Selective Production of H2 from Ethanol at Low Temperatures over Rh/ZrO2–CeO2 Catalysts

摘要

A series of Rh catalysts on various supports (Al2O3, MgAl2O4, ZrO2, and ZrO2–CeO2) have been applied to H2 production from the ethanol steam reforming reaction. In terms of ethanol conversion at low temperatures (below 450 °C) with 1wt% Rh catalysts, the activity decreases in the order: Rh/ZrO2–CeO2 > Rh/Al2O3 > Rh/MgAl2O4 > Rh/ZrO2. 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/ZrO2–CeO2 catalyst exhibits the highest CO2 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/ZrO2–CeO2 catalyst exhibited the highest H2 yield at 450 °C, which is possibly due to the high oxygen storage capacity of ZrO2–CeO2 resulting in efficient transfer of mobile oxygen species from the H2O molecule to the reaction intermediate.