Ceria based novel nanocomposites catalysts MnxCe1−xO2/α-Al2O3 for low-temperature combustion of methanol

Highly improved soot combustion performance over synergetic MnxCe1-xO2 solid solutions within mesoporous nanosheets

Constructing synergetic bimetal oxide solid solutions with exceptional catalytic performances for efficient soot elimination is becoming a research frontier in environmental catalysis. Herein, synergetic Mn_xCe_1-xO₂ solid solutions within mesoporous nanosheets, synthesized by a facile hydrothermal method for the first time, have been performed to catalyze the NO_x-assisted soot combustion. Research results validate that Mn_xCe_1-xO₂ solid solutions displayed highly improved soot combustion performance with respect to activity and selectivity, mainly due to the synergetic effect by combining factors of the unique mesoporous nanosheet-shaped feature, the enhanced chemical nature stemmed from high-valence Mn species, abundant active oxygen species originated from the enriched oxygen vacancies and the escalated redox properties. Furthermore, the enhanced NO_x storage and oxidation abilities, mainly derived from integrating reciprocal merits of high-valence Mn species and CeO₂, were also responsible for the highly improved soot combustion performance via NO_x-assisted mechanism. Moreover, Mn_xCe_1-xO₂ solid solutions also exhibited excellent reusability due to the unique morphological structure and stable crystal phase, showing good potential in practical applications.

Enhanced activity and stability of La-doped CeO2 monolithic catalysts for lean-oxygen methane combustion

Effective utilization of coal bed methane is very significant for energy utilization and environment protection. Catalytic combustion of methane is a promising way to eliminate trace amounts of oxygen in the coal bed methane and the key to this technology is the development of high-efficiency catalysts. Herein, we report a series of Ce_1-xLa_xO_2-δ (x = 0-0.8) monolithic catalysts for the catalytic combustion of methane, which are prepared by citric acid method. The structural characterization shows that the substitution of La enhance the oxygen vacancy concentration and reducibility of the supports and promote the migration of the surface oxygen, as a result improve the catalytic activity of CeO₂. M-Ce_0.8La_0.2O_2-δ (monolithic catalyst, Ce_0.8La_0.2O_2-δ coated on cordierite honeycomb) exhibits outstanding activity for methane combustion, and the temperature for 10 and 90% methane conversion are 495 and 580 °C, respectively. Additionally, Ce_0.8La_0.2O_2-δ monolithic catalyst presents excellent stability at high temperature. These Ce_1-xLa_xO_2-δ monolithic materials with a small amount of La incorporation therefore show promises as highly efficient solid solution catalysts for lean-oxygen methane combustion. Graphical abstract ᅟ.