenation reaction product includes: exchanging heat between the mixture after the oxidative dehydrogenation reaction and the epoxidation product obtained by the epoxidation reaction to fully utilize the energy of the reaction system.

[0033] In a specific embodiment of the present invention, the gas phase product obtained by gas-liquid separation of the oxidative dehydrogenation reaction product is mainly a substance with a boiling point less than 0°C after the oxidative dehydrogenation reaction, which may include but is not limited to oxygen that has not reacted completely in the oxygen-containing atmosphere, inert gases such as nitrogen that may be contained in the oxygen-containing atmosphere, etc.

[0034] In a specific embodiment of the present invention, in step S1, the oil phase product contains ethylbenzene and styrene, and the water phase product contains water generated by oxidative dehydrogenation reaction; based on the total weight of the oil phase product, the content of ethylbenzene is 5-95% by weight, preferably 20-60% by weight. The present invention does not limit the method for stratifying the liquid phase product, for example, static sedimentation stratification can be adopted.

[0035] In a specific embodiment of the present invention, in step S2, the conditions for the epoxidation reaction may include: temperature of 10-70°C, pressure of 0.5-2.5MPa, and time of 1-18h; preferably, temperature of 20-60°C, pressure of 0.1-2MPa, and time of 2-12h.

[0036] In a specific embodiment of the present invention, in step S2, the molar ratio of the oil phase product to the amount of hydrogen peroxide can vary within a large range, for example, it can be 1:(0.5-2.5), preferably 1:(0.6-1), and the oil phase product is calculated as styrene; the weight ratio of the solvent to the amount of the oil phase product can also vary within a large range, for example, it can be 100:(1-500), preferably 100:(5-200).

[0037] According to the present invention, the oxidant is hydrogen peroxide; 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.

[0038] According to the present invention, 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 the 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 the 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.

[0039] The present invention does not limit the source of the nano-carbon material, and it can be purchased commercially or prepared by itself. In a specific embodiment, preferably, the nano-carbon material is a biomass carbon particle modified with ammonia nitrogen, and is prepared by a method comprising the following steps: in an ammonia atmosphere, the biomass carbon material is roasted at 800-1300°C, preferably 900-1000°C for 2-10h to obtain the nano-carbon material. Among them, the biomass carbon material is conventionally used by technicians in this field, for example, it can be selected from one or more of cellulose, hemicellulose, lignin, sucrose and starch.

[0040] According to the present invention, in order to prepare nano-carbon materials with good catalytic performance, the ammonia atmosphere also contains nitrogen as a balance gas, and the ammonia content can vary in a large range, for example, 0.1-10% by volume, preferably 0.5-5% by volume.

[0041] According to the present invention, 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.

[0042] According to the present invention, the method of the present invention can be a continuous operation, and 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 .

[0043] The present invention is further illustrated by the following examples, but the present invention is not limited thereto.

[0044] The reagents used in the examples and comparative examples are all commercially available chemically pure reagents.

[0045] The nanocarbon material is biomass carbon particles modified by ammonia and nitrogen. The specific preparation method is: calcining cellulose at 1100°C for 6 hours in a 2 volume % ammonia atmosphere, with the balance gas being nitrogen. The carbon content in the nanocarbon material is 93 weight percent, the nitrogen content is 2.1 weight percent, and the remainder is oxygen.

[0046] Titanium silicate molecular sieve (TS-1) is a calcined molecular sieve (TS-1) prepared by the method described in the prior art Zeolites, 1992, Vol. 12, pp. 943-950. The silicon-titanium molar ratio of titanium silicate molecular sieve (TS-1) is 27.

[0047] Example 1

[0048] S1. In an oxygen atmosphere, at an oxygen to ethylbenzene molar ratio of 0.5:1, 0.1 MPa, 500 °C, and an ethylbenzene volume space velocity of 20 h -1 Under the conditions of , ethylbenzene is first subjected to an oxidative dehydrogenation reaction for 6 hours through a bed layer using a nano-carbon material as a catalyst, and the mixture obtained after the oxidative dehydrogenation reaction is heat exchanged with the epoxidation reaction product to perform gas-liquid separation to obtain a gas phase product and a liquid phase product, and then the liquid phase product is allowed to stand for sedimentation and stratification to obtain an oil phase product and an aqueous phase product; wherein the content of ethylbenzene in the oil phase product is 46% by weight, and the balance is styrene;

[0049] S2, at a temperature of 60°C, a pressure of 0.5 MPa, and a total volume space velocity of 10 h -1 Under the condition of 1:1, the oil phase product was contacted with hydrogen peroxide, methanol and TS-1 for epoxidation reaction for 3 hours to obtain an epoxidation product. The molar ratio of the oil phase product (calculated as styrene) to hydrogen peroxide was 1:1, and the mass ratio of the oil phase product to methanol was 2:1. The results after 2 hours of reaction are shown in Table 1.

[0050] Example 2

[0051] S1. In air, the molar ratio of oxygen to ethylbenzene in the air is 0.2:1, 0.1MPa, 400℃, and the volumetric space velocity of ethylbenzene is 60h -1 Under the conditions of , ethylbenzene is first passed through a bed layer with nano-carbon material as catalyst for oxidative dehydrogenation reaction for 8 hours, and the obtained mixture after oxidative dehydrogenation reaction is subjected to gas-liquid separation after heat exchange with the epoxidation reaction product to obtain a gas phase product and a liquid phase product, and then the liquid phase product is allowed to stand for stratification to obtain an oil phase product and an aqueous phase product; wherein the content of ethylbenzene in the oil phase is 71% by weight, and the remainder is styrene;

[0052] S2, at a temperature of 40°C, a pressure of 2.5 MPa, and a total volume space velocity of 2 h -1Under the condition of 1:1, the oil phase product was contacted with hydrogen peroxide, methanol and TS-1 for epoxidation reaction for 3 hours to obtain an epoxidation product, wherein the molar ratio of the oil phase product (calculated as styrene) to hydrogen peroxide was 2:1, and the mass ratio of the oil phase product to methanol was 1:20.

[0053] Example 3

[0054] S1. In an oxygen atmosphere, at 0.1 MPa, 550°C, and a volume space velocity of 150 h -1 Under the condition of 1000 ℃ and 2000 ℃, ethylbenzene is first passed through a bed layer with nano-carbon material as catalyst for oxidative dehydrogenation reaction for 8 hours, and the obtained mixture after oxidative dehydrogenation reaction is subjected to gas-liquid separation after heat exchange with the epoxidation reaction product to obtain a gas phase product and a liquid phase product, and then the liquid phase product is allowed to stand for stratification to obtain an oil phase product and an aqueous phase product; wherein the content of ethylbenzene in the oil phase product is 52% by weight, and the balance is styrene;

[0055] S2, at a temperature of 50°C, a pressure of 1.5 MPa, and a total volumetric air velocity of 100 h -1 Under the condition of 1:1, the oil phase product was contacted with hydrogen peroxide, tert-butyl alcohol and TS-1 for epoxidation reaction for 2 hours to obtain an epoxidation product, wherein the molar ratio of the oil phase product (calculated as styrene) to hydrogen peroxide was 20:1, and the mass ratio of the oil phase product (calculated as styrene) to tert-butyl alcohol was 1:5.

[0056] Example 4

[0057] The same method as in Example 1 was used to prepare ethylene oxide, except that in step S1, the conditions for the oxidative dehydrogenation reaction included: a temperature of 750° C., a pressure of 0.1 MPa, and a time of 4 h. The ethylbenzene content was 58% by weight based on the total weight of the oil phase product.

[0058] Example 5

[0059] Epoxystyrene was prepared by the same method as in Example 1, except that in step S2, the epoxidation reaction temperature was 80° C., the pressure was 0.4 MPa, and the time was 3 h.

[0060] Example 6

[0061] Epoxystyrene was prepared by the same method as in Example 1, except that in step S2, the molar ratio of the oil phase product (in terms of styrene) to hydrogen peroxide was 1:1.1, and the mass ratio of the oil phase product (in terms of styrene) to methanol was 3:1.

[0062] Example 7

[0063] Epoxystyrene was prepared by the same method as in Example 1, except that the nano-carbon material used was different from that in Example 1. The nano-carbon material in this example was prepared by the following steps:

[0064] The cellulose was calcined at 800° C. for 6 h in an atmosphere of 0.4 vol % ammonia, with the balance gas being nitrogen. The carbon content in the nanocarbon material was 76 wt %, the nitrogen content was 1.8 wt %, and the remainder was oxygen.

[0065] Comparative Example 1

[0066] Epoxystyrene was prepared by the same method as in Example 1, except that no nano-carbon material was used in step S1.

[0067] Comparative Example 2

[0068] Epoxystyrene was prepared by the same method as in Example 1, except that catalyst TS-1 was not used in step S2.

[0069] Comparative Example 3

[0070] 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.

[0071] Comparative Example 4

[0072] Epoxystyrene was prepared by the same method as in Example 1, except that in step S1, the liquid product was not subjected to static sedimentation treatment, but was directly contacted with hydrogen peroxide, methanol and TS-1 for reaction.

[0073] Table 1

[0074] Ethylbenzene conversion rate (%) Epoxystyrene selectivity (%) Example 1 61 83 Example 2 45 76 Example 3 48 80 Example 4 52 72 Example 5 56 68 Example 6 50 64 Comparative Example 1 12 76 Comparative Example 2 56 5 Comparative Example 3 5 4 Comparative Example 4 40 58

[0075] 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.

[0076] 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, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0078] In addition, 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 oxidizing ethylbenzene, the method comprising: S1. In an oxygen-containing atmosphere, ethylbenzene is contacted with a nano-carbon material to carry out an oxidative dehydrogenation reaction, and the obtained oxidative dehydrogenation reaction product is subjected to gas-liquid separation to obtain a gas phase product and a liquid phase product, and then the liquid phase product is separated into layers to obtain an oil phase product and a water phase product; The oil phase product contains ethylbenzene and styrene; S2, in the presence of a titanium silicon catalyst and an optional solvent, contacting the oil phase product with hydrogen peroxide to carry out an epoxidation reaction; in step S2, the molar ratio of the oil phase product to the hydrogen peroxide is 1:(0.6-1), and the oil phase product is calculated in terms of styrene; The nano carbon material is prepared by a method comprising the following steps: roasting the biomass carbon material at 800-1300° C. for 2-10 hours in an ammonia atmosphere to obtain the nano carbon material; 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 of the oxidative dehydrogenation reaction include: temperature of 250-700°C, pressure of 0.1-2.5 MPa, time of 1-10 h, and a molar ratio of oxygen in the oxygen-containing atmosphere to ethylbenzene of (0.1-10):

1.

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

4. The method according to claim 1, wherein: In step S1, based on the total weight of the oil 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 oil phase product, the content of ethylbenzene is 20-60% by weight.

6. The method according to claim 1, wherein: In step S2, the conditions of the epoxidation reaction include: temperature of 10-70°C, pressure of 0.5-2.5 MPa, and time of 1-18 h.

7. The method according to claim 1, wherein: The weight ratio of the solvent to the oil phase product is 100:(1-500).

8. The method according to claim 7, wherein: The weight ratio of the solvent to the oil phase product is 100:(5-200).

9. The method according to claim 1, wherein: 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: The titanium silicon catalyst contains titanium silicon molecular sieve. 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; the ammonia atmosphere contains ammonia and nitrogen, and the ammonia content is 0.1-10% by volume.

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

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