Preparation and characterization of N–Ti-MCM-22 mesoporous molecular sieve and investigation of its photocatalytic properties

Abstract

Nanocrystalline N-doped and Ti-containing MCM-22 catalyst was synthesized by the static hydrothermal method, using sodium azide as nitrogen source for doping, and tetra-n-butyl titanate [Ti(OC4H9)4] as precursor for TiO2. The catalysts were characterized by X-ray diffraction, transmission electron microscopy, and energy-dispersive spectroscopy. The results showed that a mesoporous region with ca. 3-nm pore size was created by expansion between lamellar crystalline sheets in Ti-MCM-22. Nitrogen was substituted for some of the lattice oxygen atoms. During liquid phase photocatalytic degradation of methylene blue under high-pressure Hg arc lamp irradiation, the as-prepared N-doped Ti-MCM-22 exhibited much higher activity than the undoped Ti-MCM-22, attributed to the effect of the nitrogen dopant. The effects of N-doping amount, catalyst concentration, initial solution pH, and initial concentration of MB on the photocatalytic activity were investigated.