DECOMPOSITION AND OXIDATION OF CH313 CH2OH ON AL2O3, PD AL2O3, AND PDO/AL2O3 CATALYSTS/

Temperature-programmed desorption (TPD) and oxidation (TPO) were used to investigate the decomposition and oxidation of ethanol on Al2O3, Pd /Al2O3, and PdO/Al2O3. Ethyl-alpha-C-13 alcohol ((CH3CH2OH)-C-13) was adsorbed on the catalysts so that reaction pathways of the two carbons could be distinguished. Alumina was mainly a dehydration catalyst, bu t dehydrogenation was also observed and some carbon remained on the su rface. In the presence of O-2, Al2O3 oxidized the decomposition produc ts and the beta-carbon was oxidized faster. Ethanol, which was adsorbe d on Al2O3, decomposed much faster on Pd/Al2O3 by diffusing to Pd and undergoing CO elimination to form CH4, (CO)-C-13, H-2, and surface car bon. On PdO/Al2O3, the decomposition was slower than on Pd/Al2O3 until lattice oxygen was extracted above 450 K; the decomposition products were oxidized by lattice oxygen. In the presence of gas phase O-2, Pd/ Al2O3 was an active oxidation catalyst at low temperature, but lattice oxygen had to be extracted from PdO/Al2O3 before it had significant o xidation activity.