Pr6O11-SnO2-ZrO2 ternary composite oxide as well as preparation method and application thereof

Abstract

The invention provides a Pr6O11-SnO2-ZrO2 ternary composite oxide as well as a preparation method and application thereof, and relates to the technical field of catalyst carriers. The Pr6O11-SnO2-ZrO2 ternary composite oxide disclosed by the invention is prepared from the following raw materials in percentage by mass: 60%-80% of ZrO2, 10%-20% of SnO2 and 10%-20% of Pr6O11. According to the invention, by designing the composition ratio of the Pr6O11-SnO2-ZrO2 ternary composite oxide material, the structural stability of the Pr6O11-SnO2-ZrO2 ternary composite oxide is enhanced, and the Pr6O11-SnO2-ZrO2 ternary composite oxide plays a synergistic effect with the active component and the auxiliary agent, so that the low-temperature activity and high-temperature-resistant hydrothermal stability of the catalyst are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of catalyst carriers, in particular to a Pr6O 11 -SnO2-ZrO2 ternary composite oxide and its preparation method and application. Background Art

[0002] Volatile organic compounds (VOCs) are the main pollutants in industrial waste gas, mainly including hydrocarbons, olefins, benzene and its derivatives, ethyl acetate, acetone and other volatile organic compounds. VOCs are one of the sources of air pollution and are commonly found in the production processes of industries such as petroleum, chemical industry, refining, tank farm emissions, coatings, painting, fine chemicals, textile printing and dyeing.

[0003] As environmental regulations become increasingly stringent, the implementation of national and local standards in various industries requires that industrial waste gas VOCs must be treated by recycling, purification and other methods before they can be discharged; among them, alkane volatile organic compounds are the most difficult to treat type of substances among VOCs, such as small molecule alkanes such as ethane and propane. At present, the main treatment methods for alkane volatile organic compounds are high-temperature incineration and catalytic oxidation. With the requirements of green production, the requirements for industrial energy conservation, consumption reduction and emission reduction are getting higher and higher, and the requirements for the entire waste gas emission control are also getting higher and higher. Even some areas require ultra-low emissions. The catalytic oxidation method has the advantages of relatively low purification temperature, low energy consumption, and not easy to produce secondary pollution. It is considered to be the most effective method for eliminating alkane volatile organic compounds. It is one of the most widely used process technologies in industry. This process technology takes the catalyst as the core, and combines adsorption concentration, desorption and other processes to achieve high integration, intelligence, and ultra-low emission requirements. However, the low-temperature high conversion efficiency of the catalyst and its high-temperature hydrothermal performance have always been insufficient. When there is a large amount of water in the service environment, the catalyst performance is inhibited and cannot be used stably for a long time, thus failing to meet the long-term catalytic performance of 99% or more and its performance stability requirements.

[0004] The invention patent with the publication number CN 116726915 A discloses the preparation of a VOCs catalytic combustion catalyst with low precious metal content and high thermal stability, comprising: 1) dissolving a structure directing agent in anhydrous ethanol, stirring vigorously to fully dissolve it to obtain a mixed solution A; 2) adding HNO3 and aluminum isopropoxide to the mixed solution A in sequence, stirring vigorously to form a uniform transparent solution B; 3) adding a non-precious metal salt to the transparent solution B, stirring to form a uniform mixed solution C; 4) adding a precious metal salt to the mixed solution C, stirring evenly to obtain a mixed solution D; and aging the mixed solution D in a constant temperature and humidity drying oven to obtain a paste; 5) drying the paste, calcining it in an air atmosphere in a muffle furnace, and cooling it naturally to room temperature to obtain a catalyst. However, the catalytic performance of the catalyst is poor under low temperature conditions.

[0005] The invention patent with publication number CN 107398295 A discloses a catalyst and preparation method for catalytic purification of volatile organic compounds. The catalyst is prepared by mixing a supported base metal catalyst and a supported precious metal catalyst and calcining at 350-1000°C, wherein the supported base metal catalyst is composed of a carrier and a base metal supported on the carrier, and the supported precious metal catalyst is composed of a carrier and a precious metal supported on the carrier and an additive. The mass ratio of the supported base metal catalyst to the supported precious metal catalyst is 1:99 to 99:1. The catalyst adopts an oxide carrier including Al2O3, SiO2, TiO2, ZrO2 and their composite oxides. However, the catalyst has a good low-temperature catalytic effect on chlorine-containing volatile organic matter dichloroethane, but the catalytic effect on propane is unknown, and the catalyst does not catalyze VOCs in a hydrothermal environment.

[0006] Therefore, how to overcome the shortcomings of existing VOCs catalysts, especially alkane volatile organic compound catalysts, and develop a VOCs catalyst with good low-temperature activity and hydrothermal and high-temperature stability is one of the technical problems that need to be solved urgently. Summary of the invention

[0007] In order to solve the above problems, the present invention provides a Pr6O 11 -SnO2-ZrO2 ternary composite oxide and its preparation method and application.

[0008] The present invention designs Pr6O 11 -SnO2-ZrO2 ternary composite oxide material composition ratio, enhanced Pr6O 11 -The structural stability of the SnO2-ZrO2 ternary composite oxide plays a synergistic role with the active components and additives to enhance the low-temperature activity and hydrothermal and high-temperature stability of the catalyst.

[0009] The Pr6O 11 -SnO2-ZrO2 ternary composite oxide includes the following raw materials in mass percentage:

[0010] ZrO260%~80%, SnO210%~20%, Pr6O 11 10%~20%.

[0011] The present invention also provides the Pr6O 11 -The preparation method of SnO2-ZrO2 ternary composite oxide specifically comprises the following steps:

[0012] S1. Dissolving and mixing soluble salts of zirconium, tin and praseodymium to obtain a soluble salt solution;

[0013] S2, adding an alkali solution with a pH of 8.5 to 11 into the soluble salt solution under stirring until precipitation occurs;

[0014] S3. After precipitation occurs, PVP is immediately added to the solution and stirred continuously until precipitation is complete to obtain a reaction solution;

[0015] S4, aging and filtering the reaction solution to obtain a precipitate, and drying and continuously calcining the precipitate to obtain Pr6O 11 -SnO2-ZrO2 ternary composite oxide.

[0016] Furthermore, the soluble salt is nitrate or stannous chloride.

[0017] Furthermore, the alkali solution is aqueous ammonia or ammonium carbonate solution.

[0018] Furthermore, the stirring rate is 100 to 300 r / min.

[0019] Furthermore, the amount of PVP added is 0.5wt.% to 5wt.% of the ternary composite oxide.

[0020] Furthermore, the aging temperature is room temperature, and the aging time is 10 to 24 hours.

[0021] Furthermore, the drying temperature is 60°C to 90°C, and the drying time is 5 to 10 hours. Preferably, the drying temperature is 80°C.

[0022] Furthermore, the continuous calcination is carried out in two stages. The calcination temperature in the first stage is 300°C to 450°C, and the calcination time is 3 to 5 hours; the calcination temperature in the second stage is 650°C to 900°C, and the calcination time is 3 to 7 hours.

[0023] The Pr6O 11 -SnO2-ZrO2 ternary composite oxide can be used as a carrier to prepare VOCs low-temperature purification catalyst (PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst).

[0024] Furthermore, the PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst contains active component (PGM) 0.01wt.%~5.0wt.%, auxiliary agent (M) 1.0wt.%~10wt.%, and the balance is Pr6O 11 -SnO2-ZrO2 ternary composite oxide support.

[0025] Further, the active component is platinum (Pt) and / or palladium (Pd). Preferably, the active components are Pt and Pd. More preferably, the active components Pt and Pd are composed of a molar ratio of (1-10):1.

[0026] Furthermore, the auxiliary agent is one or two of tungsten (W), molybdenum (Mo) and niobium (Nb).

[0027] Furthermore, the preparation method of the catalyst is as follows:

[0028] The soluble salt solution of the auxiliary element is impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried, calcined, and then the soluble salt of the active component element was impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried and calcined to obtain PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst;

[0029] Alternatively, the soluble salt solution of the auxiliary element and the soluble salt solution of the active component element are impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried and calcined to obtain PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst.

[0030] Furthermore, the drying temperature is 60°C to 90°C, the drying time is 5 to 10 hours, the roasting temperature is 350°C to 550°C, and the roasting time is 5 to 10 hours. Preferably, the drying temperature is 80°C.

[0031] The PGM-M / Pr6O 11 -The application method of SnO2-ZrO2 catalyst is as follows:

[0032] PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst, water and adhesive are uniformly mixed in a mass ratio of (30-55):100:(2-10), ball-milled to a catalyst particle size of 3-10 μm to prepare a catalyst slurry, and then coated on the pores of a base honeycomb substrate to obtain a catalyst coating of a specific thickness, hot-air dried at 60°C-90°C for 2-5 hours, and then calcined at 400°C-650°C for 5 hours before being used for low-temperature catalytic purification of VOCs.

[0033] The present invention does not strictly limit the number of coating times, and the coating can be performed once or multiple times until the thickness of the catalyst coating reaches the design requirement.

[0034] Furthermore, the substrate is a ceramic honeycomb frame or a metal honeycomb frame.

[0035] Furthermore, the PGM-M / Pr6O 11 -SnO2-ZrO2 catalyst accounts for 5wt.% to 40wt.% of the substrate.

[0036] Further, the VOCs are one or more of alkanes, benzene and its derivatives, aromatic hydrocarbons, ethers, alcohols, and esters. Preferably, the VOCs are one or more of propane, ethane, styrene, ethyl acetate, ethanol, acrylonitrile, and acrylic acid.

[0037] Compared with the prior art, the beneficial technical effects of the present invention are:

[0038] Pr6O of the present invention 11 -SnO2-ZrO2 ternary composite oxide has good structural stability. As a carrier, it can play a good synergistic role with additives and active components, inhibit the adsorption and accumulation of water or hydroxyl groups on the active centers of the catalyst and the carrier materials, and improve the low-temperature activity and hydrothermal high-temperature stability of the catalyst.

[0039] PGM-M / Pr6O of the present invention 11 -SnO2-ZrO2 catalyst has good low-temperature ignition performance for VOCs, is suitable for low-temperature catalytic purification of VOCs in industrial waste gas, has excellent hydrothermal and high-temperature resistance, and good stability. It can be used for catalytic combustion purification of various toxic and harmful VOCs such as alkanes in the tail gas of petroleum refining and chemical plants (industrial acrylic acid plants, acrylonitrile plants, maleic anhydride plants, PDH plants, phthalic anhydride plants and MMA plants, etc.), and the preparation process is simple, which is suitable for large-scale production. DETAILED DESCRIPTION

[0040] The technical solution provided by the present invention is further described below in conjunction with embodiments.

[0041] Example 1

[0042] A Pr6O 11 -SnO2-ZrO2 ternary composite oxide, composed of the following raw materials in percentage by mass: ZrO2 70%, SnO2 15% and Pr6O 11 15%.

[0043] The Pr6O 11 -The preparation method of SnO2-ZrO2 ternary composite oxide is as follows:

[0044] S1. Mix zirconium nitrate, stannous chloride and praseodymium nitrate according to the designed ratio to obtain a soluble salt solution;

[0045] S2, using ammonium carbonate, prepare an alkali solution with a pH of 9.0, and add the alkali solution dropwise to the soluble salt solution at a stirring rate of 200 r / min until precipitation occurs, which takes 30 min in total;

[0046] S3. After precipitation occurs, immediately add 1wt.% PVP to the solution, control the uniformity of the grain size, and stir continuously until precipitation is complete;

[0047] S4, the reaction solution was aged at room temperature for 12 hours, filtered to obtain a precipitate, the precipitate was dried at 80°C for 6 hours, then calcined at 400°C for 5 hours, then calcined at 800°C for 4 hours, and cooled to obtain the Pr6O 11 -SnO2-ZrO2 ternary composite oxide.

[0048] A Pt4Pd-Nb / Pr6O 11 -SnO2-ZrO2 catalyst, composed of the following raw materials in percentage by weight: 1.0% active component, 5% Nb, and the balance of the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier; the active component is composed of Pt and Pd in ​​a molar ratio of 4:1.

[0049] The Pt4Pd-Nb / Pr6O 11 -The preparation method of SnO2-ZrO2 catalyst is as follows:

[0050] Platinum nitrate, palladium nitrate and niobium nitrate are prepared into a solution and then impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried at 80°C for 5h, and then calcined at 450°C for 5h to obtain the Pt4Pd-Nb / Pr6O 11 -SnO2-ZrO2 catalyst.

[0051] The Pt4Pd-Nb / Pr6O 11 -The application method of SnO2-ZrO2 catalyst is as follows:

[0052] The Pt4Pd-Nb / Pr6O 11 -SnO2-ZrO2 catalyst is uniformly mixed with water and adhesive in a mass ratio of 40:100:4, and ball-milled to a catalyst particle size of 3 to 10 μm to obtain a catalyst slurry; the catalyst slurry is then coated on a ceramic honeycomb substrate with 400 pores per square inch, hot-air dried at 80°C for 3 hours, and then calcined at 450°C for 5 hours;

[0053] The Pt4Pd-Nb / Pr6O 11-SnO2-ZrO2 catalyst accounts for 20wt.% of the substrate.

[0054] Example 2

[0055] A Pr6O 11 -SnO2-ZrO2 ternary composite oxide, composed of the following raw materials in percentage by mass: ZrO2 70%, SnO2 20% and Pr6O 11 10%.

[0056] The Pr6O 11 -The preparation method of SnO2-ZrO2 ternary composite oxide is the same as that in Example 1.

[0057] A Pt-W / Pr6O 11 -SnO2-ZrO2 catalyst, composed of the following raw materials in percentage by weight: Pt 1.0%, W 5%, and the balance of Pr6O 11 -SnO2-ZrO2 ternary composite oxide support.

[0058] The Pt-W / Pr6O 11 -The preparation method of SnO2-ZrO2 catalyst is as follows:

[0059] Platinum nitrate and ammonium metatungstate are prepared into a solution and then impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried at 80°C for 5h, and then calcined at 450°C for 5h to obtain the Pt-Nb / Pr6O 11 -SnO2-ZrO2 catalyst.

[0060] The Pt-W / Pr6O 11 -The application method of SnO2-ZrO2 catalyst is as follows:

[0061] The Pt-W / Pr6O 11 -SnO2-ZrO2 catalyst is uniformly mixed with water and adhesive in a mass ratio of 40:100:4, and ball-milled to a catalyst particle size of 3 to 10 μm to obtain a catalyst slurry; the catalyst slurry is then coated on a ceramic honeycomb substrate with 400 pores per square inch, hot-air dried at 80°C for 3 hours, and then calcined at 450°C for 5 hours;

[0062] The Pt-W / Pr6O 11 -SnO2-ZrO2 catalyst accounts for 20wt.% of the substrate.

[0063] Example 3

[0064] A Pr6O 11-SnO2-ZrO2 ternary composite oxide, composed of the following raw materials in percentage by mass: ZrO2 60%, SnO2 20% and Pr6O 11 20%.

[0065] The Pr6O 11 -The preparation method of SnO2-ZrO2 ternary composite oxide is the same as that in Example 1.

[0066] A Pt-Mo / Pr6O 11 -SnO2-ZrO2 catalyst, composed of the following raw materials in percentage by weight: Pt 1.0%, Mo 5%, and the balance of Pr6O 11 -SnO2-ZrO2 ternary composite oxide support.

[0067] The Pt-Mo / Pr6O 11 -The preparation method of SnO2-ZrO2 catalyst is as follows:

[0068] Platinum nitrate and ammonium molybdate are prepared into a solution and then impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried at 80°C for 5h, and then calcined at 450°C for 5h to obtain the Pt-Mo / Pr6O 11 -SnO2-ZrO2 catalyst.

[0069] The Pt-Mo / Pr6O 11 -The application method of SnO2-ZrO2 catalyst is as follows:

[0070] The Pt-Mo / Pr6O 11 -SnO2-ZrO2 catalyst is uniformly mixed with water and adhesive in a mass ratio of 40:100:4, and ball-milled to a catalyst particle size of 3 to 10 μm to obtain a catalyst slurry; the catalyst slurry is then coated on a ceramic honeycomb substrate with 400 pores per square inch, hot-air dried at 80°C for 3 hours, and then calcined at 450°C for 5 hours;

[0071] The Pt-Mo / Pr6O 11 -SnO2-ZrO2 catalyst accounts for 20wt.% of the substrate.

[0072] Example 4

[0073] Same as Example 2, except that the catalyst active component is composed of Pt and Pd in ​​a molar ratio of 4:1, and the catalyst is Pt4Pd-W / Pr6O 11 -SnO2-ZrO2 catalyst.

[0074] Example 5

[0075] Same as Example 3, except that the catalyst is prepared as follows:

[0076] Prepare ammonium molybdate into a solution and soak it in Pr6O 11 -SnO2-ZrO2 ternary composite oxide support, dried at 80 ° C for 5 h, then calcined at 450 ° C for 5 h, and then platinum nitrate was prepared into a solution and impregnated into the Mo-containing Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried at 80°C for 5h, and then calcined at 450°C for 5h to obtain the Pt-Mo / Pr6O 11 -SnO2-ZrO2 catalyst.

[0077] Comparative Example 1

[0078] Catalyst Pt-Pd-La / Al2O3, La / Al2O3 is a commercial catalyst material, the total content of precious metal platinum and palladium (Pt-Pd) is 40g / ft 3 , g / ft 3 is the unit of total precious metal loading, and the molar ratio of Pt:Pd is 4:1.

[0079] Comparative Example 2

[0080] Same as Example 1, except that the catalyst carrier is a SnO2-ZrO2 binary composite oxide.

[0081] The SnO2-ZrO2 binary composite oxide is composed of the following raw materials in percentage by mass: ZrO2 85%, SnO2 15%.

[0082] The preparation method of the SnO2-ZrO2 binary composite oxide is as follows:

[0083] S1. Mix zirconium nitrate and stannous chloride in a designed ratio to obtain a soluble salt solution;

[0084] S2, using ammonium carbonate, prepare an alkali solution with a pH of 9.0, and add the alkali solution dropwise to the soluble salt solution at a stirring rate of 200 r / min until precipitation occurs, which takes 30 min in total;

[0085] S3. After precipitation occurs, immediately add 1wt.% PVP to the solution, control the uniformity of the grain size, and stir continuously until precipitation is complete;

[0086] S4. The reaction solution is aged at room temperature for 12 hours and filtered to obtain a precipitate. The precipitate is dried at 80° C. for 6 hours, then calcined at 400° C. for 5 hours, then calcined at 800° C. for 4 hours, and then cooled to obtain the SnO2-ZrO2 binary composite oxide.

[0087] The catalyst obtained in this comparative example is Pt4Pd-Nb / SnO2-ZrO2.

[0088] Comparative Example 3

[0089] Same as Example 1, except that: the Pr6O 11 -SnO2-ZrO2 ternary composite oxide preparation process, the step S4 is only calcined once, the calcination temperature is 800 ° C, the calcination time is 4h. The catalyst Pt4Pd-Nb / Pr6O 11 -SnO2-ZrO2(800).

[0090] Comparative Example 4

[0091] Same as Example 1, except that the aging time is 3 hours.

[0092] Example 6

[0093] The same as Example 1, except that: the continuous calcination is carried out in two stages, the calcination temperature of the first stage is 300° C., and the calcination time is 5 h; the calcination temperature of the second stage is 650° C., and the calcination time is 7 h.

[0094] Example 7

[0095] The same as Example 1, except that: the continuous roasting is carried out in two stages, the roasting temperature of the first stage is 450° C., and the roasting time is 3 hours; the roasting temperature of the second stage is 900° C., and the roasting time is 3 hours.

[0096] Example 8

[0097] The same as Example 1, except that the active component is composed of Pt and Pd in ​​a molar ratio of 1:1.

[0098] Example 9

[0099] The same as Example 1, except that the active component is composed of Pt and Pd in ​​a molar ratio of 10:1.

[0100] Test Example 1 VOCs catalytic performance determination

[0101] The catalysts of Examples 1-9 and Comparative Examples 1-4 were used to carry out propane catalytic performance and high temperature hydrothermal stability tests, and the exhaust gas concentration before and after passing through the catalyst was detected using a chromatograph. The test conditions are shown in Table 1 and Table 2, and the results are shown in Table 3 and Table 4.

[0102] Table 1 Exhaust gas concentration and test boundary

[0103] Test subjects <![CDATA[Propane C3H8]]> Test atmosphere <![CDATA[O2: 2%; Balance gas: N2; C3H8: 2000 ppm; H2O: 20 vol%]]> <![CDATA[Test airspeed / h -1 > 15000 Test temperature / ℃ 250，275，300，350，400，450 Test Status Steady State

[0104] Table 2 High temperature water thermal stability test conditions

[0105] Test subjects <![CDATA[Propane (C3H8)]]> Test atmosphere <![CDATA[O2: 2%; Balance gas: N2; C3H8: 2000 ppm; H2O: 20 vol%]]> <![CDATA[Test airspeed / h -1 > 15000 High temperature / ℃ 550 Hydrothermal treatment time / h 200

[0106] The test results are shown in Tables 3 and 4.

[0107] Table 3 Propane catalytic activity (%) performance test statistics of the embodiments and comparative examples

[0108]

[0109] Table 4 Propane catalytic performance stability (%) test data statistics of the embodiments and comparative examples

[0110]

[0111]

[0112] It can be seen from Table 3 and Table 4 that the freshness performance and high temperature hydrothermal stability performance of the catalysts of Examples 1-9 are significantly better than those of Comparative Examples 1-4, especially at a temperature below 300°C, the propane catalytic conversion performance is significantly improved, and the propane conversion efficiency is at least 95%; when the temperature is 250°C, the propane catalytic conversion efficiency can reach more than 50%, showing good low temperature ignition performance. The catalyst of the present invention still has good catalytic performance under long-term application under high temperature hydrothermal conditions, indicating that the catalyst of the present invention has good high temperature hydrothermal stability. It can be seen that Pr6O 11 -SnO2-ZrO2 ternary composite oxide can improve the catalytic performance and high temperature hydrothermal stability of the catalyst.

[0113] At the same time, by comparing Example 2 and Example 3 with other examples, it is shown that the performance of the bimetallic Pt-Pd catalyst formed by adding Pt and Pd is not much different from that of the single Pt noble metal catalyst in terms of fresh state and high temperature hydrothermal stability. This is mainly because the activity performance of the catalyst disclosed in the present invention not only involves the noble metal active component, but also involves the synergistic improvement of the performance by the interaction between the noble metal active component and the additive; by comparing Example 3 with Example 5, it is shown that by adjusting the impregnation order of the additive, the active component in Pr6O 11-The electronic state in the SnO2-ZrO2 ternary composite oxidation carrier improves the low-temperature performance of the catalyst for propane. Combined with the description in Examples 1, 2, and 3, different additives are matched with corresponding impregnation sequences to produce different electronic states of the active components, which promotes different degrees of enhancement of the adsorption of propane and the ability to crack HC under low-temperature conditions, and has a significant effect on the low-temperature catalytic conversion of propane.

[0114] Through Examples 1, 6-7 and Comparative Example 3, it is shown that the two-step calcination process of the disclosed patent is more beneficial to the catalytic performance and stability of the catalyst. Through Example 1 and Comparative Example 4, it is shown that Pr6O 11 -The aging time of SnO2-ZrO2 during the preparation process directly affects the performance of the catalyst. This is mainly because the aging time directly affects the degree of crystallization, grain size and uniformity of the ternary composite oxide material.

[0115] Through Examples 1-9 and Comparative Example 2, the invention discloses a ternary Pr6O 11 The catalyst prepared by SnO2-ZrO2 composite oxide has obvious advantages over binary catalyst, which is mainly because the catalyst has strong adsorption and dissociation ability for propane, thanks to the strong adsorption of propane and the strong adsorption of HC bond with Pr6O 11 -Interaction force between SnO2-ZrO2 and active components.

[0116] Through the propane catalytic conversion efficiency test in a long-term high-temperature hydrothermal environment, the catalyst of the present invention exhibits excellent water resistance and stability, with a water content of up to 20 vol% and a stability time of 200h. On the one hand, under the synergistic effect of the auxiliary agent and the noble metal active component, the interaction between the auxiliary agent and the noble metal active component is strengthened, and the MO-Pt / PdOx active site is partially formed to improve the low-temperature performance. In addition, by designing a zirconium-based ternary composite carrier support material with high temperature resistance and water resistance, the dispersion of the active component is improved, the adsorption of the active site to the hydroxyl group is suppressed, and the catalyst stability is improved, and finally the beneficial effect of improving the low-temperature catalytic propane activity and its high-temperature hydrothermal stability is achieved, laying the foundation for the widespread application of the catalyst.

[0117] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A Pr6O 11 -SnO2-ZrO2 ternary composite oxide, characterized in that: The following raw materials are included in mass percentage: ZrO260%~80%, SnO210%~20%, Pr6O 11 10% to 20%.

2. Pr6O according to claim 1 11 -A method for preparing a SnO2-ZrO2 ternary composite oxide, characterized in that: The following steps are involved: S1. Dissolving and mixing soluble salts of zirconium, tin and praseodymium to obtain a soluble salt solution; S2, adding an alkali solution with a pH of 8.5 to 11 into the soluble salt solution under stirring until precipitation occurs; S3. After precipitation occurs, PVP is immediately added to the solution and stirred continuously until precipitation is complete to obtain a reaction solution; S4, aging and filtering the reaction solution to obtain a precipitate, and drying and continuously calcining the precipitate to obtain Pr6O 11 -SnO2-ZrO2 ternary composite oxide.

3. The preparation method according to claim 2, characterized in that: The continuous calcination is carried out in two stages. The calcination temperature of the first stage is 300°C to 450°C, and the calcination time is 3 to 5 hours. The calcination temperature of the second stage is 650°C to 900°C, and the calcination time is 3 to 7 hours.

4. Pr6O according to claim 1 11 -SnO2-ZrO2 ternary composite oxide is used as a carrier to prepare VOCs low-temperature purification catalyst.

5. The use according to claim 4, characterized in that: The VOCs low-temperature purification catalyst comprises the following raw materials: The active component is 0.01wt.%~5.0wt.%, the auxiliary agent is 1.0wt.%~10wt.%, and the balance is the Pr6O 11 -SnO2-ZrO2 ternary composite oxide support.

6. The use according to claim 5, characterized in that: The active component is platinum and / or palladium.

7. The use according to claim 5, characterized in that: The auxiliary agent is one or two of tungsten, molybdenum and niobium.

8. The use according to claim 4, characterized in that: The preparation method of the VOCs low-temperature purification catalyst is as follows: The soluble salt solution of the auxiliary element is impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried, calcined, and then the soluble salt of the active component element was impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried and calcined to obtain a VOCs low-temperature purification catalyst; Or, the soluble salt solution of the auxiliary element and the soluble salt solution of the active component element are impregnated into the Pr6O 11 -SnO2-ZrO2 ternary composite oxide carrier, dried and calcined to obtain a VOCs low-temperature purification catalyst.

9. A VOCs low-temperature purification catalyst, characterized in that: Prepared by the method of claim 8.

10. A method for applying the VOCs low-temperature purification catalyst according to claim 9, characterized in that: Here are the steps: The VOCs low-temperature purification catalyst, water and an adhesive are uniformly mixed to form a catalyst slurry, and then the catalyst slurry is coated on a substrate to obtain a catalyst coating of a specific thickness, which is then dried and calcined for low-temperature catalytic purification of VOCs.

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