Reaction conditions effect and pathways in the oxidative steam reforming of raw bio-oil on a Rh/CeO2-ZrO2 catalyst in a fluidized bed reactor

Abstract

A reaction scheme has been proposed for the oxidative steam reforming (OSR) of raw bio-oil on a Rh/CeO2-ZrO2 catalyst, based on the study of the effect reaction conditions (temperature, space time, oxygen/carbon ratio and steam/carbon ratio) have on product yields (H2, CO, CO2, CH4, hydrocarbons). The runs were performed in a two-step system, with separation of pyrolytic lignin (first step) followed by catalytic reforming in a fluidized bed reactor (second step), under a wide range of reaction conditions (600–750 °C; space time, 0.15–0.6 gcatalysth/gbio-oil; oxygen to carbon molar ratio (O/C), 0–0.67; steam to carbon molar ratio (S/C), 3–9). The catalyst is very active for bio-oil reforming, and produces high H2 yield (between 0.57 and 0.92), with low CO yield (0.035–0.175) and CH4 yield (below 0.045) and insignificant light hydrocarbons formation. The proposed reaction scheme considers the catalyzed reactions (reforming, water gas shift (WGS) and combustion) and the thermal routes (decomposition/cracking and combustion). The deactivation of the catalyst affects progressively the reactions in the following order: CH4 reforming, hydrocarbons reforming, oxygenates reforming, combustion and WGS.