Insights into In-Situ Catalytic Degradation of Plastic Wastes Over Zeolite-Based Catalyst from Perspective of Three-Dimensional Pore Structure Evolution

Insightfully understanding the process of volatiles from plastic depolymerization entering from the exterior into internal structure of catalyst favors to rationalize the catalyst design in scale-up principles. Herein, catalytic degradation of plastic wastes with fluid catalytic cracking catalyst (FCC) was investigated in-depth. The yield and composition of liquid and gas products over various FCCs were studied quantitatively. The structural evolution of catalyst on overall scope, including the topology of heterogeneous pore systems and spatial distribution of zeolite was probed by X-ray nano-CT. The results showed that FCC enhanced the transformation of C16-C30 chains to C9-centered monocyclic aromatics. The nano-CT analysis of FCCs illustrated remarkable loss of exterior porosity after reaction, particularly at the depth of ~16.5 μm from the outmost layer. While the interior pores were marginally affected, indicating large hydrocarbons incapable of engaging with active sites to full advantage, which preferably occupied large-size pores (>385 nm) of external surface. © 2022, The Authors. All rights reserved.