Oleic Acid Esterification Catalyzed By Zeolite Y-Model of the Biomass Conversion

Abstract

Residual oils and fats are promising renewable sources for the production of liquid fuels and the synthesis of various chemicals with significant life cycle and large-scale economic advantages over other biomass sources. Thus, oleic acid esterification was investigated on zeolites type FAU and sulfuric acid by kinetic, spectroscopic assessments and theoretical calculations using a hybrid ONIOM scheme. In the catalytic tests, the solid catalyst with the highest Si/Al (H-Y-80) ratio showed the highest catalytic activity for esterification (92% conversion) as compared to H-Y-5.2 (66% conversion), Na-Y (15% conversion) and homogeneous acid catalysis (89% conversion). The catalytic activity between different acid catalysts is discussed. It was observed that the acidity of the active sites and the hydrophobicity resulting from the Si/Al molar ratio influence the esterification conversion. Theoretical calcultations predicts that the voluminous confined space of the FAU zeolite perfectly accommodates the oleic acid molecule in the adsorption step (Eads= -25.5 kJ mol-1) and the van der Waals interactions of the zeolite walls with the aliphatic chain help to accommodate the bulky molecule between the supercages. Experimental and theoretical results confirm that H-Y-80 zeolite applied in the esterification reaction can be an efficient catalyst in processes involving conversion of unsaturated fatty acids.