Esterification and neutralization of bio-oil from palm empty fruit bunch fibre with calcium oxide

Abstract Bio-oil from fast pyrolysis of biomass is considered as a potential drop-in fuel and a source of chemicals. Nonetheless, the high acid content in bio-oil challenges storage and further downstream processes. The current study investigated a combination of esterification and neutralization reactions for intrinsic acids in bio-oil by treating with MeOH in presence of CaO. CaO can have two roles: as a catalyst in esterification and as an alkaline agent in neutralization. Even though methanol reduced the acidity of bio-oil, the presence of CaO enhanced the reduction. This is because of a combined effect of esterification and neutralization reactions. 98% of acids in the bio-oil was converted in the presence of 5 wt% of CaO and MeOH/bio-oil ratio of 0.5. Further analysis showed that neutralization reaction was dominant over esterification for acid conversion.