Supercritical Water Gasification as Treatment for High Lipid Content Biomass in the Presence of Nickel Catalyst

Abstract

In this work, a new approach towards converting high lipid content biomass into renewable hydrogen is investigated. Using canola oil as the representative biomass, hydrogen was obtained by employing supercritical water as a reaction medium in a continuous gasi cation system over nickel catalyst. The experiments were conducted at xed temperature (400°C), pressure (25 MPa), reaction time (residence time 45 s, or weight hourly space velocity 25.5 h 1 for catalytic reaction) and varying feed concentrations (2-5 wt%). The results of the study revealed that increasing the feed concentration had a negative e ect on hydrogen yield due to less water molecules present in the reactant. Another interesting observation is the appearance of a solid-like emulsion, composed of products from polymerization reaction. The appearance of this emulsion is strongly correlated to the decline of catalyst activity. Further characterization of the nickel catalyst used after the reaction found a signi cant decrease of its surface area. Moreover, deposition of carbonaceous compounds on its surface was detected, which could have inhibited the catalytic activity.