纳米TiO_2催化燃烧固硫的实验研究

Experimental Investigation of Nano-TiO_2 on Combustion and Desulfurization Catalysis

通过纳米TiO2催化CaO燃烧后粉煤灰的成分分析和燃烧烟气中SO2含量的测定确定固硫效果,探讨了纳米TiO2添加量、Ca/S摩尔比、不同条件制备的纳米TiO2及燃烧温度对分析纯CaO固硫的影响,比较了纳米TiO2对不同煤种以及不同钙基固硫剂的固硫效果,并对反应产物进行了X射线衍射和扫描电镜分析.结果表明,纳米TiO2与CaO共同作用时,纳米TiO2最佳的添加量为8%;在Ca/S摩尔比为2、燃烧温度为850℃时纳米TiO2催化分析纯和工业纯CaO固硫效率达87.8%和60.3%,比不添加纳米TiO2时增加13.4%和29.6%.纳米TiO2对不同煤种燃烧时CaO固硫有较好地催化作用,能够促进SO2转化成SO3的本征反应,同时增加煤灰的孔尺寸,促进二氧化硫的扩散从而提高CaO的固硫效果.

Experiment research of nanometer TiO2 catalytic combustion to CaO desulfurization was studied. Desulfurization effect was measured by the composition analysis of fly ash after combustion and the content of SO2 in flue gas. The effects of analytical grade CaO desulfurization by nanometer TiO2 addition, Ca/S molar ratio, nanometer TiO2 that was prepared at different conditions and combustion temperature were discussed. Desulfurization effects were compared with different coals and Ca-base agents by nanometer TiO2 addition. The reaction products were analyzed by X-ray diffraction analysis （XRD） and scanning electron microscopy （SEM） analysis. The combustion desulfurization mechanisms of CaO by nanometer TiO2 addition were discussed. The experiment results show that nanometer TiO2 has good catalytic effect to CaO combustion desulfurization. When nanometer TiO2 was added together with CaO, the optimal addition dosage of nanometer TiO2 is 8% , Ca/S molar ratio is 2 and the combustion temperature is 850℃. The desulfurization efficiency of analytical and industrial grade CaO catalyzed by nanometer TiO2 can achieve to 87.8% and 60.3%, and it increased 13.4% and 29.6% than that without nanometer TiO2. The pore diameter and surface area of different coal ashes with nano-TiO2 addition increase because of the active centers of nano-TiO2 surface which are helpful to the diffusion of SO2 and reaction of SO2 to SO3 and increase the desulphurization efficiency of CaO.