Steam- and autothermal-reforming of n-butanol over Rh/ZrO2 catalyst

Steam reforming (SR) and autothermal reforming (ATR) of n-butanol was studied over 0.5 wt% Rh/ZrO2 catalyst at 500, 600 and 700 °C, atmospheric pressure, steam to carbon (S/C) molar ratio of 4 and oxygen to carbon (O2/C) molar ratio of 0.1. The influence of the O2/C ratio on performance was also carried out at 500 °C. Catalyst performance, i.e. conversion, product distribution and short-term stability, was compared with plain ZrO2 support to derive a reaction network, including contributions of reactions in the gas phase, on the support and on Rh. At 500 and 600 °C the catalyst deactivated very rapidly for WGS and hydro-isomerization reactions, slightly less rapidly for reforming and significantly slower for dehydration and dehydrogenation reactions. Increasing temperature and oxygen concentration improved catalyst stability. Rh/ZrO2 showed promising performance at 700 °C with complete conversion and hydrogen yield, 70% of theoretical maximum, decreasing over 21 h with not more than 8 and 1% for SR and ATR, respectively. Deactivation of the catalyst for reforming is caused by carbon deposition on and near the Rh particles. At 700 °C, coke forms via gas phase reactions, while catalytic reactions on the surface mainly contribute at 500 and 600 °C