A molecular sieve-supported bimetallic catalyst and its preparation method and use

Abstract

The present invention belongs to the field of catalyst technology and relates to a molecular sieve-loaded bimetallic catalyst and its preparation method and use, which are used to solve the technical problems of poor catalytic activity, low 2-methylfuran production and complex product composition when catalyzing furfural hydrogenation with existing catalysts. The present invention adopts a wet impregnation method to prepare an acidic ZSM-5 molecular sieve-loaded Cu-Ni bimetallic catalyst. The constructed Cu-Ni bimetallic Ni1Cu3.8(111) crystal plane is used to tiltly adsorb furfural molecules, selectively hydrogenate the carbonyl group to generate the intermediate product furfuryl alcohol, the regular pore structure of the ZSM-5 molecular sieve promotes the adsorption of reactant molecules, and the acid center on the molecular sieve surface catalyzes the cleavage of the carbon-oxygen bond in the intermediate product furfuryl alcohol molecule to generate dimethylfuran. The designed catalyst has excellent catalytic performance. When the total loading of the Cu-Ni bimetallic active component is 8%, the selectivity of 2-methylfuran is as high as about 83%, and the yield is as high as about 80%.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalysts and relates to a molecular sieve-supported bimetallic catalyst and a preparation method and application thereof. Background Art

[0002] Due to the depletion of traditional fossil energy, the utilization of green renewable biomass energy has become a research focus in recent years (ACS Sustainable Chem Eng 2016, 4 (9): 4506). Furfural (FUR), as a representative of α, β-unsaturated aldehydes, is derived from the hydrolysis of hemicellulose by xylose dehydration sequencing and has received considerable attention as one of the most promising biomass model molecules (ACS Catal 2020, 10 (8), 4770). There are many possible pathways for the conversion of furfural into more valuable chemicals. For example, the selective hydrogenolysis of the CO bond in furfural to 2-methylfuran (2-MeF) is desirable because it not only has intrinsically good fuel properties (high octane number, RON = 103; low water solubility, 7 g / L), but can also be regarded as a typical product of the reaction pathway required in bio-oil upgrading, that is, removing O while maintaining high C yield (Appl Catal B: Environ 2019, 254, 560).

[0003] Cu-Cr bimetallic catalysts exhibit excellent catalytic performance and have been used for decades in the industrial production of 2-methylfuran, but face serious environmental problems due to Cr leaching (JEnergy Chem 2021, 60, 16). For monometallic-Cu catalysts in furfural conversion, selective hydrogenation of aldehyde functions is easier to achieve than hydrogenolysis of CO bonds. Furfural is converted to 2-methylfuran by η 1 The (O)-coordinated model is adsorbed on Cu, where η 1 (O)-surface species bind active metals, leading to high hydrogenation activity for C=O bonds, along with the production of FOL (furfuryl alcohol). To enhance the deoxygenation of copper-based catalysts, the addition of a second oxophilic metal, high reaction temperatures, or the introduction of Lewis acids have proven effective. In particular, noble-metal-free bimetallic / multimetallic catalysts (CuFe, CuCo, CuAl, CuMgAl, CuZnAl, and CuNiMgAl) have demonstrated excellent catalytic performance in the liquid-phase catalytic upgrading of furfural to produce 2-methylfuran (Catal Commun 2015, 58, 6).

[0004] In addition to metal active sites, supports also play an important role in the conversion of furfural. Supports with different compositions and porosity, such as modified mesoporous silica, molecular sieves, carbon, metal organic frameworks (MOFs) and titanium oxide, have been studied for the conversion of furfural (Chin J Catal 2015, 36(7), 933). Among various supports, molecular sieves with high surface area, good hydrothermal stability and tunable acidity have attracted great attention. In addition, the molecular sieve microenvironment, such as the coordination framework ions of the metal, can also significantly affect the conversion of furfural. For example, SBA-15-supported metal catalysts showed better catalytic performance than unstructured silica in the selective hydrogenation of furfural to FOL, which was attributed to the uniform cylindrical channels of SBA-15 (J Catal 2015, 327, 65). The Cu-Co / ZSM-5 catalyst with high metal dispersion exhibits excellent performance for the HDO of furfural (1,6-hexanediol), producing 55 wt% of 2-methylfuran in 2-propanol at 220 °C with complete conversion of furfural.

[0005] Nickel-based catalysts have the advantages of low price and high H2 activation activity, and are expected to replace precious metal-based catalysts for furfural hydrogenation (Appl Catal B: Environ 2017, 203, 227). For copper and nickel bimetallics, alloy formation is easy because the atoms are close in size and have a similar crystal structure (face-centered cubic), which has been shown to be very effective in hydrogenation. For example, patent CN111135857A discloses a method for preparing a reduced catalyst and its use, which comprises the following steps: (1) weighing a certain amount of nickel nitrate and cobalt salt or copper salt or molybdate, dissolving them in water to obtain a metal salt solution, and adding an HZSM-5 carrier to the metal salt solution to obtain a suspension; (2) placing the suspension sample on a shaker for immersion reaction for a period of time at room temperature, taking it out, and evaporating the water under certain temperature conditions to obtain a solid sample; (3) placing the solid sample in a reactor and reducing it in a hydrogen atmosphere at 250-600°C for 1-10 hours to obtain a reduced catalyst; wherein the molar ratio of Ni:M in the reduced catalyst is (1-10):(1-5), the total mass of the active metal components NiO and MO is 10-50% of the total mass of the carrier and the metal oxide; and M is metal Co, Mo or Cu. Although the patent also uses the catalyst prepared therein for the catalytic hydrogenation of furfural, the catalyst prepared therein has the problem of a large active component loading but poor catalytic activity, and in the process of catalytic hydrogenation preparation of furfural, the amount of 2-methylfuran produced is extremely small and the product composition is relatively complex.

[0006] Therefore, it is very necessary to explore a catalyst with low active ingredient loading to efficiently and selectively catalyze furfural hydrogenation and prepare 2-methylfuran with high selectivity and high yield. Summary of the Invention

[0007] To address the technical issues of existing catalysts in furfural hydrogenation, such as poor catalytic activity, low 2-methylfuran production, and complex product composition, the present invention proposes a molecular sieve-supported bimetallic catalyst, its preparation method, and its use. The catalyst designed with an optimized Cu / Ni ratio exhibits excellent catalytic performance. When the total loading of the Cu-Ni bimetallic active components is 8wt%, the selectivity for 2-methylfuran reaches a maximum of approximately 83%, the furfural conversion is greater than 97%, and the yield reaches a maximum of approximately 80%.

[0008] In order to achieve the above object, the technical solution of the present invention is achieved as follows:

[0009] A method for preparing a molecular sieve-supported bimetallic catalyst comprises the following steps:

[0010] (1) Stirring the template and aluminum source at room temperature until uniformly mixed to obtain solution A;

[0011] (2) mixing deionized water and a silicon source, adding the mixture to the solution A obtained in step (1), and stirring at room temperature until uniform to obtain a synthetic liquid gel;

[0012] (3) subjecting the synthetic lyogel obtained in step (2) to hydrothermal treatment, and after the hydrothermal treatment, washing, drying, and calcining to obtain a ZSM-5 molecular sieve precursor;

[0013] (4) adding an ammonium salt solution to the ZSM-5 molecular sieve precursor obtained in step (3), performing ion exchange, washing with water, drying II, and repeating the ion exchange, washing with water, and drying II; and then calcining to obtain a ZSM-5 molecular sieve;

[0014] (5) dissolving a copper source and a nickel source in water to prepare a Cu-Ni bimetallic solution; mixing the Cu-Ni bimetallic solution with the ZSM-5 molecular sieve obtained in step (4), and sequentially stirring, drying III, calcining, and reducing to obtain a molecular sieve-supported bimetallic catalyst.

[0015] In the step (1), the template agent is any one or more of tetrapropylammonium hydroxide, tetrapropylammonium bromide and the like; the aluminum source is an organic aluminum compound (such as aluminum isopropoxide C9H 21 Any one or more of aluminum chloride (such as aluminum chloride AlCl3, aluminum sulfate Al2(SO4)3) or its complex (such as aluminum chloride hexahydrate AlCl3·6H2O, aluminum sulfate 18hydrate Al2(SO4)3·18H2O).

[0016] Preferably, the aluminum source in step (1) is aluminum isopropoxide.

[0017] The silicon source in step (2) is silica gel, fumed silica, inorganic silicate (such as sodium silicate Na2SiO3), organic silicate (such as ethyl orthosilicate C8H 20 O4Si), white carbon black or silicic acid (such as orthosilicic acid H4SiO4, metasilicic acid H2SiO3) any one or more.

[0018] Preferably, the organic silicate in step (2) is ethyl orthosilicate.

[0019] The molar ratio of silicon source, aluminum source, template, and deionized water in the synthetic lyogel is 100:(0.5-4):(30-50):(3000-4000). Controlling this ratio can achieve the goal of adjusting the molecular sieve's silicon-aluminum ratio, pore properties, acidity, and grain morphology and size.

[0020] In step (3), the hydrothermal treatment temperature is 130°C to 200°C, and the hydrothermal treatment time is 24h to 168h; the pH value after water washing is neutral; the drying temperature I is 80°C to 120°C, and the drying time I is 8h to 12h; the calcination atmosphere is air atmosphere, the calcination temperature is 300°C to 650°C, and the calcination time is 4h to 12h. Regulating the temperature and time of the hydrothermal treatment can improve the stability of the molecular sieve, adjust the acidity and pore structure of the molecular sieve, and have a direct impact on the crystallinity of the molecular sieve; the drying treatment is mainly to remove moisture from the molecular sieve; and the calcination treatment is mainly to remove excess templates, thereby constructing a rich pore structure.

[0021] In the step (4), the ammonium salt is NH4Cl, and the concentration of the ammonium salt solution is 1M; the stirring temperature of the ion exchange is 85°C, and the stirring time of the ion exchange is 3 hours; based on the mass of the ZSM-5 molecular sieve precursor, 125 mL of ammonium salt solution is added per gram of the ZSM-5 molecular sieve precursor; the ion exchange is repeated at least once; and the pH value after washing is neutral.

[0022] In the step (4), the drying temperature of the drying step II is 80° C. to 120° C., and the drying time of the drying step II is 8 hours to 12 hours; the calcination atmosphere is air atmosphere, the calcination temperature is 300° C. to 650° C., and the calcination time is 4 hours to 12 hours.

[0023] In step (5), the copper source is copper sulfate or copper nitrate; the nickel source is nickel nitrate or nickel chloride; the concentration of Cu ions in the Cu-Ni bimetallic solution is 0.43456 μM to 0.84233 μM, and the concentration of Ni ions in the Cu-Ni bimetallic solution is 0.11453 μM to 0.46919 μM.

[0024] In step (5), the mass ratio of the Cu-Ni bimetallic solution to the ZSM-5 molecular sieve is 1.8:1; the drying temperature in step III is 30°C to 120°C, and the drying time in step III is 6 hours to 18 hours; the calcination atmosphere is air, the calcination temperature is 300°C to 650°C, and the calcination time is 4 hours to 12 hours; the reduction atmosphere is hydrogen, the reduction temperature is 450°C to 650°C, and the reduction time is 4 hours to 12 hours. For the molecular sieve that has undergone ammonium ion exchange, it will only become a hydrogen-type molecular sieve after calcination, thereby improving the acidity of the molecular sieve; the reduction treatment is to transform the metal component from an oxide form to a catalytically active elemental form. These elemental or bimetallic alloy structures are active centers for catalytic hydrogenation.

[0025] Preferably, in step (5), the drying temperature of step III is 30° C. to 120° C., and the drying time of step III is 18 hours.

[0026] Preferably, the drying III in step (5) is gradient drying, and the operation is: first drying at 30°C for 6 hours, then drying at 60°C for 6 hours, and finally drying at 120°C for 6 hours.

[0027] The molecular sieve-supported bimetallic catalyst prepared by the above-described preparation method has a total Cu and Ni loading of 8wt%, with the Cu loading being 4wt% ≤ Cu loading < 8wt%, and the balance being Ni loading. Under this low metal loading condition, the Cu-Ni metallic components in the Cu-Ni alloy can be highly uniformly dispersed.

[0028] The molecular sieve-supported bimetallic catalyst is used in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to prepare 2-methylfuran.

[0029] The present invention has the following beneficial effects:

[0030] 1. The present invention adopts the wet impregnation method to prepare the acidic ZSM-5 molecular sieve loaded Cu-Ni bimetallic catalyst. An appropriate amount of Ni is added to Cu as a promoter to improve the activity and / or selectivity of the catalyst by changing the electronic coordination environment of Cu. The introduced Ni can also serve as a Lewis acid site to polarize the C=O bond in furfural. The constructed Cu-Ni bimetallic Ni1Cu3.8(111) crystal plane is used to adsorb furfural molecules, and the carbonyl group is selectively hydrogenated to generate the intermediate product furfuryl alcohol. The regular pore structure of the ZSM-5 molecular sieve promotes the adsorption of reactant molecules, and the acid center on the molecular sieve surface catalyzes the breaking of the carbon-oxygen bond in the intermediate product furfuryl alcohol molecule to generate dimethylfuran. At a lower metal loading (total loading is not higher than 8wt%), the introduction of a small amount of Ni metal in the Cu metal center improves the metal dispersion ( Figure 1-4), the utilization rate of the active centers of the constructed high-Cu and low-Ni alloy was significantly improved, further accelerating the reaction process of furfural hydrodeoxygenation to prepare 2-methylfuran.

[0031] 2. During the preparation of the catalyst, the present invention can change the form of the metal center by regulating the loading amount and ratio of different metals in the molecular sieve, including single metal form or alloy form with different crystal structures (Examples 1-5, Figure 2-5 ); By using different carriers, the influence of the carrier on the reaction process is explored (the commercial carriers of Examples 16-17 and the molecular sieve-loaded bimetallic catalysts prepared in other embodiments of the present invention). During the preparation of the molecular sieve, the silicon-aluminum ratio of the molecular sieve is changed by regulating the ratio of the silicon source to the aluminum source in the synthesis liquid, thereby regulating the acid properties of the molecular sieve (Examples 6-9); by regulating the crystallization temperature and time, etc., the crystallinity, pore structure and acid properties of the molecular sieve can be regulated (Examples 10-15). The above control methods can construct different alloy types and the dispersion of metal active centers, which will have a significant impact on the hydrodeoxygenation reaction process.

[0032] 3. The catalyst designed in the present invention has excellent catalytic performance. When the ZSM-5 molecular sieve-loaded Cu-Ni bimetallic catalyst is used in the process of hydrodeoxygenation of biomass-derived furfural compounds to produce dimethylfuran, when the total loading of the Cu-Ni bimetallic active component is 8wt%, the selectivity of 2-methylfuran is as high as about 83%, the furfural conversion rate is greater than 97%, and the yield is as high as about 80%. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0034] Figure 1 These are SEM images of the molecular sieve-loaded bimetallic catalysts prepared in Examples 1-5 of the present invention; (a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4; and (e) Example 5.

[0035] Figure 2 This is a TEM image of the molecular sieve-supported bimetallic catalyst prepared in Example 1 of the present invention.

[0036] Figure 3TEM images of the molecular sieve-loaded bimetallic catalyst prepared in Example 3 of the present invention; including (a) TEM; (b) dark field image; (c) metal particle size distribution image; (d) high-resolution TEM; (e) Ni element mapping image; (f) Cu element mapping image; and (g) metal selection line scan image.

[0037] Figure 4 TEM images of the molecular sieve-loaded bimetallic catalyst prepared in Example 5 of the present invention; including (a) TEM image; (b) dark field image; (c) metal particle size distribution image; (d) high-resolution TEM image; (e) Ni element mapping image; (f) Cu element mapping image; and (g) metal selection line scan image.

[0038] Figure 5 XRD patterns of the molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 of the present invention.

[0039] Figure 6 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 of the present invention at 200°C.

[0040] Figure 7 This is a comparative diagram of the distribution of various products obtained by catalyzing the hydrodeoxygenation of furfural at 200° C. using the molecular sieve-supported bimetallic catalyst prepared in Examples 1-5 of the present invention.

[0041] Figure 8 This is a comparison chart of the yield of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 of the present invention at 200°C.

[0042] Figure 9 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 3 and 6-9 of the present invention at 200°C.

[0043] Figure 10 This is a comparison chart of the yield of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 3 and 6-9 of the present invention at 200°C.

[0044] Figure 11 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by molecular sieve-supported bimetallic catalysts prepared in Examples 3, 16, and 17 of the present invention at 200°C.

[0045] Figure 12 This is a comparison chart of the yield of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 3, 16, and 17 of the present invention at 200°C. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without creative work are within the scope of protection of the present invention.

[0047] The water used in the present invention is all deionized water, and the reagents used are all analytically pure reagents.

[0048] Example 1

[0049] A method for preparing a molecular sieve-supported metal catalyst, wherein the Cu loading is 8 wt %, the Ni loading is 0 wt %, and the silicon-aluminum ratio (Si / Al) is 100; the steps are as follows:

[0050] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0051] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0052] (3) Weigh 3.042 g of copper nitrate, then add 14.958 g of deionized water, and stir at room temperature for 30 minutes to completely dissolve the metal, thereby preparing a metal solution containing Cu metal.

[0053] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve impregnated with Cu metal catalyst.

[0054] At this time, the theoretical loading amount calculated based on metal Cu is 8 wt %, and the theoretical loading amount calculated based on metal Ni is 0 wt %.

[0055] Example 2

[0056] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 1 only in that the Cu loading is 7 wt% and the Ni loading is 1 wt%; the other steps are the same as Example 1; the steps are as follows:

[0057] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0058] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0059] (3) Weigh 2.661 g of copper nitrate and 0.496 g of nickel nitrate, then add 14.843 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0060] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0061] At this time, the theoretical loading amount calculated based on metal Cu is 7 wt %, and the theoretical loading amount calculated based on metal Ni is 1 wt %.

[0062] Example 3

[0063] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 1 only in that the Cu loading is 6 wt% and the Ni loading is 2 wt%; the other steps are the same as Example 1; the steps are as follows:

[0064] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0065] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0066] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0067] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0068] At this time, the theoretical loading amount calculated based on metal Cu is 6 wt %, and the theoretical loading amount calculated based on metal Ni is 2 wt %.

[0069] Example 4

[0070] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 1 only in that the Cu loading is 5 wt% and the Ni loading is 3 wt%; the other steps are the same as Example 1; the steps are as follows:

[0071] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0072] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0073] (3) Weigh 1.901 g of copper nitrate and 1.486 g of nickel nitrate, then add 14.613 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0074] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0075] At this time, the theoretical loading amount calculated based on metal Cu is 5 wt %, and the theoretical loading amount calculated based on metal Ni is 3 wt %.

[0076] Example 5

[0077] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 1 only in that the Cu loading is 4 wt% and the Ni loading is 4 wt%; the other steps are the same as Example 1; the steps are as follows:

[0078] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0079] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0080] (3) Weigh 1.521 g of copper nitrate and 1.982 g of nickel nitrate, then add 14.497 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0081] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0082] At this time, the theoretical loading amount calculated based on metal Cu is 4 wt %, and the theoretical loading amount calculated based on metal Ni is 4 wt %.

[0083] Examples 1 to 5 are a series of catalysts prepared using different metal loadings in the process of preparing Cu-Ni bimetallic catalysts. The characterization of this series of catalysts is as follows Figure 1 、 Figure 2 、 Figure 3 、 Figure 4 and Figure 5 shown.

[0084] Figure 1 The SEM images of the molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 of the present invention are shown below: (a) Example 1; (b) Example 2; (c) Example 3; (d) Example 4; (e) Example 5. Figure 1It can be seen that the prepared catalysts all have a hexagonal morphology, the average particle size of the nanocrystals is 300-600 nm, and the difference in metal content has no significant effect on the morphology of the catalyst.

[0085] Figure 2 This is a TEM image of the molecular sieve-supported bimetallic catalyst prepared in Example 1 of the present invention. Figure 2 It can be observed that the molecular sieve particles are about 400 nm, which is consistent with the phenomenon observed in the SEM image. In addition, it is also observed that the metal particles are obviously aggregated and distributed on the catalyst surface, with a size of more than 50 nm.

[0086] Figure 3 TEM images of the molecular sieve-supported bimetallic catalyst prepared in Example 3 of the present invention; (a) TEM; (b) dark field image; (c) metal particle size distribution; (d) high-resolution TEM; (e) Ni element mapping; (f) Cu element mapping; (g) metal selection line scan. Figure 3 It can be observed that the metal particles are evenly distributed on the surface of the catalyst. The average particle size of the metal particles is 12.2 nm, and the crystal plane belonging to CuNi(111) (d=0.208 nm) can be observed from the high-resolution transmission electron microscopy image. The EDS line scan results show that Cu and Ni are evenly distributed, indicating that a CuNi alloy is formed in the catalyst synthesized in Example 3.

[0087] Figure 4 TEM images of the molecular sieve-supported bimetallic catalyst prepared in Example 5 of the present invention; (a) TEM image; (b) dark field image; (c) metal particle size distribution image; (d) high-resolution TEM image; (e) Ni element mapping image; (f) Cu element mapping image; (g) metal selection line scan image. Figure 4 It can be observed that the metal particles are uniformly distributed on the catalyst surface. The average particle size of the metal particles is statistically determined to be 8.9 nm. The (d = 0.208 nm) and Ni(111) observed in the high-resolution transmission electron microscopy images are attributed to the lattice planes of CuNi(111) (d = 0.208 nm) and Ni(111), respectively, indicating that as the Ni content increases and the Cu content decreases, an isolated Ni metal phase appears in the metal alloy. In addition, EDS line scan results also demonstrate that the Cu and Ni in the catalyst synthesized in Example 5 are unevenly distributed. In addition to forming a CuNi alloy, a portion of free single metal Ni is also present.

[0088] Figure 5The XRD patterns of the molecular sieve-loaded bimetallic catalysts prepared in Examples 1-5 of the present invention. By comparing the pdf card (JCPDS-44-0003) in the Jade software, it can be found that all the prepared catalysts have a typical MFI molecular sieve crystal form. For the XRD pattern of Example 1, a characteristic diffraction peak attributable to Cu (111) was observed at a double diffraction angle of about 43°. For the XRD patterns of Example 2, Example 3, and Example 4, a characteristic diffraction peak attributable to 3.8Cu1Ni (111) was observed between a double diffraction angle of 43°-44°, proving that a CuNi alloy was formed. For the XRD pattern of Example 5, in addition to observing the characteristic diffraction peak attributable to 3.8Cu1Ni (111), a characteristic diffraction peak attributable to Ni (111) was also observed between a double diffraction angle of 44°-45°, indicating that as the Ni content further increases, a portion of Ni will exist in a free form.

[0089] The molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 were characterized for pore properties and acidity, as shown in Table 1.

[0090] Table 1 Pore properties and acid results of molecular sieve-supported bimetallic catalysts prepared in Examples 1-5

[0091]

[0092] Note: T-total acid content of catalyst; Acid; L-Lewis acid

[0093] From the results in Table 1, it can be seen that the molecular sieve-supported bimetallic catalysts prepared in each embodiment have a large pore volume (about 0.39 cm 3 g -1 ) and a larger specific surface area (about 330m 2 g -1 ), the silicon-aluminum ratio of the catalysts prepared in each embodiment is about 95, which is equivalent to the theoretical silicon-aluminum ratio (100). Comparing the acid density of each catalyst, it can be seen that as the Ni content in the catalyst increases and the Cu content decreases, the total acid content (T) of the catalyst gradually decreases, and The ratio of (B) acid to Lewis (L) acid also gradually decreased.

[0094] Example 6

[0095] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 3 only in that the amount of deionized water used and the silicon-aluminum ratio are different (200), and the other steps are the same as Example 3; the steps are as follows:

[0096] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.0306 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0097] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0098] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0099] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0100] At this time, the theoretical loading amount calculated based on metal Cu is 6 wt %, and the theoretical loading amount calculated based on metal Ni is 2 wt %. The theoretical silicon-to-aluminum ratio of the molecular sieve-supported bimetallic catalyst is 200.

[0101] Example 7

[0102] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 6 only in that the silicon-aluminum ratio is different (150), and the other steps are the same as Example 6; the steps are as follows:

[0103] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.0409 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0104] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0105] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0106] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0107] At this time, the theoretical loading amount calculated based on metal Cu is 6 wt %, and the theoretical loading amount calculated based on metal Ni is 2 wt %. The theoretical silicon-to-aluminum ratio of the molecular sieve-supported bimetallic catalyst is 150.

[0108] Example 8

[0109] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 6 only in that the silicon-aluminum ratio is different (50), and the other steps are the same as Example 6; the steps are as follows:

[0110] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.1225 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0111] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0112] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0113] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0114] At this time, the theoretical loading amount calculated based on metal Cu is 6 wt %, and the theoretical loading amount calculated based on metal Ni is 2 wt %. The theoretical silicon-to-aluminum ratio of the molecular sieve-supported bimetallic catalyst is 50.

[0115] Example 9

[0116] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 6 only in that the silicon-aluminum ratio is different (25), and the other steps are the same as Example 6; the steps are as follows:

[0117] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.2451 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 100°C for 12 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0118] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0119] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0120] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0121] At this time, the theoretical loading amount calculated based on metal Cu is 6 wt %, and the theoretical loading amount calculated based on metal Ni is 2 wt %. The theoretical silicon-to-aluminum ratio of the molecular sieve-supported bimetallic catalyst is 25.

[0122] The total acid content of the molecular sieve-supported bimetallic catalysts prepared in Examples 6-9 was measured, and the results are shown in Table 2.

[0123] Table 2 Total acid content of molecular sieve-supported bimetallic catalysts prepared in Examples 6-9

[0124]

[0125] It can be found from Table 2 that the actual silicon-aluminum ratio of the molecular sieve-supported bimetallic catalyst is close to the theoretical value, and as the silicon-aluminum ratio decreases, the total acid content of the catalyst gradually increases.

[0126] Example 10

[0127] A method for preparing a molecular sieve-supported bimetallic catalyst comprises preparing a ZSM-5 molecular sieve with a silicon-aluminum ratio (Si / Al) of 100 and impregnated with a Cu-Ni bimetallic catalyst, wherein the theoretical loading of Cu is 6 wt % and the theoretical loading of Ni is 2 wt %. The specific implementation process is as follows:

[0128] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0129] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0130] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0131] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 500°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 550°C for 6 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0132] Example 11

[0133] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 10 only in that the molecular sieve catalyst after being impregnated with a metal solution is calcined and reduced at different temperatures and times, i.e., the calcination temperature used in step (4) is 500° C. and the calcination time is 8 h; the reduction temperature used is 550° C. and the reduction time is 6 h. The specific implementation process is as follows:

[0134] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0135] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0136] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0137] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 500°C for 8 h in an air atmosphere, and then reduced in a tube furnace at 550°C for 6 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0138] Example 12

[0139] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 10 only in that the molecular sieve catalyst impregnated with the metal solution is calcined and reduced at different temperatures and times, i.e., the calcination temperature used in step (4) is 500° C. and the calcination time is 8 h; the reduction temperature used is 600° C. and the reduction time is 4 h. The specific implementation process is as follows:

[0140] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0141] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0142] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0143] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 500°C for 8 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0144] Example 13

[0145] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 10 only in that the molecular sieve catalyst impregnated with the metal solution is calcined and reduced at different temperatures and times, i.e., the calcination temperature used in step (4) is 550° C. and the calcination time is 6 h; the reduction temperature used is 550° C. and the reduction time is 4 h. The specific implementation process is as follows:

[0146] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0147] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0148] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0149] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 550°C for 4 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0150] Example 14

[0151] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 10 only in that the molecular sieve catalyst impregnated with the metal solution is calcined and reduced at different temperatures and times, i.e., the calcination temperature used in step (4) is 550° C. and the calcination time is 6 h; the reduction temperature used is 550° C. and the reduction time is 6 h. The specific implementation process is as follows:

[0152] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0153] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0154] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0155] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 550°C for 6 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve impregnated Cu-Ni bimetallic catalyst.

[0156] Example 15

[0157] A method for preparing a molecular sieve-supported bimetallic catalyst, which differs from Example 10 only in that the molecular sieve catalyst impregnated with the metal solution is calcined and reduced at different temperatures and times, i.e., the calcination temperature used in step (4) is 550° C. and the calcination time is 6 h; the reduction temperature used is 600° C. and the reduction time is 6 h. The specific implementation process is as follows:

[0158] (1) Weigh 10.8312 g of tetrapropylammonium hydroxide and 0.068 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 12.8472 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 170°C for 96 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120°C for 8 h, and calcined at 550°C in an air atmosphere in a muffle furnace for 6 h to obtain a ZSM-5 molecular sieve precursor.

[0159] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 120°C for 8 h, repeat this process twice, and finally calcine it at 550°C for 6 h to obtain ZSM-5 molecular sieve.

[0160] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0161] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying process, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 6 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0162] The effects of the calcination temperature and time, and the reduction temperature and time of the molecular sieve catalyst after impregnation with the metal solution in Examples 10-15 on the performance of the molecular sieve-supported bimetallic catalyst were studied, and the results are shown in Table 3.

[0163] Table 3 Parameters of molecular sieve-supported bimetallic catalysts prepared in Examples 10-15

[0164]

[0165] Note: T- total acid content of catalyst

[0166] As shown in Table 3, the calcination and reduction temperature processes did not significantly affect the acidity and pore structure of the catalysts. All catalysts showed similar pore volume, surface area and total acid content.

[0167] Example 16

[0168] Commercial Al2O3-supported Cu-Ni bimetallic catalyst was prepared by co-impregnation method using commercial Al2O3 as the support. The loading amounts of Cu and Ni were 6 wt% and 2 wt%, respectively. The steps are as follows:

[0169] (1) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0170] (2) 1 g of commercial Al2O3 was mixed with 1.8 g of the metal solution prepared in the previous step. After thorough stirring, the mixture was dried in a gradient manner: first at 30°C for 6 h, then at 60°C for 6 h, and finally at 120°C for 6 h. After the gradient drying, the product was calcined in a muffle furnace at 550°C for 6 h in an air atmosphere, and then reduced in a tube furnace at 600°C for 4 h in a H2 atmosphere to obtain a commercial Al2O3-impregnated Cu-Ni bimetallic catalyst.

[0171] Example 17

[0172] Commercial SiO2-supported Cu-Ni bimetallic catalyst was prepared by co-impregnation method using commercial SiO2 as the support. The loading amounts of Cu and Ni were 6 wt% and 2 wt%, respectively. The steps are as follows:

[0173] (1) Weigh 2.281 g of copper nitrate and 0.991 g of nickel nitrate, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0174] (2) Weigh 1 g of commercial SiO2 and mix it with 1.8 g of the metal solution prepared in the previous step. After thorough stirring, perform gradient drying: first drying at 30°C for 6 h, then drying at 60°C for 6 h, and finally drying at 120°C for 6 h. After the gradient drying is completed, the product is first calcined at 550°C in a muffle furnace under air atmosphere for 6 h, and then reduced at 600°C in a tube furnace under H2 atmosphere for 4 h to obtain a commercial SiO2-impregnated Cu-Ni bimetallic catalyst.

[0175] Example 18

[0176] A method for preparing a molecular sieve-supported bimetallic catalyst, the specific implementation process is as follows:

[0177] (1) Weigh 8.123 g of tetrapropylammonium bromide and 0.034 g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 11.883 g of deionized water and 6.9345 g of ethyl orthosilicate to the mixture and stir at room temperature for 6 h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 130°C for 168 h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 80°C for 9 h, and calcined at 300°C in an air atmosphere in a muffle furnace for 12 h to obtain a ZSM-5 molecular sieve precursor.

[0178] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 100°C for 10 h, repeat this process twice, and finally calcine it at 300°C for 12 h to obtain ZSM-5 molecular sieve.

[0179] (3) Weigh 2.281 g of copper sulfate and 0.991 g of nickel chloride, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0180] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 2 h, then at 60°C for 2 h, and finally at 120°C for 2 h. After the gradient drying process, the product was calcined in a muffle furnace at 300°C for 12 h in an air atmosphere, and then reduced in a tube furnace at 650°C for 7 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0181] Example 19

[0182] A method for preparing a molecular sieve-supported bimetallic catalyst, the specific implementation process is as follows:

[0183] (1) Weigh 13.538g of tetrapropylammonium bromide and 0.272g of aluminum isopropoxide into a flask and stir at room temperature until uniform. After stirring, add 13.812g of deionized water and 6.9345g of ethyl orthosilicate to the mixture and stir at room temperature for 6h. Then, place the synthetic solution prepared in the previous step into a hydrothermal reactor and perform static hydrothermal synthesis at 200℃ for 24h to obtain a hydrothermal product. The synthesized product is washed with water until neutral, dried at 120℃ for 8h, and calcined at 650℃ in a muffle furnace under air atmosphere for 4h to obtain a ZSM-5 molecular sieve precursor.

[0184] (2) Weigh 1 g of the product obtained in the previous step and mix it with 125 mL of 1 mol / L NH4Cl solution, stir it at 85°C for 3 h, wash it with deionized water until it is neutral, dry it at 80°C for 12 h, repeat this process twice, and finally calcine it at 650°C for 4 h to obtain ZSM-5 molecular sieve.

[0185] (3) Weigh 2.281 g of copper nitrate and 0.991 g of nickel chloride, then add 14.728 g of deionized water and stir at room temperature for 30 min to completely dissolve the metals, thereby preparing a metal solution containing a Cu-Ni bimetallic.

[0186] (4) 1 g of ZSM-5 molecular sieve was mixed with 1.8 g of the metal solution prepared in the previous step, stirred thoroughly, and then dried in a gradient drying process: first at 30°C for 4 h, then at 60°C for 4 h, and finally at 120°C for 4 h. After the gradient drying process, the product was calcined in a muffle furnace at 650°C for 4 h in an air atmosphere, and then reduced in a tube furnace at 450°C for 12 h in a H2 atmosphere to obtain a ZSM-5 molecular sieve-impregnated Cu-Ni bimetallic catalyst.

[0187] Application Examples

[0188] The molecular sieve catalysts prepared in Examples 1 to 9, Example 16, and Example 17 were used in the furfural hydrodeoxygenation reaction. The specific operation is as follows:

[0189] 60 mL of isopropanol and 210 μL of furfural were mixed, followed by 320 μL of n-dodecane as an internal standard. The mixture was stirred thoroughly and placed in a high-temperature, high-pressure reactor. 0.05 g of the catalyst was added to the reactor, and H₂ was introduced to a pressure of 3 MPa. The reaction was carried out at a heating rate of 10°C / min, at a pressure of 3 MPa, at 200°C, for 1 hour, and the resulting product was analyzed by gas chromatography.

[0190] Figure 6 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by molecular sieve-supported bimetallic catalysts prepared in Examples 1-5 of the present invention at 200°C. Figure 6 As can be observed, the Cu-Ni bimetallic impregnated commercial ZSM-5 molecular sieve catalyst prepared in Example 3 exhibits the best catalytic activity. First, in terms of furfural conversion, as the proportion of Ni in the catalyst increases, the catalysts prepared in Examples 3, 4, and 5 achieve near-complete furfural conversion (>97%) under the stated reaction conditions.

[0191] Figure 7 This is a comparative diagram of the distribution of various products obtained by catalyzing the hydrodeoxygenation of furfural at 200°C using the molecular sieve-supported bimetallic catalyst prepared in Examples 1-5 of the present invention. Figure 7), the catalyst prepared in Example 3 can make the selectivity of the target product 2-methylfuran the highest (about 83%).

[0192] Figure 8 The figure shows the yield comparison of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalyst prepared in Examples 1-5 of the present invention at 200°C. Finally, from the perspective of the yield of the target product 2-methylfuran ( Figure 8 ), the catalyst prepared in Example 3 showed the highest yield (about 80%). This shows that ZSM-5 molecular sieve loaded with 6% by mass of Cu and 2% by mass of Ni exhibits better catalytic activity in the furfural hydrodeoxygenation reaction. Combined with the aforementioned TEM and XRD characterization results, it can be seen that the CuNi alloy accounts for the highest proportion in the catalyst prepared in Example 3, and the formation of the CuNi alloy is beneficial to its catalytic furfural hydrodeoxygenation, thereby exhibiting better catalytic activity.

[0193] Figure 9 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by molecular sieve-supported bimetallic catalysts prepared in Examples 3 and 6-9 of the present invention at 200°C. Figure 9 It can be seen that the Cu-Ni bimetallic impregnated ZSM-5 molecular sieve catalyst prepared in Example 3 exhibits the best catalytic activity, and the catalyst prepared in Example 3 exhibits a higher furfural conversion rate (>97%) under the reaction conditions.

[0194] Figure 10 This is a comparison chart of the yield of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 3 and 6-9 of the present invention at 200°C. Figure 10 It can be seen that the catalyst prepared in Example 3 exhibits the highest 2-methylfuran yield (>80%). This shows that low or high acidity is not conducive to the catalyst-catalyzed furfural hydrodeoxygenation, while appropriate acidity is conducive to the catalyst-catalyzed furfural hydrodeoxygenation. This may be because when the acidity is low, the catalyst activity is low, resulting in a low furfural conversion rate and 2-methylfuran yield in the furfural hydrodeoxygenation reaction. When the acidity is high, furfural or the target product 2-methylfuran may undergo side reactions such as deep hydrogenation, resulting in its catalytic activity being low.

[0195] Figure 11 This is a comparison chart of the conversion rates of furfural hydrodeoxygenation catalyzed by molecular sieve-supported bimetallic catalysts prepared in Examples 3, 16, and 17 of the present invention at 200°C. Figure 11It can be observed that the Cu-Ni bimetallic impregnated ZSM-5 molecular sieve catalyst prepared in Example 3 exhibits the best catalytic activity. The catalyst prepared in Example 3 exhibits a high furfural conversion rate (about 97%) under the reaction conditions. However, under the same reaction conditions, the furfural conversion rates of Examples 16 and 17 are 81% and 86%, respectively, which are lower than those of Example 3.

[0196] Figure 12 This is a comparison chart of the yield of 2-methylfuran in the product of furfural hydrodeoxygenation catalyzed by the molecular sieve-supported bimetallic catalysts prepared in Examples 3, 16, and 17 of the present invention at 200°C. Figure 12 It can be observed that the catalyst prepared in Example 3 exhibited the highest 2-methylfuran yield (approximately 80%), while the 2-methylfuran yields obtained in Examples 16 and 17 under the same reaction conditions were 47% and 53%, respectively, both lower than those in Example 3. This indicates that the use of ZSM-5 molecular sieve as a support for Cu and Ni metals exhibits superior performance in catalyzing the hydrodeoxygenation of furfural over commercial Al2O3 and commercial SiO2.

[0197] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. Use of a molecular sieve-supported bimetallic catalyst in catalyzing the hydrodeoxygenation of cellulose / hemicellulose-derived aldehyde compounds to produce 2-methylfuran, characterized in that: The total loading amount of Cu and Ni in the molecular sieve-supported bimetallic catalyst is 8 wt %, wherein the loading amount of Cu is 4 wt %≤Cu loading amount<8 wt %, and the balance is the loading amount of Ni; The preparation method of the molecular sieve-supported bimetallic catalyst comprises the following steps: (1) Stir the template and aluminum source at room temperature until evenly mixed to obtain solution A; (2) Mixing deionized water and a silicon source, adding the mixture to the solution A obtained in step (1), and stirring at room temperature until the mixture is uniform to obtain a synthetic liquid gel; (3) subjecting the synthetic lyogel obtained in step (2) to hydrothermal treatment, washing, drying, and calcining after the hydrothermal treatment to obtain a ZSM-5 molecular sieve precursor; (4) adding an ammonium salt solution to the ZSM-5 molecular sieve precursor obtained in step (3), performing ion exchange, washing with water, and drying II, and then repeating the ion exchange, washing with water, and drying II again; and then calcining to obtain a ZSM-5 molecular sieve; (5) Dissolving a copper source and a nickel source in water to prepare a Cu-Ni bimetallic solution; mixing the Cu-Ni bimetallic solution with the ZSM-5 molecular sieve obtained in step (4), and sequentially performing stirring, drying III, calcining, and reduction to obtain a molecular sieve-supported bimetallic catalyst.

2. Use of the molecular sieve-supported bimetallic catalyst according to claim 1 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In step (1), the template agent is tetrapropylammonium hydroxide or tetrapropylammonium bromide; the aluminum source is any one or more of an organic aluminum compound, pseudo-boehmite, aluminum gel, an inorganic acid aluminum salt or a complex thereof; and the silicon source in step (2) is any one or more of silica gel, fumed silica, an inorganic silicate, an organic silicate, white carbon black or silicic acid.

3. Use of the molecular sieve-supported bimetallic catalyst according to claim 1 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: The molar ratio of the silicon source, the aluminum source, the template and the deionized water in the synthetic liquid gel is 100:(0.5-4):(30-50):(3000-4000).

4. Use of the molecular sieve-supported bimetallic catalyst according to claim 1 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In the step (3), the hydrothermal treatment temperature is 130°C to 200°C, and the hydrothermal treatment time is 24 h to 168 h; the drying temperature I is 80°C to 120°C, and the drying time I is 8 h to 12 h; the roasting atmosphere is air atmosphere, the roasting temperature is 300°C to 650°C, and the roasting time is 4 h to 12 h.

5. Use of the molecular sieve-supported bimetallic catalyst according to claim 4 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In the step (4), the ammonium salt is NH4Cl, and the concentration of the ammonium salt solution is 1 M; the stirring temperature of the ion exchange is 85°C, and the stirring time of the ion exchange is 3 h; based on the mass of the ZSM-5 molecular sieve precursor, 125 mL of the ammonium salt solution is added per gram of the ZSM-5 molecular sieve precursor; and the ion exchange is repeated at least once.

6. Use of the molecular sieve-supported bimetallic catalyst according to claim 5 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In the step (4), the drying II temperature is 80°C to 120°C, and the drying II time is 8 h to 12 h; the roasting atmosphere is air atmosphere, the roasting temperature is 300°C to 650°C, and the roasting time is 4 h to 12 h.

7. Use of the molecular sieve-supported bimetallic catalyst according to claim 1 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In step (5), the copper source is copper sulfate or copper nitrate; the nickel source is nickel nitrate or nickel chloride; the concentration of Cu ions in the Cu-Ni bimetallic solution is 0.43456 μM~0.84233 μM, and the concentration of Ni ions in the Cu-Ni bimetallic solution is 0.11453 μM~0.46919 μM.

8. Use of the molecular sieve-supported bimetallic catalyst according to claim 7 in catalyzing the hydrodeoxygenation of aldehyde compounds derived from cellulose / hemicellulose to produce 2-methylfuran, characterized in that: In the step (5), the mass ratio of the Cu-Ni bimetallic solution to the ZSM-5 molecular sieve is 1.8:1; the drying temperature of step III is 30°C to 120°C, and the drying time of step III is 6h to 18h; the calcination atmosphere is an air atmosphere, the calcination temperature is 300°C to 650°C, and the calcination time is 4h to 12h; the reducing atmosphere is a hydrogen atmosphere, the reduction temperature is 450°C to 650°C, and the reduction time is 4h to 12h.

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