A catalyst for the one-step hydrogenation of furfural to 2-methyltetrahydrofuran and its preparation method thereof.

Abstract

This invention relates to the field of catalytic materials technology, and discloses a catalyst for the one-step hydrogenation of furfural to 2-methyltetrahydrofuran and its preparation method. The catalyst uses Mg-modified Al₂O₃ as a support, Ni as the main active component, and introduces Pt to form a bimetallic active phase. This invention modifies the support by introducing Mg to regulate its acid-base properties, thereby suppressing side reaction pathways and improving the selectivity of the target product.

Description

Technical Field

[0001] This invention relates to the field of catalytic materials technology, specifically to a Ni-Pt bimetallic catalyst and its application in the hydrogenation of furfural (FA) to prepare 2-methyltetrahydrofuran (2-MTHF). Background Technology

[0002] Furfural is an important biomass-based platform compound that can be prepared from agricultural and forestry wastes such as corn cobs, straw, sawdust, and bagasse through processes such as hydrolysis and dehydration. 2-Methyltetrahydrofuran is one of the important products of furfural hydrogenation conversion and can be used as a solvent, fuel additive, and intermediate in fine chemicals, showing application value in fine chemicals and new energy materials. Therefore, developing catalytic systems to achieve efficient conversion of furfural to 2-methyltetrahydrofuran has significant research and application value.

[0003] Currently, Ni-based catalysts are widely used in the hydrogenation reaction of furfural due to their low cost and high hydrogenation activity. However, traditional Ni-based catalysts supported on Al2O3 have numerous acidic sites on their surface, which can easily trigger side reactions during the reaction, leading to reduced selectivity for the target product. Furthermore, single-metal catalysts have limitations in controlling the reaction pathway, making it difficult to simultaneously achieve high conversion and high selectivity. Therefore, developing a catalytic system capable of controlling the acid-base properties of the support and optimizing the structure of active sites is of great significance.

[0004] Pt-based catalysts exhibit good selective hydrogenation performance on the C=O bond in furfural molecules, which is beneficial for improving the selectivity of specific hydrogenation pathways. However, the overall hydrogenation activity of single Pt catalysts is affected by the activation capacity of hydrogen and the metal dispersion, and the high amount of precious metals required limits their practical application.

[0005] Chinese patent CN105601592A discloses a continuous one-step process for preparing 2-methyltetrahydrofuran under atmospheric pressure. It employs a fixed-bed reactor with segmented Cu / SiO2 and Pd / SiO2 packing, enabling the further hydrogenation of furfural via the intermediate 2-methylfuran to produce 2-methyltetrahydrofuran. This method achieves high conversion and selectivity through multi-catalyst synergy in segmented processes, but the process is complex and the equipment cost is high.

[0006] International patent WO2023193425A1 discloses a method for preparing 2-methyltetrahydrofuran by hydrogenation of biomass platform molecules using a Cu-Ni bimetallic catalyst. While related technical solutions can achieve high conversion rates under certain conditions, some solutions rely on specific additives or high pressure conditions to maintain catalytic activity, and there is still room for further optimization of the process conditions.

[0007] In summary, existing technologies for the hydrogenation of furfural to 2-methyltetrahydrofuran still suffer from problems such as complex catalytic system composition, difficulty in balancing selectivity and activity, and stringent requirements for reaction conditions. In particular, achieving the direct one-step conversion of furfural to 2-methyltetrahydrofuran using a single catalyst system still has room for further optimization. Therefore, it is necessary to develop a catalytic system with a relatively simple structure that can achieve the conversion of furfural to 2-methyltetrahydrofuran in a single reaction step, while also possessing high activity and selectivity. Summary of the Invention

[0008] The purpose of this invention is to provide a Ni-Pt bimetallic catalyst that improves the selectivity of 2-methyltetrahydrofuran in the hydrogenation reaction of furfural by controlling the acid-base properties of the support and constructing a bimetallic synergistic system. Preferably, the above effect is achieved by modifying the support with Mg.

[0009] Figure 1 The main reaction pathway and possible side reaction pathways for the hydrogenation of furfural to prepare 2-methyltetrahydrofuran are described. Furfural is first hydrogenated to furfuryl alcohol, which is then further hydrogenated to tetrahydrofurfural alcohol, followed by a deoxygenation reaction to produce the target product, 2-methyltetrahydrofuran. During this process, side reactions may occur, generating byproducts such as tetrahydrofuran. The formation of tetrahydrofuran not only reduces the selectivity of the target product but also increases the difficulty of subsequent separation due to its close boiling point to the target product. Therefore, effectively controlling the reaction pathway and suppressing the occurrence of side reactions is key to improving the performance of this reaction system.

[0010] To achieve the above objectives, the present invention adopts the following technical solution:

[0011] This invention provides a Ni-Pt bimetallic catalyst, wherein the catalyst uses Mg-modified Al2O3 as a support and Ni-Pt as the active phase. The composition, based on metal content, is 30%~50 wt% for Ni and 2.5~3.5 wt% for Pt.

[0012] Furthermore, the molar ratio of Mg to Al in the Mg-modified Al2O3 is 1:3.

[0013] Furthermore, the catalyst incorporates Ni active components via co-precipitation and Pt active components via impregnation.

[0014] A second aspect of the present invention is to provide a method for preparing the catalyst, comprising the following steps:

[0015] (1) Dissolve nickel, aluminum and magnesium precursors in deionized water, add precipitant to precipitate, adjust pH to 7~10, and obtain NiO / MgAl precursors by aging, filtering, drying and calcining.

[0016] (2) The NiO / MgAl precursor was subjected to a first reduction treatment under a hydrogen atmosphere to obtain a Ni / MgAl catalyst;

[0017] (3) The Ni / MgAl catalyst was contacted with a platinum precursor solution, dried, and then subjected to a second reduction treatment under a hydrogen atmosphere to obtain the Ni-Pt / MgAl bimetallic catalyst.

[0018] Furthermore, the nickel precursor is one or more of nickel nitrate, nickel chloride, and nickel sulfate; the aluminum precursor is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; the magnesium precursor is one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate; and the platinum precursor is one or more of chloroplatinic acid, platinum chloride, and platinum nitrate.

[0019] Furthermore, the precipitant is selected from one or both of sodium hydroxide and sodium carbonate.

[0020] Furthermore, the calcination temperature is 300~500 ℃, and the calcination time is 1~5 h.

[0021] Furthermore, the first reduction temperature is 300~500 ℃ and the time is 1~5 h; the second reduction temperature is 300~500 ℃ and the time is 1~5 h.

[0022] A third aspect of the invention provides the application of the catalyst in the one-step hydrogenation of furfural to prepare 2-methyltetrahydrofuran. The hydrogenation reaction is carried out at 160–200 °C and 1–3 MPa hydrogen pressure, with a catalyst-to-furfural mass ratio of 1:10 to 1:100, and the reaction solvent is one or more of 1,4-dioxane, isopropanol, ethanol, and methanol. Attached Figure Description

[0023] Figure 1 The main reaction pathway and possible side reaction pathways for the hydrogenation of furfural to prepare 2-methyltetrahydrofuran.

[0024] Figure 2 HAADF-STEM and elemental distribution images of Ni-3%Pt / Mg1Al3.

[0025] Figure 3 The XRD pattern of Ni-3%Pt / Mg1Al3 is shown.

[0026] Advantages and beneficial effects of the present invention:

[0027] This invention effectively suppresses the formation of the byproduct tetrahydrofuran by modifying the acid-base properties of the support with Mg; the synergistic effect of Ni-Pt bimetallic catalysts improves the selectivity of the target product 2-methyltetrahydrofuran. A combination of co-precipitation and impregnation methods achieves synergistic optimization of the catalyst structure and surface activity. Experimental results show that the catalyst of this invention exhibits excellent performance in the hydrogenation reaction of furfural, significantly improving the selectivity of the target product and reducing the formation of byproducts at high conversion rates. Under optimized conditions, the furfural conversion rate can reach over 99%, the selectivity of 2-methyltetrahydrofuran can reach over 95%, and the selectivity of the byproduct tetrahydrofuran is only 2.1%. Detailed Implementation

[0028] The present invention will be further described in detail below through specific embodiments. The following embodiments are merely descriptive and not limiting, and should not be used to limit the scope of protection of the present invention.

[0029] Comparative Example 1

[0030] A method for preparing a Ni / Al₂O₃ catalyst includes the following steps: A certain amount of nickel nitrate and aluminum nitrate are weighed and dissolved in deionized water to prepare a mixed solution, resulting in a final Ni loading of 43 wt%. A mixed solution of sodium hydroxide and sodium carbonate is added under stirring to adjust the pH to 8-9. After stirring for 2 h, the solution is aged at 45 ℃ for 6 h. The precipitate is filtered and dried at 80 ℃ for 24 h.

[0031] The dried solid was placed in a muffle furnace and calcined at 450 °C for 3 h in air to obtain a NiO / Al2O3 precursor. Subsequently, it was reduced in a tube furnace at 500 °C in hydrogen atmosphere for 3 h to obtain a Ni / Al2O3 catalyst, denoted as CAT-1.

[0032] Furfural (1 mL), 1,4-dioxane (2 mL), and CAT-1 catalyst (0.1 g) were added to a 50 mL stainless steel high-pressure reactor. After sealing, the reactor was purged with hydrogen three times, and then purged with hydrogen to 3 MPa.

[0033] The reaction was carried out at 180 °C for 3 h with a stirring speed of 800 rpm. After the reaction was completed, the mixture was cooled to room temperature and the catalyst was separated by filtration.

[0034] The composition of the reaction solution was analyzed by gas chromatography. The results showed that the furfural conversion rate was 99.3%, the selectivity for 2-methyltetrahydrofuran was 17.4%, and the selectivity for tetrahydrofuran was 20.1%.

[0035] Comparative Example 2

[0036] Based on the Ni / Al2O3 catalyst prepared in Comparative Example 1, Pt was introduced by impregnation to achieve a loading of 3 wt%. After drying and reduction treatment, Ni-3%Pt / Al2O3 catalyst was obtained, denoted as CAT-2.

[0037] Catalyst CAT-2 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 99.6%, the selectivity of 2-methyltetrahydrofuran was 80.7%, and the selectivity of tetrahydrofuran was 15.6%.

[0038] Comparative Example 3

[0039] Magnesium and aluminum precursors were dissolved in deionized water. A mixed solution of sodium hydroxide and sodium carbonate was added under stirring to adjust the pH to 8-9, with a Mg / Al molar ratio of 1:3. The precipitate was then stirred, aged, and calcined to obtain a MgAl composite oxide support with a Mg / Al molar ratio of 1:3. Pt was introduced by impregnation to a loading of 3 wt%, stirred at room temperature for 12 h, dried, and then reduced at 350 ℃ under a hydrogen atmosphere for 3 h to obtain a 3% Pt / Mg1Al3 catalyst, denoted as CAT-3.

[0040] Catalyst CAT-3 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 50.9%, the selectivity of 2-methyltetrahydrofuran was 0.7%, and the selectivity of tetrahydrofuran was 3.1%.

[0041] Example 1

[0042] A method for preparing a Ni-3%Pt / Mg1Al3 bimetallic catalyst includes the following steps: (1) Dissolve nickel nitrate, magnesium nitrate and aluminum nitrate in deionized water, prepare a mixed solution with a Mg / Al molar ratio of 1:3 and a Ni loading of 43 wt%, add a mixed solution of sodium hydroxide and sodium carbonate dropwise under stirring, adjust the pH to 8~9, continue stirring for 2 h and then age at 45 ℃ for 6 h; filter the obtained precipitate and dry it at 80 ℃ for 24 h; (2) calcine the dried solid at 450 ℃ for 3 h in an air atmosphere in a muffle furnace to obtain a NiO / Mg1Al3 precursor, and then perform a first reduction treatment at 500 ℃ in a hydrogen atmosphere for 3 h to obtain a Ni / Mg1Al3 catalyst; (3) contact the Ni / Mg1Al3 catalyst with an aqueous solution of chloroplatinic acid, stir at room temperature for 12 h and then dry it, and perform a second reduction treatment at 350 ℃ in a hydrogen atmosphere for 3 h to obtain a Ni-3%Pt / Mg1Al3 catalyst, denoted as CAT-4.

[0043] Catalyst CAT-4 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 99.9%, the selectivity of 2-methyltetrahydrofuran was 95.1%, and the selectivity of tetrahydrofuran was 2.1%.

[0044] Figure 2 The images show the HAADF-STEM and elemental distribution of Ni-3%Pt / Mg1Al3. The HAADF-STEM results indicate that Ni is uniformly dispersed on the surface of the MgAl composite oxide support, with no obvious agglomeration observed. The Pt signal is weak but uniformly distributed, indicating that it exists in a highly dispersed form on the catalyst surface. Simultaneously, the uniform distribution of Mg and Al elements indicates a stable support structure without phase separation. The good spatial overlap between Ni and the support demonstrates strong metal-support interactions, which are beneficial for improving the stability and activity of the catalyst.

[0045] Figure 3 The XRD pattern of Ni-3%Pt / Mg1Al3 is shown. The XRD results indicate the presence of NiO and MgO characteristic diffraction peaks, with broad peak shapes, suggesting small grain size and good dispersion. No obvious Pt characteristic peaks were observed, indicating small or highly dispersed Pt particles. Furthermore, no Ni-Pt alloy characteristic peaks or significant peak shifts were detected, indicating that Ni and Pt do not form a bulk alloy structure, but rather exist mainly in a dispersed state or as an interfacial synergistic form. These results demonstrate that the catalyst of this invention possesses good structural uniformity and highly dispersed active sites, providing a structural basis for its excellent catalytic performance.

[0046] Comparative Example 4

[0047] The method of Example 1 was followed, except that the Pt loading was changed to 1 wt%, resulting in a Ni-1%Pt / Mg1Al3 catalyst, denoted as CAT-5.

[0048] Catalyst CAT-5 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 99.6%, the selectivity of 2-methyltetrahydrofuran was 53.1%, and the selectivity of tetrahydrofuran was 6.1%.

[0049] Comparative Example 5

[0050] The method of Example 1 was followed, except that the Pt loading was changed to 2 wt%, resulting in a Ni-2%Pt / Mg1Al3 catalyst, denoted as CAT-6.

[0051] Catalyst CAT-6 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 99.6%, the selectivity of 2-methyltetrahydrofuran was 81.5%, and the selectivity of tetrahydrofuran was 3.7%.

[0052] Comparative Example 6

[0053] The method of Example 1 was followed, except that the Mg / Al molar ratio was changed to 1:1 to obtain a Ni-3%Pt / Mg1Al1 catalyst, denoted as CAT-7.

[0054] Catalyst CAT-7 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 90.8%, the selectivity of 2-methyltetrahydrofuran was 80.7%, and the selectivity of tetrahydrofuran was 6.5%.

[0055] Comparative Example 7

[0056] The method of Example 1 was followed, except that the Mg / Al molar ratio was changed to 3:1 to obtain the Ni-3%Pt / Mg3Al1 catalyst, denoted as CAT-8.

[0057] The catalyst CAT-8 was used in the process of preparing 2-methyltetrahydrofuran by hydrogenation of furfural under the same reaction conditions as Comparative Example 1. The conversion rate of furfural was 79.7%, the selectivity of 2-methyltetrahydrofuran was 50.6%, and the selectivity of tetrahydrofuran was 0.9%.

[0058] Catalytic performance evaluation results of catalysts prepared in the examples and comparative examples

[0059]

[0060] The results showed that while the unmodified Ni / Al2O3 catalyst exhibited high conversion rates, it also generated a significant amount of tetrahydrofuran as a byproduct. Introducing Pt improved the selectivity of the target product, but side reactions still occurred. In contrast, by introducing Mg to regulate the acid-base properties of the support, the Ni-3%Pt / Mg1Al3 catalyst significantly reduced tetrahydrofuran formation while maintaining high conversion rates, and markedly improved the selectivity for 2-methyltetrahydrofuran.

[0061] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several modifications and improvements can be made without departing from the inventive concept, and these all fall within the protection scope of the present invention.

Claims

1. A catalyst for the one-step hydrogenation of furfural to 2-methyltetrahydrofuran, characterized in that, The catalyst uses Mg-modified Al2O3 as a support, and the active component is a bimetallic system formed by Ni and Pt; based on metal content, the Ni content is 30%~50wt% and the Pt content is 2.5%~3.5wt%.

2. The catalyst according to claim 1, characterized in that, The molar ratio of Mg to Al in the Mg-modified Al2O3 is 1:

3.

3. The catalyst according to claim 1, characterized in that, The catalyst incorporates Ni active components via co-precipitation and Pt active components via impregnation.

4. A method for preparing the catalyst according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Dissolve nickel, aluminum and magnesium precursors in deionized water, add precipitant to precipitate, adjust pH to 7~10, and obtain NiO / MgAl precursors by aging, filtering, drying and calcining. (2) The NiO / MgAl precursor was subjected to a first reduction treatment under a hydrogen atmosphere to obtain a Ni / MgAl catalyst; (3) The Ni / MgAl catalyst was contacted with a platinum precursor solution, dried, and then subjected to a second reduction treatment under a hydrogen atmosphere to obtain the Ni-Pt / MgAl bimetallic catalyst.

5. The preparation method according to claim 4, characterized in that, The nickel precursor is one or more of nickel nitrate, nickel chloride, and nickel sulfate; the aluminum precursor is one or more of aluminum nitrate, aluminum chloride, and aluminum sulfate; the magnesium precursor is one or more of magnesium nitrate, magnesium chloride, and magnesium sulfate; and the platinum precursor is one or more of chloroplatinic acid, platinum chloride, and platinum nitrate.

6. The preparation method according to claim 4, characterized in that, The selected precipitant is one or both of sodium hydroxide and sodium carbonate.

7. The preparation method according to claim 4, characterized in that, The roasting temperature is 300~500 ℃, and the roasting time is 1~5 h.

8. The preparation method according to claim 4, characterized in that, The first reduction temperature is 300~500 ℃ and the time is 1~5 h; the second reduction temperature is 300~500 ℃ and the time is 1~5 h.

9. The use of the catalyst according to any one of claims 1 to 3 in the one-step hydrogenation of furfural to prepare 2-methyltetrahydrofuran.

10. The application according to claim 9, characterized in that, The hydrogenation reaction is carried out at a hydrogen pressure of 1.0~3.0 MPa and a temperature of 160~200 °C. The mass ratio of catalyst to furfural is 1:10~1:100, and the reaction solvent is one or more of 1,4-dioxane, isopropanol, ethanol, and methanol.

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