Hydrogen Production from Ethanol Steam Reforming Over Supported Cobalt Catalysts
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Hydrogen production was carried out via ethanol steam reforming over supported cobalt catalysts. Wet incipient impregnation method was used to support cobalt on ZrO2, CeO2 and CeZrO4 followed by pre-reduction with H2 up to 677 °C to attain supported cobalt catalysts. It was found that the non-noble metal based 10 wt.% Co/CeZrO4 is an efficient catalyst to achieve ethanol conversion of 100% and hydrogen yield of 82% (4.9 mol H2/mol ethanol) at 450 °C, which is superior to 0.5 wt.% Rh/Al2O3. The pre-reduction process is required to activate supported cobalt catalysts for high H2 yield of ethanol steam reforming. In addition, support effect is found significant for cobalt during ethanol steam reforming. 10% Co/CeO2 gave high H2 selectivity while suffered low conversion due to the poor thermal stability. In contrast to CeO2, 10 wt.% Co/ZrO2 achieved high conversion while suffered lower H2 yield due to the production of methane. The synergistic effect of ZrO2 and CeO2 to promote high ethanol conversion while suppress methanation was observed when CeZrO4 was used as a support for cobalt. This synergistic effect of CeZrO4 support leads to a high hydrogen yield at low temperature for 10 wt.% Co/CeZrO4 catalyst. Under the high weight hourly space velocity (WHSV) of ethanol (2.5 h−1), the hydrogen yield over 10 wt.% Co/CeZrO4 was found to gradually decrease to 70% of its initial value in 6 h possibly due to the coke formation on the catalyst.