Composite catalyst of high-entropy rare earth oxide cooperating with platinum / aluminum oxide and preparation method of composite catalyst

Abstract

The invention relates to a high-entropy rare earth oxide synergistic platinum / aluminum oxide composite catalyst and a preparation method thereof.The composite catalyst takes gamma-Al2O3 as a carrier, Pt as an active component and high-entropy rare earth oxide as an active auxiliary agent, in the preparation process, chloroplatinic acid, lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate and gadolinium nitrate are adopted to obtain active component gel, and the active component gel is mixed with the high-entropy rare earth oxide synergistic platinum / aluminum oxide composite catalyst; and adding a carrier to obtain catalyst pug, and finally aging, drying and roasting to obtain the composite catalyst. The prepared composite catalyst has more active sites, variable-valence rare earth elements and oxygen vacancy on the surface of the catalyst can effectively promote decomposition and conversion of pollutants such as NOx and ammonium bisulfate, and the composite catalyst has good CO oxidation catalytic activity and poisoning resistance in steel sintering flue gas at the temperature of 100-200 DEG C; the method is suitable for high-efficiency and high-stability CO removal of the steel sintering flue gas under the complex flue gas working condition containing various pollutants.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of catalyst preparation, in particular to a high-entropy rare earth oxide synergistic platinum / alumina composite catalyst and a preparation method thereof. BACKGROUND

[0002] In addition to containing a large amount of CO, the sintering flue gas discharged by the steel industry also contains SO2, NO x , alkali metals and other pollutants.

[0003] High-entropy oxides are a new type of material formed by five or more metal or non-metal oxides in equal or near-equal molar ratios through mutual solid solution, and have high configurational entropy. This high-entropy effect helps to stabilize the crystal structure, so that it can maintain good structural stability in complex flue gas environments and is not prone to phase transition and structural collapse. The multi-component composition allows the high-entropy oxide to have multiple active sites on the surface, which is beneficial to catalytic reactions. The chaotic arrangement of multiple components leads to lattice distortion, resulting in a unique electronic structure that is conducive to improving catalytic efficiency. Studies have shown that the multiple active sites and unique electronic structure of high-entropy oxides can optimize the adsorption and activation of reaction intermediates, thereby improving the activity of the catalytic reaction. In addition, the multi-component nature of high-entropy rare earth oxides makes them have better resistance to poisoning, and can disperse and reduce the impact of various pollutants and impurities in the flue gas on the catalyst, improving the catalyst's resistance to poisoning.

[0004] The electronic properties of high-entropy rare earth oxides promote the activity and stability of platinum / alumina catalysts, which helps to achieve efficient and stable CO removal in complex flue gas conditions. High-entropy rare earth oxides change the electronic environment of Pt, adjust its adsorption and activation ability for reactants, and thus improve the activity and selectivity of the CO oxidation reaction. At the same time, high-entropy rare earth oxides can also enhance the interaction between the support and the active component, improving the stability and resistance to poisoning of the catalyst. This allows the catalyst to maintain high-efficiency CO removal performance in complex steel sintering flue gas conditions, meeting strict environmental protection standards. Compared with traditional CO removal catalysts, high-entropy rare earth oxide-promoted platinum / alumina catalysts have significant advantages in efficiency, stability and adaptability, providing a new solution for CO removal from steel sintering flue gas. SUMMARY

[0005] The present application provides a high-entropy rare earth oxide synergistic platinum / alumina composite catalyst and a preparation method thereof, which solves the problem of few CO active sites in existing catalysts and poor CO conversion rate in complex flue gas conditions.

[0006] The application adopts the following technical scheme: a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst, the composite catalyst takes Al2O3 as a carrier, Pt as an active component, and high-entropy rare earth oxide as an active additive, and the composite catalyst comprises, in percentage by mass, 0.01-0.05% of Pt, 5-10% of high-entropy rare earth oxide, and the balance of Al2O3, wherein the high-entropy rare earth oxide is (LaCePrNdGd)O x , and the five rare earth elements each account for 0.8-2.5% of the mass of the catalyst, and the molar ratio of the rare earth element with the highest content to the rare earth element with the lowest content is not higher than 2:1.

[0007] In the application, the content of the five rare earth elements and the molar ratio of the rare earth element with the highest content to the rare earth element with the lowest content are set to form high-entropy rare earth oxide in a solid solution form.

[0008] Further, the Al2O3 is in a γ-Al2O3 crystal form, and the grain size of the γ-Al2O3 is 50-80 nm.

[0009] In the application, the γ-Al2O3 has a relatively high specific surface area as a catalyst carrier.

[0010] Further, in the high-entropy rare earth oxide, La2O3 accounts for 1.14-1.91% of the mass percentage of the composite catalyst, CeO2 accounts for 0.91-2.00% of the mass percentage of the composite catalyst, Pr6O 11 accounts for 1.05-2.00% of the mass percentage of the composite catalyst, Nd2O3 accounts for 0.98-1.97% of the mass percentage of the composite catalyst, and Gd2O3 accounts for 0.95-2.47% of the mass percentage of the composite catalyst.

[0011] A preparation method of a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst comprises the following steps: (1) Preparation of an active component gel: ethanol and water are mixed in a ratio of 4:1 to prepare an ethanol aqueous solution of chloroplatinic acid, lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate, and citric acid is added to the solution, which is stirred at 55-60°C until completely dissolved to form an active component gel; (2) Addition of a carrier: γ-Al2O3 is added to the gel solution obtained in step (1) and fully mixed in a powerful mixer, and microwave treatment is performed for 20-25 min to obtain catalyst mud, with a microwave power of 600-800 W; (3) Aging, drying, and calcination: the catalyst mud is aged, dried, and calcined to finally obtain a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst.

[0012] Further, the concentration of the chloroplatinic acid ethanol aqueous solution is 0.002-0.005 mol / L, and the concentration of the lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate and gadolinium nitrate ethanol aqueous solution is 0.2-0.5 mol / L.

[0013] Further, the molar amount of the citric acid in the step (1) is 5-10 times of the total molar amount of the six elements of platinum, lanthanum, cerium, praseodymium, neodymium and gadolinium.

[0014] Further, the catalyst mud in the step (3) is aged at 80-85℃ for 24-72 h, then dried at 110-120℃ for 24-30 h, and finally calcined at 600-800℃ for 2-3 h.

[0015] The present application has the following beneficial effects: 1. In the present application, the high-entropy rare earth oxide is added to the platinum / alumina catalyst, which helps to stabilize the crystal structure of the catalyst, so that it can maintain good structural stability in a complex flue gas environment and is not prone to phase change and structural collapse. The multiple active sites and unique electronic structure of the high-entropy oxide can optimize the adsorption and activation of intermediate species in the reaction, change the electronic environment of Pt, adjust its adsorption and activation capacity for reactants, and thus improve the activity and selectivity of the CO oxidation reaction.

[0016] 2. The multi-component property of the high-entropy rare earth oxide in the present application makes it have better resistance to poisoning, which can disperse and reduce the influence of various pollutants and impurities in the flue gas on the catalyst and improve the resistance of the catalyst to poisoning.

[0017] 3. In the present application, Pt is dispersed on the catalyst carrier in the form of multi-atomic cluster nanoparticles, the active ingredient has a large specific surface area, the number of catalytic active sites is large, the activity of the catalyst is improved, the utilization rate of Pt atoms is high, and the Pt nano cluster and the surface of the carrier form a chemical interaction, thereby improving the stability of the catalyst. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 The XRD pattern of the composite catalyst prepared in Example 1 of the present application; Figure 2 The HAADF-STEM and EDS mapping pattern of the composite catalyst prepared in Example 1 of the present application; Figure 3 The O2-TPD pattern of the composite catalyst prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0019] In order for those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application.

[0020] Example 1: A method for preparing a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst: comprising the following steps: (1) 2.049 g of chloroplatinic acid is added to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate are respectively added to a 4:1 ethanol / water mixture, and the volume is adjusted to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) 102.5 L of the chloroplatinic acid aqueous solution, 27.9 L of the lanthanum nitrate ethanol aqueous solution, 46.5 L of the cerium nitrate ethanol aqueous solution, 33.5 L of the praseodymium nitrate ethanol aqueous solution, 33.5 L of the neodymium nitrate ethanol aqueous solution, and 44.7 L of the gadolinium nitrate ethanol aqueous solution are mixed, 178.8 kg of citric acid is added, and stirring is performed at 60°C until complete dissolution; (4) 183.9 kg of γ-Al2O3 is added to the mixture obtained in the above step, and a powerful mixer is used for sufficient mixing, microwave treatment is performed for 20 min, and the microwave power is 800 W; (5) The mud obtained in the above step is aged at 80°C for 60 h, then dried at 120°C for 24 h, and then calcined at 700°C for 3 h to obtain a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst The mass fraction of each component in the catalyst of Example 1 is 0.05% of Pt, 8% of high-entropy rare earth oxide (1.14% La2O3, 2.00% CeO2, 1.43% Pr6O 11 , 1.41% Nd2O3, and 2.02% Gd2O3), and 91.95% Al2O3.

[0021] Example 2: A method for preparing a high-entropy rare earth oxide cooperated platinum / alumina composite catalyst: comprising the following steps: (1) 2.049 g of chloroplatinic acid is added to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate are respectively added to a 4:1 ethanol / water mixture, and the volume is adjusted to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) Mix 102.5 L of the aqueous chloroplatinic acid solution, 46.8 L of the aqueous lanthanum nitrate ethanol solution, 46.8 L of the aqueous cerium nitrate ethanol solution, 46.8 L of the aqueous praseodymium nitrate ethanol solution, 46.8 L of the aqueous neodymium nitrate ethanol solution, and 46.8 L of the aqueous gadolinium nitrate ethanol solution, and add 224.8 kg of citric acid, and stir at 60°C until completely dissolved; (4) Add 179.9 kg of γ-Al2O3 to the mixture obtained in the above step, and mix well using a powerful mixer, and microwave for 20 min at a microwave power of 700W; (5) Age the mud obtained in the above step at 80°C for 60 h, then dry at 120°C for 24 h, then calcine at 700°C for 3 h to obtain the high-entropy rare earth oxide promoted platinum-alumina catalyst embodiment 2.

[0022] The mass fraction of each component in the catalyst of embodiment 2 is 0.05% Pt, 10% high-entropy rare earth oxide (1.91% La2O3, 2.01% CeO2, 1.99% Pr6O 11 , 1.97% Nd2O3, and 2.12% Gd2O3), and 89.95% Al2O3.

[0023] Embodiment 3: A method for preparing a high-entropy rare earth oxide and platinum / alumina composite catalyst, comprising the following steps: (1) Add 2.049 g of chloroplatinic acid to 1 L of water to prepare a 0.005 mol / L aqueous chloroplatinic acid solution; (2) Add 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate to 4:1 ethanol / water mixture, respectively, and make up to 1 L to prepare 0.5 mol / L aqueous ethanol solutions of lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate, respectively; (3) Mix 102.5 L of the aqueous chloroplatinic acid solution, 19.9 L of the aqueous lanthanum nitrate ethanol solution, 23.4 L of the aqueous cerium nitrate ethanol solution, 29.2 L of the aqueous praseodymium nitrate ethanol solution, 23.4 L of the aqueous neodymium nitrate ethanol solution, and 22.1 L of the aqueous gadolinium nitrate ethanol solution, and add 112.4 kg of citric acid, and stir at 60°C until completely dissolved; (4) Add 189.9 kg of γ-Al2O3 to the mixture obtained in the above step, and mix well using a powerful mixer, and microwave for 20 min at a microwave power of 600W; (5) The mud obtained in the above step is aged at 80 °C for 60 h, then dried at 120 °C for 24 h, and then calcined at 700 °C for 3 h to obtain the high-entropy rare earth oxide promoted platinum-alumina catalyst of Example 3.

[0024] The mass fraction of each component in the catalyst of Example 3 is 0.05% Pt, 5% high-entropy rare earth oxide (0.81% La2O3, 1.01% CeO2, 1.24% Pr6O 11 , 0.98% Nd2O3, and 0.95% Gd2O3), and 94.95% Al2O3.

[0025] Example 4: A method for preparing a high-entropy rare earth oxide synergistic platinum / alumina composite catalyst, comprising the following steps: (1) 2.049 g of chloroplatinic acid is added to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate are added to 4:1 ethanol / water mixture, respectively, and the volume is adjusted to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) 20.5 L of chloroplatinic acid aqueous solution, 35.2 L of lanthanum nitrate ethanol aqueous solution, 21.1 L of cerium nitrate ethanol aqueous solution, 25.3 L of praseodymium nitrate ethanol aqueous solution, 31.0 L of neodymium nitrate ethanol aqueous solution, and 28.2 L of gadolinium nitrate ethanol aqueous solution are mixed, and 135.3 kg of citric acid is added, and stirred at 60 °C until completely dissolved; (4) 188.0 kg of γ-Al2O3 is added to the mixture obtained in the above step, and is fully mixed using a powerful mixer, and is treated by microwave for 20 min, with a microwave power of 800 W; (5) The mud obtained in the above step is aged at 80 °C for 60 h, then dried at 120 °C for 24 h, and then calcined at 700 °C for 3 h to obtain the high-entropy rare earth oxide promoted platinum-alumina catalyst of Example 4.

[0026] The mass fraction of each component in the catalyst of Example 4 is 0.01% Pt, 6% high-entropy rare earth oxide (1.43% La2O3, 0.91% CeO2, 1.08% Pr6O 11 , 1.30% Nd2O3, and 1.28% Gd2O3), and 93.99% Al2O3.

[0027] Example 5: A method for preparing a high-entropy rare earth oxide promoted platinum / alumina composite catalyst: comprising the following steps: (1) 2.049 g of chloroplatinic acid was added to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate were added to 4:1 ethanol / water mixture, respectively, and diluted to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) 61.5 L of chloroplatinic acid aqueous solution, 34.5 L of lanthanum nitrate ethanol aqueous solution, 34.5 L of cerium nitrate ethanol aqueous solution, 24.6 L of praseodymium nitrate ethanol aqueous solution, 41.0 L of neodymium nitrate ethanol aqueous solution, and 29.5 L of gadolinium nitrate ethanol aqueous solution were mixed, 157.7 kg of citric acid was added, and stirring was performed at 60°C until complete dissolution; (4) 186.0 kg of γ-Al2O3 was added to the mixture obtained in the above step, and a powerful mixer was used for sufficient mixing, microwave treatment was performed for 20 min, and the microwave power was 800 W; (5) The mud obtained in the above step was aged at 80°C for 60 h, then dried at 120°C for 24 h, and then calcined at 700°C for 3 h to obtain the high-entropy rare earth oxide promoted platinum / alumina catalyst of Example 5.

[0028] The mass fraction of each component in the catalyst of Example 5 was 0.03% Pt, 7% high-entropy rare earth oxide (1.40% La2O3, 1.48% CeO2, 1.05% Pr6O 11 , 1.73% Nd2O3, and 1.34% Gd2O3), and 92.97% Al2O3.

[0029] Example 6: A method for preparing a high-entropy rare earth oxide promoted platinum / alumina composite catalyst: comprising the following steps: (1) 2.049 g of chloroplatinic acid was added to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate were added to 4:1 ethanol / water mixture, respectively, and diluted to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) Mix 41.0 L of chloroplatinic acid aqueous solution, 45.2 L of lanthanum nitrate ethanol aqueous solution, 43.3 L of cerium nitrate ethanol aqueous solution, 47.0 L of praseodymium nitrate ethanol aqueous solution, 28.2 L of neodymium nitrate ethanol aqueous solution, 24.5 L of gadolinium nitrate ethanol aqueous solution, and add 180.8 kg of citric acid, and stir at 60°C until completely dissolved; (4) Add 184.0 kg of γ-Al2O3 to the mixture obtained in the above step, and mix well using a powerful mixer, and microwave for 20 min at a microwave power of 800W; (5) Age the mud obtained in the above step at 80°C for 60 h, then dry at 120°C for 24 h, then calcine at 700°C for 3 h to obtain the high-entropy rare earth oxide promoted platinum-alumina catalyst of Example 6.

[0030] The mass fraction of each component in the catalyst of Example 6 is 0.02% Pt, 8% high-entropy rare earth oxide (1.84% La2O3, 1.86% CeO2, 2.00% Pr6O 11 , 1.19% Nd2O3, and 1.11% Gd2O3), and 91.98% Al2O3.

[0031] Example 7: A method for preparing a high-entropy rare earth oxide synergistic platinum / alumina composite catalyst, comprising the following steps: (1) Add 2.049 g of chloroplatinic acid to 1 L of water to prepare a 0.005 mol / L chloroplatinic acid aqueous solution; (2) Add 216.515 g of lanthanum nitrate hexahydrate, 217.110 g of cerium nitrate hexahydrate, 217.505 g of praseodymium nitrate hexahydrate, 219.175 g of neodymium nitrate hexahydrate, and 225.680 g of gadolinium nitrate hexahydrate to 4:1 ethanol / water mixture, respectively, and make up to 1 L to prepare 0.5 mol / L lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate, and gadolinium nitrate ethanol aqueous solutions, respectively; (3) Mix 82.0 L of chloroplatinic acid aqueous solution, 33.5 L of lanthanum nitrate ethanol aqueous solution, 35.6 L of cerium nitrate ethanol aqueous solution, 46.1 L of praseodymium nitrate ethanol aqueous solution, 39.8 L of neodymium nitrate ethanol aqueous solution, and 54.5 L of gadolinium nitrate ethanol aqueous solution, and add 201.2 kg of citric acid, and stir at 60°C until completely dissolved; (4) Add 181.92 kg of γ-Al2O3 to the mixture obtained in the above step, and mix well using a powerful mixer, and microwave for 20 min at a microwave power of 800W; (5) The mud obtained in the above step is aged at 80 ℃ for 60 h, then dried at 120 ℃ for 24 h, and then the high-entropy rare earth oxide promoted platinum-alumina catalyst embodiment 7 is obtained after calcination at 700 ℃ for 3 h.

[0032] The mass fraction of each component in the catalyst of embodiment 7 is 0.04% of Pt, 9% of high-entropy rare earth oxide (1.36% of La2O3, 1.53% of CeO2, 1.96% of Pr6O 11 , 1.67% of Nd2O3 and 2.47% of Gd2O3) and 90.96% of Al2O3.

[0033] The composite catalyst prepared in embodiment one is characterized: The high-entropy rare earth oxide is a mixed oxide with a single crystal structure formed by the atomic-level solid solution of the five rare earths with cubic fluorite structure, and the cations of the rare earths randomly and orderly occupy the top corners and faces of the crystal lattice in the form of face-centered cubic close packing, and the oxygen atoms occupy the tetrahedral voids of the rare earth cations, Figure 1 From the XRD pattern, it can be seen that the catalyst mainly presents the characteristic peaks of (LaCePrNdGd)O x and the characteristic peaks of Al2O3.

[0034] From the HAADF-STEM and EDS mapping of Figure 2 , it can be seen that the HAADF-STEM photo presents that the composite catalyst is a nanoparticle with a size of 70 nm; and the EDS mapping shows that all the rare earth elements are highly uniformly distributed on the surface of the Al2O3 carrier particles of the catalyst, forming a highly random and orderly uniform high-entropy rare earth oxide.

[0035] The composite catalyst of the application introduces a high-entropy rare earth oxide additive on the basis of platinum-alumina, and such high-entropy rare earth oxide has high configurational entropy, so the structure is stable. The composition of multiple main elements makes the surface of the high-entropy oxide have rich active sites.

[0036] From the O2-TPD graph in Figure 3 , it can be seen that the low-temperature desorption α peak is the surface adsorbed oxygen, and α1, α2 and α3 are respectively the physically adsorbed O2, the chemically adsorbed O2 - and the chemically adsorbed O -; The beta peak of high-temperature desorption is lattice oxygen, and beta1 and beta2 are surface and internal lattice oxygen, respectively. The alpha2 peak is mainly from the adsorption signal of oxygen vacancies, accounting for as high as 65%. Through theoretical calculation, it is proved that the f-electron orbital energy of rare earth elements is widened in the chaotic arrangement of multi-principal elements, which promotes the energy level splitting of the d-orbital of Pt, and at the same time improves the activation ability of the catalyst to molecular oxygen and the adsorption ability of CO. In addition, the variable valence rare earth elements and oxygen vacancies on the surface of high-entropy rare earth oxides can effectively promote the decomposition and conversion of pollutants such as NOx, ammonium bisulfate, etc., so that the catalyst can maintain good activity and stability under complex flue gas conditions containing multiple pollutants.

[0037] Comparative Example 1: Commercially available Pt / Al2O3 catalyst, the mass fraction of Pt is 0.05%.

[0038] Comparative Example 2: Pt-containing CO oxidation removal catalyst used in a certain steel sintering unit.

[0039] The catalysts in the above examples and comparative examples 1-2 were evaluated for CO oxidation removal performance using simulated flue gas. Under typical flue gas conditions: CO concentration is 5000 mg / Nm 3 , SO2 concentration is 1000 mg / Nm 3 , NO2 concentration is 500 mg / Nm 3 , O2 concentration is 10%, H2O is 5%, N2 is balance gas, GHSV = 18000 h -1 . After the sample was stabilized in the flue gas for 24 h, the test was carried out, and the test results are as follows: Table 1 CO conversion rate of composite catalyst at different temperatures As can be seen from Table 1, compared with Comparative Examples 1 and 2, the catalysts in Examples 1-7 have much higher CO oxidation activity than conventional catalysts in the temperature range of 100-200 ℃, and maintain very high stability in flue gas containing up to 1000 mg / Nm 3 of sulfur and up to 500 mg / Nm 3 of NOx, and can still maintain very high conversion efficiency after 24 h of reaction, having good sulfur resistance.

Claims

1. A high-entropy rare earth oxide co-supported platinum / alumina composite catalyst, characterized in that: The composite catalyst takes Al2O3 as a carrier, Pt as an active component, and high-entropy rare earth oxide as an active additive, and each component in the composite catalyst includes 0.01-0.05% of Pt, 5-10% of high-entropy rare earth oxide, and the balance of Al2O3 in terms of mass percentage, and the high-entropy rare earth oxide is (LaCePrNdGd)O x , five rare earth elements each account for 0.8-2.5% of the mass of the catalyst, and the molar ratio of the rare earth element with the highest content to the rare earth element with the lowest content is not higher than 2:

1.

2. The high-entropy rare earth oxide co-supported platinum / alumina composite catalyst of claim 1, wherein: The Al2O3 crystal form is γ-Al2O3, and the grain size of the γ-Al2O3 is 50-80 nm.

3. The high-entropy rare earth oxide co-supported platinum / alumina composite catalyst of claim 1, wherein: The high-entropy rare earth oxide has La2O3 accounting for 1.14-1.91% of the mass percentage of the composite catalyst, CeO2 accounting for 0.91-2.00% of the mass percentage of the composite catalyst, Pr6O 11 accounting for 1.05-2.00% of the mass percentage of the composite catalyst, Nd2O3 accounting for 0.98-1.97% of the mass percentage of the composite catalyst, and Gd2O3 accounting for 0.95-2.47% of the mass percentage of the composite catalyst.

4. The method for preparing high-entropy rare earth oxide composite catalysts synergized with platinum / alumina according to any one of claims 1-3, characterized in that: The method comprises the following steps: (1) Preparation of active component gel: chloroplatinic acid, lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate and gadolinium nitrate are mixed in ethanol and water in a certain proportion, wherein the proportion of ethanol and water is 4:1, and citric acid is added and stirred at 55-60°C until completely dissolved to form an active component gel; (2) Adding carrier: γ-Al2O3 is added to the gel solution obtained in step (1) and fully mixed in a powerful mixer, and microwave treatment is performed for 20-25 min to obtain catalyst mud, and the microwave power is 600-800 W; (3) Aging, drying and calcination: the catalyst mud is aged, dried and calcined to finally obtain a high-entropy rare earth oxide synergistic platinum / alumina composite catalyst.

5. The method of claim 4, wherein the method comprises: (a) mixing the high-entropy rare earth oxide and the platinum / alumina catalyst; and (b) calcining the mixture of step (a) at a temperature of 400-800 °C for 1-5 hours. The concentration of the chloroplatinic acid ethanol solution is 0.002-0.005 mol / L, and the concentration of the lanthanum nitrate, cerium nitrate, praseodymium nitrate, neodymium nitrate and gadolinium nitrate ethanol solution is 0.2-0.5 mol / L.

6. The method for preparing the high-entropy rare earth oxide synergistic platinum / alumina composite catalyst according to claim 4, characterized in that: The molar amount of citric acid in step (1) is 5-10 times the total molar amount of platinum, lanthanum, cerium, praseodymium, neodymium and gadolinium.

7. The method for preparing the high-entropy rare earth oxide synergistic platinum / alumina composite catalyst according to claim 4, characterized in that: In step (3), the catalyst mud is aged at 80-85°C for 24-72 h, then dried at 110-120°C for 24-30 h, and finally calcined at 600-800°C for 2-3 h.

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