Preparation method and application of sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based

Abstract

The present invention discloses a method for preparing a sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst, and relates to the technical field of catalytic hydrogenation. A noble metal catalyst is used as an active ingredient, sodium hypophosphite is used as an auxiliary agent, and a sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst is prepared by a heat treatment method and an equal volume impregnation method. The invention greatly improves the catalytic performance while reducing the amount of noble metal through the synergistic effect between sodium hypophosphite, black phosphorus and noble metals, which is beneficial to improving the economic benefits of industrial production. Ultimately, an energy-saving, environmentally friendly and efficient styrene hydrogenation catalytic process is achieved. The method of the present invention has the characteristics of high efficiency, simplicity, green and pollution-free reaction process, and has high industrial application value.

Description

Technical Field

[0001] The invention discloses a preparation method and application of a black phosphorus modified noble metal / carbon base modified by sodium hypophosphite, and relates to the technical field of catalytic hydrogenation. Background Art

[0002] Aromatics and other organic compounds are important chemical raw materials. Styrene hydrogenation is the most common hydrogenation reaction in industry and is often used as a probe reaction in metal-catalyzed hydrogenation research. Ethylbenzene, the product of selective styrene hydrogenation, has excellent stability and plays an important role in gasoline production and the aromatics industry. Therefore, styrene hydrogenation has attracted widespread attention in the petroleum industry.

[0003] Commonly used hydrogenation catalysts for the hydrogenation reaction of aromatic organic compounds include two types: precious metal catalysts and non-precious metal catalysts. Precious metal catalysts are widely used in the field of catalysis due to their special electronic structure and high catalytic activity. Non-metal doping strategies are often used to enhance the activity of precious metal catalysts. Lin et al. [Catalysis Communications, 2020, 144: 106094] used calcination and impregnation techniques to prepare a palladium catalyst supported by phosphorus-doped g-C3N4. The highly dispersed Pd catalyst showed excellent activity for the hydrogenation of styrene. Chen et al. [Applied Catalysis B: Environmental, 2021, 284, 119713] synthesized a Pd-P catalyst using a heating reflux method, which has the advantages of high efficiency and good stability. Since precious metals are expensive, the large-scale use of this catalyst will inevitably lead to higher production costs. Therefore, improving the hydrogen efficiency of the catalyst and reducing the amount of catalyst used are effective ways to reduce the production costs of enterprises.

[0004] Activated carbon (AC) has a developed pore structure, a large specific surface area, stable physical properties, strong adsorption capacity and rich surface chemical groups. It can provide more active sites for catalysts, make them well dispersed, and improve catalytic efficiency. It is the main carrier of catalysts.

[0005] Black phosphorus (BP) has attracted widespread attention in the electronics and optoelectronics fields due to its unique properties, including high carrier mobility, a wide and tunable direct band gap, and its ability to be stacked as a few atomic layers in a van der Waals fashion [Nature Materials | doi:10.1038 / s41563-023-01516-1]. Theoretical calculations indicate that the unoccupied orbitals of noble metals can interact with black phosphorus through cation-π bonds, autonomously forming a relatively stable structure. The synergistic effect of black phosphorus and noble metals can effectively enhance catalytic activity and significantly reduce costs [Bai Lichen, et al. Advanced Materials 2018;30:1803641, Wang Xin, et al. Angewandte Chemie - International Edition 2019;131:2]. Summary of the Invention

[0006] The present invention provides a method for preparing a black phosphorus-modified noble metal / carbon-based catalyst modified with sodium hypophosphite and its application to improve the conversion rate in styrene hydrogenation reactions, reduce the amount of catalyst used in production, and lower production costs. This method has a simple process, mild reaction conditions, and significantly improves the conversion rate of styrene hydrogenation.

[0007] The present invention is achieved through the following technical solutions:

[0008] A preparation method and application of a black phosphorus-modified noble metal / carbon-based composite modified with sodium hypophosphite, wherein the noble metal is selected from one or more of palladium / carbon, platinum / carbon, ruthenium / carbon, palladium / carbon, and platinum / carbon composite materials;

[0009] The raw material of black phosphorus is selected from one or more of black phosphorus powder, black phosphorus quantum dots, black phosphorus nanosheets, and black phosphorus crystals.

[0010] The content of black phosphorus is 0.001wt%-5wt% of the mass of the precious metal.

[0011] The content of sodium hypophosphite is selected from 0.01-10 wt% of the mass of the precious metal.

[0012] More preferably, the mass fraction of sodium hypophosphite is 0.01 wt%-5 wt%.

[0013] More preferably, the mass fraction of sodium hypophosphite is any one of 0.05 wt%, 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.5 wt%, 0.8 wt% and 1.0 wt%.

[0014] The raw material of black phosphorus in the black phosphorus modified noble metal / carbon-based catalyst is selected from one or more of black phosphorus powder, black phosphorus quantum dots, black phosphorus nanosheets, and black phosphorus crystals; the content of black phosphorus is selected from any one of 0.1wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.8wt%, and 1wt%.

[0015] The carbon base is selected from one or more of columnar carbon, spherical carbon, carbon molecular sieve, microspherical carbon, carbon nanotube, and carbon fiber. The carbon bases described in this application can all achieve the technical effects of the carrier as a carrier part.

[0016] The preparation method and application of the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based material comprises the following steps:

[0017] (1) ultrasonically treating black phosphorus powder to obtain a black phosphorus dispersion, and then adding sodium hypophosphite to obtain a mixed solution;

[0018] (2) Spraying the mixed solution evenly on the surface of the support with a spray bottle, followed by drying and calcining;

[0019] (3) Loading noble metal salts on the black phosphorus-modified carrier, drying and then reducing to obtain a black phosphorus-noble metal / carbon-based catalyst modified with black sodium hypophosphite.

[0020] The black phosphorus solution is obtained by uniformly dispersing the black phosphorus raw material in a solvent; the solvent is selected from one or more of anhydrous ethanol, N-methylpyrrolidone, N-vinylpyrrolidone, N-cycloethylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropyl alcohol, tert-butanol, acetone, 2-pentanone, and water. All of the above solvents can effectively disperse black phosphorus.

[0021] After the ultrasound, a surfactant is selectively added, wherein the surfactant is selected from one or more of polyvinyl pyrrolidone, Pluronic F127, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, alkyloxyethylene phenol ether, octadecyl trimethyl ammonium bromide, and sodium dodecylbenzene sulfonate, and the mass fraction of the surfactant is 0.01wt%-10wt%; or more preferably, the mass fraction of the surfactant is 0.01wt%-5wt%; or more preferably, polyvinyl pyrrolidone, and the mass fraction of the surfactant is selected from any one of 0.625wt%, 1.25wt%, 2.5wt%, 3.75wt%, and 5.0wt%. The surfactant of the present invention can achieve rich active groups on the surface of black phosphorus, increase the contact area between black phosphorus and inorganic sodium hypophosphite, and improve the efficiency of the contact reaction.

[0022] After the ultrasound, sodium hypophosphite is added, wherein the content of the sodium hypophosphite is 0.01wt%-10wt% of the mass of the precious metal, or further preferably, the mass fraction of the sodium hypophosphite is 0.01wt%-5wt%; or further preferably, the mass fraction of the sodium hypophosphite is any one of 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.8wt%, and 1.0wt%.

[0023] P doping in sodium hypophosphite can induce the formation of concave Pd sites, lowering the activation energy of the d-band center. Furthermore, sodium hypophosphite is weakly alkaline, which plays a crucial role in the nanocrystallization of black phosphorus. The synergistic effect between sodium hypophosphite, black phosphorus, and precious metals can significantly enhance the catalyst's activity.

[0024] The noble metal salt is selected from one or more of PdCl2, K2PtCl6 and RuCl3·3H2O.

[0025] The standing time is 1h-10h.

[0026] The drying temperature is 30° C.-100° C., and the drying time is 6-20 hours.

[0027] The calcination temperature is 200-700° C., more preferably 180-400° C., the calcination time is 1-6 hours, and the inert atmosphere used during the calcination process is selected from any one of argon, nitrogen and helium.

[0028] The reduction reaction is carried out by heating the reaction chamber to 160-450°C in a mixed atmosphere of hydrogen and nitrogen for a period of 1-15 hours. The product obtained after the reduction reaction is a black phosphorus-modified noble metal / carbon-based catalyst. The volume fraction of hydrogen in the mixed atmosphere of hydrogen and nitrogen is 5-10%.

[0029] The prepared sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst is used for catalytic reduction of styrene.

[0030] The method for the hydrogenation reduction reaction of styrene using a black phosphorus modified noble metal / carbon-based catalyst modified with sodium hypophosphite comprises the following steps:

[0031] In a preferred embodiment, the solution containing styrene is transferred to the inner lining of an autoclave, a catalyst is added, and hydrogen is introduced in a closed environment. After the hydrogen replaces the air, hydrogen is continuously introduced. It usually takes 3-5 cycles to completely replace the air. Hydrogen is continuously introduced until the pressure in the reactor is controlled to 0.5-10 MPa and the temperature is 30°C-200°C. The reaction is carried out for 0.1-5 hours to obtain a reduced product.

[0032] In a preferred embodiment, the mass ratio of the catalyst to styrene is 0.1-1:3-10; the solvent used in the organic solution is selected from C1-C4 alcohol solvents, and the mass concentration of styrene is 1-50%.

[0033] The present invention utilizes the synergistic effect of sodium hypophosphite, black phosphorus, and precious metals to significantly enhance the catalytic performance and stability of the catalyst while reducing the amount of precious metals used, thereby improving the economic benefits of industrial production. Ultimately, this method achieves an energy-saving, environmentally friendly, and highly efficient styrene hydrogenation catalytic process. The method is characterized by high efficiency, simplicity, and a green, pollution-free reaction process, and has high industrial application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a physical photo of the cylindrical carbon support of Example 2.

[0035] Figure 2 This is the XRD pattern of 1wt% BP-Pd / C-P1 in Example 2.

[0036] Figure 3 This is the stability test of 1wt% BP-Pd / C-P1 in Example 2. After 10 hours of testing, the catalyst has good cyclic stability. DETAILED DESCRIPTION

[0037] The present invention provides a preparation method and application of a black phosphorus-modified noble metal / carbon base modified with sodium hypophosphite. The black phosphorus-modified noble metal / carbon base modified with sodium hypophosphite is modified by forming a bond between phosphorus and the noble metal. The application is to use the black phosphorus-modified noble metal / carbon base modified with sodium hypophosphite for hydrogenation of styrene to produce ethylbenzene.

[0038] To make the objectives, technical solutions, and advantages of the present invention more clearly understood, the present invention is described in detail below with reference to the accompanying drawings and examples. It should be noted that the specific examples described herein are only used to explain the present invention and are not intended to limit the embodiments of the present invention. Any other changes, modifications, combinations, simplifications, and substitutions made without departing from the spirit and principles of the present invention shall be considered equivalent replacement methods and shall be included within the scope of protection of the present invention.

[0039] Example 1

[0040] (1) Preparation of black phosphorus dispersion: 0.8 g of ball-milled black phosphorus powder was dispersed in 80 mL of ethanol and ultrasonically dispersed for 30 h. The resulting solution was the black phosphorus dispersion.

[0041] (2) Preparation of Catalyst 0.05 g of polyvinyl pyrrolidone was added to 10 mL of the black phosphorus dispersion prepared in step (1), and the mixture was ultrasonically treated for 10 min and stirred for 10 min.

[0042] (3) The mixture obtained in step (2) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of columnar carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0043] (4) The black phosphorus-modified activated carbon support obtained in step (3) was placed in an oven at 60° C. and dried for 20 h.

[0044] (5) The support sample obtained in step (4) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0045] (6) A certain amount of PdCl2 was dissolved in deionized water, and metallic palladium was loaded onto the black phosphorus-modified activated carbon of step (5) by electrostatic adsorption at room temperature, and then dried at 80°C overnight.

[0046] (7) The dried sample obtained in step (6) is placed in a tube furnace in a mixed atmosphere containing 90% nitrogen and 10% hydrogen for reduction. Before heating, the remaining air in the tube furnace is first evacuated by vacuuming, and the tube is cleaned three times with nitrogen to ensure safety. The tube furnace is then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction is completed and cooled to room temperature, the sample is taken out, and the final catalyst sample is recorded as 1wt% BP-Pd / C, where 1wt% refers to the mass fraction of black phosphorus.

[0047] Performance evaluation was conducted using an autoclave evaluation apparatus. The reaction conditions were as follows: a certain mass (0.1% relative to the mass of styrene) of the above-mentioned catalyst, 1 wt% BP-Pd / C, was loaded into an autoclave, the hydrogen pressure was 1 MPa, the hydrogenation temperature was 80°C, and the concentration of the styrene ethanol solution was 50%. Hydrogen was introduced, and after sealing the autoclave, 0.25 MPa of hydrogen was added to the autoclave and then released to displace the air in the autoclave. This process was repeated five times, and the autoclave was then filled with hydrogen to the desired pressure (1 MPa). The reaction temperature was 80°C, and the reaction time was 1 hour. After the reaction was completed, the autoclave was cooled to room temperature, and the reaction solution and the catalyst were separated by filtration and centrifugation. The yield of ethylbenzene from styrene was 67%.

[0048] Example 2

[0049] (1) Preparation of black phosphorus dispersion: 0.8 g of ball-milled black phosphorus powder was dispersed in 80 mL of anhydrous formamide and ultrasonically dispersed for 30 h. The resulting solution was the black phosphorus dispersion.

[0050] (2) Preparation of Catalyst 0.05 g of polyvinyl pyrrolidone was added to 10 mL of the black phosphorus dispersion prepared in step (1), and the mixture was ultrasonically treated for 10 min and stirred for 10 min.

[0051] (3) 0.015 g of sodium hypophosphite was added to step (2) and stirred for 1 h to obtain a uniform mixture.

[0052] (4) The mixture obtained in step (3) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of activated carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0053] (5) The black phosphorus-modified activated carbon support obtained in step (4) was placed in an oven at 60° C. and dried for 20 h.

[0054] (6) The support sample obtained in step (5) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0055] (7) Take a certain amount of PdCl2 and dissolve it in deionized water. At room temperature, use electrostatic adsorption to load metal palladium onto the black phosphorus-modified activated carbon in step (6), and then dry it at 80°C overnight.

[0056] (8) The dried sample obtained in step (7) was placed in a tube furnace in a mixed atmosphere containing 90% nitrogen and 10% hydrogen for reduction. Before heating, the remaining air in the tube furnace was evacuated by vacuum, and the tube was purged three times with nitrogen to ensure safety. The tube furnace was then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction was completed and cooled to room temperature, the sample was removed. The catalyst sample finally obtained was recorded as 1wt% BP-Pd / C-P1. Figure 2 This is the XRD pattern of 1wt% BP-Pd / C-P1 material based on black phosphorus nanosheets. The X-ray diffraction peaks at 2-Theta of 17.3, 26.5, 34.5, 35.3, 36.0, 40.1, 43.3, 56.4 and 57.2, corresponding to the (111) crystal plane of palladium, the (300), (401), (315) crystal planes of carbon and the (020), (040), (111), (061) and (132) crystal planes of BP. It can be seen that 1wt% BP-Pd / C-P1 was successfully prepared.

[0057] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.03 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P2.

[0058] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.06 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P3.

[0059] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.09 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P4.

[0060] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.15 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P5.

[0061] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.24 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P6.

[0062] In another embodiment of the present invention, the mass of sodium hypophosphite added in step (3) is 0.3 g, and the other steps are the same as above, and the obtained product is 1 wt% BP-Pd / C-P7.

[0063] Performance evaluation was conducted using an autoclave evaluation apparatus. The reaction conditions were as follows: a certain mass of the aforementioned catalysts (1 wt% BP-Pd / C-P1, 1 wt% BP-Pd / C-P2, 1 wt% BP-Pd / C-P3, 1 wt% BP-Pd / C-P4, 1 wt% BP-Pd / C-P5, and 1 wt% BP-Pd / C-P6) was loaded into an autoclave, the hydrogen pressure was 0.5 MPa, the hydrogenation temperature was 80°C, and the concentration of the styrene ethanol solution was 50% (the catalyst amount being 0.1% by mass of the styrene). Hydrogen was introduced, and after the reactor was sealed, 0.25 MPa of hydrogen was filled into the reactor and then released to replace the air in the reactor. After this process was repeated 5 times, hydrogen was filled into the reactor to the required pressure (1 MPa). The reaction temperature was 80°C and the reaction time was 1 hour. After the reaction was completed, the reactor was cooled to room temperature. Finally, the reaction liquid and the catalyst were separated by filtration and centrifugation. The yield of ethylbenzene prepared from styrene is shown in Table 2.

[0064] A cyclic test was conducted on 1 wt% BP-Pd / C-P1 to catalyze the hydrogenation of styrene to produce ethylbenzene. The test procedure was as follows: after the above catalytic reaction was carried out once, the separated catalyst was washed with ethanol and then loaded into the autoclave again to carry out the above cyclic catalytic reaction of styrene to produce ethylbenzene. The yield was as follows: Figure 3 shown.

[0065] Table 1

[0066]

[0067] A stability test was conducted on the 1wt% BP-Pd / C-P1 product. That is, after sampling and testing at 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10 hours using the above technical solution, it was found that the stability effect still maintained at around 100%, indicating that the catalyst cycle stability is good.

[0068] Example 3

[0069] (1) Preparation of black phosphorus dispersion: 0.8 g of ball-milled black phosphorus powder was dispersed in 80 mL of ethanol and ultrasonically dispersed for 30 h. The resulting solution was the black phosphorus dispersion.

[0070] (2) Preparation of catalyst: Weigh 0.05 g of polyvinyl pyrrolidone and dissolve it in 9 mL of H2O water containing 1 mL of black phosphorus dispersion prepared in step (1), ultrasonically treat for 10 min, and stir for 10 min.

[0071] (3) 0.015 g of sodium carbonate was added to step (2) and stirred for 1 h to obtain a uniform mixture.

[0072] (4) The mixture obtained in step (3) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of columnar carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0073] (5) The black phosphorus-modified activated carbon support obtained in step (4) was placed in an oven at 60° C. and dried for 20 h.

[0074] (6) The support sample obtained in step (5) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0075] (7) A certain amount of PdCl2 was dissolved in deionized water, and metallic palladium was loaded onto the black phosphorus-modified activated carbon of step (5) by electrostatic adsorption at room temperature, and then dried at 80°C overnight.

[0076] (8) The dried sample obtained in step (7) was placed in a tube furnace in a mixed atmosphere containing 90% nitrogen and 10% hydrogen for reduction. Before heating, the remaining air in the tube furnace was first evacuated by vacuum, and the tube was purged three times with nitrogen to ensure safety. The tube furnace was then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction was completed and cooled to room temperature, the sample was removed and the catalyst sample obtained was recorded as 0.1wt% BP-Pd / C-P1.

[0077] In another embodiment of the present invention, sodium carbonate is replaced by sodium bicarbonate in step (2), and the other steps are the same as above, and the obtained product is 0.1 wt% BP-Pd / C-P2.

[0078] In another embodiment of the present invention, in step (2), sodium carbonate is replaced by sodium sulfate, and the other steps are the same as above, and the obtained product is 0.1 wt% BP-Pd / C-P3.

[0079] In another embodiment of the present invention, sodium carbonate is replaced by sodium chloride in step (2), and the other steps are the same as above, and the obtained product is 0.1 wt% BP-Pd / C-P4.

[0080] In another embodiment of the present invention, sodium carbonate is replaced by sodium phosphate in step (2), and the other steps are the same as above, and the obtained product is 0.1 wt% BP-Pd / C-P5.

[0081] Performance evaluation was conducted using an autoclave evaluation apparatus. The reaction conditions were as follows: a certain mass of the aforementioned catalysts (0.1 wt% BP-Pd / C-P1, 0.1 wt% BP-Pd / C-P2, 0.1 wt% BP-Pd / C-P3, 0.1 wt% BP-Pd / C-P4, and 0.1 wt% BP-Pd / C-P5) was loaded into an autoclave, the hydrogen pressure was 1 MPa, the hydrogenation temperature was 80°C, and the concentration of the styrene ethanol solution was 50% (the catalyst amount being 0.1% by mass of the styrene). Hydrogen was introduced, and after the reactor was sealed, 0.25 MPa of hydrogen was filled into the reactor and then released to replace the air in the reactor. After this process was repeated 5 times, hydrogen was filled into the reactor to the required pressure (1 MPa). The reaction temperature was 80°C and the reaction time was 1 hour. After the reaction was completed, the reactor was cooled to room temperature. Finally, the reaction liquid and the catalyst were separated by filtration and centrifugation. The yield of ethylbenzene prepared from styrene is shown in Table 2.

[0082] Table 2

[0083]

[0084] Example 4

[0085] (1) Preparation of black phosphorus dispersion: 0.8 g of ball-milled black phosphorus powder was dispersed in 80 mL of anhydrous isopropanol and ultrasonically dispersed for 30 h. The resulting solution was the black phosphorus dispersion.

[0086] (2) Preparation of Catalyst 0.05 g of Pluronic F127 was weighed into 10 mL of the black phosphorus dispersion prepared in step (1), and the mixture was ultrasonically treated for 10 min and stirred for 10 min.

[0087] (3) 0.03 g of sodium hypophosphite was added to step (2) and stirred for 1 h to obtain a uniform mixture.

[0088] (4) The mixture obtained in step (3) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of columnar carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0089] (5) The black phosphorus-modified activated carbon support obtained in step (4) was placed in an oven at 60° C. and dried for 20 h.

[0090] (6) The support sample obtained in step (5) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0091] (7) Take a certain amount of PdCl2 and dissolve it in deionized water. At room temperature, use electrostatic adsorption to load metal palladium onto the black phosphorus-modified activated carbon in step (6), and then dry it at 80°C overnight.

[0092] (8) The dried sample obtained in step (7) was placed in a tube furnace in a mixed atmosphere containing 90% nitrogen and 10% hydrogen for reduction. Before heating, the remaining air in the tube furnace was evacuated by vacuum, and the tube was purged three times with nitrogen to ensure safety. The tube furnace was then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction was completed and the temperature was cooled to room temperature, the sample was removed and the catalyst sample obtained was recorded as 1wt% BP-Pd / C-P2-1.

[0093] In another embodiment of this example, the surfactant is a polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, and the obtained product is 1 wt% BP-Pd / C-P2-2.

[0094] In another embodiment of this example, the surfactant is alkyloxyethylene phenol ether, and the obtained product is 1 wt% BP-Pd / C-P2-3.

[0095] In another embodiment of this example, the surfactant is sodium dodecylbenzenesulfonate, and the obtained product is 1 wt% BP-Pd / C-P2-4.

[0096] In another embodiment of this example, the black phosphorus raw material is black phosphorus quantum dots, and the obtained product is 1 wt% BP-Pd / C-P2-5.

[0097] In another embodiment of this example, the noble metal / carbon-based catalyst is Pt / C, and the obtained product is 1 wt% BP-Pt / C-P2.

[0098] In another embodiment of this example, the noble metal / carbon-based catalyst is Ru / C, and the obtained product is 1 wt% BP-Ru / C-P2.

[0099] Performance evaluation was conducted using an autoclave evaluation apparatus. The reaction conditions were as follows: a certain mass of the above-prepared catalysts (1 wt% BP-Pd / C-P2-1, 1 wt% BP-Pd / C-P2-2, 1 wt% BP-Pd / C-P2-3, 1 wt% BP-Pd / C-P2-4, 1 wt% BP-Pd / C-P2-5, 1 wt% BP-Pd / C-P2-6, 1 wt% BP-Pt / C-P2, and 1 wt% BP-Ru / C-P2) were loaded into an autoclave, the hydrogen pressure was 1 MPa, the hydrogenation temperature was 80°C, and the concentration of the styrene solution was 50% (the amount of catalyst was 0.1% by mass of the styrene). Hydrogen was introduced, and after sealing the reactor, the reactor was filled with 0.25 MPa of hydrogen and then released to displace the air. This process was repeated five times, and the reactor was then filled with hydrogen to the desired pressure (1 MPa). The reaction temperature was 80°C, and the reaction time was 1 hour. After the reaction, the reactor was cooled to room temperature, and the reaction liquid and catalyst were separated by filtration and centrifugation. The yields are shown in Table 3.

[0100] Table 3

[0101]

[0102] Example 5

[0103] (1) Preparation of black phosphorus dispersion: 0.4 g of ball-milled black phosphorus powder was dispersed in 80 mL of anhydrous dimethyl sulfoxide and ultrasonically dispersed for 15 h. The resulting solution was the black phosphorus dispersion.

[0104] (2) Preparation of Catalyst 0.05 g of polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer was weighed into 10 mL of the black phosphorus dispersion in step (1), ultrasonically treated for 10 min, and stirred for 10 min.

[0105] (3) 0.03 g of sodium hypophosphite was added to step (2) and stirred for 1 h to obtain a uniform mixture.

[0106] (4) The mixture obtained in step (3) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of columnar carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0107] (5) The black phosphorus-modified activated carbon support obtained in step (4) was placed in an oven at 60° C. and dried for 20 h.

[0108] (6) The support sample obtained in step (5) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0109] (7) Take a certain amount of PdCl2 and dissolve it in deionized water. At room temperature, use electrostatic adsorption to load metal palladium onto the black phosphorus-modified activated carbon in step (6), and then dry it at 80°C overnight.

[0110] (8) The dried sample obtained in step (7) was placed in a tube furnace in a mixed atmosphere containing 95% nitrogen and 5% hydrogen for reduction. Before heating, the remaining air in the tube furnace was first evacuated by vacuum, and the tube was purged three times with nitrogen to ensure safety. The tube furnace was then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction was completed and the temperature was cooled to room temperature, the sample was taken out and the catalyst sample finally obtained was recorded as 1wt% BP-Pd / C-P2-0.05.

[0111] In another embodiment of the present invention, the PdCl2 aqueous solution sample in step (7) is electrostatically adsorbed onto the black phosphorus-modified activated carbon in step (5) at room temperature, and then dried overnight at 80°C. The other steps are the same as those in the above embodiment. The resulting catalyst sample is designated as 1 wt% BP-Pd / C-P2-0.05.

[0112] Performance evaluation was performed using an autoclave evaluation apparatus. The reaction conditions were as follows: a certain mass of the above-mentioned catalysts (1 wt% BP-Pd / C-P2-0.1 and 1 wt% BP-Pd / C-P3-0.1) were loaded into an autoclave, the hydrogen pressure was 1 MPa, the hydrogenation temperature was 80°C, and the concentration of the styrene solution was 50% (the catalyst amount was 0.1% of the mass of the styrene). Hydrogen was introduced, and after sealing the autoclave, 0.25 MPa of hydrogen was added to the autoclave and then released to displace the air in the autoclave. This process was repeated five times, and the autoclave was then filled with hydrogen to the desired pressure (1 MPa). The reaction temperature was 80°C, and the reaction time was 1 hour. After the reaction, the autoclave was cooled to room temperature, and the reaction solution and catalyst were separated by filtration and centrifugation. The yield of ethylbenzene from styrene is shown in Table 4.

[0113] Table 4

[0114] catalyst 1wt%BP-Pd / C-P2-0.05 1wt%BP-Pd / C-P2-0.05 Yield 100％ 42％

[0115] Example 6

[0116] (1) Preparation of black phosphorus dispersion: 0.4 g of ball-milled black phosphorus powder was dispersed in 80 mL of anhydrous N-methylformamide and ultrasonically dispersed for 15 h. The resulting solution was the black phosphorus dispersion.

[0117] (2) Preparation of Catalyst: 0.05 g of alkyloxyethylene phenol ether was weighed into 10 mL of the black phosphorus dispersion prepared in step (1), and the mixture was ultrasonically treated for 10 min and stirred for 10 min.

[0118] (3) 0.015 g of sodium hypophosphite was added to step (2) and stirred for 1 h to obtain a uniform mixture.

[0119] (4) The mixture obtained in step (3) was placed in a 15 mL spray bottle and evenly sprayed on the surface of 10 g of microspherical carbon. The mixture was allowed to stand for 1 h to obtain a black phosphorus-modified activated carbon support.

[0120] (5) The black phosphorus-modified activated carbon support obtained in step (4) was placed in an oven at 60° C. and dried for 20 h.

[0121] (6) The support sample obtained in step (5) was placed in a tube furnace and calcined under a nitrogen atmosphere. The calcination temperature was increased to 260°C at a heating rate of 5°C / min and maintained for 2 hours. The nitrogen flow rate was maintained at 110 mL / min during the heating, holding, and cooling processes. After cooling to room temperature, the support sample was removed.

[0122] (7) Take a certain amount of PdCl2 and dissolve it in deionized water. At room temperature, use electrostatic adsorption to load metal palladium onto the black phosphorus-modified activated carbon in step (6), and then dry it at 80°C overnight.

[0123] (8) The dried sample obtained in step (7) was placed in a tube furnace in a mixed atmosphere containing 90% nitrogen and 10% hydrogen for reduction. Before heating, the remaining air in the tube furnace was first evacuated by vacuum, and the tube was purged three times with nitrogen to ensure safety. The tube furnace was then heated at a rate of 5°C / min to 200°C and maintained for 4 hours. After the reaction was completed and the temperature was cooled to room temperature, the sample was taken out and the catalyst sample finally obtained was recorded as 1wt% BP-Pd / C-P1-MC.

[0124] The performance evaluation was performed using an autoclave evaluation device. The reaction conditions were as follows: a certain mass of the above-mentioned catalyst (1wt% BP-Pd / C-P1-MC) was respectively loaded into an autoclave, the hydrogen pressure was 1MPa, the hydrogenation temperature was 80°C, and the mass concentration of the styrene ethanol solution was 50% (and the amount of catalyst was 0.1% of the mass of styrene). Hydrogen was introduced, and after the reactor was sealed, 0.25MPa of hydrogen was filled into the reactor and then released to replace the air in the reactor. After this process was repeated 5 times, the reactor was filled with hydrogen to the required pressure (1MPa). The reaction temperature was 80°C and the reaction time was 1h. After the reaction was completed, the reactor was cooled to room temperature, and finally the reaction liquid and the catalyst were separated by filtration and centrifugation.

[0125] In another embodiment of the present invention, styrene is dissolved in methanol solution to control the mass concentration to 50%, and the other steps are the same as above. The labeling test is 1 wt% BP-Pd / C-P1-MeOH.

[0126] In another embodiment of the present invention, styrene is dissolved in isopropanol solution to control the mass concentration to 50%, and the other steps are the same as above. The labeling test is 1wt% BP-Pd / C-P1-IPA.

[0127] The yields of ethylbenzene from styrene are shown in Table 5.

[0128] Table 5

[0129]

Claims

1. A method for preparing a sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst, characterized in that: (1) The black phosphorus raw material is ultrasonically treated to obtain a black phosphorus dispersion, and sodium hypophosphite is added to obtain a mixed solution; (2) Use a spray bottle to evenly spray the mixed solution on the surface of the carrier, and then dry and roast; (3) Loading noble metal salts on the carbon-based support after black phosphorus modification, drying and then reducing to obtain a sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst; The content of sodium hypophosphite is 0.01-10wt% of the precious metal mass; The calcination temperature is 200-700°C, the calcination time is 1-6 h, and the inert atmosphere used during the calcination process is selected from any one of argon, nitrogen and helium; The reduction is carried out by heating the mixture to 160-450° C. in a mixed atmosphere of hydrogen and nitrogen to carry out a reduction reaction; in the mixed atmosphere of hydrogen and nitrogen, the volume fraction of hydrogen is 5-10%.

2. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 1, wherein: The content of sodium hypophosphite is 0.01wt%-5wt% of the precious metal mass.

3. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 1, wherein: The content of sodium hypophosphite is any one of 0.05wt%, 0.1wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.8wt%, and 1.0wt% of the mass of the precious metal.

4. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 2, wherein: The noble metal / carbon base is selected from one or more of palladium / carbon, platinum / carbon, ruthenium / carbon, palladium / carbon and platinum / carbon composite materials, and the raw material of black phosphorus in the sodium hypophosphite-modified black phosphorus modified noble metal / carbon-based catalyst is selected from one or more of black phosphorus quantum dots, black phosphorus nanosheets and black phosphorus crystals.

5. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 4, wherein: The black phosphorus dispersion is obtained by uniformly dispersing the black phosphorus raw material in a solvent; the solvent is selected from one or more of N-methylpyrrolidone, N-vinylpyrrolidone, N-cycloethylpyrrolidone, N-octylpyrrolidone, formamide, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, methanol, ethanol, ethylene glycol, isopropanol, tert-butanol, acetone, 2-pentanone, and water; The carrier carbon base is selected from one or more of columnar carbon, spherical carbon, carbon molecular sieve, carbon nanotube, and carbon fiber.

6. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 5, wherein: The content of black phosphorus is 0.001-2.0 wt% of the mass of the carrier carbon base.

7. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 5, wherein: The content of black phosphorus is selected from any one of 0.1wt%, 0.2wt%, 0.3wt%, 0.5wt%, 0.8wt% and 1wt% of the mass of the carrier carbon base.

8. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 1, wherein: After the black phosphorus raw material is dispersed, a surfactant is selectively added. The surfactant is selected from one or more of polyvinyl pyrrolidone, Pluronic F127, polyethylene oxide-polypropylene oxide-polyethylene oxide triblock copolymer, alkyloxyethylene phenol ether, octadecyltrimethylammonium bromide, and sodium dodecylbenzenesulfonate. The mass fraction of the surfactant is 0.01wt%-10wt%.

9. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 8, wherein: The mass fraction of the surfactant is 0.01wt%-5wt%.

10. The method for preparing the sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst according to claim 8, characterized in that: The mass fraction of the surfactant is selected from any one of 0.625wt%, 1.25wt%, 2.5wt%, 3.75wt%, and 5.0wt%.

11. Use of a sodium hypophosphite-modified black phosphorus-modified noble metal / carbon-based catalyst prepared according to the method of any one of claims 1 to 10 in the catalytic reduction of styrene, characterized in that: The steps include: The solution containing styrene is transferred to the lining of an autoclave, and a black phosphorus-modified noble metal / carbon-based catalyst modified with sodium hypophosphite is added. In a closed environment, hydrogen is introduced. After the hydrogen replaces the air, hydrogen is continuously introduced. The reaction is carried out for 0.1-5 h at a pressure of 0.5-10 MPa and a temperature of 30°C-200°C to obtain a reduction product.

12. The use according to claim 11, characterized in that The mass ratio of the catalyst to styrene is 0.1-1:3-10; the solvent used in the solution containing styrene is selected from C1-C4 alcohol solvents, and the mass concentration of styrene is 1-50%.

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