Comparative study of propane dehydrogenation over V-, Cr-, and Pt-based catalysts: Time on-stream behavior and origins of deactivation

Catalytic performance of VOx/MCM-41 possessing highly dispersed VOx species in non-oxidative propane dehydrogenation (DH) was compared with that of industrially relevant CrOx/MCM-41 and Pt–Sn/Al2O3 over four DH (24 h on-stream) and oxidative regeneration cycles. The effect of reduction with H2 on the catalysts DH properties was also investigated. VOx/MCM-41 in both oxidized and reduced form showed superior time on-stream stability in all DH cycles and its activity could be fully recovered by oxidative regeneration. In situ time-resolved UV/Vis spectroscopy and temperature-programmed oxidation of the used catalysts enabled us to elucidate the origins of the catalysts deactivation. In a single DH cycle, the formation of carbon deposits is the main reason for the deactivation. Activity loss of CrOx/MCM-41 and Pt–Sn/Al2O3 from cycle to cycle was caused by structural changes in the catalytically active metal/metal oxide species. In contrast to these two catalysts, the structure of active VOx species on MCM-41 was not changed during the DH/regeneration cycles, which is the reason for stable performance of the latter catalyst.

V- and Cr oxide-based catalysts with highly dispersed metal oxide species were prepared using MCM-41 as a support and tested in propane dehydrogenation. VOx/MCM-41 retained its activity through four dehydrogenation/oxidative regeneration cycles thanks to high stability of VOx species, whereas CrOx/MCM-41 gradually lost activity as aggregation of CrOx species occurred..Figure optionsDownload high-quality image (109 K)Download as PowerPoint slideHighlights
► V-, Cr-, and Pt-based catalysts were tested in non-oxidative C3H8 dehydrogenation (DH).
► VOx/MCM-41 showed the lowest deactivation over four 24 h DH cycles.
► Oxidative regeneration fully restored VOx/MCM-41 activity after each DH cycle.
► The other two catalysts lost their activity from cycle to cycle.
► VOx species remained unchanged over 4 DH cycles, while CrOx aggregated.