Copper-silicon catalyst for synthesizing high-carbon alcohol and preparation method of copper-silicon catalyst

Abstract

The invention relates to the technical field of catalysts, in particular to a copper-silicon catalyst for synthesizing high alcohols and a preparation method thereof.The copper-silicon catalyst comprises an active component, a carrier and an auxiliary, the active component is copper element, and the copper element is derived from copper nitrate trihydrate; the carrier is a silicon-based carrier, and the silicon-based carrier is derived from liquid silicon; the auxiliary agent is a calcium element, and the calcium element is derived from calcium nitrate tetrahydrate. According to the invention, a copper-silicon-calcium system is adopted to construct the catalyst, copper nitrate trihydrate is adopted to provide an active component copper, liquid silicon is adopted to provide a silicon-based carrier, calcium nitrate tetrahydrate is adopted to provide an auxiliary calcium, and the raw material ratio is accurately controlled, so that high-loading active components are not needed on the premise of ensuring the activity, and the raw material cost for preparing the catalyst is remarkably reduced; meanwhile, the cost control difficulty in subsequent industrial application is simplified, and a cost basis is provided for large-scale popularization of a technology for preparing high-carbon alcohol from synthesis gas.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a copper-silicon catalyst for synthesizing higher alcohols and its preparation method. Background Technology

[0002] Higher alcohols refer to monohydric alcohols with six or more carbon atoms. They are fundamental raw materials for the synthesis of fine chemicals such as surfactants, plasticizers, detergents, and industrial solvents, and have a wide range of applications. Based on their end use and carbon chain length, higher alcohols are mainly divided into plasticizer alcohols (C6-C11 alcohols) and detergent alcohols (C12-C20 alcohols). Plasticizers are used in polymer products such as polyvinyl chloride (PVC) to make them easier to process and to provide better mechanical, electrical insulation, cold resistance, and impact resistance properties. Detergent alcohols and their three major downstream derivatives—fatty alcohol polyoxyethylene ethers (AE), alcohol ether sulfates (AES), and fatty alcohol sulfates (AS)—are the main components of household, personal care, and industrial detergents. Higher alcohol surfactants have advantages such as good biodegradability, strong detergency, hard water resistance, and good compatibility, and can be used in low-temperature washing and heavy-duty cleaning applications, leading to the development of environmentally friendly low-phosphorus and phosphorus-free detergents.

[0003] The current mainstream technological routes for the industrial synthesis of higher alcohols all have significant limitations: the natural oil esterification hydrogenation method relies on natural oil resources and is affected by agricultural production cycles and climate conditions, resulting in weak production stability and scalability; the main product of the C10~C16 n-alkane oxidation method is a secondary alcohol with a high carbon number, the production process is lengthy and the product purity is low; the Alfor process is complex and has high requirements for reaction equipment, leading to a significant increase in equipment investment and subsequent operation and maintenance costs; the α-olefin carbonyl synthesis method uses expensive α-olefins as raw materials, and suffers from low reactivity and easy catalyst loss in the hydroformylation reaction of higher olefins, further increasing production costs and reducing product yield.

[0004] The direct synthesis of higher alcohols from syngas has broad application prospects due to the wide availability of raw materials, including coal, natural gas, and biomass, a short production process, and the production of high-value straight-chain primary alcohols. However, the industrialization of this process is limited by the performance defects of existing catalysts: First, it generally relies on precious metals such as Ru and Rh, which account for more than 60% of the total production cost and require high loading to ensure catalytic efficiency, thus restricting large-scale application; second, the selectivity for C8-C16 aviation fuel precursor alcohols is generally below 60%, and the ratio of branched to straight-chain alcohols in the product is less than 0.5, which cannot meet the pour point requirements of sustainable aviation fuel (SAF); third, the synthesis requires multiple steps, and intermediates such as olefins and aldehydes need to be separated during the process, significantly increasing equipment investment and production energy consumption; fourth, in acidic reaction environments, commonly used catalyst supports such as ZrO2 are prone to sintering, and active components are easily dissolved, resulting in catalyst life of less than 500 hours. Therefore, developing new catalysts with low cost, high selectivity, and long lifespan is key to breaking through the technical bottlenecks of syngas-to-higher alcohols and promoting the self-sufficiency of my country's higher alcohol industry. Summary of the Invention

[0005] The purpose of this invention is to provide a copper-silicon catalyst for synthesizing higher alcohols and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a copper-silicon catalyst for synthesizing higher alcohols, comprising an active component, a support, and an auxiliary agent, wherein the active component is copper element, the copper element is derived from copper nitrate trihydrate, and the amount of copper nitrate trihydrate used is 230g; the support is a silicon-based support, the silicon-based support is derived from liquid silicon, and the amount of liquid silicon used is 25-100g; the auxiliary agent is calcium element, the calcium element is derived from calcium nitrate tetrahydrate, and the amount of calcium nitrate tetrahydrate used is 69g.

[0007] This invention also provides a copper-silicon catalyst for synthesizing higher alcohols and a method for preparing the same, comprising the following steps: S1: Raw material preparation: Prepare a mixed metal salt solution A containing copper nitrate trihydrate and calcium nitrate tetrahydrate, a sodium carbonate solution with a concentration of 30%, and a transparent solution C containing liquid silica; S2: Coprecipitation reaction: Solution A and solution B are simultaneously added dropwise to solution C at 60℃, with the dropwise addition rate of solution A controlled at 3.5 mL / min, the pH of the system neutral, and the stirring speed at 250 rpm; S3: Post-treatment: After reaction, allow to stand at 60℃ for 0.5h for aging, filter and wash until the filtrate is neutral, dry at 100℃ until the moisture content is less than 7%, calcine at 550℃ and then cool. S4: Tableting: Take 0.15g of the calcined solid and press it into tablets using a 0.3×0.3mm mold. Control the saturation time and pressure to obtain the finished catalyst.

[0008] Preferably, in S1, the mixed metal salt solution A is prepared by dissolving 220g of copper nitrate trihydrate and 69g of calcium nitrate tetrahydrate in 150g of water, and the solution C is prepared by dissolving 50g of liquid silicon in 200mL of deionized water.

[0009] Preferably, in S2, the solution temperature and pH value are recorded every 10 minutes during the dropwise addition process.

[0010] Preferably, in step S3, a vacuum filtration device is used for filtration, and washing is stopped when the pH of the washing solution reaches 7.

[0011] Preferably, in S4, the saturation time is 30s and the pressure is 2.6N.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The technical solution provided by this invention uses a copper-silicon-calcium system to construct the catalyst. Copper nitrate trihydrate provides the active component copper, liquid silicon provides the silicon-based support, and calcium nitrate tetrahydrate provides the auxiliary calcium. The entire process does not rely on high-priced precious metals such as Ru and Rh. By precisely controlling the raw material ratio, high loading of active components is not required while ensuring activity, which significantly reduces the raw material cost of catalyst preparation. At the same time, it simplifies the cost control difficulty in subsequent industrial applications and provides a cost basis for the large-scale promotion of syngas to higher alcohols technology.

[0013] By optimizing the amount of liquid silicon and the co-precipitation reaction temperature, the catalyst can precisely guide the reaction towards the target product, effectively reducing the formation of byproducts such as low-carbon alcohols and alkanes. Among them, C8-C16 branched high-carbon alcohols, as key precursors for sustainable aviation fuel (SAF), can directly enhance the high-end application value of the product and broaden the application scenarios of high-carbon alcohols in the energy field through highly selective preparation.

[0014] The preparation process adopts an integrated workflow of "raw material preparation - co-precipitation reaction - post-treatment - tableting". The steps are closely connected. For example, in the co-precipitation stage, the pH of the system is controlled to be neutral by dynamically adjusting the dropping speed of solution B. In the post-treatment stage, the parameters of drying at 100℃ to a moisture content of less than 7% and calcining at 550℃ are clearly defined, without the need for additional complex processes. In the reaction stage, the conversion of syngas to higher alcohols can be completed in a single reactor without the need to separate intermediates such as olefins and aldehydes. This significantly shortens the production cycle, reduces equipment investment and maintenance costs, and reduces energy consumption during the reaction process, meeting the high efficiency and energy-saving requirements of industrial production.

[0015] The tableting stage, through optimization of 30s saturation time and 2.6N pressure, ensures that the finished catalyst has a radial pressure ≥100N and an axial pressure ≥400N. This allows it to withstand an initial temperature of 180℃, a test pressure of 3.8MPa, and an airflow of 350-400L / H in industrial reactions, preventing equipment blockage caused by breakage and pulverization during use. At the same time, the liquid silica support has good structural stability, which can reduce the risk of dissolution of active components and sintering of the support, ensuring the activity stability of the catalyst during long-term use and reducing the cost and operational losses caused by frequent replacements. Detailed Implementation

[0016] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0017] This invention provides a copper-silicon catalyst for synthesizing higher alcohols, comprising an active component, a support, and an auxiliary agent. The active component is copper element, derived from copper nitrate trihydrate, and the amount of copper nitrate trihydrate used is 230g. The support is a silicon-based support, derived from liquid silicon, and the amount of liquid silicon used is 25-100g. The auxiliary agent is calcium element, derived from calcium nitrate tetrahydrate, and the amount of calcium nitrate tetrahydrate used is 69g. Example 1

[0018] A method for preparing a copper-silicon catalyst for synthesizing higher alcohols includes the following steps: S1: Raw material preparation: Preparation of solution A: Under warm conditions, 230g of copper nitrate trihydrate and 69g of calcium nitrate tetrahydrate were dissolved together in 150g of water and stirred evenly to obtain mixed metal salt solution A; Preparation of solution B: Dissolve anhydrous sodium carbonate in water to prepare a 30% solution B; Preparation of solution C: Dissolve 50g of liquid silicon completely in 200mL of deionized water and stir until there are no obvious particles to form a transparent solution C.

[0019] S2: Coprecipitation reaction: Install a stirrer, pH monitor, and temperature control device in the reaction vessel containing solution C. Set the stirring speed to 250 rpm and the reaction temperature to 60℃. Simultaneously add solutions A and B to solution C using a peristaltic pump. The dropping rate of solution A is fixed at 3.5 mL / min, while the dropping rate of solution B is dynamically adjusted based on the pH monitoring results to ensure that the pH of the system remains neutral throughout the reaction process. During the dropping process, record the solution temperature and pH value every 10 minutes to ensure stable reaction conditions.

[0020] S3: Post-processing: After solutions A and B are added dropwise, the reaction system is kept at 60℃ for 0.5 hours to age and form a uniform precipitate. The aged precipitate is filtered using a vacuum filtration device, and the filter cake is repeatedly washed with deionized water until the washing liquid is neutral (pH=7). The washed filter cake is placed in a 100℃ oven to dry until the moisture content of the filter cake is less than 7%. The dried solid is then transferred to a muffle furnace and calcined at 550℃. After calcination, it is cooled to room temperature to obtain the catalyst semi-finished product.

[0021] S4: Tableting: Select a tableting mold with a size of 0.3×0.3mm, weigh 0.15g of the above catalyst semi-finished product and put it into the mold, set the tableting machine full pressing time to 30s and the pressure to 2.6N, start the tableting machine to complete the tableting, and obtain the finished catalyst.

[0022] The performance testing method is as follows: The finished catalyst is loaded into the reaction device, and the feed rate is controlled at 0.2 kg / h, the gas flow rate is 350 L / h to 400 L / h, the circulating gas flow rate is 1.2 kg / h, the test pressure is 3.8 MPa, and the initial test temperature is 180℃. Under each test condition, 10 monitoring points are stably operated. The first 6 unstable points are removed, and the detection data of the last 4 stable points are used for catalyst performance analysis. The selectivity of the catalyst for C8-C16 branched higher alcohols in this embodiment is 95.8%.

[0023] Examples 2-5 (Example group of examples with variable liquid silicon usage) In this set of examples, only the amount of liquid silicon in solution C was changed. The other preparation steps, parameters, and test conditions were completely consistent with those in Example 1. The specific variables and their corresponding performance relationships are shown in Table 1.

[0024] Test results show that the catalyst with the highest selectivity was achieved when 50g of liquid silicon was added. Excessive use of liquid silicon can lead to the covering of active sites, resulting in a decrease in the selectivity of the catalyst for higher alcohols.

[0025] Examples 6-8 (Preparation of Temperature Variable Example Group) In this set of examples, only the reaction temperature of the coprecipitation reaction stage was changed. The other preparation steps, parameters, and test conditions were completely consistent with those in Example 1. The specific variables and their corresponding performance relationships are shown in Table 2.

[0026] Test results show that the optimal preparation temperature is 60℃. Too high a temperature will lead to the loss of active sites, while too low a temperature will lead to a decrease in the dispersion of active sites.

[0027] The above examples adopt the principle of high-carbon alcohol selectivity evaluation. High-carbon alcohol selectivity can reflect the proportion of the target product (C8-C16 branched high-carbon alcohols) in the total product in the catalytic reaction, and can directly reflect the influence of the above variables on the catalyst's ability to directionally convert raw materials.

[0028] Examples 9-12 (Example group of saturation time variable examples) In this set of examples, only the full compression time during the tableting stage was changed. All other preparation steps, parameters, and testing conditions were completely consistent with those in Example 1. The specific variables and their corresponding performance relationships are shown in Table 3.

[0029] Test results show that the optimal saturation time during tableting is 30 seconds. Too short a time will result in the catalyst's radial compressive strength being lower than the required value of 100 N.

[0030] Examples 13-16 (Tablet Compression Pressure Variable Example Group) In this set of examples, only the pressure during the tableting stage was changed. All other preparation steps, parameters, and testing conditions were completely consistent with those in Example 1. The specific variables and their corresponding performance relationships are shown in Table 4.

[0031] Test results show that the optimal pressure during tableting is 2.6 N. Insufficient pressure will cause the catalyst's radial compressive strength to fall below the required value of 100 N, while increasing the pressure does not significantly improve the catalyst's mechanical strength or resistance to breakage.

[0032] The above examples use the evaluation principle of axial compression and radial compression of the finished catalyst tablets. Axial compression (axial compressive strength) and radial compression (radial compressive strength) are indicators for measuring the physical and mechanical strength of the formed catalyst. They can directly reflect the influence of the above variables on the physical properties of the catalyst, so as to determine whether the catalyst can be adapted to industrial reaction conditions.

[0033] It will be apparent to those skilled in the art that the invention is not limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered exemplary and non-limiting in all respects, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the invention.

[0034] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A copper-silicon catalyst for synthesizing higher alcohols, characterized in that: The product includes an active component, a carrier, and an additive. The active component is copper, derived from copper nitrate trihydrate, and the amount of copper nitrate trihydrate used is 230g. The carrier is a silicon-based carrier derived from liquid silicon, and the amount of liquid silicon used is 25-100g. The additive is calcium, derived from calcium nitrate tetrahydrate, and the amount of calcium nitrate tetrahydrate used is 69g.

2. A method for preparing the copper-silicon catalyst as described in claim 1, characterized in that: Includes the following steps: S1: Raw material preparation: Prepare a mixed metal salt solution A containing copper nitrate trihydrate and calcium nitrate tetrahydrate, a sodium carbonate solution with a concentration of 30%, and a transparent solution C containing liquid silica; S2: Coprecipitation reaction: Solution A and solution B are simultaneously added dropwise to solution C at 60℃, with the dropwise addition rate of solution A controlled at 3.5 mL / min, the pH of the system neutral, and the stirring speed at 250 rpm; S3: Post-treatment: After reaction, allow to stand at 60℃ for 0.5h for aging, filter and wash until the filtrate is neutral, dry at 100℃ until the moisture content is less than 7%, calcine at 550℃ and then cool. S4: Tableting: Take 0.15g of the calcined solid and press it into tablets using a 0.3×0.3mm mold. Control the saturation time and pressure to obtain the finished catalyst.

3. The method for preparing the copper-silicon catalyst according to claim 2, characterized in that: In S1, the mixed metal salt solution A is prepared by dissolving 220g of copper nitrate trihydrate and 69g of calcium nitrate tetrahydrate in 150g of water, and the solution C is prepared by dissolving 50g of liquid silicon in 200mL of deionized water.

4. The method for preparing the copper-silicon catalyst according to claim 2, characterized in that: In S2, the solution temperature and pH value were recorded every 10 minutes during the dropwise addition process.

5. The method for preparing the copper-silicon catalyst according to claim 2, characterized in that: In S3, a vacuum filtration device is used for filtration, and washing is stopped when the pH of the washing solution reaches 7.

6. The method for preparing the copper-silicon catalyst according to claim 2, characterized in that: In S4, the saturation time is 30s and the pressure is 2.6N.

Images