Morphology-Directed Stabilization of PtZn Intermetallic Phases via Framework Ti Sites in TS-1 Zeolites for Robust Propane Dehydrogenation

Abstract The rational construction of stable Pt-based catalysts is crucial for achieving efficient propane dehydrogenation (PDH) at high temperatures, yet controlling the formation and stabilization of Pt-based intermetallic active phases remains challenging. Herein, framework Ti species in TS-1 zeolite were exploited as anchoring sites to stabilize PtZn bimetallic catalysts, and the influence of TS-1 morphology on the structural evolution and catalytic behavior of PtZn catalysts was systematically investigated. Comprehensive catalytic evaluations, structural characterizations, and kinetic analyses reveal that the morphology of TS-1 governs the accessibility of framework Ti sites and thereby regulates the formation of Pt1Zn1 intermetallic species. Compared with platelet-like TS-1, spherical TS-1 possesses a higher surface area, abundant intracrystalline mesoporosity, and fewer extra-framework Ti species, providing more effective anchoring sites for PtZn species and facilitating the construction of highly dispersed Pt1Zn1 intermetallic nanoparticles. Moreover, the hierarchical pore structure of spherical TS-1 promotes reactant/product diffusion and enhances the catalyst’s resistance to carbon deposition during PDH. Consequently, the optimized PtZn/TS-1-sphere catalyst delivers a superior initial propylene formation rate of 44.6 molC3H6·gPt−1·h−1 at 600 °C with a remarkably low deactivation rate constant of 0.0035 h−1 over 50 h. In contrast, platelet-like TS-1 containing abundant extra-framework Ti species exhibits inferior metal anchoring capability and limited PtZn intermetallic formation. This work offers insights into the morphology-directed regulation of zeolite-based metal interfaces for designing highly stable dehydrogenation catalysts.