Catalytic upgrading of bio oil model compound into polyol ester via green alginate catalyzed esterification reaction

Abstract

Abstract Recent studies have successfully synthesized polyol ester of vegetable oil origin for the application of biolubriant, which though biodegradable, met with the challenge of food chain disruption. Therefore, biomass-derived bio oil is a potential alternative for the production of polyol ester in the application of biolubricant production. Due to its high oxygen content and low storage stability, further upgrading process such as esterification is necessary before bio oil is ready to be used as biolubricant. Acetic acid (AcA), a major component found in bio oil was used for the catalytic esterification with neopentyl glycol (NPG) in the presence of bio-polymer acid catalyst, aluminium alginate (Al-A) and ferric alginate (Fe-A). Surface morphological study reveals Al-A has higher surface area as the surface is rough and wrinkled as compared to the more compact surface of Fe-A. TPD-NH 3 shows acidity of Al-A is 1.5 times higher than Fe-A. Catalytic activity screening test showed that Al-A catalyzed esterification renders highest polyol ester yield of 100% (monoester: 40.2% and diester: 59.8%) under 15 wt% of catalyst, 6 h, 0.5:1 molar ratio of NPG:AcA and 100 °C, as compared to Fe-A catalyst. The presence of Lewis acid site from Al 3+ ion played a major role in esterification process. In additional, the Al-A catalyst rendered significant reusability up to 3 consecutive cycles with ester yield above 85%.