阅读说明：本技术 一种钯复合膜及其制备方法 (Palladium composite membrane and preparation method thereof ) 是由 梁立双 郝立娟 胡彦明 于 2021-08-04 设计创作，主要内容包括：本发明公开了一种钯复合膜及其制备方法,包括分子筛的制备、分子筛膜的制备、分子筛膜的修饰、活化、钯膜的沉积、热处理、缺陷修补等处理步骤。本发明通过对分子筛膜、钯膜的二次修饰,极大地降低了膜的缺陷；制得的钯复合膜渗透通量大、氢气分离选择因素高、稳定性好,具有较好的应用前景。(The invention discloses a palladium composite membrane and a preparation method thereof, which comprises the processing steps of preparation of a molecular sieve, preparation of a molecular sieve membrane, modification and activation of the molecular sieve membrane, deposition of the palladium membrane, heat treatment, defect repair and the like. The invention greatly reduces the defects of the membrane by secondary modification of the molecular sieve membrane and the palladium membrane; the prepared palladium composite membrane has the advantages of large permeation flux, high hydrogen separation selection factor, good stability and good application prospect.)

1. A preparation method of a palladium composite membrane is characterized by comprising the following steps:

(1) preparing a molecular sieve;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃Synthesizing a molecular sieve membrane on the ceramic tube;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing a silane coupling agent, treating the molecular sieve membrane for 4-8 hours at 50-100 ℃, and cleaning the molecular sieve membrane with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 1-allyl imidazole, adding di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1-5 hours at 50-100 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: placing the modified molecular sieve membrane prepared in the step (3) in a trichloromethane solvent containing palladium acetate for activation;

(5) deposition of palladium film: depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4);

(6) and (3) heat treatment: placing the film deposited with palladium in the step (5) in an inert gas atmosphere for heat treatment;

(7) defect repair: and (4) placing the membrane subjected to heat treatment in the step (6) in a reactor, simultaneously leading silicon-containing steam to the side of the palladium membrane, leading oxygen to the palladium membrane substrate, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane after the reaction is finished.

2. The method for preparing a palladium composite membrane according to claim 1, wherein the silane coupling agent accounts for 9% by mass and the 1-allylimidazole accounts for 8% by mass in the step (3).

3. The method for preparing a palladium composite membrane according to claim 1, wherein the amount of di-tert-butyl peroxide used in step (3) is 1 to 20 g.

4. The method for preparing a palladium composite membrane according to claim 1, wherein the content of palladium acetate in step (4) is 4 g/L.

5. The preparation method of the palladium composite membrane according to claim 4, wherein the activation temperature in the step (4) is 40-50 ℃ and the activation time is 1-3 h.

6. The method of claim 1, wherein the palladium film is deposited by one or both of electroless plating and electroplating in step (5).

7. The preparation method of the palladium composite membrane according to claim 6, wherein the heat treatment in the step (6) is performed in an inert gas atmosphere, the heat treatment temperature is 450 ℃, and the heat treatment time is 0.5-4 h.

8. The method according to claim 7, wherein the silicon vapor in step (7) is silicon hydride.

9. The method of claim 9, wherein the flow rate of the silicon vapor in the step (7) is 15ml/min, and the flow rate of the oxygen gas is 15 ml/min.

10. A palladium composite membrane prepared by the method of any one of claims 1 to 9.

Technical Field

The invention relates to the technical field of hydrogen separation, in particular to a palladium composite membrane and a preparation method thereof.

Background

Hydrogen energy plays a very important role in future energy systems. With the rapid development of hydrogen energy, the research on the corresponding production, separation, storage and transportation and application links is increasingly paid attention. The hydrogen separation is an important link of a hydrogen energy system, and the development of the hydrogen energy system plays an important role in the development of the hydrogen energy industry.

The separation and purification of hydrogen is performed by a pressure swing adsorption method, a temperature swing adsorption method, a cryogenic method, a membrane method and the like, wherein the membrane method has been a hot point of research due to the advantages of low investment, low energy consumption, high efficiency, convenient operation and the like. The membrane materials which can be used for hydrogen separation at present include metallic palladium and alloy membranes thereof, molecular sieve membranes, carbon membranes, silicon membranes and the like, wherein the palladium and alloy membranes thereof are concerned about due to the advantages of strong hydrogen permeability, high selectivity and the like. The commercialized palladium membrane is mainly a self-supporting palladium-silver and palladium-copper alloy membrane, is prepared by a rolling process, and has the thickness of about 100 mu m for keeping enough strength, and the membrane prepared by the process has extremely high density, low hydrogen permeability and high cost.

Although the supported metal palladium membrane reduces the use amount of noble metals and reduces the production cost, the composite palladium membrane changes the hydrogen permeation process from bulk phase diffusion control step to external diffusion control, and increases the mass transfer resistance of hydrogen in the external diffusion process. In addition, because the carrier is in a loose and porous structure in the membrane preparation process, the palladium membrane is difficult to perfectly cover the surface carrier without defects, so that defects are generated, the integrity of the membrane material is influenced, and the separation performance of the membrane material is reduced.

The chemical plating method for preparing the palladium membrane is a method for forming a membrane by reducing and depositing metal salt through autocatalysis reaction under the condition of no external current, the method can almost deposit metal on a substrate in any shape, and the prepared membrane has uniform thickness, fine crystal grains and less defects, and is known as one of the most successful methods for preparing the compact palladium composite membrane. The chemical plating comprises the operation steps of cleaning, activating, plating, post-processing and the like, each step influences the performance of the film layer, and meanwhile, the film with excellent performance and thinner thickness needs a high-quality porous carrier, which undoubtedly increases the cost of the film. How to optimize each preparation process link is necessary to provide a preparation method of a high-performance palladium composite membrane.

Disclosure of Invention

Aiming at the defects in the prior art, the invention aims to provide a palladium composite membrane and a preparation method thereof, which ensure that the prepared palladium composite membrane has excellent hydrogen separation performance by optimizing the steps of a modification method of a carrier, selection of an active substance, defect repair and the like.

In order to achieve the purpose, the invention adopts the following technical scheme:

a preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃Synthesizing a molecular sieve membrane on the ceramic tube;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing a silane coupling agent, treating the molecular sieve membrane for 4-8 hours at 50-100 ℃, and cleaning the molecular sieve membrane with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 1-allyl imidazole, adding di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1-5 hours at 50-100 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: placing the modified molecular sieve membrane prepared in the step (3) in a trichloromethane solvent containing palladium acetate for activation;

(5) deposition of palladium film: depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4);

(6) and (3) heat treatment: placing the film deposited with palladium in the step (5) in an inert gas atmosphere for heat treatment;

(7) defect repair: and (4) placing the membrane subjected to heat treatment in the step (6) in a reactor, simultaneously leading silicon-containing steam to the side of the palladium membrane, leading oxygen to the palladium membrane substrate, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane after the reaction is finished.

Preferably, in the step (3), the mass fraction of the silane coupling agent is 9% and the mass fraction of the 1-allylimidazole is 8%.

Preferably, the dosage of the di-tert-butyl peroxide in the step (3) is 1-20 g.

Preferably, the content of palladium acetate in the step (4) is 4 g/L.

Preferably, the activation temperature in the step (4) is 40-50 ℃, and the activation time is 1-3 h.

Preferably, the deposition of the palladium film in step (5) adopts one or two of electroless plating or electroplating.

Preferably, the heat treatment in the step (6) is carried out in an inert gas atmosphere, the heat treatment temperature is 450 ℃, and the heat treatment time is 0.5-4 h.

Preferably, the silicon vapor in step (7) is silicon hydride.

Preferably, the flow rate of silicon vapor in step (7) is 15ml/min and the flow rate of oxygen is 15 ml/min.

The invention also claims a palladium composite membrane prepared by any one of the methods.

Compared with the prior art, the invention has the following beneficial effects:

(1) the invention provides a preparation method of a palladium composite membrane with optimized process, which greatly reduces the defects of the membrane by carrying out secondary modification on a molecular sieve membrane and a palladium membrane; the prepared palladium composite membrane has the advantages of large permeation flux, high hydrogen selection and good stability.

(2) The invention repairs the surface defect of the prepared molecular sieve membrane by carrying out surface modification once on the molecular sieve membrane, reduces the pore channel density of non-molecular sieves of the membrane layer and improves the permeability of the carrier.

(3) The invention carries out secondary defect modification on the prepared palladium composite membrane and uses concentration difference to deposit SiO₂The surface of the composite membrane is repaired in situ, so that the defects of the palladium membrane are repaired; simultaneous deposition of SiO₂The micropores can further improve the hydrogen separation performance.

(4) The invention unexpectedly finds that the palladium acetate is used for activating the molecular sieve membrane carrier to replace the traditional tin chloride-palladium chloride method, overcomes the defect that the tin is introduced into the palladium membrane to cause the defect of the palladium membrane in the tin chloride-palladium chloride method, is environment-friendly and maintains the high hydrogen flux and hydrogen/nitrogen selectivity of the membrane.

In a word, the invention optimizes the synthesis process of the palladium composite membrane, improves the aspects of modification of the carrier, activation of the carrier, secondary defect repair and the like, ensures that the prepared palladium composite membrane has excellent hydrogen separation performance, greatly reduces the defects of the palladium composite membrane, and prolongs the service life of the composite membrane.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

All raw materials are purchased from the market in the present invention unless otherwise specified.

Example 1

A preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve; the preparation of the molecular sieve belongs to the prior art, and in the embodiment, reference document data 1 (preparation and characterization of the plum steel, SAPO-34 and the composite membrane and membrane reactor performance research [ D ]. university of university, 2009.) is prepared;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃The specific preparation method of the molecular sieve membrane synthesized on the ceramic tube also belongs to the prior art, and in this example, reference 1 (preparation and characterization of Ligang, SAPO-34 and composite membrane and membrane reactor performance research [ D ]]University of major graduate, 2009.); wherein the size of the seed crystal is 200nm, and the carrier is pulled in the seed crystal liquid for 4 times;

wherein the pretreatment process of the carrier comprises the following steps: alpha-Al to be purchased₂O₃Polishing a ceramic tube smoothly, then placing the ceramic tube in a hydrochloric acid solution with the mass fraction of 5%, fully oscillating and washing with water; then placing the carrier in a sodium hydroxide solution with the mass fraction of 1%, oscillating again, washing with water to be neutral, drying, and finally roasting at the high temperature of 740 ℃ to finish the pretreatment of the carrier;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing 9 wt% of silane coupling agent, treating for 5 hours at 70 ℃, and cleaning with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 8 wt% of 1-allyl imidazole, adding 4g of di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1.5h at 75 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: putting the modified molecular sieve membrane prepared in the step (3) into a chloroform solvent containing 4g/L palladium acetate, and activating for 2 hours at 50 ℃;

(5) deposition of palladium film: and (4) depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4), wherein the deposition is carried out by adopting a chemical plating method in the prior art, and the plating solution comprises the following components: PdCl₂ 3.5g/L，EDTA-2Na 30g/L，NH₃·H₂O(28％)101ml/L，N₂H₄·H₂O(1mol/L)16ml/L；

(6) And (3) heat treatment: placing the film deposited with palladium in the step (5) in an inert gas atmosphere, and carrying out heat treatment for 2h at 450 ℃;

(7) defect repair: and (3) placing the membrane subjected to heat treatment in the step (6) in a reactor, simultaneously leading steam containing silicon hydride to the side of the palladium membrane at the flow rate of 15ml/min, leading oxygen to the palladium membrane substrate at the flow rate of 15ml/min, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane product after the reaction is finished.

And (3) carrying out performance test on the prepared palladium composite membrane, wherein the test method comprises the following steps: and respectively measuring the permeability of the membrane layer by using hydrogen or nitrogen as test gas under the conditions of 500 ℃ and 100kPa, wherein the hydrogen selectivity is the ratio of the permeability of the hydrogen to the permeability of the nitrogen.

And (3) testing results: hydrogen permeability of 5.7X 10^-6mol m^-2s^-1Pa^-1Selectivity is 698; meanwhile, the gas permeability of the membrane is not obviously changed after 120 hours of operation.

Example 2

A preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve; the preparation of the molecular sieve belongs to the prior art, and in the embodiment, reference document data 1 (preparation and characterization of the plum steel, SAPO-34 and the composite membrane and membrane reactor performance research [ D ]. university of university, 2009.) is prepared;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃The specific preparation method of the molecular sieve membrane synthesized on the ceramic tube also belongs to the prior art, and in this example, reference 1 (preparation, characterization and membrane inversion of Ligang, SAPO-34 and composite membrane) is providedReactor Performance study [ D]University of major graduate, 2009.);

wherein the pretreatment process of the carrier comprises the following steps: alpha-Al to be purchased₂O₃Polishing a ceramic tube smoothly, then placing the ceramic tube in a hydrochloric acid solution with the mass fraction of 5%, fully oscillating and washing with water; then placing the carrier in a sodium hydroxide solution with the mass fraction of 1%, oscillating again, washing with water to be neutral, drying, and finally roasting at the high temperature of 740 ℃ to finish the pretreatment of the carrier;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing 9 wt% of silane coupling agent, treating for 4.5 hours at 75 ℃, and cleaning with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 8 wt% of 1-allyl imidazole, adding 6g of di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1h at 80 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: placing the modified molecular sieve membrane prepared in the step (3) in a chloroform solvent containing 4g/L palladium acetate, and activating for 2.5h at 48 ℃;

(5) deposition of palladium film: and (4) depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4), wherein the deposition is carried out by adopting a chemical plating method in the prior art, and the plating solution comprises the following components: PdCl₂ 3.5g/L，EDTA-2Na 30g/L，NH₃·H₂O(28％)101ml/L，N₂H₄·H₂O(1mol/L)16ml/L；

(6) And (3) heat treatment: placing the film deposited with palladium in the step (5) in an inert gas atmosphere, and carrying out heat treatment at 450 ℃ for 2.5 h;

(7) defect repair: and (3) placing the membrane subjected to heat treatment in the step (6) in a reactor, simultaneously leading steam containing silicon hydride to the side of the palladium membrane at the flow rate of 15ml/min, leading oxygen to the palladium membrane substrate at the flow rate of 15ml/min, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane product after the reaction is finished.

And (3) carrying out performance test on the prepared palladium composite membrane, wherein the test method comprises the following steps: and respectively measuring the permeability of the membrane layer by using hydrogen or nitrogen as test gas under the conditions of 500 ℃ and 100kPa, wherein the hydrogen selectivity is the ratio of the permeability of the hydrogen to the permeability of the nitrogen.

And (3) testing results: hydrogen permeability of 5.6X 10^-6mol m^-2s^-1Pa^-1Selectivity is 702; meanwhile, the gas permeability of the membrane is not obviously changed after 120 hours of operation.

Comparative example 1

A preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve; the preparation of the molecular sieve belongs to the prior art, and in the embodiment, reference document data 1 (preparation and characterization of the plum steel, SAPO-34 and the composite membrane and membrane reactor performance research [ D ]. university of university, 2009.) is prepared;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃The specific preparation method of the molecular sieve membrane synthesized on the ceramic tube also belongs to the prior art, and in this example, reference 1 (preparation and characterization of Ligang, SAPO-34 and composite membrane and membrane reactor performance research [ D ]]University of major graduate, 2009.); wherein the size of the seed crystal is 200nm, and the carrier is pulled in the seed crystal liquid for 4 times;

wherein the pretreatment process of the carrier comprises the following steps: alpha-Al to be purchased₂O₃Polishing a ceramic tube smoothly, then placing the ceramic tube in a hydrochloric acid solution with the mass fraction of 5%, fully oscillating and washing with water; then placing the carrier in a sodium hydroxide solution with the mass fraction of 1%, oscillating again, washing with water to be neutral, drying, and finally roasting at the high temperature of 740 ℃ to finish the pretreatment of the carrier;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing 9 wt% of silane coupling agent, treating for 5 hours at 70 ℃, and cleaning with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 8 wt% of 1-allyl imidazole, adding 4g of di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1.5h at 75 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: activating the modified molecular sieve membrane prepared in the step (3), wherein sensitization is adopted for activationActivating by two-step method, wherein the sensitizing solution contains SnCl₂2g/L of hydrochloric acid and 2ml/L of activating solution containing PdCl₂0.2g/L and 2ml/L of hydrochloric acid, and carrying out sensitization and activation treatment for 8 times;

(5) deposition of palladium film: and (4) depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4), wherein the deposition is carried out by adopting a chemical plating method in the prior art, and the plating solution comprises the following components: PdCl₂ 3.5g/L，EDTA-2Na 30g/L，NH₃·H₂O(28％)101ml/L，N₂H₄·H₂O(1mol/L)16ml/L；

(6) And (3) heat treatment: placing the film deposited with palladium in the step (5) in an inert gas atmosphere, and carrying out heat treatment for 2h at 450 ℃;

(7) defect repair: and (3) placing the membrane subjected to heat treatment in the step (6) in a reactor, simultaneously leading steam containing silicon hydride to the side of the palladium membrane at the flow rate of 15ml/min, leading oxygen to the palladium membrane substrate at the flow rate of 15ml/min, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane product after the reaction is finished.

And (3) carrying out performance test on the prepared palladium composite membrane, wherein the test method comprises the following steps: and respectively measuring the permeability of the membrane layer by using hydrogen or nitrogen as test gas under the conditions of 500 ℃ and 100kPa, wherein the hydrogen selectivity is the ratio of the permeability of the hydrogen to the permeability of the nitrogen.

And (3) testing results: hydrogen permeability of 4.9X 10^-6mol m^-2s^-1Pa^-1The selectivity is 665; meanwhile, the gas permeability of the membrane is not obviously changed after 120 hours of operation.

Comparative example 2

A preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve; the preparation of the molecular sieve belongs to the prior art, and in the embodiment, reference document data 1 (preparation and characterization of the plum steel, SAPO-34 and the composite membrane and membrane reactor performance research [ D ]. university of university, 2009.) is prepared;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃The molecular sieve membrane synthesized on the ceramic tube, and its concrete preparation method also belongs to the existent technologyReference 1 (preparation, characterization and membrane reactor performance of Ligang SAPO-34 and composite membranes) in the examples [ D]University of major graduate, 2009.); wherein the size of the seed crystal is 200nm, and the carrier is pulled in the seed crystal liquid for 4 times;

wherein the pretreatment process of the carrier comprises the following steps: alpha-Al to be purchased₂O₃Polishing a ceramic tube smoothly, then placing the ceramic tube in a hydrochloric acid solution with the mass fraction of 5%, fully oscillating and washing with water; then placing the carrier in a sodium hydroxide solution with the mass fraction of 1%, oscillating again, washing with water to be neutral, drying, and finally roasting at the high temperature of 740 ℃ to finish the pretreatment of the carrier;

(3) and (3) activation: putting the molecular sieve membrane prepared in the step (2) into a chloroform solvent containing 4g/L palladium acetate, and activating for 2 hours at 50 ℃;

(4) deposition of palladium film: and (4) depositing a palladium membrane on the surface of the molecular sieve membrane after the activation in the step (3), wherein the deposition is carried out by adopting a chemical plating method in the prior art, and the plating solution comprises the following components: PdCl₂ 3.5g/L，EDTA-2Na 30g/L，NH₃·H₂O(28％)101ml/L，N₂H₄·H₂O(1mol/L)16ml/L；

(5) And (3) heat treatment: placing the film deposited with palladium in the step (4) in an inert gas atmosphere, and carrying out heat treatment for 2h at 450 ℃;

(6) defect repair: and (3) placing the membrane subjected to heat treatment in the step (5) in a reactor, simultaneously leading steam containing silicon hydride to the side of the palladium membrane at the flow rate of 15ml/min, leading oxygen to the palladium membrane substrate at the flow rate of 15ml/min, reacting for 4 hours at 400 ℃, and obtaining the palladium composite membrane product after the reaction is finished.

And (3) carrying out performance test on the prepared palladium composite membrane, wherein the test method comprises the following steps: and respectively measuring the permeability of the membrane layer by using hydrogen or nitrogen as test gas under the conditions of 500 ℃ and 100kPa, wherein the hydrogen selectivity is the ratio of the permeability of the hydrogen to the permeability of the nitrogen.

And (3) testing results: hydrogen permeability of 3.0X 10^-6mol m^-2s^-1Pa^-1Selectivity is 358; meanwhile, the gas permeability of the membrane is obviously reduced after 120 hours of operation.

Comparative example 3

A preparation method of a palladium composite membrane comprises the following steps:

(1) preparing a molecular sieve; the preparation of the molecular sieve belongs to the prior art, and in the embodiment, reference document data 1 (preparation and characterization of the plum steel, SAPO-34 and the composite membrane and membrane reactor performance research [ D ]. university of university, 2009.) is prepared;

(2) preparing a molecular sieve membrane; alpha-Al after pretreatment by adopting secondary growth method₂O₃The specific preparation method of the molecular sieve membrane synthesized on the ceramic tube also belongs to the prior art, and in this example, reference 1 (preparation and characterization of Ligang, SAPO-34 and composite membrane and membrane reactor performance research [ D ]]University of major graduate, 2009.); wherein the size of the seed crystal is 200nm, and the carrier is pulled in the seed crystal liquid for 4 times;

wherein the pretreatment process of the carrier comprises the following steps: alpha-Al to be purchased₂O₃Polishing a ceramic tube smoothly, then placing the ceramic tube in a hydrochloric acid solution with the mass fraction of 5%, fully oscillating and washing with water; then placing the carrier in a sodium hydroxide solution with the mass fraction of 1%, oscillating again, washing with water to be neutral, drying, and finally roasting at the high temperature of 740 ℃ to finish the pretreatment of the carrier;

(3) modification of molecular sieve membrane: plugging two ends of the molecular sieve membrane prepared in the step (2), placing the molecular sieve membrane in ethanol containing 9 wt% of silane coupling agent, treating for 5 hours at 70 ℃, and cleaning with ethanol after the treatment is finished; then placing the molecular sieve membrane in ethanol containing 8 wt% of 1-allyl imidazole, adding 4g of di-tert-butyl peroxide in the nitrogen atmosphere, continuing to react for 1.5h at 75 ℃, and washing and drying after the reaction is finished to obtain a modified molecular sieve membrane;

(4) and (3) activation: putting the modified molecular sieve membrane prepared in the step (3) into a chloroform solvent containing 4g/L palladium acetate, and activating for 2 hours at 50 ℃;

(5) deposition of palladium film: and (4) depositing a palladium membrane on the surface of the modified molecular sieve membrane after the activation in the step (4), wherein the deposition is carried out by adopting a chemical plating method in the prior art, and the plating solution comprises the following components: PdCl₂ 3.5g/L，EDTA-2Na 30g/L，NH₃·H₂O(28％)101ml/L，N₂H₄·H₂O(1mol/L)16ml/L；

(6) And (3) heat treatment: and (3) placing the membrane deposited with the palladium in the step (5) in an inert gas atmosphere, carrying out heat treatment for 2h at 450 ℃, and obtaining a palladium composite membrane product after finishing the heat treatment.

And (3) carrying out performance test on the prepared palladium composite membrane, wherein the test method comprises the following steps: and respectively measuring the permeability of the membrane layer by using hydrogen or nitrogen as test gas under the conditions of 500 ℃ and 100kPa, wherein the hydrogen selectivity is the ratio of the permeability of the hydrogen to the permeability of the nitrogen.

And (3) testing results: hydrogen permeability of 3.8X 10^-6mol m^-2s^-1Pa^-1Selectivity is 509; meanwhile, the gas permeability of the membrane does not obviously decrease after 120 hours of operation.

The above-mentioned embodiment is only one of the preferred embodiments of the present invention, and should not be used to limit the scope of the present invention, but all the insubstantial modifications or changes made within the spirit and scope of the main design of the present invention, which still solve the technical problems consistent with the present invention, should be included in the scope of the present invention.