Novel Catalyst System for Treating Exhaust Gases from Internal Combustion and Stationary Source Engines

A major challenge facing the automotive industry today is substantially lower emissions from internal combustion engines. In the face of the 1990 Clean Air Act passed by the US Government, various approaches are being researched and developed to meet that challenge. A simple solution can result if one has available a high temperature stable catalyst system that can be installed close to the engine exhaust manifold. Such a simple catalyst system has been discovered^(1)* and is being developed for commercial use. This system is based on a thermodynamically stable, alpha-alumina monolith onto which are deposited noble metals. These alpha-alumina monoliths do not require a wash-coat. The noble metal loadings are typically equal to or less than those currently employed in commercial automotive catalysts. In standard engine dynamometer (V-8 Chevrolet, 350 CID, 5.7 liter) tests done at Southwest Research Institute, it has been demonstrated that these catalysts have equivalent initial performance for HC and CO combustion and NO_x reduction without the need for rhodium. However, they excel in superior high temperature stability, and a surprisingly excellent NO_x reduction activity equivalent to the commercial rhodium containing catalysts. This paper will highlight the results of catalyst performance testing and also show the ability of the new catalyst system to withstand greater than 1200°C (likely about 1400+°C) temperature experienced during engine misfire-conditions under which a commercial Honda Ac-