Effect of Water Content on Product Distribution of Base-Catalyzed Transesterification

Biodiesel is an environmentally friendly fuel which can be economically produced by the use of waste culinary oil as raw material and NaOH as catalyst. However, the moisture in waste culinary oil or solid NaOH can affect the distribution of final products. In this paper, the water content of solid NaOH and waste culinary oil were determined to be 4.7 and 1.0 % respectively. A simulated transesterification system of methyl butyrate and n-butanol was catalyzed by anhydrous NaOH which was sintered at 800 °C for 2 h. The moistures in reaction system were imitated by contrived addition of water. Experimental results show that when the water content is 0.25 %, the yield of transesterification achieves the highest, simultaneously, saponification remains at the minimum level. The soybean oil and methanol were investigated as exemplary biodiesel system. The results show that when the water content is 1 %, the yield of biodiesel reaches 98.81 %, which is the highest.