The integrated photocatalytic removal of SO2 and NO using Cu doped titanium dioxide supported by multi-walled carbon nanotubes

In this paper, the titanium dioxide supported by multi-walled carbon nanotubes (MWCNTs/TiO2), and Cu doped TiO2 supported by MWCNTs (MWCNTs/Cu-TiO2) were synthesized in a sol-gel method. Characterizations of the prepared photocatalysts were done by means of transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and UV-Vis diffuse reflectance spectra (DRS). The introduction of MWCNTs inhibited the grain growth of TiO2. The excellent optical properties in the UV and visible region were observed on 10% MWCNTs/Cu-TiO2 and 15% MWCNTs/Cu-TiO2. The oxidation and removal efficiencies of SO2 and NO in simulated flue gas were investigated experimentally in a fix-bed reactor. The optimal conditions (73 mg/m(3) NO, 155 mg/m(3) SO2, 8% O-2, 5% H2O) were determined, and 62% and 43% of total SO2 and NO removal were achieved on 15% MWCNTs/Cu-TiO2. The enhancement of 15% MWCNTs/Cu-TiO2 on photocatalytic oxidation was related to modified electronic structure and surface Oxygen vacancies, and also to good conductivity of MWCNTs. The integrated desulfurization and denitration efficiencies were lower than that in baseline experiments due to SO2 and NO competing for adsorption sites. O-2 and H2O played important roles in the formation of O-2(-), O- and (OH)-O-center dot. In addition, the possible reaction mechanism involved in the integrated desulfurization and denitration was also proposed here. (C) 2014 Elsevier B.V. All rights reserved.