Four-metal supported catalyst as well as preparation method and application thereof

Abstract

The invention discloses a tetra-metal supported catalyst and a preparation method and application thereof.The preparation method comprises the steps that a dried ZSM-5 molecular sieve, nickel nitrate hexahydrate and ammonium molybdate are taken and mixed with deionized water, and a suspension A is prepared; adjusting the pH value of the turbid liquid A to be alkaline, standing and precipitating, and drying to obtain a precipitate B; taking palladium dichloride and chloroplatinic acid hexahydrate to prepare a mixed solution, uniformly dropwise adding the mixed solution on the precipitate B, stirring, and drying to obtain solid powder C; and roasting the solid powder C in an air atmosphere and reducing the solid powder C in a reducing atmosphere to prepare the four-metal supported catalyst. According to the method, a'coprecipitation-impregnation double-stage synergistic catalysis' strategy is provided mainly from the aspect of metal synergistic loading, and through ZSM-5 carrier and multi-metal cross-scale synergistic loading, the nitrogen-oxygen synergistic removal conversion rate is increased, and meanwhile, the use content of noble metal is remarkably reduced, so that double improvement of economy and performance is realized.

Description

Technical Field

[0001] The present invention belongs to the field of hydrodenitrogenation and deoxygenation catalysts, and relates to a four-metal supported catalyst, a preparation method thereof and an application thereof. Background Art

[0002] As a highly potential renewable energy source, bio-oil is gradually becoming a sustainable alternative to fossil fuels. Its raw materials are widely sourced, covering lignocellulosic biomass (such as agricultural waste, forestry residues), algal biomass, and municipal organic waste, etc., and are prepared through conversion technologies such as fast pyrolysis and hydrothermal liquefaction. This biomass-based liquid fuel not only has the characteristics of being renewable, can effectively alleviate the dependence on traditional fossil energy, and reduce carbon emissions, but also its production process is relatively flexible, and can be adjusted according to different raw material characteristics and target product requirements, and has a very broad application prospect. However, bio-oil itself has many inherent defects, such as high oxygen content, low calorific value, poor stability, strong corrosiveness, etc., and these characteristics seriously restrict its direct application as a high-quality fuel. In order to improve the fuel quality of bio-oil and make it closer to the performance of traditional fossil fuels, high-value utilization technologies have become the key. However, its high-value utilization requires catalytic hydrodenitrogenation to remove nitrogen and oxygen heteroatoms, so as to improve its calorific value, stability and combustion performance, and enable it to better meet the usage requirements of modern engines and industrial equipment.

[0003] In traditional technologies, due to the significant difference in chemical bond energies between nitrogen and oxygen atoms and the carbon skeleton, efficient nitrogen and oxygen removal requires the synergistic action of different active sites. Multimetallic-supported catalysts, due to their tunable electronic structure and spatial configuration, have become a research focus. These catalysts combine multiple metal active components on a suitable support, leveraging the electronic effects and synergistic interactions between the different metals to achieve efficient nitrogen and oxygen removal. Multimetallic-supported catalysts possess tunable electronic structures and spatial configurations. By rationally selecting the metal species, loading amount, and support type, the electronic properties and geometry of the catalyst can be optimized, thereby enhancing its adsorption and activation of nitrogen and oxygen atoms and promoting the nitrogen and oxygen removal reaction. Among the many metal catalysts, traditional Ni-based catalysts and precious metal Pt / Pd catalysts are two representative systems. While traditional Ni-based catalysts are effective for nitrogen removal, they have poor adsorption capacity for oxygen-containing compounds. Precious metal Pt / Pd catalysts, while offering high deoxygenation rates, face bottlenecks such as high cost and susceptibility to poisoning. In order to improve the synergy of metals, the existing technology uses mechanical mixing loading. This method loads different metal active components on the carrier by physical mixing, hoping that different metals can produce synergistic effects and improve the overall performance of the catalyst. However, actual studies have shown that the utilization rate of active sites in mechanically mixed loaded catalysts is very low. Due to the lack of effective interaction and electron transfer between different metal particles, some metal active sites cannot fully play their role, and the activity and selectivity of the catalyst are seriously affected. These current technologies all have certain problems, which limit their practical application, and the catalytic efficiency needs to be further improved. Summary of the Invention

[0004] The purpose of the present invention is to provide a four-metal supported catalyst and its preparation method and application, so as to solve the problem of low efficiency of bio-oil catalytic denitrification and deoxidation in the prior art.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A method for preparing a four-metal supported catalyst comprises: Dry ZSM-5 molecular sieves, nickel nitrate hexahydrate, ammonium molybdate and deionized water were mixed to prepare suspension A; Adjust the pH value of suspension A to alkaline, let it stand and settle, and then dry to obtain precipitate B; Prepare a mixed solution of palladium dichloride and chloroplatinic acid hexahydrate, evenly drop it onto the precipitate B, stir, and dry to obtain solid powder C; The solid powder C was calcined in an air atmosphere and reduced in a reducing atmosphere to prepare a tetrametallic supported catalyst.

[0006] Further, the mass-volume ratio of the ZSM-5 molecular sieve, nickel nitrate hexahydrate, ammonium molybdate and deionized water is 0.8~0.96 g: 0.0495~0.248 g: 0.0204~0.102 g: 20~30 mL.

[0007] Further, the static precipitation time is 3~5 h, the drying temperature of the precipitate B is 80~120 °C, and the drying time is 6~18 h.

[0008] Further, the mass ratio of palladium dichloride and chloroplatinic acid hexahydrate is 0.0166~0.0832: 0.0209~0.104.

[0009] Further, the mass-volume ratio of the precipitate B and the mixed solution is 1.025~1.200 g: 20~30 mL.

[0010] Further, the drying temperature of the solid powder C is 80~120 °C, and the drying time is 6~18 h.

[0011] Further, the calcination temperature is 350~450 °C, and the calcination time is 3~4 h.

[0012] Further, the reducing atmosphere is H2, the reducing temperature is 440~480 °C, and the reducing time is 4~6 h.

[0013] A four-metal supported catalyst prepared by the above preparation method.

[0014] Application of the described four-metal supported catalyst in catalytic hydrodenitrogenation and desulfurization upgrading of microalgae bio-oil.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a method for preparing a four-metal supported catalyst. First, dried ZSM-5 molecular sieve is mixed with nickel nitrate hexahydrate and ammonium molybdate in deionized water. The pH of the suspension is then adjusted to alkaline using dilute ammonia water. The nickel and molybdenum metals are loaded by co-precipitation. Then, a mixed solution of palladium dichloride and chloroplatinic acid hexahydrate is prepared. The solid obtained after drying the suspension is evenly added dropwise and stirred thoroughly. The platinum and palladium metals are loaded by impregnation. Finally, the catalyst is calcined in air and reduced in a reducing atmosphere to obtain a nickel-molybdenum-platinum-palladium four-metal supported catalyst with excellent catalytic performance for the thermal decomposition and conditioning of nitrogen- and oxygen-containing bio-oil. The present invention mainly proposes a "co-precipitation-impregnation two-stage synergistic catalysis" strategy from the perspective of metal synergistic loading. Through the rational design of the ZSM-5 carrier and the cross-scale synergistic loading of multiple metals, a composite catalyst of Ni, Mo, Pt, and Pd, which is adapted to water-insoluble and high-heteroatom content systems, is prepared to achieve efficient and simultaneous removal of nitrogen and oxygen from bio-oil. The present invention is based on the ZSM-5 carrier and adopts the co-precipitation technology to accurately load the Ni-Mo bimetallic to achieve the primary synergy of the denitrification and deoxygenation reaction. On the surface of the Ni-Mo and carrier co-precipitation layer, the Pt-Pd bimetallic is synchronously loaded by the impregnation method to avoid the efficiency loss caused by competitive adsorption. The electronic structure is regulated by a multi-metal composite strategy, the charge transfer effect of the Ni-Mo bimetallic is utilized to enhance the CN bond breaking ability, the hydrogen adsorption characteristics of the Pt-Pd noble metal are combined to promote the CO bond hydrogenolysis, and the co-precipitation impregnation distribution loading process is used to optimize the spatial distribution of active sites. The present invention uses the co-precipitation method and the impregnation method to load multiple metals on the ZSM-5 molecular sieve at the same time, fully utilizes the porous structure of the molecular sieve, realizes the multi-layer loading of multiple metals, solves the problems of low metal loading rate and uneven metal loading that are common in multi-metal loading, and improves the space utilization rate of the catalyst. At the same time, through multi-metal loading, while improving the nitrogen and oxygen synergistic removal conversion rate, the use content of the precious metal is significantly reduced, thereby achieving a dual improvement in economy and performance, and improving the feasibility of its promotion and application.

[0016] The present invention also provides an application of a four-metal supported catalyst. Taking the typical model compound of stearic acid-hexadecanamide bio-crude oil as the research object, two pairs of metals, nickel-molybdenum and platinum-palladium, which have a coupling effect on deoxygenation and denitrification respectively, are used to convert nitrogen-containing amides (hexadecanamide) into alkanes through hydrodeamination, while oxygen-containing fatty acids (stearic acid) are converted into long-chain alkanes through decarboxylation. The synergistic deoxygenation, denitrification and hydrogenation catalytic conditioning of nitrogen- and oxygen-containing bio-oils represented by microalgae bio-oil are realized, and the problems of excessively high continuous experimental costs of by-products in separate catalytic deoxygenation or catalytic denitrification and the difficulty in treating intermediate products are solved. The present invention not only effectively reduces the usage amount of precious metals, but also realizes the synergistic removal of nitrogen and oxygen through the multi-path coupling of "hydrolysis-hydrogenation-dehydration", and the efficiency is increased by up to 40% compared with traditional petroleum catalysts. The high-energy-density hydrocarbon fuel obtained by the technology of the present invention contains fewer impurities, and the content of pollutants such as NO x emitted during the combustion process is also greatly reduced, reducing the energy consumption and treatment cost of the subsequent refining process, and achieving both economic and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, other related drawings can also be obtained based on these drawings without creative efforts.

[0018] Figure 1 It is a conversion rate curve graph of stearic acid-hexadecanamide for the catalytic hydrogenation reaction of bio-crude oil model compounds using the catalysts prepared under the conditions of Embodiments 1-5 and Comparative Examples 1-5 of the present invention.

[0019] Figure 2 is a GC (gas chromatography) curve graph of stearic acid (Figure (a)) and hexadecanamide (Figure (b)) after the catalytic hydrogenation reaction of bio-crude oil model compounds using the catalysts prepared under the conditions of Embodiments 1-5 and Comparative Examples 1-5 of the present invention.

[0020] Figure 3 is a pie chart of the products after the catalytic hydrogenation reaction of bio-crude oil model compounds using the catalysts prepared under the conditions of Embodiment 2 and Comparative Example 3 of the present invention and without a catalyst (only compounds with a total peak area percentage ≥ 1% are marked). Among them, Figure (a) is a pie chart of the products after the catalytic hydrogenation reaction of bio-crude oil model compounds using the catalyst prepared in Embodiment 2, Figure (b) is a pie chart of the products after the catalytic hydrogenation reaction of bio-crude oil model compounds using the catalyst prepared in Comparative Example 3, and Figure (c) is a pie chart of the products after the catalytic hydrogenation reaction of bio-crude oil model compounds without a catalyst.

[0021] Figure 4 is a peak area diagram of the reaction products (hydrocarbons (Figure (a)) and nitrogen- and oxygen-containing by-products (Figure (b))) of the catalyst prepared under the conditions of Example 2 of the present invention and Comparative Example 3 for the catalytic hydroprocessing of a bio-oil model compound.

[0022] Figure 5 is an SEM electron micrograph of the catalysts prepared under the conditions of Example 2 (Figure (a)), Comparative Example 5 (Figure (b)), Comparative Example 3 (Figure (c)), and Comparative Example 1 (Figure (d)) of the present invention.

[0023] Figure 6 is an energy spectrum diagram of the catalyst prepared under the conditions of Example 2 of the present invention. Detailed Embodiments

[0024] To enable those skilled in the art to understand the features and effects of the present invention, the following provides a general description and definition of the terms and expressions mentioned in the specification and claims. Unless otherwise specified, all technical and scientific terms used herein shall have the ordinary meaning understood by those skilled in the art regarding the present invention. In case of conflict, the definitions in this specification shall prevail.

[0025] The theories or mechanisms described and disclosed herein, whether correct or incorrect, shall not limit the scope of the present invention in any way, that is, the content of the present invention can be implemented without being limited by any specific theory or mechanism.

[0026] In this article, all features defined in the form of numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are only for the sake of brevity and convenience. Accordingly, the description of numerical ranges or percentage ranges should be regarded as having covered and specifically disclosed all possible sub-ranges and individual numerical values within the range (including integers and fractions).

[0027] In this article, unless otherwise specified, terms such as "comprising", "including", "containing", "having", or similar expressions cover the meanings of "consisting of" and "consisting essentially of". For example, "A comprises a" covers the meanings of "A comprises a and others" and "A consists only of a".

[0028] In this article, for the sake of brevity of description, all possible combinations of all technical features in each embodiment or example are not described. Therefore, as long as the combinations of these technical features do not conflict, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered as the scope described in this specification.

[0029] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0030] Conventional instrument and equipment in the art are used in the following embodiments. For the experimental methods without specific conditions noted in the following embodiments, they are usually carried out under conventional conditions or according to the conditions recommended by the manufacturer. Various raw materials are used in the following embodiments. Unless otherwise stated, commercially available products are used, and their specifications are conventional specifications in the art. In the specification of the present invention and the following embodiments, unless otherwise specified, "%" represents weight percentage, "parts" represents weight parts, and the ratio represents weight ratio.

[0031] The present invention will be further described in detail below with reference to the accompanying drawings: The present invention provides a method for preparing a four-metal supported catalyst, which specifically includes the following steps: First, take the ZSM-5 molecular sieve dried at 60 °C for 2 h, mix it with nickel nitrate hexahydrate (NiN₂O₆·6H₂O) and ammonium molybdate (H₈MoN₂O₄), and add deionized water. The mass-volume ratio of the ZSM-5 molecular sieve, nickel nitrate hexahydrate, ammonium molybdate to deionized water is 0.8~0.96 g: 0.0495~0.248 g: 0.0204~0.102 g: 20~30 mL to prepare a suspension A. Subsequently, while stirring the suspension A, slowly drop 1 mol / L dilute ammonia water into it, use the dilute ammonia water to adjust the pH value of the suspension to pH = 8, and let it stand for precipitation for 3~5 h after the pH value is constant to load nickel and molybdenum metals in a coprecipitation manner. Dry it at 80~120 °C for 6~18 h to evaporate the liquid to obtain a precipitate B; Then, prepare a mixed solution of palladium dichloride (PdCl₂) and chloroplatinic acid hexahydrate (H₂PtCl₆·6H₂O) according to a mass ratio of 0.0166~0.0832: 0.0209~0.104, and uniformly drop it on the precipitate B at a mass-volume ratio of the precipitate B to the mixed solution of 1.025~1.200 g: 20~30 mL, and stir magnetically at room temperature for 12 h to load platinum and palladium metals in an impregnation manner. Subsequently, dry it at 80~120 °C for 6~18 h to evaporate the liquid to obtain a solid powder C; The solid powder C was calcined at 350 - 450 °C in an air atmosphere for 3 - 4 h. Finally, in a tubular furnace, it was heated from room temperature to 440 - 480 °C at a heating rate of 2 °C / min in a H₂ atmosphere of 25 ml / min and reduced for 4 - 6 h. After calcination in an air atmosphere and reduction in a reducing atmosphere, a nickel - molybdenum - platinum - palladium four - metal supported catalyst with excellent catalytic performance for the thermal demodulation and upgrading of nitrogen - and oxygen - containing bio - oil was obtained.

[0032] This patent also provides an application method of the above - mentioned nickel - molybdenum - platinum - palladium four - metal supported catalyst, specifically for the application of the above - mentioned nickel - molybdenum - platinum - palladium four - metal supported catalyst in the catalytic hydro - denitrogenation and denitration and upgrading of micro - algal bio - oil.

[0033] The following further describes the present invention in detail through specific examples: Example 1: 1) 0.96 g of ZSM - 5 molecular sieve dried at 60 °C for 2 h, 0.0495 g of NiN₂O₆·6H₂O and 0.0204 g of H₈MoN₂O₄ were added to 20 ml of deionized water to prepare a suspension A. 2) While stirring suspension A, 1 mol / L dilute ammonia water was slowly added dropwise to it until pH = 8. After the pH value was constant, it was left to stand and precipitate for 3 h, and then dried at 80 °C for 6 h to evaporate the liquid to obtain precipitate B. 3) 0.0166 g of PdCl₂ and 0.0209 g of H₂PtCl₆·6H₂O were added to deionized water to prepare a 20 - ml solution, which was evenly dropped onto precipitate B and magnetically stirred at room temperature for 12 h, and then dried at 80 °C for 6 h to evaporate the liquid to obtain solid powder C. 4) The solid powder C was calcined at 350 °C in an air atmosphere for 3 h. Finally, in a tubular furnace, it was heated from room temperature to 440 °C at a heating rate of 2 °C / min in a H₂ atmosphere of 25 ml / min and reduced for 4 h to prepare a Ni - Mo - Pt - Pd / ZSM - 5 four - metal supported catalyst with a metal loading of 1 wt% for each metal.

[0034] Example 2: 1) 0.9 g of ZSM - 5 molecular sieve dried at 60 °C for 2 h, 0.124 g of NiN₂O₆·6H₂O and 0.0511 g of H₈MoN₂O₄ were added to 22.5 ml of deionized water to prepare a suspension A. 2) While stirring suspension A, dilute ammonia water was slowly added dropwise to it until pH = 8. After the pH value was constant, it was left to stand and precipitate for 3.5 h, and then dried at 90 °C for 9 h to evaporate the liquid to obtain precipitate B. 3) Weigh 0.0416 g of PdCl2 and 0.0523 g of H2PtCl6·6H2O, add deionized water to make a 22.5 ml solution, and evenly drop it on precipitate B. Stir magnetically at room temperature for 12 h, and then dry it at 90 °C for 9 h to evaporate the liquid to obtain solid powder C; 4) Calcine the solid powder C at 375 °C in an air atmosphere for 3.25 h. Finally, use a tube furnace to rise to 450 °C at a heating rate of 2 °C / min in a H2 atmosphere of 25 ml / min and reduce it for 4.5 h to prepare a nickel-molybdenum-platinum-palladium four-metal supported catalyst with a metal loading of 2.5 wt% for each metal.

[0035] Example 3: 1) Take 0.85 g of ZSM-5 molecular sieve dried at 60 °C for 2 h, 0.124 g of NiN2O6·6H2O and 0.0511 g of H8MoN2O4, add 25 ml of deionized water to make a suspension A; 2) While stirring suspension A, slowly drop 1 mol / L dilute ammonia water into it until pH = 8. After the pH value is constant, let it stand for precipitation for 4 h, and then dry it at 100 °C for 12 h to evaporate the liquid to obtain precipitate B; 3) Weigh 0.0832 g of PdCl2 and 0.104 g of H2PtCl6·6H2O, add deionized water to make a 25 ml solution, and evenly drop it on precipitate B. Stir magnetically at room temperature for 12 h, and then dry it at 100 °C for 12 h to evaporate the liquid to obtain solid powder C; 4) Calcine the solid powder C at 400 °C in an air atmosphere for 3.5 h. Finally, use a tube furnace to rise to 460 °C at a heating rate of 2 °C / min in a H2 atmosphere of 25 ml / min and reduce it for 5 h to prepare a Ni-Mo-Pt-Pd / ZSM-5 four-metal supported catalyst with a nickel and molybdenum loading of 2.5 wt% and a platinum and palladium loading of 5 wt%.

[0036] Example 4: 1) Take 0.85 g of ZSM-5 molecular sieve dried at 60 °C for 2 h, 0.248 g of NiN2O6·6H2O and 0.102 g of H8MoN2O4, add 27.5 ml of deionized water to make a suspension A; 2) While stirring suspension A, slowly drop 1 mol / L dilute ammonia water into it until pH = 8. After the pH value is constant, let it stand for precipitation for 4.5 h, and then dry it at 110 °C for 15 h to evaporate the liquid to obtain precipitate B; 3) Weigh 0.0416 g of PdCl2 and 0.0523 g of H2PtCl6·6H2O, add deionized water to make up a 27.5 ml solution, and evenly drip it onto precipitate B. Stir magnetically at room temperature for 12 h, and then dry it at 110 °C for 15 h to evaporate the liquid to obtain solid powder C; 4) Roast solid powder C at 425 °C in an air atmosphere for 3.75 h. Finally, use a tube furnace to raise the temperature to 470 °C at a heating rate of 2 °C / min in a H2 atmosphere of 25 ml / min and reduce it for 5.5 h to prepare a Ni-Mo-Pt-Pd / ZSM-5 four-metal supported catalyst with a nickel and molybdenum loading of 5 wt% and a platinum and palladium loading of 2.5 wt%.

[0037] Example 5: 1) Take 0.8 g of ZSM-5 molecular sieve dried at 60 °C for 2 h, 0.248 g of NiN2O6·6H2O and 0.102 g of H8MoN2O4, add 30 ml of deionized water to make up suspension A; 2) While stirring suspension A, slowly drip 1 mol / L dilute ammonia water into it until pH = 8. After the pH value is constant, let it stand and precipitate for 5 h, and then dry it at 120 °C for 18 h to evaporate the liquid to obtain precipitate B; 3) Weigh 0.0832 g of PdCl2 and 0.104 g of H2PtCl6·6H2O, add deionized water to make up a 30 ml solution, evenly drip it onto precipitate B, stir magnetically at room temperature for 12 h, and then dry it at 120 °C for 18 h to evaporate the liquid to obtain solid powder C; 4) Roast solid powder C at 450 °C in an air atmosphere for 4 h. Finally, use a tube furnace to raise the temperature to 480 °C at a heating rate of 2 °C / min in a H2 atmosphere of 25 ml / min and reduce it for 6 h to prepare a Ni-Mo-Pt-Pd / ZSM-5 four-metal supported catalyst with a metal loading of 5 wt% for all.

[0038] Comparative Example 1: 1) Weigh 0.1688 g of ZSM-5 molecular sieve, and respectively weigh 0.0376 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O) and 0.0289 g of ammonium molybdate ((NH4)6Mo7O 24 ·4H2O) according to the loading of 3.33 wt% for each of nickel (Ni) and molybdenum (Mo). Dissolve them in 30 mL of deionized water, add ZSM-5 powder and ultrasonically disperse for 10 min. While stirring, drip 1 mol / L dilute ammonia water until pH = 8. After aging for 3 hours, evaporate the solution to dryness. The solid product is dried at 120 °C for 12 h and roasted at 500 °C for 3 h to obtain a Ni-Mo / ZSM-5 intermediate; 2) Subsequently, weigh 0.0139 g of ruthenium chloride (RuCl3·xH2O) with a ruthenium (Ru) loading of 3.33 wt%, dissolve and stir it, impregnate the intermediate for 12 h, dry it at 120 °C for 12 h, calcine it at 400 °C for 4 h, and then reduce it in a 5% hydrogen - 95% nitrogen mixture with a temperature gradient increase of 2 °C / min (460 °C, 4 h) to finally obtain the Ni - Mo - Ru / ZSM - 5 catalyst.

[0039] Comparative Example 2: 1) Weigh 1.594 g of ZSM - 5 molecular sieve, and respectively weigh 0.148 g of hexahydrate chloroplatinic acid (H2PtCl6·6H2O), 0.117 g of palladium chloride (PdCl2), 0.1161 g of nickel nitrate hexahydrate (Ni(NO3)2·6H2O), and 0.0479 g of ruthenium chloride (RuCl3·xH2O) according to a total loading of 15 wt% of platinum (Pt), palladium (Pd), nickel (Ni), and ruthenium (Ru). First, dissolve H2PtCl6 and PdCl2 in 30 mL of deionized water, add the ZSM - 5 powder and stir for 10 minutes, dropwise add dilute ammonia water until pH = 8, co - precipitate for 3 h, then evaporate the solution to dryness, dry the solid at 120 °C for 12 h, and calcine it at 500 °C for 3 h to obtain the Pt - Pd / ZSM - 5 intermediate; 2) Subsequently, dissolve Ni(NO3)2 and RuCl3 in 5 mL of deionized water, impregnate the intermediate for 12 h, dry it at 120 °C for 12 h, calcine it at 400 °C for 4 h, and then reduce it in a 5% hydrogen - 95% nitrogen mixture by heating to 460 °C at a rate of 2 °C / min for 4 h to obtain the Pt - Pd - Ni - Ru / ZSM - 5 four - metal - loaded catalyst.

[0040] Comparative Example 3: 1) Take 0.833 g of ZSM - 5 molecular sieve dried at 60 °C for 2 h, weigh 0.165 g of NiN2O6·6H2O, 0.0832 g of PdCl2, 0.104 g of H2PtCl6·6H2O, and 0.0683 g of RuCl3 to prepare a 30 ml aqueous solution, uniformly drop it on the ZSM - 5 molecular sieve, stir magnetically at room temperature for 12 h, and then dry it at 120 °C for 12 h to evaporate the liquid to obtain solid powder A; 2) Calcinate the solid powder A at 400 °C in an air atmosphere for 4 h, and finally use a tube furnace to reduce it to 460 °C at a heating rate of 2 °C / min in a H2 atmosphere of 25 ml / min for 4 h to prepare a Ni - Ru - Pt - Pd / ZSM - 5 four - metal - loaded catalyst with a nickel and ruthenium loading of 3.33 wt% and a platinum and palladium loading of 5 wt%.

[0041] Comparative Example 4: 1) Take 0.9 g of HZSM-5 molecular sieve dried at 60 °C for 2 h, 0.165 g of NiN₂O₆·6H₂O and 0.0683 g of RuCl₃, and add deionized water to prepare 30 ml of suspension A; 2) While stirring suspension A, slowly add 1 mol / L dilute ammonia water to it until pH = 8. After the pH value is constant, let it stand and precipitate for 3 h, and then dry it at 120 °C for 12 h to evaporate the liquid to obtain precipitate B; 3) Weigh 0.0554 g of PdCl₂ and prepare it into 30 ml of aqueous solution, and evenly drop it on precipitate B, stir magnetically at room temperature for 12 h, and then dry it at 120 °C for 12 h to evaporate the liquid to obtain solid powder C; 4) Calcine the solid powder C at 400 °C in an air atmosphere for 4 h, and finally use a tubular furnace to raise the temperature to 460 °C at a heating rate of 2 °C / min in a H₂ atmosphere of 25 ml / min and reduce it for 4 h to prepare a Ni-Ru-Pd / HZSM-5 trimetallic supported catalyst with a metal loading of 3.33 wt% for all.

[0042] Comparative Example 5: 1) Take 0.9 g of m-HZSM-5 molecular sieve dried at 60 °C for 2 h, 0.165 g of NiN₂O₆·6H₂O and 0.0680 g of H₈MoN₂O₄, and add deionized water to prepare 30 ml of suspension A; 2) While stirring suspension A, slowly add 1 mol / L dilute ammonia water to it until pH = 8. After the pH value is constant, let it stand and precipitate for 3 h, and then dry it at 120 °C for 12 h to evaporate the liquid to obtain precipitate B; 3) Weigh 0.0683 g of RuCl₃ and prepare it into 30 ml of aqueous solution, and evenly drop it on precipitate B, stir magnetically at room temperature for 12 h, and then dry it at 120 °C for 12 h to evaporate the liquid to obtain solid powder C; 4) Calcine the solid powder C at 400 °C in an air atmosphere for 4 h, and finally use a tubular furnace to raise the temperature to 460 °C at a heating rate of 2 °C / min in a H₂ atmosphere of 25 ml / min and reduce it for 4 h to prepare a Ni-Mo-Ru / m-HZSM-5 trimetallic supported catalyst with a metal loading of 3.33 wt% for all.

[0043] The nickel-molybdenum-platinum-palladium four-metal supported catalysts prepared in Examples 1-5 of the present invention and the catalysts prepared in Comparative Examples 1-5 were used in the catalytic hydrogenation reaction of bio-crude oil model compounds. Four parts of stearic acid and one part of hexadecanamide were taken as the mixed microalgae bio-crude oil model compounds, and together with 5 parts of the above catalysts and 3.2 parts of formic acid, they were added to the reaction kettle and reacted at 300 °C for 2 h. Then, the reaction kettle was rinsed with dichloromethane. After filtration through filter paper and secondary rinsing with dichloromethane, the product was fixed in a volumetric flask. 1.5 ml of the product was taken, filtered twice through a filter head, and then discharged into a chromatographic vial to prepare a product sample. The conversion rate of stearic acid-hexadecanamide was measured by GC (gas chromatography), and the specific data are shown in Table 1. After GC detection, the raw material conversion rate of Example 2 of the present invention was excellent, solving the problem of difficult co-removal of nitrogen and oxygen by conventional catalysts, and confirming the superiority of the nickel-molybdenum-platinum-palladium four-metal supported catalyst prepared by the present invention in catalytic performance.

[0044] Table 1 shows the conversion rate data of stearic acid-hexadecanamide for the catalysts prepared in Examples and Comparative Examples of the present invention in the catalytic hydrogenation reaction of bio-crude oil model compounds.

[0045] As Figure 1 shown, it is a bar graph of the conversion rate of stearic acid-hexadecanamide for the catalysts prepared under the conditions of Examples 1-5 and Comparative Examples 1-5 of the present invention in the catalytic hydrogenation reaction of bio-crude oil model compounds. From Figure 1 this, it can be concluded that Example 2 of the present invention has the best catalytic performance and the highest conversion rate for this mixed bio-crude oil model compound, and the conversion rates of the examples are all greater than those of the comparative examples, indicating that the four-metal supported catalyst of the present invention has better performance than the comparative examples in the co-removal of oxygen and nitrogen in bio-oil catalytic hydrogenation.

[0046] As shown in Figure 2, it is the GC (gas chromatography) curves of stearic acid (Figure 2 (a)) and hexadecanamide (Figure 2 (b)) after the catalysts prepared under the conditions of Examples 1-5 and Comparative Examples 1-5 of the present invention were used in the catalytic hydrogenation reaction of bio-crude oil model compounds. The residual concentrations of stearic acid and hexadecanamide after the reaction can be approximately inferred from the peak area size combined with the standard curve. As can be seen from Figure 2, there is almost no peak in Example 2 of the present invention, so it can be obtained that the residual concentrations of stearic acid and hexadecanamide after the reaction approach 0. Stearic acid is a saturated fatty acid (C18H 36 O2), and the oxygen atom comes from the carboxylic acid group (-COOH). The oxygen content of this compound is 11.25%; hexadecanamide belongs to amide compounds (C 16 H 33 NO), its nitrogen atom comes from the amide group (-CONH2), and the oxygen atom comes from the carbonyl group (C=O). The oxygen content of this compound is 6.17%, and the nitrogen content is 5.40%. Therefore, it can be obtained that the catalyst prepared by the present invention has excellent co-removal performance of nitrogen and oxygen.

[0047] As shown in Figure 3, it is a pie chart of the reaction products (only compounds with a total peak area percentage ≥ 1% are marked) of the catalytic hydrogenation reaction of the bio - crude oil model compound prepared under the conditions of Example 2 (Figure 3(a)) and Comparative Example 3 (Figure 3(b)) of the present invention and without a catalyst (Figure 3(c)). It can be seen from Figure 3(c) that the product analysis of the blank sample includes C 36 H 72 O2, C 34 H 68 O3, C 35 H 70 O and other long - chain organic compounds, as well as C 17 H 36 long - chain alkanes with a peak area ratio of only 12.16%, indicating that the simple high - temperature hydrogenation reaction without a catalyst will promote the esterification reaction of stearic acid to dehydrate and condense into long - chain organic compounds; in addition, there is no nitrogen element in the product, so it is speculated that hexadecanamide is converted into a long - chain organic compound that is insoluble in dichloromethane, and there is only one kind of effective product, C 17 H 36 One kind, and the deoxygenation and denitrification efficiency is extremely low. By comparing Figure 3(a) and Figure 3(b), it can be seen that the types and proportions of the effective products (hydrocarbons) of Example 2 are more than those of Comparative Example 3 and the blank sample. For example, long - chain alkanes with molecular formulas of C 16 H 34 , C 21 H 44 , and long - chain alkenes with molecular formulas of C 18 H 36 (1 - octadecene, 7 - octadecene). It can be obtained that the catalyst prepared in Example 2 has excellent oxygen - nitrogen co - removal performance.

[0048] As shown in Figure 4, it is a peak area diagram of the reaction products (hydrocarbons (Figure 4(a)) and nitrogen - and oxygen - containing by - products (Figure 4(b))) of the catalyst prepared under the conditions of Example 2 and Comparative Example 3 of the present invention for the catalytic hydrogenation reaction of the bio - crude oil model compound. It can be known from Figure 4(a) that the peak area values of the hydrocarbons, that is, the effective products, of Example 2 are all greater than those of Comparative Example 3, indicating that the concentration and yield of the effective products after the reaction are high. It can be known from Figure 4(b) that the peak area values of the residual reactants such as stearic acid (C 18 H 36 O2) and hexadecanamide (C 16 H 33 NO) of Example 2 are lower than those of Comparative Example 3, indicating that the concentration of the residual reactants of Example 2 is lower, that is, the conversion rate of Example 2 is higher. And the C 18 H 35 N, C 18 H 37The peak area value of nitrogen and oxygen-containing by-products such as NO is equal to or higher than that of this compound in Comparative Example 3, indicating a higher by-product concentration. Combining with Figure 4(a), it can be seen that: within the same volume of the sample, the reaction products of Example 2 are more diverse, and the product concentration is higher, indicating that the reaction is more complete and the raw material utilization rate is higher. In summary, the catalytic performance of Example 2 of the present invention is more excellent.

[0049] As shown in Figure 5, it is the SEM electron micrograph of the catalysts prepared under the conditions of Example 2 (Figure 5(a)), Comparative Example 5 (Figure 5(b)), Comparative Example 3 (Figure 5(c)) and Comparative Example 1 (Figure 5(d)) of the present invention. It can be seen from Figure 5(a) that the carrier shape of the catalyst prepared in Example 2 is relatively regular, the metal loading is evenly distributed inside and on the surface of the ZSM-5 carrier, the metal loading particles are obvious, and the individual particle size is small, indicating that there is no multi-metal loading adhesion situation, and the carrier wrapping is thin, which is beneficial to the catalytic reaction. It can be seen from Figure 5(b) that the catalyst carrier prepared in Comparative Example 5 is in the form of irregular stacked flakes, the pore structure is chaotic, and a large amount of metal loading aggregates on the surface of the carrier, with general catalytic performance and poor cycle life. It can be seen from Figure 5(c) and Figure 5(d) that the metal loading particles of the catalysts prepared in Comparative Example 3 and Comparative Example 1 are larger, the carrier wrapping is thick, which is not conducive to hydrogen diffusion, active site binding and metal loading to play a role. In summary, the carrier structure of Example 2 is stable, the metal loading is evenly distributed, and the catalytic performance is good.

[0050] As Figure 6 shown, it is the energy spectrum diagram of the catalyst prepared under the conditions of Example 2 of the present invention. It can be seen from the figure that the distribution of each metal loading element in the catalyst is uniform and there is no agglomeration phenomenon. And the concentration of each metal element approaches 1:1:1:1, which conforms to the experimental scheme design, indicating that the loading rate of each metal element is relatively high, further proving the feasibility of the co-precipitation-impregnation synergistic loading method, and reflecting the excellent performance of the catalyst prepared in Example 2.

[0051] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A preparation method of a four-metal supported catalyst, characterized in that, Including: Take dry ZSM-5 molecular sieve, nickel nitrate hexahydrate and ammonium molybdate, add deionized water and mix them to prepare suspension A; Adjust the pH value of suspension A to alkaline, let it stand for precipitation, and after drying, obtain precipitate B; Take palladium dichloride and chloroplatinic acid hexahydrate to prepare a mixed solution, uniformly drip it onto precipitate B, stir, and after drying, obtain solid powder C; The solid powder C is calcined in an air atmosphere and reduced in a reducing atmosphere to prepare a four-metal supported catalyst.

2. The preparation method of a four-metal supported catalyst according to claim 1, wherein The mass-volume ratio of the ZSM-5 molecular sieve, nickel nitrate hexahydrate, ammonium molybdate to deionized water is (0.8~0.96) g : (0.0495~0.248) g : (0.0204~0.102) g : (20~30) mL.

3. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The standing precipitation time is 3~5 h, the drying temperature of precipitate B is 80~120 °C, and the drying time is 6~18 h.

4. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The mass ratio of palladium dichloride to chloroplatinic acid hexahydrate is (0.0166~0.0832) : (0.0209~0.104).

5. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The mass-volume ratio of precipitate B to the mixed solution is (1.025~1.200) g : (20~30) mL.

6. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The drying temperature of solid powder C is 80~120 °C, and the drying time is 6~18 h.

7. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The calcination temperature is 350~450 °C, and the calcination time is 3~4 h.

8. The preparation method of a four-metal supported catalyst according to claim 1, characterized in that, The reducing atmosphere is H2, the reduction temperature is 440~480 °C, and the reduction time is 4~6 h.

9. A four-metal supported catalyst prepared by the preparation method according to any one of claims 1~8.

10. Application of the four-metal supported catalyst according to claim 9 in the catalytic hydrodenitrogenation and oxygen co-removal and upgrading of microalgae bio-oil.

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