Unsaturated cobalt single-atoms stabilized by silanol nests of zeolites for efficient propane dehydrogenation

Abstract

Propane dehydrogenation (PDH) has emerged as a key on-purpose technology for the production of propylene, but it often depends on toxic chromium and expensive platinum catalysts, highlighting the need for environmentally friendly and cost-effective alternatives. In this study, we developed a facile impregnation method to fabricate unsaturated Co single-atoms with a tricoordinated Co₁O₃H_x structure by regulating silanol nests in purely siliceous Beta zeolites. Detailed PDH catalytic tests and characterizations revealed a positive correlation between the presence of silanol nests and enhanced catalytic activity. Additionally, the unsaturated Co single-atoms exhibited a carbon deposition rate more than an order of magnitude slower than that of Co nanoparticles. Notably, the optimized Co_0.3%/deAl-meso-Beta catalyst achieved a record-high propylene formation rate of 21.2 mmol_C3H6 g_cat^–1 h^–1, with an exceptional propylene selectivity of 99.1% at 550 °C. Moreover, the Co_0.3%/deAl-meso-Beta catalyst demonstrated excellent stability, with negligible deactivation after 5 consecutive regeneration cycles. This study emphasizes the pivotal role of silanol nests of zeolites in stabilizing and modulating the coordination environment of metallic active sites, providing valuable insights for the design of high-activity, high-stability, and low-cost PDH catalysts.