I. Environmental abatement of air pollutants and greenhouse gases by photocatalytic oxidation and discharge plasmas. II. Preparation and characterization of binary mesoporous oxides

Date of Completion

January 2001

Keywords

Chemistry, Inorganic

Degree

Ph.D.

Abstract

This research contains two major parts. The first part involves abatement of small environmentally unfriendly molecules such as triethylamine, carbon tetrafluoride, and carbon dioxide by photocatalytic oxidation, and alternating current (AC) discharge plasmas respectively. The second part involves synthesis and characterization of some binary mesoporous oxides. ^ The rate of triethylamine oxidation was found to be dependent on water vapor pressure, UV intensity, and concentration of TEA. Several reaction intermediates or partial oxidation products were observed to adsorb on the catalyst surface and deactivate the catalyst by blocking the adsorption of TEA on the surface and/or by poisoning active sites for TEA degradation. ^ The concentrations of CF4 and H2O, the type of the reactors, the characteristics of the plasmas, and input voltage all played important roles in the destruction of CF4. Combined glow discharge and arc plasmas showed a synergetic effect on the destruction of CF4 . In glow discharge plasmas, N2 was activated to N2 * and N2+, which transferred energy to CF 4 and H2O to form CO2 and HF. In arc plasmas, in addition to the activation of N2 to N2* and N 2+, CF4 was also activated and formed excited CF and CF2 species, which reacted with activated N2 species to form products and other intermediates such as CN. ^ The process of glow discharge plasmas with and without arc formation using a Y-type reactor is effective in CO2 reforming CH4 into CO and H2. The reaction products included CO, H2, as well as a small amount of hydrocarbons. Reactions with the formation of arcs produced more CO as well as higher energy efficiencies than those without arc formation. ^ Thermally stable mesoporous germanium manganese oxide materials have been synthesized. The materials have an amorphous wall structure, disordered mesopores, and high surface areas. Increasing synthetic temperature increased pore volume and mean pore size, and contributed to the broadening of the pore size distribution. Extending the same approach to nickel germanium oxide system produces a high surface area material with mostly micropores. The nickel tin oxide material prepared by this approach yields a material with much larger and less defined pores similar to γ-Al2O3. ^

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