Screening of procedures catalyzed by lipase transesterification in non-aqueous solvents

Biodiesel production catalyzed by Novozyme 435 was optimized using Plaekett-Burman design and response surface methodology. Firstly, Plaekett-Burman was employed to screen the main efficient parameters on conversion rate from enzyme dosage, reaction temperature, tert-butanol amount, oil/alcohol molar ratio and molecular sleves added amount. Then, the steepest ascent experiments were carried out to approach the optimal conditions. Finally, the optimized conditions were addressed with three-factor-three-level response surface methodology. The results showed that the optimized conditions were: lipase dosage 3 wt% (based on oil weight), temperature 40 °C, tert-butanol added amount 38.7 % (based on oil volume, v/v), molecular sleves added amount 11.9 wt% (based on oil weight) and molar ratio of methanol to oil 4.77:1. Under the optimized conditions, the biodiesel yield was estimated to be 97.69 %. The proposed model on conversion rate had a satisfactory coefficient of R² (= 98.34 %) and was experimentally verified. The Novozyme 435 exhibited high operational stability in non-aqueous. After 10 cycles (160 h) successively, the activity of combined lipases maintained 90 % of its original activity.