Bio-based sorbitol azelaic acid ester synthesis through germanium (IV) oxide catalysed esterification

Conventionally, polyurethane (PU) is derived from the non-renewable petroleum feedstocks, polyol polyester and di-isocyanate. Bio-based polyol polyester is an alternate to reduce the environmental impacts of the petroleum-based polyol polyester. Bio-based reactants, sorbitol (SL) and azelaic (AA) acid were used in the esterification to produce sorbitol azelaic acid ester (SAAE) using germanium (IV) oxide (GeO2) as a catalyst. The experimental studies set at various operating conditions were conducted to determine the best operating condition that gave product with highest AA conversion and acceptable colour. The best operating condition was achieved at a temperature of 200°C, SL/AA reactant ratio of 4:1 and catalyst loading of 0.5 wt%, with the corresponding AA conversion of 90.10%. The kinetic data was well fitted to the Langmuir Hinshelwood Hougen Watson (LHHW) model with the corresponding activation energy of 11.55 kJ/mol.