Catalysis in C1 and H2S Chemistry and Solar Fuel Synthesis Based on Particle and Polycrystalline Semiconductors. Final Report August 1983-October 1989

摘要

Supported PdO was found to catalyze the oxidative dimerization of CH4 to C2H6 and C2H4 at T > or = 300 C; the selectivity for C2 conversion exceeded 80% at 360 C and a space velocity of 48,000/h. Methane conversion was 0.5% under the conditions. PdO was deposited on yttria-stabilized ZrO2 solid electrolyte membranes, produced by tape casting a ZrO2/Y2O3 mixture and was used with a LaO.84SrO.16MnO3 oxygen cathode. At a current density of 200 mA/sq cm, the faradaic efficiency for C2 hydrocarbon formation was 18%, the selectivity for oxidative coupling exceeded 50%. Investigations into the removal of hydrogen sulfide from natural gas and waste streams included the catalytic methanation of CO2 and CO with H2S over transition metal sulfides and the decomposition of H2S into H2 and S using the I2/I- redox couple as a mediator. Immobilization of Pd onto TiO2 powders and colloids was found to produce active photocatalysts for the selective reduction of CO2 to formate in aqueous media. Methane activation by CO2 insertion was studied. A rhodium complex was found to activate the C-H bond of several hydrocarbons towards CO2 insertion to produce carboxylic acids. Several novel photosensitizers, a photocatalyst, and a molecular semiconducting membrane were prepared and characterized.