Ni / MoC catalyst and preparation method and application thereof

Abstract

The invention discloses a Ni / MoC catalyst as well as a preparation method and application thereof. The catalyst takes a metal carbide as a carrier and takes a transition metal as an active auxiliary agent. According to the prepared catalyst, an efficient, economical and environment-friendly'hydrogen storage-hydrogenation 'circulating system is ingeniously constructed, and a series of pain points of high-pressure danger, high cost of a noble metal catalyst, difficulty in selectivity control and the like in a traditional ANT hydrogenation process are successfully solved; and a brand-new path with industrial potential is provided for green synthesis of sym-OHA and related fine chemicals.

Description

Technical Field

[0001] This invention belongs to the field of catalyst preparation technology, specifically relating to a Ni / MoC catalyst, its preparation method, and its application. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] Symmetric octahydroanthracene (sym-OHA), as a highly symmetrical molecular platform, has demonstrated significant value in cutting-edge scientific research and the development of functional materials. Sym-OHA is a key precursor and structural unit for constructing high-performance organic semiconductor materials, particularly benzoxene derivatives. This molecule possesses both high carrier mobility and excellent solution processability, and is widely used in organic field-effect transistors (OFETs), organic solar cells (OPVs), and organic light-emitting diodes (OLEDs). Furthermore, oxidation of sym-OHA can derive a class of quinone compounds. These compounds, with their symmetrical framework and reversible redox properties, show potential applications in organic electrode material systems such as lithium / sodium-ion batteries. Therefore, the synthesis of sym-OHA is not only about the molecule itself, but also serves as a "seed" for functional materials, with profound significance for promoting development in multiple fields.

[0004] Sym-OHA primarily originates from the hydrogenation of anthracene molecules (ANT). Its hydrogenation products also include dihydroanthracene (DHA), tetrahydroanthracene (THA), asymmetric octahydroanthracene (cis / trans-OHA), and perhydroanthracene (PHA) (as shown in the figure below). ANT itself possesses a stable aromatic conjugated structure, and its hydrogenation process requires overcoming the kinetic and thermodynamic energy barriers of the aromatic ring stepwise, resulting in harsh reaction conditions. Furthermore, the hydrogenation products of ANT have similar structures, polarities, and boiling points, making the isolation of sym-OHA extremely difficult and energy-intensive. Therefore, increasing the sym-OHA content in the products by adjusting catalytic conditions is a more economical and reasonable approach, which places higher demands on the catalyst.

[0005]

[0006] Traditional ANT hydrogenation processes often rely on noble metal catalysts (such as Pt, Pd, and Ru) under high temperature, high pressure, and high-risk hydrogen environments. While these catalysts possess high catalytic activity, they suffer from high costs and are prone to deactivation due to coking or sulfur poisoning, limiting their application. Non-noble metal catalysts (such as Ni and Co) are less expensive, but they are prone to over-hydrogenation during hydrogenation, forming fully hydrogenated products, or inducing side reactions such as aromatic ring cracking, resulting in unsatisfactory selectivity for the target product sym-OHA.

[0007] In recent years, supercritical methanol has become an ideal medium for heterogeneous catalytic reactions due to its unique physicochemical properties (such as low viscosity, high diffusion coefficient, and tunable polarity). It can undergo reforming reactions with water to generate active hydrogen in situ and effectively dissolve polycyclic aromatic hydrocarbon substrates, mitigating carbon buildup on the catalyst surface. Therefore, constructing a supercritical methanol-mediated water (SMW) in-situ hydrogenation system for ANTs can further regulate the polarity and mass transfer behavior of the reaction system, promoting the generation and transfer of hydrogen species to achieve the directional conversion of ANTs. Transition metal carbides such as β-Mo2C, due to their noble metal-like electronic structure and excellent thermal stability, have shown potential to replace noble metals in methanol liquid-phase reforming and ANT hydrogenation reactions. However, the uneven acid-base distribution on the surface of β-Mo2C materials easily leads to low ANT hydrogenation levels.

[0008] In summary, it is evident that in existing technologies, it is difficult to simultaneously achieve catalyst activity and sym-OHA selectivity, and the synergistic regulatory mechanism of the reaction medium on mass transfer and hydrogen transfer processes remains unclear.

[0009] Developing a catalyst with high selectivity and high activity remains a pressing issue in the field of ANT hydrogenation technology. Summary of the Invention

[0010] To address the shortcomings of existing technologies, the purpose of this invention is to provide a Ni / MoC catalyst, its preparation method, and its applications. This invention provides a catalyst for the in-situ hydrogenation of water (ANT) mediated by supercritical methanol to prepare sym-OHA, its preparation method, and its practical application. The catalyst uses a metal carbide as a support and a transition metal as an active promoter.

[0011] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides a Ni / MoC catalyst comprising a metal carbide support and a transition metal supported on the metal carbide support as the catalyst active component.

[0012] This invention constructs the Ni / MoC catalyst and applies it to the supercritical methanol-mediated in-situ hydrogenation of water (ANT) to prepare sym-OHA, proposing more effective ratio parameters. Compared with existing catalysts used in ANT hydrogenation, the catalyst prepared in this invention ingeniously constructs a highly efficient, economical, and environmentally friendly "hydrogen storage-hydrogenation" cycle system, successfully solving a series of pain points in traditional ANT hydrogenation processes, such as high pressure hazards, high cost of precious metal catalysts, and difficulty in selectivity control. This provides a new and industrially promising route for the green synthesis of sym-OHA and related fine chemicals.

[0013] In some embodiments of the present invention, the metal in the metal carbide is Mo. Experimental comparisons of the present invention show that using MoC as a support achieves higher ANT conversion and sym-OHA selectivity than commonly used supports such as activated carbon AC or Al2O3.

[0014] In some embodiments of the present invention, the transition metal is selected from at least one of Ni, Cu, Co, and Fe.

[0015] The present invention also screened the molar ratio of transition metals in the catalyst active component to metals in the support. Compared with other ratios, the selected molar ratio conditions resulted in higher yield and selectivity for sym-OHA.

[0016] In some embodiments of the present invention, the molar ratio of the transition metal to the metal in the metal carbide support is 2.5 to 10:100.

[0017] Secondly, the present invention provides a method for preparing the Ni / MoC catalyst described in the first aspect, which adopts a programmed temperature-controlled reaction method. The preparation process is as follows: different metal hydrates are dissolved in deionized water and mixed evenly, then rotary evaporated to obtain a catalyst precursor, the catalyst precursor is calcined in air to obtain a metal oxide intermediate, and finally the metal oxide is reduced and carbonized in a two-stage heating program in a tube furnace under a hydrogen / methane atmosphere to obtain the catalyst.

[0018] Specifically, the preparation method of the Ni / MoC catalyst described in the second aspect includes the following steps: Step 1, Preparation of catalyst precursor: The transition metal salt A used to prepare the active component of the catalyst and the B used to prepare the support are dissolved in deionized water according to the corresponding metal molar ratio and stirred continuously to make them mixed evenly. Then, the mixture is obtained by rotary evaporation at 80±5℃ as the catalyst precursor. Step 2, catalyst precursor oxidation: The catalyst precursor obtained in step 1 is calcined in air at 450-550℃ for 3-5 h at a single-step heating rate of 5±0.5℃ / min to obtain a metal oxide intermediate. Step 3, reduction / carbonization to obtain catalyst: The metal oxide intermediate obtained in step 2 was reduced and carbonized in a tube furnace under a methane / hydrogen atmosphere of 19-21 vol% in a two-stage heating program to obtain catalyst. The heating program was to raise the temperature to 300±30℃ at a heating rate of 5±0.5℃ / min, and then raise the temperature from 300±30℃ to the final temperature at a heating rate of 1±0.1℃ / min and hold for 1.5-2.5 h.

[0019] Preferably, in step 1, the transition metal hydrate A and the carrier B are in a molar ratio of 2.5 to 10:100.

[0020] Preferably, in step 1, the transition metal salt is selected from the nitrate salt hydrate form of Ni, Cu, Co, and Fe.

[0021] Preferably, in step 1, the B used to prepare the metal carbide support is an ammonium salt compound of Mo.

[0022] Further, the transition metal salt A mentioned in step 1 is selected from Ni(NO3)2·6H2O, Cu(NO3)2·3H2O, Co(NO3)2·6H2O, and Fe(NO3)3·9H2O.

[0023] Furthermore, the B used to prepare the support in step 1 is selected from (NH4)6Mo7O. 24 ·4H2O.

[0024] Furthermore, in step 3, the final reduction / carbonization temperature of the metal oxide intermediate is 500~900℃. Within this temperature range, CH4 decomposes at high temperatures, providing carbon atoms for the carbonization reaction to form a metal carbide support such as MoC.

[0025] Thirdly, the present invention provides the application of the Ni / MoC catalyst described in the first aspect in the preparation of sym-OHA by supercritical methanol-mediated in-situ hydrogenation of water via ANT.

[0026] Fourthly, the present invention provides a method for preparing sym-OHA by hydrogenation of ANT based on the Ni / MoC catalyst described in the first aspect, comprising the following steps: adding ANT and the Ni / MoC catalyst described in the first aspect into a high-pressure reactor, adding deionized water and methanol as hydrogen sources into the reactor, and introducing inert gas into the reactor to increase the pressure for reaction.

[0027] The catalyst provided by this invention significantly improves process safety and economy in ANT hydrogenation reactions. By using methanol / water as a mild liquid hydrogen source, it fundamentally replaces the reliance on high-pressure pure hydrogen in traditional ANT deep hydrogenation processes, greatly reducing operational risks. Furthermore, the catalyst uses non-precious metal carbides as the support and active component, resulting in a significantly lower cost than commonly used platinum, palladium, and rhodium catalysts, demonstrating substantial economic advantages.

[0028] Furthermore, the mass ratio of ANT to methanol is 0.1 to 1:10, and the mass ratio of ANT to water is 0.1 to 1:10.

[0029] Furthermore, the mass ratio of the catalyst to ANT is 1~10:10.

[0030] Furthermore, the pressure in the high-pressure reactor is 0.5~5 MPa, the reaction temperature is 200~400℃, and the reaction time is 1~10 h.

[0031] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows: 1. This invention constructs a highly efficient hydrogen storage-hydrogenation cycle system. The prepared catalyst can ingeniously catalyze the synergistic cycle of "methanol reforming to produce hydrogen-ANT hydrogenation" in a supercritical methanol-mediated water system. Methanol and water are converted in situ to generate active hydrogen species, which are then efficiently used for the directional hydrogenation of ANT, avoiding the direct use of high-pressure hydrogen and creating an endogenous, safe, and efficient hydrogen recycling system.

[0032] 2. By introducing a second metal, such as Ni, to modulate the electronic structure of MoC, its surface hydrogen activation pathway can be optimized, enhancing the selective adsorption of specific hydrogenation intermediates and thus improving the yield of sym-OHA. Currently, there are no reports on the preparation of sym-OHA by supercritical methanol-mediated in-situ hydrogenation of water ANT using nickel-modified molybdenum carbide (Ni / MoC). The Ni / MoC catalyst provided in this invention, utilizing the synergistic effect of supercritical methanol-water dual solvents, aims to achieve efficient and highly selective hydrogenation of ANT, providing a new strategy for the green synthesis of sym-OHA.

[0033] 3. The catalyst prepared in this invention possesses excellent catalytic activity and sym-OHA selectivity. Through a temperature-controlled reduction and carbonization process, a unique structure with a metal carbide substrate and a highly dispersed transition metal as the active center was successfully constructed. This catalyst exhibits high activity for ANT hydrogenation under mild conditions and can precisely control the degree of hydrogenation, generating the target product sym-OHA with high selectivity, effectively suppressing the occurrence of over-hydrogenation or cracking side reactions. Attached Figure Description

[0034] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0035] Figure 1 The images shown are TEM and TEM-Mapping images of the catalyst 5% Ni / MoC obtained in Example 1 of this invention, where a is a TEM image and b is a TEM-Mapping image. Detailed Implementation

[0036] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0037] The present invention will be further described below with reference to the embodiments.

[0038] Example 1 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst. Figure 1 TEM and TEM-Mapping images of the obtained catalyst 5% Ni / MoC, from... Figure 1 The TEM image of a shows that the 5% Ni / MoC catalyst exhibits a nano-sized particle agglomeration morphology, forming an aggregated structure with abundant pores and a large specific surface area. Figure 1 TEM-Mapping images in section b show that C, O, Mo, and Ni are uniformly distributed in the catalyst without significant segregation, indicating that the Ni active component is highly dispersed on the MoC support. This structural feature is closely related to the catalytic role of methanol liquid-phase reforming to produce in-situ hydrogen and hydrogenation of ANT to generate sym-OHA: on the one hand, the high dispersion of Ni provides a large number of active sites, which not only promotes the breaking of CH and OH bonds in methanol liquid-phase reforming to generate in-situ hydrogen (H*), but also efficiently adsorbs and activates ANT molecules; on the other hand, the porous aggregated structure of the MoC support increases the specific surface area, which is conducive to the diffusion and mass transfer of reactants. At the same time, its hydrogen spillover effect can promote the transfer of H* generated at Ni sites to ANT, accelerating the hydrogenation process, while the uniform distribution of elements ensures the structural stability of the catalyst in the reaction, improving catalytic efficiency and service life.

[0039] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃, the stirring rate was 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0040] Example 2 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0041] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 0.5 MPa for reaction. The temperature was set to 300℃, the stirring rate was 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0042] Example 3 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0043] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 5 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0044] Example 4 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0045] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 200℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0046] Example 5 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24• 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0047] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 250℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0048] Example 6 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0049] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 350℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0050] Example 7 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 10:100, and stirred continuously to ensure uniform mixing. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 10% Ni / MoC catalyst.

[0051] 0.2 g of ANT and 0.2 g of 10% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃, the stirring rate was 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0052] Example 8 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 2.5:100, and stirred continuously to ensure homogeneity. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h, finally yielding a 2.5% Ni / MoC catalyst.

[0053] 0.2 g of ANT and 0.2 g of 2.5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃, the stirring rate was 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0054] Example 9 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24 • 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 7.5:100, and stirred continuously to ensure homogeneity. The mixture was then rotary evaporated at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced and carbonized in a tube furnace under a 20 vol% CH4 / H2 atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h. Finally, a 7.5% Ni / MoC catalyst was obtained.

[0055] 0.2 g of ANT and 0.2 g of 7.5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0056] Example 10 The transition metal hydrate Ni(NO3)2·6H2O, which is the active component of the catalyst, is combined with (NH4)6Mo7O, which is the support. 24• 4H2O was dissolved in 20 mL of deionized water at a Ni:Mo molar ratio of 5:100, and stirred continuously to ensure uniform mixing. The mixture was then obtained by rotary evaporation at 80 °C to obtain a co-crystallized mixture as a catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then subjected to a two-stage reduction and carbonization process in a tube furnace under a 20 vol% CH4 / H2 atmosphere to obtain the catalyst. The heating program was as follows: heating from 20 °C to 300 °C at a rate of 5 °C / min, and then heating from 300 °C to 700 °C at a rate of 1 °C / min and holding for 2 h to finally obtain a 5% Ni / MoC catalyst.

[0057] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 10 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. The reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0058] Comparative Example 1 The transition metal hydrate Ni(NO3)2·6H2O, serving as the active component of the catalyst, was dissolved in 20 mL of deionized water. Then, an appropriate amount of activated carbon (AC) powder was added to the solution, with a Ni to AC mass ratio of 10:100. The mixture was stirred continuously until homogeneous, and then rotary evaporated at 80 °C to obtain a co-crystallized mixture as the catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h at a single-step heating rate of 5 °C / min under an inert atmosphere to obtain a metal oxide intermediate. The metal oxide was then reduced in a tube furnace under a 10 vol% H2 / Ar atmosphere using a temperature-programmed reduction method to obtain the catalyst. The temperature program was as follows: increasing the temperature from 20 °C to 350 °C at a rate of 5 °C / min and holding for 1.5 h, then increasing the temperature from 350 °C to 550 °C at a rate of 5 °C / min and holding for 3 h, finally yielding a 10 wt% Ni / AC catalyst.

[0059] 0.2 g of ANT and 0.2 g of 10 wt% Ni / AC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0060] Comparative Example 2 The transition metal hydrate Ni(NO3)2·6H2O, which serves as the active component of the catalyst, was dissolved in 20 mL of deionized water. Then, an appropriate amount of Al2O3 powder was added to the solution, with a Ni to Al2O3 mass ratio of 10:100. The mixture was stirred continuously until homogeneous, and then rotary evaporated at 80 °C to obtain a co-crystallized mixture as the catalyst precursor. The catalyst precursor was transferred to a muffle furnace and calcined at 500 °C for 4 h in air at a single-step heating rate of 5 °C / min to obtain a metal oxide intermediate. The metal oxide was then reduced in a tube furnace under a 10 vol% H2 / Ar atmosphere using a two-stage heating program to obtain the catalyst. The heating program was as follows: heating from 20 °C to 350 °C at a rate of 5 °C / min and holding for 1.5 h, followed by heating from 350 °C to 550 °C at a rate of 5 °C / min and holding for 3 h, ultimately yielding a 10 wt% Ni / Al2O3 catalyst.

[0061] 0.2 g of ANT and 0.2 g of 10 wt% Ni / Al2O3 catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃, the stirring rate was 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0062] Comparative Example 3 Copper nitrate trihydrate (Cu(NO3)2·3H2O) was used as an active metal precursor and dissolved in 20 mL of deionized water to form a solution. Ammonium molybdate ((NH4)6Mo7O) was then added to this solution. 24 The mixture was prepared by stirring ·4H2O, with the molar ratio of copper to molybdenum controlled at 5:100 (corresponding to a stoichiometric ratio of 5% Cu / MoC). After continuous stirring to ensure uniform mixing of all components, the slurry was dried by rotary evaporation at 80°C to obtain a composite precursor. This precursor was placed in a muffle furnace and calcined at 500°C for 4 h in air at a rate of 5°C / min to form a mixed oxide intermediate of copper oxide and molybdenum oxide. Subsequently, this intermediate was transferred to a tube furnace and subjected to programmed carbonization and reduction in a 20 vol% CH4 / H2 reducing atmosphere: first, the temperature was increased from room temperature to 300°C at a rate of 5°C / min, then slowly increased to 700°C at a rate of 1°C / min and held for 2 h, so that the molybdenum oxide was carbonized to molybdenum carbide (MoC), while the copper oxide was reduced to metallic copper, ultimately obtaining the target catalyst 5% Cu / MoC.

[0063] 0.2 g of ANT and 0.2 g of 5% Cu / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0064] Comparative Example 4 Ferric nitrate nonahydrate (Fe(NO3)3·9H3O) was used as an active metal precursor and dissolved in 20 mL of deionized water to obtain a clear solution. Ammonium molybdate ((NH4)6Mo7O) was then added to this solution. 24 The slurry, containing iron and molybdenum in a controlled molar ratio of 5:100 (corresponding to a stoichiometric ratio of 5% Fe / MoC), was stirred continuously to ensure thorough mixing. The slurry was then rotary dried at 80°C to obtain the composite precursor. Subsequently, the precursor was placed in a muffle furnace and calcined at 500°C in air at a programmed heating rate of 5°C / min for 4 h to form a mixed oxide intermediate of iron oxide and molybdenum oxide. Finally, the intermediate was transferred to a tube furnace and subjected to a programmed reduction in a 20 vol% CH4 / H2 reducing atmosphere: first, the temperature was increased from room temperature to 300°C at 5°C / min, then slowly increased to 700°C at a rate of 1°C / min, and held at this temperature for 2 h. This process ultimately yielded the target product, the 5% Fe / MoC catalyst.

[0065] 0.2 g of ANT and 0.2 g of 5% Fe / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0066] Comparative Example 5 Cobalt nitrate hexahydrate (Co(NO3)2·6H2O) was used as an active metal precursor and dissolved in 20 mL of deionized water to obtain a clear solution. Ammonium molybdate ((NH4)6Mo7O) was then added to this solution. 24The mixture was prepared by stirring ·4H₂O, with the molar ratio of cobalt to molybdenum controlled at 5:100 (corresponding to the stoichiometry of 5% Co / MoC). After thorough mixing of all components, the slurry was dried by rotary evaporation at 80°C to obtain the composite precursor. Subsequently, the precursor was placed in a muffle furnace and calcined at 500°C in air at a programmed heating rate of 5°C / min for 4 h to form a mixed oxide intermediate of cobalt oxide and molybdenum oxide. Finally, the intermediate was transferred to a tube furnace and subjected to programmed reduction in a 20 vol% CH₄ / H₂ reducing atmosphere: first, the temperature was increased from room temperature to 300°C at 5°C / min, then slowly increased to 700°C at a rate of 1°C / min, and held at this temperature for 2 h. This process ultimately yielded the target product, the 5% Co / MoC catalyst.

[0067] 0.2 g of ANT and 0.2 g of 5% Co / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added to the reactor as hydrogen sources. N2 was introduced into the reactor to increase the pressure to 3 MPa for reaction. The temperature was set to 300℃ and the stirring rate was 400 rpm. After the reaction was completed for 10 h, the resulting solution was characterized and calculated. The ANT conversion rate and the selectivity of hydrogenation products are listed in Table 1.

[0068] Table 1. Conversion rate and selectivity results for each embodiment and comparative example.

[0069] Analysis of the reaction evaluation data in Table 1 shows that the 5% Ni / MoC catalyst prepared in this invention exhibits excellent catalytic performance in the supercritical methanol-mediated in-situ hydrogenation of ANT to prepare sym-OHA. Under optimal reaction conditions (Example 1), the conversion of ANT reached 100%, and the selectivity of sym-OHA was as high as 99.99%, demonstrating the excellent activity and product orientation of the catalyst. Although the conversion of ANT and the selectivity of sym-OHA fluctuated somewhat by adjusting reaction conditions such as temperature, pressure, reaction time, and alcohol / water ratio, they generally maintained a high level of 73.18%-100% conversion and 65.22%-98.43% selectivity, proving that the catalytic system has good and stable performance over a wide operating window. Furthermore, by adjusting the molar ratio of Ni to Mo in the catalyst, it was found that the catalyst performance is relatively sensitive to the Ni:Mo ratio. Within the loading range of this study, 5% Ni / MoC exhibited relatively optimal overall performance, indicating that this ratio may be an optimal balance point for active site distribution, support interaction, and carbonization degree. Compared to traditional Ni-based catalysts supported on biomass activated carbon (AC) and Al2O3, the Ni / MoC catalyst exhibits significantly improved conversion and selectivity under the same conditions. This highlights the unique catalytic effect of the MoC support in the methanol-water system and its potential synergistic effect with Ni metal. In summary, the Ni / MoC catalyst provided by this invention can efficiently and selectively catalyze the hydrogenation of ANT to sym-OHA in a methanol-water mixed solvent, demonstrating its application potential in heterogeneous catalytic hydrogenation, especially in the deep hydrogenation of polycyclic aromatic hydrocarbons.

[0070] Application Example 1 The 5% Ni / MoC prepared in Example 1 was applied to a supercritical methanol-mediated in-situ hydrogenation cycle experiment of water ANT.

[0071] 0.2 g of ANT and 0.2 g of 5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added as hydrogen sources. N2 was introduced into the reactor to pressurize it to 3 MPa for reaction. The temperature was set at 300℃, the stirring rate at 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and the ANT conversion and sym-OHA selectivity are listed in Table 1. The catalyst was used to conduct five reactions to evaluate the cyclic reaction capability of the catalyst in Example 1.

[0072] Liquid products were analyzed using a Shimadzu QP2010 Plus GC-MS system. An HP 190915-433 capillary column was selected for the assay, and the initial temperature was 80°C. o C, hold for two minutes, then at 5o C / min increased to 260 o C, finally 10 o The speed increased to 280 C / min o C, Inlet temperature set to 300 o C; High-purity helium was used as the carrier gas, with a flow rate set at 2.4 mL / min, a split ratio of 5.0:1, an injection volume of 0.2 μL, and a solvent delay of 3 min; the ion source was an EI source with an electron impact energy of 70 eV, and the m / z measurement range was 30–500. Qualitative and quantitative analyses were performed using the NIST 5 mass spectrum standard library after the tests.

[0073] Under the same reaction conditions, the ANT conversion and sym-OHA selectivity of the 5% Ni / MoC catalyst prepared in Example 1 in the supercritical methanol-mediated in-situ hydrogenation cycle of water ANT are shown in Table 2.

[0074] Table 2 Results of in-situ hydrogenation cycle experiment of 5% Ni / MoC in supercritical methanol-mediated water ANT

[0075] As can be seen from the cyclic experiment results of Application Example 1, the 5% Ni / MoC catalyst prepared in this invention exhibits extremely high catalytic activity and structural stability.

[0076] Application Example 2 The 10% Ni / MoC prepared in Example 7 was applied to a supercritical methanol-mediated in-situ hydrogenation cycle experiment of water ANT.

[0077] 0.2 g of ANT and 0.2 g of 10% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added as hydrogen sources. N2 was introduced into the reactor to pressurize it to 3 MPa for reaction. The temperature was set at 300℃, the stirring rate at 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and calculated. The ANT conversion rate and sym-OHA selectivity are listed in Table 3. The catalyst was used to conduct five reactions to evaluate the cyclic reaction capability of the catalyst in Example 7.

[0078] Under the same reaction conditions, the ANT conversion and sym-OHA selectivity of the 10% Ni / MoC catalyst prepared in Example 7 in the supercritical methanol-mediated in-situ hydrogenation cycle of water ANT are shown in Table 3.

[0079] Table 3 Results of in-situ hydrogenation cycle experiment of 10% Ni / MoC in supercritical methanol-mediated water ANT

[0080] Application Example 3 The 2.5% Ni / MoC prepared in Example 8 was applied to a supercritical methanol-mediated in-situ hydrogenation cycle experiment of water ANT.

[0081] 0.2 g of ANT and 0.2 g of 2.5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added as a hydrogen source. N2 was introduced into the reactor to pressurize it to 3 MPa for reaction. The temperature was set at 300℃, the stirring rate at 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and the conversion and selectivity are listed in Table 4. The catalyst was then used to conduct five reactions to evaluate the cyclic reaction capability of the catalyst in Example 8.

[0082] Table 4 Results of in-situ hydrogenation cycle experiment of 2.5% Ni / MoC in supercritical methanol-mediated water ANT

[0083] Application Example 4 The 7.5% Ni / MoC prepared in Example 9 was applied to a supercritical methanol-mediated in-situ hydrogenation cycle experiment of water ANT.

[0084] 0.2 g of ANT and 0.2 g of 7.5% Ni / MoC catalyst were added to a high-pressure reactor. 4 mL of deionized water and 10 mL of methanol were added as hydrogen sources. N2 was introduced into the reactor to pressurize it to 3 MPa for reaction. The temperature was set at 300℃, the stirring rate at 400 rpm, and the reaction was completed after 10 h. The resulting solution was characterized and the conversion and selectivity are listed in Table 5. The catalyst was used to conduct five reactions to evaluate the cyclic reaction capability of the catalyst in Example 9.

[0085] Table 5 Results of in-situ hydrogenation cycle experiment of 7.5% Ni / MoC in supercritical methanol-mediated water ANT

[0086] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A Ni / MoC catalyst, characterized in that, It includes a metal carbide support and a transition metal supported on the metal carbide support as the active component of the catalyst; The metal carbide is Mo; The transition metal is selected from at least one of Ni, Cu, Co, and Fe.

2. The Ni / MoC catalyst according to claim 1, characterized in that, The molar ratio of the transition metal to the metal carbide support is 2.5~10:

100.

3. A method for preparing a Ni / MoC catalyst, characterized in that, Includes the following steps: Step 1, Preparation of catalyst precursor: The transition metal salt A used to prepare the active component of the catalyst and the B used to prepare the support are dissolved in deionized water according to the corresponding metal molar ratio and stirred continuously to make them mixed evenly. Then, the mixture is obtained by rotary evaporation at 80±5℃ as the catalyst precursor. Step 2, catalyst precursor oxidation: The catalyst precursor obtained in step 1 is calcined in air at 450-550℃ for 3-5 h at a single-step heating rate of 5±0.5℃ / min to obtain a metal oxide intermediate. Step 3, reduction / carbonization to obtain catalyst: The metal oxide intermediate obtained in step 2 was reduced and carbonized in a tube furnace under a methane / hydrogen atmosphere of 19-21 vol% in a two-stage heating program to obtain catalyst. The heating program was to raise the temperature to 300±30℃ at a heating rate of 5±0.5℃ / min, and then raise the temperature from 300±30℃ to the final temperature at a heating rate of 1±0.1℃ / min and hold for 1.5-2.5 h.

4. The method for preparing the Ni / MoC catalyst according to claim 3, characterized in that, In step 1, the transition metal hydrate A and the carrier B are in a molar ratio of 2.5~10:

100.

5. The method for preparing the Ni / MoC catalyst according to claim 3, characterized in that, In step 1, the transition metal salt is selected from the nitrate salt hydrate form of Ni, Cu, Co, and Fe; The B used to prepare the metal carbide support is an ammonium salt compound of Mo.

6. The method for preparing the Ni / MoC catalyst according to claim 3, characterized in that, The transition metal salt A mentioned in step 1 is selected from Ni(NO3)2·6H2O, Cu(NO3)2·3H2O, Co(NO3)2·6H2O, and Fe(NO3)3·9H2O; The B used to prepare the support is selected from (NH4)6Mo7O. 24 ·4H2O.

7. The method for preparing the Ni / MoC catalyst according to claim 3, characterized in that, In step 3, the final reduction / carbonization temperature of the metal oxide intermediate is 500~900℃.

8. The application of the Ni / MoC catalyst according to claim 1 in the catalytic hydrogenation reaction of ANT.

9. The application of ANT hydrogenation based on Ni / MoC catalyst to prepare sym-OHA, characterized in that, The process includes the following steps: ANT and the Ni / MoC catalyst described in claim 1 are added to a high-pressure reactor; deionized water and methanol are added to the reactor as hydrogen sources; and N2 is introduced into the reactor to increase the pressure and carry out the reaction.

10. The application of the Ni / MoC catalyst-based ANT hydrogenation to prepare sym-OHA according to claim 9, characterized in that, The N2 pressure in the high-pressure reactor is 0.5~5 MPa, the reaction temperature is 200~400℃, and the reaction time is 1~10 h.

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