A highly stable Pt-based catalyst, its preparation method and application in the catalytic oxidation of light alkanes

Abstract

The present invention discloses a highly stable Pt-based catalyst, a preparation method thereof, and an application in the catalytic oxidation of light alkanes. A transition metal salt is added to an inorganic acid, and NaHCO3, Na2CO3 or Na2SO4 is added to form a buffer solution; a Pt / SiO2 support, a Pt / TiO2 support or a Pt / CeO2 support is added to water to form a suspension; the suspension is added dropwise to the buffer solution, and after stirring evenly, an aqueous solution of NaHCO3, Na2CO3 or Na2SO4 is added, followed by filtration, and calcination is carried out at 300-400 °C for 1-3 h. In the present invention, the transition metal salt is used as a transition metal source. According to the characteristic that the d orbit of the transition metal element is easy to accept electrons to form a complex, through the redox reaction between the noble metal element Pt and the transition metal element ions, it can be adsorbed on the surface of the noble metal at room temperature to form a metal oxide film, so as to achieve the effect of stabilizing the noble metal.

Description

Technical Field

[0001] The present invention belongs to the field of air pollution control and technology, and particularly relates to a highly stable Pt-based catalyst, a preparation method thereof, and an application in the catalytic oxidation of light alkanes. Background Art

[0002] The emissions of volatile organic compounds (VOCs) are continuously increasing, causing great harm to the environment and triggering the formation of many adverse weather conditions. Among them, light alkanes as VOCs are very stable and difficult to break due to their large C-H bond energy. Compared with transition metal catalysts, noble metal catalysts have high activity and good selectivity and have been widely used in industrial catalysis. However, they are prone to sintering and deactivation due to poisoning, which hinders their development. Therefore, exploring the preparation of highly stable noble metal catalysts is crucial for the development of industrial catalysis.

[0003] Chinese Patent No. 201810222359.1 discloses a "method for improving the thermal stability of noble metal nanocatalysts", which improves the anti-sintering performance of noble metals. However, its preparation method is obtained by high-temperature treatment of noble metal catalysts loaded with organic matter in an inert atmosphere and an air atmosphere.

[0004] Chinese Patent No. 201910020661.3 discloses a "noble metal catalyst with high thermal stability and its preparation method", and its preparation process also must be calcined at a high temperature (500 - 600 °C) to obtain the target catalyst.

[0005] Therefore, how to modify noble metal catalysts through simple steps to improve their thermal stability at room temperature is still challenging. Summary of the Invention

[0006] To overcome the problems in the prior art, the purpose of the present invention is to provide a highly stable Pt-based catalyst, a preparation method thereof, and an application in the catalytic oxidation of light alkanes. The preparation method of the present invention has the characteristics of being economical and inexpensive, having simple preparation materials, mild synthesis conditions, and the prepared catalyst having high low-temperature reaction activity, good high-temperature stability, and good water resistance.

[0007] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0008] A preparation method of a highly stable Pt-based catalyst, comprising the following steps:

[0009] 1) Add a transition metal salt to an inorganic acid, mix evenly, and then add NaHCO3, Na2CO3, or Na2SO4 to form a buffer solution;

[0010] Add the Pt / SiO2 support, Pt / TiO2 support or Pt / CeO2 support to water to form a suspension;

[0011] 2) While stirring, add the suspension to a dropping buffer solution. After stirring evenly, add an aqueous solution of NaHCO3, Na2CO3 or Na2SO4. After stirring evenly, filter, and dry the obtained solid at 100 - 150 °C for 2 - 8 h, and calcine it at 300 - 400 °C for 1 - 3 h to obtain a highly stable Pt-based catalyst.

[0012] Furthermore, in step 1), the transition metal salt is CoCl2·6H2O, Co(NO3)2·6H2O, CoSO4·7H2O, FeCl3 or TiCl3.

[0013] Furthermore, in step 1), the inorganic acid is hydrochloric acid, HNO3 or H2SO4.

[0014] Furthermore, the dosage ratio of the transition metal salt to the inorganic acid is 10 - 50 mg: 3 - 18 mg, the mass concentration of hydrochloric acid is 37%, and the mass concentrations of HNO3 and H2SO4 are 98%.

[0015] Furthermore, in steps 1) and 2), the sodium salt is NaHCO3, Na2CO3 or Na2SO4; in step 1), the mass ratio of the sodium salt to the transition metal salt is 10 - 30: 10 - 50; in step 2), the dosage ratio of the aqueous sodium salt solution to the transition metal salt is 1 - 5 mL: 10 - 50 mg, and the concentration of the aqueous sodium salt solution is 0.5 - 1.5 mol / L.

[0016] Furthermore, in step 1), the Pt / SiO2 support, Pt / TiO2 support or Pt / CeO2 support is prepared through the following process: Dissolve urea in an aqueous H2PtCl6 solution, then add SiO2, TiO2 or CeO2 powder, stir at 80 - 120 °C for 5 - 10 h, filter and separate the solid, dry it, and then calcine it at 300 - 500 °C for 4 - 8 h.

[0017] Furthermore, the dosage ratio of urea to the aqueous H2PtCl6 solution is 0.1 - 0.8 g: 100 - 200 mL, the concentration of the aqueous H2PtCl6 solution is 0.1 - 0.5 mmol / L; the mass ratio of SiO2, TiO2 or CeO2 powder to urea is 0.5 - 2 g: 0.1 - 0.8 g.

[0018] Furthermore, in step 2), the mass ratio of one of the Pt / SiO2 support, Pt / TiO2 support and Pt / CeO2 support to the transition metal salt is 1 - 2 g: 10 - 50 mg.

[0019] A highly stable Pt-based catalyst prepared according to the preparation method described above.

[0020] Application of a highly stable Pt-based catalyst prepared according to the above preparation method in the catalytic oxidation of light alkanes.

[0021] Furthermore, in step 1), the drying temperature is 100 - 150 °C and the time is 2 - 8 h.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] In the present invention, transition metal salts are used as the transition metal source. According to the characteristic that the d orbitals of transition metal elements are easy to accept electrons to form complexes, through the redox reaction between the noble metal element Pt and transition metal element ions, it can be adsorbed on the surface of the noble metal at room temperature to form a metal oxide film, so as to achieve the effect of stabilizing the noble metal, and solve the problem of improving the thermal stability of noble metal catalysts through simple steps under room temperature conditions. At the same time, there is a difference in electronegativity between the noble metal and the transition metal element, which will promote the transfer of some electrons on the transition metal to the d orbitals of the noble metal, thereby further changing the defect state, electronic structure and surface characteristics of the noble metal, which is beneficial to the adsorption and activation of reactant molecules and reduces the chemical reaction energy barrier.

[0024] Under the space velocity condition of 20000 h -1 , balance gas N2, 21% O2 and 2500 ppm C3H8 are introduced. When the reaction temperature is 270 °C, propane can be completely oxidized, and it still has excellent catalytic oxidation performance after calcination at 800 °C for 5 hours. Its excellent high-temperature stability stems from the space confinement effect formed by the M thin layer, which hinders the aggregation of active sites, and at the same time has strong water resistance. The catalyst of the present invention has simple and green synthesis steps. The prepared Pt@M / (SiO2, TiO2 or CeO2) catalyst has good catalytic oxidation performance for propane at low temperature. The degradation rate of propane reaches 100% at 270 °C, and its stability is better than that of traditional industrial noble metal catalysts. Therefore, using the prepared highly stable Pt-based catalyst to catalytically oxidize light alkanes has certain industrial practical value. Description of the Drawings

[0025] Figure 1 It is the electron microscope image and particle size distribution diagram of Pt / SiO2. Among them, (a) is the field emission transmission electron microscope image, and (b) is the field emission high-magnification transmission electron microscope image.

[0026] Figure 2 For Pt@CoO x (0.4 wt% Co) / SiO2 high-magnification transmission electron microscope image.

[0027] Figure 3 It is Pt@CoO x (0.6 wt% Co) / SiO2 high-magnification transmission electron microscopy image.

[0028] Figure 4 It is Pt@CoO x (1.2 wt% Co) / SiO2 high-magnification transmission electron microscopy image.

[0029] Figure 5 It is Pt@CoO x (0.4 wt% Co) / SiO2-800 and Pt / SiO2-800 field emission transmission electron microscopy images. Among them, (a) is Pt@CoO x (0.4 wt% Co) / SiO2-800 field emission transmission electron microscopy image, (b) is Pt / SiO2-800 field emission transmission electron microscopy image, (c) is Pt@CoO x (0.4 wt% Co) / SiO2-800 particle size distribution diagram, (d) is Pt / SiO2-800 particle size distribution diagram.

[0030] Figure 6 It is the propane catalytic oxidation performance diagram of the catalyst under the test conditions of C3H8 concentration of 2500 ppm and space velocity of 20000 h -1 Test conditions.

[0031] Figure 7 It is the propane catalytic oxidation performance diagram of the catalyst under the test conditions of C3H8 concentration of 2500 ppm and space velocity of 20000 h -1 High-temperature stability and water resistance under test conditions. Specific implementation method

[0032] The present invention will be described in detail below with reference to the accompanying drawings.

[0033] A preparation method of a highly stable Pt-based catalyst of the present invention includes the following steps:

[0034] First, the preparation of Pt / SiO2 (Pt / TiO2 or Pt / CeO2) catalyst: Dissolve 0.1 - 0.8 g of urea in 100 - 200 mL of H2PtCl6 aqueous solution (0.1 - 0.5 mmol / L), and then add 0.5 - 2 g of commercial SiO2 powder (TiO2 or CeO2). After stirring at 80 - 120 °C for 5 - 10 h, filter and separate the solid, wash it 4 - 5 times with 200 - 300 ml of H2O, dry it at 100 - 150 °C for 8 - 24 h, and calcine it at 300 - 500 °C for 4 - 8 h to obtain Pt / SiO2 (Pt / TiO2 or Pt / CeO2) catalyst.

[0035] Next is the preparation of Pt@M / (SiO2), Pt@M / (SiO2)TiO2 or Pt@M / (CeO2) catalysts:

[0036] Using a simple wet impregnation method, first prepare the M buffer solution: Add 10 - 50 mg of CoCl2·6H2O (Co(NO3)2·6H2O, CoSO4·7H2O, FeCl3 or TiCl3) and 3 - 18 mg of hydrochloric acid with a mass concentration of 37% (HNO3 with a mass concentration of 98% or H2SO4 with a mass concentration of 98%) to 10 - 20 mL of H2O, and then slowly add 10 - 30 mg of NaHCO3, Na2CO3 or Na2SO4 to the above solution to form the M buffer solution (NaHCO3, Na2CO3 or Na2SO4 is used to adjust the pH value to avoid the rapid deposition of Co, Fe or Ti species).

[0037] Next, disperse 1 - 2 g of Pt / SiO2 (Pt / TiO2 or Pt / CeO2) catalyst powder into 60 - 100 mL of H2O to obtain a suspension.

[0038] Finally, dropwise add the M buffer solution to the above suspension under stirring. After the addition is complete, stir for 1 - 3 h, then dropwise add 1 - 5 mL of an aqueous solution of NaHCO3, Na2CO3 or Na2SO4 (0.5 - 1.5 mol / L), and continue stirring for 2 - 5 h to deposit Co, Fe or Ti species. Finally, filter, wash 4 - 5 times with 300 - 500 mL of H2O, dry at 100 - 150 °C for 2 - 8 h, and calcine at 300 - 400 °C for 1 - 3 h to obtain a highly stable Pt-based catalyst.

[0039] The present invention investigated Pt@CoO x / SiO2 and Pt / SiO2 catalysts for their low-temperature catalytic activity in the catalytic oxidation of propane and the hydrothermal stability of the catalysts after high-temperature calcination.

[0040] Method of using the catalyst: Under the space velocity condition of 20000 h -1 using the as-prepared Pt@CoO x / SiO2 or Pt@CoO x / SiO2 catalyst calcined in air at 800 °C for 5 hours, Pt@CoO x / TiO2 catalyst or Pt@CoO x / CeO2 catalyst as the catalyst to catalytically oxidize propane in volatile organic compounds. The catalytic reaction temperature is 25 - 500 °C, the concentration of propane is 2500 ppm, and the volume concentration of oxygen is 21%.

[0041] Example 1

[0042] Dissolve 0.3 g of urea in 100 mL of an aqueous H2PtCl6 solution (0.5 mmol / L), and then add 1 g of commercial SiO2 powder. After stirring at 80 °C for 5 h, filter and separate the solid, wash it 5 times with 200 ml of H2O, dry it at 120 °C for 12 h, calcine it at 400 °C for 5 h, and pass it through a sieve of 40 - 60 mesh by pressing and crushing to obtain Pt / SiO2 powder, denoted as the Pt / SiO2 catalyst.

[0043] Prepare the CoOx buffer solution: Add 16 mg of CoCl2·6H2O and 9 mg of hydrochloric acid (mass concentration of 37%) to 10 mL of H2O, and then slowly add 18 mg of NaHCO3 to the above solution to form CoO x buffer solution.

[0044] Next, disperse 1 g of Pt / SiO2 powder into 60 mL of H2O to obtain a suspension.

[0045] While stirring the above suspension, add the CoO x buffer solution dropwise. After stirring for 1 h, add 1 mL of an aqueous NaHCO3 solution (1 mol / L) dropwise and continue stirring for 2 h. Finally, filter, wash it 5 times with 400 mL of H2O, dry it at 120 °C for 8 h, and calcine it at 400 °C for 2 h to obtain Pt@CoO x (0.4 wt% Co) / SiO2 catalyst.

[0046] As can be seen from Figure 1 (a) and (b), the average size of Pt nanoparticles in the Pt / SiO2 catalyst prepared in Example 1 is 2.4 nm.

[0047] As can be seen from Figure 2 it, in the Pt@CoO x (0.4 wt% Co) / SiO2 catalyst prepared in Example 1, the surface of Pt nanoparticles is covered with a layer of CoO with a thickness of 0.37 nm x .

[0048] Example 2

[0049] The preparation of Pt / SiO2 powder is the same as in Example 1;

[0050] First, prepare the CoO x buffer solution: Add 24 mg of CoCl2·6H2O and 6 mg of hydrochloric acid to 10 mL of H2O, and then slowly add 12.5 mg of NaHCO3 to the above solution to form CoO x buffer solution.

[0051] Next, disperse 1 g of Pt / SiO2 powder into 60 mL of H2O to obtain a suspension.

[0052] Finally, CoO was added dropwise with stirring to the above suspension. x Buffer solution. After stirring for 1 h, 1.5 mL of aqueous NaHCO3 solution (1 mol / L) was added dropwise, and stirring was continued for 2 h. Finally, filtration was carried out, and it was washed 5 times with 400 mL of H2O, dried at 120 °C for 8 h, and calcined at 400 °C for 2 h to obtain Pt@CoO x (0.6 wt% Co) / SiO2 catalyst.

[0053] From Figure 3 it can be seen that in the Pt@CoO x (0.6 wt% Co) / SiO2 catalyst prepared in Example 2, the surface of the Pt nanoparticles was covered with a layer of CoO with a thickness of 0.84 nm. x .

[0054] Example 3

[0055] The Pt / SiO2 powder was prepared in the same manner as in Example 1;

[0056] First, CoO was prepared. x Buffer solution: 48 mg of CoCl2·6H2O and 12 mg of hydrochloric acid were added to 10 mL of H2O, and then 25 mg of NaHCO3 was slowly added to the above solution to form CoO x buffer solution.

[0057] Then, 1 g of Pt / SiO2 powder was dispersed in 60 mL of H2O to obtain a suspension.

[0058] Finally, CoO was added dropwise with stirring to the above suspension. x Buffer solution. After stirring for 1 h, 1.5 mL of aqueous NaHCO3 solution (1 mol / L) was added dropwise, and stirring was continued for 2 h. Finally, filtration was carried out, and it was washed 5 times with 400 mL of H2O, dried at 120 °C for 8 h, and calcined at 400 °C for 2 h to obtain Pt@CoO x (1.2 wt% Co) / SiO2 catalyst.

[0059] From Figure 4 it can be seen that in the Pt@CoO x (1.2 wt% Co) / SiO2 catalyst prepared in Example 3, the surface of the Pt nanoparticles was covered with a layer of CoO with a thickness of 1.32 nm. x .

[0060] Comparative Example 1

[0061] Prepare CoO xBuffer solution: Dissolve 48 mg of CoCl2·6H2O and 12 mg of hydrochloric acid in 10 mL of H2O, and then slowly add 25 mg of NaHCO3 to the above solution to form CoO x buffer solution.

[0062] Next, disperse 1 g of SiO2 powder in 60 mL of H2O to obtain a suspension. Finally, dropwise add CoO x buffer solution to the above suspension under stirring. After stirring for 1 h, add 1.5 mL of aqueous NaHCO3 solution (1 mol / L), and continue stirring for 2 h. Finally, filter, wash with 400 mL of H2O 5 times, dry at 120 °C for 8 h, and calcine at 400 °C for 2 h to obtain CoO x / SiO2 catalyst.

[0063] The Pt / SiO2 catalyst and Pt@CoO x (0.4 wt% Co) / SiO2 catalyst obtained in Example 1 were calcined in a muffle furnace at 800 °C for 5 h to obtain catalysts Pt / SiO2-800 and Pt@CoO x (0.4 wt% Co) / SiO2-800, respectively.

[0064] As can be seen from Figure 5 (a), (b), (c), and (d) below, the average diameter of Pt particles on the surface of Pt@CoO x (0.4 wt% Co) / SiO2-800 increased from 2.4 nm to 4.4 nm, while the average diameter of Pt particles on the traditional Pt / SiO2-800 catalyst increased from 2.4 nm to 10.7 nm, indicating that Pt@CoO x (0.4 wt% Co) / SiO2 catalyst has excellent thermal stability and can prevent the aggregation of active sites at high temperatures.

[0065] Activity tests of the catalysts in Example 1, Example 2, Example 3, and Comparative Example 1:

[0066] Place 0.15 g of the catalysts in Example 1, Example 2, Example 3, and Comparative Example 1 in a fixed-bed reactor for catalytic activity evaluation. The experimental conditions are as follows: 2500 ppm C3H8, 21% O2, N2 as the balance gas, and the reaction space velocity is 20000 h -1 . The propane concentration was detected by gas chromatography.

[0067] The catalytic performance results are as shown in Figure 6 . As can be seen from Figure 6 , Pt@CoO x (0.4 wt% Co) / SiO2 catalyst can completely oxidize propane at 270 °C, and its performance is superior to other catalysts.

[0068] The catalysts in Example 1, Pt / SiO2-800, and Pt@CoO x (0.4 wt% Co) / SiO2-800 activity and stability test: 0.15 g of the catalysts Pt / SiO2-800 and Pt@CoO in Example 1 x (0.4 wt% Co) / SiO2-800 were placed in a fixed-bed reactor for catalytic activity evaluation. The experimental conditions were: 2500 ppm C3H8, 21% O2, 1% H2O, N2 as the balance gas, and the reaction space velocity was 20000 h -1 . The propane concentration was detected by gas chromatography.

[0069] The catalytic performance results are as Figure 7 shown. It can be seen from Figure 7 that the Pt@CoO x (0.4 wt% Co) / SiO2-800 catalyst could still completely oxidize propane at 348 °C, only a decrease of 80 °C, while the Pt / SiO2 catalyst decreased by 200 °C, showing excellent thermal stability. And in the presence of 1% moisture, the degradation efficiency of propane did not change, showing excellent water resistance.

[0070] Example 4

[0071] 0.1 g of urea was dissolved in 100 mL of an aqueous H2PtCl6 solution (0.1 mmol / L), and then 0.5 g of commercial TiO2 powder was added. After stirring at 120 °C for 5 h, the solid was separated by filtration, washed 4 times with 300 ml of H2O, dried at 100 °C for 24 h, calcined at 300 °C for 8 h, and passed through a 40-60 mesh sieve by pressing and crushing, denoted as the Pt / TiO2 catalyst.

[0072] Preparation of CoO x Buffer solution: 10 mg of Co(NO3)2·6H2O and 3 mg of hydrochloric acid (mass concentration 37%) were added to 20 mL of H2O, and then 10 mg of NaHCO3 was slowly added to the above solution to form CoO x buffer solution. Then 1 g of Pt / TiO2 powder was dispersed in 100 mL of H2O to obtain a suspension.

[0073] The CoO x buffer solution was added dropwise to the above suspension under stirring. After stirring for 2 h, 5 mL of an aqueous NaHCO3 solution (0.5 mol / L) was added dropwise, and stirring was continued for 5 h. Finally, filtration was carried out, washed 4 times with 300 mL of H2O, dried at 150 °C for 2 h, and calcined at 300 °C for 3 h to obtain the Pt@CoO x / TiO2 catalyst.

[0074] Example 5

[0075] Dissolve 0.5 g of urea in 150 mL of an aqueous H2PtCl6 solution (0.5 mmol / L), and then add 1.5 g of commercial CeO2 powder. After stirring at 80 °C for 10 h, filter and separate the solid, wash it 5 times with 220 mL of H2O, dry it at 120 °C for 20 h, calcine it at 500 °C for 4 h, and pass it through a sieve of 40 - 60 mesh by pressing and crushing, denoted as the Pt / CeO2 catalyst.

[0076] Preparation of CoO x Buffer solution: Add 24 mg of CoSO4·7H2O and 12.5 mg of hydrochloric acid (mass concentration 37%) to 10 mL of H2O, and then slowly add 25 mg of NaHCO3 to the above solution to form CoO x buffer solution. Then disperse 1 g of Pt / CeO2 powder into 60 mL of H2O to obtain a suspension.

[0077] Dropwise add the CoO x buffer solution to the above suspension under stirring. After stirring for 1 h, add 1.5 mL of an aqueous NaHCO3 solution (1 mol / L), and continue stirring for 2 h. Finally, filter, wash it 5 times with 400 mL of H2O, dry it at 120 °C for 8 h, and calcine it at 400 °C for 2 h to obtain the Pt@CoO x / CeO2 catalyst.

[0078] Example 6

[0079] Dissolve 0.8 g of urea in 200 mL of an aqueous H2PtCl6 solution (0.3 mmol / L), and then add 2 g of commercial TiO2 powder. After stirring at 100 °C for 7 h, filter and separate the solid, wash it 4 times with 260 mL of H2O, dry it at 150 °C for 8 h, calcine it at 350 °C for 7 h, and pass it through a sieve of 40 - 60 mesh by pressing and crushing, denoted as the Pt / TiO2 catalyst.

[0080] Preparation of FeOx buffer solution: Add 30 mg of FeCl3 and 10 mg of H2SO4 with a mass concentration of 98% to 13 mL of H2O, and then slowly add 30 mg of Na2CO3 to the above solution to form FeO x buffer solution. Then disperse 2 g of Pt / TiO2 powder into 70 mL of H2O to obtain a suspension.

[0081] Dropwise add the FeO xBuffer solution. After stirring for 1 h, 3 mL of aqueous Na2CO3 solution (1 mol / L) was added dropwise, and stirring was continued for 3 h. Finally, filtration was carried out, and the product was washed 4 times with 400 mL of H2O, dried at 130 °C for 5 h, and calcined at 350 °C for 3 h to obtain Pt@FeO x / SiO2 catalyst.

[0082] Example 7

[0083] Dissolve 0.4 g of urea in 120 mL of aqueous H2PtCl6 solution (0.4 mmol / L), and then add 0.8 g of commercial TiO2 powder. After stirring at 90 °C for 8 h, the solid was separated by filtration, washed 5 times with 300 ml of H2O, dried at 130 °C for 13 h, calcined at 450 °C for 5 h, and sieved through 40 - 60 mesh by pressing and crushing, denoted as Pt / TiO2 catalyst.

[0084] Prepare TiOx buffer solution: Add 50 mg of Ti and 18 mg of 98% mass concentration HNO3 to 17 mL of H2O, and then slowly add 15 mg of Na2SO4 to the above solution to form TiO x buffer solution. Then, 1.5 g of Pt / TiO2 powder was dispersed in 90 mL of H2O to obtain a suspension.

[0085] The TiO x buffer solution was added dropwise to the above suspension under stirring. After stirring for 2 h, 4 mL of aqueous Na2SO4 solution (1.5 mol / L) was added dropwise, and stirring was continued for 2 h. Finally, filtration was carried out, and the product was washed 5 times with 350 mL of H2O, dried at 120 °C for 7 h, and calcined at 400 °C for 2 h to obtain Pt@TiO x / SiO2 catalyst.

[0086] The Pt@CoO x / SiO2 catalyst prepared in the present invention forms a novel Pt - O - Co interface with CoO x thin layer loaded on Pt, which can serve as a highly active site and is crucial for catalytic activity. The Pt@CoO x / SiO2 catalyst enhances the electronic effect, geometric effect, and dual active site effect of the strong metal - support interaction through the directional loading of the oxide thin layer, thereby improving its low - temperature catalytic oxidation activity and hydrothermal stability.

Claims

1. A preparation method of a highly stable Pt-based catalyst, characterized in that, It includes the following steps: 1) Add a transition metal salt to an inorganic acid, and after mixing evenly, add a sodium salt to form a buffer solution; Add a Pt / SiO2 support, a Pt / TiO2 support or a Pt / CeO2 support to water to form a suspension; 2) Drop the suspension into the buffer solution under stirring, after stirring evenly, add an aqueous sodium salt solution, stir evenly and then filter, dry the obtained solid at 100 - 150 °C for 2 - 8 h, and calcine it at 300 - 400 °C for 1 - 3 h to obtain a highly stable Pt-based catalyst; In step 1), the transition metal salt is CoCl2·6H2O, Co(NO3)2·6H2O, CoSO4·7H2O, FeCl3 or TiCl3; In steps 1) and 2), the sodium salt is NaHCO3 or Na2CO3.

2. The preparation method of the highly stable Pt-based catalyst according to claim 1, characterized in that, In step 1), the inorganic acid is hydrochloric acid, HNO3 or H2SO4.

3. The preparation method of the highly stable Pt-based catalyst according to claim 2, wherein, The dosage ratio of the transition metal salt to the inorganic acid is 10 - 50 mg: 3 - 18 mg, the mass concentration of hydrochloric acid is 37%, and the mass concentrations of HNO3 and H2SO4 are 98%.

4. The preparation method of the highly stable Pt-based catalyst according to claim 1, characterized in that, In step 1), the mass ratio of the sodium salt to the transition metal salt is 10 - 30: 10 - 50; in step 2), the dosage ratio of the aqueous sodium salt solution to the transition metal salt is 1 - 5 mL: 10 - 50 mg, and the concentration of the aqueous sodium salt solution is 0.5 - 1.5 mol / L.

5. The preparation method of the highly stable Pt-based catalyst according to claim 1, characterized in that, In step 1), the Pt / SiO2 support, the Pt / TiO2 support or the Pt / CeO2 support is prepared through the following process: Dissolve urea in an aqueous H2PtCl6 solution, then add SiO2, TiO2 or CeO2 powder, stir at 80 - 120 °C for 5 - 10 h, filter and separate the solid, and after drying, calcine it at 300 - 500 °C for 4 - 8 h.

6. The preparation method of the highly stable Pt-based catalyst according to claim 5, wherein The dosage ratio of urea to the aqueous H2PtCl6 solution is 0.1 - 0.8 g: 100 - 200 mL, the concentration of the aqueous H2PtCl6 solution is 0.1 - 0.5 mmol / L; the mass ratio of SiO2, TiO2 or CeO2 powder to urea is 0.5 - 2 g: 0.1 - 0.8 g.

7. The preparation method of the highly stable Pt-based catalyst according to claim 1, characterized in that, In step 2), the mass ratio of one of the Pt / SiO2 support, the Pt / TiO2 support and the Pt / CeO2 support to the transition metal salt is 1 - 2 g: 10 - 50 mg.

8. A highly stable Pt-based catalyst prepared by any of the preparation methods according to claims 1 - 7.

9. The application of a highly stable Pt-based catalyst prepared by any of the preparation methods according to claims 1 - 7 in the catalytic oxidation of light alkanes.

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