Direct catalytic decomposition of nitric oxide. Quarterly technical progress report No. 5, October--December 1992

Abstract

This project investigates a suitable catalyst system for the direct NO decomposition in post-combustion gas streams. The process does not use a reductant, such as the ammonia used in Selective Catalytic Reduction (SCR) of NO{sub x} to nitrogen. Therefore, it is a greatly simplified process basically involving passing the flue gas through a catalytic converter. Catalysts are prepared by incorporating metal cations into zeolite supports according to ion exchange procedures widely used in preparation of metal/zeolite catalysts. The catalysts of primary interest include copper, palladium, silver, and nickel exchanged ZSM-5 catalysts. Particular emphasis is given in this work on promoted Cu-exchanged zeolites, especially the catalyst system Mg/Cu-ZSM-5 and a few others, which are promising for NO conversion to nitrogen at typical flue gas O{sub 2} and NO levels and over the temperature range of 723--873K. Effects of zeolite modification, copper exchange level and catalyst preparation conditions on the catalyst activity are studied in a packed-bed microreactor. Temperature-programmed desorption (TPD) and reduction (TPR) experiments will be carried out in a thermogravimetric analyzer and a single-particle electrodynamic balance (EDB). Kinetic studies of NO and O{sub 2} interaction with catalysts over a wide temperature range as well as catalyst structural investigations are planned.