Experimental Study of Nanometer TiO2 for Use as an Adsorbent for SO2 Removal

The flue gas desulphurization (FGD) process for the majority of industrial applications worldwide is chemical absorption. A large amount of adsorbent is spent and becomes waste material. If a new type of adsorbent can be found, which utilizes physical adsorption (and hence can be regenerated) instead of chemical absorption, then FGD processes will be greatly improved. Significant technical progress and economic benefits would be obtained. A new kind of adsorbent, namely nanometer sized TiO2 particles, which is processed and sintered at low temperature and having high porosity and surface area is investigated in this paper. Using different sintering temperatures, four TiO2 adsorbents are prepared. The pore structure of TiO2 particles is characterized by a scanning electron microscope (SEM), the BET method, and calculated pore size distribution by the BJH model. The crystal types of all four samples are found to possess anatase structures by XRD. The tests of adsorption dynamics for FGD and the performance of SO2 removal are investigated in a fixed-bed system for different samples. Different operating conditions such as adsorption temperature, SO2 concentration in flue gas, and the superficial velocity of flue gas were investigated. The experimental adsorption breakthrough curves for these types of adsorbents in a fixed-bed show good SO2 removal performance which is strongly influenced by adsorption temperature, SO2 concentration in the flue gas, and superficial velocity of the flue gas. The mechanism for SO2 removal is demonstrated by infrared (IR) spectroscopy to be mainly physical adsorption. The pore texture of TiO2 particles to be used as a physical adsorbent is very important for its adsorption capacity. The SO2 removal process using TiO2 as a physical adsorbent is reversible, and the TiO2 adsorbent can then be regenerated by raising the temperature.