Supported transition metal-catalyzed chemical upcycling of polyolefins by hydrogenolysis typically occurs in a polymer melt phase at elevated temperatures (T > 200°C). Currently, the impact of the melt phase on the catalytic activity and selectivity of the transition metal is largely unknown. Here, we use a hybrid quantum mechanical/molecular mechanical (QM/MM) approach to investigate the melt-phase effects on the adsorption free energy (${\Delta \Delta G}_{Adsorbate}^{gas\to liq}$) of atomic hydrogen, 12 hydrocarbon molecules, and 4 transition states in the hydrogenolysis mechanism of butane on a Pt(111) catalyst surface at 573 K in the presence of a polyethylene surrogate melt consisting of C₃₆H₇₄ chains. The smallest and largest endergonic melt phase effects, ${\Delta \Delta G}_{Adsorbate}^{gas\to liq}$, belong to hydrogen (0.045 eV) and butane (1.357 eV). Overall, we find that melt-phase effects are significant and change the activity of transition metal catalysts. Beyond an overall reduced adsorption strength, elementary surface reactions are also affected by the melt phase.

中文翻译：

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聚烯烃熔融相对 Pt 催化剂上烷烃加氢的影响


通过氢解对聚烯烃进行负载型过渡金属催化的化学升级回收通常发生在高温 （T > 200°C） 下的聚合物熔融相中。目前，熔融相对过渡金属的催化活性和选择性的影响在很大程度上是未知的。在这里，我们使用混合量子力学/分子力学 （QM/MM） 方法研究了在 C₃₆H₇₄ 组成的聚乙烯替代物熔体存在下，丁烷在 573 K 下丁烷氢解机理中丁烷氢解机理中对氢原子吸附自由能 （） 的影响链。最小和最大的内能熔融相效应 属于氢 （0.045 eV） 和丁烷 （1.357 eV）。总体而言，我们发现熔融相效应很重要，并改变了过渡金属催化剂的活性。除了整体吸附强度降低外，基本表面反应还受到熔融相的影响。