A catalyst, its preparation and use

Abstract

The application provides a catalyst and a preparation method and application thereof, and the preparation method comprises the following steps: (1) mixing a solution containing a strong electronegative group and a catalyst carrier raw material, drying, and then calcining to obtain a strong electronegative group modified catalyst carrier; (2) mixing the strong electronegative group modified catalyst carrier and a precursor solution of an active component, drying, and then calcining to obtain the catalyst; wherein the strong electronegative group comprises at least one of SO4 2‑ , WO4 2‑ , VO3 ‑ , MoO4 2‑ , PO4 3‑ , trifluoromethyl and Nb2O5; and the median particle size of the catalyst carrier raw material is 20-150 nm. Under the joint action of the strong electronegative group, the active component and the catalyst carrier raw material, the activity and sulfur resistance of the catalyst at low temperature and high space velocity are greatly improved.

Description

Technical Field

[0001] This invention belongs to the field of catalysis technology, and relates to a catalyst, its preparation method and application, particularly to a sulfur-resistant low-temperature propane combustion catalyst adapted to high space velocities, its preparation method and application. Background Technology

[0002] In recent years, my country's automobile industry has developed rapidly, resulting in significant pollution emissions. Pollutants released from fuel combustion mainly include unburned hydrocarbons (HCs) and nitrogen oxides (NOx). x Hydrocarbons, along with particulate matter, pose significant hazards to the environment and human health. Hydrocarbons in exhaust gases cause a substantial increase in atmospheric volatile organic compound (VOC) levels. These compounds not only lead to serious health problems but also promote photochemical smog formation. To mitigate the harm caused by hydrocarbon releases, efficient treatment strategies are urgently needed. However, compared to the catalytic oxidation of unsaturated hydrocarbons, alkanes released from vehicle exhaust (especially short-chain alkanes such as methane and propane) have stable molecular structures and strong CH bonds, making their catalytic oxidation a considerable challenge. In actual operation, due to the variable operating conditions of vehicles, catalysts are required to adapt to a wide space velocity range and possess certain sulfur resistance properties, maintaining catalytic activity even in sulfur-containing atmospheres.

[0003] CN104684643A discloses a method for preparing a propane oxidation catalyst, the method comprising pre-calcining a catalyst precursor in an oxygen-containing gas in a pre-calcination zone, then supplying an oxygen-free gas to a purification zone until the gas leaving the zone is substantially oxygen-free, and calcining the pre-calcined precursor to obtain the catalyst.

[0004] CN107952441A discloses a method for preparing a propane catalytic combustion composite oxide catalyst and its application. The catalyst preparation method uses the citric acid method to prepare cerium-cobalt composite oxides, with the following steps: cobalt nitrate and cerium nitrate are weighed and dissolved in deionized water to form solution A; citric acid is weighed and dissolved in deionized water to form solution B; solutions A and B are mixed and stirred to obtain solution C; solution C is rotary evaporated to obtain a gel-like substance D; the obtained substance D is dried, calcined at 300℃-350℃ for 1-2 hours to obtain a solid substance, which is then ground and calcined at 500℃-700℃ for 3-4 hours to obtain the cerium-cobalt composite oxide. However, the catalysts provided by the above patents cannot simultaneously meet the requirements of high space velocity and sulfur resistance.

[0005] Therefore, there is an urgent need for a method to prepare catalysts that can exhibit good catalytic performance under high space velocities and sulfur-containing atmospheres. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a catalyst, its preparation method, and its applications. The present invention uses a catalyst support material with a median particle size of 20-150 nm modified with a strongly electronegative group, and loads an active component onto the modified support. The combined effect of the strongly electronegative group, the active component, and the catalyst support material enhances the catalyst's activity and sulfur resistance, enabling the catalyst to exhibit good catalytic performance even under low temperature, high space velocity, and sulfur-containing atmosphere conditions.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing a catalyst, the method comprising the following steps:

[0009] (1) Mix the solution containing strong electronegative groups with the catalyst support raw material, dry it and then calcine it to obtain a catalyst support modified with strong electronegative groups.

[0010] (2) The catalyst support modified with the strong electronegative group and the precursor solution of the active component are mixed, dried and then calcined to obtain the catalyst;

[0011] The strongly electronegative group includes SO4. 2- WO4 2- VO3 - MoO4 2- PO4 3- Trifluoromethyl, PW 12 O 40 4- At least one of (phosphotungstic acid) and Nb2O5; the median particle size of the catalyst support raw material is 20-150 nm, for example, it can be 20 nm, 30 nm, 40 nm, 50 nm, 60 nm, 70 nm, 80 nm, 90 nm, 100 nm, 110 nm, 120 nm, 130 nm, 140 nm or 150 nm, etc.

[0012] This invention provides a method for preparing a catalyst. The preparation process is simple, involving modifying a catalyst support material with a median particle size of 20-150 nm using strongly electronegative groups, and then loading an active component onto the modified support. The strongly electronegative groups synergistically interact with the active component to promote the activation of molecular oxygen and propane CH bonds, making the prepared catalyst more sensitive to high space velocities and redox atmospheres, significantly improving its activity at high space velocities and low temperatures. Simultaneously, the strongly electronegative groups and the active component jointly enhance the catalyst's resistance to sulfur poisoning. Furthermore, using a catalyst support material with a median particle size of 20-150 nm further improves the catalyst's activity.

[0013] Furthermore, the catalyst prepared by the method of the present invention can self-adjust and optimize the state of the active components under the action of the heat energy of the catalytic oxidation reaction to achieve the best catalytic activity to adapt to high space velocity; even under low temperature, high space velocity and sulfur-containing atmosphere, the catalyst can exhibit high catalytic activity and high stability, which significantly reduces the energy consumption during propane combustion.

[0014] In this invention, if the particle size of the catalyst support material is too small, the catalyst will gradually sinter and deactivate, which is not conducive to its long-term catalytic stability; if the particle size of the catalyst support material is too large, the catalyst's specific surface area will decrease and its surface active species will agglomerate and have insufficient activity.

[0015] Preferably, the substance containing the strongly electronegative group includes at least one of hydrogen chloride, sulfuric acid, nitric acid, phosphoric acid, ammonium chloride, ammonium sulfate, ammonium molybdate, ammonium phosphate, tungstic acid, and ammonium metavanadate, and more preferably at least one of sulfuric acid, phosphoric acid, ammonium sulfate, ammonium molybdate, ammonium phosphate, tungstic acid, and ammonium metavanadate.

[0016] Preferably, the catalyst support material includes at least one of titanium dioxide, cerium-based metal oxide, acidic molecular sieve and molecular sieve-like material, and is preferably cerium-based metal oxide.

[0017] In this invention, the catalyst support material is preferably a cerium-based metal oxide because cerium-based metal oxides have stable oxygen storage and release capabilities and surface tunability.

[0018] Preferably, the cerium-based metal oxide comprises cerium dioxide and cerium-zirconium solid solution.

[0019] Preferably, the cerium dioxide is spherical cerium dioxide.

[0020] Preferably, the cerium dioxide includes a doping element, which includes at least one of Zr, Si, Al, Ti and rare earth elements.

[0021] Preferably, based on the mass of cerium dioxide as 100%, the mass fraction of the dopant element is 0-10%, for example, it can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc. Wherein, a mass fraction of 0% represents no doping.

[0022] Preferably, the cerium-zirconium solid solution includes a doping element, which includes at least one of Zr, Si, Al, Ti, and rare earth elements.

[0023] Preferably, based on the mass of the cerium-zirconium solid solution as 100%, the mass fraction of the doping element is 0-10%, for example, it can be 0%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, or 10%, etc. Wherein, a mass fraction of 0% represents no doping.

[0024] Preferably, the acidic molecular sieve includes silica acidic molecular sieve (SBA-15).

[0025] Preferably, based on the total mass of the catalyst support modified with the strongly electronegative groups as 100%, the mass fraction of the strongly electronegative groups is 5-20%, for example, it can be 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, or 20%, etc.

[0026] Preferably, the mixing process in step (1) is accompanied by ultrasonic treatment, and the ultrasonic treatment time is 10-60 min, for example, 10 min, 20 min, 30 min, 40 min, 50 min or 60 min.

[0027] Preferably, the drying method in step (1) includes rotary drying.

[0028] Preferably, the drying temperature in step (1) is 50-120°C, for example, it can be 50°C, 60°C, 70°C, 80°C, 90°C, 100°C, 110°C or 120°C.

[0029] Preferably, the calcination in step (1) is a stepwise calcination, which includes: first performing a first calcination, and then performing a second calcination to obtain a catalyst support modified with a strong electronegative group.

[0030] In this invention, step (1) is performed by stepwise calcination instead of one-step calcination because stepwise calcination is more conducive to the retention and dispersion of the strongly negatively charged species on the surface of the carrier.

[0031] Preferably, the temperature of the first calcination is 300-400℃, for example, it can be 300℃, 310℃, 320℃, 330℃, 340℃, 350℃, 360℃, 370℃, 380℃, 390℃ or 400℃, etc.

[0032] Preferably, the calcination time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.4 hours, 1.6 hours, 1.8 hours, 2 hours, 2.2 hours, 2.4 hours, 2.6 hours, 2.8 hours or 3 hours.

[0033] Preferably, the temperature of the secondary calcination is 400-700℃, for example, it can be 400℃, 420℃, 440℃, 460℃, 480℃, 500℃, 520℃, 540℃, 600℃, 620℃, 650℃, 680℃ or 700℃, etc.

[0034] Preferably, the secondary calcination time is 1-3 hours, for example, it can be 1 hour, 1.2 hours, 1.5 hours, 1.7 hours, 2 hours, 2.2 hours, 2.5 hours, 2.7 hours or 3 hours.

[0035] Preferably, both the primary calcination and the secondary calcination are carried out in an oxygen-containing atmosphere.

[0036] Preferably, the gas in the atmosphere of both the primary calcination and the secondary calcination is air.

[0037] Preferably, the active component in step (2) includes a noble metal element.

[0038] Preferably, the noble metal element includes at least one of Pt, Rh and Pd, and more preferably a combination of Pt and at least one of Rh and Pd, such as a combination of Pt and Rh, a combination of Pt and Pd, or a combination of Pt, Rh and Pd.

[0039] In this invention, an active component containing Pt is selected because the electronic interaction between the strongly electronegative group and the Pt component is more conducive to promoting the activation of molecular oxygen and propane CH bond. At the same time, the combination of Rh and Pd elements helps to improve the catalyst activity.

[0040] Preferably, the mass fraction of the noble metal element is 0.1-5% based on 100% of the mass of the catalyst, for example, it can be 0.1%, 0.2%, 0.3%, 0.5%, 0.7%, 1%, 1.5%, 2%, 2.5%, 3%, 3.5%, 4%, 4.5% or 5%, etc.

[0041] Preferably, the active component further includes a first dopant element and / or a second dopant element.

[0042] Preferably, the first doping element includes at least one of Fe, Co, Sc, Mn, Ni and Cu.

[0043] Preferably, based on the total mass of the precious metal elements as 100%, the mass fraction of the first dopant element is 1-50%, for example, it can be 1%, 2%, 3%, 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, or 50%, etc.

[0044] Preferably, the second doping element includes at least one of C, N, and S.

[0045] Preferably, the ratio of the total molar amount of the second doped element to the molar amount of Pt element is 1:(1-20), for example, it can be 1:1, 1:2, 1:5, 1:7, 1:10, 1:15 or 1:20, etc.

[0046] Preferably, the mixing process in step (2) is accompanied by ultrasonic treatment, and the ultrasonic treatment time is 10-60 min, for example, it can be 10 min, 20 min, 30 min, 40 min, 50 min or 60 min, etc., preferably 20-30 min.

[0047] Preferably, step (2) further includes a step of allowing the mixture to stand between the mixing and the drying.

[0048] Preferably, the settling time is 1-24 hours, for example, it can be 1 hour, 2 hours, 5 hours, 10 hours, 12 hours, 15 hours, 17 hours, 20 hours or 24 hours, and preferably 6-12 hours.

[0049] Preferably, the heating rate of the calcination in step (2) is 2-5℃ / min, for example, it can be 2℃ / min, 3℃ / min, 4℃ / min or 5℃ / min, etc.

[0050] Preferably, the calcination temperature in step (2) is 300-700℃, for example, it can be 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃ or 700℃, etc., preferably 300-500℃.

[0051] Preferably, the calcination time in step (2) is 2-6 hours, for example, it can be 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours, 5 hours, 5.5 hours or 6 hours, preferably 2-4 hours.

[0052] Preferably, the calcination atmosphere in step (2) is an oxygen-containing atmosphere.

[0053] Preferably, the gas in the calcination atmosphere in step (2) is air.

[0054] Preferably, step (2) further includes an activation step after calcination.

[0055] Preferably, the gases in the activated atmosphere include propane and air.

[0056] Preferably, the volume fraction of propane is 0.3-2% based on the total volume of propane and air as 100%, for example, it can be 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.55%, 0.6%, 1%, 1.5% or 2%, etc.

[0057] Preferably, the activation temperature is 100-400℃, for example, it can be 100℃, 150℃, 200℃, 250℃, 300℃, 350℃ or 400℃.

[0058] As a preferred technical solution of the present invention, the preparation method includes the following steps:

[0059] (I) A solution containing a strong electronegative group is mixed with a catalyst support material with a median particle size of 20-150 nm. The mixing process is accompanied by ultrasonic treatment for 10-60 min. After drying, the mixture is calcined in steps: first at 300-400 °C for 1-3 h, and then at 400-700 °C for 1-3 h, to obtain a catalyst support modified with a strong electronegative group.

[0060] (II) The catalyst support modified with the strong electronegative group is mixed with the precursor solution of the active component. The mixing process is accompanied by ultrasonic treatment for 10-60 min. After standing for 1-24 h, it is dried and then calcined at 300-700℃ for 2-6 h to obtain the catalyst after activation.

[0061] The strongly electronegative group includes SO4. 2- WO4 2- VO3 - MoO4 2- PO4 3- Trifluoromethyl, PW 12 O 40 4- At least one of Nb2O5.

[0062] In a second aspect, the present invention provides a catalyst prepared by the preparation method described in the first aspect.

[0063] Thirdly, the present invention provides an application of the catalyst described in the second aspect, wherein the catalyst is applied in the field of propane catalytic combustion.

[0064] The numerical range described in this invention includes not only the point values ​​listed above, but also any point values ​​within the numerical ranges not listed above. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific point values ​​included in the range.

[0065] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0066] (1) This invention provides a method for preparing a catalyst, which is simple in process. A catalyst support material with a median particle size of 20-150 nm is modified with a strongly electronegative group, and an active component is loaded onto the modified support. The strongly electronegative group can synergistically interact with the active component to promote the activation of molecular oxygen and propane CH bonds, making the prepared catalyst more sensitive to high space velocities and redox atmospheres, significantly improving its activity at high space velocities and low temperatures. Simultaneously, the strongly electronegative group and the active component can jointly enhance the catalyst's resistance to sulfur poisoning. Furthermore, using a catalyst support material with a median particle size of 20-150 nm is more conducive to balancing the activity and stability of the catalyst.

[0067] (2) The catalyst prepared by the method of the present invention can self-adjust and optimize the state of the active components under the action of the heat energy of the catalytic oxidation reaction to achieve the best catalytic activity to adapt to high space velocity; even at low temperature, high space velocity and sulfur-containing atmosphere, the catalyst can exhibit high catalytic activity and high stability. Attached Figure Description

[0068] Figure 1 This is a schematic diagram of the mechanism in the catalyst preparation method provided in Example 1 of the present invention.

[0069] Figure 2 The diagram shows the sulfur resistance of the catalyst provided in Example 10 of this invention for the catalytic combustion of propane. Detailed Implementation

[0070] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0071] Example 1

[0072] This embodiment provides a method for preparing a catalyst, the method comprising:

[0073] (1) Weigh an appropriate amount of cerium dioxide nanospheres (CNs) with a median particle size of 100 nm, mix them with a certain amount of H2SO4 solution with a concentration of 0.05 mol / L, sonicate for 30 min, and then evaporate them while stirring on a magnetic stirrer at a temperature of about 80 °C. After evaporation, grind the obtained mixture and place it in a muffle furnace for calcination. In an air atmosphere, heat it to 300 °C at a heating rate of 5 °C / min, pre-calcine it at 300 °C for 1 h, and then calcine it at 500 °C for 3 h to obtain the H2SO4-treated CeO2-based catalyst support, denoted as H2SO4-CNs. The total mass of H2SO4-CNs is 100%, and the mass fraction of sulfate groups is 10%.

[0074] (2) Take an appropriate amount of H2SO4-treated CeO2-based catalyst support, mix it with a certain amount of platinum nitrate solution, sonicate it for 20-30 min and let it stand for 8 h, then put the mixed solution into an oven and dry it at 80℃ for 8 h, grind it and put it into a muffle furnace and calcine it in an air atmosphere, heat it to 400℃ at a heating rate of 2℃ / min, then keep it at 400℃ for 2 h and then cool it naturally to room temperature to obtain a noble metal supported CeO2-based catalyst, denoted as Pt-H2SO4-CNs, wherein the mass fraction of noble metal elements is 1% based on the total mass of Pt-H2SO4-CNs as 100%;

[0075] (3) The catalyst obtained in step (2) is activated by heating from 100°C to 400°C at a heating rate of 5°C / min in an atmosphere of propane and air to obtain the catalyst, wherein the volume fraction of propane is 0.5% based on the total volume of propane and air as 100%.

[0076] Example 2

[0077] This embodiment provides a method for preparing a catalyst. The difference from Example 1 is that the H2SO4 solution in step (1) is replaced with H3PO4 solution, and the rest is exactly the same as in Example 1.

[0078] Example 3

[0079] This embodiment provides a method for preparing a catalyst. The difference from Example 1 is that the H2SO4 solution in step (1) is replaced with an ammonium sulfate solution with a concentration of 10 wt%. The rest is exactly the same as in Example 1.

[0080] Example 4

[0081] This embodiment provides a method for preparing a catalyst, which differs from Example 1 in that, in step (1), cerium dioxide nanospheres are replaced with Sm-doped cerium-zirconium solid solution Ce. 0.6 Zr 0.4 O2(Sm / CZO), wherein, based on the total mass of the cerium-zirconium solid solution as 100%, the mass fraction of Sm is 10%, and the rest is exactly the same as in Example 1.

[0082] Example 5

[0083] This embodiment provides a method for preparing a catalyst, which differs from Example 2 in that, in step (1), cerium dioxide nanospheres are replaced with Sm-doped cerium-zirconium solid solution Ce. 0.6 Zr 0.4O2(Sm / CZO), wherein, based on the total mass of the cerium-zirconium solid solution as 100%, the mass fraction of Sm is 10%, and the rest is exactly the same as in Example 2.

[0084] Example 6

[0085] This embodiment provides a method for preparing a catalyst, which differs from Example 3 in that, in step (1), cerium dioxide nanospheres are replaced with Sm-doped cerium-zirconium solid solution Ce. 0.6 Zr 0.4 O2(Sm / CZO), wherein, based on the total mass of the cerium-zirconium solid solution as 100%, the mass fraction of Sm is 10%, and the rest is exactly the same as in Example 3.

[0086] Example 7

[0087] This embodiment provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), cerium dioxide nanospheres are replaced with silica acid molecular sieves (SBA-15), while the rest is exactly the same as in Example 1.

[0088] Example 8

[0089] This embodiment provides a method for preparing a catalyst. The difference from Example 2 is that in step (1), cerium dioxide nanospheres are replaced with silica acid molecular sieves (SBA-15), while the rest is exactly the same as in Example 2.

[0090] Example 9

[0091] This embodiment provides a method for preparing a catalyst. The difference from Example 3 is that in step (1), cerium dioxide nanospheres are replaced with silica acid molecular sieves (SBA-15), while the rest is exactly the same as in Example 3.

[0092] Example 10

[0093] This embodiment provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), cerium dioxide nanospheres are replaced with titanium dioxide; and in step (2), platinum nitrate solution is replaced with a mixed solution of platinum nitrate and palladium nitrate, wherein the mass ratio of platinum to palladium is 9:1, and the rest is exactly the same as in Example 1.

[0094] Example 11

[0095] This embodiment provides a method for preparing a catalyst, the method comprising:

[0096] (1) Weigh an appropriate amount of cerium dioxide nanospheres with a median particle size of 60 nm, mix them with a certain amount of H2SO4 solution with a concentration of 0.05 mol / L, sonicate for 20 min, and then evaporate to dryness while stirring on a magnetic stirrer. The temperature is controlled at about 60 °C. After evaporation, grind the obtained mixture and put it into a muffle furnace for calcination. In an air atmosphere, heat it to 350 °C at a heating rate of 5 °C / min, pre-calcine it at 350 °C for 1.5 h, and then calcine it at 600 °C for 3 h to obtain the H2SO4-treated CeO2-based catalyst support, denoted as H2SO4-CNs. The total mass of H2SO4-CNs is 100%, and the mass fraction of sulfate groups is 15%.

[0097] (2) Take an appropriate amount of H2SO4-treated CeO2-based catalyst support, mix it with a certain amount of platinum nitrate and rhodium nitrate solution, sonicate for 30 min and let stand for 10 h, then put the mixed solution into an oven and dry it at 60℃ for 8 h. After grinding, put it into a muffle furnace and calcine it in an air atmosphere. Heat it to 500℃ at a heating rate of 3℃ / min, then keep it at 500℃ for 2 h and cool it naturally to room temperature to obtain a noble metal supported CeO2-based catalyst, denoted as Pt / Rh-H2SO4-CNs, wherein the mass fraction of noble metal elements is 3% based on the total mass of Pt / Rh-H2SO4-CNs as 100%.

[0098] (3) The catalyst obtained in step (2) is activated by heating from 100°C to 400°C at a heating rate of 5°C / min in an atmosphere of propane and air to obtain the catalyst, wherein the volume fraction of propane is 0.5% based on the total volume of propane and air as 100%.

[0099] Example 12

[0100] This embodiment provides a method for preparing a catalyst, the method comprising:

[0101] (1) Weigh an appropriate amount of cerium dioxide nanospheres with a median particle size of 120 nm, mix them with a certain amount of H2SO4 solution with a concentration of 0.05 mol / L, sonicate for 50 min, and then evaporate to dryness while stirring on a magnetic stirrer. The temperature is controlled at about 60 °C. After evaporation, grind the obtained mixture and put it into a muffle furnace for calcination. In an air atmosphere, heat it to 400 °C at a heating rate of 5 °C / min, pre-calcine it at 400 °C for 2 h, and then calcine it at 700 °C for 1 h to obtain the H2SO4-treated CeO2-based catalyst support, denoted as H2SO4-CNs. The total mass of H2SO4-CNs is 100%, and the mass fraction of sulfate groups is 20%.

[0102] (2) Take an appropriate amount of H2SO4-treated CeO2-based catalyst support, mix it with a certain amount of palladium nitrate solution, sonicate it for 40 min and let it stand for 20 h, then put the mixed solution into an oven and dry it at 60℃ for 10 h. After grinding, put it into a muffle furnace and calcine it in an air atmosphere. Heat it to 600℃ at a heating rate of 5℃ / min, then keep it at 600℃ for 2 h and then cool it naturally to room temperature to obtain a noble metal supported CeO2-based catalyst, denoted as Pd-H2SO4-CNs, wherein the mass fraction of noble metal elements is 5% based on the total mass of Pd-H2SO4-CNs as 100%.

[0103] (3) The catalyst obtained in step (2) is activated by heating from 100°C to 400°C at a heating rate of 5°C / min in an atmosphere of propane and air to obtain the catalyst, wherein the volume fraction of propane is 0.5% based on the total volume of propane and air as 100%.

[0104] Example 13

[0105] This embodiment provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), the pre-calcination step is omitted, and the catalyst is calcined at 500°C for 3 hours. The rest is exactly the same as in Example 1.

[0106] Comparative Example 1

[0107] This comparative example provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), the step of mixing cerium dioxide nanospheres with H2SO4 solution is omitted, and the cerium dioxide nanospheres are directly calcined. The rest is exactly the same as in Example 1.

[0108] Comparative Example 2

[0109] This comparative example provides a method for preparing a catalyst. The difference from Comparative Example 1 is that in step (1), cerium dioxide nanospheres are replaced with Sm-doped cerium-zirconium solid solution Ce. 0.6 Zr 0.4 O2(Sm / CZO), wherein, based on the total mass of the cerium-zirconium solid solution as 100%, the mass fraction of Sm is 10%, and the rest is exactly the same as Comparative Example 1.

[0110] Comparative Example 3

[0111] This comparative example provides a method for preparing a catalyst. The difference between this method and Comparative Example 1 is that in step (1), cerium dioxide nanospheres are replaced with silica acid molecular sieves (SBA-15), while the rest is exactly the same as Comparative Example 1.

[0112] Comparative Example 4

[0113] This comparative example provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), the median particle size of the cerium dioxide nanospheres is adjusted to 10 nm, while the rest is exactly the same as in Example 1.

[0114] Comparative Example 5

[0115] This comparative example provides a method for preparing a catalyst. The difference from Example 1 is that in step (1), the median particle size of the cerium dioxide nanospheres is adjusted to 165 nm, while the rest is exactly the same as in Example 1.

[0116] The propane catalytic combustion performance of the catalysts provided in Examples 1-13 and Comparative Examples 1-5 was tested under the following conditions: high space velocity of 120,000 h⁻¹, test temperature range of 200-400 °C, test temperature gradient of 50 °C, and the test was conducted after each temperature point had stabilized for 15 minutes. The test results are shown in Table 1.

[0117] The propane catalytic combustion performance of the catalyst provided in Example 3 was tested at different space velocities. The test conditions were as follows: space velocities of 120,000, 240,000, 360,000, and 480,000, with the other test conditions being the same as above. The test results are shown in Table 2.

[0118] The propane catalytic combustion performance of the catalysts provided in Examples 1-13 and Comparative Examples 1-5 was tested under a sulfur-containing atmosphere. The tests were conducted at 300°C under conditions of a high space velocity of 300,000 mL / (h·g) and an ultra-high concentration of 500 ppm SO2. The results are shown in Table 3. The results for Example 10 are as follows: Figure 2 As shown in the figure, alloying and surface modification with strong negative charge can give the catalyst strong resistance to poisoning by high concentrations of sulfur dioxide and adaptability at high space velocities.

[0119] Table 1

[0120]

[0121]

[0122] Table 2

[0123]

[0124] Table 3

[0125]

[0126] analyze:

[0127] As can be seen from the results of Examples 1-12, the present invention uses strongly electronegative groups to modify catalyst support raw materials with a median particle size of 20-150 nm, and loads active components on the modified support. For example... Figure 1As shown, the strongly electronegative groups can synergistically interact with the active components, making the prepared catalyst more sensitive to redox atmospheres and significantly improving its activity at high space velocities and low temperatures. Simultaneously, the strongly electronegative groups and the active components can jointly enhance the catalyst's resistance to sulfur poisoning. This is because: the strongly electronegative groups and the active components can promote the activation of molecular oxygen and propane CH bonds, and catalyst supports with a median particle size of 20-150 nm are more conducive to improving catalytic activity; furthermore, the catalyst prepared using the method of this invention can self-adjust and optimize the state of the active components under the influence of the heat energy of the catalytic oxidation reaction to achieve optimal catalytic activity adapted to high space velocities. Therefore, the catalyst of this invention can also exhibit high catalytic activity and high stability under low temperature, high space velocity, and sulfur-containing atmospheres.

[0128] As can be seen from the results of Examples 1 and 13, if one-step calcination is used in step (1), the retention and dispersion of strongly electronegative species on the surface of the support will be poor, thereby reducing the activity and sulfur resistance of the catalyst at high space velocities.

[0129] The results of Examples 1-9 and Comparative Examples 1-3 show that the modification of the support surface with strongly electronegative species is beneficial to the activity and sulfur resistance of the catalyst at high space velocities.

[0130] As can be seen from the results of Example 1 and Comparative Examples 4-5, if the particle size of the carrier is too small, it will lead to accelerated deactivation under high concentrations of sulfur dioxide; if the particle size of the carrier is too large, it will lead to poor performance at high space velocities.

[0131] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. The application of a catalyst, characterized in that, The catalyst is used in the field of propane catalytic combustion. The method for preparing the catalyst includes the following steps: (1) Mix the solution containing a strong electronegative group with the catalyst support raw material, dry it and then calcine it to obtain a catalyst support modified with a strong electronegative group; (2) The catalyst support modified with the strong electronegative group and the precursor solution of the active component are mixed, dried and then calcined to obtain the catalyst; The strongly electronegative group includes SO4. 2- and PO4 3- At least one of them; The median particle size of the catalyst support material is 20-150 nm; The catalyst support material includes at least one of titanium dioxide, cerium-based metal oxides, acidic molecular sieves, and molecular sieve-like materials. The active component includes a noble metal element, which includes at least one of Pt, Rh and Pd. The calcination in step (1) is a stepwise calcination, which includes: first calcination, then calcination, to obtain a catalyst support modified with a strong electronegative group; The temperature of the first calcination is 300-400℃, and the time of the first calcination is 1-3 hours; The temperature of the secondary calcination is 400-700℃, and the time of the secondary calcination is 1-3 hours.

2. The application according to claim 1, characterized in that, The catalyst support material is a cerium-based metal oxide.

3. The application according to claim 2, characterized in that, The cerium-based metal oxides include cerium dioxide and cerium-zirconium solid solutions.

4. The application according to claim 3, characterized in that, The cerium dioxide is spherical cerium dioxide.

5. The application according to claim 3, characterized in that, The cerium dioxide includes a doping element, which includes at least one of Zr, Si, Al, Ti and rare earth elements.

6. The application according to claim 5, characterized in that, With the mass of cerium dioxide being 100%, the mass fraction of the doping element is 0-10% and not 0.

7. The application according to claim 3, characterized in that, The cerium-zirconium solid solution includes doping elements, which include at least one of Zr, Si, Al, Ti, and rare earth elements.

8. The application according to claim 7, characterized in that, With the mass of the cerium-zirconium solid solution being 100%, the mass fraction of the doping element is 0-10% and not 0.

9. The application according to claim 1, characterized in that, With the total mass of the catalyst support modified by the strongly electronegative groups being 100%, the mass fraction of the strongly electronegative groups is 5-20%.

10. The application according to claim 1, characterized in that, The mixing process in step (1) is accompanied by ultrasonic treatment, which lasts for 10-60 minutes.

11. The application according to claim 1, characterized in that, The drying method described in step (1) includes rotary drying.

12. The application according to claim 1, characterized in that, The drying temperature in step (1) is 50-120℃.

13. The application according to claim 1, characterized in that, Both the primary and secondary calcinations are conducted in an oxygen-containing atmosphere.

14. The application according to claim 1, characterized in that, Based on the mass of the catalyst being 100%, the mass fraction of the precious metal element is 0.1-5%.

15. The application according to claim 1, characterized in that, The active component further includes a first doping element and / or a second doping element.

16. The application according to claim 15, characterized in that, The first doping element includes at least one of Fe, Co, Sc, Mn, Ni and Cu.

17. The application according to claim 15, characterized in that, With the total mass of the precious metal elements being 100%, the mass fraction of the first dopant element is 1-50%.

18. The application according to claim 15, characterized in that, The second doping element includes at least one of C, N, and S.

19. The application according to claim 1, characterized in that, In step (2), the mixing process is accompanied by ultrasonic treatment, which takes 10-60 minutes.

20. The application according to claim 19, characterized in that, The ultrasonic treatment time is 20-30 minutes.

21. The application according to claim 1, characterized in that, Step (2) further includes a step of allowing the mixture to stand between the mixing and the drying.

22. The application according to claim 21, characterized in that, The settling time is 1-24 hours.

23. The application according to claim 21, characterized in that, The settling time is 6-12 hours.

24. The application according to claim 1, characterized in that, The heating rate for calcination in step (2) is 2-5℃ / min.

25. The application according to claim 1, characterized in that, The calcination temperature in step (2) is 300-700℃.

26. The application according to claim 1, characterized in that, The calcination temperature in step (2) is 300-500℃.

27. The application according to claim 1, characterized in that, The calcination time in step (2) is 2-6 hours.

28. The application according to claim 1, characterized in that, The calcination time in step (2) is 2-4 hours.

29. The application according to claim 1, characterized in that, The calcination atmosphere in step (2) is an oxygen-containing atmosphere.

30. The application according to claim 1, characterized in that, Step (2) also includes an activation step after the calcination.

31. The application according to claim 30, characterized in that, The gases in the activated atmosphere include propane and air.

32. The application according to claim 31, characterized in that, With the total volume of propane and air being 100%, the volume fraction of propane is 0.3-2%.

33. The application according to claim 30, characterized in that, The activation temperature is 100-400℃.

34. The application according to claim 1, characterized in that, The preparation method includes the following steps: (I) A solution containing a strong electronegative group is mixed with a catalyst support material with a median particle size of 20-150 nm. The mixing process is accompanied by ultrasonic treatment for 10-60 min. After drying, the mixture is calcined in steps: first at 300-400 °C for 1-3 h, and then at 400-700 °C for 1-3 h, to obtain a catalyst support modified with a strong electronegative group. (II) The catalyst support modified with the strong electronegative group is mixed with the precursor solution of the active component. The mixing process is accompanied by ultrasonic treatment for 10-60 min. After standing for 1-24 h, it is dried and then calcined at 300-700℃ for 2-6 h to obtain the catalyst after activation. The strongly electronegative group includes SO4. 2- and PO4 3- At least one of them.

Images