CO2吸附与迁移强化的碳化钼重整催化剂设计及其二甲醚制氢其性能研究

Dimethyl ether (DME) with high C/H ratio, saftey storage and transportation shows great potential to generate high-purity hydrogen for fuel cell. Based on similarity of catalytic activity between molybdenum carbide and noble metals, a new way of hydrogen production by sorption- and transgfer-enhanced steam reforming of DME on core-shell catalysts of Mo2C /(CNT, Al2O3)@La2O3 is presented and investigated. The surface structure, redox properties, surface acidity/basicity and chemiadsorption ability of the multi-functional catalysts synthesized by the co-precipitation or hydrothermal methods are studied by the modern characterization techniques. The activities and lifetime of the catalysts are also explored. The crystal lattice stability of molybdenum carbide is adjusted by controlling its morphology. The microstructure and surface propertie of the multi-functional catalysts related to its catalytic activity are characterized to reveal their similarities of chemical properties between carbides and noble metals, which can provide a theoretical basis to develope transition-metal carbides as new catalytic materials to replace noble metals. Additionally the dynamic and quantitative analysis methods of lattice carbon transfer are used to provide a basis for designing and developing a new highly-efficient carbide catalysts. By way of the experiment and in-situ characterization of the catalysts, the mechanism of hydrogen production from DME on the multi-functional catalysts is explored and a chemical reaction kinetic model will be established. This work is helpful to provide new methods for the preparation of molybdenum carbide catalysts and to speed up the development of vechile-carried hydrogen production.

二甲醚由于其来源多样化、含氢量高、易于储存和运输等优点，作为燃料电池车载制氢的原料而极具潜力。本课题利用过渡金属碳化物具有类似贵金属的催化性质，提出利用核-壳型设计并组装一种Mo2C/(CNT, Al2O3)@La2O3多功能复合催化剂，实现吸附与迁移强化的二甲醚水蒸气重整高效、稳定制氢工艺。利用现代表征技术，研究催化剂的表面结构与氧化还原性质、酸碱性质、化学吸附性能之间的变化规律；考察催化剂的吸附和迁移强化与催化重整耦合的二甲醚制氢的反应性能及其寿命，研究催化剂特性与催化性能之间的变化规律；通过碳化钼形貌控制调控晶格稳定性，揭示碳化物具有贵金属化学性质的微观本质，为碳化物作为新型催化材料替代贵金属提供理论依据；采用原位表征技术，研究多功能催化剂催化重整二甲醚制氢的反应机理，分析反应物分子在催化剂表面的反应途径。此研究有助于为新型催化剂的制备提供方法，加快车载制氢的产业化应用进程

二甲醚由于其来源多样化、含氢量高、易于储存和运输等优点，作为燃料电池车载制氢的原料而极具潜力。本项目以具有类贵金属特性的碳化钼为核心，构筑了一系列拥有高活性、稳定性的二甲醚水蒸气重整制氢双功能催化剂。在确定了反应系统中水衍生的活性氧物种为碳化钼氧化失活的主要原因后，通过贵金属铂和过渡金属氧化物二氧化铈分别对催化剂进行了改性。利用原位红外表征技术，证实了加速活性氧物种与重整中间产物反应和改变活性氧物种生成位置都能有效避免碳化钼被氧化，提高催化剂稳定性。其中Pt-Mo2C/Al2O3催化剂能在350℃条件下，达到二甲醚转化率100%，氢气生成速率1605μmol•min-1•gcat-1，优于常见铜锌催化剂。此外，通过调控碳源，实现了活性比β-Mo2C更优的棒状α-MoC1-x形貌控制合成。利用甲烷二氧化碳重整反应，研究发现La2O3能促进碳化钼催化剂氧化-碳化循环，提高催化剂活性和抗积碳能力。相关研究结果有助于二甲醚制氢催化剂的研发，具有一定实用价值，将为加快车载制氢的产业化应用进程提供帮助。