EXHAUST GAS CLEANING BY THREE WAY CATALYTIC CONVERTERS

Abstract

The object of this study is to develop a three way catalytic converter (TWC) for removal of three main exhaust pollutants; hydrocarbons (HC), carbon monoxide (CO) and nitrogen oxides (NOx) which are dangerous for both human health and environment. Previously, we developed Ag and Ce based perovskite type catalysts which are known to be active for methane combustion. We obtained full conversion of methane at 450o C with Ag substituted perovskite catalysts which are also known very active for CO and NOx removal. In our earlier work, catalysts are prepared by sol-gel method and calcined at 973 K for 5 hours. In this study, we plan to apply flame spray pyrolysis method to produce the particles as well. Catalyst will be characterized by SEM-EDS, XRD and BET surface area to describe physical properties of the both powder and monolith coated catalysts. The activity measurements of the catalysts are planned based on the real engine emission gas mixture. 0.5 % C3H8, 1.5 % CO, 0.4 % NO and 14 % CO2 balance with N2 will be tested under fuel lean and rich conditions. Activity tests will be carried out for both in powder form and monolith coated catalysts. 0.2 mg powder catalysts will be placed in a 0.6 cm outer diameter quartz tubular reactor and the three main pollutants HC, NO, CO concentrations in the outlet gas stream will be analyzed with online HC, CO and NOx gas monitors. The same catalyst will be coated on 2 cm diameter 400 cpsi cordierite monoliths and activity tests will be carried out in a stainless steel reactor.

Keywords

• emissions, gas cleaning, catalyst, TWC