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The size of precious metal catalysts plays an important role in their activity, and inhibiting precious metal aggregation or even sintering is a major challenge in practical industrial applications. Herein, the physical limitation of fibrous mesoporous silica (KCC-1) and Pt–CeO2 interaction of CeO2 nanoislands were designed and used to inhibit the size of Pt particles, thereby improving their intrinsic activity and thermal stability. With the introduction of CeO2 nanoislands, the turnover frequency (TOF) value of the Pt–CeO2/KCC-1 catalyst for propane-catalyzed combustion at 210 °C was 1.5 times that of Pt/KCC-1 and 5.6 times that of Pt/CeO2. Moreover, after aging at 800 °C, Pt–CeO2/KCC-1 showed enhanced thermal stability compared with Pt/KCC-1 due to the smaller change in the Pt size. Through comprehensive characterization and research of the reaction mechanism, the results indicate that due to the Pt–CeO2 interaction, the Pt species were confined to the middle of the CeO2 nanoisland, which was further separated by fiber sheets of KCC-1, to advance the activity and thermal stability of the catalyst. The strategy of the nanoisland in this paper provides guidance for designing better catalysts for other harsh reaction conditions. [ABSTRACT FROM AUTHOR]

Ce-based selective catalytic reductions with an NH3 (NH3-SCR) catalyst have emerged as a focal point in denitrification catalyst research. However, the correlation between the structural characteristics of Ce-based catalysts and the influence of CeO2 nanoparticle size on SO2 resistance remains unclear. CeO2 nanospheres with different sizes of less than 10 nm were synthesized, and a series of supported CeO2/SBA-15 catalysts were prepared according to the 10 nm pore size of SBA-15. These catalysts were used to explore the influence of the size of the CeO2 nanospheres on these catalysts, specifically on their SO2 resistance in NH3-SCR reactions. With the increase in size, their SO2 resistance became stronger. The results of NH3-TPD, H2-TPR, and XPS indicated that the catalyst with the largest particle size had the lowest adsorption of SO2, which was attributed to more acid sites and a mutual effect between Si and Ce, resulting in the best SO2 resistance. It was also observed that there was less sulfate deposition on the catalyst by thermogravimetric analysis. In situ DRIFTs revealed that after SO2 poisoning, the NH3-SCR reaction on the catalyst predominantly follows the E-R mechanism. This study offers recommendations for the development of Ce-based SO2-resistant NH3-SCR catalysts, specifically focusing on the synthesis and interaction of nanomaterials. [ABSTRACT FROM AUTHOR]

NOx is a common atmospheric pollutant, and NH3‐SCR technology efficiently purifies it. CeCuOx binary‐oxide nanoparticles were synthesized and loaded onto acid MCM‐49 molecular sieve with a large specific surface area to increase acid sites and disperse active sites of the catalyst. The optimized 35 % CeCu/MCM‐49 catalyst effectively purified over 80 % of NOx in the temperature range of 200–500 °C and demonstrated excellent resistance to alkali metals, such as K, Na, and Ca. Even after K poisoning, it still removed over 80 % of NOx in the range of 200–450 °C. Various characterization methods, including XRD, FT‐IR, TEM, and N2 isotherm adsorption‐desorption tests, confirmed the structure of the catalyst remained intact after poisoning with no substance change, nor agglomeration of nanoparticles. NH3‐TPD and H2‐TPR confirmed that the catalyst had effective acidity and redox capacity that were not affected by alkali metals. In‐situ DRIFTs showed that the catalytic reaction predominant mechanism shifted from L−H to E−R mechanism after poisoning. This study provides valuable insights into the development of high‐performance Ce‐based NH3‐SCR catalysts with alkali metal resistance. [ABSTRACT FROM AUTHOR]

Reducing pollution and carbon emissions is an important step toward peaking CO2 emissions before 2030 and reaching carbon neutrality before 2060, and heavy diesel vehicle pollution, particularly nitrogen oxides (NOx) emissions, is an essential part. Cu-SAPO-34 is a CHA-type small pore molecular sieve with excellent ammonia (NH3) selective catalytic reduction (NH3-SCR) catalytic activity, but it cannot be stored or applied because of severe degradation caused by low-temperature hydrothermal aging. To improve the hydrothermal stability, TiO2 was coated on the surface of Cu-SAPO-34 by the ALD method to form a uniform nanolayer. Though this ultrathin TiO2 nanolayer has little effect on NH3-SCR catalytic activity of Cu-SAPO-34, the resistance to low-temperature hydrothermal aging in liquid water at 80°C for 24 h has greatly been improved. A study carried out by SEM, XRD, NH3-TPD, and EPR, showed that the ultra-thin TiO2 nanolayers were covered uniformly and hydrolysis of frameworks silicon and the migration of Cu2+ was retarded. This method has some implications for the future preparation of highly robust Cu-SAPO-34 catalysts for industrial applications. This research could inspire the development of highly robust Cu-SAPO-34 catalysts to control the NOx emissions from diesel engines. [ABSTRACT FROM AUTHOR]