Key role of temperature monitoring in interpretation of microwave effect on transesterification and esterification reactions for biodiesel production.
Microwave effects have been quantified, comparing activation energies and pre-exponential factors to those obtained in a conventionally-heated reactor for biodiesel production from waste cooking oils via transesterification and esterification reactions. Several publications report an enhancement of biodiesel production using microwaves, however recent reviews highlight poor temperature measurements in microwave reactors give misleading reaction performances. Operating conditions have therefore been carefully chosen to investigate non-thermal microwave effects alone. Temperature is monitored by an optical fiber sensor, which is more accurate than infrared sensors. For the transesterification reaction, the activation energy is 37.1kJ/mol (20.1-54.2kJ/mol) in the microwave-heated reactor compared with 31.6kJ/mol (14.6-48.7kJ/mol) in the conventionally-heated reactor. For the esterification reaction, the activation energy is 45.4kJ/mol (31.8-58.9kJ/mol) for the microwave-heated reactor compared with 56.1kJ/mol (55.7-56.4kJ/mol) for conventionally-heated reactor. The results confirm the absence of non-thermal microwave effects for homogenous-catalyzed reactions.
Laboratoire de Génie Chimique CNRS/INPT/UPS, University of Toulouse, 4 Allée Emile Monso, BP-84234, 31030 Toulouse Cedex, France. Electronic address: alex.mazubert@gmail.com.
Alex
A
Mazubert
Department of Chemical & Process Engineering, University of Strathclyde, 16 Richmond Street, Glasgow, Lanarkshire, Scotland G1 1XQ, United Kingdom. Electronic address: cameron.taylor@strath.ac.uk.
Cameron
C
Taylor
Laboratoire de Génie Chimique CNRS/INPT/UPS, University of Toulouse, 4 Allée Emile Monso, BP-84234, 31030 Toulouse Cedex, France. Electronic address: joelle.aubin@ensiacet.fr.
Joelle
J
Aubin
Laboratoire de Génie Chimique CNRS/INPT/UPS, University of Toulouse, 4 Allée Emile Monso, BP-84234, 31030 Toulouse Cedex, France. Electronic address: martine.poux@ensiacet.fr.
Martine
M
Poux
D056804:Biofuels; D004951:Esterification / Q000528:radiation effects; D008872:Microwaves; D009821:Oils / Q000737:chemistry* / Q000528:radiation effects*; D013696:Temperature
D056804:Biofuels; D009821:Oils
Biodiesel; Esterification; Microwave; Transesterification; Waste cooking oil