Nano island-shaped cerium oxide loaded palladium-based catalyst as well as preparation method and application thereof

Abstract

The invention relates to the technical field of catalysts, in particular to a nano island-shaped cerium oxide loaded palladium-based catalyst and a preparation method and application thereof, and the nano island-shaped cerium oxide loaded palladium-based catalyst comprises a carrier, an active oxygen carrier and active metal, the carrier is silicon oxide (SiO2) or aluminum oxide (Al2O3), and the active oxygen carrier is element-doped cerium oxide-based nanoparticles; the element-doped cerium oxide-based nanoparticles are in an isolated island shape on the surface of the carrier. The cerium oxide nano-particles (cerium oxide nano-islands) with high density and isolated island morphology are synthesized on the surface of the carrier, so that precious metal particles can be better dispersed and stabilized, and agglomeration is inhibited.

Description

Technical Field

[0001] This invention relates to the field of catalyst technology, specifically to a nano-island cerium oxide-supported palladium-based catalyst, its preparation method, and its application. Background Technology

[0002] Carbon monoxide (CO) and methane (CH4) are not only significant greenhouse gases, but their emission sources are widely distributed across energy, industry, and transportation sectors, posing a continuous threat to the atmospheric environment. Meanwhile, tritium (T2), a β-radioactive nuclide, can induce cellular DNA damage, increase the risk of cancer, and damage internal organs after entering the human body; therefore, the treatment of tritium-containing waste gas is equally urgent. Among the technologies for controlling these pollutants, catalytic oxidation has become a recognized effective approach due to its advantages of high efficiency, wide applicability, and low secondary pollution. Currently, palladium-based catalysts are the most widely used catalytic materials in this field; however, they often face problems such as easy sintering of active components, insufficient resistance to poisoning, and poor long-term operational stability during CO and CH4 oxidation. In tritium catalytic oxidation applications, existing catalysts generally suffer from high activation temperatures, low activity at low temperatures, and poor stability, making it difficult to meet the requirements for efficient removal under mild conditions. Summary of the Invention

[0003] The purpose of this invention is to provide a nano-island cerium oxide supported palladium-based catalyst, its preparation method and application, to solve the technical problems that existing catalysts generally have defects such as high activation temperature, low low-temperature activity and poor stability, which make it difficult to meet the requirements of efficient removal under mild conditions.

[0004] This invention discloses a nano-island-shaped cerium oxide supported palladium-based catalyst, comprising a support, an active oxygen carrier, and an active metal; The carrier is silicon oxide (SiO2) or aluminum oxide (Al2O3), and the active oxygen carrier is element-doped cerium oxide-based nanoparticles. The element-doped cerium oxide-based nanoparticles exhibit an isolated island / reef morphology on the carrier surface.

[0005] By synthesizing cerium oxide nanoparticles (cerium oxide nanoislands) with high density and isolated island morphology on the surface of a carrier, noble metal particles can be better dispersed and stabilized, and aggregation can be inhibited.

[0006] By adding other auxiliary elements to cerium oxide nanoisland particles, element-doped cerium oxide-based nanoislands are formed, which have excellent oxygen storage and release capabilities and superior oxidation activities for tritium (T2), carbon monoxide (CO) and methane (CH4).

[0007] Furthermore, the element-doped cerium oxide-based nanoparticles are synthesized via an electrostatic adsorption-anchoring co-impregnation-high-temperature calcination method. Furthermore, the doping element of the element-doped cerium oxide-based nanoparticles is at least one selected from La, Pr, Zr, Nd, Ga, In, Co, Mn, and Cr.

[0008] Furthermore, the active metal is a highly dispersed particle containing Pd element.

[0009] By using single-metal Pd to form alloy particles with other noble metals, it exhibits better oxidation performance for tritium (T2), carbon monoxide (CO), and methane (CH4).

[0010] Furthermore, the highly dispersed particles containing Pd are monodisperse Pd atoms, Pd clusters, or alloy particles formed by Pd and noble metals.

[0011] Furthermore, the precious metal is at least one of Pt, Rh, Au, Ru, or Ir.

[0012] Furthermore, based on mass percentage, with the catalyst mass as 100%, the content of active oxygen carrier is 4.0% to 20.0%; And / or, the active metal content is 0.05% to 1.0%.

[0013] A method for preparing a nano-island-shaped cerium oxide-supported palladium-based catalyst includes the following steps: S1. Prepare the carrier suspension, the active oxygen carrier precursor salt solution, and the active metal precursor salt solution; S2. The active oxygen carrier precursor salt solution is added dropwise to the carrier suspension while stirring. Then, ammonia water is added dropwise to adjust the pH value. The mixture is stirred at room temperature, centrifuged, and dried to obtain a solid powder. S3. The solid powder prepared in step S2 is ground and then calcined in air to obtain a carrier powder loaded with active oxygen carrier; S4. Disperse the active oxygen carrier powder in deionized water and add dilute hydrochloric acid to adjust the pH of the suspension. Add dilute hydrochloric acid to adjust the pH of the active metal precursor aqueous solution, and then add it dropwise to the active oxygen carrier powder suspension while stirring at room temperature. S5. After stirring, dry in a water bath. The resulting solid powder is then ground and calcined in air to obtain the final product. The active oxygen carrier is element-doped cerium oxide-based nanoparticles, and the active oxygen carrier has an isolated island / reef morphology on the surface of the carrier.

[0014] Furthermore, the method for preparing the carrier suspension involves adding SiO2 or Al2O3 powder to deionized water and stirring to form a carrier suspension.

[0015] Furthermore, the method for preparing the active oxygen carrier precursor salt solution involves dissolving Ce(NO3)3·6H2O or a salt selected from La(NO3)3·6H2O, Pr(NO3)3·6H2O, ZrO(NO3)2·xH2O, Nd(NO3)3·xH2O, Ga(NO3)3·xH2O, In(NO3)2·xH2O, Co(NO3)2·6H2O, Mn(NO3)2·xH2O, and Cr(NO3)3·9H2O in deionized water to prepare the active oxygen carrier precursor salt solution.

[0016] Furthermore, the method for preparing the active metal precursor salt solution involves dissolving PdCl2 or a salt of PtCl4, RhCl3, HAuCl3, RuCl3, or IrCl3 in deionized water to prepare the active metal precursor salt solution.

[0017] Furthermore, in step S2, the pH value is adjusted to 8-10, preferably 9, and the stirring time is 6-18 hours, preferably 12 hours.

[0018] Furthermore, the air calcination temperature in step S3 is 400–800°C, preferably 600°C, and the calcination time is 1–6 hours, preferably 3 hours.

[0019] Furthermore, in step S4, the pH value of the suspension is adjusted to 2-4, preferably 3, the pH value of the aqueous solution of the active metal precursor is adjusted to 2-4, preferably 3, and the stirring time at room temperature is 6-18 hours, preferably 12 hours.

[0020] Furthermore, in step S5, the water bath drying temperature is 70–90°C, preferably 80°C, the drying time is 6–18 hours, preferably 12 hours, the air calcination temperature is 400–800°C, preferably 400°C, and the air calcination time is 2–8 hours, preferably 4 hours.

[0021] The application of a nano-island cerium oxide-supported palladium-based catalyst for the efficient removal of carbon monoxide (CO), methane (CH4) and tritium (T2).

[0022] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention constructs high-density, isolated, and dispersed cerium oxide nanoparticles on a support surface through a controlled synthesis strategy, significantly enhancing the dispersion of the active metal and its strong interaction with the support. This unique structure not only provides abundant active sites but also effectively improves the catalytic oxidation performance of the catalyst for CO, CH4, and T2 through the synergistic effect of the support and the metal. 2. This invention achieves high-density and isolated dispersion of reactive oxygen carrier nanoparticles exhibiting an island-reef morphology, and high dispersion of active noble metals on the reactive oxygen carrier nanoislands, significantly inhibiting the migration and aggregation of the loaded active metals between the islands. Furthermore, due to the enhanced interfacial interaction between the highly dispersed reactive oxygen carrier nanoparticles and the highly dispersed active noble metals, the catalyst simultaneously possesses good activity and stability. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.

[0024] Example 1 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.1009 g of Ce(NO3)3 6H₂O (purity ≥99.95%) was dissolved in 50 ml of deionized water and added dropwise to the SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60℃ for 12 h, ground, and then calcined in air at 400℃ for 12 h to obtain 4% CeO₂. x / SiO2 nano-island support. 1g of support powder was dispersed in 70ml of deionized water and sonicated for 30min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. 50mL of a palladium precursor aqueous solution (containing 0.0025g Pd) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12h. After stirring, the solution was evaporated to dryness in an 80℃ water bath. The resulting solid powder was dried at 60℃ for 12h, ground, and then calcined in air at 400℃ for 12h. The resulting catalyst was 0.25% Pd / 4% CeO2. x / SiO2-400-400.

[0025] Example 2 Take 1g of SiO2 powder (specific surface area 300 m2) (g-1) was dispersed in 100 ml of deionized water (18.25 Ω) and sonicated for 30 min to form a homogeneous mixture. 0.2271 g of Ce(NO3)3 was then taken. 6H₂O (purity ≥99.95%) and 0.0405 g Pr(NO₃)₃·6H₂O (purity ≥99.99%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 600 °C for 12 h to obtain 12% Pr-CeO. x A SiO2 nano-island support was used, with CeO2:Pr2O3 = 3:1 (mass ratio). 1 g of support powder was dispersed in 70 mL of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. A 50 mL aqueous solution of palladium-platinum precursor (containing 0.00372 g Pt and 0.00628 g Pd, Pd:Pt = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80 °C water bath. The resulting solid powder was dried at 60 °C for 12 h, ground, and then calcined in air at 600 °C for 12 h. The resulting catalyst was 1% Pd3Pt1 / 12% Pr-CeO2. x / SiO2-600-600.

[0026] Example 3 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.3785 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0668 g La(NO₃)₃·6H₂O (purity ≥99.999%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 800 °C for 12 h to obtain 20% La-CeO₂. xA SiO2 nano-island support was used, with CeO2:La2O3 = 3:1 (mass ratio). 1 g of support powder was dispersed in 70 mL of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. A 50 mL aqueous solution of palladium-rhodium precursors (containing 0.0113 g Pd and 0.0037 g Rh, Pd:Rh = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80 °C water bath. The resulting solid powder was dried at 60 °C for 12 h, ground, and then calcined in air at 800 °C for 12 h. The resulting catalyst was 1.5% Pd3Rh1 / 20% La-CeO2. x / SiO2-800-800.

[0027] Example 4 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.0757 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0189 g ZrO(NO₃)₂·xH₂O (purity ≥99.5%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 600 °C for 12 h to obtain 4% Zr-CeO. x A SiO2 nano-island support was used, with CeO2:ZrO2 = 3:1 (mass ratio). 1 g of support powder was dispersed in 70 mL of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. A 50 mL aqueous solution of palladium precursor (containing 0.0015 g Pd and 0.001 g Au, Pd:Au = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80 °C water bath. The resulting solid powder was dried at 60 °C for 12 h, ground, and then calcined in air at 600 °C for 12 h. The resulting catalyst was 0.25% Pd3Au1 / 4% Zr-CeO2. x / SiO2-600-600.

[0028] Example 5 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.2271 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0392 g Nd(NO₃)₂·xH₂O (purity ≥99.99%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 800 °C for 12 h to obtain 12% Nd-CeO. x A SiO2 nano-island support was used, with CeO2:Nd2O3 = 3:1 (mass ratio). 1 g of support powder was dispersed in 70 mL of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. A 50 mL aqueous solution of a palladium-iridium precursor (containing 0.0062 g Pd and 0.0038 g Ir, Pd:Ir = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80 °C water bath. The resulting solid powder was dried at 60 °C for 12 h, ground, and then calcined in air at 800 °C for 12 h. The resulting catalyst was 1% Pd3Ir1 / 12% Nd-CeO2. x / SiO2-800-800.

[0029] Example 6 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.3785 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.1001 g Ga(NO₃)₃·xH₂O (purity ≥99.99%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 400 °C for 12 h to obtain 20% Ga-CeO₂. xA SiO2 nano-island support was used, with CeO2:Ga2O3 = 3:1 (mass ratio). 1 g of support powder was dispersed in 70 mL of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. A 50 mL aqueous solution of palladium-ruthenium precursor (containing 0.0114 g Pd and 0.0036 g Ru, Pd:Ru = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80 °C water bath. The resulting solid powder was dried at 60 °C for 12 h, ground, and then calcined in air at 400 °C for 12 h. The resulting catalyst was a 1.5% Pd3Ru1 / 12% Ga-CeO2 catalyst. x / SiO2-400-400.

[0030] Example 7 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.0757 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0108 g In(NO₃)₃·xH₂O (purity ≥99.999%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 800 °C for 12 h to obtain 4% In-CeO. x / SiO2 nano-island support. 1 g of support powder was dispersed in 70 ml of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to approximately 3. 50 mL of a palladium precursor aqueous solution (containing 0.015 g Pd) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH of the solution to approximately 3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the solution was evaporated to dryness in an 80℃ water bath. The resulting solid powder was dried at 60℃ for 12 h, ground, and then calcined in air at 400℃ for 12 h. The resulting catalyst was 1.5% Pd / 4% In-CeOx / SiO2-800-400.

[0031] Example 8 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.2271 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0363 g Co(NO₃)₂·6H₂O (purity ≥99.9%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 400 °C for 12 h to obtain 12% Co-CeO. x / SiO2 nano-island support. 1g of support powder was dispersed in 70ml of deionized water and sonicated for 30min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to ≈3. 50mL of a palladium-platinum precursor aqueous solution (containing 0.0016g Pd and 0.001g Pt, Pd:Pt = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to ≈3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12h. After stirring, the solution was evaporated to dryness in an 80℃ water bath. The resulting solid powder was dried at 60℃ for 12h, ground, and then calcined in air at 800℃ for 12h. The resulting catalyst was 0.25% Pd3Pt1 / 12% Co-CeOx / SiO2-400-800.

[0032] Example 9 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.3785 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.1453g Mn(NO₃)₂·xH₂O (purity ≥99.99%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60℃ for 12 h, ground, and then calcined in air at 600℃ for 12 h to obtain a 20% Mn-CeOx / SiO₂ nanoisland carrier. 1g of the carrier powder was dispersed in 70 ml of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to ≈3. 50 mL of a palladium-rhodium precursor aqueous solution (containing 0.0018 g Pd and 0.0006 g Rh, Pd:Rh = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH of the solution to ≈3. The precursor aqueous solution was added dropwise to the suspension and stirred at room temperature for 12 hours. After stirring, the solution was evaporated to dryness in an 80°C water bath. The resulting solid powder was dried at 60°C for 12 hours, ground, and then calcined in air at 800°C for 12 hours. The resulting catalyst was 0.25% Pd3Rh1 / 20%Mn-CeOx / SiO2-600-800.

[0033] Example 10 Take 1g of SiO2 powder (specific surface area 300 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.0757 g of Ce(NO3)3 6H₂O (purity ≥99.95%) and 0.0216 g Cr(NO₃)₃·9H₂O (purity ≥99.99%) were dissolved in 50 ml of deionized water and added to a SiO₂ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 8-9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60 °C for 12 h, ground, and then calcined in air at 600 °C for 12 h to obtain 4% Cr-CeO₂. x / SiO2 nanoisland support. 1g of support powder was dispersed in 70ml of deionized water and sonicated for 30min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to ≈3. 50mL of a palladium precursor aqueous solution (containing 0.0093g Pd and 0.0057g Au, Pd:Au = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH to ≈3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12h. After stirring, the solution was evaporated to dryness in an 80℃ water bath. The resulting solid powder was dried at 60℃ for 12h, ground, and then calcined in air at 800℃ for 12h. The resulting catalyst was 1.5% Pd3Au1 / 4% Cr-CeOx / SiO2-600-800.

[0034] Example 11 Take 1g of Al2O3 powder (specific surface area 200 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.3028 g of Ce(NO3)3 6H₂O (purity ≥99.95%) was dissolved in 50 ml of deionized water and added to an Al₂O₃ suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60℃ for 12 h, ground, and then calcined in air at 600℃ for 12 h to obtain a 12% CeOx / SiO₂ nanoisland support. 1 g of the support powder was dispersed in 70 ml of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to ≈3. 50 mL of a palladium-iridium precursor aqueous solution (containing 0.0062 g Pd and 0.0038 g Ir, Pd:Ir = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH of the solution to ≈3. The precursor aqueous solution was added dropwise to the suspension, and the mixture was stirred at room temperature for 12 h. After stirring, the mixture was evaporated to dryness in an 80℃ water bath. The resulting solid powder was dried at 60℃ for 12 hours, ground, and then calcined in air at 600℃ for 12 hours. The resulting catalyst was 1% Pd3Ir1 / 12% CeO. x / SiO2-600-600.

[0035] Example 12 Take 1g of Al2O3 powder (specific surface area 200 m²) 2 g -1 Disperse the Ce(NO3)3 in 100 ml of deionized water (18.25 Ω) and sonicate for 30 min to form a homogeneous mixture. Take 0.3785 g of Ce(NO3)3 6H2O (purity ≥99.95%) and 0.0947g ZrO(NO3)2·xH2O (purity ≥99.5%) were dissolved in 50 ml of deionized water and added to an Al2O3 suspension under vigorous stirring. Ammonia was added dropwise to adjust the pH of the suspension to 9, and the mixture was stirred at room temperature for 12 h. The solid product was separated by centrifugation, dried at 60℃ for 12 h, ground, and then calcined in air at 400℃ for 12 h to obtain a 20% Zr-CeOx / SiO2 nanoisland support. 1g of the support powder was dispersed in 70 ml of deionized water and sonicated for 30 min to form a homogeneous mixture. Dilute hydrochloric acid was added dropwise to adjust the pH of the suspension to ≈3. 50 mL of a palladium-ruthenium precursor aqueous solution (containing 0.0019 g Pd and 0.0006 g Ru, Pd:Ru = 3:1 molar ratio) was prepared, and dilute hydrochloric acid was added dropwise to adjust the pH of the solution to ≈3. The precursor aqueous solution was added dropwise to the suspension and stirred at room temperature for 12 hours. After stirring, the solution was evaporated to dryness in an 80°C water bath. The resulting solid powder was dried at 60°C for 12 hours, ground, and then calcined in air at 800°C for 12 hours. The resulting catalyst was 0.25% Pd3Ru1 / 20% Zr-CeOx / SiO2-400-800.

[0036] Catalyst performance testing The catalysts prepared in Examples 1-12 were placed in micro-fixed-bed reactors to test their catalytic performance. Before testing, the reactors were pretreated with argon gas for 1 h. The feed gases were CH4 at a flow rate of 0.25 mL / min, oxygen at a flow rate of 5 mL / min, and nitrogen at a flow rate of 19.75 mL / min. The volume hourly space velocity (VHSV) was 30,000 h⁻¹. -1 The catalyst dosage was 100 mg, and the pressure was atmospheric pressure. The test results are detailed in Table 1.

[0037] Table 1. Test results of the catalytic combustion performance of the catalyst of the present invention for CH4.

[0038] Note: T 10 The temperature at which the target substance is converted by 10%.

[0039] T 90 The temperature at which 90% of the target substance is converted.

[0040] The catalysts prepared in Examples 1-12 were placed in micro-fixed-bed reactors to test their catalytic performance. No pretreatment was required before testing. The feed gas consisted of 0.6 mL / min CO, 12 mL / min oxygen, 47.4 mL / min argon, and 4.2 vol% water vapor. The space velocity (HV) was 60,000 h⁻¹. -1 The catalyst dosage was 50 mg, and the pressure was atmospheric pressure. The test results are detailed in Table 2.

[0041] Table 2. Test results of the catalytic combustion performance of the catalyst of the present invention for CO.

[0042] Note: T 10 The temperature at which the target substance is converted by 10%.

[0043] T 99 The temperature at which 99% of the target substance is converted.

[0044] The catalysts prepared in Examples 1-12 were placed in microreactors to test their catalytic performance. No pretreatment was required before the test. The feed gas was a tritium-air mixture at a flow rate of 50 mL / min, the catalyst dosage was 1 g, the reaction temperature was -10 to 30 °C, and the pressure was atmospheric pressure. The test results are detailed in Table 3.

[0045] Reference 3: Test results of the catalytic T2 oxidation performance of the catalyst of this invention

Claims

1. A nano-island-shaped cerium oxide-supported palladium-based catalyst, characterized in that: Including carriers, active oxygen carriers, and active metals; The carrier is silicon oxide or aluminum oxide, and the active oxygen carrier is element-doped cerium oxide-based nanoparticles. The element-doped cerium oxide-based nanoparticles exhibit an isolated island / reef morphology on the carrier surface.

2. The nano-island cerium oxide-supported palladium-based catalyst according to claim 1, characterized in that: The element-doped cerium oxide-based nanoparticles were synthesized via an electrostatic adsorption-anchored co-impregnation-high temperature calcination method. And / or, the element doping cerium oxide-based nanoparticles are at least one of La, Pr, Zr, Nd, Ga, In, Co, Mn, and Cr; And / or, the active metal is a highly dispersed particle containing Pd element.

3. The nano-island cerium oxide-supported palladium-based catalyst according to claim 2, characterized in that: The highly dispersed particles containing Pd are monodisperse Pd atoms, Pd clusters, or alloy particles formed by Pd and noble metals.

4. The nano-island cerium oxide-supported palladium-based catalyst according to claim 3, characterized in that: The precious metal is at least one of Pt, Rh, Au, Ru, or Ir.

5. A nano-island-shaped cerium oxide-supported palladium-based catalyst according to any one of claims 1-4, characterized in that: By mass percentage, with the catalyst mass as 100%, the content of active oxygen carrier is 4.0% to 20.0%; And / or, the active metal content is 0.05% to 1.0%.

6. A method for preparing a palladium-based catalyst supported on cerium oxide nano-island structures, characterized in that: Includes the following steps: S1. Prepare the carrier suspension, the active oxygen carrier precursor salt solution, and the active metal precursor salt solution; S2. The active oxygen carrier precursor salt solution is added dropwise to the carrier suspension while stirring. Then, ammonia water is added dropwise to adjust the pH value. The mixture is stirred at room temperature, centrifuged, and dried to obtain a solid powder. S3. The solid powder prepared in step S2 is ground and then calcined in air to obtain a carrier powder loaded with active oxygen carrier; S4. Disperse the active oxygen carrier powder in deionized water and add dilute hydrochloric acid to adjust the pH of the suspension. Add dilute hydrochloric acid to adjust the pH of the active metal precursor aqueous solution, and then add it dropwise to the active oxygen carrier powder suspension while stirring at room temperature. S5. After stirring, dry in a water bath. The resulting solid powder is then ground and calcined in air to obtain the final product. The active oxygen carrier is element-doped cerium oxide-based nanoparticles, and the active oxygen carrier has an isolated island / reef morphology on the surface of the carrier.

7. The method for preparing a nano-island-shaped cerium oxide-supported palladium-based catalyst according to claim 6, characterized in that: The method for preparing the carrier suspension is to add SiO2 or Al2O3 powder to deionized water and stir to form a carrier suspension. And / or, the method for preparing the active oxygen carrier precursor salt solution is to dissolve Ce(NO3)3·6H2O or a salt thereof and one of La(NO3)3·6H2O, Pr(NO3)3·6H2O, ZrO(NO3)2·xH2O, Nd(NO3)3·xH2O, Ga(NO3)3·xH2O, In(NO3)2·xH2O, Co(NO3)2·6H2O, Mn(NO3)2·xH2O, Cr(NO3)3·9H2O in deionized water to prepare the active oxygen carrier precursor salt solution; And / or, the method for preparing the active metal precursor salt solution is to dissolve PdCl2 or a salt of PtCl4, RhCl3, HAuCl3, RuCl3, IrCl3 in deionized water to prepare the active metal precursor salt solution.

8. The method for preparing a nano-island-shaped cerium oxide-supported palladium-based catalyst according to claim 6, characterized in that: In step S2, the pH value is adjusted to 8-10, and the stirring time is 6-18 hours. And / or, the air calcination temperature in step S3 is 400-800°C, and the calcination time is 1-6 hours; And / or, in step S4, the pH of the suspension is adjusted to 2-4, the pH of the aqueous solution of the active metal precursor is adjusted to 2-4, and the stirring time at room temperature is 6-18 hours. And / or, in step S5, the water bath drying temperature is 70-90°C, the drying time is 6-18 hours, the air calcination temperature is 400-800°C, and the air calcination time is 2-8 hours.

9. The method for preparing a nano-island-shaped cerium oxide-supported palladium-based catalyst according to claim 8, characterized in that: The pH value is adjusted to 9 in step S2; And / or, the air calcination temperature in step S3 is 600°C and the calcination time is 3 hours; And / or, in step S4, the pH of the suspension is adjusted to 3, the pH of the active metal precursor aqueous solution is adjusted to 3, and the stirring time at room temperature is 12 hours. And / or, in step S5, the water bath drying temperature is 80°C, the drying time is 12 hours, the air calcination temperature is 400°C, and the air calcination time is 4 hours.

10. The application of the nano-island cerium oxide-supported palladium-based catalyst according to any one of claims 1-5, or the catalyst prepared by the method for preparing the nano-island cerium oxide-supported palladium-based catalyst according to any one of claims 6-9, characterized in that: It is used for the simultaneous removal of carbon monoxide, methane, and tritium.

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