Fig. 6: Active species and mechanism.
From: Mixed-valence Co0/IIOx clusters on silicalite-1 facilitate propane dehydrogenation to propene
a, The initial propene formation rate over 1.1Co-S-1 in the absence and presence of co-fed oxygen. Reaction conditions: T = 500 °C, 40 vol% C3H8 in N2 or N2 containing 0.1 vol% O2, and WHSV(C3H8) = 70.7 h−1. b,c, Transient responses recorded upon pulsing C3H8/Ar = 1:1 over 1.1Co-S-1 after oxidation (b) and reduction (c) at 500 °C. d, Gibbs free-energy profiles of the PDH reaction on (Si–O)4Co4O2 (blue) and (Si–O)4Co4 (black). Optimization was performed at the PBE-D3 level of theory and Gibbs correction at 773 K. The corresponding energies (ΔG‡ or ΔGr) of the elementary steps are given in parentheses. In the structures, blue, red, yellow, grey and white balls represent Co, O, Si, C and H atoms, respectively.
