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

Abstract

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 material (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 ro-bustness 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 performance – initial produc-tivity 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 re-sponsible for the outstanding performance of the investigated materials.

Selective Conversion of Syngas to Ethanol over a Tailored Supported RhFe Alloy Catalyst

“…Taken together with catalytic studies and detailed in situ or operando spectroscopic investigations, molecular-level structure-activity relationships and guideline principles can be elaborated, thus providing opportunities for rational catalyst development. Our group has successfully implemented this approach to explore and understand various heterogeneous catalysts used for propane dehydrogenation, [21,22] selective oxidation of methane [23] and CO2 hydrogenation. [20,24,25] Considering the unique ability of Fe to promote the formation of ethanol with Rh-based catalysts, we have thus decided to interrogate the promotional role of Fe in syngas conversion, employing SOMC to prepare well-defined RhFe@SiO2 model catalysts.…”