Pyrolysis versus hydrolysis behavior during steam decomposition of polyesters using 18O-labeled steam
Pyrolysis versus hydrolysis behavior during steam decomposition of polyesters using 18O-labeled steam
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DOI：
10.1039/c5ra08577b
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发表时间：
2015-07
期刊：
影响因子：
3.9
通讯作者：
S. Kumagai;Yuto Morohoshi;G. Grause;T. Kameda;T. Yoshioka
中科院分区：
文献类型：
--
作者：
S. Kumagai;Yuto Morohoshi;G. Grause;T. Kameda;T. Yoshioka
蒸汽分解是一种用于聚酯解聚的方法，不需要溶剂、催化剂或高压。在蒸汽分解过程中，酯基团通过水解发生裂变，而在热解过程中酯基团在没有水的作用下裂解，导致单体产率降低。因此，阐明水解和热解对蒸汽气氛中解聚的贡献，以及聚酯结构对选择性的影响，将提高动力学分析的准确性并最大限度地提高单体产率。在这项研究中，使用 18O 标记的蒸汽在不同的蒸汽浓度和分解温度下量化了聚对苯二甲酸乙二醇酯 (PET)、聚对苯二甲酸丁二醇酯 (PBT) 和聚 2,6-萘二甲酸乙二醇酯 (PEN) 蒸汽分解过程中热解和水解的选择性。分解温度强烈影响PET和PBT的水解选择性，而PEN的水解选择性几乎不受影响。对于 PET 和 PEN（PBT 除外），聚酯水解的选择性随着蒸汽浓度的增加而增加。这些结果表明，热解和水解的选择性均受到聚酯结构的显着影响。此外，蒸汽分解热重动力学分析与18O标记实验结果一致。
Steam decomposition, a method employed for the depolymerization of polyesters, does not require solvents, catalysts, or high pressure. During steam decomposition, the fission of the ester group occurs by hydrolysis, whereas the ester group is cleaved without the action of water during pyrolysis, affording reduced monomer yields. Hence, elucidating the contribution of hydrolysis and pyrolysis to depolymerization in a steam atmosphere, as well as the effect of polyester structure on selectivity, will improve the accuracy of kinetic analyses and maximize monomer yields. In this study, the selectivities for pyrolysis and hydrolysis during the steam decomposition of polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and polyethylene 2,6-naphthalate (PEN) were quantified using 18O-labeled steam at different steam concentrations and decomposition temperatures. The decomposition temperature strongly affected the hydrolysis selectivity for PET and PBT, whereas that for PEN was hardly affected. The selectivity for polyester hydrolysis increased with increasing steam concentration for both PET and PEN, with the exception of PBT. These results revealed that the selectivities for both pyrolysis and hydrolysis were significantly affected by the structure of the polyester. In addition, the thermogravimetric kinetic analysis of steam decomposition was consistent with the results of the 18O-labeling experiments.