Nitrogen-doped Carbon Nanotubes Preparation And Their Catalytic Performance In Nitro Compounds Hydrogenation Reaction

Metals usually serve as the active site of hydrogenation reaction,and the most widely used catalyst is the noble metal supported catalyst.The price of this kind of catalysts are relatively high,so many researchers began to study low-cost metals,such as Cu,Ni.Carbon nanotubes possess good electrical conductivity,thermal conductivity,high stability and mechanical strength,it can be used as catalyst support,in addition,heteroatom doping carbon nanotubes as a nonmetallic catalyst are used in oxygen reduction reaction.This thesis is mainly to prepare a kind of non-metallic mineral nitrogen carbon nanotubes(NCNTs)which can be applied to the hydrogenation of nitro compound.Then these catalysts were characterized and we optimize the reaction conditions.In this thesis,NCNTs has been in-situ synthesized and post-treatment synthesized,in-situ synthesized NCNTs have obvious bamboo-like structure.The post-treatment synthesized NCNTs catalyst showed catalytic performance in the hydrogenation of 1,5-dinitronaphthalene,but with low selectivity of 1,5-diamino-naphthalene,and the NCNTs can catalyze nitro naphthalene,the selectivity of aniline can reach to 90% in the hydrogenation of nitrobenzene under the right conditions.So we think the hydrogenation of nitrobenzene showed better cataly t-ic performance when use the NCNTs as catalyst.And the m-ONCNTs-800 has been seen as the optimal catalyst which was prepared on 800?.In this thesis,deeper research of nitrobenzene hydrogenation have been done,after the hydrogenation process proceed 8h the conversion of nitrobenzene reach to 59.74% and the selectivity of aniline reach to 91.48% under the condition of 1g nitrobenzene,0.1g catalyst,20 ml ethanol,170?,4 MPa,reaction time is 8h.I have confirmed that the nitrobenzene hydrogenation process is a nonmetal catalytic process and the active site of this process is the doping N atom,the quaternary N and the pyridinic N are the major factor that affect the nitrobenzene hydrogenation.Through the simulation calculation we know that the N doping can change the the energy level of the highest-occupied molecular orbitals(HOMO)and the lowest-unoccupied molecular orbitals(LUMO),and the N atom of the NCNTs with more electronegativity,the surrounding C atom carry obviously positive charge.Which says that the chemical activity around the doping N atom should be more active.Calculation results show that between nitrogen doped carbon nanotubes and H2 is chemical adsorption,between carbon nanotubes and H2 is more difficult to generate chemical bond.