(328c) Effect of Noble Metals On Steam Reforming of Ethanol for Minimization of Carbon Monoxide Formation for Hydrogen Production

The ethanol reforming is being considered as potential source for hydrogen generation to feed PEM fuel cells. The main challenge is to develop a catalyst to optimize the hydrogen yield with minimization of carbon monoxide formation and increase of energy efficiency of process to foster the use of onboard compact reformers. In this study steam reforming of ethanol over Ni/CeO₂-ZrO₂ catalyst and effect of addition of noble metals (Rh and Ru) were examined. The CeO₂-ZrO₂ support was prepared by co precipitation method which has a high oxygen storage capacity and promotes water gas shift reaction at high temperature. The active Ni metal was impregnated on support by wetness impregnation method. Noble metals were doped on Ni/CeO₂-ZrO₂ by wetness incipient method. The ethanol steam reforming experiments were conducted in a fixed bed reactor and results were reported in terms of hydrogen yield and product selectivity. The  catalysts were analyzed for ethanol reforming at a steam to ethanol molar ratio 9:1 and for a range of temperatures (550-700⁰ C), at atmospheric pressure condition. It was observed that for Ni/CeO₂-ZrO₂, the maximum H₂ yield was 5.3 moles with CO selectivity of 8% at 700⁰C. However, for noble metals maximum H₂ selectivity was figured at lower temperatures. Ru doped catalyst at 550⁰C exhibited a lower value of CO selectivity, i.e. 5.7% with H2 yield of 5.76 moles. But Rh doped catalyst reported a substantial decrease in CO selectivity (2.6%) with H₂ yield of 5.84 moles at 600⁰C. Rh exhibits high activity towards C-C and C-H bond breaking which helps in reducing formation of undesired hydrocarbon such as ethylene which further results in coke formation. This argues the use of Rh doped Ni/CeO₂-ZrO₂ as a potential catalyst for onboard reformers due to comparatively lower value of CO selectivity and operating temperature (~600 ⁰C).