Catalyst for eliminating methylbenzene as well as preparation method and application of catalyst

Abstract

The invention relates to a catalyst for eliminating toluene and a preparation method and application thereof, the chemical formula of the catalyst is 1% Ru / Pr2Ce2O7-300, the preparation method comprises the following steps: preparing praseodymium oxide, cerous nitrate, dilute nitric acid, glucose and acrylic acid as precursor liquid of the catalyst, depositing 1% Ru on a carrier, and carrying out suction filtration, drying and roasting to obtain the catalyst for eliminating toluene. The 1% Ru / Pr2Ce2O7 solid solution type composite oxide catalyst with excellent water resistance and sulfur resistance and large specific surface area is prepared. The catalyst prepared by the invention is low in raw material cost, simple and feasible in preparation process, low in equipment requirement, non-toxic and harmless in solvent and free of secondary pollution to the environment; the 1% Ru / Pr2Ce2O7-300 solid solution type composite oxide catalyst has a relatively large specific surface area, and is beneficial to the contact efficiency of toluene and the catalyst; the catalyst shows excellent activity and excellent water resistance and sulfur resistance in a toluene catalytic combustion elimination reaction.

Description

Technical Field

[0001] The present invention belongs to the technical field of catalytic chemistry. It relates to a preparation method and application of a Pr-based solid solution composite oxide catalyst for toluene elimination. Background Art

[0002] In recent decades, the volatile organic compounds (VOCs) emitted by industries and transportation have increased sharply, causing serious harm to human health and the ecosystem. Therefore, more effective VOCs removal technologies are needed to reduce their global emissions. Catalytic oxidation has the advantages of high catalytic efficiency, no secondary pollution, and easy product control, and is the most promising method for VOCs removal. Currently, catalysts are mainly divided into supported noble metal catalysts (such as Pt, Pd, Ag, Au, Ru, etc.) and non-noble metal catalysts, such as transition metal oxides and mixed oxides. Supported noble metal catalysts are more widely used in low-temperature catalysis than transition metal oxides, but their high cost limits the widespread application of Pt, Pd, and Au catalysts. Ru is widely used in various catalytic oxidation processes due to its low price and stable chemical properties.

[0003] In the patent with the application publication number CN202211489317.7, the inventor prepared a Mn3O4-Fe2O3 composite catalyst using the new precursor K2FeO4, increasing the specific surface area and the number of active sites exposed on the catalyst surface, and being able to efficiently convert toluene in the air into CO2 and H2O; in the patent with the application publication number CN202111352664.0, the inventor prepared a mesoporous metal oxide Ce x M y O z (M is Mn, Co, or Cu, x + y = 100, and z = 100 to 200; when M is Mn, x = 0.05 to 20, while y = 99.95 to 80; when M is Co, x = 0.05 to 20, while y = 99.95 to 80; and when M is Cu, x = 0.05 to 20, while y = 99.95 to 80), which shows good catalytic activity in the combustion reaction of volatile organic compounds and can oxidize more than 99% of the aromatic volatile organic compounds introduced into it into water and carbon dioxide in the range of 180 - 230 °C; in the patent with the application publication number CN202411462241.8, the inventor synthesized a modified catalyst by loading Cu 2+ and Ce 3+ on the surface of a pure silica molecular sieve MCM-41 synthesized under alkaline conditions, and simultaneously synergistically eliminating NO while catalytically oxidizing toluene x, which is superior to the single waste gas treatment method in industrial production and has good application prospects. Therefore, the development of a non-noble metal catalyst with excellent performance and low price is still the focus of current domestic and foreign researchers. Summary of the Invention

[0004] The first object of the present invention is to propose a catalyst for eliminating toluene, a catalyst of a large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide with excellent water and sulfur resistance performance, which shows excellent performance in the catalytic oxidation of toluene.

[0005] The second object of the present invention is to propose a preparation method of the above-mentioned catalyst for eliminating toluene.

[0006] The third object of the present invention is to propose the application of the above-mentioned catalyst for eliminating toluene in the catalytic combustion of toluene.

[0007] The present invention is achieved through the following technical solutions.

[0008] A catalyst for eliminating toluene according to the present invention has a chemical formula of 1% Ru / Pr2Ce2O7-300.

[0009] A catalyst for eliminating toluene according to the present invention is characterized in that the crystal phase structure of the catalyst is disordered defective fluorite.

[0010] A preparation method of a catalyst for eliminating toluene according to the present invention adopts a hydrothermal method and a deposition precipitation method, and includes the following steps.

[0011] (1) Prepare a precursor solution. A large specific surface area Pr2Ce2O7 solid solution support is prepared by a hydrothermal method. First, Pr6O is dissolved in a certain amount of dilute nitric acid solution according to a molar ratio of 1:6, and Ce(NO3)3·6H2O is dissolved in deionized water until a clear solution is obtained. The two are mixed and stirred to obtain a homogeneous and transparent solution, denoted as solution I; glucose with a molar amount of 1:1 of the molar amount of metal ions is dissolved in an appropriate amount of deionized water. After complete dissolution, an acrylic acid solution with a molar amount of 1.5 times the molar amount of metal ions is added, and the mixture is stirred until it is uniformly mixed, denoted as solution II. 11 Dissolve in a certain amount of dilute nitric acid solution, take Ce(NO3)3·6H2O and dissolve it in deionized water until a clear solution is obtained. Mix the two and stir to obtain a homogeneous and transparent solution, denoted as solution I; dissolve glucose with a molar amount of 1:1 of the molar amount of metal ions in an appropriate amount of deionized water. After complete dissolution, add an acrylic acid solution with a molar amount of 1.5 times the molar amount of metal ions and stir until it is uniformly mixed, denoted as solution II.

[0012] (2) Mix solution I and solution II, add NH3·H2O to adjust the pH to 8-12, continuously stir for 2-10 h, put it into a hydrothermal autoclave, keep it warm at 180 °C for 2-10 d, cool it and then filter it until the TDS < 20, and dry it in an oven at 110 °C for 5-24 h.

[0013] (3) Put the sample obtained after drying into a tubular furnace. Under the condition of introducing nitrogen at a flow rate of 50 mL / min, heat it up to 600 °C at a heating rate of 2 - 5 °C / min, calcine for 4 - 6 h, and then cool it to room temperature.

[0014] (4) Transfer the sample obtained in step (3) to a muffle furnace. Under an air atmosphere, heat it up to 400 °C at a heating rate of 2 - 5 °C / min, and calcine for 4 - 10 h to obtain a large specific surface area Pr2Ce2O7 solid solution catalyst support.

[0015] (5) Prepare a large specific surface area 1% Ru / Pr2Ce2O7 - 300 with excellent water and sulfur resistance performance by the deposition - precipitation method. Dissolve a RuCl3 solution with a mass ratio of 0.5% - 5% and Pr2Ce2O7 solid solution in deionized water. After stirring evenly, add NH3·H2O to adjust the pH to 8 - 12, continuously stir for 2 - 10 h, and let it stand for precipitation and aging for 5 - 24 h.

[0016] (6) Filter the above - mentioned solution until the TDS < 20, dry it in an oven at 110 °C for 12 h. Put the sample obtained after drying into a muffle furnace. Under an air atmosphere, heat it up to 300 - 900 °C at a heating rate of 2 - 5 °C / min, and calcine for 4 - 10 h to obtain a large specific surface area 1% Ru / Pr2Ce2O7 - 300 catalyst with excellent water and sulfur resistance performance.

[0017] The application of the catalyst described in the present invention in toluene catalytic combustion.

[0018] The catalyst described in the present invention is tested under normal pressure, with a reaction gas composition of 1000 ppm toluene + air and a gas flow rate of 30 mL / min, and has excellent catalytic activity and stability for toluene combustion.

[0019] For the catalyst described in the present invention, take 50 mg of this catalyst and stir it evenly with 50 mg of quartz sand, then place it in a gas stream with a composition of 1000 ppm toluene + air and a flow rate of 30 mL / min, and evaluate its activity by the programmed - temperature method at a rate of 2 - 10 °C / min up to 500 °C.

[0020] The A2B2O7 composite oxide has excellent thermal stability, contains intrinsic structural oxygen vacancies, is rich in surface active oxygen species, and has adjustable A and B sites, and has attracted much attention in the catalytic field. Selecting metastable metals as A and B site elements is an effective way to improve lattice disorder, so as to obtain a composite oxide toluene elimination catalyst with better redox performance and reaction activity.

[0021] During the catalytic oxidation of toluene, the formation of water is inevitable, but the role of water molecules in toluene oxidation remains controversial. SO2 is a common component in industrial waste gas, which is easily adsorbed onto the active sites to form sulfate and sulfite substances. These substances are not easily decomposed at the reaction temperature, resulting in the blockage of active sites and a significant reduction in catalytic activity. Therefore, the water and sulfur poisoning resistance performance of the catalyst is also an important factor in evaluating the stability of the catalyst.

[0022] Compared with the prior art, the catalyst prepared by the present invention has the following advantages.

[0023] (1) The raw materials used in the present invention for preparing the catalyst are inexpensive, the preparation process is simple and easy to implement, the equipment requirements are low, the solvent is non-toxic and harmless, and there is no secondary pollution to the environment.

[0024] (2) The 1% Ru / Pr2Ce2O7-300 catalyst with excellent water and sulfur resistance prepared by the present invention has a large specific surface area, which is beneficial to the contact efficiency between toluene and the catalyst.

[0025] (3) The large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared by the present invention exhibits excellent activity and stability in the catalytic combustion elimination reaction of toluene. Description of the Drawings

[0026] Figure 1 SEM photograph of the large specific surface area Pr2Ce2O7 solid solution composite oxide catalyst prepared in Example 1, with a magnification of 2 um.

[0027] Figure 2 SEM photograph of the large specific surface area Pr2Ce2O7 solid solution composite oxide catalyst prepared in Example 1, with a magnification of 500 nm.

[0028] Figure 3 SEM photograph of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2, with a magnification of 5 um.

[0029] Figure 4 SEM photograph of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2, with a magnification of 500 nm.

[0030] Figure 5 Pore size test chart of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2.

[0031] Figure 6 X-ray diffraction (XRD) pattern of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2.

[0032] Figure 7 Toluene combustion performance test chart of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2.

[0033] Figure 8 Water and sulfur resistance performance test chart of the large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2. Detailed implementation manners

[0034] To illustrate the content of the present invention more clearly, the following examples are listed, but they have no limitation on the scope of the present invention. Example 1

[0035] A large specific surface area Pr2Ce2O7 solid solution oxide support was prepared by a hydrothermal method.

[0036] A precursor solution was prepared. 0.8512 g of Pr6O 11 was dissolved in 10 mL of 30% dilute nitric acid until a clear solution was obtained. 2.1711 g of Ce(NO3)3·6H2O was dissolved in 10 mL of deionized water. The two were mixed and stirred to obtain a homogeneous and transparent solution, denoted as Solution I. 1.9817 g of glucose was dissolved in 10 mL of deionized water. After complete dissolution, 1.0809 g of acrylic acid solution was added and stirred until evenly mixed, denoted as Solution II. Solution I and II were mixed, and a certain amount of NH3·H2O was added to adjust the pH to 10. Stir continuously for 5 h, put it into a hydrothermal autoclave, keep it at 180 °C for 5 d, cool and then filter until the TDS < 20, and dry it in an oven at 110 °C for 12 h. The sample obtained after drying was placed in a tubular furnace. Under the condition of introducing nitrogen, with a heating rate of 2 °C / min and a flow rate of 50 mL / min, it was kept at 600 °C for 6 h and then cooled to room temperature. The obtained sample was transferred to a muffle furnace and calcined at 400 °C for 4 h at a heating rate of 2 °C / min in an air atmosphere to obtain a large specific surface area Pr2Ce2O7 solid solution catalyst support. Example 2

[0037] A large specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide with excellent water and sulfur resistance was prepared by a deposition-precipitation method.

[0038] Take 1.98 g of Pr2Ce2O7 solid solution catalyst support in a crucible, add 10 mL of deionized water to disperse evenly, add 4 mL of 0.05 g / mL RuCl3 solution, stir evenly, then add a certain amount of NH3·H2O to adjust the pH to 10, continuously stir for 5 h, and let it stand for precipitation and aging for 5 h; filter the above solution until TDS < 20, dry it in an oven at 110 °C for 12 h, put the dried sample into a muffle furnace, and calcine it in an air atmosphere at a heating rate of 2 °C / min to 300 °C for 4 h to obtain a large specific surface area 1% Ru / Pr2Ce2O7-300 catalyst with excellent water and sulfur resistance performance. Example 3

[0039] Prepare a large specific surface area 1% Ru / Pr2Ce2O7-500 solid solution composite oxide by the deposition-precipitation method.

[0040] Take 1.98 g of Pr2Ce2O7 solid solution catalyst support in a crucible, add 10 mL of deionized water to disperse evenly, add 4 mL of 0.05 g / mL RuCl3 solution, stir evenly, then add a certain amount of NH3·H2O to adjust the pH to 10, continuously stir for 5 h, and let it stand for precipitation and aging for 5 h; filter the above solution until TDS < 20, dry it in an oven at 110 °C for 12 h, put the dried sample into a muffle furnace, and calcine it in an air atmosphere at a heating rate of 2 °C / min to 500 °C for 4 h to obtain a large specific surface area 1% Ru / Pr2Ce2O7-500 catalyst. Example 4

[0041] Prepare a large specific surface area 1% Ru / Pr2Ce2O7-700 solid solution composite oxide by the deposition-precipitation method.

[0042] Take 1.98 g of Pr2Ce2O7 solid solution catalyst support in a crucible, add 10 mL of deionized water to disperse evenly, add 4 mL of 0.05 g / mL RuCl3 solution, stir evenly, then add a certain amount of NH3·H2O to adjust the pH to 10, continuously stir for 5 h, and let it stand for precipitation and aging for 5 h; filter the above solution until TDS < 20, dry it in an oven at 110 °C for 12 h, put the dried sample into a muffle furnace, and calcine it in an air atmosphere at a heating rate of 2 °C / min to 700 °C for 4 h to obtain a large specific surface area 1% Ru / Pr2Ce2O7-700 catalyst. Example 5

[0043] Prepare a large specific surface area 1% Ru / Pr2Ce2O7-900 solid solution composite oxide by the deposition-precipitation method.

[0044] Take 1.98 g of Pr2Ce2O7 solid solution catalyst support in a crucible, add 10 mL of deionized water and disperse evenly. Add 4 mL of 0.05 g / mL RuCl3 solution, stir evenly, then add a certain amount of NH3·H2O to adjust the pH to 10, continuously stir for 5 h, and let it stand for precipitation and aging for 5 h. Filter the above solution until the TDS < 20, dry it in an oven at 110 °C for 12 h. Put the dried sample into a muffle furnace and calcine it at a heating rate of 2 °C / min to 900 °C in an air atmosphere for 4 h to obtain a high specific surface area 1% Ru / Pr2Ce2O7-900 catalyst.

[0045] Figure 1 and Figure 2 Figure 8 is the scanning electron microscope image of the high specific surface area Pr2Ce2O7 solid solution composite oxide catalyst in Example 1. It can be seen that the high specific surface area Pr2Ce2O7 catalyst prepared by the hydrothermal method forms a relatively regular spherical structure.

[0046] Figure 3 and Figure 4 Figure 14 is the scanning electron microscope image of the high specific surface area 1% Ru / Pr2Ce2O7-300 solid solution composite oxide catalyst with excellent water and sulfur resistance in Example 2. It can be seen that the high specific surface area 1% Ru / Pr2Ce2O7-300 catalyst prepared by the deposition precipitation method does not damage the morphology of the support and still maintains a relatively regular spherical structure.

[0047] Figure 5 Figure 18 is the pore size test chart of the high specific surface area 1% Ru / Pr2Ce2O7-300 composite oxide catalyst with excellent water and sulfur resistance in Example 2. It can be seen that the catalyst has a hierarchical pore structure with both micropores and mesopores.

[0048] Figure 6 Figure 22 is the X-ray diffraction (XRD) crystal phase structure analysis spectrum of the high specific surface area 1% Ru / Pr2Ce2O7-300 composite oxide catalyst with excellent water and sulfur resistance prepared in Example 2. It can be seen that the 1% Ru / Pr2Ce2O7-300 composite oxide catalyst forms a disordered defective fluorite crystal phase structure.

[0049] Comparative Example 1.

[0050] Prepare Pr2Ce2O7 solid solution oxide support by glycine combustion method.

[0051] Take 0.8512 g of Pr6O 11Dissolve it in 10 mL of 30% dilute nitric acid to a clear solution. Dissolve 2.1711 g of Ce(NO3)3·6H2O nitrate in 10 mL of deionized water. Mix the two and stir to obtain a homogeneous and transparent solution. Add 0.7507 g of glycine and stir for 1 h. Evaporate it in a water bath at 90 °C until it becomes gel-like. Ignite it in a muffle furnace at 300 °C and then heat it to 400 °C at a heating rate of 2 °C / min and calcine for 4 h to obtain the Pr2Ce2O7 solid solution oxide support.

[0052] Comparative Example 2.

[0053] Prepare the Pr2Ce2O7 solid solution oxide support by the sol-gel method.

[0054] Dissolve 0.8512 g of Pr6O 11 Dissolve it in 10 mL of 30% dilute nitric acid to a clear solution. Dissolve 2.1711 g of Ce(NO3)3·6H2O nitrate in 10 mL of deionized water. Mix the two and stir to obtain a homogeneous and transparent solution. Add 2.5217 g of citric acid and stir for 1 h. Evaporate it in a water bath at 90 °C until it becomes gel-like. Age it in an oven at 110 °C for 12 h. Ignite it in a muffle furnace at 300 °C and then heat it to 400 °C at a heating rate of 2 °C / min and calcine for 4 h to obtain the Pr2Ce2O7 solid solution oxide support.

[0055] Comparative Example 3.

[0056] Prepare the Pr2Ce2O7 solid solution oxide support by the co-precipitation method.

[0057] Dissolve 0.8512 g of Pr6O 11 Dissolve it in 10 mL of 30% dilute nitric acid to a clear solution. Dissolve 2.1711 g of Ce(NO3)3·6H2O nitrate in 10 mL of deionized water. Mix the two and stir to obtain a homogeneous and transparent solution. Add a certain amount of NH3·H2O to adjust the pH to 10. Continuously stir for 2 h and let it stand and age for 5 h. Filter the above solution until the TDS < 20, and dry it in an oven at 110 °C for 12 h; put the dried sample into a muffle furnace and calcine it in an air atmosphere at a heating rate of 2 °C / min to 400 °C for 4 h to obtain the Pr2Ce2O7 solid solution catalyst support.

[0058] Detection of application effect: Test the catalytic effects of the catalysts prepared in Examples 1-5 and Comparative Examples 1-3.

[0059] Testing method: The catalytic combustion activities of the catalyst samples obtained in Examples 1-5 and Comparative Examples 1-3 for toluene were evaluated. The specific implementation method is as follows: The toluene combustion performance of the catalyst was evaluated on a gas chromatograph SP-7890 produced by Shandong Lunan Ruihong Chemical Instrument Co., Ltd. The catalytic combustion activity of toluene particles of the catalyst was measured by the temperature-programmed oxidation method. In order to obtain the intrinsic activity of the catalyst, the experiment was carried out under close contact conditions. 50 mg of the catalyst was stirred with 50 mg of inert quartz sand for 2 min. In an atmosphere of 1000 ppm toluene + air with a flow rate of 30 mL / min, the temperature was programmed to rise to 500 °C at a rate of 5 °C / min.

[0060] Testing results: 。

[0061] Based on the above activity evaluation method, the toluene catalytic activities of the samples obtained in Examples 1-5 and Comparative Examples 1-3 were tested. It can be seen that Example 2 showed the best toluene removal ability at different test temperatures, and its toluene combustion activity could reach 90% toluene conversion at 243 °C. In addition, Example 2 also had very excellent water and sulfur resistance. The presence of water would promote the generation of more active oxygen species on the catalyst surface that were beneficial to the toluene combustion reaction, resulting in an increase rather than a decrease in the toluene conversion. The presence of sulfur would not cover the active sites on the catalyst surface, thus having no impact on the deep catalytic oxidation of toluene.

Claims

1. A catalyst for eliminating toluene, characterized by the chemical formula It is 1% Ru / Pr2Ce2O7-300.

2. A preparation method of a catalyst for eliminating toluene, adopting a hydrothermal method and a deposition precipitation method, characterized in that It includes the following steps: (1) A large specific surface area Pr2Ce2O7 solid solution support was prepared by the hydrothermal method: First, Pr6O was taken in a molar ratio of 1:6 and dissolved in a certain amount of dilute nitric acid solution, and Ce(NO3)3·6H2O was taken and dissolved in deionized water until a clear solution was obtained. The two were mixed and stirred to obtain a homogeneous and transparent solution, denoted as Solution I; glucose with a molar amount of 1:1 of the metal ion molar amount was dissolved in an appropriate amount of deionized water. After complete dissolution, an acrylic acid solution with a molar amount of 1.5 times the metal ion molar amount was added, and stirred until evenly mixed, denoted as Solution II; 11 was dissolved in a certain amount of dilute nitric acid solution, and Ce(NO3)3·6H2O was dissolved in deionized water until a clear solution was obtained. The two were mixed and stirred to obtain a homogeneous and transparent solution, denoted as Solution I; glucose with a molar amount of 1:1 of the metal ion molar amount was dissolved in an appropriate amount of deionized water. After complete dissolution, an acrylic acid solution with a molar amount of 1.5 times the metal ion molar amount was added, and stirred until evenly mixed, denoted as Solution II; (2) Mix Solution I and Solution II, add NH3·H2O to adjust the pH to 8 - 12, continuously stir for 2 - 10 h, put it into a hydrothermal autoclave, keep it warm at 180 °C for 2 - 10 d, cool it and then filter it until the TDS < 20, and dry it in an oven at 110 °C for 5 - 24 h; (3) Put the sample obtained after drying into a tube furnace, under the condition of introducing nitrogen at a flow rate of 50 mL / min, with a heating rate of 2 - 5 °C / min, heat it up to 600 °C, calcine it for 4 - 6 h and then cool it to room temperature; (4) Transfer the sample obtained in step (3) to a muffle furnace, under an air atmosphere, with a heating rate of 2 - 5 °C / min, heat it up to 400 °C, and calcine it for 4 - 10 h to obtain a large specific surface area Pr2Ce2O7 solid solution catalyst support; (5) Prepare a large specific surface area 1%Ru / Pr2Ce2O7-300 with excellent water and sulfur resistance through the deposition-precipitation method. Dissolve the RuCl3 solution with a mass ratio of 0.5% - 5% and the Pr2Ce2O7 solid solution in deionized water, stir evenly, add NH3·H2O to adjust the pH to 8 - 12, continuously stir for 2 - 10 h, and let it stand for precipitation and aging for 5 - 24 h; (6) Filter the above solution until the TDS < 20, dry it in an oven at 110 °C for 12 h, put the sample obtained after drying into a muffle furnace, under an air atmosphere, with a heating rate of 2 - 5 °C / min, heat it up to 300 - 900 °C, and calcine it for 4 - 10 h to obtain a large specific surface area 1% Ru / Pr2Ce2O7-300 catalyst with excellent water and sulfur resistance.

3. The application of the catalyst described in Claim 1 in the catalytic combustion of toluene.

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