CN107970781B - A kind of molecular sieve ceramic membrane material for olefin purification and its preparation and application - Google Patents

Abstract

The invention relates to molecular sieve ceramic membrane materials for olefin purification and preparation and application thereof, wherein the particle size of molecular sieve particles loaded on the surface of a ceramic material in the molecular sieve ceramic membrane materials is 0.1-3 mu m, the thickness of a molecular sieve layer is 3-5 mu m, the molecular sieve ceramic membrane materials are prepared by ceramic material pretreatment, molecular sieve seed crystal precoating and closed crystallization in sequence, and the molecular sieve ceramic membrane materials are used for removing polar oxygen-containing compounds in gaseous olefin flow to below 1 ppm.

Description

A kind of molecular sieve ceramic membrane material for olefin purification and its preparation and application

technical field

The invention belongs to the technical field of inorganic membrane materials, and relates to a molecular sieve ceramic membrane material for olefin purification and its preparation and application.

Background technique

The polyolefin industry is the backbone of the petrochemical industry and occupies an important strategic position in the country. As a key prerequisite for olefin polymerization, the deep purification technology of polymer-grade olefins has a huge impact on the quality and output of polyolefin products, as well as the future development of the downstream plastics industry. With the replacement of olefin polymerization catalysts, the catalysts have higher and higher requirements for the purity of raw materials such as ethylene, propylene and butene. At present, the production technologies of olefins mainly include: steam cracking, catalytic cracking, catalytic dehydrogenation, methanol to olefins (MTO), methanol to propylene (MTP), etc. Whether it is the traditional cracking method or the new MTO and MTP processes, the olefin raw materials prepared contain various impurities, such as H ₂ O, O ₂ , CO, CO ₂ , methanol, dimethyl ether, propionaldehyde, acetone , carbonyl sulfide, etc. In particular, the presence of traces of methanol, dimethyl ether, propionaldehyde and other polar oxygen-containing compound impurities not only seriously affects the activity of polyolefin catalysts, but even causes the entire plant to stop production due to catalyst poisoning, resulting in significant economic losses.

At present, in the deep purification of polar oxygen-containing compounds in olefin streams, the widely used process technology is to adsorb and remove trace amounts of polar oxygen-containing compounds such as methanol, dimethyl ether, and propionaldehyde in the olefin stream through particulate adsorbents. impurities. However, this method has disadvantages such as large mass transfer resistance, small contact area, and large loss when deeply removing polar oxygen-containing impurities, especially for the regeneration and activation of granular adsorbents, which requires huge energy consumption, and does not require a large amount of energy. It is conducive to energy saving and emission reduction, and greatly increases the operating cost.

Therefore, there is an urgent need to develop a new type of adsorbent for the purification of polar oxygen-containing compounds such as methanol, dimethyl ether, and propionaldehyde.

Membrane adsorption and separation technology is widely used in chemical, food, medicine, environmental protection, metallurgy and other industrial fields due to its advantages of high precision, low energy consumption, less pollution, and easy realization of continuous separation. As a new type of inorganic membrane developed in the past ten years, molecular sieve ceramic membrane not only has the advantages of high temperature resistance, corrosion resistance, high mechanical strength, low mass transfer resistance, large flux, etc., but also has a uniform and adjustable pore structure. and structural properties, suitable for applications in pervaporation and gas separation. At present, the existing molecular sieve ceramic membranes mainly include LTA type, FAU type, T type, MFI type, MOR type and other membranes. The main synthesis methods are: in situ hydrothermal synthesis, secondary growth, microwave synthesis and chemical Gas phase migration method. Among them, the most widely used is the secondary growth method.

The U.S. Patent Publication No. US4699892A synthesized an A-type molecular sieve layer on the surface of the porous carrier. When the molar content of methane, ethane and propane was 33%, it showed good permeation separation performance, and the permeated gas molar composition was: Methane 73.5%, ethane 26%, propane 0.5%. Silicalite-1 zeolite was synthesized by coating gel on porous α-Al ₂ O ₃ ceramic surface in US Patent Publication No. US5464798A and then crystallizing 2-3 times in a crystallization solution containing silica gel, NaOH and TPABr Molecular sieve ceramic membrane, the molecular sieve ceramic membrane significantly reduces the gas permeation flux, which is 3-14% of the original base membrane, ₅ times lower _N2 permeability, 190 times lower nC ₄ H10, and 1000 times lower isobutane. Isobutane is obviously adsorbed on the membrane, and the separation coefficient of normal and isobutane mixture can reach 22. Japanese Patent Publication No. JP08257301A under the condition that the molar composition is H ₂ O/SiO ₂ =50-120, Na ₂ O/SiO ₂ =0.5-2, SiO ₂ /Al ₂ O ₃ =5-15, in the tubular shape A Y-type molecular sieve membrane was synthesized on the porous support carrier. When used as a pervaporation membrane, the molecular sieve membrane had excellent separation performance for alcohol-water and alcohol-cyclohexane organic mixed systems. The Chinese invention patent with application publication number CN104548956A discloses a method of combining multiple dips and pulling pre-coating seeds with high-temperature crystallization, and different silicon-alumina are synthesized on the surface of the porous α-Al ₂ O ₃ support. Compared with the high separation performance of NaA molecular sieve membrane, the membrane has excellent separation performance for isopropanol-water system. European Patent Publication No. EP674939A2 discloses a method for synthesizing ZSM-5 molecular sieve membrane on porous α-Al ₂ O ₃ ceramic carrier, and the prepared ZSM-5/α-Al ₂ O ₃ ceramic membrane is resistant to airborne CO ₂ has excellent separation effect, _αCO2/N2 can reach 53-56, and CO ₂ permeation rate can reach 1.7×10 ^-7 mol/(m ² ·S·Pa). In addition, Liang Zhou et al. synthesized SAPO-34 molecular sieve membrane on the surface of porous α-Al ₂ O ₃ ceramic carrier by steam-assisted conversion technology. The ceramic membrane has good permeability to H ₂ at room temperature, and its permeation rate reached 6.96 ×10 ^-6 mol/(m ² ·S·Pa), for H ₂ /CO ₂ , H ₂ /N ₂ , H ₂ /CH ₄ , H ₂ /C ₂ H ₆ , H ₂ /C ₃ H ₈ , The separation coefficients of H ₂ /nC ₄ H ₁₀ and H ₂ /iC ₄ H ₁₀ are 1.83, 7.58, 14.80, 18.24, 26.51, 40.15 and 53.02, respectively (see Liang Zhou. Highly H ₂ permeable SAPO-34 membranes by steam-assisted conversion). seeding[J]. International journal of hydrogen energy, 2014, 39:14949-14954).

However, the techniques disclosed in the aforementioned patents and literature cannot be used for the deep purification of polar oxygenates in olefin streams. Therefore, it is a huge technical problem to synthesize a dense and compact molecular sieve ceramic membrane material with uniform thickness, no cracks, no pores on the surface, high bonding strength and not easy to fall off for the deep purification of polar oxygen-containing compounds in olefin streams.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a molecular sieve ceramic membrane material for olefin purification and its preparation and application in order to overcome the above-mentioned defects of the prior art.

The object of the present invention can be realized through the following technical solutions:

A preparation method of a molecular sieve ceramic membrane material for olefin purification, the method comprising the following steps:

1) Ceramic material pretreatment: the ceramic material is calcined at 200-800 ℃ for 0.1-12 hours, then cooled, polished, cleaned and dried, and then the ceramic material is placed in a surface modifier solution at 10-150 ℃ Soak for 5min-36h, then take out and dry to obtain the pretreated ceramic material;

2) Molecular sieve seed crystal pre-coating: prepare a molecular sieve seed crystal liquid, and use a vacuum filtration process to coat the surface of the pretreated ceramic material with molecular sieve crystal seeds, and then dry to obtain a ceramic material coated with molecular sieve seeds;

3) Hermetic crystallization: The ceramic material coated with molecular sieve seeds is placed in the molecular sieve seed liquid, then aged at 20-80°C for 2-48h, and then crystallized at 60-140°C for 4-60h , the molecular sieve ceramic membrane material is obtained after drying.

A molecular sieve ceramic membrane material for olefin purification can be prepared by coating molecular sieve seeds on the surface pretreated ceramic material, and then through a closed crystallization process.

As a preferred technical solution, in step 1), in the roasting process, the roasting temperature is 200-600° C., and the roasting time is 1-6h.

Further, in step 1), sanding is performed with 100-2500 mesh sandpaper.

As a preferred technical solution, sand with 800-1500 mesh sandpaper.

As a preferred technical solution, in step 1), the cleaning method is ultrasonic cleaning with deionized water.

Further, in step 1), the surface modifier solution is composed of a surface modifier and an organic solvent, and the surface modifier includes polydopamine, aminopropyltriethoxysilane, chitosan or One or more of hydroxymethyl cellulose, and the organic solvent includes one or both of toluene or TRIS-HCl buffer.

As a preferred technical solution, the surface modifier is polydopamine or aminopropyltriethoxysilane.

When the surface modifier is polydopamine, the pretreatment process of the ceramic material is as follows: prepare a polydopamine solution according to the ratio of 2-8mL polydopamine (2mg/L)/40-100mL TRIS-HCl, and then mix the ceramic material under continuous stirring. Place in polydopamine solution, soak for 10-24h at 25-40°C, and dry for later use.

When the surface modifier is aminopropyltriethoxysilane, the pretreatment process of the ceramic material is as follows: prepare a silane solution according to the ratio of 120-460mg aminopropyltriethoxysilane/5-20mL toluene, and then mix the ceramic material Place in silane solution, carry out high pressure airtight treatment at 80-120°C and 0.01-3Mpa for 30min-3h, dry and cool for later use.

As a preferred technical solution, in step 1), in the soaking treatment process, the soaking temperature is 25-120°C, and the soaking time is 30min-24h.

Further, in step 1), the ceramic material includes one or more of porous alumina, porous mullite, porous zirconia, porous titanium oxide or porous silicon oxide, and the ceramic material is in the form of porous alumina, porous mullite, porous zirconia, porous titanium oxide or porous silica. Tubular, sheet, lamellar helical or annular. The molecular sieve ceramic membrane material uses a porous inorganic ceramic material as a support.

When the ceramic material is porous alumina, α-Al ₂ O ₃ , γ-Al ₂ O ₃ , δ-Al ₂ O ₃ or η-Al ₂ O ₃ can be selected, and the average pore size of the porous alumina is 0.1-5 μm , the porosity is 20-80%.

As a preferred technical solution, the ceramic material is tubular.

Further, in step 2), the molecular sieve seed liquid is a molecular sieve seed liquid sol, and the preparation method of the molecular sieve seed liquid sol is: the aluminum source, the silicon source, the sodium hydroxide, and the deionized water are prepared according to n ( Al):n(Si):n(Na):n(H ₂ O)=2:3-25:2-60:300-1320 After weighing respectively, first add aluminum source and sodium hydroxide to a part of In ionized water, stir to completely dissolve the aluminum source to obtain solution A; then add the silicon source to another part of deionized water, stir to dissolve the silicon source completely to obtain solution B, and then add solution B dropwise to solution A under stirring , and stirred at room temperature for 0.5-6h, and then allowed to stand for aging for 20-28h. Before the preparation of the molecular sieve seed crystal sol, deionized water is firstly divided into two parts, which are used as the solvent of the A solution and the B solution respectively.

The pretreated ceramic material is sol-coated with molecular sieve seed solution.

Molecular sieves are preferably LTA type (NaA), FAU type (NaX, NaY, EMT), T type, MFI type or MOR type, more preferably FAU type molecular sieves such as NaX, NaY or EMT.

When the molecular sieve is X type, the ratio of aluminum source, silicon source, sodium hydroxide and deionized water is n(Al):n(Si):n(Na):n(H ₂ O)=2:(3 -7):(6-20):(300-600); When the molecular sieve is Y type, the ratio of aluminum source, silicon source, sodium hydroxide and deionized water is n(Al):n(Si): n(Na):n( _H2O )=2:(12-30):(10-50):(120-480).

Further, the aluminum source includes one or more of aluminum hydroxide, hydrated aluminum oxide, sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum phosphate or bauxite, and the silicon source includes One or more of solid silica gel, solid sodium silicate, water glass, silica sol, tetraethyl silicate or silica.

As a preferred technical solution, the aluminum source is aluminum hydroxide, sodium aluminate or aluminum isopropoxide, and the silicon source is solid sodium silicate or water glass.

Further, when the ceramic material is in a tubular shape, in step 2), the method for coating the surface of the pretreated ceramic material with molecular sieve crystal seeds is: stirring the molecular sieve seed crystal liquid evenly, and then adding one end of the tubular ceramic material. Block, connect the vacuum pump at the other end, and then immerse the tubular ceramic material vertically in the molecular sieve seed liquid, maintain the vacuum degree in the tubular ceramic material at 0.0001-0.01MPa, and perform suction filtration for 5s-30 min, and then remove the tubular ceramic material from the molecular sieve seed crystal. Take it out of the liquid and place it in an oven at 25-65°C for 2-48h.

As a preferred technical solution, the vacuum degree in the tubular ceramic material is maintained at 0.0001-0.01MPa, and the suction filtration is performed for 5s-5min.

As a preferred technical solution, in step 3), the ageing temperature is 40-70°C, the ageing time is 4-12h, the crystallization temperature is 80-120°C, the crystallization time is 4-24h, and the number of crystallization reactions is 1-6 times.

As a preferred technical solution, the crystallization process is carried out in a homogeneous reactor, and during crystallization, the rotational speed of the stirrer is 10-200 r/min.

A molecular sieve ceramic membrane material for olefin purification, which is prepared by the method.

Further, in the molecular sieve ceramic membrane material, the particle size of the molecular sieve particles supported on the surface of the ceramic material is 0.1-3 μm, and the thickness of the molecular sieve layer is 3-5 μm. The molecular sieve ceramic membrane is the outer molecular sieve membrane, and the molecular sieve layer is continuous and uniform. The molecular sieve ceramic membrane material not only has strong mechanical strength (tensile strength 120-200MPa), large specific surface area (500-800m ² /g), but also the molecular sieve layer thickness is uniform, dense and uniform, and there are no cracks in the longitudinal and transverse directions. No pores on the surface, high bonding strength, not easy to fall off.

An application of a molecular sieve ceramic membrane material for removing polar oxygen-containing compounds in a gaseous olefin stream to less than 1 ppm. Molecular sieve ceramic membrane material has excellent deep purification function, which can remove traces of methanol, dimethyl ether, propionaldehyde, acetone, carbonyl sulfide and other polar oxygen-containing compounds impurities in gaseous olefin streams such as ethylene or propylene to less than 1ppm. The molecular sieve ceramic membrane material has smaller mass transfer resistance and lower energy consumption than the existing polar oxygen-containing compound impurity purification adsorbents when deeply purifying polar oxygen-containing compound impurities.

The method of using the molecular sieve ceramic membrane material is as follows: install the molecular sieve ceramic membrane material in the membrane module, and then let the olefin flow pass through the molecular sieve ceramic membrane material, and the olefin flow from which impurities have been removed passes through the membrane and then permeates from the other side of the membrane.

The activation and regeneration method of the molecular sieve ceramic membrane material is as follows: firstly at 60-150 ℃ with nitrogen hot blowing for 1-8h, and then at 160-220 ℃ with nitrogen hot blowing for 0.5-10h.

In the present invention, the ceramic material after high temperature roasting and polishing is first soaked in a solution containing a surface modifier to obtain a pretreated ceramic material; then a sol coating process is used to coat the surface of the pretreated ceramic material. The molecular sieve seed crystal is covered; finally, the crystallization reaction is carried out under high temperature and airtight conditions, and the molecular sieve ceramic membrane material is prepared, and the molecular sieve ceramic membrane material can purify the polar oxygen-containing compound impurities. When the molecular sieve ceramic membrane material adsorbs the polar oxygen-containing compound impurities in the olefin stream, the purification depth is less than 1ppm, not only the mass transfer resistance is small, but also the energy consumption is low and the regeneration ability is strong. The molecular sieve ceramic membrane material can be widely used in deep removal of polar oxygen-containing compounds such as methanol, dimethyl ether, propionaldehyde, acetone, carbonyl sulfide and other impurities in gaseous olefin streams such as ethylene or propylene. Under the condition of severe fluctuation, it can deeply purify oxide-containing impurities, and greatly improve the disadvantage that the molecular sieve layer on the surface of the ceramic tube is easy to fall off during transportation.

The research shows that the non-uniform coating of the seed crystals, the oversized crystallites and the electrostatic repulsion between the negatively charged ions in the seed crystal liquid and the surface of the ceramic support are the main reasons for the inability to synthesize ideal molecular sieve ceramic membrane materials. In the present invention, a suitable surface modifier is selected to perform surface modification on the ceramic support in advance, and an ideal molecular sieve ceramic membrane material is finally prepared. The molecular sieve ceramic membrane material can replace the existing particulate adsorbent for deep purification of polar oxygen-containing compounds in the existing olefin stream.

The invention combines surface chemical modification and physical coating process to synthesize a molecular sieve ceramic membrane material that is dense and compact, has uniform thickness, no cracks, no pores on the surface, high bonding strength, and is not easy to fall off. The molecular sieve ceramic membrane material has excellent properties. High rigidity and mechanical strength, low mass transfer resistance, and high heat resistance, it also has deep and efficient removal accuracy, lower co-adsorption loss of olefins such as ethylene or propylene, and is more efficient than the existing polar oxygenate impurities. The purification adsorbent has smaller mass transfer resistance, lower energy consumption, and longer penetration time, which solves the shortcomings of the existing olefin deep purification process, such as large footprint and filling volume, high energy consumption and large investment. In addition, the molecular sieve ceramic membrane material also has lower regeneration temperature and strong regeneration and reuse performance.

Compared with the prior art, the present invention has the following characteristics:

1) Compared with the existing ceramic tube surface pretreatment technology, the surface modification technology adopted in the present invention not only optimizes the surface roughness of the ceramic tube, but also after being treated in a specially prepared surface modifier solution, the ceramic tube is Abundant amino and siloxy groups are formed on the surface, which improves the hydrophilicity and electronegativity of the surface of the ceramic tube;

2) The present invention adopts the method of combining surface chemical modification technology and sol suction filtration technology under vacuum to precoat seed crystals. Compared with the existing ceramic tube surface seed crystal coating technology, the existence of special groups of the present invention The surface properties of the ceramic tube are greatly improved, and it is more conducive to the formation of a compact and uniform thickness seed layer in the seed coating stage, which helps to form a molecular sieve layer with excellent structure and performance;

3) The molecular sieve ceramic membrane material prepared by the present invention not only has high mechanical strength, but also has dense and uniform molecular sieve loading on the surface of the ceramic tube, the average thickness reaches 3-5 μm, the molecular sieve particles are small, and the average particle size is 0.1-3 μm; The molecular sieve layer has no cracks in the longitudinal and lateral directions, no pores on the surface, high bonding strength, and is not easy to fall off, and the smaller molecular sieve particles enable the molecular sieve ceramic membrane to have a larger specific surface area, which is more conducive to the transmission of polar oxygen-containing compounds. mass and adsorption;

4) Compared with the existing technology for deep purification of polar oxygen-containing compound impurities in olefin streams, the molecular sieve ceramic membrane material prepared by the present invention not only meets the requirements of deep purification, but also has small filling volume, low mass transfer resistance and low consumption. , and the regeneration energy consumption is low when reused, and the reuse efficiency is high;

5) The preparation process of the molecular sieve ceramic membrane material is simple, the initial investment cost of the device is low, it is stable and reliable, and it is easy to realize industrialization.

Description of drawings

Fig. 1 is the XRD pattern of the molecular sieve ceramic membrane material prepared in Example 1;

Fig. 2 is the SEM spectrum of the molecular sieve ceramic membrane material prepared in Example 1, wherein a is the surface SEM image of the molecular sieve ceramic membrane, and b is the cross-sectional SEM image of the molecular sieve ceramic membrane;

Fig. 3 is the breakthrough curve diagram when the molecular sieve ceramic membrane material prepared in Example 1 is used for adsorbing polar oxygen-containing compounds;

FIG. 4 is a breakthrough curve diagram of the molecular sieve ceramic membrane material prepared in Example 2 when it is used to adsorb polar oxygen-containing compounds.

Detailed ways

The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented on the premise of the technical solution of the present invention, and provides a detailed implementation manner and a specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

Example 1:

Pretreatment of ceramic tube: The α-Al ₂ O ₃ ceramic tube with an average pore diameter of 2 μm and a porosity of 55% was placed in a muffle furnace at 200 °C for 1 h, and then cooled to room temperature naturally. The α-Al ₂ The surface of the _O3 ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 120 °C for 3 h, and cooled for later use. Soak the polished α-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 2mL polydopamine (2mg/L)/100mL TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 25°C for 10 h, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of :12:300 is mixed at room temperature. The specific method is: first dissolve sodium hydroxide in a part of deionized water, and then stir and dissolve aluminum hydroxide in sodium hydroxide solution under heating and boiling conditions, which is recorded as Solution A; then add sodium silicate to another part of deionized water, stir for 1 h to completely dissolve sodium silicate, and denote it as solution B. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred at room temperature for 0.5 h, left standing for aging at room temperature for 24 h, and then vigorously stirred to obtain a molecular sieve seed crystal liquid sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then vertically immerse the ceramic tube in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5s under the vacuum of 0.001MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the ends tightly with stoppers, and place it in a 35°C oven for pretreatment for 48 hours for later use.

Preparation of molecular sieve ceramic membrane material: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 40 °C for 12 h, then heated to 100 °C, 120 r/min for crystallization for 6 h, and the crystallization was repeated 3 times to obtain a 13X molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace of 200 °C for 2 h under nitrogen protection (heating rate of 1 °C/min), and cooled to room temperature naturally, and then tested, XRD and SEM test results As shown in Figure 1 and Figure 2, respectively.

The prepared molecular sieve ceramic membrane material was loaded into the membrane evaluation reactor and purged for 2h under the condition of high-purity nitrogen flow of about 100h-1GHSV. Then nitrogen gas (about 20×10 ^-6 (mol/mol) dimethyl ether DME, methanol METH, propionaldehyde PROP) was continuously fed at 20 mL/min at a pressure of 0.3 MPa, and the permeate gas through the molecular sieve ceramic membrane passed through The contents of dimethyl ether, methanol and propionaldehyde were detected online by hydrogen ion gas chromatography. The penetration curve is shown in Figure 3.

Example 2:

Pretreatment of the ceramic tube: The α-Al ₂ O ₃ ceramic tube with an average pore diameter of 0.1 μm and a porosity of 20% was calcined in a muffle furnace at 200 °C for 1 h, cooled to room temperature naturally, and the α-Al The surface of the ₂ O ₃ ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 120 °C for 3 h, and cooled for later use. Soak the polished α-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 2mL polydopamine (2mg/L)/40ml TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 25°C for 10 h, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of :12:300 is mixed at room temperature. The specific method is: first dissolve sodium hydroxide in a part of deionized water, and then stir and dissolve aluminum hydroxide in sodium hydroxide solution under heating and boiling conditions, which is recorded as Solution A; then add sodium silicate to another part of deionized water, stir for 1 h to completely dissolve sodium silicate, and denote it as solution B. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred at room temperature for 0.5 h, left standing for aging at room temperature for 24 h, and then vigorously stirred to obtain a molecular sieve seed crystal liquid sol.

Sol coating: plug one end of the ceramic tube, and connect the other end to a vacuum pump, then vertically immerse the ceramic tube in the above-mentioned molecular sieve seed crystal liquid sol, filter for 5s under the vacuum of 0.0001MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with stoppers, and place it in a 25°C oven for pretreatment for 48 hours for later use.

Preparation of molecular sieve ceramic membrane material: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 40°C for 12h, and then heated to 80°C and crystallized at 10r/min for 48h to obtain a 13X molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 200 °C for 2 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

The prepared molecular sieve ceramic membrane material was loaded into the membrane evaluation reactor and purged for 2h under the condition of high-purity nitrogen flow of about 100h-1GHSV. Then ethylene gas (about 20×10 ^-6 (mol/mol) dimethyl ether DME, methanol METH, propionaldehyde PROP) was continuously fed at 20 mL/min at a pressure of 0.3 MPa, and the permeate gas through the molecular sieve ceramic membrane passed through The contents of dimethyl ether, methanol and propionaldehyde were detected online by hydrogen ion gas chromatography. The penetration curve is shown in Figure 4.

Example 3:

Pretreatment of the ceramic tube: The α-Al ₂ O ₃ ceramic tube with an average pore diameter of 5 μm and a porosity of 80% was calcined in a muffle furnace at 200 ° C for 1 h, cooled to room temperature naturally, and the α-Al ₂ The surface of the _O3 ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 120 °C for 3 h, and cooled for later use. Soak the polished α-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 8mL polydopamine (2mg/L)/100ml TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 25°C for 24 hours, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of :50:300 is mixed at room temperature. The specific method is: first dissolve sodium hydroxide in a part of deionized water, and then stir and dissolve aluminum hydroxide in sodium hydroxide solution under heating and boiling conditions, which is recorded as Solution A; then add sodium silicate to another part of deionized water, stir for 1 h to completely dissolve sodium silicate, and denote it as solution B. Then, solution B was slowly added dropwise to solution A under strong stirring, continuously stirred for 1 hour at room temperature, left to stand for aging at room temperature for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then immerse the ceramic tube vertically in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5 minutes under the vacuum of 0.01 MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with stoppers, and place it in a 65°C oven for pretreatment for 24 hours for later use.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 40°C for 12h, and then heated to 110°C at 50 r/min for crystallization for 8h to obtain a Y-type molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 200 °C for 2 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 4:

Pretreatment of the ceramic tube: The β-Al ₂ O ₃ ceramic tube with an average pore diameter of 3 μm and a porosity of 50% was calcined in a muffle furnace at 200°C for 6 h, cooled to room temperature naturally, and the β-Al ₂ The surface of the _O3 ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 100 °C for 4 h, and cooled for later use. Soak the polished β-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 8mL polydopamine (2mg/L)/100ml TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 40°C for 24 hours, and finally dried for use.

The preparation of molecular sieve seed crystal liquid sol: aluminum hydroxide, sodium silicate, sodium hydroxide and deionized water are prepared according to n(Al):n(Si):n(Na):n(H ₂ O)==2: The material ratio of 4:16:400 is mixed at room temperature. The specific method is: first dissolve sodium hydroxide in a part of deionized water, and then stir and dissolve aluminum hydroxide in sodium hydroxide solution under heating and boiling conditions. It is solution A; then add sodium silicate to another part of deionized water, stir for 1 h to completely dissolve sodium silicate, and record it as solution B. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then vertically immerse the ceramic tube in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 30s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the ends tightly with stoppers, and place it in a 55°C oven for pretreatment for 6 hours for later use.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 70°C for 6 hours, and then heated to 120°C at 80 r/min for crystallization for 6 hours to obtain a 13X molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace of 180 °C for 3 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 5:

Pretreatment of ceramic tube: The γ-Al ₂ O ₃ ceramic tube with an average pore diameter of 3 μm and a porosity of 50% was calcined in a muffle furnace at 200 °C for 6 h, cooled to room temperature naturally, and the γ-Al ₂ The surface of the _O3 ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 100 °C for 4 h, and cooled for later use. Soak the polished γ-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 2mL polydopamine (2mg/L)/100ml TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 40°C for 24 hours, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of :60:800 is mixed at room temperature. The specific method is: first dissolve sodium hydroxide in a part of deionized water, and then stir and dissolve aluminum hydroxide in sodium hydroxide solution under heating and boiling conditions, which is recorded as Solution A; then add sodium silicate to another part of deionized water, stir for 1 h to completely dissolve sodium silicate, and denote it as solution B. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube, and connect the other end to a vacuum pump, then vertically immerse the ceramic tube in the above-mentioned molecular sieve seed liquid sol, and filter for 3 minutes under the vacuum of 0.01 MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the ends tightly with stoppers, and place it in a 65°C oven for pretreatment for 6 hours for later use.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 70°C for 6 hours, then the temperature was raised to 120°C, 120r/min for 6 hours of crystallization, and the crystallization was repeated 3 times to obtain the molecular sieve ceramic membrane material. Washed with deionized water and dried at room temperature, placed in a high-temperature atmosphere furnace at 220 °C for 1 h under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 6:

Pretreatment of the ceramic tube: The η-Al ₂ O ₃ ceramic tube with an average pore diameter of ₃ μm and a porosity of 40% is placed in a 600 ℃ muffle furnace for 4 h and then cooled to room temperature naturally. The surface of the _O3 ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 100 °C for 4 h, and cooled for later use. Soak the polished η-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 6mL polydopamine (2mg/L)/80mL TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 40°C for 24 hours, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of 15:40:320 is mixed at room temperature. The specific method is as follows: Dissolve sodium hydroxide and sodium metaaluminate in a part of deionized water in turn, stir thoroughly for 1 hour, and record it as solution A; then add sodium silicate to To another part of deionized water, stirring for 1h to completely dissolve the sodium silicate, recorded as B solution. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then vertically immerse the ceramic tube in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 30s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with stoppers, and place it in a 40°C oven for 10 hours for pretreatment for later use.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 70°C for 12h, then the temperature was raised to 120°C, 10r/min for crystallization for 4h, and the crystallization was repeated 6 times to obtain a molecular sieve ceramic membrane material. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 160 °C for 10 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 7:

Pretreatment of ceramic tube: Put the porous zirconia ceramic tube with an average pore diameter of 0.1 μm and a porosity of 40% in a muffle furnace at 600°C for 4 hours, cool it to room temperature naturally, and polish the surface of the zirconia ceramic tube with 1200-grit sandpaper. , ultrasonically cleaned with deionized water for 2 h, dried in an oven at 80 °C for 36 h, and cooled for later use. Soak the polished η-Al ₂ O ₃ ceramic tube in the polydopamine solution: prepare the polydopamine solution according to the ratio of 6mL polydopamine (2mg/L)/80mL TRIS-HCl (10mmol/L), and then continuously Under stirring, the ceramic tube was soaked in polydopamine solution at 25°C for 24 hours, and finally dried for use.

Preparation of molecular _sieve seed crystal sol The material ratio of 12:70:480 is mixed at room temperature. The specific method is as follows: Dissolve sodium metaaluminate and sodium hydroxide in a part of deionized water in turn, stir fully for 1 hour, and record it as solution A; then add sodium silicate to To another part of deionized water, stirring for 1h to completely dissolve the sodium silicate, recorded as B solution. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then immerse the ceramic tube vertically in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with a stopper, and place it in a 30°C oven for 10 hours for pretreatment.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 50°C for 12 hours, and then heated to 100°C at 100 r/min for crystallization for 6 hours to obtain a molecular sieve ceramic membrane material. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 200 °C for 2 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 8:

Pretreatment of the ceramic tube: The porous η-Al ₂ O ₃ ceramic tube with an average pore diameter of 4 μm and a porosity of 50% was placed in a 600 ℃ muffle furnace for 4 h and calcined, cooled to room temperature naturally, and the η-Al ₂ The surface of the O ₃ ceramic tube was polished smooth, ultrasonically cleaned with deionized water for 2 h, dried in an oven at 80 °C for 36 h, and cooled for later use. Place the polished η-Al ₂ O ₃ ceramic tube in the silane solution for soaking treatment: prepare the silane solution according to the ratio of 120mg aminopropyltriethoxysilane/5mL toluene, and then place the ceramic tube in the silane solution at 80°C High-pressure airtight treatment for 3h, drying and cooling for use.

Preparation of molecular _sieve seed crystal sol The material ratio of 12:70:480 is mixed at room temperature. The specific method is as follows: Dissolve sodium hydroxide and sodium metaaluminate in a part of deionized water in turn, stir well for 1 hour, and record it as solution A; then add solid sodium silicate Add it to another part of deionized water, stir for 1 h to completely dissolve the sodium silicate, and denote it as solution B. Then, the B solution was slowly added dropwise to the A solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then immerse the ceramic tube vertically in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with stoppers, and place it in a 65°C oven for 10 h for pretreatment.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 70 °C for 12 h, and then heated to 120 °C and 120 r/min for crystallization for 4 h to obtain a molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 200 °C for 2 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 9:

Pretreatment of ceramic tube: The porous silica ceramic tube with an average pore diameter of 2 μm and a porosity of 60% is placed in a 600 ℃ muffle furnace for 4 hours, and then cooled to room temperature naturally. The surface of the silica ceramic tube is polished with 1200-grit sandpaper. Ultrasonic cleaning with deionized water for 2 h, drying in an oven at 100 °C for 4 h, and cooling for later use. Soak the polished porous silica ceramic tube in silane solution: prepare a silane solution according to the ratio of 460mg aminopropyltriethoxysilane/20mL toluene, and then place the ceramic tube in the silane solution for high pressure sealing treatment at 120°C 30min, dry and cool for later use.

Preparation of molecular _sieve seed crystal sol The material ratio of :70:480 was mixed at room temperature, and the specific method was as follows: dissolving sodium hydroxide and aluminum isopropoxide in deionized water in turn, and stirring thoroughly for 1 hour. Then, the water glass solution was slowly added dropwise to the aluminum isopropoxide solution under strong stirring, continuously stirred for 1 hour at room temperature, left for aging for 24 hours, and then vigorously stirred to obtain a molecular sieve seed crystal sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then immerse the ceramic tube vertically in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the ends tightly with stoppers, and place it in a 35°C oven for pretreatment for 8 hours for later use.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 50°C for 12h, then the temperature was raised to 100°C, 80r/min for crystallization for 6h, and the crystallization was repeated 3 times to obtain a molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high temperature atmosphere furnace at 220°C for 2h activation under nitrogen protection (the heating rate was 1°C/min), and then cooled to room temperature naturally.

Example 10:

Pretreatment of ceramic tube: Put the porous titanium oxide ceramic tube with an average pore diameter of 4 μm and a porosity of 50% in a 600 ℃ muffle furnace for 4 hours, cool it to room temperature naturally, and polish the surface of the titanium oxide ceramic tube with 1200-grit sandpaper. Ultrasonic cleaning with deionized water for 2 h, drying in an oven at 80 °C for 12 h, and cooling for later use. Soak the polished and smooth porous silica ceramic tube in silane solution: prepare a silane solution according to the ratio of 240mg aminopropyltriethoxysilane/20mL toluene, and then place the ceramic tube in the silane solution for high pressure sealing treatment at 100°C 1h, dry and cool for use.

Preparation of molecular _sieve seed crystal sol The material ratio of :70:120 was mixed at room temperature, and the specific method was as follows: Dissolve aluminum isopropoxide and sodium hydroxide in deionized water in turn, and stir thoroughly for 1 hour. Then, the water glass was slowly added dropwise to the aluminum isopropoxide solution under strong stirring, continuously stirred for 1 hour at room temperature, allowed to stand for aging for 24 hours, and then vigorously stirred to obtain the molecular sieve seed crystal liquid sol.

Sol coating: plug one end of the ceramic tube and connect the other end to a vacuum pump, then immerse the ceramic tube vertically in the above-mentioned molecular sieve seed crystal liquid sol, and filter for 5s under the vacuum of 0.01MPa in the tube, and slowly remove the ceramic tube from the sol. Take it out, plug the two ends tightly with stoppers, and place it in a 60°C oven for 10 h for pretreatment.

Preparation of molecular sieve ceramic membrane: Pour the molecular sieve seed crystal liquid sol into a reaction kettle with a polytetrafluoroethylene lining, and immerse the seed-coated ceramic tube in the molecular sieve seed crystal liquid sol. The reaction kettle was sealed and placed in a homogeneous reactor at 50°C for 12h, and then heated to 100°C and crystallized at 80 r/min for 6h to obtain a molecular sieve ceramic membrane. Washed with deionized water and dried at room temperature, placed in a high-temperature atmosphere furnace at 160 °C for 8 h activation under nitrogen protection (the heating rate was 1 °C/min), and then cooled to room temperature naturally.

Example 11:

A molecular sieve ceramic membrane material for olefin purification. In the molecular sieve ceramic membrane material, the particle size of the molecular sieve particles supported on the surface of the ceramic material is 0.1 μm, and the thickness of the molecular sieve layer is 3 μm.

The preparation method of molecular sieve ceramic membrane material comprises the following steps:

1) Pretreatment of ceramic materials: The ceramic materials were calcined at 500°C for 6 hours, then cooled, ground with 1000-grit sandpaper, cleaned and dried, and then the ceramic materials were placed in the surface modifier solution and soaked at 80°C for 12 hours , then take out and dry to obtain the pretreated ceramic material;

2) Molecular sieve seed crystal pre-coating: prepare a molecular sieve seed crystal liquid, and use a vacuum filtration process to coat the surface of the pretreated ceramic material with molecular sieve crystal seeds, and then dry to obtain a ceramic material coated with molecular sieve seeds;

3) Closed crystallization: The ceramic material coated with molecular sieve seeds is placed in the molecular sieve seed liquid, then aged at 50 °C for 24 hours, then crystallized at 100 °C for 30 hours, and dried to obtain molecular sieve ceramics membrane material.

In step 1), the surface modifier solution is composed of a surface modifier and an organic solvent, the surface modifier is polydopamine, and the organic solvent is toluene; the ceramic material is porous zirconia, and the ceramic material is tubular.

In step 2), the molecular sieve seed liquid is a molecular sieve seed liquid sol, and the preparation method of the molecular sieve seed liquid sol is as follows: aluminum source, silicon source, sodium hydroxide, and deionized water are calculated according to n(Al):n(Si ):n(Na):n(H ₂ O)=2:3:60:300 After weighing respectively, first add the aluminum source and sodium hydroxide to a part of deionized water, and stir to completely dissolve the aluminum source to obtain A Then add the silicon source to another part of deionized water, stir to completely dissolve the silicon source, and obtain solution B, then add solution B dropwise to solution A under stirring, and stir at room temperature for 6 hours, and then let stand for aging 20h is enough.

The aluminum source includes aluminum hydroxide and hydrated alumina, and the silicon source includes solid silica gel and solid sodium silicate.

When the ceramic material is in a tubular shape, in step 2), the method of coating the surface of the pretreated ceramic material with molecular sieve seed crystals is as follows: stirring the molecular sieve seed crystal liquid evenly, then blocking one end of the tubular ceramic material, and connecting the other end with a vacuum pump , and then immerse the tubular ceramic material vertically in the molecular sieve seed liquid, keep the vacuum degree in the tubular ceramic material at 0.01 MPa, and perform suction filtration for 5 s. to keep for 2h.

The molecular sieve ceramic membrane material is used to remove polar oxygenates in a gaseous olefin stream to less than 1 ppm.

Example 12:

A molecular sieve ceramic membrane material for olefin purification. In the molecular sieve ceramic membrane material, the particle size of the molecular sieve particles supported on the surface of the ceramic material is 3 μm, and the thickness of the molecular sieve layer is 5 μm.

The preparation method of molecular sieve ceramic membrane material comprises the following steps:

1) Pretreatment of ceramic materials: The ceramic materials were calcined at 800 °C for 0.1 h, then cooled, ground with 2500-grit sandpaper, cleaned and dried, and then the ceramic materials were placed in the surface modifier solution and soaked at 10 °C 36h, then take out and dry to obtain the pretreated ceramic material;

2) Molecular sieve seed crystal pre-coating: prepare a molecular sieve seed crystal liquid, and use a vacuum filtration process to coat the surface of the pretreated ceramic material with molecular sieve crystal seeds, and then dry to obtain a ceramic material coated with molecular sieve seeds;

3) Closed crystallization: the ceramic material coated with molecular sieve seeds is placed in the molecular sieve seed liquid, then aged at 20°C for 48h, then crystallized at 60°C for 60h, and dried to obtain molecular sieve ceramics membrane material.

In step 1), the surface modifier solution is composed of a surface modifier and an organic solvent, the surface modifier includes aminopropyltriethoxysilane and chitosan, and the organic solvent package is TRIS-HCl buffer; ceramic material It is porous mullite, and the ceramic material is tubular.

In step 2), the molecular sieve seed liquid is a molecular sieve seed liquid sol, and the preparation method of the molecular sieve seed liquid sol is as follows: aluminum source, silicon source, sodium hydroxide, and deionized water are calculated according to n(Al):n(Si ):n(Na):n(H ₂ O)=2:25:2:1320 After weighing respectively, first add the aluminum source and sodium hydroxide to a part of deionized water, stir to completely dissolve the aluminum source, and obtain A Then add the silicon source to another part of deionized water, stir to completely dissolve the silicon source, and obtain solution B, then add solution B dropwise to solution A under stirring, and stir at room temperature for 0.5h, then let stand It can be aged for 28h.

The aluminum source includes sodium aluminate, aluminum sulfate and aluminum isopropoxide, and the silicon source includes water glass, silica sol and tetraethyl silicate.

When the ceramic material is in a tubular shape, in step 2), the method of coating the surface of the pretreated ceramic material with molecular sieve seed crystals is as follows: stirring the molecular sieve seed crystal liquid evenly, then blocking one end of the tubular ceramic material, and connecting the other end with a vacuum pump , and then the tubular ceramic material was immersed vertically in the molecular sieve seed liquid, the vacuum degree in the tubular ceramic material was maintained at 0.0001 MPa, and the vacuum was filtered for 30 minutes, and then the tubular ceramic material was taken out from the molecular sieve seed liquid. for 48h.

The molecular sieve ceramic membrane material is used to remove polar oxygenates in a gaseous olefin stream to less than 1 ppm.

Example 13:

A molecular sieve ceramic membrane material for olefin purification. In the molecular sieve ceramic membrane material, the particle size of the molecular sieve particles supported on the surface of the ceramic material is 1 μm, and the thickness of the molecular sieve layer is 4 μm.

The preparation method of molecular sieve ceramic membrane material comprises the following steps:

1) Pretreatment of ceramic materials: The ceramic materials were calcined at 200°C for 12 hours, then cooled, ground with 100-grit sandpaper, cleaned and dried, and then the ceramic materials were placed in the surface modifier solution and soaked at 150°C for 5 minutes , then take out and dry to obtain the pretreated ceramic material;

2) Molecular sieve seed crystal pre-coating: prepare a molecular sieve seed crystal liquid, and use a vacuum filtration process to coat the surface of the pretreated ceramic material with molecular sieve crystal seeds, and then dry to obtain a ceramic material coated with molecular sieve seeds;

3) Closed crystallization: The ceramic material coated with molecular sieve seeds is placed in the molecular sieve seed liquid, then aged at 80 °C for 2 hours, then crystallized at 140 °C for 4 hours, and dried to obtain molecular sieve ceramics membrane material.

In step 1), the surface modifier solution is composed of a surface modifier and an organic solvent, the surface modifier is hydroxymethyl cellulose, and the organic solvent includes toluene and TRIS-HCl; the ceramic material is porous alumina, and the ceramic material is Tubular.

In step 2), the molecular sieve seed liquid is a molecular sieve seed liquid sol, and the preparation method of the molecular sieve seed liquid sol is as follows: aluminum source, silicon source, sodium hydroxide, and deionized water are calculated according to n(Al):n(Si ):n(Na):n(H ₂ O)=2:17:30:800 After weighing respectively, first add the aluminum source and sodium hydroxide to a part of deionized water, stir to completely dissolve the aluminum source, and obtain A Then add the silicon source to another part of deionized water, stir to dissolve the silicon source completely to obtain solution B, then add solution B dropwise to solution A under stirring, and stir at room temperature for 2 hours, and then let stand for aging 25h is enough.

The aluminum source includes aluminum phosphate and bauxite, and the silicon source is silica.

When the ceramic material is in a tubular shape, in step 2), the method of coating the surface of the pretreated ceramic material with molecular sieve seed crystals is as follows: stirring the molecular sieve seed crystal liquid evenly, then blocking one end of the tubular ceramic material, and connecting the other end with a vacuum pump , and then immerse the tubular ceramic material vertically in the molecular sieve seed liquid, maintain the vacuum degree in the tubular ceramic material at 0.001 MPa, and perform suction filtration for 10 minutes. kept for 24h.

The molecular sieve ceramic membrane material is used to remove polar oxygenates in a gaseous olefin stream to less than 1 ppm.

Example 14:

In this embodiment, the ceramic material includes porous titanium oxide and porous silicon oxide, and the ceramic material is in the form of a sheet, and the rest are the same as those in Embodiment 11.

Example 15:

In this embodiment, the ceramic material is porous titanium oxide, and the ceramic material is a layered spiral, and the rest are the same as those in Embodiment 11.

Example 16:

In this embodiment, the ceramic material is porous zirconia, and the ceramic material is annular, and the rest are the same as those in Embodiment 11.

The foregoing description of the embodiments is provided to facilitate understanding and use of the invention by those of ordinary skill in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made, and the generic principles described herein can be applied to other embodiments without inventive step. Therefore, the present invention is not limited to the above-mentioned embodiments, and improvements and modifications made by those skilled in the art according to the disclosure of the present invention without departing from the scope of the present invention should all fall within the protection scope of the present invention.

Claims (8)

1, A method for preparing a molecular sieve ceramic membrane material for olefin purification, characterized in that the method comprises the following steps:

1) pretreatment of ceramic materials: roasting the ceramic material at the temperature of 200-800 ℃ for 0.1-12h, then cooling, polishing, cleaning and drying, then placing the ceramic material in a surface modifier solution, soaking at the temperature of 10-150 ℃ for 5min-36h, and then taking out and drying to obtain the pretreated ceramic material;

2) pre-coating molecular sieve crystal seeds: preparing a molecular sieve crystal liquid, coating a molecular sieve crystal seed on the surface of the pretreated ceramic material by using a vacuum filtration process, and then drying to obtain the ceramic material coated with the molecular sieve crystal seed;

3) closed crystallization: placing the ceramic material coated with the molecular sieve crystal seeds in a molecular sieve crystal liquid, then aging at 20-80 ℃ for 2-48h, then crystallizing at 60-140 ℃ for 4-60h, and drying to obtain a molecular sieve ceramic membrane material;

in the step 1), the surface modifier solution consists of a surface modifier and an organic solvent, wherein the surface modifier comprises or more of polydopamine, aminopropyltriethoxysilane, chitosan or hydroxymethyl cellulose, and the organic solvent comprises or two of toluene or TRIS-HCl buffer solution;

in the step 2), the molecular sieve crystal liquid is a molecular sieve crystal seed hydrosol, and the preparation method of the molecular sieve crystal seed hydrosol comprises the following steps: an aluminum source, a silicon source, sodium hydroxide and deionized water according to the formula (n), (Al), (n), (Si), (n), (Na), (N) and (H)₂Respectively weighing O) 2:3-25:2-60:300-1320, adding an aluminum source and sodium hydroxide into parts of deionized water, stirring to completely dissolve the aluminum source to obtain an A solution, adding a silicon source into parts of deionized water, stirring to completely dissolve the silicon source to obtain a B solution, dropwise adding the B solution into the A solution under stirring, stirring at room temperature for 0.5-6h, and standing and aging for 20-28 h.

2. The method for preparing molecular sieve ceramic membrane materials for olefin purification according to claim 1, wherein in step 1), the sand paper with 100-2500 meshes is used for grinding.

3. The method for preparing molecular sieve ceramic membrane materials for olefin purification according to claim 1, wherein in step 1), the ceramic materials comprise or more of porous alumina, porous mullite, porous zirconia, porous titania or porous silica, and the ceramic materials are in a tubular shape, a sheet shape, a layered spiral shape or a ring shape.

4. The method of molecular sieve ceramic membrane materials for olefin purification according to claim 1, wherein the aluminum source comprises or more of aluminum hydroxide, hydrated alumina, sodium aluminate, aluminum sulfate, aluminum isopropoxide, aluminum phosphate or bauxite, and the silicon source comprises or more of solid silica gel, solid sodium silicate, water glass, silica sol, tetraethyl silicate or white carbon.

5. The preparation method of molecular sieve ceramic membrane material for olefin purification, according to claim 1, wherein when the ceramic material is tubular, the step 2) of coating molecular sieve seeds on the surface of the pretreated ceramic material comprises stirring the molecular sieve seed liquid uniformly, blocking the end of the tubular ceramic material, connecting the end to a vacuum pump, vertically immersing the tubular ceramic material in the molecular sieve seed liquid, keeping the vacuum degree in the tubular ceramic material at 0.0001-0.01MPa, suction-filtering for 5s-30min, taking out the tubular ceramic material from the molecular sieve seed liquid, and placing the tubular ceramic material in an oven at 25-65 ℃ for 2-48 h.

molecular sieve ceramic membrane material for olefin purification, characterized in that it is prepared by the method according to any of claims 1 to 5, .

7. The molecular sieve ceramic membrane material for olefin purification of claim 6, wherein the molecular sieve particles loaded on the surface of the ceramic material have a particle size of 0.1-3 μm, and the molecular sieve layer has a thickness of 3-5 μm.

Use of the molecular sieve ceramic membrane material of claim 6 for removing polar oxygenates to below 1ppm from a gaseous olefin stream in .

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