Co-pyrolysis of biodiesel-derived glycerol with Greek lignite: A laboratory study

The study has investigated the potential utilization of crude glycerol, generated from the biodiesel production Greek plants, as potential alternative fuel via co-processing with Greek lignite in existing combustion or gasification plants, looking forward to alleviate biodiesel production cost and to manage by-products by substituting conventional fuels. Fast pyrolysis was performed in this study in order to gain a further insight into the fluidized bed gasification/combustion process. Co-pyrolysis of lignite with crude glycerol performed batch-wise, in a laboratory scale, non-continuous, captive sample, wire mesh reactor, at atmospheric pressure. The process was performed at an average heating rate over the range of 300–1000 °C/s and a reaction time of 0.5 s, by varying temperature (650, 750 and 850 °C) and feedstock composition (15 wt% and 20 wt%, of crude glycerol in the blend with lignite). Pyrolysis of blends of glycerol with lignite resulted in high hydrogen yield (65.44 v/v%) normalized, for the blend of 20 wt% glycerol at 850 °C, making evident that co-pyrolysis of crude glycerol with lignite could be a source for H2 production.

► Sustainability of small scale biodiesel units urges glycerol valorization. ► Fast pyrolysis gives an insight into the gasification/combustion process. ► Crude glycerol in lignite enhances pyrolysis conversion. ► Pyrolysis of crude glycerol with lignite resulted in high hydrogen yield.