Gas catalytic oxidation device

Abstract

The present application relates to a kind of gas catalytic oxidation device, belong to gas utilization technical field.The device includes catalytic oxidation chamber;Gas containing gas flows from one end of catalytic oxidation chamber to the other end;Catalytic oxidation chamber includes porous material;Porous material is arranged on the flow path of the gas;Porous material is loaded with catalyst, and catalyst is used for catalytic oxidation methane;Porous material includes porous skeleton made of carbon fiber material, carbon fiber surface is compounded with antioxidant layer, and antioxidant layer is non-conductive material;Porous skeleton includes the conductive heating loop made of carbon fiber material;The power transmission line of conductive heating loop is communicated to the outside of catalytic oxidation chamber.The carbon fiber material with antioxidant layer is made into porous skeleton as the carrier of catalyst in the present application, realizes the unity of gas heating position and gas catalytic position, cancels the heat storage body component commonly used in prior art, and device starting process is rapid, and device operating state is stable.

Description

Technical Field

[0001] This invention belongs to the field of gas utilization technology, and specifically relates to a gas catalytic oxidation device. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Methane gas refers to unconventional natural gas that is generated and stored spontaneously by coal-forming materials during the coal-forming process in coal-bearing strata. Its main component is methane. In unmined areas, the methane concentration in methane extracted directly from wells exceeds 90%, making it directly usable. However, this type of methane accounts for less than 5% of the total methane in the coal seam. More often, methane leaks slowly and gradually from the coal-bearing strata during mining, causing the concentration in the working environment to gradually increase. To ensure production safety, large amounts of air are introduced to dilute the methane, and the methane-containing ambient gases are extracted from the working environment. This portion of the methane has a concentration far below its explosive limit and cannot burn under natural conditions, releasing directly into the atmosphere. This not only wastes resources but also causes serious greenhouse gas pollution.

[0004] Current low-concentration methane utilization systems typically include a combustion chamber and a heat storage device. The combustion chamber contains a catalytic oxidation device or a combustion supplement device to oxidize and decompose methane in the methane, releasing chemical energy as heat. The heat storage device stores the heat released in the combustion chamber, preheats the gas entering the combustion chamber, or exchanges heat with other devices. However, the heat storage device and the combustion chamber are not always perfectly aligned. The heat accumulation process in the heat storage device lags behind the methane oxidation process in the combustion chamber, resulting in poor preheating effect and slow system startup. Large fluctuations in the methane concentration in the gas entering the combustion chamber can also lead to unstable equipment operation, resulting in incomplete combustion and waste of some methane during operation.

[0005] Ceramic materials with poor thermal conductivity are often used in heat storage bodies, partly because of their good heat insulation properties and partly because of their stability at high temperatures. Carbon fiber is a good thermal conductor, but it is rarely used as a heat storage material, partly because it is easily oxidized at high temperatures and its chemical properties are unstable. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a gas catalytic oxidation device, comprising a porous material loaded with a catalytic oxidant. The porous material is made of carbon fiber with an added anti-oxidation layer on its surface, and the temperature conditions for catalytic oxidation are provided by utilizing the electrothermal effect of the carbon fiber.

[0007] To achieve the above objectives, the technical solution of the present invention is as follows:

[0008] In a first aspect, a gas catalytic oxidation device includes: a catalytic oxidation chamber; a gas containing gas flows from one end of the catalytic oxidation chamber to the other end;

[0009] The catalytic oxidation chamber includes a porous material; the porous material is disposed in the gas flow path;

[0010] The porous material is loaded with a catalyst, which is used to catalyze the oxidation of methane.

[0011] The porous material includes a porous skeleton made of carbon fiber material, and the surface of the carbon fiber is coated with an antioxidant layer, which is a non-conductive material.

[0012] The porous framework includes a conductive heating circuit made of carbon fiber material; the power transmission line of the conductive heating circuit is connected to the outside of the catalytic oxidation chamber.

[0013] Secondly, the method for catalytic oxidation of gas containing methane using the aforementioned gas catalytic oxidation device includes the following processes:

[0014] S1. The conductive heating circuit in the porous skeleton is turned on, heating the porous material to the set temperature;

[0015] S2. Introduce a gas-containing gas into the catalytic oxidation chamber, allowing the gas to pass through the micropores in the porous material;

[0016] S3. The combustible components in the gas containing methane are oxidized and decomposed under the catalysis of the catalyst, releasing heat, and the resulting high-temperature gas is discharged from the catalytic oxidation chamber.

[0017] S4. When the proportion of combustible components in the gas fluctuates, the control device adjusts the opening of different conductive heating circuits according to the temperature fluctuation in the catalytic oxidation chamber in order to stabilize the catalytic reaction temperature in the catalytic oxidation chamber.

[0018] The beneficial effects of this invention are as follows:

[0019] 1. This invention adds an anti-oxidation layer to the surface of carbon fiber and makes the carbon fiber material with the anti-oxidation layer into a porous skeleton, which serves as a catalyst carrier, enabling the carbon fiber material to serve under heating conditions for a long time. This achieves the unification of the gas heating position and the gas catalysis position, eliminates the heat storage body component commonly used in the prior art, and makes the device smaller and lighter. In addition, the device starts up quickly and the amount of methane wasted during the start-up process is small.

[0020] 2. This invention uses carbon fiber material to make a porous skeleton. By utilizing the electrical and thermal conductivity of carbon fiber, methane-containing gas is heated to reach the catalytic oxidation temperature. The electric heating power can be flexibly adjusted according to the fluctuation of methane content in the input gas. The device is less affected by the fluctuation of methane content during operation and has a high degree of stability. Attached Figure Description

[0021] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0022] Figure 1 This is a schematic diagram of the gas catalytic oxidation device in Example 1.

[0023] Figure 2 This is a schematic diagram of the catalyst and catalyst support in Example 1.

[0024] The components include: 1. Catalytic oxidation chamber; 2. Porous material; 3. Carbon fiber; 4. Antioxidant layer; 5. Catalyst; 6. Baffled gas distribution device; 7. Inlet pipe; 8. Outlet pipe; and 9. Pyrolytic carbon coating. Detailed Implementation

[0025] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0026] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0027] Example 1

[0028] A gas catalytic oxidation device, such as Figure 1 As shown, it includes: a catalytic oxidation chamber 1; a gas containing methane flows from one end of the catalytic oxidation chamber to the other end. Figure 1 The dashed lines with arrows indicate the direction of gas flow containing methane.

[0029] The catalytic oxidation chamber includes a porous material 2; the porous material 2 is disposed in the gas flow path;

[0030] The porous material 2 is loaded with a catalyst, which is used to catalyze the oxidation of methane;

[0031] like Figure 2 As shown, the porous material 2 includes a porous skeleton made of carbon fiber 3, and an anti-oxidation layer 4 composite on the surface of the carbon fiber 3. The anti-oxidation layer 4 is a non-conductive material.

[0032] The porous framework includes a conductive heating circuit made of carbon fiber material; the power transmission line of the conductive heating circuit is connected to the outside of the catalytic oxidation chamber.

[0033] Through the above setup, carbon fiber material with an antioxidant layer is made into a porous skeleton to serve as a catalyst carrier, enabling the carbon fiber material to operate under heating conditions for a long time. This unifies the gas heating position and the gas catalytic position, eliminates the heat storage components commonly used in existing technologies, and allows the device to start up quickly. It can also sensitively adjust the heat generation of the conductive heating circuit according to the methane concentration, reducing methane waste.

[0034] Optionally, the catalyst includes a catalytically active component, which may include one or more of palladium, platinum, rhodium, and iridium.

[0035] Optionally, the catalyst may include a catalyst promoter, which may include a metal oxide.

[0036] Specifically, it includes one or more of zinc oxide, zirconium oxide, nickel oxide, and titanium oxide.

[0037] Optionally, the catalyst's activation temperature is 300–500°C.

[0038] Optionally, the catalyst preparation method includes:

[0039] Step 1: Impregnate the catalyst support with a precursor solution of catalyst promoter, dry and then calcine;

[0040] Step 2: Impregnate the catalyst support with a precursor solution of the catalyst active component, dry it, and then calcine it.

[0041] Preferably, in step one, the precursor solution of the catalyst promoter includes a metal nitrate solution, specifically, one or more of zinc nitrate solution, zirconium nitrate solution, nickel nitrate solution, and titanium nitrate solution; the calcination temperature is 600-700℃, and the calcination time is 1-3h.

[0042] Preferably, in step two, the precursor solution of the catalyst active component includes a chloride salt of the catalyst active component, or an acid containing the catalyst active component; specifically, it includes one or more of the following: platinum chloride solution, chloroplatinic acid solution, chloropalladium acid solution, chlororhodium acid solution, and chloroiridium acid solution, with a calcination temperature of 600-700°C and a calcination time of 1-3 hours.

[0043] Through the above preparation methods, such as Figure 2 As shown, catalyst 5 is obtained by loading a catalyst support, which is carbon fiber 3 in a porous skeleton coated with an antioxidant layer 4. During the process of gas containing methane passing through the porous skeleton, catalyst 5 catalytically oxidizes the methane in the gas. The catalytic oxidation temperature is lower than the combustion temperature of methane, which can completely oxidize methane with too low a concentration.

[0044] Optionally, the antioxidant components of the antioxidant layer include one or more of silicon oxide, aluminum oxide, silicon carbide, and zirconium boride.

[0045] Optional, such as Figure 2 As shown, the antioxidant layer 4 is prepared on the surface of the fiber material including carbon fiber 3 in the porous skeleton after the porous skeleton is prepared.

[0046] Optionally, the preparation process of antioxidant layer 4 includes:

[0047] Step 1: Prepare a pyrolytic carbon coating on the surface of the porous framework;

[0048] Step 2: Prepare an antioxidant layer 4 on the surface of the pyrolytic carbon coating 9.

[0049] Preferably, in step one, the method for preparing the pyrolytic carbon coating 9 includes: preparing the pyrolytic carbon coating on the surface of the porous skeleton by vapor deposition; specifically, propane is used as the carbon source gas, argon is used as the carrier gas, and the deposition temperature is 800-1000℃; the purpose of deposition is to prepare a transition layer between the carbon fiber 3 and the antioxidant layer 4 to enhance the bonding ability between the antioxidant layer 9 and the carbon fiber 3.

[0050] Preferably, in step two, the method for preparing the antioxidant layer includes: uniformly dispersing the powder of the antioxidant component in a siloxane liquid, immersing the siloxane liquid doped with the powder of the antioxidant component onto the surface of the porous skeleton, and then performing overall calcination and curing; specifically, the calcination and curing process includes: calcining at a temperature of 800 to 1300°C and a calcination time of 1 to 3 hours under an inert atmosphere.

[0051] The above preparation method yields a porous framework coated with an antioxidant layer. The thickness of the antioxidant layer is approximately 10–200 μm, retaining the porous characteristics of the framework and allowing gas to pass through.

[0052] During the preparation of porous materials, the calcination temperature of the antioxidant layer is higher than that of the catalyst, and the calcination temperature of the catalyst is higher than that of the heating and maintenance temperature of the porous materials during the operation of the gas catalytic oxidation device of the present invention.

[0053] Optionally, the porous skeleton is a felt or fabric made of raw materials including carbon fiber and other fibers, with a pore size of 0.5 to 2 mm, and the conductive heating circuit is uniformly distributed in the porous skeleton.

[0054] Optionally, other fibers include one or more of silicon carbide fibers, alumina fibers, boron nitride fibers, and boron carbide fibers.

[0055] Optionally, the conductive heating circuit includes an electric heating wire evenly distributed in the porous skeleton. The electric heating wire is woven from carbon fiber and other fiber raw materials. The mixing ratio of other fibers and carbon fiber can be flexibly adjusted according to the heating power. After the electric heating wire becomes conductive, it generates heat. The heat is conducted through the fibers around the electric heating wire and evenly distributed in the porous skeleton, realizing the overall heating of the porous skeleton.

[0056] The overall heated porous framework provides the temperature conditions for the catalytic oxidation of the catalyst, enabling the catalytic oxidation of gas-containing gases as they pass through the porous framework.

[0057] The porous skeleton includes multiple conductive heating circuits with different heating powers. By activating different conductive heating circuits, the porous skeleton can achieve different heating temperatures.

[0058] Optionally, the porous material is composed of multiple porous skeletons, which can combine small porous skeleton fabrics into larger porous materials. At the same time, multiple porous skeletons can be arranged along the airflow direction, so that thin porous skeletons can be combined into thicker porous materials. This makes the adjustment of the catalytic oxidation process of gas more flexible and can adapt to a larger range of methane concentration fluctuations.

[0059] Optionally, multiple temperature sensors are installed in the catalytic oxidation chamber. These temperature sensors are connected to a control device. The control device activates different conductive heating circuits based on the temperature detected by the temperature sensors inside the catalytic oxidation chamber to adapt to fluctuations in the methane concentration within the chamber.

[0060] Optional, such as Figure 1 As shown, the catalytic oxidation chamber 1 includes an inlet pipe 7 and an outlet pipe 8. The inlet pipe 7 and the outlet pipe 8 are installed on the same side of the catalytic oxidation chamber 1. The inlet pipe 7 passes through the porous material 2 inside the catalytic oxidation chamber 1 and distributes gas on the other side of the porous material 2 opposite to the outlet pipe 8.

[0061] Preferably, the diameter of the intake pipe 7 is smaller than the internal size of the catalytic oxidation chamber 1, so that the intake pipe can be installed in the center of the porous material 2, and the heat of the porous material 2 is used to heat the intake pipe to preheat the gas in the intake pipe 7.

[0062] Optionally, inside the catalytic oxidation chamber 1, a baffle gas distribution device 6 is installed at the end of the inlet pipe 7 to uniformly distribute gas in the catalytic oxidation chamber 1, so that the gas is input through the inlet pipe 7 that passes through the porous material 2, and is preheated by the heat of the porous material 2 during the transportation process in the inlet pipe 7; then the flow direction is changed by the baffle gas distribution device 6 and the gas is discharged through the baffle gas distribution device 6, and uniformly passes through the porous material 2 in the opposite direction of the transportation direction of the inlet pipe 7, and becomes a high-temperature gas after catalytic oxidation, and is discharged from the catalytic oxidation chamber.

[0063] The method for catalytic oxidation of gas containing methane using the above-mentioned gas catalytic oxidation device includes the following processes:

[0064] S1. The conductive heating circuit in the porous skeleton is turned on, heating the porous material to the set temperature;

[0065] S2. Introduce a gas-containing gas into the catalytic oxidation chamber, allowing the gas to pass through the micropores in the porous material;

[0066] S3. The combustible components in the gas containing methane are oxidized and decomposed under the catalysis of the catalyst, releasing heat, and the resulting high-temperature gas is discharged from the catalytic oxidation chamber.

[0067] S4. When the proportion of combustible components in the gas fluctuates, the control device adjusts the opening of different conductive heating circuits according to the temperature fluctuation in the catalytic oxidation chamber in order to stabilize the catalytic reaction temperature in the catalytic oxidation chamber.

[0068] Optionally, by adjusting the on / off state of different conductive heating circuits, the temperature of the porous material can be maintained within the active temperature range of the catalyst; optionally, the temperature can be maintained between 300 and 500°C.

[0069] This invention does not use metal materials to make porous materials for the following reasons: metal materials have a high coefficient of thermal expansion and are prone to breakage under temperature fluctuations at high temperatures, making it difficult to weave and prepare a framework material; moreover, low-cost metal materials are prone to oxidation and easily generate oxides in environments with low methane concentration and high oxygen concentration, and the continuously growing oxides will also affect the catalytic efficiency of the catalyst.

[0070] Using carbon fiber to create a porous framework offers advantages such as low thermal expansion coefficient and good durability. Utilizing the electrical and thermal conductivity of carbon fiber, methane-containing gas is heated to the catalytic oxidation temperature. The heating power can be flexibly adjusted according to fluctuations in the methane content of the input gas, minimizing the impact of methane concentration fluctuations on the device's operation and resulting in high stability. However, carbon fiber has relatively weak oxidation resistance and cannot operate long-term within the catalyst's active temperature range. Therefore, an antioxidant layer is prepared on the surface of the porous framework to enhance its oxidation resistance, enabling long-term operation at high temperatures. The antioxidant layer's components are often used in catalyst supports; therefore, preparing the catalyst on the antioxidant layer surface allows for successful catalyst loading. Loading the catalyst onto a self-heating support framework allows for rapid attainment of the temperature environment required for methane catalytic oxidation. The heat generated during catalytic oxidation is used to maintain the temperature environment and generate high-temperature gas. When high methane concentration leads to excessively rapid temperature rise, the temperature can be stabilized by reducing the heat generation of the framework material. Furthermore, the heat generated during catalytic oxidation is carried away by the gas, and the high-temperature gas discharged from the catalytic oxidation chamber can be utilized as a heat source.

[0071] The above solutions eliminate the need for a heat storage structure, reducing the size and weight of the device and enabling rapid startup, thus minimizing methane waste.

[0072] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A gas catalytic oxidation device, characterized in that, include: Catalytic oxidation chamber; gas containing methane flows from one end of the catalytic oxidation chamber to the other end; The catalytic oxidation chamber includes a porous material; the porous material is disposed in the gas flow path; The porous material is loaded with a catalyst, which is used to catalyze the oxidation of methane. The porous material includes a porous skeleton made of carbon fiber material and an antioxidant layer composited on the surface of the carbon fiber, wherein the antioxidant layer is a non-conductive material. The porous framework includes a conductive heating circuit made of carbon fiber material; the power transmission line of the conductive heating circuit is connected to the outside of the catalytic oxidation chamber; The porous skeleton is a felt or fabric made of raw materials including carbon fiber and other fibers; the other fibers include one or more of silicon carbide fiber, alumina fiber, boron nitride fiber, and boron carbide fiber; the pore size of the porous skeleton is 0.5~2 mm, and the conductive heating circuit is uniformly distributed in the porous skeleton; The conductive heating circuit includes electric heating wires evenly distributed in the porous skeleton. The electric heating wires are woven from carbon fiber and other fiber raw materials. After the electric heating wires become conductive, they generate heat. The heat is conducted through the fibers around the electric heating wires and evenly distributed in the porous skeleton, thereby achieving overall heating of the porous skeleton. The porous skeleton includes multiple conductive heating circuits with different heating powers. By activating different conductive heating circuits, the porous skeleton can achieve different heating temperatures.

2. The gas catalytic oxidation device as described in claim 1, characterized in that, The catalyst includes a catalytically active component, which includes one or more of palladium, platinum, rhodium, and iridium.

3. The gas catalytic oxidation device as described in claim 2, characterized in that, The catalyst includes a catalytic promoter, which includes a metal oxide; Specifically, it includes one or more of zinc oxide, zirconium oxide, nickel oxide, and titanium oxide.

4. The gas catalytic oxidation device as described in claim 2, characterized in that, The method for preparing the catalyst includes: Step 1: Impregnate the catalyst support with a precursor solution of catalyst promoter, dry and then calcine; Step 2: Impregnate the catalyst support with a precursor solution of the catalyst active component, dry it, and then calcine it. The catalyst support includes carbon fibers in a porous framework coated with an antioxidant layer.

5. The gas catalytic oxidation device as described in claim 1, characterized in that, The antioxidant components of the antioxidant layer include one or more of silicon oxide, aluminum oxide, silicon carbide, and zirconium boride.

6. The gas catalytic oxidation device as described in claim 5, characterized in that, The antioxidant layer is prepared on the surface of the porous skeleton after the porous skeleton is prepared.

7. The gas catalytic oxidation device as described in claim 6, characterized in that, The preparation process of the antioxidant layer includes: Step 1: Prepare a pyrolytic carbon coating on the surface of the porous framework; Step 2: Prepare an antioxidant layer on the surface of the pyrolytic carbon coating.

8. The gas catalytic oxidation device as described in claim 1, characterized in that, A temperature sensor is installed in the catalytic oxidation chamber. The temperature sensor is connected to a control device. The control device activates different conductive heating circuits based on the temperature detected by the temperature sensor in the catalytic oxidation chamber.

9. The gas catalytic oxidation device as described in claim 1, characterized in that, The catalytic oxidation chamber includes an inlet pipe and an outlet pipe. The inlet pipe passes through a porous material within the catalytic oxidation chamber, and the gas in the inlet pipe is preheated using the heat from the porous material.

10. The gas catalytic oxidation device as described in claim 9, characterized in that, The diameter of the intake pipe is smaller than the internal dimensions of the catalytic oxidation chamber.

11. The gas catalytic oxidation device as described in claim 9, characterized in that, Inside the catalytic oxidation chamber, a baffle gas distribution device is installed at the end of the air inlet pipe.

12. A method for catalytic oxidation of gas-containing gases using a gas catalytic oxidation device as described in any one of claims 1-11, characterized in that, The process includes the following: S1. The conductive heating circuit in the porous skeleton is turned on, heating the porous material to the set temperature; S2. Introduce a gas-containing gas into the catalytic oxidation chamber, allowing the gas to pass through the micropores in the porous material; S3. The combustible components in the gas containing methane are oxidized and decomposed under the catalysis of the catalyst, releasing heat, and the resulting high-temperature gas is discharged from the catalytic oxidation chamber. S4. When the proportion of combustible components in the gas fluctuates, the control device adjusts the opening of different conductive heating circuits according to the temperature fluctuation in the catalytic oxidation chamber in order to stabilize the catalytic reaction temperature in the catalytic oxidation chamber.

13. The method as described in claim 12, characterized in that, By adjusting the on / off state of different conductive heating circuits, the temperature of the porous material can be maintained within the active temperature range of the catalyst.

14. The method as described in claim 13, characterized in that, The temperature is maintained at 300~500℃.

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