A noble metal loaded organic-inorganic hybrid catalyst, its preparation method and application

Abstract

The application relates to the field of biomass energy conversion, and provides an organic-inorganic hybrid catalyst loaded with noble metal and application, the catalyst comprising an organic-inorganic hybrid phosphotungstate carrier and a noble metal active component loaded on the organic-inorganic hybrid phosphotungstate carrier, the organic-inorganic hybrid phosphotungstate carrier being formed by self-assembly without a template from an organic base and phosphotungstic acid, the organic-inorganic hybrid phosphotungstate carrier having a mesoporous structure, and the mesoporous pore size being greater than the kinetic diameter of a fatty acid ester macromolecule; and the noble metal active component is selected from any one of ruthenium, palladium and platinum. The catalyst can be compatible with various woody oil raw materials, realizes efficient deoxygenation of a substrate and extremely high product selectivity for long-chain bioalkanes in complex biomass macromolecule conversion, and provides a new efficient, low-carbon heterogeneous catalysis path for large-scale preparation of high-quality aviation kerosene and diesel from non-edible woody oils.

Description

Technical Field

[0001] This application relates to the field of biomass energy conversion technology, specifically to an organic-inorganic hybrid catalyst supported on noble metals, its preparation method, and its application. Background Technology

[0002] With the increasing severity of global climate change and the gradual depletion of fossil fuel resources, the development of advanced low-carbon emission biofuels (such as green diesel and bio-aviation kerosene) has become an important strategic direction in the modern energy sector. Traditional biofuel production mainly relies on edible oils such as soybean oil, rapeseed oil, and palm oil as raw materials, resulting in high production costs. Therefore, developing biofuel preparation technologies using non-edible woody oils as raw materials has significant practical and industrial value.

[0003] *Vernicia fordii*, a high-quality woody oilseed tree species widely distributed in southern China, is rich in oil in both its pulp and seeds, boasting a high oil yield per unit area and earning it the reputation of an "oil depot on the tree." *Vernicia fordii* oil contains 60% to 80% unsaturated fatty acids, including linoleic acid, with a carbon chain primarily consisting of C16-C18, making it an excellent chemical precursor for producing high-grade long-chain alkane biofuels (especially biodiesel and bio-aviation kerosene). Besides *Vernicia fordii* oil, other non-edible woody oils and their derivatives, such as *Jatropha curcas* oil, *Sapindus mukorossi* oil, *Sapium sebiferum* oil, *Camellia oleifera* seed oil, and palm oil by-products, all possess similar long-chain fatty acid structural characteristics and can serve as ideal raw materials for catalytic hydrodeoxygenation reactions.

[0004] In existing technologies, catalyst systems used for the hydrodeoxygenation of oils and their methyl esters can be mainly classified into the following categories:

[0005] The first category is traditional sulfide-state transition metal catalysts, such as sulfide-state nickel-molybdenum / alumina catalysts and cobalt-molybdenum / alumina catalysts. Although these catalysts have certain hydrodeoxygenation activity, they are prone to sulfur loss during the reaction, which not only contaminates the products and corrodes the equipment, but also causes the hydrothermal structure of the Al2O3 support to collapse, resulting in a short catalyst lifespan. In addition, these catalysts have a high proportion of decarboxylation and decarbonylation pathways during the reaction, leading to a low carbon yield of the target long-chain alkanes.

[0006] The second category consists of transition metal catalysts supported on traditional molecular sieves (such as ZSM-5, Beta, and Y-type molecular sieves). Although these catalysts have tunable acidity and good hydrocracking capabilities, their micropore size (typically less than 1 nanometer) is much smaller than the hydrodynamic diameter of long-chain fatty acid ester macromolecules (approximately 2 to 3 nanometers). This severely hinders the diffusion of macromolecular reactants within the catalyst channels, resulting in low utilization of active sites and a high susceptibility to coking and blockage at the pore openings, leading to rapid catalyst deactivation.

[0007] The third category consists of acidic catalysts represented by heteropolyacids (especially Keggin-type heteropolyacids, such as phosphotungstic acid, silicotungstic acid, and phosphomolybdic acid). Heteropolyacids possess extremely strong Brønsted acidity far exceeding that of traditional mineral acids, and also exhibit bifunctional redox properties, making them a type of green strong acid catalyst. However, heteropolyacid crystals typically have a low specific surface area (generally less than 10 square meters per gram) and high solubility in polar media (such as water and methanol), making them difficult to effectively separate and recycle in heterogeneous catalytic systems, severely limiting their industrial applications. Although there are reports in the existing technology of improving the dispersion of heteropolyacids by loading them onto supports such as activated carbon, silica, and alumina, the binding force between the supported heteropolyacids and the support is weak, making it easy for active components to be lost during the reaction, and the density of exposed acidic sites remains limited.

[0008] The fourth category comprises supported noble metal catalysts developed in recent years, including supported palladium (Pd), platinum (Pt), ruthenium (Ru), rhodium (Rh), and iridium (Ir) catalysts. Noble metal active components possess excellent hydrogen dissociation and activation capabilities, enabling them to drive hydrodeoxygenation reactions under relatively mild reaction conditions. However, most existing supported noble metal catalysts use traditional oxides (such as Al₂O₃, SiO₂, TiO₂, ZrO₂, etc.) or activated carbon as supports. These supports themselves lack sufficient Brønsted acid sites, making it difficult to effectively polarize CO bonds, lower the CO bond hydrogenolysis barrier, and promote the dehydration reaction of aliphatic alcohol intermediates. Therefore, decarboxylation and decarbonylation side reactions account for a high proportion during the reaction, limiting the selectivity of the target direct hydrodeoxygenation pathway and leading to a decrease in product carbon yield. Furthermore, traditional supports lack sufficient dispersion and stabilization capabilities for noble metal nanoparticles, which are prone to agglomeration and sintering at higher reaction temperatures, causing rapid decline in catalyst activity. Summary of the Invention

[0009] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide an organic-inorganic hybrid catalyst supported on noble metals and its application.

[0010] To achieve the above objectives, this application provides an organic-inorganic hybrid catalyst supported on a noble metal, comprising an organic-inorganic hybrid phosphotungstenate support and a noble metal active component supported on the organic-inorganic hybrid phosphotungstenate support. The organic-inorganic hybrid phosphotungstenate support is formed by template-free self-assembly of an organic base and phosphotungstic acid. The organic-inorganic hybrid phosphotungstenate support has a mesoporous structure with a mesopore diameter greater than 2 nm. The noble metal active component is selected from any one of ruthenium, palladium, and platinum.

[0011] In one embodiment, the mass loading of the noble metal active component in the catalyst is 1wt%-10wt%.

[0012] In one embodiment, the organic base is triethylamine or pyridine.

[0013] In one embodiment, the molar ratio of the organic base to phosphotungstic acid is 1:1 to 5:1.

[0014] Based on a general inventive concept, the present invention also provides a method for preparing the above-mentioned catalyst, comprising the following steps: (1) Dissolve an organic base in anhydrous ethanol to prepare an ethanol solution of the organic base; dissolve phosphotungstic acid in anhydrous ethanol to prepare an ethanol solution of phosphotungstic acid; add the ethanol solution of the organic base dropwise to the ethanol solution of phosphotungstic acid, stir, and generate a precipitate by centrifugation. After washing, centrifuging and drying the precipitate, organic-inorganic hybrid phosphotungstic acid carrier powder is obtained. (2) Using a wet impregnation method, the noble metal precursor is first dissolved in water to prepare a noble metal precursor aqueous solution. Then, the organic-inorganic hybrid phosphotungstenate support powder is added to the noble metal precursor aqueous solution for impregnation. After stirring evenly, the water is removed by drying to obtain the catalyst precursor. The catalyst precursor loaded with noble metal is then placed in a hydrogen environment for high-temperature reduction treatment. After the treatment is completed, it is cooled to room temperature to prepare the organic-inorganic hybrid catalyst loaded with noble metal.

[0015] In one embodiment, the stirring time in step (1) is 12-48 hours; The centrifugation speed is 6000-10000 rpm, and the centrifugation time is 10-20 min; The precipitate was washed with anhydrous ethanol and centrifuged at least three times after washing; the drying temperature was 60-100℃ and the drying time was 6 h-24 h. In the ethanol solution of the organic base, the mass ratio of the organic base to the volume of anhydrous ethanol is 1g:150-500mL. In the ethanol solution of phosphotungstic acid, the mass ratio of phosphotungstic acid to anhydrous ethanol is 1 g: 5.5-12.5 mL, and the molar ratio of organic base to phosphotungstic acid is 1:1-5:1.

[0016] In one embodiment, in step (2), the temperature of the high-temperature reduction treatment is 350-450℃, the time is 1-3h, and the heating rate is 10-15℃ / min; In the aqueous solution of the noble metal precursor, the mass ratio of the noble metal precursor to the volume of water is 1 g: 20-50 mL, and the mass ratio of the noble metal precursor to the organic-inorganic hybrid phosphotungstenate carrier powder is 0.025: 1-0.3: 1.

[0017] Based on a general inventive concept, the present invention also provides the application of the above-mentioned catalyst in the conversion of non-edible woody oils into long-chain bioalkanes.

[0018] In one embodiment, after non-edible woody oils are pre-esterified and transesterified to produce fatty acid methyl esters, the catalyst is added to a reactor containing fatty acid methyl esters. Under a pure hydrogen atmosphere, the temperature is raised to the reaction temperature, stirred, and kept constant to produce long-chain bioalkane.

[0019] In one embodiment, the non-edible woody oil is selected from any one of the following: *Vernicia fordii* oil, *Jatropha curcas* oil, *Sapindus mukorossi* oil, *Sapium sebiferum* oil, and *Sapium sebiferum* oil. The reaction pressure is 2MPa-5MPa; The stirring speed is 600-800 rpm; The reaction temperature is 220-300℃, and the constant temperature reaction time is 8-24h; The mass ratio of the catalyst to fatty acid methyl ester or fatty acid ethyl ester is 1:1 to 1:30.

[0020] The method for preparing the organic-inorganic hybrid catalyst supported on noble metals provided by this invention is simple, cost-controllable, and feasible for large-scale production.

[0021] Compared with the prior art, this application has the following beneficial effects: (1) Phosphotungstic acid provides an acidic environment. Under acidic conditions, organic bases and hydrogen ions combine to transform into organic cations. Since the organic cations contain both hydrophobic nonpolar carbon skeletons and hydrophilic polar ionic ends, when they undergo template-free self-assembly with heteropolyacid anions (phosphotungstic acid anions), they spontaneously form aggregates composed of organic cations and heteropolyacid anions through hydrophilic-hydrophobic interactions and steric hindrance effects. The aggregates stack together to create a void structure, thereby giving the support a unique microscopic amphiphilicity and a rich mesoporous network. This type of pore structure can provide sufficient diffusion channels for long-chain fatty acid ester macromolecules, effectively improving the diffusion mass transfer capacity of the reaction substrate inside the catalyst and significantly reducing the diffusion resistance of the reaction substrate entering the pores and the product leaving the surface of the support. (2) The Keggin-type heteropolyacid anion core completely preserved inside the organic-inorganic hybrid phosphotungsten support provides a high density of Brønsted acid sites. These acidic sites can effectively protonate and polarize CO and C=O bonds in macromolecular substrates, significantly reducing their breaking energy barrier, promoting the combination of oxygen-containing groups with hydrogen and their removal in the form of water molecules, thereby precisely controlling the reaction to proceed along the direct hydrogenation-deoxygenation pathway and maximally suppressing the loss of carbon atoms caused by decarbonylation / decarboxylation. (3) The skeletal structure of the phosphotungstic acid anion on the support surface contains abundant terminal oxygen and bridging oxygen atoms. These oxygen atoms have lone pairs of electrons and can provide electron pairs to participate in bonding. The noble metal cations have empty valence electron orbitals and can receive lone pairs of electrons provided by oxygen atoms. Therefore, the heteropolyacid anion can capture the positively charged noble metal precursor through strong electrostatic adsorption. The heteropolyacid anion can form stable coordination bonds with the noble metal cation through surface oxygen atoms, thereby achieving a firm coordination anchoring of the metal precursor, effectively inhibiting the aggregation of noble metals during the high-temperature reduction process, and introducing a high degree of [missing information] on the surface of the organic-inorganic hybrid phosphotungstic acid support. Dispersed noble metal active components; the supported noble metal active components have excellent hydrogen activation and dissociation capabilities, which can continuously provide adsorbed active hydrogen for catalytic reactions; the noble metal active components are directly anchored on the surface of a heteropolyacid support framework rich in Brønsted acid sites. The noble metal active components and Brønsted acid sites have a high degree of spatial coupling at the nanoscale, realizing a spatial synergistic effect. This spatial synergistic effect greatly shortens the diffusion distance of active hydrogen species from metal sites to surrounding acid sites, enabling the substrate polarized by acid sites to be rapidly attacked and broken by active hydrogen, forming a highly efficient metal (hydrogenation)-acid (deoxygenation) bifunctional synergistic catalytic system. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 This is a schematic diagram illustrating the principle of the method for preparing long-chain hydrocarbon molecules by converting long-chain fatty acid molecules according to Example 1 of the present invention. Figure 2 X-ray diffraction pattern of the organic-inorganic hybrid catalyst loaded with noble metals prepared in Example 1 of this invention; Figure 3 X-ray photoelectron spectra of the organic-inorganic hybrid catalyst loaded with noble metals prepared in Example 1 of this invention; (a) shows the N in the X-ray photoelectron spectrum. 1s (a) is the high-resolution energy spectrum; (b) is P 2p High-resolution energy spectrum; (c) is W 4f High-resolution energy spectrum; (d) is Ru 2p High-resolution energy spectrum; Figure 4 The images show transmission electron microscopy (TEM) spectra of the organic-inorganic hybrid catalyst loaded with noble metals prepared in Example 1 of this invention; (a) is a TEM spectra at the 500 nm scale; and (b) is a TEM spectra at the 20 nm scale. Detailed Implementation

[0024] To facilitate understanding of this application, the following description will be more comprehensive and detailed in conjunction with the accompanying drawings and preferred embodiments, but the scope of protection of this application is not limited to the following specific embodiments.

[0025] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of this application.

[0026] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0027] Example 1 An organic-inorganic hybrid catalyst supported on a noble metal comprises an organic-inorganic hybrid phosphotungstenate support and a noble metal active component supported on the organic-inorganic hybrid phosphotungstenate support. The organic-inorganic hybrid phosphotungstenate support is formed by template-free self-assembly of triethylamine and phosphotungstic acid. The organic-inorganic hybrid phosphotungstenate support has a mesoporous structure with a mesopore size of 15 nm. The noble metal active component is selected from ruthenium.

[0028] A method for preparing an organic-inorganic hybrid catalyst supported on a noble metal includes the following steps: (1) Preparation of carrier: 0.20 g of triethylamine was added to 20 mL of anhydrous ethanol and stirred magnetically at room temperature until completely dissolved to obtain a clear solution. The ethanol solution of triethylamine was prepared. 2.88 g of phosphotungstic acid was dissolved in 20 mL of anhydrous ethanol to prepare an ethanol solution of phosphotungstic acid. The ethanol solution of organic base was added dropwise to the ethanol solution of phosphotungstic acid. The molar ratio of triethylamine to phosphotungstic acid was 2:1. The mixture was continuously stirred magnetically for 24 h. A white precipitate was generated by centrifugation. The supernatant was discarded. The centrifugation speed was 8000 rpm and the centrifugation time was 15 min. The precipitate was redispersed and washed with anhydrous ethanol and centrifuged at least three times. Then it was placed in an oven at 80 °C and dried overnight to obtain organic-inorganic hybrid phosphotungstic acid carrier powder.

[0029] (2) Catalyst preparation: The wet impregnation method was adopted. First, 0.13 g of ruthenium precursor was dissolved in 5 mL of water to prepare an aqueous solution of ruthenium precursor. Then, 1 g of organic-inorganic hybrid phosphotungstic acid support powder was added to the aqueous solution of ruthenium precursor for impregnation. After stirring evenly, the solution was dried in an oven at 80°C for 12 h to remove moisture and obtain the catalyst precursor. The ruthenium precursor was ruthenium trichloride trihydrate (RuCl3·3H2O). The mass loading of ruthenium in the catalyst was controlled to be 5 wt% to obtain the catalyst precursor. Then, the ruthenium-loaded catalyst precursor was placed in a hydrogen environment for high-temperature reduction treatment at 400°C for 2 h. After the high-temperature reduction treatment was completed, the solution was cooled and removed to obtain the organic-inorganic hybrid catalyst loaded with noble metal.

[0030] This invention provides the application of a noble metal-supported organic-inorganic hybrid catalyst in the conversion of methyl esters from *Vernicia fordii* oil to prepare long-chain bioalkane.

[0031] First, *Vernicia fordii* oil is pre-esterified and transesterified to produce *Vernicia fordii* oil methyl ester. The specific steps are as follows: High-acid-value tung oil was pre-esterified by heating and dehydrating the oil, then adding methanol at a methanol-to-oil molar ratio of 6:1 to 12:1, and adding concentrated sulfuric acid as a catalyst (the mass of the concentrated sulfuric acid was 0.5%-2.0% of the tung oil mass). The reaction was refluxed and stirred at 60℃-70℃ for 2 hours. The reaction was stopped and the oil was washed and dehydrated after the acid value dropped below 1.0 mg KOH / g. Subsequently, the transesterification stage was carried out by adding a methanol solution containing 0.8%-1.5% sodium hydroxide (the methanol-to-tung oil molar ratio was maintained at 6:1) to the pre-esterified oil. The reaction was carried out at a constant temperature of 60℃-65℃ and stirred at 300-500 rpm for 1-2 hours. After the reaction is complete, the mixture is transferred to a separatory funnel and allowed to stand for 8-12 hours to separate the glycerol layer at the bottom. The upper crude methyl ester is washed repeatedly with hot water at 50℃-60℃ until neutral. Finally, residual water and methanol are removed by vacuum distillation at 105℃ to obtain high-purity methyl ester of tung oil.

[0032] Then, methyl arbutin oil undergoes a hydrodeoxygenation reaction to produce long-chain bioalkane. The steps of the hydrodeoxygenation reaction are as follows: In a 50 mL high-pressure stainless steel batch reactor, 6 g of methyl arvense and 0.6 g of the prepared organic-inorganic hybrid catalyst loaded with noble metals were added. Air was purged with nitrogen at least three times, followed by hydrogen purging, and the pressure was increased to 3 MPa at room temperature. Mechanical stirring was started at 800 rpm, and the temperature was increased to 260 °C at a rate of 10 °C / min and held at this temperature for 12 h to obtain long-chain bioalkane.

[0033] After the hydrodeoxygenation reaction is completed, the reaction system is naturally cooled and depressurized step by step. The reaction mixture is taken out, centrifuged, and the supernatant is collected for gas chromatography detection and analysis of the liquid product.

[0034] Agilent 7890A gas chromatograph equipped with a flame ionization detector (FID) was used to perform qualitative identification and precise quantitative analysis of the liquid phase products. For chromatographic separation, an HP-5 capillary column was used, which is well-suited for the efficient separation of fatty acid methyl esters and long-chain alkanes. High-purity nitrogen (≥99.999%) was used as the carrier gas, and both the injection port temperature and the detector temperature were set at 280℃.

[0035] The column oven temperature program was set as follows: initial temperature 120℃, hold for 1 min; then increase the temperature to 175℃ at a rate of 10℃ / min, and then adjust the rate of increase to 5℃ / min to continue increasing the temperature to 250℃.

[0036] Chromatographic analysis results showed that the methyl ester of tung oil was completely converted, with a conversion rate of 100%; the selectivity of the target product, long-chain alkanes, was 95.8%, and the proportion of characteristic chromatographic peaks of long-chain alkanes in the gas chromatogram reached 100.00%.

[0037] Figure 1 This is a schematic diagram illustrating the principle of the method for preparing long-chain hydrocarbon molecules by converting long-chain fatty acid molecules according to an embodiment of the present invention.

[0038] Figure 2 The image shows the X-ray diffraction pattern of the organic-inorganic hybrid catalyst loaded with noble metals prepared in this embodiment. The X-ray diffraction pattern shows that the original crystal structure of the support was not destroyed after loading with noble metals. Furthermore, characteristic ruthenium diffraction peaks appear in the pattern, preliminarily indicating that ruthenium was successfully loaded and exists mainly in elemental form. Figure 2 Ru / TEA-PW is the organic-inorganic hybrid catalyst supported on noble metals in this embodiment.

[0039] Figure 3 X-ray photoelectron spectra of the organic-inorganic hybrid catalyst loaded with noble metals prepared in Example 1 of this invention; (a) shows the N in the X-ray photoelectron spectrum. 1s (a) is the high-resolution energy spectrum; (b) is P 2p High-resolution energy spectrum; (c) is W 4f High-resolution energy spectrum; (d) is Ru 2p High-resolution energy spectrum, Figure 3 The results indicate that the chemical state of the organic-inorganic hybrid phosphotungsten support remains stable during the loading process, and that ruthenium is predominantly elemental, which is consistent with the design scheme of the catalyst in this system.

[0040] Figure 4 The images show transmission electron microscopy (TEM) spectra of the organic-inorganic hybrid catalyst loaded with noble metals prepared in Example 1 of this invention; (a) is a TEM spectra at the 500 nm scale; (b) is a TEM spectra at the 20 nm scale, confirming that Ru particles are uniformly dispersed on the support surface.

[0041] Example 2 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that the mass loading of ruthenium in the catalyst is controlled to be 1 wt% in step (2).

[0042] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that, due to the insufficient abundance of effective hydrogenation sites at the interface, the relative proportion of the target long-chain alkanes was 82.84%, and the proportion of unreacted methyl arvense was 17.16%.

[0043] Example 3 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that the mass loading of ruthenium in the catalyst is controlled to be 10 wt% in step (2).

[0044] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 82.92%, and the proportion of unreacted methyl arvense oil was 17.08%.

[0045] Example 4 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1, except that the organic base in step (1) is pyridine.

[0046] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 98.48%, and the proportion of unreacted methyl arvense oil was 1.52%.

[0047] Example 5 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in step (2), the platinum precursor (H2PtCl6·6H2O) is used instead of the ruthenium precursor.

[0048] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 95.27%, and the proportion of unreacted methyl arvense oil was 4.73%.

[0049] Example 6 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in step (2), palladium precursor (Pd(NO3)2) is used instead of ruthenium precursor.

[0050] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 97.53%, and the proportion of unreacted methyl arvense was 2.47%.

[0051] Example 7 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that the temperature is increased to 300°C in the hydrodeoxygenation reaction step.

[0052] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100%, and the proportion of unreacted methyl arvense was 0%.

[0053] Example 8 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in the hydrodeoxygenation reaction step, the temperature is programmed to rise to 260°C and the reaction is kept at a constant temperature for 16 hours.

[0054] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted methyl arvense was 0%.

[0055] Example 9 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in the hydrodeoxygenation reaction step, the temperature is programmed to rise to 260°C and the reaction is kept at a constant temperature for 8 hours.

[0056] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 95.29%, and the proportion of unreacted methyl arvense oil was 4.71%.

[0057] Example 10 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that the temperature is programmed to rise to 220°C in the hydrodeoxygenation reaction step.

[0058] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 80.63%, and the proportion of unreacted methyl arvense oil was 19.37%.

[0059] Example 11 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that hydrogen gas is introduced at room temperature to 5 MPa.

[0060] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted methyl arvense was 0%.

[0061] Example 12 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that hydrogen gas is introduced at room temperature to 2 MPa.

[0062] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 98.85%, and the proportion of unreacted methyl arvense was 1.15%.

[0063] Example 13 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that Jatropha curcas oil is used instead of tung oil.

[0064] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted methyl jatropha oil was 0%.

[0065] Example 14 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that Sapindus mukorossi oil is used instead of tung oil.

[0066] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted Xanthoceras sorbifolium oil methyl ester was 0%.

[0067] Example 15 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metals in this embodiment is the same as that in Example 1, except that the only difference is that the oil of the tung oil tree is used instead of the oil of the tung tree.

[0068] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted methyl sphagnum moss oil was 0%.

[0069] Example 16 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in the hydrodeoxygenation reaction step, the mass ratio of the catalyst to the amount of methyl arvense oil is 1:1 while the amount of methyl arvense oil remains unchanged.

[0070] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 100.00%, and the proportion of unreacted methyl sphagnum moss oil was 0%.

[0071] Example 17 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this embodiment is the same as that in Example 1. The only difference between Example 1 and Example 1 is that in the hydrodeoxygenation reaction step, the mass ratio of the catalyst to the amount of methyl arvense oil is 1:30 while the amount of methyl arvense oil remains unchanged.

[0072] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 77.92%, and the proportion of unreacted methyl sphagnum moss oil was 22.08%.

[0073] Comparative Example 1 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this comparative example is the same as that in Example 1, except that the mass loading of ruthenium in the catalyst is controlled to be 0.1 wt% in step (2).

[0074] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that, due to the insufficient abundance of effective hydrogenation sites at the interface, the relative proportion of the target long-chain alkanes was only 31.77%, and the proportion of unreacted methyl arvense was 68.23%.

[0075] Comparative Example 2 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this comparative example is the same as that in Example 1, except that the cobalt precursor is used instead of the ruthenium precursor in step (2).

[0076] The cobalt precursor is cobalt nitrate hexahydrate.

[0077] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 3.56%, and the proportion of unreacted methyl arvense oil was 96.43%.

[0078] Comparative Example 3 The preparation method of the organic-inorganic hybrid catalyst loaded with noble metal in this comparative example is the same as that in Example 1, except that hydrogen gas was introduced at room temperature to 1 MPa.

[0079] The cobalt precursor is cobalt nitrate hexahydrate.

[0080] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 3.65%, and the proportion of unreacted methyl arvense oil was 96.35%.

[0081] Comparative Example 4 A method for preparing a nano-zirconia supported catalyst with noble metals includes the following steps: (1) Purchase nano-zirconia carriers produced by Shanghai Aladdin Company.

[0082] (3) Catalyst preparation: The same wet impregnation method as in Example 1 was used to load the ruthenium precursor onto the above-mentioned nano-zirconia support. The ruthenium precursor was ruthenium trichloride trihydrate (RuCl3·3H2O), and the mass loading of ruthenium in the catalyst was controlled to be 5wt%, thereby obtaining the catalyst precursor. Then, the ruthenium-loaded catalyst precursor was placed in a hydrogen environment and subjected to high-temperature reduction treatment at a temperature of 400℃ for 2h. After the high-temperature reduction treatment was completed, it was cooled and removed to prepare the noble metal / nano-zirconia supported catalyst.

[0083] This invention provides the application of a nano-zirconia supported catalyst loaded with noble metals in the conversion of methyl esters of tung oil to prepare long-chain bioalkane.

[0084] First, *Vernicia fordii* oil is pre-esterified and transesterified to produce *Vernicia fordii* oil methyl ester. The specific steps are as follows: High-acid-value tung oil was pre-esterified by heating and dehydrating the oil, then adding methanol at a methanol-to-oil molar ratio of 6:1 to 12:1, and adding concentrated sulfuric acid as a catalyst (the mass of the concentrated sulfuric acid was 0.5%-2.0% of the tung oil mass). The reaction was refluxed and stirred at 60℃-70℃ for 2 hours. The reaction was stopped and the oil was washed and dehydrated after the acid value dropped below 1.0 mg KOH / g. Subsequently, the transesterification stage was carried out by adding a solution of sodium hydroxide and methanol at a concentration of 0.8%-1.5% of the oil mass (molecular ratio of methanol to oil maintained at 6:1) to the pre-esterified oil. The reaction was carried out at a constant temperature of 60℃-65℃ and stirred at a speed of 300-500 rpm for 1-2 hours. After the reaction is complete, the mixture is transferred to a separatory funnel and allowed to stand for 8-12 hours to separate the glycerol layer at the bottom. The upper crude methyl ester is washed repeatedly with hot water at 50℃-60℃ until neutral. Finally, residual water and methanol are removed by vacuum distillation at 105℃ to obtain high-purity methyl ester of tung oil.

[0085] Then, methyl arbutin oil undergoes a hydrodeoxygenation reaction to produce long-chain bioalkane. The steps of the hydrodeoxygenation reaction are as follows: In a 50 mL high-pressure stainless steel batch reactor, 6 g of methyl arvense and 0.6 g of precious metal / nano-zirconia supported catalyst were added. Nitrogen gas was purged at least three times to purge air, followed by hydrogen purging. The pressure was increased to 3 MPa at room temperature. Mechanical stirring was started at 800 rpm, and the temperature was programmed to rise to 260 °C and held constant for 12 h to obtain long-chain bioalkane.

[0086] After the reaction was completed, the sample was analyzed under the same gas chromatography test conditions as in Example 1. The test results showed that the relative proportion of the target long-chain alkanes was 0%, and the proportion of unreacted methyl arvense was 100%.

[0087] Analysis of the test results of each embodiment and comparative example shows that the organic-inorganic hybrid catalysts supported on noble metals prepared in each embodiment have a mesoporous structure, which can provide sufficient diffusion channels for long-chain fatty acid ester macromolecules and overcome mass transfer limitations. In this catalyst system, the noble metal center exhibits excellent hydrogen activation and dissociation capabilities. At the same time, the Keggin-type heteropolyacid anion core completely preserved inside the organic-inorganic hybrid phosphotungsten support provides a high density of Brønsted acid sites. The synergistic effect between the noble metal active component and the Brønsted acid sites promotes the efficient conversion of substrates such as methyl arvense oil along the direct hydrodeoxygenation pathway. After the final reaction, the test results of the sample analysis under the gas chromatography test conditions show that the relative proportion of the target long-chain alkanes is 77.92%-100.00%, and the proportion of unreacted methyl arvense oil is 0%-22.08%.

[0088] The method for preparing the precious metal-loaded organic-inorganic hybrid catalyst of this invention is simple, cost-controllable, and feasible for large-scale production. The precious metal-loaded organic-inorganic hybrid catalyst of this invention has a wide range of applications and is compatible with various woody oil feedstocks (including but not limited to *Vernicia fordii* oil, *Jatropha curcas* oil, *Sapindus mukorossi* oil, and *Scleroderma purpurea* oil). This invention achieves deep deoxygenation of substrates and extremely high product selectivity for long-chain bioalkane in the transformation of complex biomass macromolecules, providing a new, efficient, low-carbon heterogeneous catalytic pathway for the large-scale production of high-quality green aviation kerosene and diesel from non-edible woody oils.

[0089] The above are merely preferred embodiments of this application. It should be noted that this application is not limited to the above embodiments. For those skilled in the art, several improvements and modifications can be made without departing from the principles of this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should also be considered within the scope of protection of this application.

Claims

1. An organic-inorganic hybrid catalyst supported on a noble metal, characterized in that, The invention comprises an organic-inorganic hybrid phosphotungstenate support and a noble metal active component loaded on the organic-inorganic hybrid phosphotungstenate support. The organic-inorganic hybrid phosphotungstenate support is formed by template-free self-assembly of an organic base and phosphotungstic acid. The organic-inorganic hybrid phosphotungstenate support has a mesoporous structure with a mesopore diameter greater than 2 nm. The noble metal active component is selected from any one of ruthenium, palladium, and platinum.

2. The catalyst according to claim 1, characterized in that, The mass loading of the noble metal active component in the catalyst is 1wt%-10wt%.

3. The catalyst according to claim 1, characterized in that, The organic base is triethylamine or pyridine.

4. The catalyst according to claim 1, characterized in that, The molar ratio of the organic base to phosphotungstic acid is 1:1 to 5:

1.

5. A method for preparing an organic-inorganic hybrid catalyst supported on a noble metal as described in any one of claims 1-4, characterized in that, Includes the following steps: (1) Dissolve the organic base in anhydrous ethanol to prepare an ethanol solution of the organic base; dissolve the phosphotungstic acid in anhydrous ethanol to prepare an ethanol solution of the phosphotungstic acid; add the ethanol solution of the organic base dropwise to the ethanol solution of the phosphotungstic acid, stir to react and generate a precipitate, then separate the precipitate by centrifugation, and after washing, centrifuging and drying the precipitate, obtain organic-inorganic hybrid phosphotungstic acid carrier powder; (2) Using a wet impregnation method, the noble metal precursor is first dissolved in water to prepare a noble metal precursor aqueous solution. Then, the organic-inorganic hybrid phosphotungstenate support powder is added to the noble metal precursor aqueous solution for impregnation. After stirring evenly, the water is removed by drying to obtain the catalyst precursor. The catalyst precursor loaded with noble metal is then placed in a hydrogen environment for high-temperature reduction treatment and cooled to room temperature to obtain the organic-inorganic hybrid catalyst loaded with noble metal.

6. The preparation method according to claim 5, characterized in that, In step (1), the stirring reaction time is 12-48 hours; The centrifugation speed is 6000-10000 rpm, and the centrifugation time is 10-20 min; The precipitate was washed with anhydrous ethanol and centrifuged at least three times after washing; the drying temperature was 60-100℃ and the drying time was 6 h-24 h. In the ethanol solution of the organic base, the mass ratio of the organic base to the volume of anhydrous ethanol is 1g:150-500mL. In the ethanol solution of phosphotungstic acid, the mass ratio of phosphotungstic acid to anhydrous ethanol is 1 g: 5.5-12.5 mL, and the molar ratio of organic base to phosphotungstic acid is 1:1-5:

1.

7. The preparation method according to claim 5, characterized in that, In step (2), the high-temperature reduction treatment is performed at a temperature of 350-450℃ for 1-3 hours and at a heating rate of 10-15℃ / min. In the aqueous solution of the noble metal precursor, the mass ratio of the noble metal precursor to the volume of water is 1 g: 20-50 mL, and the mass ratio of the noble metal precursor to the organic-inorganic hybrid phosphotungstenate carrier powder is 0.025: 1-0.3:

1.

8. The application of the catalyst according to any one of claims 1-4 in the conversion of non-edible woody oils into long-chain bioalkane.

9. The application as described in claim 8, characterized in that, After non-edible woody oils are pre-esterified and transesterified to produce fatty acid methyl esters, the catalyst is added to a reactor containing fatty acid methyl esters. Under a pure hydrogen atmosphere, the temperature is raised to the reaction temperature, stirred, and kept constant to produce long-chain bioalkane.

10. The application as described in claim 9, characterized in that, The non-edible woody oils are selected from any one of the following: *Vernicia fordii* oil, *Jatropha curcas* oil, *Sapindus mukorossi* oil, *Sapium sebiferum* oil, and *Sapium sebiferum* oil. The reaction pressure is 2MPa-5MPa; The stirring speed is 600-800 rpm; The reaction temperature is 220-300℃, and the constant temperature reaction time is 8-24h; The mass ratio of the catalyst to fatty acid methyl ester or fatty acid ethyl ester is 1:1 to 1:30.

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