Influence of homogeneous decane oxidation on the catalytic performance of lean NOx catalysts

Abstract

Extensive homogeneous gas‐phase reactions were observed when decane was used as the hydrocarbon reductant for the selective reduction of NOx. The catalytic performance of a SnO2/CoOx/Al2O3 catalyst was found to be strongly dependent on the extent of the homogeneous reaction in the pre‐catalytic volume. The effect of the homogeneous reaction on the catalytic performance also depended on whether SO2 was present in the feed. By filling the pre‐catalytic volume with 25–35 mesh irregularly shaped quartz chips, gas‐phase reaction was suppressed significantly. This methodology was used to evaluate the inherent catalytic performance of SnO2/CoOx/Al2O3 and SnO2/Al2O3 catalysts with decane as a reductant. It was found that in the absence of SO2, SnO2/Al2O3 was a better catalyst than SnO2/CoOx/Al2O3, but in the presence of 30 ppm of SO2 the latter was a far better catalyst.