A copper-carbon composite catalyst, its preparation method, and its application in methanol liquid-phase reforming for hydrogen production.

Abstract

This application discloses a copper-carbon composite catalyst, its preparation method, and its application in methanol liquid-phase reforming for hydrogen production. The preparation method of the copper-carbon composite catalyst includes the following steps: S1, dissolving an acidic organic ligand, a basic substance, and a copper salt in a solvent and mixing them evenly to form a mixed solution, thereby generating a copper metal-organic framework crystal precipitate through a coordination reaction; S2, grinding the copper metal-organic framework crystal precipitate evenly and then calcining it at high temperature under an inert gas atmosphere to generate the copper-carbon composite catalyst.

Description

Technical Field

[0001] This application belongs to the technical field of catalysts, specifically relating to a copper-carbon composite catalyst, its preparation method, and its application in methanol liquid-phase reforming for hydrogen production. Background Technology

[0002] Hydrogen is a clean and efficient energy carrier. It reacts with oxygen to produce only water, with no pollutant emissions. Its mass energy density is three times that of gasoline. Its applications are wide-ranging, covering industry, transportation, and power generation, making it a crucial energy source for achieving carbon neutrality. However, hydrogen's low density and flammability / explosiveness make its transportation a challenge. Methanol reforming for hydrogen production is one of the core technologies in the hydrogen energy industry chain. It enables on-site hydrogen production, directly connecting the "production end" and "application end" of hydrogen energy, and can meet the needs of high-end applications such as vehicle fuel cells. my country's methanol production industry chain is mature. Using methanol as a raw material for hydrogen production not only ensures a stable and reliable source but also solves industry pain points such as difficulties in hydrogen storage and transportation and insufficient pure hydrogen refueling facilities. Methanol reforming for hydrogen production includes methanol steam reforming (MSR) and methanol liquid phase reforming (APRM). Among them, methanol liquid phase reforming (APRM) has advantages such as mild reaction conditions, rapid start-up, and high H2 selectivity, while the catalyst is a key factor affecting the hydrogen production efficiency of APRM.

[0003] Among common catalysts, noble metal-based catalysts, represented by Pt, possess excellent properties such as high activity, high H2 selectivity, and high stability. However, their stringent manufacturing processes and high prices limit their large-scale industrial application. In contrast, non-noble metal-based catalysts, Cu-based catalysts offer advantages such as low cost and high activity at low temperatures. Cu-based catalysts can also be adapted to different water-to-alcohol ratios, balancing efficiency and cost. Commercially available Cu / Zn / Al ternary catalysts exhibit high catalytic activity only at reaction temperatures above 300℃. However, at this temperature, Cu is prone to sintering and agglomeration, leading to a shortened catalyst lifespan, making its industrial application in APRM technology difficult. To lower the reaction temperature, Chinese patent CN119425690A involves mixing and reacting copper salts, acidic organic ligands, and chelating agents, followed by crystallization to form CuMOF crystals, and then high-temperature calcination and carbonization to form MOF-derived copper-based catalysts. This technology disperses copper particles on a carbon material with a large specific surface area and high porosity, lowering the reaction temperature of the methanol liquid-phase reforming hydrogen production reaction to around 220°C, thus avoiding the problem of Cu sintering and agglomeration at high temperatures of 300°C. However, this technology has a long processing time, with slow CuMOF crystal nucleation and growth (typically over 40 hours at room temperature and over 10 hours under heating conditions). Furthermore, its hydrogen production efficiency in methanol liquid-phase reforming hydrogen production applications at a reaction temperature of around 220°C still needs improvement.

[0004] In view of this, this application provides a copper-carbon composite catalyst, a preparation method, and its application in methanol liquid-phase reforming for hydrogen production. The CuMOF crystals form quickly without the need for an additional crystallization process. The copper-carbon composite catalyst has a high copper loading and strong catalytic activity, thereby significantly improving the hydrogen production efficiency of the copper-carbon composite catalyst in methanol liquid-phase reforming for hydrogen production. Summary of the Invention

[0005] The purpose of this application is to provide a copper-carbon composite catalyst, its preparation method, and its application in methanol liquid-phase reforming for hydrogen production. The CuMOF crystals form quickly without the need for an additional crystallization process. The copper-carbon composite catalyst has a high copper loading and strong catalytic activity, thereby significantly improving the hydrogen production efficiency of the copper-carbon composite catalyst in methanol liquid-phase reforming for hydrogen production.

[0006] A first aspect of this application provides a method for preparing a copper-carbon composite catalyst, comprising the steps of: S1, acidic organic ligands, basic substances and copper salts are dissolved in a solvent and mixed evenly to form a mixed solution, and a coordination reaction is performed to generate copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate). S2, the above copper metal-organic framework crystals are precipitated and ground evenly, and then carbonized by high-temperature calcination under an inert gas atmosphere to generate a copper-carbon composite catalyst.

[0007] In some embodiments, in step S1, the acidic organic ligand comprises a benzene ring and an active group; the benzene ring is not easily broken during carbonization to form a carbon skeleton, and the active group participates in the coordination reaction.

[0008] Furthermore, the acidic organic ligand includes at least one of terephthalic acid, isophthalic acid, phthalic acid, or aminoterephthalic acid.

[0009] In some embodiments, the alkaline substance is an inorganic substance that is readily soluble in water and has a pKb ≤ 4.

[0010] Furthermore, the alkaline substance includes at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, or potassium carbonate.

[0011] In some embodiments, the concentration of the acidic organic ligand in the mixture is 0.1-0.5 mol / L, and the molar ratio of the acidic organic ligand to the basic substance is 1:(0.8-3.5). Preferably, the concentration of the acidic organic ligand in the mixture is 0.25-0.45 mol / L, and the molar ratio of the acidic organic ligand to the basic substance is 1:(1-3).

[0012] In some embodiments, the copper salt comprises at least one of copper nitrate, copper acetate, copper citrate, or copper acetylacetonate. In some embodiments, the molar ratio of the acidic organic ligand to the copper salt in the mixture is 1:(0.5-2). Preferably, the molar ratio of the acidic organic ligand to the copper salt in the mixture is 1:(0.8-1.3).

[0013] In some embodiments, the solvent is deionized water.

[0014] In some embodiments, an acidic organic ligand and a basic substance are dissolved in a solvent, a copper salt is dissolved in the solvent, and the two are then mixed evenly to form a mixture.

[0015] In some embodiments, the coordination reaction takes 0.2-4 hours. Preferably, the coordination reaction takes 0.5-3 hours.

[0016] In some embodiments, after the coordination reaction, the copper-organic framework crystal precipitate (Cu-MOF crystal precipitate) is obtained by centrifugation, washing and drying.

[0017] In some embodiments, during step S2, the carbonization process involves first introducing an inert gas into a high-temperature tube furnace at a flow rate of 50-150 mL / min for 5-30 minutes, then starting heating and adjusting the inert gas flow rate to 20-50 mL / min until the reaction is complete. Preferably, during the carbonization process, an inert gas is first introduced into a high-temperature tube furnace at a flow rate of 80-120 mL / min for 8-15 minutes, then starting heating and adjusting the inert gas flow rate to 25-40 mL / min until the reaction is complete.

[0018] In some embodiments, the copper-carbon composite catalyst has copper particles uniformly dispersed on a carbon support, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary valence state.

[0019] Furthermore, the copper-carbon composite catalyst has a size of 5-20 μm, and the copper particles have a size of 5-30 nm.

[0020] Furthermore, the inert gas includes at least one of nitrogen, helium, neon, argon, krypton, or xenon.

[0021] Furthermore, the high-temperature calcination carbonization treatment is carried out at a temperature of 400-900℃, a calcination time of 1-10h, and a heating rate of 2-8℃ / min. Preferably, the high-temperature calcination carbonization treatment is carried out at a temperature of 600-800℃, a calcination time of 1-5h, and a heating rate of 3-6℃ / min.

[0022] Furthermore, the aforementioned copper metal-organic framework crystals are precipitated and ground uniformly, and then placed in a high-temperature calcination apparatus for high-temperature carbonization treatment under an inert gas atmosphere. The high-temperature calcination apparatus includes: a high-temperature tube furnace, a crucible, a muffle furnace, etc.

[0023] A second aspect of this application provides a copper-carbon composite catalyst obtained by the above-described preparation method.

[0024] In some embodiments, the copper-carbon composite catalyst comprises copper particles and a carbon support, wherein the copper particles are uniformly dispersed on the carbon support, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary valence state.

[0025] Furthermore, the copper-carbon composite catalyst has a size of 5-20 μm, and the copper particles have a size of 5-30 nm.

[0026] In a third aspect of this application, the aforementioned copper-carbon composite catalyst is added to the methanol liquid-phase reforming hydrogen production reaction.

[0027] In some embodiments, a copper-carbon composite catalyst and an aqueous methanol solution are mixed and reacted at 180-220°C under an inert gas atmosphere. After cooling, the gaseous product (hydrogen) is collected.

[0028] The copper-carbon composite catalyst, its preparation method, and its application in methanol liquid-phase reforming for hydrogen production disclosed in this application have at least the following advantages compared with existing technologies: Firstly, in the coordination reaction of this application, an alkaline substance is used to neutralize the acidic / active groups on the acidic organic ligand, causing it to undergo a deprotonation reaction and transform into its anion, which can react with Cu. 2+ CuMOF crystals precipitate immediately after the solution is mixed (rapidly and directly forming crystals within approximately 0.2-2 hours), and the reaction is very thorough, requiring no additional crystallization process. This significantly shortens the process time, simplifies the process flow, and improves the controllability of the coordination reaction.

[0029] Secondly, in the coordination reaction of this application, the acidic organic ligand is deprotonated and converted into its anion, which is completely soluble in water, greatly increasing the amount of acidic organic ligand participating in the coordination reaction. After carbonization treatment, the loading of copper element on the carbon skeleton per unit area is increased (by about 80% by mass), thereby improving the catalytic performance of the copper-carbon composite catalyst under the same addition amount.

[0030] Thirdly, during the carbonization process, by controlling the operation of the inert gas, the copper element in the copper particles of the copper-carbon composite catalyst is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary oxidation state in methanol liquid-phase reforming for hydrogen production Cu + It forms a synergistic catalytic effect with Cu, enhancing catalytic activity and thus significantly promoting hydrogen production.

[0031] Fourthly, the copper-carbon composite catalyst of this application has a high loading of copper particles, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + The binary valence state of Cu results in high catalytic activity. Together, these two components significantly improve the hydrogen production efficiency of this copper-carbon composite catalyst in methanol liquid-phase reforming hydrogen production applications.

[0032] Fifthly, the acidic organic ligands include benzene rings and active groups, while the basic substances are readily soluble in water with pKb≤4. By controlling the molar ratio of the two, the deprotonation reaction is made rapid and complete, without any other adverse effects. Attached Figure Description

[0033] Combined with the following appendix Figure 1 The above and other features of this application will be more fully described when the drawings are read. It is understood that these drawings only depict a few embodiments of the application and should not be considered as limiting the scope of the application. The application will be explained more clearly and in more detail through the use of the drawings.

[0034] Figure 1 This is a scanning electron microscope (SEM) image of the Cu-MOF crystal precipitate of Example 1 of this application.

[0035] Figure 2 This is a SEM image of the copper-carbon composite catalyst of Example 1 of this application.

[0036] Figure 3 This is a transmission electron microscope (TEM) image of the copper-carbon composite catalyst of Example 1 of this application.

[0037] Figure 4This is an X-ray powder diffraction (XRD) pattern of the Cu-MOF crystal precipitate of Example 1 of this application.

[0038] Figure 5 The image shows the XRD pattern of the copper-carbon composite catalyst of Example 1 of this application.

[0039] Figure 6 This is the Auger spectrum of copper in the copper-carbon composite catalyst of Example 1 of this application, obtained from X-ray photoelectron spectroscopy (XPS).

[0040] Figure 7 This is a graph showing the hydrogen production rate of Examples 1-7 and Comparative Examples 1-3 of this application. Detailed Implementation

[0041] The following embodiments are described to aid in understanding this application. These embodiments are not, and should not be, construed in any way as limiting the scope of protection of this application.

[0042] Unless otherwise defined, all terms (including technical and scientific terms) in this specification may be defined as commonly understood by one of ordinary skill in the art to which this disclosure pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having meanings consistent with their meanings in the context of this disclosure and the relevant field, and will be interpreted in a non-idealized or overly formal sense unless clearly defined herein.

[0043] As used herein, the term "at least one," when modifying the entire list of elements without modifying any individual elements of the list before or after it, shall not be construed as limiting "one." The terms "comprising" and "including," when used in this specification, indicate the presence of the stated features, regions, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, regions, wholes, steps, operations, elements, components, and / or collections thereof. Therefore, the above wording shall be understood to mean including the stated elements, but not excluding any other elements. The term "and / or" includes any and all combinations of one or more of the associated listed items. The term "multiple" refers to two or more. The term "connected" refers to a direct or indirect connection. The terms "first," "second," "third," etc., may be used herein to describe and distinguish different elements, components, regions, layers, and / or portions, but these elements, components, regions, layers, and / or portions should not be limited by these terms.

[0044] A first aspect of this application provides a method for preparing a copper-carbon composite catalyst, comprising the steps of: S1, acidic organic ligands, basic substances and copper salts are dissolved in a solvent and mixed evenly to form a mixed solution, and a coordination reaction is performed to generate copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate). S2, the above copper metal-organic framework crystals are precipitated and ground evenly, and then carbonized by high-temperature calcination under an inert gas atmosphere to generate a copper-carbon composite catalyst.

[0045] In existing Cu-MOF crystal formation techniques, chelating agents (such as polyvinylpyrrolidone, polyethers, hexadecyltrimethylammonium bromide, lauric acid, acetic acid, triethylamine, sodium formate, etc.) are added to an acidic organic ligand and an aqueous solution of copper salt to form a reaction mixture, thereby promoting the crystallization process of the MOF material. Although the chelating agent can participate in coordination as an auxiliary ligand, it forms stable complexes with metal ions (copper ions), inhibiting the direct coordination between the acidic organic ligand and copper ions. This results in a low rate of coordination reaction and slow crystal nucleation and growth (reaction time 10-60 hours). Furthermore, the resulting product has poor crystallinity, requiring additional, longer crystallization processes or harsh conditions such as high temperature and high pressure to improve crystallinity.

[0046] In step S1 of this application, an alkaline substance is used to neutralize the acidic / active groups (such as the carboxyl group of terephthalic acid) on the acidic organic ligand, causing it to undergo a deprotonation reaction and transform into its anion (such as terephthalate ion), which is completely soluble in water. Firstly, this greatly enhances the reaction between the acidic organic ligand and copper ions (Cu). 2+ The rate of coordination reactions of terephthalic acid with Cu. For example, terephthalic acid in the reaction with Cu 2+ During coordination, charge conservation must be satisfied, i.e., one Cu 2+ A copper metal-organic framework (CuMOF) material, containing two positive charges, needs to pair with a terephthalate anion containing two negative charges to form an electrically neutral copper metal-organic framework. However, upon the addition of a basic substance, terephthalic acid is converted into terephthalate anions, which can then react with Cu. 2+ Upon mixing, CuMOF crystals immediately precipitate (rapidly and directly forming crystals within approximately 0.2-2 hours), and the reaction is very thorough, requiring no additional crystallization process. Secondly, it increases the copper loading in the copper-carbon composite catalyst, thus enhancing its catalytic performance. For example, the terephthalate anion is significantly more polar than neutral terephthalic acid, completely soluble in water, and can fully participate in the coordination reaction with copper ions. This greatly increases the amount of acidic organic ligands involved in the coordination reaction. After carbonization, the copper loading per unit area of ​​the carbon skeleton is increased (by approximately 80% by mass), improving the catalytic performance of the copper-carbon composite catalyst at the same addition amount.

[0047] In some embodiments, in step S1, the acidic organic ligand comprises a benzene ring and an active group; the benzene ring is not easily broken during carbonization to form a carbon skeleton, and the active group participates in the coordination reaction.

[0048] Furthermore, the acidic organic ligand includes at least one of terephthalic acid, isophthalic acid, phthalic acid, or aminoterephthalic acid. In addition to these listed acidic organic ligands, other acidic organic ligands having a benzene ring and an active group are also within the scope of protection of this application.

[0049] In some embodiments, the alkaline substance is an inorganic substance that is readily soluble in water and has pKb ≤ 4 (pKb is the negative logarithm of the base dissociation constant), for example, pKb is 1, pKb is 1.5, pKb is 2, pKb is 2.5, pKb is 3, pKb is 3.5, or pKb is 4, but is not limited to the listed values. Other unlisted values ​​within the above range are also applicable.

[0050] Furthermore, the alkaline substance includes at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, or potassium carbonate. In addition to these listed alkaline substances, other inorganic alkaline substances that are readily soluble in water and have a pKb ≤ 4 are also within the scope of protection of this application.

[0051] The purpose of adding a basic substance in this application is to deprotonate the acidic organic ligand, converting it into a water-soluble anionic form. The applicant has discovered that not all basic inorganic substances are suitable for this application. For the acidic organic ligand used in this application, the basic substance must be readily soluble in water and have a pKb ≤ 4 to rapidly achieve deprotonation.

[0052] In some embodiments, the concentration of the acidic organic ligand in the mixture is 0.1-0.5 mol / L, such as 0.1 mol / L, 0.15 mol / L, 0.2 mol / L, 0.25 mol / L, 0.3 mol / L, 0.35 mol / L, 0.4 mol / L, 0.45 mol / L, or 0.5 mol / L, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. The molar ratio of the added acidic organic ligand to the basic substance is 1:(0.8-3.5), such as 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2, 1:2.2, 1:2.4, 1:2.6, 1:2.8, 1:3, 1:3.2, or 1:3.5, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. Preferably, in the mixture, the concentration of the acidic organic ligand is 0.25-0.45 mol / L, and the molar ratio of the acidic organic ligand to the alkaline substance is 1:(1-3).

[0053] The molar ratio of the acidic organic ligand to the basic substance in this application needs to be 1:(0.8-3.5). If the molar ratio is less than 1:0.8, for example, 1:0.4, too little basic substance is added, and the deprotonation of the acidic groups on the acidic organic ligand is incomplete. If the molar ratio is greater than 1:3.5, for example, 1:5, too much basic substance is added, and the deprotonation of the acidic groups on the acidic organic ligand is complete. However, if there is too much remaining basic substance, it will react with copper ions to form precipitates (such as Cu(OH)2, CuCO3), affecting the formation of Cu-MOF crystals.

[0054] In some embodiments, the copper salt includes at least one of copper nitrate, copper acetate, copper citrate, or copper acetylacetonate. Other common copper salts besides those listed are also within the scope of this application.

[0055] In some embodiments, the molar ratio of the acidic organic ligand to the copper salt in the mixture is 1:(0.5-2), for example, 1:0.5, 1:0.8, 1:1, 1:1.2, 1:1.4, 1:1.6, 1:1.8, or 1:2, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. Preferably, the molar ratio of the acidic organic ligand to the copper salt in the mixture is 1:(0.8-1.3).

[0056] In this application, the molar ratio of the acidic organic ligand to the copper salt is 1:(0.5-2). If the molar ratio is less than 1:0.5, the acidic organic ligand will be in excess, resulting in waste; if the molar ratio is greater than 1:2, the copper salt will be in excess, resulting in waste.

[0057] In some embodiments, the solvent is deionized water. Water is preferred as the solvent in this application. While other organic solvents, such as methanol and ethanol, may also dissolve other components, in this application, these organic solvents would complicate the coordination reaction, potentially causing the organic solvent to participate in the reaction, reducing controllability, and increasing cost.

[0058] In some embodiments, the acidic organic ligand and the basic substance are dissolved in a solvent, and the copper salt is dissolved in the solvent, then the two are mixed evenly to form a mixture. In this application, the acidic organic ligand, the basic substance, and the copper salt are dissolved simultaneously in the solvent, resulting in a significantly better coordination reaction rate, crystallinity, and catalytic performance of the copper-carbon composite catalyst compared to existing technologies. As a more preferred approach, the acidic organic ligand and the basic substance are first dissolved in the solvent, allowing the active group of the acidic organic ligand to undergo a deprotonation reaction to transform into its anion, which is more conducive to the subsequent coordination reaction.

[0059] In some embodiments, the coordination reaction time is 0.2-4 hours, for example, 0.2 hours, 0.5 hours, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. Preferably, the coordination reaction time is 0.5-3 hours.

[0060] Due to the coordination reaction in this application, the acidic organic ligands are first treated to their anionic form before reacting with Cu. 2+ CuMOF crystals will form immediately after the solution is mixed, which takes 10-30 minutes, or 2-4 hours, to ensure a more complete and thorough reaction; and the reaction is so complete that no additional crystallization process is required.

[0061] In some embodiments, after the coordination reaction, the copper-organic framework crystal precipitate (Cu-MOF crystal precipitate) is obtained by centrifugation, washing and drying.

[0062] In some embodiments, during the carbonization process in step S2, the carbonization is first performed in a high-temperature tube furnace at a rate of 50-150 mL / min (e.g., 50 mL / min, 60 mL / min, 70 mL / min, 80 mL / min, 85 mL / min, 90 mL / min, 95 mL / min, 100 mL / min, 105 mL / min, 110 mL / min, 115 mL / min, 120 mL / min, 125 mL / min, 130 mL / min, 135 mL / min). Inert gas is introduced at a flow rate of n, 140 mL / min, 145 mL / min, or 150 mL / min, but not limited to the listed values; other unlisted values ​​within the above range also apply. This process is repeated for 5-30 minutes (e.g., 5 min, 10 min, 15 min, 20 min, 25 min, or 30 min, but not limited to the listed values; other unlisted values ​​within the above range also apply). Heating is then started, and the inert gas flow rate is adjusted to 20-50 mL / min (e.g., 20 mL / min, 25 mL / min, 30 mL / min, 35 mL / min, 40 mL / min, 45 mL / min, or 50 mL / min, but not limited to the listed values; other unlisted values ​​within the above range also apply) until the reaction is complete. Preferably, during the carbonization process, an inert gas is first introduced into a high-temperature tube furnace at a flow rate of 80-120 mL / min for 8-15 minutes, then heating is started, and the inert gas flow rate is adjusted to 25-40 mL / min until the reaction is complete.

[0063] Through extensive experimental research, the applicant has discovered for the first time that the operation of the inert gas atmosphere during the carbonization process is highly correlated with the catalytic performance of the copper-carbon composite catalyst. During the carbonization process, divalent copper ions (Cu) from copper salts are... 2+ ( ) is partially or completely reduced to monovalent copper ions (Cu) + The copper particles in the copper-carbon composite catalyst contain Cu, or / and elemental copper (Cu). This application achieves this through precise control of the inert gas atmosphere, ensuring that the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary oxidation state in methanol liquid-phase reforming for hydrogen production Cu + Copper particles form a synergistic catalytic effect with Cu, enhancing catalytic activity and significantly promoting hydrogen generation. If air is completely removed from the equipment (e.g., a high-temperature tubular furnace), the copper in the copper particles is primarily elemental copper (Cu) with zero valence, resulting in poor catalytic performance of the copper-carbon composite catalyst. If a large amount of air remains in the equipment, the copper in the copper particles is mainly divalent copper ions (with almost no catalytic activity), forming copper oxide (CuO), leading to poor catalytic performance.

[0064] The copper-carbon composite catalyst of this application has a high loading of copper particles, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + The binary valence state of Cu results in high catalytic activity. Together, these two components significantly improve the hydrogen production efficiency of this copper-carbon composite catalyst in methanol liquid-phase reforming hydrogen production applications.

[0065] In some embodiments, the copper-carbon composite catalyst has copper particles uniformly dispersed on a carbon support, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary valence state.

[0066] Furthermore, the size of the copper-carbon composite catalyst is 5-20 μm, such as 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, or 20 μm, but not limited to the listed values; other unlisted values ​​within the above range are also applicable. The size of the copper particles is 5-30 nm, such as 5 nm, 10 nm, 15 nm, 20 nm, 25 nm, or 30 nm, but not limited to the listed values; other unlisted values ​​within the above range are also applicable.

[0067] Furthermore, the inert gas includes at least one of nitrogen, helium, neon, argon, krypton, or xenon. In addition to these listed inert gases, other common inert gases are also within the scope of protection of this application.

[0068] Furthermore, the high-temperature calcination carbonization treatment is carried out at a temperature of 400-900℃ (e.g., 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, 800℃, 850℃, or 900℃, but not limited to the listed values; other unlisted values ​​within the above range are also applicable), the calcination time is 1-10h (1h, 2h, 3h, 4h, 5h, 6h, 7h, 8h, 9h, or 10h, but not limited to the listed values; other unlisted values ​​within the above range are also applicable), and the heating rate is 2-8℃ / min (2℃ / min, 3℃ / min, 4℃ / min, 5℃ / min, 6℃ / min, 7℃ / min, or 8℃ / min, but not limited to the listed values; other unlisted values ​​within the above range are also applicable). Preferably, the high-temperature calcination carbonization treatment is carried out at a temperature of 600-800℃, a calcination time of 1-5h, and a heating rate of 3-6℃ / min.

[0069] Furthermore, the aforementioned copper metal-organic framework crystals are precipitated and ground uniformly, and then placed in a high-temperature calcination apparatus for high-temperature carbonization treatment under an inert gas atmosphere. The high-temperature calcination apparatus includes: a high-temperature tube furnace, a crucible, a muffle furnace, etc.

[0070] A second aspect of this application provides a copper-carbon composite catalyst obtained by the above-described preparation method.

[0071] In some embodiments, the copper-carbon composite catalyst comprises copper particles and a carbon support, wherein the copper particles are uniformly dispersed on the carbon support, and the copper element in the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary valence state.

[0072] Furthermore, the copper-carbon composite catalyst has a size of 5-20 μm, and the copper particles have a size of 5-30 nm.

[0073] In a third aspect of this application, the aforementioned copper-carbon composite catalyst is added to the methanol liquid-phase reforming hydrogen production reaction.

[0074] In some embodiments, a copper-carbon composite catalyst and an aqueous methanol solution are mixed and reacted at 180-220°C under an inert gas atmosphere. After cooling, the gaseous product (hydrogen) is collected.

[0075] With the same catalyst addition amount, the copper-carbon composite catalyst of this application, when applied to the methanol liquid-phase reforming hydrogen production reaction, exhibits significantly higher hydrogen production rate and methanol conversion rate than existing technologies.

[0076] The present invention will be further described in detail below with reference to specific embodiments and comparative examples. However, the present invention is not limited to the following embodiments. The implementation conditions used in the embodiments can be further adjusted according to different requirements of specific use. The conditions not specified are conventional conditions in the industry. Example 1:

[0077] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.04 mol (1.6 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 hours. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0078] The copper-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 100 mL / min for 10 minutes, and then heating was started (calcination temperature set at 700℃, heating rate at 5℃ / min), while the nitrogen flow rate was adjusted to 30 mL / min (until the reaction was completed). After reaching 700℃, calcination was carried out for 2 hours, and then cooled to room temperature (25℃) to obtain a copper-carbon composite catalyst. X-ray photoelectron spectroscopy (XPS) was performed on the copper-carbon composite catalyst. The XPS total spectrum showed that copper atoms accounted for 47.91% of all elements, and the calculated mass percentage of copper element was 82%, that is, the copper particle loading in the copper-carbon composite catalyst was 82%, which significantly improved the copper particle loading.

[0079] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 2:

[0080] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.03 mol (1.2 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.016 mol (3.866 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 hours. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0081] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 120 mL / min for 8 minutes, and then heating was started (calcination temperature set at 700℃, heating rate at 5℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 28 mL / min (until the reaction was completed). After reaching 700℃, calcination was carried out for 2 hours, and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0082] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 3:

[0083] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.05 mol (2 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.026 mol (6.282 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 hours. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0084] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 110 mL / min for 10 minutes, and then heating was started (calcination temperature set at 700℃, heating rate at 5℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 28 mL / min (until the reaction was completed). After reaching 700℃, calcination was carried out for 2 hours, and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0085] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 4:

[0086] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.04 mol (1.6 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (3.993 g) of copper acetate monohydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 1.5 h. Centrifuge the mixture at 3000 rpm for 5 min, wash three times with water, and then dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0087] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 100 mL / min for 10 minutes, and then heating was started (the calcination temperature was set to 700℃ and the heating rate was 5℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 30 mL / min (until the reaction was completed). After reaching 700℃, the calcination was carried out for 2 hours and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0088] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 5:

[0089] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) isophthalic acid, 0.02 mol (2.12 g) sodium carbonate, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 hours. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0090] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 100 mL / min for 10 minutes, and then heating was started (the calcination temperature was set to 700℃ and the heating rate was 5℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 30 mL / min (until the reaction was completed). After reaching 700℃, the calcination was carried out for 2 hours and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0091] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 6:

[0092] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.04 mol (1.6 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 h. Centrifuge the mixture at 3000 rpm for 5 min, wash three times with water, and then dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0093] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 90 mL / min for 15 minutes, and then heating was started (the calcination temperature was set to 600℃ and the heating rate was 4℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 30 mL / min (until the reaction was completed). After reaching 600℃, the calcination was carried out for 4 hours and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0094] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography. Example 7:

[0095] Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.04 mol (1.6 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 1 hour. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0096] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was first introduced at a flow rate of 110 mL / min for 10 minutes, and then heating was started (calcination temperature set at 800℃ and heating rate at 6℃ / min). At the same time, the nitrogen gas flow rate was adjusted to 28 mL / min (until the reaction was completed). After reaching 800℃, calcination was carried out for 1.5 h, and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0097] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography.

[0098] Comparative Example 1: Preparation of copper-carbon composite catalysts: 2.1 g of copper nitrate trihydrate was dissolved in 35 ml of DMF (N,N-dimethylformamide), denoted as solution A. 1.5 g of terephthalic acid and 0.75 g of polyvinylpyrrolidone (PVP) (Mw = 10000) were dissolved in 35 ml of DMF, denoted as solution B. After thorough mixing, solution B was added to solution A to obtain a mixed solution. This mixed solution was placed in a 100 ml hydrothermal reactor lined with polytetrafluoroethylene and then placed in an oven for crystallization at 85°C for 40 h. After crystallization, the solution was removed, washed three times with anhydrous ethanol, and dried in a vacuum oven at 80°C to obtain CuMOF material.

[0099] The obtained CuMOF material was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was introduced for protection at a flow rate of 30 mL / min (until the reaction was completed). Heating was started (calcination temperature set at 700℃, heating rate at 2℃ / min) and calcined for 4 hours. The temperature was then lowered to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0100] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography.

[0101] Comparative Example 2: Preparation of copper-carbon composite catalysts: In a 200 mL beaker, add 0.02 mol (3.323 g) of terephthalic acid, 0.04 mol (1.6 g) of sodium hydroxide, and 50 mL of water. Stir magnetically until completely dissolved, and label this solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) of copper nitrate trihydrate and 50 mL of water. Stir magnetically until completely dissolved, and label this solution B. Pour solution B into solution A to form a mixture. Stir magnetically (700 rpm) for 2 hours. Centrifuge the mixture at 3000 rpm for 5 minutes. Wash three times with water. Then, dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0102] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. The furnace was evacuated and nitrogen was introduced three times to completely remove the air. Heating was then started (calcination temperature set at 700℃, heating rate at 5℃ / min), while the nitrogen flow rate was adjusted to 30mL / min (until the reaction was completed). After reaching 700℃, the furnace was calcined for 2 hours and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0103] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography.

[0104] Comparative Example 3: Preparation of copper-carbon composite catalyst: In a 200 mL beaker, add 0.02 mol (3.323 g) terephthalic acid, 0.04 mol (1.6 g) sodium hydroxide, and 50 mL of water, and stir magnetically until completely dissolved; this is denoted as solution A. In another 200 mL beaker, add 0.02 mol (4.832 g) copper nitrate trihydrate and 50 mL of water, and stir magnetically until completely dissolved; this is denoted as solution B. Pour solution B into solution A to form a mixture, and stir magnetically (700 rpm) for 2 h. Centrifuge the resulting mixture at 3000 rpm for 5 min, wash three times with water, and then dry the solid precipitate in a vacuum drying oven at 80 °C to obtain a copper metal-organic framework crystal precipitate (Cu-MOF crystal precipitate).

[0105] The copper-metal-organic framework crystal precipitate (Cu-MOF crystal precipitate) was ground evenly in a mortar and then placed in a high-temperature tube furnace. Nitrogen gas was introduced for protection at a flow rate of 30 mL / min (until the reaction was completed). Heating was started (calcination temperature set at 700℃, heating rate at 5℃ / min). After reaching 700℃, calcination was carried out for 2 hours, and then cooled to room temperature (25℃) to obtain the copper-carbon composite catalyst.

[0106] Application testing of methanol liquid-phase reforming for hydrogen production: In a 70 mL reactor, 50 mg of the aforementioned copper-carbon composite catalyst and 20 mL of methanol-water solution (methanol to water volume ratio of 1:1) were added. The reactor was then purged and vented three times with nitrogen gas at 2.0 MPa as a protective gas, and then purged again to 2.0 MPa and sealed. The reactor temperature was maintained at 210 °C and the reaction was carried out under magnetic stirring for 1 h. After the reaction was completed and cooled to room temperature, the gaseous products were collected, and the hydrogen content was determined by gas chromatography.

[0107] from Figure 1 It can be seen that Cu-MOF crystals are elongated strips with a length of 5-20 μm. From Figure 2 It can be seen that the copper-carbon composite catalyst obtained after calcination retains its elongated external morphology. From Figure 3 It can be seen that the internal microstructure of the copper-carbon composite catalyst consists of copper particles of 5-30 nm uniformly attached to the carbon support.

[0108] from Figure 4 It can be seen that the XRD peaks of Cu-MOF crystals are very sharp and have high intensity, indicating that Cu-MOF crystals have a high degree of crystallization and good crystallinity. From Figure 5 It can be seen that the copper-carbon composite catalyst at 36.6 O The XRD peak at 43.5 is a characteristic peak of Cu₂O, corresponding to monovalent copper; O 50.6 O 74.3 O The XRD peak at that location is a characteristic peak of elemental Cu, corresponding to zero-valent copper.

[0109] Figure 6 The Auger spectrum of copper in the copper-carbon composite catalyst of Example 1 is obtained by XPS fitting using the nonlinear least squares method. + The content of [unspecified substance] is 41%, and the content of Cu is 59%. The element copper is Cu. + / Cu binary valence state, no Cu 2+ This represents the ideal state for high catalytic activity, resulting in high catalytic activity.

[0110] from Figure 7It can be seen that the hydrogen production rate of Examples 1-7 of this application is significantly higher than that of Comparative Example 1 of the prior art. That is, in the methanol liquid-phase reforming hydrogen production reaction, the catalytic performance of the copper-carbon composite catalyst of this application is significantly better than that of the prior art, and the efficiency of methanol to hydrogen conversion is significantly improved. Compared with Comparative Examples 2-3, Examples 1-7 completely eliminate air in the calcination equipment, and the copper element in the copper particles is mainly elemental copper (Cu) with zero valence; when more air is retained in the calcination equipment, the copper element in the copper particles is mainly divalent copper ions (with almost no catalytic activity); the catalytic performance of the resulting copper-carbon composite catalyst will be significantly reduced.

[0111] Although this application discloses several aspects and embodiments, other aspects and embodiments will be obvious to those skilled in the art. Various modifications and improvements can be made without departing from the concept of this application, and these all fall within the scope of protection of this application. The various aspects and embodiments disclosed in this application are for illustrative purposes only and are not intended to limit this application. The actual scope of protection of this application is determined by the claims.

Claims

1. A method for preparing a copper-carbon composite catalyst, characterized in that, Including the following steps: S1, acidic organic ligands, basic substances and copper salts are dissolved in a solvent and mixed evenly to form a mixed solution, and a coordination reaction is performed to generate copper metal-organic framework crystal precipitates; S2, the above copper metal-organic framework crystals are precipitated and ground evenly, and then carbonized by high-temperature calcination under an inert gas atmosphere to generate a copper-carbon composite catalyst.

2. The preparation method of the copper-carbon composite catalyst according to claim 1, characterized in that, In step S1, one or more features selected from the group consisting of: (1) The acidic organic ligand comprises: a benzene ring and an active group; the benzene ring is not easily broken during carbonization to form a carbon skeleton, and the active group participates in the coordination reaction; (2) The alkaline substance is an inorganic substance that is easily soluble in water and has a pKb ≤ 4; (3) In the mixture, the concentration of the acidic organic ligand is 0.1-0.5 mol / L, and the molar ratio of the acidic organic ligand to the alkaline substance is 1:(0.8-3.5). (4) The solvent is deionized water.

3. The preparation method of the copper-carbon composite catalyst as described in claim 2, characterized in that, Includes one or more features selected from the following group: (1) The acidic organic ligand includes at least one of terephthalic acid, isophthalic acid, phthalic acid, or aminoterephthalic acid; (2) The alkaline substance includes at least one of sodium hydroxide, sodium carbonate, potassium hydroxide, or potassium carbonate; (3) In the mixture, the concentration of the acidic organic ligand is 0.25-0.45 mol / L, and the molar ratio of the acidic organic ligand to the alkaline substance is 1:(1-3).

4. The preparation method of the copper-carbon composite catalyst according to claim 1, characterized in that, The copper salt includes at least one of copper nitrate, copper acetate, copper citrate, or copper acetylacetone; in the mixture, the molar ratio of the acidic organic ligand to the copper salt is 1:(0.5-2).

5. The method for preparing the copper-carbon composite catalyst as described in claim 1, characterized in that, Acidic organic ligands and basic substances are dissolved in a solvent, and copper salts are dissolved in the solvent. The two are then mixed thoroughly to form a mixture.

6. The method for preparing the copper-carbon composite catalyst as described in claim 1, characterized in that, The coordination reaction takes 0.2-4 hours.

7. The method for preparing the copper-carbon composite catalyst as described in claim 1, characterized in that, In step S2, during the carbonization process, inert gas is first introduced into a high-temperature tube furnace at a flow rate of 50-150 mL / min for 5-30 minutes, then heating is started, and the inert gas flow rate is adjusted to 20-50 mL / min until the reaction is complete. Preferably, during the carbonization process, an inert gas is first introduced into a high-temperature tube furnace at a flow rate of 80-120 mL / min for 8-15 minutes, then heating is started, and the inert gas flow rate is adjusted to 25-40 mL / min until the reaction is complete. Preferably, the high-temperature calcination carbonization treatment is carried out at a temperature of 400-900℃, a calcination time of 1-10h, and a heating rate of 2-8℃ / min.

8. A copper-carbon composite catalyst, characterized in that, The copper-carbon composite catalyst is obtained by any one of the preparation methods described in claims 1-7; wherein the copper-carbon composite catalyst comprises copper particles and a carbon support, the copper particles are uniformly dispersed on the carbon support, and the copper element of the copper particles is Cu. 2+ / Cu + / Cu ternary oxidation state, or Cu + / Cu binary valence state.

9. The copper-carbon composite catalyst as described in claim 8, characterized in that, The copper-carbon composite catalyst has a size of 5-20 μm, and the copper particles have a size of 5-30 nm.

10. The application of the copper-carbon composite catalyst obtained by the preparation method of any one of claims 1-7, and the copper-carbon composite catalyst as described in any one of claims 8-9, in the methanol liquid-phase reforming hydrogen production reaction; the copper-carbon composite catalyst and methanol aqueous solution are mixed, reacted under inert gas protection at 180-220°C, and the gaseous products are collected after cooling.

Images