Low-temperature acetylene selective hydrogenation catalyst, and preparation method and application thereof

Abstract

The application relates to a low-temperature acetylene selective hydrogenation catalyst and a preparation method and application thereof, and belongs to the chemical and chemical engineering technical field. The preparation method of the catalyst comprises the following steps: (1) uniformly dispersing a template and a transition metal source in a solvent I, removing the solvent I through stirring or filtering, drying, and obtaining a mixture A; (2) reacting the mixture A obtained in the step (1) with a sulfur source at 200-750 DEG C for 1-48h, then washing off the template, performing suction filtration and washing, and drying to obtain a two-dimensional transition metal sulfide; and (3) dispersing noble metal precursors and the two-dimensional transition metal sulfide in a solvent II, and preparing a two-dimensional transition metal sulfide supported noble metal catalyst through a wet impregnation method. The catalyst has the characteristics of high acetylene conversion rate, high ethylene selectivity, anti-coking, good stability and the like, has good industrial application prospect and commercial value, and promotes the low-temperature, green and sustainable development of the ethylene industry.

Description

Technical Field

[0001] This invention relates to a low-temperature selective hydrogenation catalyst for acetylene, its preparation method and application, belonging to the fields of chemistry and chemical engineering technology. Background Technology

[0002] Ethylene is an important basic raw material in chemical production, and its main source is naphtha cracking. Due to the scarcity and high price of petroleum, selective hydrogenation of coal-derived acetylene has become a promising non-oil route for ethylene production (Angewandte Chemie International Edition, 2019, 58:7669).

[0003] Currently, in the research on catalysts for the selective hydrogenation of acetylene, the catalyst systems developed by researchers mainly include single-atom catalysts, supported catalysts, and bimetallic catalysts (ACS Catalysis, 2015, 5:3717; ACS Catalysis, 2015, 6:666; ACS Catalysis, 2020, 10:3495; ACS Catalysis, 2016, 6:1054; Journal of American Chemical Society, 2017, 139:7294; ACS Catalysis, 2017, 7:7835; Physical Chemistry Chemical Physics, 2013, 15:12187; Nano Research, 2022, 15). To improve ethylene selectivity, the adsorption intensity of ethylene can be reduced by dispersing active sites or electronic modification. However, it is difficult to maintain strong acetylene adsorption at the same time. It is difficult to maintain high activity while achieving high selectivity. Therefore, achieving 100% acetylene conversion usually requires a high reaction temperature of 100-220℃, and there is a lack of low-temperature, high-activity acetylene hydrogenation catalysts.

[0004] High reaction temperatures in industrial processes lead to higher energy consumption and the generation of unnecessary byproducts, such as green oil or coking. Therefore, mild reaction conditions are essential for energy conservation and industrial applications. Designing novel two-dimensional transition metal sulfide-based catalysts that reduce ethylene adsorption while maintaining strong acetylene adsorption and suitable H2 dissociation capabilities, thereby achieving high activity and ethylene selectivity at low temperatures, has significant industrial implications for the selective hydrogenation of acetylene. Summary of the Invention

[0005] The purpose of this invention is to provide a low-temperature selective hydrogenation catalyst for acetylene, its preparation method, and its application. This invention utilizes two-dimensional nanosheet or porous foam-like two-dimensional transition metal sulfide materials grown on a template, confining noble metals using a wet impregnation method, and for the first time applying them to the selective hydrogenation of acetylene at low temperatures. This method synthesizes two-dimensional nanosheet-like two-dimensional transition metal sulfide materials in one step. The structure of the two-dimensional transition metal sulfide can be modulated by controlling the template size and type, increasing the specific surface area, improving the probability of interfacial reaction collisions, and thus increasing the reaction rate. The confinement of noble metals through sulfur coordination improves the atomic utilization of the noble metals and significantly enhances the interaction between the noble metals and the support. Electronic modification gives the catalyst strong acetylene adsorption capacity while also facilitating ethylene desorption, achieving high acetylene conversion and high ethylene selectivity at low temperatures or even room temperature. This exhibits catalytic activity higher than commercial Lindela catalysts, overcoming key technical bottlenecks in acetylene selective hydrogenation catalyst systems such as low active site concentration, high reaction temperature, slow diffusion of reactant molecules at low temperatures, and low reaction activity.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] This invention provides a method for preparing a two-dimensional transition metal sulfide-supported noble metal catalyst, the method comprising the following steps:

[0008] (1) The template and the transition metal source are uniformly dispersed in solvent I. Solvent I is removed by stirring or filtration and dried to obtain mixture A.

[0009] (2) The mixture A obtained in step (1) is reacted with a sulfur source at 200-750°C for 1-48 hours. Then the template is washed off, filtered, washed and dried to obtain a two-dimensional transition metal sulfide.

[0010] (3) The noble metal precursor and the two-dimensional transition metal sulfide are dispersed in solvent II and the two-dimensional transition metal sulfide supported noble metal catalyst is prepared by wet impregnation.

[0011] In the above technical solution, further, in step (1), the template is at least one of the following: silica mesoporous molecular sieve SBA-15, nano silica spheres, silica nanowires, alumina nanowires, titanium dioxide nanowires, titanium dioxide nanospheres, and nano zinc oxide, and the diameter of each oxide sphere and oxide nanowire is 2 to 500 nm.

[0012] The transition metal source is one of tungsten, molybdenum, vanadium, titanium, and tantalum. The tungsten source is at least one of ammonium tungstate, sodium tungstate, sodium phosphotungstate, and tungsten chloride. The molybdenum source is at least one of ammonium molybdate, potassium molybdate, phosphomolybdic acid, and molybdenum oxide. The vanadium source is at least one of sodium orthovanadate, sodium metavanadate, and vanadium chloride. The titanium source is ammonium fluorotitanate, and the tantalum source is tantalum pentachloride.

[0013] Solvent I is at least one of water, ethanol, acetone, acetaldehyde, carbon tetrachloride, and cyclohexane;

[0014] The sulfur source is at least one of thiourea, sodium thiosulfate, sodium sulfite, sulfur powder, sodium sulfide, potassium sulfide, hydrogen sulfide, carbon disulfide, dimethyl sulfoxide, thioacetamide, cysteine, and thiols.

[0015] In the transition metal source and the sulfur source, the molar ratio of transition metal atoms to sulfur atoms is 1:1 to 1:800.

[0016] In the above technical solution, further, in step (2), at least one of the following solutions is used to wash away the template: ethanol solution, sodium hydroxide solution, potassium hydroxide solution, hydrochloric acid solution, hydrofluoric acid solution, nitric acid solution, formic acid solution, and acetic acid solution, and the treatment time is 1 to 48 hours;

[0017] The drying temperature is 50-200℃, and the drying time is 2-48h.

[0018] In the above technical solution, further, in step (3), the noble metal precursor is at least one of the noble metal chloride, nitrate compound, sulfate compound, acetate and acetylacetone metal salt, and the noble metal is one of gold, silver, palladium, rhodium, platinum and ruthenium;

[0019] Solvent II is at least one of water, ethanol, ethylene glycol, acetone, acetaldehyde, carbon tetrachloride, and cyclohexane;

[0020] In the noble metal precursor and the two-dimensional transition metal sulfide, the molar ratio of noble metal atoms to transition metal atoms is 0.0001 to 2.

[0021] Another aspect of the present invention provides a two-dimensional transition metal sulfide supported noble metal catalyst prepared by the above preparation method, wherein the two-dimensional transition metal sulfide is one of molybdenum disulfide, vanadium disulfide, tungsten disulfide, tantalum disulfide, and titanium disulfide; and the noble metal is one of gold, silver, palladium, rhodium, platinum, and ruthenium, wherein the noble metal is at least one of single atoms or particles.

[0022] In the above technical solution, the transition metal sulfide is a nanosheet or porous foam structure, and the pore size of the porous foam structure is 20-500 nm.

[0023] In another aspect, this invention provides the application of the above-mentioned catalyst in a low-temperature selective hydrogenation reaction of acetylene, wherein the acetylene hydrogenation reaction pressure is 0.1-2 MPa; the reaction temperature is -30-100℃; and the reaction space velocity is 3000-720000 mL g. cat. -1 h -1.

[0024] In the above technical solution, the low-temperature acetylene selective hydrogenation reactor is one or more of the following: fixed bed reactor, batch reactor, fluidized bed reactor, slurry bed reactor, and moving bed reactor.

[0025] In the above technical solution, further, before the selective hydrogenation reaction of low-temperature acetylene, the mixture is pretreated at 180–600°C for 0.5–50 h in an inert atmosphere, a reducing atmosphere, or a mixture of an inert atmosphere and a reducing atmosphere; the inert atmosphere is at least one of nitrogen, argon, and helium, and the reducing atmosphere is at least one of hydrogen, carbon monoxide, hydrogen sulfide, and ammonia; the volume content of the reducing atmosphere in the mixture of the inert atmosphere and the reducing atmosphere is 1–90%.

[0026] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0027] (1) In view of the problem that traditional catalysts require a certain high temperature to achieve high acetylene conversion and low low temperature conversion, the present invention synthesizes two-dimensional nanosheets or porous foam two-dimensional transition metal sulfides in one step by template method. The structure of two-dimensional transition metal sulfides can be modulated by controlling the size and type of template, increasing the specific surface area, increasing the probability of interfacial reaction collision, thereby increasing the reaction rate and reducing the reaction temperature.

[0028] (2) To address the problem of low ethylene selectivity in the selective hydrogenation of acetylene by traditional noble metal catalysts, this invention utilizes a simple wet impregnation method to achieve atomic-level dispersion of noble metals. The noble metals are placed in the upper limit of the well-defined two-dimensional transition metal sulfide, which improves the uniformity of active sites. The noble metal precursor, solvent type, and molar ratio of noble metal atoms to transition metal atoms can be adjusted through the wet impregnation process. This method is simple and has a wide range of applications. In addition, the interaction between the noble metal and the support allows the catalyst to maintain strong acetylene adsorption capacity while facilitating ethylene desorption, which significantly improves catalytic activity and selectivity.

[0029] (3) The interaction between noble metals and two-dimensional transition metal sulfides is enhanced by atmospheric treatment. The unique coordination and electron transfer between noble metals and two-dimensional transition metal sulfides enable the catalyst to maintain high ethylene selectivity at low temperature while having a much higher activity than other supported noble metal catalysts.

[0030] In summary, this invention is the first to use two-dimensional nanosheet or porous foam two-dimensional transition metal sulfide materials for low-temperature selective hydrogenation of acetylene, breaking through the key technical bottlenecks of high reaction temperature, low low-temperature activity, and low selectivity in acetylene selective hydrogenation catalyst systems. The catalyst exhibits high acetylene conversion rate at low temperatures or even at room temperature, high ethylene selectivity, anti-sintering properties, and good stability, and has excellent industrial application prospects and commercial value. Attached Figure Description

[0031] Figure 1 The XRD patterns are of the catalysts Cat-1, Cat-2, and Cat-4 prepared in Examples 1, 2, and 4, respectively.

[0032] Figure 2 The XRD pattern is shown in Example 3.

[0033] Figure 3 The images show TEM and HAADF-STEM images of the catalyst Cat-1 prepared in Example 1, where a is the TEM image and b is the HAADF-STEM image.

[0034] Figure 4 TEM images of catalysts Cat-2-4 prepared in Examples 2-4 and Catalysts Cat5-7 prepared in Comparative Examples 1-3 are shown. a is Cat2, b is Cat3, c is Cat4, d is Cat5, e is Cat6, and f is Cat7. Detailed Implementation

[0035] The following examples illustrate the low-temperature selective hydrogenation catalyst for acetylene provided by the present invention, its preparation method, and its application, but the present invention is not limited thereto.

[0036] Example 1

[0037] (1) Disperse 400mg sodium tungstate dihydrate and 1600mg silica (silica spheres with a diameter of about 50-100nm) evenly in 20mL of deionized water, sonicate for 1h at a frequency of 120kHz, then stir dry at room temperature, and then dry in a 100℃ drying oven for 24h.

[0038] (2) The dried sample and 20 mL of carbon disulfide were sealed in a 50 mL stainless steel autoclave under argon protection and reacted at 450 °C for 6 h. The product was treated in hydrofluoric acid solution for 12 h to remove the silica template. Then it was washed with deionized water and anhydrous ethanol until neutral and dried in an oven at 80 °C for 24 h to obtain a two-dimensional transition metal sulfide.

[0039] (3) Disperse 10 mg of chloropalladic acid and 400 mg of two-dimensional transition metal sulfide in 30 mL of water, stir at room temperature for 12 h, filter, and then dry in a 100 °C drying oven for 12 h. Record as Cat-1.

[0040] Example 2

[0041] (1) Disperse 600mg sodium tungstate dihydrate and 2000mg silica (silica spheres with a diameter of about 50-100nm) evenly in 40mL of deionized water, sonicate for 1h at a frequency of 120kHz, then stir dry at room temperature, and then dry in a 100℃ drying oven for 24h.

[0042] (2) The dried sample and 30 mL of carbon disulfide were sealed in a 50 mL stainless steel autoclave under argon protection and reacted at 450 °C for 6 h. The product was treated in hydrofluoric acid solution for 12 h to remove the silica template. Then it was washed with deionized water and anhydrous ethanol until neutral and then dried in an oven at 80 °C for 24 h to obtain a two-dimensional transition metal sulfide.

[0043] (3) Disperse 6 mg of palladium chloride and 400 mg of two-dimensional transition metal sulfide in 10 mL of acetone solution, air dry at room temperature, and then dry in a drying oven at 100 °C for 12 h. This is denoted as Cat-2.

[0044] Example 3

[0045] (1) Disperse 400mg ammonium molybdate and 1600mg silica (silica spheres with a diameter of about 70-200nm) evenly in 20mL of deionized water, sonicate for 1h at a frequency of 120kHz, then stir dry at room temperature, and then dry in a 100℃ drying oven for 24h.

[0046] (2) The dried sample and 20 mL of carbon disulfide were sealed in a 50 mL stainless steel autoclave under argon protection and reacted at 450 °C for 4 h. The product was treated in hydrofluoric acid solution for 12 h to remove the silica template. Then it was washed with deionized water and anhydrous ethanol until neutral and then dried in an oven at 80 °C for 24 h to obtain a two-dimensional transition metal sulfide.

[0047] (3) Disperse 20 mg of chloropalladic acid and 400 mg of two-dimensional transition metal sulfide in 20 mL of ethylene glycol solution, heat and stir at 100 °C until dry, and then dry in a drying oven at 100 °C for 12 h. Record as Cat-3.

[0048] Example 4

[0049] (1) Disperse 200mg ammonium tungstate and 1600mg silica (silica spheres with a diameter of about 70-200nm) evenly in 20mL of deionized water, sonicate for 1h at a frequency of 120kHz, then stir dry at room temperature, and then dry in a 100℃ drying oven for 24h.

[0050] (2) The dried sample and 20 mL of carbon disulfide were sealed in a 50 mL stainless steel autoclave under argon protection and reacted at 400 °C for 6 h. The product was treated in hydrofluoric acid solution for 12 h to remove the silica template. Then it was washed with deionized water and anhydrous ethanol until neutral and then dried in an oven at 80 °C for 24 h to obtain a two-dimensional transition metal sulfide.

[0051] (3) Disperse 10 mg of chloropalladic acid and 400 mg of two-dimensional transition metal sulfide in 30 mL of a solution of water and ethanol in a 1:1 ratio. Stir at room temperature for 12 h, filter, and then dry in a 100 °C drying oven for 12 h. This solution is denoted as Cat-4.

[0052] Comparative Example 1

[0053] (1) Disperse 600mg sodium tungstate dihydrate and 2000mg silica (silica spheres with a diameter of about 50-100nm) evenly in 40mL of deionized water, sonicate for 1h at a frequency of 120kHz, then stir dry at room temperature, and then dry in a 100℃ drying oven for 24h.

[0054] (2) The dried sample and 30 mL of carbon disulfide were sealed in a 50 mL stainless steel autoclave under argon protection and reacted at 450 °C for 6 h. The product was treated in hydrofluoric acid solution for 12 h to remove the silica template. Then it was washed with deionized water and anhydrous ethanol until neutral and dried in an oven at 80 °C for 24 h to obtain a two-dimensional transition metal sulfide, denoted as Cat-5.

[0055] Comparative Example 2

[0056] 10 mg of chloropalladic acid and 400 mg of carbon black (XC-72) (Annegi) were dispersed in 30 mL of aqueous solution. After stirring at room temperature for 12 h, the mixture was filtered and then dried in a drying oven at 100 °C for 12 h. This product is designated as Cat-6.

[0057] Comparative Example 3

[0058] 10 mg of chloropalladic acid and 400 mg of nano-silica (Alfa Aesar) were dispersed in 30 mL of aqueous solution, stirred at room temperature for 12 h, filtered, and then dried in a drying oven at 100 °C for 12 h. This was designated Cat-7.

[0059] Comparative Example 4

[0060] A commercially available Lindela catalyst was used as a control sample. It was designated Cat-8.

[0061] Application Example 1

[0062] Taking a fixed-bed reactor as an example, the specific steps for applying a catalyst are as follows:

[0063] 10 mg of catalyst was loaded into the reaction tube, and then 1 bar and 50 mL of water were introduced at a constant temperature. -1 H2 was pretreated at 300℃ for 1 hour. After the temperature was lowered to the reaction temperature (25℃ for example), the reaction gas was switched to 1% C2H2 / 20% / H2 / 79% He, and the gas space velocity was 360,000 mL g / L. cat. -1 h -1 For example, the reaction products were analyzed online using gas chromatography, and qualitative and quantitative analyses were performed using an FID detector. Specific reaction performance details are listed in Table 1.

[0064] Table 1 Catalyst performance evaluation results

[0065]

[0066] The catalyst Cat-5 prepared in Comparative Example 1 is tungsten sulfide without noble metal support. It has almost no acetylene activity at low temperature. However, after being supported with noble metal, catalysts Cat-1, Cat-2 and Cat-4 can all achieve complete acetylene conversion at room temperature. They have a significant advantage in low-temperature acetylene hydrogenation activity compared with other carbon supports and silica supports that support noble metals (Cat-6, Cat-7). Compared with commercial Lindela catalysts, they exhibit higher acetylene catalytic activity and comparable ethylene selectivity.

[0067] The catalyst prepared in this invention has never been reported or applied to the selective hydrogenation of acetylene at low temperatures, and it exhibits excellent activity and selectivity in the selective hydrogenation of acetylene at low temperatures, while also possessing excellent stability, and is expected to be industrialized.

Claims

1. The application of a two-dimensional transition metal sulfide-supported noble metal catalyst in the selective hydrogenation of acetylene at low temperature, characterized in that, The temperature range for acetylene hydrogenation is -30 to 25 °C. The method for preparing the catalyst includes the following steps: (1) The template and the transition metal source are uniformly dispersed in solvent I. Solvent I is removed by stirring or filtration and dried to obtain mixture A; (2) The mixture A obtained in step (1) was reacted with a sulfur source at 200~750 °C for 1~48 h, then the template was washed off, filtered, washed and dried to obtain a two-dimensional transition metal sulfide; (3) The noble metal precursor and the two-dimensional transition metal sulfide are dispersed in solvent II and the two-dimensional transition metal sulfide supported noble metal catalyst is prepared by wet impregnation method. The transition metal source is one of tungsten source and molybdenum source, wherein the tungsten source is at least one of ammonium tungstate, sodium tungstate, sodium phosphotungstate, and tungsten chloride, and the molybdenum source is at least one of ammonium molybdate, potassium molybdate, phosphomolybdic acid, and molybdenum oxide; The sulfur source is carbon disulfide.

2. The application according to claim 1, characterized in that, In step (1), the template is a nano-silica sphere; Solvent I is at least one of water, ethanol, acetone, acetaldehyde, carbon tetrachloride, and cyclohexane; In the transition metal source and the sulfur source, the molar ratio of transition metal atoms to sulfur atoms is 1:1 to 1:

800.

3. The application according to claim 1, characterized in that, In step (2), the template is washed away with sodium hydroxide solution, potassium hydroxide solution or hydrofluoric acid solution for a processing time of 1 to 48 hours. The drying temperature is 50~200 ℃, and the drying time is 2~48 h.

4. The application according to claim 1, characterized in that, In step (3), the noble metal precursor is at least one of the chloride, nitrate compound, sulfate compound, acetate and acetylacetone metal salt of a noble metal, and the noble metal is one of gold, silver, palladium, rhodium, platinum and ruthenium. Solvent II is at least one of water, ethanol, ethylene glycol, acetone, acetaldehyde, carbon tetrachloride, and cyclohexane; In the noble metal precursor and the two-dimensional transition metal sulfide, the molar ratio of noble metal atoms to transition metal atoms is 0.0001~2.

5. The application according to claim 4, characterized in that, In the catalyst, the two-dimensional transition metal sulfide is one of molybdenum disulfide and tungsten disulfide; the noble metal is one of gold, silver, palladium, rhodium, platinum and ruthenium, wherein the noble metal is at least one of single atoms or particles.

6. The application according to claim 5, characterized in that, The transition metal sulfide is in the form of nanosheets.

7. The application according to claim 1, characterized in that: The hydrogenation reaction of acetylene is carried out at a pressure of 0.1–2 MPa and a space velocity of 3,000–720,000 mL g. cat. -1 h -1 .

8. The application according to claim 1, characterized in that: The reactor for the selective hydrogenation reaction of low-temperature acetylene is one or more of the following: fixed-bed reactor, batch reactor, fluidized-bed reactor, slurry-bed reactor, and moving-bed reactor.

9. The application according to claim 1, characterized in that: Before the selective hydrogenation reaction of acetylene at low temperature, the mixture is pretreated at 180~600 °C for 0.5~50 h in a reducing atmosphere or a mixture of an inert atmosphere and a reducing atmosphere; the inert atmosphere is at least one of nitrogen, argon, and helium, and the reducing atmosphere is at least one of hydrogen and carbon monoxide; the volume content of the reducing atmosphere in the mixture of the inert atmosphere and the reducing atmosphere is 1%~90%.

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