Ni-molybdenum oxide / nb2o5 nanocomposite catalyst, and preparation method and application thereof
By preparing Ni-molybdenum oxide/Nb2O5 nanocomposite catalysts and utilizing the hydrogen source in the lignin structure for self-hydrogen transfer catalysis, the problems of high corrosivity and high cost of traditional catalysts were solved, and the efficient conversion of guaiacol to catechol was achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENYANG AEROSPACE UNIVERSITY
- Filing Date
- 2025-06-12
- Publication Date
- 2026-06-19
Smart Images
Figure CN120679551B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of catalyst technology, and in particular to a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, its preparation method, and its application. Background Technology
[0002] Lignin, as the only sustainable source of aromatic compounds, has promising prospects for industrial applications. However, its stable and complex structure reduces the potential and reaction controllability of upgrading lignin into viable and valuable products. Therefore, to further achieve efficient utilization of lignin, it is usually converted into platform compounds such as guaiacol and then directed to downstream products. Guaiacol, as a typical phenolic compound, can be upgraded through chemical synthesis and catalytic conversion to obtain high-value products such as ethers and phenols. Catechol, as one of the high-value products from the catalytic conversion of guaiacol, can be used as an important chemical / chemical intermediate in the synthesis of vanillin, antioxidants, and pesticides, as well as as a precursor for epoxy resin curing agents or polyamide monomers in the preparation of high-temperature resistant materials, demonstrating enormous economic potential.
[0003] O-demethylation (ODM) is a key reaction in the conversion of guaiacol to catechol. Traditional inorganic acid catalysis mediating this reaction is relatively mature, but aqueous inorganic acids are often highly corrosive, resulting in harsh reaction conditions and irreversible damage to the reactor. Therefore, heterogeneous liquid-phase ODM systems for guaiacol have attracted attention. The core of this system lies in the catalyst and high H2 pressure. Noble metal-based catalysts have shown excellent catalytic performance, but their market application is hindered by scarcity and high cost. Simultaneously, the safety and economics of external hydrogen sources during production and storage also limit the development of this process. Therefore, designing a highly efficient catalyst with a non-noble metal as the catalytic active center and good CO bond breaking ability, utilizing the potential hydrogen source (-OCH3) in the lignin structure and a green solvent for hydrogen supply, is of great significance for realizing the self-hydrogen transfer catalytic conversion of lignin and its model compounds to catechol. Summary of the Invention
[0004] The purpose of this invention is to provide a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, its preparation method and application, which can achieve high-value conversion of guaiacol to catechol under mild reaction conditions without exogenous hydrogen.
[0005] To achieve the above-mentioned objectives, the present invention provides the following technical solution:
[0006] This invention provides a method for preparing a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, comprising the following steps:
[0007] The nickel source and molybdenum source are mixed with water to obtain a nickel-molybdenum bimetallic salt solution;
[0008] Niobium pentoxide was mixed with the nickel-molybdenum bimetallic salt solution, and the resulting composite suspension was sequentially heated, dried and calcined to obtain a catalyst precursor.
[0009] The catalyst precursor was reduced under a reducing atmosphere to obtain a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst.
[0010] Preferably, the nickel source includes nickel nitrate or nickel chloride; the molybdenum source includes ammonium molybdate or sodium molybdate.
[0011] Preferably, the molar ratio of the nickel source, molybdenum source and water is 0-0.05:0-0.004:3.33, and the molar number of both the nickel source and the molybdenum source is not 0.
[0012] Preferably, the molar ratio of niobium pentoxide to the nickel source and the molybdenum source is 0.0376:0~0.05:0~0.04, and the molar number of both the nickel source and the molybdenum source is not 0;
[0013] The heat treatment is carried out at a temperature of 60–80°C for 4–6 hours; the heat treatment is carried out under stirring conditions, the stirring speed is 200–400 rpm, and the time is 4–6 hours.
[0014] The drying temperature is 90–120°C, and the time is 12–24 hours;
[0015] The calcination temperature is 400–600℃, and the time is 3–5 hours.
[0016] Preferably, the reducing atmosphere is a hydrogen atmosphere, and the flow rate of the hydrogen is 80-100 mL / min;
[0017] The reduction reaction is carried out at a temperature of 500–600°C for 1–3 hours.
[0018] This invention provides a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst prepared by the preparation method described above.
[0019] Preferably, in the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, the theoretical loading of Ni element is 8-20 wt%, and the theoretical loading of molybdenum oxide is 8-20 wt%.
[0020] This invention provides the application of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst described above in the catalytic hydrothermal conversion of guaiacol to catechol.
[0021] Preferably, the method of application includes: mixing Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol and water, and carrying out a hydrothermal reaction to obtain catechol.
[0022] Preferably, the ratio of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol, and water is 0.3-0.7 g: 5 mL: 50 mL; the hydrothermal reaction conditions include: a reaction temperature of 280-320°C, a reaction time of 1-3 h, and a reaction vessel rotation speed of 300-400 rpm.
[0023] This invention provides a method for preparing a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst. Ni and Mo are co-supported on an Nb2O5 support. Ni exhibits high catalytic activity in hydrogenation reactions; Mo possesses good CO bond breaking ability and hydrogenation-assisting ability; niobium pentoxide serves as the catalyst support, and its abundant oxygen vacancies effectively lower the dissociation barrier of water molecules, significantly promoting the hydrogen evolution process. Simultaneously, this invention supports transition metals nickel and molybdenum oxide on the Nb2O5 support surface, forming a strong metal-support electronic interaction (SMSI effect), improving anti-sintering ability and catalytic activity, demonstrating significant advantages in hydrothermal catalytic systems.
[0024] The preparation method of this invention is simple and the raw material cost is low. First, the catalyst precursor is prepared by excess impregnation method, and then the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst is prepared by hydrogen reduction treatment. The active component in the catalyst is uniformly loaded and has excellent self-hydrothermal catalytic performance.
[0025] The Ni-molybdenum oxide / Nb2O5 supported catalyst prepared by this invention via a one-pot method can activate the O-demethylation reaction (ODM), Ni promotes the hydrogenation process of guaiacol, and molybdenum oxide (MoO) x This invention provides oxygen uptake capacity and assists in-situ hydrogenation. Simultaneously, the Nb₂O₅ support surface possesses both Brønsted (B) and Lewis (L) acid sites, minimizing the dissociation energy of the CO bond, promoting CO bond cleavage, and allowing the reaction to proceed in the forward direction. This enables the high-value conversion of guaiacol to catechol under mild reaction conditions without exogenous hydrogen. Therefore, this invention provides a novel Ni-molybdenum oxide / Nb₂O₅ nanocomposite catalyst for the one-pot preparation of catechol from guaiacol in a hydrogen-rich environment. Attached Figure Description
[0026] Figure 1 5Ni-5MoO prepared in Example 1 xScanning electron microscope (SEM) images of the 10Ni / Nb2O5 nanocomposite catalyst in Comparative Example 1 and 10Mo / Nb2O5 in Comparative Example 2, (a) is the SEM characterization of Ni / Nb2O5 in Comparative Example 1 at a 200 nm scale; (b) is the SEM image of 5Ni-5MoO5 in Example 1. x (c) is the scanning electron microscope characterization of 10Mo / Nb2O5 at a 200 nm scale; (d) is the scanning electron microscope characterization of 10Mo / Nb2O5 at a 200 nm scale in Comparative Example 2.
[0027] Figure 2 The 10Ni / Nb2O5 in Comparative Example 1, the 10Mo / Nb2O5 in Comparative Example 2, and the 5Ni-5MoO in Example 1 are all examples of this. x A schematic diagram of the temperature-progression reduction test results for / Nb2O5 (Temperature, Intensity).
[0028] Figure 3 For the 10Ni / Nb2O5 metal nanocatalyst in Comparative Example 1 and the 5Ni-5MoO in Example 1 x XRD characterization analysis of / Nb2O5 nanocomposite catalyst and 10Mo / Nb2O5 metal nanocatalyst and niobium pentoxide raw material in Comparative Example 2;
[0029] Figure 4 The graph shows the results of the content of catechol prepared by hydrothermal conversion of guaiacol by hydrogen using different catalysts in Application Example 1 and Comparative Examples 1-3. Detailed Implementation
[0030] In this invention, unless otherwise specified, the raw materials or reagents required for preparation are all commercially available products well known to those skilled in the art.
[0031] This invention provides a method for preparing a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, comprising the following steps:
[0032] The nickel source and molybdenum source are mixed with water to obtain a nickel-molybdenum bimetallic salt solution;
[0033] Niobium pentoxide was mixed with the nickel-molybdenum bimetallic salt solution, and the resulting composite suspension was sequentially heated, dried and calcined to obtain a catalyst precursor.
[0034] The catalyst precursor was reduced under a reducing atmosphere to obtain a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst.
[0035] In this invention, a nickel source and a molybdenum source are dissolved in deionized water to obtain a nickel-molybdenum bimetallic salt solution.
[0036] In this invention, the nickel source preferably includes nickel nitrate or nickel chloride, more preferably nickel nitrate hexahydrate; the molybdenum source preferably includes ammonium molybdate or sodium molybdate, more preferably ammonium molybdate.
[0037] In this invention, the molar ratio of the nickel source, molybdenum source and water is preferably 0-0.05:0-0.004:3.33, and the molar number of both the nickel source and the molybdenum source is not 0. More preferably, it is 0-0.04259:0-0.00372:3.33, and even more preferably, it is 0.01067:0.00231:3.33.
[0038] In this invention, niobium pentoxide support is preferably added to a nickel-molybdenum bimetallic salt solution to obtain a composite suspension; the composite suspension is then subjected to heating, drying and calcination in sequence to obtain a Nb2O5 catalyst precursor supported on NiO-molybdenum oxide.
[0039] In this invention, the molar ratio of niobium pentoxide to the nickel source and the molybdenum source is preferably 0.0376:0~0.05:0~0.04, and the molar number of both the nickel source and the molybdenum source is not 0. More preferably, it is 0.0376:0~0.0426:0~0.02606, and even more preferably, it is 0.0376:0.01617:0.00231.
[0040] In this invention, the temperature of the heat treatment is preferably 60–80°C, more preferably 65–75°C, and even more preferably 70°C; the time is preferably 4–6 hours, more preferably 4.5–5.5 hours, and even more preferably 5 hours; the heat treatment is preferably carried out under water bath and stirring conditions, the stirring speed is preferably 200–400 rpm, more preferably 250–350 rpm, and even more preferably 300 rpm; the time is preferably 4–6 hours, more preferably 4.5–5.5 hours, and even more preferably 5 hours. This invention improves the solubility of metal salts through heating and stirring.
[0041] In this invention, the drying temperature is preferably 90-120°C, more preferably 100-110°C, and even more preferably 105°C; the drying time is preferably 12-24 hours, more preferably 14-18 hours, and even more preferably 16 hours.
[0042] In this invention, the calcination temperature is preferably 400-600℃, more preferably 450-550℃, and even more preferably 500℃; the calcination time is preferably 3-5h, more preferably 3.5-4.5h, and even more preferably 4h.
[0043] In this invention, the reducing atmosphere is preferably a hydrogen atmosphere, and the flow rate of the hydrogen is preferably 80-100 mL / min, more preferably 85-95 mL / min, and even more preferably 90 mL / min.
[0044] In this invention, the temperature of the reduction reaction is preferably 500-600°C, more preferably 530-570°C, and even more preferably 544°C; the time is preferably 1-3 hours, more preferably 1.5-2.5 hours, and even more preferably 2 hours.
[0045] This invention provides a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst prepared by the preparation method described above.
[0046] In this invention, the theoretical loading of Ni element in the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst is preferably 8-20 wt%, and the theoretical loading of molybdenum oxide is preferably 8-20 wt%.
[0047] This invention provides the application of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst described above in the catalytic hydrothermal conversion of guaiacol to catechol.
[0048] In this invention, the preferred method of application includes: mixing Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol and water, and carrying out a hydrothermal reaction to obtain catechol.
[0049] In this invention, the preferred ratio of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol, and water is 0.3-0.7g:5mL:50mL, more preferably 0.45-0.55g:5mL:50mL, and even more preferably 0.5g:5mL:50mL.
[0050] In this invention, the hydrothermal reaction conditions preferably include: a reaction temperature of 280–320°C, more preferably 290–310°C, and even more preferably 300°C; a reaction time of 1–3 h, more preferably 1.5–2.5 h, and even more preferably 2 h; and a reaction vessel rotation speed of 300–400 rpm, more preferably 330–370 rpm, and even more preferably 350 rpm.
[0051] The specific embodiments of the present invention are described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention. Unless otherwise specified, the experimental methods described in the embodiments of the present invention are conventional methods.
[0052] Unless otherwise specified, the experimental and testing methods described below are conventional methods; unless otherwise specified, the reagents and raw materials described below are commercially available.
[0053] Example 1
[0054] 0.01067 mol nickel nitrate hexahydrate and 0.00231 mol ammonium molybdate were dissolved in 3.33 mol deionized water to obtain a nickel-molybdenum bimetallic salt solution;
[0055] 10 g of niobium pentoxide support was added to a nickel-molybdenum bimetallic salt solution to obtain a composite suspension. The resulting composite suspension was magnetically stirred in a water bath at 70 °C for 5 h at a speed of 300 rpm, then dried in an oven at 105 °C for 16 h, and finally calcined in a muffle furnace at 500 °C for 4 h to obtain supported NiO-MoO. x Nb2O5 catalyst precursor;
[0056] The obtained catalyst precursor was reduced under a hydrogen atmosphere. The hydrogen flow rate was set at 90 mL / min, the reduction temperature at 544 °C, and the time at 2 h to obtain a nanocomposite catalyst, denoted as 5Ni-5MoO. x / Nb2O5.
[0057] Comparative Example 1
[0058] Keeping other conditions unchanged in Example 1, the molar amounts of nickel nitrate hexahydrate, ammonium molybdate, and deionized water were modified to 0.04259 mol, 0 mol, and 3.33 mol, respectively, and the reduction reaction temperature was set to 434 °C, resulting in 10Ni / Nb2O5 metal nanoparticles.
[0059] Comparative Example 2
[0060] Keeping other conditions unchanged in Example 1, the molar amounts of nickel nitrate hexahydrate, ammonium molybdate, and deionized water were modified to 0 mol, 0.00372 mol, and 3.33 mol, respectively, and the reduction reaction temperature was set to 653 °C, resulting in 10Mo / Nb2O5 metal nanoparticles.
[0061] Comparative Example 3
[0062] By keeping other conditions unchanged in Example 1 and modifying the temperature of the reduction reaction to 748°C, 5Ni-5Mo / Nb2O5 metal nanoparticles were obtained.
[0063] Characterization and performance testing
[0064] 1) The 5Ni-5MoO prepared in Example 1 x The / Nb2O5 nanocomposite catalyst was characterized by scanning electron microscopy with 10Ni / Nb2O5 in Comparative Example 1 and 10Mo / Nb2O5 in Comparative Example 2, as follows: Figure 1 As shown; Figure 1 In the image, (a) is a scanning electron microscope (SEM) image of Ni / Nb₂O₅ in Comparative Example 1 at a 200 nm scale; (b) is a scanning electron microscope (SEM) image of 5Ni-5MoO₅ in Example 1. x(c) is a scanning electron microscope (SEM) image of 10Mo / Nb2O5 at a 200 nm scale; (d) is a scanning electron microscope (SEM) image of 10Mo / Nb2O5 in Comparative Example 2 at a 200 nm scale; Figure 1 As can be seen, Ni metal is distributed in a granular, dispersed manner, while Mo metal is arranged in a blocky, non-uniform, interlocking pattern. The 5Ni-5MoO composition, which contains a bimetallic component, exhibits this characteristic. x The / Nb2O5 nanocomposite catalyst exhibits characteristics such as reduced particulate fragments and smaller block particle size, resulting in a more uniform overall loading.
[0065] 2) The 10Ni / Nb2O5 in Comparative Example 1, the 10Mo / Nb2O5 in Comparative Example 2, and the 5Ni-5MoO5 in Example 1 were compared. x Temperature-programmed reduction tests were performed on Nb₂O₅ and the results of the temperature-programmed reduction tests on different materials are shown in the following diagram. Figure 2 As shown. From Figure 2 As can be seen, the 10Ni / Nb2O5 metal nanocatalyst exhibits a NiO reduction peak at 350–440 °C; while the 10Mo / Nb2O5 metal nanocatalyst exhibits a MoO reduction peak at approximately 640–670 °C. x The reduction peak of 5Ni-5MoO x The surface redox peaks of the 5Ni / Nb₂O₅ nanocomposite catalyst are similar to those of the 10Ni / Nb₂O₅ metal nanocatalyst near 470–550 °C, and similar to those of the 10Mo / Nb₂O₅ metal nanocatalyst near 725–775 °C. Therefore, to preserve the oxidation state of Mo, a reduction at 544 °C is chosen to obtain 5Ni-5MoO₅. x / Nb2O5 nanocomposite catalyst.
[0066] 3) The 10Ni / Nb2O5 metal nanocatalyst from Comparative Example 1 and the 5Ni-5MoO from Example 1 were used. x The 10Mo / Nb2O5 nanocomposite catalyst and the 10Mo / Nb2O5 metal nanocatalyst in Comparative Example 2, as well as the niobium pentoxide raw material, were characterized by XRD. The XRD characterization analysis diagrams are shown below. Figure 3 As shown; Figure 3 According to the standard card, the diffraction peaks of the Nb₂O₅ support reveal the presence of two oxide crystalline phases: Nb₂O₅ (2θ = 22.6°, 28.3°) and NbO₂ (2θ = 23.8°), indicating that Nb₂O₅ has two oxide crystalline phases. 5+ During the reduction process, it can be partially reduced to Nb. 4+ Therefore, the catalyst support exists in the form of NbO. x It can provide some oxygen vacancies, and the position and intensity are basically stable and consistent, indicating that 5Ni-5MoO xThe basic structure of the niobium pentoxide support remained intact and highly stable during the preparation of the Nb₂O₅ nanocomposite catalyst; the significant diffraction peaks at 36.6° and 40.5° corresponded to MoO₂ and Mo₄O₅, respectively. 11 The reflective crystal planes of the phases indicate that Mo remains in the oxide state during the preparation process, resulting in better catalytic effect; while the presence of Ni2Mo3O8 (2θ=25.5°, 36.5°) and NiMoO4 (2θ=25.5°, 36.5°) phases indicates that there is a certain interaction between the bimetals during the preparation process.
[0067] 4) The 5Ni-5MoO prepared in Example 1 x The 10Ni / Nb2O5 and 10Mo / Nb2O5 nanocomposite catalysts prepared in Comparative Examples 1 and 2 were characterized by ICP-OES, and the property parameters of the different nanocomposite catalysts were obtained, as shown in Table 1.
[0068] Table 1. Property parameters of different nanocomposite catalysts
[0069] Case Ni (wt%) <![CDATA[MoO x (wt%)]]> Example 1 8.91 8.27 Comparative Example 1 19.15 - Comparative Example 2 - 13.816
[0070] As can be seen from Table 1, 5Ni-5MoO x The / Nb2O5 nanocomposite catalyst showed good loading performance during preparation, with an actual loading (Ni and MoO) of [missing information]. x The ratio of the total loading (17.18 wt%) to the theoretical loading (20 wt%) was 85.9%, indicating that Ni and Mo metals did not significantly lose or volatilize during the loading process, and the loading efficiency was high, providing a basis for catalytic performance.
[0071] Application Example 1
[0072] In a hydrothermal reactor, 0.5 g of the 5Ni-5MoO prepared in Example 1 was added. x The Nb2O5 nanocomposite catalyst, 5 mL of guaiacol, and 50 mL of water were mixed and subjected to a hydrothermal reaction at 300℃. The reaction vessel was rotated at 350 rpm and the hydrothermal reaction time was set to 120 min. The content and selectivity of catechol in the product were tested.
[0073] Application Comparative Example 1
[0074] In Application Example 1, all other conditions remained unchanged, except that the 5Ni-5MoO prepared in Example 1 was not added. x / Nb2O5 nanocomposite catalyst, the content of catechol in the product was tested.
[0075] Application Comparative Example 2
[0076] Keeping other conditions unchanged in Application Example 1, the 5Ni-5MoO prepared in Example 1 was used... x The / Nb2O5 nanocomposite catalyst was replaced with the 10Ni / Nb2O5 metal nanocatalyst in Comparative Example 1, and the content of catechol in the product was tested.
[0077] Application Comparative Example 3
[0078] Keeping other conditions unchanged in Application Example 1, the 5Ni-5MoO prepared in Example 1 was used... x The / Nb2O5 nanocomposite catalyst was replaced with 10Mo / Nb2O5 in Comparative Example 2, and the content of catechol in the product was tested.
[0079] Application Comparative Example 4
[0080] Keeping other conditions unchanged in Application Example 1, the 5Ni-5MoO prepared in Example 1 was used... x The Nb2O5 nanocomposite catalyst was replaced with 5Ni-5Mo / Nb2O5 in Comparative Example 3, and the selectivity of catechol in the product was semi-quantitatively tested by GC-MS peak fractionation.
[0081] The results of GC-MS internal standard method for quantitative determination of catechol content in Application Example 1 and Comparative Examples 1-3 are recorded in Table 2. For specific numerical comparisons, see [link to table]. Figure 4 .
[0082] Table 2. Test results of catechol content in the products of Application Example 1 and Comparative Examples 1-3
[0083] Application Cases Catechol content (mg / g) Application Example 1 26.628 Application Comparative Example 1 8.439 Application Comparative Example 2 10.946 Application Comparative Example 3 23.961
[0084] Table 2 shows that at a temperature of 300℃, 5Ni-5MoO x The Nb₂O₅ nanocomposite catalyst enabled the hydrothermal conversion of guaiacol to catechol to a content of 26.628 mg / g, an increase of 18.189 mg / g compared to the uncatalyzed condition; compared to the 10Ni / Nb₂O₅ metal nanocatalyst and the 10Mo / Nb₂O₅ metal nanocatalyst, the increases were 15.682 mg / g and 2.667 mg / g, respectively, indicating that the 5Ni-5MoO₅ nanocomposite catalyst achieved the desired catechol content. x / Nb2O5 nanocomposite catalysts exhibit good hydrothermal catalytic effects.
[0085] The results of the semi-quantitative GC-MS peak separation method for the selection of catechol in Application Example 1 and Comparative Example 4 are recorded in Table 3.
[0086] Table 3. Results of the test on the selectivity of catechol in the products of Application Example 1 and Comparative Example 4.
[0087] Application Cases Catechol selectivity (%) Application Example 1 86.78 Application Comparative Example 4 44.09
[0088] As shown in Table 3, under the condition of 300℃, the 5Ni-5MoO used in Application Example 1 x The / Nb2O5 nanocomposite catalyst enabled the selective conversion of guaiacol to catechol by hydrothermal conversion to reach 86.78%, which is 42.69% higher than that under the 5Ni-5Mo / Nb2O5 condition in Comparative Example 4. This indicates that among bimetallic nanocomposite catalysts, retaining the oxidation state of Mo has a better selective catalytic effect than elemental Mo.
[0089] As can be seen from the above examples, under the condition of 300℃, the 5Ni-5MoO prepared by the present invention... x The Nb2O5 nanocomposite catalyst can activate the O-demethylation reaction (ODM) via a one-pot process, Ni promotes the hydrogenation process of guaiacol, and MoO... x It provides oxygen uptake capacity and assists in-situ hydrogenation. At the same time, the Nb2O5 support surface has both Brønsted acid and Lewis acid sites, which can minimize the dissociation energy of CO bonds, promote CO bond breaking, and enable the reaction to proceed in the forward direction, achieving a high-value conversion of guaiacol to catechol under mild reaction conditions without external hydrogen.
[0090] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. The application of a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst in the catalytic hydrothermal conversion of guaiacol to catechol, characterized in that, The preparation method of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst includes the following steps: The nickel source and molybdenum source are mixed with water to obtain a nickel-molybdenum bimetallic salt solution; Niobium pentoxide was mixed with the nickel-molybdenum bimetallic salt solution, and the resulting composite suspension was sequentially heated, dried and calcined to obtain a catalyst precursor. The catalyst precursor was reduced under a reducing atmosphere to obtain a Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst. The molar ratio of niobium pentoxide to the nickel source and the molybdenum source is 0.0376:0~0.05:0~0.04, and the molar number of both the nickel source and the molybdenum source is not 0. The reduction reaction is carried out at a temperature of 500-600℃ for 1-3 hours. In the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, the theoretical loading of Ni is 8~20 wt%, and the theoretical loading of molybdenum oxide is 8~20 wt%. The method of the application includes: mixing Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol and water, and carrying out a hydrothermal reaction to obtain catechol; The conditions for the hydrothermal reaction include: a reaction temperature of 280~320℃, a reaction time of 1~3h, and a reaction vessel rotation speed of 300~400rpm.
2. The application according to claim 1, characterized in that, The nickel source includes nickel nitrate or nickel chloride; the molybdenum source includes ammonium molybdate or sodium molybdate.
3. The application according to claim 2, characterized in that, The molar ratio of the nickel source, molybdenum source and water is 0~0.05:0~0.004:3.33, and the number of moles of both the nickel source and the molybdenum source is not 0.
4. The application according to claim 1 or 3, characterized in that, The heat treatment is carried out at a temperature of 60~80℃ for 4~6 hours; the heat treatment is carried out under stirring conditions, the stirring speed is 200~400 rpm, and the time is 4~6 hours. The drying temperature is 90~120℃, and the time is 12~24h; The calcination temperature is 400~600℃, and the time is 3~5h.
5. The application according to claim 4, characterized in that, The reducing atmosphere is a hydrogen atmosphere, and the flow rate of the hydrogen is 80~100mL / min.
6. The application according to claim 1, characterized in that, The ratio of the Ni-molybdenum oxide / Nb2O5 nanocomposite catalyst, guaiacol, and water is 0.3~0.7g:5mL:50mL.