Studies On Non-oxidative Dehydrogenation Of Cyclohexane

Cyclohexane,as a kind of important basic chemical material,not only can be used as organic liquid hydrogen storage material,but also can be used for preparing cyclohexene,an important intermediate of manufacturing nylon products.The preparation of cyclohexene with cyclohexane non-oxidation selective dehydrogenation can prevent the excessive oxidation of cyclohexane oxidation dehydrogenation process.It can form a cyclic reaction system with the selective hydrogenation process of benzene and efficiently utilize carbon atom.However,higher reaction temperature is required in cyclohexane non-oxidation dehydrogenation process.Therefore,to gain higher selectivity and yield of cyclohexene by controlling the cyclohexane non-oxidation dehydrogenation process through the different catalysts and reaction conditions is an important role to realize the high added value of cyclohexane.First of all,the cyclohexane non-oxidation complete dehydrogenation process was studied.The performance of Pt-Sn catalyst loaded by the different supports?ZSM-5,SiO₂,MgAlO and Al₂O₃?was respectively compared.The structure of catalyst was identified through a variety of characterization methods.Besides,the influence of the catalyst calcination temperature and reaction temperature under nitrogen atmosphere on the catalytic performance was explored.The stability of superiority catalysts Pt-Sn/MgAlO and Pt-Sn/Al₂O₃ under the high temperature was examined.In the non-oxidation complete dehydrogenation process of cyclohexane,catalyst Pt-Sn/Al₂O₃reduced the reaction temperature to 300?and presented excellent benzene selectivity?>96%?and stability.Secondly,the cyclohexane non-oxidation selective dehydrogenation process was explored.The effect of hydrogen atmosphere on the superiority catalysts Pt-Sn/MgAlO and Pt-Sn/Al₂O₃ for cyclohexane conversion and cyclohexene selectivity was discussed.Moreover,the influence of Mn/Ru-modified Ni-Cu/SiO₂ catalyst on cyclohexene selectivity was also explored.Hydrogen atmosphere significantly increased the dehydrogenation reaction temperature and reduced cyclohexane conversion,but also improved the selectivity of cyclohexene.The results showed that the highest cyclohexene selectivity on catalyst Ni-Cu?Ru?/SiO₂ was 56.23%,while the maximum cyclohexene yield on catalyst Pt-Sn/MgAlO was 4.82%.The reaction process under different carrier atmospheres was compared.The results showed that nitrogen atmosphere could help to reduce the reaction temperature of cyclohexane non-oxidation dehydrogenation process,and that hydrogen atmosphere could help to improve the selectivity of cyclohexane in the process of cyclohexane dehydrogenation process.The study is reference significance for the cyclic utilization of cyclohexane,a by-product in the process of benzene selective hydrogenation.