Effects of propane/methane ratios on NOX reduction by mixtures of methane and propane over In/H-BEA catalyst were investigated at temperatures ranging from 250 to 550 degrees C. The higher catalytic activity of In/H-BEA was exhibited for CH4-SCR at high temperatures above 450 degrees C, while the higher NOX conversion was achieved in C3H8-SCR at below 425 degrees C. A broadened temperature window and enhanced CO2 selectivity were achieved by combining of methane and propane as the co-reductant. The mixtures with propane/methane of 1/2 showed the most superior T-50 (325 degrees C) and T-90 (500 degrees C) temperatures for NOX reduction over In/H-BEA catalyst. For the promotion mechanism of propane on NO reduction by methane at low temperature, the formation of carbonaceous species (e.g. R-COOH) were enhanced by the activation of C3H8 on Bronsted acid sites at low temperature, and further promoted the generation of -NCO species, which was a crucial determining step for NO reduction. (C) 2016 Elsevier B.V. All rights reserved.