Cai-Hao Wen, Lin-Ya Xu, Yao-Dong Hao, Qian Zhou, Yi-Wei Xian, Mao-Di Wang*, Wei Tan*, Lin Dong, Jian Chen*, Meng-Fei Luo and Qi-Hua Yang,
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引用次数: 0
Abstract
Catalytic combustion represents one of the most efficient technologies for light-alkane volatile organic compound abatement. However, the reaction mechanisms over heterogeneous catalysts remain controversial, which significantly hinders the rational design of highly efficient and stable catalysts. In this work, it is found that the T50 (the temperature at which propane conversion reached 50%) of Pt/MoO3 (220 °C) is much lower than that of Pt/CeO2 (T50 = 320 °C) in propane combustion (C3H8 + O2 → CO2 + H2O), indicating the possibility of synergistic catalysis occurring between Pt and MoO3 sites. Based on a hybrid catalysis system composed of physically mixed MoO3 and Pt/CeO2 (denoted as Pt/CeO2+MoO3), the critical roles of the acid site from MoO3 for propane activation and the Pt site for oxygen-activation have been originally investigated in propane oxidation, even though Pt and MoO3 sites are spatially separated. The results of the kinetic study, in situ diffuse reflectance infrared Fourier transform spectra of propane combustion, and X-ray photoelectron spectra experiments sufficiently evidenced that propane preferentially absorbs on the MoO3 surface, and the oxygen spillover from Pt sites to the MoO3 surface further facilitates the oxidation of propane. Density functional theory calculations reveal that Pt sites exhibit stronger O2 adsorption, while the synergy between five-coordinated and four-coordinated Mo sites enables MoO3 with an enhanced propane activation capability. That is, MoO3 offers important extra sites for propane activation, effectively avoiding the competitive adsorption between oxygen and propane on the Pt sites. A large distance between MoO3 and Pt sites negatively impacts catalytic activity. Additionally, via construction of defective MoO3 containing more surface acid sites, it is disclosed that stronger surface acidity of MoO3 significantly promotes the catalytic performance of Pt sites and MoO3 sites. This work sheds light on the reaction mechanism of light-alkane oxidation over the metal oxide-supported Pt catalyst.
期刊介绍：
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.
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