You are here:
SELECTIVE OXIDATION OF ALCOHOLS IN GAS PHASE USING LIGHT-ACTIVATED TITANIUM DIOXIDE
Citation:
Pillai**, U R. AND E SahleDemessie*. SELECTIVE OXIDATION OF ALCOHOLS IN GAS PHASE USING LIGHT-ACTIVATED TITANIUM DIOXIDE. Iglesia, E. (ed.), JOURNAL OF CATALYSIS. Elsevier Science Ltd, New York, NY, 211(2):434-444, (2002).
Description:
Selective oxidations of various primary and secondary alcohols were studied in a gas phase photochemical reactor using immobilized TiO2 catalyst. An annular photoreactor was used at 463K with an average contact time of 32sec. The system was found to be specifically suited for the selective oxidation of primary and secondary aliphatic alcohols to their corresponding carbonyl compounds. Benzylic alcohols gave higher conversions, however, with more secondary reaction products. This has been explained in relation to their tentative geometry of adsorption on the catalyst surface. The reaction mechanism for various products formed is explained. The effects of different reaction parameters like O2/substrate ratio, water vapor, UV light and contact time were studied. presence of oxygen was found to be critical for the photo oxidation but its concentration was not very significant. Water vapor in the feed was also found to be helpful in the reaction although it was not as critical as in hydrocarbon oxidations where it was necessary for hydroxylating the catalyst surface and sustaining its activity. In alcohol oxidation, surface hydroxylation could be partially provided by the hydroxyl groups of the alcohol itself. Catalyst deactivation was also observed and is attributed to the surface accumulation of reaction intermediates and products. However, the catalyst regained its original activity after regeneration by calcining in air for 3h at 723K.