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<p>Current methods of processing accumulated polyolefin waste typically require harsh conditions, precious metals or high metal loadings to achieve appreciable activities. Here we examined supported, single-site organonickel catalysts for polyolefin upcycling. Chemisorption of Ni(COD)<sub>2</sub> (COD, 1,5-cyclooctadiene) onto Brønsted acidic sulfated alumina (AlS) yields a highly electrophilic Ni(I) precatalyst, AlS/Ni(COD)<sub>2</sub>, which is converted under H<sub>2</sub> to the active AlS/Ni<sup>II</sup>H catalyst. This single-site system exhibits unique hydrogenolysis selectivity that favours cleaving branched polyolefin C–C linkages, enabling the hydrogenolytic separation of polyethylene and isotactic polypropylene (iPP) mixtures. Moreover, AlS/Ni<sup>II</sup>H remains highly selective and active for hydrogenolysis of iPP admixed with polyvinyl chloride, and the spent catalyst can be repeatedly regenerated by AlEt<sub>3</sub> treatment. Experimental mechanistic analysis and density functional theory modelling reveal a turnover-limiting C–C scission pathway featuring β-alkyl transfer and strong olefin binding. These results highlight the potential of nickel-based systems for the selective upcycling of complex plastic waste streams.</p><p></p>

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Stable single-site organonickel catalyst preferentially hydrogenolyses branched polyolefin C–C bonds

  • 期刊论文

  • 发表日期：

    2025年9月2日

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  • Qingheng Lai,
  • Xinrui Zhang,
  • Shan Jiang,
  • Matthew D. Krzyaniak,
  • Selim Alayoglu,
  • Amol Agarwal,
  • Yukun Liu,
  • Wilson C. Edenfield,
  • Takeshi Kobayashi,
  • Yuyang Wang,
  • Vinayak Dravid,
  • Michael R. Wasielewski,
  • Jeffery T. Miller,
  • Yosi Kratish,
  • Tobin J. Marks

摘要

Current methods of processing accumulated polyolefin waste typically require harsh conditions, precious metals or high metal loadings to achieve appreciable activities. Here we examined supported, single-site organonickel catalysts for polyolefin upcycling. Chemisorption of Ni(COD)2 (COD, 1,5-cyclooctadiene) onto Brønsted acidic sulfated alumina (AlS) yields a highly electrophilic Ni(I) precatalyst, AlS/Ni(COD)2, which is converted under H2 to the active AlS/NiIIH catalyst. This single-site system exhibits unique hydrogenolysis selectivity that favours cleaving branched polyolefin C–C linkages, enabling the hydrogenolytic separation of polyethylene and isotactic polypropylene (iPP) mixtures. Moreover, AlS/NiIIH remains highly selective and active for hydrogenolysis of iPP admixed with polyvinyl chloride, and the spent catalyst can be repeatedly regenerated by AlEt3 treatment. Experimental mechanistic analysis and density functional theory modelling reveal a turnover-limiting C–C scission pathway featuring β-alkyl transfer and strong olefin binding. These results highlight the potential of nickel-based systems for the selective upcycling of complex plastic waste streams.