A Robust and Efficient Propane Dehydrogenation Catalyst from Unexpectedly Segregated Pt2Mn Nanoparticles

The increasing demand for short chain olefins like propene for plastics production and the availability of shale gas make the development of highly performing propane dehydrogenation (PDH) catalysts, robust towards industrially applied harsh regeneration conditions, a highly important field of research. A combination of surface organometallic chemistry (SOMC) and thermolytic molecular precursor (TMP) approach was used to prepare a nanometric, bimetallic Pt-Mn mate-rial (3 wt% Pt, 1.3 wt% Mn) supported on silica via consecutive grafting of a Mn and Pt precursor on surface OH groups present on the support surface, followed by a treatment under a H2 flow at high temperature. The material exhibits a 70% fraction of the overall Mn as MnII single sites on the support surface; the remaining Mn is incorporated in segregated Pt2Mn nanoparticles. The material shows great performance in PDH reaction with a low deactivation rate. In particular, it shows outstanding robustness during repeated regeneration cycles, with conversion and selectivity stabilizing at ca. 37% and 98%, respectively. Notably, a material with a lower Pt loading of only 0.05 wt% shows an outstanding catalytic per-formance – initial productivity of 4523 gC3H6/gPt h and an extremely low kd of 0.003 h-1 under a partial pressure of H2 – ranging among the highest reported productivities. A combined in situ XAS, STEM, EPR and metadynamics at the DFT level study could show that the strong interaction between the MnII decorated support and the unexpectedly segregated Pt2Mn particles is most likely responsible for the outstanding performance of the investigated materials.