CN116199647A - Method for producing epoxypropane - Google Patents

Abstract

The invention relates to a method for producing propylene oxide. The method comprises: (1) under anaerobic conditions, contacting propane and nano-carbon-based materials at 550-750° C. and 0-10 MPa for the first reaction to obtain the first Mixed product; (2) In the presence of a catalyst and an optional solvent, the first mixed product is contacted with hydrogen peroxide at 30-65° C. and 0.4-7 MPa to carry out the second reaction. The method of the invention can directly use propane and hydrogen peroxide as raw materials to produce propylene oxide, and the conversion rate of the raw materials and the selectivity of the target product are both high.

Description

A method for producing propylene oxide

technical field

The present invention relates to a method for producing propylene oxide.

Background technique

Propylene oxide, also known as propylene oxide (PO), is a bulk chemical raw material. It is the second largest organic chemical product in propylene derivatives after polypropylene. It ranks among the 50 chemicals with the largest output in the world. PO chemical properties are very lively, and it has a wide range of uses. It has a profound impact on the development of the chemical industry and the national economy. It is widely used in chemical industry, light industry, medicine, food, textile and other industries.

At present, the industrial production of propylene oxide mainly adopts the chlorohydrin method and the co-oxidation method, and the production capacity of these two methods accounts for more than 80% of the world's total production capacity. The chlorohydrin method was first used in production. This method uses chlorine gas, which is severely corroded. In order to increase the conversion rate, a large amount of water is added during the reaction process, so a large amount of chlorine-containing wastewater that pollutes the environment will be produced after the reaction, which does not meet the requirements of green chemistry and clean production. . Therefore, as people's requirements for environmental protection are increasing day by day, this process will eventually be eliminated. The co-oxidation method mainly uses ethylbenzene peroxide, tert-butyl hydroperoxide or cumene peroxide as an oxygen source to indirectly oxidize propylene to PO. The co-oxidation method overcomes the shortcomings of the chlorohydrin method such as polluting the environment and corroding equipment. It is a relatively cleaner production process than the chlorohydrin method, but co-produces a large amount of cheap by-products such as styrene or tert-butanol. Lengthy, large-scale construction investment, market supply and demand of by-products and economic factors are the main reasons restricting its development.

The method using hydrogen peroxide as the oxidant and heteroatom molecular sieves, especially titanium-silicon molecular sieves, as the catalyst can obtain higher propylene conversion and PO selectivity. The method is simple, the by-product is mainly water, the process is clean, and does not pollute the environment. It is a highly competitive PO production process that meets the requirements of contemporary green chemistry and atomic economy development concepts, and is considered to be a new green process for producing PO. is currently the most promising PO production method. However, its economy needs to be improved, and its technical maturity needs to be improved.

Contents of the invention

The object of the present invention is to provide a kind of method of producing propylene oxide, this method can be that raw material production obtains propylene oxide directly with propane and hydrogen peroxide.

In order to achieve the above object, the present invention provides a method for producing propylene oxide, the method comprising:

(1) Under oxygen-free conditions, contacting propane and nano-carbon-based materials at 550-750° C. and 0-10 MPa to perform a first reaction to obtain a first mixed product;

(2) In the presence of a catalyst and an optional solvent, the first mixed product is contacted with hydrogen peroxide at 30-65° C. and 0.4-7 MPa to carry out the second reaction.

Optionally, in step (1), the conditions of the first reaction include: a temperature of 600-700° C., a time of 1-5 MPa, and a volume space velocity of propane of 1-100 h ⁻¹ .

Optionally, in step (2), the molar ratio of the first mixed product to the amount of hydrogen peroxide is 1:(0.1-2), preferably 1:(0.2-1).

Optionally, in step (2), the conditions of the second reaction include: a temperature of 35-60° C. and a pressure of 0.5-6 MPa.

Optionally, the nano-carbon-based material is prepared by a method comprising the following steps: calcining multi-walled carbon nanotubes at 200-1000° C. for 1-24 h in an ammonia atmosphere with a concentration of 0.1-5 volume percent.

Optionally, the catalyst contains titanium-silicon molecular sieve, based on the total weight of the catalyst, the content of the titanium-silicon molecular sieve is 70-100% by weight.

Optionally, the silicon-titanium molar ratio of the titanium-silicon molecular sieve is 30-60, the total specific surface area is 250-600m ² /g, and the mesopore specific surface area is 30-100m ² /g.

Optionally, in step (2), the second reaction is carried out in the presence of a catalyst and a solvent; the weight ratio of the amount of the solvent to the catalyst is (10-1000):1, preferably (20-500) :1.

Optionally, the solvent is selected from inorganic solvents and/or organic solvents; the inorganic solvent is deionized water; the organic solvent is selected from methanol, ethanol, n-propanol, isopropanol, tert-butyl alcohol, isobutyl One or more of alcohol, acetone, butanone and acetonitrile, preferably methanol and/or deionized water.

Optionally, the total volume space velocity of the second reaction is 1-1000h ^-1 , preferably 5-500h ^-1 .

Through the above-mentioned technical scheme, in the method of the present invention, by coupling the first reaction and the second reaction, it is possible to directly use propane and hydrogen peroxide as raw materials to produce propylene oxide, and the first reaction obtains the first mixed product directly mixed with peroxide The second reaction is carried out by hydrogen contact, the preparation process is simple and easy, and the conversion rate of raw materials and the selectivity of epoxypropylene are high.

Other features and advantages of the present invention will be described in detail in the following detailed description.

Detailed ways

Specific embodiments of the present invention will be described in detail below. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

A first aspect of the present invention provides a method for producing propylene oxide, the method comprising:

(1) Under oxygen-free conditions, contacting propane and nano-carbon-based materials at 550-750° C. and 0-10 MPa to perform a first reaction to obtain a first mixed product;

(2) In the presence of a catalyst and an optional solvent, the first mixed product is contacted with hydrogen peroxide at 30-65° C. and 0.4-7 MPa to carry out the second reaction.

In the present invention, oxygen-free conditions means that the first reaction is performed in an atmosphere that does not contain oxygen, such as a nitrogen atmosphere, a helium atmosphere, a mixed atmosphere of nitrogen and helium, etc., or an atmosphere formed by propane alone. In an oxygen-free atmosphere, the molar ratio of gases other than propane to propane can be (0-10):1. The method of the present invention directly uses propane and hydrogen peroxide as raw materials to produce propylene oxide, the method is simple and easy, low in cost, and can produce propylene oxide with higher conversion rate and selectivity, and is especially suitable for using propane as an initial Raw material for industrial production of propylene oxide.

In a specific embodiment of the present invention, in step (1), the conditions of the first reaction include: the temperature is 600-700°C, the time is 1-5MPa, and the volume space velocity of propane is 1-100h ^-1 .

In a specific embodiment of the present invention, in step (2), the molar ratio of the first mixed product to the amount of hydrogen peroxide can vary within a relatively large range, for example, it can be 1:(0.1～ 2), preferably 1: (0.2-1).

In a specific embodiment of the present invention, in step (2), the conditions of the second reaction include: the temperature is 35-60°C, the pressure is 0.5-6MPa; preferably, the temperature is 40-50°C, the pressure It is 1~4MPa.

According to the present invention, the device used for the first reaction and the second reaction is not specifically limited, and the device used for the first reaction and the second reaction can be each independently a fixed bed reactor, a moving bed reactor, a microreactor or other Various types of reactors. In a preferred embodiment, the first reaction is carried out in a fixed-bed microreactor, and the second reaction is carried out in a slurry-bed reactor, and the conversion rate of raw materials and the reaction to propylene oxide can be further improved by adopting the above-mentioned method selective.

According to the present invention, the nano-carbon-based material is a nano-carbon-based material with good thermal stability. In a specific embodiment of the present invention, the nano-carbon-based material can be a commercially available product, or a modified product obtained after modifying a commercially-available product. Preferably, the nano-carbon-based material is modified by ammonia nitrogen activation. Sexual carbon nanotubes. In one embodiment, the modified carbon nanotubes are produced by a method comprising the following steps: the multi-walled carbon nanotubes are heated at 200-1000° C. Preferably calcination at 400-600°C for 1-24h. Preferably, the carbon nanotubes are carbon nanotubes. The ammonia atmosphere may also contain nitrogen and/or an inert gas, and the inert gas is well known to those skilled in the art, such as helium, argon and the like.

According to the present invention, the catalyst contains titanium-silicon molecular sieves, and titanium-silicon molecular sieves are well known to those skilled in the art, such as one or more molecular sieves with MFI structure, MOR structure, and BEA structure. The content of the titanium-silicon molecular sieve can vary within a relatively large range, for example, based on the total weight of the catalyst, the content of the titanium-silicon molecular sieve is 70-100% by weight, preferably 40-55% by weight, and the silicon-titanium molar ratio of the titanium-silicon molecular sieve is also It can be changed within a large range, for example, it can be 15-60, preferably 20-55. The total specific surface area of the titanium-silicon molecular sieve is 250-600m ² /g, and the mesopore specific surface area is 25-100m ² /g. The conversion rate of raw materials and the selectivity of propylene oxide in the method of the present invention can be further improved by using the above-mentioned titanium-silicon molecular sieve. Among them, titanium-silicon molecular sieves are well known to those skilled in the art, and can be obtained through self-synthesis or commercial purchase, and the specific preparation methods will not be repeated here.

According to the present invention, in step (2), carry out described second reaction in the presence of catalyst and solvent; Solvent is selected from inorganic solvent and/or organic solvent; Inorganic solvent can be deionized water; Organic solvent can be selected from alcohol, ketone and one or more of nitriles, such as one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone and acetonitrile, preferably methanol and/or deionized water. The weight ratio of the amount of the solvent to the catalyst can vary within a wide range, for example, it can be (10-1000):1, preferably (20-500):1.

In a specific embodiment of the present invention, the total space velocity of the second reaction may be 1-1000h ^-1 , preferably 5-500h ^-1 .

The present invention will be further illustrated below by way of examples, but the present invention is not limited thereto. The reagents used in the examples are commercially available chemically pure reagents.

The nano-carbon material is a multi-walled carbon nanotube modified by ammonia nitrogen (CNT is activated and modified). The specific production is as follows: the multi-walled carbon nanotubes are calcined at 600° C. for 4 hours in an atmosphere of 1 volume percent ammonia (the balance is nitrogen) using a tube furnace.

Titanium-silicon molecular sieve (TS-1) is the (TS-1) molecular sieve sample produced by the method described in the prior art Zeolites, 1992, Vol.12 page 943-950, and its silicon-titanium molar ratio is 24, and the total The specific surface area is 402m ² /g, and the mesopore specific surface area is 27m ² /g.

Adopt gas chromatography to analyze the content of each component in the reaction product that obtains, adopt following formula to calculate the conversion ratio of propane and the selectivity of propylene oxide respectively on this basis:

Propane conversion rate = [(molar amount of propane added - molar amount of unreacted propane)/molar amount of propane added] × 100%;

Propylene oxide selectivity=[the molar amount of propylene oxide produced by the reaction/(the molar amount of added propane-the molar amount of unreacted propane)]×100%.

Example 1

The process of producing propylene oxide is as follows:

(1) Under the conditions of nitrogen atmosphere, 0.1MPa, 600°C and propane volumetric space velocity of 100h ^-1 , propane (the molar ratio of nitrogen and propane is 1:1) is passed through the catalyst bed with nano-carbon-based materials. The fixed-bed microreactor of layer carries out first reaction, obtains the first mixed product;

(2) will make the first mixed product and hydrogen peroxide, solvent methanol and catalyzer be 1:1 according to the mol ratio of the first mixed product and hydrogen peroxide in the slurry bed reactor, the weight ratio of solvent methanol and catalyzer is 50, the second reaction was carried out by contacting at a temperature of 60°C, a pressure of 0.5 MPa, and a total volume space velocity of 500 h ^-1 . The reaction mixture obtained after the completion of the second reaction was analyzed by gas chromatography, and the conversion rate of propane and the selectivity of propylene oxide were calculated. The 2 hour reaction results are listed in Table 1.

Example 2

Propylene oxide is produced in the same manner as in Example 1, except that in step (1), at a temperature of 550° C., the volumetric space velocity of propane is 5 h ⁻¹ ;

In step (2), the molar ratio of the first mixed product to hydrogen peroxide is 2:1, the weight ratio of the solvent methanol to the catalyst is 20, the reaction temperature is 40°C, the pressure is 2.5MPa, and the total volume space velocity is 200h ^-1 .

Example 3

Adopt the method identical with embodiment 1 to produce propylene oxide, difference is only, in step (1), propane volume space velocity is 25h ^-1 ;

In step (2), the molar ratio of the first mixed product to the hydrogen peroxide solution (calculated as hydrogen peroxide) is 10:1, the weight ratio of the solvent methanol to the catalyst is 40, the temperature is 50°C, and the pressure is 1.5MPa, The total volumetric space velocity is 100h ^-1 .

Example 4

Propylene oxide was produced by the same method as in Example 1, except that in step (1), the pressure was 6 MPa, the temperature was 550°C, and the volume space velocity of propane was 8h ^-1 .

Example 5

Adopt the method identical with embodiment 1 to produce propylene oxide, difference is only, in step (2), the temperature of second reaction is 30, and pressure is 0.45MPa, and the first mixed product and hydrogen peroxide solution (with peroxide) The molar ratio of hydrogen peroxide) is 1:1.2.

Example 6

Propylene oxide is produced in the same manner as in Example 1, the only difference being that the nano-carbon-based material used in step (1) is different, and the nano-carbon-based material used in this embodiment is to combine multi-walled carbon nanotubes at a concentration of It is prepared by firing at 800° C. for 3 hours under an atmosphere of 3 volume percent ammonia gas.

Comparative example 1

Propylene oxide was produced by the same method as in Example 1, except that no nano-carbon-based material was used.

Comparative example 2

Propylene oxide was produced in the same manner as in Example 1, except that no catalyst was used.

Comparative example 3

Propylene oxide was produced by the same method as in Example 1, except that nano-carbon-based materials and catalysts were not used.

Comparative example 4

Propylene oxide was produced by the same method as in Example 1, except that the reaction temperature in step (1) was 400°C.

Table 1

serial number Propane Conversion (%) Propylene oxide selectivity (%) Example 1 58 94 Example 2 31 92 Example 3 35 89 Example 4 41 83 Example 5 47 87 Example 6 39 84 Comparative example 1 3 82 Comparative example 2 51 2 Comparative example 3 1 3 Comparative example 4 14 52

From the results of comparative examples and examples, it can be seen that the present invention can directly produce propylene oxide with propane and hydrogen peroxide, the method is simple and easy, low in cost, and has high propane conversion rate and propylene oxide selectivity.

The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solutions of the present invention. These simple modifications All belong to the protection scope of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable way if there is no contradiction. The combination method will not be described separately.

In addition, various combinations of different embodiments of the present invention can also be combined arbitrarily, as long as they do not violate the idea of the present invention, they should also be regarded as the disclosed content of the present invention.

Claims (10)

1. A method of producing propylene oxide, the method comprising:

(1) Under the anaerobic condition, enabling propane to contact with the nano carbon-based material at 550-750 ℃ and 0-10 MPa to perform a first reaction to obtain a first mixed product;

(2) The first mixed product is contacted with hydrogen peroxide at 30-65 ℃ and 0.4-7 MPa in the presence of a catalyst and an optional solvent to carry out a second reaction.

2. The method of claim 1, wherein in step (1), the conditions of the first reaction comprise: the temperature is 600-700 ℃, the time is 1-5 MPa, and the volume airspeed of propane is 1-100 h ^-1 。

3. The method of claim 1, wherein in step (2), the molar ratio of the first mixed product to the amount of hydrogen peroxide is 1: (0.1 to 2), preferably 1: (0.2-1).

4. The method of claim 1, wherein in step (2), the conditions of the second reaction comprise: the temperature is 35-60 ℃ and the pressure is 0.5-6 MPa.

5. The method of claim 1, wherein the nanocarbon-based material is prepared by a method comprising: roasting the multi-wall carbon nano tube for 1-24h at 200-1000 ℃ in ammonia gas atmosphere with the concentration of 0.1-5 vol%.

6. The process of claim 1 or 5, wherein the catalyst comprises titanium silicalite in an amount of 70-100 wt.%, based on the total weight of the catalyst.

7. The method according to claim 6, wherein the titanium silicalite molecular sieve has a molar ratio of silicon to titanium of 30-60 and a total specific surface area of 250-600m ² Per gram, mesoporous specific surface area of 30-100m ² /g。

8. The process of claim 1, wherein in step (2), the second reaction is performed in the presence of a catalyst and a solvent; the weight ratio of the solvent to the catalyst is (10-1000): 1, preferably (20 to 500): 1.

9. the method according to claim 8, wherein the solvent is selected from inorganic solvents and/or organic solvents; the inorganic solvent is deionized water; the organic solvent is selected from one or more of methanol, ethanol, n-propanol, isopropanol, tert-butanol, isobutanol, acetone, butanone and acetonitrile, preferably methanol and/or deionized water.

10. The process according to claim 1, wherein the total volume space velocity of the second reaction is from 1 to 1000h ^-1 Preferably 5 to 500h ^-1 。