Monolithic noble metal catalyst and method for its production and use

Abstract

This invention relates to the field of catalyst preparation technology, and discloses a monolithic noble metal catalyst, its preparation method, and its application. The monolithic noble metal catalyst comprises a porous structured support and an active noble metal component and an auxiliary agent supported on the porous structured support. The particle size of the active noble metal component is 2-3 nm. The method includes: (1) sequentially acid-treating and calcining the structured support to obtain a porous structured support; (2) immersing the porous structured support in a mixed solution containing a noble metal precursor and optional structural auxiliary agent, and then sequentially subjecting it to high-pressure gas knife purging, drying, calcination, and reduction. The monolithic noble metal catalyst prepared by this invention exhibits good catalytic performance in the catalytic oxidation of carbon-based oxygen-containing molecular gases, and the catalyst exhibits significantly better stability, making it suitable for continuous long-term operation.

Description

Technical Field

[0001] This invention relates to the field of catalyst preparation technology, specifically to a monolithic noble metal catalyst, its preparation method and application, and more specifically, to a monolithic carbon-based oxygen-containing small molecule gas oxidation and removal catalyst, its preparation method and its application in the catalytic oxidation of carbon-based oxygen-containing small molecule gases. Background Technology

[0002] In petrochemical production, carbon-based oxygen-containing small molecules often undergo incomplete reactions during directional oxidation, leading to the enrichment of these gases in exhaust gases or circulating carrier gases. This not only poses a risk of combustion and explosion but also generates photochemical phenomena, causing environmental pollution. Currently, the main method for treating oxygen-containing small molecule exhaust gases from petrochemical oxidation processes is catalytic oxidation. Catalytic oxidation can completely oxidize these gases to form carbon dioxide. Furthermore, to meet the demands of low pressure drop and high volume operation, catalytic oxidation methods commonly employ monolithic catalysts loaded with precious metals. However, the problems of high precious metal consumption, high cost, and poor stability remain.

[0003] Currently, catalytic oxidation methods generally employ catalysts with active metals supported on carriers. Common carrier forms include silica gel, activated alumina, glass fiber mesh (cloth), hollow ceramic spheres, sea sand, layered graphite, hollow glass beads, quartz glass tubes (sheets), ordinary (conductive) glass sheets, plexiglass, optical fibers, natural clay, foam plastics, resins, wood chips, expanded perlite, activated carbon, etc. Different carriers correspond to different loading amounts of active metals. However, the problems of large amounts of active metals used, high costs, and poor stability still exist.

[0004] Patent application CN113996284A discloses a method for preparing a low-temperature catalytic oxidation catalyst for carbon monoxide. A simple impregnation method is used, where cerium nitrate ethanol solution is impregnated in diatomaceous earth, followed by drying and calcination to prepare a novel diatomaceous earth-supported CeO2 CO catalytic oxidation catalyst, which exhibits good catalytic activity in CO catalytic oxidation experiments. However, this catalyst requires loading a large amount of active noble metal during preparation, and the addition of low specific surface area CeO2 / Fe2O3 during the preparation of the monolithic catalyst results in poor dispersion of the active metal loading and low effective utilization.

[0005] Patent application CN114308063A discloses a PtCo / Co3O 4x Al2O3 multi-interface structure catalysts, their preparation methods and applications: Although the catalyst has multi-interface structure characteristics, good noble metal dispersion and many active sites, the multi-interface structure determines that the amount of noble metal used in the catalyst is relatively high, the catalyst preparation cost is high, and the prospects for industrial promotion are unclear.

[0006] Patent application CN1986035A discloses a method for purifying automobile exhaust, in which a catalyst can achieve the purification of CO, HC, and NO at a relatively low ignition temperature. x While purification can be achieved, a significant amount of precious metals are required to reach the desired purification target. Furthermore, after a period of use, the active components will detach from the support, causing a rapid decline in catalyst activity or even deactivation.

[0007] Patent application CN1488435A discloses a catalytic combustion catalyst and its preparation method. The catalyst has a high conversion efficiency of catalytic combustion of organic waste gas, but the coating is composed of a composite oxide formed by Al2O3, SiO2 and one or more alkaline earth metal oxides. It uses a high content of precious metal elements and has disadvantages such as high price, poor anti-poisoning performance and poor general applicability.

[0008] Therefore, the development of catalysts that are highly efficient, inexpensive, environmentally friendly, and durable has become a research hotspot and application trend for catalytic oxidation catalysts both domestically and internationally. Summary of the Invention

[0009] The purpose of this invention is to efficiently remove carbon-based oxygen-containing molecular gases from exhaust gases emitted during chemical production processes, providing a monolithic noble metal catalyst, its preparation method, and its applications. This invention promotes the dispersion of active noble metals and the exposure of the active phase by controlling the surface defect site structure of the monolithic catalyst; and efficiently constructs catalytic active sites on the catalyst surface, reducing the content of active noble metals while increasing the adsorption capacity of carbon-based oxygen-containing molecular gases and oxygen, promoting oxygen adsorption and activation, thereby improving the catalytic efficiency of the catalyst.

[0010] To achieve the above objectives, the present invention provides an integral noble metal catalyst, comprising a porous structured support and an active component supported on the porous structured support, wherein the active component contains a noble metal and optionally an alloy metal, and the particle size of the active component is 1-8 nm, preferably 2-6 nm.

[0011] Preferably, the mesoporous channel size of the monolithic noble metal catalyst is 0.1-20 nm, and the specific surface area is 200-800 m². 2 / g.

[0012] Preferably, the content of the active component is 0.1-1 parts by weight relative to 100 parts by weight of the porous structured carrier.

[0013] Preferably, the porous structured carrier is obtained by sequentially acid-treating and calcining the structured carrier.

[0014] Preferably, the acid used in the acid treatment process is a mixture of nitric acid, sulfuric acid and / or hydrochloric acid, and the molar ratio of nitric acid to sulfuric acid and / or hydrochloric acid is 1:1-10.

[0015] Preferably, the calcination process is carried out under conditions of 100-1000 ml / min air flow and 100-1000 °C.

[0016] Preferably, the regularized carrier is selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier and alumina honeycomb carrier.

[0017] Preferably, in the active component, the molar ratio of the noble metal to the alloy metal is 1:0.1-0.3.

[0018] Preferably, the precious metal is at least one selected from silver, ruthenium, rhodium, palladium, osmium, iridium and platinum, and more preferably a combination of platinum and palladium.

[0019] Preferably, the alloy metal is at least one of Fe, La and Ce, and more preferably a combination of La and Ce.

[0020] A second aspect of this invention provides a method for preparing a monolithic noble metal catalyst, the method comprising the following steps:

[0021] (1) The structured carrier is subjected to acid treatment and calcination in sequence to obtain a porous structured carrier;

[0022] (2) The porous structured carrier is immersed in a mixed solution containing a noble metal precursor and optional structural additives, and then subjected to high-pressure air knife purging, drying, calcination and reduction in sequence.

[0023] Preferably, in step (1), the acid treatment process includes: reflux treatment of the regularized carrier with a mixed acid solution, followed by washing until neutral and drying.

[0024] Preferably, the mixed acid is a mixture of nitric acid, sulfuric acid and / or hydrochloric acid, and the molar ratio of nitric acid to sulfuric acid and / or hydrochloric acid is 1:1-10.

[0025] Preferably, the concentration of the mixed acid is 2-10 mol / L.

[0026] Preferably, the reflux treatment conditions include: a temperature of 50-90°C and a time of 1-24 hours.

[0027] Preferably, the regularized carrier is selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier and alumina honeycomb carrier.

[0028] Preferably, in step (1), the calcination process is carried out under conditions of 100-1000 ml / min air flow and 100-1000 °C.

[0029] Preferably, in step (2), the pH value of the mixed solution containing the noble metal precursor and the structural aid is 9-12.

[0030] Preferably, the noble metal precursor is selected from at least one of chloroplatinic acid, 2-hydroxyethylamine salt of platinum(IV) hydroxyacetate, platinum chloride, platinum nitrate, platinum acetylacetonate, palladium chloride, palladium nitrate, and palladium acetate.

[0031] Preferably, the structural additive is selected from at least one of ferric nitrate, cerium nitrate, lanthanum nitrate, lanthanum sulfate, lanthanum chloride, cerium sulfate, and cerium trioxide.

[0032] Preferably, in step (2), the high-pressure air knife purging process is performed by purging with an air knife at 1.5-2.5 MPa.

[0033] Preferably, the roasting conditions include: a temperature of 200-300℃ and a time of 4-10 hours;

[0034] Preferably, during the reduction process, the reducing atmosphere is H2, CO, a combination of H2 and CO, a mixed atmosphere with different hydrogen concentrations, or a mixed atmosphere with different CO concentrations.

[0035] Preferably, the reduction conditions include: a catalyst heating rate of 2-20℃ / min, a reduction temperature of 300-450℃, and a reduction time of 1-10h.

[0036] A third aspect of the present invention provides a monolithic noble metal catalyst prepared by the above method.

[0037] The fourth aspect of the present invention provides the application of the above-mentioned monolithic noble metal catalyst in the catalytic oxidation of carbon-based oxygen-containing molecular gases.

[0038] Compared with the prior art, the technical solution of the present invention has the following advantages:

[0039] (1) Compared with other catalytic oxidation technologies, the monolithic noble metal catalyst with defect sites formed by pretreatment of the structured support has higher oxygen adsorption and activation capabilities and higher catalytic oxidation efficiency.

[0040] (2) Compared with other catalytic oxidation technologies, this catalyst has high mechanical strength and is suitable for high space velocity and large volume gas processing conditions;

[0041] (3) Compared with other catalytic oxidation technologies, this catalyst does not require coating preparation, has the advantages of high active metal strength, strong water resistance, and is conducive to continuous long-term operation.

[0042] (4) Compared with other catalytic oxidation technologies, this catalyst has a low active metal content and does not require coating, which greatly reduces operating costs. Attached Figure Description

[0043] Figure 1 This is a TEM image of the monolithic catalyst prepared in Example 1;

[0044] Figure 2 This is a SEM-Mapping image of the monolithic catalyst prepared in Example 1. Detailed Implementation

[0045] The following provides a detailed description of specific embodiments of the present invention. It should be understood that the specific embodiments described herein are for illustrative and explanatory purposes only and are not intended to limit the scope of the invention.

[0046] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0047] In this invention, unless otherwise specified, the gas concentration "%" refers to "volume %"; "space velocity" refers to "volume space velocity"; and "pressure" refers to absolute pressure.

[0048] The monolithic noble metal catalyst of this invention comprises a porous structured support and an active component supported on the porous structured support. The active component contains a noble metal and optionally an alloy metal. In this invention, the surface of the porous structured support has a uniformly distributed porous structure (i.e., a surface defect site structure), and the active component is dispersed in the porous structure, resulting in a relatively uniform dispersion and a small particle size. Specifically, the particle size of the active component is 1-8 nm, preferably 2-6 nm, and more preferably 2-3 nm.

[0049] In the monolithic noble metal catalyst of the present invention, the mesopore size of the monolithic noble metal catalyst is 0.1-20 nm, preferably 0.5-12 nm; and the specific surface area is 200-800 m². 2 / g, preferably 300-600m 2 / g.

[0050] In the monolithic noble metal catalyst of the present invention, the content of the active component relative to 100 parts by weight of the porous structured support can be 0.1-1 parts by weight, specifically, for example, 0.1 parts by weight, 0.2 parts by weight, 0.3 parts by weight, 0.4 parts by weight, 0.5 parts by weight, 0.6 parts by weight, 0.7 parts by weight, 0.8 parts by weight, 0.9 parts by weight, or 1 part by weight.

[0051] In the monolithic noble metal catalyst of the present invention, the porous structured support is obtained by sequentially acid-treating and calcining the structured support.

[0052] In some preferred embodiments, the acid used in the acid treatment process is a mixture of nitric acid, sulfuric acid, and / or hydrochloric acid, and the molar ratio of nitric acid to sulfuric acid and / or hydrochloric acid is 1:1-10. Specifically, the molar ratio of nitric acid to sulfuric acid and / or hydrochloric acid can be, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9, or 1:10. In this invention, by adjusting the ratio of the mixed acid, the surface defect site structure of the porous and well-structured support can be controlled, efficiently constructing catalytic active sites on the catalyst surface. This reduces the content of noble metal catalysts while increasing the adsorption capacity of carbon-based oxygen-containing molecular gases and oxygen, promoting oxygen adsorption and activation, and thus improving the catalytic efficiency of the catalyst.

[0053] In some other preferred embodiments, the calcination process is carried out under conditions of an airflow of 100-1000 ml / min (specifically, for example, 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, 600 ml / min, 700 ml / min, 800 ml / min, 900 ml / min or 1000 ml / min) and a temperature of 100-1000℃ (specifically, for example, 100℃, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃).

[0054] In this invention, the regularized carrier is preferably selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier and alumina honeycomb carrier, and most preferably cordierite honeycomb carrier.

[0055] In the monolithic noble metal catalyst of the present invention, the molar ratio of the noble metal to the alloy metal in the active component is 1:0.1-0.3, preferably 1:0.15-0.2.

[0056] In the monolithic noble metal catalyst of the present invention, the noble metal in the active component may be selected from at least one of ruthenium, rhodium, palladium, osmium, iridium and platinum, preferably a combination of platinum and palladium. When the noble metal is a combination of platinum and palladium, the molar ratio of platinum to palladium may be 1:0.5-2, and most preferably 1:1.

[0057] In the monolithic noble metal catalyst of the present invention, the alloy metal in the active component can be at least one of Fe, La, and Ce, preferably a combination of La and Ce. When the alloy metal is a combination of La and Ce, the molar ratio of La to Ce can be 1:0.5-2, and most preferably 1:1.

[0058] The preparation method of the monolithic noble metal catalyst of the present invention includes the following steps:

[0059] (1) The structured carrier is subjected to acid treatment and calcination in sequence to obtain a porous structured carrier;

[0060] (2) The porous structured carrier is immersed in a mixed solution containing a noble metal precursor and optional structural additives, and then subjected to high-pressure air knife purging, drying, calcination and reduction in sequence.

[0061] In step (1), the acid treatment process can remove impurities contained in the structured carrier, forming a bare hydroxyl surface. The acid treatment process may include: reflux treatment of the structured carrier with a mixed acid solution, followed by washing until neutral and drying.

[0062] Specifically, the mixed acid is a mixture of nitric acid, sulfuric acid and / or hydrochloric acid, and the molar ratio of nitric acid to sulfuric acid and / or hydrochloric acid can be 1:1-10, for example, 1:1, 1:2, 1:3, 1:4, 1:5, 1:6, 1:7, 1:8, 1:9 or 1:10.

[0063] Specifically, the concentration of the mixed acid can be 2-10 mol / L, preferably 2-5 mol / L.

[0064] Specifically, the reflux treatment conditions may include: a temperature of 50-90°C and a time of 1-24 hours.

[0065] In the method described in this invention, the regularized carrier may be selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier and alumina honeycomb carrier, preferably cordierite honeycomb carrier.

[0066] In step (1), the calcination process is carried out under the conditions of an air flow of 100-1000 ml / min (specifically, for example, 100 ml / min, 200 ml / min, 300 ml / min, 400 ml / min, 500 ml / min, 600 ml / min, 700 ml / min, 800 ml / min, 900 ml / min or 1000 ml / min) and a temperature of 100-1000℃ (specifically, for example, 100℃, 200℃, 300℃, 400℃, 500℃, 600℃, 700℃, 800℃, 900℃ or 1000℃).

[0067] In step (2), the pH value of the mixed solution containing the noble metal precursor and the structural aid is 9-12. Specifically, the pH value of the mixed solution can be, for example, 9, 10, 11 or 12.

[0068] In this invention, the noble metal in the noble metal precursor is at least one selected from silver, ruthenium, rhodium, palladium, osmium, iridium, and platinum, preferably a combination of platinum and palladium. In a specific embodiment, the noble metal precursor is selected from at least one selected from chloroplatinic acid, 2-hydroxyethylamine hexahydroxide platinum(IV) acid, platinum chloride, platinum nitrate, platinum acetylacetonate, palladium chloride, palladium nitrate, and palladium acetate.

[0069] In this invention, the structural aid is added to provide an alloy metal, so that the active component in the prepared catalyst exists in the form of a noble metal element, an alloy, or a noble metal oxide. In a specific embodiment, the structural aid is selected from at least one of ferric nitrate, cerium nitrate, lanthanum nitrate, lanthanum sulfate, lanthanum chloride, cerium sulfate, and cerium trioxide.

[0070] In step (2), the high-pressure air knife purging process is carried out by purging with an air knife at 1.5-2.5 MPa.

[0071] In step (2), the calcination conditions may include: a temperature of 200-300℃ and a time of 4-10 hours;

[0072] In step (2), the reducing atmosphere can be H2, CO, a combination of H2 and CO, a mixed atmosphere with different hydrogen concentrations, or a mixed atmosphere with different CO concentrations. In a specific embodiment, the reducing atmosphere is a mixed atmosphere with different H2 concentrations and / or a mixed atmosphere with different CO concentrations. By adjusting the reducing atmosphere, efficient control of oxygen vacancy formation on the catalyst surface can be achieved. Specifically, the reducing atmosphere can be, for example, 5% H2 (diluted with N2), 10% H2 (diluted with N2), 15% H2 (diluted with N2), or 5% CO (diluted with N2).

[0073] In step (2), the reduction conditions may include: a catalyst heating rate of 2-20℃ / min, a reduction temperature of 300-450℃, and a reduction time of 1-10h.

[0074] In the method described in this invention, the amounts of various reaction raw materials used in steps (1) to (2) are such that, in the prepared monolithic noble metal catalyst, the content of the active component relative to 100 parts by weight of the porous structured support can be 0.1-1 parts by weight, preferably 0.2-0.5 parts by weight.

[0075] The present invention also provides a monolithic noble metal catalyst prepared by the above method. In this monolithic noble metal catalyst, by controlling the surface defect site structure of the monolithic catalyst, the dispersion of active components and exposure of the active phase are promoted; and the catalytic active sites on the catalyst surface are efficiently constructed, reducing the noble metal content while increasing the adsorption capacity of carbon-based oxygen-containing molecular gases and oxygen, promoting oxygen adsorption and activation, thereby improving the catalytic efficiency of the catalyst.

[0076] This invention also provides the application of the above-mentioned monolithic noble metal catalyst in the catalytic oxidation of carbon-based oxygen-containing molecular gases.

[0077] The following examples further illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0078] Unless otherwise specified, the experimental methods used in the following embodiments are conventional methods in the art. Unless otherwise specified, the experimental materials used in the following embodiments are commercially available.

[0079] Example 1

[0080] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0081] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0082] Next, 0.5 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1) and 200 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 9 for 3 h to obtain solution 1.

[0083] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 250°C for 6 hours. Then, it was reduced at 400°C (heating rate 10°C / min) for 5 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-1. The catalyst contained 0.35% by weight of active noble metal and 3% by weight of additives. The particle size of the active noble metal was between 2.1 and 2.4 nm, the mesopore size distribution was 3-4 nm, and the specific surface area was approximately 400 m². 2 / g.

[0084] The TEM and SEM-Mapping images of the monolithic noble metal catalyst are shown below. Figure 1 and Figure 2 As shown.

[0085] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 245℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0086] Example 2

[0087] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0088] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / hydrochloric acid (mixed acid ratio 1:1) at 90°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 500°C with an air flow of 1000 ml / min to obtain a porous structured carrier.

[0089] Next, 0.5 L of a mixed solution of 1 mol / L chloroplatinic acid and palladium chloride (platinum-palladium molar ratio of 1:1) and 200 mL of a mixed solution of 1 mol / L cerium nitrate and lanthanum nitrate (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 10 for 3 h to obtain solution 1.

[0090] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 250°C for 6 hours. Then, it was reduced at 400°C (heating rate 10°C / min) for 5 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-2. The catalyst contained 0.35 wt% of active noble metal and 3 wt% of additives. The particle size of the active noble metal was between 2.2 and 2.5 nm, the mesopore size distribution was 10-12 nm, and the specific surface area was approximately 300 m². 2 / g.

[0091] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 275℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0092] Example 3

[0093] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:5) under reflux at 50°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 800°C under an air flow of 1000 ml / min to obtain a porous structured carrier.

[0094] Next, 0.5 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1) and 200 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 12 for 3 h to obtain solution 1.

[0095] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 250°C for 6 hours. Then, it was reduced at 400°C (heating rate 10°C / min) for 5 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-3. The catalyst contained 0.35% by weight of active noble metal and 3% by weight of additives. The particle size of the active noble metal was between 2.6 and 2.8 nm, the mesopore size distribution was 0.5-2 nm, and the specific surface area was approximately 600 m². 2 / g.

[0096] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 295℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0097] Example 4

[0098] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0099] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 1 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0100] Next, 0.6 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1.5:1) and 240 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 10 for 3 h to obtain solution 1.

[0101] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 200°C for 10 hours. Then, it was reduced at 420°C (heating rate 8°C / min) for 6 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-4. The catalyst contained 0.38% by weight of active noble metal and 3.5% by weight of additives. The particle size of the active noble metal was between 2.2 and 2.3 nm, the mesopore size distribution was 2-3 nm, and the specific surface area was approximately 450 m². 2 / g.

[0102] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 235℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 450 h (i.e., the catalyst activity did not significantly decrease after 450 h of continuous reaction).

[0103] Example 5

[0104] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0105] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 5 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0106] Next, 0.8 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1.5) and 250 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 11 for 3 h to obtain solution 1.

[0107] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 220°C for 8 hours. Then, it was reduced at 380°C (heating rate 12°C / min) for 7 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-5. The catalyst contained 0.51 wt% of active noble metal and 3.8 wt% of additives. The particle size of the active noble metal was between 2.5 and 2.6 nm, the mesopore size distribution was 10-12 nm, and the specific surface area was approximately 500 m². 2 / g.

[0108] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 305℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0109] Example 6

[0110] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0111] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0112] Next, 1 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 2:1) and 180 ml of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 12 for 3 h to obtain solution 1.

[0113] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 250°C for 5 hours. Then, it was reduced at 360°C (heating rate 15°C / min) for 10 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-6. The catalyst contained 0.63% by weight of active noble metal and 2.5% by weight of additives. The particle size of the active noble metal was between 2.2 and 2.3 nm, the mesopore size distribution was 2-2.5 nm, and the specific surface area was approximately 430 m². 2 / g.

[0114] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 225℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0115] Example 7

[0116] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0117] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 h. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 500°C under an air flow of 1000 ml / min to obtain a porous structured carrier.

[0118] Next, 0.7 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:2) and 240 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:1) were stirred at 25 °C and pH 9 for 3 h to obtain solution 1.

[0119] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 280°C for 4 hours. Then, it was reduced at 320°C (heating rate 18°C / min) for 9 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-7. The catalyst contained 0.45 wt% of active noble metal and 3.6 wt% of additives. The particle size of the active noble metal was between 2.5 and 2.7 nm, the mesopore size distribution was 3-4 nm, and the specific surface area was approximately 400 m². 2 / g.

[0120] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 255℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 450 h (i.e., the catalyst activity did not significantly decrease after 450 h of continuous reaction).

[0121] Example 8

[0122] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0123] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0124] Next, 0.5 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1) and 200 mL of a 1 mol / L ferric nitrate and zirconium nitrate mixed solution (ferric-zirconium molar ratio of 1:1) were stirred at 25 °C and pH 9 for 3 h to obtain solution 1.

[0125] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 250°C for 6 hours. Then, it was reduced at 400°C (heating rate 10°C / min) for 5 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-8. The catalyst contained 0.35% by weight of active noble metal and 3% by weight of additives. The particle size of the active noble metal was between 2.1 and 2.4 nm, the mesopore size distribution was 3-4 nm, and the specific surface area was approximately 400 m². 2 / g.

[0126] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 315℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 350 h (i.e., the catalyst activity did not significantly decrease after 350 h of continuous reaction).

[0127] Example 9

[0128] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0129] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0130] Next, 0.7 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1) and 220 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 2:1) were stirred at 25 °C and pH 10 for 3 h to obtain solution 1.

[0131] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 240°C for 7 hours. Then, it was reduced at 410°C (heating rate 5°C / min) for 4 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-9. The catalyst contained 0.46 wt% of active noble metal and 3.2 wt% of additives. The particle size of the active noble metal was between 2.5 and 2.7 nm, the mesopore size distribution was 3-4 nm, and the specific surface area was approximately 400 m². 2 / g.

[0132] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 325℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0133] Example 10

[0134] This embodiment is used to illustrate the monolithic noble metal catalyst, its preparation method, and its application according to the present invention.

[0135] First, commercially available cordierite honeycomb ceramic (200 cpsi, 100×100×50 mm) was treated with 2 mol / L nitric acid / sulfuric acid (mixed acid ratio 1:10) under reflux at 80°C for 24 hours. After washing with deionized water until the pH reached 7, the ceramic was dried to obtain an acid-treated structured carrier. The acid-treated structured carrier was then calcined at 1000 ml / min airflow and 1000°C to obtain a porous structured carrier.

[0136] Next, 0.9 L of a 1 mol / L chloroplatinic acid and palladium chloride mixed solution (platinum-palladium molar ratio of 1:1) and 250 mL of a 1 mol / L cerium nitrate and lanthanum nitrate mixed solution (cerium-lanthanum molar ratio of 1:2) were stirred at 25 °C and pH 11 for 3 h to obtain solution 1.

[0137] The porous, structured support was immersed in solution 1 and allowed to stand for 30 minutes. After removal, it was purged with a 2 MPa air knife and dried in a 100°C oven for 12 hours, followed by calcination at 260°C for 5 hours. Then, it was reduced at 440°C (heating rate 3°C / min) for 2 hours under a 10% H₂ and 90% N₂ atmosphere to obtain the monolithic noble metal catalyst Cat-10. The catalyst contained 0.58 wt% active noble metal and 3.7 wt% additives. The active noble metal particle size was between 2.5 and 2.8 nm, the mesopore size distribution was 3-4 nm, and the specific surface area was approximately 400 m². 2 / g.

[0138] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was 300℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that CO ≤ 100 ppm, VOCs ≤ 120 ppm, the conversion rate ≥ 99%, and the catalyst stability was 500 h (i.e., the catalyst activity did not significantly decrease after 500 h of continuous reaction).

[0139] Comparative Example 1

[0140] The monolithic noble metal catalyst prepared according to the method of Example 1 differs in that the cordierite honeycomb ceramic is not acid-treated or calcined. Instead, the cordierite honeycomb ceramic is directly impregnated in a mixed solution containing chloroplatinic acid, palladium chloride, cerium nitrate, and lanthanum nitrate, and then sequentially subjected to high-pressure air knife purging, drying, calcination, and reduction to obtain the monolithic noble metal catalyst Cat-D1. The catalyst contains 0.05% by weight of active noble metal component, 0.1% by weight of additive, and the active noble metal component has a particle size between 2.1 and 2.3 nm, is non-mesoporous, and has a specific surface area of ​​approximately 50 m². 2 / g.

[0141] The catalyst was packed into a fixed-bed reactor. The feed gas consisted of 95% CO2, 4% CO, and 1% VOCs, with a reaction space velocity of 5000 h⁻¹. -1 The reaction pressure was 0.1 MPa, and the reaction temperature was ≥500℃. Gas chromatography was used to detect the CO and VOC concentrations at the reactor outlet. The results showed that the CO concentration was approximately 5000 ppm, the VOC concentration was approximately 5000 ppm, the conversion rate was ≤5%, and the catalyst stability was poor (less than 50 h).

[0142] As can be seen from the above examples and comparative examples, the monolithic noble metal catalyst prepared by the present invention exhibits good catalytic effect in the catalytic oxidation of carbon-based oxygen-containing molecular gases, and the catalyst has significantly better stability, making it suitable for continuous long-term operation.

[0143] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A monolithic noble metal catalyst, characterized by, The invention includes a porous structured support and an active component loaded on the porous structured support. The active component contains a noble metal and an alloy metal, and the particle size of the active component is 1-8 nm. The noble metal is a combination of platinum and palladium, and the molar ratio of platinum to palladium is 1:0.5-2. The alloy metal is a combination of La and Ce, and the molar ratio of La to Ce is 1:0.5~2. The preparation method of the monolithic noble metal catalyst includes the following steps: (1) The structured carrier is subjected to acid treatment and calcination in sequence to obtain a porous structured carrier; (2) The porous structured carrier is immersed in a mixed solution containing a noble metal precursor and a structural aid, and then subjected to high-pressure air knife purging, drying, calcination and reduction in sequence; In step (1), the acid treatment process includes: reflux treatment of the regularized carrier with a mixed acid solution, followed by washing until neutral and drying; the mixed acid is a mixture of nitric acid and sulfuric acid or hydrochloric acid, and the molar ratio of nitric acid to sulfuric acid or hydrochloric acid is 1:1-10; The structural additive is selected from at least one of ferric nitrate, cerium nitrate, lanthanum nitrate, lanthanum sulfate, lanthanum chloride, cerium sulfate, and cerium trioxide; During the reduction process, the reducing atmosphere is H2, CO, a combination of H2 and CO, a mixed atmosphere with different hydrogen concentrations, or a mixed atmosphere with different CO concentrations.

2. The monolithic noble metal catalyst according to claim 1, characterized in that The particle size of the active component is 2~6 nm.

3. The monolithic noble metal catalyst according to claim 1 or 2, characterized in that The monolithic noble metal catalyst has a mesopore channel size of 0.1-20 nm, a specific surface area of 200-800 m 2 / g.

4. The monolithic noble metal catalyst of claim 3, wherein The content of the active component is 0.1-1 parts by weight relative to 100 parts by weight of the porous structured carrier.

5. The monolithic noble metal catalyst of claim 3, wherein In step (1), the calcination process is carried out under conditions of 100-1000 ml / min air flow and 100-1000 °C.

6. The monolithic noble metal catalyst of claim 3, wherein The regularized carrier is selected from at least one of cordierite honeycomb carrier, mullite honeycomb carrier, diamond honeycomb carrier, corundum honeycomb carrier, zirconium corundum honeycomb carrier, quartz honeycomb carrier, nepheline honeycomb carrier, feldspar honeycomb carrier and alumina honeycomb carrier.

7. The monolithic noble metal catalyst of claim 3, wherein In the active component, the molar ratio of the noble metal to the alloy metal is 1:0.1-0.

3.

8. The monolithic noble metal catalyst of claim 3, wherein The noble metal precursor is selected from chloroplatinic acid, 2-hydroxyethylamine salt of platinum(IV) hydroxyacetate, platinum chloride, platinum nitrate, platinum acetylacetonate, palladium chloride, palladium nitrate and palladium acetate.

9. The monolithic noble metal catalyst of claim 3, wherein The concentration of the mixed acid is 2-10 mol / L.

10. The monolithic noble metal catalyst of claim 3, wherein The reflux treatment conditions include: a temperature of 50-90℃ and a time of 1-24 hours.

11. The monolithic noble metal catalyst of claim 3, wherein In step (2), the pH of the mixed solution containing the noble metal precursor and the structural aid is 9-12.

12. The monolithic noble metal catalyst of claim 3, wherein In step (2), the high-pressure air knife purging process is to use an air knife with a pressure of 1.5-2.5 MPa for purging.

13. The monolithic noble metal catalyst of claim 3, wherein In step (2), the roasting conditions include: a temperature of 200-300℃ and a time of 4-10 hours.

14. The monolithic noble metal catalyst of claim 3, wherein The reduction conditions include: a catalyst heating rate of 2-20℃ / min, a reduction temperature of 300-450℃, and a reduction time of 1-10h.

15. The use of the monolithic noble metal catalyst according to any one of claims 1-14 in the catalytic oxidation of carbon-based oxygen-containing molecular gases.

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