SYNTHESIS AND CHARACTERISATION OF CATALYTIC MATERIALS FOR DECOMPOSITION OF NITROUS OXIDE

Abstract

Catalytic decomposition of nitrous oxide (N2O) has been studied on transition metals (Co, Ni) involved catalyst systems Co/Ni/ZrO2/Al2O3 (CNZSn) with GC, EA and BET methods. The ZrO2 in current work is prepared using sol-gel technique and further supported on Al2O3. The results of catalytic activity evaluation show that the supported ZrO2 carrier and CNZSn materials have better catalytic performance than Al2O3 support itself for the decomposition of high concentration N2O. With FTIR, XRD and DTA methods, a systematic study on the metal (Co, Ni) induced stabilising effects on starting ZrO2 matrices of tetragonal and monoclinic modifications is reported. The investigation indeed shows the metal induced tetragonal stability and effects on other phase transformations of the studied material system. Combined metal system (Co + Ni) is also studied to see each role of metals at elevated temperatures and their capability in stabilising metastable tetragonal phase. A study on material aspects of Mg-Co binary oxides system for low-temperature high-concentration N2O decomposition is also presented in this thesis. Binary metal oxide catalysts of Mg-Co have been synthesised from the double metal hydroxide precursors by a co-precipitation then calcination method. Using this materials system at 350°C, approximately 6 moles of N2O per kg of catalyst can be decomposed in one hour, which is among the most active catalysts reported so far in terms of thermal energy saving. With FTIR, XRD, SEM, EA, DSC, BET, and GC techniques, the investigation examines in great detail the synthesis parameters, hydrothermal treatment, chemical composition, anion exchangeability, surface morphology, chemical/thermal stabilities, and catalytic performance of the precursor materials.