Method for synthesizing vinyl chloride by photocatalytic hydrochlorination of acetylene

Abstract

The application discloses a method for synthesizing chloroethylene by photocatalytic acetylene hydrochlorination, and relates to the technical field of organic synthesis. The method comprises the following steps: introducing acetylene and argon into hydrogen chloride gas or a water solution containing chloride ions, and reacting under the irradiation of a light source in the presence of a photocatalyst to obtain chloroethylene. The method for synthesizing chloroethylene by photocatalytic acetylene hydrochlorination has a pioneering significance, and chloroethylene can be prepared at room temperature under the irradiation of a light source, and there is chloroethylene product in the gaseous product.

Description

Technical Field

[0001] This invention relates to the field of organic synthesis technology, and specifically to a method for synthesizing vinyl chloride by photocatalytic hydrochlorination of acetylene. Background Technology

[0002] Polyvinyl chloride (PVC), as a high-performance plastic, is in extremely high demand and is one of the world's top five engineering plastics. PVC is typically produced by polymerizing vinyl chloride (VCM) monomers. Currently, the main industrial production process for synthesizing vinyl chloride uses the acetylene hydrochlorination method. However, this method involves activated carbon supported on mercuric chloride as a catalyst. The addition reaction between acetylene and hydrogen chloride to produce vinyl chloride releases a large amount of heat. If the catalyst bed is not cooled in time, the temperature will quickly exceed 200°C, causing mercury to be reduced and sublimated into the atmosphere, resulting in serious environmental pollution. In actual industrial practice, water is used to cool the reaction and maintain the temperature at 100–120°C, which wastes a considerable amount of energy. Furthermore, because 3–5% of the reaction gas contains excess hydrogen chloride to ensure catalyst activity, subsequent steps such as alkaline washing and water washing are required, which not only wastes water but also potentially releases mercury into water bodies.

[0003] With increasing attention to environmental issues, research on mercury-free catalysts has been progressing steadily in recent years. Researchers have focused on the thermocatalytic reactions of acetylene hydrochlorination using precious metals such as gold and ruthenium, as well as other non-precious metal or non-metal catalysts. However, these reactions still require significant energy consumption. Currently, the main energy supply comes from fossil fuels, such as oil and coal. The energy storage of these fossil fuels is limited, and their extensive use results in substantial CO2 emissions. Summary of the Invention

[0004] To address the shortcomings of the aforementioned background technologies, primarily targeting environmental issues such as mercury emissions and energy consumption in current industry, this invention provides a groundbreaking method for the photocatalytic hydrochlorination of acetylene to produce vinyl chloride. Vinyl chloride can be prepared at room temperature under light source irradiation, and vinyl chloride is present in the gaseous products. This invention offers a green and environmentally friendly method for preparing vinyl chloride, characterized by a simple process, mild reaction conditions, stable catalyst performance, high reactivity, simple equipment, and low-cost raw materials. This method meets the development needs of green chemical engineering and has significant strategic importance. Furthermore, this type of nano-semiconductor photocatalyst exhibits extremely high stability, can be recycled multiple times while maintaining excellent activity, making this method promising for industrial applications.

[0005] To achieve the above objectives, the present invention provides a method for photocatalytic hydrochlorination of acetylene to synthesize vinyl chloride, comprising the following steps:

[0006] Acetylene and argon are passed into hydrogen chloride gas or an aqueous solution containing chloride ions, and the reaction is carried out under the irradiation of a light source in the presence of a photocatalyst to obtain vinyl chloride.

[0007] Preferably, the photocatalyst comprises a nano-semiconductor photocatalyst and a metal or metal oxide supported on the nano-semiconductor photocatalyst.

[0008] Preferably, the nano-semiconductor photocatalyst comprises g-C3N4, BiVO4, CdS, MoS2, Bi2WO6, BiOCl, or heterojunction composite materials thereof;

[0009] The metal elements in the metal or metal oxide include Pd, Pt, Ni, Ag, Cu, Co, Fe, Ru, or binary or ternary alloys thereof.

[0010] Preferably, the heterojunction composite material includes BiOCl-C3N4, BiOCl / BiVO4, Bi / BiOCl, Cu2O / BiOCl, Au / BiOCl, Au / BiOCl-C3N4 or Bi2MoO6-BiOCl.

[0011] Preferably, the nano-semiconductor photocatalyst is loaded with 0.1% to 5% metal or metal oxide by mass percentage.

[0012] Preferably, when acetylene and argon are introduced into hydrogen chloride gas, the amount of photocatalyst added is 2 to 100 mg; the ratio of acetylene to hydrogen chloride gas is 1:1 to 1.2; and the ratio of argon gas to the total amount of acetylene and hydrogen chloride gas is 0 to 50:100.

[0013] Preferably, when acetylene and argon are introduced into an aqueous solution containing chloride ions, a photocatalyst is added to the aqueous solution containing chloride ions, wherein the amount of photocatalyst added is 2 to 100 mg; the volume of the aqueous solution containing chloride ions added is 5 to 20 mL, wherein the amount of chloride salt added to the aqueous solution containing chloride ions is 0.01 to 1 g.

[0014] Preferably, the aqueous solution containing chloride ions further includes an acid solution with a concentration of 0.01 to 6 mol / L.

[0015] Preferably, a photocatalytic reactor is used in the reaction process.

[0016] Preferably, the light source includes a xenon lamp, a mercury lamp, a 420nm LED lamp, a 475nm LED lamp, or a 550nm LED lamp; the illuminance is 10–3000 mW / cm². 2 The illumination time is 0.5 to 50 hours.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention provides a photocatalytic method for the hydrochlorination of acetylene to synthesize vinyl chloride. In this method, acetylene is hydrochlorinated to prepare vinyl chloride under ambient temperature and pressure with light source irradiation. The reaction system is safe and simple, and the gaseous product is vinyl chloride. Light can serve as a direct energy source, reducing the use of heat and electricity, lowering energy consumption, and saving production costs. This invention uses only hydrogen chloride gas or a chloride ion-containing solution, eliminating mercury pollution and the potential hazards associated with the use of mercury catalysts in current industrial processes, thus meeting the requirements of green chemistry. The catalyst preparation process used in this invention is simple, with high repeatability and stability. Attached Figure Description

[0019] Figure 1 This is the mass spectrum of the product vinyl chloride.

[0020] Figure 2 The image shows the gas chromatogram of the product vinyl chloride. Detailed Implementation

[0021] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0022] The purpose of this invention is to reduce structural defects and the content of coordinated water molecules in Prussian blue-based cathode materials, and to solve the complex sodium ion storage phase transition behavior and severe Jan Taylor effect during charging and discharging. A high-performance photocatalytic method for the hydrochlorination of acetylene to synthesize vinyl chloride is proposed.

[0023] This invention provides a method for the photocatalytic hydrochlorination of acetylene to synthesize vinyl chloride.

[0024] A method for synthesizing vinyl chloride by photocatalytic hydrochlorination of acetylene, characterized by comprising the following steps:

[0025] Acetylene is introduced into a container containing hydrogen chloride gas or an aqueous solution containing chloride ions, and the reaction is carried out under the irradiation of a light source in the presence of a photocatalyst to obtain vinyl chloride.

[0026] The synthesis route is as follows:

[0027]

[0028] According to the present invention, the photocatalyst comprises a nano-semiconductor photocatalyst and a metal or metal oxide supported on the nano-semiconductor photocatalyst. The supported metal or metal oxide modulates the separation efficiency of photogenerated electrons and holes, thereby increasing the product yield.

[0029] The photocatalyst is loaded with 0.1% to 5% metal or metal oxide by mass percentage.

[0030] Specifically, the nano-semiconductor photocatalyst includes g-C3N4, BiVO4, CdS, MoS2, Bi2WO6, BiOCl, or heterojunction composite materials thereof;

[0031] The metal elements in the metal or metal oxide include Pd, Pt, Ni, Ag, Cu, Co, Fe, Ru, or binary or ternary alloys thereof.

[0032] Furthermore, the heterojunction composite material includes BiOCl-C3N4, BiOCl / BiVO4, Bi / BiOCl, Cu2O / BiOCl, Au / BiOCl, Au / BiOCl-C3N4, or Bi2MoO6-BiOCl.

[0033] According to the present invention, when acetylene is introduced into a container containing hydrogen chloride gas, argon gas is also introduced into the hydrogen chloride gas; the amount of photocatalyst added is 2 to 100 mg; the ratio of acetylene to hydrogen chloride gas is 1:1 to 1.2, and the ratio of argon gas to the total amount of acetylene and hydrogen chloride gas is 0 to 50:100; the ratio here refers to argon gas:(acetylene + hydrogen chloride gas).

[0034] In one embodiment, a certain amount of nano-semiconductor photocatalyst is added to a photocatalytic reactor, and acetylene, hydrogen chloride, and argon gas are introduced into the reactor in a certain proportion. The reaction system temperature is maintained at room temperature using a constant temperature water bath, and the catalyst is continuously irradiated by a light source. After the reaction is completed, the product is qualitatively and quantitatively analyzed using a gas chromatograph. The product vinyl chloride is present in the gas after the reaction.

[0035] According to the present invention, when acetylene is introduced into a container containing an aqueous solution of chloride ions, a photocatalyst is added to the aqueous solution containing chloride ions, wherein the amount of photocatalyst added is 2 to 100 mg; the volume of the aqueous solution containing chloride ions added is 5 to 20 mL, wherein the amount of chloride salt added to the aqueous solution containing chloride ions is 0.01 to 1 g;

[0036] In this process, acetylene is introduced into a container containing an aqueous solution of chloride ions. After other gases in the container are removed, gases including oxygen, nitrogen, carbon monoxide, or carbon dioxide are introduced.

[0037] The aqueous solution containing chloride ions also includes an acid solution with a concentration of 0.01–6 mol / L.

[0038] In one embodiment, a certain amount of nano-semiconductor photocatalyst is added to an aqueous solution containing chloride ions, and the mixture is ultrasonicated and stirred to form a suspension. The suspension is then transferred to a photocatalytic reactor, and acetylene and argon gas are introduced into it in a certain proportion. Under continuous stirring and inert gas protection, the reaction system temperature is maintained at room temperature using a constant temperature water bath, and a light source is turned on to continuously irradiate the reaction system. After the reaction is completed, the product is qualitatively and quantitatively analyzed using a gas chromatograph. The product vinyl chloride is present in the gas after the reaction.

[0039] The nano-semiconductor photocatalyst is added to an aqueous solution containing chloride ions, wherein the amount of nano-semiconductor photocatalyst added is 2-100 mg; the aqueous solution containing chloride ions is an aqueous solution of salts such as KCl and NaCl, or seawater, wherein the amount of chloride salt added is 0.01-50 g; the volume of the aqueous solution is 5-50 mL; an appropriate amount of acid, such as hydrochloric acid, sulfuric acid, phosphoric acid, perchloric acid, etc., may also be added to the chloride-containing aqueous solution, and the concentration of the added acid is 0.01-6 mol / L; adding a certain amount of acid will increase the yield.

[0040] The stirring and ultrasonic dispersion time is 5–30 min; the room temperature is 25–25 °C, and the reaction temperature is not limited to room temperature; the stirring rate is 100–1500 r / min.

[0041] It should be noted that the introduction of acetylene gas into the system removes other gases present in the system. Furthermore, other inert gases such as oxygen, nitrogen, carbon monoxide, and carbon dioxide can be added during photocatalysis without affecting the formation of vinyl chloride, and will instead increase the yield of vinyl chloride.

[0042] The container is a photocatalytic reactor.

[0043] The light source includes, but is not limited to, xenon lamps, mercury lamps, 420nm LED lamps, 475nm LED lamps, and 550nm LED lamps; the illuminance is 10–3000 mW / cm². 2 The illumination time is 0.5 to 50 hours.

[0044] This invention specifically describes the photocatalytic hydrochlorination of acetylene to vinyl chloride at room temperature and pressure, utilizing a gas-solid two-phase or gas-liquid-solid three-phase reaction in the presence of a photocatalyst. Acetylene is hydrochlorinated to vinyl chloride under light source irradiation and at room temperature and pressure. The reaction system is safe and simple, and the gaseous product is vinyl chloride. Light can serve as a direct energy source, reducing the use of heat and electricity, lowering energy consumption, and saving production costs. Only hydrogen chloride gas or a chloride ion-containing solution is needed, eliminating mercury pollution and the potential dangers associated with the use of mercury catalysts in current industrial processes, thus meeting the requirements of green chemistry.

[0045] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are merely illustrative and explanatory of the present invention, and should not be construed as limiting the scope of protection of the present invention. All technologies implemented based on the above content of the present invention are covered within the scope of protection intended by the present invention.

[0046] It should be noted that, unless otherwise specified, the experimental methods used in this invention are all conventional methods; and the reagents and materials used, unless otherwise specified, are all commercially available.

[0047] Example 1

[0048] (1) Add 0.486 g of bismuth nitrate pentahydrate and 0.0745 g of potassium chloride to 15 mL of deionized water, stir for 60 minutes, then transfer to a 25 mL reactor. Heat at a rate of 5 °C / min and maintain at 160 °C for 24 hours. After washing three times with deionized water by centrifugation, place in a vacuum drying oven at 60 °C for 12 hours. After drying and grinding, BiOCl solid powder is obtained.

[0049] (2) Add 5g of melamine to a round crucible and cover it. Heat the crucible at a rate of 5℃ / min and maintain it at 520℃ for 4 hours. Grind the resulting product into powder. Then put 1g of powder into a square crucible and heat it at a rate of 2℃ / min. Maintain it at 520℃ for 6 hours to obtain powdered g-C3N4.

[0050] (3) The obtained BiOCl and g-C3N4 were mixed in water at a certain mass ratio, sonicated for 30 minutes and stirred for 1 hour. After centrifugation and washing three times with deionized water, the mixed solution was dried in an oven for 24 hours to obtain BiOCl-C3N4.

[0051] (4) Take 5 mg of the prepared BiOCl-C3N4 and add it to 30 mL of aqueous solution containing 0.1 M hydrochloric acid. Sonicate and stir to ensure thorough mixing and form a suspension. Transfer the suspension to a photocatalytic reactor. Introduce high-purity acetylene gas into the solution for approximately 15 minutes, vent other gases, and add a certain amount of oxygen. Under continuous stirring, maintain the reaction system temperature at room temperature using a constant-temperature water bath. Continuously irradiate the reaction system with a xenon lamp equipped with an AM1.5G filter at a light intensity of 150 mW / cm². 2 The illumination time was 8 hours. After the reaction was complete, the products were qualitatively and quantitatively analyzed using gas chromatography. Gas chromatography analysis of extracted gas showed that the vinyl chloride yield was 998.5 μmol·g. -1 ·h -1 .

[0052] Figure 1 The mass spectrum of vinyl chloride, the product provided in Example 1. Figure 1 As can be seen, the results obtained by injecting the gas in Example 1 into the gas chromatography-mass spectrometry instrument are shown in red for mass spectrometry data and in blue for standard mass spectrometry data of vinyl chloride from the instrument database. It can be seen that the experimental result is vinyl chloride.

[0053] Figure 2 The gas chromatogram of vinyl chloride, the product provided in Example 1. From... Figure 2 It can be seen that the results obtained by injecting the gas from Example 1 into the gas chromatograph show two peaks: the first peak is acetylene, and the second peak is the product vinyl chloride.

[0054] Example 2

[0055] (1) Add 0.97 g of bismuth nitrate pentahydrate and 0.149 g of potassium chloride to 30 mL of deionized water, stir for 60 minutes, then transfer to a 50 mL reactor. Heat at a rate of 1 °C / min and maintain at 160 °C for 24 hours. After washing three times with deionized water by centrifugation, place in a vacuum drying oven at 60 °C for 12 hours. After drying and grinding, BiOCl solid powder is obtained.

[0056] (2) Take 5 mg of the prepared BiOCl and add it to the photocatalytic reactor. Introduce argon, acetylene, and hydrogen chloride gases into the reactor at a ratio of 1:1.1:0.25 for approximately 15 minutes, and then exhaust other gases. Maintain the reaction system temperature at room temperature using a constant-temperature water bath. Continuously irradiate the catalyst with a xenon lamp equipped with a 400-cut filter at a light intensity of 100 mW / cm². 2 The illumination time was 10 hours. After the reaction was complete, the products were qualitatively and quantitatively analyzed using gas chromatography. Gas chromatography analysis of extracted gas showed that the yield of vinyl chloride was 150.3 μmol·g. -1 ·h -1 .

[0057] Example 3

[0058] (1) Add 10g of urea to a round crucible and cover it. Heat the crucible at a rate of 5℃ / min and maintain it at 520℃ for 4 hours. Grind the resulting product into powder. Then put 1g of powder into a square crucible and heat it at a rate of 10℃ / min. Maintain it at 550℃ for 3 hours to obtain powdered g-C3N4.

[0059] (2) Take 10 mg of the prepared g-C3N4 and add it to 30 mL of seawater. Sonicate and stir to ensure thorough mixing and form a suspension. Transfer the suspension to a photocatalytic reactor. Introduce a 1:1 mixture of acetylene and argon into the solution for approximately 15 minutes, then remove other gases. A certain amount of oxygen may be added. Under continuous stirring, maintain the reaction system temperature at room temperature using a constant-temperature water bath. Irradiate the reaction system continuously with a xenon lamp equipped with an AM 1.5G filter at a light intensity of 150 mW / cm². 2 The illumination time was 8 hours. After the reaction was complete, the products were qualitatively and quantitatively analyzed using gas chromatography. Gas extraction and gas chromatography analysis showed that the vinyl chloride yield was 203.6 μmol·g. -1 ·h -1 .

[0060] Example 4

[0061] (1) Take 10 mg of titanium dioxide P25 and add it to 28 mL of aqueous solution containing 0.4 g NaCl. Then add 1 mL of 0.5 M sulfuric acid, sonicate and stir to mix thoroughly to form a suspension. Transfer the suspension to a photocatalytic reactor. Introduce high-purity acetylene gas into the solution for about 15 minutes and purge other gases. Under continuous stirring, maintain the reaction system temperature at room temperature using a constant temperature water bath. Turn on a xenon lamp equipped with a 400 nm filter to continuously irradiate the reaction system with a light intensity of 100 mW / cm². 2 The illumination time was 4 hours. After the reaction was complete, the products were qualitatively and quantitatively analyzed using gas chromatography. Gas extraction and gas chromatography analysis showed that the vinyl chloride yield was 21.5 μmol·g. -1 ·h -1 .

[0062] Example 5

[0063] (1) Add 15g of melamine to a round crucible and cover it. Heat the crucible at a rate of 5℃ / min and maintain it at 550℃ for 4 hours. Grind the resulting product into powder. Then put 1g of powder into a square crucible and heat it at a rate of 10℃ / min. Maintain it at 550℃ for 3 hours to obtain powdered g-C3N4.

[0064] (2) 4.62 g Cd(NO3)2 and 4.62 g thiourea were dispersed in 60 mL ethylenediamine and stirred for 1 h. Then, the mixture was transferred to a 100 mL reactor and kept at 160°C for 24 h. After naturally cooling to room temperature, the resulting yellow product was centrifuged, washed three times with water and ethanol, and then dried at 60°C to obtain CdS nanorods.

[0065] (3) 16 mg g-C3N4 was dispersed in 15 mL of methanol and sonicated for 1 h. Then, 10 mL of methanol containing 194 mg CdS nanorods was added dropwise to the mixture and stirred for another 24 h. After that, the final product was collected by centrifugation and dried at 60 °C under vacuum to obtain CdS-C3N4.

[0066] (4) Take 15 mg of the prepared CdS-C3N4 and add it to 20 mL of aqueous solution, and add 0.9 g of sodium chloride to the solution. Pass high-purity acetylene gas into the solution for about 15 minutes to purge other gases. Under continuous stirring, maintain the reaction system temperature at room temperature using a constant temperature water bath, and continuously irradiate the reaction system with a xenon lamp equipped with a UVCUT420 filter at a light intensity of 200 mW / cm². 2 The illumination time was 6 hours. After the reaction was complete, the products were qualitatively and quantitatively analyzed using gas chromatography. Gas extraction and gas chromatography analysis showed that the vinyl chloride yield was 53.6 μmol·g. -1 ·h -1 .

[0067] This invention describes preferred embodiments and their effects. However, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to include both the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0068] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for the synthesis of vinyl chloride by the photocatalytic hydrochlorination of acetylene, characterized in that, The method comprises the following steps: ethyne is introduced into a container containing a water solution of chloride ions, and a reaction is carried out by irradiation of a light source in the presence of a photocatalyst to obtain vinyl chloride; the photocatalyst comprises a nano semiconductor photocatalyst and a metal or metal oxide supported on the nano semiconductor photocatalyst; the nano semiconductor photocatalyst comprises g-C3N4, BiVO4, CdS, MoS2, Bi2WO6, BiOCl or a heterojunction composite material composed of the above; the metal element in the metal or metal oxide comprises Pd, Pt, Ni, Ag, Cu, Co, Fe, Ru or a binary or ternary alloy composed of the above; the heterojunction composite material comprises BiOCl-C3N4, BiOCl / BiVO4, Bi / BiOCl, Cu2O / BiOCl, Au / BiOCl, Au / BiOCl-C3N4 or Bi2MoO6-BiOCl; the nano semiconductor photocatalyst is loaded with 0.1% to 5% of the metal or metal oxide by mass percentage; when the ethyne is introduced into the container containing the water solution of chloride ions, the photocatalyst is added into the water solution of chloride ions, wherein the amount of the photocatalyst added is 2 to 100 mg, and the volume of the water solution of chloride ions added is 5 to 20 mL, wherein the amount of the chloride salt in the water solution of chloride ions added is 0.01 to 1 g; wherein the ethyne is introduced into the container containing the water solution of chloride ions, and after other gases in the container are removed, oxygen, nitrogen, carbon monoxide or carbon dioxide gas is introduced; the water solution of chloride ions further comprises an acid solution with a concentration of 0.01 to 6 mol / L.

2. The method of photocatalytic hydrochlorination of acetylene to synthesize vinyl chloride according to claim 1, characterized in that, the container is a photocatalytic reactor.

3. The method of photocatalytic hydrochlorination of acetylene to synthesize vinyl chloride according to claim 1, characterized in that, The light source comprises a xenon lamp, a mercury lamp, a 420 nm LED lamp, a 475 nm LED lamp or a 550 nm LED lamp; the light intensity is 10-3000 mW / cm 2 ; and the light exposure time is 0.5-50 h.

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