Cobalt oxide species supported on SBA-15, KIT-5 and KIT-6 mesoporous silicas for ethyl acetate total oxidation

Cobalt oxide modified SBA-15, KIT-5 and KIT-6 mesoporous silicas with different pore size/pore entrances have been synthesized by a conventional wet impregnation method using cobalt nitrate as the precursor. The modified materials were characterized by N(2)-physisorption, XRD, TEM-EDX, XPS, FT-IR, UV-vis and TPR-TG with hydrogen. Their catalytic activities in total oxidation of ethyl acetate were evaluated. A good correlation was observed between the catalytic activity, and the presence of spinel-type Co(3)O(4) in the materials. Supports with larger mesopores facilitated the formation of such easily reducible spinel particles. However, the interconnectivity of the mesopores and the uniformity of the channel dimensions also had an influence on the catalytic activity. implying that mass-transfer effects, especially in the case of supports with cage-like mesopores. (C) 2008 Elsevier B.V. All rights reserved.