高表面铁基六铝酸盐氧载体甲烷化学链燃烧过程研究

Recently, the production of shale gas increases significantly, which makes it become important feedstock of energy and chemicals. Chemical looping combustion (CLC) is a novel fossil fuel combustion technology that offers the inherent feature of isolating CO2. Iron based oxygen carrier (OC) have received particular attention in CLC because of their resistance to carbon deposition and environmental benign. However, it suffers from severe aggregation and sintering during multiple redox cycles. In this proposal, high surface area Fe-substituted hexaaluminates are employed to be OC to stabilize Fe ions for CLC of CH4 due to their remarkable resistance to sintering, various Al coordination sites available for substitution and anisotropic diffusivities of oxygen. The activity and stability under multiple redox cycles of high surface Fe-substituted hexaaluminate OCs for CLC of CH4 will be investigated. In addition, 57Fe Mössbauer spectroscopy characterization techniques will be employed to investigate the micro-structure, characteristic of pores, chemical state of Fe ions and mobility of lattice oxygen in order to propose stabilization mechanism of Fe ions and establish the structure-reactivity relationship. Combined with a kinetic study, the order and activity energy of reaction between high surface Fe-substituted hexaaluminate OCs and CH4 will be determined and reaction mechanism will be proposed. This application will open up a new avenue for developing novel Fe-based OC with high reactivity and stability under multiple redox cycles for CLC of CH4.

近年来，页岩气产量大幅度增加，成为一种重要的能源和化工原料。化学链燃烧（CLC）是一种新型的化石燃料燃烧技术，可以实现CO2自动分离。铁基氧载体因具有较好的抗积碳性能、环境友好而受到了广泛关注，但面临在氧化还原过程中团聚烧结难题。本项目提出采用高表面铁基六铝酸盐为甲烷CLC氧载体，利用其高温稳定性、晶格可镶嵌性以及晶格氧移动性来抑制铁的团聚烧结，系统研究高表面铁基六铝酸盐氧载体甲烷CLC反应活性和氧化还原循环稳定性，结合57Fe穆斯堡尔谱等技术阐明其稳定Fe离子机制，揭示高表面铁基六铝酸盐氧载体的晶体结构、比表面积、孔尺寸和结构、Fe的化学状态、晶格氧的移动性与甲烷CLC反应性能的内在关联。结合动力学研究确定高表面铁基六铝酸盐甲烷CLC反应活化能、反应级数、机理模型。本项目将为开发新型高效CLC铁基氧载体提供一条新途径。

近年来，页岩气产量大幅度增加，成为一种重要的能源和化工原料。化学链燃烧（CLC）是一种新型的化石燃料燃烧技术，可以实现CO2自动分离和避免NOx污染物的产生，已成为理论上和技术上关注的焦点。铁基氧载体因具有较好的抗积碳性能、环境友好而受到了广泛关注，但面临在高温氧化还原过程中团聚烧结难题。该申请利用高表面六铝酸盐的高温稳定性、晶格可镶嵌性和晶格氧移动性，从耐高温材料研究入手，开展高表面铁基六铝酸盐、钙钛矿和石榴石型复合氧化物设计、制备以及在CLC和化学链重整（CLR）的反应性能研究，利用多种表征手段阐明活性金属稳定机制。在此基础上，针对CLC反应高活性，开展贵金属和过渡金属模型催化剂组成、结构与催化性能研究，认识活性金属催化剂的构效关系，进而为CLC反应高性能氧载体提供研制方向和理论基础。