Influence of hydrocarbon molecular size on the selective catalytic reduction of NO by hydrocarbons over Cu-MFI zeolite

The influence of hydrocarbon molecular size on the HC-SCR activity was inve stigated over Cu-MFI zeolites having different crystal sizes. In the case o f n-hexane as a reductant, the catalytic activity did not depend on the zeo lite crystal size. In the case of 2,2-dimethylbutane, however, the observed reaction rate depended on the zeolite crystal size, indicating that the re action was controlled by intracrystalline diffusivity. It was verified that the catalytic activity for the SCR of NO by a larger hydrocarbon over Cu-M FI zeolite was restricted by geometry-limited diffusion depending on the hy drocarbon molecular size and the zeolite pore size. (C) 2001 Elsevier Scien ce B.V. All rights reserved.