Chemo-enzymatic epoxidation of rapeseed methyl esters: Parameters influencing the reaction and enzyme stability

The chemo-enzymatic epoxidation of rapeseed methyl ester (RME) in a solvent-free medium was studied using the immobilized Candida antarctica lipase B (Novozym® 435) as catalyst. Hydrogen peroxide (H2O2) was used as the oxygen donor. The enzyme cost is an important factor determining the economics of the process. High enzyme stability and the possibility to recycle the enzyme are therefore highly desirable. The stability of the enzyme was studied for initial H2O2 concentration in the water phase of 5, 10 and 20% (w/w). The epoxidation rate increased with increasing H2O2 concentration, however at the expense of enzyme inactivation. A temperature increase has a similar effect: the reaction rate increases but the remaining enzymatic activity is reduced. The epoxidation of RME was also performed with continuous addition of H2O2 solution. Maintaining an approximately constant concentration of H2O2 in the water phase of 15 M, at 40°C and with an enzyme loading of 3%, a conversion of 83% was obtained after 14 hours with a remaining enzymatic activity of 61%.