Bimetal catalyst as well as preparation method and application thereof
By combining bimetallic catalysts with molybdenum and platinum on the catalyst support, the existing catalysts have been solved, with low activity, short life and susceptible to chlorine poisoning, and a catalytic purification effect with high efficiency, long life and anti-chlorine poisoning is achieved.
Patent Information
- Application Number
- CN202510276194.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-10
- Publication Date
- 2025-06-10
AI Technical Summary
When treating mixed volatile organic compounds, existing catalysts have low activity, short life, and are susceptible to chlorine poisoning, resulting in loss of catalytic activity and increased toxicity of pollutants.
The catalyst is prepared by hydrothermal method by using cerium oxide as a support, combining transition metal molybdenum and noble metal platinum, to ensure the high dispersion of molybdenum and platinum and the anti-poisoning ability of active sites.
It realizes the high activity, long life and strong anti-chlorine poisoning oxidation ability of the catalyst, and can efficiently purify mixed volatile organic compounds under lower temperature and high aerial speeds, with the advantages of being more economical and green and environmentally friendly.
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Figure CN120115148A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of catalysts, and in particular to a bimetallic catalyst, a preparation method thereof, and an application in catalytic purification of mixed volatile organic compounds. Background Art
[0002] With the development of modern industry, environmental problems are increasing day by day. Modern industrial production is always accompanied by the emission of a large amount of polluted waste gas. How to purify the polluted waste gas has become a key issue in environmental protection. Among them, VOCs are one of the important air pollution sources. Due to their volatile characteristics, they are extremely easy to generate from daily industrial production. The sources of VOCs are diverse, and the types of VOCs emitted from different fixed sources are also different. Usually, the VOCs emitted by industries are mostly mixed VOCs, and appropriate catalysts need to be prepared according to the actual working conditions to achieve the best results.
[0003] Ethyl acetate is often used as a solvent for drug synthesis, so it is commonly found in the pollutants discharged by pharmaceutical factories. However, in addition to containing a large amount of ethyl acetate, there are also other VOCs in the pollutants, such as benzene, toluene, propane, chlorobenzene, etc. It is worth noting that chlorobenzene, as a chlorine-containing VOC, is prone to cause the deactivation of the catalyst due to chlorine poisoning during the catalytic combustion process, especially the poisoning effect on noble metals. After being poisoned by chlorine, noble metals not only lose their catalytic combustion activity, but also increase the toxicity of pollutants. Therefore, it is urgent to prepare a catalyst with high activity, high lifespan, and anti-chlorine poisoning ability. In view of the above problems, the catalyst prepared by the present invention has the characteristics of highly dispersed zero-valent Pt, high activity even at high space velocities of reactants, and strong anti-chlorine poisoning oxidation ability in the treatment of organic waste gas. Summary of the Invention
[0004] The purpose of the present invention is to solve the deficiencies existing in the prior art, and to provide a bimetallic catalyst, a preparation method thereof, and an application in catalytic purification of mixed volatile organic compounds.
[0005] To achieve the above purpose, the present invention adopts the following technical solutions:
[0006] A bimetallic catalyst, the catalyst comprises the following components:
[0007] Using cerium oxide as the catalyst carrier, the bimetallic active components include transition metal molybdenum and noble metal platinum;
[0008] Wherein the content of transition metal molybdenum is 2-8% of the mass of the carrier, and the content of noble metal platinum is 0.25-1% of the mass of the carrier.
[0009] A preparation method of the bimetallic catalyst according to claim 1, comprising the following steps:
[0010] S1: Prepare a solution with appropriate concentrations of a cerium precursor and urea, place it in a hydrothermal reactor for hydrothermal reaction, then perform suction filtration, washing, drying, and calcination to obtain Support I.
[0011] S2: Prepare Solution A with an appropriate concentration from the precursors of the bimetallic active components;
[0012] S3: Take a certain amount of Solution A and mix it with Support I, impregnate, dry, and calcine to obtain the catalyst.
[0013] Preferably, in step S1, the cerium precursor is a soluble salt of cerium;
[0014] The salt of transition metal cerium is selected from at least one of cerium nitrate, cerium chloride, and cerium acetate;
[0015] The hydrothermal reaction temperature is 100 - 180 °C; the reaction time is 2 - 15 hours, the drying temperature is 80 - 120 °C, and the time is 4 - 12 hours; the calcination temperature is 400 - 500 °C; the calcination time is 2 - 6 hours.
[0016] Preferably, in step S2, the precursors of the bimetallic active components are ammonium salts of molybdenum and acidic compounds of noble metals;
[0017] The ammonium salts of transition metal molybdenum are selected from at least one of ammonium molybdate and ammonium metatungstate;
[0018] The acidic compounds of noble metals are selected from at least one of platinum nitrate, platinum chloride, palladium nitrate, and palladium chloride.
[0019] Preferably, in step three: the impregnation is isovolumetric impregnation;
[0020] The drying time is 4 - 18 hours; the drying temperature is 80 - 120 °C, the calcination temperature is 400 - 500 °C; the calcination time is 2 - 6 hours.
[0021] The present invention also provides an application of the bimetallic catalyst in catalytic purification of mixed volatile organic compounds. The bimetallic catalyst prepared according to claim 1 is applied to the low-temperature and high-air-speed catalytic combustion purification of organic waste gas composed of volatile organic compounds such as chloroalkanes, chloroaromatics, chloroolefins, and other oxygen-containing or oxygen-free organic compounds in industrial emissions.
[0022] Advantages of the present invention:
[0023] 1. The effective active components of the catalyst with the characteristics of the present invention are highly dispersed, the active sites have strong anti-poisoning ability, good activity, long lifespan, and more efficient catalysis.
[0024] 2. The catalyst of the present invention is applied to the catalytic purification of mixed chlorine-containing or chlorine-free volatile organic compounds, enabling the harmful volatile organic compounds to be purified under conditions of lower temperature and higher space velocity, with the advantages of a more economical reaction system, environmental friendliness, and a long service life. BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Figure 1 It is a line graph of the conversion rate at different temperatures for each example;
[0026] Figure 2 It is the CO adsorption infrared spectrum of the catalyst Mo-Pt / CeO 2 -1;
[0027] Figure 3 It is the CO adsorption infrared spectrum of the catalyst Mo-Pt / CeO 2 -4. DETAILED DESCRIPTION OF THE EMBODIMENTS
[0028] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments.
[0029] Example 1
[0030] 80 mL of deionized water was added to a 100 mL polytetrafluoroethylene inner liner, and then 20 g of Ce(NO 3 ) 3 ·6H 2 O and 6 g of CH 4 N 2 O were added to the deionized water. A rotor was added and stirred at 400 r / min for 30 min. After complete dissolution, the inner liner was placed in a hydrothermal autoclave and reacted in an oven at 140 °C for 300 min. After natural cooling to room temperature, the solution in the autoclave was filtered by suction, and washed with a large amount of deionized water until the filtrate was neutral. The filter cake was placed in an oven at 80 °C and dried overnight. The dried filter cake was crushed with a mortar and placed in a muffle furnace. The temperature was raised from room temperature to 450 °C at a rate of 2 °C / min and calcined at this temperature for 4 h. The required catalyst support was obtained and named CeO 2 .
[0031] Ammonium molybdate was selected as the precursor to prepare a standard aqueous solution of (NH 4 ) 6 H 8 Mo 7 O 28 with a Mo concentration of 60 g / L. Chloroplatinic acid was selected as the noble metal precursor to prepare a standard aqueous solution of chloroplatinic acid with a Pt concentration of 50 g / L. 15 g of the support CeO 2, Take 10 mL of the prepared molybdenum standard solution (Mo content is 60 g / L), and 1.5 mL of the prepared platinum standard solution (Pt content is 50 g / L), add them to the carrier and impregnate for 12 h with equal volume. After drying at 80 °C, calcine at 450 °C for 4 h to obtain Mo-Pt / CeO 2 -1. According to Figure 2 The CO adsorption infrared spectrum, it can be seen that there is a Pt adsorption peak at 2094 cm -1 which is attributed to highly dispersed zero-valent Pt and is beneficial to enhancing the catalytic activity in this reaction.
[0032] The catalyst in this example: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the catalyst reaction space velocity is 100,000 mL / (h·g), and the reaction temperature is 100 - 300 °C. Under these conditions, the mixed reactants can be completely converted into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C. For example, Figure 1 at 260 °C, the conversion rate is maintained at 90%, and there is no obvious deactivation phenomenon within 20 hours. It proves that the catalyst has good stability and high space velocity activity.
[0033] Example 2
[0034] Same as Example 1, except that
[0035] The adjusted dosage of transition metal Mo is 15 mL, and the Mo content of the obtained catalyst is 6%. The catalyst Mo-Pt / CeO 2 -2. The CO adsorption infrared spectrum is similar to Figure 2 that, and there is a Pt adsorption peak at 2094 cm -1 which is attributed to highly dispersed zero-valent Pt and is beneficial to enhancing the catalytic activity in this reaction.
[0036] The catalyst in this example: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the catalyst reaction space velocity is 100,000 mL / (h·g), and the reaction temperature is 100 - 300 °C. Under these conditions, the mixed reactants can be completely converted into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C. For example, Figure 1 at 260 °C, the conversion rate is maintained at 85%, and there is no obvious deactivation phenomenon within 20 hours. It proves that the catalyst has good stability and high space velocity activity.
[0037] Example 3
[0038] Same as Example 1, except that
[0039] The adjusted dosage of noble metal Pt is 3 mL, and the Pt content of the obtained catalyst is 1%. The catalyst Mo-Pt / CeO2 -3. The CO adsorption infrared spectrum is similar to Figure 2 that, and the Pt adsorption peak at 2094 cm -1 is attributed to highly dispersed zero-valent Pt, which is beneficial to enhancing the catalytic activity in this reaction.
[0040] The catalyst in this example can completely convert the mixed reactants into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C under the conditions of: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the catalyst reaction space velocity of 100,000 mL / (h·g), and the reaction temperature of 100 - 300 °C. As Figure 1 for the conversion rate at 260 °C is maintained at 85%, and there is no obvious deactivation phenomenon within 20 hours. It proves that the catalyst has good stability and high space velocity activity.
[0041] Example 4
[0042] Same as Example 1, except that
[0043] the adjusted dosage of transition metal Mo is 2.5 mL, and the Mo content of the obtained catalyst is 1%. The obtained catalyst is Mo-Pt / CeO 2 -4. The CO adsorption infrared spectrum is as Figure 3 shown, and there is no zero-valent Pt adsorption peak at 2094 cm -1 , which is not conducive to the progress of this reaction.
[0044] The catalyst in this example can completely convert the mixed reactants into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C under the conditions of: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the catalyst reaction space velocity of 100,000 mL / (h·g), and the reaction temperature of 100 - 300 °C. As Figure 1 for the conversion rate at 260 °C rapidly drops to 75% after a short time, proving that the catalyst has good high space velocity activity but the stability has decreased.
[0045] Example 5
[0046] Same as Example 1, except that
[0047] the adjusted dosage of noble metal Pt is 0.3 mL, and the Pt content of the obtained catalyst is 0.1%. The obtained catalyst is Mo-Pt / CeO 2 -5. The CO adsorption infrared spectrum is similar to Figure 2 that, and the Pt adsorption peak at 2094 cm -1 is attributed to highly dispersed zero-valent Pt, which is beneficial to enhancing the catalytic activity in this reaction.
[0048] The catalyst of this example can completely convert the mixed reactants into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C under the conditions of: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the reaction space velocity of the catalyst is 100,000 mL / (h·g), and the reaction temperature is 100 - 300 °C. As Figure 1 The conversion rate of the reaction at 260 °C was maintained at 78%, and there was no obvious deactivation within 20 hours. It is proved that the catalyst has good stability, but its activity is slightly affected due to the decrease in the content of Pt.
[0049] Example 6
[0050] Same as Example 1, except that
[0051] The noble metal Pt precursor was changed to platinum nitrate, and the dosage was still 1.5 mL. The Pt content of the obtained catalyst was 0.5%. The catalyst Mo-Pt / CeO 2 -6. The CO adsorption infrared spectrum is similar to Figure 2 that, and the Pt adsorption peak at 2094 cm -1 is attributed to highly dispersed zero-valent Pt, which is beneficial to improving the catalytic activity in this reaction.
[0052] The catalyst of this example can completely convert the mixed reactants into non-toxic and non-polluting products such as carbon dioxide and water at 280 °C under the conditions of: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the reaction space velocity of the catalyst is 100,000 mL / (h·g), and the reaction temperature is 100 - 300 °C. As Figure 1 The conversion rate of the reaction at 260 °C was maintained at 87%, and there was no obvious deactivation within 20 hours. It is proved that the catalyst has good stability and high space velocity activity.
[0053] Example 7
[0054] Same as Example 1, except that
[0055] The temperature in the hydrothermal reaction for preparing the carrier was adjusted to 200 °C. The catalyst Mo-Pt / CeO 2 -7. The CO adsorption infrared spectrum is similar to Figure 2 that, and the Pt adsorption peak at 2094 cm -1 is attributed to highly dispersed zero-valent Pt, which is beneficial to improving the catalytic activity in this reaction.
[0056] The catalyst in this example: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, air as the carrier gas, the catalyst reaction space velocity is 100,000 mL / (h·g), and the mixed reactants are completely converted into non-toxic and non-polluting products such as carbon dioxide and water. As Figure 1 The conversion rate of the reaction at 260 °C was maintained at 50%, and there was no obvious deactivation phenomenon within 20 hours. It was proved that the catalyst had good stability, but its activity was greatly affected, and its activity was poor under the conditions of low temperature and high space velocity.
[0057] Comparative Example 1
[0058] Add 80 mL of deionized water to a 100 mL polytetrafluoroethylene inner liner, then weigh 20 g of Ce(NO 3 ) 3 ·6H 2 O and 6 g of CH 4 N 2 O, add them to the deionized water, add a rotor and stir at 400 r / min for 30 min. After complete dissolution, put the inner liner into a hydrothermal autoclave and react in an oven at 140 °C for 300 min. After natural cooling to room temperature, filter the solution in the autoclave, and wash it with a large amount of deionized water until the filtrate is neutral. Put the filter cake into an oven at 80 °C and dry it overnight. Grind the dried filter cake with a mortar, put it into a muffle furnace, and heat it from room temperature to 450 °C at a heating rate of 2 °C / min, and calcine it at this temperature for 4 h. The required catalyst support obtained is named CeO 2 .
[0059] Weigh 15 g of the support CeO 2 , disperse it in 200 mL of deionized water to obtain suspension A.
[0060] Select ammonium molybdate as the precursor, and prepare a standard aqueous solution of (NH 4 ) 6 H 8 Mo 7 O 28 with a Mo concentration of 60 g / L. Select chloroplatinic acid as the noble metal precursor, and prepare a standard aqueous solution of chloroplatinic acid with a Pt concentration of 50 g / L. Take 10 mL of the prepared molybdenum standard solution (Mo content is 60 g / L) and dilute it to 100 ml to obtain solution B. And take 1.5 mL of the prepared platinum standard solution (Pt content is 50 g / L) and dilute it to 100 ml to obtain solution C. Prepare 100 ml of 0.1 M ammonia water solution to obtain solution D.
[0061] Under stirring conditions, slowly drop solutions B, C, and D into solution A at the same time. After dropping, continue stirring for 2 h, and filter to obtain a precipitate. Wash the precipitate, dry it at 80 °C, and then calcine it at 450 °C for 4 h to obtain Mo-Pt / CeO2 -8. The infrared absorption spectrum of CO adsorption is similar to Figure 3 that of -1 and there is no adsorption peak of zero-valent Pt at 2094 cm
[0062] For the catalyst of this example: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, with air as the carrier gas, and the reaction space velocity of the catalyst is 100,000 mL / (h·g), the mixed reactants are completely converted into non-toxic and non-polluting products such as carbon dioxide and water. For example, Figure 1 the conversion rate of the reaction at 260 °C is maintained at 75%, and there is no obvious deactivation phenomenon within 20 hours. It is proved that the catalyst has good stability, but its activity is slightly affected.
[0063] Comparative Example 2
[0064] Same as Example 1, except that
[0065] the second active component is adjusted to Ru, and the Ru content of the obtained catalyst is 0.1%. The obtained catalyst is Mo-Ru / CeO 2 -9.
[0066] For the catalyst of this example: 100 mg of catalyst, 200 ppm of chlorobenzene + 800 ppm of ethyl acetate, with air as the carrier gas, and the reaction space velocity of the catalyst is 100,000 mL / (h·g), the mixed reactants are completely converted into non-toxic and non-polluting products such as carbon dioxide and water. For example, Figure 1 the conversion rate of the reaction at 260 °C drops from 60% to 50%. It is proved that the stability of the catalyst is slightly affected, but due to the change of the active component, its activity is poor under the conditions of low temperature and high space velocity in application.
[0067] As mentioned above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution and inventive concept of the present invention, makes equivalent substitutions or changes, and all should be covered by the protection scope of the present invention.
Claims
1. A bimetallic catalyst, characterized in that: The catalyst comprises the following components: Cerium oxide is used as the catalyst carrier, and the bimetallic active components include transition metal molybdenum and precious metal platinum; The content of transition metal molybdenum is 2-8% of the carrier mass, and the content of noble metal platinum is 0.25-1% of the carrier mass.
2. The method for preparing a bimetallic catalyst according to claim 1, characterized in that: The following steps are involved: S1: The cerium precursor and urea are prepared into a solution of appropriate concentration, placed in a hydrothermal kettle for hydrothermal reaction, and then filtered, washed, dried and calcined to obtain carrier I. S2: preparing the precursor of the bimetallic active component into a solution A of appropriate concentration; S3: taking a certain amount of solution A and mixing it with carrier I, impregnating, drying, and calcining to obtain the catalyst.
3. A method for preparing a bimetallic catalyst according to claim 2, characterized in that: In the step S1, the cerium precursor is a soluble salt of cerium; The transition metal cerium salt is selected from at least one of cerium nitrate, cerium chloride and cerium acetate; The hydrothermal reaction temperature is 100-180°C; the reaction time is 2-15 hours; the drying temperature is 80-120°C, the time is 4-12 hours; the calcination temperature is 400-500°C; the calcination time is 2-6 hours.
4. A method for preparing a bimetallic catalyst according to claim 2, characterized in that: In the step S2, the precursors of the bimetallic active component are ammonium salt of molybdenum and acidic compounds of noble metals; The ammonium salt of transition metal molybdenum is selected from at least one of ammonium molybdate and ammonium metamolybdate; The acidic compound of the noble metal is selected from at least one of platinum nitrate, platinum chloride, palladium nitrate and palladium chloride.
5. The method for preparing a bimetallic catalyst according to claim 2, characterized in that: In the step 3: the impregnation is equal volume impregnation; The drying time is 4 to 18 hours; the drying temperature is 80-120° C., the roasting temperature is 400 to 500° C.; and the roasting time is 2 to 6 hours.
6. Application of a bimetallic catalyst in catalytic purification of mixed volatile organic compounds, characterized in that: The bimetallic catalyst prepared according to claim 1 is used for low-temperature and high-space-velocity catalytic combustion purification of organic waste gas composed of volatile organic compounds such as chlorinated alkanes, chlorinated aromatic hydrocarbons, chlorinated olefins and other oxygen-containing or oxygen-free organic compounds emitted from industry.