Hydrogen enrichment of biogas via dry and autothermal-dry reforming with pure nickel (Ni) nanoparticle

Abstract

The present study includes first attempt to assess the performance of bare Ni nanoparticle towards dry and autothermal-dry reforming of synthetic biogas. Influence of reaction temperature was strong on H2/CO ratio in both reforming processes, whereas, weight hour space velocity (WHSV) showed variation in products yields. In dry reforming, Ni showed better performance at high temperature and low WHSV. Highest CH4 conversion and H2 selectivity of 77.1 and 36.7%, respectively, were observed at 900 °C temperature and 20,000 NmL g−1 h−1 WHSV, whereas, increased WHSV to 40,000 NmL g−1 h−1, 21.6 and 26.3% decrement in CH4 conversion and H2 selectivity was observed. Autothermal-dry reforming employed at 0.17 O2/CH4 ratio with high reaction temperature (≥850 °C) showed improved performance in terms of reactant conversion and H2 yield. At 900 °C, CH4 conversion and H2 selectivity of 80.8 and 35.9%, respectively, were obtained at 0.17 O2/CH4 ratios in autothermal-dry reforming. Carbon deposition of 0.40 wt% was examined under dry reforming at 900 °C, whereas, negligible carbon deposition (0.003 wt %) was observed in case of autothermal-dry reforming. Thus, autothermal-dry reforming offers better option for H2 enrichment and effectively addresses the problems of carbon deposition and high energy requirement of dry reforming process.