The Study On The Hydrogenation Of Nitroaromatic Compounds Catalyzed By Iron Oxides

Hydrogenation is one of the most valuable synthetic transformations,in petroleum refining and processing and the manufacture of fine and bulk chemicals.In particular,the hydrogenation of substituted nitroarenes to the corresponding anilines is of great importance because anilines are among the most important organic intermediates necessary for the manufacture of many valuable products such as dyestuffs,pharmaceuticals,and agricultural chemicals.A significant number of investigations have been devoted to creating new catalysts for the efficient hydrogenation of nitrobenzene.Indeed,aromatic nitro compounds can be hydrogenated by platinum,palladium,rhodium and Pd@Au catalysts.However,when the substrates contain other reactive groups,such as ketones,aldehydes,alkenes or alkynes,the selective reduction of-NO2 becomes particularly difficult.Moreover,the high price and limited availability of these precious metals have spurred interest in catalysis with more earth-abundant alternatives.The main purpose of this paper is to explore new and efficient non-noble metal catalysts for the hydrogenation of substituted nitroarenes to the corresponding anilines,through hydrogenation testing and characterization analysis to find the key to its catalytic activity and provide theoretical and practical basis for the development of new catalysts.Herein,we studied the catalytic activity of several iron oxide catalysts with similar structure and surface area.It is found that ?-Fe2O3,?-Fe2O3,and FeO show obvious but a little limited activity,but the activity of used catalyst is increased in the second run,especially for ?-Fe2O3.Characterization shows the Fe2O3 is partly reduced with many oxygen vacancies produced on the surface,which accounts for the high hydrogenation activity.Finally,Fe₃O₄ exhibits activity significantly higher than Fe2O3 and FeO,and 100% selectivity in the hydrogenation of nitroarenes to anilines.Also,Fe₃O₄ is easy to separate by a magnetic field and shows excellent recycling stability.Based on previous laboratory research and taking into account the advantages of carbon material,we added two transition metals Fe and W while making metal-organic framework materials to make bimetallic metal-organic framework materials.We studied the catalytic hydrogenation performance of carbon materials,which were obtained from bimetallic metal-organic framework materials through further high temperature sintering in inert atmosphere.When the two metals are both present,the activity of calcination at 700 and 500 °C generated oxides phase is very limited,but 900 °C high temperature calcination generated Fe6W6 C crystalline phase plays a key central role in the hydrogenation reaction.Finally,the catalyst calcinated at 900 °C exhibits high activity significantly and nearly 100% hydrogenation selectivity.Also,PTA @ MOF-900-N2 shows excellent recycling stability.