Membrane reactor for reaction-separation coupling process

Abstract

The utility model belongs to the technical field of carbon dioxide hydro-conversion, particularly relates to a membrane reactor for a reaction-separation coupling process, and aims to solve the problem of performance failure of the membrane reactor in a high-temperature environment in the background technology, the following scheme is provided: the membrane reactor comprises a reaction tube body, end covers are screwed on the outer walls of two ends of the reaction tube body, and the end covers are screwed on the outer walls of two ends of the reaction tube body; a product gas outlet is welded to one end of the outer wall of the bottom of the reaction tube body, a feed gas inlet is welded to the other end of the outer wall of the top of the reaction tube body, and a purge gas outlet is welded to the outer wall of one side of one end cover. The NaA molecular sieve membrane loaded by the ceramic hollow fiber carrier is adopted, a compact and defect-free zeolite membrane layer is formed through a multi-time in-situ growth process, the membrane can still keep a stable hydrophilic nano channel (the aperture is 0.4 nm) at the temperature of 300-400 DEG C and the high pressure of 4 MPa, water molecules are preferentially adsorbed and permeated, the thermodynamic equilibrium limitation is effectively broken, and compared with a traditional molecular sieve membrane, the membrane has the advantages that the membrane is simple in structure and convenient to use, and the cost is low. The thermal stability is obviously improved.

Description

Technical Field

[0001] This utility model relates to the field of carbon dioxide hydrogenation conversion technology, and in particular to a membrane reactor for a reaction-separation coupled process. Background Technology

[0002] Carbon dioxide hydrogenation conversion technology is an important pathway to achieving carbon recycling and green chemical engineering. By catalytically converting carbon dioxide and hydrogen into chemicals such as methanol and hydrocarbons, it not only reduces greenhouse gas emissions but also improves resource utilization efficiency. This technology typically involves photochemical, electrochemical, and thermochemical methods, among which thermocatalytic hydrogenation has attracted much attention due to its mature process and ease of scalability. During the reaction, the formation of water as a byproduct can lead to thermodynamic equilibrium limitations and reduce the conversion rate. To address this, existing technologies often employ membrane reactors to couple the reaction and separation processes, selectively separating the water byproduct to drive the reaction forward while simultaneously reducing catalyst deactivation.

[0003] However, existing membrane reactors still have some shortcomings in applications under high temperature and high pressure conditions. First, conventional molecular sieve membranes (such as ZSM-5 and FAU) are prone to structural collapse or pore deformation in high-temperature and high-pressure environments above 300°C, leading to a decrease in separation efficiency. Second, traditional sealing methods (such as rubber O-rings) are prone to aging and failure at high temperatures, causing gas leakage and affecting the maintenance of the pressure difference across the membrane. In addition, problems such as uneven catalyst distribution and low mass transfer efficiency in fixed-bed reactors limit the reaction rate, while frequent adsorbent regeneration processes further increase energy consumption. Current technologies have not yet effectively solved the synergistic optimization problem of membrane material stability, sealing reliability, and efficient catalyst utilization under high temperature and high pressure conditions. Utility Model Content

[0004] To address the shortcomings of existing technologies, this invention provides a membrane reactor for a reaction-separation coupled process, which overcomes the deficiencies of existing technologies and effectively solves the problem of membrane reactor performance failure under high-temperature environments.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A membrane reactor for a reaction-separation coupled process includes a reaction tube, with end caps screwed to the outer walls of both ends of the reaction tube. A product gas outlet is welded to one end of the bottom outer wall of the reaction tube, and a raw material gas inlet is welded to the other end of the top outer wall of the reaction tube. A purge gas outlet is welded to one side of the outer wall of one end cap, and a purge gas inlet is welded to one side of the outer wall of the other end cap.

[0007] The product gas outlet and the raw material gas inlet are screwed to the outer wall of one end with an adapter. The inside of the reaction tube is provided with a NaA molecular sieve membrane, and a catalyst filling layer is provided between the reaction tube and the NaA molecular sieve membrane.

[0008] Preferably, the adapter includes a stainless steel sleeve screwed onto the outer wall of one end of the product gas outlet and the raw material gas inlet, and a gas connection welded onto the outer wall of one end of the stainless steel sleeve.

[0009] Preferably, the NaA molecular sieve membrane comprises ceramic hollow fibers and a zeolite membrane, wherein the zeolite membrane is disposed on the outer surface of the ceramic hollow fibers and is tightly attached to the inner wall of the catalyst filling layer.

[0010] Preferably, graphite sealing gaskets are provided on the inner walls of both end caps, and the graphite sealing gaskets and the NaA molecular sieve membrane are interference-fitted.

[0011] Preferably, a limiting ring is fixedly connected to the inner wall of each of the two end caps, and the graphite sealing gasket is tightly attached to the outer wall of the limiting ring.

[0012] Preferably, the outer wall of the NaA molecular sieve membrane is provided with hydrophilic nanochannels, and the pore size of the hydrophilic nanochannels is about 0.4 nm.

[0013] Preferably, a gap for filling the catalyst filling layer is provided between the reaction tube and the outer wall of the NaA molecular sieve membrane, and the thickness of the gap is 1.5 mm.

[0014] The beneficial effects of this utility model are as follows:

[0015] 1. The membrane reactor for the reaction-separation coupling process designed in this paper employs a NaA molecular sieve membrane supported on a ceramic hollow fiber carrier, forming a dense and defect-free zeolite membrane layer through multiple in-situ growth processes. This membrane can maintain stable hydrophilic nanochannels (pore size 0.4 nm) at 300-400℃ and 4MPa high pressure, preferentially adsorbing and permeating water molecules, effectively breaking the thermodynamic equilibrium limitation, and its thermal stability is significantly improved compared with traditional molecular sieve membranes;

[0016] 2. The membrane reactor in this reaction-separation coupled process design solves the sealing failure problem caused by the axial expansion of the NaA molecular sieve membrane at high temperatures through the interference fit design of the flexible graphite gasket and the limiting ring. The graphite gasket is heat-resistant up to 800℃ and can still achieve zero leakage at 400℃ and a pressure difference of 4 MPa. Furthermore, the counter-current purge gas design enhances the water molecule removal efficiency, maintains the partial pressure difference across the membrane, reduces catalyst sintering and poisoning caused by water accumulation, and extends service life. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the overall structure of a membrane reactor for a reaction-separation coupling process proposed in this utility model;

[0018] Figure 2This is a schematic diagram of the connection structure between the reaction tube and the end cap of a membrane reactor for a reaction-separation coupling process proposed in this utility model;

[0019] Figure 3 This is a schematic diagram showing the overall structure of a membrane reactor for a reaction-separation coupling process proposed in this utility model.

[0020] Figure 4 This is a schematic diagram of the internal connection structure of the reaction tube of a membrane reactor for a reaction-separation coupling process proposed in this utility model;

[0021] Figure 5 This is a schematic diagram of the NaA molecular sieve membrane structure of a membrane reactor for a reaction-separation coupled process proposed in this utility model.

[0022] In the diagram: 1. Reaction tube body; 2. End cap; 3. Product gas outlet; 4. Raw material gas inlet; 5. Purge gas outlet; 6. Purge gas inlet; 7. Adapter; 71. Stainless steel ferrule; 72. Gas connection; 8. NaA molecular sieve membrane; 81. Ceramic hollow fiber; 82. Zeolite membrane; 9. Graphite gasket; 10. Catalyst packing layer; 11. Limiting ring. Detailed Implementation

[0023] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present utility model. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments.

[0024] Reference Figures 1-5 Example 1: A membrane reactor for a reaction-separation coupled process includes a reaction tube 1. End caps 2 are screwed to the outer walls of both ends of the reaction tube 1. A product gas outlet 3 is welded to one end of the bottom outer wall of the reaction tube 1, and a raw material gas inlet 4 is welded to the other end of the top outer wall of the reaction tube 1. A purge gas outlet 5 is welded to one side of the outer wall of one end cap 2, and a purge gas inlet 6 is welded to one side of the outer wall of the other end cap 2.

[0025] The feed gas enters through feed gas inlet 4, reacts in the catalyst bed, and exits through product gas outlet 3. The purge gas inlet 6 is introduced into the permeate side, and carries water molecules countercurrently to exit through purge gas outlet 5, maintaining the partial pressure difference.

[0026] Example 2: A membrane reactor for a reaction-separation coupled process, wherein a connector 7 is screwed to the outer wall of one end of the product gas outlet 3 and the feed gas inlet 4, a NaA molecular sieve membrane 8 is disposed inside the reaction tube 1, and a catalyst filling layer 10 is disposed between the reaction tube 1 and the NaA molecular sieve membrane 8, the connector 7 includes a stainless steel sleeve 71 screwed to the outer wall of one end of the product gas outlet 3 and the feed gas inlet 4, and a gas passage connector 72 welded to the outer wall of one end of the stainless steel sleeve 71, the NaA molecular sieve membrane 8 includes a ceramic hollow fiber 81 and a zeolite membrane 82, wherein the zeolite membrane 82 is disposed on the outer surface of the ceramic hollow fiber 81, and the zeolite membrane 82 is tightly attached to the inner wall of the catalyst filling layer 10.

[0027] The NaA molecular sieve membrane 8 is composed of ceramic hollow fiber 81 as a carrier and a surface zeolite membrane 82. After being modified with APTES, the ceramic hollow fiber 81 is reacted in a hydrothermal synthesis reactor with a solution of Na2O: Al2O3: SiO2: H2O = 50:1:5:1000 at 60°C for 24 hours to form a dense membrane layer with a thickness of 20 μm.

[0028] The catalyst (Fe-Co / Al2O3) was quantitatively filled into the 1.5 mm voids at a rate of 4 g to prevent airflow disturbance. After filling, the NaA molecular sieve membrane 8 was exposed at both ends by 3 mm to ensure that the graphite sealing gasket 9 was completely wrapped.

[0029] Graphite sealing gaskets 9 are provided on the inner walls of both end caps 2, and the graphite sealing gaskets 9 and the NaA molecular sieve membrane 8 are interference-fitted. Limiting rings 11 are fixedly connected to the inner walls of both end caps 2, and the graphite sealing gaskets 9 are tightly attached to the outer wall of the limiting rings 11.

[0030] The reaction tube 1 is connected to end caps 2 by threads at both ends. A limiting ring 11 is provided on the inner wall of the end cap 2, and a graphite sealing gasket 9 is embedded between the limiting ring 11 and the NaA molecular sieve membrane 8. Radial pressure is applied by tightening the end cap 2 to ensure sealing at high temperatures.

[0031] The outer wall of the NaA molecular sieve membrane 8 is provided with hydrophilic nanochannels, and the pore size of the hydrophilic nanochannels is about 0.4 nm. A gap for filling the catalyst filling layer 10 is provided between the reaction tube 1 and the outer wall of the NaA molecular sieve membrane 8, and the thickness of the gap is 1.5 mm.

[0032] Working Principle: During operation, the feed gas (CO2 / H2) enters the reaction tube 1 through the feed gas inlet 4, flows through the catalyst packing layer 10, and undergoes a hydrogenation reaction to produce hydrocarbons and water. Water molecules, a byproduct, permeate through the hydrophilic channels of the NaA molecular sieve membrane 8 to the inner side of the membrane and are continuously carried out of the system by the counter-current purge gas (such as nitrogen). The partial pressure difference across the NaA molecular sieve membrane 8 (4 MPa on the permeate side, atmospheric pressure on the permeate side) drives efficient water molecule separation, shifting the reaction equilibrium towards the product side. The catalyst in the catalyst packing layer 10 is uniformly distributed in 1.5 mm pores, ensuring high space velocity consistency and preventing localized overheating or carbon buildup. The graphite sealing gasket 9 adapts to the expansion of the NaA molecular sieve membrane 8 at high temperatures, ensuring complete isolation between the reaction side and the permeate side. Finally, the converted gas exits from the product gas outlet 3 and, after separation, yields high-value-added chemicals.

[0033] The above description is only a preferred embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Any equivalent substitutions or changes made by those skilled in the art within the technical scope disclosed in the present utility model, based on the technical solution and the inventive concept of the present utility model, should be included within the protection scope of the present utility model.

Claims

1. A membrane reactor for a reaction-separation coupled process, comprising a reaction tube (1), characterized in that, Both ends of the reaction tube (1) are screwed with end caps (2), and one end of the bottom outer wall of the reaction tube (1) is welded with a product gas outlet (3), and the other end of the top outer wall of the reaction tube (1) is welded with a raw material gas inlet (4). One of the end caps (2) is welded with a purge gas outlet (5) on one side of its outer wall, and the other end cap (2) is welded with a purge gas inlet (6) on one side of its outer wall. The product gas outlet (3) and the raw material gas inlet (4) are screwed with an adapter (7) on one end of the outer wall. The reaction tube (1) is provided with a NaA molecular sieve membrane (8), and a catalyst filling layer (10) is provided between the reaction tube (1) and the NaA molecular sieve membrane (8).

2. The membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, The adapter (7) includes a stainless steel sleeve (71) screwed onto the outer wall of one end of the product gas outlet (3) and the raw material gas inlet (4), and a gas connection (72) welded onto the outer wall of one end of the stainless steel sleeve (71).

3. The membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, The NaA molecular sieve membrane (8) includes a ceramic hollow fiber (81) and a zeolite membrane (82), wherein the zeolite membrane (82) is disposed on the outer surface of the ceramic hollow fiber (81) and the zeolite membrane (82) is attached to the inner wall of the catalyst filling layer (10).

4. The membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, Graphite gaskets (9) are provided on the inner walls of both end caps (2), and the graphite gaskets (9) and the NaA molecular sieve membrane (8) are interference-fitted.

5. A membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, Limiting rings (11) are fixedly connected to the inner walls of both end caps (2), and graphite sealing gaskets (9) are tightly attached to the outer wall of the limiting rings (11).

6. A membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, The outer wall of the NaA molecular sieve membrane (8) is provided with hydrophilic nanochannels, and the pore size of the hydrophilic nanochannels is about 0.4 nm.

7. A membrane reactor for a reaction-separation coupled process according to claim 1, characterized in that, A gap for filling the catalyst filling layer (10) is provided between the reaction tube (1) and the outer wall of the NaA molecular sieve membrane (8), and the thickness of the gap is 1.5 mm.

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