High external surface Pt/zeolite catalysts for improving polystyrene hydrocracking

• Polymer degradation presents problems of accessibility to active centers in zeolites.
• Bifunctional Pt/h-HZSM-5 and Pt/ITQ-6 with increased external surface were prepared.
• Their behavior was compared to that of microporous Pt/HZSM-5 and Pt/Ferrierite.
• Pt/h-HZSM-5 and Pt/ITQ-6 presented enhanced activity in polystyrene hydrocracking.

Hierarchical (Pt/h-HZSM-5) and delaminated (Pt/ITQ-6) catalysts were prepared as alternative materials to reduce mass-transfer limitations in waste plastics degradation, by increasing external surface area. These catalysts were characterized and tested in polystyrene hydrocracking, and the results compared with Pt/HZSM-5 and Pt/Ferrierite, respectively, as reference materials of similar nature and highly microporous. The activity in polystyrene hydrocracking has been found to be higher in the mesoporous catalysts, Pt/h-HZSM-5 and Pt/ITQ-6. Comparing both strategies, hierarchical and delamination, the latter presents more accessibility of reactants to the active sites, better platinum dispersion and, despite the loss of acidity, higher initial rates in polystyrene hydrocracking, what makes it of great interest for catalyst optimization.

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