A continuous separation and purification device and method for oil methyl esterification reaction liquid based on super-hydrophobic PVDF membrane
The continuous separation and purification device for oil-methyl esterification reaction liquid using superhydrophobic PVDF membranes solves the problems of cumbersome biodiesel separation processes and the difficulty of separation under strong acid and alkali environments using traditional membranes by utilizing the selective permeability of superhydrophobic porous PVDF membranes and magnetic clamping technology. It achieves efficient, low-cost and automated separation results.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- DALIAN UNIV OF TECH
- Filing Date
- 2023-11-27
- Publication Date
- 2026-05-29
AI Technical Summary
Existing biodiesel separation processes are cumbersome and energy-intensive, and traditional superhydrophilic PVDF membranes have difficulty separating immiscible organic mixtures in strong acid and alkali environments.
A continuous separation and purification device for oil methyl esterification reaction solution using a superhydrophobic PVDF membrane utilizes the selective permeability of the superhydrophobic porous PVDF membrane. The membrane is clamped by magnetic attraction to achieve automatic oil phase stratification and selective component permeation. Combined with automated control of membrane clamping force, continuous and stable separation of acidic oil methyl esterification reaction solution is achieved.
It improves the purity of biodiesel separation, simplifies the equipment structure, reduces costs, and achieves efficient separation in acidic environments, featuring automation and intelligence.
Smart Images
Figure CN117463156B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of separation and purification, and relates to a continuous separation and purification device and method for oil methyl esterification reaction solution based on a superhydrophobic PVDF membrane. Background Technology
[0002] With dwindling oil reserves, there is an urgent need to develop alternative energy materials to alleviate the energy crisis. Biodiesel, with its advantages of being biodegradable, renewable, and low-polluting, is a green and environmentally friendly energy source that has attracted widespread attention worldwide and has broad application prospects. Biodiesel is primarily an ester compound produced from animal and vegetable oils, as well as waste cooking oil, through processes such as transesterification. Typically, the raw materials are mixed with methanol and a catalyst and then added to a reactor for esterification. After the reaction, glycerol and methyl ester are separated, and the methyl ester is distilled to obtain fatty acid methyl ester (biodiesel). However, due to the physical properties of methanol, fatty acids, and the catalyst, the esterification reaction is difficult to complete. The degree of separation of methanol, fatty acids, catalyst, glycerol, and methyl ester determines the quality of biodiesel.
[0003] Currently, many methods for processing methyl ester mixtures have been developed, such as distillation, rectification, secondary separation, heating, multi-stage separation, and physical precipitation. For example, Chinese patent CN114230465A discloses a process for separating dimethyl carbonate and methanol azeotropic mixtures through catalytic rectification and distillation. However, distillation and rectification processes are cumbersome, energy-intensive, and costly, while physical precipitation and separation show promising prospects and advantages in recovering incompatible oil-ester mixtures. For instance, Chinese patent CN115287310A discloses a solid-enzyme method for producing biodiesel, which further improves the purity of biodiesel through repeated precipitation. Another example is Chinese patent CN218932006U, which discloses a secondary separation system for the automatic and continuous separation of glycerol and methyl esters, improving the separation degree of methyl esters and glycerol. These methods reduce on-site operators and save production costs to some extent, but the separation purity still needs improvement, and the equipment is complex and costly. Therefore, there is an urgent need to develop a device and method for separating and purifying biodiesel with high purity, simple equipment, and low cost.
[0004] In recent years, with the rapid development of biomimetic superwetting materials, researchers have designed many functional surfaces with superhydrophobic / superoleophilic properties for efficient separation of oil-water mixtures. For example, Chinese patent CN111362351A discloses an oil-water separation device and method based on hydrophilic and hydrophobic metal meshes. Based on the difference in wettability of the functional membranes to water, water and oil in the oil-water mixture can effectively and selectively permeate, achieving oil-water separation. However, metal meshes are easily corroded by strong acids and alkalis, making them unsuitable for separating liquids with different wettability, such as strong acids and alkalis. Chinese patent CN109499393B discloses a superhydrophilic PVDF oil-water separation membrane for separating oily wastewater, its preparation method, and its application. The prepared superhydrophilic PVDF oil-water separation membrane can be used to separate immiscible oil-water mixtures and emulsion-stabilized oil-water emulsions. It exhibits excellent separation performance for both neutral and acidic mixtures or emulsions, and has broad industrial application value in wastewater treatment and oil extraction. However, this superhydrophilic PVDF membrane requires plasma treatment and acid modification, making the preparation process complex and unable to separate immiscible organic mixtures. Furthermore, the use of superwetting functional materials for the separation and purification of biological organic mixtures has not yet been studied or reported.
[0005] In summary, the problems with existing technologies include:
[0006] (1) In the existing technology, the traditional process for separating biodiesel mixtures is cumbersome, energy-intensive and costly;
[0007] (2) It is difficult to separate immiscible organic mixtures under strong acid and strong alkali conditions using wettable porous mesh / membrane. Summary of the Invention
[0008] To address the problems existing in the prior art, this invention proposes a continuous separation and purification device and method for oil methyl esterification reaction solution based on a superhydrophobic PVDF membrane, which realizes continuous, reliable and stable separation of fatty acid methyl esters in acidic oil methyl esterification reaction solution.
[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0010] A continuous separation and purification device for oil esterification reaction solution based on a superhydrophobic PVDF membrane is disclosed. The device includes an oil inlet chamber, a separation pipeline, two identical superhydrophobic porous PVDF membrane-fixed assemblies, and two oil collection tanks. The oil esterification reaction solution separation and purification device is fixed by a support frame 1.
[0011] The oil inlet chamber is an inverted T-shaped structure, which is used to fill the oil methyl esterification reaction solution. It includes two parts: a vertical pipeline and a horizontal pipeline. The top of the vertical pipeline is connected to the oil inlet, and the side of the vertical pipeline has an oil outlet. A valve is installed on the oil outlet pipeline to control the outflow rate. The horizontal pipeline is open at both ends and is connected to the superhydrophobic porous PVDF membrane-fixed assembly through a separation pipeline.
[0012] The separation pipeline is a hollow glass elbow, with two glass elbows connected to the first separation chamber and the second separation chamber respectively. The two separation chambers are symmetrically distributed, and the end of the separation chamber is an oil outlet chamber, which is connected to an oil collection tank. The oil collection tank is used to collect the separated oil. The separation chamber is a hollow pipeline structure, with a superhydrophobic porous PVDF membrane-fixing assembly installed in the middle.
[0013] The superhydrophobic porous PVDF membrane fixing assembly consists of, from top to bottom, an upper annular magnet, an upper glass plate, a superhydrophobic porous PVDF membrane, a lower glass plate, and a lower annular magnet. The inner hole of the upper annular magnet fits onto the outer wall of the separation chamber and is in contact with the upper glass plate. The inner hole of the lower annular magnet fits onto the outer wall of the oil outlet chamber and is in contact with the lower glass plate. The superhydrophobic porous PVDF membrane is clamped by the mutual attraction between the upper and lower annular magnets. The clamping force on the superhydrophobic porous PVDF membrane is adjusted by changing the distance between the upper and lower annular magnets.
[0014] A continuous separation and purification method for oil methyl esterification reaction solution based on a superhydrophobic PVDF membrane is disclosed. Based on the aforementioned apparatus, when the oil methyl esterification reaction solution is added to the oil inlet chamber from the top, due to the inherent physicochemical properties of the acidic oil methyl esterification reaction solution, the oil phase will automatically separate into two liquid layers under gravity after standing still for a period of time in the oil chamber. The upper layer is phase A, and the lower layer is phase B. Phase A is discharged through valve 4 at the oil outlet and enters an external collection tank for circulation and purification. The superhydrophobic porous PVDF membrane in the separation pipelines on both sides continuously selects the permeability of the phase B component in the oil solution. The selected permeable oil component finally flows out of the oil outlet chamber and reaches the collection tank. The method includes the following steps:
[0015] Step 1: Preparation of the separation chamber-fixation assembly:
[0016] A T-shaped hollow glass tube and two matching glass elbows are connected by glass glue. An oil outlet is located on the side wall of the T-shaped hollow glass tube, and the liquid flow rate is adjusted by a valve, connecting to an external liquid storage tank. Furthermore, this assembly is fixedly connected by a side support frame.
[0017] Step 2: Preparation of superhydrophobic porous PVDF membrane - Fixing assembly:
[0018] Four annular magnets are respectively fitted onto the outer walls of the two separation chambers and the two oil outlet chambers. Four glass plates are then connected to the separation chambers and the oil outlet chambers using resin adhesive. Utilizing the principle of attraction between opposite magnetic poles, the magnets create mutual attraction, applying pressure to the upper and lower glass plates to compress the superhydrophobic porous PVDF membrane.
[0019] Step 3: Assembly of the apparatus for continuous separation of acidic oil methyl esterification reaction solution:
[0020] The superhydrophobic porous PVDF membrane-fixed assembly and the separation chamber-fixed assembly are assembled. A collection tank is placed at the bottom of the oil outlet chamber and at the oil outlet to collect the separated and purified oil.
[0021] Compared with existing methods for continuous separation and purification of oil methyl esterification reaction solutions, this invention has the following advantages:
[0022] (1) The size of the superhydrophobic porous PVDF membrane is not limited by the inner diameter of the separation tube, and a larger superhydrophobic porous PVDF membrane can be used to further improve the separation efficiency of the system.
[0023] (2) The pressure between the superhydrophobic porous PVDF membranes is constant, which makes it easy to ensure that the superhydrophobic porous PVDF membranes do not fall off or leak during the separation process, thus ensuring the reliability of the system in the continuous and long-term separation of acidic oil methyl ester reaction solution.
[0024] (3) Electromagnetic coils can be used to regulate the clamping force on the PVDF membrane, thereby realizing the automated replacement and assembly of the superhydrophobic porous PVDF membrane, which is conducive to the automation and intelligent separation of acidic oil methyl ester reaction liquid. Attached Figure Description
[0025] Figure 1 This is a schematic diagram of the device structure of the present invention;
[0026] Figure 2 This is a graph showing the component analysis data after separation by the acidic methyl ester reaction solution separation and purification device described in this embodiment of the invention;
[0027] In the diagram: 1 Support frame; 2 Oil inlet; 3 Oil outlet; 4 Valve; 5 Oil inlet chamber; 6 First separation chamber; 7 Upper annular magnet A; 8 Upper glass plate A; 9 First superhydrophobic porous PVDF membrane; 10 Lower glass plate A; 11 Lower annular magnet A; 12 First oil collection tank; 13 First oil outlet chamber; 14 Second oil outlet chamber; 15 Second separation chamber; 16 Upper annular magnet B; 17 Upper glass plate B; 18 Second superhydrophobic porous PVDF membrane; 19 Lower glass plate B; 20 Lower annular magnet B; 21 Second oil collection tank. Detailed Implementation
[0028] The following figures, together with the accompanying drawings and specific embodiments, further illustrate the present invention, but the following embodiments are by no means intended to limit the present invention in any way.
[0029] like Figure 1 As shown, a continuous separation and purification device for oil esterification reaction liquid based on a superhydrophobic PVDF membrane is disclosed. The device includes an oil inlet chamber 5, a separation pipeline, two identical superhydrophobic porous PVDF membrane-fixed assemblies, and two oil collection tanks. The oil esterification reaction liquid separation and purification device is fixed by a side support frame 1.
[0030] The oil inlet chamber 5 is an inverted T-shaped structure, comprising a vertical pipeline and a horizontal pipeline. The top of the vertical pipeline is connected to the oil inlet 2, and the side of the vertical pipeline has an oil outlet 3. A valve 4 is installed on the oil outlet pipeline to control the outflow rate. The horizontal pipeline is open at both ends and connected to the superhydrophobic porous PVDF membrane-fixed assembly through a separation pipeline.
[0031] The separation conduit is a hollow glass elbow, with two glass elbows connected to the first separation chamber 6 and the second separation chamber 15 respectively. The two separation chambers are symmetrically distributed.
[0032] The first separation chamber 6 ends in a first oil outlet chamber 13, which is connected to the first oil collection tank 12. Both the first separation chamber 6 and the first oil outlet chamber 13 are cylindrical structures, and a superhydrophobic porous PVDF membrane-fixing assembly is installed between them. This superhydrophobic porous PVDF membrane-fixing assembly consists of, from top to bottom, an upper annular magnet A7, an upper glass plate A8, a first superhydrophobic porous PVDF membrane 9, a lower glass plate A10, and a lower annular magnet A11. The inner hole of the upper annular magnet A7 is fitted onto the outer wall of the first separation chamber 6 and contacts the upper glass plate A8. The inner hole of the lower annular magnet A11 is fitted onto the outer wall of the first oil outlet chamber 13 and contacts the lower glass plate A10. The mutual attraction between the upper and lower annular magnets A7 and A11 clamps the first superhydrophobic porous PVDF membrane 9 between the two glass plates. The clamping force on the first superhydrophobic porous PVDF membrane 9 is adjusted by changing the distance between the upper and lower annular magnets A7 and A11.
[0033] The second separation chamber 15 ends at the second oil outlet chamber 14, which is connected to the second oil collection tank 21. Both the second separation chamber 15 and the second oil outlet chamber 14 are cylindrical structures, and a superhydrophobic porous PVDF membrane-fixing assembly is installed between them. This superhydrophobic porous PVDF membrane-fixing assembly, from top to bottom, consists of an upper annular magnet B16, an upper glass plate B17, a second superhydrophobic porous PVDF membrane 18, a lower glass plate B19, and a lower annular magnet B20. The inner hole of the upper annular magnet B16 is fitted onto the outer wall of the second separation chamber 15 and contacts the upper glass plate B17. The inner hole of the lower annular magnet B19 is fitted onto the outer wall of the second oil outlet chamber 14 and contacts the lower glass plate B19. The mutual attraction between the upper and lower annular magnets B16 and B20 clamps the second superhydrophobic porous PVDF membrane 18 between the two glass plates. The clamping force on the second superhydrophobic porous PVDF membrane 18 is adjusted by adjusting the distance between the upper and lower annular magnets B16 and B20.
[0034] The two superhydrophobic porous PVDF membranes 18 and 9 are clamped together by the mutual attraction between two pairs of annular magnets: upper annular magnet B16 and lower annular magnet B20, and upper annular magnet A7 and lower annular magnet A11. The clamping force on the superhydrophobic porous PVDF membranes can be adjusted by adjusting the distance between the magnets. The oil esterification reaction liquid separation and purification device is fixed by the support frame 1.
[0035] The preparation method of the superhydrophobic porous PVDF membrane in this invention is not limited. The following is one preparation method, and the specific process is as follows:
[0036] 1) Mix PVDF:N-methyl-2-pyrrolidone = 0.5g:9.5mL and stir magnetically at 1500rpm for 120min until the liquid is clear and transparent;
[0037] 2) Add 0.5 mL / 10 mL of ammonia water to 1) and stir magnetically at 1500 rpm for 6 hours until the liquid becomes clear;
[0038] 3) Cast the solution prepared in 2) onto the PTFE concave template (size: area 5cm×5cm, thickness 2mm), and immerse the whole in a 60℃ water bath for 30min to complete the phase transformation;
[0039] 4) Demolding and drying. After the PVDF membrane has completed the phase transition, it is peeled off from the PTFE template. Excess moisture inside the PVDF membrane is absorbed by absorbent paper. The PVDF membrane is then transferred to an oven and dried at 60°C for 4 hours to obtain a superhydrophobic porous PVDF membrane with a water static contact angle greater than 150°.
[0040] Example 1
[0041] In this embodiment, further reference is made to Figure 1 After the acidic methyl ester esterification reaction solution is introduced into the oil inlet chamber 5, due to the physicochemical properties of the solution, the oil phase will automatically separate into two layers by gravity after standing still for a period of time in the oil inlet chamber 5. The upper layer is phase A, and the lower layer is phase B. A small amount of phase A liquid components will remain in phase B. After phase B passes through the first and second separation chambers 6 and 15, the first and second superhydrophobic porous PVDF membranes 9 and 18 selectively filter the phase B liquid. The phase B liquid passes through the first and second superhydrophobic porous PVDF membranes 9 and 18 and enters the first and second oil collection tanks 12 and 21 along the inner walls of the first and second oil outlet chambers 13 and 14. At this time, phase B liquid does not contain phase A liquid components and is named phase C. Phase A is discharged through valve 4 at the oil outlet and enters the external collection tank for circulation and purification.
[0042] Phase A contains a large amount of methanol and a small amount of water, while Phase B is mostly mixed fatty acid methyl esters and contains a small amount of methanol and water.
[0043] This device, along with the selective permeability of the superhydrophobic porous PVDF membrane to the components of the oil-ester reaction solution, enables the efficient separation and purification of mixed fatty acid methyl esters in the acidic oil methyl esterification reaction solution. Testing revealed... Figure 2 For the comparison of Fourier transform infrared (FTIR) spectra of liquids with different components, curve a is a methanol solution with a purity of 99.9%, curve b is the upper layer liquid (phase A) taken after the acidic oil methyl esterification reaction solution has been allowed to stand and separate into layers, curve c is the lower layer liquid (phase B) taken after the acidic oil methyl esterification reaction solution has been allowed to stand and separate into layers, curve d is the liquid (phase C) taken after the acidic oil methyl esterification reaction solution has been separated using a superhydrophobic porous PVDF membrane, and curve e is a mixed fatty acid methyl ester with a purity of 99.9%. Characteristic peak (1) is a special peak of alcohol functional group, characteristic peaks (2) and (3) are characteristic peaks of mixed fatty acid methyl ester functional group, and characteristic peak (4) is a characteristic peak of water. Comparative analysis shows that after separating the acidic oil methyl esterification reaction solution using a superhydrophobic porous PVDF membrane (curve d), it was found that the characteristic functional groups (1) and (4) of alcohol and water were not present in curve d, and the characteristic peaks and peak intensities of curve d and curve e were almost identical. This means that the acidic oil methyl esterification reaction solution (C phase liquid) separated by the superhydrophobic porous PVDF membrane contains no other components besides mixed fatty acid methyl esters.
[0044] The above results demonstrate that the selective permeability of superhydrophobic porous PVDF membranes can be used to successfully separate and purify mixed fatty acid methyl esters from acidic oil methyl esterification reactions.
[0045] The superhydrophobic porous PVDF membranes 9 and 18 are cut into circles with a diameter of 3 cm.
[0046] Although the present invention has been described above in conjunction with the accompanying drawings, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many modifications under the guidance of the present invention without departing from the spirit of the present invention, and these modifications are all within the protection scope of the present invention.
Claims
1. A continuous separation and purification device for oil methyl esterification reaction solution based on a superhydrophobic PVDF membrane, characterized in that, The continuous separation and purification device for oil esterification reaction liquid includes an oil inlet chamber, a separation pipeline, two identical superhydrophobic porous PVDF membrane-fixing components, and two oil collection tanks; the oil esterification reaction liquid separation and purification device is fixed by a support frame; The oil inlet chamber is an inverted T-shaped structure, which is used to fill the oil methyl esterification reaction liquid. It includes two parts: a vertical pipeline and a horizontal pipeline. The top of the vertical pipeline is connected to the oil inlet, and the side of the vertical pipeline has an oil outlet. A valve is installed on the oil outlet to control the outflow rate. The horizontal pipeline is open at both ends and is connected to the superhydrophobic porous PVDF membrane-fixation assembly through a separation pipeline. The separation pipeline is a hollow glass elbow, with two glass elbows connected to the first separation chamber and the second separation chamber respectively. The two separation chambers are symmetrically distributed, and the end of the separation chamber is an oil outlet chamber, which is connected to an oil collection tank for collecting the separated oil. The separation chamber is a hollow pipeline structure, with a superhydrophobic porous PVDF membrane-fixing assembly installed in its middle. The superhydrophobic porous PVDF membrane-fixing assembly consists of, from top to bottom, an upper annular magnet, an upper glass plate, a superhydrophobic porous PVDF membrane, a lower glass plate, and a lower annular magnet. The inner hole of the upper annular magnet is fitted onto the outer wall of the separation chamber and is in contact with the upper glass plate. The inner hole of the lower annular magnet is fitted onto the outer wall of the oil outlet chamber and is in contact with the lower glass plate. The superhydrophobic porous PVDF membrane is clamped by the mutual attraction between the upper and lower annular magnets. The superhydrophobic separation membrane, separation chamber, and oil outlet chamber are clamped together using magnetic suction. When the acidic oil methyl esterification reaction solution is poured into the oil inlet chamber, it automatically separates into two liquid layers by gravity: the upper layer is phase A, and the lower layer is phase B. To prevent excessive oil pressure from causing membrane failure, the upper liquid is discharged from the oil inlet chamber through the discharge port and circulated back into the separation chamber through an external pipeline for purification. The lower phase B, i.e., the mixed fatty acid methyl esters in the mixed methyl esterification reaction solution, is separated and purified by the superhydrophobic porous PVDF membrane in the separation chamber. Ultimately, continuous and rapid separation and purification of the acidic oil methyl esterification reaction solution is achieved.
2. The continuous separation and purification device for oil methyl esterification reaction solution based on a superhydrophobic PVDF membrane according to claim 1, characterized in that, The clamping force on the superhydrophobic porous PVDF membrane can be adjusted by changing the distance between the upper and lower annular magnets.