Optimum operating conditions in ethanol steam reforming over a Ni/La2O3-alpha Al2O3 catalyst in a fluidized bed reactor

摘要

This manuscript analyzes the steam reforming of ethanol (SRE) over a Ni/La2O3-alpha Al2O3 catalyst in a fluidized bed reactor under a wide range of operating conditions (500-650 degrees C, space time up to 0.35 g(catalyst)h/g(EtOH), and steam/ethanol (S/E) molar ratio in the feed between 3 and 9) in order to select optimum conditions for maximizing H-2 production. The significance the individual reactions in the reaction mechanism have on products distribution and the role of the catalyst in the extent of these reactions has also been analyzed. Blank runs (without catalyst) have been performed to test the contribution of thermal routes to this mechanism. Ethylene and acetaldehyde are intermediate products in the kinetic scheme, whose presence is only observed when ethanol conversion is not full. The increase in temperature enhances the reforming and decomposition of ethanol and acetaldehyde and, when the catalyst is used, CH4 reforming and reverse WGS reactions are also promoted, so that the yield of H-2 and CO increases, that of CH4 decreases and the one of CO2 remains almost constant with temperature. The increase in S/E molar ratio increases H-2 yield, but attenuates the rate of some reactions involved in the process. 600 degrees C, a space time of 0.35 g(catalyst)h/g(EtOH) and S/E = 6 are suitable conditions for maximizing ethanol conversion (100%) and H-2 yield (82%) with high catalyst stability.