Highly Selective Conversion of Polyethylene Terephthalate into Liquid Fuel via Nb-Assisted Ru Bimetallic Catalyst

Chemical recycling of polyester plastics such as polyethylene terephthalate (PET), by converting them into high value-added chemical products, represents a highly promising technological approach. However, persistent challenges remain in PET conversion, including unclear structure–activity relationships of catalysts, low conversion efficiency of hydrogenation-active metals, and insufficient selectivity toward target products. In this work, we developed a high-performance Ru/xNb-BEA (BEA represents dealuminated Beta zeolite) catalyst synthesized via a simple impregnation method. The optimized 1Ru/8Nb-BEA catalyst achieved the highest turnover frequency of 63.3 h–1 with a high selectivity of >95% for cycloalkanes (among all detected products) and demonstrated stable performance over five consecutive reaction cycles (240 °C, 3 MPa H2, 12 h) but also maintained a high reaction performance in practical applications. Combined with comprehensive characterizations, the structure-performance relationship of Ru/Nb-BEA was elucidated. Nb species occupying BEA zeolite T-site vacancies form Si–O–Nb units that disperse and stabilize the Ru0 species. The synergistic effect between distinct acidic site Nb species and hydrogenation-active Ru0 species is proposed as the critical determinant for enhanced catalytic activity. Furthermore, using in situ infrared spectroscopy, we detected the presence of aromatic alcohols and aldehydes during the reaction, providing insights into the plausible reaction mechanism. This study provides valuable insights for the future design of catalysts for the hydro-deoxygenation (HDO) of PET.