Comparative study on thermal cracking behaviors and kinetics of two typical lignocellulosic biomass pyrolysis oils
LI Guotong;ZHANG Yuming;XIONG Qing’an;QIAO Pei;LI Jiazhou;ZHANG Wei;CHEN Zhewen
为提高生物质热解油的利用效率,探究生物质热解油在提质转化过程中的热解特性,进一步拓宽生物质热解油的利用途径,选取2种木质纤维素类生物质热解油作为研究对象,采用热重分析仪分别考察2种生物油的热解行为。选用Friedman法、FWO法2种等转化率方法求取生物质热解油整体热解反应的动力学参数,选用分布活化能模型(DAEM)法将生物质热解油热解过程分为轻质组分和重质组分2种虚拟组分热解过程,并求取2种虚拟组分热解的动力学参数。2种生物油的轻重组分含量差异导致2者的热解行为表现出不同特征,木屑热解生物油的最大质量变化速率对应温度和热失重反应结束温度均高于稻壳热解生物油。Friedman法计算所得2种生物油的活化能分别为89.92、145.98 kJ/mol,FWO法计算所得2种生物油的活化能分别为90.30、138.44 kJ/mol,2种方法计算结果具有较好的一致性;木屑热解生物油的平均活化能(142.21 kJ/mol)高于稻壳热解生物油(90.11 kJ/mol)。进一步采用DAEM方法将2种生物油热解过程分别分为轻质组分热解和重质组分热解,两组分DAEM方法动力学计算结果表明稻壳热解生物油和木屑热解生物油轻质组分的活化能(79.03、85.00 kJ/mol)小于重质组分的活化能(158.56、160.00 kJ/mol)。2种动力学方法计算结果表明生物油热解过程中轻质组分降低了生物油整体的活化能,2种动力学计算方法综合使用有利于对生物油的热解反应形成更为全面的认识。
To improve the utilization efficiency of biomass pyrolysis oil, the pyrolysis characteristics of biomass pyrolysis oil in the process of transformation were explored, so as to further expand the utilization ways of biomass pyrolysis oil, two kinds of lignocellulosic biomass pyrolysis oils of rice husk and sawdust were selected as the materials, and the cracking behaviors of these two pyrolysis oils were investigated by TG. The Friedman, FWO, and distributed activation energy model (DAEM) methods were used to calculate the overall reaction and kinetic parameters of two virtual components. The results showed that the content difference between light components and heavy components of two pyrolysis oils resulted in different cracking behaviors. The maximum thermogravimetric rate corresponds to temperature and the end temperature of sawdust pyrolysis oil weight-loss reaction was higher than that of rice husk. The activation energy calculated by Friedman and FWO methods was 89.92 and 90.30 kJ/mol for rice husk pyrolysis oil, and 145.98 and 138.44 kJ/mol for sawdust pyrolysis oil, respectively. Two pyrolysis oils were separated into light and heavy components by DAEM. The calculated activation energy of light components of rice husk and sawdust pyrolysis oils (79.03 and 85.00 kJ/mol) was lower than that of heavy components (158.56 and 160.00 kJ/mol). Synergistic effect between light and heavy component existed in the cracking process, and the light component reduced the cracking activation energy of biomass pyrolysis oil. The comprehensive use of the two kinetic calculation methods was conducive to the formation of a more comprehensive understanding of the pyrolysis reaction of bio-oil.
biomass pyrolysis oil;cracking characteristics;iso-conversion method;distributed activation energy model
主办单位:煤炭科学研究总院有限公司 中国煤炭学会学术期刊工作委员会