Fatty acid methyl esters production with glycerol metal alkoxide catalyst

Abstract

Metal hydroxides and alkoxides are popular base catalysts for production of fatty acid methyl esters (FAME). Hydroxides dissolved in alcohols produce water. Some of that water reacts with triacylglycerols (TAGs) to produce free fatty acids instead of desired FAME, thus decreasing the yield of the transesterification reaction. Metal alkoxides are expensive, their production is hazardous and energy intensive, therefore, less expensive safer and more efficient catalysts for transesterification are desirable. Glycerol derived non‐toxic alkoxide base catalysts were synthesized by heating KOH solution (50 wt%) and glycerol at three different mole ratios (KOH: glycerol, denoted KGly, at 1:1, 2:1, and 3:1) under four different vacuum pressures. Transesterification reactions were conducted. The reaction rate and yield of FAME synthesis from TAG achieved by catalyst prepared at 3:1 mole ratio of KOH: glycerol achieved superior or similar FAME yield to conventional potassium methoxide catalyst under same reaction conditions. At 120 s after adding catalyst, the reactions achieved satisfactory yield (74.3–78.9%) which was similar to that of KOCH3 catalyst (77.9%). The reactivity of catalyst at initial stage of the reaction was in the following order: KGly (1:1) < KGly (2:1) < KOCH3 < KGly (3:1).Glycerol derived non‐toxic alkoxide base catalysts were synthesized by heating KOH solution (50 wt%) and glycerol at three different mole ratios (KOH: glycerol, 1:1, 2:1, and 3:1) under four different vacuum pressures. The catalysts were used for transesterification reaction and the catalyst prepared at 3:1 mole ratio achieved superior or similar FAME yield to conventional potassium methoxide catalyst.