Study On Photo-catalysis Treatment Of NO_x In Flue Gases

Nitrogen oxides(NO_x) derived from coal combustion are the major air pollutants and have caused various environmental problems. With the help of the sub-project, "mechanism of creating NO_x and reduction of NO_x emission during coal combustion", of National "973" Key Basic Research Project, NO_x which were the oxidation products stemmed from the mold compound pyridine of azo-cycle compound in coal structure, over MCs/TiO₂/MCM-41 photocatalysts of nanoparticle mesoporous assembly system, especially mesoporous loaded nanometer photocatalyst with rare earth metal CeO₂, which is rich in our country, acting as modifier of nano-TiO₂, were photocatalyzed in a fluidized-bed photoreactor. The mechanism of the photocatalytic oxidation, factors which may affect the reaction efficiency, the ways by which to enhance the reaction efficiency and the reaction kinetics were discussed, all these discussions benefit the application and exploration research of this method.In the thesis, the mesoporous molecular sieve MCM-41 used in photocatalyzing NO_x treatment, which has hexagonally packed cylindrical mesopores, was prepared with water glass as silica source by crystallization method at ambient temperature. The results from XRD, N₂ adsorption-isotherm, FT-IR and TG-DSC indicated that prepared samples had the advantages of regular framework structure, higher specific surface area, narrowly distribution in average pore diameter, and good heat stability.The new photocatalysts-MCs/TiO₂/MCM-41, which is a nanoparticle mesoporous assembly system, were prepared by sol-gel method and dipping process, with stannic oxide(SnO2), zinc oxide (ZnO), cadmium sulfide (CdS), and rare earth oxide CeO₂ as dopants, mesoporous molecule sieve MCM-41 as carrier, and TiO₂ as the primary photocatalyst. By the results of XRD, FT-IR, N₂ adsorption-desorption, it was shown that the ordered structure of synthesized materials can still be well maintained. The results of FT-IR, SEM, UV-Vis DRS, etc. indicated that TiO₂ and MCs had been successfully assembled in the mesoporous channels of carrier MCM-41, and it was found that decrease in particles size with resultant quantum size effect will cause.For the purpose of NO_x photocatalysis oxidation, the gaseous products which were used as the analog NO_x flue gases emerged from simulated compound pyridine, were firstly...