Preparation Of Supported Nanometer Heterogeneous Catalysts And Study Of Their Applications In Catalytic Transfer Hydrogenation Reactions

Aromatic amines are important intermediates widely used in the fields of medicine,dyes,pesticides and fine chemicals.The common preparation method is to reduce the corresponding aryl nitro compounds.Several metals or its salts which have been used as reducing agent for the hydrogenation of nitro chemicals,such as such as Fe,Zn,Sn and metal salts etc.However,these methods have some shortcomings such as the pollution of vast industrial wastes.Hydrogenation of double bonds is an important transformation reaction in the fabrication of fine and commodity chemicals,functional materials and pharmaceuticals.?-Valerolactone has been widely used as a fuel additive,solvent,liquid fuel and raw material for the fabrication of other value-added chemicals.Alkene hydrogenation and the hydrogenation of?-valerolactone are commonly conducted with pressurized hydrogen?H₂?catalyzed by various metal catalysts.The reaction is generally conducted at high pressure and high temperature.In addition,H₂ is flammable and difficult to handle.The catalytic transfer hydrogenation?CTH?that utilizes safe hydrogen donors other than H₂ has been considered as a prospective approach for the hydrogenation reaction.In recent years,Formic acid?FA?and alcohol have been regarded as a promising and sustainable hydrogen sources because of their no obvious toxicity,excellent stability and easy handling capability.The triazine organic frame with excellent physical and chemical properties can be used as catalysts or support.Nitrogen-doped porous carbon is widely used in catalysis because of its large specific surface,thermal stability and rich nitrogen content.Alumina is also a commonly used carrier or catalyst.Its stability can be enhanced by adding other oxides.In this work,several metal catalysts including triazine organic framework,nitrogen-doped porous carbon and metal oxide supported catalysts were prepared.They are employed in the catalytic transfer hydrogenation of nitro compounds,olefin compounds and levulinate esters:1.Pd nanoparticles supported on the triazine organic framework?Pd@CTF?were fabricated and employed to catalyze the transfer hydrogenation of nitro compounds with HCOOH-NH₄OOH as the hydrogen source.The results showed that Pd@CTF displayed excellent catalytic activity and high chemoselectivity for the hydrogenation reaction at room temperature.2.Ultrafine palladium nanoparticles were immobilized on nitrogen-enriched porous carbon nanosheets?NPC?by wet impregnation method.The prepared Pd@NPC exhibited superior catalytic activity and chemoselectivity for the catalytic transfer hydrogenation of alkenes under mild conditions with HCOOH-NH₄OOH as a hydrogen donor.Moreover,the catalyst displays high structure stability,and can be reused for five runs without any significant decrease of its catalytic activity and obvious leaching of Pd species.3.A high-performance Cu-Ni bimetallic catalyst supported on Zr-Al oxides was fabricated for the catalytic transfer hydrogenation?CTH?of levulinate esters into?-valerolactone?GVL?under mild conditions.The optimized Cu₂Ni₁/Zr₃Al₇O_z catalyst provided the highest ethyl levulinate conversion of 99%with 96.8%GVL yield at 150^oC usinging 2-butyl alcohol?2-BuOH?as the hydrogen source.The catalyst shows excellent catalytic and selectivity and can be reused 5 times without significant loss of catalytic activity.