Authors: Prakash Biswas Deepak Kunzru
Publish Date: 2007/05/16
Volume: 118, Issue: 1-2, Pages: 36-49
Abstract
Steam reforming SR and oxidative steam reforming OSR of ethanol were investigated over undoped and Cu Co and Ca doped Ni/CeO2–ZrO2 catalyst in the temperature range of 400–650 °C The nickel loading was kept fixed at 30 wt and the loading of Cu and Co was varied from 2 to 10 wt whereas the Ca loading was varied from 5 to 15 wt The catalysts were characterized by various techniques such as surface area temperature programmed reduction XRay diffraction and H2 chemisorption For Cu and Co doped catalyst CuO and Co3O4 phases were detected at high loading whereas for Ca doped catalyst no separate phase of CaO was found The reducibility and the metal support interactions were different for doped catalysts and varied with the amount and nature of dopants The hydrogen uptake nickel dispersion and nickel surface area was reduced with the metal loading and for the Co loaded catalysts the dispersion of Ni and nickel surface area was very low For Cu and Ca doped catalysts the activity was increased significantly and the main products were H2 CO CH4 and CO2 However the Co doped catalysts showed poor activity and a relatively large amount of C2H4 C2H6 CH3CHO and CH3COCH3 were obtained For SR the maximum enhancement in catalytic activity was obtained with in the order of NCu5 For Cu–Ni catalysts CH3CHO decomposition and reforming reaction was faster than ethanol dehydrogenation reaction Addition of Cu and Ca enhanced the water gas shift WGS and acetaldehyde reforming reactions as a result the selectivity to CO2 and H2 were increased and the selectivity to CH3CHO was reduced significantly The maximum hydrogen selectivity was obtained for Catalyst N 934 at 650 °C whereas nearly the same selectivity to hydrogen 89 was obtained for NCa10 catalyst at 550 °C In OSR the catalytic activity was in the order N NCu5 NCa15 NCo5 In the presence of oxygen oxidation of ethanol was appreciable together with ethanol dehydrogenation For SR reaction the highest hydrogen yield was obtained on the undoped catalyst at 600 °C However with calcium doping the hydrogen yields are higher than the undoped catalyst in the temperature range of 400–550 °C
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