A method for the preparation of a platinum-based catalyst for hydrogen isotope catalytic exchange

Abstract

The application relates to a preparation method of a platinum-based catalyst for hydrogen isotope catalytic exchange; the graphene oxide of the application has rich oxygen-containing functional groups thereon, which can provide a basis for subsequent directional modification of hydrophilic groups and hydrophobic groups; the graphene carrier is a two-dimensional carrier, which can reduce the influence of reactant diffusion caused by pores as much as possible; based on the advantages of the graphene oxide, hydrophilic amino groups and hydrophobic dioctadecylaminohexafluorobutyl ester are introduced on the graphene surface through aminoization and silanization reactions; the ratio of the hydrophilic groups and the hydrophobic groups is optimized to construct a double-modified graphene carrier with different wettability, and a platinum catalyst is prepared through a liquid-phase photoreduction method; the performance of the double-modified graphene loaded platinum-based catalyst is evaluated by taking liquid-phase catalytic deuterium removal as a model reaction; and the catalyst shows relatively high intrinsic activity, equilibrium exchange efficiency and TOF (turnover frequency) under suitable conditions.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis technology, in particular to a preparation method of a platinum-based catalyst for hydrogen isotope catalytic exchange. BACKGROUND

[0002] Platinum has the best oxygen reduction catalytic activity, at the same time, graphene material has excellent physical and chemical properties, has excellent electron mobility and conductivity, large specific surface area and stability, etc., has been widely used as catalyst carrier, adsorbent and cocatalyst, etc.

[0003] Patent CN116832799A discloses a preparation method of an aminated graphene catalyst, which uses ammonia, graphene oxide and diethylene triamine to prepare aminated graphene. The method is simple and fast, does not require complex high-toxicity chemical reagents, has low cost, and can obtain aminated graphene. The aminated graphene catalyst is applied to activate peroxysulfate to remove pollutants. The aminated graphene can efficiently treat organic pollutants in wastewater by activating peroxysulfate.

[0004] For example, patent CN116870968A discloses an iridium complex functionalized nanographene catalyst, its preparation method and application. It belongs to the technical field of iridium complex functionalized nanographene catalysts. Through a two-step strategy of modification by a new amide ligand N-(4-aminophenyl) pyridine amide and metal-iridium coordination, a new type of nanographene catalyst functionalized by organic iridium (Ir) complex Ir-PyPh-GC is prepared.

[0005] For example, patent CN116870909A discloses a single-atom iron supported graphene Fenton catalyst, its preparation method and application. Ferrous ions are used as iron source, and complexation with 1.10 phenanthroline can effectively prevent the aggregation of iron atoms. After being mixed uniformly with graphene oxide solution, the single-atom iron supported graphene catalyst coordinated by nitrogen is obtained through freeze-drying and high-temperature pyrolysis reduction.

[0006] The existing preparation method of modified graphene is single and high-performance products have not been developed, so it is of great significance to select a suitable catalyst and modify graphene to improve the catalytic performance. SUMMARY

[0007] The purpose of the present application is to solve the problems of single preparation method of modified graphene and poor catalytic performance, and provide a method for double-modified graphene and a preparation method of platinum catalyst with graphene as carrier.

[0008] The present application provides a preparation method of the platinum catalyst with graphene as carrier, which comprises the following steps:

[0009] Step 1: 4-10 parts of GO suspension (1 mg / mL), 0.25-1 part of ethylenediamine and 0.3-1.5 parts of ammonia water are mixed into a three-necked flask, stirred at room temperature for 30-40 min, heated to 95-100°C and stirred under reflux for 7-10 h, and the product is centrifuged, washed and dried to obtain aminated graphene;

[0010] Step 2: 0.12-1 part of aminated graphene, 70-200 parts of ethanol, 0.3-1.5 parts of a silicone containing dioctadecyl and 0.5-1.5 parts of ammonia water are added into a stirred tank and continuously stirred at room temperature for 30-40 min, heated to 50-60°C and stirred under reflux for 5-8 h to obtain the product; the product is centrifuged, washed and dried to obtain double-modified graphene;

[0011] Step 3: 0.3-2 parts of the prepared aminated graphene carrier powder or double-modified graphene powder is dissolved in 50-200 parts of deionized water. Stir continuously at room temperature, then slowly add 0.1-0.8 parts of chloroplatinic acid aqueous solution (5wt%-10wt%). Stir at 30-40°C for 13-15 h, after filtration, add to 200-300 parts of an ethanol aqueous solution, irradiate with a mercury lamp for 2-5 hours under continuous stirring, and then centrifuge, wash and dry to obtain double-modified graphene supported platinum-based catalyst.

[0012] The distance from the liquid surface to the mercury lamp is 20 cm.

[0013] The preparation method of the silicone containing dioctadecyl is as follows:

[0014] By weight parts, 0.2-0.6 parts of propoxy triacetoxy methacrylate silane, 0.8-2 parts of dioctadecylamine, 0.2 parts of hexafluorobutyl acrylate, 0.4 parts of triethylamine, 50 parts of DMF are added into a stirred tank, and stirred at 80°C for 100 min, and the DMF is distilled off to obtain the silicone containing dioctadecyl.

[0015] Preferably, the preparation method of the GO uses a modified Hummer method or is purchased from the market.

[0016] Further, the amine compound in step 1) is one or more selected from ethylenediamine and triethylamine.

[0017] Further, the stirring in step 1) is at room temperature for 20-40 min.

[0018] Further, after stirring in step 1), the product is heated to 90-100°C and stirred under reflux for 5-10 h.

[0019] Further, the volume x of the silicone in step 2) is 0.2-1.5 g.

[0020] Furthermore, in step 2), the mixture is stirred continuously at room temperature for 20-40 minutes.

[0021] Furthermore, in step 2), after heating to 40-60℃, the mixture is stirred and refluxed for 5-8 hours.

[0022] Furthermore, in step 3), stirring at 20-40℃ for 10-15 hours is intended to allow chloroplatinic acid in the solution to be fully adsorbed onto the carrier surface and reach adsorption equilibrium.

[0023] Furthermore, in step 3), the volume ratio of ethanol to water is 9:1.

[0024] Furthermore, in step 3), the mercury lamp is used for irradiation and reduction for 2-5 hours.

[0025] Compared with existing technologies, the selection of graphene oxide in this invention has two advantages:

[0026] First, it has abundant oxygen-containing functional groups, which provides a basis for the subsequent directional modification of hydrophilic and hydrophobic groups;

[0027] Second, the graphene support is a two-dimensional support, which can minimize the impact of reactant diffusion caused by pores. Based on the advantages of graphene oxide, hydrophilic amino groups and hydrophobic dioctadecylamine hexafluorobutyl ester are introduced onto the graphene surface using amination and silanization reactions. By optimizing the ratio of hydrophilic to hydrophobic groups, dual-modified graphene supports with different wettability are constructed, and platinum catalysts are prepared using a liquid-phase photoreduction method.

[0028] The performance of a double-modified graphene-supported platinum-based catalyst was evaluated using liquid-phase catalytic deuteration as a model reaction. Under suitable conditions, the catalyst exhibited high intrinsic activity, equilibrium exchange efficiency, and TOF (transition frequency). Attached Figure Description

[0029] Appendix Figure 1 For evaluation systems of semi-batch reactors;

[0030] Appendix Figure 2 The image shows a SEM image of the catalyst prepared in Example 1.

[0031] Appendix Figure 3 The XRD pattern of the catalyst prepared in Example 1;

[0032] Appendix Figure 4 This is a SEM image of the catalyst prepared in Example 2;

[0033] Appendix Figure 5 The XRD pattern of the catalyst prepared in Example 2;

[0034] AppendixFigure 6 This is a SEM image of the catalyst prepared in Example 3;

[0035] Appendix Figure 7 The XRD pattern of the catalyst prepared in Example 3;

[0036] Appendix Figure 8 SEM image of the catalyst prepared in Comparative Example 1;

[0037] Appendix Figure 9 The XRD pattern of the catalyst prepared in Comparative Example 1;

[0038] Appendix Figure 10 Here is a SEM image of the catalyst prepared in Comparative Example 2;

[0039] Appendix Figure 11 The image shows the XRD pattern of the catalyst prepared in Comparative Example 2. Detailed Implementation

[0040] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.

[0041] Catalyst performance evaluation

[0042] The catalytic exchange performance of the catalyst was evaluated using a semi-batch reactor system, such as... Figure 1 As shown, the system mainly consists of four parts: an intake system, a reaction system, a condensation system, and an online analysis system. The intake system includes a hydrogen cylinder and a mass flow meter, with the hydrogen flow rate into the reaction system controlled by the mass flow meter. The reaction system comprises a preheating section and a reactor, with the overall temperature controlled by a constant-temperature water bath. The preheating section is composed of 3mm diameter PTFE rigid tubing, 50cm in length. The preheating section ensures that the gas temperature entering the reactor is maintained at the preset reaction temperature. Before each experiment, approximately 5g of semi-heavy water is added. The condensation system mainly consists of a precooling section and a liquid collector, with the temperature set to 0℃ using an ice-water bath. This system aims to condense water vapor in the outlet gas. The precooling section is also composed of 3mm diameter PTFE rigid tubing, 50cm in length. The online analysis system mainly consists of an online chromatography system. Due to the relatively low pressure requirements of the entire system, all pipelines use 3mm diameter PTFE rigid tubing.

[0043] Meanwhile, the hydrogen isotope exchange performance of the catalyst in the liquid phase exchange technology is evaluated by using two evaluation indexes of equilibrium exchange efficiency (η, %) and turnover frequency (TOF, h-1), and the specific calculation process is shown in formulas (1) and (2)

[0044]

[0045]

[0046] wherein y HD0 and y HD1 are the molar fractions of HD in the gas at the inlet and outlet of the reactor, respectively. The value of the molar fraction of HD at the inlet of the reactor is calculated according to the natural abundance of deuterium in water, which is 0.003%. The equilibrium molar fraction of HD in the outlet gas is calculated by mass balance and the isotopic separation factor of hydrogen and water. is the molar flow rate of the inlet hydrogen; n HD is the number of moles of HD produced by the reaction; n Pt is the total number of moles of platinum in the catalyst; and t is the total reaction time, in h.

[0047] Example 1

[0048] 4 g of the GO suspension (1 mg / mL), 0.25 g of ethylenediamine and 0.3 g of ammonia water are mixed into a three-necked flask, stirred at room temperature for 30 min, heated to 95°C and stirred under reflux for 7 h, and the product is subjected to centrifugation, washing and drying to obtain aminated graphene.

[0049] 0.12 g of the aminated graphene, 70 g of ethanol, 0.3 g of bis-stearyl siloxane and 0.5 g of ammonia water are added into a stirred tank, continuously stirred at room temperature for 30 min, heated to 50°C and stirred under reflux for 5 h to obtain bis-modified graphene.

[0050] The product is subjected to centrifugation, washing and drying to obtain bis-modified graphene, 0.3 g of the prepared bis-modified graphene support powder is dissolved in 50 g of deionized water, continuously stirred at room temperature, and then 0.1 g of chloroplatinic acid (5 wt%) aqueous solution is slowly added. Stirring is performed at 30°C for 13 h, after filtration, the product is added into 200 g of an ethanol aqueous solution, reduced by mercury lamp irradiation under continuous stirring for 2 h, wherein the liquid level is 20 cm away from the mercury lamp. After centrifugation, washing and drying, a bis-modified graphene supported platinum catalyst is obtained.

[0051] The preparation method of the bis-stearyl siloxane is as follows:

[0052] By weight parts, 0.2 g of methacrylic acid propoxy triacetyloxy silane, 0.8 g of dioctadecylamine, 0.09 g of hexafluorobutyl acrylate, 0.15 g of triethylamine, 30 g of DMF were added to a stirred tank, and after stirring at 75 °C for 80 minutes, the DMF was distilled off to obtain a dioctadecyl-containing siloxane.

[0053] Example 2

[0054] 7 g of GO suspension (1 mg / mL), 0.75 g of triethylamine and 1 g of ammonia water were mixed into a three-necked flask, stirred at room temperature for 20 min, heated to 90 °C and stirred under reflux for 5 h, and the product was obtained by centrifugation, washing and drying to obtain aminated graphene.

[0055] 0.5 g of aminated graphene, 150 g of ethanol, 1 g of n-octyl triethoxysilane, and 1.1 g of ammonia water were weighed into a stirred tank and stirred continuously at room temperature for 20 min, heated to 40 °C and stirred under reflux for 5 h to obtain the product. The product was centrifuged, washed and dried to obtain double-modified graphene.

[0056] 1.3 g of the prepared double-modified graphene support powder was weighed into 150 g of deionized water. Stir continuously at room temperature, then slowly add 0.5 g of 8 wt% aqueous chloroplatinic acid. Stir at 20 °C for 10 h, after filtration, add to 200 g of an ethanol aqueous solution, and reduce under the irradiation of a mercury lamp for 3 hours with continuous stirring, with the liquid level to the distance from the mercury lamp being 20 cm. After centrifugation, washing and drying, a double-modified graphene supported platinum-based catalyst was obtained.

[0057] The preparation method of the dioctadecyl-containing siloxane is as follows:

[0058] By weight parts, 0.4 g of methacrylic acid propoxy triacetyloxy silane, 1.3 g of dioctadecylamine, 0.12 g of hexafluorobutyl acrylate, 0.25 g of triethylamine, 40 g of DMF were added to a stirred tank, and after stirring at 70 °C for 50 minutes, the DMF was distilled off to obtain a dioctadecyl-containing siloxane.

[0059] Example 3

[0060] 10 g of GO suspension (1 mg / mL), 1 g of ethylenediamine and 1.5 g of ammonia water were mixed into a three-necked flask, stirred at room temperature for 40 min, heated to 100 °C and stirred under reflux for 10 h, and the product was obtained by centrifugation, washing and drying to obtain aminated graphene.

[0061] Take 1 g of amino graphene, 200 g of ethanol, 1.5 g of dodecyl trimethoxysilane, and 1.5 g of ammonia water into a stirred tank, and continuously stir at room temperature for 40 min, and stir to reflux at 60℃ for 8 h to obtain the product. The product is centrifuged, washed, and dried to obtain the double-modified graphene.

[0062] Take 2 g of the prepared double-modified graphene powder into 200 g of deionized water. Stir continuously at room temperature, and then slowly add 0.8 g of 10 wt% chloroplatinic acid aqueous solution. Stir at 40℃ for 15 h, after filtration, add into 300 g of ethanol aqueous solution, and reduce under irradiation of a mercury lamp for 5 h with the liquid level being 20 cm away from the mercury lamp. Centrifuge, wash, and dry again to obtain the double-modified graphene supported platinum-based catalyst.

[0063] The preparation method of the double-octadecyl-containing siloxane is as follows:

[0064] By weight parts, 0.6 g of propoxy triacetoxy silane methacrylic acid, 2 g of double-octadecyl amine, 0.2 g of hexafluorobutyl acrylate, 0.4 g of triethylamine, and 50 g of DMF are added into a stirred tank, and stirred at 80℃ for 100 min, and DMF is removed by distillation to obtain the double-octadecyl-containing siloxane.

[0065] Comparative Example 1

[0066] Mix 4 g of GO suspension (1 mg / mL), 0.25 g of ethylenediamine, and 0.3 g of ammonia water into a three-necked flask, stir at room temperature for 30 min, and stir to reflux at 95℃ for 7 h. The product is centrifuged, washed, and dried to obtain the amino graphene.

[0067] Take 0.3 g of the prepared amino graphene support powder into 50 g of deionized water. Stir continuously at room temperature, and then slowly add 0.1 g of chloroplatinic acid aqueous solution. Stir at 30℃ for 13 h, after filtration, add into an ethanol aqueous solution, and reduce under irradiation of a mercury lamp for 5 h with the liquid level being 20 cm away from the mercury lamp. Centrifuge, wash, and dry again to obtain the amino graphene supported platinum catalyst.

[0068] Comparative Example 2

[0069] Mix 4 g of GO suspension (1 mg / mL), 0.25 g of ethylenediamine, and 0.3 g of ammonia water into a three-necked flask, stir at room temperature for 30 min, and stir to reflux at 95℃ for 7 h. The product is centrifuged, washed, and dried to obtain the amino graphene.

[0070] Take 0.12g of amino graphene, 70g of ethanol, 0.3g of bis-stearyl siloxane, and 0.5g of ammonia water into a stirred tank, and continuously stir at room temperature for 30min, and after heating to 50℃, stir reflux for 7h to obtain bis-modified graphene.

[0071] The preparation method of the bis-stearyl siloxane is:

[0072] By weight parts, 0.2g of methacrylic acid propoxy triacetyl silane, 0.8g of bis-stearyl amine, 0.09g of hexafluorobutyl acrylate, 0.15g of triethylamine, 30g of DMF are added into a stirred tank, and after stirring at 75℃ for 80min, the DMF is distilled off to obtain bis-stearyl siloxane.

[0073] Table 1 equilibrium exchange efficiency and conversion frequency of each catalyst

[0074]

[0075] From the above, it can be seen that:

[0076] Based on the advantages of graphene oxide, amino and silane reactions are used to introduce hydrophilic amino groups and hydrophobic bis-stearyl amine and hexafluorobutyl acrylate on the surface of graphene. By optimizing the ratio of hydrophilic groups and hydrophobic groups, bis-modified graphene carriers with different wettability are constructed, and platinum catalysts are prepared by liquid phase photoreduction method, which improves the hydrogen isotope exchange performance of the catalyst in liquid phase exchange technology.

[0077] The above is only a preferred embodiment of the present application, and does not limit the present application in any form. Although the present application has been disclosed as above with a preferred embodiment, it is not intended to limit the present application. Any person skilled in the art can make some changes or modifications to the above disclosed technical content to obtain equivalent embodiments with equivalent changes, without departing from the technical solution of the present application. Any modification, change and modification of the above embodiments, which does not depart from the technical solution of the present application, is still within the scope of the present application.

Claims

1. A method for the preparation of a platinum-based catalyst for hydrogen isotope catalytic exchange, characterized in that, The method comprises the following steps: Step 1, mixing GO suspension, ethylenediamine and ammonia water into a three-necked flask, stirring at room temperature, continuing to stir and reflux after warming, centrifuging, washing and drying the product to obtain aminated graphene; Step 2, adding 0.12-1 parts of the aminated graphene prepared in step 1, 70-200 parts of ethanol, 0.3-1.5 parts of a double-octadecyl-containing siloxane and 0.5-1.5 parts of ammonia water into a stirred tank, continuously stirring at room temperature for 30-40 min, stirring and refluxing at 50-60℃ after warming for 5-8 h to obtain a product, centrifuging, washing and drying the product to obtain double-modified graphene; Step 3, placing the double-modified graphene powder into deionized water, continuously stirring at room temperature, then slowly adding an aqueous chloroplatinic acid solution, stirring at a suitable temperature, filtering, adding into an ethanol aqueous solution, reducing under irradiation of a mercury lamp, and then centrifuging, washing and drying to obtain double-modified graphene supported platinum-based catalyst; The double-octadecyl-containing siloxane is prepared by the following method: According to weight parts, 0.2-0.6 parts of propoxy triacetoxy methacrylate silane, 0.8-2 parts of double-octadecyl amine, 0.2 parts of hexafluorobutyl acrylate, 0.4 parts of triethylamine and 50 parts of DMF are added into a stirred tank, and stirring is performed at 80℃ for 100 min, and then DMF is removed by distillation to obtain the double-octadecyl-containing siloxane.

2. The method of claim 1, wherein the platinum-based catalyst is prepared by the steps of: (a) providing a platinum-based catalyst; (b) impregnating the catalyst with a solution of a transition metal salt; (c) drying the impregnated catalyst; (d) calcining the dried catalyst; and (e) reducing the calcined catalyst. The mixture in step 1 is stirred at room temperature for 30-40 min, and then stirred and refluxed at 95-100℃ after warming for 7-10 h; the raw materials are 4-10 parts of 1 mg / mL GO suspension, 0.25-1 parts of ethylenediamine and 0.3-1.5 parts of ammonia water.

3. The method of claim 1, wherein the platinum-based catalyst is prepared by the steps of: (a) preparing a platinum-based catalyst precursor; (b) impregnating the catalyst precursor with a solution of a noble metal; (c) drying the impregnated catalyst precursor; and (d) calcining the dried impregnated catalyst precursor. The mixture in step 3 is stirred at 20-40℃ for 10-15 h, and the raw materials are 1-20 parts of double-modified graphene, 100-2000 parts of deionized water, 1-8 parts of a chloroplatinic acid solution and 500-3000 parts of an ethanol aqueous solution.

4. The method for preparing a platinum-based catalyst for hydrogen isotope catalytic exchange according to claim 1, characterized in that, The reduction under irradiation of a mercury lamp is performed for 2-5 h.

Images