Oxidative and non-oxidative steam reforming of crude bio-ethanol for hydrogen production over Rh promoted Ni/CeO2-ZrO2 catalyst

Abstract

The catalytic oxidative and non-oxidative steam reforming of crude bio-ethanol for hydrogen production was studied in a tubular fixed bed reaction system over 30wt.%Ni/CeO2-ZrO2 and 1wt.%Rh-30wt.%Ni/CeO2-ZrO2 catalysts. The catalysts were prepared by impregnation-co-precipitation method and characterized by BET, XRD, TPR, TGA, XPS, XANES and EXAFS techniques. Characterization results revealed that the addition of Rh promotes reducibility of NiO at lower temperature for the bimetallic catalysts. Extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) analysis depicted that NiO with 6-fold local co-ordination is present in all the samples. Ethanol conversion, hydrogen yield and product selectivity were investigated at 600°C and space time of 9.17kgcath/kgmol[EtOH]) at atmospheric pressure. In steam reforming of crude bio-ethanol, 81% ethanol conversion was achieved with 59% hydrogen selectivity on Ni/CeO2-ZrO2 catalyst, whereas, higher ethanol conversion (86%) with 73% hydrogen selectivity was achieved using Rh-Ni/CeO2-ZrO2 catalysts. In oxidative steam reforming of crude bio-ethanol, hydrogen yield and selectivity reduced due to the partial oxidation of oxygenate compounds present in the feed. The used catalysts were also analysed by BET, TGA/DTA, TPR, TPO, Raman spectroscopy, SEM, and TEM techniques to identify the cause of catalyst deactivation. The results indicate that the catalyst deactivation occurred mainly due to amorphous and filamentous carbon deposition on the catalysts surface, due to the presence of the impurities in the feed.