[en] High-activity, visible-light-driven photocatalysts were prepared by forming N-doped TiO₂ on multi-walled carbon nanotubes (MWCNTs). The use of MWCNTs as the support in a N-doped TiO₂ system favored electron trapping, because the recombination process could be retarded, thus promoting photocatalytic activity. The prepared photocatalysts were systematically characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunaure-Emmett-Teller (BET) spectroscopy, and UV-Vis diffuse reflectance spectroscopy (UV-Vis/DRS). The results indicated that the N-doped TiO₂ coated on MWCNTs improved the surface area and slightly modified the optical properties of the composite. The activities of the photocatalysts were probed by photodegradation of methanol in the presence of visible light irradiation. The experimental results revealed that the strong interphase linkage between the MWCNTs and the N-doped TiO₂ played a significant role in improving photocatalytic activity. However, the mechanical process for MWCNT-TiO_2-xN_x mixtures showed lower activity than just pure N-doped TiO₂. In this study, N-doped TiO₂ precursors coated with pretreated MWCNTs during a sol-gel process could effectively form a MWCNT-TiO_2-xN_x composite. The composite showed excellent activity and effectively enhanced the efficiency of N-doped TiO₂ under the visible light region.

[en] This study investigated the activities of prepared and commercial V₂O₅-WO₃ catalysts for simultaneous removals of NO and polycyclic aromatic hydrocarbons (PAHs) and the influences of particulates, heavy metals, SO₂, and HCl on the performances of catalysts. The experiments were carried out in a laboratory-scale waste incineration system equipped with a catalyst reactor. The DREs of PAHs by prepared and commercial V₂O₅-WO₃ catalysts were 64% and 72%, respectively. Increasing the particulate concentrations in flue gas suppressed the DRE of PAHs, but increasing the carbon content on surface of catalysts promotes the NO conversions. The DRE of PAHs by the catalysts was significantly decreased by the increased concentrations of heavy metal Cd, but was promoted by high concentration of Pb. The influence level of SO₂ was higher than HCl on the performances of V₂O₅-WO₃ catalysts for PAHs removal, but was lower than HCl for NO removal. Prepared and commercial V₂O₅-WO₃ catalysts have similar trends on the effects of particulates, heavy metals, SO₂, and HCl. The results of ESCA analysis reveal that the presences of these pollutants on the surface of catalysts did not change the chemical state of V and W.