CN111330455A - MFI zeolite membrane for efficient dehydration of biological oil and preparation method and application thereof - Google Patents
MFI zeolite membrane for efficient dehydration of biological oil and preparation method and application thereof Download PDFInfo
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- CN111330455A CN111330455A CN202010105560.9A CN202010105560A CN111330455A CN 111330455 A CN111330455 A CN 111330455A CN 202010105560 A CN202010105560 A CN 202010105560A CN 111330455 A CN111330455 A CN 111330455A
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D71/00—Semi-permeable membranes for separation processes or apparatus characterised by the material; Manufacturing processes specially adapted therefor
- B01D71/02—Inorganic material
- B01D71/028—Molecular sieves
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D17/00—Separation of liquids, not provided for elsewhere, e.g. by thermal diffusion
- B01D17/08—Thickening liquid suspensions by filtration
- B01D17/085—Thickening liquid suspensions by filtration with membranes
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D61/00—Processes of separation using semi-permeable membranes, e.g. dialysis, osmosis or ultrafiltration; Apparatus, accessories or auxiliary operations specially adapted therefor
- B01D61/36—Pervaporation; Membrane distillation; Liquid permeation
- B01D61/362—Pervaporation
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D67/00—Processes specially adapted for manufacturing semi-permeable membranes for separation processes or apparatus
- B01D67/0039—Inorganic membrane manufacture
- B01D67/0051—Inorganic membrane manufacture by controlled crystallisation, e,.g. hydrothermal growth
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01D—SEPARATION
- B01D69/00—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor
- B01D69/02—Semi-permeable membranes for separation processes or apparatus characterised by their form, structure or properties; Manufacturing processes specially adapted therefor characterised by their properties
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Abstract
The invention discloses an MFI zeolite membrane for efficient dehydration of biological oil and a preparation method and application thereof. The method comprises the steps of firstly depositing a layer of continuous MFI molecular sieve seed crystals on a carrier, and then carrying out secondary growth on the seed crystals in a synthetic solution without adding a template agent to obtain the MFI zeolite membrane. The structure of the MFI zeolite membrane transmission pore channel can be effectively changed by adjusting the synthesis parameters of the zeolite membrane, so that the MFI zeolite membrane with the high-efficiency biological oil dehydration and separation performance can be synthesized. The MFI zeolite membrane prepared by the method can effectively solve the serious influence of membrane pollution on the membrane separation performance in the biological oil permeation, vaporization and dehydration process, so that the MFI zeolite membrane always keeps high flux, high selectivity and high stability in the separation process. The MFI zeolite membrane has good application prospect in the practical application of biological oil dehydration and separation.
Description
Technical Field
The invention belongs to the technical field of chemical separation, and particularly relates to an MFI zeolite membrane for efficient dehydration of bio-oil, and a preparation method and application thereof.
Background
With the rapid consumption of traditional fossil resources, the development of green and environment-friendly renewable energy sources has become a research hotspot in the field of energy science, and especially, the conversion of biomass raw materials with huge reserves and renewable into high-performance liquid fuels has received unprecedented attention. Among them, bio-oil obtained by simply thermally cracking biomass at high temperature is one of the most promising bio-based liquid fuels to be widely used in the future. The wide use of the liquid fuel can not only relieve the over dependence on fossil fuel, but also realize the high-valued utilization of agricultural and forestry wastes, and has important economic value and social benefit. However, the bio-oil directly prepared contains a large amount of water, which results in a low calorific value of the bio-oil. Therefore, the development of a separation technology for efficiently dehydrating the bio-oil is of great significance for effectively improving the quality of the bio-oil and developing related high-performance bio-based liquid fuels.
The zeolite molecular sieve is a porous material with uniform pore structure and good chemical stability and hydrothermal stability, and the properties of the zeolite molecular sieve enable the zeolite membrane to have good application prospects in organic matter dehydration separation application, and various zeolite membranes are successfully put to practical industrial application. Currently, the application of zeolite membranes in the dehydration separation of organic substances is mainly focused on simple binary systems, but the application in complex multi-component systems is relatively less, mainly because the zeolite membranes are easily affected by membrane fouling in the complex multi-component systems, thereby causing the permeation flux to be reduced sharply. Bio-oils are a complex mixture of substances including water, acids, alcohols, aldehydes, ketones, esters, phenols, organic oligomers, and the like. Researches report that the zeolite membrane is rapidly blocked after organic molecules are adsorbed in the pore channels of the zeolite membrane in a bio-oil system, so that the zeolite membrane is seriously polluted in the pervaporation dehydration separation force, and the permeation flux of the membrane is sharply reduced. The above membrane fouling problem has severely hindered the effective use of zeolite membranes in the separation of bio-oil by dehydration.
Research shows that after the zeolite membrane is polluted in the biological oil, water molecules in the system are mainly permeated through intercrystalline pores in the membrane. Therefore, the influence of membrane pollution on the membrane separation performance can be effectively reduced by reasonably regulating and controlling the number and the size of intercrystalline pores, so that the zeolite membrane is ensured to always keep excellent separation performance in the dehydration separation of the bio-oil.
Disclosure of Invention
In order to solve the problem that flux is sharply reduced due to membrane pollution in the biological oil dehydration separation of the zeolite membrane, the invention provides the MFI zeolite membrane oriented to the biological oil high-efficiency dehydration and the preparation method and the application thereof.
The technical scheme of the invention is as follows.
A preparation method of an MFI zeolite membrane for efficient dehydration of bio-oil comprises the following steps:
(1) preparing a seed crystal synthesis liquid precursor, and synthesizing seed crystals by a hydrothermal crystallization method;
(2) after the carrier is pretreated, uniformly depositing the seed crystals synthesized in the step (1) on the surface of the carrier;
(3) preparing a synthetic liquid precursor of the MFI zeolite membrane, and synthesizing the MFI zeolite membrane on the surface of the carrier obtained in the step (2) by a hydrothermal crystallization method.
Preferably, the seed crystal synthesis liquid precursor in the step (1) is prepared from a silicon source, an aluminum source, a template agent and water; the silicon source is one of tetraethoxysilane, silica sol, white carbon black and sodium silicate, the aluminum source is one of aluminum sulfate, sodium metaaluminate, aluminum chloride and aluminum isopropoxide, and the template agent is tetrapropylammonium hydroxide (TPAOH).
Preferably, SiO in the seed crystal synthesis liquid precursor2： Al2O3： TPAOH： H2The molar ratio of O is 1: (0-0.035): (0.1-0.2): (30-100).
Preferably, the temperature of the hydrothermal crystallization method in the step (1) is 100-200 ℃.
Preferably, the hydrothermal crystallization time in the step (1) is 8-48 h.
Preferably, the support material in step (2) is porous alumina, stainless steel, zirconia or titania.
Preferably, the shape of the support in step (2) may be a flat plate, a tube or a hollow fiber.
Preferably, the seed crystal deposition mode in the step (2) is vacuum filtration, dip coating or suspension coating.
Preferably, the precursor of the synthesis solution of the MFI zeolite membrane in step (3) is prepared from a silicon source, an aluminum source, NaOH, NaF, and water. The silicon source is one of tetraethoxysilane, silica sol, white carbon black and sodium silicate, and the aluminum source is one of aluminum sulfate, sodium metaaluminate, aluminum chloride and aluminum isopropoxide.
Preferably, SiO in the precursor of the MFI zeolite membrane synthesis solution in the step (3)2： Al2O3： Na2O ： NaF：H2The molar ratio of O is 1: (0-0.05): (0.1-0.5): (0.5-2.5): (20 to 500)
Preferably, the hydrothermal crystallization temperature in the step (3) is 100-200 ℃, and the hydrothermal crystallization time is 8-24 h.
An MFI zeolite membrane prepared by the above-described preparation method.
The application of the MFI zeolite membrane in the biological oil dehydration comprises the following steps:
sealing the MFI zeolite membrane, and dehydrating and separating the bio-oil by pervaporation.
Preferably, the separated bio-oil is prepared by rapid thermal cracking in an oxygen-free state, and has a water content of 1-40 wt% and a pH of 1-7. The pervaporation temperature is 10-90 ℃, and the pressures of the membrane feed side and the permeation side are respectively normal pressure and 0 MPa.
Compared with the prior art, the invention has the following beneficial effects:
the invention can keep the zeolite membrane with higher permeation flux and stability on the premise of ensuring the MFI zeolite membrane to have higher selectivity by reasonably regulating and controlling the size and the number of intercrystalline pores in the zeolite membrane, and well solves the problem that the permeation flux of the MFI zeolite membrane is rapidly reduced due to membrane pollution in a biological oil multi-component system. The MFI zeolite membrane has good application prospect in the actual industrial application of biological oil dehydration.
Detailed Description
The present invention is further specifically described below with reference to specific examples, but the scope of the present invention is not limited thereto.
Example 1
Firstly, 9 ml of tetrapropylammonium hydroxide (TPAOH, 25 wt.%), 19.2 ml of tetraethoxysilane (TEOS, 98 wt.%) and 60 ml of deionized water are mixed and stirred at room temperature for 18 h, then 0.46 g of sodium aluminate is fully dissolved in 10ml of deionized water, the solution is slowly dropped and stirred at room temperature for 4 h, finally the synthetic solution is filled into a reaction kettle and reacts in an oven at 180 ℃ for 24 h, the synthetic molecular sieve is washed by deionized water for 3 times to prepare 1 wt.% seed crystal suspension, and seed crystals are deposited to α -Al by a dip-coating method2O3And (3) drying the outer surface of the tube at room temperature, and then roasting the tube in a muffle furnace at 550 ℃ for 6h to obtain the seed crystal layer.
1.2 g of sodium hydroxide, 22.2 g of silica gel (SiO)240 wt.%) and 65 ml of deionized water and stirred at room temperature for 18 h; then, 2.5 g of aluminum sulfate octadecahydrate is fully dissolved in 15 ml of deionized water and slowly dropped into the solution, the solution is stirred for 15 min at normal temperature, 25.5 ml of aqueous solution containing 18 wt.% of NaF is added, and the mixed solution is stirred for 3 h at room temperature; finally, sealing two ends of the alumina tube coated with the seed crystal, vertically placing the alumina tube into a reaction kettle, adding the precursor synthetic liquid, and placing the reaction kettleThe mixture is put into an oven at 180 ℃ for reaction for 24 hours. After the reaction was complete, the zeolite membrane was removed and washed 3 times with deionized water and placed in an oven to dry overnight at 60 ℃.
The synthetic MFI zeolite membrane was used for pervaporation dehydration separation (30 ℃) of bio-oil (water content 40 wt.%, pH = 2), with a permeate flux and permeate side water content of 0.44 kg m, respectively-2h-1And 98 wt.%. The separation process is continuously carried out for 10 hours, the permeation flux of the MFI zeolite membrane is gradually reduced, and the permeation flux and the water content on the permeation side in the 10 th hour are respectively 0.04 kg m-2h-1And 98 wt.%.
Example 2
The pervaporation temperature of the MFI zeolite membrane used in example 1 for bio-oil (water content 40 wt.%, pH = 2) was increased by 70 ℃ from 30 ℃, and the permeation flux and permeate side water content of the MFI zeolite membrane were 0.18 kg m-2h-1And 99 wt.%. After the separation process was continued for 10 hours, the permeation flux and the water content on the permeation side were 0.19 kg m, respectively-2h-1And 99 wt.%, the separation performance of the membrane remains stable.
Example 3
The synthesis time of the MFI zeolite membrane was reduced from 24 h in example 1 to 20 h, and the other synthesis conditions remained the same as in example 1. The synthetic MFI zeolite membrane was used for pervaporation dehydration separation (70 ℃) of bio-oil (water content 40 wt.%, pH = 2), with a permeate flux and permeate side water content of 1.87 kg m, respectively-2h-1And 98 wt.%. After the separation process is continuously carried out for 10 hours, the permeation flux and the water content on the permeation side of the MFI zeolite membrane are respectively 1.84 kg m-2h-1And 98wt.%, the separation performance of the membrane remains stable.
Example 4
The synthesis time of the MFI zeolite membrane was reduced from 24 h to 16 h in example 1, and the other synthesis conditions remained the same as in example 1. The synthetic MFI zeolite membrane was used for pervaporation dehydration separation (70 ℃) of bio-oil (water content 40 wt.%, pH = 2), with a permeate flux and permeate side water content of 2.69 kg m, respectively-2h-1And 93 wt.%. After the separation process is continuously carried out for 10 hours, the permeation flux and permeation of the MFI zeolite membraneThe side water content was 2.70 kg m, respectively-2h-1And 93 wt.%, the separation performance of the membrane remained stable.
Claims (10)
1. A preparation method of an MFI zeolite membrane for efficient dehydration of bio-oil is characterized by comprising the following steps:
(1) preparing a seed crystal synthesis liquid precursor, and synthesizing seed crystals by a hydrothermal crystallization method;
(2) after the carrier is pretreated, uniformly depositing the seed crystals synthesized in the step (1) on the surface of the carrier;
(3) preparing a synthetic liquid precursor of the MFI zeolite membrane, and synthesizing the MFI zeolite membrane on the surface of the carrier obtained in the step (2) by a hydrothermal crystallization method.
2. The method according to claim 1, wherein the seed crystal synthesis solution precursor in step (1) is prepared from a silicon source, an aluminum source, a template agent and water; the silicon source is one of ethyl orthosilicate, silica sol, white carbon black and sodium silicate; the aluminum source is one of aluminum sulfate, sodium metaaluminate, aluminum chloride and aluminum isopropoxide; the template agent is tetrapropylammonium hydroxide.
3. The method according to claim 2, wherein the SiO in the seed synthesis liquid precursor2：Al2O3: tetrapropylammonium hydroxide: h2The molar ratio of O is 1: (0-0.035): (0.1-0.2): (30-100).
4. The preparation method according to claim 1, wherein the temperature of the hydrothermal crystallization in the step (1) is 100 to 200 ℃; the hydrothermal crystallization time is 8-48 h.
5. The production method according to claim 1, wherein the support of step (2) is porous alumina, stainless steel, zirconia or titania; the carrier is in the shape of a flat plate, a tube or a hollow fiber; the deposition mode is vacuum filtration, dip coating or suspension coating.
6. The preparation method according to claim 1, wherein the synthesis solution precursor of the MFI zeolite membrane in step (3) is prepared from a silicon source, an aluminum source, NaOH, NaF, and water; the silicon source is one of ethyl orthosilicate, silica sol, white carbon black and sodium silicate; the aluminum source is one of aluminum sulfate, sodium metaaluminate, aluminum chloride and aluminum isopropoxide.
7. The preparation method according to claim 6, wherein SiO in the precursor of the MFI zeolite membrane synthesis solution2：Al2O3： Na2O ： NaF： H2The molar ratio of O is 1: (0-0.05): (0.1-0.5): (0.5-2.5): (20-500).
8. The preparation method according to claim 1, wherein the hydrothermal crystallization temperature of the synthetic zeolite membrane in the step (3) is 100 to 200 ℃; the hydrothermal crystallization time is 8-24 h.
9. An MFI zeolite membrane obtained by the production method as claimed in any one of claims 1 to 8.
10. The use of an MFI zeolite membrane in the dehydration of bio-oil as claimed in claim 9, comprising the steps of:
sealing the MFI zeolite membrane, and dehydrating and separating the bio-oil by pervaporation;
the bio-oil is prepared by rapid thermal cracking in an anaerobic state, the water content of the bio-oil is 1-40 wt%, and the pH value is 1-7; the temperature of pervaporation is 10-90 ℃, and the pressures of the membrane feed side and the permeation side are respectively normal pressure and 0 MPa.
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| CN115036547A (en) * | 2022-05-06 | 2022-09-09 | 黄山学院 | Preparation method of ion-conducting membrane for all-vanadium redox flow battery |
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| CN115036547A (en) * | 2022-05-06 | 2022-09-09 | 黄山学院 | Preparation method of ion-conducting membrane for all-vanadium redox flow battery |
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