Insight into crystal-plane-dependent of cobalt catalysts for ethylene glycol amination

Abstract

Co possesses outstanding dehydrogenation and hydrogenation activitiy and is a suitable catalyst for the amination of ethylene glycol. Nevertheless, the catalytic activity of Co's different crystal surfaces remains unclear, which hinders the further advancements in its catalytic efficiency. This research comprehensively examines the influence of Co's crystal plane effect on the amination of ethylene glycol employing both experimental and theoretical methodologies. Three single-crystal Co catalysts with mainly exposed (10−11), (0001) and (11−20) crystal planes were synthesized by a hydrothermal method and evaluated for ethylene glycol amination. The experimental results indicated that the c-Co-R catalyst with exposed Co (11–20) crystal facets exhibits optimal performance, with a 55.4 % ethylene glycol conversion and a 43.7 % primary amines (ethylenediamine and ethanolamine) selectivity. Combined with density-functional theory calculations and experimental characterization, the results showed that the Co (11−20) surface exhibited robust C-H bond dissociation and strong adsorption of ethylene glycol, which markedly improved the dehydrogenation efficiency of ethylene glycol and improved ethylene glycol conversion. Furthermore, the weak adsorption capacity of NH3 further promoted the selectivity of the target products.