Mesoporous silica-immobilized FeCl3 as a highly efficient and recyclable catalyst for the nitration of benzene with NO2 to nitrobenzene

Mesoporous silica-immobilized FeCl3 (FeCl3-SiO2) as a highly efficient and reusable catalyst for the nitration of benzene with NO2 has been successfully prepared in this work. The physical-chemical properties of samples were characterized by BET, XRD, TG-DTG, NH3-TPD, FT-IR, UV-vis DRS, Raman spectra and SEM. The characterization results indicated that FeCl3 could be immobilized on the silica surface by bonding of FeCl3 and silicon hydroxyl groups (Si-OH) in forming the new Lewis acid sites of Si-O-Fe-Cl-2. The results showed the immobilized 15% FeCl3-SiO2 catalyst exhibited excellent catalytic performance (99% of benzene conversion with 99% of selectivity to nitrobenzene) under the optimized reaction conditions. Furthermore, the durability of catalyst was remarkably improved by immobilizing. The present immobilized FeCl3-SiO2 catalyst as a solid heterogeneous and stable catalyst could be conveniently recycled from the reaction media by filtering and remained highly catalytic performance even after five runs of recycling. The possible reaction pathway for the nitration of benzene with NO2 over FeCl3-SiO2 catalyst was suggested. This method provides a promising strategy for highly efficient preparation of nitro aromatic compounds by using NO2 as nitration reagent, with the potential industrial applications. (C) 2016 Elsevier B.V. All rights reserved.