Low-Temperature Active Pt-catalysts Supported on Mesoporous Silica and Metal-Silicates for Cleaning Diesel-NOx Exhausts

摘要

New Pt-catalysts supported on mesoporous silica (MPS) and metal-silicates, which have high de-NOx capabilities over 70 % in NOx-conversion at temperatures around 170?under lean conditions, were developed. A new prototype honeycomb supporting Pt-catalyst allows high de-NOx of diesel-exhausts possible over the wide temperature range of 170-400. The low-temperature activities of the catalysts are well correlated with the Br?nsted acidity of the support materials. In view of the reaction mechanism of the de-NOx processes, the Br?nsted acid-sites of the supports probably stimulate the oxidation of NO into NO 2 , which is the rate-determining step of de-NOx processes, leading to the low-temperature activities.