Method for preparing a catalyst and combustible gas sensor

Abstract

This application provides a method for preparing a catalyst and a combustible gas sensor. The preparation method includes providing a reactor; wherein the reactor has a purge port at the bottom, a feed port at the top, and a reaction chamber located in the middle; catalyst particles are fed into the reaction chamber through the feed port; the purge port is controlled to purge an aqueous solution mixed with a protective material into the reactor, so that the aqueous solution mixed with the protective material coats the surface of the catalyst particles; the reaction chamber is controlled to heat the catalyst particles to form a protective layer with a gap of less than 1 micrometer on the surface of the catalyst particles, thereby obtaining the catalyst. This invention, by using this preparation method, significantly improves the anti-poisoning ability of the combustible gas sensor, thus ensuring the sensitivity and response speed of the combustible gas sensor during detection.

Description

Technical Field

[0001] This application relates to the field of gas concentration detection technology, and in particular to a method for preparing a catalyst and a combustible gas sensor. Background Technology

[0002] Current combustible gas sensors primarily rely on the principle of catalytic combustion for detection. Their core structure typically employs noble metals such as platinum (Pt) or palladium (Pd) as the catalytically active component, supported on the surface of porous ceramic supports such as alumina (Al₂O₃) or zirconium oxide (ZrO₂). When combustible gases (such as methane or propane) diffuse into the catalytic layer, a flameless oxidation reaction occurs under the catalytic action of the noble metal. The released heat causes a linear change in the resistance of the support material, and the gas concentration can be quantitatively detected by measuring this change in resistance. This type of sensor is widely used in industrial safety monitoring and environmental gas analysis due to its advantages such as high response stability, good linearity, and wide measurement range.

[0003] However, sensors based on noble metal catalysis have significant limitations in complex gas environments. When sulfides (such as H2S, SO2), chlorides (such as HCl, Cl2), or organosilicon compounds (such as hexamethyldisiloxane) are present in the detection environment, these gas molecules can occupy the active sites of the noble metal catalyst through chemisorption or physical covering, leading to a reduction in the number of catalytic active centers and causing irreversible catalyst poisoning. Specifically, this manifests as a delay in sensor response time from seconds to minutes, a decrease in detection sensitivity of more than 50%, or even complete failure. Furthermore, high-temperature operating conditions accelerate the chemical reaction between the catalyst and the poison, further deteriorating sensor performance.

[0004] Therefore, how to develop a new type of combustible gas sensor that combines resistance to poisoning with high selectivity is a technical problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] The technical problem to be solved by this application is to provide a method for preparing a catalyst and a combustible gas sensor, which improves the anti-poisoning ability of the combustible gas sensor, thereby ensuring the sensitivity and response speed of the combustible gas sensor during detection.

[0006] To address the aforementioned technical problems, in a first aspect, this application provides a method for preparing a catalyst for installation on a combustible gas sensor, comprising:

[0007] A reactor is provided; wherein the reactor has a purge port at the bottom, a feed port at the top, and a reaction chamber located in the middle;

[0008] Catalyst particles are fed into the reaction chamber through the feed inlet;

[0009] The purge port is controlled to purge an aqueous solution mixed with protective material into the reactor, so that the aqueous solution mixed with protective material coats the surface of the catalyst particles;

[0010] The catalyst particles are heated in the reaction chamber to form a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles, thereby obtaining the catalyst.

[0011] In some embodiments of this application, controlling the purge port to purge an aqueous solution mixed with a protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with the protective material, includes:

[0012] The flow rate at the purge port is controlled at 0.1~3.0 m / s to purge the aqueous solution mixed with the protective material into the reactor, and to make the catalyst particles with a particle size range of 0.8-1 mm move and tumble in the reaction chamber, so that the aqueous solution mixed with the protective material is uniformly coated on the surface of the catalyst particles.

[0013] The catalyst particulate component includes at least one of noble metal oxides, alumina, cerium oxide, zirconium oxide, and silicon oxide, and the proportion of noble metal oxides is 0.5%-2%.

[0014] In some embodiments of this application, controlling the purge port to purge an aqueous solution mixed with a protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with the protective material, includes:

[0015] The purge port is controlled to purge an aqueous solution mixed with zinc acetate or zinc nitrate into the reactor so that the aqueous solution mixed with zinc acetate or zinc nitrate coats the surface of the catalyst particles.

[0016] The method of controlling the reaction chamber to heat the catalyst particles to form a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles includes:

[0017] The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of zinc acetate or zinc nitrate coated on the surface of the catalyst particles evaporates, thereby forming a zinc oxide protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles.

[0018] The protective layer includes the zinc oxide protective layer.

[0019] In some embodiments of this application, after forming a zinc oxide protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles, the method further includes:

[0020] The purge port is controlled to purge an aqueous solution mixed with calcium acetate or calcium nitrate into the reactor so that the aqueous solution mixed with calcium acetate or calcium nitrate is coated on the surface of the zinc oxide protective layer.

[0021] The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of calcium acetate or calcium nitrate coated on the surface of the zinc oxide protective layer evaporates, thereby forming a calcium oxide protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer.

[0022] The protective layer includes the calcium oxide protective layer.

[0023] In some embodiments of this application, after forming a calcium oxide protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer, the following steps are included:

[0024] The purge port is controlled to purge an aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate into the reactor so that the aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate is coated on the surface of the calcium oxide protective layer;

[0025] The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of aluminum ammonium sulfate or aluminum nitrate coated on the surface of the calcium oxide protective layer evaporates, thereby forming a nano-alumina protective layer with gaps of less than 1 micrometer on the surface of the calcium oxide protective layer.

[0026] The protective layer includes the nano-alumina protective layer.

[0027] In some embodiments of this application, the water concentration in the aqueous solution containing zinc acetate is 10-30 g / 100 ml, or the water concentration in the aqueous solution containing zinc nitrate is 50-100 g / 100 ml.

[0028] In some embodiments of this application, the water concentration in the aqueous solution containing calcium acetate is 5-20 g / 100 ml, or the water concentration in the aqueous solution containing calcium nitrate is 50-160 g / 100 ml.

[0029] In some embodiments of this application, the water concentration in the aqueous solution containing ammonium aluminum sulfate is 5-10 g / 100 ml, or the water concentration in the aqueous solution containing aluminum nitrate is 50-120 g / 100 ml.

[0030] In some embodiments of this application, the purge port includes an atomizing hole and an inert gas purge hole;

[0031] The control of the purge port to purge an aqueous solution mixed with protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with protective material, includes:

[0032] An aqueous solution containing protective material is sprayed into the reaction chamber through the atomizing orifice;

[0033] The inert gas purging port releases inert gas to purge the atomized aqueous solution mixed with protective material into the reaction chamber, so that the aqueous solution mixed with protective material is coated on the surface of the catalyst particles.

[0034] In a second aspect, embodiments of this application provide a combustible gas sensor, including a housing, leads, and a catalyst prepared using the aforementioned preparation method;

[0035] The catalyst is disposed within the shell;

[0036] The lead is connected to the catalyst.

[0037] The beneficial effects of the catalyst preparation method and combustible gas sensor provided in this application are as follows:

[0038] 1. This application involves forming a protective layer on the surface of catalyst particles. This protective layer comprises a zinc oxide protective layer, a calcium oxide protective layer, and a nano-alumina protective layer, sequentially arranged. The nano-alumina protective layer adsorbs macromolecular organosilicon, thus preventing contact between the organosilicon and the catalyst particles. The calcium oxide protective layer adsorbs chlorides, preventing contact between chlorides and catalyst particles. The zinc oxide protective layer adsorbs sulfides, preventing contact between sulfides and catalyst particles. Therefore, by using this preparation method to form a catalyst, this application utilizes this catalyst to prepare a combustible gas sensor, significantly improving the sensor's resistance to poisoning and ensuring its sensitivity and response speed during detection.

[0039] 2. This application improves the reliability of sulfide and chloride removal by placing the nano-alumina protective layer on the outermost layer of the protective layer to avoid the organosilicon reacting and failing with the zinc oxide and calcium oxide protective layers first.

[0040] 3. The catalysts provided in this application all contain 0.5%-2% precious metal oxides, which reduces costs and ensures the catalytic effect of the catalysts. Attached Figure Description

[0041] Figure 1 A flowchart of the catalyst preparation method provided in this application;

[0042] Figure 2 This is a schematic diagram of the reactor structure provided in the embodiments of this application.

[0043] Figure label:

[0044] Reactor 100, purge port 101, feed port 102, reaction chamber 103, heater 104;

[0045] Catalyst particulate matter 200. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application. Unless otherwise defined, the technical or scientific terms used herein should have the ordinary meaning understood by those skilled in the art to which this application pertains. The terms "comprising" and similar expressions used herein mean that the element or object preceding the word covers the element or object listed after the word and its equivalents, but does not exclude other elements or objects. Unless otherwise specified, the term "connection" as used herein can refer to a direct connection or an indirect connection, i.e., a connection through an intermediate object.

[0047] Furthermore, it should be understood that the orientations or positional relationships indicated by terms such as "length," "width," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer" in this document are based on the orientations or positional relationships shown in the accompanying drawings and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this application. The terms "first" and "second" in this document are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0048] To address the problems existing in the prior art, embodiments of this application provide a method for preparing a catalyst for use in a combustible gas sensor. (Reference) Figure 1 and Figure 2 As shown, the preparation method includes:

[0049] S101: Provide a reactor 100; wherein the reactor 100 has a purge port 101 at the bottom, a feed port 102 at the top, and a reaction chamber 103 located in the middle.

[0050] S102: Catalyst particles 200 are fed into the reaction chamber 103 through the feed port 102.

[0051] Specifically, in this step, catalyst particles 200 with a particle size ranging from 0.8 to 1 mm are fed into the reaction chamber 103 through the feed inlet 102. The catalyst particles comprise at least one of noble metal oxides, alumina, cerium oxide, zirconium oxide, and silicon oxide, with the noble metal oxides accounting for 0.5% to 2%. The noble metal oxides may be palladium oxide, platinum oxide, ruthenium oxide, or rhodium oxide, etc.

[0052] S103: Control the purge port 101 to purge the aqueous solution mixed with the protective material into the reactor 100 so that the aqueous solution mixed with the protective material is coated on the surface of the catalyst particles 200.

[0053] It should be noted that the purge port 101 includes an atomizing hole and an inert gas purge hole. The atomizing hole can atomize the aqueous solution, and the inert gas purge hole is used to purge the atomized aqueous solution with inert gas so as to purge the aqueous solution into the reaction chamber 103.

[0054] In this step, specifically, the aqueous solution mixed with the protective material is sprayed into the reaction chamber 103 through the atomizing hole, and at the same time, the atomized aqueous solution mixed with the protective material is blown into the reaction chamber 103 through the inert gas purging hole, so that the aqueous solution mixed with the protective material uniformly covers the surface of the catalyst particles 200 to form the protective layer.

[0055] In addition, in this embodiment, by controlling the flow rate of the gas purging through the inert gas purging hole to be between 0.1 and 3.0 m / s, the catalyst particles 200 with a particle size range of 0.8-1 mm can be made to move and tumble in the reaction chamber 103, thereby uniformly coating the surface of the catalyst particles 200 with the aqueous solution mixed with the protective material, so as to ensure the uniformity of the protective layer subsequently formed on the surface of the catalyst particles 200.

[0056] S104: Control the reaction chamber 103 to heat the catalyst particles 200 to form a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles 200, so as to obtain the catalyst.

[0057] It should be noted that a heater 104 is also provided on the outer wall of the reaction chamber 103, which is used to heat the inside of the reaction chamber 103. When the preparation process is started, the heater 104 starts to work and heats the temperature inside the reaction chamber 103 to 300-500°C.

[0058] Therefore, in this step, the water in the aqueous solution containing the protective material coated on the surface of the catalyst particles 200 evaporates, thereby forming a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles 200. This removes and isolates various gases that can poison the combustible gas sensor. Furthermore, because the gaps in the protective layer are less than 1 micrometer, combustible gases can pass through the protective layer and react with the catalyst particles.

[0059] Example 1

[0060] refer to Figure 1 and Figure 2 As shown, the reactor 100 is turned on, and catalyst particles 200 with a particle size of 0.9 mm are fed into the reaction chamber 103 through the feed port 102. The catalyst particles 200 are composed of alumina and palladium oxide.

[0061] The flow rate of the inert gas purging orifice at the purging port 101 is controlled at 2 m / s. An aqueous solution mixed with zinc acetate or zinc nitrate is atomized through the atomizing orifice and then purged into the reaction chamber 103, so that the aqueous solution mixed with zinc acetate or zinc nitrate coats the surface of the catalyst particles 200. The water concentration in the aqueous solution mixed with zinc acetate is 20 g / 100 ml, or the water concentration in the aqueous solution mixed with zinc nitrate is 75 g / 100 ml.

[0062] The heater 104 is controlled to heat the reaction chamber 103 to a temperature of 400°C. The surface of the catalyst particles 200 is coated with an aqueous solution of zinc acetate or zinc nitrate, from which the water evaporates upon heating, thereby forming a zinc oxide protective layer with gaps less than 1 micrometer on the surface of the catalyst particles 200. This protective layer includes the zinc oxide protective layer.

[0063] In this embodiment, a catalyst coated with the zinc oxide protective layer is prepared by the preparation method. When it comes into contact with sulfide gas, it can react with it to remove the sulfide gas, thereby preventing the combustible gas sensor from being poisoned by contact with sulfide gas.

[0064] Example 2

[0065] Based on Example 1, after preparing the catalyst coated with the zinc oxide protective layer, an aqueous solution mixed with calcium acetate or calcium nitrate is atomized through an atomizing orifice and then blown into the reaction chamber 103, so that the aqueous solution mixed with calcium acetate or calcium nitrate is coated on the surface of the zinc oxide protective layer. The water concentration in the aqueous solution mixed with calcium acetate is 12 g / 100 ml; or the water concentration in the aqueous solution mixed with calcium nitrate is 100 g / 100 ml.

[0066] The temperature inside the reaction chamber 103 is maintained at 400°C to allow the water in the aqueous solution of calcium acetate or calcium nitrate mixed with the zinc oxide protective layer to evaporate, thereby forming a calcium oxide protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer. The protective layer includes the calcium oxide protective layer.

[0067] In this embodiment, it can be understood that by adding the calcium oxide protective layer on the basis of Embodiment 1, chloride gas can be removed to prevent the combustible gas sensor from being poisoned by contact with chloride gas.

[0068] Example 3

[0069] Based on Example 1 or Example 2, an aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate is atomized through an atomizing orifice and then blown into the reaction chamber 103, so that the aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate coats the surface of the zinc oxide protective layer or covers the surface of the calcium oxide protective layer. The water concentration in the aqueous solution mixed with ammonium aluminum sulfate is 9 g / 100 ml, or the water concentration in the aqueous solution mixed with aluminum nitrate is 80 g / 100 ml.

[0070] The temperature inside the reaction chamber 103 is maintained at 400°C to allow the moisture in the aqueous solution of calcium acetate or calcium nitrate mixed with the zinc oxide protective layer or the calcium oxide protective layer to evaporate, thereby forming a nano-alumina protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer or the calcium oxide protective layer. The protective layer includes the nano-alumina protective layer.

[0071] In this embodiment, it can be understood that by adding the nano-alumina protective layer based on Embodiment 1 or Embodiment 2, the macromolecular organosilicon gas can be removed to prevent the combustible gas sensor from being poisoned by contact with organosilicon gas.

[0072] In this embodiment, after the catalyst is prepared by the preparation method, a combustible gas sensor is prepared using the catalyst, which greatly improves the anti-poisoning ability of the combustible gas sensor, thereby ensuring the sensitivity and response speed of the combustible gas sensor during detection.

[0073] In another embodiment of the present invention, a combustible gas sensor is provided, comprising a housing, leads, and a catalyst prepared using the methods described in the above embodiments. The catalyst is disposed within the housing, and the leads are connected to the catalyst.

[0074] In this embodiment, a protective layer is formed on the surface of the catalyst particles 200. This protective layer comprises a zinc oxide protective layer, a calcium oxide protective layer, and a nano-alumina protective layer, sequentially arranged. The nano-alumina protective layer adsorbs macromolecular organosilicon, thereby preventing contact between the organosilicon and the catalyst particles. The calcium oxide protective layer adsorbs chlorides, thus preventing contact between chlorides and the catalyst particles. The zinc oxide protective layer adsorbs sulfides, thus preventing contact between sulfides and the catalyst particles. Therefore, by using this preparation method to form the catalyst, this application utilizes the catalyst to prepare a combustible gas sensor, significantly improving the sensor's resistance to poisoning, thereby ensuring the sensitivity and response speed of the combustible gas sensor during detection.

[0075] The above description is merely a specific implementation of the embodiments of this application, but the protection scope of the embodiments of this application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the embodiments of this application should be covered within the protection scope of the embodiments of this application. Therefore, the protection scope of the embodiments of this application should be determined by the protection scope of the claims.

Claims

1. A method for preparing a catalyst, said catalyst being used to mount on a combustible gas sensor, characterized in that, include: A reactor is provided; wherein the reactor has a purge port at the bottom, a feed port at the top, and a reaction chamber located in the middle; Catalyst particles are fed into the reaction chamber through the feed inlet; The purge port is controlled to purge an aqueous solution mixed with protective material into the reactor, so that the aqueous solution mixed with protective material coats the surface of the catalyst particles; The catalyst particles are heated in the reaction chamber to form a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles, thereby obtaining the catalyst. The control of the purge port to purge an aqueous solution mixed with protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with protective material, includes: The flow rate at the purge port is controlled at 0.1~3.0 m / s to purge the aqueous solution mixed with the protective material into the reactor, and to make the catalyst particles with a particle size range of 0.8-1 mm move and tumble in the reaction chamber, so that the aqueous solution mixed with the protective material is uniformly coated on the surface of the catalyst particles. The protective layer comprises a zinc oxide protective layer, a calcium oxide protective layer and a nano-alumina protective layer arranged sequentially, and the catalyst particulate component comprises at least one of noble metal oxides, alumina, cerium oxide, zirconium oxide and silicon oxide, wherein the proportion of noble metal oxides is 0.5%-2%.

2. The preparation method according to claim 1, characterized in that, The control of the purge port to purge an aqueous solution mixed with protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with protective material, includes: The purge port is controlled to purge an aqueous solution mixed with zinc acetate or zinc nitrate into the reactor so that the aqueous solution mixed with zinc acetate or zinc nitrate coats the surface of the catalyst particles. The method of controlling the reaction chamber to heat the catalyst particles to form a protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles includes: The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of zinc acetate or zinc nitrate coated on the surface of the catalyst particles evaporates, thereby forming a zinc oxide protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles. The protective layer includes the zinc oxide protective layer.

3. The preparation method according to claim 2, characterized in that, After forming a zinc oxide protective layer with gaps of less than 1 micrometer on the surface of the catalyst particles, the process further includes: The purge port is controlled to purge an aqueous solution mixed with calcium acetate or calcium nitrate into the reactor so that the aqueous solution mixed with calcium acetate or calcium nitrate is coated on the surface of the zinc oxide protective layer. The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of calcium acetate or calcium nitrate coated on the surface of the zinc oxide protective layer evaporates, thereby forming a calcium oxide protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer. The protective layer includes the calcium oxide protective layer.

4. The preparation method according to claim 3, characterized in that, After forming a calcium oxide protective layer with gaps of less than 1 micrometer on the surface of the zinc oxide protective layer, the process includes: The purge port is controlled to purge an aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate into the reactor so that the aqueous solution mixed with ammonium aluminum sulfate or aluminum nitrate is coated on the surface of the calcium oxide protective layer; The temperature inside the reaction chamber is controlled at 300-500℃ so that the water in the aqueous solution of aluminum ammonium sulfate or aluminum nitrate coated on the surface of the calcium oxide protective layer evaporates, thereby forming a nano-alumina protective layer with gaps of less than 1 micrometer on the surface of the calcium oxide protective layer. The protective layer includes the nano-alumina protective layer.

5. The preparation method according to claim 2, characterized in that, The concentration of zinc acetate in the aqueous solution containing zinc acetate is 10-30 g / 100 ml, or the concentration of zinc nitrate in the aqueous solution containing zinc nitrate is 50-100 g / 100 ml.

6. The preparation method according to claim 3, characterized in that, The concentration of calcium acetate in the aqueous solution containing calcium acetate is 5-20 g / 100 ml, or the concentration of calcium nitrate in the aqueous solution containing calcium nitrate is 50-160 g / 100 ml.

7. The preparation method according to claim 4, characterized in that, The concentration of ammonium aluminum sulfate in the aqueous solution mixed with ammonium aluminum sulfate is 5-10 g / 100 ml, or the concentration of aluminum nitrate in the aqueous solution mixed with aluminum nitrate is 50-120 g / 100 ml.

8. The preparation method according to claim 1, characterized in that, The purge port includes an atomizing hole and an inert gas purge hole; The control of the purge port to purge an aqueous solution mixed with protective material into the reactor, so as to coat the surface of the catalyst particles with the aqueous solution mixed with protective material, includes: An aqueous solution containing protective material is sprayed into the reaction chamber through the atomizing orifice; The inert gas purging port releases inert gas to purge the atomized aqueous solution mixed with protective material into the reaction chamber, so that the aqueous solution mixed with protective material is coated on the surface of the catalyst particles.

9. A combustible gas sensor, characterized in that, Includes a shell, leads, and a catalyst prepared by the preparation method according to any one of claims 1 to 8; The catalyst is disposed within the shell; The lead is connected to the catalyst.

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