Palladium and copper: Environmentally benign catalysts for oxidative carbonylation and photocatalysis

Approaches to developing the novel synthetic methodologies include toxic feedstock substitution and/or the recycle of undesirable products to be useful chemicals. This dissertation addresses two issues in catalyst for the environmentally benign processes: development of novel catalytic processes for environmentally benign synthesis and hydrocarbon synthesis from photcatalytic reaction for the recycle of CO2 over Pd- and Cu-based catalysts. The traditional carbamate synthesis route utilizes phosgene, which is highly detrimental to the environment. An alternative approach, oxidative carbonylation, offers a much more environmentally-friendly solution. A low-pressure oxidative carbonylation reaction system for the production of carbamate may serve as an environmentally benign, economically feasible, and alternative to the conventional toxic phosgene-amine route.; Pd/C-NaI exhibited a high activity for oxidative carbonylation of aniline to form urea and oxidative carbonylation of aniline with methanol to form carbamate. We developed the gas-solid oxidative carbonylation of aniline with methanol to overcome the solubility limitation of gaseous reactant in the liquid phase. The gas-solid reaction system not only produces higher yield of carbamate formation than the conventional slurry phase reactor but also slows down the catalyst deactivation and provides ease of catalyst separation. These studies have not only enabled a better understanding of the carbamate synthesis from oxidative carbonylation reaction over Pd/C, but they also promise for further development towards industrial application.; Photocatalysis could provide a cost-effective route to recycle CO to useful chemicals or fuels. The objective of this research is to study the photo-catalytic activity of TiO2, TiO2 sol gel, and SiC-base catalysts. Pd/TiO2 sol gel was found to be the most active and selective catalyst for methane synthesis. The activity of the catalyst decreased in the order: Pd/TiO2 sol gel > Rh/TiO2 > Pd/SiC > Cu/TiO2 > Cu/SrTiO3 > TiO2 > SiC. These catalysts were characterized via XRD and UV-Vis before and after reaction. XRD data show the changes in TiO2 sol gel crystal structure from rutile to anatase under the UV light exposure to enhance the overall activity and selectivity for hydrocarbon synthesis.