Utilization of biochars as sustainable catalysts for upgrading of glycerol from biodiesel production

Abstract

Abundant bioglycerol generated via transesterification of triglycerides was used to synthesize valuable glycerol carbonate, GC. This was achieved by pyrolyzing cow dung (CDB) and fish scale (FSB) biowastes at various temperatures (500 °C to 750 °C) and utilizing the obtained biochar catalysts to propagate the synthesis of GC. The results indicate that pyrolysis temperature promoted the biochars basicity and the catalytic activity. Also, the FSB biochar catalytic activity was limited by the nature or amount of surface basicity and was significantly improved when 3 wt.% potassium fluoride (KF) was added. The highest catalytic activity for KF modified FSB (>96% GC yield) was achieved under 60 min reaction time at a mild reaction condition of 85 °C and DMC/glycerol molar ratio of 2. Also, the CDB catalyst presented similar GC yield under similar conditions with longer reaction time (90 min). The biochars could be reused in four consecutive reaction cycles without serious deactivation.