Modulation of the cobalt species state on zincosilicate to maximize propane dehydrogenation to propylene

Abstract

Dispersing metals from nanoparticles into clusters or single atoms often exhibits unique properties such as the inhibition of structure-sensitive side reactions. Here, we reported the use of ion exchange (IE) methods and direct hydrogen reduction to achieve high dispersion of Co species on zincosilicate. The obtained 2Co/Zn-4-IE catalyst achieved an initial propane conversion of 41.4% at a temperature of 550 °C in a 25% propane and 75% nitrogen atmosphere for propane dehydrogenation. Visualization of the presence of Co species within specific rings (alpha-α, beta-β and delta-δ) was obtained by aberration-corrected scanning transmission electron microscopy. A series of Fourier transform infrared spectra confirmed the anchoring of Co by specific hydroxyl groups in zincosilicate and the specific coordination environment of Co and its presence in the rings essentially as a single site. The framework Zn for the modulation of the microenvironment and the presence of Co species as Lewis acid active sites (Co-O₄) was also supported by density functional theory calculations.