Zeolite-encaged Ultrasmall Pt-Zn Species with Trace Amount of Pt for Efficient Propane Dehydrogenation

Propane dehydrogenation(PDH)has become a globe-welcoming technology to meet the massive demand for propylene,but the most commonly used Pt-based catalysts suffer from quick sintering,poor selectivity for propylene,and unsatisfied Pt utilization.Herein,a series of Silicalite-1(S-1)zeolite-encaged ultrasmall Pt-Zn clusters with a trace amount of Pt[40—180 ppm(parts per million)]were developed by using a one-pot ligand-protected direct H_(2) reduction method.Interestingly,the extremely low amount of Pt can significantly promote the activity of zeolite-encaged Zn catalysts in PDH reactions.Thanks to the high Pt dispersion,the synergy between Pt and Zn species,and the confinement effect of zeolites,the optimized PtZn@S-1 catalyst with 180 ppm Pt and 1.88%(mass fraction)Zn,exhibited an extraordinarily high propane conversion(33.9%)and propylene selectivity(99.5%)at 550℃with a weight hourly space velocity(WHSV)of 8 h^(-1),affording an extremely high propylene formation rate of 340.7 mol_(C_(3)H_(6))·g_(Pt^(-1))·h^(-1).This work provides a reference for the preparation of zeolite-encaged metal catalysts with high activity and noble metal utilization in PDH reactions.