The Optimization Conditions of Polyhydroxybutyrate Methyl Ester from Polyhydroxybutyrate via Acid-Catalyst

Recently, microbial polyhydroxyalkanoates (PHA) were proposed as an alternative biofuel, termed 3-hydroxyalkanoate methyl ester (3HAME). PHA is a strong candidate to make biofuels and be used in the fuel additive market today. However, an optimization study of 3HAME from PHA has never been reported. In this paper, 3HBME was produced from polyhydroxybutyrate (PHB) via acid catalyst. The effects of acid types and concentration, alcohol, reaction temperature and time were determined. The optimal conditions for 3HBME production were methanol with 10% (v/v) H2SO4 under a reaction temperature and a time of 67°C and 50 h, respectively. The highest yield of 3HBME (70.7%) was obtained under these optimal conditions. 3HBME was further characterized for chemical and fuel related properties following ASTM. The characteristics of 3HBME including acid value, free fatty acid, saponification and molecular mass were 2.16, 0.0098, 60.27 and 2792.434, respectively. The 3HBME properties were also compared with Thailand and ASTM standards. Almost all of the properties passed these standards.