Hernández-Fernández Joaquín, González-Cuello Rafael, Ortega-Toro Rodrigo
Chemistry Program, Department of Natural and Exact Sciences, San Pablo Campus, University of Cartagena, Cartagena 130015, Colombia.
Chemical Engineering Program, School of Engineering, Universidad Tecnológica de Bolivar, Parque Industrial y Tecnológico Carlos Vélez Pombo, Km 1 Vía Turbaco, Turbaco 130001, Colombia.
Polymers (Basel). 2023 Oct 12;15(20):4061. doi: 10.3390/polym15204061.
The study focused on the evaluation of the influence of inhibitory compounds such as hydrogen sulfide (HS) and methanol (CHOH) on the catalytic productivity and properties of the polymers in the polymerization process with the Ziegler-Natta catalyst. The investigation involved experimental measurements, computational calculations using DFT, and analysis of various parameters, such as molecular weight, melt flow index, xylene solubility, and reactivity descriptors. The results revealed a clear correlation between the concentration of HS and methanol and the parameters evaluated. Increasing the HS concentrations, on average by 0.5 and 1.0 ppm, resulted in a drastic decrease in the polymer's molecular weight. A directly proportional relationship was observed between the flow rate and the HS concentration. In the case of methanol, the change occurred from 60 ppm, causing a sharp decrease in the molecular weight of the polymer, which translates into an increase in the fluidity index and a decrease in solubility in xylene. The presence of these inhibitors also affected the catalytic activity, causing a reduction in the productivity of the Ziegler-Natta catalyst. Computational calculations provided a deeper understanding of the molecular behavior and reactivity of the studied compounds. The computational calculations yielded significantly lower results compared to other studies, with values of -69.0 and -43.9 kcal/mol for the Ti-CHOH and HS interactions, respectively. These results indicate remarkable stability in the studied interactions and suggest that both adsorptions are highly favorable.
该研究聚焦于评估诸如硫化氢（HS）和甲醇（CHOH）等抑制性化合物对使用齐格勒-纳塔催化剂的聚合过程中聚合物的催化生产率和性能的影响。该调查涉及实验测量、使用密度泛函理论（DFT）的计算以及对各种参数的分析，如分子量、熔体流动指数、二甲苯溶解度和反应性描述符。结果显示HS和甲醇的浓度与所评估的参数之间存在明显的相关性。将HS浓度平均提高0.5和1.0 ppm会导致聚合物分子量急剧下降。观察到流速与HS浓度之间存在正比关系。对于甲醇，在60 ppm时发生变化，导致聚合物分子量急剧下降，这转化为流动指数增加和二甲苯溶解度降低。这些抑制剂的存在也影响了催化活性，导致齐格勒-纳塔催化剂的生产率降低。计算为所研究化合物的分子行为和反应性提供了更深入的理解。与其他研究相比，计算结果显著更低，Ti-CHOH和HS相互作用的值分别为-69.0和-43.9 kcal/mol。这些结果表明所研究的相互作用具有显著的稳定性，并表明两种吸附都非常有利。
