CATALYTIC OXIDATION AND DEGRADATION OF ORGANIC COMPOUNDS USING SUPPORTED TRANSITION METALS/METAL OXIDES.

Abstract

0.1 wt % Palladium/ZrO 2, Manganese oxide and cobalt oxide were synthesized in our laboratory. Zirconia was prepared in the laboratory by precipitation of zirconyl chloride with ammonium hydroxide. Pd/ZrO 2 was prepared by incipient wetness impregnation technique. Cobalt oxide was prepared by solid state mixing of cobalt nitrate and ammonium bicarbonate in an agate mortar at room temperature. Manganese oxide was also prepared by mechanochemical addition of potassium permanganate and Ammonium bicarbonate in a molar ratio of 2:3 respectively. The prepared catalysts were characterized by several physical/analytical methods that include nitrogen adsorption studies (Surface area and Pore Size Analysis), X-Ray Diffractometery, Fourier Transform Infra Red spectroscopy, particle size and Scanning Electron Microscope analysis. Pd/ZrO 2 was tested for the solvent free oxidation of benzyl alcohol and Toluene respectively. The reactions were carried out in liquid phase under mild conditions of temperature and pressure. Molecular oxygen was used as oxidant. The oxidation of BzOH was > 70 % selective towards benzaldehyde formation with a TOF>6000 per hour. Kinetic study showed that Langmuir Hinshelwood (L-H) mechanism was found to be followed when the experimental data was applied to the L-H equation. The oxidation of toluene was more selective towards benzyl alcohol formation in lower reaction temperature regime; however as the reaction temperature was increased the reaction became more selective towards benzoic acid. The main oxidation products were benzyl alcohol, benzaldehyde and benzoic acid however the main product was benzoic acid. Manganese oxide was prepared by solid state mechanochemical addition of potassium permanganate and Ammonium bicarbonate. The synthesized manganese oxide powder was employed for the oxidation of benzyl alcohol in liquid phase using n-heptane as a solvent. The reaction was found to very fast and 100% selective towards the formation of benzaldehyde atxv

363K and atmospheric pressure of oxygen. The reactions were performed at very low reaction temperatures i.e. 323-363K. Cobalt oxide was prepared by was prepared by solid state mechanochemical mixing of cobalt nitrate and ammonium bicarbonate. The synthesized catalyst was employed for the catalytic degradation of two different dyes i.e. Methylene Blue and Congo red. The catalyst was found to be extremely efficient towards the degradation of both these dyes. Both the organic dyes were successfully destructed in a very quick reaction time i.e. 10 minutes. Reactions were carried out in atmospheric conditions and room temperature. Various parameters affecting the degradation performance of the dye were examined such as time, catalyst loading, temperature, initial dye concentrations, speed of agitation and effect of partial pressure of oxygen. The removal percentage of dyes increased with increasing mass of Cobalt oxide up to an optimum mass but decreased with increasing initial concentrations. All the catalysts were heterogeneous in nature, which could be separated easily by simple filtration.