Magnetically separable core-shell structural γ-Fe_2O_3@Cu/Al-MCM-41 nanocomposite and its performance in heterogeneous Fenton catalysis

摘要

To target the low catalytic activity and the inconvenient separation of copper loading nanocatalysts in heterogeneous Fenton-like reaction, a core-shell structural magnetically separable catalyst, with γ-Fe_2O_3 nanoparticles as the core layer and the copper and aluminum containing MCM-41 as the shell layer, has been fabricated. The role of aluminum has been discussed by comparing the copper containing mesoporous silica with various Cu contents. Their physiochemical properties have been characterized by XRD, UV-vis, FT-IR, TEM, nitrogen physisorption and magnetite susceptibility measurements. Double content Cu incorporation results in an improved catalytic activity for phenol degradation at the given condition (40℃, initial pH = 4), but leads to a declined BET surface area and less ordered mesophase structure. Aluminum incorporation helps to retain the high BET surface area (785.2 m~2/g) and the regular hexagonal mesoporous structure of MCM-41, which make the catalyst possess a lower copper content and even a higher catalytic activity than that with the double copper content in the absence of aluminum. The catalysts can be facilely separated by an external magnetic field for recycle usage.