A bismuth-doped palladium-on-carbon catalyst, its preparation method and applications

Abstract

This invention discloses a bismuth-doped palladium-on-carbon catalyst, its preparation method, and its applications. The total palladium loading of the catalyst is 1.0–10.0 wt.%, and the bismuth loading is 0.05–0.15 times the molar amount of palladium. The method includes: dispersing a carbon support in water to obtain suspension A; adding chloropalladic acid to an aqueous sodium citrate solution to obtain solution B; adding solution B to suspension A to obtain suspension C; sonicating suspension C, maintaining temperature, stirring, and impregnating; adding a sodium carbonate solution containing sodium borohydride for reduction, filtering, washing, and drying to obtain the palladium-on-carbon catalyst; dispersing the palladium-on-carbon catalyst in deionized water, sonicating, and stirring to obtain suspension D; adding an aqueous bismuth nitrate solution to suspension D, stirring, impregnating, filtering, and drying to obtain the catalyst. This catalyst exhibits advantages such as high catalytic activity, high conversion rate, easy recovery, and recyclability when used for hydrogen production from formic acid decomposition or hydrogen production from ammonia borane hydrolysis.

Description

Technical Field

[0001] This invention relates to heterogeneous catalysts using a series of carbons as supports and bismuth-doped palladium carbons with different molar ratios, their preparation methods, and the use of these catalysts in formic acid decomposition for hydrogen production and ammonia borane hydrolysis for hydrogen production. Background Technology

[0002] Hydrogen, one of the most abundant elements on Earth, is an ideal energy carrier, possessing high energy density, cleanliness, and global abundance. Its calorific value is very high, three times that of gasoline, and its only product after oxidation / combustion is water, making it one of the most promising and hopeful clean energy sources to replace fossil fuels. Currently, hydrogen energy is being gradually applied in fuel cells, aerospace, military, energy, transportation, and industry. However, hydrogen is the lightest of all elements, existing as a gas at room temperature and pressure with a density of only 0.0899 kg / m³. 3 Furthermore, hydrogen is flammable and explosive, making it difficult to store and transport. Therefore, how to safely and efficiently store and transport hydrogen has become a challenge and an urgent problem to be solved in order to realize the widespread use of hydrogen energy.

[0003] Hydrogen storage methods are mainly divided into two types: physical hydrogen storage and chemical hydrogen storage. Physical hydrogen storage includes traditional methods such as high-pressure tank storage and cryogenic liquid hydrogen storage, as well as methods using novel materials such as metal-organic frameworks for adsorption hydrogen storage. However, physical storage methods are often characterized by high cost, poor safety, large weight, and inconvenient transportation. Chemical hydrogen storage refers to storing hydrogen in hydrogen-containing compounds such as metal hydrides, sodium borohydride, ammonia borane, and formic acid. Compared with physical hydrogen storage, chemical hydrogen storage, which stores hydrogen through chemical bonds, is safer, more convenient, and more efficient, and is considered a more ideal hydrogen storage method with the potential for large-scale application. Among these, formic acid and ammonia borane have become the preferred hydrogen storage materials due to their respective advantages.

[0004] Formic acid (HCOOH, Formic Acid, FA) is the simplest carboxylic acid, with low toxicity and a very high hydrogen density (4.4 wt.%, 53.4 g·L⁻¹). -1Formic acid is inexpensive and, being liquid at room temperature, has low volatility and is not easily flammable, making it safe to store and transport. It is considered a promising organic liquid hydrogen storage material. Compared to other hydrogen storage technologies, formic acid hydrogen storage technology is extremely low-cost, highly safe, and has unparalleled advantages in storage and transportation. At room temperature and pressure, formic acid can only decompose to produce hydrogen under the action of a catalyst. Under the action of a catalyst, formic acid can decompose through two pathways: a dehydrogenation pathway (HCOOH→H2+CO2), producing carbon dioxide and hydrogen; and a dehydration pathway (HCOOH→H2O+CO), producing water and carbon monoxide. Both pathways are thermodynamically favorable reactions (standard Gibbs free energy change less than 0), with the dehydration pathway being a side reaction. Compared to homogeneous catalysts, heterogeneous catalysts have advantages such as easy recovery, recyclability, higher resistance to carbon monoxide (CO) poisoning, long lifespan, avoidance of large amounts of organic solvents in the preparation process, and easier control of the reaction process, showing broad development prospects. Heterogeneous catalysts consist of a support and an active component mounted on it. Catalysts can be classified into single-metal catalysts and binary / multi-component alloy catalysts based on the active component. Among single-metal catalysts, palladium is the most reactive catalyst for the decomposition of formic acid to produce hydrogen. However, because carbon monoxide can form stable adsorption on noble metal surfaces, even trace amounts of carbon monoxide gas can poison the catalyst and cause deactivation; therefore, side reactions must be avoided. Although some single-palladium catalysts have good performance, most are unstable due to their susceptibility to poisoning by carbon monoxide, a byproduct of formic acid decomposition. By alloying or doping Pd with elements such as Ag, Au, Ni, Co, Cr, B, and Bi, the valence electron density of Pd can be adjusted, thereby reducing the adsorption of carbon monoxide or promoting the adsorption of formate ions. The introduction of Bi atoms not only allows Bi itself to suppress CO adsorption sites, making it less likely for CO to be adsorbed on Pd, but also creates an electronic effect between Pd and Bi atoms after they form an alloy structure. This alters the electronic structure of the Pd surface, reducing CO adsorption on Pd and thus improving the stability of the catalyst.

[0005] Ammonia borane (NH3BH3, AB) is stable as a solid (white crystals, density 0.78 g / cm³) at room temperature. 3 It is non-toxic and soluble in polar solvents such as water and methanol. It boasts a high hydrogen storage capacity of 19.6% and 185 kg (H2) / m³. 3Ammonia borane has advantages such as good stability and relatively low cost, making it one of the ideal hydrogen sources. There are three methods for producing hydrogen from ammonia borane: pyrolysis, alcoholysis, and hydrolysis. Pyrolysis requires high temperatures, consumes a lot of energy, and releases pollutants at high temperatures; alcoholysis has low efficiency and relatively high cost. Hydrolysis of ammonia borane is the process of reacting ammonia borane with water to release hydrogen. Aqueous solutions of ammonia borane are very stable and do not react at room temperature without a catalyst. With the addition of a catalyst, rapid and large-volume hydrogen release at room temperature can be achieved; 1 mole of ammonia borane can catalytically hydrolyze to produce 3 moles of hydrogen gas (NH3BH3 + 2H2O → NH4). + +BO2 - (+3H2↑), and is clean and pollution-free. Therefore, the key to the development and application of ammonia borane hydrolysis for hydrogen production lies in the development of efficient, stable, environmentally friendly, and easily separable and recoverable catalysts. In catalytic ammonia borane hydrolysis for hydrogen production, noble metals (such as Pt, Rh, Ru, Pd, Ag, etc.) have shown excellent catalytic performance; however, single-component noble metal catalysts are often easily poisoned and metal particles are prone to agglomeration, leading to reduced catalytic activity. Furthermore, noble metals are scarce and expensive, and single-component noble metal catalysts increase catalyst costs, thereby increasing the cost of hydrogen production. To reduce their usage, catalyst design focuses on two aspects: first, minimizing size and increasing specific surface area; second, developing non-noble metals or alloys with non-noble metals. Since the catalytic activity and stability of non-precious metal catalysts are still somewhat inferior to those of precious metal catalysts, and the electronic effects and synergistic catalytic effects between multi-component metals usually have better stability and catalytic performance than single-metal catalysts, introducing transition metals into single-component precious metal catalysts to form precious metal-non-precious metal bimetallic catalysts can not only reduce the consumption of precious metals, but also improve catalytic activity. This is a feasible route for preparing efficient and stable catalytic catalysts for the hydrolysis of ammonia borane to produce hydrogen.

[0006] Therefore, developing a method for preparing a palladium-carbon catalyst that is simple, mild, low-cost, can be prepared on a large scale, has uniformly dispersed active components, and exhibits high catalytic activity and good stability has become an urgent problem to be solved for the promotion and utilization of hydrogen energy. Summary of the Invention

[0007] The technical problem to be solved by this invention is to overcome the above-mentioned shortcomings and provide a bismuth-doped palladium-carbon catalyst and its preparation method for catalytic hydrogen production from formic acid decomposition and hydrogen production from ammonia borane hydrolysis. The catalyst consists of a carbon support, palladium nanoparticles as the active component supported on the carbon support, and doped rare metal bismuth. The total palladium loading is 1.0–10.0 wt.%, and the bismuth loading is 0.05–0.15 times the molar amount of palladium loaded in the catalyst. The preparation method is simple and the preparation conditions are mild. This catalyst is suitable for various carbon supports, and the proportion of its active components is adjustable. Furthermore, it can be applied to the rapid decomposition of formic acid and hydrogen production from ammonia borane hydrolysis.

[0008] Specifically, the present invention utilizes the preparation method described above to prepare a series of catalysts by fixing the metal loading, adjusting the molar ratio between palladium and bismuth, and changing the type of carbon support. When these catalysts are used for hydrogen production from formic acid decomposition and hydrogen production from ammonia borane hydrolysis, they can effectively avoid the occurrence of side reactions and have the advantages of high catalytic activity, high conversion rate, easy recovery and recyclability. They are suitable for industrial scale-up production and have promotional value.

[0009] The technical solution adopted in the preparation method of the present invention is as follows:

[0010] Weigh out 318 mg of activated carbon AC1 (specific surface area 1300 m²). 2 370.6 mg of sodium citrate was dissolved in 40 mL of water and ultrasonically dispersed for 30 min. Then, 3.15 mL of 0.05 M chloropalladium acid solution was added, and ultrasonication was continued for 20 min. The mixture was then transferred to a low-temperature reaction bath and stirred at 0 °C for 1 h. Then, 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) was added dropwise at a rate of 0.5 mL / min. After the addition was completed, the mixture was kept at the same temperature and stirred for 4 h. The mixture was filtered, and the filter cake was washed with a large amount of water. After vacuum drying at 50 °C for 12 h, palladium on carbon (Pd / AC1) catalyst was obtained.

[0011] Step 1, Preparation of carrier suspension A: 318 mg of carbon carrier is dispersed in 40 mL of deionized water, ultrasonically dispersed for 30 min, and stirred to form carrier suspension A;

[0012] Step 2, Preparation of palladium precursor solution B: Dissolve 370.6 mg sodium citrate in water, then add 3.15 mL of 0.05 M palladium precursor solution to form palladium precursor solution B;

[0013] Step 3, Mixed suspension C: Add palladium precursor solution B to carrier suspension A under stirring, and stir at room temperature for 10 min to form mixed solution C;

[0014] Step 4, ultrasonic mixing: Ultrasonically mix the mixed suspension C for 20 minutes;

[0015] Step 5, stirring and impregnation: Transfer the mixed suspension C to a low-temperature constant temperature reaction bath and stir and impregnate it under controlled temperature (0-50℃);

[0016] Step 6, reduction: Add 10 mL of sodium carbonate aqueous solution containing 40 mg sodium borohydride dropwise at a rate of 0.5 mL / min, and continue reduction and stirring under controlled temperature (0-50℃) conditions for 2-16 hours;

[0017] Step 7, filtration and drying: filter by suction and wash the filter cake with a large amount of water. Dry the filter cake in a vacuum oven at 50°C for 16 hours, grind it, and obtain the palladium on carbon Pd / C catalyst.

[0018] Step 8: Disperse the prepared palladium-carbon Pd / C catalyst in deionized water, ultrasonically disperse for 30 min, and stir for 1 h to form catalyst suspension D.

[0019] Step 9, stirring and impregnation: Weigh bismuth nitrate and dissolve it in deionized water. Add the 1 mg / mL bismuth nitrate aqueous solution to the catalyst suspension D under stirring, and continue stirring for 1-2 hours.

[0020] Step 10, Filtration and Drying: Filter by suction, wash the filter cake with a small amount of water, dry the filter cake in a vacuum oven, grind it, and obtain the bismuth-doped palladium-on-carbon catalyst, named PdBi. x The name of the carbon support, such as naming a catalyst prepared using superconducting carbon Ketjen Black ECP as a support with a molar amount of bismuth of 0.11 times that of palladium as PdBi. 0.11 / ECP.

[0021] The use of a bismuth-doped palladium-on-carbon catalyst in the catalytic decomposition of formic acid to produce hydrogen.

[0022] The use of a bismuth-doped palladium-on-carbon catalyst in the catalytic hydrolysis of ammonia borane to produce hydrogen.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] 1. Compared with pure palladium on carbon catalyst, the bismuth-doped palladium on carbon catalyst prepared according to the method of the present invention has higher catalytic activity and better stability when the molar amount of palladium in the active component is the same.

[0025] 2. Compared with palladium-on-carbon catalysts / palladium-bismuth catalysts prepared by other methods, the bismuth-doped palladium-on-carbon catalyst prepared by the method described in this invention can catalyze the dehydrogenation of formic acid and the hydrogen release from ammonia borane water under mild conditions, thus realizing the multifunctional application of the catalyst; at the same time, the catalyst has high catalytic activity, good selectivity, and can be repeatedly recycled.

[0026] 3. Compared with other palladium-bismuth alloy catalysts, the preparation method of the present invention has the advantages of simple process, convenient operation, short preparation time, low cost and good reproducibility, and is more suitable for industrial scale-up production. Attached Figure Description

[0027] Figure 1 Schematic diagram of the preparation process of bismuth-doped palladium-carbon catalyst.

[0028] Figure 2 PdBi prepared in Example 1 0.11TEM images of Pd / AC1(a) and Pd / AC1(b) prepared in Comparative Example 1.

[0029] Figure 3 PdBi prepared in Example 1 0.11 XPS plots of Pd 3d and Bi 4f in / AC1 and Pd 3d in Pd / AC1 prepared in Comparative Example 1.

[0030] Figure 4 PdBi prepared in Example 1 0.11 XRD patterns of Pd / AC1 prepared in Comparative Example 1 and Pd / AC1 prepared in Comparative Example 1.

[0031] Figure 5 PdBi prepared in Example 1 0.11 Catalytic performance of Pd / AC1(a) and Pd / AC1(b) prepared in Comparative Example 1 at temperatures of 303K to 333K for the decomposition of formic acid to produce hydrogen.

[0032] Figure 6 PdBi prepared in Example 1 0.11 Catalytic performance of Pd / AC1(a) and Pd / AC1(b) prepared in Comparative Example 1 at temperatures ranging from 298 K to 313 K for the hydrolysis of ammonia borane to produce hydrogen. Detailed Implementation

[0033] The present invention will be further described below with reference to specific embodiments. The illustrative embodiments and descriptions herein are used to explain the present invention, but are not intended to limit the present invention.

[0034] The following examples and comparative examples involve methods for testing the catalytic performance and reusability of the catalysts in the catalytic decomposition of formic acid to produce hydrogen:

[0035] (1) Catalytic performance test: First, weigh 32 mg of catalyst and add it to a 25 mL side-branched reaction tube with a magnetic inlet. Then, add 0.5 mL of deionized water and place the tube in a water bath for 10 min with stirring. Next, quickly inject 1.5 mL of a solution containing 84 μL formic acid (AR, 99%) and 502 mg sodium formate dihydrate (AR, 99.5%) into the reaction tube using a syringe. Start timing and record the gas volume by water displacement. Use the modified formula PV = nRT: Calculate the total gas volume produced under the ambient temperature and pressure conditions during the test, assuming 100% decomposition of formic acid. Then calculate the total gas volume at 25% decomposition. Finally, use the formula... Calculate the Turn Over Frequency (TOF), where P is the local atmospheric pressure (in Pa); V 25％This refers to 25% of the total volume of gases (carbon dioxide and hydrogen, in L) produced by the 100% decomposition of formic acid under experimental conditions; R is the gas constant 8.314; T is the reaction temperature (in K); n metal It refers to the total molar amount of palladium and gold in the catalyst used (unit: mol); t is the reaction time (unit: h);

[0036] (2) Test on the reusability of catalyst: After the first catalytic decomposition of formic acid to produce hydrogen is completed, the reacted catalyst is recovered by filtration, washing and drying; then the catalytic performance of the recovered catalyst is tested by following the same operating steps as above.

[0037] The following examples and comparative examples involve methods for testing the catalytic performance and reusability of the catalysts in the catalytic hydrolysis of ammonia borosilicate to produce hydrogen:

[0038] (1) Catalytic performance test: First weigh 6×10 -6 The catalyst, mmol Pd, was added to a 25 mL side-branched reaction tube equipped with a magnetic magnet, and then placed in a water bath for incubation and stirring for 10 min. 5 mL of a 0.2 mol / L ammonia borane aqueous solution was rapidly injected into the reaction tube using a syringe, and timing was started. The gas volume was recorded by water displacement. A graph was plotted with the gas volume (mL) produced as the Y-axis and time (min) as the X-axis, and the slope represents the hydrogen production rate k (mL·min). -1 Using the formula PV = nRT, the conversion frequency TOF is calculated. Where P is the local atmospheric pressure (in Pa), V is the total gas volume (in mL) when hydrogen production stops under the experimental conditions, R is the gas constant 8.314, T is the reaction temperature (in K), and n Pd This refers to the molar amount of palladium in the catalyst used (unit: mol); t is the reaction time (unit: min), and the unit of TOF is molH2·mol⁻¹. -1 Pd·min -1 ;

[0039] (2) Test on the reusability of the catalyst: After the first catalytic hydrolysis of ammonia borane to produce hydrogen is completed, the same operating steps as above are followed to inject an aqueous solution of ammonia borane to test the catalytic performance of the catalyst.

[0040] Example 1

[0041] Weigh 318 mg of activated carbon AC1 and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution, continue sonicating for 20 min, transfer to a low-temperature reaction bath, and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at this temperature for 4 h. Filter, wash the filter cake with plenty of water, and vacuum dry at 50 °C for 12 h to obtain the Pd / AC1 catalyst. Weigh 118.5 mg of Pd / AC1 in deionized water, sonicate for 30 min, stir at room temperature for 1 h, then add 3 mL of bismuth nitrate aqueous solution (3 mg of bismuth nitrate pentahydrate dissolved in 3 mL of deionized water), continue stirring for 1–2 h, filter, wash, dry, and grind to obtain PdBi. 0.11 / AC1 catalyst.

[0042] Example 2

[0043] Weigh 318 mg of superconducting carbon Ketjen Black ECP and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladium acid solution, continue sonicating for 20 min, transfer to a low-temperature reaction bath, and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at this temperature for 4 h. Filter, wash the filter cake with plenty of water, and vacuum dry at 50 °C for 12 h to obtain the Pd / AC1 catalyst. Weigh 118.5 mg of Pd / AC1 in deionized water, sonicate for 30 min, stir at room temperature for 1 h, then add 3 mL of bismuth nitrate aqueous solution (3 mg of bismuth nitrate pentahydrate dissolved in 3 mL of deionized water), continue stirring for 1–2 h, filter, wash, dry, and grind to obtain PdBi. 0.11 / ECP catalyst.

[0044] Example 3

[0045] Weigh 318 mg of superconducting carbon Ketjen Black ECP600JD and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution, continue sonicating for 20 min, transfer to a low-temperature reaction bath, and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at this temperature for 4 h, filter, wash the filter cake with plenty of water, and vacuum dry at 50 °C for 12 h to obtain the Pd / AC1 catalyst. Weigh 118.5 mg of Pd / AC1 in deionized water, sonicate for 30 min, stir at room temperature for 1 h, then add 3 mL of bismuth nitrate aqueous solution (3 mg of bismuth nitrate pentahydrate dissolved in 3 mL of deionized water), continue stirring for 1–2 h, filter, wash, dry, and grind to obtain PdBi. 0.11 / ECP600JD catalyst.

[0046] Example 4

[0047] Weigh 318 mg of ordered mesoporous carbon CMK-3 and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution, continue sonicating for 20 min, transfer to a low-temperature reaction bath, and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at this temperature for 4 h. Filter, wash the filter cake with plenty of water, and dry under vacuum at 50 °C for 12 h to obtain the Pd / AC1 catalyst. Weigh 118.5 mg of Pd / AC1 in deionized water, sonicate for 30 min, stir at room temperature for 1 h, then add 3 mL of bismuth nitrate aqueous solution (3 mg of bismuth nitrate pentahydrate dissolved in 3 mL of deionized water), continue stirring for 1–2 h, filter, wash, dry, and grind to obtain PdBi. 0.11 / CMK-3 catalyst.

[0048] Example 5

[0049] 318 mg of activated carbon AC1 and 370.6 mg of sodium citrate were weighed and dissolved in 40 mL of water. The mixture was ultrasonically dispersed for 30 min, then 3.15 mL of 0.05 M chloropalladic acid solution was added, and the mixture was ultrasonically dispersed for another 20 min. The mixture was then transferred to a low-temperature reaction bath and stirred at 0 °C for 1 h. Then, 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) was added dropwise at a rate of 0.5 mL / min. After the addition was complete, the mixture was kept at this temperature and stirred for 4 h. The mixture was filtered, and the filter cake was washed with plenty of water. After vacuum drying at 50 °C for 12 h, the Pd / AC1 catalyst was obtained. 121.7 mg of Pd / AC1 was weighed and dissolved in 40 mL of deionized water. The mixture was ultrasonically dispersed for 30 min and stirred at room temperature for 1 h. Then, 1.4 mL of bismuth nitrate aqueous solution (1.4 mg of bismuth nitrate pentahydrate dissolved in 1.4 mL of deionized water) was added, and the mixture was stirred for 1–2 h. After filtration, washing, drying, and grinding, PdBi was obtained. 0.05 / AC1 catalyst.

[0050] Example 6

[0051] 318 mg of activated carbon AC1 and 370.6 mg of sodium citrate were weighed and dissolved in 40 mL of water. The mixture was ultrasonically dispersed for 30 min, then 3.15 mL of 0.05 M palladium chloroacetic acid solution was added, and the mixture was ultrasonically dispersed for another 20 min. The mixture was then transferred to a low-temperature reaction bath and stirred at 0 °C for 1 h. Then, 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) was added dropwise at a rate of 0.5 mL / min. After the addition was complete, the mixture was kept at this temperature and stirred for 4 h. The mixture was filtered, and the filter cake was washed with plenty of water. After vacuum drying at 50 °C for 12 h, the Pd / AC1 catalyst was obtained. 121.7 mg of Pd / AC1 was weighed and dissolved in deionized water. The mixture was ultrasonically dispersed for 30 min and stirred at room temperature for 1 h. Then, 4.2 mL of bismuth nitrate aqueous solution (4.2 mg of bismuth nitrate pentahydrate dissolved in 4.2 mL of deionized water) was added, and the mixture was stirred for 1–2 h. The mixture was filtered, washed, dried, and ground into a fine powder to obtain PdBi. 0.15 / AC1 catalyst.

[0052] Comparative Example 1

[0053] Weigh 318 mg of activated carbon AC1 and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution and continue sonicating for 20 min. Transfer to a low-temperature reaction bath and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at the same temperature for 4 h. Filter and wash the filter cake with a large amount of water. Dry under vacuum at 50 °C for 12 h to obtain the Pd / AC1 catalyst.

[0054] Comparative Example 2

[0055] Weigh 318 mg of superconducting carbon Ketjen Black ECP and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladium acid solution and continue sonicating for 20 min. Transfer to a low-temperature reaction bath and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at the same temperature for 4 h. Filter and wash the filter cake with a large amount of water. Dry under vacuum at 50 °C for 12 h to obtain the Pd / ECP catalyst.

[0056] Comparative Example 3

[0057] Weigh 318 mg of superconducting carbon Ketjen Black ECP600JD and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution and continue sonicating for 20 min. Transfer to a low-temperature reaction bath and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at the same temperature for 4 h. Filter and wash the filter cake with a large amount of water. After vacuum drying at 50 °C for 12 h, the Pd / ECP600JD catalyst is obtained.

[0058] Comparative Example 4

[0059] Weigh 318 mg of ordered mesoporous carbon CMK-3 and 370.6 mg of sodium citrate, dissolve them in 40 mL of water, and sonicate for 30 min. Then add 3.15 mL of 0.05 M chloropalladic acid solution and continue sonicating for 20 min. Transfer to a low-temperature reaction bath and stir at 0 °C for 1 h. Then add 12.6 mL of sodium carbonate solution (containing 48.6 mg of sodium borohydride) dropwise at a rate of 0.5 mL / min. After the addition is complete, continue stirring at the temperature for 4 h. Filter and wash the filter cake with a large amount of water. After vacuum drying at 50 °C for 12 h, the Pd / CMK-3 catalyst is obtained.

[0060] The catalytic performance of the catalysts prepared in Examples 1-6 and Comparative Examples 1-4 for the formic acid dehydrogenation (FAD) reaction was evaluated, and the results are shown in Table 1. To examine the stability of the examples and comparative examples, reusability tests were conducted on Examples 1 and 4-6, and Comparative Examples 1 and 4, and the results are shown in Table 2. Following the test method for catalysts catalyzing the decomposition of formic acid to produce hydrogen, the catalysts prepared in Example 1 and Comparative Example 1 were tested at 303K, 313K, 323K, and 333K. FA :n SF The catalytic performance at a ratio of 1.1M:2.4M is shown in the figure. Figure 5The results showed that the prepared catalyst had good cycle stability for the catalytic dehydrogenation reaction of formic acid. After three reactions, the catalyst still achieved 100% conversion rate and hydrogen selectivity for the decomposition of formic acid to produce hydrogen.

[0061] The catalytic performance of the catalysts prepared in Examples 1-6 and Comparative Examples 1-4 for the hydrolysis of ammonia borane to produce hydrogen was evaluated, and the results are shown in Table 3. To examine the stability of the examples and comparative examples, reusability tests were conducted on Examples 1 and 4, and Comparative Examples 1 and 4, and the results are shown in Table 4. Following the test methods for catalysts catalyzing the hydrolysis of ammonia borane to produce hydrogen, the catalysts prepared in Example 1 and Comparative Example 1 were tested at 298 K, 303 K, 308 K, and 313 K. Pd / n AB The catalytic performance at a ratio of 0.006 is shown in the figure. Figure 6 .

[0062] Table 1. TOF (h) of catalysts for the catalytic decomposition of formic acid to produce hydrogen -1 )value

[0063]

[0064]

[0065] Table 2. Tests on the reusability of catalysts for the decomposition of formic acid to hydrogen.

[0066]

[0067] Table 3. TOF (mol H2·mol⁻¹) for hydrogen production via catalyst catalysis of ammonia boron hydrolysis -1 Pd·min -1 )value

[0068]

[0069] Table 4. Tests on the reusability of the catalyst for hydrogen production via hydrolysis of ammonia boron.

[0070]

[0071] As can be seen from the above examples and comparative examples, the present invention can serve as a simple catalyst preparation method, applicable to different supports, metal precursors, and palladium-bismuth molar ratios, to prepare a series of bismuth-doped palladium-carbon catalysts. When the prepared catalysts are applied to the formic acid decomposition for hydrogen production and the ammonia borane hydrolysis for hydrogen production, they exhibit excellent catalytic activity and stability. This provides a new approach for developing inexpensive, versatile, safe, and efficient catalysts, and further promotes the application of formic acid and ammonia borane as hydrogen storage materials in practical production and daily life.

Claims

1. The use of a bismuth-doped palladium-on-carbon catalyst in the catalytic hydrolysis of ammonia borane to produce hydrogen, characterized in that, The bismuth-doped palladium-carbon catalyst is composed of a carbon support, palladium nanoparticles as the active component supported on the carbon support, and bismuth as the dopant. The total loading of palladium is 1.0 to 10.0 wt%, and the amount of bismuth is 0.05 to 0.15 times the molar amount of palladium loaded in the catalyst. The carbon support is ordered mesoporous carbon CMK-3. The bismuth-doped palladium-carbon catalyst was placed in a reaction tube, and an aqueous solution of ammonia borane was injected. Hydrogen was produced at a reaction temperature of 298K to 313K. The molar concentration of the aqueous solution of ammonia borane is 0.2 mol / L, n Pd / n AB =0.

006.

2. The use of a bismuth-doped palladium-on-carbon catalyst in the catalytic production of hydrogen from formic acid-sodium formate aqueous solution, characterized in that, The bismuth-doped palladium-carbon catalyst is composed of a carbon support, palladium nanoparticles as the active component supported on the carbon support, and bismuth as the dopant. The total loading of palladium is 1.0 to 10.0 wt%, and the amount of bismuth is 0.05 to 0.15 times the molar amount of palladium loaded in the catalyst. The carbon support is ordered mesoporous carbon CMK-3. The bismuth-doped palladium-carbon catalyst is dispersed in water and injected into a formic acid-sodium formate aqueous solution to produce hydrogen at a reaction temperature of 303K to 333K. The molar concentrations of formic acid and sodium formate are 1.1 mol / L and 2.4 mol / L, respectively.

3. The use as described in claim 1 or 2, characterized in that, The preparation method of the bismuth-doped palladium-on-carbon catalyst includes the following steps: Step 1, Preparation of carrier suspension A: Disperse the carbon carrier in deionized water, and then ultrasonically disperse and stir to form carrier suspension A; Step 2, Preparation of palladium precursor solution B: Dissolve sodium citrate in water, then add palladium precursor solution to form palladium precursor solution B; Step 3, Mixed suspension C: Add palladium precursor solution B to carrier suspension A under stirring, and stir at room temperature to form mixed solution C; Step 4, ultrasonic mixing: The mixed suspension C is ultrasonically mixed; Step 5, stirring and impregnation: Transfer the mixed suspension C to a low-temperature constant temperature reaction bath, and stir and impregnate under temperature control; Step 6, reduction: Add sodium carbonate aqueous solution containing sodium borohydride dropwise, and continue reduction and stirring under temperature control; Step 7, filtration and drying: filter by suction and wash the filter cake with a large amount of water. Dry the filter cake in a vacuum oven and grind it to obtain the palladium-on-carbon catalyst. Step 8: Disperse the prepared palladium-on-carbon catalyst in deionized water, and then ultrasonically disperse and stir to form a catalyst suspension D; Step 9, stirring and impregnation: Weigh bismuth nitrate and dissolve it in deionized water. Add the bismuth nitrate aqueous solution to the catalyst suspension D and continue stirring. Step 10, filtration and drying: filter, wash the filter cake with a small amount of water, dry the filter cake in a vacuum oven, grind it, and obtain bismuth-doped palladium carbon catalyst.

4. The use according to claim 3, characterized in that: In step 2: the palladium precursor includes chloropalladium acid, sodium chloropalladium, potassium chloropalladium, palladium nitrate and palladium acetate, and the molar ratio of palladium in the palladium precursor to the molar ratio of sodium citrate is 1:

8.

5. The use according to claim 3, characterized in that: In step 6: the ratio of the total molar amount of palladium in the mixed suspension C to the molar amount of sodium borohydride in the sodium carbonate solution is 1:8 to 1:20; the reduction time is 2h to 16h, and the reduction temperature is 0 to 50℃; the molar concentration of sodium borohydride in the 0.05mol / L sodium carbonate aqueous solution is 0.1mol / L; and the dropping rate of the suspension D is 0.5mL / min.

6. The use according to claim 3, characterized in that: In step 9, the concentration of the bismuth nitrate aqueous solution is 1 mg / mL.

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