Analysis and optimisation of a microwave-assisted hydrothermal process for the production of value-added chemicals from glycerol

Javier Remón*, Guangya Zhu, Vitaliy L. Budarin, James H. Clark

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


This work addresses an alternative and green route for glycerol upgrading recently highlighted as a potentially critical aspect of the economic and environmental viability of future biodiesel-based bio-refineries. For the first time we report the microwave-assisted hydrothermal process, examining the effects of the temperature (150-250 °C), pressure (50-120 bar), reaction time (0-2 h) and catalyst mass (5-15 wt%; Ni-Co/Al-Mg) during the upgrading of a 30 wt% glycerol solution. The global glycerol conversion and the carbon converted to gas and liquids varied by 5-54%, 0-21% and 3-42%, respectively. Increasing the temperature, reaction time and/or catalyst amount increased glycerol decomposition due to the positive kinetic effects that these variables have on the process. The pressure exerted two counteracting effects: a positive kinetic effect and a thermodynamic inhibitory influence; this latter being accounted for by the lower dielectric loss factor of water at high pressures. The liquid phase was made up of monohydric (10-62 wt%) and polyhydric (0-46 wt%) alcohols, carboxylic acids (0-9 wt%) and C3-ketones (0-80 wt%). Monohydric alcohols and C3-ketones were the most abundant compounds in the liquid when short reaction times and/or low catalyst amounts were used. An increase in these operating variables increased the concentration of polyhydric alcohols and decreased the amount of C3-ketones. The production of C3-ketones (72 wt%) could be maximised using a medium temperature (210 °C) and low pressure (50 bar) and catalyst mass (5 wt%) for a long reaction time (2 h). Around 40% of the glycerol can be purely converted to monohydric (79 wt%) and polyhydric (21 wt%) alcohols by employing a temperature of 250 °C, a pressure of 83 bar and a catalyst mass of 10 wt% for 2 h.

Original languageEnglish
Pages (from-to)2624-2636
Number of pages13
JournalGreen Chemistry
Issue number11
Early online date15 May 2018
Publication statusPublished - 7 Jun 2018

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