LEWIS ACID SITES OF Mg2+-MODIFIED POLYSTYRENE SULFONIC ACID RESIN CATALYSYS FOR SYNTHESIS OF DIBUTYL SUCCINATE

The polystyrene sulfonic acid resin catalysts were fabricated, containing elements of Cl and Mg through oxidization and impregnation, and they were characterized by EDS, FT-IR spectra, Py-IR spectra, UV spectra, XPS and TGA to investigate their physiochemical properties. The catalytic performances of these catalysts were examined in the esterification reaction of succinic acid with n-butanol, and the catalytic results showed that modified resins exhibited the highest catalytic activity and achieved a high yield of dibutyl succinate (91.6%) in addition, the modified resin generated new Lewis acid sites and showed significantly higher thermal stability. The experimental results demonstrated that the Mg2+ coordinated with a sulfonic acid group to form stable active sites, which effectively decreased the deactivation caused by the thermal degradation of sulfonic acid. Moreover, the monomer structures of polystyrene sulfonic acid resin and modified polystyrene sulfonic acid resin have been modelled using B3LYP/6-311G(d,p) approximation.

本研究制备了通过氧化与浸渍工艺负载氯（Cl）、镁（Mg）元素的聚苯乙烯磺酸树脂催化剂，并采用能量色散X射线光谱（EDS）、傅里叶变换红外光谱（FT-IR）、吡啶吸附红外光谱（Py-IR）、紫外光谱（UV）、X射线光电子能谱（XPS）以及热重分析（TGA）对其理化性能进行表征。考察了该类催化剂在丁二酸与正丁醇酯化反应中的催化性能，结果表明：改性树脂展现出最优的催化活性，丁二酸二丁酯产率可达91.6%；此外，改性树脂生成了新型路易斯酸位点（Lewis acid sites），且热稳定性显著提升。实验结果证实，镁离子（Mg²+）与磺酸基团配位形成稳定的活性位点，有效缓解了因磺酸基团热降解引发的催化剂失活问题。此外，采用B3LYP/6-311G(d,p)近似方法对聚苯乙烯磺酸树脂与改性聚苯乙烯磺酸树脂的单体结构进行了建模。