Improvement of Immobilized Lipase-Catalyzed Methanolysis of Tributyrin Using Methyl Acetate

Transesterification by methanol and interesterification by methyl acetate were performed simultaneously, and the advantages of using methyl acetate with methanol were investigated in the enzymatic production of methyl ester from tributyrin. It was observed that 100% excess amount (1:6 mol ratio) of methanol/methyl acetate makes no negative effect on the enzyme activity. The initial reaction rate decreases as the tributyrin concentration increases. Consequently, tributyrin causes an inhibition at high concentrations. When the tributyrin concentration was used above the stoichiometric ratio (1:3 mol ratio), it decreased the activity of the enzyme. Michaelis−Menten parameters ( K m ) for tributyrin and methanol/methyl acetate were calculated as 0.1 and 50 M, respectively. An uncompetitive substrate inhibition constant for tributyrin was determined as 22.42 M. Experimental results were found to correlate well with the results of the kinetic model according to the ping-pong bi−bi mechanism. High conversions up to 90% were observed in a semi-continuous fluidized bed with low enzyme levels (1%). Conversions decreased with increasing flow rates.