表面形貌控制增强铁基载氧体与褐煤化学链燃烧反应活性

为探究载氧体形貌控制获取适用于化学链燃烧的高活性表面结构载氧体的可行性,以Fe2O3作为模型载氧体,从理论上对比研究Fe2O3的高弥勒指数晶面(104)和Fe2O3自然裸露的最主要晶面之一(001)的表面电子特性,结果表明,Fe2O3(104)的电子结构更有利于表面与煤模型分子的相互作用.基于理论分析结果,从实验上控制制备了单晶载氧体Fe2O3(104)/Al2O3,研究了该载氧体与褐煤的化学链燃烧反应特性.Fe2O3(104)/Al2O3比传统浸渍法制备的载氧体Fe2O3/Al2O3具有更高的反应活性,与理论计算结果一致.元素分析表明,Fe2O3(104)/Al2O3与褐煤反应的积碳量远少于Fe2O3/Al2O3与褐煤反应的积碳量.对比新鲜载氧体及再生后载氧体的结构发现,Fe2O3(104)/Al2O3在反应过程中不断进行氧化还原反应而发生结构弛豫后,仍然能通过氧化再生.这表明形貌控制制备可为化学链燃烧技术开发新型高效载氧体提供新思路.

Enhancing the Activity of Iron Based Oxygen Carrier via Surface Controlled Preparation for Lignite Chemical Looping Combustion

We selected Fe2O3 as the model oxygen carrier for chemical looping combustion(CLC) to theoretically detect the electronic properties of the high index surface(104) and the referenced low index surface(001). Fe2O3(104) exhibits better electronic structure for the interaction to lignite. Then, based on the theoretical calculations, Fe2O3(104) supported on Al2O3 was obtained via surface-controlled preparation. Thereaction between lignite and the prepared Fe2O3(104)/Al2O3 is more efficient than the reaction between lignite and the reference Fe2O3/Al2O3 prepared via traditional impregnation method, which corresponds to the theoretical calculations. Ultimate analysis shows less carbon deposit on the reduced Fe2O3(104)/Al2O3 than on the reduced Fe2O3/Al2O3. Further, the fresh and the regenerated oxygen carrier were characterized, which verified the regeneration ability of Fe2O3(104) after severe structural relaxation during the reaction processes. These findings indicate that morphological control of oxygen carrier is very rewarding and will throw light to the next generation of highly efficient oxygen carriers for CLC technology.