The Preparation Of The Novel Ni-Cu/γ-Al₂O₃-ZrO₂ Catalyst In The Dehydrogenation Of Methylcyclohexane And Its Reactivity

With the development of society and technology, we need a new Energy sources standard. The per capita coal, petroleum and natural gas amount in our world has been decreasing year by year, the environmental pollution caused by the traditional energy is becoming more and more serious, the energy crisis and increasingly prominent of environmental problems have forced people to seek new sources of energy. Hydrogen is regarded as the most ideal new energy in twenty-first Century, owning to its high burning value, no pollution and abundant resource. However, the volume density of hydrogen is low, how to improve the high density storage and safety, long distance transportation of hydrogen is the key problem to realize "hydrogen energy society".Organic liquid hydrides have the characteristics of high density, high reversibility of hydrogenation dehydrogenation reaction, safe and good portability in hydrogen storage, is a very promising way to store hydrogen. The mainly organic liquid used as the hydrogen storage carrier is aromatic hydrocarbon compounds（benzene, toluene, naphthalene,）, first the carrier achieves hydrogen through the catalytic hydrogenation reaction, and then releases hydrogen through the catalytic dehydrogenation reaction. The catalytic hydrogenation technology has matured in industry, hence, catalytic dehydrogenation technology has become the bottleneck of the application of organic liquid hydrogen storage, in this paper, the catalytic dehydrogenation of methylcyclohexane was studied on continuous flow micro-reactor dynamic devices.The compound support γ-Al₂O₃-ZrO₂ was prepared by co precipitation method, during the preparation process, ultrasonic technology was used to increase the specific surface area of the, a series of different supports were prepared by changing the molar ratio of Zr/ Al. Supports were charactered by X-ray diffraction, it is showed that Al₂O₃ and ZrO₂ mainly existed in gamma phase and tetragonal phase.Three different Ni-Cu/γ-Al₂O₃-ZrO₂ catalysts were prepared by impregnation, co-precipitation and deposition precipitation method, catalysts were characterized by X-ray diffraction（XRD）, transmission electron microscope（TEM）, specific surface area measurement（BET）,temperature programmed desorption（NH3-TPD）and temperature programmed reduction（H2-TPR）. The results showed that the catalyst prepared by impregnation method has more Ni0, and the Ni-Cu alloy was formed in the catalyst. The surface acidity of the catalyst has a greater impact on catalytic properties, the catalyst prepared by impregnation method containing weak and medium strength acid sites, all catalyst have larger specific surface area, pore size and pore volume, the active groups loaded on the support have no significant effect on the pore size of catalyst.The performance of dehydrogenation of methylcyclohexane with different catalysts was investigated by using the flow dynamic micro reactor, Meanwhile the reaction parameters: reaction temperature, loading of n（Ni）: n（Cu）, n（Al）: n（Zr） and LHSV were optimized. The results showed that the Ni-Cu/γ-Al₂O₃-ZrO₂ catalyst prepared by impregnation showed a better catalytic activity, under the conditions of reaction temperature 450℃, n（Ni）: n（Cu） = 8:2, n（Zr）:n（Al） =0.25,LHSV=10h-1, the methylcyclohexane dehydrogenation conversion rate reached to 82.6%, the selectivity of toluene was close to 98.2%.