Hydrogen charging/discharging system with liquid organic compounds : a lacunar oxide catalyst to hydrogenate the unsaturated organic compound
Résumé
Lacunar mixed oxides based on cerium nickel and aluminium or zirconium CeM0.5NiXOYs (M = Zr or Al), able to store high quantities of hydrogen, have been analysed in the hydrogenation of toluene into methyl-cyclohexane (MCH). When these solids present very good toluene hydrogenation activity and selectivity towards MCH in presence of H2, in absence of gaseous hydrogen, the reactive hydrogen species stored in the solid can hydrogenate toluene into MCH. The hydrogenation activity under helium + toluene flow decreases as a function of time and becomes nil. The integration of the curve obtained allows to determine the extractable hydrogen content of the solid used, and a value of 1.2 wt % is obtained at 80°C on a CeAl0.5Ni3OY compound pre-treated in H2 at 300°C. To optimise the system, different parameters have been analysed, such as the catalyst formulation, the metal content, the pre-reducing conditions as well as the reaction conditions under helium + toluene.