Hydrogen production catalyst for bio-ethanol reforming, preparation method and application thereof

Abstract

The invention discloses a bioethanol reforming hydrogen production catalyst and its preparation method and application. The preparation method comprises the following steps: h-BN powder is ball-milled for 2-4 hours at a rotation speed of 400-600rpm in a planetary ball mill, and then a solution is added for ultrasonic treatment to obtain a defect-rich precursor h-BNNS; after the defect-rich precursor h-BNNS is mixed with a solution containing an active metal M salt, the mixture is ball-milled for 10-16 hours at a rotation speed of 600-800rpm in a planetary ball mill, and a sample is collected after the ball milling is completed; the sample is dried at 40-100°C for 6-12 hours; the dried sample is calcined at 400-700°C and H2 atmosphere to obtain a catalyst. The catalyst prepared by the present invention has the advantages of low metal loading, high dispersion, and resistance to carbon deposition, can achieve high hydrogen production efficiency at a lower temperature, and provides a more effective solution for bioethanol reforming hydrogen production.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of renewable energy fuel cell hydrogen source. More particularly, the present application relates to a bio-ethanol reforming hydrogen catalyst, a preparation method and application thereof. BACKGROUND

[0002] Hydrogen energy is an ideal energy with high efficiency and cleanness, and plays an important role in the sustainable development of global energy system. With the development and application of fuel cell technology, hydrogen-oxygen fuel cell has stronger technical adaptability than lithium battery in future underwater energy storage / charging equipment, especially in long-time submarine, and can convert chemical energy of hydrogen into electrical energy, has high conversion efficiency, is clean and pollution-free, and is an excellent hydrogen energy utilization technology. Biomass is the only renewable carbon source, which is essentially the solar energy fixed in the form of chemical energy, and is widely distributed and abundant in nature. The hydrogen production technology based on biomass energy is one of the hydrogen production technologies with the potential to replace traditional fossil energy hydrogen production.

[0003] The second-generation biofuel refers to fuel made from non-edible biomass such as catering waste oil and forestry waste. Among them, bio-ethanol can be produced on a large scale by fermentation of various biomasses, and is a widely available renewable hydrogen production raw material. Compared with fossil energy hydrogen production technology, bio-ethanol reforming hydrogen has the following advantages: (1) crude ethanol does not contain sulfur element, and will not cause pollution and catalyst poisoning in subsequent processing; (2) the carbon in ethanol molecule comes from the CO2 in the atmosphere fixed by plant photosynthesis; (3) ethanol is a liquid at room temperature, has low toxicity, and is convenient for transportation and storage; (4) the hydrogen-carbon ratio in ethanol molecule is 3, which is a suitable hydrogen production raw material.

[0004] Bio-ethanol steam reforming hydrogen can produce 6 mol of hydrogen from 1 mol of ethanol in theory under sufficient water, and has the highest hydrogen production efficiency compared with other liquid carbon-hydrogen fuels such as acetic acid. However, the ethanol reforming reaction is endothermic, and due to the weak oxidation ability of water molecules, carbon deposition is easily generated during the reforming process, leading to catalyst deactivation. How to regulate the reaction path of ethanol steam reforming by reasonable design of catalyst to inhibit the generation of carbon deposition is the biggest challenge in the development of current ethanol steam reforming catalysts. Generally, non-noble metal catalysts such as Ni-based and Co-based catalysts have strong C-C bond breaking ability and catalytic activity, and are commonly used catalysts for ethanol steam reforming reaction, but sintering and carbon deposition often lead to deactivation of non-noble metal catalysts. Noble metal (such as Ru-based and Rh-based) catalysts have excellent ethanol steam reforming performance and low deactivation rate, but the high price limits their large-scale application.

[0005] Therefore, based on the above, it is urgently needed to prepare a low-loading and high-dispersion carbon deposition resistant catalyst through research, to regulate metal-support interaction, to improve the hydrogen production efficiency of the catalyst under the premise of ensuring the long-term stability of the catalyst, and to realize the application of the catalyst for large-scale ethanol steam reforming to produce hydrogen. SUMMARY

[0006] The application aims to provide a bio-ethanol reforming hydrogen catalyst, a preparation method and application thereof, aiming to solve the problems of low hydrogen production rate, poor stability and easy carbon deposition of existing bio-ethanol reforming hydrogen catalysts, to improve the performance of the catalyst by optimizing the preparation process of the catalyst, and to realize efficient and stable bio-ethanol reforming to produce hydrogen.

[0007] In order to achieve these objects and other advantages of the present application, a preparation method of a bio-ethanol reforming hydrogen catalyst is provided, comprising the following steps:

[0008] S1, preparation of a surface functionalized precursor: h-BN powder is ball milled in a planetary ball mill at a speed of 400-600 rpm for 2-4 h, then a solution is added for ultrasonic treatment to obtain a defect-rich precursor h-BNNS;

[0009] S2, introduction of active metal centers by mechanical ball milling: the defect-rich precursor h-BNNS and a solution containing active metal M salt are mixed, then ball milled in a planetary ball mill at a speed of 600-800 rpm for 10-16 h, and the sample is collected after ball milling;

[0010] S3, drying treatment: the obtained sample is dried at 40-100℃ for 6-12 h;

[0011] S4, calcination treatment: the dried sample is calcined at 400-700℃ under H2 atmosphere to obtain the bio-ethanol reforming hydrogen catalyst M / h-BNNS.

[0012] Preferably, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the solution in S1 is one or more of water, ethanol and ethylene glycol.

[0013] Preferably, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the active metal M salt in S2 is one of Pd salt, Pt salt, Ru salt, Rh salt, Ir salt, Co salt or Ni salt.

[0014] Preferably, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the mass of the active metal M in S2 is 0.2-1 wt% of the total mass of the active metal M and the defect-rich precursor h-BNNS.

[0015] Preferably, in the preparation method of the bioethanol reforming hydrogen production catalyst, the temperature is raised to 400-700° C. at a heating rate of 2-10° C. / min in S4, and the calcination time is 2-10 h.

[0016] Preferably, the method for preparing the bioethanol reforming hydrogen production catalyst comprises the following steps:

[0017] S1. Preparation of surface functionalized precursors:

[0018] 2.0-3.0g of h-BN powder was ball-milled in a planetary ball mill at 400-600rpm for 2-4h. 50mL of ethanol solution was added with 0.04-0.06g of sodium dodecylbenzenesulfonate, 0.03-0.07g of polyvinylpyrrolidone, and 0.02-0.06g of nano-alumina. After stirring to fully dissolve the sodium dodecylbenzenesulfonate and polyvinylpyrrolidone and uniformly disperse the nano-Al2O3 in the solution, the ball-milled h-BN powder was added and ultrasonicated for 10-60min to obtain the defect-rich precursor h-BNNS.

[0019] S2. Mechanical ball milling method to introduce active metal centers:

[0020] Weigh 0.01-0.06g of active metal M salt and dissolve it in 20-30mL of deionized water. Then add 0.02-0.04g of ascorbic acid, 0.01-0.03g of disodium ethylenediaminetetraacetic acid, and 0.02-0.05g of sodium borohydride. After stirring evenly, add the defect-rich precursor h-BNNS. Then, ball mill at 600-800rpm in a planetary ball mill for 10-16h. After ball milling, collect the sample;

[0021] S3, drying process:

[0022] The obtained sample was dried at 40-100°C for 6-12h;

[0023] S4, calcination treatment:

[0024] The dried sample was calcined in a H2 atmosphere, the temperature was raised to 400-700°C at a heating rate of 2-10°C / min, and maintained for 2-10 hours to obtain the bioethanol reforming hydrogen production catalyst M / h-BNNS.

[0025] Preferably, in the method for preparing the bioethanol reforming hydrogen production catalyst, S1, preparation of a surface functionalized precursor:

[0026] Take 2.5g h-BN powder in a planetary ball mill at a speed of 500 rpm for 3h; prepare 50mL ethanol solution, and add 0.05g sodium dodecyl benzene sulfonate, 0.05g polyvinylpyrrolidone and 0.04g nano alumina to it, stir to dissolve sodium dodecyl benzene sulfonate and polyvinylpyrrolidone, and disperse nano Al2O3 uniformly in the solution, then add the h-BN powder after ball milling, ultrasonic treatment for 1h, to obtain a precursor h-BNNS rich in defects;

[0027] S2, mechanical ball milling method for introducing active metal centers:

[0028] Take 0.05g of active metal M salt, dissolve in 25mL of deionized water, then add 0.03g of ascorbic acid, 0.02g of ethylenediaminetetraacetic acid disodium and 0.03g of sodium borohydride, stir uniformly, then add the precursor h-BNNS rich in defects, and then ball mill in a planetary ball mill at a speed of 700 rpm for 13h, and collect the sample after ball milling.

[0029] A biological ethanol reforming hydrogen catalyst is prepared by the above preparation method.

[0030] The application of the biological ethanol reforming hydrogen catalyst in catalyzing ethanol steam reforming is as follows:

[0031] The catalyst is loaded into a fixed bed reactor, pre-reduced, and then reacted with ethanol steam and carrier gas.

[0032] Preferably, in the application of the biological ethanol reforming hydrogen catalyst in catalyzing ethanol steam reforming, the pre-reduction treatment conditions are: reduction temperature of 400-600℃, reduction atmosphere composed of H2 and N2, and reduction time of 1-2h.

[0033] The present application at least includes the following beneficial effects:

[0034] The high-dispersion carbon-deposition-resistant biological ethanol reforming hydrogen catalyst of the present application has the characteristics of low metal loading and high dispersion. This enables the catalyst to exhibit excellent catalytic activity at a lower temperature, achieving high hydrogen production efficiency. In the reaction temperature range of 500-600℃, some catalysts catalyze ethanol steam reforming reaction, with ethanol conversion rate reaching 80-100% and H2 production rate reaching 70-100%, greatly improving the efficiency of biological ethanol reforming hydrogen production and reducing energy consumption.

[0035] The carrier has abundant defect sites, which provide a large number of anchoring sites for active metals. Through metal-carrier interaction, the active metals synergize with the defect sites, which can effectively eliminate and inhibit the generation of carbon deposition in the catalytic process. Taking the catalysts of example 10 and example 15 as examples, in the stability test at 550 DEG C for 40 hours, the ethanol conversion rate and hydrogen yield are close to 100%, which shows good stability, prolongs the service life of the catalyst, and reduces the cost increase caused by frequent replacement of the catalyst.

[0036] The catalyst raw materials of the application are widely available, such as h-BN powder, common active metal salt and various additives, which are easy to obtain. The preparation method includes ball milling, ultrasonic, drying, calcination and other conventional operations, which is simple in process and easy to operate, without the need for complex equipment and technology, which is conducive to large-scale industrialized production, and provides strong technical support for the wide application of bio-ethanol reforming hydrogen technology.

[0037] In the process of catalyzing bio-ethanol reforming to produce hydrogen, the by-product selectivity is low, and the generated hydrogen production purity is high. This not only reduces the cost of subsequent gas separation and purification, improves the production efficiency, but also meets the requirements of fuel cells and other application scenarios for high-purity hydrogen, and enhances the market competitiveness of the product.

[0038] Other advantages, objects and features of the present application will be partly embodied in the following description, and will be partly understood by those skilled in the art through research and practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 X-ray diffraction patterns of M / h-BNNS catalysts provided for examples 6-15;

[0040] Figure 2 Stability test chart (40 h) of ethanol conversion rate and hydrogen yield in the catalytic ethanol steam reforming reaction of Ru / h-BNNS catalysts provided for example 10 and example 15;

[0041] Figure 3 Thermogravimetric-differential thermal analysis chart of M / h-BNNS catalysts provided for example 10 and example 15 after stability test. DETAILED DESCRIPTION

[0042] The application will be further described in detail below with reference to the accompanying drawings, so that those skilled in the art can implement it according to the description.

[0043] It should be noted that the experimental methods in the following embodiments are conventional methods, and the reagents and materials are commercially available unless otherwise specified.

[0044] The application provides a preparation method of a hydrogen catalyst for bio-ethanol reforming, comprising the following steps:

[0045] S1, preparation of a surface functionalized precursor: h-BN powder is ball milled in a planetary ball mill at a rotating speed of 400-600 rpm for 2-4 h, and then a solution is added for ultrasonic treatment to obtain a defect-rich precursor h-BNNS;

[0046] Purpose: By ball milling and ultrasonic treatment, the crystal lattice structure of h-BN is changed to form a defect-rich precursor h-BNNS, so that more anchoring sites are provided for subsequent loading of active metals, and the carrying capacity and binding force of the carrier for the active metals are improved.

[0047] Beneficial effect: h-BN is changed in crystal lattice structure under the action of a grinding medium in the planetary ball mill at a rotating speed of 400-600 rpm for 2-4 h. The defect of h-BN is further increased by using the energy of ultrasonic waves in the subsequent ultrasonic treatment of the solution. This treatment mode makes the h-BNNS thinner in layer and better in dispersibility, which not only provides abundant adhesion sites for the active metals and is conducive to the uniform dispersion of the active metals, but also enhances the interaction between the carrier and the active metals. This step lays a foundation for preparing a high-dispersion and carbon-deposition-resistant catalyst and is crucial for improving the overall performance of the catalyst.

[0048] S2, introduction of an active metal center by a mechanical ball milling method: the defect-rich precursor h-BNNS and a solution containing an active metal M salt are mixed, and then ball milled in a planetary ball mill at a rotating speed of 600-800 rpm for 10-16 h, and the sample is collected after the ball milling is completed;

[0049] Purpose: The active metal M salt is uniformly loaded on the defect-rich precursor h-BNNS, more active sites are created on the surface of the catalyst by the mechanical ball milling method, the interaction between the metal and the carrier is enhanced, and the activity and selectivity of the catalyst are optimized.

[0050] Beneficial effect: The defect-rich precursor h-BNNS and the solution containing the active metal M salt are mixed at a rotating speed of 600-800 rpm for 10-16 h. The high-energy impact in the ball milling process, on the one hand, produces more defect sites and active sites on the surface of the catalyst, provides more active centers for the reaction, and is conducive to improving the activity of the catalyst and enhancing the selectivity of the reaction; on the other hand, the interface reconstruction between the metal and the carrier is realized, the electronic metal-carrier interaction is enhanced, the surface electronic structure is regulated, and the performance of the catalyst is improved. In addition, the mechanical force makes the metal particles have higher dispersity, which helps to maximize the exposure area of the metal and improves the utilization efficiency of the metal. Compared with other active metal introduction methods, this method has significant advantages.

[0051] S3, drying treatment: drying the obtained sample at 40-100℃ for 6-12 h;

[0052] Purpose: to remove water and organic solvents from the sample, make the active metal salt and additives more closely attached to the surface of h-BNNS, and preliminarily solidify the catalyst structure to prepare for subsequent calcination.

[0053] Beneficial effect: drying at 40-100℃ for 6-12 h can effectively remove water and residual organic solvents from the sample, preventing these substances from having a negative impact on the catalyst structure and performance during subsequent calcination. Drying treatment makes the active metal salt and additives firmly attached to the surface of h-BNNS, preliminarily forming a stable structure, which helps to maintain the dispersion state of active metals during calcination, avoids their agglomeration, and ensures that the catalyst has good activity and stability in subsequent reactions. It is an indispensable link for preparing high-performance catalysts.

[0054] S4, calcination treatment: calcining the dried sample at 400-700℃ in H2 atmosphere to obtain the bio-ethanol reforming hydrogen catalyst M / h-BNNS.

[0055] Purpose: to heat the dried sample to 400-700℃ in H2 atmosphere, reduce metal ions to metal elements, promote chemical bonding between metal and support, optimize the crystal structure and surface properties of the catalyst, and ultimately obtain a highly dispersed and carbon deposition resistant bio-ethanol reforming hydrogen catalyst M / h-BNNS.

[0056] Beneficial effect: hydrogen as a reducing gas fully reduces metal ions to metal elements during calcination, improving the catalytic activity of active metals. Calcination at 400-700℃ in H2 atmosphere promotes the formation of stronger chemical bonds between metal and support, enhances the electron metal-support interaction, optimizes the crystal structure of the catalyst, and improves its thermal and chemical stability. At the same time, calcination treatment can further remove impurities, purify the catalyst surface, and increase the number and activity of active sites, so that the prepared catalyst has the characteristics of high dispersion and resistance to carbon deposition, exhibits excellent catalytic activity and stability in bio-ethanol reforming hydrogen reaction, effectively improves hydrogen production rate, and inhibits carbon deposition, meeting the needs of practical applications.

[0057] Research has found that two-dimensional hexagonal boron nitride nanosheets (h-BNNS) are composed of several layers of hexagonal arrangement of alternating boron and nitrogen atoms, also known as "white graphene" or "non-carbon graphene", which has excellent oxidation resistance, high chemical stability and thermal performance. However, pristine hexagonal boron nitride (h-BN) is a metallic inert carrier that can be adjusted through defect engineering and chemical modification. The increase of boron nitride defects can improve the metal dispersion and provide anchoring sites for metal atoms.

[0058] The preparation method of the high-dispersion carbon-resistant bio-ethanol reforming hydrogen catalyst provided by the application has unique technical advantages and good application prospects.

[0059] In the preparation process, first, the two-dimensional boron nitride (h-BN) is subjected to surface functionalization treatment. The h-BN powder is placed in a planetary ball mill and ball milled at a speed of 400-600 rpm for 2-4 h, and then subjected to solution ultrasonic treatment. This process changes the crystal structure of the h-BN and forms a defect-rich structure on the surface of the h-BN, obtaining a defect-rich precursor h-BNNS. This defect-rich structure provides more anchoring sites for the subsequent loading of active metals, greatly facilitating the uniform dispersion and stability of the active metals.

[0060] Next, the active metal is introduced by mechanical ball milling. The defect-rich precursor h-BNNS is mixed with a solution containing active metal M salt and placed in a planetary ball mill and ball milled at a speed of 600-800 rpm for 10-16 h. In this process, the high-energy impact of mechanical ball milling not only produces more defect sites and active sites on the surface of the catalyst, but also enhances the interaction between the metal and the support, thereby improving the activity and selectivity of the catalyst, and enabling the active metal to be successfully embedded in the crystal lattice structure.

[0061] Subsequently, drying and calcination treatment are performed in sequence. The drying treatment is performed at 40-100℃ for 6-12 h to remove water and organic solvents from the sample, allowing the active metal salt and additives to adhere more closely to the surface of the h-BNNS and preliminarily solidify the catalyst structure. The calcination treatment is performed at 400-700℃ in a H2 atmosphere, which further reduces the metal ions to metal elements, greatly optimizing the crystal structure and surface properties of the catalyst and further enhancing the chemical bonding between the metal and the support.

[0062] The high-dispersion carbon-resistant bio-ethanol reforming hydrogen catalyst M / h-BNNS prepared by the above method has a high dispersion of active components, and exhibits high catalytic activity and stability even at a low loading. In addition, the catalyst has abundant defect sites, which are beneficial for the adsorption and dissociation of carbon monoxide and water vapor in the catalytic steam reforming reaction of low-carbon alcohols represented by ethanol, effectively eliminating and inhibiting the formation of carbon deposits, thereby achieving stable and efficient hydrogen production. Therefore, the catalyst can effectively improve the hydrogen production rate, enhance its stability, and reduce production costs in the bio-ethanol reforming hydrogen reaction, and has a broad application prospect in related fields. In another aspect, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the solution in S1 is one or more of water, ethanol, and ethylene glycol.

[0063] The solution is limited to one or more of water, ethanol, and ethylene glycol, which provides a clear solution selection range for preparing the defect-rich precursor h-BNNS. These common solutions can fully interact with the h-BN powder during ultrasonic treatment, helping to form more abundant and uniform defect structures. At the same time, these solutions are widely available and relatively low-cost, facilitating large-scale production. The choice of different solutions can also be adjusted according to actual needs to optimize the preparation process, improve the quality of the precursor, and thus enhance the performance of the final catalyst in the bio-ethanol reforming reaction to produce hydrogen.

[0064] In another aspect, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the active metal M salt in S2 is one of Pd salt, Pt salt, Ru salt, Rh salt, Ir salt, Co salt, or Ni salt.

[0065] The type of active metal M salt is specified, providing a basis for selecting the appropriate active metal, so that the catalyst can better perform its catalytic role in the bio-ethanol reforming reaction to produce hydrogen.

[0066] These metal salts have different catalytic activity and selectivity in the bio-ethanol reforming reaction to produce hydrogen. By specifying the type of active metal M salt, it is easier to select the appropriate metal salt according to specific reaction requirements and cost requirements. For example, noble metal salts such as Pd salt and Pt salt have high catalytic activity but are relatively expensive, while non-noble metal salts such as Co salt and Ni salt are less expensive and also have some catalytic activity. By reasonably selecting the active metal M salt, the production cost can be reduced while ensuring the performance of the catalyst, improving the cost-effectiveness of the catalyst and enhancing its competitiveness in practical applications.

[0067] In another aspect, in the preparation method of the bio-ethanol reforming hydrogen catalyst, the mass of the active metal M in S2 is 0.2-1 wt% of the total mass of the active metal M and the defect-rich precursor h-BNNS.

[0068] Determining the reasonable content range of the active metal M in the catalyst ensures the performance of the catalyst while avoiding excessive metal usage that increases costs or insufficient metal usage that affects catalytic effectiveness.

[0069] Controlling the mass fraction of the active metal M within the range of 0.2-1 wt% can effectively control costs while ensuring that the catalyst has high activity and stability. Lower metal loading can reduce the use of noble metals and lower production costs, while appropriate loading can ensure that the active metal is fully dispersed on the surface of the carrier and can perform its catalytic role. This content range has been experimentally verified to enable the catalyst to achieve good catalytic results in the bio-ethanol reforming reaction to produce hydrogen, improve hydrogen production rate, and inhibit the formation of carbon deposits, thus having good economic benefits and application value.

[0070] In another aspect, the method for preparing the bio-ethanol reforming hydrogen catalyst includes the following steps:

[0071] Controlling the heating rate and calcination time during the calcination process can optimize the structure and performance of the catalyst, and improve the activity and stability of the catalyst in the bio-ethanol reforming hydrogen reaction.

[0072] The appropriate heating rate and calcination time have a significant impact on the structure and performance of the catalyst. Too fast or too slow heating rate, or too long or too short calcination time, can result in an undesirable structure of the catalyst, affecting its catalytic activity and stability. Controlling the heating rate at 2-10℃ / min and the calcination time at 2-10h can allow the catalyst to fully react during the calcination process, form a stable structure, enhance the interaction between the metal and the support, and improve the number and quality of active sites of the catalyst. The catalyst prepared in this way can more effectively promote the reaction and improve the hydrogen yield in the bio-ethanol reforming hydrogen reaction, while maintaining good stability.

[0073] In another aspect, the method for preparing the bio-ethanol reforming hydrogen catalyst includes the following steps:

[0074] S1, preparation of surface functionalized precursor:

[0075] Take 2.0-3.0g h-BN powder in a planetary ball mill at a speed of 400-600 rpm for 2-4h; during the ball milling process, the h-BN powder is impacted and rubbed by the grinding medium, and the crystal structure gradually changes, creating conditions for the formation of more defects. Prepare 50mL ethanol solution, and add 0.04-0.06g sodium dodecyl benzene sulfonate (SDBS), 0.03-0.07g polyvinylpyrrolidone (PVP) and 0.02-0.06g nano alumina (Al2O3) to it, SDBS as a surfactant, can reduce the surface tension of the solution, enhance the cavitation effect in the subsequent ultrasonic process; PVP with good dispersion performance and high molecular chain structure, can prevent h-BN sheet from agglomeration; nano Al2O3 has high specific surface area and chemical stability, although it is not soluble in ethanol solution, but can adsorb SDBS and PVP, the three form a composite system, together promote the generation and uniform distribution of h-BN surface defects. Stirring makes sodium dodecyl benzene sulfonate and polyvinylpyrrolidone fully dissolved, and nano Al2O3 uniformly dispersed in the solution, then add the ball-milled h-BN powder, ultrasonic treatment for 10-60min, get the precursor h-BNNS rich in defects; during the ultrasonic process, ultrasonic cavitation bubbles are generated in the solution, the energy released by the collapse of the bubbles further destroys the structure of h-BN, increases the number of defects, and at the same time makes the additives better interact with h-BN, finally get the precursor h-BNNS rich in defects.

[0076] S2, mechanical ball milling method to introduce active metal center:

[0077] Take 0.01-0.06g active metal M salt, dissolve in 20-30mL deionized water, then add 0.02-0.04g ascorbic acid, 0.01-0.03g disodium EDTA (EDTA-2Na) and 0.02-0.05g sodium borohydride (NaBH4), ascorbic acid has reducing property, can partially reduce metal ions, make the metal in low valence state or atomic state more uniformly dispersed on the surface of h-BNNS; EDTA-2Na as a complexing agent, can control the release speed of metal ions, avoid agglomeration; NaBH4 is also a strong reducing agent, cooperates with ascorbic acid to further reduce metal ions, and forms more active sites on the surface of h-BNNS, promotes the combination of metal and carrier. After stirring uniformly, add the precursor h-BNNS rich in defects, then ball mill in a planetary ball mill at a speed of 600-800 rpm for 10-16h, collect the sample after ball milling; during the ball milling process, high-energy impact makes the catalyst surface produce more defect sites and active sites, promotes the interaction between active metal and carrier, is beneficial to the loading and dispersion of active metal, and the sample is collected after ball milling.

[0078] S3, drying treatment:

[0079] The obtained sample is dried at 40-100℃ for 6-12h; during the drying process, water and organic solvent in the sample are removed, and the active metal salt and additives are more closely attached to the surface of the h-BNNS, preliminarily solidifying the structure of the catalyst and preparing for the subsequent calcination process.

[0080] S4, calcination process:

[0081] The dried sample is subjected to a calcination process under a H2 atmosphere, and the temperature is raised to 400-700℃ at a heating rate of 2-10℃ / min and maintained for 2-10h, thereby obtaining the bio-ethanol reforming hydrogen catalyst M / h-BNNS. Hydrogen gas, as a reducing gas, further reduces metal ions to metal elements during the calcination process, promotes the chemical bonding between the metal and the carrier, enhances the electron metal-carrier interaction, and improves the performance of the catalyst. A suitable heating rate and calcination temperature and time can ensure that the reduction reaction proceeds sufficiently without damaging the structure of the catalyst, and ultimately obtain a highly dispersed and carbon deposition resistant bio-ethanol reforming hydrogen catalyst M / h-BNNS.

[0082] In the surface functionalized precursor preparation step, the addition of sodium dodecyl benzene sulfonate, polyvinylpyrrolidone and nano-alumina can synergistically promote the generation and uniform distribution of h-BN surface defects, and improve the quality of the precursor. In the active metal center introduction step, the addition of ascorbic acid, disodium ethylenediaminetetraacetate and sodium borohydride helps to reduce and uniformly disperse metal ions, and enhances the interaction between the metal and the carrier. The optimized drying and calcination conditions further improve the performance of the catalyst. Overall, this preparation method can make the catalyst exhibit higher activity, stability and carbon deposition resistance in the bio-ethanol reforming hydrogen reaction, effectively improving the hydrogen yield.

[0083] In another aspect, the preparation method of the bio-ethanol reforming hydrogen catalyst comprises the following steps:

[0084] 2.5g of h-BN powder is ball milled in a planetary ball mill at a speed of 500rpm for 3h; 50mL of ethanol solution is prepared, and 0.05g of sodium dodecyl benzene sulfonate, 0.05g of polyvinylpyrrolidone and 0.04g of nano-alumina are added thereto. After stirring to fully dissolve the sodium dodecyl benzene sulfonate and the polyvinylpyrrolidone and uniformly disperse the nano-Al2O3 in the solution, the ball-milled h-BN powder is added, and ultrasonic treatment is performed for 60min, thereby obtaining a defect-rich precursor h-BNNS;

[0085] S2, mechanical ball milling method to introduce active metal center:

[0086] Take 0.05 g of active metal M salt, dissolve in 25 mL of deionized water, and then add 0.03 g of ascorbic acid, 0.02 g of ethylenediaminetetraacetic acid disodium salt, and 0.03 g of sodium borohydride, stir uniformly, then add the defect-rich precursor h-BNNS, and then ball mill in a planetary ball mill at a speed of 700 rpm for 13 h. After ball milling, the sample is collected.

[0087] A bio-ethanol reforming hydrogen catalyst is prepared by the above preparation method.

[0088] The application of the bio-ethanol reforming hydrogen catalyst in catalyzing ethanol steam reforming is as follows:

[0089] The catalyst is loaded into a fixed bed reactor, pre-reduced, and then reacted with ethanol steam and carrier gas.

[0090] In another aspect, the application of the bio-ethanol reforming hydrogen catalyst in catalyzing ethanol steam reforming is as follows: the pre-reduction conditions are as follows: reduction temperature is 400-600°C, reduction atmosphere is composed of H2 and N2, and reduction time is 1-2 h.

[0091] Examples 1-5

[0092] This example provides the synthesis of defect-rich precursor h-BNNS using different solutions and different ultrasonic times, which is prepared by the following method:

[0093] Accurately weigh 2.5 g of h-BN powder, ball mill in a planetary ball mill at a speed of 500 rpm for 3 h, then add 50 mL of ethanol and ultrasonically for 10 min, 30 min and 60 min respectively, to obtain the defect-rich precursor h-BNNS.

[0094] Replace the above 50 mL of ethanol solution with 50 mL of deionized water and 50 mL of ethylene glycol solution respectively, to prepare the defect-rich precursor h-BNNS with different surface functionalization. The specific addition amount is shown in Table 1.

[0095] Table 1 Synthesis of h-BNNS in Examples 1-5 and control of its amount

[0096]

[0097] Example 6

[0098] This example provides a highly dispersed and carbon deposition resistant bio-ethanol reforming hydrogen catalyst Pd / h-BNNS, and the preparation process is as follows:

[0099] Accurately weigh 0.010 g of palladium chloride, dissolve in 25 mL of deionized water, and then add to the defect-rich precursor h-BNNS obtained in Example 1. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry the obtained sample in an oven at 60°C for 12 h, and then place in a tube furnace to be calcined. Under a flowing H2atmosphere, heat to 600°C at a rate of 2°C / min, and then calcine for 2 h to obtain a Pd / h-BNNS (0.2) catalyst.

[0100] Example 7

[0101] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Pd / h-BNNS, and the preparation process is as follows:

[0102] Accurately weigh 0.020 g of palladium chloride, dissolve in 25 mL of deionized water, and then add to the defect-rich precursor h-BNNS obtained in Example 2. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry the obtained sample in an oven at 60°C for 12 h, and then place in a tube furnace to be calcined. Under a flowing H2atmosphere, heat to 600°C at a rate of 2°C / min, and then calcine for 2 h to obtain a Pd / h-BNNS (0.5) catalyst.

[0103] Example 8

[0104] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Pd / h-BNNS, and the preparation process is as follows:

[0105] Accurately weigh 0.033 g of palladium chloride, dissolve in 25 mL of deionized water, and then add to the defect-rich precursor h-BNNS obtained in Example 3. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry the obtained sample in an oven at 60°C for 12 h, and then place in a tube furnace to be calcined. Under a flowing H2atmosphere, heat to 600°C at a rate of 2°C / min, and then calcine for 2 h to obtain a Pd / h-BNNS catalyst.

[0106] Example 9

[0107] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Pt / h-BNNS, and the preparation process is as follows:

[0108] Accurately weigh 0.034 g of platinum chloride, dissolve in 25 mL of deionized water, and then add to the precursor h-BNNS rich in defects obtained in Example 3, and ball mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, the sample is collected, dried in an oven at 60℃ for 12 h, and then placed in a tube furnace for calcination. The temperature is raised to 600℃ at a rate of 2℃ / min under a flowing H2 atmosphere, and the calcination is performed for 2 h to obtain a Pt / h-BNNS catalyst.

[0109] Example 10

[0110] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Ru / h-BNNS, and the preparation process is as follows:

[0111] Accurately weigh 0.05 g of ruthenium chloride, dissolve in 25 mL of deionized water, and then add to the precursor h-BNNS rich in defects obtained in Example 3, and ball mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, the sample is collected, dried in an oven at 60℃ for 12 h, and then placed in a tube furnace for calcination. The temperature is raised to 600℃ at a rate of 2℃ / min under a flowing H2 atmosphere, and the calcination is performed for 2 h to obtain a Ru / h-BNNS catalyst.

[0112] Example 11

[0113] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Rh / h-BNNS, and the preparation process is as follows:

[0114] Accurately weigh 0.041 g of rhodium chloride, dissolve in 25 mL of deionized water, and then add to the precursor h-BNNS rich in defects obtained in Example 3, and ball mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, the sample is collected, dried in an oven at 60℃ for 12 h, and then placed in a tube furnace for calcination. The temperature is raised to 600℃ at a rate of 2℃ / min under a flowing H2 atmosphere, and the calcination is performed for 2 h to obtain a Rh / h-BNNS catalyst.

[0115] Example 12

[0116] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen production catalyst Ir / h-BNNS, and the preparation process is as follows:

[0117] Accurately weigh 0.035 g of iridium chloride, dissolve it in 25 mL of deionized water, and then add it to the defect-rich precursor h-BNNS obtained in Example 3. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry it in an oven at 60°C for 12 h, and then place it in a tube furnace for calcination. Under a flowing H2 atmosphere, heat it to 600°C at a rate of 2°C / min, and then calcine it for 2 h. An Ir / h-BNNS catalyst is obtained.

[0118] Example 13

[0119] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen catalyst Co / h-BNNS, and the preparation process is as follows:

[0120] Accurately weigh 0.044 g of cobalt chloride, dissolve it in 25 mL of deionized water, and then add it to the defect-rich precursor h-BNNS obtained in Example 3. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry it in an oven at 60°C for 12 h, and then place it in a tube furnace for calcination. Under a flowing H2 atmosphere, heat it to 600°C at a rate of 2°C / min, and then calcine it for 2 h. A Co / h-BNNS catalyst is obtained.

[0121] Example 14

[0122] This example provides a highly dispersed carbon deposition resistant bioethanol reforming hydrogen catalyst Ni / h-BNNS, and the preparation process is as follows:

[0123] Accurately weigh 0.044 g of nickel chloride, dissolve it in 25 mL of deionized water, and then add it to the defect-rich precursor h-BNNS obtained in Example 3. Mill in a planetary ball mill at a speed of 700 rpm for 13 h. After the ball milling is completed, collect the sample. Dry it in an oven at 60°C for 12 h, and then place it in a tube furnace for calcination. Under a flowing H2 atmosphere, heat it to 600°C at a rate of 2°C / min, and then calcine it for 2 h. A Ni / h-BNNS catalyst is obtained.

[0124] Example 15

[0125] Take 2.5 g of h-BN powder and mill it in a planetary ball mill at a speed of 500 rpm for 3 h. Prepare 50 mL of an ethanol solution, and then add 0.05 g of sodium dodecyl benzene sulfonate, 0.05 g of polyvinylpyrrolidone, and 0.04 g of nano-alumina to the solution. Stir to fully dissolve the sodium dodecyl benzene sulfonate and the polyvinylpyrrolidone, and uniformly disperse the nano-Al2O3 in the solution. Then add the milled h-BN powder, and ultrasonically treat it for 1 h. A defect-rich precursor h-BNNS is obtained.

[0126] Take 0.05 g of active metal M salt (ruthenium chloride), dissolve in 25 mL of deionized water, and then add 0.03 g of ascorbic acid, 0.02 g of disodium ethylenediaminetetraacetate, and 0.03 g of sodium borohydride, stir until uniform, then add the precursor h-BNNS rich in defects, and then ball mill in a planetary ball mill at a speed of 700 rpm for 13 h, and then collect the sample after the ball milling is completed;

[0127] Dry the obtained sample in an oven at 60°C for 12 h;

[0128] Place the dried sample in a tube furnace and perform calcination treatment in an H2 atmosphere, increase the temperature to 600°C at a rate of 2°C / min, and maintain for 2 h, to obtain a hydrogen catalyst for bio-ethanol reforming Ru / h-BNNS.

[0129] Example 16

[0130] Different from Example 15, take 0.03 g of active metal M salt (ruthenium chloride), dissolve in 25 mL of deionized water. The rest is the same as Example 15.

[0131] Example 17

[0132] Different from Example 15, take 0.06 g of active metal M salt (ruthenium chloride), dissolve in 25 mL of deionized water. The rest is the same as Example 15.

[0133] Example 18

[0134] Different from Example 15, prepare 50 mL of an ethanol solution, and then add 0.04 g of sodium dodecyl benzene sulfonate, 0.03 g of polyvinylpyrrolidone, and 0.02 g of nano-alumina to the solution. The rest is the same as Example 15.

[0135] Example 19

[0136] Different from Example 15, prepare 50 mL of an ethanol solution, and then add 0.06 g of sodium dodecyl benzene sulfonate, 0.07 g of polyvinylpyrrolidone, and 0.06 g of nano-alumina to the solution. The rest is the same as Example 15.

[0137] Example 20

[0138] Different from Example 15, add 0.02 g of ascorbic acid, 0.01 g of disodium ethylenediaminetetraacetate, and 0.02 g of sodium borohydride. The rest is the same as Example 15.

[0139] Example 21

[0140] Different from Example 15, add 0.04 g of ascorbic acid, 0.03 g of disodium ethylenediaminetetraacetate, and 0.05 g of sodium borohydride. The rest is the same as Example 15.

[0141] Performance test

[0142] (I) Characterization

[0143] The M / h-BNNS catalysts prepared in the above examples were characterized by the following means.

[0144] 1) X-ray diffraction pattern (XRD), as shown in Figure 1 .

[0145] Figure 1 From top to bottom are the XRD of M / h-BNNS catalysts obtained in Examples 6-15, respectively. The patterns of the catalysts after introducing different active metal centers are given in the figure, and the diffraction peaks of the h-BNNS carrier can be observed, which are consistent with the standard card diffraction peaks; no diffraction peak of active metal is observed, indicating that the active component is highly dispersed.

[0146] 2) The elemental composition table of the catalyst in Example 6-21 is shown in Table 2.

[0147] Table 2 is the inductively coupled plasma spectroscopy data (ICP) of the M / h-BNNS catalyst obtained in Example 6-21, which was analyzed by inductively coupled plasma emission spectrometer (Thermo Fischer, ICAP-6300). The types and contents of trace metal elements in the catalyst were determined, and the results showed that the theoretical value was consistent with the actual value. The amount of active metal M salt / molecular weight of active metal M salt x molecular weight of active metal M = mass of active metal M, mass of active metal M / (mass of active metal M + mass of h-BN powder) = M (wt%).

[0148] Take Example 10 as an example: 0.05 (mass of ruthenium chloride) / 261.47 (molecular weight of ruthenium chloride) x 101 (molecular weight of Ru) ≈ 0.019 (mass of Ru); 0.019 / (0.019+ 2.5) ≈ 0.8wt%.

[0149] Table 2 Elemental composition table of catalyst in Example 6-21

[0150]

[0151] (II) Catalytic activity

[0152] The performance evaluation of the catalyst prepared in the above examples was carried out on a constant bed reaction device at normal pressure. Before the activity test, the catalyst M / h-BNNS (40-60 mesh, 200 mg) was pre-reduced and activated in a 10% H2 / N2 atmosphere, and the reduction temperature was 600°C, and the reduction time was 2 h.

[0153] After reduction, N2 (50 mL / min) was used as carrier gas to send into the reactor at normal pressure, and a mixed solution of ethanol and water (molar ratio n H2O : n EtOH =3:1) was injected by using a syringe pump, evaporated into steam in the vaporization chamber, and mixed with N2. The test temperature interval was 400-600℃, with a temperature interval of 50℃. The reaction products were analyzed by using a gas chromatograph (INFICON, PN074-594-P1D, USA). The test results are shown in Table 3.

[0154] Table 3 Activity evaluation of catalysts prepared in Examples 6-21 at different temperatures

[0155]

[0156] As can be seen from Table 3, with the increase of temperature, the conversion rate of ethanol and the yield of H2 gradually increased. At 500-600℃, the conversion rate of ethanol in the catalytic steam reforming reaction of ethanol and water was 65-100%, the yield of H2 was 55-100%, and the catalysts had high catalytic activity. The preferred catalyst of Example 6-14 was Example 10. The preferred catalyst of Examples 15-21 was Example 15, and Example 15 had a better effect than Example 10.

[0157] (III) Catalyst stability

[0158] Taking the catalysts prepared in Examples 10 and 15 as examples, the stability of the catalysts was tested: the activity evaluation of the catalysts prepared in the above examples was carried out on a normal pressure fixed bed reaction device. Before the activity test, the catalyst Ru / h-BNNS (40-60 mesh, 200 mg) was first activated and reduced at 600℃ for 2 h in a 10% H2 / N2 atmosphere.

[0159] After reduction, N2 (50 mL / min) was used as carrier gas to send into the reactor at normal pressure, and the temperature was reduced to 550℃, a mixed solution of ethanol and water (molar ratio n H2O : n EtOH =3:1) was injected by using a syringe pump, evaporated into steam in the vaporization chamber, and mixed with N2. The reaction products were analyzed by using a gas chromatograph (INFICON, PN074-594-P1D, USA). The test results are shown in Table 3. Figure 2

[0160] As can be seen from Figure 2 A, when the test temperature was 550℃, Example 10 maintained good catalytic activity in the long-term stability experiment. Within 40 h of reaction, the catalyst exhibited excellent ethanol conversion rate and H2 yield (close to 100%), and the stability was more than 40 hours. As can be seen from Figure 2 ​As shown in Figure 1, at a test temperature of 550°C, Example 15 maintained good catalytic activity during the long-term stability experiment. Within 40 hours of reaction, the catalyst also exhibited excellent ethanol conversion and H2 yield (nearly 100%), with stability exceeding 40 hours.

[0161] In addition, the catalysts prepared in Example 10 and Example 15 after stability test were subjected to thermogravimetric-differential thermal analysis (TG-DSC). The results are as follows: Figure 3 As shown. Figure 3 A shows that the catalyst prepared in Example 10 has less carbon deposition and a mass loss of only 3.4%, which indicates that the catalyst prepared in Example 10 of the present invention has good carbon deposition resistance. The interaction between the defect-rich h-BNNS and the highly dispersed active metal is conducive to the rapid vaporization of the carbon deposition precursor, thereby improving the stability of the catalyst. The catalyst prepared in Example 15 ( Figure 3 B) The amount of carbon deposits is less, and the mass loss is only 1.7%, which is better than the catalyst prepared in Example 10. This shows that the catalyst prepared in Example 15 of the present invention has the best carbon deposition resistance. This is because in the surface functionalized precursor preparation step, the addition of sodium dodecylbenzenesulfonate, polyvinylpyrrolidone and nano-alumina can synergistically promote the generation and uniform distribution of h-BN surface defects and improve the quality of the precursor. In the step of introducing active metal centers, the addition of ascorbic acid, disodium ethylenediaminetetraacetic acid and sodium borohydride helps to reduce and uniformly disperse metal ions and enhance the interaction between metal and support. The optimized addition amount of each component, drying and calcination conditions further improve the performance of the catalyst. Overall, the preparation method of Example 15 can enable the catalyst to exhibit higher activity, stability and carbon deposition resistance in the bioethanol reforming hydrogen production reaction, effectively improving the hydrogen yield.

[0162] (IV) Summary

[0163] The reason why Example 15 is better than Example 10 and Examples 16-21 is:

[0164] Compared with Example 10

[0165] Advantages of surface functionalization aids: Example 15 precisely optimizes the amount of surface functionalization aids. The sufficient addition of sodium dodecyl benzene sulfonate sufficiently reduces the surface tension of the solution, significantly enhances the cavitation effect during ultrasonic treatment, and can more fully destroy the original structure of h-BN than Example 10, generating a large number of and uniformly distributed defects, providing more abundant and ideal sites for active metal loading. The appropriate amount of polyvinylpyrrolidone effectively inhibits the aggregation of h-BN layers, ensuring the high dispersion of active metals on the surface of the carrier. Compared to the structure formed in Example 10 without the interference of such aids, Example 15 can more stably and uniformly disperse active metals. The appropriate amount of nano-alumina greatly promotes the uniform distribution of h-BN surface defects, further improving the quality and uniformity of active metal loading, while Example 10 lacks the synergistic effect of these aids.

[0166] Advantages of additive synergies: In Example 15, the amounts of reducing agents (ascorbic acid and sodium borohydride) and complexing agents (disodium ethylenediaminetetraacetate) are carefully adjusted to synergize with surface functionalization aids. In the case of good active metal loading, the reducing agent can fully reduce metal ions and uniformly distribute the reduced metal atoms on the surface of h-BN, and the complexing agent effectively controls the release rate of metal ions, avoids aggregation, and enhances the interaction between metal and carrier. Example 10, without these additive synergies, is not as perfect as Example 15 in terms of active metal loading and dispersion.

[0167] Advantages of each step synergy: In Example 15, from ball milling, ultrasonic treatment, to mechanical ball milling to introduce active metal centers, drying, calcination, etc., due to the appropriate amount of additives, a more stable and efficient system is formed. The high-quality defect structure produced by ball milling and ultrasonic treatment, combined with the appropriate action of additives, allows the subsequent active metal loading, reduction, and dispersion process to proceed efficiently, the active metal and the carrier are more closely combined, and the active center formed is more stable. In contrast, although Example 10 has some synergy in each step, it lacks the additive optimization addition effect, and the overall synergy is inferior to Example 15.

[0168] Compared with Examples 16-21

[0169] Compared with Example 16: Example 16 lacks sufficient active metal, resulting in a lack of active sites. Even with the addition of surface functionalization aids, reducing agents, and complexing agents, it cannot make up for the serious impact of insufficient active metal on catalytic activity. Example 15 optimizes the amount of active metal and the amount of each additive, ensuring sufficient and high-quality active sites, and the catalytic activity is much higher than Example 16.

[0170] Compared with Example 17: increasing the amount of active metal should increase activity, but the problem of metal agglomeration is serious. As the amount of active metal increases, the distance between metal atoms decreases, and the interatomic interaction force increases, making it easier for metal atoms to come together to form agglomerates. The effective active surface area of the agglomerated metal particles is greatly reduced, many metal atoms cannot participate in the reaction, and the metal-support interaction is weakened, resulting in limited improvement in catalytic activity, far less than the case where the active metal is uniformly dispersed and stably loaded in Example 15.

[0171] Compared with Example 18:

[0172] Surface functionalization agent dosage problem: The dosage of surface functionalization agent in Example 18 is reduced, and sodium dodecylbenzenesulfonate cannot fully enhance the ultrasonic cavitation effect, the h-BN structure is not fully destroyed, the number of defects produced is small and unevenly distributed, and there are not enough active metal attachment sites. The ability of polyvinylpyrrolidone to inhibit h-BN sheet layer agglomeration decreases, and the active metal dispersion is poor. The function of nano-alumina to promote uniform distribution of defects is weakened, and the active metal is not uniformly loaded. While the dosage of surface functionalization agent in Example 15 is appropriate, it can fully play the role of the agent in promoting the modification of h-BN structure and the loading of active metal, and the loading and dispersion of active metal are much better than in Example 18.

[0173] Additive interaction problem: In Example 18, the lack of surface functionalization agent between additives leads to poor loading of active metal, and the reducing agent and complexing agent cannot function properly. Ascorbic acid and sodium borohydride cannot evenly distribute the reduced metal atoms on the surface of h-BN, and disodium ethylenediaminetetraacetate cannot effectively control the release speed of metal ions and prevent agglomeration. In Example 15, the additives work together to ensure the effective loading and dispersion of active metal, and the catalytic activity is much higher than in Example 18.

[0174] Step-by-step synergy problem: In Example 18, the lack of surface functionalization agent disrupts the synergy of the entire preparation process, making it difficult to effectively proceed with the subsequent reduction and dispersion processes. In Example 15, the steps work together well, forming a highly efficient and stable system from ball milling, ultrasonication, active metal loading, and subsequent processing, resulting in better catalyst performance.

[0175] Compared with Example 19: The excessive amount of additives in Example 19 has many negative effects, such as sodium dodecylbenzenesulfonate causing excessive foam that affects the transmission of ultrasonic energy, polyvinylpyrrolidone forming a too-thick coating layer that hinders the combination of active metal and h-BN NS, and nano-alumina making the system too viscous to facilitate uniform loading of active metal. The precise dosage of additives in Example 15 avoids these negative problems, resulting in better catalytic activity and stability.

[0176] Compared with Example 20:

[0177] Interference of introduced substances: The reduced amount of reducing agent and complexing agent in Example 20 not only fails to achieve the desired effect, but also changes the chemical environment around the active metal center, introduces impurities or initiates side reactions, affects the nature of the active site, and leads to reduced activity. The amount of reducing agent and complexing agent in Example 15 is appropriate, and there is no such interference, and the active metal can play a more pure role.

[0178] Difference in ball milling effect: In Example 20, the reducing agent and complexing agent interact with the active metal and the carrier during ball milling, dispersing the ball milling energy, affecting the introduction and dispersion of the active metal center, and making the particles more prone to agglomeration, reducing the specific surface area of the active metal, and reducing the dispersion of the active metal. The ball milling process in Example 15 is not subject to such interference, and is more conducive to concentrating energy on forming suitable defects and active centers, and the dispersion of the active metal after ball milling is better.

[0179] Lack of synergy: In Example 20, the small amount of reducing agent and complexing agent destroys the synergy between the active metal and the carrier, changes the reaction path, and may have a higher reaction energy barrier or more complex intermediate process. In Example 15, the active metal and the carrier form a good matching relationship through specific ball milling conditions and appropriate amounts of additives, and the reaction path is more direct and efficient.

[0180] Compared with Example 21: In Example 21, the reducing agent and complexing agent are excessive, and ascorbic acid and sodium borohydride make the reduction reaction too violent, the metal particles grow out of control, the dispersion is poor, and the strong complex formed by disodium ethylenediaminetetraacetate and metal ions hinders the effective loading and reduction of metal ions on the surface of h-BNNS. In Example 15, the amount of reducing agent and complexing agent is appropriate, the reduction reaction is controllable, and the loading and dispersion of metal ions are good, with much higher catalytic activity and stability than Example 21.

[0181] Comparison of Examples 16-21 with Example 10:

[0182] Comparison of Example 16 with Example 10

[0183] Effect of active metal amount: In Example 16, the amount of active metal is insufficient, and the active site is lacking, limiting the chemical reaction rate. Although Example 10 does not use surface functionalization aids, reducing agents, and complexing agents, it produces defects in h-BN through specific ball milling and ultrasonic treatment, and loads active metal, which is superior to Example 16 in terms of the number of active sites and has higher catalytic activity.

[0184] Stability effect: In Example 16, the amount of active metal is small, and the active site is easily damaged by carbon deposition and other factors, resulting in poor stability. Example 10 is relatively better in terms of stability, as the distribution of active metal and the structure of the carrier are relatively stable under its preparation process, and can maintain good performance in long-term reactions.

[0185] Comparison of Example 17 with Example 10

[0186] Metal aggregation: Example 17 has serious metal aggregation, the effective active surface area is reduced, and the promotion of catalytic activity is limited. Example 10 avoids the problem of metal aggregation, and the active metal can effectively participate in the reaction, and the catalytic activity is higher.

[0187] Stability impact: Metal aggregation destroys the structural stability of the catalyst in Example 17. The structural stability of Example 10 is relatively good, and the performance is more stable in long-term reaction.

[0188] Example 18 compared with Example 10

[0189] Effect of surface functionalization agent dosage:

[0190] Sodium dodecyl benzene sulfonate: In Example 18, the dosage of sodium dodecyl benzene sulfonate is insufficient, which reduces the ability to reduce the surface tension of the solution and enhance the ultrasonic cavitation effect, and cannot fully destroy the h-BN structure to produce abundant and uniform defects. Although Example 10 does not have this additive, the ball milling and ultrasonic treatment parameters may be optimized to form a defect structure that is more conducive to active metal loading.

[0191] Polyvinylpyrrolidone: In Example 18, the dosage of polyvinylpyrrolidone is reduced, and the ability to inhibit h-BN sheet aggregation is significantly reduced. h-BN sheets are more likely to aggregate, making it difficult for active metals to be uniformly dispersed on the surface of the carrier during subsequent loading, and the active sites are unevenly distributed. In the absence of this additive, Example 10 may form a structure that is more conducive to the natural dispersion of active metals in the appropriate location through ball milling and ultrasonic treatment.

[0192] Nano-alumina: In Example 18, the dosage of nano-alumina is reduced, and its function of promoting uniform distribution of h-BN surface defects is also weakened, resulting in an undesirable distribution of h-BN surface defects, making it difficult for active metals to be uniformly loaded on the surface of the carrier. Although Example 10 does not have this additive, the defect structure formed by the overall process performs better in terms of active metal loading.

[0193] Effect of synergy of each step: The ball milling and ultrasonic treatment of Example 10 cooperate with subsequent steps to form a relatively stable and efficient system, and the active metal can be well combined with the carrier to form a stable active center. Example 18 has insufficient dosage of surface functionalization agent, which affects the loading effect of active metals and disrupts the synergy of the entire preparation process, making the subsequent reduction and dispersion process ineffective, and the catalyst performance is not as good as Example 10.

[0194] Effect of additive interaction: The poor active metal loading in Example 18 due to the surface functionalization aid between the additives makes it difficult for the reducing agent and complexing agent to function properly. The ascorbic acid and sodium borohydride cannot evenly distribute the reduced metal atoms on the h-BN surface, and the disodium ethylenediaminetetraacetate cannot effectively control the metal ion release rate and prevent agglomeration. Example 10, without these additive interactions, achieves a good balance in active metal loading and dispersion.

[0195] Example 19 compared to Example 10

[0196] Negative effect of excess aid: The excess aid in Example 19 has a negative effect, such as sodium dodecylbenzenesulfonate causing excessive foam affecting the transmission of ultrasonic energy, polyvinylpyrrolidone forming a too thick coating layer hindering the active metal from combining with the h-BN NS, and nano-alumina making the system too viscous to facilitate uniform loading of active metal, which severely affects the catalyst activity. Example 10 does not use these aids and forms a stable active metal-support structure through its own preparation process, resulting in higher catalytic activity.

[0197] Stability effect: The excess aid in Example 19 affects the catalyst structure and performance, and the structure is unstable over a long reaction time, which is less stable than Example 10.

[0198] Example 20 compared to Example 10

[0199] Interference of introduced substances:

[0200] In terms of active site properties: The small amount of reducing agent and complexing agent in Example 20 can change the chemical environment around the active metal center, causing changes in the electronic cloud distribution, acidity and other properties of the active site that are not conducive to the reaction, resulting in reduced activity. Example 10 does not have these substances, and there is no such interference, so the active metal can function more purely.

[0201] Impurities or side reactions: Even a small amount of reducing agent and complexing agent in Example 20 can introduce impurities or trigger some side reactions in the reaction system, consuming part of the active metal or changing the form in which the active metal exists, affecting the overall effect. Example 10 does not have such problems.

[0202] Difference in ball milling effect:

[0203] Energy input and active center formation: In Example 20, due to the presence of reducing agent and complexing agent, they interact with active metal and support during ball milling, dispersing the ball milling energy, which makes it difficult for the active metal center to be effectively introduced and dispersed through simple ball milling as in Example 10. The simple ball milling process in Example 10 is more conducive to concentrating energy on forming suitable defects and active centers.

[0204] Particle agglomeration: The reducing agent and complexing agent in Example 20 can affect the particle surface properties during ball milling, making the particles more prone to agglomeration, reducing the active specific surface area, and lowering the active metal dispersion, which in turn affects the activity. Example 10 does not have these substances interfering, and the active metal dispersion after ball milling can be better.

[0205] Lack of synergy: Example 10 forms a unique interaction and matching relationship between the active metal and the carrier through specific ball milling conditions, which is conducive to the active metal to exert its catalytic function. The small amount of reducing agent and complexing agent in Example 20 disrupts this originally possible good match, leading to a weakening of the synergy between the active metal and the carrier, and the effect is not as good as Example 10. At the same time, the reducing agent and complexing agent change the reaction path, and in the case of small amounts, the new reaction path can have a higher reaction energy barrier or more complex intermediate process, which is not conducive to the reaction, while the reaction path of Example 10 is more direct and efficient.

[0206] Example 21 compared with Example 10

[0207] Negative effects of excess reducing agent and complexing agent: In Example 21, the reducing agent and complexing agent are excessive, ascorbic acid and sodium borohydride make the reduction reaction too violent, the metal particles grow out of control, the dispersion becomes poor, and the ethylenediaminetetraacetic acid disodium salt forms a too strong complex with metal ions, hindering the effective loading and reduction of metal ions on the h-BNNS surface, which seriously damages the catalytic activity. Example 10 does not use these aids, and through its own preparation process, it forms a stable and efficient active metal-carrier structure, with higher catalytic activity.

[0208] Stability impact: Excess reducing agent and complexing agent destroy the catalyst structure in Example 21, and the stability decreases significantly, which is not as good as Example 10.

[0209] Comparison between Examples 16-21;

[0210] Active metal dosage factor

[0211] Comparison between Example 16 and Example 17: Example 16 reduces the amount of active metal, and the lack of active sites limits the catalytic activity; Example 17 increases the amount of active metal, but the metal agglomeration limits the improvement of activity. Comparing the two can clearly show that the amount of active metal has a significant impact on the performance of the catalyst, and too little or too much is not conducive to improving the catalytic activity, providing a reference for determining the appropriate amount of active metal. Through comparison, it can be seen that there is an optimal range for the amount of active metal, within which both sufficient active sites can be ensured and problems such as metal agglomeration can be avoided, thereby achieving higher catalytic activity.

[0212] Surface functionalization aid dosage factor

[0213] Example 18 vs. Example 19: The amount of surface functionalization assistant in Example 18 is reduced, which cannot fully play the role of promoting the structural modification of h-BN and the loading of active metal; the amount of surface functionalization assistant in Example 19 is too much, which has a negative effect. The comparison shows that the amount of surface functionalization assistant needs to be accurately controlled, and improper amount will seriously affect the performance of the catalyst. This provides a basis for optimizing the amount of the assistant. This shows that the amount of surface functionalization assistant has an important influence on the performance of the catalyst. The appropriate amount can promote the loading and dispersion of active metal and improve the activity of the catalyst. Too little or too much will destroy this synergy and reduce the performance of the catalyst.

[0214] Amount of reducing agent and complexing agent

[0215] Example 20 vs. Example 21: The amount of reducing agent and complexing agent in Example 20 is reduced, which cannot fully reduce and disperse the metal ions; the amount of these components in Example 21 is too much, which makes it difficult to control the reduction reaction. The comparison between the two can clearly see that the amount of reducing agent and complexing agent has a significant influence on the state of metal ions and the performance of the catalyst, which provides a direction for determining the appropriate amount. It shows that the amount of reducing agent and complexing agent needs to be accurately controlled. Too little cannot guarantee the full reduction and dispersion of metal ions, and too much will lead to an out-of-control reaction. Only the appropriate amount can ensure that the catalyst has good performance.

[0216] Comprehensive performance consideration

[0217] Different factor combinations affect: By comparing Examples 16-21, it can be found that various factors such as the amount of active metal, the amount of surface functionalization assistant, the amount of reducing agent and complexing agent, etc. affect the performance of the catalyst. Through comprehensive comparison, the role of each factor in the preparation of the catalyst and the mutual relationship can be understood in depth, which provides a comprehensive reference for optimizing the catalyst formula and preparation process, and helps to develop a catalyst with better performance. For example, through comparison, it can be found that when the amount of active metal is appropriate, and the amounts of surface functionalization assistant, reducing agent and complexing agent are also coordinated, the catalyst can achieve a good balance in activity, stability and cost-effectiveness, etc., thereby providing a more valuable reference for practical application.

[0218] Although the embodiments of the present application have been disclosed as above, they are not limited to the application listed in the specification and embodiments, and can be fully applied to various fields suitable for the present application. Those skilled in the art can easily make other modifications, and therefore the present application is not limited to specific details and examples shown and described herein without departing from the general concept defined by the claims and equivalent scope.

Claims

1. A method for preparing a bioethanol reforming hydrogen production catalyst, characterized in that: The following steps are involved: S1. Preparation of surface functionalized precursors: 2.0-3.0g of h-BN powder was ball-milled in a planetary ball mill at 400-600rpm for 2-4h. 50mL of ethanol solution was added with 0.04-0.06g of sodium dodecylbenzenesulfonate, 0.03-0.07g of polyvinylpyrrolidone, and 0.02-0.06g of nano-alumina. After stirring to fully dissolve the sodium dodecylbenzenesulfonate and polyvinylpyrrolidone and uniformly disperse the nano-Al2O3 in the solution, the ball-milled h-BN powder was added and ultrasonicated for 10-60min to obtain the defect-rich precursor h-BNNS. S2. Mechanical ball milling method to introduce active metal centers: Weigh 0.01-0.06g of active metal M salt and dissolve it in 20-30mL of deionized water. Then add 0.02-0.04g of ascorbic acid, 0.01-0.03g of disodium ethylenediaminetetraacetic acid, and 0.02-0.05g of sodium borohydride. After stirring evenly, add the defect-rich precursor h-BNNS. Then, ball mill at 600-800rpm in a planetary ball mill for 10-16h. After ball milling, collect the sample; S3, drying process: The obtained sample was dried at 40-100°C for 6-12h; S4, calcination treatment: The dried sample was calcined in a H2 atmosphere, the temperature was raised to 400-700°C at a heating rate of 2-10°C / min, and maintained for 2-10 hours to obtain the bioethanol reforming hydrogen production catalyst M / h-BNNS.

2. The method for preparing a bioethanol reforming hydrogen production catalyst according to claim 1, wherein: The solution in S1 is one or more of water, ethanol, and ethylene glycol.

3. The method for preparing a bioethanol reforming hydrogen production catalyst according to claim 1, wherein: The active metal M salt in S2 is one of Pd salt, Pt salt, Ru salt, Rh salt, Ir salt, Co salt or Ni salt.

4. The method for preparing a bioethanol reforming hydrogen production catalyst according to claim 1, wherein: The mass of the active metal M in S2 is 0.2-1 wt% of the total mass of the active metal M and the defect-rich precursor h-BNNS.

5. The method for preparing a bioethanol reforming hydrogen production catalyst according to claim 1, wherein: In S4, the temperature is raised to 400-700°C at a heating rate of 2-10°C / min, and the calcination time is 2-10 h.

6. The method for preparing a bioethanol reforming hydrogen production catalyst according to claim 1, wherein: S1. Preparation of surface functionalized precursors: 2.5g of h-BN powder was ball-milled at 500rpm in a planetary ball mill for 3h. 50mL of ethanol solution was added with 0.05g of sodium dodecylbenzenesulfonate, 0.05g of polyvinylpyrrolidone, and 0.04g of nano-alumina. After stirring to fully dissolve the sodium dodecylbenzenesulfonate and polyvinylpyrrolidone and uniformly disperse the nano-Al2O3 in the solution, the ball-milled h-BN powder was added and ultrasonicated for 1h to obtain the defect-rich precursor h-BNNS. S2. Mechanical ball milling method to introduce active metal centers: Weigh 0.05 g of active metal M salt and dissolve it in 25 mL of deionized water. Then add 0.03 g of ascorbic acid, 0.02 g of disodium ethylenediaminetetraacetic acid, and 0.03 g of sodium borohydride. After stirring evenly, add the defect-rich precursor h-BNNS. Then, ball mill at 700 rpm in a planetary ball mill for 13 hours. After ball milling, collect the sample.

7. A bioethanol reforming hydrogen production catalyst, characterized in that: It is prepared by the preparation method according to any one of claims 1 to 6.

8. Use of the bioethanol reforming hydrogen production catalyst according to claim 7 in catalytic ethanol steam reforming, characterized in that: The application method is as follows: The catalyst is loaded into a fixed bed reactor, and after pre-reduction treatment, ethanol vapor and carrier gas are introduced to carry out the reaction.

9. Use of the bioethanol reforming hydrogen production catalyst according to claim 8 in catalytic ethanol steam reforming, characterized in that: The pre-reduction treatment conditions are: reduction temperature of 400-600° C., reduction atmosphere composed of H 2 and N 2 , and reduction time of 1-2 h.

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