Simulation of enzymatic ethyl esters production in non-isothermal semi batch reactor

In the production of biodiesel esters by enzymatic transesterification of vegetable oils using batch reactor, lipase inactivation by temperature and alcohol indicates that new reactor configurations should be searched for reaching high yields which are relevant to larger scale production.

The objective of this work was to compare the simulation of ethyl esters production in batch and semi batch reactors with Burkholderia cepacialipase transesterification of canola oil with ethanol, taking into consideration the enzyme inactivation by temperature and irreversible inhibition by ethanol. Simulation was carried out with the software MATLAB, making the reaction temperature variable with time and using variable ethanol feed in the system.

The results showed that a linear increase in temperature exhibited higher esters yields than the isothermal batch system. After 72 h of reaction, the isothermal batch reactor at 60 °C reached an oil conversion of 58%, while the same reactor with a linear increase in temperature from 25 to 60 °C showed a conversion of 74%. This results due to the fact that lipase has low thermostability.  In relation to ethanol concentration, the batch reactor showed a maximum oil conversion of 92% at ethanol to oil molar ratio of 4.5:1, while a semi batch reactor showed a maximum conversion of 97% with an increasing molar ratio that reached 18:1 at the end of the reaction.

Therefore, this study allowed concluding that the use of a semi batch reactor with time increasing temperature and ethanol concentration, give higher esters yields than a batch reactor.