Polyolefin melt-phase effects on alkane hydrogenolysis over Pt catalysts

IF 11.5 Q1 CHEMISTRY, PHYSICAL Chem Catalysis Pub Date : 2024-09-05 DOI:10.1016/j.checat.2024.101093

Mehdi Zare, Dia Sahsah, Olajide H. Bamidele, Andreas Heyden

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Abstract

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 ( ${Δ Δ G}_{A d s o r b a t e}^{g a s \to l i q}$ ${Δ Δ G}_{A d s o r b a t e}^{g a s \to l i q}$ ) 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, ${Δ Δ G}_{A d s o r b a t e}^{g a s \to l i q}$ ${Δ Δ G}_{A d s o r b a t e}^{g a s \to l i q}$ , 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.

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聚烯烃熔相对铂催化剂上烷烃氢解的影响

支持过渡金属催化的聚烯烃氢解化学升循环通常在高温（T > 200°C）下的聚合物熔融相中进行。目前，熔融相对过渡金属催化活性和选择性的影响尚不清楚。在此，我们采用量子力学/分子力学（QM/MM）混合方法研究了在 573 K 下，由 C36H74 链组成的聚乙烯代用熔体存在时，丁烷在 Pt(111) 催化剂表面的氢解机理中，熔相对原子氢、12 个碳氢化合物分子和 4 个过渡态的吸附自由能（ΔΔGAdsorbategas→liqΔΔGAdsorbategas→liq）的影响。最小和最大的内能熔相效应ΔΔGAdsorbategas→liqΔΔGAdsorbategas→liq分别属于氢（0.045 eV）和丁烷（1.357 eV）。总之，我们发现熔相效应非常显著，会改变过渡金属催化剂的活性。除了整体吸附强度降低之外，基本表面反应也受到熔融相的影响。

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来源期刊

Chem Catalysis

CiteScore

10.50

自引率

6.40%

发文量

期刊介绍： Chem Catalysis is a monthly journal that publishes innovative research on fundamental and applied catalysis, providing a platform for researchers across chemistry, chemical engineering, and related fields. It serves as a premier resource for scientists and engineers in academia and industry, covering heterogeneous, homogeneous, and biocatalysis. Emphasizing transformative methods and technologies, the journal aims to advance understanding, introduce novel catalysts, and connect fundamental insights to real-world applications for societal benefit.