Copper silicon catalyst for catalyzing the coupling of ethylene glycol with primary alcohols to synthesize long-chain vicinal diols, its preparation method and use

Abstract

The present application provides a copper-silicon catalyst for catalyzing the coupling reaction of ethylene glycol with primary alcohols to synthesize long-chain vicinal diols, its preparation method and use, which belong to the technical field of heterogeneous catalysis. The general chemical formula of the copper-silicon catalyst is Cu x Si 1-x 0, and 0.01≦x≦0.3. The copper silicon catalyst has good stability and high activity, and when used in the synthesis of long-chain vicinal diols, it is easy to separate from the product, and has high ethylene glycol conversion and product selectivity, and can be reused multiple times.

Description

[Technical Field]

[0001] This application relates to the technical field of heterogeneous catalysis, for example, to copper silicon catalysts, their preparation methods and uses for catalyzing the coupling of ethylene glycol with primary alcohols to synthesize long-chain vicinal diols. [Background technology]

[0002] Ethylene glycol, an important petrochemical product, is widely used in various fields. China is the world's largest consumer market for ethylene glycol. Over the past decade, China's ethylene glycol industry has developed rapidly, with production capacity significantly improved. In 2020, China's ethylene glycol production capacity reached more than 15.7 million tons, with the main production technologies being the ethylene method and the oxalate ester method. China is a major coal-producing country with abundant resources. The indirect production process of ethylene glycol using coal is an important ethylene glycol production route, accounting for nearly 50% of the total production. With the continuous improvement and updating of production technologies, new ethylene glycol production routes are being developed one after another, including the use of renewable biomass feedstocks, hydrogenation of sugars, direct conversion of cellulose, and biomass fermentation to reduce glyoxal to ethylene glycol. This has the potential to greatly increase ethylene glycol production. With the continuous improvement of the world's ethylene glycol production capacity, there is an excess of ethylene glycol production capacity in the world, so how to use ethylene glycol with low value cost to make high value-added products and realize high value utilization has become a hot topic of scientific researchers' research.Among the many routes for using ethylene glycol, the process route of combining ethylene glycol with dimethyl carbonate to catalyze the synthesis of high value ethylene carbonate has attracted attention.

[0003] Currently, the conversion of ethylene glycol to lactic acid, α-hydroxy acids, etc. using the coupling of ethylene glycol with primary alcohols has become a hot research topic. However, this route still has significant problems. Wu et al. (Angewandte Chemie, 2020, 10507-10511) prepared a series of iridium complexes using three azacycloalkenes derived from 1,3-dimethylbenzimidazole salts to catalyze the coupling of ethylene glycol with methanol to produce lactic acid, with a TOF value of 3660 h. -1 Satyadeep Waiba et al. (ACS Catalysis, 2022, 12, 7, 3995-4001) designed a manganese complex, {[HN(C2H4PPh2)2]Mn(CO)2Br}, to catalyze the conversion of vicinal diols to α-hydroxycarboxylic acids. This complex has attracted widespread attention in various pharmaceuticals, bioactive molecules, and biodegradable polymers, enabling the subsequent efficient conversion and utilization of vicinal diols. However, current homogeneous catalyst complexes have problems such as complex preparation processes, difficulty in reuse, and difficulty in achieving industrial scale-up.

[0004] Therefore, designing a heterogeneous catalyst that is easy to prepare, highly selective, and reusable for use in catalyzing the coupling of ethylene glycol is an urgent technical problem to be solved. Summary of the Invention [Problem to be solved by the invention]

[0005] The following is a general summary of the subject matter described in detail herein. This summary does not limit the scope of the claims. [Means for solving the problem]

[0006] The present application provides a copper-silicon catalyst for catalyzing the coupling reaction of ethylene glycol with primary alcohols to synthesize long-chain vicinal diols, as well as its preparation and use. The copper-silicon catalyst has good stability and activity, and when used in the synthesis of long-chain vicinal diols, it is easy to separate from the product, has high ethylene glycol conversion and product selectivity, and can be reused multiple times.

[0007] In aspect 1, the present application provides a copper silicon catalyst for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol, the copper silicon catalyst having the general chemical formula Cu x Si 1-x O, and 0.05≦x≦0.3.

[0008] The copper silicon catalyst of the present invention has good stability and high activity. When used in the synthesis of long-chain vicinal diols, it is easy to separate from the product, has high ethylene glycol conversion and product selectivity, and can be reused multiple times.

[0009] In this application, x is 0.01≦x≦0.3, and may be, for example, 0.01, 0.05, 0.1, 0.015, 0.02, 0.025, or 0.3, but is not limited to the recited values, and other unrecited values ​​within the numerical range also apply.

[0010] In this application, if the value of x is too small, the content of copper species on the catalyst surface will be too low, resulting in a shortage of active sites and a low conversion rate; if the value of x is too large, excessive aggregation of copper species on the surface will occur, which is unfavorable for uniform dispersion of active sites.

[0011] In one preferred technical solution of the present application, the copper silicon catalyst has a coral seed-like structure.

[0012] In this application, the coral seed-like structure contributes to the exposure of more active sites and the uniform distribution of copper on the silica surface.

[0013] In a second aspect, the present application provides a method for preparing the copper silicon catalyst for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol according to the first aspect, the method comprising: (1) mixing a copper solution with a silicon source and performing ammonia removal treatment by heating to obtain a precursor solution; and (2) subjecting the precursor solution to hydrothermal crystallization, calcination and reduction treatment to obtain the copper silicon catalyst.

[0014] The present application provides a simple catalyst preparation method, which is low cost and can prepare a copper silicon catalyst without the need for a solvent or carrier.

[0015] In one preferred technical solution of the present application, the method for preparing the copper solution described in step (1) comprises: The method includes mixing a copper source, an alkali source, and a solvent to obtain the copper solution.

[0016] In one embodiment, the copper source is a soluble copper salt, and the soluble copper salt includes one or a combination of at least two of copper nitrate pentahydrate, copper nitrate, copper sulfate, copper chloride, or copper carbonate. Illustratively, typical examples of the combination may be, but are not limited to, a combination of copper nitrate and copper chloride, a combination of copper chloride and copper carbonate, or a combination of copper carbonate and copper sulfate.

[0017] In one embodiment, the solution comprises water.

[0018] In one embodiment, the alkaline source includes a combination of at least one of hydroxide, aqueous ammonia, ammonium carbonate, ammonium bicarbonate, and urea. Illustrative examples of the combination include, but are not limited to, a combination of aqueous ammonia and ammonium carbonate, a combination of aqueous ammonia and urea, or a combination of aqueous ammonia and ammonium bicarbonate.

[0019] In one embodiment, the hydroxide ion concentration of the alkalinity source is 1 to 10 mol / L, and may be, for example, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, 6 mol / L, 7 mol / L, 8 mol / L, 9 mol / L, or 10 mol / L, but is not limited to the recited values, and other unrecited values ​​within the numerical range also apply.

[0020] In one embodiment, the pH of the copper solution is 9 to 11, such as 9.0, 9.5, 10.0, 10.5, or 11.0, but is not limited to the recited values, and other unrecited values ​​within the range also apply.

[0021] In one embodiment, the mixing method includes stirring and mixing the copper source and the solvent to obtain a mixed solution, and then adding the alkali source dropwise to the mixed solution and continuing to stir and mix to obtain the copper solution.

[0022] In one embodiment, the rate at which the alkali source is added dropwise is 60 to 150 drops / min, and may be, for example, 60 drops / min, 80 drops / min, 100 drops / min, 120 drops / min, or 150 drops / min, but is not limited to the recited numerical values, and other unrecited numerical values ​​within the numerical range also apply.

[0023] In one preferred technical solution of the present application, the silicon source described in step (1) comprises silica sol and / or tetraethyl orthosilicate.

[0024] In one embodiment, the temperature of the heating treatment for removing ammonia in step (1) is 40 to 70°C, and may be, for example, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C, but is not limited to the recited values, and other unrecited values ​​within the range also apply.

[0025] In the present application, if the temperature of the ammonia removal treatment by heating is too low, the removal of ammonia gas will be too slow and even ammonia gas will remain; if the temperature of the ammonia removal treatment by heating is too high, it will affect the crystal growth of the copper silicon catalyst and affect the growth process in the subsequent hydrothermal process.

[0026] In one embodiment, the pH of the precursor solution described in step (1) is ≦7, for example, the pH may be 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, or 7.0, etc., but is not limited to the recited values, and other unrecited values ​​within the numerical ranges also apply.

[0027] In this application, a pH of the precursor solution of ≦7 ensures effective removal of ammonia gas and contributes to ensuring complete conversion of copper salts to solid hydroxides and oxides.

[0028] In one preferred technical solution of the present application, the temperature of the hydrothermal crystallization described in step (2) is 120 to 200°C, such as 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C, or 200°C, and the time is 12 to 48 hours, such as 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours, or 48 hours. However, the present invention is not limited to the recited values, and other unrecited values ​​within the numerical ranges also apply.

[0029] In this application, if the temperature of hydrothermal crystallization is too low, the crystal growth of the crystals will be insufficient and the exposure of the sites will be insufficient; if the temperature of hydrothermal crystallization is too high, the growth of the crystals will be too complete, the specific surface area of ​​the catalyst will be too low, and the active center of the catalyst will be hidden.

[0030] In one embodiment, after the hydrothermal crystallization growth treatment described in step (2), washing and drying are carried out, followed by calcination and reduction treatment.

[0031] In one embodiment, the drying temperature is 60 to 120°C, such as 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, and the drying time is 2 to 18 hours, such as 2 hours, 6 hours, 10 hours, 14 hours, or 18 hours, etc. However, the drying is not limited to the recited values, and other unrecited values ​​within the range of values ​​also apply.

[0032] In one embodiment, the firing temperature is 300 to 600°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, but is not limited to the recited values, and other unrecited values ​​within the range also apply, and the firing time is 2 to 6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, but is not limited to the recited values, and other unrecited values ​​within the range also apply.

[0033] In one embodiment, the reduction treatment is performed at a temperature of 300 to 600°C, such as 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, for a time of 2 to 6 hours, such as 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours, but is not limited to the listed values, and other unlisted values ​​within the ranges also apply.

[0034] In this application, if the temperature of the reduction treatment is too low, the degree of reduction of some copper species will be insufficient, and Cu 0 , Cu + and Cu 2+ If the reduction temperature is too high, it will cause aggregation and coagulation of the surface active sites, reducing the reaction activity.

[0035] In one embodiment, the reduction process is carried out in a reducing gas, and the reducing gas includes hydrogen gas and nitrogen gas.

[0036] In one embodiment, the volume fraction of hydrogen gas in the reducing gas is 8 to 12%, and may be, for example, 8%, 9%, 10%, 11%, or 12%, but is not limited to the recited values, and other unrecited values ​​within the numerical range also apply.

[0037] As a preferred technical solution of the present application, the preparation method includes: a step of stirring and mixing a soluble copper salt and deionized water at room temperature for 2 to 30 minutes to obtain a copper salt solution, then adding an alkali source dropwise to the copper salt solution until the pH reaches 9 to 11, and then stirring and mixing for 10 to 30 minutes to obtain a copper solution, Step (I) in which the hydroxide ion concentration of the alkali source is 1 to 10 mol / L and the rate of dropping the alkali source is 60 to 150 drops / min; a step of dropping a silicon source into the copper solution at room temperature, stirring for 0.5 to 2 hours, and then performing an ammonia removal treatment by heating at a temperature of 40 to 70°C until a precursor solution having a pH of 3 to 8 is obtained; Step (II) in which the silicon source is dropped at a dropping rate of 60 to 150 drops / min; (III) transferring the precursor solution into a hydrothermal oven, carrying out hydrothermal crystallization at 120 to 200°C for 12 to 48 hours, washing after completion, and then drying at 60 to 120°C for 8 to 18 hours to obtain a solid catalyst; The solid catalyst is calcined at 300 to 600°C for 2 to 6 hours, and then cooled to room temperature, and the solid catalyst is subjected to reduction treatment in a reducing gas at 300 to 600°C for 2 to 6 hours to obtain the copper silicon catalyst, and step (IV) wherein the reducing gas comprises hydrogen gas and nitrogen gas.

[0038] In a third aspect, the present application provides a use of a copper silicon catalyst for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol according to the first aspect, wherein the copper silicon catalyst is used to catalyze the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol.

[0039] In one preferred technical solution of the present application, the long-chain vicinal diol is a long-chain vicinal diol having a carbon number of ≥ 3, and exemplary examples of the combination may be, but are not limited to, 1,2-propanediol, 1,2-butanediol, 1,2-pentanediol, or 1,2-hexanediol.

[0040] In one embodiment, the specific steps in which the copper silicon catalyst is used to catalyze the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol are: (a) performing reduction and pre-activation treatment on the copper silicon catalyst to obtain a treated copper silicon catalyst; and (b) mixing ethylene glycol, a primary alcohol, and the treated copper silicon catalyst to carry out a catalytic reaction to obtain a long-chain vicinal diol.

[0041] In one preferred technical solution of the present application, the specific steps of the reduction and preactivation treatment described in step (a) are: The catalyst reduction and preactivation process involves passing hydrogen gas through a vessel containing a copper silicon catalyst at a predetermined temperature.

[0042] In this application, the purpose of the reduction and preactivation treatment of the copper silicon catalyst is to change the valence of the species on the catalyst surface and activate the active centers.

[0043] In one embodiment, the preset temperature is 250 to 450°C, and may be, for example, 250°C, 300°C, 350°C, 400°C, or 450°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range also apply.

[0044] In one embodiment, the primary alcohol referred to in step (b) comprises any one or a combination of at least two of methanol, ethanol, n-propanol, and n-butanol.

[0045] In one embodiment, the mass fraction of the ethylene glycol is 0.01 to 0.3% based on the total mass of the ethylene glycol and the primary alcohol, and may be, for example, 0.01%, 0.05%, 0.1%, 0.2%, or 0.3%, but is not limited to the recited values, and other unrecited values ​​within the numerical range also apply.

[0046] In one embodiment, the temperature of the catalytic reaction in step (b) is 150 to 300°C, and may be, for example, 150°C, 200°C, 250°C, or 300°C, and the pressure during the catalytic reaction is 0.5 to 5 MPa, and may be, for example, 0.5 MPa, 1 MPa, 2 MPa, 3 MPa, or 4 MPa.

[0047] In the present application, if the temperature of the catalytic reaction is too low, the thermodynamic conditions for the catalyst cannot be met and the target product cannot be obtained; if the temperature of the catalytic reaction is too high, the amount of by-products such as ethers increases and the selectivity of the target product, long-chain vicinal diol, decreases.

[0048] The numerical ranges referred to in this application include not only the recited point values ​​but also any point values ​​between the recited numerical ranges, and for reasons of space and clarity, this application does not exhaustively list specific point values ​​included in the ranges. [Effects of the Invention]

[0049] Compared to the related art, the present application has the following beneficial effects:

[0050] (1) The copper silicon catalyst of the present invention has good stability and high activity. When used to catalyze the coupling of ethylene glycol with primary alcohol to synthesize long-chain vicinal diol chemicals, it is easy to separate from the product and has high ethylene glycol conversion and product selectivity, with a conversion rate of over 80% and a selectivity of over 75%, allowing for multiple reuse.

[0051] (2) The present application provides a method for preparing a catalyst that is easy to synthesize, which is low cost and does not require a solvent or a carrier to prepare a copper silicon catalyst.

[0052] Other aspects may be understood upon reading and understanding the drawings and detailed description.

[0053] The drawings are intended to provide a further understanding of the technical solution of the present application, constitute a part of the specification, and are intended to interpret the technical solution of the present application together with the examples of the present application, but are not intended to limit the technical solution of the present application. [Brief explanation of the drawings]

[0054] [Figure 1] FIG. 2 is an XRD diagram of copper silicon catalysts according to Examples 1 to 4 of the present application. [Figure 2] FIG. 2 is an SEM image of a copper silicon catalyst according to Example 3 of the present application. DETAILED DESCRIPTION OF THE INVENTION

[0055] The technical solution of the present application will be further described below through specific embodiments. Those skilled in the art should understand that the above examples are only for understanding the present application and should not be considered as specific limitations of the present application.

[0056] In the following embodiments, room temperature means 25°C. [Example]

[0057] [Example 1] This example provides a method for preparing a copper silicon catalyst, which includes the following steps:

[0058] (1) 3.83 g of copper nitrate trihydrate and 500 mL of deionized water were mixed and stirred at room temperature for 30 minutes to obtain a copper salt solution. Then, ammonia water with a mass fraction of 35% was added dropwise to the copper salt solution until the pH reached 11, and the mixture was then mixed and stirred for 30 minutes to obtain a copper solution.

[0059] However, the hydroxide ion concentration of the ammonia water was 1 mol / L, and the rate at which the ammonia water was dropped was 90 drops / min.

[0060] (2) At room temperature, 10 mL of 30% mass fraction silica sol was dropped into the copper solution, stirred for 0.5 hours, and then heated to 65°C to remove ammonia until a precursor solution with a pH of 7 was obtained.

[0061] However, the dropping rate of the silicon source was 100 drops / min.

[0062] (3) The precursor solution was transferred into a 200 mL polytetrafluoroethylene-lined hydrothermal kettle and subjected to hydrothermal crystallization at 200°C for 15 hours. After completion, the solution was washed and then dried at 90°C for 12 hours to obtain a solid catalyst.

[0063] (4) The solid catalyst is calcined at 500°C for 4 hours in an air atmosphere, and then cooled to room temperature. The solid catalyst is then reduced in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst with a coral-like structure, whose chemical formula is Cu 0.02 Si 0.98 It was O.

[0064] However, the reducing gas contained hydrogen gas at a volume fraction of 10% and nitrogen gas at a volume fraction of 90%.

[0065] This example further provides a method for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol using the above copper silicon catalyst, the method comprising the following steps:

[0066] (a) The copper silicon catalyst is tableted using a tableting machine, crushed to a 50 mesh size, and sieved. The tableted catalyst is then packed into a fixed-bed stainless steel tube, and quartz sand and quartz wool are packed above and below the copper silicon catalyst to prevent the catalyst from splashing out together with the reaction solution.

[0067] (b) Hydrogen gas was passed through the fixed-bed stainless steel tube at a flow rate of 100 mL / min for 3 hours at a temperature of 300°C to carry out catalyst reduction and preactivation.

[0068] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, of which ethylene glycol accounted for 0.05% of the total mass. This solution was then pumped through a micro-fixed bed and injected into a stainless steel tube containing a copper-silicon catalyst at a feed rate of 0.15 mL / min. The catalytic reaction was carried out under conditions of 1 MPa, a H2 flow rate of 100 mL / min, and a reaction temperature of 200 °C. The product, 1,2-butanediol, was obtained. Samples were taken every hour and detected by a combination of gas chromatography-mass spectrometry and gas chromatography.

[0069] [Example 2] This example provides a method for preparing a copper silicon catalyst, which includes the following steps:

[0070] (1) 6.35 g of copper nitrate trihydrate and 500 mL of deionized water were mixed and stirred at room temperature for 30 minutes to obtain a copper salt solution. Then, ammonia water with a mass fraction of 35% was added dropwise to the copper salt solution until the pH reached 11, and the mixture was then mixed and stirred for 30 minutes to obtain a copper solution.

[0071] However, the hydroxide ion concentration of the ammonia water was 2 mol / L, and the rate at which the ammonia water was dropped was 100 drops / min.

[0072] (2) At room temperature, 10 mL of 30 wt.% silica sol was added dropwise to the copper solution, stirred for 0.5 h, and then heated at 65°C to remove ammonia until a precursor solution with a pH of <7 was obtained.

[0073] However, the dropping rate of the silicon source was 100 drops / min.

[0074] (3) The precursor solution was transferred into a 200 mL polytetrafluoroethylene-lined hydrothermal kettle and subjected to hydrothermal crystallization at 200°C for 15 hours. After completion, the solution was washed and then dried at 90°C for 12 hours to obtain a solid catalyst.

[0075] (4) The solid catalyst is calcined at 500°C for 4 hours in an air atmosphere, and then cooled to room temperature. The solid catalyst is then reduced in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst with a coral-like structure, whose chemical formula is Cu 0.05 Si 0.95 It was O.

[0076] However, the reducing gas contained hydrogen gas at a volume fraction of 10% and nitrogen gas at a volume fraction of 90%.

[0077] This example further provides a method for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol using the above copper silicon catalyst, the method comprising the following steps:

[0078] (a) The copper silicon catalyst is tableted using a tableting machine, crushed to 40 mesh, and sieved. The tableted catalyst is then packed into a fixed-bed stainless steel tube, and quartz sand and quartz wool are packed above and below the copper silicon catalyst to prevent the catalyst from splashing out together with the reaction solution.

[0079] (b) Hydrogen gas was passed through the fixed-bed stainless steel tube at a flow rate of 100 mL / min for 3 hours at a temperature of 300°C to carry out catalyst reduction and preactivation.

[0080] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, of which ethylene glycol accounted for 0.1% of the total mass. This solution was then pumped through a micro-fixed bed and injected into a stainless steel tube containing a copper-silicon catalyst at a feed rate of 0.15 mL / min. The catalytic reaction was carried out under conditions of 1 MPa, a H2 flow rate of 100 mL / min, and a reaction temperature of 200 °C, yielding the product 1,2-butanediol. Samples were taken every hour and detected by a combination of gas chromatography-mass spectrometry and gas chromatography.

[0081] [Example 3] This example provides a method for preparing a copper silicon catalyst, which includes the following steps:

[0082] (1) 13.42 g of copper nitrate trihydrate and 500 mL of deionized water were mixed and stirred at room temperature for 30 minutes to obtain a copper salt solution. Then, ammonia water with a mass fraction of 35% was added dropwise to the copper salt solution until the pH reached 11, and the mixture was then mixed and stirred for 30 minutes to obtain a copper solution.

[0083] However, the hydroxide ion concentration of the ammonia water was 1 mol / L, and the rate at which the ammonia water was dropped was 100 drops / min.

[0084] (2) At room temperature, 10 mL of 30 wt. % silica sol was added dropwise to the copper solution, and the mixture was stirred for 0.5 hours. After that, the mixture was heated at 65°C to remove ammonia until a precursor solution with a pH of 7 was obtained.

[0085] However, the dropping rate of the silicon source was 100 drops / min.

[0086] (3) The precursor solution was transferred into a 200 mL polytetrafluoroethylene-lined hydrothermal kettle and subjected to hydrothermal crystallization at 200°C for 15 hours. After completion, the solution was washed and then dried at 90°C for 12 hours to obtain a solid catalyst.

[0087] (4) The solid catalyst is calcined at 500°C for 4 hours in an air atmosphere, and then cooled to room temperature. The solid catalyst is then reduced in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst with a coral-like structure, whose chemical formula is Cu 0.1 Si 0.9 It was O.

[0088] However, the reducing gas contained hydrogen gas at a volume fraction of 10% and nitrogen gas at a volume fraction of 90%.

[0089] This example further provides a method for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol using the above copper silicon catalyst, the method comprising the following steps:

[0090] (a) The copper silicon catalyst is tableted using a tableting machine, crushed to a 60 mesh size, and sieved. The tableted catalyst is then packed into a fixed-bed stainless steel tube, and quartz sand and quartz wool are packed above and below the copper silicon catalyst to prevent the catalyst from splashing out together with the reaction solution.

[0091] (b) Hydrogen gas was passed through the fixed-bed stainless steel tube at a flow rate of 100 mL / min for 3 hours at a temperature of 300°C to carry out catalyst reduction and preactivation.

[0092] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, of which ethylene glycol accounted for 0.2% of the total mass. This solution was then pumped through a micro-fixed bed and injected into a stainless steel tube containing a copper-silicon catalyst at a feed rate of 0.15 mL / min. The catalytic reaction was carried out under conditions of 1 MPa, a H2 flow rate of 100 mL / min, and a reaction temperature of 200 °C. The product, 1,2-butanediol, was obtained. Samples were taken every hour and detected by a combination of gas chromatography-mass spectrometry and gas chromatography.

[0093] FIG. 2 shows the SEM image of the copper silicon catalyst according to this example, which shows that the catalyst has a coral-like structure.

[0094] [Example 4] This example provides a method for preparing a copper silicon catalyst, which includes the following steps:

[0095] (1) 21.31 g of copper nitrate trihydrate and 500 mL of deionized water were stirred and mixed at room temperature for 30 minutes to obtain a copper salt solution, and then ammonia water with a mass fraction of 35% was added dropwise to the copper salt solution until the pH reached 11. The mixture was then stirred and mixed for 30 minutes to obtain a copper solution.

[0096] However, the hydroxide ion concentration of the ammonia water was 1 mol / L, and the rate at which the ammonia water was dropped was 90 drops / min.

[0097] (2) At room temperature, 10 mL of 30 wt. % silica sol was added dropwise to the copper solution, and after stirring for 1 hour, ammonia was removed by heating at 65°C until a precursor solution with a pH of 7 was obtained.

[0098] However, the dropping rate of the silicon source was 100 drops / min.

[0099] (3) The precursor solution was transferred into a 200 mL polytetrafluoroethylene-lined hydrothermal kettle and subjected to hydrothermal crystallization at 200°C for 15 hours. After completion, the solution was washed and then dried at 90°C for 12 hours to obtain a solid catalyst.

[0100] (4) The solid catalyst is calcined at 500°C for 4 hours in an air atmosphere, and then cooled to room temperature. The solid catalyst is then reduced in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst with a coral-like structure, whose chemical formula is Cu 0.15 Si 0.85 It was O.

[0101] However, the reducing gas contained hydrogen gas at a volume fraction of 10% and nitrogen gas at a volume fraction of 90%.

[0102] This example further provides a method for catalyzing the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol using the above copper silicon catalyst, the method comprising the following steps:

[0103] (a) The copper silicon catalyst is tableted using a tableting machine, crushed to a 60 mesh size, and sieved. The tableted catalyst is then packed into a fixed-bed stainless steel tube, and quartz sand and quartz wool are packed above and below the copper silicon catalyst to prevent the catalyst from splashing out together with the reaction solution.

[0104] (b) Hydrogen gas was passed through the fixed-bed stainless steel tube at a flow rate of 100 mL / min for 3 hours at a temperature of 300°C to carry out catalyst reduction and preactivation.

[0105] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, of which ethylene glycol accounted for 0.25% of the total mass. This solution was then pumped through a micro-fixed bed and injected into a stainless steel tube containing a copper-silicon catalyst at a feed rate of 0.15 mL / min. The catalytic reaction was carried out under conditions of 1 MPa, a H2 flow rate of 100 mL / min, and a reaction temperature of 200 °C, yielding the product 1,2-butanediol. Samples were taken every hour and detected by a combination of gas chromatography-mass spectrometry and gas chromatography.

[0106] FIG. 1 shows the XRD patterns of the copper silicon catalysts according to Examples 1 to 4. It can be seen from the diagram that the catalysts have clear peaks characteristic of copper silicon oxide, and with the increase in the molar ratio of the copper source, the peaks characteristic of copper oxide are significantly enhanced.

[0107] [Example 5] The difference between this example and Example 1 is that ethanol in step (c) was replaced with methanol.

[0108] The remaining preparation methods and parameters were consistent with Example 1.

[0109] [Example 6] The difference between this example and Example 1 is that ethanol in step (c) was replaced with n-propanol.

[0110] The remaining preparation methods and parameters were consistent with Example 1.

[0111] [Example 7] The difference between this example and Example 1 is that ethanol in step (c) was replaced with n-butanol.

[0112] The remaining preparation methods and parameters were consistent with Example 1.

[0113] [Example 8] The difference between this example and Example 1 is that the temperature of the ammonia removal treatment by heating in step (2) was 30°C.

[0114] The remaining preparation methods and parameters were consistent with Example 1.

[0115] [Example 9] The difference between this example and Example 1 is that the temperature of the ammonia removal treatment by heating in step (2) was 100°C.

[0116] The remaining preparation methods and parameters were consistent with Example 1.

[0117] [Example 10] The difference between this example and Example 1 is that the pH of the precursor solution in step (2) was 10.

[0118] The remaining preparation methods and parameters were consistent with Example 1.

[0119] [Example 11] The difference between this example and Example 1 is that the temperature of the hydrothermal crystallization in step (3) was 100°C.

[0120] The remaining preparation methods and parameters were consistent with Example 1.

[0121] [Example 12] The difference between this example and Example 1 is that the temperature of the hydrothermal crystallization in step (3) was 250°C.

[0122] The remaining preparation methods and parameters were consistent with Example 1.

[0123] [Example 13] The difference between this example and Example 1 is that the temperature of the reduction treatment in step (4) was 200°C.

[0124] The remaining preparation methods and parameters were consistent with Example 1.

[0125] [Example 14] The difference between this example and Example 1 is that the temperature of the reduction treatment in step (4) was 700°C.

[0126] The remaining preparation methods and parameters were consistent with Example 1.

[0127] [Example 15] The difference between this example and Example 1 is that step (b) was not performed.

[0128] The remaining preparation methods and parameters were consistent with Example 1.

[0129] [Example 16] The difference between this example and Example 1 is that the reaction temperature in step (c) was 100°C.

[0130] The remaining preparation methods and parameters were consistent with Example 1.

[0131] [Example 17] The difference between this example and Example 1 is that the reaction temperature in step (c) was 350°C.

[0132] The remaining preparation methods and parameters were consistent with Example 1.

[0133] [Comparative Example 1] The difference between this comparative example and Example 1 is that no silica sol was added in step (2), and a single copper oxide catalyst was obtained.

[0134] The remaining preparation methods and parameters were consistent with Example 1.

[0135] Comparative Example 2 The difference between this comparative example and Example 1 is that copper nitrate trihydrate was not added in step (1), and a single silica catalyst was obtained.

[0136] The remaining preparation methods and parameters were consistent with Example 1.

[0137] Comparative Example 3 The difference between this comparative example and Example 1 is that the amount of copper nitrate trihydrate added in step (1) was adjusted to change the chemical formula of the prepared copper silicon catalyst to Cu 0.3 Si 0.7 This is what I did to O.

[0138] The remaining preparation methods and parameters were consistent with Example 1.

[0139] [Performance test] After centrifuging the products prepared in the above Examples and Comparative Examples, an appropriate amount of the supernatant was taken, and an internal standard (biphenyl) was added to it, followed by quantitative analysis by the gas chromatography internal standard method.

[0140] The test results are shown in Table 1.

[0141] [Table 1]

[0142] [analysis] As can be seen from the above table, the copper silicon catalyst of the present invention has good stability and high activity. When used to catalyze the coupling of ethylene glycol with primary alcohol to synthesize long-chain vicinal diol chemicals, it is easy to separate from the product, and the conversion rate of ethylene glycol and the selectivity of the product are high, with the conversion rate reaching 80% or more and the selectivity reaching 75% or more, and it can be reused multiple times.

[0143] As can be seen from the data results of Examples 1 to 7 and Comparative Examples 1 and 2, the coral-like silicon copper oxide structure of the present application exhibits high catalytic stability and activity in the process of catalyzing the coupling reaction of ethylene glycol to prepare long-chain vicinal diols. On the other hand, a single silica catalyst or copper oxide catalyst has low catalytic activity and poor catalytic effect. This indicates that only when the catalyst of the present application contains both copper and silicon, can it achieve excellent selectivity and yield in catalyzing the synthesis of long-chain vicinal diols.

[0144] As can be seen from the data results of Examples 1 and 8 to 9, if the temperature of the ammonia removal treatment by heating is too low, the removal of ammonia gas is too slow and more ammonia gas remains, while if the temperature of the ammonia removal treatment by heating is too high, it will affect the crystal growth of the copper silicon catalyst, which will affect the growth process in the subsequent hydrothermal process.

[0145] As can be seen from the data results of Examples 1 and 10, if the pH of the precursor solution is too high, it will cause the precipitation and decomposition of copper hydroxide, which will result in incomplete copper salt conversion, excessive washout, and a large difference from the theoretical molar ratio, reducing the reaction activity.

[0146] As can be seen from the data results of Examples 1 and 11-12, if the hydrothermal crystallization temperature is too low, the crystal growth of the crystals will be insufficient and the sites will not be exposed enough; if the hydrothermal crystallization temperature is too high, the crystal growth will be too complete, the specific surface area of ​​the catalyst will be too low, and the active center of the catalyst will be hidden.

[0147] As can be seen from the data results of Examples 1 and 13 to 14, if the temperature of the reduction treatment is too low, the degree of reduction of some copper species is insufficient, and Cu 0 , Cu + and Cu 2+ If the reduction temperature is too high, it will cause aggregation and coagulation of the surface active sites, reducing the reaction activity.

[0148] As can be seen from the data results of Examples 1 and 15, in the method of synthesizing long-chain vicinal diols by catalyzing the coupling of ethylene glycol with primary alcohols, if the copper silicon catalyst is not subjected to reduction and preactivation treatment, almost no Cu is present on the catalyst surface. 2+ exists in the valence state Cu + , Cu 0 The number of valences present is extremely small, and the number of active sites is too small, which further leads to a decrease in catalytic activity.

[0149] As can be seen from the data results of Examples 1 and 16-17, if the temperature of the catalytic reaction is too low, the thermodynamic catalytic conditions cannot be met and the target product cannot be obtained. If the temperature of the catalytic reaction is too high, the amount of by-products such as ethers increases and the selectivity of the target product, long-chain vicinal diol, decreases.

[0150] The present application has described the process method of the present application through the above examples, but the applicant declares that the present application is not limited to the above process, that is, it does not mean that the present application must be carried out depending on the above process. Those skilled in the art should understand that any improvements to the present application, equivalent substitution of raw materials used in the present application, addition of auxiliary components, selection of specific forms, etc., are all within the protection scope and disclosure scope of the present application.

Claims

1. Use of a copper silicon catalyst, The copper silicon catalyst is used to catalyze the coupling of ethylene glycol with primary alcohol to synthesize long-chain vicinal diols, and the general chemical formula of the copper silicon catalyst is Cu ｘ Si １－ｘ O, 0.01≦x<0.3, The method for preparing the copper silicon catalyst includes: Step (1) of mixing a copper solution and a silicon source, and performing ammonia removal treatment by heating to obtain a precursor solution; (2) performing hydrothermal crystallization of the precursor solution at 120-200°C for 12-48 hours, calcination at 300-600°C for 2-6 hours, and reduction treatment at 300-600°C for 2-6 hours to obtain the copper silicon catalyst; Before the copper-silicon catalyst can be used to catalyze the coupling of ethylene glycol with a primary alcohol to produce a long-chain vicinal diol, the copper-silicon catalyst must be subjected to a reduction and preactivation process. use.

2. The copper silicon catalyst has a coral seed-like structure; 2. The use according to claim 1.

3. The method for preparing a copper solution according to step (1) includes the steps of: mixing a copper source, an alkali source, and a solvent to obtain the copper solution; the copper source is a soluble copper salt, and the soluble copper salt comprises any one or a combination of at least two of copper nitrate pentahydrate, copper nitrate, copper sulfate, copper chloride, or copper carbonate; the alkalinity source comprises one or a combination of at least two of hydroxide, aqueous ammonia, ammonium carbonate, ammonium bicarbonate, or urea; the hydroxide ion concentration of the alkali source is 1 to 10 mol / L; the pH of the copper solution is 9 to 11; 2. The use according to claim 1.

4. The silicon source according to step (1) comprises silica sol and / or tetraethyl orthosilicate; The temperature of the ammonia removal treatment by heating described in step (1) is 40 to 70°C, The pH of the precursor solution described in step (1) is 3 to 8; 2. The use according to claim 1.

5. The preparation method comprises: a step of stirring and mixing a soluble copper salt and deionized water at room temperature for 2 to 30 minutes to obtain a copper salt solution, then adding an alkali source dropwise to the copper salt solution until the pH reaches 9 to 11, and then stirring and mixing for 10 to 30 minutes to obtain a copper solution; Step (I) in which the hydroxide ion concentration of the alkali source is 1 to 10 mol / L and the rate of dropping the alkali source is 60 to 150 drops / min; Dropping a silicon source into the copper solution at room temperature, stirring for 0.5-2 hours, and then performing an ammonia removal treatment by heating at a temperature of 40-70°C until a precursor solution with a pH of 7 or less is obtained; Step (II) in which the silicon source is dropped at a dropping rate of 60 to 150 drops / min; (III) transferring the precursor solution to a hydrothermal oven, carrying out hydrothermal crystallization at 120-200°C for 12-48 hours, washing after completion, and then drying at 60-120°C for 8-18 hours to obtain a solid catalyst; The solid catalyst is calcined at 300 to 600°C for 2 to 6 hours, and then cooled to room temperature, and the solid catalyst is reduced in a reducing gas at 300 to 600°C for 2 to 6 hours to obtain the copper silicon catalyst; and step (IV) wherein the reducing gas comprises hydrogen gas and nitrogen gas.

2. The use according to claim 1.

6. The long-chain vicinal diol is a long-chain vicinal diol having a carbon number of ≥ 3, The specific steps in which the copper silicon catalyst is used to catalyze the coupling of ethylene glycol with a primary alcohol to synthesize a long-chain vicinal diol are as follows: (a) performing reduction and pre-activation treatment on the copper silicon catalyst to obtain a treated copper silicon catalyst; and (b) mixing ethylene glycol, a primary alcohol, and the treated copper silicon catalyst to carry out a catalytic reaction to obtain a long-chain vicinal diol.

2. The use according to claim 1.

7. The specific steps of the reduction and preactivation process described in step (a) are: The method includes passing hydrogen gas through a vessel containing a copper silicon catalyst at a predetermined temperature to carry out a catalyst reduction and preactivation process; The preset temperature is 250 to 450°C, The primary alcohol in step (b) comprises any one or a combination of at least two of methanol, ethanol, n-propanol, and n-butanol; the mass fraction of the ethylene glycol is 0.01 to 0.3% based on the total mass of the ethylene glycol and the primary alcohol; The temperature of the catalytic reaction described in step (b) is 150 to 300°C, and the pressure during the catalytic reaction is 0.5 to 5 MPa; 7. The use according to claim 6.

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