Benzene hydrogenation over Ni/Al2O3 catalysts prepared by conventional and sol-gel techniques

摘要

Nickel supported on alumina catalysts have been prepared using various synthesis methods (dry impregnation,co-precipitation,sol-gel) and evaluated for the hydrogenation of benzene contained in gasoline.The evaluation was carried out in a laboratory scale high pressure fixed bed reactor fed with a stream of surrogated reformate gasoline consisted by a mixture of hexane,benzene and toluene.All catalysts have been characterized by the joint use of various physicochemical characterization methods (XRF,BET,TGA,SEM,XRD,UV-vis DRS and XPS) in order to correlate their catalytic performances to their physicochemical properties.The results obtained revealed that sol-gel procedure,especially when it is followed by supercritical drying (aerogel),produced the most promising catalysts for the aforementioned catalytic process.Sol-gel methodology ensured the best compromise between dispersion of the nickel phase and its interaction with the support surface.Co-precipitated catalysts exhibited important activities but lower than those of the sol-gel catalysts.The catalyst prepared by dry impregnation proved to be the less active.Calcination of the catalysts before their activation by reduction decreased their activities.