The beneficial effect of lauric acid addition in nucleation stage on the soot catalytic combustion performance of cerium-manganese catalyst

Abstract

For cerium-manganese catalyst system, increasing the threshold of the amount of Mnx+ entering into the CeO2 lattice can generate more oxygen vacancies and adsorb more active oxygen species, thus promoting its soot catalytic combustion. However, this is difficult to achieve under the premise of fixed cerium-manganese ratio of the catalyst. Fortunately, the results of this study show that the addition of lauric acid at the nucleation stage of the cerium-manganese catalyst can effectively improve its activity and high temperature aging resistance. Combined with a series of characterization results, the addition of lauric acid can increase the threshold of Mnx+ content in CeO2 lattice, improve the structural performance of the catalyst, increase the specific surface area and pore volume of the catalyst, inhibit the secondary aggregation of catalyst particles, increase the content of surface Ce3+, increase the low temperature reduction performance and the content of surface chemical desorbed oxygen of the catalyst. In addition, it can also prevent the phase separation of cerium-manganese solid solution, the growth of grains, the increase of reduction peak temperature and the decrease of H2 consumption during high temperature aging. Moreover, the addition of lauric acid also greatly improves the release performance of active oxygen in cerium-manganese catalyst. Therefore, this study plays a positive role in promoting the commercial application of highly active cerium-manganese catalyst.