Process method for continuously preparing allyl alcohol from epoxypropane

Abstract

The invention provides a process method for continuously preparing allyl alcohol from epoxypropane, and relates to the technical field of chemical synthesis. According to the process method, a feeding unit, a reaction unit, a catalyst recovery unit, a solvent recovery unit, a catalyst preparation unit, an allyl alcohol refining unit, an acquisition unit and a control unit are included, the purity and flow of a solvent output from the top of a solvent refining tower are acquired and transmitted to the control unit in real time, and according to data of the acquisition unit, the allylic alcohol is obtained. The control unit is used for controlling the feeding flow of auxiliary gas in the feeding unit and the feeding flow of a catalyst supplementing pipe in the catalyst recovery unit; the catalyst and solvent recovery unit and the solvent preparation unit are arranged, and the flow of the auxiliary gas in the feeding unit and the supplement amount of the catalyst are controlled according to the purity and flow of the solvent output by the solvent recovery unit, so that the retention time of the raw material in the reaction unit can be effectively shortened, and the generation of tar byproducts is reduced; the selectivity and stability of the catalyst are remarkably improved, and the loss rate of the solvent is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical synthesis, and in particular to a process for continuously preparing allyl alcohol from propylene oxide. Background Art

[0002] Allyl alcohol, also known as propenyl alcohol, is a colorless, flammable liquid with a strong, pungent odor and tear-inducing properties. Soluble in water, ethanol, ether, petroleum ether, and chloroform, allyl alcohol is an important chemical raw material. Due to the presence of double bonds and hydroxyl groups in its molecular structure, it can participate in a variety of chemical reactions, including oxidation, reduction, esterification, and addition, and can be used to synthesize a wide range of downstream products. Allyl alcohol has extensive applications in agrochemicals, pharmaceuticals, fragrances, and organic synthesis.

[0003] The main industrial production methods for allyl alcohol include hydrolysis of allyl chloride, isomerization of propylene oxide, reduction of acrolein, hydrolysis of allyl acetate (prepared by oxidation of propylene catalyzed by the precious metal Pd), and the glycerol method. Previously, allyl alcohol was synthesized primarily through the hydrolysis of allyl chloride, a process that generates large amounts of chlorine-containing wastewater and liquid. To meet environmental protection and atom economy requirements, the development of low-cost, high-yield, and low-pollution production processes has become an inevitable trend in the future development of the chemical industry. Therefore, a greener and more efficient solution is urgently needed.

[0004] The equation for preparing allyl alcohol by the isomerization process of propylene oxide is as follows:

[0005] Patent US4720598A discloses a gas-phase synthesis and regeneration process with a reaction temperature of 255-260°C. Propylene oxide isomerizes to allyl alcohol under the catalysis of a lithium phosphate catalyst. The gas-phase process uses a fixed-bed reactor. This process has the advantages of a short process flow and a high yield of allyl alcohol. However, the catalyst loses activity by 50% after 30 hours of use, indicating extremely rapid deactivation. In addition, the process requires frequent switching and regeneration, resulting in low production efficiency and failure to meet the requirements of industrial production.

[0006] Patent CN107537526A discloses a fluidized bed isomerization catalyst, its preparation method, and application. The fluidized bed reactor in this method has the advantages of high gas-solid mass transfer efficiency, fast reaction rate, and no solvent loss. However, the catalyst still deactivates rapidly in this isomerization process, and the fixed fluidized bed process cannot achieve a catalyst recycling process. In addition, due to severe backmixing in the fixed fluidized bed reactor, the selectivity of allyl alcohol and the conversion rate of propylene oxide are affected, which is not conducive to further industrial scale-up. Therefore, this method has not yet been used in the epoxide isomerization process.

[0007] Patent US3238264A discloses an isomerization method and catalyst. The isomerization method is a slurry method for preparing allyl alcohol. A powdered lithium phosphate catalyst is used and the catalyst is suspended in a high-boiling point solvent for reaction. During the reaction, part of the suspended deactivated catalyst needs to be continuously extracted and separated to separate the tar attached to the oil layer. This method has the characteristics of continuous addition and withdrawal of the catalyst. However, due to the use of a large amount of high-boiling point solvent, there is solvent loss. In addition, the presence of the high-boiling point solvent causes gas-liquid-solid diffusion to become the rate-determining step, which significantly reduces the reaction activity. This results in problems such as long reaction residence time and many side reactions. Summary of the Invention

[0008] In view of the deficiencies in the prior art, the present invention discloses a process for continuously preparing allyl alcohol from propylene oxide. The process has high conversion rate and long catalyst service life, can significantly reduce the occurrence of side reactions and achieve effective solvent recovery, and is suitable for continuous industrial preparation of allyl alcohol.

[0009] In order to achieve the above technical objectives, the present invention provides a process for continuously preparing allyl alcohol from propylene oxide, the process comprising: Feeding unit: used to preheat propylene oxide and mix propylene oxide with auxiliary gas and then feed it into the subsequent reaction unit for reaction; Reaction unit: used for isomerization of propylene oxide to prepare allyl alcohol; the reaction unit includes a suspended bed reactor; Catalyst recovery unit: used to separate the catalyst from the reaction liquid output from the reaction unit and regenerate the catalyst; Solvent recovery unit: used for refining the solvent separated from the reaction liquid output from the reaction unit; the solvent recovery unit includes a solvent refining tower; Catalyst configuration unit: used to configure catalyst using the regenerated catalyst output from the catalyst recovery unit and the solvent output from the solvent recovery unit to obtain a catalyst solution, and the catalyst solution is transported to the reaction unit; the catalyst configuration unit is connected to a catalyst replenishing pipe; Allyl alcohol refining unit: used to separate and recover propylene oxide from the gaseous material output from the reaction unit, and purify it to obtain a high-purity allyl alcohol product; Collection unit: used to collect the purity and flow rate of the solvent output from the top of the solvent refining tower and transmit it to the control unit in real time; Control unit: used to control the feed flow of the auxiliary gas in the feed unit and the feed flow of the catalyst replenishing pipe in the catalyst recovery unit according to the data of the acquisition unit.

[0010] In the above technical solution, the feeding unit can preheat the input propylene oxide and regulate the concentration, rate, etc. of the feed, thereby optimizing the reaction residence time in the subsequent reaction unit and improving the reaction efficiency; further, the catalyst recovery unit and the solvent recovery unit are used to efficiently separate and recover the catalyst and solvent in the reaction materials. These materials will be configured in the catalyst configuration unit to obtain a catalyst solution of appropriate concentration and returned to the reaction unit to continue catalyzing the isomerization reaction of propylene oxide, thereby recycling the catalyst and solvent to achieve economic and environmental benefits.

[0011] In the above technical solution, a solvent refining unit is used to recover the solvent from the post-reaction material. The solvent refining tower used can refine the recovered solvent to a specific purity (e.g., above 98%). The solvent recovery flow rate within this purity range is related to the reaction residence time in the reaction unit and, further, the amount of by-products generated. In the above technical solution, the auxiliary gas feed flow rate in the feed unit is regulated based on the purity and flow rate of the solvent output from the top of the solvent refining tower, thereby regulating the feed rate of the reaction materials, thereby reducing the residence time of the raw materials in the reaction unit and reducing the generation of tar-like by-products. In addition, the solvent recovery flow rate within this purity range is related to the amount of by-products generated. If the above technical solution is provided with a method for removing by-products from the post-reaction material, it may result in the loss of solvent and catalyst. Therefore, by controlling the feed flow rate of the catalyst replenishment pipe in the catalyst recovery unit based on the purity and flow rate of the solvent output from the top of the solvent refining tower, it is possible to promote the provision of an appropriate amount of catalyst for the continuous isomerization of propylene oxide and improve the reaction efficiency.

[0012] In a further example of the present invention, the bottom of the solvent refining tower is connected to a heavy component discharge pipe; the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than a threshold value p1; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1, reducing the flow rate of the solvent output from the top of the solvent refining tower to a threshold value q0; if at this time the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1, maintaining the flow rate of the auxiliary gas in the feeding unit; if at this time the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1, increasing the flow rate of the auxiliary gas in the feeding unit to a threshold value t0; when the flow rate of the auxiliary gas in the feeding unit is t0, if at this time the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1, maintaining the heavy component discharge pipe in a closed state; if at this time the purity of the solvent output from the top of the solvent refining tower is still equal to or less than the threshold value p1, discharging the heavy component from the heavy component discharge pipe until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1. In the above technical solution, by extracting a solvent with a purity greater than the threshold value p1, it is beneficial for the isomerization reaction to proceed efficiently during subsequent recycling; when its purity is equal to or less than the threshold value p1, the extraction amount can be reduced to promote further separation and purification so that the purity meets the set requirements. When the flow rate of the solvent output from the top of the solvent refining tower is reduced to the threshold value q0, it is judged whether the purity of the solvent output from the top of the solvent refining tower has met the set requirements. If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1 at this time, it indicates that the recovery rate of the catalyst in the reaction liquid is high, further reflecting that the reaction efficiency in the reaction unit is high and the reaction residence time is short, thereby reducing the generation of by-products (such as tar). Therefore, the flow rate of the auxiliary gas in the feeding unit can be controlled to maintain; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1 at this time, it indicates that more side reactions have occurred, thereby reducing the recovery rate of the solvent in the solvent recovery unit. At this time, by increasing the flow rate of the auxiliary gas in the feeding unit to t0, the rate of raw material input into the reaction unit can be increased, thereby effectively shortening the reaction residence time. The occurrence of side reactions is reduced, so that the purity of the solvent output from the top of the solvent refining tower is improved. The control method is easy to operate, has a fast response and high efficiency. It can be understood that increasing the flow rate of the auxiliary gas in the feeding unit will affect the effective feed amount of the reaction raw materials. Therefore, the flow rate of the auxiliary gas cannot be increased indefinitely. If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1 at this time, the heavy component discharge pipe is maintained in a closed state. If the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1 at this time, it reflects that increasing the flow rate of the auxiliary gas cannot achieve the purpose of further improving the purity of the solvent output from the top of the solvent refining tower. At this time, the heavy component can be discharged from the heavy component discharge pipe, that is, the solvent purity is improved by directly discharging the heavy component impurities, until the purity of the solvent output from the top of the solvent refining tower meets the set requirement and is greater than the threshold value p1.

[0013] In a further example of the present invention, the bottom of the solvent refining tower is connected to a heavy component discharge pipe; the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than a threshold value p2; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2, the flow rate of the solvent output from the top of the solvent refining tower is reduced to a threshold value q1; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2 at this time, the heavy component discharge pipe is maintained in a closed state; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2 at this time, the heavy component is discharged from the heavy component discharge pipe until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2. It is understood that the accumulation of heavy component impurities in the solvent refining tower will affect the purity of the produced solvent. In this example, by discharging some of the heavy component impurities, the purity of the solvent produced from the top of the solvent refining tower is improved.

[0014] In a further example of the present invention, the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than a threshold value p3; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3, reducing the flow rate of the solvent output from the top of the solvent refining tower to a threshold value q2; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3 at this time, maintaining the feed flow rate of the catalyst replenishment pipe in the feed unit; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3 at this time, increasing the feed flow rate of the catalyst replenishment pipe in the feed unit until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3. Based on the above technical solution, by extracting a solvent with a purity greater than the threshold value p3, it is beneficial to the efficient isomerization reaction during subsequent recycling; when its purity is equal to or less than the threshold value p3, further separation and purification can be promoted by reducing the extraction amount so that the purity meets the set requirements. In order to reduce the occurrence of side reactions, the feed flow rate of the catalyst replenishment pipe in the feed unit can be regulated by adjusting the flow rate of the solvent output from the top of the solvent refining tower. When the flow rate of the solvent output from the top of the solvent refining tower is reduced to the threshold value q2, the purity of the solvent output from the top of the solvent refining tower is judged. If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3 at this time, the feed flow rate of the catalyst replenishment pipe in the feed unit is maintained; if the purity of the solvent output from the top of the solvent refining tower still does not meet the set requirements and is equal to or less than the threshold value p3 at this time, the feed flow rate of the catalyst replenishment pipe can be increased until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3. That is, by increasing the flow rate of the newly added input catalyst to promote sufficient reaction, thereby improving reaction efficiency, shortening reaction residence time, reducing the generation of by-products, and further improving the purity of the solvent output from the top of the solvent refining tower.

[0015] It should be noted that the above technical solution does not limit the specific device mode of the catalyst regeneration device. It can be selected from a cleaning solvent washing device, a high-temperature roasting device, a high-temperature steam washing device, etc., and technicians in this field can choose according to their needs.

[0016] In a further example of the present invention, the catalyst recovery unit includes a separator and a catalyst regeneration device; the catalyst regeneration device includes a cleaning agent washing device; the process method includes: controlling the flow rate and washing time of the cleaning agent in the cleaning agent washing device according to the data of the acquisition unit; the purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p4; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q3; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4 at this time, maintaining the flow rate and washing time of the cleaning agent in the cleaning agent washing device; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4 at this time, increasing the flow rate and washing time of the cleaning agent in the cleaning agent washing device until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4. Based on the above technical solution, extracting solvent with a purity greater than the threshold p4 facilitates efficient isomerization during subsequent recycling. When the purity is equal to or less than the threshold p4, the extraction volume can be reduced to facilitate further separation and purification to meet the required purity. The catalyst regeneration device can regenerate deactivated catalysts after the reaction. In practice, the cleaning agent flow rate and washing time (i.e., the contact time between the cleaning agent and the washed catalyst) can be controlled to successfully activate the catalyst. Based on the above technical solution, when the flow rate of the solvent output from the top of the solvent refining tower is reduced to the threshold value q3, a judgment is made based on the purity of the solvent output from the top of the solvent refining tower. If the purity at this time has met the set requirements, the flow rate and washing time of the cleaning agent in the cleaning agent washing device are maintained; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4 at this time, reflecting an increase in tar by-products, the adverse effects of the by-products on the solvent recovery unit can be reduced by regulating the regeneration and activation operation of the catalyst in the catalyst recovery unit; specifically, the tar by-products can be removed by increasing the flow rate of the cleaning agent and the washing time, thereby achieving the purpose of increasing the flow rate of the solvent output from the top of the solvent refining tower.

[0017] Based on the above technical solution, in addition to regulating the reaction efficiency or reaction residence time of the reaction unit, the conversion rate of the raw material propylene oxide is also an effect parameter that needs to be considered.

[0018] In a further example of the present invention, the allyl alcohol refining unit includes a propylene oxide recovery tower and an allyl alcohol refining tower; the process method includes: collecting the purity and flow rate of the propylene oxide output from the propylene oxide recovery tower and transmitting it to the control unit in real time, and controlling the feed flow rate of the auxiliary gas in the feeding unit according to the collected purity and flow rate data of the propylene oxide output from the propylene oxide recovery tower. In the above technical solution, unreacted propylene oxide is collected after distillation through a propylene oxide recovery tower connected to the reaction unit; it is understandable that the purity of the propylene oxide output from the propylene oxide recovery tower can be achieved by controlling the parameters of the propylene oxide recovery tower, and the flow rate of propylene oxide will be directly related to the conversion rate of the raw material in the reaction unit; specifically, a relatively large flow rate of propylene oxide output from the propylene oxide recovery tower indicates that the raw material conversion rate in the reaction unit is relatively low, and vice versa, it indicates that the raw material conversion rate is relatively high; and the feed flow rate of the raw material propylene oxide can be regulated by the input flow rate of the auxiliary gas. When the flow rate of the auxiliary gas increases too much, the residence time of the raw material will be too low, resulting in a decrease in conversion efficiency. Therefore, the feed flow rate of the auxiliary gas in the feeding unit can be controlled according to the purity and flow rate of the propylene oxide output from the propylene oxide recovery tower to improve the raw material conversion rate.

[0019] In a further example of the present invention, the bottom of the propylene oxide recovery tower is connected to a light component discharge pipe; the purity of the propylene oxide output from the propylene oxide recovery tower should be greater than a threshold value x1; when the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x1, the flow rate of the propylene oxide output from the propylene oxide recovery tower is reduced to a threshold value g0; if the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1 at this time, the flow rate of the auxiliary gas in the feeding unit is maintained ... If the purity of propane is equal to or less than the threshold value x1, the flow rate of the auxiliary gas in the feeding unit is reduced to the threshold value f0; when the flow rate of the auxiliary gas in the feeding unit is f0, if the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1 at this time, the light component discharge pipe is maintained in a closed state; if the purity of the propylene oxide output from the propylene oxide recovery tower is still equal to or less than the threshold value x1 at this time, the light component is discharged from the light component discharge pipe until the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1. Specifically, when the flow rate of propylene oxide output from the propylene oxide recovery tower is reduced to g0, a judgment is made based on the purity of the propylene oxide output from the propylene oxide recovery tower. If the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1 at this time, the flow rate of the auxiliary gas in the feeding unit is maintained; if the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x1 at this time, it reflects that the conversion rate of the raw material propylene oxide is low, which is not conducive to sufficient mass transfer reaction. Therefore, by slowly reducing the flow rate of the auxiliary gas in the feeding unit, the amount of light component impurities carried to the propylene oxide recovery tower can be reduced by reducing the flow rate of the auxiliary gas in the feeding unit, thereby promoting the improvement of the propylene oxide output from the propylene oxide recovery tower. The purity of propylene oxide is controlled by the light component discharge pipe. The control method is simple to operate and has high efficiency. It is understandable that increasing the flow rate of the auxiliary gas in the feeding unit may affect the effective feeding of the reaction raw materials. Therefore, the flow rate of the auxiliary gas cannot be increased indefinitely. If the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1 at this time, the light component discharge pipe is maintained in a closed state. If the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x1 at this time, the light component can be discharged from the light component discharge pipe, that is, the purity of the propylene oxide output from the propylene oxide recovery tower is improved by directly discharging the light component impurities from the propylene oxide recovery tower, until the purity of the propylene oxide output from the propylene oxide recovery tower meets the set requirements.

[0020] In a further example of the present invention, the bottom of the propylene oxide recovery tower is connected to a light component discharge pipe; the process method includes: the purity of the propylene oxide output from the propylene oxide recovery tower should be greater than a threshold value x2; when the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x2, reducing the flow rate of the propylene oxide output from the propylene oxide recovery tower to a threshold value g1; if at this time the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x2, maintaining the light component discharge pipe in a closed state; if at this time the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x2, discharging the light component from the light component discharge pipe until the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x2. Specifically, in actual operation, in order to improve the purity of the propylene oxide output from the propylene oxide recovery tower, the flow rate of the propylene oxide output from the propylene oxide recovery tower is reduced to the threshold value g1. If the purity still does not meet the set requirements at this time, it is optional to discharge light component impurities (heavier than propylene oxide) from the bottom of the propylene oxide recovery tower to improve the purity of the propylene oxide output from the propylene oxide recovery tower.

[0021] In a further example of the present invention, the catalyst configuration unit is connected to a solvent replenishment pipe; the process method includes: collecting the liquid level within the suspended bed reactor and transmitting it to a control unit in real time; and opening or closing the solvent replenishment pipe based on the collected liquid level data within the suspended bed reactor. It is understood that in actual process, a reaction system of appropriate size can be set based on the required reaction volume. During the process operation, some of the solvent used will be discharged or inevitably lost. Optionally, a liquid level monitoring device can be installed on the reactor to adjust the solvent replenishment pipe to replenish new solvent, thereby maintaining stable operation of the reaction system.

[0022] In a further example of the present invention, the process includes collecting the solids content within the suspended bed reactor and transmitting it to a control unit in real time, and opening or closing the catalyst replenishment tube based on the collected solids content data within the suspended bed reactor. This application utilizes a suspended bed reactor for the isomerization of propylene oxide to produce allyl alcohol. During the reaction, the reaction system is uniformly mixed. The solids content reflects the effective content of the catalyst (solid-phase catalyst). In actual operation, the solids content within the reactor can be sampled and tested, and the catalyst replenishment tube can be opened and closed based on the solids content to maintain the catalyst dosage within the reaction system within a specific range.

[0023] In a further embodiment of the present invention, the feed unit is equipped with temperature, pressure, and flow control components for preheating and pressurizing fresh propylene oxide before feeding it into the reaction unit. The fresh propylene oxide is the propylene oxide raw material newly fed into the reaction process of the present invention. In an alternative embodiment of the present invention, the preheating temperature of the propylene oxide in the feed unit is optionally 150-300°C, preferably 200-230°C; and the pressure of the feed unit can be optionally 0.1-2.0 mPa, preferably 0.2-1.0 mPa.

[0024] Compared with the prior art, the present invention has the following beneficial effects: the process method for continuously preparing allyl alcohol from propylene oxide of the present invention is provided with a catalyst and solvent recovery and configuration unit, and the flow rate of the auxiliary gas and the amount of catalyst replenished in the feeding unit are controlled according to the purity and flow rate of the solvent output by the solvent recovery unit, thereby effectively reducing the residence time of the raw materials in the reaction unit, thereby reducing the generation of tar by-products, significantly improving the selectivity and stability of the catalyst, and reducing the loss rate of the solvent.

[0025] The reaction residence time of the continuous preparation of allyl alcohol from propylene oxide is less than 10 seconds, thereby reducing side reactions and coking. The total yield of allyl alcohol prepared by isomerization is greater than 55%, the allyl alcohol selectivity is greater than 95%, and the catalyst and solvent replenishment amounts are both less than 0.05% / h. The allyl alcohol product with a purity greater than 99.0% is obtained by combining the two-stage distillation of the allyl alcohol refining unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The accompanying drawings, which constitute part of this application, are intended to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are intended to explain the present invention and do not constitute an undue limitation of the present invention. In the accompanying drawings: Figure 1 A structural diagram showing the process for continuously preparing allyl alcohol from propylene oxide according to the present invention.

[0027] The above drawings include the following reference numerals: 1-feeding unit, 11-propylene oxide inlet pipe, 12-auxiliary gas inlet pipe, 2-reaction unit, 31-separator, 32-catalyst regeneration device, 4-solvent recovery unit, 41-first online collection device, 42-solvent refining tower top output pipeline, 43-heavy component discharge pipe, 5-catalyst configuration unit, 51-solvent replenishing pipe, 52-catalyst replenishing pipe, 61-propylene oxide recovery tower, 611-second online collection device, 612-propylene oxide recovery tower top output pipeline, 613-light component discharge pipe, 62-allyl alcohol refining tower, 71-first switch valve, 72-second switch valve, 73-third switch valve, 74-fourth switch valve, 75-fifth switch valve, 76-sixth switch valve. DETAILED DESCRIPTION

[0028] To facilitate understanding of the present invention, the present invention will be described in more detail below, with preferred embodiments of the present invention provided. However, it should be understood that these embodiments are merely for the purpose of further explanation and are not to be construed as limiting the present invention in any form, i.e., they are not intended to limit the scope of protection of the present invention.

[0029] Unless otherwise defined, the technical terms used in the following examples have the same meanings as commonly understood by those skilled in the art to which the present invention pertains. The experimental reagents used in the following examples, unless otherwise specified, are conventional biochemical reagents; and the experimental methods, unless otherwise specified, are conventional methods.

[0030] Example 1 A process for continuously preparing allyl alcohol from propylene oxide, combined with Figure 1 , the method comprising: Feeding unit 1: used to preheat propylene oxide and mix propylene oxide with auxiliary gas and then feed it into the subsequent reaction unit 2 for reaction; Reaction unit 2: for isomerization of propylene oxide to produce allyl alcohol; reaction unit 2 includes a suspended bed reactor; Catalyst recovery unit: used to separate the catalyst from the reaction liquid output from the reaction unit 2 and regenerate the catalyst; Solvent recovery unit 4: used to purify the solvent separated from the reaction liquid output from reaction unit 2; solvent recovery unit 4 includes a solvent refining tower; Catalyst configuration unit 5: used to configure catalyst using the regenerated catalyst output from the catalyst recovery unit and the solvent output from the solvent recovery unit 4 to obtain a catalyst solution, which is then transported to the reaction unit 2; the catalyst configuration unit 5 is connected to the catalyst replenishment pipe 52; Allyl alcohol refining unit: used to separate and recover propylene oxide from the gaseous material output from reaction unit 2, and purify it to obtain high-purity allyl alcohol product; Collection unit: used to collect the purity and flow of the solvent output from the top of the solvent refining tower and transmit it to the control unit in real time; Control unit: Based on the data of the acquisition unit, it controls the feed flow of the auxiliary gas in the feed unit 1 and the feed flow of the catalyst replenishing pipe 52 in the catalyst recovery unit.

[0031] Optionally, the feeding unit 1 includes a propylene oxide preheater, a mixing device and a gas distributor. The material mixed by the gas phase mixer is quickly pumped into the bottom of the liquid phase material in the reactor through the gas distributor to fully transfer the reaction.

[0032] Optionally, the preheating temperature of propylene oxide in the feeding unit 1 is 150-300°C, preferably 200-230°C.

[0033] Optionally, the molar ratio of the auxiliary gas to propylene oxide in the feeding unit 1 is 0.1-10, preferably 1-5; the pressure of the feeding unit 1 can be selected to be 0.1-2.0 mPa, preferably 0.2-1.0 mPa.

[0034] Optionally, auxiliary gas is used to mix with propylene oxide to facilitate regulation of the feed rate, temperature and pressure of the reaction raw materials. It can be an inert gas such as nitrogen, argon, helium, etc., and can be selected according to needs in actual use.

[0035] It should be noted that the present invention is not limited to the specific structure of the mixing device, and any device that can be used to mix propylene oxide and auxiliary gas is sufficient; the present invention is not limited to the specific structure of the gas distributor, and common aeration equipment such as annular or tubular aeration pipes can be selected as the gas distributor that can quickly and evenly pump the gas into the bottom of the reactor.

[0036] Optionally, the suspended bed reactor includes a reaction section and a distillation section; wherein the reaction section is the lower part of the reactor and the distillation section is the upper part of the reactor, so that the reaction liquid containing the solvent and the catalyst is output from the lower part of the reaction unit 2, and the gaseous material containing allyl alcohol and unreacted propylene oxide is output from the upper part of the reaction unit 2. Further optionally, the aspect ratio of the reaction section is 1 to 10, preferably 4 to 6, and the position of the reaction liquid level is regulated by optimizing the aspect ratio, thereby regulating the residence time of the isomerization reaction; the top distillation section is a common distillation tower structure, which can be a packed tower, a plate tower, etc. Further optionally, the suspended bed reactor includes an agitator for increasing the mixed mass transfer of the gas, liquid, and solid phases and improving the reaction efficiency; the agitator can be selected as a top stirring or bottom stirring type, preferably a bottom stirring type.

[0037] Optionally, the suspended bed reactor is equipped with a heating device to provide suitable temperature conditions for propylene oxide isomerization. Furthermore, the heating device can be heated by thermal oil or an electric furnace. Furthermore, the heating temperature of the heating device is preferably 250-310°C, preferably 270-300°C.

[0038] Optionally, the reaction temperature of the reaction unit 2 is 250-310° C., preferably 270-300° C.; the reaction pressure is -0.05-1 MPa, preferably -0.01-0.5 MPa; and the reaction residence time is 0.2-20 s, preferably 1-4 s.

[0039] It should be noted that the catalyst used in the propylene oxide isomerization of the present invention can be a common modified lithium phosphate catalyst or a carrier-supported lithium phosphate powder catalyst. Optionally, the mass ratio of the epoxide feed to the catalyst is 0.5 to 10, preferably 1 to 5.

[0040] Separator 31 is used to separate the reaction liquid output from reaction unit 2 into solids and liquids; optionally, separator 31 can be one or more of a centrifuge, a filter, and a settler. The catalyst recovery unit of the present invention can achieve a solids content of less than 0.5% in the separated reaction solvent, thereby preventing fine powder generated by catalyst wear during use from being carried over into the solvent recovery tower.

[0041] The catalyst regeneration device 32 is used to regenerate the catalyst that has been deactivated after the reaction. Optionally, the catalyst regeneration device 32 can be a cleaning solvent washing device, a high-temperature roasting device, a high-temperature steam washing device, etc., preferably a cleaning agent washing device. Furthermore, the cleaning agent can be at least one of common solvents such as water, ketones, alcohols, and ethers, preferably at least one of acetone and ethanol. Furthermore, the amount of cleaning agent used can be 2 to 10 times the mass of the catalyst, preferably 3 to 5 times; the cleaning temperature can be 20 to 150°C, preferably 20 to 80°C; and the cleaning time can be 0.4 to 6 hours, preferably 1 to 4 hours.

[0042] Optionally, the catalyst regeneration device 32 is connected to a discharge pipe. To extend and maintain the service life of the catalyst during the continuous preparation process, partially deactivated catalyst is periodically discharged from the catalyst regeneration device 32 according to the reaction conditions, and fresh catalyst is replenished into the catalyst configuration unit 5 through the catalyst replenishment pipe 52. Further optionally, the replenishment rate of the newly replenished catalyst is 0.002 to 0.5% / h of the initial catalyst feed amount, preferably 0.005 to 0.05% / h.

[0043] Optionally, the purity of the solvent output from the solvent refining tower is greater than 97%; further optionally, the bottom of the solvent refining tower will regularly discharge a portion of heavy oil containing heavy component impurities according to the impurity situation.

[0044] It should be noted that the present invention does not limit the type of solvent, and can be selected from at least one of polar organic solvents with a boiling point greater than 300°C (such as alcohols, ketones, lipids, etc.), non-polar organic solvents (such as hydrocarbon solvents, halogenated hydrocarbon solvents), ionic liquids (such as imidazole ionic liquids) or water. The solvent can be selected according to needs in the actual process.

[0045] The catalyst configuration unit 5 uses the recovered solvent and regenerated catalyst to prepare a catalyst solution, which is then recycled, effectively reducing process costs. Optionally, the catalyst configuration unit 5 is also connected to a solvent replenishment pipe 51, through which fresh solvent is introduced to maintain the catalyst-solvent balance in the catalyst solution entering the reaction unit 2. Furthermore, the fresh solvent replenishment rate is 0.005% to 0.3% / h of the initial solvent feed, preferably 0.01% to 0.03% / h.

[0046] The feed port of the propylene oxide recovery tower 61 is connected to the upper discharge port of the suspended bed reactor. By adjusting the parameters, the unreacted propylene oxide in the gas phase material after the reaction can be separated and extracted, and this part of the material can be returned to the reaction unit 2 for recycling. Optionally, the total content of propylene oxide, acetone and propionaldehyde in the bottom material (crude allyl alcohol) of the propylene oxide recovery tower 61 is less than 1%.

[0047] The feed port of the allyl alcohol refining tower 62 is connected to the bottom discharge port of the propylene oxide recovery tower 61. By adjusting the parameters, the allyl alcohol can be refined, and an allyl alcohol product with a purity greater than 99.0% is extracted from the top of the tower, and heavy impurities are discharged from the bottom of the tower.

[0048] Optionally, the distillation tower used in the present invention (such as the propylene oxide recovery tower 61, the allyl alcohol refining tower 62, the solvent refining tower, etc.) is a plate tower or a packed tower, preferably a packed tower.

[0049] Optionally, the catalyst configuration unit 5 is connected to a solvent replenishing pipe 51 ; the process method includes: opening or closing the solvent replenishing pipe 51 according to the liquid level in the suspension bed reactor.

[0050] Optionally, the catalyst supplement pipe 52 is opened or closed according to the solid content in the suspension bed reactor.

[0051] This example illustrates a process for continuously preparing allyl alcohol from propylene oxide under normal operating conditions. It should be noted that this example is merely a demonstration of the preferred embodiment and does not limit the scope of protection of the present invention. Specifically: The reactor used in this example is a slurry bed reactor with a bottom reaction section of 40 cm in height and 8 cm in diameter. The stirring mode is bottom stirring. The top of the reactor is a distillation section of 20 cm in length and 4 cm in diameter. 120 g of ISO-CAT-1 catalyst is added to the reactor, and 1000 g of a high-boiling-point solvent is added at the same time.

[0052] The specific process involves introducing propylene oxide and nitrogen into feed unit 1 through propylene oxide inlet pipe 11 and auxiliary gas inlet pipe 12. The propylene oxide flow rate is controlled at 5.0 g / min and the nitrogen flow rate is 20 sccm. The mixture is heated to 230°C and the pressure is adjusted to 0.3 MPa before entering the bottom of the slurry bed reactor. The isomerization reactor is maintained at a pressure of 0.2 MPa and a temperature of 280°C, with a contact residence time of 2 seconds. The gaseous discharge from the reactor is fed through a gas phase pipeline to a propylene oxide recovery tower 61. After separation, the overhead propylene oxide is returned to feed unit 1. The crude allyl alcohol discharged from the bottom of the tower is refined in an allyl alcohol refining tower 62 to produce an allyl alcohol product with a purity greater than 99%. The reaction liquid is output from the liquid phase outlet at the bottom of the reactor into the separator 31. After continuous filtration and separation, the liquid phase solvent enters the solvent refining tower for purification. The solid phase catalyst is cleaned and regenerated with the solvent acetone. The mass ratio of acetone to spent catalyst is 2:1. The purified solvent and regenerated catalyst respectively enter the catalyst configuration unit 5. At the same time, some fresh catalyst and solvent are replenished and then return to the reactor to continue the catalytic reaction.

[0053] Gas chromatography was used to qualitatively and quantitatively analyze the reaction substrates and products in the reactor. The results showed a single-pass allyl alcohol conversion rate of 65% to 70%, a 91.5% yield after 24 hours of continuous reaction, and a 90.3% yield after 2,000 hours of continuous reaction.

[0054] Example 2 Based on the process for continuously preparing allyl alcohol from propylene oxide shown in Example 1, this example explores the specific control process of the process for continuously preparing allyl alcohol from propylene oxide when special operating conditions occur.

[0055] Optionally, the bottom of the solvent refining tower is connected to the heavy component discharge pipe 43; the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p1; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q0; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1 at this time, maintaining the flow rate of the auxiliary gas in the feeding unit; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1 at this time, increasing the flow rate of the auxiliary gas in the feeding unit to the threshold value t0; when the flow rate of the auxiliary gas in the feeding unit is t0, if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1 at this time, maintaining the heavy component discharge pipe 43 in a closed state; if the purity of the solvent output from the top of the solvent refining tower is still equal to or less than the threshold value p1 at this time, discharging the heavy component from the heavy component discharge pipe 43 until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1.

[0056] Combine Figure 1The control principle of this embodiment includes: using a first online acquisition device 41 (such as an online gas chromatograph or an online Raman spectrometer, etc.) to detect the purity of the material in the solvent refining tower top output pipeline 42 and transmit it to the control unit in real time; when the control unit determines that the purity of the material in the solvent refining tower top output pipeline 42 is equal to or less than the set threshold value p1, the control unit controls the opening of the first switch valve 71 to slowly decrease, so that the flow rate of the material entering the solvent refining tower top output pipeline 42 gradually decreases to q0; at this time, when the control unit determines that the purity of the material in the solvent refining tower top output pipeline 42 is greater than the set threshold value p1, it controls the opening of the second switch valve 72 on the auxiliary gas input pipe 12 to remain unchanged; when the control unit determines that the purity of the material in the solvent refining tower top output pipeline 42 is greater than the set threshold value p1, the control unit controls the opening of the second switch valve 72 on the auxiliary gas input pipe 12 to remain unchanged. When the control unit determines that the purity of the material in the top output line 42 of the solvent refining tower is still equal to or less than the set threshold value p1, the opening of the second switch valve 72 on the auxiliary gas input pipe 12 is controlled to increase, so that the flow rate of the auxiliary gas in the feeding unit 1 gradually increases to the threshold value t0; at this time, when the control unit determines that the purity of the material in the top output line 42 of the solvent refining tower is greater than the set threshold value p1, the third switch valve 73 on the heavy component discharge pipe 43 is controlled to be closed; when the control unit determines that the purity of the material in the top output line 42 of the solvent refining tower is still equal to or less than the set threshold value p1, the third switch valve 73 on the heavy component discharge pipe 43 is controlled to be slowly opened to discharge the heavy component impurities from the heavy component discharge pipe 43.

[0057] It should be noted that p1 can be selected as any value greater than 97%. It can be understood by those skilled in the art that the purity of the solvent output from the top of the solvent refining tower can be achieved by regulating the control parameters of the refining tower, such as temperature, pressure, reflux ratio, etc. For example, in the actual process, it is optional to set the solvent refining tower top to extract a solvent with a purity greater than 98% for reuse, and detect the purity of the output solvent in the connecting pipeline at the top of the solvent refining tower during operation. When the purity is lower than 98%, the extraction flow rate of the top of the solvent refining tower is controlled and reduced to 6kg / h; if the purity of the solvent output from the top of the solvent refining tower meets the requirement of greater than 98% at this time, the feed flow rate of the auxiliary gas in the feed unit 1 is kept unchanged; if the purity of the solvent output from the top of the solvent refining tower still does not meet the set requirements at this time, it reflects that the isomerization reaction produces a large amount of tar by-products, and such by-products are dissolved in the solvent and enter the solvent refining tower, resulting in an increase in the load of the refining tower and the inability to extract qualified solvents that meet the purity requirements from the top of the tower. At this time, it can be considered to intervene by regulating the process parameters of the reaction unit 2; Specifically, the auxiliary gas feed flow rate in feed unit 1 can be increased to t0 (for example, from 0.5 SLM to 3 SLM) to increase the feedstock feed rate, uniformly inject the feedstock into the reaction system through the feed port injector, reduce the feedstock residence time, and reduce the production of tar-like byproducts, thereby increasing the purity of the solvent output from the top of the solvent refining tower. At this time, if the purity of the solvent output from the top of the solvent refining tower is greater than threshold p1, the heavy component discharge pipe 43 remains closed. If the purity of the solvent output from the top of the solvent refining tower is still equal to or less than threshold p1, indicating that simply increasing the auxiliary gas feed flow rate cannot further improve the purity of the solvent output from the top of the solvent refining tower, the heavy components can be discharged from the heavy component discharge pipe 43 to promote the increase of the purity of the solvent output from the top of the solvent refining tower to greater than p1. Further, after the reaction system reaches equilibrium, the discharge of heavy component impurities can be stopped first, and then the flow rate of the solvent output from the top of the solvent refining tower is increased and / or the flow rate of the auxiliary gas in feed unit 1 is reduced.

[0058] Optionally, the bottom of the solvent refining tower is connected to the heavy component discharge pipe 43; the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p2; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2, the flow rate of the solvent output from the top of the solvent refining tower is reduced to the threshold value q1; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2 at this time, the heavy component discharge pipe 43 is maintained in a closed state; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2 at this time, the heavy component is discharged from the heavy component discharge pipe 43 until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2. Figure 1The control principle of this embodiment includes: using a first online data acquisition device 41 (such as an online gas chromatograph or an online Raman spectrometer) to detect the purity of the material in the solvent refining tower overhead output pipeline 42 and transmit the information to a control unit in real time. When the control unit determines that the purity of the material in the solvent refining tower overhead output pipeline 42 is equal to or less than a set threshold value p2 (such as an arbitrary value greater than 97%), the control unit controls the opening of the first on-off valve 71 to slowly decrease, so that the flow rate of the material entering the solvent refining tower overhead output pipeline 42 gradually decreases to q1 (such as 5 kg / h). At this time, if the control unit determines that the purity of the material in the solvent refining tower overhead output pipeline 42 is greater than the set threshold value p2, the control unit controls the third on-off valve 73 to remain closed. If the control unit determines that the purity of the material in the solvent refining tower overhead output pipeline 42 is equal to or less than the set threshold value p2, the control unit controls the third on-off valve 73 to slowly open, gradually discharging the heavy component from the heavy component discharge pipe 43 until the purity of the solvent output from the solvent refining tower overhead exceeds the threshold value p2. Further optionally, after the reaction system reaches equilibrium, the flow rate of the solvent output from the top of the solvent refining tower can be increased and / or the third switch valve 73 can be controlled to be closed.

[0059] Optionally, the purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p3; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3, the flow rate of the solvent output from the top of the solvent refining tower is reduced to the threshold value q2; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3 at this time, the feed flow rate of the catalyst replenishing pipe 52 in the feed unit is maintained; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3 at this time, the feed flow rate of the catalyst replenishing pipe 52 in the feed unit is increased until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3. Combined Figure 1The control principle of this embodiment includes: using a first online acquisition device 41 (such as an online gas chromatograph or an online Raman spectrometer) to detect the purity of the material in the solvent refining tower top output pipeline 42 and transmit it to the control unit in real time; when the control unit determines that the purity of the material in the solvent refining tower top output pipeline 42 is equal to or less than a set threshold value p3 (such as 98%), the control unit controls the opening of the first switch valve 71 to slowly decrease, so that the flow rate of the material entering the solvent refining tower top output pipeline 42 gradually decreases to q2; at this time, if the control unit determines that the solvent refining tower When the purity of the material in the top output pipeline 42 is greater than the set threshold value p3, the opening of the fourth switch valve 74 on the catalyst replenishment pipe 52 is kept unchanged, so that the flow rate of the newly prepared catalyst input to the catalyst configuration unit 5 remains unchanged; if the control unit determines that the purity of the material in the top output pipeline 42 of the solvent refining tower is equal to or lower than the set threshold value p3, the opening of the fourth switch valve 74 on the auxiliary gas input pipe 12 is controlled to slowly increase, so that the flow rate of the newly prepared catalyst input to the catalyst configuration unit 5 gradually increases until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3. In actual processes, if the solvent refining tower overhead extraction rate is reduced to 6.5 kg / h and the solvent purity output from the solvent refining tower still does not meet the set requirements, confirming that the isomerization reaction produces a certain amount of tar-like byproducts, it is possible to consider adjusting the process parameters of catalyst configuration unit 5. Specifically, to compensate for possible catalyst loss, the flow rate in catalyst replenishment pipe 52 can be increased to 0.05% / h until the purity of the solvent refining tower overhead extraction rate exceeds threshold value p3. Furthermore, after the reaction system reaches equilibrium, the solvent refining tower overhead extraction rate can be increased and / or the feed rate in catalyst replenishment pipe 52 can be reduced.

[0060] Optionally, the catalyst recovery unit includes a separator 31 and a catalyst regeneration device 32; the catalyst regeneration device 32 includes a cleaning agent washing device; the process method includes: controlling the flow rate and washing time of the cleaning agent in the cleaning agent washing device according to the data of the acquisition unit; the purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p4; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q3; if the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4 at this time, maintaining the flow rate and washing time of the cleaning agent in the cleaning agent washing device; if the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4 at this time, increasing the flow rate and washing time of the cleaning agent in the cleaning agent washing device until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4. Combined Figure 1The control principle of this embodiment includes: using a first online acquisition device 41 (such as an online gas chromatograph or an online Raman spectrometer, etc.) to detect the purity of the material in the solvent refining tower top output pipeline 42 and transmit it to the control unit in real time; when the control unit determines that the purity of the material in the solvent refining tower top output pipeline 42 is equal to or less than a set threshold value p4 (such as an arbitrary value greater than 97%), the control unit controls the opening of the first switch valve 71 to slowly decrease, so that the flow rate of the material entering the solvent refining tower top output pipeline 42 gradually decreases to a threshold value q3 (such as 6.25 kg / h); at this time, the control unit determines whether the purity of the material in the solvent refining tower top output pipeline 42 meets the set requirements; if the purity of the material in the solvent refining tower top output pipeline 42 meets the set requirements, the control unit controls the first switch valve 71 to slowly decrease the opening of the first switch valve 71 ... in the solvent refining tower top output pipeline 42 meets the set requirements, the control unit controls the first switch valve 71 to slowly decrease the opening of the first switch valve 71, so that the flow rate of the material in the solvent refining tower top output pipeline 42 meets the set requirements, the control unit controls the first switch valve 71 to slowly decrease the opening of the first switch valve 71, If the purity of the material in the output line 42 from the top of the solvent refining tower is greater than the set threshold value p4, the control unit controls the opening of the on-off valve on the cleaning agent input pipe connected to the cleaning agent washing device to maintain the opening (for the purpose of simplicity, the cleaning agent washing device and the cleaning agent input pipe are not shown in the figure), so that the flow rate of the cleaning agent input to the cleaning agent washing device remains unchanged and the washing time in which the catalyst and the cleaning agent are in contact remains unchanged; if the control unit determines at this time that the purity of the material in the output line 42 from the top of the solvent refining tower is still equal to or lower than the set threshold value p4, the control unit controls the opening of the on-off valve on the cleaning agent input pipe connected to the cleaning agent washing device to slowly increase, so that the flow rate of the cleaning agent input to the cleaning agent washing device gradually increases, and at the same time controls the catalyst washing time to increase. In the actual process, as shown above, when the solvent refining tower overhead extraction flow rate is less than 6.25kg / h, it is confirmed that the isomerization reaction produces a certain amount of tar-like byproducts. At this time, it is possible to consider adjusting and intervening in the process parameters of the catalyst recovery unit; specifically, to eliminate the impact of the tar byproduct on the catalyst regeneration effect, the amount of cleaning agent in the catalyst regeneration system can be increased to 3 times the amount of catalyst to be cleaned and the washing time can be increased to 2h to improve the purity of the solvent output from the solvent refining tower overhead until it meets the set requirements. Further, after the reaction system reaches equilibrium, the flow rate of the solvent output from the solvent refining tower overhead can be increased and / or the flow rate and washing time of the cleaning agent in the cleaning agent washing device can be reduced.

[0061] It can be understood that p1, p2, p3, p4, q0, q1, q2, q3, t0, etc. independently represent a specific numerical value as a threshold, and as long as they do not exceed the basic principles limited by the present invention, they all fall within the scope of protection of the present invention.

[0062] Example 3 Based on the process for continuously preparing allyl alcohol from propylene oxide shown in Example 1 or Example 2, the specific process method in the process is optimized in this example.

[0063] Optionally, the allyl alcohol refining unit includes a propylene oxide recovery tower 61 and an allyl alcohol refining tower 62; the process method includes: collecting the purity and flow rate of propylene oxide output from the propylene oxide recovery tower 61 and transmitting it to the control unit in real time, and controlling the feed flow rate of the auxiliary gas in the feeding unit 1 according to the collected purity and flow rate data of the propylene oxide output from the propylene oxide recovery tower 61.

[0064] Further optionally, the bottom of the propylene oxide recovery tower 61 is connected to the light component discharge pipe 613; the purity of the propylene oxide output from the propylene oxide recovery tower 61 should be greater than the threshold value x1; when the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than the threshold value x1, the flow rate of the propylene oxide output from the propylene oxide recovery tower 61 is reduced to the threshold value g0; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x1 at this time, the flow rate of the auxiliary gas in the feeding unit is maintained; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than the threshold value x1 at this time, the flow rate of the auxiliary gas in the feeding unit is maintained; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than the threshold value x1 at this time, the flow rate of the auxiliary gas in the feeding unit is maintained; is equal to or less than the threshold value x1, the flow rate of the auxiliary gas in the feed unit is reduced to the threshold value f0; when the flow rate of the auxiliary gas in the feed unit is f0, if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x1, the light component discharge pipe 613 is maintained in a closed state; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is still equal to or less than the threshold value x1, the light component is discharged from the light component discharge pipe 613 until the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x1. Combined Figure 1The control principle of this embodiment includes: using a second online data acquisition device 611 (such as an online gas chromatograph or an online Raman spectrometer) to detect the purity of the material in the propylene oxide recovery tower overhead output pipeline 612 and transmit the information to the control unit in real time. When the control unit determines that the purity of the propylene oxide recovery tower overhead output pipeline 612 is equal to or less than a set threshold value x1 (such as 99%), the control unit controls the opening of the fifth on-off valve 75 to slowly decrease until the flow rate of the produced propylene oxide drops to g0 (such as 0.3 kg / h). At this time, the control unit determines based on the purity of the material in the propylene oxide recovery tower overhead output pipeline 612: when the purity is greater than the set threshold value x1, the opening of the second on-off valve 72 on the auxiliary gas input pipe 12 is maintained unchanged. When the purity of the material in the propylene oxide recovery tower overhead output pipeline 612 is still equal to or less than the set threshold value x1, the opening of the second on-off valve 72 on the auxiliary gas input pipe 12 is slowly controlled to decrease, reducing the flow rate of the auxiliary gas in the feeding unit to f0. In this embodiment, when the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or lower than the threshold value x1, it is optional to promote sufficient distillation separation and thereby improve the purity by reducing the output volume; understandably, in this embodiment, if the purity of the produced propylene oxide still does not meet the requirements after the flow rate of the produced propylene oxide is reduced to g0, it is optional to slowly reduce the flow rate of the auxiliary gas in the feed unit 1 to f0 (for example, from 0.5SLM to 0.35SLM) to reduce the amount of light component impurities carried to the propylene oxide recovery tower 61, thereby facilitating the improvement of the purity of the produced propylene oxide; at this time, if the propylene oxide recovery tower 61 outputs If the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x1, reducing the auxiliary gas flow rate indicates that the purity of the propylene oxide output from the propylene oxide recovery tower 61 can be improved by reducing the auxiliary gas flow rate. Therefore, the light component discharge pipe 613 is maintained in a closed state. If the purity of the propylene oxide output from the propylene oxide recovery tower 61 is still equal to or less than the threshold value x1, simply reducing the auxiliary gas flow rate is no longer sufficient to improve the purity of the propylene oxide output from the propylene oxide recovery tower 61. In this case, light component impurities can be discharged from the light component discharge pipe 613 to improve the purity of the produced propylene oxide until the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x1. Furthermore, after the reaction system reaches equilibrium, the discharge of light components can be stopped, and then the flow rate of propylene oxide output from the propylene oxide recovery tower 61 and / or the auxiliary gas flow rate in the feed unit 1 can be increased.

[0065] Further optionally, the bottom of the propylene oxide recovery tower 61 is connected to the light component discharge pipe 613, and the process method includes: the purity of the propylene oxide output from the propylene oxide recovery tower 61 should be greater than the threshold value x2; when the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than the threshold value x2, the flow rate of the propylene oxide output from the propylene oxide recovery tower 61 is reduced to the threshold value g1; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x2 at this time, the light component discharge pipe 613 is maintained in a closed state; if the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than the threshold value x2 at this time, the light component is discharged from the light component discharge pipe 613 until the purity of the propylene oxide output from the propylene oxide recovery tower 61 is greater than the threshold value x2. Combined Figure 1 The control principle of this embodiment includes: using a second online acquisition device 611 (such as an online gas chromatograph or an online Raman spectrometer) to detect the purity of the material in the propylene oxide recovery tower top output pipeline 612 and transmit it to the control unit in real time; when the control unit determines that the purity of the propylene oxide recovery tower top output pipeline 612 is equal to or less than a set threshold value x2 (such as 98%), the control unit controls the opening of the fifth switch valve 75 to slowly decrease until the flow rate of the produced propylene oxide gradually decreases to g1 (such as 0.25 kg). / h), at which point the purity of the material in the propylene oxide recovery tower overhead output line 612 is determined: if the control unit determines that the purity is greater than x2, the sixth on-off valve 76 remains closed. If the control unit determines that the purity of the propylene oxide output from the propylene oxide recovery tower 61 is equal to or less than x2, the sixth on-off valve 76 in the light component discharge pipe 613 is controlled to open, thereby discharging some light component impurities, such as propionaldehyde and acetone, to improve the purity of the propylene oxide produced from the overhead of the propylene oxide recovery tower 61 until it meets the required purity. Furthermore, after the reaction system reaches equilibrium, the flow rate of propylene oxide produced from the propylene oxide recovery tower 61 can be increased and the sixth on-off valve 76 can be closed.

[0066] It can be understood that x1, x2, g0, g1, and f0 each independently represent a numerical value serving as a threshold, and as long as they do not exceed the basic principles defined by the present invention, they all fall within the scope of protection of the present invention.

[0067] It should be noted that the above is a further detailed description of the present invention in conjunction with specific embodiments, and the specific implementation of the present invention should not be considered to be limited to these descriptions. For those skilled in the art of the present invention, several simple improvements can be made without departing from the concept of the present invention, and all of these should be considered to fall within the scope of protection of the present invention.

Claims

1. A process for continuously preparing allyl alcohol from propylene oxide, characterized in that: The process comprises: Feeding unit: used to preheat propylene oxide and mix propylene oxide with auxiliary gas and then feed it into the subsequent reaction unit for reaction; Reaction unit: used for isomerization of propylene oxide to prepare allyl alcohol; the reaction unit includes a suspended bed reactor; Catalyst recovery unit: used to separate the catalyst from the reaction liquid output from the reaction unit and regenerate the catalyst; Solvent recovery unit: used for refining the solvent separated from the reaction liquid output from the reaction unit; the solvent recovery unit includes a solvent refining tower; Catalyst configuration unit: used to configure catalyst using the regenerated catalyst output from the catalyst recovery unit and the solvent output from the solvent recovery unit to obtain a catalyst solution, and the catalyst solution is transported to the reaction unit; the catalyst configuration unit is connected to a catalyst replenishing pipe; Allyl alcohol refining unit: used to separate and recover propylene oxide from the gaseous material output from the reaction unit, and purify it to obtain a high-purity allyl alcohol product; Collection unit: used to collect the purity and flow rate of the solvent output from the top of the solvent refining tower and transmit it to the control unit in real time; Control unit: controls the feed flow rate of the auxiliary gas in the feed unit and the feed flow rate of the catalyst replenishing pipe in the catalyst recovery unit according to the data of the acquisition unit.

2. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The bottom of the solvent refining tower is connected to a heavy component discharge pipe; the process method includes: the purity of the solvent output from the top of the solvent refining tower should be greater than a threshold value p1; when the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1, reducing the flow rate of the solvent output from the top of the solvent refining tower to a threshold value q0; If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1, the flow rate of the auxiliary gas in the feeding unit is maintained; If the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p1, the flow rate of the auxiliary gas in the feeding unit is increased to the threshold value t0; When the flow rate of the auxiliary gas in the feeding unit is t0, If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1, the heavy component discharge pipe is maintained in a closed state; If the purity of the solvent output from the top of the solvent refining tower is still equal to or less than the threshold value p1, the heavy component is discharged from the heavy component discharge pipe until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p1.

3. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The bottom of the solvent refining tower is connected to a heavy component discharge pipe; the process method comprises: The purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p2; When the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q1; If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2, the heavy component discharge pipe is maintained in a closed state; If the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p2, the heavy component is discharged from the heavy component discharge pipe until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p2.

4. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The process comprises: The purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p3; When the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q2; If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3, the feed flow rate of the catalyst replenishing pipe in the feed unit is maintained; If the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p3, the feed flow rate of the catalyst replenishing pipe in the feed unit is increased until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p3.

5. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The catalyst recovery unit includes a separator and a catalyst regeneration device; the catalyst regeneration device includes a cleaning agent washing device; The process method comprises: controlling the flow rate and washing time of the cleaning agent in the cleaning agent washing device according to the data of the acquisition unit; The purity of the solvent output from the top of the solvent refining tower should be greater than the threshold value p4; When the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4, reducing the flow rate of the solvent output from the top of the solvent refining tower to the threshold value q3; If the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4, the flow rate and washing time of the detergent in the detergent washing device are maintained; If the purity of the solvent output from the top of the solvent refining tower is equal to or less than the threshold value p4 at this time, the flow rate and washing time of the cleaning agent in the cleaning agent washing device are increased until the purity of the solvent output from the top of the solvent refining tower is greater than the threshold value p4.

6. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The allyl alcohol refining unit includes a propylene oxide recovery tower and an allyl alcohol refining tower; the process method includes: collecting the purity and flow rate of the propylene oxide output from the propylene oxide recovery tower and transmitting them to a control unit in real time, and controlling the feed flow rate of the auxiliary gas in the feeding unit according to the collected purity and flow rate data of the propylene oxide output from the propylene oxide recovery tower.

7. The process for continuously preparing allyl alcohol from propylene oxide according to claim 6, wherein The bottom of the propylene oxide recovery tower is connected to a light component discharge pipe; the purity of the propylene oxide output from the propylene oxide recovery tower should be greater than a threshold value x1; When the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x1, reducing the flow rate of the propylene oxide output from the propylene oxide recovery tower to the threshold value g0; If the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1, the flow rate of the auxiliary gas in the feeding unit is maintained; If the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x1, the flow rate of the auxiliary gas in the feeding unit is reduced to the threshold value f0; When the flow rate of the auxiliary gas in the feeding unit is f0, If the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1, the light component discharge pipe is maintained in a closed state; If the purity of the propylene oxide output from the propylene oxide recovery tower is still equal to or less than the threshold value x1, the light component is discharged from the light component discharge pipe until the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x1.

8. The process for continuously preparing allyl alcohol from propylene oxide according to claim 6, wherein The bottom of the propylene oxide recovery tower is connected to a light component discharge pipe; The process comprises: The purity of the propylene oxide output from the propylene oxide recovery tower should be greater than the threshold value x2; When the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x2, reducing the flow rate of the propylene oxide output from the propylene oxide recovery tower to the threshold value g1; If the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x2, the light component discharge pipe is maintained in a closed state; If the purity of the propylene oxide output from the propylene oxide recovery tower is equal to or less than the threshold value x2 at this time, the light component is discharged from the light component discharge pipe until the purity of the propylene oxide output from the propylene oxide recovery tower is greater than the threshold value x2.

9. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The catalyst configuration unit is connected to a solvent supply pipe; the process method includes: collecting the liquid level in the suspension bed reactor and transmitting it to a control unit in real time, and opening or closing the solvent supply pipe according to the collected liquid level data in the suspension bed reactor; And / or, the solid content in the suspended bed reactor is collected and transmitted to a control unit in real time, and the catalyst replenishing pipe is opened or closed according to the collected solid content data in the suspended bed reactor.

10. The process for continuously preparing allyl alcohol from propylene oxide according to claim 1, wherein The feeding unit is provided with temperature, pressure and flow control components for preheating and pressurizing the freshly fed propylene oxide and then feeding it into the reaction unit.

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