Optimization and kinetics of biodiesel production from soybean oil using new tetraethylammonium ionic liquids with amino acid-based anions as catalysts

By using amino acids (AAs) as anions, eleven ionic liquids composed of tetraethylammonium (N-2222) as a cation were synthesized, namely, [N-2222][AA]s. Their structures were characterized by FT-IR and NMR. The alkalinity of the synthesized AAILs was measured using a pH meter. In the transesterification reaction of soybean oil with methanol, tetraethylammonium arginine ([N-2222][Arg]) presented the best catalytic capability. The optimal reaction conditions for the transesterification reaction of soybean oil to achieve 98.4% biodiesel conversion were a methanol/oil of 10:1 mol/mol, reaction temperature of 100 degrees C, catalyst dosage of 20 wt% (based on the oil weight) and reaction time of 60 min. The kinetics study was evaluated and followed the pseudo-first order reaction mechanism, and the activation energy and pre-exponential factor were 34.53 kJ/mol and 1.21 x 10(4) min(-1), respectively. [N-2222][Arg] is a promising, operationally simple, sustainable, biodegradable and possibly renewable catalyst for the conversion of vegetable oil or animal fat into biodiesel.

Automated summary

Eleven ionic liquids composed of tetraethylammonium and amino acids were synthesized and evaluated for their catalytic capability in transesterification reactions. Tetraethylammonium arginine showed the highest catalytic activity. By adjusting the reaction conditions, a biodiesel conversion rate of 98.4% was achieved in 60 minutes.