Copper-silicon catalyst for catalyzing the coupling of ethylene glycol and primary alcohols to synthesize long-chain vicinal diols, method for preparing the same, and use thereof.

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, and more particularly to a copper-silicon catalyst for catalyzing the coupling of ethylene glycol and a primary alcohol to synthesize long-chain vicinal diols, a method for preparing the same, and its use. [Background technology]

[0002] Ethylene glycol, as an important petrochemical product, is widely applied in various fields. China is the world's largest consumer market for ethylene glycol, and in the last decade, China's ethylene glycol industry has developed rapidly, with production capacity already significantly increasing. In 2020, China's ethylene glycol production capacity reached over 15.7 million tons, with the main production technologies being the ethylene process and the oxalate ester process. China is a major coal-producing country with abundant resources, and the indirect production process of ethylene glycol using coal is an important ethylene glycol production route, accounting for nearly 50% of the total process. With the continuous improvement and updating of production technology, new ethylene glycol production routes are being developed one after another. Various methods have been developed that utilize renewable biomass raw materials, such as hydrogenation of sugars, direct conversion of cellulose, and fermentation of biomass to reduce glyoxal to ethylene glycol. As a result, the production volume of ethylene glycol has great potential for increase. Due to the continuous increase in ethylene glycol production capacity worldwide, a surplus of ethylene glycol production capacity has emerged. Therefore, how to utilize the low-value-cost ethylene glycol to create high-value-added products and realize high-value utilization has become a hot topic of research for scientific researchers. Among the many routes for using ethylene glycol, the process route that catalyzes the synthesis of high-value ethylene carbonate by combining ethylene glycol with dimethyl carbonate is attracting attention.

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

[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 that needs to be solved. [Overview of the project] [Problems that the invention aims to solve]

[0005] The following is an overview of the subject matter described in detail in this paper. This overview does not limit the scope of the claims. [Means for solving the problem]

[0006] This application provides a copper-silicon catalyst for catalyzing the coupling of ethylene glycol and a primary alcohol to synthesize long-chain vicinal diols, a method for preparing the same, and its use. The copper-silicon catalyst has good stability and high activity, is easily separated from the product when used in the synthesis of long-chain vicinal diols, has a high conversion rate of ethylene glycol and product selectivity, and can be reused multiple times.

[0007] In Embodiment 1, the present application provides a copper-silicon catalyst for catalyzing the coupling of ethylene glycol and a primary alcohol to synthesize long-chain vicinal diols, wherein the general chemical formula of the copper-silicon catalyst is Cu x Si 1-x The answer is O, and 0.05 ≤ x ≤ 0.3.

[0008] The copper-silicon catalyst according to this invention has good stability and high activity, and when used in the synthesis of long-chain vicinal diols, it is easily separated from the product, and also exhibits a high conversion rate of ethylene glycol and product selectivity, enabling multiple reuses.

[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 listed numbers, and other unlisted numbers within the numerical range are also applicable.

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

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

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

[0013] In Embodiment 2, the present application provides a method for preparing a copper-silicon catalyst for catalyzing the coupling of ethylene glycol and a primary alcohol to synthesize a long-chain vicinal diol. The preparation method includes: Step (1) of mixing a copper solution and a silicon source, and performing an ammonia removal treatment by heating to obtain a precursor solution; Step (2) of performing hydrothermal crystallization, calcination, and reduction treatment on the precursor solution to obtain the copper-silicon catalyst.

[0014] The present application provides a method for preparing a catalyst with a simple process, which has low cost and can prepare a copper-silicon catalyst without the need for a solvent and a carrier.

[0015] As one preferred technical solution of the present application, the method for preparing the copper solution described in Step (1) 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 any one or at least two combinations of copper nitrate pentahydrate, copper nitrate, copper sulfate, copper chloride, or copper carbonate. Exemplarily, typical examples of the combination may be, but are not limited to, the combination of copper nitrate and copper chloride, the combination of copper chloride and copper carbonate, or the combination of copper carbonate and copper sulfate, etc.

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

[0018] In one embodiment, the alkali source includes any one or at least two combinations of a hydroxide, aqueous ammonia, ammonium carbonate, ammonium bicarbonate, or urea. Exemplarily, examples of the combination may be, but are not limited to, the combination of aqueous ammonia and ammonium carbonate, the combination of aqueous ammonia and urea, or the combination of aqueous ammonia and ammonium bicarbonate, etc.

[0019] In one embodiment, the hydroxide ion concentration of the alkali source is 1 to 10 mol / L. For example, it may be 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, etc. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0020] In one embodiment, the pH of the copper solution is 9 to 11. For example, it may be 9.0, 9.5, 10.0, 10.5, or 11.0, etc. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0021] In one embodiment, the mixing method includes stirring and mixing a copper source and a solvent to obtain a mixed solution, and then dropping the alkali source into the mixed solution and continuously stirring and mixing to obtain the copper solution.

[0022] In one embodiment, the dropping rate of the alkali source is 60 to 150 drops / min. For example, it may be 60 drops / min, 80 drops / min, 100 drops / min, 120 drops / min, or 150 drops / min, etc. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

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

[0024] In one embodiment, the temperature of the ammonia removal treatment by heating described in step (1) is 40 to 70°C. For example, it may be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C, etc. However, it is not limited to the listed values, and other unlisted values within the numerical range are equally applicable.

[0025] In this invention, if the temperature of the ammonia removal treatment by heating is too low, the removal of ammonia gas is too slow, and some ammonia gas remains. If the temperature of the ammonia removal treatment by heating is too high, it affects the crystal growth of the copper silicon catalyst and the subsequent hydrothermal process.

[0026] In one embodiment, the pH of the precursor solution described in step (1) is ≤ 7, and 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 listed values, and other unlisted values ​​within the numerical range are also applicable.

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

[0028] As one preferred technical application of this invention, the hydrothermal crystallization described in step (2) may be at a temperature of 120 to 200°C, for example, 120°C, 130°C, 140°C, 150°C, 160°C, 170°C, 180°C, 190°C or 200°C, and at a time of 12 to 48 hours, for example, 12 hours, 16 hours, 20 hours, 24 hours, 28 hours, 32 hours, 36 hours, 40 hours, 44 hours or 48 hours, etc. However, it is not limited to the listed values, and other unlisted values ​​within the numerical range may also apply.

[0029] In this invention, if the hydrothermal crystallization temperature is too low, the crystal growth of the crystal body will be insufficient, resulting in insufficient exposure of the sites. If the hydrothermal crystallization temperature is too high, the crystal growth will be excessively perfect, resulting in an excessively low specific surface area of ​​the catalyst and concealment of the catalyst's active center.

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

[0031] In one embodiment, the drying may be at a temperature of 60 to 120°C, for example, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C, or 120°C, and at a duration of 2 to 18 hours, for example, 2 hours, 6 hours, 10 hours, 14 hours, or 18 hours. However, it is not limited to the listed values, and other unlisted values ​​within the numerical range may also apply.

[0032] In one embodiment, the firing is performed at a temperature of 300 to 600°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable, and the firing is performed at a temperature of 2 to 6 hours, for example, 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 numerical range are also applicable.

[0033] In one embodiment, the reduction treatment may be performed at a temperature of 300 to 600°C, for example, 300°C, 350°C, 400°C, 450°C, 500°C, 550°C, or 600°C, and for a duration of 2 to 6 hours, for example, 2 hours, 3 hours, 4 hours, 5 hours, or 6 hours. However, it is not limited to the listed values, and other unlisted values ​​within the numerical range may also apply.

[0034] In this application, if the reduction treatment temperature is too low, the degree of reduction of some copper species will be insufficient, Cu 0 Cu + and Cu 2+ If the proportion is too high, it becomes impossible to achieve a good catalytic effect, and if the reduction treatment temperature is too high, it causes aggregation and condensation of the surfactant 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 8-12%, and may be, for example, 8%, 9%, 10%, 11%, or 12%, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] As one preferred technical proposal of the present invention, the preparation method is: The process involves 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) is one in which the hydroxide ion concentration of the alkali source is 1 to 10 mol / L and the dropping rate of the alkali source is 60 to 150 drops / min, The steps include: adding a silicon source dropwise to 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 with a pH of 3 to 8 is obtained; Step (II) involves dropping the silicon source at a dropping rate of 60-150 drops / min, Step (III) involves transferring the precursor solution into a hydrothermal vessel, performing 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 steps include: firing the solid catalyst at 300-600°C for 2-6 hours, then letting it cool to room temperature, and then reducing the solid catalyst in a reducing gas at 300-600°C for 2-6 hours to obtain the copper-silicon catalyst, The method includes step (IV), in which the reducing gas contains hydrogen gas and nitrogen gas.

[0038] In Embodiment 3, the present application provides the use of a copper-silicon catalyst for catalyzing the coupling of ethylene glycol and a primary alcohol to synthesize long-chain vicinal diols, wherein the copper-silicon catalyst is used to catalyze the coupling of ethylene glycol and a primary alcohol to synthesize long-chain vicinal diols.

[0039] As one preferred technical application of the present invention, the long-chain vicinal diol is a long-chain vicinal diol having ≥ 3 carbon atoms, and typical examples of combinations 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 used to catalyze the coupling of ethylene glycol and a primary alcohol to synthesize a long-chain vicinal diol are as follows: (a) A step in which a copper-silicon catalyst is subjected to reduction and pre-activation to obtain the treated copper-silicon catalyst, The method includes (b) mixing ethylene glycol, a primary alcohol, and the treated copper-silicon catalyst, carrying out a catalytic reaction to obtain a long-chain vicinal diol.

[0041] As one preferred technical example of the present invention, the specific steps of the reduction and pre-activation treatment described in step (a) are: The process includes passing hydrogen gas through a container containing a copper-silicon catalyst at a preset temperature to perform catalytic reduction and pre-activation.

[0042] In this application, the purpose of performing reduction and pre-activation treatment on the copper-silicon catalyst is to change the valence of the species on the catalyst surface and activate the active center.

[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 are also applicable.

[0044] In one embodiment, the primary alcohol described in step (b) includes one or at least two of methanol, ethanol, n-propanol, and n-butanol.

[0045] In one embodiment, the mass fraction of 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 listed values, and other unlisted values ​​within the numerical range are also applicable.

[0046] In one embodiment, the temperature of the catalytic reaction described 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 this invention, if the catalytic reaction temperature is too low, the catalytic conditions cannot be satisfied thermodynamically due to the low temperature, and the target product cannot be obtained. If the catalytic reaction temperature is too high, by-products such as ethers increase, and the selectivity of the target product, the long-chain vicinal diol, decreases.

[0048] The numerical range relating to this application includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. For the sake of space and simplicity, this application does not comprehensively list the specific point values ​​included in the range. [Effects of the Invention]

[0049] With respect to related technologies, this application offers the following beneficial effects.

[0050] (1) The copper-silicon catalyst according to the present invention has good stability and high activity, and when used to catalyze the coupling of ethylene glycol and primary alcohol to synthesize long-chain vicinal diol chemicals, it is easily separated 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, enabling multiple reuses.

[0051] (2) The present invention provides a method for preparing a catalyst that is easy to synthesize, and the method is low-cost and does not require solvents or supports to prepare a copper-silicon catalyst.

[0052] After reviewing and understanding the drawings and detailed descriptions, other embodiments can also be understood.

[0053] The drawings are provided to further understand the technical proposal presented in this paper, constitute part of the specification, and are intended to interpret the technical proposal together with the embodiments of this application, and do not limit the technical proposal presented hereto. [Brief explanation of the drawing]

[0054] [Figure 1] These are XRD diagrams of the copper-silicon catalysts relating to Examples 1-4 of this application. [Figure 2] This is a SEM diagram of the copper-silicon catalyst according to Example 3 of this application. [Modes for carrying out the invention]

[0055] The technical proposal of this application will be further described below with reference to specific embodiments. Those skilled in the art should understand that the above embodiments are merely for the purpose of understanding this application and should not be considered as specific limitations of this application.

[0056] In the following embodiments, room temperature refers to 25°C. [Examples]

[0057] [Example 1] This embodiment provides a method for preparing a copper-silicon catalyst, the preparation method comprising the following steps.

[0058] (1) 3.83 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. Then, 35% ammonia water was added dropwise to the copper salt solution until the pH reached 11, and the mixture was stirred and mixed for 30 minutes to obtain a copper solution.

[0059] However, the hydroxide ion concentration of the ammonia solution was 1 mol / L, and the dropping rate of the ammonia solution was 90 drops / min.

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

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

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

[0063] (4) After calcining the solid catalyst at 500°C for 4 hours in an air atmosphere, the solid catalyst is cooled to room temperature and then subjected to reduction treatment in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst having a coral-like structure, the chemical formula of which is Cu 0.02 Si 0.98 The answer was O.

[0064] However, the reducing gas contained 10% hydrogen gas and 90% nitrogen gas by volume.

[0065] This embodiment further provides a method for synthesizing long-chain vicinal diols by catalyzing the coupling of ethylene glycol and a primary alcohol using the above-mentioned copper-silicon catalyst, the method comprising the following steps.

[0066] (a) The copper-silicon catalyst is compressed into tablets using a tablet press, crushed to a 50-mesh consistency and sieved, and then packed into a stainless steel pipe in a fixed bed. Quartz sand and quartz wool are packed above and below the copper-silicon catalyst to prevent the catalyst from flying out with the reaction liquid.

[0067] (b) At a temperature of 300°C, hydrogen gas was passed through a fixed-bed stainless steel pipe at a flow rate of 100 mL / min for 3 hours to perform catalytic reduction and pre-activation treatment.

[0068] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, in which ethylene glycol accounted for 0.05% of the total mass. This solution was fed through a feed pump into a micro fixed bed and injected into a stainless steel tube of a fixed bed 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, H2 flow rate of 100 mL / min, and reaction temperature of 200°C to obtain the product 1,2-butanediol. Sampling was performed once every hour, and detection was performed by gas chromatography-mass spectrometry and a combination of gas chromatography and mass spectrometry.

[0069] [Example 2] This embodiment provides a method for preparing a copper-silicon catalyst, the preparation method comprising the following steps.

[0070] (1) 6.35 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. Then, 35% ammonia water was added dropwise to the copper salt solution until the pH reached 11, and the mixture was stirred and mixed for 30 minutes to obtain a copper solution.

[0071] However, the hydroxide ion concentration of the ammonia solution was 2 mol / L, and the dropping rate of the ammonia solution 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 hours, and then heated at 65°C to remove ammonia until a precursor solution with pH < 7 was obtained.

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

[0074] (3) Transfer the precursor solution into a 200 mL hydrothermal autoclave lined with polytetrafluoroethylene, perform hydrothermal crystallization at 200 °C for 15 h, wash it after completion, and then dry it at 90 °C for 12 h to obtain a solid catalyst.

[0075] (4) In an air atmosphere, calcine the solid catalyst at 500 °C for 4 h, cool it to room temperature, and then perform a reduction treatment on the solid catalyst in a reducing gas at 400 °C for 4 h to obtain a copper silicon catalyst having a coral-like structure, and its chemical formula is Cu 0.05 Si 0.95 O.

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

[0077] This example further provides a method for synthesizing a long-chain vicinal diol by catalyzing the coupling of ethylene glycol and a primary alcohol using the above copper silicon catalyst, and the method includes the following steps.

[0078] (a) Tablet the copper silicon catalyst with a tableting machine, crush it until it becomes 40 mesh, sieve it, and then fill it into a stainless steel tube of a fixed bed. Fill quartz sand and quartz wool above and below the copper silicon catalyst to prevent the catalyst from jumping out with the reaction solution.

[0079] (b) At a temperature of 300 °C, pass hydrogen gas with a flow rate of 100 mL / min through the stainless steel tube of the fixed bed for 3 h to perform catalyst reduction and pre-activation treatment.

[0080] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, in which ethylene glycol accounted for 0.1% of the total mass. This solution was fed through a feed pump into a micro fixed bed and injected into a stainless steel tube of a fixed bed 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, H2 flow rate of 100 mL / min, and reaction temperature of 200°C to obtain the product 1,2-butanediol. Sampling was performed once every hour, and detection was performed by gas chromatography-mass spectrometry and a combination of gas chromatography and mass spectrometry.

[0081] [Example 3] This embodiment provides a method for preparing a copper-silicon catalyst, the preparation method comprising the following steps.

[0082] (1) 13.42 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. Then, 35% ammonia water was added dropwise to the copper salt solution until the pH reached 11, and the mixture was stirred and mixed for another 30 minutes to obtain a copper solution.

[0083] However, the hydroxide ion concentration of the ammonia solution was 1 mol / L, and the dropping rate of the ammonia solution was 100 drops / min.

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

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

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

[0087] (4) After calcining the solid catalyst at 500°C for 4 hours in an air atmosphere, the solid catalyst is cooled to room temperature and then subjected to reduction treatment in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst having a coral-like structure, the chemical formula of which is Cu 0.1 Si 0.9 The answer was O.

[0088] However, the reducing gas contained 10% hydrogen gas and 90% nitrogen gas by volume.

[0089] This embodiment further provides a method for synthesizing long-chain vicinal diols by catalyzing the coupling of ethylene glycol and a primary alcohol using the above-mentioned copper-silicon catalyst, the method comprising the following steps.

[0090] (a) The copper-silicon catalyst is compressed into tablets using a tablet press, crushed to a 60-mesh consistency and sieved, and then packed into a stainless steel pipe in a fixed bed. Quartz sand and quartz wool are packed above and below the copper-silicon catalyst to prevent the catalyst from flying out with the reaction liquid.

[0091] (b) At a temperature of 300°C, hydrogen gas was passed through a fixed-bed stainless steel pipe at a flow rate of 100 mL / min for 3 hours to perform catalytic reduction and pre-activation treatment.

[0092] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, in which ethylene glycol accounted for 0.2% of the total mass. This solution was fed through a feed pump into a micro fixed bed and injected into a stainless steel tube of a fixed bed 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, H2 flow rate of 100 mL / min, and reaction temperature of 200°C to obtain the product 1,2-butanediol. Sampling was performed once every hour, and detection was performed by gas chromatography-mass spectrometry and a combination of gas chromatography and mass spectrometry.

[0093] Figure 2 shows an SEM image of the copper-silicon catalyst according to this embodiment, and the figure shows that the catalyst has a coral-like structure.

[0094] [Example 4] This embodiment provides a method for preparing a copper-silicon catalyst, the preparation method comprising 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. Then, 35% ammonia water was added dropwise to the copper salt solution until the pH reached 11, and the mixture was stirred and mixed for another 30 minutes to obtain a copper solution.

[0096] However, the hydroxide ion concentration of the ammonia solution was 1 mol / L, and the dropping rate of the ammonia solution was 90 drops / min.

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

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

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

[0100] (4) After calcining the solid catalyst at 500°C for 4 hours in an air atmosphere, the solid catalyst is cooled to room temperature and then subjected to reduction treatment in a reducing gas at 400°C for 4 hours to obtain a copper silicon catalyst having a coral-like structure, the chemical formula of which is Cu 0.15 Si 0.85 The answer was O.

[0101] However, the reducing gas contained 10% hydrogen gas and 90% nitrogen gas by volume.

[0102] This embodiment further provides a method for synthesizing long-chain vicinal diols by catalyzing the coupling of ethylene glycol and a primary alcohol using the above-mentioned copper-silicon catalyst, the method comprising the following steps.

[0103] (a) The copper-silicon catalyst is compressed into tablets using a tablet press, crushed to a 60-mesh consistency and sieved, and then packed into a stainless steel pipe in a fixed bed. Quartz sand and quartz wool are packed above and below the copper-silicon catalyst to prevent the catalyst from flying out with the reaction liquid.

[0104] (b) At a temperature of 300°C, hydrogen gas was passed through a fixed-bed stainless steel pipe at a flow rate of 100 mL / min for 3 hours to perform catalytic reduction and pre-activation treatment.

[0105] (c) Ethylene glycol and ethanol were mixed to prepare a homogeneous solution with a mass fraction of 25 wt%, in which ethylene glycol accounted for 0.25% of the total mass. This solution was fed through a feed pump into a micro fixed bed and injected into a stainless steel tube of a fixed bed 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, H2 flow rate of 100 mL / min, and reaction temperature of 200°C to obtain the product 1,2-butanediol. Sampling was performed once every hour, and detection was performed by gas chromatography-mass spectrometry and a combination of gas chromatography and mass spectrometry.

[0106] Figure 1 shows the XRD diagrams of the copper-silicon catalysts according to Examples 1 to 4. The diagram shows that the catalysts exhibit a clear characteristic peak of copper-silicon oxide, and that the characteristic peak of copper oxide is significantly enhanced as the molar ratio of the copper source increases.

[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 those of 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 those of 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 those of Example 1.

[0113] [ Comparative Example 8] Book Comparative Example The difference between this 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 those of Example 1.

[0115] [ Comparative Example 9] Book Comparative Example The difference between this 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 those of Example 1.

[0117] [ Comparative Example 10] Book Comparative Example The difference between this 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 those of Example 1.

[0119] [ Comparative Example 11] Book Comparative ExampleThe difference between this and Example 1 is that the temperature for hydrothermal crystallization in step (3) was 100°C.

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

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

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

[0123] [ Comparative Example 13] Book Comparative Example The difference between this 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 those of Example 1.

[0125] [ Comparative Example 14] Book Comparative Example The difference between this 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 those of Example 1.

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

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

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

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

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

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

[0133] [Comparative Example 1] The difference between this comparative example and Example 1 is that in step (2), silica sol was not added, and a single copper oxide catalyst was obtained.

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

[0137] [Comparative Example 3] The difference between this comparative example and Example 1 is that by adjusting the amount of copper nitrate trihydrate added in step (1), the chemical formula of the prepared copper silicon catalyst is changed to Cu 0.3 Si 0.7 The result was O.

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

[0139] [Performance Test] After centrifuging the products prepared in the above examples and comparative examples, an appropriate amount of supernatant was taken, an internal standard substance (biphenyl) was added, and quantitative analysis was performed by 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 table above, the copper-silicon catalyst according to the present invention has good stability and high activity, and when used to catalyze the coupling of ethylene glycol and primary alcohols to synthesize long-chain vicinal diol chemicals, it is easily separated 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, enabling multiple reuses.

[0143] As can be seen from the data results of Examples 1-7 and Comparative Examples 1-2, the coral-like silicon copper oxide structure according to the present invention exhibits high catalytic stability and activity in the process of preparing long-chain vicinal diols by catalyzing the coupling reaction of ethylene glycol. On the other hand, single silica catalysts or copper oxide catalysts exhibit low catalytic activity and poor catalytic effect. This indicates that the catalyst according to the present invention can only exhibit superior selectivity and yield in catalyzing the synthesis of long-chain vicinal diols if it contains two metals, copper and silicon, simultaneously.

[0144] Example 1 and Comparative Example As can be seen from the data results in 8-9, if the temperature of the ammonia removal process by heating is too low, the removal of ammonia gas is too slow, and some ammonia gas remains. If the temperature of the ammonia removal process by heating is too high, it affects the crystal growth of the copper silicon catalyst and the subsequent growth process in the hydrothermal step.

[0145] Example 1 and Comparative Example As can be seen from the 10 data results, if the pH of the precursor solution is too high, it causes precipitation and decomposition of copper hydroxide, further resulting in incomplete copper salt conversion, excessive leaching, a large difference from the theoretical molar ratio, and reduced reaction activity.

[0146] Example 1 and Comparative Example As can be seen from the data results in 11-12, if the hydrothermal crystallization temperature is too low, the crystal growth of the crystal body will be insufficient, resulting in insufficient exposure of the sites. If the hydrothermal crystallization temperature is too high, the crystal growth will be excessively perfect, the specific surface area of ​​the catalyst will be too low, and the active center of the catalyst will be concealed.

[0147] Example 1 and Comparative Example As can be seen from the data results in 13-14, if the reduction temperature is too low, the reduction degree of some copper species will be insufficient, and Cu 0 Cu + and Cu 2+ If the proportion is too high, it becomes impossible to achieve a good catalytic effect, and if the reduction treatment temperature is too high, it causes aggregation and condensation of the surfactant sites, reducing the reaction activity.

[0148] Example 1 and Comparative Example As can be seen from the 15 data results, in the method of synthesizing long-chain vicinal diols by catalyzing the coupling of ethylene glycol and primary alcohol, if the copper-silicon catalyst is not subjected to reduction and pre-activation treatment, the catalyst surface will have almost no Cu 2+ It exists in valence state, Cu + Cu 0 The presence of extremely low valencies, such as those mentioned above, results in too few active sites, further leading to a decrease in catalytic activity.

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

[0150] Although this application has illustrated the process method described above, the applicant declares that this application is not limited to the above process, and that it does not mean that this application must be implemented in accordance with the above process. Those skilled in the art should understand that any improvements to this application, equivalent substitutions and additions of auxiliary components to the raw materials used in this application, and selection of specific forms are all included within the scope of protection and disclosure of this application.

Claims

1. The use of a copper-silicon catalyst, The copper-silicon catalyst is used to catalyze the coupling of ethylene glycol and a 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, and 0.01 ≤ x < 0.3, The method for preparing the copper-silicon catalyst is as follows: Step (1) involves mixing a copper solution with a silicon source, performing an ammonia removal treatment by heating, and obtaining a precursor solution. The process includes (2) a step of performing hydrothermal crystallization of the precursor solution at 120 to 200°C for 12 to 48 hours, calcination at 300 to 600°C for 2 to 6 hours, and reduction treatment at 300 to 600°C for 2 to 6 hours to obtain the copper silicon catalyst, The temperature for the ammonia removal treatment by heating described in step (1) is 40 to 70°C, and the pH of the precursor solution described in step (1) is ≤ 7. The long-chain vicinaldiol is a long-chain vicinaldiol with ≥ 3 carbon atoms. The specific steps by which the copper-silicon catalyst is used to catalyze the coupling of ethylene glycol and a primary alcohol to synthesize a long-chain vicinal diol are as follows: (a) A step in which a copper-silicon catalyst is subjected to reduction and pre-activation to obtain the treated copper-silicon catalyst, The process includes (b) a step of mixing ethylene glycol, a primary alcohol, and the copper-silicon catalyst after the above treatment, and carrying out a catalytic reaction to obtain a long-chain vicinal diol, The temperature of the catalytic reaction described in step (b) is 150 to 300°C. use.

2. The copper-silicon catalyst has a coral-like structure. The use described in claim 1.

3. The method for preparing the copper solution described in step (1) is: The process includes 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 includes one or at least two of the following: copper nitrate pentahydrate, copper nitrate, copper sulfate, copper chloride, or copper carbonate. The alkali source includes one or a combination of at least two of the following: 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. The use described in claim 1.

4. The silicon source described in step (1) comprises silica sol and / or tetraethyl orthosilicate. The use described in claim 1.

5. The aforementioned preparation method is The process involves 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) is one in which the hydroxide ion concentration of the alkali source is 1 to 10 mol / L, and the dropping rate of the alkali source is 60 to 150 drops / min, The steps include adding a silicon source dropwise to 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 with a pH of ≤ 7 is obtained, Step (II) involves dropping the silicon source at a dropping rate of 60 to 150 drops / min, Step (III): Transfer the precursor solution to a hydrothermal vessel, perform hydrothermal crystallization at 120-200°C for 12-48 hours, wash after completion, and then dry at 60-120°C for 8-18 hours to obtain a solid catalyst. After calcining the solid catalyst at 300-600°C for 2-6 hours, it is cooled to room temperature and then the solid The step of obtaining the copper-silicon catalyst is to reduce the catalyst in a reducing gas at 300 to 600°C for 2 to 6 hours, Step (IV) includes a reducing gas containing hydrogen gas and nitrogen gas, The use described in claim 1.

6. The specific steps of the reduction and pre-activation treatment described in step (a) are: The process includes passing hydrogen gas through a container containing a copper-silicon catalyst at a preset temperature to perform catalytic reduction and pre-activation. The aforementioned preset temperature is 250 to 450°C. The primary alcohol described in step (b) includes one or at least two of methanol, ethanol, n-propanol, and n-butanol. Based on the total mass of the ethylene glycol and primary alcohol, the mass fraction of the ethylene glycol is 0.01 to 0.3%. The pressure during the catalytic reaction is 0.5 to 5 MPa. The use described in claim 1.

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