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

TY - JOUR

T1 - Analysis and optimisation of a microwave-assisted hydrothermal process for the production of value-added chemicals from glycerol

AU - Remón, Javier

AU - Zhu, Guangya

AU - Budarin, Vitaliy L.

AU - Clark, James H.

PY - 2018/6/7

Y1 - 2018/6/7

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85048054292&partnerID=8YFLogxK

U2 - 10.1039/c8gc01079j

DO - 10.1039/c8gc01079j

M3 - Article

AN - SCOPUS:85048054292

SN - 1463-9262

VL - 20

SP - 2624

EP - 2636

JO - Green Chemistry

JF - Green Chemistry

IS - 11

ER -