Method for preparing tetrahydrofuran by harmlessly treating BDO organic waste liquid
By preparing composite catalysts with mesoporous structures and new reaction media, the problems of difficult catalyst preparation and single reaction media in the existing BDO organic waste liquid treatment technology are solved, and efficient and stable BDO organic waste liquid treatment is achieved, which significantly improves the yield of tetrahydrofuran and reduces energy consumption.
Patent Information
- Application Number
- CN202510207985.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-25
- Publication Date
- 2025-05-27
AI Technical Summary
The existing BDO organic waste liquid treatment technology has problems such as difficult to control catalyst preparation, poor structure, single reaction medium, poor mass transfer, high energy consumption and weak synergy, which is difficult to meet industrial needs.
By preparing a composite catalyst with a mesoporous structure, the catalyst is embedded in transition metal nickel and cobalt nanoparticles in the matrix composed of a silicon oxygen skeleton and a rare earth metal cerium, combined with a new reaction medium, the target ionic liquid obtained by exchanging the initial ionic liquid with potassium hexafluorophosphate ion is combined with supercritical carbon dioxide.
It significantly improves the catalytic activity, selectivity and stability of BDO organic waste liquid, enhances the targeted processing capacity of various components, reduces side reactions, improves the yield of tetrahydrofuran, and reduces energy consumption, ensuring the stability and reliability of the treatment process.
Smart Images
Figure CN120040389A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of organic chemical waste treatment, in particular to a method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran. Background Art
[0002] The organic matter contained in BDO organic waste liquid has high chemical oxygen demand (COD) and biological oxygen demand (BOD). Direct discharge will consume dissolved oxygen in the water body, causing water quality deterioration and affecting the survival of aquatic organisms. At the same time, some components in the waste liquid may be toxic and bioaccumulative, posing a potential threat to human health through the food chain. In addition, with the increasingly stringent environmental protection regulations, the requirements for the discharge of industrial waste liquid are getting higher and higher. Enterprises are facing huge environmental pressure. Therefore, it is urgent to seek effective BDO organic waste liquid treatment methods; The existing technology has certain defects. The first is the lack of synergistic composite system materials. At present, the material systems used for BDO organic waste liquid treatment are mostly single materials or simple combinations, lacking synergistic effects between the components. In the combination of catalyst and carrier, the two are only a simple loading relationship, which cannot give full play to the synergistic catalytic effect and cannot effectively improve the activity, selectivity and stability of the reaction. In contrast, synergistic composite system materials are expected to break through the limitations of the existing technology. Secondly, the existing BDO organic waste liquid treatment technology has difficult control of catalyst preparation, poor structure, single reaction medium, poor mass transfer, high energy consumption, and weak synergy between the two, poor adaptability to waste liquid, and difficulty in meeting industrial needs. To this end, we propose a method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran. Summary of the invention
[0003] The object of the present invention is to provide a method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran.
[0004] In order to solve the problems raised in the above background technology, the present invention provides the following technical solution: a method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran, the method comprising the following specific steps: Step 1, weighing nickel nitrate, cobalt nitrate and cerium nitrate as raw materials, dissolving them in deionized water to prepare a metal salt solution, slowly dropping a sodium carbonate solution into the metal salt solution while stirring, and controlling the pH value of the solution to precipitate metal ions, continuing to stir after precipitation is complete, then aging at room temperature, then washing the precipitate with deionized water, and filtering to obtain a precursor; Step 2: Mix the precursor, citric acid and tetraethyl orthosilicate in anhydrous ethanol, then add hydrochloric acid solution and stir evenly, stir to form a sol and transform it into a gel, tetraethyl orthosilicate undergoes a hydrolysis reaction under the catalysis of hydrochloric acid to generate silanol groups, and as the reaction proceeds, a polycondensation reaction occurs between the silanol groups to form silicon-oxygen bonds, gradually building up a three-dimensional network structure, and as the polycondensation reaction continues, the sol particles in the system gradually grow and connect to each other, and the viscosity of the solution gradually increases. When the viscosity increases to a certain extent, the system loses fluidity and transforms from a sol to a gel, and the gel is placed in an oven to dry to remove organic solvents and moisture, and then placed in a muffle furnace for calcination, thereby obtaining a composite catalyst with a specific structure, and the composite catalyst has a mesoporous structure with a pore size of Distributed between 2nm-5nm, the specific surface area reaches 200㎡ / g-300㎡ / g. Among them, transition metal nickel and cobalt are embedded in the matrix composed of silicon-oxygen skeleton and rare earth metal cerium in the form of highly dispersed nanoparticles. This unique structure enables strong interaction between the active components. On the one hand, the silicon-oxygen skeleton provides a high specific surface area and stable physical support, which is conducive to the adsorption and diffusion of reactants. On the other hand, rare earth metal cerium can adjust the electron cloud density on the catalyst surface, enhance the activation ability of reactants, and improve the anti-sintering performance of the catalyst. The highly dispersed nickel and cobalt nanoparticles provide rich and efficient active sites for the reaction of converting BDO organic waste liquid into tetrahydrofuran, greatly improving the catalytic performance. Step 3, reacting N-methylimidazole and n-butyl chloride as raw materials to generate 1-butyl-3-methylimidazole chloride ionic liquid, then reacting the ionic liquid with potassium hexafluorophosphate to perform ion exchange, obtaining the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate, adding the target ionic liquid and supercritical carbon dioxide into a high-pressure reactor, adjusting the temperature and pressure of the reactor to make the carbon dioxide reach a supercritical state, and simultaneously starting a stirring device to perform stirring reaction, thereby obtaining a novel reaction medium; Step 4: adding the composite catalyst to a high-pressure reactor filled with a novel reaction medium, and then adding an organic waste liquid for reaction, and monitoring the temperature, pressure, and concentration changes of reactants and products of the reaction system in real time by an online mass spectrometer to optimize the reaction process. After the reaction, the temperature of the reactor is lowered to room temperature, and the pressure is lowered to normal pressure, so that the supercritical carbon dioxide is converted back to a gaseous state and separated from the ionic liquid and the reaction product, and the ionic liquid containing tetrahydrofuran is transferred to a distillation tower for distillation to separate the tetrahydrofuran product. The ionic liquid can be reused for more than 5 times, and the catalyst after the reaction is regenerated by a combination of solvent washing and roasting for next use.
[0005] As a further solution of the present invention: in the step 1, 25g-35g of nickel nitrate, 15g-25g of cobalt nitrate and 8g-12g of cerium nitrate are weighed and dissolved in 400mL-600mL of deionized water to prepare a metal salt solution.
[0006] As a further scheme of the present invention: in the step 1, at a stirring speed of 300r / min-350r / min, a sodium carbonate solution with a concentration of 0.8mol / L-1.2mol / L is added to the metal salt solution, and the pH value of the solution is controlled at 8.0-9.0 to precipitate the metal ions. After the precipitation is complete, stirring is continued for 0.5h-1.5h, followed by aging at room temperature for 10h-14h, and then the precipitate is washed with deionized water 4-6 times, with a water consumption of 150mL-250mL each time.
[0007] As a further scheme of the present invention: in the step 2, the precursor is mixed with 15g-25g of citric acid and 40mL-60mL of tetraethyl orthosilicate in 400mL-600mL of anhydrous ethanol, and then 25mL-35mL of a hydrochloric acid solution with a concentration of 1.5mol / L-2.5mol / L is added, and the mixture is stirred evenly at a speed of 200r / min-300r / min, and the mixture is stirred and reacted at 55°C-65°C for 8h-12h to form a sol and transform it into a gel.
[0008] As a further solution of the present invention: in the step 2, after obtaining the gel, the gel is placed in an oven and dried at 75°C-85°C for 20h-28h to remove the organic solvent and moisture, then placed in a muffle furnace and heated to 550°C-650°C at a heating rate of 2°C / min-4°C / min, and the calcination time is 4h-6h.
[0009] As a further scheme of the present invention: in the step three, 45g-55g of N-methylimidazole and 75g-85g of n-butyl chloride are used as raw materials, and the reaction is carried out at 75°C-85°C for 10h-14h to generate 1-butyl-3-methylimidazole chloride ionic liquid, which is then reacted with potassium hexafluorophosphate at a molar ratio of 1:1.1-1.3 at 45°C-55°C for 6h-10h for ion exchange to obtain the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate.
[0010] As a further scheme of the present invention: in the step three, 180g-220g of the target ionic liquid and supercritical carbon dioxide are added to a 5L-6L high-pressure reactor in a mass ratio of 1:2.5-3.5, the temperature of the reactor is adjusted to 32°C-38°C, and the pressure is adjusted to 7MPa-9MPa to make the carbon dioxide reach a supercritical state, and at the same time, the stirring device is turned on and stirred at a speed of 350r / min-450r / min for 25min-35min to obtain a new reaction medium.
[0011] As a further solution of the present invention: in the step 4, 45-55 g of the composite catalyst is added to a high-pressure reactor filled with a novel reaction medium, and then 450 mL-550 mL of BDO organic waste liquid is added for reaction, and after sealing, helium is used for leak detection. During the reaction, the temperature of the reactor is controlled at 170° C.-230° C., and the pressure is controlled at 2.5 MPa-5.5 MPa.
[0012] As a further solution of the present invention: in the step 4, the ionic liquid phase containing tetrahydrofuran is transferred to a distillation tower, and distilled under the conditions of a theoretical plate number of 35-45, a reflux ratio of 5-7:1, and a tower top temperature controlled at 63° C.-67° C. to separate the tetrahydrofuran product.
[0013] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are: 1. In the preparation of the multifunctional composite catalyst, the present invention uses nickel nitrate, cobalt nitrate and cerium nitrate as raw materials to prepare a precursor, and then forms a composite catalyst containing transition metals and rare earth metals through the steps of coprecipitation, sol-gel, drying and calcination. The composite catalyst has a mesoporous structure, and the transition metal is uniformly dispersed in the matrix composed of a silicon-oxygen skeleton and rare earth metals in the form of nanoparticles. The elements in the precursor are converted to form active sites. The unique structure enables synergistic effects between the components of the catalyst, thereby improving the catalytic activity, selectivity and stability of BDO organic waste liquid. Secondly, the target ionic liquid obtained by exchanging the synthesized initial ionic liquid with potassium hexafluorophosphate ions forms a new reaction medium with supercritical carbon dioxide. The ionic liquid has special dissolution and selectivity properties for the reaction system, and the supercritical carbon dioxide provides good mass transfer performance. The reaction medium formed by the synergistic formation of the two not only strengthens the mass transfer and dissolution process, but also facilitates the distribution of reactants and products, greatly promotes the conversion reaction of BDO organic waste liquid to tetrahydrofuran, and significantly improves the treatment efficiency and product quality. 2. The composite catalyst formed by the precursor undergoing precisely controlled precipitation, gelation and calcination treatments during the preparation of the multifunctional composite catalyst of the present invention has a unique mesoporous structure and a reasonable distribution of active components, so that the transition metal and rare earth metal in the precursor achieve complementary advantages, enhance the targeted treatment capability of various components in the BDO organic waste liquid, significantly reduce the occurrence of side reactions, and improve the yield of tetrahydrofuran. At the same time, the novel reaction medium constructed combines ionic liquid with supercritical carbon dioxide, and utilizes the special solubility of ionic liquid for different substances and the high diffusivity of supercritical carbon dioxide. During the reaction process, not only the viscosity of the reaction system is reduced, the material transfer speed is accelerated, but also the reaction can be carried out under relatively mild conditions, reducing energy consumption. The reaction medium and the composite catalyst work synergistically, and have stronger adaptability to BDO organic waste liquids of different sources and different component ratios, ensuring the stability and reliability of the entire treatment process, and providing solid technical support for large-scale industrial applications. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 Schematic diagram of the method steps in an embodiment of the present invention. DETAILED DESCRIPTION
[0015] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.
[0016] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.
[0017] Please see attached Figure 1 The present invention provides a method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran, the method comprising the following specific steps: Step 1, weighing nickel nitrate, cobalt nitrate and cerium nitrate as raw materials, dissolving them in deionized water to prepare a metal salt solution, slowly dropping a sodium carbonate solution into the metal salt solution while stirring, and controlling the pH value of the solution to precipitate metal ions, continuing to stir after precipitation is complete, then aging at room temperature, then washing the precipitate with deionized water, and filtering to obtain a precursor; Step 2: Mix the precursor, citric acid and tetraethyl orthosilicate in anhydrous ethanol, then add hydrochloric acid solution and stir evenly, stir to form a sol and transform it into a gel, tetraethyl orthosilicate undergoes a hydrolysis reaction under the catalysis of hydrochloric acid to generate silanol groups, and as the reaction proceeds, a polycondensation reaction occurs between the silanol groups to form silicon-oxygen bonds, gradually building up a three-dimensional network structure, and as the polycondensation reaction continues, the sol particles in the system gradually grow and connect to each other, and the viscosity of the solution gradually increases. When the viscosity increases to a certain extent, the system loses fluidity and transforms from a sol to a gel, and the gel is placed in an oven to dry to remove organic solvents and moisture, and then placed in a muffle furnace for calcination, thereby obtaining a composite catalyst with a specific structure, and the composite catalyst has a mesoporous structure with a pore size of Distributed between 2nm-5nm, the specific surface area reaches 200㎡ / g-300㎡ / g. Among them, transition metal nickel and cobalt are embedded in the matrix composed of silicon-oxygen skeleton and rare earth metal cerium in the form of highly dispersed nanoparticles. This unique structure enables strong interaction between the active components. On the one hand, the silicon-oxygen skeleton provides a high specific surface area and stable physical support, which is conducive to the adsorption and diffusion of reactants. On the other hand, rare earth metal cerium can adjust the electron cloud density on the catalyst surface, enhance the activation ability of reactants, and improve the anti-sintering performance of the catalyst. The highly dispersed nickel and cobalt nanoparticles provide rich and efficient active sites for the reaction of converting BDO organic waste liquid into tetrahydrofuran, greatly improving the catalytic performance. Step 3, reacting N-methylimidazole and n-butyl chloride as raw materials to generate 1-butyl-3-methylimidazole chloride ionic liquid, then reacting the ionic liquid with potassium hexafluorophosphate to perform ion exchange, obtaining the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate, adding the target ionic liquid and supercritical carbon dioxide into a high-pressure reactor, adjusting the temperature and pressure of the reactor to make the carbon dioxide reach a supercritical state, and simultaneously starting a stirring device to perform stirring reaction, thereby obtaining a novel reaction medium; Step 4: adding the composite catalyst to a high-pressure reactor filled with a novel reaction medium, and then adding an organic waste liquid for reaction, and monitoring the temperature, pressure, and concentration changes of reactants and products of the reaction system in real time by an online mass spectrometer to optimize the reaction process. After the reaction, the temperature of the reactor is lowered to room temperature, and the pressure is lowered to normal pressure, so that the supercritical carbon dioxide is converted back to a gaseous state and separated from the ionic liquid and the reaction product, and the ionic liquid containing tetrahydrofuran is transferred to a distillation tower for distillation to separate the tetrahydrofuran product. The ionic liquid can be reused for more than 5 times, and the catalyst after the reaction is regenerated by a combination of solvent washing and roasting for next use.
[0018] In one embodiment of the present invention: in step 1, 25g-35g of nickel nitrate, 15g-25g of cobalt nitrate and 8g-12g of cerium nitrate are weighed and dissolved in 400mL-600mL of deionized water to prepare a metal salt solution.
[0019] In one embodiment of the present invention: in step 1, at a stirring speed of 300r / min-350r / min, a sodium carbonate solution with a concentration of 0.8mol / L-1.2mol / L is added to the metal salt solution, and the pH value of the solution is controlled at 8.0-9.0 to precipitate the metal ions. After the precipitation is complete, stirring is continued for 0.5h-1.5h, followed by aging at room temperature for 10h-14h, and then the precipitate is washed 4-6 times with deionized water, each time with a water consumption of 150mL-250mL.
[0020] In one embodiment of the present invention: in step 2, the precursor is mixed with 15g-25g of citric acid and 40mL-60mL of tetraethyl orthosilicate in 400mL-600mL of anhydrous ethanol, and then 25mL-35mL of a hydrochloric acid solution with a concentration of 1.5mol / L-2.5mol / L is added, and stirred evenly at a speed of 200r / min-300r / min, and stirred at 55°C-65°C for 8h-12h to form a sol and transform it into a gel.
[0021] In one embodiment of the present invention: in step 2, after obtaining the gel, the gel is placed in an oven and dried at 75°C-85°C for 20h-28h to remove the organic solvent and moisture, then placed in a muffle furnace and heated to 550°C-650°C at a heating rate of 2°C / min-4°C / min, and the calcination time is 4h-6h.
[0022] In one embodiment of the present invention: in step three, 45g-55g of N-methylimidazole and 75g-85g of n-butyl chloride are used as raw materials, and the reaction is carried out at 75°C-85°C for 10h-14h to generate 1-butyl-3-methylimidazole chloride ionic liquid, which is then reacted with potassium hexafluorophosphate at a molar ratio of 1:1.1-1.3 at 45°C-55°C for 6h-10h for ion exchange to obtain the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate.
[0023] In one embodiment of the present invention: in step three, 180g-220g of the target ionic liquid and supercritical carbon dioxide are added to a 5L-6L high-pressure reactor in a mass ratio of 1:2.5-3.5, the temperature of the reactor is adjusted to 32°C-38°C, and the pressure is adjusted to 7MPa-9MPa to make the carbon dioxide reach a supercritical state, and at the same time, the stirring device is turned on and stirred at a speed of 350r / min-450r / min for 25min-35min to obtain a new reaction medium.
[0024] In one embodiment of the present invention: in step 4, 45-55 g of the composite catalyst is added to a high-pressure reactor filled with a novel reaction medium, and then 450 mL-550 mL of BDO organic waste liquid is added for reaction, and after sealing, helium is used for leak detection. During the reaction, the temperature of the reactor is controlled at 170° C.-230° C., and the pressure is controlled at 2.5 MPa-5.5 MPa.
[0025] In one embodiment of the present invention: in step 4, the ionic liquid phase containing tetrahydrofuran is transferred to a distillation tower, and distilled under the conditions of a theoretical plate number of 35-45, a reflux ratio of 5-7:1, and a tower top temperature controlled at 63° C.-67° C. to separate the tetrahydrofuran product.
[0026] In one embodiment of the present invention: in step 1, when sodium carbonate solution is added dropwise for precipitation reaction, ultrasonic assisted precipitation is adopted, the ultrasonic frequency is 20kHz-50kHz, and the power is 100W-500W. Through the synergistic effect of ultrasonic cavitation effect and mechanical stirring, the metal ion precipitation is made more uniform and rapid, and the formed precipitated particles have smaller particle size and narrower particle size distribution, thereby improving the performance of the precursor, providing a more uniform distribution of active sites for the subsequently prepared composite catalyst, and further improving the catalytic activity and selectivity.
[0027] In one embodiment of the present invention: in step 2, an appropriate amount of nano metal oxide is added to the mixed system of the precursor, citric acid, tetraethyl orthosilicate and hydrochloric acid solution. The nano metal oxide is nano titanium dioxide or nano zinc oxide, and the added amount is 1wt%-5wt% of the mass of the precursor. The nano metal oxide acts as a co-catalyst, which can adjust the electronic structure and acidity and alkalinity of the catalyst surface, enhance the activity and stability of the composite catalyst, improve the tolerance to different impurities in the BDO organic waste liquid, reduce the occurrence of side reactions, and thus improve the yield of tetrahydrofuran.
[0028] In one embodiment of the present invention: in step 3, when the target ionic liquid is mixed with supercritical carbon dioxide, a trace amount of surfactant is added, the surfactant is polyoxyethylene ether or sodium dodecylbenzene sulfonate, and the added amount is 0.1wt%-1wt% of the mass of the target ionic liquid. The surfactant can improve the interfacial properties between the ionic liquid and the supercritical carbon dioxide, improve the compatibility and synergistic effect between the two, optimize the mass transfer performance, improve the reaction efficiency, reduce the energy consumption of the reaction, and promote the conversion of BDO organic waste liquid.
[0029] In one embodiment of the present invention: in step 4, after the reaction is completed, the ionic liquid phase containing tetrahydrofuran is subjected to membrane separation treatment, the membrane used is a ceramic membrane or an organic polymer membrane, the pore size of the membrane is 0.1 μm-1 μm, and the membrane separation process is carried out at room temperature and low pressure conditions. The membrane separation can further remove the trace impurities remaining in the tetrahydrofuran product, improve the purity of the product, and at the same time achieve partial recovery of the ionic liquid, reduce the energy consumption and solvent usage in the separation process, and improve the economy and environmental protection of the entire process.
[0030] Example 1, please refer to the attached Figure 1 , 35g nickel nitrate, 25g cobalt nitrate and 12g cerium nitrate were weighed in proportion, dissolved in 600mL deionized water to prepare a metal salt solution, and a sodium carbonate solution with a concentration of 1.2mol / L was slowly added to the metal salt solution at a stirring speed of 350r / min, while the pH value of the solution was controlled at 9.0 to precipitate the metal ions. After the precipitation was complete, stirring was continued for 1.5h, and then aged at room temperature for 14h, and then the precipitate was washed with deionized water for 6 times, each time with 250mL of water, and the precursor was filtered to obtain the precursor, and the precursor was mixed with 25g citric acid and 6 0mL of ethyl orthosilicate was mixed in 600mL of anhydrous ethanol, and then 35mL of a hydrochloric acid solution with a concentration of 2.5mol / L was added, and the mixture was stirred at a speed of 300r / min. The mixture was stirred and reacted at 65℃ for 12h to form a sol and then transformed into a gel. The gel was placed in an oven and dried at 85℃ for 28h to remove the organic solvent and moisture. Then, the gel was placed in a muffle furnace and heated to 650℃ at a heating rate of 4℃ / min and calcined for 6h to obtain a composite catalyst with a specific structure. 55g of N-methylimidazole and 85g of n-butyl chloride were used as raw materials and reacted at 85℃ for 12h. The ionic liquid 1-butyl-3-methylimidazole chloride was generated by reacting it with potassium hexafluorophosphate at a molar ratio of 1:1.3 at 55°C for 10 hours for ion exchange to obtain the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate. 220g of the target ionic liquid and supercritical carbon dioxide were added to a 6L high-pressure reactor at a mass ratio of 1:3.5. The temperature of the reactor was adjusted to 38°C and the pressure was adjusted to 9MPa to make the carbon dioxide reach a supercritical state. At the same time, the stirring device was turned on and stirred at a speed of 450r / min for 35min. g composite catalyst was added into a high-pressure reactor filled with a novel reaction medium, and then 550 mL of BDO organic waste liquid was added. After sealing, helium was used to detect leaks. During the reaction, the temperature of the reactor was controlled at 230° C. and the pressure was controlled at 5.5 MPa. After the reaction was completed, the temperature of the reactor was lowered to room temperature and the pressure was lowered to normal pressure to convert the supercritical carbon dioxide back into a gaseous state and separate it from the ionic liquid and the reaction product. The ionic liquid phase containing tetrahydrofuran was transferred to a distillation tower, and distilled under the conditions of a theoretical plate number of 45, a reflux ratio of 7:1, and a tower top temperature controlled at 67° C. to separate the tetrahydrofuran product.
[0031] Example 2, please refer to the attached Figure 1 , 25g nickel nitrate, 15g cobalt nitrate and 8g cerium nitrate were weighed in proportion, dissolved in 400mL deionized water to prepare a metal salt solution, and a sodium carbonate solution with a concentration of 0.8mol / L was slowly added to the metal salt solution at a stirring speed of 300r / min, while the pH value of the solution was controlled at 8.0 to precipitate the metal ions. After the precipitation was complete, stirring was continued for 0.5h, and then aged at room temperature for 10h, and then the precipitate was washed 4 times with deionized water, each time with 150mL of water, and the precursor was filtered to obtain the precursor, and the precursor was mixed with 15g citric acid and 40 mL of ethyl orthosilicate was mixed in 400 mL of anhydrous ethanol, and then 25 mL of a hydrochloric acid solution with a concentration of 1.5 mol / L was added, and stirred at a speed of 200 r / min. The mixture was stirred and reacted at 55 ° C for 8 h to form a sol and then transformed into a gel. The gel was placed in an oven and dried at 75 ° C for 20 h to remove the organic solvent and moisture. Then, it was placed in a muffle furnace and heated to 550 ° C at a heating rate of 2 ° C / min and calcined for 4 h to obtain a composite catalyst with a specific structure. 45 g of N-methylimidazole and 75 g of n-butyl chloride were used as raw materials and reacted at 75 ° C. 10h, 1-butyl-3-methylimidazole chloride ionic liquid is generated, and then it is reacted with potassium hexafluorophosphate at a molar ratio of 1:1.1 at 45°C for 6h for ion exchange to obtain the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate. 180g of the target ionic liquid and supercritical carbon dioxide are added to a 5L high-pressure reactor at a mass ratio of 1:2.5. The reactor temperature is adjusted to 32°C and the pressure is adjusted to 7MPa to make the carbon dioxide reach a supercritical state. At the same time, the stirring device is turned on and stirred at a speed of 350r / min for 25min. 45g The composite catalyst is added into a high-pressure reactor filled with a novel reaction medium, and then 450 mL of BDO organic waste liquid is added. After sealing, helium is used for leak detection. During the reaction, the temperature of the reactor is controlled at 170° C. and the pressure is controlled at 2.5 MPa. After the reaction is completed, the temperature of the reactor is lowered to room temperature and the pressure is lowered to normal pressure, so that the supercritical carbon dioxide is converted back into a gaseous state and separated from the ionic liquid and the reaction product. The ionic liquid phase containing tetrahydrofuran is transferred to a distillation tower, and distillation is performed under the conditions of a theoretical plate number of 35, a reflux ratio of 5:1, and a tower top temperature controlled at 63° C. to separate the tetrahydrofuran product.
[0032] According to the above two groups of embodiments, it can be concluded that by using nickel nitrate, cobalt nitrate and cerium nitrate as raw materials to prepare a precursor, and then synthesizing a multifunctional composite catalyst through coprecipitation, sol-gel, drying and calcination, and synthesizing a new reaction medium, the multifunctional composite catalyst is synergistically applied to the treatment of BDO organic waste liquid with the composite catalyst, and the conversion of BDO organic waste liquid into tetrahydrofuran is effectively achieved, wherein the mesoporous structure and active component distribution of the composite catalyst enable the transition metal and the rare earth metal to produce a synergistic effect and complementary advantages, thereby improving the catalytic activity, selectivity and stability of the BDO organic waste liquid, and enhancing the targeted treatment of various components. The novel reaction medium combines the special dissolution and selectivity of ionic liquids with the good mass transfer performance of supercritical carbon dioxide, which not only strengthens the mass transfer and dissolution process, but also facilitates the distribution of reactants and products. It also reduces the viscosity of the reaction system, allowing the reaction to proceed under mild conditions and reducing energy consumption. At the same time, the two work together to have stronger adaptability to BDO organic waste liquids of different sources and component ratios, ensuring the stability and reliability of the treatment process. The process has significant technical advantages and has broad application prospects in the field of BDO organic waste liquid treatment.
[0033] Although the present invention is disclosed as above in terms of preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modification, equivalent change and modification made to the above embodiments according to the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.
Claims
1. A method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran, characterized in that: The method comprises the following specific steps: Step 1, weighing nickel nitrate, cobalt nitrate and cerium nitrate as raw materials, dissolving them in deionized water to prepare a metal salt solution, slowly dropping a sodium carbonate solution into the metal salt solution while stirring, and controlling the pH value of the solution to precipitate metal ions, continuing to stir after precipitation is complete, then aging at room temperature, then washing the precipitate with deionized water, and filtering to obtain a precursor; Step 2: Mix the precursor, citric acid and tetraethyl orthosilicate in anhydrous ethanol, add hydrochloric acid solution and stir evenly, stir to form a sol and transform it into a gel, place the gel in an oven to dry to remove organic solvent and water, and then place it in a muffle furnace for calcination to obtain a composite catalyst; Step 3, reacting N-methylimidazole and n-butyl chloride as raw materials to generate 1-butyl-3-methylimidazole chloride ionic liquid, then reacting the ionic liquid with potassium hexafluorophosphate to perform ion exchange, obtaining the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate, adding the target ionic liquid and supercritical carbon dioxide into a high-pressure reactor, adjusting the temperature and pressure of the reactor to make the carbon dioxide reach a supercritical state, and simultaneously starting a stirring device to perform stirring reaction, thereby obtaining a novel reaction medium; Step 4: adding the composite catalyst into a high-pressure reactor filled with a novel reaction medium, and then adding organic waste liquid to react. After the reaction is completed, the temperature of the reactor is lowered to room temperature and the pressure is lowered to normal pressure, so that the supercritical carbon dioxide is converted back to a gaseous state and separated from the ionic liquid and the reaction product, and the ionic liquid containing tetrahydrofuran is transferred to a distillation tower for distillation to separate the tetrahydrofuran product.
2. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 1, 25 g to 35 g of nickel nitrate, 15 g to 25 g of cobalt nitrate and 8 g to 12 g of cerium nitrate are weighed and dissolved in 400 mL to 600 mL of deionized water to prepare a metal salt solution.
3. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 1, at a stirring speed of 300 r / min-350 r / min, a sodium carbonate solution with a concentration of 0.8 mol / L-1.2 mol / L is added to the metal salt solution, and the pH value of the solution is controlled at 8.0-9.0 to precipitate the metal ions. After the precipitation is complete, stirring is continued for 0.5 h-1.5 h, followed by aging at room temperature for 10 h-14 h, and then the precipitate is washed 4-6 times with deionized water, each time using 150 mL-250 mL of water.
4. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 2, the precursor is mixed with 15g-25g of citric acid and 40mL-60mL of tetraethyl orthosilicate in 400mL-600mL of anhydrous ethanol, and then 25mL-35mL of a hydrochloric acid solution with a concentration of 1.5mol / L-2.5mol / L is added, and stirred evenly at a speed of 200r / min-300r / min. The mixture is stirred and reacted at 55°C-65°C for 8h-12h to form a sol and transform it into a gel.
5. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 2, after obtaining the gel, the gel is placed in an oven and dried at 75°C-85°C for 20h-28h to remove the organic solvent and moisture, then placed in a muffle furnace and heated to 550°C-650°C at a heating rate of 2°C / min-4°C / min, and the calcination time is 4h-6h.
6. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step three, 45g-55g of N-methylimidazole and 75g-85g of n-butyl chloride are used as raw materials, and the reaction is carried out at 75°C-85°C for 10h-14h to generate 1-butyl-3-methylimidazole chloride ionic liquid, which is then reacted with potassium hexafluorophosphate at a molar ratio of 1:1.1-1.3 at 45°C-55°C for 6h-10h for ion exchange to obtain the target ionic liquid 1-butyl-3-methylimidazole hexafluorophosphate.
7. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step three, 180g-220g of the target ionic liquid and supercritical carbon dioxide are added to a 5L-6L high-pressure reactor in a mass ratio of 1:2.5-3.5, the temperature of the reactor is adjusted to 32°C-38°C, and the pressure is adjusted to 7MPa-9MPa to make the carbon dioxide reach a supercritical state, and at the same time, the stirring device is turned on and stirred at a speed of 350r / min-450r / min for 25min-35min to obtain a new reaction medium.
8. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 4, 45-55 g of the composite catalyst is added to a high-pressure reactor filled with a novel reaction medium, and then 450 mL-550 mL of BDO organic waste liquid is added for reaction. After sealing, helium is used for leak detection. During the reaction, the temperature of the reactor is controlled at 170° C.-230° C., and the pressure is controlled at 2.5 MPa-5.5 MPa.
9. The method for harmlessly treating BDO organic waste liquid to prepare tetrahydrofuran according to claim 1, characterized in that: In the step 4, the ionic liquid phase containing tetrahydrofuran is transferred to a distillation tower, and distilled under the conditions of a theoretical plate number of 35-45, a reflux ratio of 5-7:1, and a tower top temperature controlled at 63° C.-67° C. to separate the tetrahydrofuran product.