Insights into <em>in-situ</em> 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-C30chains 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 m 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.

深入了解塑料解聚产生的挥发物从外部进入催化剂内部结构的过程，有助于在放大原则下合理设计催化剂。在此，对使用流化催化裂化催化剂（FCC）催化降解塑料废弃物进行了深入研究。对不同FCC上液体和气体产物的产率及组成进行了定量研究。利用X射线纳米CT探测了催化剂在整体范围内的结构演变，包括非均相孔隙系统的拓扑结构和沸石的空间分布。结果表明，FCC促进了C16 - C30链向以C9为中心的单环芳烃的转化。对FCC的纳米CT分析表明，反应后外部孔隙率显著降低，特别是在距离最外层约16.5μm处。而内部孔隙受到的影响较小，这表明大分子烃类无法充分利用活性位点，它们更倾向于占据外表面的大尺寸孔隙（>385nm）。