CNT-based catalysts for H_2 production by ethanol reforming

摘要

Hydrogen production by steam reforming of ethanol (SRE) was studied using steam-to-ethanol ratio of 3:1, between the temperature range of 150-450 ℃ over metal and metal oxide nanoparticle catalysts (Ni, Co, Pt and Rh) supported on carbon nanotubes (CNTs) and compared to a commercial catalyst (Ni/Al_2O_3). The aim was to find out the suitability of CNTs supports with metal nanoparticles for the SRE reactions at low temperatures. The idea to develop CNT-based catalysts that have high selectivity for H_2 is one of the driving forces for this study. The catalytic performance was evaluated in terms of ethanol conversion, product gas composition, hydrogen yield and selectivity to hydrogen. The Co/ CNT and Ni/CNT catalysts were found to have the highest activity and selectivity towards hydrogen formation among the catalysts studied. Almost complete ethanol conversion is achieved over the Ni/CNT catalyst at 400 ℃. The highest hydrogen yield of 2.5 is, however, obtained over the Co/CNT catalyst at 450 ℃. The formation of CO and CH_4 was very low over the Co/CNT catalyst compared to all the other tested catalysts. The Pt and Rh CNT-based catalysts were found to have low activity and selectivity in the SRE reaction. Hydrogen production via steam reforming of ethanol at low temperatures using especially Co/CNT catalyst has thus potential in the future in e.g. the fuel cell applications.