Organic molecule modified cuprous oxide-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalyst preparation, in particular to an organic molecule modified cuprous oxide-based catalyst as well as a preparation method and application thereof. According to the catalyst, soluble copper salt is used as a precursor, heteroaromatic ring molecules are used as a coordination inducer, the copper salt and the heteroaromatic ring molecules are mixed to form a complex, a precipitator is added for precipitation, a reducing agent is added for reduction after sufficient precipitation, and then centrifugal washing and vacuum drying are performed to obtain the organic molecule modified cuprous oxide-based catalyst. In the catalyst prepared by the method, heteroaromatic ring molecules are used as organic molecules to form coordination with the surface of cuprous oxide, so that the electronic structure and the geometric structure of copper are effectively adjusted. Meanwhile, the microenvironment on the surface of cuprous oxide is improved by organic molecules, and adsorption of formaldehyde molecules is enhanced. The designed catalyst has the advantages of more rough and loose special morphology, high catalytic activity and high yield of 1, 4-butynediol.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to an organically modified cuprous oxide-based catalyst, its preparation method, and its application. Background Technology

[0002] 1,4-Butanediol, as an important chemical intermediate, has high-value-added downstream derivatives such as 1,4-butyrolactone (GBL), tetrahydrofuran (THF), polyurethane (PU), polybutylene terephthalate (PBT), and polybutylene terephthalate (PBAT), which are widely used in various fields such as pharmaceuticals, chemicals, textiles, papermaking, and daily chemicals. The preparation of 1,4-butanediol is currently mainly carried out through the formaldehyde-acetylene oxidation (BDO) process, which mainly includes the following two reactions: the first step involves formaldehyde and acetylene as raw materials reacting under the action of a copper catalyst to produce 1,4-butynediol (BYD); the second step involves the hydrogenation reduction reaction of 1,4-butynediol under the action of a nickel-based catalyst to produce 1,4-butanediol.

[0003] Previous studies have suggested that Cu is involved in the condensation reaction between formaldehyde and acetylene. 2+ Reduced to Cu by formaldehyde + Cu + It reacts with acetylene to form a cuprous acetylene complex, which serves as the true active center. Compared to other types of copper-based catalysts, cuprous oxide-based catalysts can eliminate the need for Cu. 2+ The complex reduction process is more conducive to the formation of cuprous acetylene active species. Furthermore, the Cu₂O surface exhibits a stronger activation effect on C=O in formaldehyde, synergistically adsorbing and activating C≡C and C=O bonds, promoting C-C coupling. To improve the catalytic activity of cuprous oxide-based catalysts, researchers have reported Cu₂O / MgO, Cu₂O / Al₂O₃, and Cu₂O / Fe₂O₃ catalysts modified with different promoters, as well as Cu₂O / TiO₂ catalysts supported on different supports. However, these catalysts still face challenges such as low catalytic activity and Cu… + It is easily reduced to Cu 0 The limited interaction between Cu₂O and supports such as MgO, Al₂O₃, and TiO₂ leads to a decrease in catalyst activity. Furthermore, insufficient adsorption strength of reaction intermediates and an imperfect CC coupling pathway result in the easy formation of polyacetylenes as byproducts, further reducing catalyst stability. Therefore, there is a need to develop more efficient and stable cuprous oxide-based acetylation catalysts.

[0004] In recent years, strategies such as additive doping, crystal plane engineering, and surface modulation have been widely used to improve the activity and stability of cuprous oxide-based catalysts. Among them, organic molecule modification of the copper surface is considered a new approach to regulate reaction pathways and enhance intermediate adsorption. Wang et al. (Shilun Wang, Wei Peng, Heliang Ma, et al. Theory-Guided Modification of Ionic Liquid on Cu2O Promotes Asymmetric CC Coupling for CO2 Conversion[J], ACS Catalysis,2025,15:14127-14137.) modified cuprous oxide with 1-butyl-3-methylimidazolium chloride (Bmim-Cu2O). The results showed that the introduction of ionic liquid enhanced the adsorption capacity of reaction intermediates and promoted asymmetric *CO-CHO coupling, thereby increasing the conversion of carbon dioxide to C. 2+ The conversion efficiency of the product. Ding et al. (Jie Ding, Fuhua Li, Xinyi Ren, et al. Molecular tuning boosts asymmetric C-Ccoupling for CO conversion to acetate[J], Nature Communications,2024,15:3641.) proposed a general surface molecular regulation strategy based on pyridine derivatives. When cuprous oxide nanocube catalysts modified with 4-mercaptopyridine were used in the electrochemical carbon monoxide reduction reaction, they exhibited a Faradaic efficiency of over 60% for acetate formation, with a current density as high as 380 mA / cm². 2 Studies have shown that 4-mercaptopyridine can effectively modulate the electronic structure of copper catalysts and enhance the adsorption of *CO and *CHO intermediates through hydrogen bonding stabilization, thereby significantly promoting asymmetric CO-CHO coupling. However, research and application of this type of organic molecule regulation strategy in the formaldehyde acetylation reaction are limited. In summary, the catalysts used in the formaldehyde acetylation reaction still have limitations in the application of Cu. + Problems include easy reduction, weak adsorption of reaction intermediates, low efficiency of CC coupling pathway, and easy formation of polyacetylenes. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an organically modified cuprous oxide-based catalyst, its preparation method, and its applications. Heteroaromatic ring molecules, acting as organic molecules, coordinate with copper species on the surface of the cuprous oxide-based catalyst, effectively improving the microenvironment of the cuprous oxide surface and enhancing the adsorption and activation of formaldehyde molecules on the catalyst surface. Simultaneously, the organic molecules regulate the electronic and geometric structures of copper, further stabilizing Cu.+ The active center enhances the adsorption capacity for acetylene molecules, significantly improving the catalytic performance of the catalyst, thus solving the problem of Cu in the catalyst used in the formaldehyde acetyleneification reaction. + Problems include easy reduction, weak adsorption of reaction intermediates, low efficiency of CC coupling pathway, and easy formation of polyacetylenes.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: The first objective of this invention is to provide a method for preparing an organically modified cuprous oxide-based catalyst, comprising the following steps: S1. Using soluble copper salt as a precursor and heteroaromatic ring molecules as coordination inducers, the mixture is prepared in a solvent system. The heteroaromatic ring molecules coordinate with copper ions to form a complex.

[0007] S2. A precipitant is added to the complex for precipitation, followed by the addition of a reducing agent for reduction aging, which reduces copper ions to form cuprous oxide. The heteroaromatic ring molecules coat the cuprous oxide to form cuprous oxide aggregates, thus obtaining an organically modified cuprous oxide-based catalyst.

[0008] In a preferred embodiment of the present invention, the molar ratio of soluble copper salt to heteroaromatic ring molecules is 5:0.5~3.

[0009] In a preferred embodiment of the present invention, the precipitant is sodium hydroxide, sodium carbonate, sodium bicarbonate or ammonia; the molar volume ratio of heteroaromatic ring molecules to precipitant is 0.5mol~3mol:50mL~150mL.

[0010] In a preferred embodiment of the present invention, the reducing agent is glucose, L-ascorbic acid, sodium borohydride or hydrazine hydrate; the molar volume ratio of heteroaromatic ring molecules and precipitant is 0.5mol~3mol:50mL~150mL.

[0011] In a preferred embodiment of the present invention, the heteroaromatic ring molecule is imidazole, 2-methylimidazolium, 2-aminobenzimidazole, 2-nitroimidazolium, pyrazole, 4-mercaptopyridine, or furan.

[0012] In a preferred embodiment of the present invention, the soluble copper salt is at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate.

[0013] In a preferred embodiment of the present invention, the aging time is 15 min to 90 min; the molar volume ratio of heteroaromatic ring molecules to solvent is 0.5 mol to 3 mol: 400 mL to 600 mL, and the solvent is water.

[0014] A second objective of this invention is to provide an organically modified cuprous oxide-based catalyst prepared by the above method.

[0015] A third objective of this invention is to provide the application of the above-mentioned organically modified cuprous oxide-based catalyst in the formaldehyde acetylene reaction.

[0016] In a preferred embodiment of the present invention, formaldehyde solution and acetylene are used as raw materials, and a formaldehyde acetylation reaction is carried out under constant pressure in the presence of an organically modified cuprous oxide-based catalyst to obtain 1,4-butynediol; the mass-volume ratio of the organically modified cuprous oxide-based catalyst to the formaldehyde solution is 2.5g:50mL, and the mass concentration of the formaldehyde solution is 37wt%~40wt%.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a method for preparing an organically modified cuprous oxide-based catalyst. A soluble copper salt is used as a precursor, and a heteroaromatic ring molecule is used as a coordination initiator. The mixture is stirred in a solvent system, where the heteroaromatic ring molecule coordinates with copper ions to form a complex. A precipitant is then added for precipitation. After sufficient precipitation, a reducing agent is added for reduction and aging, reducing copper ions to form cuprous oxide. The heteroaromatic ring molecule coats the cuprous oxide, forming cuprous oxide aggregates, thus obtaining the organically modified cuprous oxide-based catalyst. In this invention, the heteroaromatic ring molecule, as an organic molecule, coordinates with copper species on the catalyst surface, effectively improving the microenvironment of the cuprous oxide surface and enhancing the adsorption and activation of formaldehyde molecules on the catalyst surface. Simultaneously, the organic molecule regulates the electronic and geometric structures of copper, further stabilizing Cu. + The active center enhances the adsorption capacity for acetylene molecules, significantly improving the catalytic performance of the catalyst. This solves the problem of Cu content still present in catalysts used in the formaldehyde acetyleneification reaction. + Problems include easy reduction, weak adsorption of reaction intermediates, low efficiency of CC coupling pathway, and easy formation of polyacetylenes.

[0018] 2. The catalyst designed in this invention has the advantages of a rougher and more porous morphology, high catalytic activity, and high yield of 1,4-butynediol. Its preparation method is simple, the process conditions are easy to control, the raw materials are widely available and low in cost, and it has the potential for large-scale industrial production. Attached Figure Description

[0019] Figure 1 Cu2O, which is Comparative Example 1 of this invention NaOH,L-AA Catalyst and Im-Cu2O of Example 1 1:5,NaOH,L-AA XRD pattern of the -60 catalyst.

[0020] Figure 2 Cu2O, which is Comparative Example 1 of this invention NaOH,L-AA Catalyst and Im-Cu2O of Example 1 1:5,NaOH,L-AASEM image of the -60 catalyst. Figure 2 Figure a shows Cu2O in Comparative Example 1. NaOH,L-AA SEM images of the catalyst, b is Im-Cu2O from Example 1. 1:5,NaOH,L-AA SEM image of the -60 catalyst. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that the technical terms used in this invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0023] Existing organic molecule regulation strategies have limited research and application in the formaldehyde acetylation reaction. Furthermore, the catalysts used in the formaldehyde acetylation reaction still contain Cu. + The Cu₂O catalyst suffers from several problems, including easy reduction, weak adsorption of reaction intermediates, low efficiency of the CC coupling pathway, and easy formation of polyacetylenes. Organic molecules can construct unique local microenvironments on the catalyst surface, potentially improving the directional adsorption and activation of reactant molecules in the liquid phase, thereby further enhancing the selectivity of the reaction. Based on this, this invention constructs an organic molecular layer suitable for the formaldehyde acetylenelation reaction environment, achieving synergistic regulation of the electronic structure and surface microenvironment of the Cu₂O catalyst, thus significantly improving the activity, selectivity, and stability of Cu₂O-based catalysts.

[0024] First, this invention provides a method for preparing an organically modified cuprous oxide-based catalyst, comprising the following steps: (1) Dissolve the soluble copper salt and organic molecule in 400 mL to 600 mL of deionized water and stir for 5 min until evenly dispersed to obtain a copper complex solution. The organic molecule is a heteroaromatic ring molecule.

[0025] (2) Add 50 mL to 150 mL of a 2 mol / L precipitant solution to the copper complex solution. After the addition is complete, stir for 5 min to allow the precipitation to be complete.

[0026] (3) Add 50 mL to 150 mL of a reducing agent solution with a concentration of 1 mol / L to the above precipitate. After the addition is complete, age the precipitate for a period of time to allow it to be fully reduced. After the reaction is complete, centrifuge and wash the precipitate, and vacuum dry it at 60 °C for 12 h to obtain an organically modified cuprous oxide catalyst.

[0027] It should be noted that during the catalyst preparation process, organic molecules first act as coordination inducers and react with Cu. 2+ In solution, Cu-organic molecular complexes are formed; the presence of ligands reduces Cu levels. 2+ The concentration of "free" Cu and the change of Cu 2+ The surrounding local pH and coordination environment. The presence of organic molecules reduces the nucleation-growth rate differential during subsequent precipitation and reducing agent additions. Finally, the complexed Cu... 2+ When Cu2O is reduced to Cu2O, the Cu2O is surrounded by organic molecules, leading to the formation of primary Cu2O crystal nuclei. These nuclei then aggregate and adhere directionally, eventually forming rough-surfaced Cu2O agglomerates. In contrast, pure Cu2O prepared without the addition of organic molecules produces larger, smooth, spherical particles with uniform distribution and relatively dense surfaces.

[0028] The soluble copper salt may be selected from at least one of copper nitrate, copper sulfate, copper chloride, or copper acetate, preferably copper chloride.

[0029] The heteroaromatic ring molecule can be selected from imidazole, 2-methylimidazolium, 2-aminobenzimidazole, 2-nitroimidazolium, pyrazole, 4-mercaptopyridine, or furan, etc., preferably imidazole. Different heteroaromatic ring molecules have different coordination forms and coordination strengths with the copper salt, which in turn affects the degree of surface modification on cuprous oxide nucleation, leading to significant changes in the catalyst morphology and electronic structure. Weakly coordinated organic molecules may not modify the cuprous oxide surface, while excessively strong coordination may over-cover copper sites.

[0030] The molar ratio of the soluble copper salt to the organic molecule is 5:0.5~3, preferably 5:1.

[0031] The precipitant is sodium hydroxide, sodium carbonate, sodium bicarbonate, or ammonia. Sodium hydroxide is preferred because sodium carbonate, sodium bicarbonate, and ammonia, which are weakly alkaline precipitants, have poor precipitation effects or incomplete precipitation during the precipitation stage, thus affecting the nucleation of cuprous oxide in the subsequent reduction stage.

[0032] The reducing agent is glucose, L-ascorbic acid, sodium borohydride, or hydrazine hydrate, preferably L-ascorbic acid. This is because L-ascorbic acid has moderate reducing power, while glucose has weak reducing power, and sodium borohydride or hydrazine hydrate has excessively strong reducing power. Glucose's weak reducing power leads to insufficient reduction, while the excessively strong reducing power of sodium borohydride or hydrazine hydrate causes some cuprous oxide to be over-reduced to zero copper, resulting in a reduction in monovalent copper active sites.

[0033] The aging time is 15 min to 90 min, preferably 60 min. The purpose of aging is to ensure that the reduction reaction, crystal growth and phase stabilization processes are fully completed, thereby obtaining cuprous oxide with a more complete structure, purer phase and more stable properties.

[0034] Secondly, the present invention provides an organic molecule-modified cuprous oxide-based catalyst prepared by the above method.

[0035] Finally, this invention provides an application of the above-mentioned organically modified cuprous oxide-based catalyst in the formaldehyde acetylene reaction.

[0036] The process of the formaldehyde acetylene reaction is as follows: the reaction activity of the catalyst is evaluated in a high-pressure reactor, the amount of catalyst used is 2.5g, the amount of formaldehyde solution (concentration of 37wt%~40wt%) added is 50mL, the acetylene introduced into the reactor is kept constant at 0.6MPa, the reaction temperature is 90℃, and the reaction time is 10h.

[0037] The following specific examples will provide further explanation.

[0038] Example 1 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of imidazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and imidazole.

[0039] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and imidazole. After the addition is complete, stir for 5 min to form a precipitate.

[0040] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Im-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0041] Im-Cu2O 1:5,NaOH,L-AAThe subscript "1:5" in -60 indicates the molar ratio of organic molecules to copper salt, "NaOH" indicates that the precipitant used is sodium hydroxide, "L-AA" indicates that the reducing agent used is L-ascorbic acid, and "60" indicates that the aging time is 60 min, and the same applies below.

[0042] Example 2 The difference from Example 1 is that the amount of imidazole added is 0.005 mol, resulting in Im-Cu2O. 0.5:5,NaOH,L-AA -60 catalyst.

[0043] Example 3 The difference from Example 1 is that the amount of imidazole added is 0.015 mol, resulting in Im-Cu2O. 1.5:5,NaOH,L-AA -60 catalyst.

[0044] Example 4 The difference from Example 1 is that the amount of imidazole added is 0.02 mol, resulting in Im-Cu2O. 2:5,NaOH,L-AA -60 catalyst.

[0045] Example 5 The difference from Example 1 is that the amount of imidazole added is 0.03 mol, resulting in Im-Cu2O. 3:5,NaOH,L-AA -60 catalyst.

[0046] Example 6 The difference from Example 1 is that the precipitant sodium hydroxide is replaced with sodium carbonate to obtain Im-Cu2O. 1:5,Na2CO3,L-AA -60 catalyst.

[0047] Example 7 The difference from Example 1 is that the precipitant sodium hydroxide is replaced with sodium bicarbonate to obtain Im-Cu2O. 1:5,NaHCO3,L-AA -60 catalyst.

[0048] Example 8 The difference from Example 1 is that the precipitant sodium hydroxide is replaced with ammonia water to obtain Im-Cu2O. 1:5,NH3·H2O,L-AA -60 catalyst.

[0049] Example 9 The difference from Example 1 is that the reducing agent L-ascorbic acid was replaced with glucose to obtain Im-Cu2O. 1:5,NaOH,Glc -60 catalyst.

[0050] Example 10 The difference from Example 1 is that the reducing agent L-ascorbic acid was replaced with sodium borohydride to obtain Im-Cu2O. 1:5,NaOH,NaBH4 -60 catalyst.

[0051] Example 11 The difference from Example 1 is that the reducing agent L-ascorbic acid was replaced with hydrazine hydrate to obtain Im-Cu2O. 1:5,NaOH,N2H4·H2O -60 catalyst.

[0052] Example 12 The difference from Example 1 is that the aging time is 15 minutes, resulting in Im-Cu2O. 1:5,NaOH,L-AA -15 catalyst.

[0053] Example 13 The difference from Example 1 is that the aging time is 30 minutes, resulting in Im-Cu2O. 1:5,NaOH,L-AA -30 catalyst.

[0054] Example 14 The difference from Example 1 is that the aging time is 70 min, resulting in Im-Cu2O. 1:5,NaOH,L-AA -70 catalyst.

[0055] Example 15 The difference from Example 1 is that the aging time is 90 min, resulting in Im-Cu2O. 1:5,NaOH,L-AA -90 catalyst.

[0056] Example 16 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of 2-methylimidazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and 2-methylimidazole.

[0057] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and 2-methylimidazole, and stir for 5 min after the addition is complete.

[0058] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain 2-MeIm-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0059] Example 17 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of 2-aminobenzimidazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and 2-aminobenzimidazole.

[0060] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and 2-aminobenzimidazole, and stir for 5 min after the addition is complete.

[0061] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain 2-ABIm-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0062] Example 18 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of 2-nitroimidazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and 2-nitroimidazole.

[0063] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and 2-nitroimidazole, and stir for 5 min after the addition is complete.

[0064] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain 2-NIm-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0065] Example 19 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of pyrazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and pyrazole.

[0066] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and pyrazole, and stir for 5 min after the addition is complete.

[0067] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Pz-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0068] Example 20 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of 4-mercaptopyridine in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and 4-mercaptopyridine.

[0069] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and 4-mercaptopyridine, and stir for 5 min after the addition is complete.

[0070] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain 4-MPyS-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0071] Example 21 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of furan in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and furan.

[0072] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and furan, and stir for 5 min after the addition is complete.

[0073] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Fu-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0074] Comparative Example 1 A Cu2O NaOH,L-AA The method for preparing the catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride in 400 mL of deionized water and stir for 5 min until it is evenly dispersed to obtain a copper chloride solution.

[0075] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the copper chloride solution, and stir for 5 min after the addition is complete.

[0076] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Cu2O. NaOH,L-AA catalyst.

[0077] Comparative Example 2 The difference from Comparative Example 1 is that sodium hydroxide, the precipitant, was replaced with sodium carbonate, resulting in Cu2O. Na2CO3,L-AA catalyst.

[0078] Comparative Example 3 The difference from Comparative Example 1 is that sodium hydroxide, the precipitant, was replaced with sodium bicarbonate, resulting in Cu2O. NaHCO3,L-AA catalyst.

[0079] Comparative Example 4 The difference from Comparative Example 1 is that the precipitant sodium hydroxide was replaced with ammonia water, resulting in Cu2O. NH3·H2O,L-AA catalyst.

[0080] Comparative Example 5 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of thiophene in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and thiophene; (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and thiophene, and stir for 5 min after the addition is complete; (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Th-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0081] Comparative Example 6 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of pyrrole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and pyrrole.

[0082] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and pyrrole, and stir for 5 min after the addition is complete.

[0083] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Pyr-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0084] Comparative Example 7 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of pyridine in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and pyridine.

[0085] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and pyridine, and stir for 5 min after the addition is complete.

[0086] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Py-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0087] Comparative Example 8 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of 2-methylpyridine in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and 2-methylpyridine.

[0088] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and 2-methylpyridine, and stir for 5 min after the addition is complete.

[0089] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain 2-Mepy-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0090] Comparative Example 9 A method for preparing an organically modified cuprous oxide-based catalyst includes the following steps: (1) First, dissolve 0.05 mol of copper chloride and 0.01 mol of thiazole in 400 mL of deionized water and stir for 5 min until the mixture is evenly dispersed to obtain a complex solution of copper chloride and thiazole.

[0091] (2) Slowly add 150 mL of 2 mol / L sodium hydroxide solution to the complex solution formed by copper chloride and thiazole, and stir for 5 min after the addition is complete.

[0092] (3) Slowly add 100 mL of 1 mol / L L-ascorbic acid to the generated precipitate, and age for 60 min after the addition is complete. After the reaction is complete, wash three times with deionized water by centrifugation, and dry under vacuum at 60 °C for 12 h to obtain Thz-Cu2O. 1:5,NaOH,L-AA -60 catalyst.

[0093] The catalysts of Examples 1 to 21 and Comparative Examples 1 to 9 were characterized in terms of structure and performance.

[0094] Figure 1 Cu2O, which is Comparative Example 1 of this invention NaOH,L-AA Catalyst and Im-Cu2O of Example 1 1:5,NaOH,L-AA XRD pattern of the -60 catalyst. Figure 1 As can be seen, Cu2O in Comparative Example 1 NaOH,L-AA The catalyst exhibits typical diffraction peaks of cubic cuprous oxide, indicating its high crystallinity; while the imidazole-modified Im-Cu2O 1:5,NaOH,L-AA In the -60 catalyst, the peak intensities of all diffraction peaks decreased, indicating a significant reduction in crystallinity or extremely small particle size. This can be attributed to the interaction between imidazole molecules and Cu on the cuprous oxide surface. + The coordination effect of the imidazole forms an organic coating layer, which in turn restricts grain growth and introduces a disordered structure. Overall, the cuprous oxide-based catalyst modified with imidazole molecules still has Cu2O as the core, but the surface organic layer causes it to exhibit near-amorphous diffraction characteristics, reflecting that imidazole modification significantly reduces the crystallinity of Cu2O and enhances its dispersibility.

[0095] Figure 2 Cu2O, which is Comparative Example 1 of this invention NaOH,L-AACatalyst and Im-Cu2O of Example 1 1:5,NaOH,L-AA SEM image of the -60 catalyst. Figure 2 Figure a shows Cu2O in Comparative Example 1. NaOH,L-AA SEM images of the catalyst, b is Im-Cu2O from Example 1. 1:5,NaOH,L-AA SEM image of the -60 catalyst. (Source: [Insert source here]) Figure 2 It can be seen that unmodified Cu2O NaOH,L-AA The catalyst particles are uniformly distributed and densely packed, exhibiting a typical spherical or near-spherical shape, indicating that pure cuprous oxide has a high degree of crystallinity. In contrast, Im-Cu₂O 1:5,NaOH,L-AA The particle size of the -60 sample increased significantly, accompanied by agglomeration and increased surface roughness. These morphological changes indicate that the imidazole organic layer has been successfully modified onto the Cu2O surface, thereby reducing its crystallinity, which is consistent with... Figure 1 The XRD results are consistent.

[0096] Next, the catalysts from Examples 1-26 and Comparative Examples 1-4 were used to catalyze the acetyleneation reaction of formaldehyde. The specific catalytic process was as follows: First, 2.5g of the above catalyst and 50mL of a 37.43% formaldehyde solution were added sequentially to a 250mL reactor. The stirring device was turned on and the rotation speed was kept constant at 600rpm to ensure uniform mixing of the catalyst and the formaldehyde solution. Then, N2 was introduced into the reactor to purge the air from the reaction system; subsequently, acetylene gas was introduced to purge the nitrogen from the reactor. The heating device was then turned on until the temperature inside the reactor reached 90°C, and the acetylene pressure was kept constant at 0.6MPa during the reaction. The reaction was allowed to proceed for 10 hours to synthesize 1,4-butynediol. After 10 hours of reaction, the heating and stirring devices were turned off, the temperature was lowered to room temperature, and the introduction of acetylene gas was stopped. The catalyst and reaction liquid were separated by centrifugation, and then the catalyst was dried under vacuum at 60°C for 4 hours. The resulting centrifuged liquid mainly contains the main product 1,4-butynediol, unreacted formaldehyde, the intermediate product propynyl alcohol, and a small amount of byproduct polyyne.

[0097] Table 1 shows the performance of different catalysts in the acetylenelation reaction of formaldehyde. 1,4-Butynediol is abbreviated as BYD. As can be seen from Table 1, in the comparative examples, when only the type of precipitant (NaOH, Na₂CO₃, NaHCO₃, and NH₃·H₂O) was changed while other conditions remained the same, the formaldehyde conversion rate of the pure Cu₂O catalyst was only 39.45%–50.24%, and the BYD yield was 15.78%–24.96%. The results indicate that the Cu₂O catalyst prepared using sodium hydroxide as the precipitant has the highest formaldehyde conversion rate (50.24%) and BYD yield (24.96%). In contrast, in the examples, by fixing the precipitant to sodium hydroxide and adjusting the ratio of copper salt to imidazole, the catalyst performance was significantly improved. Formaldehyde conversion rates generally approached or reached 100%, BYD yield increased to 60.82%–73.33%, and selectivity remained stable within the range of 68.54%–73.47%, demonstrating significantly better catalytic performance than the comparative results. Specifically, the catalyst exhibited optimal catalytic performance when the ratio of copper salt to imidazole was 1:5, indicating that an appropriate salt-to-imidazole ratio is beneficial for improving the dispersion and stability of active copper species, thereby significantly increasing the formation efficiency of the target product BYD while ensuring high formaldehyde conversion. When the ratio deviated from the suitable range, both yield and conversion decreased. Subsequently, changing the precipitant type while maintaining a constant copper salt-to-imidazole ratio, although still maintaining high BYD selectivity, resulted in a significant decrease in formaldehyde conversion and BYD yield, further demonstrating the crucial role of sodium hydroxide as a precipitant in constructing a highly active catalytic structure. Furthermore, different reducing agents significantly affected the catalytic performance. L-AA showed the best overall performance, while the formaldehyde conversion rate and BYD yield were significantly reduced when using glucose, NaBH4, or N2H4, indicating that excessively weak or strong reducing power is detrimental to the stable existence of active copper species. The introduction of certain organic molecules (such as imidazole, 2-methylimidazole, 2-aminobenzimidazole, pyrazole, 4-mercaptopyridine, and furan) improved the yield and selectivity of 1,4-butynediol. The introduction of imidazole-based organic molecules significantly enhanced the catalytic performance of cuprous oxide catalysts in the formaldehyde acetylenelation reaction. This may be because these organic molecules formed suitable coordination interactions with the cuprous oxide surface, effectively regulating the electronic structure of copper species. Simultaneously, the interaction between organic molecules and formaldehyde molecules enhanced formaldehyde adsorption, thereby promoting the reaction. Then there are also some organic molecules (such as thiazoles, pyrroles, pyridines, 2-methylpyridines, and thiophenes) that, due to their strong coordination ability or large steric hindrance to the copper active center, interact with Cu. +The formation of a stable coordination structure covers the key active sites required for acetylene adsorption and activation, making it difficult for reactant molecules to effectively access the copper sites, thus reducing the formaldehyde conversion rate and the yield of 1,4-butynediol. In contrast, imidazole ligands have moderate coordination ability and good structural stability, and can maintain sufficient exposure of active sites while stabilizing active copper species, thus exhibiting superior catalytic performance.

[0098] Table 1 Performance of different catalysts in the catalytic reaction of formaldehyde acetylene. It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and methods used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of this invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended scope of protection is intended to be interpreted as including the preferred embodiments and all changes and modifications falling within the scope of this invention.

[0099] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of protection of this invention and its equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing an organically modified cuprous oxide-based catalyst, characterized in that, Includes the following steps: Using soluble copper salt as a precursor and heteroaromatic ring molecules as coordination inducers, the mixture is prepared in a solvent system. The heteroaromatic ring molecules coordinate with copper ions to form a complex. A precipitant is added to the complex to precipitate it, followed by a reducing agent to reduce and age it, so that copper ions are reduced to form cuprous oxide. The cuprous oxide is then coated with heteroaromatic ring molecules to form cuprous oxide aggregates, thus obtaining an organically modified cuprous oxide-based catalyst.

2. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The molar ratio of soluble copper salt and heteroaromatic ring molecules is 5:0.5~3.

3. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The precipitant is sodium hydroxide, sodium carbonate, sodium bicarbonate, or ammonia; the molar volume ratio of heteroaromatic ring molecules to precipitant is 0.5mol~3mol:50mL~150mL.

4. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The reducing agent is glucose, L-ascorbic acid, sodium borohydride, or hydrazine hydrate; the molar volume ratio of heteroaromatic ring molecules to precipitant is 0.5 mol to 3 mol: 50 mL to 150 mL.

5. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The heteroaromatic ring molecule is imidazole, 2-methylimidazolium, 2-aminobenzimidazole, 2-nitroimidazolium, pyrazole, 4-mercaptopyridine, or furan.

6. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The soluble copper salt is at least one of copper nitrate, copper sulfate, copper chloride, and copper acetate.

7. The method for preparing the organically modified cuprous oxide-based catalyst according to claim 1, characterized in that, The aging time is 15 min to 90 min; the molar volume ratio of heteroaromatic ring molecules to solvent is 0.5 mol to 3 mol: 400 mL to 600 mL, and the solvent is water.

8. An organically modified cuprous oxide-based catalyst, characterized in that, It is prepared by the method described in any one of claims 1 to 7.

9. The application of the organically modified cuprous oxide catalyst of claim 8 in the formaldehyde acetylene reaction.

10. The application of the organically modified cuprous oxide-based catalyst according to claim 9 in the formaldehyde acetyleneation reaction, characterized in that, Using formaldehyde solution and acetylene as raw materials, a formaldehyde acetylation reaction was carried out under constant pressure in the presence of an organically modified cuprous oxide catalyst to obtain 1,4-butynediol; the mass-volume ratio of the organically modified cuprous oxide catalyst to the formaldehyde solution was 2.5 g: 50 mL, and the mass concentration of the formaldehyde solution was 37 wt%~40 wt%.

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