Catalytic upgrading of the heavy fraction of waste coffee grounds pyrolysis bio-oil using supercritical ethanol as a hydrogen source to produce marine biofuel

Biomass pyrolysis oil has the potential to serve as a sustainable fuel in the maritime sector, either through the production of marine biofuel or as fuel blends. However, the production of biofuels with high energy value and low oxygen content during the upgrading process calls for a more in-depth understanding. Herein, the heavy fraction of bio-oil was upgraded in supercritical ethanol in order to produce a biofuel which can be used as an alternative for heavy fuel oil (HFO). The impact of distinct operational factors such as temperature, holding time, and amount of catalyst was experimentally evaluated on the upgrading process. Using an MgNiMo/SAPO-11 catalyst, the supercritical ethanol upgrading of CG-BO heavy fraction at 325 °C and 4 h reaction time yielded a biofuel product with a 63.2 % yield, 0.07O/C ratio and high heating values over 39 MJ/kg. The prevailing fractions observed in the upgraded bio-oil primarily encompassed esters and hydrocarbons.