Sains Malaysiana 39(5)(2010): 805-809

 

Optimization of Process Parameters for Alkaline-Catalysed Transesterification of Palm Oil Using Response Surface Methodology

(Pengoptimuman Parameter Proses untuk Transesterifikasi Minyak Sawit Bermangkin Alkali Menggunakan Kaedah Sambutan)

 

N. Razali, H. Mootabadi, B. Salamatinia, K.T. Lee & A.Z. Abdullah*

School of Chemical Engineering, Universiti Sains Malaysia

Engineering Campus, Seri Ampangan

14300 Nibong Tebal, Penang, Malaysia

 

Received: 14 April 2009 / Accepted: 18 December 2009

 

ABSTRACT

 

Biodiesel (fatty acid methyl esters) was synthesized from direct transesterification of vegetable oils, where the corresponding triglycerides react with methanol in the presence of a suitable catalyst. The alkali catalysts are the most common catalyst used in biodiesel industry, because the process proves faster and the reaction conditions are moderate compared to the acid catalyst. In the present study, biodiesel production using heterogeneous alkaline-catalysed transesterification process (KOH supported on SBA 15) was proposed. The influence of reaction temperature x1 (50 – 90 oC), ratio of  methanol to oil, x2 (6:1 – 14:1 mol/mol), amount of catalyst, x3 (1 – 5wt.%), and reaction time, x4 (2 – 6 h) to the reaction was studied. These four conditions were studied using design of experiment (DOE), based on four-variable central composite design (CCD) with α = 2. The process variables were optimised using the Response Surface Methodology (RSM) in obtaining the maximum yield of biodiesel. This method was also applied to determine the significance and interaction of the variables affecting the biodiesel production. The biodiesel produced in the experiment was analysed by gas chromatography, which considered five major fatty acid methyl esters. The optimal conditions of response were found to be 70 oC for reaction temperature, 11.6 wt/wt of ratio methanol to oil, 3.91wt.% of weight of catalyst and 5 h for reaction time with 93% of biodiesel yield for predicted value and 87.3% from experimental.

 

Keywords: Base catalyst; biodiesel; response surface methodology

 

ABSTRAK

 

Biodiesel telah disintesis daripada transesterifikasi langsung minyak sayuran yang melibatkan trigliserida bertindak balas dengan metanol dengan kehadiran mangkin yang sesuai. Mangkin beralkali adalah mangkin yang biasanya digunakan di dalam industri biodiesel kerana proses terbukti lebih cepat dan keadaan tindak balas sederhana berbanding dengan mangkin berasid. Dalam kajian ini, penghasilan biodiesel menggunakan proses transesterifikasi bermangkinkan heterogen beralkali (KOH disokong di atas SBA-15) telah dikaji. Kesan suhu tindakbalas, x1 (50 – 90 oC), nisbah metanol kepada minyak, x2 (6:1 – 14:1 mol/mol), berat mangkin, x3 (1 – 5wt.%), dan masa, x4 (2 – 6 h) terhadap tindak balas dikaji. Empat keadaan ini telah dikaji menggunakan reka bentuk eksperimen (DOE) berdasarkan kepada empat pembolehubah reka bentuk gabungan berpusat (CCD) dengan α = 2. Pembolehubah proses telah dioptimumkan menggunakan kaedah sambutan permukaan (RSM) dalam mendapatkan hasil biodiesel yang maksimum. Kaedah ini juga digunakan untuk menentukan kepentingan dan interaksi pembolehubah-pembolehubah yang mempengaruhi hasil biodiesel. Biodiesel yang dihasilkan telah dianalisis melalui kromatografi yang mengambilkira lima metil ester asid lemak utama. Keadaan optimum sambutan didapati pada suhu tindak balas 70 oC, nisbah metanol kepada minyak 11.6 mol/mol, berat mangkin 3.91 wt.% dan 5 jam masa tindak balas dengan 93% hasil keluaran biodiesel untuk nilai jangkaan dan 87.3% daripada eksperimen.

 

Kata kunci: Biodiesel; kaedah sambutan permukaan; mangkin beralkali

 

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*Corresponding author; email: chzuhairi@eng.usm.my

 

 

 

 
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