Characterization and performance of a [PtMo6]/MgO catalyst for alkane-to-alkene conversion

A novel [PtMo6]/MgO ensemble catalyst was prepared by using an inorganic cluster [PtMo2O24](8-) as precursor and characterized by X-ray absorption fine structure (XAFS) spectroscopy. The EXAFS analysis revealed that platinum and molybdenum atoms interact with MgO support after calcination at temperatures above 673 K, making Pt-O, Pt-Mg and Pt-O (long) bonds, and Mo-O and Mo-Mg bonds, respectively, It was suggested that Pt4+ ions replaced M(2+) ions of the top layer of the MgO surface, while Mo6+ ions located on the surface in a distorted octahedral symmetry. The dehydrogenation activity of the [PtMo6]/MgO catalyst for the dehydrogenation reactions of butane, isobutane and propane was much higher compared to those of conventionally prepared bimetallic (Pt-Mo/MgO) and monometallic (Pt/MgO and Mo/MgO) catalysts. The selectivity to the corresponding alkenes was typically above 97%. The [PtMo6]/MgO ensemble catalyst was found to be resistant to deactivation due to coke formation.