TiO2改性的镁基中温吸附剂及其CO2吸附性能的研究

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。

TiO2 modified magnesium-based adsorbents for intermediate-temperature CO2 capture

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 4.0~5.0μm 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.