Bimetallic single atom catalyst and its preparation method and application

Abstract

The bimetallic single-atom catalyst disclosed in the present invention is composed of an active component and a carrier, wherein the active component is composed of two metals, and the two metals are dispersed on the carrier surface in a single-atom structure; the present invention also discloses a method for preparing the above catalyst, which mainly loads the first metal and the second metal on the carrier surface in sequence by an impregnation method; the present invention also discloses the application of the above catalyst in the reaction of polyols to diols. The bimetallic single-atom catalyst of the present invention can effectively catalyze the reaction of polyols to diols, and the reaction can have both high conversion rate and selectivity, and its preparation method is simple, low cost, and has broad industrial application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysis, and specifically relates to a bimetallic single-atom catalyst. The present invention also relates to a preparation method of the bimetallic single-atom catalyst and an application of the bimetallic single-atom catalyst. Background Art

[0002] Biomass and its derivatives have the advantages of large storage capacity and renewability, making them an important part of the development and utilization of new energy. The most abundant components in biomass are sugars and polyols derived from sugars. The deoxygenation of these oxygen-rich substances can provide a renewable way for platform chemicals and transportation fuels, thereby providing an alternative resource for fossil fuels. Therefore, the conversion of biomass polyols has a high application value.

[0003] For the conversion of polyols to diols, compared with traditional high-temperature pyrolysis, acid-catalyzed dehydration and hydrogenolysis, the method of deoxygenation and dehydration (DODH) between adjacent hydroxyl groups can achieve a one-step conversion from alcohol to olefins, and then the olefins are converted into the target product, i.e., the corresponding diols, through further hydrogenation reactions. However, in the existing polyol-to-diol technology, only a few metals, such as rhenium, molybdenum, ruthenium, rhodium, palladium, platinum and gold, can effectively catalyze the reaction, but the above-mentioned precious metals are expensive, and the metal atom utilization rate of traditional non-single-atom catalysts is low, resulting in high catalyst costs, which are not suitable for industrial application and promotion. Therefore, for the process of catalyzing polyols to diols by catalysts, it is urgent to propose a catalyst that has high selectivity, high conversion rate, and low cost, and is suitable for industrial application. Summary of the invention

[0004] The object of the present invention is to provide a bimetallic single-atom catalyst which has both high selectivity and high conversion rate in the reaction of polyols to diols.

[0005] Another object of the present invention is to provide a method for preparing the above-mentioned bimetallic single-atom catalyst.

[0006] Another object of the present invention is to provide an application of the above-mentioned bimetallic single-atom catalyst in the reaction of polyols to diols.

[0007] The technical solution adopted by the present invention is a bimetallic single-atom catalyst, the catalyst consists of an active component and a carrier, the active component consists of two metals, and the two metals are dispersed on the surface of the carrier in a single-atom structure.

[0008] Another technical solution adopted by the present invention is a method for preparing a bimetallic single-atom catalyst, which specifically comprises the following steps:

[0009] Step 1, preparing a first metal precursor solution and a second metal precursor solution;

[0010] Step 2, uniformly mixing the first metal precursor solution obtained in step 1 with the carrier, stirring and drying, and subjecting to heat treatment to obtain a single metal single atom catalyst precursor;

[0011] Step 3: Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, stir to dry and heat treat to obtain a bimetallic single atom catalyst.

[0012] Another technical solution adopted by the present invention is the application of a bimetallic single-atom catalyst in the reaction of converting polyols to diols.

[0013] The present invention is also characterized in that

[0014] The two metals include a first metal and a second metal, the first metal is one of rhenium, molybdenum or vanadium, and the content of the first metal in the catalyst is 1wt% to 20wt% based on its corresponding element; the second metal is one of ruthenium, rhodium, palladium, platinum or gold, and the content of the second metal in the catalyst is 0.25wt% to 20wt% based on its corresponding element; the carrier is one of aluminum oxide, silicon oxide, iron oxide, cerium oxide or titanium oxide.

[0015] The specific preparation process of the first metal precursor solution in step 1 is: dissolving the first metal soluble precursor in a solvent to obtain a first metal precursor solution, and the metal concentration in the first metal precursor solution is 0.14 to 3.9 mol / L; the specific preparation process of the second metal precursor solution in step 1 is: dissolving the second metal soluble precursor in a solvent to obtain a second metal precursor solution, and the metal concentration in the second metal precursor solution is 0.034 to 1.9 mol / L.

[0016] The first metal-soluble precursor is one of metal chloride, ammonium salt or organic complex; the second metal-soluble precursor is one of metal chloride, ammonium salt or acetate; the solvent is an inorganic solvent or an organic solvent, the inorganic solvent is one of deionized water, ammonia water, hydrochloric acid, oxalic acid, ether or chloroform, and the organic solvent is one of anhydrous ethanol, acetone, aniline, ethylenediamine or a mixture of any two of them.

[0017] The drying temperature of the stirring and drying process in step 2 is 40-120°C, and the drying time is 5-24 hours; the drying temperature of the stirring and drying process in step 3 is 40-120°C, and the drying time is 4-24 hours; the heat treatment processes in steps 2 and 3 are both performed in an atmosphere of He, Ar, N2, O2 or H2 or a mixed atmosphere of any ratio of two of them, at 200-800°C for 60-300 minutes.

[0018] The substrate and the reaction solvent are mixed to obtain a reaction solution, and then a bimetallic single atom catalyst is added and a catalytic reaction is carried out in a closed high-pressure reactor. The initial pressure of hydrogen in the reactor is 1 to 5 MPa at room temperature, the reaction temperature is 50 to 150° C., and the reaction time is 5 to 240 min.

[0019] The initial pressure of hydrogen in the reactor is 2-4 MPa at room temperature, the reaction temperature is 80-120° C., and the reaction time is 60-180 min.

[0020] The substrate is one of erythritol, xylitol, D-sorbitol, D-mannitol or L-mannitol or a mixture of two of them in any ratio; the reaction solvent is one of methanol, ethanol, toluene, ethylbenzene, cyclohexane, tetrahydrofuran, isopropanol or deionized water or a mixture of two of them in any ratio; the substrate concentration in the reaction solution is 0.11-1.32 mol / L; the molar ratio of the active component of the catalyst to the substrate is 1.3×10 -3 ~0.073.

[0021] The beneficial effects of the present invention are:

[0022] (1) The first metal and the second metal active components of the bimetallic single atom catalyst of the present invention are dispersed on the carrier surface in a single atom structure. Compared with non-single atom catalysts, it can maximize the utilization rate of metal atoms and effectively reduce the amount of precious metals used, thereby reducing the cost of the catalyst.

[0023] (2) The first metal and the second metal active components in the bimetallic single atom catalyst of the present invention respectively undertake different catalytic processes and cooperate to complete the catalytic reaction of polyols to diols. In this reaction, the bimetallic single atom catalyst exhibits high selectivity and conversion rate, and its preparation method is simple, which is suitable for industrial promotion and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the AC-HAADF-STEM image of the Pt-Re / CeO2 bimetallic single atom catalyst in Example 1 of the present invention;

[0025] Figure 2 This is the EDS-Mapping diagram of the Pt-Re / CeO2 bimetallic single atom catalyst in Example 1 of the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] The bimetallic single-atom catalyst of the present invention is composed of an active component and a carrier, wherein the active component of the catalyst is composed of two metals, including a first metal and a second metal, the first metal is one of rhenium, molybdenum or vanadium, and plays a role in realizing the conversion of polyols into diols by utilizing active hydrogen species in the catalyst, and the content of the first metal in the catalyst is 1wt% to 20wt% based on its corresponding element; the second metal is one of ruthenium, rhodium, palladium, platinum or gold, and plays a role in activating hydrogen to produce active hydrogen species in the catalyst, and the content of the second metal in the catalyst is 0.25wt% to 20wt% based on its corresponding element; the carrier of the catalyst is one of aluminum oxide, silicon oxide, iron oxide, cerium oxide, titanium oxide or other metal oxides; in addition, the two metals of the active component are dispersed on the surface of the carrier in a single-atom structure, which can maximize the utilization rate of metal atoms, effectively reduce the amount of precious metals used, and thus reduce the cost of the catalyst.

[0028] The present invention prepares the above-mentioned bimetallic single-atom catalyst by an impregnation method, which is specifically implemented according to the following steps:

[0029] Step 1, prepare a first metal precursor solution and a second metal precursor solution; the specific preparation process is: dissolve the first metal soluble precursor in a solvent to obtain a first metal precursor solution with a metal concentration of 0.14 to 3.9 mol / L; dissolve the second metal soluble precursor in a solvent to obtain a second metal precursor solution with a metal concentration of 0.034 to 1.9 mol / L.

[0030] Among them, the first metal soluble precursor is one of metal chloride, ammonium salt or organic complex, and the second metal soluble precursor is one of metal chloride, ammonium salt or acetate; the solvent is an inorganic solvent or an organic solvent, wherein the inorganic solvent is one of deionized water, ammonia water, hydrochloric acid, oxalic acid, ether or chloroform, and the organic solvent is one of anhydrous ethanol, acetone, aniline or ethylenediamine or a mixture of any two of them in any ratio.

[0031] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with the carrier, stir and dry at 40-120°C for 5-24 hours, place in an atmosphere of one or two mixed in any ratio of He, Ar, N2, O2 or H2, and heat treat at 200-800°C for 60-300 minutes to obtain a monometallic single-atom catalyst precursor.

[0032] Step 3: Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, stir and dry at 40-120°C for 4-24 hours, place in an atmosphere of He, Ar, N2, O2 or H2 in any ratio, and heat treat at 200-800°C for 60-300 minutes to obtain a bimetallic single atom catalyst.

[0033] The present invention also includes the use of the above-mentioned bimetallic single-atom catalyst in the reaction of polyols to diols. Since the polyols have a unique vicinal diol structure, under the catalytic action of the bimetallic single-atom catalyst of the present invention, a one-step reaction can be achieved to efficiently convert the polyols into diols. The specific reaction is as follows:

[0034]

[0035] The specific process of using the bimetallic single-atom catalyst of the present invention to catalyze the preparation of diols from polyols is as follows: first, a reaction solvent and a substrate are mixed to obtain a reaction solution, wherein the reaction solvent is one or a mixture of two of methanol, ethanol, toluene, ethylbenzene, cyclohexane, tetrahydrofuran, isopropanol or deionized water in any ratio; the substrate is one or a mixture of two of erythritol, xylitol, D-sorbitol, D-mannitol, L-mannitol or other polyols in any ratio; the concentration of the substrate in the reaction solution is 0.11-1.32 mol / L; then, the bimetallic single-atom catalyst of the present invention is added to the above reaction solution and a catalytic reaction is carried out in a closed high-pressure reactor, wherein the molar ratio of the active component of the bimetallic single-atom catalyst to the substrate is 1.3×10 -3 The catalytic reaction conditions are as follows: the initial pressure of hydrogen in the reactor at room temperature is 1-5 MPa, the reaction temperature is 50-150°C, and the reaction time is 5-240 min. Preferably, the initial pressure of hydrogen in the reactor at room temperature is 2-4 MPa, the reaction temperature is 80-120°C, and the reaction time is 60-180 min.

[0036] Example 1

[0037] The bimetallic single-atom catalyst of the present invention, taking Pt-Re / CeO2 as an example, is prepared according to the following steps:

[0038] Step 1: Dissolve 0.27 g of tetrabutylammonium perrhenate in 3 g of anhydrous ethanol to obtain a first metal precursor solution with a Re concentration of 0.14 mol / L; dissolve 0.07 g of chloroplatinic acid hexahydrate in 10 g of aniline to obtain a Pt concentration of 3.41×10 - 2 mol / L of the second metal precursor solution.

[0039] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with 10 g of a cerium oxide carrier, stir and dry at 60°C for 18 hours, place in a N2 atmosphere, and heat treat at 550°C for 120 minutes to obtain a monometallic single-atom catalyst precursor.

[0040] Step 3. Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single-atom catalyst precursor obtained in step 2, and place them in a N2 atmosphere after stirring and drying at 50°C for 4 hours. Heat treat them at 400°C for 200 minutes to obtain a Pt-Re / CeO2 bimetallic single-atom catalyst, wherein the contents of Pt and Re in the catalyst are 0.25wt% and 1.0wt% respectively based on their corresponding elements.

[0041] The AC-HAADF-STEM image and EDS-Mapping image of the Pt-Re / CeO2 bimetallic single atom catalyst prepared by the above steps are shown in Figure 2. Figure 1 , Figure 2 As shown by Figure 1 No nano-metal particles can be observed in the figure and the distribution of bright spots of various elements in the catalyst in FIG2 shows that the Pt-Re / CeO2 bimetallic single-atom catalyst was successfully prepared in this embodiment, and Pt and Re are dispersed on the surface of the CeO2 carrier in a single-atom structure.

[0042] The above-mentioned Pt-Re / CeO2 bimetallic single atom catalyst was applied to the reaction of erythritol to butanediol. First, 100 mg of erythritol substrate was mixed with 5 g of cyclohexane reaction solvent to obtain a reaction solution, wherein the substrate concentration in the reaction solution was 0.13 mol / L; then, 20 mg of Pt-Re / CeO2 catalyst was added to the reaction solution and the catalytic reaction was carried out in a closed autoclave, wherein the molar ratio of the active component of the catalyst to the substrate was 1.3×10 -3 The conditions of the catalytic reaction are as follows: the initial pressure of hydrogen in the reactor is 2MPa at room temperature, the reaction temperature is 100°C, and the reaction time is 120min. With n-dodecane as the internal standard, the results were analyzed by gas chromatography after the reaction, and the results showed that the reaction selectivity was 98% and the conversion rate was 80%.

[0043] In addition, since the second metal and the first metal in the bimetallic single-atom catalyst respectively play the role of activating hydrogen to produce active hydrogen species and utilizing active hydrogen species to realize the conversion of polyols to diols, in order to improve the conversion rate of the catalyst to polyols to diols, it is necessary to ensure that the catalyst can produce sufficient active hydrogen species during the reaction process, thereby ensuring the subsequent conversion reaction. To this end, in this example, catalysts with different loading amounts of the second metal were prepared and applied to the reaction of erythritol to butanediol, while ensuring that other conditions remain unchanged. The reaction results are shown in Table 1:

[0044] Catalyst Time(min) Conversion(%) Selectivity(%) <![CDATA[0.25%Pt-1%Re / CeO2]]> 120 99.9 92.2 <![CDATA[0.20%Pt-1%Re / CeO2]]> 120 91.0 99.9 <![CDATA[0.15%Pt-1%Re / CeO2]]> 120 88.5 92.5 <![CDATA[0.10%Pt-1%Re / CeO2]]> 120 76.4 90.3

[0045] The results show that when the loading amount of the second metal in the Pt-Re / CeO2 bimetallic single atom catalyst increases, the conversion rate of the erythritol to butanediol reaction catalyzed by the catalyst also increases accordingly, but at the same time, the selectivity of the catalyst shows a trend of first increasing and then decreasing, indicating that the conversion rate and selectivity of the catalyst restrict each other. In the process of polyols to diols, the second metal loading amount of the catalyst should be determined according to the requirements of conversion rate and selectivity for actual applications.

[0046] Example 2

[0047] The bimetallic single-atom catalyst of the present invention, taking Ru-Re / SiO2 as an example, is prepared according to the following steps:

[0048] Step 1: Dissolve 0.79 g of rhenium trichloride in 10 ml of deionized water to obtain a first metal precursor solution with a Re concentration of 0.27 mol / L; dissolve 0.0138 g of ruthenium acetate in 5 ml of acetone to obtain a second metal precursor solution with a Ru concentration of 0.099 mol / L.

[0049] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with 10 g of a silicon oxide carrier, stir and dry at 40°C for 24 hours, place in a mixed atmosphere of O2 and Ar (volume ratio 1:99), and heat treat at 200°C for 60 minutes to obtain a monometallic single-atom catalyst precursor.

[0050] Step 3. Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, and place them in a mixed atmosphere of O2 and Ar (volume ratio 1:99) after stirring and drying at 40°C for 24 hours. Heat treat them at 200°C for 60 minutes to obtain a Ru-Re / SiO2 bimetallic single atom catalyst, wherein the contents of Ru and Re in the catalyst are 0.05wt% and 5wt% respectively based on their corresponding elements.

[0051] The above-mentioned Ru-Re / SiO2 bimetallic single atom catalyst is applied to the reaction of D-mannitol and L-mannitol to produce hexylene glycol. First, 100 mg of a mixed substrate of D-mannitol and L-mannitol (mass ratio is 1:1) is added to a mixed reaction solvent of 5 ml of methanol and toluene (volume ratio is 1:1) to obtain a reaction solution, wherein the substrate concentration in the reaction solution is 0.11 mol / L; then, 100 mg of Ru-Re / SiO2 catalyst is added to the reaction solution and the catalytic reaction is carried out in a closed high-pressure reactor, wherein the molar ratio of the active component of the catalyst to the substrate is 0.049. The conditions of the catalytic reaction are as follows: the initial pressure of hydrogen in the reactor is 1 MPa at room temperature, the reaction temperature is 50°C, and the reaction time is 5 min. With n-dodecane as the internal standard, the results are analyzed by gas chromatography after the reaction, and the results show that the reaction selectivity is 98% and the conversion rate is 90%.

[0052] In addition, since the cyclic stability of the catalyst is one of the key indicators for practical application, this embodiment uses Ru-Re / SiO2 bimetallic single atom catalyst to carry out multiple cyclic reactions of D-mannitol and L-mannitol to produce hexylene glycol, while ensuring that other conditions remain unchanged. The reaction results are shown in Table 2:

[0053]

[0054] The results show that the Ru-Re / SiO2 bimetallic single atom catalyst still maintains high selectivity and conversion rate after multiple cycles of reaction, indicating that the catalyst has high stability.

[0055] Example 3

[0056] The bimetallic single-atom catalyst of the present invention, taking Rh-Mo / Al2O3 as an example, is prepared according to the following steps:

[0057] Step 1: Dissolve 2.04 g of ammonium molybdate in 10 ml of ammonia water to obtain a first metal precursor solution with a Mo concentration of 1 mol / L; dissolve 0.26 g of rhodium chloride trihydrate in 2 ml of ethylenediamine to obtain a second metal precursor solution with a Rh concentration of 0.49 mol / L.

[0058] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with 10 g of an alumina carrier, stir and dry at 120° C. for 18 h, place in a He atmosphere, and heat treat at 800° C. for 300 min to obtain a monometallic single-atom catalyst precursor.

[0059] Step 3. Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, and place them in a He atmosphere after stirring and drying at 120°C for 20 hours. Heat treat them at 800°C for 300 minutes to obtain a Rh-Mo / Al2O3 bimetallic single atom catalyst, wherein the contents of Rh and Mo in the catalyst are 1wt% and 10wt% respectively based on their corresponding elements.

[0060] The above Rh-Mo / Al2O3 bimetallic single atom catalyst is applied to the reaction of D-sorbitol to hexanediol. First, 100 mg of D-sorbitol substrate is mixed with 5 g of deionized water to obtain a reaction solution, wherein the substrate concentration in the reaction solution is 0.11 mol / L; then, 40 mg of Au-Mo / TiO2 catalyst is added to the reaction solution and the catalytic reaction is carried out in a closed high-pressure reactor, wherein the molar ratio of the active component of the catalyst to the substrate is 0.073. The conditions of the catalytic reaction are as follows: the initial pressure of hydrogen in the reactor is 5 MPa at room temperature, the reaction temperature is 80°C, and the reaction time is 60 min. With n-dodecane as the internal standard, the results are analyzed by gas chromatography after the reaction, and the results show that the reaction selectivity is 90% and the conversion rate is 99%.

[0061] Example 4

[0062] The bimetallic single-atom catalyst of the present invention, taking Pd-V / Fe2O3 as an example, is prepared according to the following steps:

[0063] Step 1: Dissolve 4.59 g of ammonium metavanadate in 10 ml of anhydrous ethanol to obtain a first metal precursor solution with a V concentration of 3.9 mol / L; dissolve 5.34 g of ammonium chloropalladate in 10 ml of dilute hydrochloric acid with a concentration of 4 mol / L to obtain a second metal precursor solution with a Pd concentration of 1.9 mol / L.

[0064] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with 10 g of an iron oxide carrier, stir and dry at 100°C for 5 hours, place in a mixed atmosphere of O2 and N2 (volume ratio 1:99), and heat treat at 400°C for 200 minutes to obtain a monometallic single-atom catalyst precursor.

[0065] Step 3. Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, and place them in a mixed atmosphere of O2 and N2 (volume ratio 1:99) after stirring and drying at 100°C for 20 hours, and heat treat them at 600°C for 200 minutes to obtain a Pd-V / Fe2O3 bimetallic single atom catalyst, wherein the contents of Pd and V in the catalyst are 20wt% and 20wt%, respectively, based on their corresponding elements.

[0066] The above-mentioned Pd-V / Fe2O3 bimetallic single atom catalyst is applied to the reaction of xylitol to pentanediol. First, 1g of xylitol substrate is added to 5ml of a mixed reaction solvent of tetrahydrofuran and isopropanol (volume ratio is 1:1) to obtain a reaction solution, wherein the substrate concentration in the reaction solution is 1.32mol / L; then, 100mg of Pd-V / Fe2O3 catalyst is added to the reaction solution and the catalytic reaction is carried out in a closed high-pressure reactor, wherein the molar ratio of the active component of the catalyst to the substrate is 0.06. The conditions of the catalytic reaction are as follows: the initial pressure of hydrogen in the reactor is 4MPa at room temperature, the reaction temperature is 120℃, and the reaction time is 180min. With n-dodecane as the internal standard, the results are analyzed by gas chromatography after the reaction, and the results show that the reaction selectivity is 98% and the conversion rate is 98%.

[0067] Example 5

[0068] The bimetallic single-atom catalyst of the present invention, taking Au-Mo / TiO2 as an example, is prepared according to the following steps:

[0069] Step 1: Dissolve 4.08 g of ammonium molybdate in 10 ml of aqueous ammonia to obtain a first metal precursor solution with a Mo concentration of 2 mol / L; dissolve 4.2 g of tetrahydrated chloroauric acid in 10 ml of a mixed solvent of ether and chloroform (volume ratio of 1:1) to obtain a second metal precursor solution with a Au concentration of 1 mol / L.

[0070] Step 2: Evenly mix the first metal precursor solution obtained in step 1 with 10 g of titanium oxide carrier, stir and dry at 80°C for 15 h, place in H2 atmosphere, and heat treat at 200°C for 60 min to obtain a monometallic single-atom catalyst precursor.

[0071] Step 3. Evenly mix the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, and place them in a H2 atmosphere after stirring and drying at 100°C for 15 hours. Heat treat them at 200°C for 60 minutes to obtain an Au-Mo / TiO2 bimetallic single atom catalyst, wherein the contents of Au and Mo in the catalyst are 20wt% and 20wt% respectively based on their corresponding elements.

[0072] The above Au-Mo / TiO2 bimetallic single atom catalyst is applied to the reaction of D-sorbitol to hexanediol. First, 0.64g of D-sorbitol substrate is mixed with 5g of deionized water to obtain a reaction solution, wherein the substrate concentration in the reaction solution is 0.7mol / L; then, 40mg of Au-Mo / TiO2 catalyst is added to the reaction solution and the catalytic reaction is carried out in a closed high-pressure reactor, wherein the molar ratio of the active component of the catalyst to the substrate is 0.24. The conditions of the catalytic reaction are as follows: the initial pressure of hydrogen in the reactor is 3MPa at room temperature, the reaction temperature is 150℃, and the reaction time is 240min. With n-dodecane as the internal standard, the results are analyzed by gas chromatography after the reaction, and the results show that the reaction selectivity is 88% and the conversion rate is 99%.

Claims

1. Application of a bimetallic single-atom catalyst in the reaction of polyols to diols, characterized in that: Specifically, the substrate and the reaction solvent are mixed to obtain a reaction solution, and then a bimetallic single atom catalyst is added to carry out a catalytic reaction in a closed high-pressure reactor, wherein the initial pressure of hydrogen in the reactor is 1-5 MPa at room temperature, the reaction temperature is 50-150° C., and the reaction time is 5-240 min; The bimetallic single-atom catalyst is specifically a Pt-Re / CeO2 catalyst, the active component of which is composed of Pt-Re, and the Pt-Re is dispersed on the surface of the CeO2 carrier in a single-atom structure; The preparation method of the bimetallic single-atom catalyst specifically comprises the following steps: Step 1, preparing a first metal precursor solution and a second metal precursor solution; Dissolving tetrabutylammonium perrhenate in anhydrous ethanol to obtain a first metal precursor solution having a Re concentration of 0.14-3.9 mol / L; dissolving hexahydrated chloroplatinic acid in aniline to obtain a second metal precursor solution having a Pt concentration of 0.034-1.9 mol / L; Step 2, uniformly mixing the first metal precursor solution obtained in step 1 with the carrier, stirring and drying, and subjecting to heat treatment to obtain a single metal single atom catalyst precursor; The drying temperature of the stirring drying process is 40~120℃, and the drying time is 5~24h; The heat treatment process is to heat treat for 60 to 300 minutes at 200 to 800°C in an atmosphere of He, Ar, N2 or H2 or a mixture of two of them in any ratio; Step 3, uniformly mixing the second metal precursor solution obtained in step 1 and the monometallic single atom catalyst precursor obtained in step 2, stirring and drying, and heat treating to obtain a bimetallic single atom catalyst, and obtaining a Pt-Re / CeO2 bimetallic single atom catalyst, wherein the contents of Pt and Re in the catalyst are 0.25wt%~20wt% and 1wt%~20wt% respectively based on their corresponding elements; The drying temperature of the stirring drying process is 40~120℃, and the drying time is 4~24h; The heat treatment process is to perform heat treatment at 200-800°C for 60-300 minutes in an atmosphere of He, Ar, N2 or H2 or a mixed atmosphere of two of them in any ratio.

2. The use of the bimetallic single atom catalyst according to claim 1 in the reaction of polyols to diols, characterized in that: The initial pressure of hydrogen in the reactor is 2-4 MPa at room temperature, the reaction temperature is 80-120° C., and the reaction time is 60-180 min.

3. The use of the bimetallic single atom catalyst according to claim 1 or 2 in the reaction of polyols to diols, characterized in that: The substrate is one or a mixture of erythritol, xylitol, D-sorbitol, D-mannitol or L-mannitol; the reaction solvent is one or a mixture of methanol, ethanol, toluene, ethylbenzene, cyclohexane, tetrahydrofuran, isopropanol or deionized water; the substrate concentration in the reaction solution is 0.11-1.32 mol / L; the molar ratio of the active component of the catalyst to the substrate is 1.3×10 -3 ~0.073.

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