| There is an increasing demand for technology that can be used to convert environmentally hazardous chemicals into benign and useful compounds. Generation of these new technologies relies on a fundamental understanding of the nature of catalytic activity. This thesis provides such an understanding of the selective conversion of two major classes of compounds (Chlorocarbons and Automotive emissions) to more environmentally benign alternatives.; The research carried out on the conversion of 1,2-dichloroethane to ethylene over a bimetallic Pt-Cu catalyst is presented in Chapter 3. It was found that for monometallic Pt catalyst and for those with Cu/Pt atomic ratio <1, the reaction products were mainly ethane and monochloroethane. However, as the Cu/Pt ratio was increased from 1 to 18, the selectivity towards ethylene increased to almost 90%. Monometallic Cu exhibited 100% selectivity towards ethylene but its activity was 2 orders of magnitude lower than the bimetallic catalysts. A molecular level picture involving the effect of equilibration of bimetallic particles during the reaction on the ethylene selectivity has been developed.; Bimetallic Pt-Cu catalysts supported on silica were studied using infrared spectroscopy. Infrared investigations of CO adsorption indicate that Pt and Cu form bimetallic particles during the catalyst pretreatment and that besides a dilution effect of Cu on Pt ensembles, Cu alters the electronic properties of Pt atoms. In this context, the cause of increased selectivity and activity of the bimetallic catalysts when compared to the monometallic catalysts is discussed in detail in Chapter 4.; Automotive exhaust treatment has been a widely researched area in environmental catalysis. Of particular interest is the development of sulfur tolerant catalysts. Two catalysts Pd/CeO2 and Pd/CeO2-ZrO2 were studied for the NO + O2 + CO + C3H6 reaction both in the presence and absence of SO2 and under different feed-stream conditions. Although Pd/CeO2 was active for the conversion of NO x, CO and C3H6 in the absence of SO2, its activity was affected by the presence of 20 ppm of SO2. Addition of ZrO2 increased the stability and activity of the catalyst both under steady reactant stream and cyclic conditions. These results are discussed in detail in Chapter 5. |
