Fe2O3/ATP载氧体制备及煤化学链燃烧性能研究

以天然凹凸棒(ATP)为载体,分别利用机械混合法、浸渍法和溶胶-凝胶法制备了3种铁基复合载氧体。利用X射线衍射(XRD)、能谱(EDS)、N₂-吸附脱附等温线等对其进行物化表征,并在900 ℃流化床中考察其煤化学链燃烧反应性能。结果表明,ATP能显著增加载氧体比表面积和抗磨损能力,并对煤转化过程有催化作用,其与Fe₂O₃的协同作用使初始碳转化速率显著提高。溶胶-凝胶法制备的U-Fe4ATP6表面Ca元素含量为4.3%,比表面积为4.920 7 m²/g,均高于其他两种载氧体,表现出更高的催化性能和反应活性:初始碳转化速率为0.168 min^-1,平均CO₂浓度为98.6%,燃烧效率为98.7%。20次反应后,U-Fe4ATP6催化性能略有降低,对应的初始碳转化速率降至0.108 min^-1,停留时间t₉₅延长到18 min;且能维持较高的反应活性,对应的CO₂捕集效率和燃烧效率分别稳定在98.6%和96.7%。

Preparation and performance of the Fe2O3/ATP oxygen carriers in coal chemical looping combustion

Through mechanical-mixing, impregnating and sol-gel methods, Fe₂O₃-based oxygen carriers (OC) were prepared with natural attapulgite (ATP) as an inert support and characterized by X-ray diffraction (XRD), energy dispersive spectrometer (EDS), and nitrogen adsorption-desorption measurements. The reactivity of Fe₂O₃-based oxygen carriers (Fe₂O₃/ATP OCs) in coal chemical looping combustion (CLC) was investigated in a fluidized-bed reactor at 900 ℃ by using steam as the gasification agent. The results indicated that the surface area and attrition resistance of Fe₂O₃/ATP OCs are improved significantly by using ATP as the support. Owing the synergy between ATP and Fe₂O₃, both are catalytic active, carbon conversion is enhanced significantly. ATP is an appropriate support for Fe₂O₃ oxygen carriers, whereas the sol-gel method gives the carriers best performance. U-Fe4ATP6 prepared by the sol-gel method, with a surface area of 4.920 7 m²/g and Ca content of 4.3%, exhibits much better performance than other two oxygen carriers. When used in CLC, the initial carbon conversion rate reaches 0.168 min^-1, with an average CO₂ concentration of 98.6% and a combustion efficiency of 98.7%. The catalytic activity of U-Fe4ATP6 is slightly decreased after twenty cycles; the initial carbon conversion rate is decreased to 0.108 min^-1 and the residence time (t₉₅) is extended to 18 min, whereas the CO₂ capture efficiency and combustion efficiency remain at about 98.6% and 96.7%, respectively.