Zinc Doping Boosts the Reactivity and Anti-Coking Ability of Cobalt-Based Catalysts for Propane Dehydrogenation

Abstract

The development of environmentally friendly non-noble-metal catalysts for propane dehydrogenation (PDH) has attracted significant attention. CoO_x and ZnO_x catalysts, known for their relatively high C–H bond activation ability, show great potential. Bimetallic oxide catalysts with dual active sites are particularly promising because of their unique intrinsic properties for PDH. In this study, we synthesized high-performance ZnCoO_x oxides supported on Silicalite-1 (S-1) zeolite via a complexation-impregnation method with citric acid. The optimized ZnCoO_x/S-1 catalyst demonstrated a propylene formation rate approximately twice as high as that of monometallic CoO_x/S-1 or ZnO_x/S-1 catalysts. The kinetic analysis and in situ spectroscopy confirmed that bimetallic ZnCoO_x species exhibited superior selective activation ability for propane C–H bonds compared to those of monometallic CoO_x and ZnO_x catalysts. Furthermore, these results demonstrated the dominant role of metallic Co⁰ sites as the primary active centers for PDH. These features contributed to minimal coke deposition, further improving the catalytic performance. Additionally, reversible transformation between metallic Co⁰ and the ZnCoO_x spinel phase under redox conditions accounts for the good regeneration stability of this catalytic system.