Hydrogen production and carbon dioxide enrichment from ethanol steam reforming followed by water gas shift reaction

Hydrogen production from a two-stage reaction, namely, the ethanol steam reforming (ESR) followed by the water gas shift reaction (WGSR), is experimentally investigated in this study. A Ni/Al2O3 catalyst and a Fe/Cr2O3 catalyst are employed to trigger the ESR and WGSR, respectively, and four operating parameters, including the feed liquid flow rate, water-to-carbon (H2O/C) molar ratio, ESR temperature, and WGSR temperature, are taken into account. To analyze the impact of the operating parameters upon the chemical reactions and maximize the H-2 yield from ethanol, the Taguchi method considering the four factors along with three levels is adopted. The results suggest that the influences of the factors on the H-2 yield are ranked by H2O/C ratio > ESR temperature > WGSR temperature > liquid flow rate. In light of the optimal operation suggested by the Taguchi approach, ethanol is completely consumed and the maximum H-2 yield is 4.26 mol/(mol C2H5OH). This value accounts for around 73% of theoretical H-2 yield based on thermodynamic analysis. Meanwhile, the CO2 concentration in the product gas is enriched to 21.77%, whereas the CO one is as low as 0.81%. These evidences reveal that the two-stage reaction can reach the requirement of high H-2 yield along with low CO formation, and is conducive to CO2 capture. (C) 2017 Elsevier Ltd. All rights reserved.