Selective oxidative conversion of cyclohexylamine to cyclohexanone oxime using an efficient Co-WO3 catalyst: Experimental and theoretical investigations

[Display omitted] •A solvent-free selective oxidation of cyclohexylamine to CHO under mild conditions afforded.•About 81% conversion and 86.1% selectivity towards CHO observed under optimum reaction conditions.•rGO surface hydroxyl groups played a synergistic role along with the catalytically active Co species experimentally.•The supported CoW (15)/rGO catalyst can be easily separated and reused up to 7 catalytic cycles.•Synergetic role of the rGO and Co upon the reaction of cyclohexylamine and oxygen molecules explored through DFT.•Impact of the Co atom on the reactivity of the cyclohexylamine (repulsive) was opposite to that of O2 molecule (attractive). In this contribution, the successful development of an efficient and green approach for producing cyclohexanone oxime (CHO) through highly selective solvent-free oxidative conversion of cyclohexylamine using rGO-based modified WO3 is reported. The role of rGO was emphasized because the presence of hydroxyl groups upon the surface of this species was revealed liable in the absorption and activation process of cyclohexylamine. Under optimum conditions, a total conversion of 81% with selectivity towards CHO of 86% was obtained. Moreover, the results of Density Functional Theory (DFT) confirms the experimental finding of the synergism between Co and rGO components, through their d and P states, on the reactivity of both cyclohexylamine and molecular oxygen. It was shown that the Co atom has a repulsive effect on the reactivity of cyclohexylamine while being attractive for the O2 molecule at the beginning of the reaction.