Thermogravimetric kinetics of lignocellulosic biomass slow pyrolysis using distributed activation energy model, Fraser-Suzuki deconvolution, and iso-conversional method
Thermogravimetric kinetics of lignocellulosic biomass slow pyrolysis using distributed activation energy model, Fraser-Suzuki deconvolution, and iso-conversional method
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DOI：
10.1016/j.enconman.2016.03.058
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发表时间：
2016-06-15
影响因子：
10.4
通讯作者：
Ma, Shu
中科院分区：
文献类型：
--
作者：
Hu, Mian;Chen, Zhihua;Ma, Shu
采用热重分析技术研究了松木、稻壳和竹材在低升温速率下的热解动力学。无模型过程的结果表明，一步反应模型下的木质纤维素热解主要受扩散效应的影响。然而，变化的复杂特征是由机制变化引起的，很难确定。分布式活化能模型（DAEM）动力学结果表明，伪组分的活化能分布顺序为：E-o（木质素）>（纤维素）> E-o（半纤维素）、sigma（木质素）> sigma（半纤维素）> sigma（纤维素）。与DAEM相比，Fraser-Suzuki反褶积法更符合实验数据。伪组分反卷积后的热解机理遵循理论模型：半纤维素和木质素的三阶模型f(α)= (1 - α)(3)，纤维素的随机裂解模型f(α)=2（α (1/2) - α）。松木、稻壳和竹子的伪半纤维素表观活化能分别为162.84 +/- 26.45 kJ/mol、168.63 +/- 28.47 kJ/mol和154.55 +/- 26.49 kJ/mol。E-alpha值随转换量的增大而增大，与平均值相差不大。类似的eα,vs。松木、稻壳和竹子的α依赖关系分别为188.14 +/- 24.42 kJ/mol、206.71 +/- 24.88 kJ/mol和190.45 +/- 23.79 kJ/mol。(C) 2016 Elsevier Ltd.版权所有。
Pyrolysis kinetics of pine wood, rice husk and bamboo (Bambusa chungii) were studied via thermogravimetric analysis technique under low heating rates. The result of model-free procedure showed that the lignocellulosic pyrolysis according to one-step reaction model is dominated by the diffusion effects. However, the complex features of variations are caused by the mechanism changes, which are hard to be determined. The distributed activation energy model (DAEM) kinetic results indicated that the activation energy distribution for pseudo components follows the orders of: E-o(lignin) > E-0(cellulose) > E-o(hemicelluloses), sigma(lignin) > sigma(hemicelluloses) > sigma(cellulose). The Fraser-Suzuki deconvolution fits better with the experimental data than DAEM. The pyrolysis mechanism of pseudo components after deconvolutions follows the theoretical models: third order model f(alpha)= (1 - alpha)(3) for hemicelluloses and lignin, random scission model f(alpha)=2(alpha(1/2) - alpha) for cellulose. The apparent activation energy for pseudo hemicelluloses is 162.84 +/- 26.45 kJ/mot for pine wood, 168.63 +/- 28.47 kJ/mol for rice husk and 154.55 +/- 26.49 kJ/mol for bamboo, respectively. The E-alpha, value increases with the conversion with little deviation to its mean value. Similar E-alpha,vs. alpha dependencies also are observed for pseudo celluloses, which has E-alpha, of 188.14 +/- 24.42 kJ/mol for pine wood, 206.71 +/- 24.88 kJ/mol for rice husk and 190.45 +/- 23.79 kJ/mol for bamboo, respectively. (C) 2016 Elsevier Ltd. All rights reserved.