Comparison of Selective Catalytic Reduction Performance of Mn–Co Bi‐Metal Oxides Prepared by Different Methods

Abstract

AbstractIn this work, the low dimensional flake Mn4Co1Ox composite oxides were prepared by four different methods (hydrothermal, template, co‐precipitation and one‐step, noted as HS, TM, OP and OS, respectively) and used for the ammonia selective catalytic reduction (NH3‐SCR) at low temperatures. The results showed that the activity of the catalysts decreased in the sequence: Mn4Co1Ox‐HS > Mn4Co1Ox‐TM > Mn4Co1Ox‐OP> Mn4Co1Ox‐OS. The activity of the best catalyst (Mn4Co1Ox‐HS) was nearly 100 % NO conversion in the temperature range of 75–250 °C and the N2 selectivity remained above 50 % even at 250 °C. Mn4Co1Ox‐TM catalyst also maintained the NO conversion more than 90 % in the range of 100–250 °C, but the N2 selectivity was poor. The catalytic activity of the other two catalysts was slightly lower than the above two catalysts. Based on the comprehensive characterization, it was found that the Mn4Co1Ox‐HS catalyst had a higher NH3 adsorption and activation capacity, which was attributed to the higher surface area caused by its approximately two‐dimensional folded layered structure leading to more active sites. Meanwhile, it was rich in the surface acid sites, Mn3+, Co3+ and surface oxygen in the Mn−Co spinel structure, thus giving strong acidity and good redox capacity.