Metal phosphide catalysts and methods of making, methods of making gamma valerolactone
By preparing phosphorus-doped porous carbon, the agglomeration and sintering of metal particles at high temperatures were suppressed, the catalytic activity of the catalyst was improved, and the preparation efficiency of gamma-valerate was increased.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2024-03-21
- Publication Date
- 2026-06-19
Abstract
Description
Technical Field
[0001] This invention relates to the field of biochar production, and in particular to a method for preparing a metal phosphide catalyst. Background Technology
[0002] The rapid development of human society has accelerated the consumption of fossil fuels and triggered a series of climate and environmental problems, making the vigorous development of renewable energy an urgent priority. Gamma-valerate lactone (GVL) is a biomass-based chemical and fuel with great application potential. Currently, GVL is mainly obtained by hydrogenating levulinic acid (LA), a biomass hydrolysis product, under high temperature (>200 °C) and high hydrogen pressure (>2 MPa) conditions. However, the acidity of levulinic acid itself and the harsh reaction conditions can easily lead to catalyst deactivation.
[0003] To address this, existing technologies have employed a method of combining hydrophobic thiol ligands with metal precursors to place the metal within the hydrophobic core of the micelles. This method, involving hydrothermal self-assembly followed by pyrolysis, has led to the preparation of S-doped single, double, and triple metal-confined mesoporous carbon catalysts. This in-situ synthesis method, combining metals with organic precursors, effectively confines metal particles uniformly within the pores. However, in this method, metal ions can easily disrupt the equilibrium of the synthesis system, causing severe particle aggregation and pore collapse. Furthermore, the expensive precursor materials and complex synthesis process significantly increase the cost of catalyst synthesis, thus hindering the preparation of gamma-valerate. Summary of the Invention
[0004] The present invention aims to at least solve one of the technical problems existing in the prior art. To this end, the present invention proposes a method for preparing a metal phosphide catalyst. This method prepares phosphorus-doped porous carbon by pyrolyzing a carbon precursor and a phosphorus-containing precursor. By utilizing the binding effect of phosphorus functional groups with metal ions, the migration and agglomeration of metal particles under high temperature conditions are inhibited, thereby avoiding sintering of metal particles.
[0005] A method for preparing a metal phosphide catalyst according to a first aspect of the present invention includes the following steps:
[0006] S1. After uniformly mixing the carbon-containing precursor and the phosphorus-containing precursor solution, the mixture is dried to obtain a solid product.
[0007] The carbon-containing precursor is any one or a combination of at least two of carbon black, activated carbon, biochar, biomass, and plastics; the phosphorus-containing precursor is any one or a combination of at least two of phosphoric acid, phytic acid, potassium phosphate, potassium hydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, ammonium phosphate, and ammonium hydrogen phosphate; and the mixing mass ratio of the carbon-containing precursor to the phosphorus-containing precursor is in the range of 1:1 to 1:5.
[0008] S2. The solid product is pyrolyzed under an inert atmosphere, wherein the inert atmosphere is any one of nitrogen, helium, argon, carbon monoxide, and carbon dioxide, and the temperature range for pyrolyzing the solid product under the inert atmosphere is 400℃ to 700℃.
[0009] S3. Wash and dry the solid product after pyrolysis to obtain phosphorus-doped carbon material;
[0010] S4. After uniformly mixing the metal salt solution with the obtained phosphorus-doped carbon material, the mixture is dried and then reduced in an atmosphere containing hydrogen gas mixture to obtain a metal phosphide catalyst.
[0011] Specifically, the metal salt solution is any one of Ni(NO3)2, NiCl2, (CH3COO)2Ni, Co(NO3)2, CoCl2, (CH3COO)2Co, Fe(NO3)2, FeCl2, and (CH3COO)2Fe. Furthermore, after the metal salt solution is uniformly mixed with the obtained phosphorus-doped carbon material, it is dried and reduced in a hydrogen-containing mixed gas atmosphere at a temperature range of 400℃ to 700℃.
[0012] In practical applications, preferably, wood chips are used as a C-containing precursor material, H3PO4 is used as a P-containing precursor material, and metal Ni is used as a support. A method for preparing a metal phosphide catalyst specifically includes the following steps.
[0013] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h, and dry the mixture to obtain a solid product.
[0014] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 °C under a nitrogen atmosphere (40 mL / min).
[0015] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0016] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0017] Due to their excellent hydrothermal stability, high specific surface area, well-developed pore structure, and easily adjustable surface chemistry, porous carbon materials are ideal catalyst supports. Therefore, in the current technology, various elements are usually pyrolyzed with biomass raw materials to form carbon materials doped with various elements, thereby meeting various special application purposes.
[0018] However, unlike oxide supports, the interaction between metals and traditional carbon materials is relatively weak. Therefore, metal particles, especially non-precious metals such as Ni / Co / Fe, are prone to sintering under high temperature conditions, which greatly weakens the catalytic activity of the catalyst.
[0019] In this invention, phosphorus-doped porous carbon is prepared by pyrolysis of carbon precursor and phosphorus-containing precursor. During this process, phosphorus-containing functional groups are formed on the carbon material. These phosphorus-containing functional groups can adsorb metal ions such as Ni2+ during the mixing process with metal salt solution and bind firmly to them, inhibiting the migration and agglomeration of metal particles under high temperature environment, thereby avoiding sintering of metal particles.
[0020] Meanwhile, during the hydrogen reduction process, as the heating temperature increases, the phase composition of the metal will change from the metallic state to metal phosphide. The transition metal phosphide, due to P doping into the metal lattice, will change the electronic state of the metal, thereby changing the activation performance of the metal sites for hydrogen and improving the activity of catalytic hydrogenation.
[0021] Furthermore, transition metal phosphides have triangular prisms as structural units, which are approximately spherical. This spherical structure can expose more coordinated unsaturated surface atoms and has a higher surface active site density, thus exhibiting better catalytic activity and thereby improving the yield of gamma-valerol.
[0022] According to a second aspect of the present invention, a metal phosphide catalyst is prepared using any of the above-described methods for preparing metal phosphide catalysts.
[0023] A method for preparing gammavalproic acid according to a third aspect of the present invention includes the following steps:
[0024] A mixture of levulinic acid, catalyst, and deionized water was obtained to form a mixed solution. The mixed solution was then heated under a high-pressure hydrogen atmosphere to obtain gamma-valerate. The catalyst used was the metal phosphide catalyst as described in claim 9, the hydrogen pressure was 3 MPa, the heating temperature was 120°C, and the heating time was 2 h.
[0025] Beneficial effects
[0026] This invention prepares phosphorus-doped porous carbon by pyrolysis of carbon precursor and phosphorus-containing precursor. By utilizing the binding effect of phosphorus functional groups with metal ions, the migration and aggregation of metal particles under high temperature environment is inhibited, thereby effectively avoiding sintering of metal particles and improving the yield of target catalytic products. Detailed Implementation
[0027] Example 1
[0028] In this embodiment, the effect of different metal-supported catalysts on the hydrogenation reaction of levulinic acid (LA) was studied. Specifically, metal phosphide catalysts were prepared using Ni(NO3)2, NiCl2, (CH3COO)2Ni, Co(NO3)2, CoCl2, (CH3COO)2Co, Fe(NO3)2, FeCl2, and (CH3COO)2Fe, respectively. These different metal phosphide catalysts were then used in the hydrogenation reaction of levulinic acid (LA). The specific steps are as follows:
[0029] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h, and dry the mixture to obtain a solid product.
[0030] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 °C under a nitrogen atmosphere (40 mL / min).
[0031] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0032] Step 4: Add a 20% (w / w) metal salt solution to a round-bottom flask containing 40 g of ethanol, add the prepared PAC to the solution, stir at 45 °C for 12 h, dry by rotary evaporation, and then reduce at 600 °C with a 10% H2 / N2 gas flow rate for 2 h to finally obtain the metal phosphide catalyst.
[0033] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0034] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0035] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0036] The results are shown in Table 1:
[0037] Table 1: Effect of catalysts with different metal supports on the hydrogenation reaction of levulinic acid (LA)
[0038] ;
[0039] As can be seen from the results shown in Table 1 above, the hydrogenation effects of catalysts prepared by different types of metal support vary greatly on levulinic acid (LA). Among them, the catalyst prepared by metal Ni support has the best hydrogenation effect on levulinic acid (LA), the highest GVL yield, and the best catalytic effect. The catalyst prepared by metal Co support has the second best hydrogenation effect on levulinic acid (LA), while the catalyst prepared by metal Fe support has a very limited effect on hydrogenation of levulinic acid (LA).
[0040] Example 2
[0041] In this embodiment, the effect of catalysts prepared with different inert atmosphere sources on the hydrogenation reaction of levulinic acid (LA) is studied. Specifically, metal phosphide catalysts are prepared under inert gas atmospheres using nitrogen, helium, and argon, respectively. The different metal phosphide catalysts prepared are then used in the hydrogenation reaction of levulinic acid (LA). The specific steps are as follows:
[0042] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h, and dry the mixture to obtain a solid product.
[0043] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere.
[0044] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0045] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0046] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0047] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0048] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0049] The results are shown in Table 2:
[0050] Table 2: Effect of catalysts prepared with different inert atmosphere sources on the hydrogenation reaction of levulinic acid (LA)
[0051] ;
[0052] As can be seen from the results shown in Table 2 above, the metal phosphide catalysts prepared with different inert atmosphere sources have no significant effect on the hydrogenation effect of levulinic acid (LA).
[0053] Example 3
[0054] In this embodiment, the effect of different pyrolysis temperatures on the hydrogenation reaction of levulinic acid (LA) was explored. The specific steps are as follows:
[0055] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h, and dry the mixture to obtain a solid product.
[0056] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere. The pyrolysis temperatures are 300 ℃, 400 ℃, 450 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃ and 900 ℃ respectively.
[0057] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0058] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0059] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0060] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0061] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0062] The results are shown in Table 3:
[0063] Table 3: Effect of catalysts prepared at different pyrolysis temperatures on the hydrogenation reaction of levulinic acid (LA)
[0064] ;
[0065] As can be seen from the results shown in Table 3 above, the metal phosphide catalysts prepared at pyrolysis temperatures between 400 and 700 °C have better catalytic effects, and the catalytic effect is best at 450 °C.
[0066] Example 4
[0067] In this embodiment, the effect of catalysts prepared at different reduction temperatures on the hydrogenation reaction of levulinic acid (LA) is explored. The specific steps are as follows:
[0068] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h. After drying the mixture, a solid product is obtained.
[0069] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere.
[0070] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0071] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h. The reduction temperatures are set at 300 ℃, 400 ℃, 500 ℃, 600 ℃, 700 ℃, 800 ℃, and 900 ℃, respectively, to finally obtain 20Ni / PAC-600 catalysts.
[0072] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0073] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0074] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0075] The results are shown in Table 4:
[0076] Table 4: Effect of catalysts prepared at different reduction temperatures on the hydrogenation reaction of levulinic acid (LA)
[0077] ;
[0078] As can be seen from the results shown in Table 4 above, the catalytic rate and yield both show a trend of first increasing and then decreasing with the increase of reduction temperature, and the catalytic effect is best at a reduction temperature of 600 ℃.
[0079] Example 5
[0080] This embodiment explores the effect of catalysts prepared from different C-containing precursor materials on the hydrogenation reaction of levulinic acid (LA). The specific operations are as follows:
[0081] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) carbon-containing precursor and stir evenly, then impregnate at 200 ℃ for 12 h, and dry the mixture to obtain a solid product. The carbon-containing precursors are carbon black, activated carbon, biochar, biomass and plastic.
[0082] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere.
[0083] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0084] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0085] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0086] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0087] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0088] The results are shown in Table 5:
[0089] Table 5: Effect of catalysts prepared from different C-containing precursor materials on the hydrogenation reaction of levulinic acid (LA)
[0090] ;
[0091] As can be seen from the results shown in Table 5 above, the metal phosphide catalysts prepared from different C-containing precursor materials generally have good catalytic effects.
[0092] Example 6
[0093] In this embodiment, the effect of catalysts prepared from different P-containing precursors on the hydrogenation reaction of levulinic acid (LA) was explored. The specific operations are as follows:
[0094] Step 1: Weigh 18.83 g (85%) of phosphorus-containing precursor solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) of sawdust and stir evenly, then soak at 200 ℃ for 12 h. After drying the mixture, a solid product is obtained. The phosphorus-containing precursors are phosphoric acid, phytic acid, potassium phosphate, potassium hydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, ammonium phosphate, and ammonium hydrogen phosphate.
[0095] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere.
[0096] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0097] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0098] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0099] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0100] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0101] Comparative Example 1: Replace the P-containing precursor with a P-free precursor: for example, use zinc chloride solution as a comparison.
[0102] The results are shown in Table 6:
[0103] Table 6: Effect of catalysts prepared from different P-containing precursor materials on the hydrogenation reaction of levulinic acid (LA)
[0104] ;
[0105] As shown in Table 6, the metal phosphide catalysts prepared from different P-containing precursor materials all exhibited good catalytic effects, while the catalyst prepared using zinc chloride showed poor conversion and yield. This indicates that the metal phosphide catalysts prepared from P-containing precursors have better catalytic effects.
[0106] Among them, the catalyst prepared using phosphoric acid as a P-containing precursor showed the best effect, with a GVL yield as high as 99.9%.
[0107] Example 7
[0108] In this embodiment, the effect of catalysts prepared with different mass ratios of mixtures on the hydrogenation reaction of levulinic acid (LA) was explored. The specific steps are as follows:
[0109] Step 1: Weigh 18.83 g (85%) H3PO4 solution into a 250 mL beaker, add 30 mL of deionized water and mix, add 4.0 g (60-80 mesh) sawdust and stir well, then soak at 200 ℃ for 12 h. After drying the mixture, a solid product is obtained. The mass ratio of sawdust to phosphoric acid is 1:0.1, 1:0.5, 1:1, 1:3, 1:4.7, 1:5, 1:8, and 1:10, respectively.
[0110] Step 2: Take 5 g of the dried solid product and put it into a U-shaped quartz tube. Pyrolyze it for 1 h in a tubular furnace at 450 ℃ under an inert gas flow (40 mL / min) atmosphere.
[0111] Step 3: Then remove the U-shaped tube and cool it to room temperature. Then wash the solid product after pyrolysis with deionized water until neutral, and dry it at 105 °C to obtain P-doped carbon material PAC.
[0112] Step 4: Add 20% Ni(NO3)2·6H2O to a round-bottom flask containing 40 g of ethanol. Add the prepared PAC to the above solution, stir at 45 ℃ for 12 h, dry by rotary evaporation, and then reduce at 600 ℃ with a gas flow rate of 10% H2 / N2 for 2 h to finally obtain the 20Ni / PAC-600 catalyst.
[0113] Step 5: Add 200 mg LA, 100 mg catalyst and 10 g deionized water to the autoclave.
[0114] Step 6: After removing the remaining air in the autoclave with hydrogen, pump 3 MPa of hydrogen into the autoclave and heat at 120 °C for 2 h.
[0115] Step 7: After cooling to room temperature, wash the reactor with ethanol, add cyclohexanol as an internal standard, and detect by gas chromatography.
[0116] The results are shown in Table 7:
[0117] Table 7: Effect of catalysts prepared with different mass ratios of mixtures on the hydrogenation reaction of levulinic acid (LA)
[0118] ;
[0119] The results shown in Table 7 above indicate that the effect is better when the mass ratio of the mixture is between 1:1 and 1:5. As the amount of phosphoric acid is further increased, the reactivity decreases to some extent.
[0120] In the description of this specification, references to terms such as "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example.
[0121] Although embodiments of the invention have been shown and described, those skilled in the art will understand 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 claims and their equivalents.
Claims
1. A method for preparing a metal phosphide catalyst, characterized in that, Includes the following steps: S1. The carbon-containing precursor and the phosphorus-containing precursor solution are mixed evenly and then dried to obtain a solid product. The carbon-containing precursor is any one or a combination of at least two of carbon black, activated carbon, biochar, biomass and plastics. S2. The solid product is pyrolyzed under an inert atmosphere; S3. Wash and dry the solid product after pyrolysis to obtain phosphorus-doped carbon material; S4. After uniformly mixing the metal salt solution with the obtained phosphorus-doped carbon material, the mixture is dried and then reduced in an atmosphere containing hydrogen gas mixture to obtain a metal phosphide catalyst. The metal salt solution is any one of Ni(NO3)2, NiCl2, (CH3COO)2Ni, Co(NO3)2, CoCl2, (CH3COO)2Co, Fe(NO3)2, FeCl2, and (CH3COO)2Fe.
2. The method for preparing a metal phosphide catalyst according to claim 1, characterized in that, The phosphorus-containing precursor is any one or a combination of at least two of the following: phosphoric acid, phytic acid, potassium phosphate, potassium hydrogen phosphate, sodium phosphate, sodium hydrogen phosphate, ammonium phosphate, and ammonium hydrogen phosphate.
3. The method for preparing a metal phosphide catalyst according to claim 1, characterized in that, The mass ratio of carbon-containing precursor to phosphorus-containing precursor in S1 ranges from 1:1 to 1:
5.
4. The method for preparing a metal phosphide catalyst according to claim 1, characterized in that, The inert atmosphere is any one of nitrogen, helium, or argon.
5. The method for preparing a metal phosphide catalyst according to claim 1, characterized in that, The temperature range for pyrolysis of the solid product in S2 under an inert atmosphere is 400℃ to 700℃.
6. The method for preparing a metal phosphide catalyst according to claim 1, characterized in that, In step S4, the metal salt solution is mixed evenly with the obtained phosphorus-doped carbon material and then dried. The temperature range for reduction in the atmosphere of hydrogen-containing mixed gas is 400℃ to 700℃.
7. A metal phosphide catalyst, characterized in that, The metal phosphide catalyst prepared by any one of the preparation methods of the metal phosphide catalyst according to claims 1-6.
8. A method for preparing gamma valerolactone, characterized by, Includes the following steps: A mixture of levulinic acid, catalyst, and deionized water is obtained to obtain a mixed solution. The mixed solution was heated under a high-pressure hydrogen atmosphere to obtain gammavalactone; The catalyst used is the metal phosphide catalyst as described in claim 7, with a hydrogen pressure of 3 MPa, a heating temperature of 120°C, and a heating time of 2 hours.