Study On The Preparation Of Titanium Oxide-based Hollow Microspheres And Its Photocatalytic Removal Of Flue Gas Mercury

The energy production is given priority to coal in our country.Coal combustion can emit pollutants such as mercury, which will cause harm to the environment and the human health. Therefore, it is crucial for the reduction and removal of mercury. Among many ways to reduce emissions of mercury, photocatalytic oxidation process is a relatively new method, it has the chemical properties of stability, no secondary pollution, etc. The preparation of photocatalyst in the photocatalytic reaction is an important process.This paper mainly studied the preparation and the mechanism of photocatalytic oxidation removal of Hg0 of titanium-based hollow microspheres. The preparation ways of hollow microspheres was reviewed. Present situation of hollow spheres in photocatalytic was reviewed. Then, prepared Ti O2 hollow microspheres by hydrothermal method and doped with Fe3+. The preparedphotocatalyst was used to photocatalytic oxidation removal mercury by using the photocatalytic reactor. The experimental mainly discussed the effect of the different of precursors mole ratio, the reaction temperature, UV light intensity. And a photocatalytic oxidation reaction kinetics model of photocatalytic oxidation removal of Hg0 was set up, the photocatalytic mechanism of Ti O2 was analyzed.According to the study in this paper, some conclusion can be obtained:(1)Ti O2 hollow spheres were synthesized by hydrothermal method and doped with Fe3+. The prepared samples were well characterized by XRD, SEM, EDX, UV-vis and BET. The results showed that: the photocatalyst prepared as hollow microspheres. The average diameter of Ti O2 hollow spheres was about 500nm-800 nm. Fe was successfully doped into the Ti O2. Anatase phase Ti O2 hollow sphere was obtained. Fe-doped catalyst average pore size is nearly doubled smaller than that without Fe3+, pore volume and the grain size are smaller than without Fe3+.(2) Ti O2 hollow spheres were synthesized by hydrothermal method. When the mole ratio was 2, it has the best removal efficiency, which higher than P25.When changing the temperature, the photocatalytic oxidation efficiency increased first and decreased with the increasing of reaction temperature.Changing the UV intensity, when the UV intensity was 303.45μW?cm-2, Hg0 removal efficiency η was 76.94%.(3) Ti O2 hollow spheres were synthesized by different mole ratio dopedwith Fe3+.The maximum efficiency was reached to 100% when the Fe/Ti molar ratio was 0.05. The photocatalytic oxidation efficiency was decreased with the increasing of reaction temperature. High temperature can inhibit the photocatalytic reaction. When UV irradiation intensity was 224μW?cm-2 and Fe/Ti was 0.2, the Hg0 removal efficiency η was the highest.(4) Photocatalytic mechanism of Fe-doped Ti O2 was analyzed. Fe-doped can improve the photocatalytic of Ti O2. But the excessive Fe3+ became the trapping position of photo-generated electrons and holes. It can make the photocatalytic of Ti O2 reduced. And led to the Hg0 removal efficiency η decreased. The reaction rate equation is 0Hg Hg 0Hg K Hg(t)r =k1+K Hg(t)?,8-1-2k?=2.11?10 mol ?min ?cm, Langmuir adsorption equilibrium constant is Hg3-1K =0.0036 cm ?mol.