Mehdi Zare, Dia Sahsah, Olajide H. Bamidele, Andreas Heyden
{"title":"Polyolefin melt-phase effects on alkane hydrogenolysis over Pt catalysts","authors":"Mehdi Zare, Dia Sahsah, Olajide H. Bamidele, Andreas Heyden","doi":"10.1016/j.checat.2024.101093","DOIUrl":null,"url":null,"abstract":"<p>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 (<span><span><math><mrow is=\"true\"><msubsup is=\"true\"><mrow is=\"true\"><mo is=\"true\">Δ</mo><mo is=\"true\">Δ</mo><mi is=\"true\">G</mi></mrow><mrow is=\"true\"><mi is=\"true\">A</mi><mi is=\"true\">d</mi><mi is=\"true\">s</mi><mi is=\"true\">o</mi><mi is=\"true\">r</mi><mi is=\"true\">b</mi><mi is=\"true\">a</mi><mi is=\"true\">t</mi><mi is=\"true\">e</mi></mrow><mrow is=\"true\"><mi is=\"true\">g</mi><mi is=\"true\">a</mi><mi is=\"true\">s</mi><mo is=\"true\" stretchy=\"true\">→</mo><mi is=\"true\">l</mi><mi is=\"true\">i</mi><mi is=\"true\">q</mi></mrow></msubsup></mrow></math></span><script type=\"math/mml\"><math><mrow is=\"true\"><msubsup is=\"true\"><mrow is=\"true\"><mo is=\"true\">Δ</mo><mo is=\"true\">Δ</mo><mi is=\"true\">G</mi></mrow><mrow is=\"true\"><mi is=\"true\">A</mi><mi is=\"true\">d</mi><mi is=\"true\">s</mi><mi is=\"true\">o</mi><mi is=\"true\">r</mi><mi is=\"true\">b</mi><mi is=\"true\">a</mi><mi is=\"true\">t</mi><mi is=\"true\">e</mi></mrow><mrow is=\"true\"><mi is=\"true\">g</mi><mi is=\"true\">a</mi><mi is=\"true\">s</mi><mo stretchy=\"true\" is=\"true\">→</mo><mi is=\"true\">l</mi><mi is=\"true\">i</mi><mi is=\"true\">q</mi></mrow></msubsup></mrow></math></script></span>) 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 C<sub>36</sub>H<sub>74</sub> chains. The smallest and largest endergonic melt phase effects, <span><span><math><mrow is=\"true\"><msubsup is=\"true\"><mrow is=\"true\"><mo is=\"true\">Δ</mo><mo is=\"true\">Δ</mo><mi is=\"true\">G</mi></mrow><mrow is=\"true\"><mi is=\"true\">A</mi><mi is=\"true\">d</mi><mi is=\"true\">s</mi><mi is=\"true\">o</mi><mi is=\"true\">r</mi><mi is=\"true\">b</mi><mi is=\"true\">a</mi><mi is=\"true\">t</mi><mi is=\"true\">e</mi></mrow><mrow is=\"true\"><mi is=\"true\">g</mi><mi is=\"true\">a</mi><mi is=\"true\">s</mi><mo is=\"true\" stretchy=\"true\">→</mo><mi is=\"true\">l</mi><mi is=\"true\">i</mi><mi is=\"true\">q</mi></mrow></msubsup></mrow></math></span><script type=\"math/mml\"><math><mrow is=\"true\"><msubsup is=\"true\"><mrow is=\"true\"><mo is=\"true\">Δ</mo><mo is=\"true\">Δ</mo><mi is=\"true\">G</mi></mrow><mrow is=\"true\"><mi is=\"true\">A</mi><mi is=\"true\">d</mi><mi is=\"true\">s</mi><mi is=\"true\">o</mi><mi is=\"true\">r</mi><mi is=\"true\">b</mi><mi is=\"true\">a</mi><mi is=\"true\">t</mi><mi is=\"true\">e</mi></mrow><mrow is=\"true\"><mi is=\"true\">g</mi><mi is=\"true\">a</mi><mi is=\"true\">s</mi><mo stretchy=\"true\" is=\"true\">→</mo><mi is=\"true\">l</mi><mi is=\"true\">i</mi><mi is=\"true\">q</mi></mrow></msubsup></mrow></math></script></span>, 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.</p>","PeriodicalId":53121,"journal":{"name":"Chem Catalysis","volume":"9 1","pages":""},"PeriodicalIF":11.5000,"publicationDate":"2024-09-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Chem Catalysis","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.1016/j.checat.2024.101093","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"CHEMISTRY, PHYSICAL","Score":null,"Total":0}
引用次数: 0
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 () 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, , 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.
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.