ELECTRON SPIN RESONANCE BASED INVESTIGATIONS OF COPPER DOPED ZEOLITES AS SELECTIVE CATALYTIC REDUCTION CATALYSTS FOR deNOx APPLICATIONS
OF THE THESIS Electron Spin Resonance based investigations of Copper doped Zeolites as Selective Catalytic Reduction catalysts for deNOx applications by VIRAL SAGAR Thesis Director: Professor Gerard Charles Dismukes Electron spin resonance (ESR) is an excellent spectroscopic tool to detect speciation transitions in paramagnetic samples. This research studies the activity of copper doped zeolite catalysts that breakdown the atmospheric pollutant NOx gases in diesel engine exhaust emissions.
... ust emissions. Copper exhibits +1, +2, +3 and +4 oxidation states with 3d 9 as outer shell electronic configuration for +2 oxidation state, which is most favored and detectable with Electron Spin Resonance (ESR) spectroscopy. Copper exhibits multiple coordinations such as tetra-, penta-, hexa-or octa-coordinate forms out of which four coordinate or tetra forms are preferred in the +2 state. The determination of this geometry, which affects electronic properties of Cu 2+ ions, is important to know the ground state of a certain arrangement through the order of energy levels of d orbital. The electronic g factor with the copper nuclear hyperfine splitting can be indicators of the geometry and the nature of spatial distribution of unpaired spin orbital of the iii copper center in zeolite as SCR catalysts. Our focus is on elucidating the mechanism at the metal center microenvironment that causes the catalytic activity. This research will drive the improvement in the molecular design of these catalysts and hence help advance environmental chemistry approach in reduction of atmospheric pollution from NO x gas emissions. iv