Dimethyl carbonate assisted catalytic esterification of palm fatty acid distillate using catalyst derived from spent bleaching clay

Abstract

Herein, we utilized environmental waste products, palm fatty acid distillate (PFAD) and spent bleaching clay (SBC) from the palm oil refining industry as cheap feedstock and catalyst support, respectively, for glycerol-free biodiesel production. Dimethyl carbonate (DMC), regarded as a suitable environmental alternative to methanol in producing glycerol-free biodiesel, was used as the methylating agent. Reactions were carried out using a heterogeneous acid catalyst derived from SBC after calcination and sulphonation. The obtained solid acid catalyst was characterized using Fourier transform infrared spectroscopy (FT-IR), Thermogravimetric analysis (TGA), Field emission scanning electron microscopy (FESEM), Brunauer-Emmett-Teller (BET) and Energy dispersive X-ray (EDX) techniques. The experimental results revealed that the synthesized solid acid catalyst efficiently converted free fatty acids (FFA) present in PFAD to fatty acid methyl esters (FAMEs). The maximum conversion efficiency of 93.18% was obtained at optimum reaction conditions: catalyst amount 10 w/w%, reaction time 4 h, reaction temperature 100 °C and PFAD/DMC molar ratio 1:10. A mechanism for the esterification reaction between PFAD and DMC using the sulphonated SBC catalyst was also proposed. This study has established the esterification of PFAD experimentally with DMC using the synthesized sulphonated SBC catalyst.