Nanostructured Ni–Co catalysts: Effect of impregnation sequence and complexing agent

This paper explores the synthesis by the impregnation method using citric acid and the characterization of bimetallic Nickel–Cobalt (Ni–Co) catalysts, focusing on their application in ethanol steam reforming leveraging the demonstrated improved stability and catalytic activity observed in previous works when Co is introduced into Ni catalysts. The study aims to investigate the effects of the sequence of incorporation of Ni and Co in the catalyst support in order to optimize the catalytic performance. The results indicate that the optimal sequence for introducing Co and Ni significantly enhanced the catalytic performance in ethanol steam reforming and it was associated to a higher Ce+3/Ce+4 ratio and a stronger active site-support interactions that modified the CNT growth mechanism, preventing increasing pressure drop through the reactors. The best catalytic performance corresponded to the system, Co/Ni/MgAl2O4–CeO2, in which Co was incorporated after Ni. [Display omitted] •The addition of citric acid helped to obtain particles with a size less than 8 nm.•Impregnation sequence affects to the Ni–Co synergy and reaction performance.•Deposited coke was inversely proportional to the availability of cobalt.•Bimetallic catalyst Co/Ni/MC was more stable over a 30-h evaluation.