Effect of surface manganese oxide species on soot catalytic combustion of Ce-Mn-O catalyst

Constructing cerium and manganese bimetallic catalysts with excellent catalytic performance for soot combustion is the research frontier at present. In order to find out the key factors for catalytic soot combustion of Ce-Mn-O catalysts, a series of Ce-Mn-O catalysts with different Ce/Mn proportions were prepared by co-precipitation method. The activity test results show that it increases first and then decreases with the increase of Mn content. The best catalytic activity is obtained for Ce0.64Mn0.36 catalyst, which shows a maximum rate temperature (T-m) at 306 degrees C for CO2 production in TPO curve. Compared with non-catalytic soot combustion, the T-m decreases by more than 270 degrees C. Systematical characterization results suggest that when the adsorbed surface oxygen, lattice oxygen, specific surface area and total reduction amount of the catalysts reach a certain value, the key factors leading to the difference of catalytic activity become the readily reducible and highly dispersed surface manganese oxide species and contact performance of the external surface. The surface manganese oxide species is beneficial to improving the low-temperature reducibility of catalysts and the porous surface is conducive to the contact between catalyst and soot. Furthermore, for the soot combustion reaction containing only O-2, the promoting effect of Mn4+ is not obvious. (C) 2021 Chinese Society of Rare Earths. Published by Elsevier B.V. All rights reserved.

Automated summary

Constructing bimetallic catalysts of cerium and manganese with excellent catalytic performance for soot combustion is currently a research frontier. Experimental results show that the catalytic activity increases first and then decreases with the increase of manganese content within a certain range. The key factors for catalytic activity are the easily reducible and highly dispersed surface manganese oxide species, as well as the contact performance of the external surface, when the adsorbed surface oxygen, lattice oxygen, specific surface area, and total reduction amount of the catalysts reach a certain value.