Role of Bifunctional Ru/Acid Catalysts in the Selective Hydrocracking of Polyethylene and Polypropylene Waste to Liquid Hydrocarbons

作者：Julie E. Rorrer, Amani M. Ebrahim, Ydna M. Questell‐Santiago, Jie Zhu, Clara Troyano-Valls, Arun S. Asundi, Anna E. Brenner, Simon R. Bare, Christopher J. Tassone, Gregg T. Beckham, Yuriy Román‐Leshkov · 发表于：ACS Catalysis · 年份：2022 · DOI：10.1021/acscatal.2c03596 · 被引用次数：177 · 研究领域：biodegradable polymer synthesis and properties、Polymer crystallization and properties、Zeolite Catalysis and Synthesis

Hydrogenolysis of C–C bonds over Ru-based catalysts has emerged as a deconstruction strategy to convert single-use polyolefin waste to liquid alkanes at relatively mild conditions, but this approach exhibits limitations, including methane formation resulting from terminal C–C bond scission. In this study, a variety of catalysts were investigated for the reductive deconstruction of polyethylene (PE) and polypropylene (PP) to identify supports that promote nonterminal C–C bond scission. We found that Ru nanoparticles supported on Brønsted-acidic zeolites with the faujasite (FAU) and Beta (BEA) topologies were highly active for the cleavage of C–C bonds in PE and PP, exhibiting improved liquid yields and suppressed methane formation. For the deconstruction of PE, supporting ruthenium nanoparticles (5 wt %) on FAU increased the yields of liquid alkanes to 67% compared to 33% over an inert silica support (5 wt % Ru/SiO 2 ) at 200 °C, 16 h, under 30 bar of H 2 . A dramatic selectivity enhancement toward liquid hydrocarbons was also observed for PP over Ru/FAU and Ru/BEA compared to Ru/SiO 2 . To understand the origin of this selectivity improvement, a combination of ex situ and operando characterization techniques were used to reveal that both catalyst structure and acidity play key roles in PE and PP conversion. Operando X-ray absorption spectroscopy studies with model polyolefins over Ru-supported catalysts with varying acidity levels revealed that the local chemical environment ...