The effect of copper on benzene hydrogenation to cyclohexane over Ni/Al2O3 catalyst

•Copper as an efficient modifier of Ni/Al2O3 catalyst for benzene to cyclohexane hydrogenation.•Considerably better selectivity of Ni–Cu catalyst compared to the reference one due to enrichment of the catalyst surface with copper.•Improvement of the catalytic activity upon addition of up to 20 wt% CuO and decrease of the activity above that content.

The effect of a copper modifier on physicochemical properties of coprecipitated precursors and final Ni–Cu/Al2O3 catalysts for benzene to cyclohexane hydrogenation was investigated. Based on the studies of physicochemical properties, the influence of copper on the catalytic activity and selectivity of Ni–Cu/Al2O3 systems was discussed. The addition of copper resulted in a decrease of the specific and nickel surface area, improvement of the selectivity and a slight decrease of the benzene hydrogenation activity compared to the reference catalyst. A decrease of methylcyclopentane and methylcyclohexane by-products formation on the surface of Ni–Cu/Al2O3 catalyst containing 10–17 wt% CuO by, respectively, 70% and 10% was observed. The results reveal a distinct, beneficial effect of the Ni/Al2O3 modification by copper on the catalyst selectivity. However, this effect depends on temperature and is limited to ca. 20 wt% CuO, above this content the activity was found to decrease considerably.

Graphical abstractFigure optionsDownload full-size imageDownload high-quality image (211 K)Download as PowerPoint slide