A supported bimetallic alloy catalyst, its preparation method and use

Abstract

The application belongs to the technical field of supported catalysts, and discloses a supported bimetallic alloy catalyst, a preparation method and application thereof; the catalyst is uniformly loaded with bimetallic alloy nanoparticles on a SiO2 or Al2O3 carrier, the nanoparticles are formed by diffusing an auxiliary metal onto an active metal in an atomic diffusion manner, and the particle size is sub-nanometer to 1-2 nanometer level; the preparation process is to prepare a supported active metal, and to prepare a supported auxiliary metal precursor; after high-temperature calcination in air, a supported auxiliary metal oxide is obtained; then the supported active metal and the supported auxiliary metal oxide are physically mixed uniformly, and then reduced at high temperature in a hydrogen atmosphere; the supported bimetallic alloy catalyst has good catalytic performance and sintering resistance under high-temperature conditions; the catalyst is suitable for alkane dehydrogenation, especially propane dehydrogenation to propylene under a hydrogen atmosphere, and has excellent catalytic activity and selectivity, and a slow deactivation rate.

Description

Technical Field

[0001] This invention belongs to the field of supported catalyst technology, specifically relating to a bimetallic alloy catalyst supported on SiO2 (or Al2O3), and a method for preparing the catalyst. Furthermore, this catalyst can also be applied to the dehydrogenation of low-carbon alkanes to olefins. Background Technology

[0002] Low-chain olefins are important chemical feedstocks, especially propylene (C3H6), which is a crucial raw material for producing a wide range of petrochemical products such as acrolein, acetone, polypropylene, and propylene oxides. With the rapid depletion of fossil fuels, traditional propylene production methods, such as fluidized bed catalytic cracking and steam cracking, can no longer meet the ever-growing demand. Given the widening supply-demand gap for propylene, there is an urgent need for alternative and efficient propylene production methods. Direct propane dehydrogenation to propylene (PDH) is considered one of the most promising "targeted" propylene production methods.

[0003] Propane dehydrogenation is a strongly endothermic reaction, requiring sufficient heat input to ensure adequate conversion. Commercially, temperatures are typically set between 550-750°C to achieve satisfactory propylene yields. With the development of propane dehydrogenation processes, several technologies, including UOP Oleflex, Lummus Catofin, PDH, STAR, and FBD, have been industrialized, with Catofin and Oleflex processes being the most widely used in commercial plants. For the Catofin process, chromium / alumina-based catalysts have become the core catalysts due to their low cost and high catalytic activity. However, due to the toxicity of chromium-based catalysts, more environmentally friendly Pt-based catalysts have been widely developed. UOP has developed the Oleflex process based on platinum / aluminum-based catalysts. The reactor is an adiabatic moving bed, employing interstage reheating in a continuous furnace. The recycling of hydrogen reduces coke formation. Due to platinum's affinity for aliphatic CH bonds, Pt-based catalysts exhibit good activity in PDH. However, Pt-based catalysts are prone to carbon deposition and sintering at high temperatures, leading to rapid deactivation, which has become one of the main challenges of existing processes.

[0004] To alleviate the problems of catalyst coking and sintering, researchers have designed various microstructures for catalysts. The metal-based PDH reaction mechanism can be divided into several steps: reactant adsorption, surface reaction, propylene desorption, and site regeneration. Different steps may occur on the catalyst during the PDH reaction. High temperatures can lead to side reactions such as hydrogenolysis, cracking, hydrogenation, and coking. Propane dehydrogenation is a structure-insensitive reaction, meaning that every surface atom is an active site; therefore, the reaction rate is proportional to the dispersion, meaning that small particles with high surface area are advantageous for propane dehydrogenation. However, as the diameter of the supported metal particles gradually decreases, the relative proportion of exposed atoms in different local environments also changes. According to geometric models, as the size of the metal particles gradually decreases, the total proportion of exposed low-coordination metal atoms increases, leading to side reactions and reduced selectivity. Therefore, bimetallic strategies have been widely used based on the geometric and electronic characteristics of the contribution of the promoter metal to the active metal. Different metal promoters are typically selected based on factors such as electronegativity, cost, and toxicity, and different preparation methods and metal loadings may result in different structures. The most common method for preparing bimetallic catalysts is the co-impregnation method, in which two metal precursors are mixed in a solution and then co-impregnated in a support. This method is simple and quick, but the resulting particles are often large with a wide particle size distribution, which leads to a decrease in the activity of the dehydrogenation reaction and the selectivity for propylene. Summary of the Invention

[0005] The present invention addresses the technical problem of existing alkane dehydrogenation catalysts being prone to sintering and carbon deposition and deactivation under high temperature conditions. It provides a supported bimetallic alloy catalyst, its preparation method and application, resulting in a supported bimetallic alloy catalyst with high activity and small particle size (sub-nanometer to 1-2 nanometers), which exhibits good catalytic performance and anti-sintering ability under high temperature conditions.

[0006] To solve the above-mentioned technical problems, the present invention is implemented through the following technical solution:

[0007] According to one aspect of the present invention, a supported bimetallic alloy catalyst is provided, comprising a SiO2 support or an Al2O3 support, characterized in that bimetallic alloy nanoparticles are uniformly supported on the SiO2 support or the Al2O3 support, the bimetallic alloy nanoparticles being formed by diffusion of an auxiliary metal onto an active metal via atomic diffusion, the particle size of the bimetallic alloy nanoparticles being sub-nanometer to 1-2 nanometer scale; the active metal being one of transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and the auxiliary metal being one of transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and In, Ga, Sn, Bi, and Pb, and the active metal and the auxiliary metal being different metals.

[0008] Furthermore, based on the carrier mass, the mass percentage of the active metal is 0.025%-20%.

[0009] Furthermore, the molar ratio of the auxiliary metal to the active metal is 0.1 to 5.

[0010] According to another aspect of the present invention, a method for preparing the above-mentioned supported bimetallic alloy catalyst is provided, comprising the following steps:

[0011] The precursor containing the active metal was dissolved in deionized water and the pH was adjusted. Then it was impregnated on the SiO2 support or the Al2O3 support while being added dropwise and stirred. Subsequently, it was sonicated to ensure full impregnation. After standing at room temperature, it was completely dried to obtain the loaded active metal.

[0012] The precursor containing the additive metal is dissolved in deionized water, then immersed in the SiO2 support or the Al2O3 support while being added dropwise and stirred. The mixture is then sonicated to ensure thorough immersion, allowed to stand at room temperature, and then completely dried to obtain the loaded additive metal precursor. The loaded additive metal precursor is then calcined in air at high temperature to obtain the loaded additive metal oxide.

[0013] The supported active metal and the supported auxiliary metal oxide are physically mixed uniformly, and then reduced at high temperature in a hydrogen atmosphere to obtain the supported bimetallic alloy catalyst.

[0014] Preferably, during the process of dissolving the precursor containing the active metal in deionized water and adjusting the pH: for SiO2 support, the pH is adjusted to 10-13; for Al2O3 support, the pH is adjusted to 2-4.

[0015] Preferably, in the process of preparing the loaded active metal and the loaded auxiliary metal precursor, the time for standing at room temperature after full impregnation is 6-12 hours.

[0016] Preferably, the temperature for high-temperature calcination in air is 400-700℃.

[0017] Preferably, the temperature for high-temperature reduction in a hydrogen atmosphere is 300-800℃.

[0018] According to another aspect of the present invention, the application of the above-described supported bimetallic alloy catalyst in alkane dehydrogenation is provided.

[0019] Preferably, the above-mentioned supported bimetallic alloy catalyst is used in the propane dehydrogenation to propylene process as follows:

[0020] The granular supported bimetallic alloy catalyst was loaded into a fixed-bed reactor and pretreated with hydrogen. After pretreatment, the reaction was carried out at 550-650°C. The molar ratio of hydrogen to propane in the reaction gas was 0-2, with nitrogen as the equilibrium gas, and the total gas volume remained constant. The feed rate was based on the propane space velocity, ranging from 1 to 30 h⁻¹. -1 between.

[0021] The beneficial effects of this invention are:

[0022] Typically, nanocatalysts exhibit excellent catalytic performance; however, due to their high surface free energy, these small nanocatalysts are prone to aggregation and sintering during reactions. The catalyst prepared in this invention contains a uniformly distributed bimetallic alloy. Its highly alloyed structure and sub-nanometer particle size ensure good dispersion of the active metal, providing numerous exposed sites and thus excellent catalytic activity. Simultaneously, the high dispersion of the metal alloy on the support surface also gives it good resistance to sintering at high temperatures.

[0023] This invention is the first to employ a physical blending method to form a bimetallic nanoalloy structure in situ during catalyst reduction. The invention utilizes a co-impregnation method combined with physical blending diffusion, which is simple to operate, highly reproducible, and has significant industrial implications.

[0024] The bimetallic alloy catalyst prepared by this invention is suitable for alkane dehydrogenation, especially propane dehydrogenation to propylene under a hydrogen atmosphere. It has excellent activity and selectivity, and the propylene selectivity can reach more than 95% under high temperature conditions, with a slow deactivation rate. Attached Figure Description

[0025] Figure 1 This is a propane conversion diagram of SiO2-supported PtZn alloy catalysts with different Zn / Pt molar ratios in the embodiments of the present invention.

[0026] Figure 2 This is a propane conversion diagram of SiO2-supported PtZn alloy catalysts with different Zn / Pt molar ratios in the embodiments of the present invention.

[0027] Figure 3 This is a performance graph of the SiO2-supported PtZn alloy catalyst in the propane dehydrogenation reaction at 600℃ for 10 hours in an embodiment of the present invention.

[0028] Figure 4 This is a performance diagram of PtZn alloy catalysts with different Pt loadings supported on Al2O3 in the propane dehydrogenation reaction at 600℃ in the embodiments of the present invention.

[0029] Figure 5This is a performance diagram of the SiO2-supported PtIn alloy catalyst in the propane dehydrogenation reaction at 580℃ in an embodiment of the present invention.

[0030] Figure 6 The graph shows the performance of PtGa alloy catalysts with different Ga / Pt molar ratios supported on SiO2 in the propane dehydrogenation reaction at 580℃ in the embodiments of the present invention.

[0031] Figure 7 The images shown are (a) TEM images and (b) particle size distribution diagrams of the SiO2-supported PtZn alloy catalyst prepared in the embodiments of the present invention.

[0032] Figure 8 AC-HAADF-TEM image of the SiO2-supported PtZn alloy catalyst prepared in the embodiments of the present invention;

[0033] Figure 9 The graph shows the performance of the Al2O3-supported Ni catalyst and NiZn alloy catalyst prepared in the embodiments of the present invention in the propane dehydrogenation reaction at 600℃.

[0034] Figure 10 The graph shows the performance of the Al2O3-supported NiZn alloy catalysts with different Ni loadings prepared in the embodiments of the present invention in the propane dehydrogenation reaction at 600℃.

[0035] Figure 11 The figure shows the performance of the Al2O3-supported and NiSn alloy catalysts prepared in the embodiments of the present invention in the propane dehydrogenation reaction at 600℃. Detailed Implementation

[0036] This invention provides a supported bimetallic alloy catalyst, comprising a SiO2 support or an Al2O3 support, wherein bimetallic alloy nanoparticles are uniformly loaded on the SiO2 support or the Al2O3 support. The bimetallic alloy nanoparticles are formed by the diffusion of an auxiliary metal onto the active metal by atomic diffusion, and the particle size of the bimetallic alloy nanoparticles is in the sub-nanometer to 1-2 nanometer range.

[0037] The active metal is one of the transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and the auxiliary metal is one of the transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and In, Ga, Sn, Bi, and Pb. Furthermore, the active metal and the auxiliary metal are different metals.

[0038] The active metal only needs to possess basic CH activation ability, while the auxiliary metals play a role in adjusting the geometric configuration and electronic structure of the active metal. Since the CH activation ability of active metals varies, their optimized loading amounts will also vary considerably. In the examples, the Pt loading amount is 0.5-1% of the support, while Ni, due to its weaker CH activation ability compared to Pt, has a loading amount of 3%-20% in the examples. In summary, based on the support mass, a mass percentage of active metal of 0.025%-20% is suitable.

[0039] Similarly, the modifying effect of the additive metal on the active metal also varies, as does the molar ratio of the additive metal to the active metal. In the following examples, the molar ratio of the additive metal to the active metal ranges from 0.4 to 4. For other metals not exemplified in the examples, the actual molar ratio of the additive metal to the active metal may be outside this range, preferably 0.1 to 5.

[0040] The preparation method of the above-mentioned supported bimetallic alloy catalyst includes the following steps:

[0041] (1) Dissolve the precursor containing the active metal in deionized water and adjust the pH; for SiO2 support, the pH is generally adjusted to 10-13; for Al2O3 support, the pH is generally adjusted to 2-4.

[0042] In a preferred embodiment, the precursor of the active metal is one or more of the metal's soluble inorganic salts, such as nitrates, carbonates, and chlorides.

[0043] (2) The pH-adjusted precursor solution of the active metal is immersed in a SiO2 or Al2O3 support while being added dropwise and stirred. Then, it is sonicated to ensure thorough impregnation. It is usually allowed to stand at room temperature for 6-12 hours and then dried completely to obtain the loaded active metal. The mass percentage of the active metal is usually in the range of 0.025%-20% based on the mass of the support.

[0044] (3) Dissolve the precursor of the auxiliary metal with a molar ratio of 0.1 to 5 with the corresponding active metal in deionized water, then impregnate it on a SiO2 support or Al2O3 support, adding it dropwise while stirring, and then sonicating it to ensure full impregnation. Usually, it is allowed to stand at room temperature for 6-12 hours and then completely dried to obtain the loaded auxiliary metal precursor; calcine the loaded auxiliary metal precursor in air at high temperature to obtain the loaded auxiliary metal oxide.

[0045] In a preferred embodiment, the precursor of the auxiliary metal is one or more of the soluble inorganic salt of the metal, such as nitrate, carbonate, and chloride.

[0046] As a preferred embodiment, the high-temperature calcination temperature is generally in the range of 400-700°C. In the following embodiments, the high-temperature calcination temperature required for additives Zn and In, Ga, and Sn is 500-600°C, but the temperature required for additive metals such as Bi and Pb can be lower than this range, while the temperature required for additive metals such as Co and Cu can be higher than this range.

[0047] (4) The loaded active metal obtained in step (2) and the loaded auxiliary metal oxide obtained in step (3) are physically mixed evenly, and then reduced at high temperature in a hydrogen atmosphere to obtain a supported bimetallic alloy catalyst.

[0048] As a preferred embodiment, the high-temperature reduction temperature is generally in the range of 300-800°C. In the following embodiments, the high-temperature reduction temperature required for additives Zn and In, Ga, and Sn is 500-600°C, but the temperature required for additive metals such as Bi and Pb can be lower than this range, while the temperature required for additive metals such as Co and Cu can be higher than this range.

[0049] The above-mentioned supported bimetallic alloy catalysts can be applied to alkane dehydrogenation reactions.

[0050] As a preferred embodiment, the above-mentioned supported bimetallic alloy catalyst is used for propane dehydrogenation to propylene under the following reaction conditions:

[0051] A granular supported bimetallic alloy catalyst was loaded into a fixed-bed reactor and pretreated with hydrogen at 400-600℃ for 1-3 hours. Following pretreatment, the reaction was carried out at 550-650℃, with a hydrogen to propane molar ratio of 0-2. Nitrogen was used as the equilibrium gas, and the total gas volume remained constant. The feed rate was based on the propane space velocity, ranging from 1-30 h⁻¹. -1 between.

[0052] The present invention will be further described in detail below through specific embodiments. These embodiments will enable those skilled in the art to have a more comprehensive understanding of the present invention, but will not limit the present invention in any way.

[0053] Example 1

[0054] (1) Dissolve 0.02 g of (NH3)4Pt(NO3)2 in 1-2 mL of deionized water, and add ammonia to adjust the pH to 11;

[0055] (2) Add the solution obtained in step (1) dropwise to 1.00 g of SiO2 while stirring, then sonicate for 30 min; let stand at room temperature for 6 h, and then place in an oven at 80-100 ℃ to dry completely;

[0056] (3) The Pt precursor loaded on SiO2 obtained in step (2) is reduced at 550°C in a diluted hydrogen atmosphere to obtain Pt / SiO2.

[0057] Example 2

[0058] In this embodiment, the active metal is Pt and the auxiliary metal is Zn.

[0059] (1) Dissolve 0.02 g of (NH3)4Pt(NO3)2 in 1-2 mL of deionized water, and add ammonia to adjust the pH to 11;

[0060] Dissolve 0.01 g of Zn(NO3)3·6H2O precursor in 1-2 mL of deionized water.

[0061] (2) The two solutions obtained in step (1) are added dropwise to two 1.00g portions of SiO2 while stirring, and then sonicated for 30min. Let stand at room temperature for 6h, and then place in an oven at 80-100℃ to dry completely.

[0062] (3) Calcine the Zn precursor containing the Zn loaded on SiO2 obtained in step (2) in air at 500-600℃ for 1 h to obtain ZnO / SiO2.

[0063] (4) Physically mix the Pt / SiO2 obtained in step (2) and the ZnO / SiO2 obtained in step (3), and then reduce them at 550°C in a diluted hydrogen atmosphere to obtain a PtZn alloy catalyst (named PtZn). x / SiO2, where x is the Zn / Pt molar ratio obtained from elemental analysis, and in Example 2 x = 0.42).

[0064] Example 3

[0065] The catalyst was prepared according to the steps of Example 2, except that the mass of Zn(NO3)3·6H2O added was 0.02 g, resulting in the PtZn alloy catalyst PtZn. 0.71 / SiO2.

[0066] Example 4

[0067] The catalyst was prepared according to the steps of Example 2, except that the mass of Zn(NO3)3·6H2O added was 0.03 g, resulting in the PtZn alloy catalyst PtZn. 1.03 / SiO2.

[0068] Example 5

[0069] The catalyst was prepared using the same steps as in Example 2, except that the mass of Zn(NO3)3·6H2O added was 0.04 g, resulting in the PtZn alloy catalyst PtZn.1.41 / SiO2.

[0070] Example 6

[0071] The catalyst was prepared according to the steps of Example 2, except that the Pt support was Al2O3, and the mass percentage of Pt was 0.5%, 0.8%, and 1% of the Al2O3 support, respectively, to obtain an Al2O3-supported PtZn alloy catalyst.

[0072] Example 7

[0073] The catalyst was prepared according to the steps of Example 2, with the auxiliary metal Zn replaced by In, i.e., the corresponding precursor used was In(NO3)3·6H2O, to prepare a PtIn alloy catalyst, wherein the In / Pt molar ratio was 2.

[0074] Example 7

[0075] The catalyst was prepared according to the steps of Example 2, with the auxiliary metal Zn replaced by Ga, i.e., the corresponding precursor used was Ga(NO3)2·6H2O, to prepare PtGa alloy catalysts, wherein the Ga / Pt molar ratios were 2, 3 and 4, respectively, and were named Pt1Ga2 / SiO2, Pt1Ga3 / SiO2 and Pt1Ga4 / SiO2.

[0076] Example 8

[0077] The catalyst was prepared according to the steps of Example 1, with metal Pt replaced by Ni and support replaced by Al2O3, i.e., the precursor used was Ni(NO3)3·6H2O, to obtain Ni / Al2O3, wherein Ni accounts for 3% of the mass percentage of support Al2O3.

[0078] Example 9

[0079] The catalyst was prepared according to the steps of Example 2, with the active metal Pt replaced by Ni, i.e., the corresponding precursor used was Ni(NO3)3·6H2O, and the support for the active metal replaced by Al2O3, to obtain a NiZn alloy catalyst, wherein the mass percentage of Ni in the support Al2O3 was 3%, and the Zn / Ni molar ratio was 2.

[0080] Example 10

[0081] The catalyst was prepared according to the steps of Example 9. NiZn alloy catalysts with different Ni loadings were prepared, the difference being that the Ni loading was 6%, 9%, and 20% of the mass percentage of the Al2O3 support, respectively.

[0082] Example 11

[0083] The catalyst was prepared according to the steps of Example 2, with the active metal Pt replaced by Ni, i.e., the corresponding precursor used was Ni(NO3)3·6H2O, and the support for the active metal replaced by Al2O3. The auxiliary metal was replaced by Sn, i.e., the corresponding precursor used was SnCl2, to prepare a NiSn alloy catalyst, wherein the mass percentage of Ni in the Al2O3 support was 3%, and the Sn / Ni molar ratio was 2.

[0084] Example 12

[0085] Supported bimetallic alloy catalysts were used for propane dehydrogenation to propylene: The catalysts prepared in Examples 1-11 were pressed into 20-40 mesh particles and treated under a nitrogen atmosphere, increasing the temperature from room temperature to the reduction temperature of 600°C for 1 hour. Subsequently, the reaction was carried out at a reaction temperature of 600°C and a propane space velocity of 4 h⁻¹. -1 The feed ratio of hydrogen and propane is controlled at 1:1, and nitrogen is used as a dilution gas.

[0086] Example 13

[0087] Propane dehydrogenation to propylene was carried out under the conditions of Example 12, except that the reaction temperature was 580°C.

[0088] The results of the above embodiments are discussed below:

[0089] (I) Based on the amount of Pt in the catalyst, the effect of different Zn / Pt molar ratios on the propane dehydrogenation conversion of Pt / SiO and PtZn / SiO2 catalysts is described in [reference]. Figure 1 The specific preparation and reaction conditions are the same as in Examples 1, 2, 3, 4, 5, and 13.

[0090] from Figure 1 It can be seen that the PtZn alloy catalyst exhibits a higher propane conversion rate compared to Pt / SiO2. As the Zn / Pt molar ratio increases from 0.42 to 1.03, the reaction stability increases. However, when the molar ratio is further increased to 1.41, although the conversion rate decreases slightly, the stability remains the best.

[0091] (II) Based on the amount of Pt in the catalyst, the effect of different Zn / Pt molar ratios on the propane dehydrogenation selectivity of Pt / SiO2 catalyst and PtZn / SiO2 catalyst is described in [reference]. Figure 2 The specific preparation and reaction conditions are the same as in Examples 1, 2, 3, 4, 5, and 13.

[0092] from Figure 2 It can be seen that when the molar ratio of Zn to Pt is 1-1.4, the catalyst simultaneously achieves high stability and selectivity. Figure 1 The initial propane conversion rate was approximately 49%, with a selectivity of approximately 97%.

[0093] (III) PtZn / SiO2 catalyst (PtZn 1.41 For the long-range performance of (SiO2) in propane dehydrogenation, please refer to [reference needed]. Figure 3 The preparation and reaction conditions are the same as in Examples 5 and 12.

[0094] from Figure 3 It can be seen that the PtZn alloy prepared by this invention can stably catalyze propane dehydrogenation with high conversion and high selectivity at 600℃ for 10 hours, with a deactivation rate of 0.002 h⁻¹. -1 .

[0095] (IV) The effect of different Pt loadings on the catalytic activity of Al2O3-supported PtZn alloy catalysts is described in [reference]. Figure 4 The preparation and reaction conditions are the same as in Examples 6 and 13.

[0096] from Figure 4 As can be seen, PtZn alloy catalysts with different Pt loadings all exhibit stable propane dehydrogenation performance and propylene selectivity of over 90%. With increasing Pt percentage, propane conversion gradually increases, while propylene selectivity remains largely unchanged.

[0097] (V) Propane dehydrogenation performance testing of SiO2-supported PtIn alloy catalyst (see [reference]). Figure 5 The preparation and reaction conditions are the same as in Examples 6 and 13.

[0098] from Figure 1 and Figure 5 As can be seen, the PtIn alloy catalyst exhibits significantly better propane dehydrogenation performance than Pt / SiO2, specifically in terms of higher propane conversion, selectivity, and stability.

[0099] (vi) The effect of silica-supported PtGa alloy catalysts with different Ga / Pt molar ratios on propane dehydrogenation activity is described in [reference]. Figure 6 The preparation and reaction conditions are the same as in Examples 7 and 13.

[0100] from Figure 1 and Figure 6 As can be seen, PtGa alloy catalysts with different Ga / Pt molar ratios all exhibit significantly higher propane dehydrogenation conversion and selectivity than Pt / SiO2 catalysts. With the Ga / Pt molar ratio increasing from 2 to 4, the conversion gradually increases, and the stability of catalytic dehydrogenation also increases.

[0101] (vii) TEM images and particle size distribution diagrams of the silica-supported PtZn alloy catalyst prepared in this invention are shown in [reference needed]. Figure 7 The preparation conditions are the same as in Example 2.

[0102] from Figure 7 As can be seen, due to the high atomic number of Pt, the PtZn alloy appears as a distinct bright spot in the dark. The prepared PtZn alloy is highly dispersed on the silica support. Particle size statistics show an average particle size of 0.9 nm. Therefore, the prepared PtZn alloy is a highly dispersed, sub-nanometer alloy with a uniform particle size distribution.

[0103] Other embodiments also show that as the loading of Pt on the support increases (1% to 3%), the average particle size of Pt increases to 1-2 nanometers, but it is still an alloy with uniform particle size distribution and high dispersion on the support surface.

[0104] (eight) Figure 8 The image shows the AC-HAADF-TEM image of the silica-supported PtZn alloy catalyst prepared in this invention, with the same preparation conditions as in Example 2.

[0105] from Figure 8 As can be seen, Pt atoms are larger and brighter than Zn atoms, and Pt and Zn form a highly ordered intermetallic alloy.

[0106] (ix) For the propane dehydrogenation performance test of the Al2O3-supported NiZn alloy catalyst, see [link to relevant documentation]. Figure 9 The preparation and reaction conditions are the same as in Examples 8, 9, and 12.

[0107] from Figure 9 As can be seen, compared with Ni / Al2O3, NiZn alloy catalysts exhibit significantly superior propane dehydrogenation conversion and selectivity.

[0108] (x) Propane dehydrogenation performance tests of Al2O3-supported NiZn alloy catalysts with different Ni loadings are available in [reference]. Figure 10 The preparation and reaction conditions are the same as in Examples 9, 10, and 12.

[0109] from Figure 9 and Figure 10 As can be seen, compared with Ni / Al2O3, NiZn alloy catalysts with different Ni loadings exhibit significantly superior propane dehydrogenation conversion and selectivity. As the Ni loading increases from 3% to 20%, the propane conversion increases, but when the loading increases to 20%, the selectivity decreases slightly compared to the loading of 9%, but is still better than Ni / Al2O3.

[0110] (xi) For the propane dehydrogenation performance test of the Al2O3-supported NiSn alloy catalyst, see [reference needed]. Figure 11 The preparation and reaction conditions are the same as in Examples 11 and 12.

[0111] from Figure 9 and Figure 11As can be seen, compared with Ni / Al2O3, NiSn alloy catalysts exhibit significantly superior propane dehydrogenation conversion and selectivity.

[0112] In summary, this invention forms a bimetallic alloy catalyst by diffusing an auxiliary metal onto an active metal. This catalyst possesses a uniform particle size, and experiments show that after a propane dehydrogenation reaction lasting up to 100 hours, the catalyst particle size does not significantly increase, indicating its excellent anti-sintering ability. The above embodiments use Group VIII Pt and Ni as examples of active metals and Group IIB Zn and In, Ga, and Sn as examples of auxiliary metals, demonstrating the universality of this invention. Due to the similarity in physicochemical properties of transition metals, it can be extended to use one of the transition metal elements Groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB as the active metal and one of the transition metal elements Groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and one of In, Ga, Sn, Bi, and Pb as the auxiliary metal.

[0113] Although the preferred embodiments of the present invention have been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many specific modifications under the guidance of the present invention without departing from the spirit and scope of the claims, and these modifications all fall within the scope of protection of the present invention.

Claims

1. A supported bimetallic alloy catalyst, comprising a SiO2 support or an Al2O3 support, characterized in that, Bimetallic alloy nanoparticles are uniformly loaded onto the SiO2 or Al2O3 support. These nanoparticles are formed by the atomic diffusion of an auxiliary metal onto an active metal. The particle size of the bimetallic alloy nanoparticles is sub-nanometer to 1-2 nanometers. The active metal is one of the transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB. The auxiliary metal is one of the transition metal elements from groups IIIB, IVB, VB, VIB, VIIB, VIII, IB, and IIB, and one of In, Ga, Sn, Bi, and Pb. Furthermore, the active metal and the auxiliary metal are different metals. Based on the carrier mass, the mass percentage of the active metal is 0.025%-20%. The molar ratio of the auxiliary metal to the active metal is 0.1-5. And it is prepared according to the following method: The precursor containing the active metal is dissolved in deionized water and the pH is adjusted. Then, it is impregnated onto the SiO2 support or the Al2O3 support while being added dropwise and stirred. Subsequently, it is sonicated to ensure thorough impregnation, and then allowed to stand at room temperature and dried completely to obtain the loaded active metal. In the process of dissolving the precursor containing the active metal in deionized water and adjusting the pH: for the SiO2 support, the pH is adjusted to 10-13; for the Al2O3 support, the pH is adjusted to 2-4. The precursor containing the additive metal is dissolved in deionized water, then immersed in the SiO2 support or the Al2O3 support while being added dropwise and stirred. The mixture is then sonicated to ensure thorough immersion, allowed to stand at room temperature, and then completely dried to obtain the loaded additive metal precursor. The loaded additive metal precursor is then calcined in air at high temperature to obtain the loaded additive metal oxide. The supported active metal and the supported auxiliary metal oxide are physically mixed uniformly, and then reduced at high temperature in a hydrogen atmosphere to obtain the supported bimetallic alloy catalyst.

2. A method for preparing the supported bimetallic alloy catalyst as described in claim 1, characterized in that, The process includes the following: The precursor containing the active metal is dissolved in deionized water and the pH is adjusted. Then, it is impregnated onto the SiO2 support or the Al2O3 support while being added dropwise and stirred. Subsequently, it is sonicated to ensure thorough impregnation, and then allowed to stand at room temperature and dried completely to obtain the loaded active metal. In the process of dissolving the precursor containing the active metal in deionized water and adjusting the pH: for the SiO2 support, the pH is adjusted to 10-13; for the Al2O3 support, the pH is adjusted to 2-4. The precursor containing the additive metal is dissolved in deionized water, then immersed in the SiO2 support or the Al2O3 support while being added dropwise and stirred. The mixture is then sonicated to ensure thorough immersion, allowed to stand at room temperature, and then completely dried to obtain the loaded additive metal precursor. The loaded additive metal precursor is then calcined in air at high temperature to obtain the loaded additive metal oxide. The supported active metal and the supported auxiliary metal oxide are physically mixed uniformly, and then reduced at high temperature in a hydrogen atmosphere to obtain the supported bimetallic alloy catalyst.

3. The method for preparing the supported bimetallic alloy catalyst according to claim 2, characterized in that, In the preparation of the supported active metal and the supported auxiliary metal precursor, the time for standing at room temperature after full impregnation is 6-12 hours.

4. The method for preparing the supported bimetallic alloy catalyst according to claim 2, characterized in that, The temperature for high-temperature calcination in air is 400-700℃.

5. The method for preparing the supported bimetallic alloy catalyst according to claim 2, characterized in that, The high-temperature reduction temperature in a hydrogen atmosphere is 300-800℃.

6. The application of the supported bimetallic alloy catalyst as described in claim 1 in alkane dehydrogenation.

7. The application of the supported bimetallic alloy catalyst according to claim 6 in alkane dehydrogenation, characterized in that, The process for propane dehydrogenation to propylene is as follows: The granular supported bimetallic alloy catalyst was loaded into a fixed-bed reactor and pretreated with hydrogen. After pretreatment, the reaction was carried out at 550-650°C. The molar ratio of hydrogen to propane in the reaction gas was 0-2, with nitrogen as the equilibrium gas, and the total gas volume remained constant. The feed rate was based on the propane space velocity, ranging from 1 to 30 h⁻¹. -1 between.

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