Pt-Shell-Protected PtZn Intermetallic Nanoclusters for Highly Efficient Propane Dehydrogenation

Abstract

Propane dehydrogenation (PDH) using platinum-based intermetallic catalysts is an important approach for the industrial production of highly value-added propylene. Nevertheless, the high temperature needed for PDH inevitably causes deactivation of the intermetallic catalysts due to phase separation or particle aggregation. Herein, we showcase that a Pt shell offers a promising solution to protect intermetallics under harsh PDH environments. Through selective removal of the surface Zn atoms, a core/shell architecture with 1–2 atomic layers of Pt coating PtZn intermetallic nanoclusters is constructed. No deactivation was observed within an 80 h long-term stability test at 580 °C on the optimal PtZn/Pt catalyst, affording an extremely low deactivation rate constant of 0.0007 h^–1. Furthermore, the construction of the PtZn/Pt core/shell promotes the catalytic efficiency, with a high propylene formation rate of 124.8 mol of C₃H₆ g_Pt^–1 h^–1 that surpasses that of most of the Pt-based PDH catalysts reported. Density functional theory calculations reveal that the Pt shell plays dual roles in stabilizing the intermetallic core and modifying the electronic structure of the ensemble by inducing a compressive strain. This lattice strain downshifts the d-band center to a lower value of −3.02 eV and decreases propylene desorption energy to a level lower than the barrier energy of C–H breaking by 0.66 eV, resulting in enhanced coking resistance and reactivity.