Preparation Of Ni-Al Catalysts And The Application In Selective Hydrogenation Of Aromatic Nitro-compounds

Chloroanilines being the important organic intermediates,are wildly applied in the synthesis of rubber,adhesives,coatings,pharmaceutical and other chemical in industry.Selective hydrogenation of chlonitrobezenes is regarded as an alternative route to obtain chloroanilines.Therefore,the design of catalyst with high activity and low toxicity is very important.The earth-abundant element Ni,is regard as one of the most potential commercial hydrogenation catalysts and tremendous progress has been made.This work focus on the selective hydrogenation of chloronitrobenzene,the development of nickel based catalysts with high activity and selectivity.In this work,a series of Ni based catalysts were synthesized and tested in the selective hydrogenation of chloronitrobenzene.Various characterization techniques such as XRD,BET,TEM,SEM-EDS and EA were applied to investigate physical structure.?1?The parameters of catalyst synthesis and selective hydrogenation of o-CNB were researched.And the expansion of substrate was explored over the Ni/?-Al₂O₃-773-573catalyst.?2?The effect of the properties of biochar for selective hydrogenation of o-CNB was investigated over the modified Ni/MC-Al₂O₃ catalysts.The substrate expansion and the preliminary mechanism were studied on the Ni/MC-Al₂O₃-A₂ catalyst.?3?The characterizations of Ni/?-Al₂O₃ and Ni/MC-Al₂O₃ catalysts were charactered by BET,XRD and TEM,which provided theoretical basis for further study.The results showed that for the Ni/?-Al₂O₃ catalysts,especially the Ni/?-Al₂O₃-773-573 with the largest specific surface area and the smallest Ni particles demonstrated the highest activity.The conversion of o-CNB and the selectivity of o-CAN reached 92.6%and 95.6%,respectively.The reactivity of chloronitrobenzene isomers followed the order of o-CNB>p-CNB>m-CNB on Ni/?-Al₂O₃-773-573 catalyst,while a different order,o-CNB>m-CNB>p-CNB,was obtained on Ni/MC-Al₂O₃-A₂ catalyst.The reason may be related to the surface properties that affecting the adsorption of chloronitrobenzene isomers.For the modified Ni/MC-Al₂O₃ catalyst,non-metal incorporated Ni/MC-Al₂O₃-A₂ catalyst showed 15%increase in the selectivity of o-CAN.Also,Ni/MC-Al₂O₃-A₂ were found to be effective in other nitro-compounds selective hydrogenation containing-Br and-CH=CH₂groups.It's proposed that the adsorption of chlornitrobenzene through-NO₂ groups on benzene ring is favorable on the modified surface of Ni/MC-Al₂O₃-A₂ catalyst.