Reactive distillation production process and device for preparing isobutanol
By adopting the reaction distillation process in the production of isobutanol, the mixture of methanol and ethanol is chemically reacted under the action of a catalyst, and high purity isobutanol is obtained through distillation separation, solving the problems of poor selectivity and high production cost in the existing process, and achieving efficient and low-cost isobutanol purification.
Patent Information
- Application Number
- CN202311192357.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-09-15
- Publication Date
- 2025-03-18
AI Technical Summary
The existing isobutanol production process has problems such as poor selectivity, many by-products and high production costs. Especially in chemical synthesis methods, high pressure carbonyl synthesis technology has poor selectivity and high production costs of biosynthesis methods.
The reaction distillation process is adopted to carry out chemical reactions of methanol and ethanol under the action of a catalyst, and high-purity isobutanol isolate through distillation. This process includes a reaction distillation tower, an extraction distillation tower and a solvent recovery tower. Through the design of the multi-layer tower and the use of extractive agent, the efficient purification of isobutanol is achieved.
The selectivity and conversion rate of isobutanol are improved, energy consumption and operating costs are reduced, high-purity isobutanol is achieved, and production costs are reduced through the recycling of extractive agents.
Smart Images
Figure CN119638551A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of chemical production processes and equipment, and relates to a reaction distillation production process and a device for preparing isobutanol. Background Art
[0002] Isobutanol is a colorless, transparent liquid with a special smell. It is used as an important intermediate substance in many industries such as food, medicine and chemical industry. As a new type of biofuel, isobutanol has its unique advantages and broad development prospects. For example, compared with biofuels, isobutanol has advantages such as high energy density and low hygroscopicity, so it is used as a new type of biofuel to supplement or replace gasoline. In addition to being a biofuel, isobutanol is also an important raw material for synthesizing plasticizers, fruit essential oils and medicines, an important ingredient for producing coatings and varnishes, and can be used as a substitute for n-butanol. Isobutanol can also be dehydrated to generate isobutylene with higher value, which is used as a raw material for plastics and diesel fuel.
[0003] At present, the production of isobutanol is mainly divided into two categories: chemical synthesis and biosynthesis. Among them, chemical synthesis is dominant. There are three main methods of chemical synthesis: (1) propylene carbonyl synthesis, which is produced by hydrogenation of isobutyraldehyde produced as a byproduct in the production of n-butanol and 2-ethylhexanol from propylene and synthesis gas; (2) isobutanol is obtained by synthesizing methanol from synthesis gas under the action of Cu-Mg catalyst; (3) isobutanol is produced by low-carbon alcohol using Zn-Cr oxide catalyst. The isobutanol propylene carbonyl synthesis method is divided into high-pressure method, medium-pressure method and low-pressure method. High-pressure carbonyl synthesis technology has been replaced by low-pressure carbonyl synthesis technology using rhodium as catalyst due to its poor selectivity and high number of byproducts (propane and high-boiling substances). The biosynthesis method produces isobutanol mainly by fermenting grain to produce a small amount of byproducts in n-butanol. This method has a high production cost and requires the use of expensive biological fungi.
[0004] Ethanol can be obtained by biological fermentation, and the ethanol obtained by this method is called bioethanol. Bioethanol is a renewable and sustainable liquid fuel. Its high oxygen content makes it burn cleaner and reduces the emission of toxic substances. Bioethanol is also a good internal combustion engine fuel that can prevent engine knock and premature ignition and has a high anti-knock value.
[0005] Distillation is the most common unit operation in multi-component separation and is the most widely used in chemical production. 90%-95% of product purification and recovery are achieved by distillation. Sometimes, due to the particularity of the physical properties of the components of the mixture, it is necessary to add various separation agents or use special distillation methods such as reactive distillation, extractive distillation, constant boiling distillation, etc. to achieve the specified separation requirements and improve the separation efficiency.
[0006] As a technical means of process intensification, reactive distillation is an operation process that couples chemical reaction and distillation separation, so that the reaction and separation processes proceed simultaneously. Therefore, chemical reaction and distillation operation both promote and restrict each other. Reactive distillation is to separate reactants and products by distillation, thereby destroying the reaction equilibrium relationship, ensuring that the direction of the reaction is the formation of products, and thus improving the conversion rate, selectivity, and production capacity of the reversible reaction. Moreover, when the reactive distillation process is carried out, the gas-liquid equilibrium relationship may also be destroyed by chemical reactions, which increases the mass transfer rate and reduces the reaction time. The heat released by the exothermic reaction can also be used for the vaporization heat required for the distillation reaction, reducing energy consumption and costs. Compared with traditional chemical production processes, reactive distillation has higher selectivity, which will improve the reaction conversion rate, production capacity, and product purity. It can also speed up the reaction speed, reduce energy consumption and operating costs, and has therefore been widely studied in recent years.
[0007] Extraction distillation is to add extractants or solvents to the raw materials to change the relative volatility of the original components and finally achieve the separation effect. The core competitiveness of extraction distillation technology lies in the solvent. A good solvent can not only greatly improve the quality of the product, but also greatly improve the production level of the enterprise, and can reasonably reduce the energy consumption of the enterprise in the production process, so as to reduce costs and increase the economic profit of the enterprise. The boiling point of the extractant is relatively high. In actual production, the selection and dosage of the extractant are quite particular. There are many types of extractants that can be selected in the production work of the extraction distillation process, and the effects that can be achieved by different types of extractants are different. Therefore, it is necessary to select the appropriate extractant for the extraction distillation process in the production process. Summary of the invention
[0008] In view of this, the object of the present invention is to provide a reactive distillation production process and device for preparing isobutanol. The process uses a mixed solution of methanol and ethanol as a raw material, undergoes a chemical reaction under the action of a catalyst, and obtains high-purity isobutanol through distillation separation. The reactants react in the reactive distillation section of the reactive distillation tower, and the mixed solution of methanol and ethanol enters the reactive distillation tower from the lower part of the tower, undergoes a chemical reaction in the tower, is separated and purified through the distillation section and the stripping section, and a mixture of water and isobutanol is obtained in the tower bottom, and then enters the extractive distillation tower for extractive distillation. Under the action of an extractant (e.g., 1,4-butanediol, ethyl acetate), light component water is obtained at the top of the tower, and a mixture of isobutanol and the extractant is obtained at the bottom of the tower, and then enters the solvent recovery tower, and high-purity isobutanol is obtained at the top of the tower. The tower bottom is an extractant with a purity of 99.99%, which can be recycled and then enters the extractive distillation tower. The device of the present invention comprises a reactive distillation tower, an extractive distillation tower, a solvent recovery tower, a raw material feed pump, three tower top condensers, three reflux tanks, three tower kettle reboilers, three reflux pumps, three tower top product pumps, and three tower bottom product pumps. The present invention realizes for the first time the use of reactive distillation technology to catalyze methanol and ethanol to prepare isobutanol, and relies on a distillation tower to separate the mixture.
[0009] In order to achieve the above object, the device of the present invention provides the following technical solutions:
[0010] A reactive distillation production process and device for preparing isobutanol. The device of the invention comprises a reactive distillation tower, an extractive distillation tower, a solvent recovery tower, a raw material feed pump, three tower top condensers, three reflux tanks, three tower kettle reboilers, three reflux pumps, three tower top product pumps, and three tower bottom product pumps.
[0011] The raw material feed pump is connected to the feed port of the reaction distillation tower through a pipeline; the tower top condenser is connected to the reaction distillation tower and a loop is formed between the two; the reboiler is connected to the reaction distillation tower and a loop is formed between the two; the reaction distillation tower is connected to the tower bottom reboiler. The tower top condenser is connected to the extraction distillation tower and a loop is formed between the two; the reboiler is connected to the extraction distillation tower and a loop is formed between the two; the extraction distillation tower is connected to the tower bottom reboiler. The tower top condenser is connected to the solvent recovery tower and a loop is formed between the two; the reboiler is connected to the solvent recovery tower and a loop is formed between the two; the solvent recovery tower is connected to the tower bottom reboiler.
[0012] The tower top condenser is connected with the reaction distillation tower and a loop is formed therebetween, which means that the tower top condenser is connected with the reflux tank and the reflux pump to form a loop with the distillation tower.
[0013] The top condenser is connected to the extractive distillation tower and a loop is formed therebetween, which means that the top condenser is connected to a reflux tank and a reflux pump to form a loop with the extractive distillation tower.
[0014] The tower top condenser is connected with the solvent recovery tower and a loop is formed therebetween, which means that the tower top condenser is connected with the reflux tank and the reflux pump to form a loop with the solvent recovery tower.
[0015] The catalytic reaction distillation tower process uses a reaction distillation tower process to catalyze the mixed liquid of methanol and ethanol and separate and obtain high-purity isobutanol.
[0016] The process of using the above device for reactive distillation comprises the following steps:
[0017] First of all, the reaction distillation tower can be divided into three sections, the upper section is the distillation section, the middle reaction distillation section, and the lower section is the stripping section. First, the mixed liquid of methanol and ethanol enters the middle and lower part of the distillation tower through the feed pump; then it contacts the catalyst and undergoes a catalytic reaction in the reaction distillation section of the distillation tower; then, as the mixed gas rises through the distillation section of the tower, the light components in the vapor phase are continuously refined, and the concentration in the vapor phase continues to increase. The steam drawn from the top of the tower is condensed through the condenser, and a part of the condensate is returned to the distillation tower from the top of the tower as reflux liquid, and the remaining distillate is used as the top product of the tower. Then in the stripping section, as the liquid phase descends, its light components are continuously stripped from the liquid phase, so that the heavy components are continuously concentrated in the liquid phase. After that, the liquid drawn from the bottom of the tower is partially vaporized through the reboiler, and the steam rises along the tower, and the remaining liquid is extracted as the bottom product of the tower.
[0018] Secondly, the product obtained from the reactor of the reactive distillation tower is a mixture of water and isobutanol. To obtain high-purity isobutanol, an extractive distillation process is required, which can preferentially remove most of the water, greatly reducing the processing volume of the subsequent separation process, which can reduce the equipment load and reduce the energy consumption of the equipment. The mixture enters the extractive distillation tower, and water is obtained at the top of the tower under the action of the extractant, and a mixture of isobutanol and the extractant is obtained at the bottom of the tower. Then a recovery tower is used to separate the mixture. High-purity isobutanol is obtained at the top of the tower, and the bottom of the tower is an extractant with a purity of 99.99%. During the production process, the extractant loss is less, and it can be recycled, greatly reducing the production cost.
[0019] Compared with the prior art, the present invention has the following beneficial effects:
[0020] (1) The reactive distillation production process and device for preparing isobutanol described in the present invention use a system consisting of a reactive distillation tower, which has the advantages of high reaction conversion rate and high selectivity for isobutanol.
[0021] (2) The process and flow of the present invention are flexible to operate, easy to control, and have low energy consumption and equipment investment costs. BRIEF DESCRIPTION OF THE DRAWINGS
[0022] Figure 1The present invention provides a process flow diagram of a reactive distillation production process and device for preparing isobutanol.
[0023] In the figure, 1, 4, 5, 7, 10, 11, 13, 16, 17, 19 are centrifugal pumps, A is a reactive distillation tower, B is an extractive distillation tower, C is a solvent recovery tower, 2, 8, 14 are condensers, 3, 9, 15 are reflux tanks, 6, 12, 18 are reboilers. a is a catalyst, b is a feed mixture of methanol and ethanol, f is an extractant feed, c, g, j are tower top reflux liquid, d, h, k are tower top products, and e, i, l are tower bottom products. (1) is a distillation section, (2) is a reactive distillation section, and (3) is a stripping section. DETAILED DESCRIPTION
[0024] The reactive distillation production process and device for preparing isobutanol described in the present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the scope of the present invention is not limited thereto.
[0025] Example 1
[0026] As shown in the figure, the reaction distillation tower A carries out the catalytic reaction of methanol and ethanol to obtain isobutanol, and a catalyst (e.g., ruthenium Ru) is added to promote the reaction. The operating pressure of the reaction distillation tower A is set to 1atm, the theoretical plate number is 45, and the reflux ratio is 0.5-8. The mixture mainly composed of methanol and ethanol enters the reaction distillation tower A from the lower part of the tower, the feed flow rate is 100koml / h, and the feed ratio is 3:1. Under steady-state operation, the reaction distillation section has been loaded with catalyst, the reaction starting plate is 8, the ending plate is 18, and the reaction residence time is 1-5min. The top vapor phase enters the reflux tank 3 after being condensed by the top condenser 2, and the reflux liquid of 115.81kmol / h is sent to the reaction distillation tower A by pump 4, and 32.96kmol / h of the top product d is extracted by pump 5. 90.99 kmol / h of the bottom liquid is reboiled in the reboiler 6 and then returned to the reactive distillation tower A, and 67.04 kmol / H of a mixture of water and isobutanol is produced by the bottom pump 7. Under this process condition, the heat loads of the condenser 2 and the reboiler 6 are -1290.51 KW and 507.99 KW respectively.
[0027] The mixture of water and isobutanol and the extractant 1,4-butanediol enter the extractive distillation tower B. The operating pressure of the extractive distillation tower B is set to 1atm, the theoretical plate number is 23, and the reflux ratio is 0.3-3. The mixture of water and isobutanol enters the extractive distillation tower B from the lower part of the tower, and the feed flow rate is 67.04koml / h. The extractant enters the tower at the upper part of the tower, and the feed flow rate is 81koml / h. The top vapor phase enters the reflux tank 9 after condensation by the top condenser 8, and the reflux liquid of 35.22kmol / h is sent to the extractive distillation tower B by pump 10, and the top product h of 44.32kmol / h is produced by pump 11. The 228.16kmol / h tower bottom liquid is reboiled by the reboiler 12 and returned to the extractive distillation tower B, and the 103.72kmol / h mixture of isobutanol and 1,4-butanediol is produced by the tower bottom pump 13. Under this process condition, the heat loads of the condenser 8 and the reboiler 12 are -909.34KW and 1857.60KW respectively.
[0028] The mixture of isobutanol and 1,4-butanediol enters the solvent recovery tower C, the operating pressure of the solvent recovery tower C is set to 1atm, the theoretical plate number is 10, and the reflux ratio is 0.1-3. The mixture of isobutanol and 1,4-butanediol enters the solvent recovery tower C from the upper position of the tower, and the feed flow rate is 103.72koml / h. The top vapor phase enters the reflux tank 15 after condensation by the top condenser 14, and the 2.04kmol / h reflux liquid is sent to the solvent recovery tower C by the pump 16, and 22.73kmol / h of isobutanol with a purity of 0.997 is extracted by the pump 17. The 184.42kmol / h tower bottom liquid is returned to the solvent recovery tower C after reboiled by the reboiler 18, and 80.99kmol / h of 1,4-butanediol with a purity of 99.99% is extracted by the tower bottom pump 19. Under this process condition, the heat loads of the condenser 14 and the reboiler 18 are -345.06KW and 1661.58KW respectively.
[0029] The extractant 1,4-butanediol produced by the solvent recovery tower C can enter the extractive distillation tower B for recycling, and the extractant 1,4-butanediol supplement liquid required is 0.01 kmol / h.
[0030] As shown in the figure, the device includes a reactive distillation tower, an extractive distillation tower, a solvent recovery tower, a raw material feed pump, three top condensers, three reflux tanks, three kettle reboilers, three reflux pumps, three top product pumps, and three bottom product pumps.
[0031] Example 2
[0032] As shown in the figure, the reaction distillation tower A carries out the catalytic reaction of methanol and ethanol to obtain isobutanol, and a catalyst (e.g. iridium Ir) is added to promote the reaction. The operating pressure of the reaction distillation tower A is set to 1atm, the theoretical plate number is 45, and the reflux ratio is 0.5-8. The mixture mainly composed of methanol and ethanol enters the reaction distillation tower A from the lower part of the tower, the feed flow rate is 125koml / h, and the feed ratio is 3:1. Under steady-state operation, the reaction distillation section has been loaded with catalyst, the reaction starting plate is 8, the ending plate is 18, and the reaction residence time is 1-5min. The top vapor phase enters the reflux tank 3 after condensation by the top condenser 2, and the 162.68kmol / h reflux liquid is sent to the reaction distillation tower A by pump 4, and 41.20kmol / h of the top product d is extracted by pump 5. 115.08 kmol / h of the bottom liquid is reboiled in the reboiler 6 and then returned to the reactive distillation tower A, and 83.80 kmol / h of the water and isobutanol mixture is produced by the bottom pump 7. Under this process condition, the heat loads of the condenser 2 and the reboiler 6 are -1536.74 KW and 796.98 KW respectively.
[0033] The water-isobutanol mixture and the extractant ethyl acetate enter the extractive distillation tower. The operating pressure of the extractive distillation tower B is set to 1atm, the theoretical plate number is 23, and the reflux ratio is 0.3-3. The mixture of water and isobutanol enters the extractive distillation tower B from the lower part of the tower, and the feed flow rate is 83.80koml / h. The extractant enters the tower at the upper part of the tower, and the feed flow rate is 81koml / h. The top vapor phase enters the reflux tank 9 after condensation by the top condenser 8, and the 46.53kmol / h reflux liquid is sent to the extractive distillation tower B by pump 10, and 58.71kmol / H of the top product h is produced by pump 11. 254.93kmol / h of the tower bottom liquid is returned to the extractive distillation tower B after reboiled by the reboiler 12, and 106.09kmol / h of the mixture of isobutanol and ethyl acetate is produced by the tower bottom pump 13. Under this process condition, the heat loads of the condenser 8 and the reboiler 12 are -1203.17KW and 2158.17KW respectively.
[0034] The mixture of isobutanol and ethyl acetate enters the solvent recovery tower C, the operating pressure of the solvent recovery tower C is set to 1atm, the theoretical plate number is 10, and the reflux ratio is 0.1-3. The mixture of isobutanol and ethyl acetate enters the solvent recovery tower C from the upper position of the tower, and the feed flow rate is 106.09koml / h. The top vapor phase enters the reflux tank 15 after condensation by the top condenser 14, and the reflux liquid of 2.22kmol / h is sent to the solvent recovery tower C by the pump 16, and 25.11kmol / h of isobutanol with a purity of 0.997 is extracted by the pump 17. 187.36kmol / h of the tower bottom liquid is returned to the solvent recovery tower C after reboiled by the reboiler 18, and 80.98kmol / h of ethyl acetate with a purity of 99.99% is extracted by the tower bottom pump 19. Under this process condition, the heat loads of condenser 17 and reboiler 18 are -377.73KW and 1708.70KW respectively.
[0035] The extractant ethyl acetate produced by the solvent recovery tower C can enter the extractive distillation tower B for recycling, and the extractant ethyl acetate replenishing liquid required is 0.02 kmol / h.
[0036] As shown in the figure, the device includes a reactive distillation tower, an extractive distillation tower, a solvent recovery tower, a raw material feed pump, three top condensers, three reflux tanks, three kettle reboilers, three reflux pumps, three top product pumps, and three bottom product pumps.
[0037] Those skilled in the art should understand that the process flow of the present invention can be used to effectively separate a mixture to obtain a desired product with high purity, and is also applicable to situations where the components in other mixtures have different volatilities.
[0038] The above is only used to illustrate the technical solution of the present invention, and is not intended to limit the present invention in other forms. Any technician familiar with the profession may use the above disclosed technical content to change or modify it into an equivalent embodiment with equivalent changes. Any modification, equivalent replacement, improvement, etc. made to the technical solution without departing from the purpose and scope of the technical solution shall be included in the protection scope of the present invention.
Claims
1. A reactive distillation production process and device for preparing isobutanol, characterized in that: A mixture of methanol and ethanol is fed into the middle and lower part of the reactive distillation tower, and then contacts with the catalyst to react chemically. After distillation and separation, the light component vapor at the top of the tower is condensed in a condenser and collected in a reflux tank. A part of it flows back to the top of the tower, and the rest is extracted as the top product; a part of the bottom liquid is reboiled in a reboiler and returned to the bottom of the tower, and the other part enters the extractive distillation tower as the bottom product. Under the action of the extractant, water is obtained at the top of the tower, and a mixture of isobutanol and the extractant is obtained in the bottom of the tower. Then, the mixture of isobutanol and the extractant enters the solvent recovery tower, and high-purity isobutanol is obtained at the top of the tower, and the bottom of the tower is a high-purity extractant. The extractant can be recycled and enter the extractive distillation tower. The extractant can be 1,4-butanediol, ethyl acetate, etc.
2. A reactive distillation production process and device for preparing isobutanol according to claim 1, characterized in that: The feed pressure of the stream consisting mainly of a mixture of methanol and ethanol is the same as the pressure at the feed point of the reactive distillation column.
3. A reactive distillation production process and device for preparing isobutanol according to claim 1, characterized in that: The reaction of catalyzing the mixture of methanol and ethanol to prepare isobutanol is carried out in the reaction distillation section of the reaction distillation tower, and high-purity light component methanol is obtained at the top of the tower, and the bottom of the tower is a mixture of heavy component isobutanol and water.
4. A reactive distillation production process and device for preparing isobutanol according to claim 3, characterized in that: The extract from the reactor of the reactive distillation tower enters the extractive distillation tower for separation. The top of the extractive distillation tower mainly obtains light component water, and the reactor obtains a mixture of heavy component isobutanol and an extractant.
5. A reactive distillation production process and device for preparing isobutanol according to claim 4, characterized in that: The bottom stream of the extractive distillation tower is used as the feed stream of the solvent recovery tower. After separation and purification, high-purity isobutanol is obtained at the top of the tower, and high-purity extractant is obtained at the bottom of the tower.
6. A reactive distillation production process and device for preparing isobutanol according to claim 1, characterized in that: The catalyst used in the reaction distillation tower to catalyze the conversion of the methanol-ethanol mixture into isobutanol is a supported solid catalyst.
7. A reactive distillation production process and device for preparing isobutanol according to claim 5, characterized in that: The bottom stream of the solvent recovery tower is circulated into the extractive distillation tower.
8. A reactive distillation production process and device for preparing isobutanol according to claim 6, characterized in that: Another feed stream to the extractive distillation column is the extractant which requires additional supplementation.
9. A reactive distillation production process and device for preparing isobutanol according to claim 1, characterized in that: The devices used mainly include a reactive distillation tower, an extractive distillation tower, and a solvent recovery tower. The tower tops are equipped with condensers and reflux tanks, as well as reflux pumps, tower top product pumps and tower bottom product pumps, raw material feed pumps, and the tower bottom is equipped with a reboiler.