TiO2改性的镁基中温吸附剂及其CO2吸附性能的研究

摘要

采用沉淀法合成一系列TiO2 改性的镁基吸附剂,利用XRD、SEM和氮气吸附等方法对吸附剂进行表征,通过变温吸附-脱附动态循环实验考察其CO2 吸附性能. 随着TiO2 含量的增加,样品的结晶度逐渐下降,同时由于焙烧后生成钛酸镁,样品比表面积逐渐减小. 当TiO2 添加量为2%(质量分数),此时吸附剂呈直径为4. 0~5. 0μm的球形,局部为纳米片状结构,该吸附剂自第二次循环开始吸附能力无明显变化;经过50次变温吸附脱附循环实验后,动态吸附容量可达6. 64%(质量分数) ,这是由于TiO2 改性后生成的钛酸镁为该吸附剂提供了刚性骨架,促进了活性组分的分散,并提高了吸附剂的稳定性.%A series of TiO2-modified magnesium-based sorbents, for thermo-swing absorption process in intermediate-temperature working range ( 250 ~500 ℃) , were prepared by precipitation, and characterized by XRD, SEM and N2 absorption etc. The sorbents were evaluated by dynamic absorption-desorption cyclic tests. With the increase of TiO2 amount, the crystallinity of the sample decreased, and the BET surface area also decreased due to the formation of MgTiO3 . When the TiO2 content was 2%, uniform particle size (nanostructured spheres with 4. 0~5. 0 μm in diameter) was obtained. The absorption capacity was stabilized from the second cycle of the absorption-desorption cyclic test, and the capacity could reach 6. 64% after 50 cycles, suggesting good stability of the sorbent. This should be attributed to the formation of MgTiO3 , which provided a rigid framework for the sample and improved the dispersion of active species.