Development of ceria and tungsten promoted nickel/alumina catalysts for steam reforming of diesel

Abstract

Use of diesel fuel for on-board hydrogen production for auxiliary power units (APUs) through diesel steam reforming (DSR) reaction is a promising route. Coke minimization for cheap and active Ni/Al2O3 catalyst is necessary for long term operation in DSR reaction. Coke minimization with high hydrogen productivity can be accomplished through the optimization of operating conditions and promoting the Ni/Al2O3 catalyst with ceria (CeO2) and tungsten (W) which attracts attention with their coke resistive properties. Maximization of hydrogen production and minimization of coke deposition would require an optimization of operating conditions as well as catalyst content in DSR reaction. It is shown that decrease of GHSV from 25,000 h−1 to 7500 h−1 enhances DSR by reducing side product formation, suggesting a mechanism of cracking of longer chain hydrocarbons into C2-C3 compounds which are then reformed into the desired products. Side product formation was also reduced at higher steam feeding by further reforming of side products and promotion of water gas shift reaction (WGSR) activity in excess steam environment enhanced H2 production. CeO2 incorporation lead to formation of CeAlO3 phase which was proven to be effective in promoting WGSR activity, on the other hand W incorporation significantly reduced, even eliminated coke deposition. Hydrogen production capability of Ni-W/Al2O3 catalyst can be improved by using higher steam feeding which enhances WGSR. Long-term operation of DSR reaction for hydrogen production to be used in fuel cell component of APUs can be applied commercially with Ni-W/Al2O3 catalyst.