Cerium modified birnessite-like MnO2 for low temperature oxidation of formaldehyde: Effect of calcination temperature

Abstract

Cerium modified birnessite-like MnO2 were synthesized (CexMn; x = 0.01; 0.1) from a simple and inexpensive redox method involving the reduction of potassium permanganate by sodium lactate in the presence of Ce(NO3)3 at ambient temperature. The as-synthesized samples were calcined at different temperatures (Tc: 200, 300 and 400 °C) to be tested in HCHO total oxidation in dry air at low temperature. The Ce0.01Mn catalyst calcined at 400 °C showed the best catalytic activity in HCHO oxidation with a T50 (temperature at which 50 % of HCHO was converted into CO2) of 50 °C and was found to be air and moisture stable (up to 75 %RH) upon time. The beneficial effects of a calcination step at 400 °C allowed to get enhanced asymmetric Ce-O-Mn surface interactions along with highly dispersed Ce4+/3+ related species and enhanced TCMn3+ (TC: triple corner) amounts which contributed to a great extent for its high activity in HCHO oxidation.