Decoupling Acidity from Micropore Confinement in an Amorphous–Crystalline Composite for Selective Polyolefin Waste Cracking
Qiaohui Ruan, Hailu Xia, Zanfeng Yuan, Zhuohan Lin, Xu Wang, Wenao Ouyang, Jian-Ping Zou, Yan Li
Abstract
The persistent accumulation of polyolefin plastic waste poses a significant environmental challenge, while its sustainable conversion into valuable olefins is limited by poor accessibility and severe coking of conventional microporous zeolite catalysts. Here, we report a rationally designed amorphous–crystalline composite (ACC) catalyst that integrates short-range ordered SOD-type domains into an amorphous aluminosilicate matrix to decouple acidity from micropore confinement. This hybrid architecture provides both open diffusion channels and accessible acid sites, enabling efficient C–C bond scission while suppressing secondary reactions. In low-density polyethylene cracking at 440 °C and a catalyst-to-feed weight ratio of 10/1, the optimized ACC catalyst achieved an exceptional C 3 –C 5 olefin selectivity of 94.92% and a yield of 88.08 wt %, outperforming commercial ZSM-5 and USY by factors of more than 13 and 37, respectively. The catalyst exhibited outstanding stability over 20 consecutive cycles with minimal coke formation (1.13 wt %) and broad applicability across various polyolefins and postconsumer plastic wastes. This work establishes a generalizable design strategy for decoupling acidity and mass transport in solid acid catalysts, offering a robust platform for the sustainable valorization of polyolefin waste.