The Preparation Of The Hydrogen Carrier Methylcyclohexane's Dehydrogenation Catalyst Ni-Cu/γ-Al₂O₃ And Its Reaction Performance

With the continuing escalation of global energy issues, dwindling oil resources, the environmental pollution problems having become more prominent and the full implementation of environmental sustainable development strategies, hydrogen has been deemed as the best green energy in the 21st century or even in the future because of its rich, renewability, high efficiency, non-polluting and the other excellent properties. In the "hydrogen economy", to develop a safe and efficient hydrogen storage technology is particularly critical. Organic liquid hydride hydrogen storage technology is a hydrogen storage method of making the use of some unsaturated liquid hydridesuch as alkenes, alkynes or aromatic hydrocarbons and hydrogen to achieve the reversible hydrogenation and dehydrogenation reactions. This paper focused on the study of catalytic dehydrogenation reaction of methylcyclohexane.The three different Ni-Cu/γ-Al₂O₃ bimetallic catalysts were prepared by co-precipitation method, impregnation method and co-precipitation-impregnation method. Meanwhile in the process of preparing, the catalyst surface area was greatly improved because of useing the ultrasonic aid. The three Ni-Cu/γ-Al₂O₃ bimetallic catalysts for dehydrogenation of the hydrogen carrier methylcyclohexane (MCH) catalytic performance was investigated by using continuous flow micro-reactor dynamic-chromatography devices. The catalysts'internal phase structure and surface morphology were characterized by X-ray diffraction analysis (XRD), scanning electron microscopy (SEM) and specific surface area measurements (BET).The results showed that using the Ni-Cu/γ-Al₂O₃ bimetallic catalyst prepared by co-precipitation-impregnation method is better than the others, at the same time the Ni-Cu loading of the three catalysts were 26% and the proportion of nickel and copper was 8 to 1. Under the conditions of the reaction temperature 673K, reaction pressure 0.6MPa, volume flow ratio MCH/N₂ = 19/27 and the volume of gas space velocity 240 h-1 , methylcyclohexane dehydrogenation conversion rate reached 98.5% and the product selectivity was close to 100% .Experiments also compared the 26%Ni-Cu/γ-Al₂O₃ bimetallic catalyst prepared by co-precipitation - impregnation method with the 3%Pt/C catalyst and the 20%Ni-Cu/γ-Al₂O₃ catalyst. All the three catalysts had good dehydrogenation activity under the high-temperature, besides, the Ni-Cu/γ-Al₂O₃ bimetallic catalyst prepared by co-precipitation-impregnation method had the higher conversion rate of dehydrogenation in the reaction temperature of 673K. But the Pt/C catalyst had the excellent dehydrogenation activity at low-temperature, and the Ni/γ-Al₂O₃ single metal catalyst in these two areas was in a relative disadvantage.