Effects of heat-treatment atmosphere and temperature on cobalt species in Co/Al2O3 catalyst for propane dehydrogenation

Co-based catalysts have attracted increasing attention as promising catalysts for propane dehydrogenation (PDH) because of their C-H bond activation ability. Co species in Co/Al2O3 are present in various forms, such as Co3O4, Co-Al2O4, CoO, and metallic Co. However, the catalytic properties of the various Co species in PDH are unclear. In this work, we prepare Co/Al2O3 with different compositional distribution of Co species by heat-treating the supported Co precursor under O-2, Ar, and H-2 atmospheres at temperatures between 500 and 600 degrees C. H-2-treated Co/Al2O3 results in superior performance compared to O-2- and Ar-treated catalysts. This is attributed to the relatively high Co surface concentration and relatively high ratio of tetrahedral Co2+ stabilized in Co-Al2O4 to the total Co species. A detailed study shows that both tetrahedral Co2+ and metallic Co in Co/Al2O3 are active for PDH, but the former is more selective. (C) 2021 Elsevier Inc. All rights reserved.

Automated summary

Co-based catalysts on Al2O3 support with different compositional distribution of Co species were prepared by heat-treating the precursor under O2, Ar, and H2 atmospheres. The H2-treated catalyst showed superior PDH performance due to higher Co surface concentration and higher ratio of tetrahedral Co2+ in Co-Al2O4. Both tetrahedral Co2+ and metallic Co were found to be active for PDH, with the former showing higher selectivity.