Intensification of waste cooking oil transformation by transesterification and esterification reactions in oscillatory baffled and microstructured reactors for biodiesel production

Abstract

The transformation of waste cooking oils for fatty acid methyl ester production is investigated in two intensified technologies: microstructured Corning® and oscillatory baffled NiTech® reactors, compared to a reference batch reactor to quantify the process intensification provided by each technology. Both reactors achieve high conversions in shorter times. For transesterification, 96 wt.% of esters are obtained in 1.4 min at 97°C in the Corning® reactor and 92.1 wt.% of esters in 6 min at 44°C in the NiTech® reactor, compared with 94.8 wt.% of esters in 10 min at 60°C in the batch reactor. For esterification, 92% conversion is obtained in 2.5 min in the Corning® reactor at 75°C compared with 20-30 min in the batch reactor at 60°C, and at 40°C, 96.8% conversion is achieved in 13.3 min in the NiTech® reactor, compared with 30 min in the batch reactor. The advantage of the Corning® reactor is that it can operate at higher pressures (1-20 bar) and temperatures (100°C), thereby providing faster kinetics than the NiTech® reactor. However, oils with a high free fatty acid level (73%) cause the Corning® reactor channels to be blocked. A wider range of operating conditions could be obtained in NiTech® with a pressure-resistant material.