Platinum-based high-entropy intermetallic compound catalyst, preparation thereof and application of platinum-based high-entropy intermetallic compound catalyst in propane dehydrogenation reaction

Abstract

The invention provides a silicon oxide loaded platinum-based high-entropy intermetallic compound catalyst for a propane catalytic dehydrogenation reaction. The catalyst is composed of a silicon oxide carrier and active metal nanoparticles loaded on silicon oxide. The preparation method of the catalyst comprises the following steps: fully drying a silicon oxide material to obtain a catalyst carrier; then, soluble metal salt is used as a precursor, and the heterogeneous catalyst is obtained through equivalent-volume impregnation, drying and reduction. A PtSn intermetallic compound is used as a substrate, the high-entropy intermetallic compound catalyst is prepared through a multi-metal doping strategy, the stability of the catalyst is greatly improved through a high-entropy structure, the electronic state of Pt can be adjusted through introduction of rare earth metal, desorption of propylene is promoted, the particle size of active components is reduced, and the catalytic activity of the catalyst is improved. The conversion rate and the stability of the catalyst are obviously improved. The catalyst shows good catalytic activity and selectivity at high temperature, shows excellent stability, and provides a novel high-activity and high-stability catalytic system for propylene preparation through propane dehydrogenation.

Description

Technical Field

[0001] The invention relates to a platinum-based high-entropy intermetallic compound catalyst and a preparation method thereof. The catalyst is mainly used for propane catalyst dehydrogenation reaction and belongs to the technical field of composite materials and catalysts. Background Art

[0002] Propylene is an important basic chemical raw material, widely used in the production of high-value chemicals such as polypropylene, propionaldehyde, and propylene oxide. In recent years, the demand for propylene has continued to grow. In industry, steam cracking and catalytic cracking of naphtha, methanol to olefins and propane catalytic dehydrogenation are the main ways to produce propylene. Compared with traditional olefin production processes, propane catalytic dehydrogenation technology has attracted more and more attention due to its simple reaction path and high propylene selectivity.

[0003] Platinum-based catalysts are important catalytic systems in propane catalytic dehydrogenation reactions. However, current commercial catalysts face problems such as low propylene selectivity, easy carbon deposition, and easy sintering of active metals at high temperatures. It is urgent to develop a catalyst with high propane conversion rate, good propylene selectivity, and good reaction stability.

[0004] Therefore, the present invention provides a platinum-tin-based high entropy intermetallic compound (HEI) catalyst supported on silicon oxide, which usually contains four or more elements and can maintain its intermetallic compound structure for a long time at high temperature. The introduction of rare earth metals can adjust the electronic state of Pt, promote the desorption of propylene, and reduce the particle size of the active component, significantly improving the conversion rate and selectivity of the catalyst. Summary of the invention

[0005] The present invention aims to provide a platinum-based high-entropy intermetallic catalyst and a preparation method thereof. The high-entropy catalyst is mainly used for catalytic dehydrogenation of propane to produce propylene. It can maintain excellent activity and stability at high temperatures, can reduce the cumbersome catalyst regeneration process, and greatly improve production efficiency.

[0006] The present invention uses PtSn intermetallic compound as the substrate and prepares a high entropy intermetallic compound catalyst through a multi-metal doping strategy. The high entropy structure greatly improves the stability of the catalyst. The introduction of rare earth metals can adjust the electronic state of Pt, promote the desorption of propylene, and reduce the particle size of the active component, significantly improving the conversion rate and stability of the catalyst. The catalyst exhibits good catalytic activity and selectivity at high temperatures, and exhibits excellent stability, providing a new high-activity and high-stability catalytic system for the dehydrogenation of propane to propylene.

[0007] The platinum-based high-entropy metal compound catalyst of the present invention is composed of a silicon oxide carrier and active metal nanoparticles supported on the silicon oxide, wherein the metal nanoparticle active component is PtSnM1M2M3, wherein M1 is one of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium, rhenium, iridium, platinum, gold, lead and bismuth, M2 is one of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium, rhenium, iridium, platinum, gold, lead and bismuth, M3 is one of yttrium, scandium, lanthanum, cerium, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, and the loading amount of the active metal is 0.1-5wt%. .

[0008] The platinum-based high entropy metal intermetallic compound catalyst of the present invention adopts an equal volume impregnation method, which comprises the following steps: fully drying the silicon oxide material, dissolving the metal active component precursor in water to prepare an equal volume impregnation solution; placing the fully dried silicon oxide carrier in the equal volume impregnation solution, stirring evenly and then impregnating, and then drying at 60-120° C. for 6-12 hours; and reducing the dried sample in a tube furnace in a H2 / Ar mixed gas for 0.5-2 hours to obtain a silicon oxide-supported platinum-based high entropy metal intermetallic compound catalyst.

[0009] In the active component, the molar ratio of platinum to metal ions Sn, M1, M2 or M3 is 1:0.1-10.

[0010] In the active components, the precursor of platinum is one of hydrated chloroplatinic acid, potassium chloroplatinate, platinum acetylacetonate, and ammonium chloroplatinate; the precursor of tin is one of tetrabutyltin, tin tetrachloride, stannous chloride, and stannous bromide.

[0011] The precursors in M1 and M2 in the active components are respectively one of aluminum nitrate, chromium nitrate, manganese nitrate, iron nitrate, iron chloride, cobalt nitrate, cobalt chloride, nickel nitrate, nickel chloride, copper nitrate, copper chloride, zinc nitrate, zinc chloride, gallium nitrate, germanium chloride, zirconium nitrate, ammonium molybdate, ruthenium chloride, rhodium chloride, rhodium nitrate, palladium chloride, silver nitrate, indium nitrate, indium chloride, hafnium nitrate, rhenium nitrate, iridium chloride, chloroauric acid, lead nitrate, and bismuth nitrate.

[0012] The precursor of M3 in the active component is one of yttrium nitrate, scandium nitrate, lanthanum nitrate, cerium nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, terbium nitrate, dysprosium nitrate, holmium nitrate, erbium nitrate, thulium nitrate, ytterbium nitrate and lutetium nitrate.

[0013] The impregnation is carried out at 10-40°C for 6-12 hours, with stirring every 30 minutes. The volume concentration of H2 in the H2 / Ar mixed gas is 5-80%. The reduction temperature is 500-600°C; and the reduction time is 0.5-2 hours.

[0014] Another object of the present invention is to provide an application of the platinum-based high entropy intermetallic compound catalyst in the catalytic propane dehydrogenation to propylene reaction. Using the platinum-based high entropy intermetallic compound as a catalyst, a mixed reaction gas of C3H8, H2, and Ar is introduced into a fixed bed reaction tube, wherein the volume ratio of C3H8, H2, and Ar is 16:16:68, and the space velocity of C3H8 is WHSV=1~40 h -1 , react at a constant temperature of 500~700℃ to obtain propylene.

[0015] The present invention has the following beneficial effects: The present invention uses silicon oxide as a carrier, and active metals such as Pt as active sites for propane conversion. After reduction, the metal components are evenly distributed on the surface of silicon oxide in the form of nanoparticles. The successful construction of supported nano high-entropy metal intermetallic compounds greatly improves the anti-sintering ability of the active components under high temperature conditions, and the rare earth metals in the components can further adjust the electronic state of Pt, improve the dispersion of the active components, significantly improve the catalytic activity and stability of propane dehydrogenation, and can effectively reduce the cumbersome regeneration process and improve production efficiency. In addition, the platinum-based high-entropy metal intermetallic compound catalyst provided by the present invention is easy to prepare and has good repeatability, providing a new industrializable catalytic system for the catalytic dehydrogenation reaction of propane. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The XRD diagrams of the catalysts of Example 1 and Comparative Example 2 of the present invention are shown in FIG. Figure 2 TEM image of the catalyst of Comparative Example 2 of the present invention; Figure 3 TEM image of the catalyst of Example 1 of the present invention; Figure 4 Elemental line scan of the catalyst of Example 1 of the present invention; Figure 5 This is a TEM image of the catalyst in Example 1 of the present invention after 100 hours of catalytic dehydrogenation reaction of propane. DETAILED DESCRIPTION

[0017] The preparation of the platinum-based high entropy intermetallic compound catalyst of the present invention and its catalytic performance for the catalytic dehydrogenation reaction of propane are further described below through specific examples.

[0018] Example 1 (1) Pretreatment of the carrier: The commercial silicon oxide material is fully dried, the saturated water absorption rate is measured, and it is ready for use; (2) Preparation of impregnation solution: Calculate the mass of active component precursor required based on the measured saturated water absorption rate and prepare it into an impregnation solution of equal volume; weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 11.4 mg of europium nitrate hexahydrate and dissolve them in 0.5 mL of water to obtain an impregnation solution; (3) Impregnation and drying: Add 0.5 g of fully dried silica carrier to the impregnation solution, stir evenly at 25°C and let it stand, stir once every 30 minutes, and place it in an oven at 80°C for 12 hours after 8 hours.

[0019] (4) Activation: The dried catalyst was loaded into a tubular furnace and reduced with 10% H2 / Ar mixed gas at 600℃ for 1h to obtain PtEu HEI catalyst, which was recorded as C-1.

[0020] Example 2 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 11.1 mg of cerium nitrate hexahydrate and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 ° C and let stand, stir once every 30 minutes, and place in an oven at 80 ° C for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 ° C for 1 hour with 10% H2 / Ar mixed gas to obtain PtCe HEI catalyst, which is recorded as C-2.

[0021] Example 3 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 11.5 mg of gadolinium nitrate hexahydrate and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 °C and let stand, stir once every 30 minutes, and place in an oven at 80 °C to dry for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 °C for 1 hour with 10% H2 / Ar mixed gas to obtain PtGd HEI catalyst, which is recorded as C-3.

[0022] Example 4 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 11.4 mg of holmium nitrate hexahydrate and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 ° C and let stand, stir once every 30 minutes, and place in an oven at 80 ° C for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 ° C for 1 hour with 10% H2 / Ar mixed gas to obtain PtHo HEI catalyst, which is recorded as C-4.

[0023] Example 5 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 8.7 mg of scandium nitrate hexahydrate and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 ° C and let stand, stir once every 30 minutes, and place in an oven at 80 ° C for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 ° C for 1 hour with 10% H2 / Ar mixed gas to obtain PtSc HEI catalyst, which is recorded as C-5.

[0024] Example 6 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, 3.5 mg of zinc chloride, and 11.4 mg of europium nitrate hexahydrate and dissolve them in 5 mL of water. Then add 5 g of fully dried silica carrier, stir evenly at 25 °C and let stand, stir once every 30 minutes, and place in an oven at 80 °C to dry for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 °C for 1 hour with 10% H2 / Ar mixed gas to obtain 0.1PtEu HEI catalyst, recorded as C-6.

[0025] Comparative Example 1 Weigh 13.3 mg of chloroplatinic acid hydrate and 9.0 mg of tin tetrachloride pentahydrate and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 °C and let stand, stir once every 30 minutes, and place in an oven at 80 °C to dry for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 °C for 1 hour with 10% H2 / Ar mixed gas to obtain a PtSn catalyst, which is recorded as C-7.

[0026] Comparative Example 2 Weigh 13.3 mg of chloroplatinic acid hydrate, 9.0 mg of tin tetrachloride pentahydrate, 5.6 mg of indium chloride, and 3.5 mg of zinc chloride and dissolve them in 0.5 mL of water. Then add 0.5 g of fully dried silica carrier, stir evenly at 25 °C and let stand, stir once every 30 minutes, and place in an oven at 80 °C to dry for 12 hours after 8 hours. The dried catalyst is loaded into a tubular furnace and reduced at 600 °C for 1 hour with 10% H2 / Ar mixed gas to obtain PtZnInSn catalyst, which is recorded as C-8.

[0027] Product structure characterization and performance evaluation Structural characterization: The catalysts of Example 1 and Comparative Example 2 were characterized by XRD. Figure 1Both exhibit the same diffraction peaks as the PtSn intermetallic compound, and no other metal diffraction peaks, indicating that intermetallic compounds are produced after reduction, and after rare earth metal doping, the peak intensity is weakened, proving that the active metal particles are reduced and the dispersion of the active components is improved.

[0028] The catalyst of Comparative Example 2 was characterized by TEM. Figure 2 The sample TEM image shows that the active metal is evenly distributed on the silicon oxide carrier in the form of nanoparticles with an average particle size of 4.0 nm.

[0029] The catalyst of Example 1 was characterized by TEM. Figure 3 The sample TEM image shows that the active metal is evenly distributed on the silicon oxide carrier in the form of nanoparticles with an average particle size of 3.3nm, indicating that the doping of rare earth metals can reduce the size of nanoparticles, which is beneficial to the exposure of active sites and thus improve the catalytic activity.

[0030] The catalyst obtained in Example 1 was subjected to elemental line scanning analysis, and the results were as follows: Figure 4 The simultaneous presence of five elements, Pt, Zn, In, Sn, and Eu, within a single nanoparticle indicates the successful synthesis of a high-entropy catalyst.

[0031] The catalyst obtained in Example 1 was subjected to TEM characterization after 100 h of propane catalytic dehydrogenation reaction. Figure 5 The active metal is still evenly dispersed on the surface of the silicon oxide carrier, with an average particle size of 3.2 nm, which has no significant change compared with before the reaction, indicating that the catalyst has good anti-sintering ability.

[0032] Performance evaluation: The catalysts prepared in Examples 1-6 and Comparative Examples 1-2 were used in the reaction of catalyzing propane dehydrogenation to produce propylene, so as to illustrate the catalytic performance of different catalysts in the reaction of catalyzing propane dehydrogenation.

[0033] A mixed reaction gas was introduced into the fixed bed reaction tube, wherein the volume ratio of H2:C3H8:Ar was 16:16:68, and the propane space velocity was WHSV = 3.7h -1 The system was maintained at a constant temperature of 580°C for reaction. The outlet of the fixed bed reaction tube was connected to an Agilent GC-8860 gas chromatograph to analyze the product components after 1 hour of catalytic dehydrogenation reaction, obtain the content of each component in the product and calculate the conversion rate and selectivity. The reaction data of different catalysts are shown in Table 1.

[0034] As can be seen from Table 1, the catalysts prepared in the present invention have excellent catalytic activity and selectivity for the propane catalytic dehydrogenation reaction. Compared with the binary and quaternary component catalysts, the high entropy metal intermetallic compound catalysts doped with rare earth metals show better conversion rate and selectivity, and when the Pt content is 0.1wt% (Example 6, lower than the 0.3wt% commonly used in industry), it can still maintain excellent activity.

[0035] Example 1 and Comparative Examples 1 and 2 are used as examples to illustrate that the high entropy metal intermetallic compound catalyst has better stability. The stability data of the reaction is shown in Table 2.

[0036] It can be seen from Table 2 that compared with binary and quaternary component catalysts, high entropy metal intermetallic compound catalysts doped with rare earth metals exhibit better stability.

[0037] The long-term stability of the high entropy intermetallic compound catalyst is illustrated by Example 1. The reaction data is shown in Table 3.

[0038] In summary, the high entropy intermetallic compound catalyst prepared by the present invention exhibits excellent catalytic activity and stability in the propane catalytic dehydrogenation reaction. The high entropy structure effectively inhibits the sintering of the active metal, allowing it to maintain long-term stability at high temperatures. The doping of rare earth metals improves the dispersibility of the active components and can provide electrons to the highly electronegative Pt, promoting the desorption of electron-rich propylene, and improving the conversion rate and stability of the catalyst. At the same time, the catalyst has the advantages of simple preparation method, high stability, good selectivity, and strong practicality, providing a reliable industrial catalytic system for the catalytic dehydrogenation of propane to propylene.

Claims

1. A platinum-based high entropy intermetallic compound catalyst, characterized in that: The invention is composed of a silicon oxide carrier and active metal nanoparticles loaded on the silicon oxide, wherein the active component of the metal nanoparticles is PtSnM1M2M3, wherein M1 is one of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium, rhenium, iridium, platinum, gold, lead and bismuth, M2 is one of aluminum, chromium, manganese, iron, cobalt, nickel, copper, zinc, gallium, germanium, zirconium, molybdenum, ruthenium, rhodium, palladium, silver, indium, hafnium, rhenium, iridium, platinum, gold, lead and bismuth, M3 is one of yttrium, scandium, lanthanum, cerium, cerium, praseodymium, neodymium, samarium, europium, gadolinium, terbium, dysprosium, holmium, erbium, thulium, ytterbium and lutetium, and the loading amount of the active metal is 0.1-5wt%; The catalyst is prepared by an equal volume impregnation method, which includes the following steps: fully drying the silicon oxide material, dissolving the metal active component precursor in water to prepare an equal volume impregnation solution; placing the fully dried silicon oxide carrier in an equal volume impregnation solution, stirring it evenly and then impregnating it, and then drying it at 60-120° C. for 6-12 hours; the dried sample is reduced in a tubular furnace with a H2 / Ar mixed gas for 0.5-2 hours to obtain a silicon oxide-supported platinum-based high entropy metal intermetallic compound catalyst.

2. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: In the active component, the molar ratio of platinum to metal ions Sn, M1, M2 or M3 is 1:0.1-10.

3. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: In the active components, the precursor of platinum is one of hydrated chloroplatinic acid, potassium chloroplatinate, platinum acetylacetonate, and ammonium chloroplatinate; the precursor of tin is one of tetrabutyltin, tin tetrachloride, stannous chloride, and stannous bromide.

4. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: The precursors in M1 and M2 in the active components are respectively one of aluminum nitrate, chromium nitrate, manganese nitrate, iron nitrate, iron chloride, cobalt nitrate, cobalt chloride, nickel nitrate, nickel chloride, copper nitrate, copper chloride, zinc nitrate, zinc chloride, gallium nitrate, germanium chloride, zirconium nitrate, ammonium molybdate, ruthenium chloride, rhodium chloride, rhodium nitrate, palladium chloride, silver nitrate, indium nitrate, indium chloride, hafnium nitrate, rhenium nitrate, iridium chloride, chloroauric acid, lead nitrate, and bismuth nitrate.

5. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: The precursor of M3 in the active component is one of yttrium nitrate, scandium nitrate, lanthanum nitrate, cerium nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, samarium nitrate, europium nitrate, gadolinium nitrate, terbium nitrate, dysprosium nitrate, holmium nitrate, erbium nitrate, thulium nitrate, ytterbium nitrate and lutetium nitrate.

6. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: The soaking is carried out at 10-40° C. for 6-12 hours, with stirring every 30 minutes.

7. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: The volume concentration of H2 in the H2 / Ar mixed gas is 5~80%.

8. The platinum-based high entropy intermetallic compound catalyst according to claim 1, characterized in that: The reduction temperature is 500~600℃; the reduction time is 0.5~2h.

9. Use of the platinum-based high entropy intermetallic compound catalyst as claimed in claim 1 in catalyzing the dehydrogenation of propane to produce propylene.

10. Use of the platinum-based high entropy intermetallic compound catalyst as claimed in claim 9 in catalytic propane dehydrogenation to propylene reaction, characterized in that: Using platinum-based high entropy metal intermetallic compounds as catalysts, a mixed reaction gas of C3H8, H2, and Ar was introduced into the fixed bed reaction tube, where the volume ratio of C3H8, H2, and Ar was 16:16:68, and the space velocity of C3H8 was WHSV = 1~40 h -1 , propylene is obtained by catalytic dehydrogenation reaction at a constant temperature of 500~700℃.

Images