Preparation for Renewable Sorbents of Titanium Dioxide and Study on Characteristics of Flue Gas Desulfurization

Many desulfurization techniques were developed to control the SO2 emissions by removing sulfur from the fuels before or during combustion, or by purification of the flue gas after combustion. The developed technologies for the emission control of SO2 from the flue gas can be categorized into either dry and wet, or recovery and throwaway processes. Physical adsorption processes, typically operated at low temperature, offer another promising way for emission control of SO2 from the flue gas. The key to the success of an adsorption process for SO2 concentration is the search or development of an appropriate sorbent which possesses the desired properties for selective adsorption of SO2. According to this idea, a new type material of TiO2, was developed, which can remove SO2 from the flue gas, and the mechanism for removal of SO2 from flue gas is mainly physical adsorption. Physical adsorption is a reversible process in which the adsorbent can be regenerated by lowering the pressure or raising the temperature. A sol-gel granulation process was developed to prepare porous nanostructured titanium dioxide granules using pigment grade materials of TiO2. The process, which starts with isopropyl alcohol sol of gelatinous titanic acid dinbutyl phthalate, involves droplet formation, gelation in paraffin oil, conditioning in nitric acid solution, and drying and calcination in air under controlled conditions. Under different controlling conditions, four sorbents of TiO2 were prepared. They are 1~3mm of diameter, spherical particles with large surface area and high crush strength and attrition resistance. Experimental SO2 breakthrough curves from a fixed-bed respectively with each of the four sorbents are presented to examine the performance of these sorbents for SO2 removal in the fixed-bed process. The surface area, pore size distribution, average pore size and pore volume of the best property sorbent among the four physical adsorbents are 180 m2/g, 20~100Å, 45 Å, 0.35 cm3/g respectively. Regeneration of sulfated sorbents was studied, which was firstly washed in some certain concentration of sulfur acid, then dried in ambient temperature and sintered at 350°C. The adsorption tests of sorbents for flue gas show that they still have 95% adsorption capacity and breakthrough time after five times regeneration.