Esterification and transesterification of palm fatty acid distillate in chitosan membrane reactor

Abstract

Biodiesel from palm fatty acid distillate (PFAD) with FFAs of 87.1 ± 1.3 wt% was studied in a 2-litres chitosan membrane reactor. The reactor used in this study comprised of three parts; i.e., upstream side for reaction, membrane cell and downstream side connecting with a vacuum pump. The feed was operated under esterification reaction followed by transesterification reaction without intermediate washing. Flat sheet symmetric dense uncrosslinked chitosan membrane was used preferably in the laboratory 2-litres reactor. Operating the reactor under the pervaporation process, the optimum esterification condition was at 1:15 of PFAD to methanol ratio, 2.0 wt% H2SO4 and 20 ml/min methanol feed rate for 120 min. The FFA and methyl ester contents in the esterification product were 1.09 ± 0.03 and 85.9 ± 0.1 wt%, respectively. On the transesterification condition at 1:6 of PFAD to methanol ratio, 1.0 wt% NaOH and 20 ml/min methanol feed rate for 60 min, the methyl ester was increased to 97.9 ± 0.0 wt%. On performance and potential application, an 8-litres reactor installing a set of membrane modules was studied. Several membrane modules with flat sheet reinforced crosslinked composite chitosan membranes were installed in the pilot 8-litres reactor. Together with operating the reactor under the pervaporation process, the esterification was operated at 1:15 of PFAD to methanol ratio and 1.5 wt% H2SO4 for 180 min followed by the transesterification reaction at 1:6 of PFAD to methanol ratio and 1.0 wt% NaOH for 60 min without intermediate washing. The methyl ester yield of 96.6 ± 0.02 wt% was obtained.