Fumaric acid removal method and removal system and application thereof

Abstract

The present invention relates to solvent recovery and processing technology, and discloses a fumaric acid removal method and removal system and their applications. The fumaric acid removal method comprises the following steps: subjecting a fluid containing fumaric acid to membrane separation through an inorganic ceramic membrane. The fumaric acid removal system comprises a membrane separator, the membrane separator comprising a membrane separator body, a filter element located inside the membrane separator body, a feed port located on the membrane separator body, and a discharge port located on the membrane separator body. The filter element contains an inorganic ceramic membrane, so that the fumaric acid-containing fluid can be input into the membrane separator body from the feed port, and after the fumaric acid is removed through membrane separation by the filter element, the fluid is discharged from the discharge port. The removal method and removal system have a high fumaric acid removal rate and a simple process.

Description

Technical Field

[0001] The invention relates to a solvent recovery and processing technology, in particular to a fumaric acid removal method, a fumaric acid removal system, and applications of the fumaric acid removal method and the system in recycling a maleic anhydride absorbent. Background Art

[0002] n-Butane reacts with a vanadium-phosphorus-oxygen catalyst to produce maleic anhydride. The maleic anhydride is then absorbed in an absorbent, dibutyl phthalate, in an absorption tower to produce a rich solvent containing maleic anhydride. This rich solvent is then stripped out of the maleic anhydride via a stripping tower. Because water is produced during the reaction of n-Butane to maleic anhydride, and the recycled absorbent contains water, this water readily reacts with the maleic anhydride to produce fumaric acid. Fumaric acid has a low solubility in water or organic solvents and can easily form deposits that clog pipes, heat exchangers, and other equipment. Therefore, effectively removing fumaric acid from the absorbent is crucial for absorbent recycling and maleic anhydride production.

[0003] EP0815098B1 discloses washing a fumaric acid-containing absorbent with water as an extractant after stripping maleic anhydride to prevent sedimentation. This technique requires mixing water with the absorbent, which is then centrifuged in a centrifuge for separation. This technique has the disadvantages of being complex, containing the absorbent in the aqueous phase after washing and separation, resulting in a high COD content in the wastewater, increasing the difficulty and cost of wastewater treatment. The separated solvent phase contains water, which, if introduced into the process system, further increases fumaric acid formation. DE102006024903A1 discloses completely or partially catalytically hydrogenating the fumaric acid-containing absorbent after stripping maleic anhydride, and recycling it partially or completely to the absorption stage. This technique requires a catalytic hydrogenation process, resulting in a complex process. CN101981018A discloses a method for separating fumaric acid and other minor components during the production of maleic anhydride. The method comprises concentrating an absorbent depleted of maleic anhydride under negative pressure (absolute pressure of 0.001-0.004 MPa) and high temperature (180-250°C). The concentrated absorbent is then cooled and passed through a random packing or structured packing (such as a mesh fabric woven from stainless steel, porcelain, or a polymer, or a wire mesh) to crystallize the fumaric acid on the packing. The packing is then periodically removed and cleaned with an alkaline solution to remove the precipitated fumaric acid and other components. This method requires concentrating the depleted absorbent under negative pressure and high temperature and then cooling it, resulting in high energy consumption. The absorbent has a long residence time on the packing, and the packing needs to be periodically removed and cleaned with an alkaline solution, making the process complex.

[0004] Therefore, the existing technology for removing fumaric acid from maleic anhydride absorbent and the device thereof still need to be further improved. Summary of the Invention

[0005] The purpose of the present invention is to overcome the problems of complex fumaric acid removal process and high cost in the prior art, and to provide a fumaric acid removal method and removal system and their application. The removal method and removal system have a high fumaric acid removal rate and a simple process.

[0006] In order to achieve the above-mentioned object, the first aspect of the present invention provides a method for removing fumaric acid, which comprises the following steps: subjecting a fluid containing fumaric acid to membrane separation through an inorganic ceramic membrane.

[0007] The second aspect of the present invention provides a fumaric acid removal system, which includes a membrane separator, wherein the membrane separator includes a membrane separator body, a filter element located inside the membrane separator body, a feed port located on the membrane separator body, and a discharge port located on the membrane separator body, wherein the filter element contains an inorganic ceramic membrane so that a fluid containing fumaric acid can be input into the membrane separator body from the feed port, and the fluid is discharged from the discharge port after membrane separation and removal of fumaric acid by the filter element.

[0008] A third aspect of the present invention provides use of the above-mentioned removal method and / or the above-mentioned removal system in recycling maleic anhydride absorbent.

[0009] The present invention provides a method and system for removing fumaric acid. The method adopts an inorganic ceramic membrane separation method to cause fumaric acid to adhere and deposit on the inorganic ceramic membrane, thereby separating and removing fumaric acid from a fluid. The method not only has a high removal rate, but also is simple to operate and suitable for industrial applications. On this basis, the reusable feature of the inorganic ceramic membrane is further utilized to rinse the attached fumaric acid, thereby regenerating the inorganic ceramic membrane and extending the operating cycle of the inorganic ceramic membrane. In addition, the water consumption during the removal method is significantly reduced, thereby effectively reducing energy consumption and costs. The method and system for removing fumaric acid have important application value for the recycling of maleic anhydride absorbent. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a structural schematic diagram of a specific embodiment of the fumaric acid removal system provided by the present invention.

[0011] Description of Reference Numerals

[0012] 1-Membrane separator, 11-Membrane separator body, 12-Filter element, 13-Feed port, 14-Discharge port; 2-Recovery tank; 3-Fluid recovery pipeline; 4-Gas pipeline; 5-Purge pipeline, 51-First purge pipeline, 52-Second purge pipeline; 6-Flushing liquid input pipeline; 7-Flushing liquid output pipeline; 8-Flushing liquid collection tank; 9-Liquid storage tank; 10-Feed pipeline. DETAILED DESCRIPTION

[0013] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0014] A first aspect of the present invention provides a method for removing fumaric acid, which comprises the following steps: subjecting a fluid containing fumaric acid to membrane separation through an inorganic ceramic membrane.

[0015] In the present invention, the fumaric acid-containing fluid refers to a mixture formed when a small amount of fumaric acid exists in a solvent in which fumaric acid is insoluble or slightly soluble, wherein the solvent of the fluid can be water or an organic solvent in which fumaric acid is insoluble or slightly soluble, such as ether, chloroform, etc.; preferably, the solvent of the fluid is an absorbent for maleic anhydride, and fumaric acid is slightly soluble or insoluble in the absorbent.

[0016] The inventors of the present invention unexpectedly discovered during their research on the recycling and utilization of depleted absorbents in the production process of maleic anhydride that the fumaric acid contained in the depleted absorbent can be efficiently attached and deposited on the inorganic ceramic membrane by using an inorganic ceramic membrane separation method to separate and remove the fumaric acid in the absorbent. At the same time, under the action of the inorganic ceramic membrane, a large fumaric acid concentration difference is formed on both sides of the membrane, further promoting the precipitation and deposition of fumaric acid. Not only does this method have a high removal rate for fumaric acid, but the removal method does not require the introduction of a large amount of water, nor does it involve complex reactions or treatment processes. It is simple and easy to operate and suitable for industrial applications. The method has important application value for the recycling of absorbents in the production process of maleic anhydride, and can effectively reduce the loss caused by the hydrolysis of the maleic anhydride product and reduce the loss of the absorbent.

[0017] According to the present invention, taking into account the acidic nature of fumaric acid, the inorganic ceramic membrane is selected to be acid-resistant. Preferably, the inorganic ceramic membrane is made of at least one of silicon carbide, silicon nitride, and diatomaceous earth; more preferably, the inorganic ceramic membrane is a silicon carbide ceramic membrane. The inventors have discovered that this preferred embodiment improves the efficiency of separating and removing fumaric acid from fluids.

[0018] In the present invention, the above-mentioned inorganic ceramic membranes can all be obtained commercially.

[0019] According to the present invention, the inorganic ceramic membrane can be of any specification, such as a tubular ceramic membrane or a flat ceramic membrane. Preferably, the pore size of the inorganic ceramic membrane is 1-500 nm; more preferably, the pore size of the inorganic ceramic membrane is 20-50 nm. The inventors have discovered that this preferred embodiment facilitates more complete contact between the inorganic ceramic membrane and fumaric acid in the fluid, resulting in more efficient adsorption and deposition of fumaric acid, thereby improving the removal rate of fumaric acid.

[0020] According to the present invention, preferably, the inorganic ceramic membrane is wound into a filter rod for membrane separation, and the inner surface area of ​​each filter rod is 0.001-100m 2 , more preferably 5-20m 2 The inventors have found that under this preferred embodiment, the inorganic ceramic membrane is conducive to more efficiently adsorbing fumaric acid in the deposition fluid, thereby improving the removal rate of fumaric acid.

[0021] According to the present invention, when the solvent in the fluid is an absorbent containing maleic anhydride and fumaric acid is slightly soluble or insoluble in the absorbent, the solvent can be a high-boiling-point inert absorbent. The boiling point of the inert high-boiling-point absorbent is generally at least 30°C higher than that of maleic anhydride, preferably at least 50°C, and particularly preferably at least 70°C. Exemplarily, the solvent in the fluid is a high-boiling-point phthalate, terephthalate, or maleate, such as dimethyl, diethyl, or dibutyl phthalate, dimethyl terephthalate, or dibutyl maleate; an aromatic hydrocarbon, such as dibenzylbenzene; a cycloaliphatic acid ester, such as dibutyl hexahydrophthalate; or a C4-C20 fatty acid ester, such as diethyl succinate, diethyl glutarate, or dibutyl adipate. More preferably, the solvent in the fluid is selected from one or more of dibutyl phthalate, diisobutyl hexahydrophthalate, and dibutyl adipate.

[0022] When the method of the present invention is applied to the production process of maleic anhydride, the absorbent depleted in the process is used as the fumaric acid-containing fluid, and a membrane separation method is used to remove the fumaric acid sediment, thereby recovering the absorbent (i.e., the solvent in the fluid). When actually applied to recovering the depleted absorbent in the maleic anhydride production process, it was further found that membrane separation using an inorganic ceramic membrane not only has a high efficiency in removing fumaric acid from the depleted absorbent, but also has a certain removal effect on maleic anhydride and phthalic anhydride.

[0023] According to the present invention, preferably, the temperature of the fluid is 10-100° C., more preferably 30-60° C. The inventors have found that under this preferred embodiment, it is beneficial to improve the adhesion and deposition of fumaric acid in the fluid on the inorganic ceramic membrane, thereby improving the removal efficiency.

[0024] According to the present invention, based on the reusability of inorganic ceramic membranes, the fumaric acid removal method preferably further comprises: regenerating the inorganic ceramic membrane within a predetermined period and reusing it for membrane separation. The inventors have discovered that this preferred embodiment extends the operating life of the inorganic ceramic membrane and significantly reduces water consumption during the removal process, thereby effectively reducing energy consumption and costs.

[0025] According to the present invention, preferably, the set period is 0.1-100 hours, more preferably 0.5-2 hours. Specifically, after the inorganic ceramic membrane performs membrane separation on the fumaric acid-containing fluid for a certain period of time, the membrane separation can be stopped and the inorganic ceramic membrane can be regenerated. The present invention does not exclude replacing the inorganic ceramic membrane after the certain period of operation with a new inorganic ceramic membrane or a regenerated inorganic ceramic membrane to continuously perform membrane separation on the fumaric acid-containing fluid, while regenerating the inorganic ceramic membrane in a separate device or equipment.

[0026] According to the present invention, conventional manner can be adopted to regenerate inorganic ceramic membrane, to realize fumaric acid and other impurities deposited on inorganic ceramic membrane are removed, and be dried, avoid introducing moisture when the fluid containing fumaric acid is processed and cause the further formation of fumaric acid. Preferably, the process of described regeneration comprises: first inorganic ceramic membrane is purged I (mainly remove the solvent of the described fluid remaining in inorganic ceramic membrane), then rinsing fluid is utilized to rinse inorganic ceramic membrane (mainly remove the impurities such as fumaric acid attached in inorganic ceramic membrane), then inorganic ceramic membrane is purged II (mainly remove the rinsing fluid remaining in inorganic ceramic membrane). The inventor finds that under this preferred embodiment, it is possible to improve the recovery efficiency to fluid, reduce the solvent loss in fluid, avoid the residual of rinsing fluid in inorganic ceramic membrane simultaneously, no moisture is brought into the solvent of fluid, when being applied to the absorbent recovery when producing maleic anhydride, it is avoided that because water enters absorbent and contacts with maleic anhydride to form fumaric acid again.

[0027] According to the present invention, various inert gases may be used in the purge I and the purge II. Preferably, the gases used in the purge I and the purge II are nitrogen and / or argon.

[0028] According to the present invention, preferably, the flushing liquid is hot water at 50-80°C. The inventors have found that under this preferred embodiment, it is beneficial to reduce the water consumption for backwashing the inorganic ceramic membrane. The amount of hot water used for treating each ton of absorbent can be reduced to about 0.03 tons, which saves about 88% of the water consumption for centrifugal separation in the prior art.

[0029] The second aspect of the present invention provides a fumaric acid removal system, which includes a membrane separator 1, the membrane separator 1 including a membrane separator body 11, a filter element 12 located inside the membrane separator body 11, a feed port 13 located on the membrane separator body 11, and a discharge port 14 located on the membrane separator body 11. The filter element 12 contains an inorganic ceramic membrane so that a fluid containing fumaric acid can be input into the membrane separator body 11 from the feed port 13, and the fluid is discharged from the discharge port 14 after membrane separation and removal of fumaric acid through the filter element 12.

[0030] The fumaric acid removal system provided by the present invention can effectively utilize the inorganic ceramic membrane of the filter element 12 to perform membrane separation on the fumaric acid in the fluid, so that the fumaric acid adheres and deposits on the inorganic ceramic membrane to separate and remove the fumaric acid in the fluid, and recycle the solvent of the fluid. It not only has a high fumaric acid removal rate, but also is simple and easy to operate and suitable for industrial applications.

[0031] In the present invention, the feed port 13 and the discharge port 14 can be located on the side wall or the upper and lower ends of the membrane separator body 11. Preferably, the feed port 13 is located at the bottom of the membrane separator body 11, and the discharge port 14 is located in the middle of the side wall of the membrane separator body 11, so as to extend the contact time of the fumaric acid-containing fluid with the filter element 12 in the membrane separator body 11, thereby improving the removal effect of fumaric acid in the fluid.

[0032] According to the present invention, the removal system preferably further includes a recovery tank 2 connected to a discharge port 14, so that the fluid (primarily the solvent) after contact with the inorganic ceramic membrane to fully remove the fumaric acid can enter the recovery tank 2 through the discharge port 14 and ultimately be recycled back to the absorption tower for reuse as an absorbent. The recovery tank 2 and the discharge port 14 can be connected in a conventional manner. Preferably, the recovery tank 2 and the discharge port 14 are connected via a fluid recovery pipe 3.

[0033] According to the present invention, the removal system preferably further includes a purge mechanism capable of purging the filter element 12. This allows for periodic purges after the membrane separator 1 has operated for a period of time, thereby reducing the amount of impurities (e.g., fluid solvent, flushing fluid, etc.) remaining on the inorganic ceramic membrane and thereby preventing any adverse effects on the adsorption and removal of fumaric acid. Furthermore, the purge mechanism preferably purges the fluid solvent from the filter element 12 and discharges it into the recovery tank 2, thereby improving the recovery rate of the fluid solvent and reducing absorbent loss.

[0034] According to the present invention, the purge mechanism can adopt various devices or structures that can input gas into the membrane separator body 11 to purge the filter element 12. Preferably, the purge mechanism includes a gas pipeline 4 and a purge pipeline 5, one end of the gas pipeline 4 is connected to the gas source, and the other end is connected to the membrane separator body 11 (preferably connected to the top of the membrane separator body 11), and the purge pipeline 5 includes a first purge pipeline 51 and a second purge pipeline 52, one end of the first purge pipeline 51 is connected to the lower side wall of the membrane separator body 11, and the other end is connected to the recovery tank 2, and one end of the second purge pipeline 52 is connected to the bottom of the membrane separator body 11, and the other end is connected to the recovery tank 2. At this time, the purge gas enters the membrane separator body 11 from the gas pipeline 4, and the residual fluid on the filter element 12 is purged and removed. The purged fluid is discharged into the recovery tank 2 through the first purge pipeline 51 and the second purge pipeline 52. Among them, the first purge pipeline 51 is used to drain the fluid filtrate after filtration (after membrane separation), and the second purge pipeline 52 is used to drain the fluid original liquid before filtration (before membrane separation), so as to realize the rapid and efficient collection of the residual fluid on the filter element 12 and shorten the operation time.

[0035] In the present invention, the gas source may be an inert gas storage tank or an inert gas generating device, so that the inert gas is used as the purge gas; preferably, the gas source is nitrogen and / or argon.

[0036] According to the present invention, preferably, the removal system further includes a flushing mechanism capable of flushing the filter element 12 , so as to achieve the effect of backwashing and regenerating the inorganic ceramic membrane of the filter element 12 .

[0037] According to the present invention, preferably, the flushing mechanism includes a flushing liquid input pipe 6, a flushing liquid output pipe 7 and a flushing liquid collection tank 8, one end of the flushing liquid input pipe 6 is connected to the flushing liquid storage tank (preferably using hot water stored at 50-80°C), and the other end is connected to the membrane separator body 11 (preferably connected to the top of the side wall of the membrane separator body 11), one end of the flushing liquid output pipe 7 is connected to the membrane separator body 11 (preferably connected to the bottom of the membrane separator body 11), and the other end is connected to the flushing liquid collection tank 8. At this time, the flushing liquid is input into the membrane separator body 11 through the flushing liquid input pipe 6 to flush the fumaric acid attached to the outside and inside of the filter element 12. The flushing liquid after flushing is transported to the flushing liquid collection tank 8 through the flushing liquid output pipe 7 for collection.

[0038] In a more preferred embodiment, the removal system is provided with the above-mentioned flushing mechanism and the above-mentioned purging mechanism to cooperate to realize the following inorganic ceramic membrane regeneration process: after the membrane separator 1 has been running for a period of time, the feed port 13 and the discharge port 14 are closed, and the gas source is first input into the membrane separator body 11 using the gas pipeline 4, and the residual fluid raw liquid and fluid filtrate outside the filter element 12 are removed by purging I and discharged into the recovery tank 2 through the first purging pipeline 51 and the second purging pipeline 52; and the flushing liquid is then input into the membrane separator body 11 using the flushing liquid input pipeline 6 to purify the residual fluid raw liquid and fluid filtrate outside the filter element 12. The fumaric acid deposits are flushed away, and the resulting flushing liquid is transported to a flushing liquid collection tank 8 via a flushing liquid output pipe 7. Gas is then again supplied to the membrane separator body 11 via the gas pipe 4, removing any residual flushing liquid from the exterior and interior of the filter element 12 via purge II. The remaining flushing liquid is then discharged to the flushing liquid collection tank 8 via the flushing liquid output pipe 7, thereby restoring the flux of the inorganic ceramic membrane of the filter element 12. The progress of purge I and purge II can be controlled by observing through a sight glass on the membrane separator body 11, and the respective purge times can also be optimized and set based on process parameters. This process can be program-controlled, automatically switching between operations periodically after the membrane separator 1 is operational to flush the inorganic ceramic membrane of the filter element 12, resulting in a high degree of automation.

[0039] According to the present invention, the feed port 13 of the membrane separator 1 can be directly connected to the device for generating the fumaric acid-containing fluid, or the fumaric acid-containing fluid can be collected and then supplied to the feed port 13 of the membrane separator 1. Preferably, the removal system further includes a liquid storage tank 9 for storing the fluid, and the liquid storage tank 9 is connected to the feed port 13 so that the fumaric acid-containing fluid can be more stably fed into the membrane separator 1. Further preferably, the liquid storage tank 9 and the feed port 13 are connected via a feed pipe 10, one end of the feed pipe 10 being connected to the liquid storage tank 9 and the other end being connected to the feed port 13.

[0040] According to the present invention, a fumaric acid-containing fluid enters the membrane separator body 11 through the feed port 13 at a certain pressure, thereby creating a pressure differential across the inorganic ceramic membrane of the filter element 12. This satisfies the driving force required for the membrane separation process, improves the permeability of the fluid through the inorganic ceramic membrane, and thereby enhances the efficiency of membrane separation in removing fumaric acid from the fluid. Preferably, a liquid pump is provided on the feed conduit 10, and the outlet pressure of the liquid pump is 0.1-2 MPa (gauge pressure), more preferably 0.3-0.6 MPa (gauge pressure).

[0041] According to the present invention, the fluid temperature is preferably 10-100°C, more preferably 30-60°C. The inventors have discovered that under this preferred embodiment, the viscosity of the fluid is reduced, which facilitates the movement of solutes from the membrane surface into the bulk fluid, thinning the concentration polarization layer on the membrane surface, thereby improving the membrane separation flow rate and increasing the membrane permeation flux. For example, the temperature of the fumaric acid-containing fluid can be controlled by providing a heating and temperature control mechanism on the liquid storage tank 9.

[0042] According to the present invention, preferably, the filter element 12 comprises at least one filter rod wound with an inorganic ceramic membrane, and the inner surface area of ​​each filter rod is 0.001-100m 2 , more preferably 5-20m 2 The number of filter elements 12 is preferably multiple to increase the rate of membrane separation and removal of fumaric acid.

[0043] According to the present invention, preferably, the solvent in the fluid is selected from one or more of dibutyl phthalate, diisobutyl hexahydrophthalate and dibutyl adipate.

[0044] It should be noted that each of the pipelines or conduits described herein (including the fluid recovery pipeline 3, gas pipeline 4, first purge pipeline 51, second purge pipeline 52, flushing liquid input pipeline 6, flushing liquid output pipeline 7, and feed pipeline 10) is equipped with a valve to control the opening and closing of the corresponding pipeline. Furthermore, the feed pipeline 10 is also equipped with a flow switch to monitor or control the flow of the fumaric acid-containing fluid entering the membrane separator 1.

[0045] A third aspect of the present invention provides the use of the aforementioned removal method and / or removal system for recycling a maleic anhydride absorbent. After absorbing maleic anhydride, the solvent-rich absorbent is stripped through a stripping tower to remove the maleic anhydride, forming an absorbent containing fumaric acid. After the fumaric acid is removed by the aforementioned removal method and / or removal system, the absorbent can be recycled.

[0046] According to a particularly preferred embodiment of the present invention, see Figure 1 The fumaric acid removal system includes a membrane separator 1, a recovery tank 2, a purge mechanism capable of purging a filter element 12, a flushing mechanism capable of flushing the filter element 12, and a liquid storage tank 9 for storing a fluid containing fumaric acid; the membrane separator 1 includes a membrane separator body 11, a filter element 12 located inside the membrane separator body 11, a feed port 13, and a discharge port 14; the filter element 12 includes a plurality of filter rods formed by winding silicon carbide ceramic membranes, the pore size of the silicon carbide ceramic membranes is 1-500nm, and the inner surface area of ​​each filter rod is 0.001-100m 2The feed port 13 is located at the bottom of the membrane separator body 11, the discharge port 14 is located in the middle of the side wall of the membrane separator body 11, the recovery tank 2 is connected to the discharge port 14 through a fluid recovery pipe 3, the liquid storage tank 9 is connected to the feed port 13 through a feed pipe 10, a heating and temperature control mechanism is provided on the liquid storage tank 9, and a liquid pump and a flow switch control are provided on the feed pipe 10; the purge mechanism includes a gas pipe 4 and a purge pipe 5, one end of the gas pipe 4 is connected to the gas source and the other end is connected to the membrane separator body 11, the purge pipe 5 includes a first purge pipe 51 and a second purge pipe 52. Pipeline 52, one end of the first purge pipeline 51 is connected to the lower side wall of the membrane separator body 11, and the other end is connected to the recovery tank 2, one end of the second purge pipeline 52 is connected to the bottom of the membrane separator body 11, and the other end is connected to the recovery tank 2; the flushing mechanism includes a flushing liquid input pipeline 6, a flushing liquid output pipeline 7 and a flushing liquid collecting tank 8, one end of the flushing liquid input pipeline 6 is connected to the flushing liquid storage tank, and the other end is connected to the membrane separator body 11, one end of the flushing liquid output pipeline 7 is connected to the membrane separator body 11, and the other end is connected to the flushing liquid collecting tank 8.

[0047] On this basis, a particularly preferred embodiment of the method for removing fumaric acid provided by the present invention comprises the following steps:

[0048] S1. Open the valves on the feed pipe 10 and the fluid recovery pipe 3, and close the valves on the other pipes. Use the heating and temperature control mechanism on the liquid storage tank 9 to control the temperature of the fluid containing fumaric acid in the liquid storage tank 9 to 10-100° C., turn on the liquid pump on the feed pipe 10, control the outlet pressure of the liquid pump to 0.1-2 MPa, and input the fluid in the liquid storage tank 9 into the membrane separator body 11 through the feed port 13, so that when the fluid containing fumaric acid flows through the filter element 12, the silicon carbide ceramic membrane is used for membrane separation to intercept the fumaric acid to obtain the fluid to be recovered (mainly the fluid solvent), and the fluid to be recovered is transported from the discharge port 14 through the fluid recovery pipe 3 to the recovery tank 2;

[0049] S2. After the filter element 12 has been operating for 0.1-100 hours, the valves on the feed pipe 10 and the fluid recovery pipe 3 are closed, and the valves on the gas pipe 4, the first purge pipe 51, and the second purge pipe 52 are opened. The purge gas is fed into the membrane separator body 11 through the gas pipe 4 and purged for 1-2 minutes to remove the residual fluid solvent on the filter element 12. The purged fluid solvent is discharged into the recovery tank 2 through the first purge pipe 51 and the second purge pipe 52;

[0050] S3. Close the valves on the gas pipeline 4, the first purge pipeline 51, and the second purge pipeline 52, open the valves on the flushing liquid input pipeline 6 and the flushing liquid output pipeline 7, and input 50-80°C hot water as a flushing liquid into the membrane separator body 11 through the flushing liquid input pipeline 6 to flush the fumaric acid and other impurities attached to and deposited on the outside and inside of the filter element 12. The flushing liquid is then transported to the flushing liquid collection tank 8 through the flushing liquid output pipeline 7. Close the valve on the flushing liquid input pipeline 6, open the valve on the gas pipeline 4, and again use the gas pipeline 4 to input a gas source into the membrane separator body 11. Remove the residual flushing liquid on the outside and inside of the filter element 12 by purge for 1-2 minutes, and discharge it to the flushing liquid collection tank 8 through the flushing liquid output pipeline 7, so that the silicon carbide ceramic membrane of the filter element 12 can recover its flux.

[0051] S4. Repeat the above steps S1-S3.

[0052] The present invention will be described in detail below through examples.

[0053] In the following examples, the absorbent depleted during the maleic anhydride production process (as a fumaric acid-containing fluid) was collected from the maleic anhydride production line of Sinopec Yizheng Chemical Fiber Co., Ltd., the absorbent used was dibutyl phthalate produced by Shandong Kexing Chemical Co., Ltd., and the fumaric acid was produced during the operation of the maleic anhydride production unit and dissolved in the dibutyl phthalate; the silicon carbide ceramic membrane was purchased from Landson Membrane Technology Nanjing Co., Ltd.; unless otherwise specified, the remaining reagents and raw materials were conventional commercially available products.

[0054] In the following examples, the contents of fumaric acid, maleic anhydride, and phthalic anhydride were respectively measured by gas chromatography using an Agilent HP-130m×0.32mm×0.25um capillary gas chromatography column; the specific detection process is as follows: standard products of fumaric acid, maleic anhydride, and phthalic anhydride are respectively injected into a gas chromatograph to detect the characteristic peak time of each of fumaric acid, maleic anhydride, and phthalic anhydride; 0.2 μL of acetonitrile is injected into the chromatograph, the sample is placed on a heating block dried at 65°C and heated for 10 min, 0.2 μL is injected into the chromatograph, and the characteristic peak area of ​​each of fumaric acid, maleic anhydride, and phthalic anhydride is detected. Based on all characteristic peak areas of the sample, the content of each of fumaric acid, maleic anhydride, and phthalic anhydride in the sample is calculated.

[0055] Example 1

[0056] The fumaric acid removal system includes a membrane separator 1, a recovery tank 2, a purge mechanism capable of purging a filter element 12, a flushing mechanism capable of flushing the filter element 12, and a liquid storage tank 9 for storing a fluid containing fumaric acid; the membrane separator 1 includes a membrane separator body 11, a filter element 12 located inside the membrane separator body 11, a feed port 13, and a discharge port 14; the filter element 12 includes a plurality of filter rods formed of silicon carbide ceramic membranes, the pore size of the silicon carbide ceramic membranes is 50 nm, and the inner surface area of ​​each filter rod is 10 m 2 The feed port 13 is located at the bottom of the membrane separator body 11, the discharge port 14 is located in the middle of the side wall of the membrane separator body 11, the recovery tank 2 is connected to the discharge port 14 through a fluid recovery pipe 3, the liquid storage tank 9 is connected to the feed port 13 through a feed pipe 10, a heating and temperature control mechanism is provided on the liquid storage tank 9, and a liquid pump and a flow switch control are provided on the feed pipe 10; the purge mechanism includes a gas pipe 4 and a purge pipe 5, one end of the gas pipe 4 is connected to the gas source and the other end is connected to the membrane separator body 11, the purge pipe 5 includes a first purge pipe 51 and a second purge pipe 52. Pipeline 52, one end of the first purge pipeline 51 is connected to the lower side wall of the membrane separator body 11, and the other end is connected to the recovery tank 2, one end of the second purge pipeline 52 is connected to the bottom of the membrane separator body 11, and the other end is connected to the recovery tank 2; the flushing mechanism includes a flushing liquid input pipeline 6, a flushing liquid output pipeline 7 and a flushing liquid collecting tank 8, one end of the flushing liquid input pipeline 6 is connected to the flushing liquid storage tank, and the other end is connected to the membrane separator body 11, one end of the flushing liquid output pipeline 7 is connected to the membrane separator body 11, and the other end is connected to the flushing liquid collecting tank 8.

[0057] Based on the above removal system, the method for removing fumaric acid from the depleted absorbent during the production of maleic anhydride comprises the following steps:

[0058] S1, the feed pipe 10 and the valve on the fluid recovery pipe 3 are opened, the valves on the other pipes are closed, the temperature of the fluid containing fumaric acid in the liquid storage tank 9 is controlled to 58 ° C by the heating and temperature control mechanism on the liquid storage tank 9, the liquid pump on the feed pipe 10 is turned on, the outlet pressure of the liquid pump is controlled to 0.5 MPa (the outlet flow rate of the fluid containing fumaric acid is controlled to 5 tons / h), the fluid in the liquid storage tank 9 is input into the membrane separator body 11 through the feed port 13, so that the fluid containing fumaric acid flows through the filter element 12, and the fumaric acid is intercepted by the silicon carbide ceramic membrane to obtain the fluid to be recovered, and the fluid to be recovered is transported from the discharge port 14 to the recovery tank 2 through the fluid recovery pipe 3, and finally circulated back to the absorption tower for recycling as an absorbent;

[0059] S2. After the filter element 12 has been operating for 1 hour, the valves on the feed pipe 10 and the fluid recovery pipe 3 are closed, and the valves on the gas pipe 4, the first purge pipe 51, and the second purge pipe 52 are opened. Nitrogen is introduced into the membrane separator body 11 through the gas pipe 4. The nitrogen is purged for 2 minutes to remove the residual fluid solvent on the filter element 12. The purged fluid solvent is discharged into the recovery tank 2 through the first purge pipe 51 and the second purge pipe 52;

[0060] S3. Close the valves on the gas pipeline 4, the first purge pipeline 51, and the second purge pipeline 52, open the valves on the flushing liquid input pipeline 6 and the flushing liquid output pipeline 7, and input 60°C hot water as a flushing liquid into the membrane separator body 11 through the flushing liquid input pipeline 6 to flush the fumaric acid and other impurities attached to and deposited on the outside and inside of the filter element 12. The flushing liquid after flushing is transported to the flushing liquid collection tank 8 through the flushing liquid output pipeline 7 (according to calculations, 0.03 tons of hot water is consumed for every ton of fluid containing fumaric acid); close the valve on the flushing liquid input pipeline 6, open the valve on the gas pipeline 4, and again use the gas pipeline 4 to input purge gas into the membrane separator body 11, remove the residual flushing liquid on the outside and inside of the filter element 12 by purge for 2 minutes, and discharge it into the flushing liquid collection tank 8 through the flushing liquid output pipeline 7, so that the silicon carbide ceramic membrane of the filter element 12 can recover its flux;

[0061] S4. Repeat the above steps S1-S3.

[0062] Example 2

[0063] The removal system and removal method provided in Example 1 are used to remove fumaric acid from the fluid, except that the temperature of the fumaric acid-containing fluid is controlled to 35° C. in step S1 .

[0064] Example 3

[0065] The removal system and removal method provided in Example 2 are used to remove fumaric acid from the fluid, except that the outlet pressure of the liquid pump in step S1 is replaced with 0.6 MPa.

[0066] Example 4

[0067] The removal system and removal method provided in Example 2 are used to remove fumaric acid from the fluid, except that the pore size of the silicon carbide ceramic membrane is replaced with 100 nm; and the time for purging the residual flushing liquid outside and inside the filter element 12 in step S3 is replaced with 1 minute.

[0068] Example 5

[0069] The removal system and removal method provided in Example 2 are used to remove fumaric acid from the fluid, except that the pore size of the silicon carbide ceramic membrane is replaced with 100 nm; and the operating time of the filter element 12 in step S2 is replaced with 2 hours.

[0070] Example 6

[0071] The removal system and removal method provided in Example 1 are used to remove fumaric acid from the fluid, except that the temperature of the fumaric acid-containing fluid is controlled to 15° C. in step S1 .

[0072] Example 7

[0073] The removal system and removal method provided in Example 1 are used to remove fumaric acid from the fluid, except that the temperature of the fumaric acid-containing fluid is controlled to 80° C. in step S1 .

[0074] Example 8

[0075] The removal system and removal method provided in Example 1 are used to remove fumaric acid from the fluid, except that the outlet pressure of the liquid pump is replaced with 1.5 MPa in step S1.

[0076] Example 9

[0077] The removal system and removal method provided in Example 4 are used to remove fumaric acid from the fluid, except that in step S1, the surface area of ​​each filter rod is replaced with 30m 2 .

[0078] Comparative Example 1

[0079] The removal system and removal method provided in Example 1 are used to remove fumaric acid from the fluid, except that in step S1, the silicon carbide ceramic membrane is replaced with a glass membrane with a pore size of 50 nm (purchased from Nanjing Landson Membrane Technology Co., Ltd.).

[0080] Comparative Example 2

[0081] The fumaric acid-containing fluid and 58°C hot water are mixed and stirred at a volume ratio of 1:4 to obtain a mixture, and the mixture is pressed into a centrifuge by nitrogen. After high-speed centrifugation, the organic phase and the aqueous phase are separated through the discharge on both sides.

[0082] In Comparative Example 1, 0.25 tons of wastewater containing organic solvents was generated for every ton of absorbent processed. The content of fumaric acid in the organic phase before and after the treatment was measured, and the results are shown in Table 1.

[0083] Test Case

[0084] When treating the depleted absorbent in the maleic anhydride production process in Examples 1 to 9, the flushing time was the same, but the purge time was different, and approximately 0.03 tons of hot water was consumed per ton of fluid containing fumaric acid. The fumaric acid content in the fluid before and after membrane separation in step S1 of Examples 1 to 9 and Comparative Example 1 was measured, and the results are shown in Table 1.

[0085] Table 1 Fumaric acid content in the treated fluid

[0086] serial number Maleic anhydride (wt%) Fumaric acid (wt%) Phthalic anhydride (wt%) Untreated absorbent 0.2 0.1 0.3 Example 1 0.04 0.028 0.1 Example 2 0.04 0.03 0.1 Example 3 0.06 0.04 0.14 Example 4 0.1 0.06 0.2 Example 5 0.08 0.062 0.2 Example 6 0.05 0.032 0.12 Example 7 0.05 0.034 0.14 Example 8 0.06 0.042 0.16 Example 9 0.08 0.06 0.18 Comparative Example 1 0.14 0.09 0.24 Comparative Example 2 0.1 0.09 0.22

[0087] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, various simple variations of the technical solution of the present invention may be made, including combining the various technical features in any other appropriate manner. These simple variations and combinations should also be regarded as disclosed in the present invention and fall within the scope of protection of the present invention.

Claims

1. A method for removing fumaric acid, characterized in that: The method comprises the following steps: subjecting a fluid containing fumaric acid to membrane separation through an inorganic ceramic membrane, wherein the pore size of the inorganic ceramic membrane is 1-500 nm, and the solvent in the fluid is selected from one or more of dibutyl phthalate, diisobutyl hexahydrophthalate and dibutyl adipate.

2. The removal method according to claim 1, characterized in that The inorganic ceramic membrane is a membrane made of at least one material selected from silicon carbide, silicon nitride and diatomaceous earth; and / or The pore size of the inorganic ceramic membrane is 20-50 nm; and / or The inorganic ceramic membrane is wound into a filter rod for membrane separation, and the inner surface area of ​​each filter rod is 0.001-100m 2 and / or The temperature of the fluid is 10-100°C.

3. The removal method according to claim 2, characterized in that: The inorganic ceramic membrane is a silicon carbide ceramic membrane; and / or The inner surface area of ​​each filter rod is 5-20m 2 and / or The temperature of the fluid is 30-60°C.

4. The removal method according to any one of claims 1 to 3, characterized in that: The method further comprises: regenerating the inorganic ceramic membrane within a set period and then reusing it for the membrane separation.

5. The removal method according to claim 4, characterized in that: The set period is 0.1-100h; and / or The regeneration process includes: firstly purging the inorganic ceramic membrane I, then flushing the inorganic ceramic membrane with a flushing liquid, and then purging the inorganic ceramic membrane II.

6. The removal method according to claim 5, characterized in that: The set period is 0.5-2h; and / or The gas used in the purge I and the purge II is nitrogen and / or argon, and the flushing liquid is hot water at 50-80°C.

7. A fumaric acid removal system, characterized in that: The removal system comprises a membrane separator (1), wherein the membrane separator (1) comprises a membrane separator body (11), a filter element (12) located inside the membrane separator body (11), a feed port (13) located on the membrane separator body (11), and a discharge port (14) located on the membrane separator body (11), wherein the filter element (12) comprises an inorganic ceramic membrane, so that a fluid containing fumaric acid can be fed into the membrane separator body (11) from the feed port (13), and the fluid is discharged from the discharge port (14) after membrane separation and interception of fumaric acid by the filter element (12), wherein the pore size of the inorganic ceramic membrane is 1-500 nm, and the solvent in the fluid is selected from one or more of dibutyl phthalate, diisobutyl hexahydrophthalate, and dibutyl adipate.

8. The removal system according to claim 7, characterized in that The removal system also includes a recovery tank (2) connected to the discharge port (14).

9. The removal system according to claim 8, characterized in that The recovery tank (2) is connected to the discharge port (14) via a fluid recovery pipe (3).

10. The removal system according to claim 9, characterized in that The removal system also includes a purge mechanism capable of purging the filter element (12).

11. The removal system according to claim 10, characterized in that The purge mechanism comprises a gas pipeline (4) and a purge pipeline (5), one end of the gas pipeline (4) is connected to the gas source, and the other end is connected to the membrane separator body (11), the purge pipeline (5) comprises a first purge pipeline (51) and a second purge pipeline (52), one end of the first purge pipeline (51) is connected to the lower side wall of the membrane separator body (11), and the other end is connected to the recovery tank (2), and one end of the second purge pipeline (52) is connected to the bottom of the membrane separator body (11), and the other end is connected to the recovery tank (2).

12. The removal system according to claim 11, characterized in that The removal system also includes a flushing mechanism capable of flushing the filter element (12).

13. The removal system according to claim 12, characterized in that The flushing mechanism comprises a flushing liquid input pipe (6), a flushing liquid output pipe (7) and a flushing liquid collection tank (8), one end of the flushing liquid input pipe (6) is connected to the flushing liquid storage tank, and the other end is connected to the membrane separator body (11), and one end of the flushing liquid output pipe (7) is connected to the membrane separator body (11), and the other end is connected to the flushing liquid collection tank (8).

14. The removal system according to any one of claims 7 to 13, characterized in that The removal system further comprises a liquid storage tank (9) for storing the fluid, wherein the liquid storage tank (9) is connected to the feed port (13).

15. The removal system according to claim 14, characterized in that The liquid storage tank (9) is connected to the feed port (13) via a feed pipe (10); and / or The feed pipe (10) is provided with a liquid pump, and the outlet pressure of the liquid pump is 0.1-2 MPa.

16. The removal system according to any one of claims 7 to 13, characterized in that The inorganic ceramic membrane is a membrane made of at least one material selected from silicon carbide, silicon nitride and diatomaceous earth; and / or The pore size of the inorganic ceramic membrane is 20-50 nm; and / or The filter element (12) comprises at least one filter rod wound with the inorganic ceramic membrane, and the inner surface area of ​​each filter rod is 0.001-100m 2 and / or The temperature of the fluid is 10-100°C.

17. The removal system according to claim 16, characterized in that The inorganic ceramic membrane is a silicon carbide ceramic membrane; and / or The inner surface area of ​​each filter rod is 5-20m 2 and / or The temperature of the fluid is 30-60°C.

18. Use of the removal method according to any one of claims 1 to 6 and / or the removal system according to any one of claims 7 to 17 in recycling maleic anhydride absorbent.

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