Sintesis Metil Ester Minyak Kelapa Sawit Mengggunakan Katalis Abu Kulit Kakao pada Variasi Waktu dan Rasio Molar Menggunakan Pendispersi Homogen

Abstract

Methyl ester from palm oil (RBD palm olein) has been synthesized through a transesterification reaction using cocoa shell ash (Theobroma cacao) as a heterogeneous catalyst. Cocoa shell powder was analyzed using Thermogravimetric Analysis (TGA), then calcined at 750oC for 4 hours then the ash obtained was analyzed using X-Ray Diffraction (XRD), X-Ray Fluorescence (XRF), Scanning Electron Microscope (SEM) and Fouries Transform Infrared (FT-IR) Spectrophotometer. The analysis results showed that cocoa shell ash contained 88.81% K2O compounds. The reaction conditions carried out in this study were variations in reaction time (5, 10, 20, 30, and 40 minutes) and molar ratio of oil: methanol (1:9, 1:12, 1:15, 1:17, and 1: 19) at a stirring speed of 6000 rpm, and a catalyst weight of 7% (w/w). The conversion of methyl esters was analyzed using Gas Chromatography (GC) and the change in functional groups from oil to methyl esters was measured using an FT-IR spectrophotometer. The highest conversion and yield of methyl ester for reaction time was obtained at 96.19 ± 0.24% and 96.12 ± 2.01%, namely at a reaction time of 20 minutes, molar ratio 1:15, stirring speed 6000 rpm, and catalyst weight 7% w/w. The highest conversion of methyl ester for the molar ratio of palm oil to methanol was obtained at 96.19 ± 0.24%, namely at a molar ratio of 1:15, catalyst weight of 7%, stirring speed of 6000 rpm, and reaction time of 20 minutes. The highest yield of methyl ester for the molar ratio of palm oil to methanol was obtained at 97.22% ± 1.50%, namely at a molar ratio of 1:17, catalyst weight of 7%, stirring speed of 6000 rpm, and reaction time of 20 minutes. The formation of methyl ester is characterized by differences in the shape of the stretching vibration peak -C-O-C- at wave numbers 1300-1000 cm-1 where in oil the strongest absorption of the 3 peaks is in the second position (middle) while in methyl ester the strongest absorption appears at rightmost position.