Effect of F, V and Mn co-doping on the catalytic performance of TiO₂-pillared bentonite in the photocatalytic denitration

F, V and Mn co-doped TiO₂-pillared bentonite was prepared by the sol-gel method and characterized by XRD, nitrogen sorption, UV-vis spectroscopy, SEM, etc.; its performance in the photocatalytic denitration of NO was investigated under visible light irradiation at room temperature. The results indicate that the photocatalytic denitration efficiency of F-V-Mn co-doped TiO₂-pillared bentonite for NO at a concentration of 661 μg/m³ is approximately 100%; when the concentration of NO increases to 1657 μg/m³, the photocatalytic efficiency decreases to 81.9%, which is however 33.8% higher than that over the unpillared F-V-Mn co-doped TiO₂. The reaction rate constant over the F-V-Mn co-doped TiO₂-pillared bentonite is twice as high as that over the V-Mn co-doped TiO₂ pillared bentonite; moreover, the F-V-Mn co-doped TiO₂-pillared bentonite also displays improved resistance against water and SO₂ poisoning. TiO₂ pillars can not only retain the flaky crystal structure of bentonite, but also increase the distance between bentonite layers from 0.667 to 0.710 nm and enhance the adsorption capacity. Meanwhile, the doping elements can inhibit the growth of TiO₂ rutile and reduce the band gap of TiO₂, which is effective in improving the response to visible light, prolonging the service life, and broadening the application range of TiO₂ for the photocatalytic denitration.