Distribution Kinetics for Temperature-Programmed Pyrolysis
Distribution Kinetics for Temperature-Programmed Pyrolysis
复制标题
程序升温热解的分布动力学
DOI：
10.1021/ie990462p
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发表时间：
1999
影响因子：
4.2
通讯作者：
B. J. McCoy
中科院分区：
文献类型：
--
作者：
B. J. McCoy
热解通常用n级或S型(成核或自催化)动力学和具有分布活化能的平行反应来模拟。然而，其基本的化学成分包括热分解键断裂、复合反应和低分子量(MW)产品的挥发。一种新的方法是基于动态布居平衡方程来计算程序升温热重过程中热解高分子材料的分子量分布。该模型考虑了随机链断裂、再聚合、链端断裂产生气体产物以及低分子物质的蒸发损失。平衡方程的零阶矩和一阶矩为样品的摩尔数n(T)和质量m(T)的时间依赖关系提供了耦合的微分方程组。N和m的单独变化解释了热解过程中平均分子量的变化。无规断链的活化能相对大于链断裂的活化能。
Pyrolysis is usually modeled with nth-order or sigmoidal (nucleation or autocatalytic) kinetics and with parallel reactions having distributed activation energies. The underlying chemistry, however, consists of thermolytic bond cleavage, recombination reactions, and volatilization of low molecular weight (MW) products. A new approach is based on a dynamic population-balance equation for the molecular weight distribution of a pyrolyzing macromolecular material in a temperature-programmed thermogravimetric process. Random chain scission, repolymerization, chain-end scission yielding gas products, and loss of low-MW matter by vaporization are included in the model. Zeroth and first moments of the balance equation provide coupled differential equations for the time dependence of moles, n(t), and mass, m(t), of the sample. Separate changes in n and m account for the changes in the average molecular weight during pyrolysis. The activation energy for random chain scission is relatively larger than that for chain...