Development and Test of a New Catalytic Converter for Natural Gas Fueled Engine

This paper presents exhaust gas emissions characteristcs of a new direct injection (DI) compressed natural gas (CNG) engine using a low cost catalytic conveter (Catco). The pollutants exhaust gas emissions measured were CO, HC and NOx with and without Catco. The Catco was developed based on catalyst materials consisting of metal oxides such as titanium dioxide (TiO₂) and cobalt oxide (CoO) with wiremesh substrate. Both of the catalyst materials (such as TiO₂ and CoO) are inexpensive in comparison to conventional catalysts (noble metals) such as palladium or platinum. In addition, the noble metals such as platinum group metal are now indentified as human health risk due to their rapid emissions in the environment from various resources like conventional catalytic converter, jewelers and other medical usages. It can be mentioned that both the CNG-DI engine and TiO₂/CoO based catalytic converter were developed under a research collaboration program. The original engine manufacture catalytic conveter (OEM Catco) was tested for comparison purposes. The OEM Catco was based on noble metal catalyst with honeycomb ceramic substrate. It is experimentally found that the conversion efficiencies of TiO₂/CoO based catalytic converter are 93%, 89% and 82% for NOx, CO and HC emissions respectively. It is calculated that the TiO₂/CoO based catalytic converter reduces 24%,41% and 40% higher NOx, CO and HC emissions in comparison to OEM Catco respectively. The objective of this paper is to develop a low cost three way catalytic converter to be used with the newly developed CNG-DI engine. Detailed review on catalytic converter, low cost catalytic converter development characteristics and CNG-DI engine test results have been presented with discussions.