A cobalt-indium-carbon catalyst suitable for hydrogen production by methanol liquid-phase reforming and aromatic hydrocarbon hydrogenation, and a preparation method and application thereof

Abstract

The application provides a cobalt-indium-carbon catalyst suitable for hydrogen production by methanol liquid-phase reforming and aromatic hydrocarbon hydrogenation, and a preparation method and application thereof, and belongs to the technical field of metal carbide catalyst preparation. The preparation method of the cobalt-indium-carbon catalyst comprises the following steps: adding a cobalt source, an indium source, an amino acid coordination additive and a nitrogen-rich carrier into a solvent containing an organic amine, placing the obtained mixed solution in a reaction kettle, and performing a hydrothermal reaction under a solvent filling rate of 20-40%; after the reaction is completed, filtering, washing and drying are performed to obtain a nitrogen-anchored metal precursor / support intermediate; and the nitrogen-anchored metal precursor / support intermediate is subjected to high-temperature carbonization to obtain the cobalt-indium-carbon catalyst. Through a nitrogen-anchoring pre-carbonization-syngas controllable carbonization two-step sequence method, an amino acid coordination additive is introduced, a coordination complex-nitrogen anchoring double anchoring system is constructed, and the prepared cobalt-indium-carbon bimetallic carbide catalyst can be simultaneously used for hydrogen production by methanol liquid-phase reforming and naphthalene hydrogenation reaction of ethylene tar.

Description

Technical Field

[0001] This invention relates to a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation, as well as its preparation method and application, belonging to the field of metal carbide catalyst preparation technology. Background Technology

[0002] The petrochemical industry faces the dual demands of optimizing energy supply and utilizing heavy oil resources. Ethylene tar naphthalene hydrorefining and methanol liquid-phase reforming for on-site hydrogen production are two key directions, both placing stringent industrial requirements on the efficiency and stability of catalysts. Traditional intermetallic carbide catalysts are constrained by the difficulty in precisely controlling their structure and insufficient industrial cycle stability. One-step and impregnation methods cannot control their microcrystalline form and metal dispersion, resulting in low activity and rapid cycle performance degradation in methanol-to-hydrogen production, low conversion rates in naphthalene hydrogenation, and weak applicability to aromatic substrates, making it difficult to meet the needs of large-scale petrochemical production.

[0003] Current catalyst improvements primarily focus on single catalytic reactions, failing to consider the synergistic needs of hydrogen production and heavy oil hydrogenation, and neglecting to optimize the preparation process based on the thermodynamic characteristics of petrochemical reaction systems. Furthermore, existing preparation processes rely solely on nitrogen sites on the support or solvents to anchor the metal precursor, which easily leads to agglomeration and uneven dispersion of metal ions during hydrothermal nucleation. Even with low solvent filling rates, achieving molecular-level dispersion of the metal precursor remains difficult, limiting the number of exposed active sites and structural stability of the catalyst. For example, Chinese patent document CN111545199A provides a supported platinum-tin bimetallic catalyst. Pt3Sn nanoparticles are first prepared via solvothermal synthesis, corroded with NaOH, and then loaded onto a CeO2 support using adsorption. Subsequent calcination forms a PtSn-c / CeO2 catalyst. However, this method of synthesizing macromolecular polymers (such as PVP) with strongly basic reagents has significant drawbacks: it not only easily leads to residual interfacial impurities and complex purification procedures, but its stepwise asynchronous strategy of "pre-nucleation followed by interfacial immobilization" also greatly increases the thermodynamic tendency for secondary agglomeration of nanocrystals, resulting in limited dispersion of the active phase and weak metal-support interaction (MSI). More seriously, the harsh strongly basic medium can easily cause excessive stripping and erosion of the pre-set bimetallic lattice, thereby weakening or even completely destroying the precise order of the core catalytic sites.

[0004] Therefore, it is of great significance to develop a catalyst with high activity, high stability and wide substrate applicability that can be adapted to both methanol liquid-phase reforming for hydrogen production and ethylene tar naphthalene hydrogenation reaction. Summary of the Invention

[0005] To address the shortcomings of existing technologies, particularly the problems of uneven metal precursor dispersion, insufficient exposure of active sites, and the need to improve catalyst stability in traditional processes, this invention provides a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation, along with its preparation method and applications. This invention innovatively introduces amino acid-based coordination additives through a two-step sequential method of "nitrogen-anchored pre-carbonization - controlled syngas carbonization," constructing a "coordination complexation - nitrogen-anchoring" dual-anchoring system. The prepared cobalt-indium-carbon bimetallic carbide catalyst can be used simultaneously for methanol liquid-phase reforming to produce hydrogen and ethylene tar naphthalene hydrogenation reactions, exhibiting high activity, high stability, and wide substrate applicability, along with high metal resource utilization, demonstrating significant economic and industrial application value.

[0006] The technical solution of the present invention is as follows:

[0007] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation includes the following steps:

[0008] (1) Cobalt source, indium source, amino acid coordination additive and nitrogen-rich support are added to a solvent containing organic amine. The resulting mixture is placed in a reaction vessel and hydrothermal reaction is carried out at a solvent filling rate of 20-40%. After the reaction is completed, the mixture is filtered, washed and dried to obtain nitrogen-anchored metal precursor / support intermediate.

[0009] (2) The nitrogen-anchored metal precursor / carrier intermediate obtained in step (1) is carbonized at high temperature to obtain a cobalt indium carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation.

[0010] According to a preferred embodiment of the present invention, the cobalt source in step (1) is cobalt octacarbonyl or cobalt nitrate (Co(NO3)2·6H2O); the indium source is InCl3 or indium nitrate; and the molar ratio of cobalt in the cobalt source to indium in the indium source is 3:1.

[0011] According to a preferred embodiment of the present invention, the amino acid coordination additive in step (1) is glycine or histidine; the ratio of the total molar number of cobalt element in the cobalt source and indium element in the indium source to the molar number of amino acid coordination additive is 1:0.5-2.

[0012] According to a preferred embodiment of the present invention, the nitrogen-rich carrier in step (1) is g-C3N4; the g-C3N4 can be commercially available or prepared according to existing technology. Preferably, the g-C3N4 is prepared by the following method: weigh melamine and place it in a covered crucible. Then place the crucible in a muffle furnace and heat it to 140-160°C at a heating rate of 1-5°C / min, hold it for 20-40 min, and then heat it to 500-600°C at a heating rate of 0.5-2°C / min, hold it for 100-150 min. After that, cool it naturally to room temperature and grind it through a 200-mesh sieve to obtain the g-C3N4 carrier.

[0013] According to a preferred embodiment of the present invention, the mass of cobalt element in the cobalt source in step (1) is 0.1-2.5% of the mass of the nitrogen-rich support.

[0014] According to a preferred embodiment of the present invention, the organic amine in step (1) is urea or ethylenediamine; the solvent is N,N-dimethylformamide, methanol or acetone; and the concentration of the organic amine in the solvent containing the organic amine is 0.01-0.1 mol / L.

[0015] According to a preferred embodiment of the present invention, the ratio of the total mass of the cobalt source, indium source, amino acid coordination additive and nitrogen-rich support in step (1) to the volume of the solvent containing organic amine is 1 mg: 0.2-0.5 mL. This ratio can ensure that the cobalt source, indium source, amino acid coordination additive and nitrogen-rich support are fully dispersed and coordinated in the hydrothermal system, and can also avoid the local agglomeration and uneven nucleation of the metal precursor due to excessive raw material concentration, thereby stably realizing the molecular-level dispersion of the metal precursor and the construction of the M-AA-NC dual anchoring interface.

[0016] According to the present invention, the solvent filling rate in step (1) refers to the percentage of the volume of the solvent containing organic amines to the volume of the reactor; the solvent filling rate is preferably 25-35%.

[0017] According to a preferred embodiment of the present invention, the temperature of the hydrothermal reaction in step (1) is 210-240°C, and the time of the hydrothermal reaction is 4-12h.

[0018] According to a preferred embodiment of the present invention, the washing in step (1) is washing with anhydrous ethanol 2-4 times, and the drying is drying at 50-60°C to constant weight.

[0019] According to a preferred embodiment of the present invention, the high-temperature carbonization in step (2) is carried out in a CO / H2 / Ar mixed gas, wherein the volume percentage of CO in the CO / H2 / Ar mixed gas is 3-10%, the volume percentage of H2 is 10-30%, and the flow rate of the CO / H2 / Ar mixed gas is 20-40 mL / min.

[0020] According to a preferred embodiment of the present invention, the high-temperature carbonization temperature in step (2) is 380-420°C, the high-temperature carbonization time is 30-90 min, and the heating rate is 2-6°C / min.

[0021] This invention provides a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation, which is prepared by the above-described preparation method.

[0022] According to the present invention, the above-mentioned cobalt indium carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is used to catalyze the methanol liquid-phase reforming to produce hydrogen or the ethylene tar naphthalene hydrogenation reaction.

[0023] The technical features and beneficial effects of this invention are as follows:

[0024] 1. This invention employs a low solvent filling rate, combined with the complexing effect of amino acid-based coordination additives, to jointly regulate the hydrothermal nucleation environment, thereby achieving molecular-level dispersion of the metal precursor and forming a highly dispersed and strongly anchored metal precursor.

[0025] 2. This invention utilizes the nitrogen sites of a nitrogen-rich support to achieve chemical anchoring of metal ions. At the same time, the amino and carboxyl groups of amino acids form stable coordination complexes with metal ions, constructing a stable "metal-amino acid-nitrogen-carbon (M-AA-NC)" dual anchoring interface. This achieves molecular-level dispersion of the metal precursor on the support, laying the structural foundation for the high catalytic activity of the catalyst.

[0026] 3. This invention uses syngas (CO / H2 / Ar) for controlled carburizing, and achieves the orderly growth of metal carbide structures on the basis of a double anchoring interface, thereby improving the crystal regularity and structural stability of the catalyst and obtaining a highly active catalyst.

[0027] 4. The catalyst prepared by this invention has the characteristics of high metal dispersion, regular carbide structure and strong metal-support interaction. At the same time, it maintains the synergistic catalytic performance of methanol to hydrogen production and aromatic hydrogenation, and has high catalytic activity and cycle stability. In methanol liquid phase reforming to hydrogen production and aromatic hydrogenation reactions, it shows significantly higher catalytic activity and excellent cycle stability (>97%) than traditional methods, and has broad prospects for industrial application. Attached Figure Description

[0028] Figure 1 The image shows a mapping diagram of the cobalt-indium-carbon catalyst prepared in Example 1, which is suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation.

[0029] Figure 2 The image shows the XRD pattern of the cobalt-indium-carbon catalyst prepared in Example 1, which is suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation.

[0030] Figure 3TEM image of the cobalt-indium-carbon catalyst prepared in Example 1, suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation. Detailed Implementation

[0031] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited thereto.

[0032] The g-C3N4 used in the examples was prepared as follows: melamine was weighed and placed in a covered crucible. The crucible was then placed in a muffle furnace and heated to 150°C at a rate of 2°C / min, held for 30 min, and then heated to 550°C at a rate of 1°C / min, held for 120 min. After that, it was naturally cooled to room temperature and ground through a 200-mesh sieve to obtain the g-C3N4 carrier, which was then set aside for use.

[0033] Example 1

[0034] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation includes the following steps:

[0035] (1) 5.2 mg of octacarbonyl cobalt, 2.2 mg of InCl3, 6.3 mg of histidine (1 times the total molar amount of Co and In) and g-C3N4 support (the mass of cobalt in octacarbonyl cobalt is 2% of the mass of g-C3N4 support, i.e., the loading is 2wt%) were added to 30 mL of N,N-dimethylformamide solution containing urea (the concentration of urea in the N,N-dimethylformamide solution containing urea is 0.05 mol / L). The mixture was ultrasonically stirred at room temperature for 10 min and placed in a 100 mL PPL hydrothermal reactor with a solvent filling rate of 30%. The mixture was hydrothermally reacted at 220 °C for 6 h. After the reaction was completed, the mixture was naturally cooled to room temperature. The resulting reaction solution was filtered, and the solid obtained by filtration was washed three times with anhydrous ethanol. The solid obtained by washing was then vacuum dried at 60 °C to constant weight to obtain a nitrogen-anchored metal precursor / support intermediate.

[0036] (2) The nitrogen-anchored metal precursor / carrier intermediate was placed in a tube furnace. Argon gas was first introduced to purge the furnace for 30 min to remove air. Then the gas was switched to a CO / H2 / Ar mixture (the volume percentage of CO in the CO / H2 / Ar mixture was 5%, the volume percentage of H2 was 20%, and the volume percentage of Ar was 75%). The gas flow rate was maintained at 30 mL / min, and the temperature was increased to 400℃ at a rate of 5℃ / min. The temperature was held for 60 min and then naturally cooled to room temperature to obtain the nitrogen-anchored-amino acid-coordinated intermetallic carbide, which is a cobalt-indium carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation, denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His.

[0037] The mapping diagram of the cobalt-indium-carbon catalyst prepared in this embodiment, suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation, is shown below. Figure 1 As shown, by Figure 1 It can be clearly observed that elements such as Co, In, C, and N are uniformly distributed on the g-C3N4 support, without obvious element aggregation or segregation. This directly proves that the dual anchoring process of amino acid coordination complexation and nitrogen anchoring has achieved molecular-level dispersion of metal precursors on the support, and successfully constructed a uniform M-AA-NC interface, laying the structural foundation for the high catalytic activity of the catalyst.

[0038] The XRD pattern of the cobalt-indium-carbon catalyst prepared in this embodiment, suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation, is shown below. Figure 2 As shown, by Figure 2 It can be seen that the phase and crystal form characterization spectra of the catalyst show characteristic diffraction peaks corresponding to the (100), (111), (200), and (220) crystal planes at 2θ positions of 32°, 40°, 47°, and 68°, respectively. The narrow and sharp peaks of this series indicate that the catalyst has excellent crystallinity, and its diffraction peak characteristics are in excellent agreement with those of the standard card PDF No. 29-0483. This indicates that after amino acid coordination-nitrogen anchoring pre-carbonization-syngas controllable carbonization, the catalyst forms a cobalt-indium bimetallic carbide with a single crystal form and a more regular structure. It also corroborates the strong bonding between the metal and the support, and verifies the precise controllability of the carbide phase by the dual-anchoring two-step sequential construction method.

[0039] TEM images of the cobalt-indium-carbon catalyst prepared in this embodiment, suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrogenation, are shown below. Figure 3 As shown, by Figure 3 It can be clearly seen that cobalt indium carbide nanoparticles are uniformly attached to the surface of g-C3N4 support. The particles are of uniform size and have no obvious agglomeration. They are tightly bound to the support, which proves that the synergistic effect of low solvent filling rate and dual anchoring enables the orderly growth of metal carbides. Moreover, the metal-support interface is firmly bonded, providing direct microstructural support for the high stability of the catalyst.

[0040] Example 2

[0041] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that in step (1), histidine is replaced with an equimolar amount of glycine, and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-Gly.

[0042] Example 3

[0043] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is as described in Example 1, except that in step (1), 0.52 mg of octacarbonyl dicobalt, 0.22 mg of InCl3, 0.63 mg of histidine (1 times the total molar amount of Co + In) and g-C3N4 support (the mass of cobalt in octacarbonyl dicobalt is 0.2% of the mass of g-C3N4 support, i.e., the loading is 0.2 wt%) are added to 30 mL of N,N-dimethylformamide solution containing urea (the concentration of urea in the N,N-dimethylformamide solution containing urea is 0.05 mol / L), and other conditions are the same as in Example 1; the resulting catalyst is denoted as N-Co3InC 0.75 / C3N4-0.2-30%-His.

[0044] Example 4

[0045] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that: in step (1), the amount of histidine added is 12.5 mg (the amount of histidine added is twice the total molar amount of Co + In elements), and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His-2.

[0046] Example 5

[0047] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that: in step (1), the amount of histidine added is 3.2 mg (the amount of histidine added is 0.5 times the total molar amount of Co + In elements), and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His-0.5.

[0048] Example 6

[0049] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that: the volume of the N,N-dimethylformamide solution containing urea in step (1) is 25 mL, and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-25%-His.

[0050] Example 7

[0051] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that urea is replaced with ethylenediamine in step (1), and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His-EDA.

[0052] Example 8

[0053] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that in step (1), octacarbonyl dicobalt is replaced with Co(NO3)2·6H2O with an equimolar cobalt content, and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His-Co(NO3)2.

[0054] Example 9

[0055] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that in step (1), InCl3 is replaced with indium nitrate with an equimolar indium content, and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-His-In(NO3)3.

[0056] Comparative Example 1

[0057] A method for preparing a cobalt-indium catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation includes the following steps:

[0058] 5.2 mg of cobalt octacarbonyl, 2.2 mg of InCl3, and g-C3N4 support (the mass of cobalt in cobalt octacarbonyl is 2% of the mass of g-C3N4 support) were added to 30 mL of 0.05 mol / L urea aqueous solution. The mixture was ultrasonically stirred at room temperature for 10 min, and then dried at 60 °C for 10 h. The dried sample was placed in a tube furnace and heated to 220 °C at a heating rate of 5 °C / min in an atmosphere of H2 / N2 mixed gas (the volume percentage of H2 in the mixed gas is 5% and the volume percentage of N2 is 95%). The mixture was calcined and reduced for 2 h and then naturally cooled to room temperature to obtain a conventional impregnation method supported catalyst, which is a cobalt-indium catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation, denoted as Co3In / C3N4-WI.

[0059] Comparative Example 2

[0060] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that histidine is not added in step (1), and the resulting catalyst is denoted as N-Co3InC. 0.75 / C3N4-2.0-30%-No AA.

[0061] Comparative Example 3

[0062] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that in step (1), the g-C3N4 support is replaced with an equal mass of commercial activated carbon (AC), and the resulting catalyst is denoted as N-Co3InC. 0.75 / AC-2.0-30%-His.

[0063] Comparative Example 4

[0064] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation is described in Example 1, except that in step (1), the solvent is replaced with 30 mL of N,N-dimethylformamide and the solvent does not contain urea.

[0065] Comparative Example 5

[0066] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that the solvent volume in step (1) is 10 mL.

[0067] Comparative Example 6

[0068] A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation is described in Example 1, except that the solvent volume in step (1) is 60 mL.

[0069] Experimental Example 1

[0070] Methanol liquid-phase reforming for hydrogen production

[0071] The catalysts prepared in the examples and comparative examples were used in the methanol liquid-phase reforming hydrogen production reaction. The specific steps are as follows: 2g of potassium hydroxide was added to 8mL of methanol-water solution (methanol to water mass ratio of 2:1) to obtain the reaction substrate. The reaction conditions were: initial nitrogen pressure of 1MPa, reaction temperature of 190℃, reaction time of 90 minutes, and catalyst dosage of 5mg. The hydrogen production performance was analyzed using an Agilent 8890 gas chromatograph, and the hydrogen production rate (mol / kgcat) was calculated. -1 h -1 The stability after 10 cycles is shown in Table 1.

[0072] Table 1. Test results of methanol liquid-phase reforming for hydrogen production using different catalysts.

[0073]

[0074] In the table, stability after 10 cycles refers to the ratio of the hydrogen production rate after 10 catalyst cycles to the hydrogen production rate in the first cycle.

[0075] Results analysis:

[0076] Table 1 shows the hydrogen production rate and 10-cycle stability test results of the catalysts in the methanol liquid-phase reforming hydrogen production reaction of each example and the comparative example. The core verification is that the introduction of amino acid-based coordinating additives, solvent filling rate, metal loading, and nitrogen-rich support play a regulatory role in the hydrogen production activity and structural stability of the catalysts. The specific analysis is as follows:

[0077] (1) Amino acid coordination additives are the core factor in improving hydrogen production activity: Examples 1-9 with added histidine / glycine all showed significantly higher hydrogen production rates than Comparative Example 2 without amino acid addition, with Example 1 (1 molar amount of histidine) achieving a hydrogen production rate of 148 mol kgcat. -1 h -1 Example 2 (1 molar amount of glycine) yielded 142 mol kgcat. -1 h -1 The results demonstrate that the coordination complexation between amino acids and metal ions can achieve molecular-level dispersion of metal precursors, increase the number of exposed active sites, and significantly improve the intrinsic hydrogen production activity of the catalyst. Furthermore, histidine has a slightly better modification effect than glycine, which is due to the hydrogen bonding between the N atom of its imidazole ring and the g-C3N4 support, which further strengthens the metal-support interface bonding.

[0078] (2) There is an optimal ratio between metal loading and amino acid addition: Example 3 has a low cobalt loading of 0.2% and a hydrogen production rate of 445 mol kgcat. -1 h -1 The highest value among all samples indicates that the coordination and dispersion of amino acids are more significant under low loading, achieving high catalytic efficiency with low metal content and greatly improving the utilization rate of precious metal resources; Example 4 used twice the molar amount of histidine, and the hydrogen production rate was slightly reduced to 145 mol kgcat. -1 h -1 This indicates that adding excessive amounts of amino acids does not provide additional benefit, and the optimal addition range is 0.5 to 1 times the total molar amount of metals.

[0079] (3) Low solvent filling rate adapted to dual anchoring system: Example 1 (30% filling rate) hydrogen production rate 148 mol kgcat -1 h -1 Higher than Example 6 (25% fill rate) 141 mol kgcat -1 h -1 This demonstrates that a 30% solvent filling rate is the optimal condition for hydrothermal nucleation, and can synergistically regulate the dispersion and anchoring of metal precursors with amino acid coordination, avoiding the problem of uneven material mixing caused by excessively low filling rates. The hydrogen production rates of Comparative Example 5 (too low solvent filling rate, 10%) and Comparative Example 6 (too high solvent filling rate, 60%) were 10⁸ mol kgcat, respectively. -1 h -1 and 115 mol kgcat-1 h -1 The stability after 10 cycles was 85% and 87%, respectively, both significantly lower than that of Example 1 (30% filling rate). This further emphasizes the decisive influence of precise control of solvent filling rate on catalyst performance. Too low a filling rate may lead to insufficient contact of reactants, decreased mass transfer efficiency, and is detrimental to the uniform nucleation and dispersion of metal precursors; while too high a filling rate may dilute the reactant concentration or affect the autogenous pressure of the hydrothermal system, thereby altering the crystal growth environment and resulting in irregular catalyst structure or hindered formation of active sites. Therefore, a solvent filling rate of 25-35% (preferably 30%) is a key process parameter for synergistic amino acid coordination and nitrogen anchoring to achieve high-performance catalyst preparation.

[0080] (4) The nitrogen-rich g-C3N4 support is the basis for the high stability of the catalyst: the stability of all 1-9 examples after 10 cycles is not less than 97%, which is much higher than that of Comparative Example 3 (88%) which was replaced with commercial activated carbon support, Comparative Example 2 (84%) which was without amino acids and Comparative Example 1 (82%) which was obtained by traditional impregnation method; even though histidine was added to Comparative Example 3, the stability still dropped significantly because the activated carbon had no nitrogen sites and could not form the M-AA-NC double anchoring interface. This directly proves that the synergistic effect of nitrogen anchoring and amino acid coordination of g-C3N4 can effectively inhibit the sintering and loss of metal particles in high-temperature reaction and significantly improve the cycle stability of the catalyst.

[0081] (5) The process of this invention is far superior to the traditional preparation method: Comparative Example 1 of the traditional impregnation method has no amino acid coordination and nitrogen anchoring synergy, and the hydrogen production rate is only 87 mol kgcat. -1 h -1 The stability was 82%, which is significantly different from the embodiment of the present invention, proving the process superiority of the two-step sequential method of "amino acid coordination-nitrogen anchoring pre-carbonization-syngas controllable carbonization".

[0082] (6) Necessity of organic amines: The hydrogen production rate of Comparative Example 4 (without added organic amines, using only N,N-dimethylformamide as solvent) was only 121 mol kgcat. -1 h -1 The stability after 10 cycles was 86%, significantly lower than that of Example 1 (hydrogen production rate 148 mol kgcat). -1 h -1 (Stability 98%). This indicates that organic amines (such as urea) do not merely exist as solvents in hydrothermal reactions; they may further promote the uniform dispersion and nitrogen anchoring of metal precursors by regulating the microenvironment of the reaction system, participating in coordination, or acting as a nitrogen source, thus playing a crucial role in the activity and stability of the catalyst.

[0083] (7) Universality of organic amine types: Example 7 (organic amine is ethylenediamine) hydrogen production rate is 146 mol kgcat-1 h -1 The stability after 10 cycles was 98%, which is close to the performance of Example 1 (urea). This proves that organic amines such as urea and ethylenediamine can effectively regulate the hydrothermal microenvironment and enhance nitrogen anchoring and coordination dispersion. The organic amines selected in this invention have a wide range and strong process compatibility, which is conducive to industrial scale-up.

[0084] (8) The hydrogen production rates of Examples 8 (cobalt nitrate) and 9 (indium nitrate) were 145 mol kgcat, respectively. -1 h -1 144mol kgcat -1 h -1 The stability after 10 cycles was 98%, which is close to the performance of Example 1 (octacarbonyl dicobalt, InCl3), proving that the present invention has strong compatibility with cobalt salt and indium salt types, and can form a stable M-AA-NC double anchoring interface and ordered carbide structure with different inorganic metal sources.

[0085] Experimental Example 2

[0086] hydrogenation reaction

[0087] The specific steps are as follows: The reaction was carried out in a high-pressure micro reactor. 0.2 g of naphthalene and 0.05 g of the catalyst from Example 1 were taken and 15 mL of n-heptane was added as solvent. The initial H2 pressure was 5 MPa, and the reaction was carried out at 130 °C, 160 °C, 190 °C, and 220 °C for 6 h respectively. The product was analyzed by gas chromatography, and the naphthalene conversion rate was calculated, as shown in Table 2.

[0088] Table 2 Hydrogenation performance of the catalyst in Example 1 for naphthalene

[0089]

[0090] Table 2 shows the test results of naphthalene hydrogenation conversion rate of the catalyst in Example 1 at different temperatures, which essentially verifies the temperature response and catalytic efficiency of the catalyst of the present invention for the naphthalene hydrogenation reaction. The specific analysis is as follows:

[0091] The naphthalene hydrogenation reaction exhibits a significant temperature dependence: at 130℃, the naphthalene conversion rate is 0%, indicating that the activation energy of the reaction is not broken at this temperature, and the catalyst has no hydrogenation activity. With increasing reaction temperature, the hydrogenation conversion rate shows a significant upward trend, reaching 73.6% at 160℃, 92.3% at 190℃, and 99.8% at 220℃, approaching complete conversion. This proves that the catalyst of this invention can achieve efficient hydrogenation of naphthalene at 220℃, meeting the industrial process temperature requirements for the hydrogenation refining of naphthalene-based aromatics from ethylene tar. The catalyst exhibits excellent hydrogenation activity in the medium- and high-temperature range: within the temperature range of 160-220℃, the conversion rate increases significantly, indicating that the active sites of the catalyst can be fully activated within this temperature range, demonstrating significant advantages in hydrogenation reaction kinetics. This provides a highly efficient catalytic system for the deep refining of naphthalene from the light fraction of ethylene tar.

[0092] Hydrogenation tests of different aromatic hydrocarbons: Under optimal conditions of 220℃, 5MPa H2, and 6h reaction, the catalysts of Example 1, Comparative Example 1, and Comparative Example 2 were used for the hydrogenation of naphthalene, benzene, toluene, and indene. The products were analyzed by gas chromatography, and the conversion rates of each substrate were calculated, as shown in Table 3.

[0093] Table 3 Hydrogenation performance of different catalysts for different aromatic hydrocarbons

[0094]

[0095] Table 3 shows the hydrogenation conversion results of typical aromatic hydrocarbons in ethylene tar such as naphthalene, benzene, toluene, and indene in Example 1, Comparative Example 1, and Comparative Example 2 under the optimal reaction conditions (220℃, 5MPa H2, 6h). The core verification demonstrates the effect of amino acid-based coordination additives on enhancing the universality of aromatic hydrocarbon substrates in the catalyst. Specific analysis is as follows:

[0096] Amino acid coordination additives can further enhance the activity and versatility of aromatic hydrocarbon hydrogenation: In Example 1, the conversion rate of naphthalene reached 99.8% after the addition of histidine, which was significantly higher than that of Comparative Example 2 (81.7%) without amino acids; the conversion rates of benzene, toluene and indene reached 98.9%, 98.5% and 96.1% respectively, which were significantly higher than those of Comparative Example 2 (83.8%, 79.7% and 84.4%). This proves that the M-AA-NC dual anchoring interface constructed by amino acid coordination can optimize the electronic structure of the catalyst surface, reduce the activation energy of aromatic hydrocarbon hydrogenation reaction, and improve the catalytic efficiency for various aromatic hydrocarbons.

[0097] The catalyst of this invention has a high efficiency in hydrogenating various naphthalene-based aromatics, proving that the catalyst of this invention can be adapted to the hydrogenation reaction of monocyclic and bicyclic aromatics in ethylene tar. It has excellent substrate versatility and solves the technical pain point of large differences in the hydrogenation activity of traditional catalysts for different aromatics.

[0098] Traditional impregnation processes have inherent defects: Comparative Example 1 uses the traditional impregnation method, which lacks the synergistic effect of amino acid coordination and nitrogen anchoring, resulting in significantly lower conversion rates for all aromatics, with naphthalene at only 62.3% and benzene, toluene, and indene all below 60%. This further proves that the two-step sequential modification process combined with amino acid coordination modification is the key to improving the catalytic performance of aromatic hydrogenation.

Claims

1. A method for preparing a cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation, characterized in that, The steps include the following: (1) Cobalt source, indium source, amino acid coordination additive and nitrogen-rich support are added to a solvent containing organic amine. The resulting mixture is placed in a reaction vessel and subjected to hydrothermal reaction at a solvent filling rate of 20-40%. After the reaction is completed, the mixture is filtered, washed and dried to obtain a nitrogen-anchored metal precursor / support intermediate. The molar ratio of cobalt in the cobalt source to indium in the indium source is 3:

1. The amino acid coordination additive is glycine or histidine. The ratio of the total molar number of cobalt in the cobalt source and indium in the indium source to the molar number of amino acid coordination additive is 1:0.5-2. The nitrogen-rich support is g-C3N4. The mass of cobalt in the cobalt source is 0.1-2.5% of the mass of the nitrogen-rich support. The organic amine is urea or ethylenediamine. The solvent is N,N-dimethylformamide, methanol or acetone. The concentration of organic amine in the solvent containing organic amine is 0.01-0.1 mol / L. (2) The nitrogen-anchored metal precursor / support intermediate obtained in step (1) is subjected to high-temperature carbonization to obtain a cobalt indium carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation; the high-temperature carbonization is carried out in a CO / H2 / Ar mixed gas, wherein the volume percentage of CO in the CO / H2 / Ar mixed gas is 3-10% and the volume percentage of H2 is 10-30%; the temperature of the high-temperature carbonization is 380-420℃ and the time of the high-temperature carbonization is 30-90min.

2. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The cobalt source in step (1) is cobalt octacarbonyl or cobalt nitrate; the indium source is InCl3 or indium nitrate.

3. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The g-C3N4 in step (1) is prepared by the following method: weigh melamine and place it in a covered crucible. Then place the crucible in a muffle furnace and heat it to 140-160℃ at a heating rate of 1-5℃ / min. Hold it at this temperature for 20-40 min. Then heat it to 500-600℃ at a heating rate of 0.5-2℃ / min. Hold it at this temperature for 100-150 min. Then cool it naturally to room temperature and grind it through a 200-mesh sieve to obtain the g-C3N4 carrier.

4. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The ratio of the total mass of the cobalt source, indium source, amino acid coordination additive and nitrogen-rich carrier in step (1) to the volume of the solvent containing organic amine is 1 mg: 0.2-0.5 mL.

5. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The temperature of the hydrothermal reaction in step (1) is 210-240℃, and the time of the hydrothermal reaction is 4-12h.

6. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The washing in step (1) involves washing with anhydrous ethanol 2-4 times, and the drying involves drying at 50-60°C to constant weight.

7. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The flow rate of the CO / H2 / Ar mixed gas in step (2) is 20-40 mL / min.

8. The method for preparing the cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming hydrogen production and aromatic hydrocarbon hydrogenation according to claim 1, characterized in that, The heating rate in step (2) is 2-6℃ / min.

9. A cobalt-indium-carbon catalyst suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrocarbon hydrogenation, characterized in that, It is prepared by the preparation method described in any one of claims 1-8.

10. The application of the cobalt-indium-carbon catalyst of claim 9, suitable for methanol liquid-phase reforming to produce hydrogen and aromatic hydrogenation, characterized in that, It is used to catalyze the liquid-phase reforming of methanol to produce hydrogen or the hydrogenation of naphthalene from ethylene tar.

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