Steam reforming of upgraded bio-oil aqueous phase fraction from sunflower seed hulls: Thermodynamic analysis

Abstract

This work focuses on the study of hy-drogen production process departing from waste lig-nocellulosic biomass. The bio-oil was first obtained by non-catalytic fast pyrolysis of sunflower seed hulls. Subsequently, it was upgraded to reduce the concen-tration of higher molecular weight compounds by wa-ter addition and mixing. A 1/1 bio-oil: water ratio was selected here. Later, a thermodynamic analysis based on free energy minimization was profited to study the steam reforming process of the upgraded bio-oil sample. The influence of the operation temperature on the reforming was analyzed. The highest hydrogen yields were obtained at ~740°C. A comparison with acetic acid used as model compound of the bio-oil is included. Results show that acetic acid is not a good ap-proximation of a real aqueous phase of upgraded bio oil fraction. The study concludes with an analysis on the energetic efficiency, showing that its maximum is presented at lower temperatures than the maximum yield, due to the thermal requirements of preheating.