A sulfur and water resistant pt-based bimetallic co oxidation catalyst and a method of making the same

Abstract

The application discloses a kind of anti-sulfur water Pt-based bimetallic CO oxidation catalyst and preparation method thereof, belong to environmental catalytic material technical field.The catalyst prepared by the application uses titanium dioxide as carrier, and adopts impregnation method to load noble metal platinum and adjuvant molybdenum to form bimetallic active component.The catalyst utilizes the regulation effect of Mo species to Pt electronic structure and the competitive adsorption mechanism of sulfur species, effectively solves the problem that traditional single platinum-based catalyst is easily poisoned and inactivated under sulfur-containing and water-containing conditions.Experiments show that the catalyst can still maintain very high CO conversion rate for a long time under harsh working conditions containing high concentration of sulfur dioxide and water vapor, and has excellent anti-sulfur regeneration performance.The catalyst preparation process is simple, and the stability is good, which is suitable for efficient elimination of carbon monoxide in industrial waste gas and motor vehicle exhaust.

Description

Technical Field

[0001] This invention belongs to the field of environmental catalytic materials technology, specifically, it relates to a supported bimetallic catalyst for the catalytic oxidation of carbon monoxide (CO), particularly a Pt-M (M being a cooperating metal) catalyst that has undergone reduction treatment and exhibits excellent resistance to sulfur poisoning and water. Catalysts and their preparation methods. Background Technology

[0002] Carbon monoxide (CO) is a common toxic gas, widely originating from vehicle exhaust, industrial boiler combustion, and various chemical processes. Catalytic oxidation is one of the most effective methods for eliminating CO. Among numerous catalysts, supported platinum (Pt) catalysts are widely studied and applied due to their high activity at low temperatures.

[0003] However, actual industrial waste gas or vehicle exhaust usually contains a certain amount of sulfur dioxide (SO2). ) and water vapor ( Traditional Catalyst in the presence In this case, Sulfates readily adsorb onto active sites or react with the support / active component to form sulfates, leading to severe catalyst poisoning and deactivation. Furthermore, the presence of water vapor often exacerbates this poisoning or reduces catalytic efficiency through competitive adsorption.

[0004] Existing solutions typically involve adding a desulfurization unit upstream of the catalyst. However, this method significantly increases system complexity, energy consumption, and operating costs, and its effectiveness is limited for treating exhaust gases with fluctuating sulfur content or high concentrations. Therefore, developing a method for treating exhaust gases rich in sulfur is crucial. and CO oxidation catalysts that can maintain high activity and high stability even under harsh environments have significant industrial application value. Summary of the Invention

[0005] The purpose of this invention is to address the issue that existing supported platinum (Pt)-based catalysts are prone to problems when treating industrial waste gas or vehicle exhaust due to the presence of sulfur dioxide (Pt) in the waste gas. ) and water vapor ( To address the technical problem of poisoning leading to a sharp decline or even deactivation of catalytic activity, this paper provides a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions: A method for preparing a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst includes the following steps: S1. Dissolve the soluble platinum salt and the soluble anti-sulfur additive metal M in deionized water, and stir thoroughly to obtain a mixed metal salt solution, which is also the impregnation precursor solution containing the active component. S2. Titanium dioxide powder is used as a carrier and added to the mixed metal salt solution in step S1. The mixture is stirred and impregnated. The impregnated slurry is continuously stirred under water bath conditions until the water evaporates to a viscous or paste-like state, thus obtaining a mixture loaded with active components. S3. The mixture of loaded active components obtained in step S2 is dried to remove the solvent and obtain a solid powder. The dried solid powder is then calcined at high temperature in an oxygen-containing atmosphere to obtain an oxidized catalyst precursor. S4. The oxidized catalyst precursor obtained in step S3 is placed in a reducing atmosphere and reduced at high temperature. After cooling, a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst is obtained.

[0007] As a further technical solution, the soluble platinum salt in step S1 is one of chloroplatinic acid, platinum nitrate, and potassium chloroplatinate.

[0008] As a further technical solution, the salt of the soluble antisulfur additive metal M in step S1 is one of ammonium molybdate, ammonium tungstate, ferric nitrate, cobalt nitrate, and nickel nitrate.

[0009] As a further technical solution, the impregnation operation in step S2 is as follows: The mixed metal salt solution is added dropwise to the solution using either an equal-volume impregnation method or an excess impregnation method. The metal salt solution is added to the carrier or in steps.

[0010] As a further technical solution, the temperature of the water bath in step S2 is 60-90℃, and the water bath time is 4-12h, to ensure that the active components are uniformly dispersed on the surface of the carrier.

[0011] As a further technical solution, the drying temperature in step S3 is 100-120℃, and the time is 8-12h.

[0012] As a further technical solution, the high-temperature calcination in step S3 is carried out in an air atmosphere, with a temperature of 300-600℃ and a time of 2-6 hours.

[0013] As a further technical solution, the reducing atmosphere in step S4 is pure hydrogen or hydrogen mixed with an inert gas (such as Ar, etc.). A mixture of gases, wherein the volume concentration of hydrogen is 5-100%.

[0014] As a further technical solution, the reduction treatment temperature in step S4 is 200-600℃, and the time is 1-4h.

[0015] In the preparation process of this invention, step S1 involves preparing a homogeneous mixed solution by combining the active component (platinum Pt) and the soluble salt precursor of the anti-sulfur agent (metal M, such as Mo or W). In step S2, the mixed solution is brought into full contact with the titanium dioxide support, and the active component precursor is transported to the entire pore structure and surface of the support through capillary action. In step S3, the solvent is first slowly removed to allow the metal salt precursor adsorbed on the support to crystallize and fix on the support surface. Then, high-temperature calcination is performed to decompose the loaded metal salt precursor and convert it into the corresponding metal oxide (such as...). , Finally, in step S4, the calcined oxide precursor is heat-treated in a reducing atmosphere to promote the formation of a bimetallic interface or alloy structure between Pt and the anti-sulfur additive metal M.

[0016] The beneficial effects of this invention are: 1. Excellent sulfur and water resistance: This invention effectively inhibits sulfur and water damage by introducing an auxiliary metal M to construct a bimetallic system. The strong adsorption at the active sites of Pt solves the problem that traditional Pt catalysts deactivate upon contact with sulfur. 2. The specific "calcination and reduction" process enhances the intermetallic interaction: The present invention adopts a preparation strategy of first high-temperature oxidation calcination and then hydrogen reduction. The calcination step ensures the full decomposition of the metal precursor and its anchoring with the support, while the subsequent hydrogen reduction step promotes the formation of a tight bimetallic interface or alloy structure between Pt and the auxiliary metal M, which optimizes the electron cloud density of Pt, thereby fundamentally improving the intrinsic anti-poisoning performance of the catalyst. 3. Good regeneration capacity and industrial application prospects: The catalyst preparation method of this invention is simple and the raw materials are readily available, making it suitable for widespread application in the treatment of industrial tail gas containing sulfur and water. In summary, the catalyst of this invention has excellent stability and resistance to poisoning, and has important application value in the treatment of industrial waste gas or automobile exhaust. Attached Figure Description

[0017] The invention will now be further described with reference to the accompanying drawings.

[0018] Figure 1 This is a transmission electron microscope (TEM) structural diagram of the catalyst prepared in Example 1 of the present invention.

[0019] Figure 2 The catalyst prepared in Example 1 of this invention contains and Figure showing the results of CO oxidation stability test under different atmospheres.

[0020] Figure 3This is a comparison diagram of the CO oxidation activity of the catalyst prepared in Example 1 of the present invention and the catalyst prepared in Comparative Example 1 before and after sulfidation. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention. Example 1

[0022] A method for preparing a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst includes the following steps: S1. Weigh out the required chloroplatinic acid and ammonium molybdate according to the ratio of 1wt% Pt loading and 1wt% Mo loading, dissolve them in deionized water, and stir thoroughly to obtain a mixed metal salt solution, which is also the impregnation precursor solution containing active components. S2. Titanium dioxide powder is added to the mixed metal salt solution in step S1 as a carrier and stirred and impregnated. The impregnated slurry is stirred continuously in a water bath at 70°C for 12 hours until the water evaporates to a viscous or paste-like state, to obtain a mixture loaded with active components. S3. The mixture of loaded active components obtained in step S2 is dried at 80°C for 12 hours to remove the solvent and obtain a solid powder. The dried solid powder is then calcined at 550°C in an oxygen-containing atmosphere in a muffle furnace for 4 hours to obtain an oxidized catalyst precursor. S4. Place the oxidized catalyst precursor obtained in step S3 in a reducing atmosphere. In a mixed gas, a reduction treatment was carried out at 600℃ for 1 hour, and then cooled to obtain a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst. Example 2

[0023] The only difference between this embodiment and Embodiment 1 is that in this embodiment, ammonium molybdate is replaced with an equimolar amount of ammonium metatungstate to obtain a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst.

[0024] Comparative Example The only difference between this comparative example and Example 1 is that in this comparative example, no ammonium molybdate precursor was added, and only Pt was loaded to prepare the catalyst.

[0025] The catalyst in the example was analyzed using transmission electron microscopy, and the TEM images are shown below. Figure 1 As shown, from Figure 1As can be seen, in the PtMo bimetallic system constructed after reduction treatment, both Pt and Mo are highly dispersed in... On the carrier; A fixed-bed quartz reactor was used, filled with the catalyst from Example 1, and simulated waste gas (components: 1% CO, ...) was introduced. , (The equilibrium gas is air), the reaction temperature is kept constant at 280℃, and the CO concentration at the reactor outlet is detected by gas chromatography (GC) every 5 minutes. The CO conversion rate is calculated, and a curve is plotted with conversion rate and reaction time as coordinates to obtain the results. Figure 2 Experimental results show that, with For example, this catalyst can withstand temperatures up to 280°C. and Under harsh conditions of coexistence, it can maintain a stable CO conversion rate for a long time (>500 minutes), demonstrating excellent stability; The catalysts from Example 1 and the comparative example were divided into two groups. One group underwent sulfidation treatment, while the other group was left untreated. The CO conversion rates of the "unsulfidated" and "sulfidated" catalyst samples were measured at different temperatures, and activity curves were plotted to obtain... Figure 3 Experimental results show that the catalyst of the present invention exhibits minimal ignition temperature drift after sulfidation treatment, demonstrating extremely strong tolerance.

[0026] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0027] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A method for preparing a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst, characterized in that, Includes the following steps: S1. Dissolve the soluble platinum salt and the soluble anti-sulfur additive metal M in deionized water, and stir thoroughly to obtain a mixed metal salt solution. S2. Titanium dioxide powder is used as a carrier and added to the mixed metal salt solution in step S1, and stirred and impregnated. The impregnated slurry is continuously stirred under water bath conditions until the water evaporates to a viscous or paste-like state, thus obtaining a mixture loaded with active components. S3. The mixture of loaded active components obtained in step S2 is dried to obtain a solid powder. The dried solid powder is then calcined at high temperature in an oxygen-containing atmosphere to obtain an oxidized catalyst precursor. S4. The oxidized catalyst precursor obtained in step S3 is placed in a reducing atmosphere and reduced at high temperature. After cooling, a sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst is obtained.

2. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, The soluble platinum salt in step S1 is one of chloroplatinic acid, platinum nitrate, or potassium chloroplatinate.

3. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S1, the salt of the soluble antisulfur additive metal M is one of ammonium molybdate, ammonium tungstate, ferric nitrate, cobalt nitrate, and nickel nitrate.

4. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, The impregnation operation in step S2 is as follows: using either the equal-volume impregnation method or the excess impregnation method, the mixed metal salt solution is added dropwise to... The metal salt solution is added to the carrier or in steps.

5. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S2, the water bath temperature is 60-90℃ and the water bath time is 4-12 hours.

6. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S3, the drying temperature is 100-120℃ and the time is 8-12h.

7. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S3, the high-temperature calcination is carried out in an air atmosphere at a temperature of 300-600℃ for 2-6 hours.

8. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S4, the reducing atmosphere is pure hydrogen or a mixture of hydrogen and an inert gas, wherein the volume concentration of hydrogen is 5-100%.

9. The preparation method of the sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst according to claim 1, characterized in that, In step S4, the reduction treatment is carried out at a temperature of 200-600℃ for 1-4 hours.

10. A sulfur- and water-resistant Pt-based bimetallic CO oxidation catalyst, characterized in that, Prepared according to the method according to any one of claims 1-9.

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