The reactions of NOX with diesel soot over Cu-ZSM-5 catalyst

Air pollution from the exhaust of Diesel engines consisting of relatively high concentrations of NOx and particulates is a difficult problem to overcome because no fully effective technology to control these emission is available. The existing methods to reduce NOx and soot can not satisfy the provisions of the 1990 CAAA (Clean Air Act Amendment). Cu-ZSM-5, a catalyst in which Cu has been ion-exchanged with H+, can catalyze the decomposition of NO to N2 and O2 and reduction to N2 and O2 with light hydrocarbons such as propene or Diesel soot in the presence of oxygen. The latter catalytic approach, refered to as lean NOx control, is attracting much attention in the automotive industry. Moreover, a new approach for using the catalyst to treat the exhaust from Diesel engines with a Rotating Fluidized Bed Reactor (RFBR) is being developed in Japan and at NJIT. This reactor captures soot at low power operation and reacts it with NOx at high power allowing self-cleaning of these emissions from Diesel engines. In order to better understand the chemistry taking place between NOx and soot, a fixed bed was used to study the decomposition of NOx and the reaction of NOx with soot. The goal of the research is to find the optimal conditions that will allow maximum soot and NOx destruction. Differences in decomposition activity were compared between NO and NO2 over Cu-ZSM-5, ZSM-5 and SiO2/Al2O3. This was followed with experiments designed to study the ability of soot to reduce NO and NO2 over the same catalyst. The effect of oxygen on the decomposition of NOx and reduction of NOx with soot was also evaluated