Pyrolysis of palm fronds waste into bio-oil and upgrading process via esterification-hydrodeoxygenation using Cu–Zn metal oxide catalyst loaded on mordenite zeolite

Abstract

Bio-oil from the pyrolysis of palm fronds waste has potential to be used as an alternative fuel. However, due to its poor physicochemical properties, it requires further treatment to improve its overall quality. In this study, the conversion of palm fronds waste into bio-oil was carried out using the semi-fast pyrolysis at 500 °C and continued with esterification and hydrodeoxygenation (HDO). Metal oxides of Cu and Zn with a zeolite carrier mordenite (Mor) were used as bifunctional catalysts in the HDO reaction performed in a fixed-bed system reactor with temperature variations (250, 300, and 350 °C) for 2 h. Upgraded bio-oil (UBO) products at optimum conditions were analyzed for their physicochemical properties. In the pyrolysis process, the highest bio-oil conversion of 46.3% was obtained at a sample size of 60 mesh with the main component of furan compounds (46.31%). In the upgrading process through the esterification pretreatment, the optimum condition of HDO was determined to be at 300 °C, this can be seen from the high yield of liquid phase products produced on each catalyst (Mor; 89.85%, and CuO-ZnO/Mor; 88.25%). The physicochemical properties of upgraded bio-oil obtained under optimum conditions showed an increase in the quality of bio-oil with a decrease in water content (up to 23%), an increase in higher heating value (HHV) (up to 14.67% in CuO-ZnO/Mor). It is known that HDO with CuO-ZnO/Mor catalyst has a higher selectivity than Mor catalyst in converting aromatic hydrocarbon compounds such as methyl cyclohexane which is a potential component of a fuel.