Thesis (M.Eng.)--Chulalongkorn University, 2007

To investigate the production of methyl ester by two step method. Palm stearin and fatty acids were used as raw materials and were mixed at a ratio of 10%, 15% and 25% of free fatty acids. The experiments were carried out in a batch reactor using sulfuric acid as a catalyst in the first step and potassium hydroxide in the second step. The experiments were conducted at the temperature of 60°C and at atmosphere’s pressure. Reaction time, methanol to oil ratio and amount of catalysts were varied in each experiment. The suitable conditions on acid esterification process were 300% mole of excess methanol from its stoichiometric ratio in the presence of 2% wt H2SO4 as a catalyst and at the reaction time of 70 minutes. High free fatty acids level was reduced to less than 2% in the first step. Acid catalyst can simultaneously catalyze both esterification of free fatty acids and transesterification of triglyceride. The suitable conditions on transesterification process were 100% mole of excess methanol from its stoichiometric ratio in the presence of 1% wt KOH as a catalyst in the second step. Final methyl ester was higher than 85% concentration within 60 minutes.