化学链蒸汽重整制氢用高效稀土基氧载体的构筑及其储氧-催化耦合

Hydrogen is an important clean fuel and ideal energy carrier. Chemical-looping steam reforming offers an effective approach for producing pure hydrogen. There is a problem that the oxygen carrier in this technology own limited oxygen storage-release capacity restricting the reactivity. However, it is known that rare earth-based oxygen carrier possess better oxygen storage-release capacity. In this case, we proposed to combine the rare earth-based oxygen carrier and catalyst, obtaining a dual-function material with catalytic and carrying oxygen. Using this material as oxygen carrier could prove the oxygen transportation and hydrogen yield. Based on the preparation of rare earth-based oxygen carrier, this project mainly focuses on the control of size, microstructure, microenvironment and the interfacial reaction of the oxygen carrier. The structural and physicochemical of different oxygen carrier will be characterized in detail, and the results can be related to the catalytic performance in the catalytic process. The law of distribution, transportation of oxygen species will be mainly discussed. The matching relationship of catalytic active center on quantity and dispersion, interfacial reaction and the oxygen storage-release capacity will be also researched. The purpose is to reveal the coordination mechanisms of Chemical-looping steam reforming. It is reasonable to believe that the implementation of this project is significant for the Chemical-looping steam reforming and will also improve the utilization of the Rare earth resources.

氢气是一种重要的清洁能源和理想的能源载体。化学链蒸汽重整技术是一种新型的制氢工艺。项目针对该制氢工艺用氧载体中晶格氧迁移与制氢能力的“瓶颈”问题，提出将储放氧能力优异的稀土基氧化物耦合于氧载体中，构筑出兼具储氧-催化的双功能氧载体材料，改善氧传输性能，提高产氢能力。项目拟以稀土基氧载体的制备为先导，围绕该纳米材料的尺度效应、微结构、微环境、界面协同作用机制对反应性能的影响规律等关键科学问题开展研究。通过氧载体材料的表征与性能分析间的反馈，探讨材料表面氧物种的分布以及迁移规律，研究材料的载氧活性中心和催化活性中心在数量、分散度、界面作用等方面的匹配关系以及材料的储放氧特性与催化功能的动态耦合特性，最终揭示出化学链蒸汽重整制氢技术的反应机理。项目的实施不仅对化学链蒸汽重整制氢技术具有很强的借鉴意义，还对稀土资源的高效利用有重要意义。

化学链蒸汽重整工艺是一种能够同时生产合成气和氢气的新技术。设计与构筑兼具载氧-催化的双功能氧载体是实现该技术的关键所在。稀土基氧化物具有优良的储放氧性能，其中镧基钙钛矿氧化物由于其独特的结构特性、优异的热稳定性及储放氧性能可以作为化学链蒸汽重整技术用氧载体。本项目运用各类表征手段系统研究了La-Mn-Cu-O及La-Mn-Fe-O等体系的物理化学性质（如微结构、界面协同作用、储氧能力和还原能力等）和反应性能。主要研究成果有：（1）在化学链蒸汽重整过程中LaMnO3氧载体具有较好的抗积碳性能，但是由于其储放氧性能较差导致H2产量较低。Cu离子的掺杂不仅提高了LaMnO3氧载体的储放氧能力，同时也提高了其反应活性。（2）La-Mn-Fe-O系列氧载体在化学链蒸汽重整过程中表现出较高的反应活性，其中La0.85MnFe0.15O3样品显示出最高的H2产量。经过20次氧化还原循环反应后，该氧载体表面均未检测到积碳产生，证明其优异的抗积碳性能、结构稳定性和热稳定性。（3）焙烧温度对La-Mn-Fe-O氧载体的结构特性具有非常重要的影响。该系列氧载体在800℃下焙烧后具有更高的氧空位浓度，优异的储放氧性能，结构稳定性及最佳的反应活性。项目的实施为化学链蒸汽重整制氢用高效稀土基氧载体的构筑及筛选提供了一定的理论和实践支撑。