Heat Generation during the Aging of Wood-Derived Fast-Pyrolysis Bio-oils
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- 作者：Tom Sundqvist ; Yrj? Solantausta ; Anja Oasmaa ; Lauri Kokko ; Ville Paasikallio
- 刊名：Energy & Fuels
- 出版年：2016
- 出版时间：January 21, 2016
- 年：2016
- 卷：30
- 期：1
- 页码：465-472
- 全文大小：433K
- ISSN：1520-5029
文摘
The changes in chemical composition and physical properties that accompany bio-oil aging reactions have been studied earlier. However, one fundamental aspect of this transformation process has been ignored. In this article, we prove that aging of fast-pyrolysis bio-oils from woody biomass is an exothermic process with notable heat generation under adiabatic conditions. The heat generation characteristics of several fast-pyrolysis bio-oils were studied in a novel reaction calorimeter that was made in-house. When typical fast-pyrolysis bio-oils were stored at 50 °C for a period of 1 week, they exhibited overall adiabatic temperature increases ranging from 14 K to 28 K. The largest differences in heat generation were observed at the beginning of the aging period, which corresponds with the previously known reactivity characteristics of bio-oils. Increasing the storage temperature accelerated the aging reactions, which manifested as higher overall temperature increases—up to 55 K in 1 week—and higher specific thermal power density (STPD) values. The reactivity of the bio-oil at 70 °C could be partly passivated by employing a 1 week pretreatment at a more moderate temperature (40 °C). The addition of alcohol decreased heat generation from the bio-oil. The observed heat generation of bio-oils under varying aging conditions correlated with changes in their chemical composition and physical properties. This shows that previously developed bio-oil stability indicators can also be used to estimate the heat generation potential of a given bio-oil. In particular, a change in the concentration of carbonyl compounds exhibited a clearly linear correlation with heat generation. A decrease of one unit in the carbonyl content (mol/kg of bio-oil) would correspond to an adiabatic temperature increase of 20 °C.