Review Paper on Perovskite Prepared by Reactive Grinding

Abstract

The main objectives of catalytic control of air pollution is to purify automobile exhaust gases which can cause serious environmental problems such as photochemical smog, acid rain, ground level ozone and respiratory diseases. Perovskite oxides is promising alternatives to supported noble metals for exhaust gas depollution because of their low cost, thermal stability at rather high temperatures, great versatility and excellent redox properties. The major traditional drawback of perovskites is the low specific surface area (usually several m2/g) due to their preparation which involves high temperature (often as high as 800 0C) to ensure the formation of the crystalline phase. This suppresses their activity and to some degree limits their application. A new preparation method called reactive grinding is developed for the synthesis of perovskites at room temperature via high-energy ball milling which results in a relatively high surface area when grinding additives are used. This review paper discuses automotive exhaust emissions and its impact, automotive exhaust emission control by platinum (noble) group metal based catalyst in catalytic converter, reactive grinding via high-energy ball milling, types of high energy ball mill, process variables in milling, synthesis of perovskite by reactive grinding.