Experimental and theoretical investigation on the high activity La0.8-xSr0.2KxMn1-yByO3-δ perovskite catalyst with combined A and B site modifications

Abstract

In this work, a series of LaMnO3 (LM) perovskite catalysts modified at A and B sites were prepared to accelerate soot combustion. The La0.68Sr0.2K0.12Mn0.9Cu0.1O3-δ (LSK0.12MCu0.1) modified by Sr, K and Cu has good catalytic activity and cycle stability, the presence of NO can obviously promote the oxidation of soot. A variety of characterization results show that doping the A and B sites of perovskite will not destroy the original structure of perovskite, and the doped ions (Sr2+, K+, and Cu2+) can enter the perovskite catalyst well, which may be conducive to the formation of more oxygen defects and active oxygen species. According to the DFT calculation, adding Sr and K to the A sites can alter how atoms interact in a perovskite catalyst, increase the amount of unsaturated coordination bonds, and encourage the development of high-valence active ions (Mn4+) and oxygen defects. The doping of transition metal to the B sites results in the formation of the Cu-O-Mn link, which forms the Mn(Cu)O6 octahedron and stimulates the development of oxygen vacancies and the release of active oxygen. This study will provide an important reference for developing non-precious metal-based perovskite materials with high activity and low cost for catalytic combustion.