CN113105300B

CN113105300B - Method for producing ethylene by homogeneous phase photocatalysis of ethanol

Info

Publication number: CN113105300B
Application number: CN202110328482.3A
Authority: CN
Inventors: 严克友; 唐慧玲; 李明洁; 吴丽琴; 周彪
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2021-03-26
Filing date: 2021-03-26
Publication date: 2022-05-24
Anticipated expiration: 2041-03-26
Also published as: CN113105300A

Abstract

The invention discloses a method for producing ethylene by ethanol through homogeneous phase photocatalysis, which comprises the following steps: adding the catalyst into ethanol for dissolving, and carrying out catalytic reaction under the illumination in a closed environment to obtain the ethylene. After the catalytic reaction is finished, the activity of the catalyst is recovered after air or oxygen is introduced into the solution; the catalytic reaction can be performed by irradiation with light again. The gas-phase product ethylene obtained by the catalytic reaction has high selectivity and high reaction rate. And the catalyst regeneration cost is low. The catalyst can restore the activity by being put into the air for oxidation, and the photocatalytic reaction is continuously carried out to produce the ethylene.

Description

Method for producing ethylene by homogeneous phase photocatalysis of ethanol

Technical Field

The invention belongs to the field of ethylene preparation, and particularly relates to a method for producing ethylene by ethanol through homogeneous phase photocatalysis.

Background

Ethylene is one of the chemical products with the largest yield in the world, the ethylene industry is the core of the petrochemical industry, and the ethylene product accounts for more than 75 percent of petrochemical products and occupies an important position in national economy. Ethylene production has been used worldwide as one of the important indicators for the development of petrochemical in one country. One of the most basic raw materials in petrochemical industry. In the aspect of synthetic materials, the method is widely used for producing polyethylene, vinyl chloride and polyvinyl chloride, ethylbenzene, styrene and polystyrene, ethylene propylene rubber and the like; in the aspect of organic synthesis, the method is widely used for synthesizing ethanol, ethylene oxide, ethylene glycol, acetaldehyde, acetic acid, propionaldehyde, propionic acid and derivatives thereof and other basic organic synthesis raw materials; halogenated to prepare chloroethylene, chloroethane and bromoethane; alpha-olefin can be prepared by oligomerization, and then higher alcohol, alkylbenzene, etc. can be produced. Meanwhile, the ethylene can also be used as environment-friendly ripening gas for fruits such as navel oranges, mandarins, bananas and the like. The ethylene used in industry is separated from the gases produced in petroleum refineries and petrochemical plants. The oil resources are seriously depended on, and with the gradual depletion of the resources, the development of new renewable energy source alternative energy sources is urgent.

There are many reports of ethylene production by ethanol dehydration, mainly activated alumina and molecular sieves. But the reaction temperature of the alumina system is high (370-470 ℃), and the investment and the energy consumption of the device are high. Molecular sieve catalysts for ethylene production by ethanol dehydration have been reported to be: the catalyst comprises a 4A molecular sieve, a SAPO-34 molecular sieve, H-mordenite, a V-MCM-41, an H-NaZSM-5 molecular sieve, H-NaZSM-5 with different silica-alumina ratios, an HY type molecular sieve, an H beta molecular sieve and the like, wherein the ZSM-5 molecular sieve catalyst has advantages in the aspect of catalytic dehydration performance due to oleophylic hydrophobicity. However, the molecular sieve catalyst has strong acidity, is easy to generate carbon deposition and cover the active sites of the catalyst to cause the inactivation of the catalyst, and the catalyst needs to be regenerated at intervals. Chinese patent CN103157503A discloses a catalyst for preparing ethylene molecular sieve by ethanol dehydration, the regeneration method provided in the patent technology can be completely regenerated only by introducing air or oxygen and raising the temperature to 500 ℃, the regeneration temperature is higher, the device investment is higher, the molecular sieve crystal lattice can be damaged by long-term high-temperature regeneration, thereby forming the skeleton defect, and simultaneously the high-temperature carbon burning easily causes the sintering of the active components on the surface of the catalyst to cause the catalyst not to be regenerated and recover the initial activity.

In summary, the conventional methods have the disadvantages of high energy consumption, easy deactivation of the catalyst, high catalyst regeneration cost, and the like.

Disclosure of Invention

In order to solve the problems, the invention provides a method for preparing ethylene by ethanol dehydration, which has low reaction temperature, easy regeneration of a catalyst and low cost.

Specifically, the invention provides a method for producing ethylene by ethanol through homogeneous phase photocatalysis;

the purpose of the invention is realized by the following technical scheme:

a method for producing ethylene by homogeneous phase photocatalysis ethanol comprises the following steps:

adding the catalyst into ethanol for dissolving, and carrying out catalytic reaction under the illumination in a closed environment to obtain the ethylene.

Preferably, the catalyst is copper chloride or copper chloride dihydrate. All purchased commercially and used directly without post-treatment.

Preferably, the solution before the catalytic reaction is a green transparent solution; the solution was colorless and transparent after the catalytic reaction was stopped.

Preferably, the closed environment is an inert atmosphere or an air atmosphere; the ethanol is absolute ethanol.

Preferably, the concentration of the catalyst is 1-100 mM; further preferably, the concentration of the catalyst is 0.01M.

Preferably, the wavelength range of the light includes any wavelength of 300-700 nm. Further preferably, the illumination is a xenon lamp with a filter, wherein the filter is a 420nm filter, an AM1.5G filter, a 300-700nm filter or a 365nm single-beam filter. More preferably, the power of the xenon lamp is 100-500W.

Preferably, the temperature of the catalytic reaction is room temperature.

Preferably, after the catalytic reaction is finished, the activity of the catalyst is recovered after air or oxygen is introduced into the solution; the catalytic reaction is continued by irradiating light again.

Preferably, the solution after the catalytic reaction is oxidized by being put into the air, and the catalyst can recover the activity.

Compared with the prior art, the invention has the following advantages and beneficial effects:

the method has the advantages of cheap and easily obtained catalyst, high selectivity of gas product ethylene, low reaction temperature, simple reaction device and capability of regenerating and reusing the catalyst by a simple method.

Drawings

FIG. 1 is a graph of the reaction gas products over time as measured by gas chromatography for examples 1-8;

FIG. 2 is a graph showing the color change of the solution in example 9;

FIG. 3 is a product graph of the first and second catalysis in example 9;

FIG. 4 is a graph showing the detection of the kind and content of a reaction gas product by gas chromatography in example 4 and example 10.

Detailed Description

The technical solutions in the present invention are described below clearly and completely by way of examples, and it is obvious that the described implementation examples are only a part of examples of the present invention, but not all examples. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

0.0068g of commercial CuCl is weighed out₂·2H₂And O, putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. The closed reaction flask with the air atmosphere is placed on the upper part of a 300W xenon lamp with a 420nm filter, and the xenon lamp is turned on to start the reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 2

0.0068g of commercial CuCl is weighed out₂·2H₂O, putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with a 420nm filter, and the xenon lamp is turned on to start reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 3

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. And placing the sealed reaction bottle on the upper part of a 300W xenon lamp with an optical filter of more than 420nm, and turning on the xenon lamp to start reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 4

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with an AM1.5G filter, and the xenon lamp is turned on to start the reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 5

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 8mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with an AM1.5G filter, and the xenon lamp is turned on to start the reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 6

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with a filter with the wavelength of 300-700nm, and the xenon lamp is turned on to start the reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 7

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with a 365nm single-beam filter, and the xenon lamp is turned on to start reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

Example 8

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. Placing the closed reaction bottle in the beltThe xenon lamp with the filter of 700 and 2500nm was turned on at the upper part of the 300W xenon lamp to start the reaction. The reaction gas products were detected by gas chromatography. The experimental results are shown in FIG. 1.

from the results of fig. 1, the results of example 1 and example 2 show that the yield of the reaction is higher for the same catalyst under nitrogen than for air; examples 2 and 3 show that the catalyst is better without water;

the results of examples 4 and 5 show that increasing the volume of ethanol does not substantially affect the reaction rate and yield. The variables of examples 3, 4, 6, 7 and 8 are different filters, and the results show that the filters using AM1.5G, 365nm and 300-2500 nm are better than those using AM1.5G, and are worse than those using AM1.5G, 365nm and 300-2500 nm, and the filters using AM1.5G, 365nm and 300-2500 nm are basically ineffective.

Example 9

0.0054g of CuCl₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. Nitrogen was introduced to make it inert. And placing the sealed reaction bottle on the upper part of a 300W xenon lamp with an AM1.5G optical filter, and turning on the xenon lamp to start reaction. The reaction gas products were detected by gas chromatography. The color of the solution becomes lighter as the reaction proceeds during the reaction. And the reaction was substantially stopped when the solution became colorless and transparent. The flask was then vented to air and after a period of time the solution gradually returned to green (as in FIG. 2) and the photocatalytic reaction described above using this solution continued to produce ethylene gas (as in FIG. 3).

Example 10

0.0054g of commercial CuCl was weighed₂And putting the mixture into a 50mL photocatalytic reaction bottle, and adding 4mL of absolute ethyl alcohol into the bottle to completely dissolve the mixture to obtain a green transparent solution. The sealed reaction bottle is placed on the upper part of a 300W xenon lamp with an AM1.5G filter, and the xenon lamp is turned on to start the reaction. The reaction gas products were detected by gas chromatography. The results are shown in FIG. 4 (7 hours in air).

The catalytic reaction results of the above catalysts show that the selectivity of ethylene in the gaseous product under nitrogen environment is as high as 98% (fig. 4). The reaction rate is high, and can reach 175umol/g in 1 hour and 196umol/g in 4 hours (as shown in an example 4 in figure 1). Wherein "g" in umol/g means the mass of copper chloride.

The results show that the catalyst is cheap and easy to obtain, the selectivity of the gaseous product ethylene is high, the reaction temperature is low, the reaction device is simple, and the catalyst can be regenerated and reused by a simple method.

The foregoing description has disclosed fully preferred embodiments of the present invention. It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the appended claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.

Claims

1. A method for producing ethylene by homogeneous phase photocatalysis ethanol is characterized by comprising the following steps:

adding a catalyst into ethanol for dissolving, and carrying out catalytic reaction under illumination in a closed environment to obtain ethylene;

the catalyst is copper chloride or copper chloride dihydrate;

the concentration of the catalyst is 1-100 mM;

the wavelength range of the illumination comprises any wavelength of 300-365 nm;

the closed environment is an inert atmosphere.

2. The homogeneous photocatalytic ethanol ethylene production method according to claim 1, wherein the solution before the catalytic reaction is a green transparent solution; the solution was colorless and transparent after the catalytic reaction was stopped.

3. The homogeneous photocatalytic ethanol ethylene production method according to claim 1, wherein the ethanol is absolute ethanol.

4. The method for producing ethylene by using ethanol through homogeneous photocatalysis as claimed in claim 1, wherein the illumination is a xenon lamp with a filter, wherein the xenon lamp is an AM1.5G filter, a 300-700nm filter or a 365nm single-beam filter.

5. The homogeneous photocatalytic ethanol ethylene production method according to claim 1, wherein the temperature of the catalytic reaction is room temperature.

6. The homogeneous photocatalytic method for producing ethylene from ethanol according to claim 1, wherein after the catalytic reaction is finished, the activity of the catalyst is recovered after air or oxygen is introduced into the solution; the catalytic reaction is continued by re-illumination.

7. The homogeneous photocatalytic method for producing ethylene from ethanol as claimed in claim 1, wherein the solution after catalytic reaction is oxidized by putting into air, and the activity of the catalyst can be recovered.