Article Link: https://pubs.acs.org/doi/abs/10.1021%2Facscatal.8b00650
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The oxidative
dehydrogenation of propane is an attractive reaction for propylene production,
but the overoxidation leads to low propylene selectivity at considerable propane
conversions. Here, we report the oxidative dehydrogenation of propane by oxygen
in the presence of hydrogen chloride. CeO2 was found to be an
efficient catalyst for the conversion of propane to propylene by (O2 + HCl). The reaction was structure-sensitive, and the catalytic behavior
depended on the exposed facet of CeO2 nanocrystals. The nanorod
exposing {110} and {100} facets showed the highest activity, whereas the
nanocube enclosed by {100} facets was the most selective for propylene
formation. The modification of CeO2 nanorods by NiO increased both
propane conversion and propylene selectivity. A propylene selectivity of 80% was
achieved at propane conversion of 69% over an 8 wt % NiO–CeO2 catalyst at 773 K, offering a single-pass propylene yield of 55%. No significant
catalyst deactivation was observed in 100 h of reaction. HCl played a pivotal
role in the selective formation of propylene, and more than 95% of HCl could be
recovered after the reaction. The structure–property correlation indicates that
the surface oxygen vacancy and the surface chloride coverage are two crucial
factors determining the activity and selectivity. The mechanistic studies
suggest that the peroxide species (O22–) formed by
adsorption of O2 on surface oxygen vacancies may activate chloride,
generating a radical-like active chlorine species. The active chlorine species
accounts for the activation of C–H bond of propane, forming propylene as a major
product.
"Oxidative Dehydrogenation of Propane to Propylene in the Presence of HCl Catalyzed by CeO2 and NiO-Modified CeO2 Nanocrystals."Q. Xie; H. Zhang; J. Kang; J. Cheng; Q. Zhang; Y. Wang, ACS Catal 2018, 8, 4902-4916.
