生物油蒸汽重整制氢催化剂限域效应的调控及其机理研究

Hydrogen production from catalytic steam reforming of bio-oil is not only improved the utilization efficiency of biomass, but also conducive to sustainable development. There are some key scientific problems hamper the development of steam reforming bio-oil, which include the migration, agglomeration and sinter of active metal atoms or particles in catalyst and the coking caused by the structural features and high temperature sensitive property of bio-oil. In order to overcome these problems, we propose a method by constructing a catalyst with confinement effect that can be suitable for hydrogen production via steam reforming of bio-oil. By using the in-situ XRD and in-situ FTIR and combining with N2/Ar adsorption-desorption, HRTEM, XPS, NH3/CO2-TPD, H2-TPR, TPO/TPH/TPD-MS and GC/MS characterization techniques, to explore the excitation, migration and catalytic conversion processes of bio-oil molecule and intermediate species in confined space, to reveal the influence mechanism of confinement effect of catalyst on bio-oil steam reforming for hydrogen production, and to study the effect mechanism of porous structure, acid-base sites, oxygen vacancy and metal-support interaction of catalysts on bio-oil steam reforming for hydrogen production, to illuminate the effect of the cooperation mechanism of catalyst sinter and coke on the regularity of bio-oil steam reforming for hydrogen production and build up heat and mass transfer reaction kinetics model. In addition, we also carry out experiment research to master the influence law of confinement effect of catalyst on bio-oil steam reforming for hydrogen production. This project lays a theoretical foundation for hydrogen production from steam reforming of bio-oil.

生物油催化重整制氢可以提高生物质能利用效率，有利于实现可持续发展。本项目针对生物油重整制氢过程中催化剂活性金属原子或颗粒易发生迁移、团聚和烧结以及由于生物油结构特点、高热敏性质引起的结焦等关键科学问题，提出构建具有限域效应、适合生物油重整制氢催化剂；通过原位XRD、原位红外表征技术，并结合N2/Ar吸附脱附、HRTEM、XPS、NH3/CO2-TPD、H2-TPR、TPO/TPH/TPD-MS、GC/MS等分析，探索生物油分子、中间物种在限域空间内的活化、迁移、催化转化过程，揭示催化剂限域效应的调控对生物油重整制氢的影响机理，研究催化剂孔道结构、酸碱位点、氧空位和金属-载体相互作用对生物油重整制氢的影响机制；阐明催化剂烧结和积炭协同机制对生物油制氢规律的影响，构建传热、传质-反应动力学模型；进行生物油重整制氢实验研究，掌握催化剂限域效应对生物油制氢的影响规律，为生物油重整制氢奠定理论基础。

针对生物油重整制氢中催化剂的烧结和结焦关键科学问题，对海泡石（SEP）和凹凸棒石（ATP）结构进行调控、重塑，负载Co、Ni等活性组分，制备出高性能催化剂：Co-0.3Ce/SEP-C0.4、含有Co-Al尖晶石15Co/SEP、页硅酸盐型Co/SEP-NaOH、纳米花型10Co/SEP-PS、Ni-10La/SEP、Ni-TiS/ATP等。采用多种现代仪器分析技术对催化剂进行结构分析，发现SEP和ATP的优良水热稳定性、丰富微纳米多孔性以及灵活的结构可塑性，可以增加催化剂的物理限域效应。催化剂中形成的特定表界面位点（Co-Ce、Niδ--OV-Ti3+等界面位点）和特定结构（Co-Al尖晶石、Co-页硅酸盐、纳米花型等结构）增强了金属与载体/助剂间电子相互作用（即化学限域效应）。. 其中，含有富Co缺陷Co1-xAl2O4-x尖晶石的15Co/SEP实现了最高的生物油转化率（95.7%）和氢气产率（68.8%）；页硅酸盐型Co/SEP-NaOH催化剂具有高比表面积（270m2/g）、强金属-载体相互作用和强碱性位点，在甘油蒸汽重整制氢反应中实现了95%的甘油转化率和70%的H2产率；纳米花状10Co/SEP-PS催化剂具有高度分散的Co纳米颗粒和独特的Co页硅酸盐型L酸位点，有效提升了生物油C-C和C-H键断键效率和重整活性，在苯酚-乙醇蒸汽重整反应中具有最低表观活化能（35.5 kJ/mol）和较高的H2转化频率（TOF=0.67 s-1）；含有丰富Niδ--OV-Ti3+界面位点的Ni-TiS/ATP催化剂，在乙酸蒸汽重整制氢实验，表现出了93.4%的碳转化率和77.6%的氢产率。研究中还发现催化剂的特定缺陷位点和介孔-微孔复合孔道效应对催化剂的重整性能明显提高，可能是由于缺陷位点有效促进了分子断键；复合多孔内特定弯曲空间的限域效应促进生物油分子快速活化和催化活性位点利用效率。. 同时，对反应后的催化剂进行系列表征分析，发现上述催化剂都具有优异抗烧结和结焦性能，在稳定测试中活性基本保持不变。通过上述研究，构建了反应动力学，初步掌握催化剂限域效应对生物油制氢的影响规律。项目的实施，为进一步深化研究生物油重整制氢提供了基础数据和技术基础。