Catalyst for coupling of ethanol to produce butadiene, preparation method and application thereof
By introducing carbonates or bicarbonates into rare earth phosphate catalysts to form porous structures and loading transition metals, the problems of insufficient activity and stability of existing catalysts are solved, and a highly efficient process for the production of butadiene from ethanol is realized.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2026-02-06
- Publication Date
- 2026-06-09
AI Technical Summary
Existing catalysts for the production of butadiene from ethanol have shortcomings in terms of activity, stability, and process feasibility, making it difficult to achieve industrial application.
By using rare earth phosphates as supports and introducing carbonates or bicarbonates as structural modifiers to form porous supports, and loading transition metals, catalysts with high specific surface areas were prepared.
It significantly improves the yield of butadiene and the stability of the catalyst, and has good prospects for industrial application.
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Figure CN122164449A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical catalysis technology, and relates to a catalyst, preparation method and application of ethanol coupling to prepare butadiene. Background Technology
[0002] 1,3-Butadiene (C4H6) is a key basic chemical raw material. As a classic representative of conjugated dienes, it exhibits strong reactivity and is widely used in the production of synthetic resins, synthetic rubbers, butanediol, adiponitrile, and nylon-66. Currently, it is mainly produced industrially as a byproduct of ethylene production. Methods for preparing butadiene include fraction extraction and oxidative dehydrogenation of butane or butene. These methods all rely on the cracking of petrochemical resources and generally suffer from high energy consumption, equipment corrosion, and low atom economy. In recent years, with the continuous advancement of bioethanol and coal-based ethanol technologies, the development of a one-step synthesis route from ethanol has demonstrated advantages such as mild reaction conditions, high atom utilization, and simple gas-liquid separation. This route is of significant value for the development of biomass resources and the advancement of national energy strategies, and represents a highly promising research direction for the future.
[0003] Catalyst research for ethanol-to-butadiene production includes Zr, Y, Ta, and Cu-based systems. Among them, Zr-based catalysts (such as Mg-Zr / MFI) [Green Chem., 2020, 22 (9): 2852-2861] have low cost, suitable Lewis acid activity, butadiene selectivity of up to 74.6%, and good stability, but Zr species agglomeration is prone to occur at high space velocities. Y-based catalysts (such as Zn-Y / Beta) [ACS Catal., 2017, 7 (5): 3703-3706] have unique acid-base synergistic effects and can significantly improve CC coupling efficiency through single-atom anchoring and zeolite confinement strategies, but carbon deposition is prone to occur during long-term operation. Ta-based materials (such as Ta / SBA-15) [Appl. Catal. B, 2014, 150-151: 596-604] exhibit strong Lewis acid activity and excellent resistance to carbon deposition, maintaining high selectivity. However, their highly dispersed synthesis process is complex, limiting their large-scale application. Cu-based catalysts (such as Cu@S-1) [J.Catal., 2022, 413: 565-574] demonstrate excellent performance in the ethanol dehydrogenation step, exhibiting high acetaldehyde selectivity and good stability. However, when coupled with subsequent Lewis acid catalysts, the reactant ratio needs precise control to avoid hindering the MPVO reaction. Overall, each system has its own characteristics in terms of activity, stability, and process feasibility, requiring further optimization. Therefore, developing a catalyst with a simple synthesis method and high activity, selectivity, and stability holds promise for the industrial-scale production of butadiene from ethanol dehydrogenation. Summary of the Invention
[0004] The purpose of this invention is to address the shortcomings of existing technologies by providing a rare-earth phosphate-supported metal catalyst for the coupling of ethanol to butadiene. This invention is the first to propose introducing carbonates or bicarbonates (such as NH4HCO3, Na2CO3, etc.) as structural modifiers during the synthesis of rare-earth phosphates (LaPO4, ZrPO4, CePO4), followed by removal of the carbonates or bicarbonates during calcination to form a porous support with a high specific surface area. Compared to catalysts without carbonates, the prepared carbonate / bicarbonate-treated catalyst exhibits a significantly higher specific surface area, thereby significantly improving the butadiene yield. Subsequently, loading transition metals (such as Zn, Co, Cu, etc.) further enhances the ethanol conversion, achieving a high butadiene yield and demonstrating promising industrial application prospects.
[0005] The technical solution of the present invention:
[0006] A catalyst for the coupling of ethanol to prepare butadiene is a transition metal-supported rare earth phosphate, which is prepared by introducing carbonate or bicarbonate as a structural modifier.
[0007] The catalyst comprises the following components by weight percentage:
[0008] Rare earth phosphates are used as supports, and their general formula is MPO4, where M is selected from one or more combinations of La, Ce, and Zr.
[0009] Structural modifiers are carbonates or bicarbonates introduced during catalyst preparation and ultimately removed by calcination, with the general formula MCO3 or MHCO3, where M is selected from NH4. + Na + Ca 2+ ;
[0010] The active component is a transition metal supported on a support, selected from one or more combinations of Co, Cu, Zn, Ag, and Y; the loading of the transition metal is 0.02 wt.%-3 wt.% based on the weight of the support.
[0011] The transition metals are prepared using nitrates, chlorides, acetylacetones, sulfates, or acetates as precursors.
[0012] A method for preparing a catalyst for the coupling of ethanol to butadiene, comprising the following steps:
[0013] S1. Preparation of rare earth phosphate supports modified with carbonates or bicarbonates:
[0014] (1) Prepare aqueous solutions of rare earth metal salts and phosphates with concentrations of 0.05~0.5 mol / L respectively;
[0015] (2) Under stirring conditions, the rare earth metal salt aqueous solution is slowly added dropwise to the phosphate aqueous solution at a volume ratio of 1:1, and the reaction is continued to be stirred at room temperature for 30 to 60 minutes to obtain a rare earth phosphate precipitate mixture.
[0016] (3) Slowly add 0.01~1.0 mol / L of carbonate or bicarbonate aqueous solution to the rare earth phosphate precipitate mixture, and continue the reaction at room temperature for 30~60 minutes; the amount of carbonate or bicarbonate aqueous solution added is in the volume ratio of V(MPO4):V(MCO3). - The ratios of MPO4 and MHCO3 are 1:1 and 1:2, respectively.
[0017] (4) The product obtained in step (3) is filtered and dried, and then calcined in an air atmosphere at 250~550 °C for 1~5 hours to obtain a rare earth phosphate support modified with carbonate or bicarbonate; during this process, carbonate or bicarbonate decomposes and escapes to form a porous structure.
[0018] S2. Load on the transition metal:
[0019] (5) Prepare a salt solution containing the desired transition metal, with a concentration of 0.08~1.0 g / mL; the solvent is water, methanol, ethanol, a mixture of water and alcohol, or a mixture of methanol and ethanol.
[0020] (6) Using the equal volume impregnation method, the salt solution prepared in step (5) is impregnated onto the rare earth phosphate carrier obtained in step (4), and left to stand at room temperature for 0.5 to 2 hours.
[0021] (7) Dry the impregnated material at 50 ℃ for 8~20 hours;
[0022] (8) The dried material is calcined in an air atmosphere at 250~550 ℃ for 1~5 hours to obtain a transition metal supported rare earth phosphate catalyst, which is a catalyst for the coupling of ethanol to prepare butadiene.
[0023] A method for preparing butadiene by ethanol coupling involves introducing ethanol feedstock into a catalyst-supported reactor via a carrier gas at a reaction temperature of 200–500 °C and a reaction pressure of 1–50 atm. The reaction gas flow rate is [missing information]. It directly catalyzes the conversion of ethanol into butadiene.
[0024] The preferred reaction temperature is 275~350 °C, the preferred reaction pressure is atmospheric pressure, and the preferred reaction gas flow is... .
[0025] The reactor is preferably a fixed-bed reactor or an atmospheric pressure reactor.
[0026] The reaction mass hourly space velocity (HHSV) is 0.01–5 h⁻¹. -1 Preferably, 0.5~2.0 h -1 .
[0027] The carrier gas is a reactive inert gas such as nitrogen, argon, or helium.
[0028] The beneficial effects of this invention are as follows: The catalyst provided by this invention exhibits high butadiene selectivity and good renewability. This is mainly attributed to the introduction of carbonate / bicarbonate during the synthesis process, which decomposes during calcination to generate gases (such as CO2 and H2O), significantly increasing the specific surface area of the catalyst. This structure not only facilitates the adsorption and condensation of acetaldehyde intermediates but also provides more active sites for subsequent metal loading. Simultaneously, the supported metals, such as Zn, are chemically bonded to the phosphate groups on the surface of rare earth phosphates, exhibiting strong chemical interactions and ensuring the stability of the supported metals under reaction conditions. Attached Figure Description
[0029] Figure 1 This shows the correspondence between the physical properties of the catalyst and the spectra of carbon dioxide temperature-programmed desorption. Detailed Implementation
[0030] The following technical solutions and accompanying drawings further illustrate the specific embodiments of the present invention.
[0031] Example 1
[0032] Preparation process of Zn-supported bicarbonate-treated LaPO4 catalyst:
[0033] (1) Prepare a certain concentration of La(NO3)3 solution and (NH4)2HPO4 solution according to the chemical reaction molar ratio, mix them evenly at room temperature and react for 30 min;
[0034] (2) Key modification steps: Take 0.04 mol / L NH4HCO3 solution and add it to the mixed solution in step (1). Mix and react at room temperature for 30 min. This step introduces bicarbonate, which plays a role in pore formation and structure guidance in subsequent calcination.
[0035] (3) The mixture obtained in step (2) is filtered and dried, and then calcined in air at 400 °C for 2 h to decompose and release bicarbonate, forming a porous structure, and obtaining NH4HCO3 modified LaPO4 support (corresponding to number 2 in Table 1).
[0036] (4) Weigh a certain amount of the carrier obtained in step (3) and dry it at 120 °C for 2 hours to remove the surface physically adsorbed water;
[0037] (5) At 25 °C, take a certain concentration of The carrier obtained in step (4) was impregnated with an aqueous solution using the equal volume impregnation method and left to stand for 2 hours.
[0038] (6) The mixture after standing in step (5) is dried at 50 °C for 10 h to obtain the catalyst precursor;
[0039] (7) The catalyst precursor obtained in step (6) was oxidized and calcined in air at 400 °C for 2 h to obtain a 1.0 wt. % Zn-supported LaPO4 catalyst (corresponding to number 2 in Table 1).
[0040] (8) By adjusting the concentration of the Zn(NO3)2 aqueous solution, catalysts with different Zn loadings can be prepared using the same method as above, corresponding to numbers 3 (0.5 wt. % Zn) and 4 (2.5 wt. % Zn) in Table 1. The preparation conditions and processes for other catalysts are the same as in Example 1. The correspondence between sample numbers and preparation conditions is shown in Table 1.
[0041] Table 1. Correspondence between sample numbers and preparation conditions in Example 1
[0042]
[0043] Example 2
[0044] Preparation process of Zn and Y bimetallic supported bicarbonate modified LaPO4 catalyst:
[0045] (4) Weigh a certain amount of LaPO4 catalyst and dry it at 120 °C for 2 hours to remove the surface physically adsorbed water;
[0046] (5) At 25 °C, take the sample prepared from item 2 in Table 2. Aqueous solutions and those prepared in Table 2, No. 17 The LaPO4 obtained by the equal volume impregnation step (4) was left to stand for 2 hours;
[0047] (6) The mixture after step (5) is allowed to stand is dried at 50 °C for 10 h to obtain the catalyst precursor;
[0048] (7) The catalyst precursor obtained in step (6) was oxidized in air at 400 °C for 2 h to obtain (No. 12 in Table 1) 0.5Zn0.5Y-LaPO4 catalyst.
[0049] Example 3
[0050] LaPO4 catalysts modified with bicarbonate supported by different transition metals catalyze the production of butadiene from ethanol.
[0051] The production of butadiene from ethanol was carried out in a fixed-bed reactor using ethanol as a raw material. The reaction conditions were as follows: a catalyst was packed in a fixed-bed reactor with an inner diameter of 8 mm, the reaction was carried out at atmospheric pressure, the reaction temperature was 350 °C, and the ethanol mass hourly space velocity was 0.73 h⁻¹. -1 After the reaction stabilized, the reactants and products were analyzed using online chromatography. The correspondence between sample number and ethanol conversion activity is shown in Table 3.
[0052] Table 2 shows the correspondence between sample numbers and ethanol activity and butadiene selectivity in Example 3.
[0053]
[0054] Example 4
[0055] This embodiment investigated the effect of reaction temperature on the catalytic performance of the preferred catalyst Zn-LaPO4-N (i.e., catalyst number 2 in Example 1, which has a composition of 1.0 wt.% Zn supported on an NH4HCO3-modified LaPO4 support) in the production of butadiene from ethanol.
[0056] The production of butadiene from ethanol was carried out in a fixed-bed reactor using ethanol as a raw material. The reaction conditions were as follows: a catalyst was packed in a fixed-bed reactor with an inner diameter of 8 mm, the reaction was carried out at atmospheric pressure, the reaction temperature was 200-350 °C, and the ethanol mass hourly space velocity was 0.73 h⁻¹. -1 After the reaction stabilized, the reactants and products were analyzed using online chromatography. The correspondence between sample number and ethanol conversion activity is shown in Table 3.
[0057] Table 3 shows the relationship between the reaction temperature and the catalytic activity of 1.0 Zn-LaPO4 in the production of butadiene from ethanol in Example 4.
[0058]
[0059] Example 5
[0060] Compare the physical properties of Zn-LaPO4-A and Zn-LaPO4-N catalysts.
[0061] The correspondence between the physical properties of the catalyst and the spectra of carbon dioxide temperature-programmed desulfurization is shown in Table 4 and the attached figure.
[0062] Table 4 shows the correspondence between sample numbers and their physical properties in Example 5.
[0063]
Claims
1. A catalyst for the coupling of ethanol to prepare butadiene, characterized in that, The catalyst is a transition metal-supported rare earth phosphate, which is prepared by introducing carbonates or bicarbonates as structural modifiers.
2. The catalyst for the coupling of ethanol to prepare butadiene according to claim 1, characterized in that, The catalyst comprises the following components by weight percentage: Rare earth phosphates are used as supports, and their general formula is MPO4, where M is selected from one or more combinations of La, Ce, and Zr. Structural modifiers are carbonates or bicarbonates introduced during catalyst preparation and ultimately removed by calcination, with the general formula MCO3 or MHCO3, where M is selected from NH4. + Na + Ca 2+ ; The active component is a transition metal supported on a support, selected from one or more combinations of Co, Cu, Zn, Ag, and Y; the loading of the transition metal is 0.02 wt.%-3 wt.% based on the weight of the support.
3. The catalyst for the coupling of ethanol to prepare butadiene according to claim 2, characterized in that, The transition metals are prepared using nitrates, chlorides, acetylacetones, sulfates, or acetates as precursors.
4. A method for preparing a catalyst for the coupling of ethanol to butadiene according to any one of claims 1-3, characterized in that, The steps are as follows: S1. Preparation of rare earth phosphate supports modified with carbonates or bicarbonates: (1) Prepare aqueous solutions of rare earth metal salts and phosphates with concentrations of 0.05~0.5 mol / L respectively; (2) Under stirring conditions, the rare earth metal salt aqueous solution is slowly added dropwise to the phosphate aqueous solution at a volume ratio of 1:1, and the reaction is continued to be stirred at room temperature for 30 to 60 minutes to obtain a rare earth phosphate precipitate mixture. (3) Slowly add 0.01~1.0 mol / L of carbonate aqueous solution or bicarbonate aqueous solution to the rare earth phosphate precipitate mixture and continue the reaction at room temperature for 30~60 minutes; the amount of carbonate aqueous solution or bicarbonate aqueous solution added is according to the volume ratio of V(MPO4):V(MCO3)=1:1, V(MPO4):V(MHCO3)=1:2, etc. (4) The product obtained in step (3) is filtered and dried, and then calcined in an air atmosphere at 250~550 °C for 1~5 hours to obtain a rare earth phosphate support modified with carbonate or bicarbonate; during this process, carbonate or bicarbonate decomposes and escapes to form a porous structure. S2. Load on the transition metal: (5) Prepare a salt solution containing the desired transition metal, with a concentration of 0.08~1.0 g / mL; the solvent is water, methanol, ethanol, a mixture of water and alcohol, or a mixture of methanol and ethanol. (6) Using the equal volume impregnation method, the salt solution prepared in step (5) is impregnated onto the rare earth phosphate carrier obtained in step (4), and left to stand at room temperature for 0.5 to 2 hours. (7) Dry the impregnated material at 50 ℃ for 8~20 hours; (8) The dried material is calcined in an air atmosphere at 250~550 ℃ for 1~5 hours to obtain a transition metal supported rare earth phosphate catalyst, which is a catalyst for the coupling of ethanol to prepare butadiene.
5. A method for preparing butadiene by coupling ethanol, characterized in that, Under reaction conditions of 200–500 °C and 1–50 atm, ethanol feedstock is introduced into a catalyst-supported reactor via a carrier gas, with a reaction gas flow rate of [missing information]. It directly catalyzes the conversion of ethanol into butadiene.
6. The method for preparing butadiene by coupling ethanol according to claim 5, characterized in that, The reaction temperature is 275~350 °C, the reaction pressure is atmospheric pressure, and the reaction gas flow is... .
7. The method for preparing butadiene by coupling ethanol according to claim 5, characterized in that, The reactor is a fixed-bed reactor or an atmospheric pressure reactor.
8. The method for preparing butadiene by coupling ethanol according to claim 5, characterized in that, The reaction mass space velocity is .
9. The method for preparing butadiene by coupling ethanol according to claim 5, characterized in that, The carrier gas is nitrogen, argon, or helium.