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Density functional theory study on the catalytic degradation mechanism of polystyrene
Aip Advances ( IF 1.6 ) Pub Date : 2020-08-03 , DOI: 10.1063/5.0013211
Jinbao Huang 1 , Xiaocai Cheng 2 , Hanxian Meng 1 , Guiying Pan 1 , Shengquan Wang 1 , Daiqiang Wang 1
Affiliation  

The density functional theory method of B3LYP/6-311G(d) was used to study two catalytic degradation (acid-catalyzed and alkali-catalyzed) reaction mechanisms of polystyrene (PS). The geometric structure optimization and frequency calculations of all the molecules involved in the catalytic degradation were performed, and the standard thermodynamic parameters of each catalytic cracking path were obtained. The calculation results show that the energy barrier of the optimal reaction path’s rate control step to form styrene monomer is 68.2 kJ/mol in the alkali-catalyzed degradation reaction paths. In the acid-catalyzed cracking paths, the energy barrier of the optimal path’s rate control step to form styrene is 151.9 kJ/mol. The energy barriers of rate control steps for the formation of styrene monomer in both types of these catalytic cracking reactions are lower than those for other products, so the main degradation product in the two types of catalytic degradation is styrene monomer. Compared with pure thermal degradation, an obvious feature of acid-catalyzed degradation is the formation of benzene, indene, and derivatives of indene. The formation of benzene reduces the phenyl content of the PS main chain, which results in a reduction in the yield of styrene monomer. However, an alkali catalyst shows a positive catalytic effect, which increases the yield of styrene monomer.

中文翻译:

聚苯乙烯催化降解机理的密度泛函理论研究

采用B3LYP / 6-311G(d)的密度泛函理论方法研究了聚苯乙烯(PS)的两种催化降解(酸催化和碱催化)反应机理。对参与催化降解的所有分子进行了几何结构优化和频率计算,获得了每个催化裂化路径的标准热力学参数。计算结果表明,在碱催化降解反应路径中,最佳反应路径的速率控制步骤以形成苯乙烯单体的能垒为68.2 kJ / mol。在酸催化裂化路径中,形成苯乙烯的最佳路径速率控制步骤的能垒为151.9 kJ / mol。在这两种类型的催化裂化反应中,用于形成苯乙烯单体的速率控制步骤的能垒比其他产品低,因此,在两种催化降解中,主要的降解产物是苯乙烯单体。与纯热降解相比,酸催化降解的一个明显特征是苯,茚和茚衍生物的形成。苯的形成降低了PS主链的苯基含量,这导致苯乙烯单体的收率降低。然而,碱催化剂显示出积极的催化作用,这增加了苯乙烯单体的产率。酸催化降解的一个明显特征是苯,茚和茚衍生物的形成。苯的形成降低了PS主链的苯基含量,这导致苯乙烯单体的产率降低。然而,碱催化剂显示出积极的催化作用,这增加了苯乙烯单体的产率。酸催化降解的一个明显特征是苯,茚和茚衍生物的形成。苯的形成降低了PS主链的苯基含量,这导致苯乙烯单体的产率降低。然而,碱催化剂显示出积极的催化作用,这增加了苯乙烯单体的产率。
更新日期:2020-08-31
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