Preparation Of Transition Metal Catalysts And Their Application In Dehydrogenation Of Cyclohexanol And Hydrogenation Of Nitrobenzene

Cyclohexanone,as an important chemical raw material and organic solvent,is widely used in industrial production.The copper-based catalysts were used in the dehydrogenation of cyclohexanol?They have the problem of easy to sinter in high temperature,which limits their catalytic activity;Aniline is the raw materials used to produce polyurethanes,which are mainly produced by high-pressure liquid hydrogenation of nitrobenzene in industrial production,which has the disadvantages of high catalyst cost,large reaction pressure,and low thermal efficiency.Transition metal phosphide catalysts and Ni-Mo composition catalysts are currently mainly used in the fields of hydrodenitrogenation and hydrodeoxygenation,exhibit excellent activity and stability,which can overcome the above problems.In this paper,the transition metal phosphides and Ni-Mo catalysts were prepared by impregnation method and solid phase method,characterized by XRD,XPS,SEM,BET,etc.The cyclohexanol and nitrobenzene were used as models to investigate catalytic activity.Firstly,Ni2P/Al2O3 and Cu3P/Al2O3 catalysts were prepared from different raw materials.Compared with the dehydrogenation properties of these catalysts,the cyclohexanol conversion and cyclohexanone selectivity of Ni2P catalyst was superior to that of Cu3P catalyst.After optimizing the catalyst preparation raw materials,loading amount and modification method,it was concluded that nickel hypophosphite was used as a raw material and the loading amount was 10%,the magnesium oxide was added as an additive.The conversion was 72.6%,the selectivity to cyclohexanone is 72.7%,and the selectivity to cyclohexene is 21.6%in this condition.Ni-Mo composite catalyst was prepared by solid-phase method and its hydrogenation performance was investigated.First,the optimum catalyst preparation and hydrogenation reaction conditions were optimized:the catalyst composition ratio was Ni/Mo=10.7,the reduction time was 5 h,the temperature was 80° C.the hydrogen flow rate was 25 ml/min,and the reaction time was 8 h.The maximum conversion rate of nitrobenzene was 90%,and the selectivity was 99.1%.The by-products were azobenzene,azoxybenzene,and N-phenylhydroxylamine.In addition,the recycling experiment showed that the catalyst had good stability.Finally,the effects of Mo addition on the structural properties of Ni-Mo catalysts were investigated by XRD,XPS,SEM and BET.With the continuous addition of Mo,the crystallinity of the active components in the catalyst continuously decreases.At the same time,Mo concentrates on the surface of the catalyst and forms a complex oxide NiMo4,and there is an electron transfer between Ni and Mo,showing a strong interaction.After adding Mo,the catalyst transforms from a hardened state to a granular state,the specific surface area and pore volume increase gradually,the pore size distribution gradually becomes uniform.At the same time,At the same time,the law of catalytic properties change are the same as those of structural properties..The Ni2P/Al2O3 catalyst and the Ni-Mo composite catalyst demonstrated good catalytic performance.This can provide an important basis for further study of cyclohexanol dehydration and nitrobenzene hydrogenation reactions.