CN111137853A - Catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in MOCVD (metal organic chemical vapor deposition) process, and preparation method and application thereof - Google Patents
Catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in MOCVD (metal organic chemical vapor deposition) process, and preparation method and application thereof Download PDFInfo
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Abstract
The invention discloses a catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in MOCVD process, which is a catalytic permeable membrane reactor with catalytic activity and separation selectivity formed by embedding 10-30% of active component cobalt and 5-20% of molybdenum, 1-10% of auxiliary catalytic component lanthanum and 1-5% of promoter potassium into pretreated Carbon Nano Tubes (CNTs) by taking a porous gamma-alumina ceramic round tube containing 5-10% (w/w, the same below) of metal palladium dispersed in the porous gamma-alumina ceramic round tube as a support, coating the membrane thickness of the inner wall of the alumina ceramic round tube with 10-1 mu m and the membrane pore diameter of 0.20-10 nm, wherein the ammonia-containing tail gas in MOCVD process enters the membrane reactor after pretreatment, the reaction temperature is 400-600 ℃, the reaction pressure is 2.0-5.0 MPa for ammonia pyrolysis catalytic reaction, and the hydrogen-rich gas generated by the reaction is adsorbed, refined, deaminated and deaminated, And (3) performing pressure swing adsorption purification and metal getter purification to obtain a hydrogen product with the purity of more than 6-7N, returning the hydrogen product to the MOCVD process for recycling, and filling the blank for green and circular economic development of the LED industry.
Description
Technical Field
The present invention belongs to a method for producing semiconductor light-emitting diode (LED) containing ammonia gas (NH)3) The technical field of hydrogen preparation by comprehensive utilization of waste gas, in particular to a catalytic permeable membrane reactor for hydrogen production by MOCVD (metal oxide chemical vapor deposition) ammonia-containing tail gas and application thereof.
Background
MOCVD (metal oxide chemical vapor deposition) process (equipment) is used as a modern method and means for research and production of compound semiconductor materials, particularly as a method and equipment for manufacturing industrial production of a novel luminescent material, namely a Light Emitting Diode (LED), is a main method and means for producing photoelectric devices and microwave device materials in the world at present, comprises a laser, a detector, a high-efficiency solar cell, a photoelectric cathode and the like besides the LED, and is an indispensable method and equipment in the photoelectron industry, wherein the method comprises the production of a typical LED GaN epitaxial wafer, and the MOCVD epitaxial tail gas comprises N260% (v/v, the same applies hereinafter), H2:25％，NH314 percent, the rest comprises metal ions, particles and methane (CH)4) Oxygen (O)2) And oxygenates such as carbon monoxide (CO), carbon dioxide (CO)2) Water (H)2O), and the like.
At present, the NH contained in the tail gas of MOCVD epitaxy3The comprehensive utilization method of (2) is to obtain ammonia water by washing with water or obtain byproducts by rectification or absorption and the like to obtain the comprehensive utilization of ammonia. Because of the corrosiveness of liquid ammonia or ammonia water, washing with water or absorbing or rectifyingSpecial anti-corrosion measures are needed for separation from equipment, the cost is high, and ammonia in tail gas is changed into ammonia water or ammonia-containing compounds and cannot be directly utilized. In addition, H is still required in MOCVD epitaxy process2And the hydrogen content in the tail gas is too low to be effectively recycled.
No carbon oxides (e.g. CO, CO) are produced by decomposition of ammonia2) And nitrogen oxides (such as NO and NOx) and low hydrogen production cost, and is one of effective ways for preparing hydrogen for fuel cells. The ammonia gas can be liquefied and compressed under lower pressure, and is favorable for storage and transportation. The ammonia decomposition hydrogen production catalyst comprises single metal catalysts such as Ir, Ru, Ni and Fe, bimetallic catalysts such as Fe-Ni and Fe-Mo, carbide catalysts such as FeCx and MoCx, nitride catalysts such as FeNx and MoNx, and the like, wherein the catalysts mainly comprise noble metals such as Ru, Fe and Ni and transition metals. The catalytic assistant mainly comprises rare earth or alkali metal such as La, K and the like, and the active component carriers are mainly metal oxides such as alumina, magnesia and the like and carbon materials with larger specific surface area such as active carbon, carbon fibers (CNFs), Carbon Nanotubes (CNTs) and the like.
However, the catalyst used in the conventional ammonia catalytic thermal cracking hydrogen production and the fixed bed tubular reactor thereof face several problems: first, the ammonia gas or liquid ammonia feed used is essentially pure ammonia. Because MOCVD epitaxial tail gas contains a large amount of nitrogen and hydrogen besides ammonia, NH3The corresponding concentration or partial pressure is low and the partial pressure of nitrogen and hydrogen is high, so that the conversion rate of hydrogen production by ammonia catalytic decomposition of MOCVD epitaxial tail gas by directly adopting the traditional ammonia decomposition catalyst is very low, the hydrogen production selectivity is poor, and the processing capacity of the catalyst or the space velocity of the decomposition reaction can not reach the production scale and technical index of pure ammonia decomposition hydrogen production; secondly, in the catalyst and fixed bed tubular reactor used in the traditional ammonia catalytic thermal cracking hydrogen production reaction, raw gas and reaction gas need to be circulated in a certain amount in the reaction process to completely decompose ammonia, so that the energy consumption is increased, and hydrogen cannot be removed in time in a reaction system, so that the hydrogen partial pressure is increased continuously due to the accumulation of hydrogen concentration in the circulation, and the decomposition of ammonia is further inhibited; thirdly, in the mixed gas generated by the reaction, the circulation quantity is avoidedThe reaction gas still contains a large amount of nitrogen and a small amount of undecomposed ammonia, so that the load and the cost of subsequent PSA hydrogen extraction are increased; fourthly, the traditional pure ammonia decomposition hydrogen production process mostly obtains higher conversion rate and hydrogen yield at higher temperature, generally the reaction temperature is 600-800 ℃, and the relative energy consumption is higher. Therefore, the catalytic thermal cracking reaction is carried out on the MOCVD epitaxial tail gas with low ammonia concentration and high hydrogen concentration at a lower temperature, so that the ammonia conversion rate and the hydrogen selectivity are high, or the space velocity on a unit catalyst at least reaches the processing scale and the technical index of pure ammonia decomposition hydrogen production, and the method is very difficult; fifthly, if the ammonia decomposition conversion rate in the MOCVD epitaxial tail gas is low, or the obtained hydrogen cannot be removed in time, the content of the undecomposed ammonia in the reaction gas is too high, so that the cost for separating and extracting hydrogen from the tail gas or recycling the hydrogen is increased, the tail gas has to be purified and removed by using the traditional methods of washing ammonia with water and the like, and the technical and economic benefits are poor.
Disclosure of Invention
In order to solve the problems in the prior art, the invention mainly aims to provide a catalytic permeable membrane reactor for separating and purifying hydrogen by thermal cracking catalytic reaction of ammonia-containing tail gas in an LED-MOCVD process and having a selective hydrogen permeation effect and an application thereof. In addition, another purpose is that the catalyst has high activity and stability by the thermal cracking of ammonia, can better adapt to the working condition that the ammonia-containing mixed tail gas with low ammonia partial pressure and high nitrogen-hydrogen partial pressure generated in the MOCVD process can be effectively subjected to catalytic thermal cracking to produce hydrogen, and the obtained hydrogen product can be returned to the MOCVD process for recycling.
The purpose of the invention is realized by the following technical scheme:
a catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas by MOCVD process is composed of a supporting body made of gamma-alumina, refractory stainless steel, sintered alloy, Pd, or alumina-zirconia-titania or the composite ceramic of two or more of them, and a carbon material chosen from carbon nanotube, carbon fibre, activated carbon, carbon molecular sieve and graphene.
Preferably, the membrane reactor comprises an inorganic carbon nano-membrane which is formed by taking a gamma-aluminum oxide ceramic round tube containing 5-10% (w/w) of metal palladium dispersed in porous as a support, 10-30% (w/w) of cobalt and 5-20% (w/w) of molybdenum containing active components, 1-10% (w/w) of lanthanum containing a cocatalyst and 1-5% (w/w) of potassium containing a promoter, embedding the inorganic carbon nano-membrane into the pretreated carbon nano-tube, coating the inorganic carbon nano-membrane on the inner wall of the support, and forming the inorganic carbon nano-membrane with the membrane thickness of 10 nm-1 mu m and the membrane aperture of 0.20-10 nm.
Preferably, the membrane reactor comprises an inorganic carbon nanotube composite membrane which is formed by adopting a pure gamma-aluminum oxide ceramic round tube as a support, and containing 5-10% (w/w) of metal palladium with permselectivity, 5-20% (w/w) of metal ruthenium with catalytic activity, 1-10% (w/w) of lanthanum containing a cocatalyst and 1-5% (w/w) of potassium containing a promoter, wherein the inorganic carbon nanotube composite membrane is embedded in a pretreated carbon nanotube, is coated on the inner wall of the support, has a membrane thickness of 10-1 mu m and a membrane aperture of 0.20-10 nm.
Preferably, the support and the membrane tubes formed in the support may take one of a circular tube type, a flat plate type, a hollow fiber type, a shell and tube type, a roll type, a spiral type, and a corrugated sheet type.
Preferably, the membrane reactor can comprise a plurality of supports, and the membrane in each support can be made into a single-channel circular tube or a round or irregular multi-channel circular tube.
A preparation method of a catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas in an MOCVD process is characterized in that,
1) preparing a support body which takes one or two of gamma-aluminum oxide, high-temperature resistant stainless steel, sintered alloy, metal palladium and alumina-zirconia-titanium oxide composite ceramics as a support body material by one of a spray-dip calcination method, a mist deposition method, a sol-gel method or a solid particle sintering method;
2) embedding at least one of a loaded permeability selection component, a catalytic active component, a cocatalyst component and a promoter into a carbon material of pretreated carbon nanotubes, carbon fibers, activated carbon, carbon molecular sieves and graphene by one of an alcohol hot-melting-roasting method, an equal-volume impregnation method or a deposition-precipitation method, wherein the catalytic active component at least comprises a transition metal, a rare metal or a corresponding metal oxide;
3) coating or spraying the carbon material of step 2) on the support of step 1).
Preferably, the first and second liquid crystal materials are,
in the step 1), a porous gamma-aluminum oxide ceramic round tube containing 5-10% (w/w) of metal palladium is dispersed as a support, and the support is prepared by dipping a gamma-aluminum oxide ceramic tube into a palladium nitrate or palladium ammonium nitrate solution containing a metal palladium precursor, taking out the dipped gamma-aluminum oxide ceramic tube, then performing evacuation drying, calcining at 600-700 ℃ for 2-4 h in inert gas atmosphere flow, and cooling by nitrogen purging to form the porous gamma-aluminum oxide ceramic round tube support containing 5-10% of metal palladium;
in the step 2), embedding 10-30% (w/w) of cobalt and 5-20% (w/w) of molybdenum containing active components, 1-10% (w/w) of lanthanum containing a cocatalyst and 1-5% (w/w) of potassium containing a promoter into the pretreated carbon nano tube, adding a proper amount of the pretreated carbon nano tube into a proper amount of absolute ethyl alcohol or polyvinyl alcohol solution through an alcohol hot-dissolving-roasting method, heating and stirring to form a slurry, heating a cobalt-molybdenum bimetallic catalyst with a certain concentration to prepare a precursor which is a mixed solution of cobalt nitrate and molybdenum nitrate, wherein the cocatalyst precursor is a mixed solution of lanthanum nitrate and potassium nitrate and an ethanol or polyvinyl alcohol solution, adding a certain amount of ammonia water, and adjusting the pH of the mixed solution to be more than 10;
in the step 3), the mixed solution prepared in the step 2 is coated or sprayed into an inner tube of the porous gamma-alumina ceramic round tube support containing 5-10% (w/w) of metal palladium, the inner tube is heated to 100-140 ℃, ultrasonic or microwave irradiation and drying are carried out by controlling the time and the intensity of ultrasonic waves or microwaves, the total process is 2-4 h, roasting is carried out for 4-8 h at 600-700 ℃ under the flowing of nitrogen, the roasting temperature rise speed is controlled at 100-140 ℃/h or 100-140 ℃/2h, or the interval combination of the temperature rise speeds is controlled, and the inorganic carbon nanotube membrane containing the active component cobalt molybdenum, the co-catalytic component lanthanum and potassium, the membrane thickness is 10 nm-1 mu m, and the membrane aperture is 0.20-10 nm is formed.
Preferably, a pure gamma-aluminum oxide ceramic round tube without metal palladium impregnation is used as a support body; embedding 5-10% (w/w) of metal palladium with osmotic selectivity, 5-20% (w/w) of metal ruthenium with catalytic activity, 1-10% (w/w) of co-catalyst component lanthanum and 1-5% (w/w) of promoter potassium into the pretreated carbon nano tube, and coating the inorganic carbon nano tube composite membrane on the inner wall of a pure gamma-alumina ceramic round tube to form the inorganic carbon nano tube composite membrane with the membrane thickness of 10-1 mu m and the membrane aperture of 0.20-10 nm.
Preferably, the pretreatment of the carbon nanotube is to add a proper amount of commercially available 10-20 nm carbon nanotube carrier into a proper amount of mixed solution of 10-30% by mass of nitric acid and 50-70% by mass of nitric acid, heat and stir, reflux azeotropically for 4-8 hours, cool to ambient temperature, filter in vacuum, wash with deionized water to neutrality, dry the obtained filter cake at 120 ℃ for 1-2 hours, grind into 10-20 nm powder, and bake and cool to form the pretreated carbon nanotube.
The application of the catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas by the MOCVD process is characterized in that:
the catalytic thermal cracking hydrogen production reaction of ammonia is carried out according to the following steps,
(1) the raw material gas comes from the production of LED-GaN epitaxial wafers, and the MOCVD epitaxial tail gas typically comprises N2:40～60％ (v/v)，H2:25～35％(v/v)，NH314-24% (v/v), the rest including trace metal ions, particulate matter, methane and oxide;
(2) before the feed gas enters the membrane reactor, the impurity components in the feed gas are removed through a pretreatment process consisting of a precision filter, a catalytic deoxidation and molecular sieve dryer, a compressor and a heat exchanger or a heater, and the feed gas is pressurized and heated to 2.0-5.0 MPa and 400-600 ℃;
(3) the catalytic reaction temperature is 400-600 ℃, the reaction pressure is 2.0-5.0 MPa, and the industrial scale for treating tail gas is 50-5,000 Nm3/h；
(4) The method comprises the following steps of (1) feeding pretreated raw material gas from an inlet of a membrane reactor, carrying out ammonia catalytic pyrolysis catalytic reaction on one side of an inorganic carbon nano membrane inner tube in the membrane reactor, selectively permeating hydrogen obtained by reaction and hydrogen in the raw material gas out through one side of an inorganic carbon nano membrane outer tube, and flowing out from an outlet of the membrane reactor, wherein the hydrogen content is 98-99.9%, and the balance of a small amount of nitrogen and a trace amount of ammonia gas, sequentially feeding the hydrogen into adsorption fine deamination, Pressure Swing Adsorption (PSA) for hydrogen purification, deep drying and metal getter to obtain a hydrogen product with the purity of more than 99.9999-99.99999%, adjusting the pressure required by an LED-MOCVD process through the pressure, and returning the hydrogen product to the MOCVD process for recycling; the gas after reaction from one side of the inner tube of the inorganic carbon nano membrane in the membrane reactor flows out from a reaction gas outlet of the membrane reactor, one part of the gas returns to the feed gas circulation, and the other part of the gas enters tail gas purification to remove a small amount of ammonia, or is directly discharged, or enters a process of extracting nitrogen.
Compared with the prior art, the invention has the following characteristics and beneficial effects:
(1) the catalyst for preparing hydrogen by ammonia pyrolysis, which is suitable for raw material gas low-concentration ammonia and high-concentration hydrogen, is used for carrying out catalytic reaction, is separated from reaction gas of a selective hydrogen permeation membrane, is coupled in a membrane tube, and can remove the hydrogen in an ammonia decomposition hydrogen preparation system in time, so that the ammonia pyrolysis reaction is carried out in a direction favorable for generating the hydrogen, the conversion rate of ammonia and the selectivity of the hydrogen can reach 99 percent and even approach 100 percent, and the problem that the conversion rate and the yield of the hydrogen of the traditional pure ammonia pyrolysis hydrogen preparation are lower is solved;
(2) the invention utilizes the organic combination of reaction and separation of the catalytic permeable membrane reactor formed by coupling the ammonia decomposition hydrogen production and the hydrogen permeable membrane, greatly reduces the load and the cost of the subsequent PSA hydrogen extraction process, and has remarkable economic benefit;
(3) the invention prepares hydrogen by carrying out ammonia cracking on the ammonia-containing tail gas in the MOCVD process and returns the hydrogen to the LED-MOCVD process for recycling, thereby solving the problems that the prior methods for removing and purifying or recovering ammonia and ammonia compounds by washing, freezing, sulfuric acid absorption, phosphoric acid (ammonium) absorption and rectification coupling, catalytic combustion, catalytic decomposition and the like have relatively high energy consumption, low recovered substances or purity or other products and cannot return to the LED-MOCVD process for recycling, and the non-condensable gas has too low hydrogen concentration and cannot be economically recovered and reused, thereby not only realizing the reutilization of hydrogen in the tail gas, but also reducing the emission of waste gas and making up the blank of the ammonia-containing tail gas treatment technology in the LED-MOCVD process;
(4) the invention solves the problems that the raw material gas required by the traditional ammonia catalytic thermal cracking hydrogen production technology is pure ammonia, the conversion temperature is higher and the energy consumption is high, and the conversion rate of the ammonia cracking reaction is not high under the working conditions of a lower temperature range and higher hydrogen partial pressure.
(5) The membrane reactor disclosed by the invention has the advantages of high activity in a lower temperature range, strong stability, large space velocity of unit catalyst, large treatment scale, high hydrogen permeation rate, high ammonia conversion rate of over 99%, high hydrogen selectivity of 99-100%, and large-scale economic benefit.
Drawings
FIG. 1 is a schematic flow chart of example 1 of the present invention;
FIG. 2 is a schematic flow chart of embodiment 6 of the present invention.
Detailed Description
The invention will now be further illustrated, but not by way of technical limitation, with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention.
A catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas by MOCVD process and its application are disclosed, which features that the membrane reactor is prepared by dispersing the metal Pd (5-10% (w/w, the same as below) in porous gamma-aluminium oxide (gamma-Al)2O3) The ceramic round tube is used as a support, an inorganic carbon nano-Membrane which is embedded in pretreated carbon nano-tubes (CNTs) and contains 10-30% of active components of cobalt and 5-20% of molybdenum, 1-10% of auxiliary catalysis components of lanthanum and 1-5% of promoter potassium and is coated on the inner wall of the alumina ceramic round tube, the Membrane thickness is 10-1 mu m, the Membrane aperture is 0.20-10 nm, and the component comprises a connecting piece, a sealing piece, a Reactor inlet and outlet, an end socket and a jacket, so that a Catalytic permeable Membrane Reactor (CPSMR) with Catalytic activity and separation selectivity is formed, and Catalytic hydrogen production and thermal cracking reaction of ammonia are carried out according to the following steps,
(1) the raw material gas applicable to the catalytic permeable membrane reactor is from LED-GaN epitaxial wafer production, and MOCVD epitaxial tail gas of the catalytic permeable membrane reactor typically comprises N240 to 60% (v/v, the same applies hereinafter), H2:25～35％，NH314-24%, the rest including trace metal ions, particles, and methane (CH)4) And oxygenates such as carbon monoxide (CO), carbon dioxide (CO)2) Water (H)2O)；
(2) Before the feed gas enters the catalytic permeable membrane reactor, the feed gas is subjected to a pretreatment process consisting of a precision filter, a catalytic deoxygenation device, a molecular sieve dryer, a compressor and a heat exchanger or a heater to remove metal ions, particles, water and other impurity components in the feed gas, and the feed gas is pressurized and heated to 2.0-5.0 MPa and 400-600 ℃;
(3) the catalytic reaction temperature of the catalytic permeable membrane reactor is 400-600 ℃, the reaction pressure is 2.0-5.0 MPa, and the industrial scale of tail gas treatment is 50-5,000 Nm3/h；
(4) The method comprises the following steps of (1) feeding pretreated raw material gas from an inlet of the catalytic permeable membrane reactor, carrying out ammonia catalytic pyrolysis catalytic reaction on one side of an inorganic carbon nano membrane (inner tube) in the membrane reactor, selectively permeating hydrogen obtained by reaction and hydrogen in the raw material gas out through one side of the inorganic carbon nano membrane (outer tube), and flowing out from an outlet of the membrane reactor, wherein the content of the hydrogen is 98-99.9%, the balance is a small amount of nitrogen and a trace amount of ammonia, sequentially feeding the hydrogen into adsorption fine deamination, Pressure Swing Adsorption (PSA) for hydrogen purification, deep drying and metal getter to obtain a hydrogen product with the purity of more than 99.9999-99.99999%, adjusting the pressure to the pressure required by an LED-MOCVD process through the pressure, and returning the hydrogen product to the MOCVD process for recycling; the gas after reaction from one side of the inorganic carbon nano membrane (inner tube) in the membrane reactor flows out from a reaction gas outlet of the membrane reactor, one part of the gas returns to the feed gas circulation, and the other part of the gas enters a tail gas purification step to remove a small amount of ammonia, or is directly discharged, or enters a nitrogen extraction step.
Furthermore, the catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in the MOCVD process and the application are characterized in that the catalytic permeable membrane reactor containing 10-30% of active component cobalt and 5-20% of molybdenum, 1-10% of cocatalyst component lanthanum and 1-5% of promoter potassium are embedded into the pretreated Carbon Nano Tubes (CNTs) and coated on gamma-aluminum oxide (gamma-Al)2O3) The inorganic carbon nano tube film is formed by that the film thickness of inner wall of ceramic round tube is 10 nm-1 micrometer and the film aperture is 0.20-10 nm, and is characterized by that it utilizes alcohol thermal dissolving-roasting method to add proper quantity of the described pretreated multilayer Carbon Nano Tube (CNTs) into proper quantity of absolute ethyl alcohol or polyvinyl alcohol solution, and after the above-mentioned materials are heated and stirred to form slurry state, the cobalt-molybdenum bimetal catalyst with a certain concentration is heated to prepare precursor cobalt nitrate (Co (NO) as precursor3)2) And molybdenum nitrate (Mo (NO)3)3) The mixed solution and the promoter precursor are lanthanum nitrate (La (NO)3)3) With potassium nitrate (KNO)3) Adding a certain amount of ammonia water into the mixed solution and ethanol or polyvinyl alcohol solution, adjusting the pH of the mixed solution to be more than 10, and then coating or spraying the mixed solution on the porous gamma-Al containing 5-10% of metal palladium dispersed in the porous gamma-Al2O3Heating the inner tube of the ceramic round tube support body to 100-140 ℃, controlling the time and intensity of ultrasonic waves or microwaves to perform ultrasonic or microwave irradiation radiation and drying, wherein the total process is 2-4 h, roasting is performed for 4-8 h at 600-700 ℃ under the flowing of nitrogen, the roasting temperature rise speed is controlled to be 100-140 ℃/h or 100-140 ℃/2h or the interval combination of the temperature rise speeds is controlled, and embedding the active component cobalt molybdenum and the co-catalysis components lanthanum and potassium into the inner tube of the ceramic round tube support body is completedA carbon nanotube film with a film thickness of 10 nm-1 μm and a film pore diameter of 0.20-10 nm, and coated on porous gamma-Al loaded with metal palladium2O3And forming an inorganic carbon nanotube film on the inner wall surface of the ceramic tube support, wherein the alcohol heating-roasting method can be replaced by an isometric dipping method, a deposition precipitation method and other methods, and the alcohol heating-roasting method is preferred.
Furthermore, the catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in the MOCVD process and the application are characterized in that CNTs are pretreated by adding a proper amount of commercially available CNTs carrier with the concentration of 10-20 nm into a proper amount of mixed solution of nitric acid with the mass concentration of 10-30% and nitric acid with the mass concentration of 50-70%, heating and stirring, carrying out azeotropic reflux for 4-8 hours, cooling to the ambient temperature, carrying out vacuum filtration, washing with deionized water to be neutral, drying the obtained filter cake at 120 ℃ for 1-2 hours, grinding into 10-20 nm powder, and roasting and cooling to form the pretreated CNTs. The pretreatment can also use sulfuric acid, mixed solution of dilute sulfuric acid and concentrated sulfuric acid, sodium hydroxide solution and potassium hydroxide solution to replace nitric acid mixed solution for azeotropic reflux, or hydrogen peroxide and phosphoric acid are used for soaking to replace nitric acid mixed solution for azeotropic reflux, or the azeotropic reflux and the soaking combination are used for replacing nitric acid mixed solution for azeotropic reflux. The preferred pretreatment is azeotropic reflux of the nitric acid mixed solution.
Furthermore, the catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in the MOCVD process and the application are characterized in that the catalytic permeable membrane reactor containing 5-10% (w/w, the same applies below) of metal palladium dispersed in porous gamma-aluminum oxide (gamma-Al)2O3) The ceramic round tube is used as a support body and is prepared by firstly soaking and calcining gamma-Al2O3The ceramic tube is dipped in palladium nitrate (Pd (NO) containing metal palladium precursor3)2) Or palladium ammonium nitrate (Pd (NH)3)4(NO2)2) Taking out the solution, then performing evacuation drying, calcining for 2-4 hours at 600-700 ℃ in inert gas atmosphere flow, and performing nitrogen purging and cooling to form a gamma-Al 2O3 ceramic round tube support containing 5-10% of metal palladium dispersed in porous material, wherein, or, the support is prepared by adoptingThe impregnation calcination method is replaced by a spray deposition method, a sol-gel method, a solid particle sintering method or other methods, and the impregnation method is preferred; or, composite ceramic of two components such as high temperature resistant stainless steel, sintered alloy, metal palladium tube and alumina-zirconia-titania is adopted as the support material to replace gamma-Al2O3Ceramic tubes, preferably of palladium and gamma-Al2O3And (3) compounding a ceramic tube support material.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application thereof are characterized in that the metals of Co and Mo which are active components of the catalyst can be replaced by oxides thereof, or single metals of Co or Mo, or one or two of noble metals, other transition metals, rare metals or corresponding metal oxides. Preferred are bimetallic Co and Mo as the catalyst active component.
Furthermore, the catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in the MOCVD process and the application are characterized in that 5-10% of metal palladium is dispersed in porous gamma-Al2O3The ceramic round tube is used as a support body, 10-30% of active component cobalt and 5-20% of molybdenum, 1-10% of cocatalyst component lanthanum and 1-5% of promoter potassium are embedded in the pretreated CNTs, and the pretreated CNTs are coated with the ceramic round tube2O3The inorganic carbon nano-film formed by the film thickness of the inner wall of the ceramic round tube being 10 nm-1 mu m and the film aperture being 0.20-10 nm can adopt pure gamma-Al without metal palladium impregnation2O3The ceramic round tube is used as a support, 5-10% of metal palladium with permselectivity, 5-20% of metal ruthenium with catalytic activity, 1-10% of lanthanum with cocatalyst and 1-5% of potassium with promoter are embedded in the pretreated CNTs and coated on pure gamma-Al2O3The inorganic carbon nanotube composite membrane with the membrane thickness of 10 nm-1 μm and the membrane aperture of 0.20-10 nm is used for replacing the ceramic round tube inner wall. Furthermore, only the active component ruthenium and the cocatalyst components lanthanum and potassium are embedded into the pretreated CNTs and coated on the inner wall of the pure alumina ceramic round tube to replace the inorganic carbon nano tube membrane which is composed of the thickness of 10 nm-100 mu m and the aperture of 0.50-10 nm. Preference is given toInstead, the components containing palladium, ruthenium, lanthanum and potassium are embedded in CNTs and coated on pure gamma-Al2O3Inorganic CNTs composite membrane formed by ceramic membrane tubes.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application thereof are characterized in that the inorganic CNTs membrane formed by the pretreated CNTs and the composite membrane material thereof can be replaced by other carbon materials such as carbon fiber (CNF), Activated Carbon (AC), carbon molecular sieve (CM), graphene and composite membrane thereof, are used for loading permselective components, catalytic active components and co-catalytic components, can be coated on a support body, and form other carbon membranes such as carbon fiber membranes, carbon molecular sieve membranes, graphene membranes and composite membranes thereof, and the preferred replacement is carbon fiber and composite membranes thereof, carbon molecular sieve membranes and composite membrane materials thereof.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application are characterized in that a raw material gas is subjected to a reaction of producing hydrogen by ammonia catalytic thermal cracking in a membrane reactor consisting of a CNTs composite membrane layer, a CNF composite membrane layer, a CM composite membrane layer and a graphene composite membrane layer, the obtained hydrogen and the hydrogen in the raw material gas selectively permeate the CNTs composite membrane layer on the inner wall of the membrane tube, enter the outer side of the membrane tube and flow out from a product gas outlet of the membrane reactor, wherein the hydrogen content is more than 99.99 percent, directly enter a PSA (pressure swing adsorption) hydrogen purification process or/and metal getter purification process to obtain a hydrogen product with the purity of more than 99.9999-99.99999 percent, are subjected to pressure regulation to the pressure required by the MOCVD process, and are returned to; the reaction gas flowing out from the inner side of the membrane tube of the membrane reactor through the outlet of the membrane reactor is completely discharged or enters the process of extracting nitrogen after being purified and deprived of a small amount of ammonia in tail gas.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application are characterized in that a plurality of inorganic CNTs membrane tubes, CNTs composite membrane layer membrane tubes, composite ceramic support membrane tubes, stainless steel, sintered alloy or metal palladium support membrane tubes in the membrane reactor can be loaded to form a tube array; meanwhile, each membrane tube can be made into a single-channel circular tube or a round or special-shaped multi-channel circular tube.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application are characterized in that gamma-Al in the membrane reactor2O3The inorganic CNTs membrane tube of the ceramic round tube or composite ceramic round tube support body can be replaced by a flat plate, hollow fibers and a shell-and-tube mode, and is preferably a round tube type; the membrane tube with the metal palladium and the sintered alloy as the support body can be replaced by a spiral type, a spiral type and a corrugated sheet type, and is preferably a circular tube type.
Furthermore, the catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in the MOCVD process and the application are characterized in that the inorganic membrane reactor and the components thereof comprise a straight tube type inorganic membrane reactor with a standard heat exchanger, a straight tube or U-shaped tube type inorganic membrane reactor with a floating head type heat exchanger, a cross-flow type inorganic membrane reactor in a cross-flow corrugated plate heat exchanger, a straight tube type inorganic membrane reactor with one end of an inorganic membrane tube capable of freely stretching and retracting, and components for connecting and sealing, such as a membrane end socket which is temperature-resistant, pressure-resistant and leak-proof, sealing elements which are enamel, ceramics, metals and organic polymers, and the sealing method comprises the steps of dipping, brushing, injecting, welding and sealing. The support is gamma-Al2O3The inorganic carbon film of ceramic or composite ceramic includes CNTs, CNF, CM and graphene film, and the two ends or one end of the film tube may be provided with glaze, gasket, O-shaped washer or vacuum grease. The connection between the ceramic or composite ceramic and the metal can adopt local cooling, metal ceramic, gland packing, graphite gasket or gasket and other measures. .
The features and properties of the present invention are described in further detail below with reference to examples.
Example 1
As shown in figure 1, a catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in MOCVD process and application thereof are disclosed, wherein the membrane reactor is prepared by dispersing metal palladium containing 7-10% (w/w, the same applies below) in porous gamma-aluminum oxide (gamma-Al)2O3) The ceramic round tube is used as a support body and contains activity15-20% of cobalt and 14-16% of molybdenum as an active component, 4-6% of lanthanum as a cocatalyst component and 3-5% of potassium as an accelerant are embedded in pretreated Carbon Nano Tubes (CNTs), and an inorganic carbon nano membrane which is coated on the inner wall of an alumina ceramic round tube and consists of a membrane with the thickness of 50nm and the membrane aperture of 0.30-0.60 nm and a component which consists of a stainless steel connecting piece, a metal ceramic sealing piece, a sealing head, a Reactor inlet and a Reactor outlet and a carbon steel jacket is formed to form a tubular Catalytic permeable membrane Reactor (CPCPSMR) of a standard heat exchanger with Catalytic activity and separation selectivity, the Catalytic thermal cracking hydrogen production reaction of ammonia is carried out according to the following steps,
(1) the raw material gas is from the production of LED-GaN epitaxial wafers, and the MOCVD epitaxial tail gas mainly comprises nitrogen (N)2) 46% (v/v, the same applies hereinafter), hydrogen (H)2) 34% of ammonia (NH)3) 19 percent, and the rest 1 percent of the total weight of the catalyst is a small amount of metal ions, particles, arsine, methane (CH4), water (H2O), carbon monoxide (CO) and carbon dioxide (CO)2) Oxygen (O)2) And other impurity components at a pressure of 0.3MPa, at ambient temperature and at a flow rate of 2,000Nm3Heating to 80-90 ℃ through a precision filter and a heat exchanger, pressurizing to 2.2-2.4 MPa through a compressor after a catalytic deoxygenator and a molecular sieve drying dehydrator, heating to 550-600 ℃ through a heater, and entering from the inlet end of the membrane reactor;
(2) the pretreated raw material gas enters from the inlet end of a membrane reactor, and is subjected to ammonia catalytic thermal cracking catalytic reaction on one side of an inorganic carbon nano membrane (inner tube) in the membrane reactor, hydrogen obtained by the reaction and hydrogen in the raw material gas selectively permeate out through one side of the inorganic carbon nano membrane (outer tube) and flow out from the outlet end of the membrane reactor to form hydrogen-rich gas, wherein the hydrogen content is 99%, the rest is a small amount of nitrogen and trace ammonia, the pressure is 1.0MPa, the temperature is 520-560 ℃, the temperature is 30-50 ℃ after being subjected to multi-stage heat exchange with the raw material gas, the hydrogen is sequentially subjected to temperature-variable adsorption refined deamination consisting of two towers, Pressure Swing Adsorption (PSA) purified hydrogen consisting of four towers and molecular sieves consisting of two towers for deep drying, the temperature is raised to 450-500 ℃ through a heat exchanger, and the hydrogen enters a metal getter process, so that a hydrogen product with the purity of more than 99.99999, according to the requirements that the pressure required by the LED-MOCVD process is 1.0MPa and the temperature is the ambient temperature, the product hydrogen is subjected to heat exchange by a plurality of stages of heat exchangers and is cooled to the ambient temperature, and then the product hydrogen is returned to the LED-MOCVD process through a delivery pump for recycling; 10-20% of reaction gas flowing through a reaction gas outlet end of the membrane reactor from the inner side of a ceramic tube of the membrane reactor returns to feed gas for circulation, and the rest of the reaction gas enters tail gas for catalytic adsorption and purification to remove a small amount of ammonia to less than 1ppm and is directly discharged.
Example 2
Based on the embodiment 1, the catalyst comprises 15-20% of active component cobalt, 14-16% of molybdenum, 460% of cocatalyst component lanthanum and 3-5% of promoter potassium, is embedded in the pretreated Carbon Nano Tubes (CNTs) and coated on gamma-aluminum oxide (gamma-Al)2O3) The inorganic CNTs membrane is formed by that the membrane thickness of the inner wall of a ceramic round tube is 50nm, the membrane aperture is 0.30-0.60 nm, the alcohol hot dissolving-roasting method is adopted, firstly, a proper amount of pretreated multi-layer Carbon Nano Tubes (CNTs) are added into a proper amount of absolute ethanol solution, after the mixture is heated and stirred to form slurry, a cobalt-molybdenum bimetallic catalyst with a certain concentration is heated to prepare a precursor of cobalt nitrate (Co (NO) which is cobalt-molybdenum bimetallic catalyst3)2) And molybdenum nitrate (Mo (NO)3)3) The mixed solution and the promoter precursor are lanthanum nitrate (La (NO)3)3) With potassium nitrate (KNO)3) Adding a certain amount of ammonia water into the mixed solution and the ethanol solution, adjusting the pH of the mixed solution to be more than 10, and repeatedly spraying for multiple times until the solution contains 7-10% of metal palladium and is dispersed in porous gamma-Al2O3Heating the inner tube of the ceramic round tube support body to 100-140 ℃, controlling the time and intensity of ultrasonic waves or microwaves to perform ultrasonic or microwave irradiation radiation and drying, wherein the total process is 2-4 h, roasting is performed for 4-8 h at 600-700 ℃ under the flowing of nitrogen, the roasting temperature rise speed is controlled to be 100-140 ℃/h, and the steps of embedding active components of cobalt and molybdenum and co-catalysis components of lanthanum and potassium on a CNTs membrane formed by the membrane thickness of 50nm and the membrane aperture of 0.30-0.60 nm, and coating the CNTs membrane on porous gamma-Al loaded with 7-10% of metal palladium2O3Inner wall surface of ceramic tube supportOn the surface, an inorganic CNTs membrane is formed, and the inorganic CNTs membrane and the components are assembled into the catalytic permeable membrane reactor for hydrogen production of ammonia-containing tail gas in the MOCVD process according to the form of a standard tubular heat exchanger.
Example 3
Based on examples 1 and 2, the pretreated CNTs in the inorganic CNTs membrane reactor are prepared by adding a proper amount of commercially available 10-20 nm CNTs carriers into a proper amount of mixed solution of 10-30% by mass of nitric acid and 50-70% by mass of nitric acid, heating and stirring, carrying out azeotropic reflux for 4-8 hours, cooling to ambient temperature, carrying out vacuum filtration, washing with deionized water for two to three times to neutrality, drying the obtained filter cake for 1-2 hours at 120 ℃, grinding into 10nm powder, roasting at 630-660 ℃ for 4-5 hours under the flowing of nitrogen, cooling to ambient temperature, roasting, and cooling.
Example 4
Based on examples 1 and 2, the pure gamma-Al 2O3 ceramic support in the inorganic CNTs membrane reactor adopts porous gamma-Al2O3The composite ceramic round tube composed of zirconium oxide and titanium oxide is used as a support body to replace the zirconium oxide and the titanium oxide, and the composite ceramic tube is firstly soaked in a metal palladium precursor palladium ammonium nitrate (Pd (NH) through a soaking-calcining method3)4(NO2)2) Taking out the solution, then carrying out evacuation drying, calcining at 600-700 ℃ in inert gas helium or argon atmosphere flow for 2-4 h, and carrying out nitrogen purging and cooling to form the gamma-Al containing 7-10% of metal palladium dispersed in the porous material2O3The composite ceramic round tube support is used for forming a membrane component in an inorganic CNTs membrane reactor.
Example 5
Based on the embodiments 1, 2 and 3, pure gamma-Al coated on the support without impregnated palladium is prepared by embedding CNTs pretreated with 7-10% of metal palladium with permselectivity, 10-15% of metal ruthenium with catalytic activity, 5-7% of lanthanum with cocatalyst and 3-5% of potassium with promoter into the CNTs2O3The inorganic CNTs composite membrane which is composed of the ceramic round tube inner wall with the membrane thickness of 60-100 nm and the membrane aperture of 0.30-0.60 nm is used for replacing the inorganic CNTs composite membrane containing 7-10% of metal palladiumDispersed porous gamma-Al2O3The ceramic round tube is used as a support body, and the inorganic CNTs membrane which contains 15-20% of active component cobalt, 14-16% of molybdenum, 4-6% of cocatalyst component lanthanum and 3-5% of promoter potassium, is embedded in the pretreated Carbon Nano Tubes (CNTs), is coated on the inner wall of the alumina ceramic round tube, has the membrane thickness of 50nm and the membrane aperture of 0.30-0.60 nm.
Example 6
As shown in fig. 2, on the basis of embodiments 1 and 5, after the feed gas is subjected to precision filtration, catalytic deoxidation, molecular sieve drying dehydration, compression, heat exchange and temperature rise, and a reaction of ammonia catalytic thermal cracking hydrogen production is performed in an inorganic CNTs composite membrane reactor composed of CNTs composite membrane layers, the obtained hydrogen and the hydrogen in the feed gas selectively permeate the CNTs composite membrane layers on the inner walls of the membrane tubes, enter the outer sides of the membrane tubes, and flow out of a product gas outlet of the composite membrane reactor to obtain a hydrogen-rich gas, wherein the hydrogen content is more than 99.99%, and the hydrogen directly enters a PSA purified hydrogen and metal getter purified process to obtain a hydrogen product with a purity of more than 99.9999-99.99999%, and is subjected to heat exchange to an ambient temperature, and the pressure is adjusted to 1.0MPa required by an MOCVD process, and returned to the MOCVD process for recycling; and (3) the reaction gas flowing out from the inner side of the membrane tube of the CNTs composite membrane reactor through the reaction gas outlet of the membrane reactor enters tail gas to be purified and a small amount of ammonia is removed, and then the reaction gas is directly discharged.
Example 7
According to fig. 2, on the basis of embodiments 1 and 5, the pretreated raw material gas is subjected to a reaction of hydrogen production by ammonia catalytic thermal cracking through a membrane tube reactor composed of CNTs composite membrane layers, the obtained hydrogen and the hydrogen in the raw material gas selectively permeate the CNTs composite membrane layers on the inner wall of the ceramic membrane tube, enter the outer side of the ceramic membrane tube and flow out of the top of the membrane reactor to obtain hydrogen-rich gas, wherein the purity of the hydrogen is 99.99%, the hydrogen is directly subjected to PSA purification hydrogen and low-temperature metal getter purification after the heat exchange temperature is reduced to 60-90 ℃, a hydrogen product with a purity of more than 99.99999% is obtained, and the hydrogen product is reduced to the ambient temperature through a heat exchanger and returned to the process for recycling; and the gas flowing through the top of the membrane reactor from the inner side of the ceramic tube of the membrane reactor enters tail gas to be purified and a small amount of ammonia is removed, and then the gas is directly discharged.
It should be apparent that the above-described embodiments are only some, but not all, of the embodiments of the present invention. All other embodiments and structural changes that can be made by those skilled in the art without inventive effort based on the embodiments described in the present invention or based on the teaching of the present invention, all technical solutions that are the same or similar to the present invention, are within the scope of the present invention.
Claims (10)
1. A catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas by MOCVD process is characterized by comprising a support body and a carbon material which can be used for loading a permeability selection component, a catalytic active component, a cocatalyst component and a promoter and can be coated on the support body to form a membrane, wherein the support body takes one or two composite ceramics of gamma-aluminum oxide, high-temperature-resistant stainless steel, sintered alloy, metal palladium and alumina-zirconia-titanium oxide as a support body material, the catalytic active component at least comprises one transition metal, rare metal or corresponding metal oxide, and the carbon material comprises carbon nano tubes, carbon fibers, activated carbon, carbon molecular sieves and graphene.
2. The catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in MOCVD process of claim 1, wherein the membrane reactor comprises an inorganic carbon nano-membrane which is formed by taking a gamma-alumina ceramic round tube containing 5-10% (w/w) of metal palladium dispersed in porous as a support, containing 10-30% (w/w) of active components cobalt and 5-20% (w/w) of molybdenum, containing 1-10% (w/w) of co-catalyst components lanthanum and 1-5% (w/w) of promoter potassium, embedding the membrane into a pretreated carbon nano-tube, coating the membrane on the inner wall of the support, and having a thickness of 10 nm-1 μm and a membrane pore diameter of 0.20-10 nm.
3. The catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in MOCVD process according to claim 1, wherein the membrane reactor comprises an inorganic carbon nanotube composite membrane which is formed by using a pure gamma-aluminum oxide ceramic round tube as a support, contains 5-10% (w/w) of metal palladium with permselectivity, 5-20% (w/w) of metal ruthenium with catalytic activity, 1-10% (w/w) of lanthanum with co-catalyst and 1-5% (w/w) of potassium with promoter, embedded in a pretreated carbon nanotube and coated on the inner wall of the support, and has a membrane thickness of 10 nm-1 μm and a membrane aperture of 0.20-10 nm.
4. The catalytic permeable membrane reactor for producing hydrogen from ammonia-containing exhaust gas in MOCVD process according to claim 1, wherein the support and the membrane tubes formed in the support are in one of circular tube type, flat plate type, hollow fiber type, shell-and-tube type, spiral type, and corrugated sheet type.
5. The catalytic permeable membrane reactor for producing hydrogen from ammonia-containing exhaust gas of MOCVD process of claim 4, wherein the membrane reactor comprises a plurality of supports, and the membrane inside each support can be made into a single-channel circular tube or a round or irregular multi-channel circular tube.
6. A preparation method of a catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas in an MOCVD process is characterized in that,
1) preparing a support body which takes one or two of gamma-aluminum oxide, high-temperature resistant stainless steel, sintered alloy, metal palladium and alumina-zirconia-titanium oxide composite ceramics as a support body material by one of a spray-dip calcination method, a mist deposition method, a sol-gel method or a solid particle sintering method;
2) embedding at least one of a loaded permeability selection component, a catalytic active component, a cocatalyst component and a promoter into a carbon material of pretreated carbon nanotubes, carbon fibers, activated carbon, carbon molecular sieves and graphene by one of an alcohol hot-melting-roasting method, an equal-volume impregnation method or a deposition-precipitation method, wherein the catalytic active component at least comprises a transition metal, a rare metal or a corresponding metal oxide;
3) coating or spraying the carbon material of step 2) on the support of step 1).
7. The method of claim 6, wherein the MOCVD process ammonia-containing tail gas hydrogen production catalytic permeable membrane reactor is prepared by a method comprising the steps of,
in the step 1), a porous gamma-aluminum oxide ceramic round tube containing 5-10% (w/w) of metal palladium is dispersed as a support, and the support is prepared by dipping a gamma-aluminum oxide ceramic tube into a palladium nitrate or palladium ammonium nitrate solution containing a metal palladium precursor, taking out the dipped gamma-aluminum oxide ceramic tube, then performing evacuation drying, calcining at 600-700 ℃ for 2-4 h in inert gas atmosphere flow, and cooling by nitrogen purging to form the porous gamma-aluminum oxide ceramic round tube support containing 5-10% of metal palladium;
in the step 2), embedding 10-30% (w/w) of cobalt and 5-20% (w/w) of molybdenum containing active components, 1-10% (w/w) of lanthanum containing a cocatalyst and 1-5% (w/w) of potassium containing a promoter into the pretreated carbon nano tube, adding a proper amount of the pretreated carbon nano tube into a proper amount of absolute ethyl alcohol or polyvinyl alcohol solution through an alcohol hot-dissolving-roasting method, heating and stirring to form a slurry, heating a cobalt-molybdenum bimetallic catalyst with a certain concentration to prepare a precursor which is a mixed solution of cobalt nitrate and molybdenum nitrate, wherein the cocatalyst precursor is a mixed solution of lanthanum nitrate and potassium nitrate and an ethanol or polyvinyl alcohol solution, adding a certain amount of ammonia water, and adjusting the pH of the mixed solution to be more than 10;
in the step 3), the mixed solution prepared in the step 2 is coated or sprayed into an inner tube of the porous gamma-alumina ceramic round tube support containing 5-10% (w/w) of metal palladium, the inner tube is heated to 100-140 ℃, ultrasonic or microwave irradiation and drying are carried out by controlling the time and the intensity of ultrasonic waves or microwaves, the total process is 2-4 h, roasting is carried out for 4-8 h at 600-700 ℃ under the flowing of nitrogen, the roasting temperature rise speed is controlled at 100-140 ℃/h or 100-140 ℃/2h, or the interval combination of the temperature rise speeds is controlled, and the inorganic carbon nanotube membrane containing the active component cobalt molybdenum, the co-catalytic component lanthanum and potassium, the membrane thickness is 10 nm-1 mu m, and the membrane aperture is 0.20-10 nm is formed.
8. The method of claim 6, wherein pure γ -alumina ceramic round tube without metal palladium impregnation is used as support; embedding 5-10% (w/w) of metal palladium with osmotic selectivity, 5-20% (w/w) of metal ruthenium with catalytic activity, 1-10% (w/w) of co-catalyst component lanthanum and 1-5% (w/w) of promoter potassium into the pretreated carbon nano tube, and coating the inorganic carbon nano tube composite membrane on the inner wall of a pure gamma-alumina ceramic round tube to form the inorganic carbon nano tube composite membrane with the membrane thickness of 10-1 mu m and the membrane aperture of 0.20-10 nm.
9. The preparation method of the catalytic permeable membrane reactor for hydrogen production from ammonia-containing tail gas in MOCVD process according to any of claims 6 to 8, characterized in that the pretreatment of the carbon nanotube comprises adding a proper amount of commercially available 10-20 nm carbon nanotube carrier into a proper amount of mixed solution of 10-30% by mass nitric acid and 50-70% by mass nitric acid, heating and stirring, performing azeotropic reflux for 4-8 hours, cooling to ambient temperature, vacuum filtering, washing with deionized water to neutrality, drying the obtained filter cake at 120 ℃ for 1-2 hours, grinding into 10-20 nm powder, and roasting and cooling to form the pretreated carbon nanotube.
10. The application of the catalytic permeable membrane reactor for preparing hydrogen from ammonia-containing tail gas by the MOCVD process is characterized in that:
the catalytic thermal cracking hydrogen production reaction of ammonia is carried out according to the following steps,
(1) the raw material gas comes from the production of LED-GaN epitaxial wafers, and the MOCVD epitaxial tail gas typically comprises N2:40～60％(v/v)，H2:25～35％(v/v)，NH314-24% (v/v), the rest including trace metal ions, particulate matter, methane and oxide;
(2) before the feed gas enters the membrane reactor, the impurity components in the feed gas are removed through a pretreatment process consisting of a precision filter, a catalytic deoxidation and molecular sieve dryer, a compressor and a heat exchanger or a heater, and the feed gas is pressurized and heated to 2.0-5.0 MPa and 400-600 ℃;
(3) the catalytic reaction temperature is 400-600 ℃, the reaction pressure is 2.0-5.0 MPa, and the industrial scale for treating tail gas is 50-5,000 Nm3/h；
(4) The method comprises the following steps of (1) feeding pretreated raw material gas from an inlet of a membrane reactor, carrying out ammonia catalytic pyrolysis catalytic reaction on one side of an inorganic carbon nano membrane inner tube in the membrane reactor, selectively permeating hydrogen obtained by reaction and hydrogen in the raw material gas out through one side of an inorganic carbon nano membrane outer tube, and flowing out from an outlet of the membrane reactor, wherein the hydrogen content is 98-99.9%, and the balance of a small amount of nitrogen and a trace amount of ammonia gas, sequentially feeding the hydrogen into adsorption fine deamination, Pressure Swing Adsorption (PSA) for hydrogen purification, deep drying and metal getter to obtain a hydrogen product with the purity of more than 99.9999-99.99999%, adjusting the pressure required by an LED-MOCVD process through the pressure, and returning the hydrogen product to the MOCVD process for recycling; the gas after reaction from one side of the inner tube of the inorganic carbon nano membrane in the membrane reactor flows out from a reaction gas outlet of the membrane reactor, one part of the gas returns to the feed gas circulation, and the other part of the gas enters tail gas purification to remove a small amount of ammonia, or is directly discharged, or enters a process of extracting nitrogen.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201911419118.7A CN111137853A (en) | 2019-12-31 | 2019-12-31 | Catalytic permeable membrane reactor for producing hydrogen from ammonia-containing tail gas in MOCVD (metal organic chemical vapor deposition) process, and preparation method and application thereof |
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| KR20220094475A (en) * | 2020-12-29 | 2022-07-06 | 한국화학연구원 | Carbon Molecular Sieve Membrane for Hydrogen Gas Separation and Manufacturing Method of Hydrogen Gas Based on Ammonia Decomposition |
| CN115010087A (en) * | 2022-08-08 | 2022-09-06 | 浙江百能科技有限公司 | HI decomposition hydrogen production membrane reactor and hydrogen production method and system thereof |
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| CN115010087B (en) * | 2022-08-08 | 2022-11-11 | 浙江百能科技有限公司 | HI decomposition hydrogen production membrane reactor and hydrogen production method and system thereof |
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