Isothermal and non-isothermal torrefaction characteristics and kinetics of microalga Scenedesmus obliquus CNW-N.
Isothermal and non-isothermal torrefaction characteristics and kinetics of microalga Scenedesmus obliquus (S. obliquus) CNW-N are studied using thermogravimetric analysis. The pyrolysis of S. obliquus CNW-N with increasing temperature is characterized by four-stage decomposition. Depending on the torrefaction temperature, light, mild, and severe torrefaction from the weight loss and the maximum decomposition rate of the microalga can be classified. Under the same average temperature and torrefaction duration, non-isothermal torrefaction gives more severe pretreatment than the isothermal one. Increasing the heating rate of non-isothermal torrefaction also intensifies the pretreatment severity. Therefore, microalgae can be torrefied via non-isothermal torrefaction in a shorter time under the same pretreatment extent. The atomic H/C ratio in the microalga decreases with increasing torrefaction severity, whereas the atomic O/C ratio rises. The analysis suggests that the activation energy of isothermal torrefaction is 57.52×10(3)Jmol(-1), while it is between 40.14×10(3) and 88.41×10(3)Jmol(-1) for non-isothermal torrefaction.
Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 701, Taiwan, ROC. Electronic address: weihsinchen@gmail.com.
Wei-Hsin
WH
Chen
Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC.
Zih-Ying
ZY
Wu
Department of Chemical Engineering, National Cheng Kung University, Tainan 701, Taiwan, ROC; Center for Bioscience and Biotechnology, National Cheng Kung University, Tainan 701, Taiwan, ROC; Research Center for Energy Technology and Strategy, National Cheng Kung University, Tainan 701, Taiwan, ROC. Electronic address: changjs@mail.ncku.edu.tw.
Jo-Shu
JS
Chang
D001703:Biophysics; D006358:Hot Temperature; D007700:Kinetics; D008956:Models, Chemical; D059205:Renewable Energy; D044444:Scenedesmus / Q000378:metabolism*; D013818:Thermogravimetry
Biomass and microalgae; Isothermal and non-isothermal torrefaction; Kinetics; Pyrolysis; Thermogravimetric analysis