TRANSESTERIFICATION OF VEGETABLES OIL USING SUBAND SUPERCRITICAL METHANOL

Abstract

A benign process, non catalytic transesterification in sub and supercritical methanol method was usedto prepare biodiesel from vegetables oil. The experiment was carried out in batch type reactor (8.8 mlcapacity, stainless steel, AKICO, JAPAN) by changing the reaction condition such as reactiontemperature (from 210°C in subcritical condition to 290°C in supercritical state with of 20°Cinterval), molar ratio oil to methanol (1:12-1:42) and time of reaction (10-90 min). The fatty acidmethyl esters (FAMEs) content was analyzed by gas chromatography-flame ionization detector (GCFID).Such analysis can be used to determine the biodiesel yield of the transesterification. The resultsshowed that the yield of biodiesel increases gradually with the increasing of reaction time atsubcritical state (210-230oC). However, it was drastically increased at the supercritical state (270-290oC). Similarly, the yield of biodiesel sharply increased with increasing the ratio molar of soy oilmethanolup to 1:24. The maximum yield 86 and 88% were achieved at 290oC, 90 min of reaction timeand molar ratio of oil to methanol 1:24, for soybean oil and palm oil, respectively.Proses transesterifikasi non katalitik dengan metanol sub dan superkritis,merupakan proses yang ramah lingkungan digunakan untuk pembuatan biodiesel dari minyak nabati.Percobaan dilakukan dalam sebuah reaktor batch (kapasitas 8,8 ml, stainless steel, AKICO, JAPAN),dengan variabel kondisi reaksi seperti temperatur reaksi (dari kondisi subkritis 210°C-kondisisuperkritis 290°C dengan interval 20°C), rasio molar minyak-metanol (1:12-1:42) dan waktu reaksi(10-90 menit). Kandungan metil ester asam lemak (FAME) dianalisis dengan kromatografi gasdengan detektor FID (GC-FID). Hasil Analisis tersebut dapat digunakan untuk menentukan yieldbiodiesel dari proses transesterifikasi. Hasil penelitian menunjukkan bahwa yield biodiesel meningkatsecara perlahan dengan meningkatnya waktu reaksi pada keadaan subkritis (210-230oC). Namun,yield biodiesel meningkat secara drastis pada kondisi superkritis (270-290oC). Demikian pula halnyadengan rasio molar minyak kedelai-metanol, dimana hasil biodiesel meningkat tajam denganmeningkatnya rasio molar minyak-metanol hingga 1:24. Yield maksimum dicapai pada 290oC, waktureaksi 90 menit dan rasio molar minyak terhadap metanol 1:24, yaitu sebesar 86% untuk minyakkedelai dan 88% untuk minyak sawit.

Keywords

• free catalyst
• sub-and supercritical methanol
• transesterification
• vegetables oil