Laboratoire de Génie Chimique CNRS/INPT/UPS, University of Toulouse, 4 Allée Emile Monso, BP-84234, 31030 Toulouse Cedex, France.
Department of Chemical & Process Engineering, University of Strathclyde, 16 Richmond Street, Glasgow, Lanarkshire, Scotland G1 1XQ, United Kingdom.
Bioresour Technol. 2014 Jun;161:270-9. doi: 10.1016/j.biortech.2014.03.011. Epub 2014 Mar 20.
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.
微波效应已经被量化，通过酯交换和酯化反应将废食用油转化为生物柴油，比较了微波加热反应器与传统加热反应器中获得的活化能和频率因子。有几篇文献报道了使用微波提高生物柴油产量的效果，然而最近的综述强调了微波反应器中温度测量不准确会导致反应性能产生误导。因此，选择了操作条件来单独研究非热微波效应。采用光纤传感器监测温度，比红外传感器更准确。对于酯交换反应，微波加热反应器中的活化能为 37.1kJ/mol（20.1-54.2kJ/mol），而传统加热反应器中的活化能为 31.6kJ/mol（14.6-48.7kJ/mol）。对于酯化反应，微波加热反应器中的活化能为 45.4kJ/mol（31.8-58.9kJ/mol），而传统加热反应器中的活化能为 56.1kJ/mol（55.7-56.4kJ/mol）。结果证实均相催化反应中不存在非热微波效应。
