Selective production of H2 from ethanol at low temperatures over Rh/ZrO2-CeO2 catalysts

A series of Rh catalysts on various supports (Al(2)O(3), MgAl(2)O(4), ZrO(2), and ZrO(2)-CeO(2)) have been applied to H(2) production from the ethanol steam reforming reaction. In terms of ethanol conversion at low temperatures (below 450 ) with 1wt% Rh catalysts, the activity decreases in the order: Rh/ZrO(2)-CeO(2) > Rh/Al(2)O(3) > Rh/MgAl(2)O(4) > Rh/ZrO(2). Support plays a very important role on product selectivity at low temperatures (below 450 C). Acidic or basic supports favor ethanol dehydration, while ethanol dehydrogenation is favored over neutral supports at low temperatures. The Rh/ZrO(2)-CeO(2) catalyst exhibits the highest CO(2) selectivity up to 550 C, which is due to the highest water gas shift (WGS) activity at low temperatures. Among the catalysts evaluated in this study, the 2wt% Rh/ZrO(2)-CeO(2) catalyst exhibited the highest H(2) yield at 450 C, which is possibly due to the high oxygen storage capacity of ZrO(2)-CeO(2) resulting in efficient transfer of mobile oxygen species from the H(2)O molecule to the reaction intermediate.