协同催化双活性位构筑及其用于合成气直接制乙醇的研究

Syngas of CO+H2 can be synergistically catalyzed to generate ethanol over bi-active centers, where the two kinds of the active centers are required to be in close contact and be in certain structure and/or state. Therefore, designing on the catalyst is a challenge. Recently, a new kind of catalyst has been found by our group, which showed very good catalytic performance and is promising for practical application, while the mechanism is unknown. The catalyst is composed of a metal which can adsorb CO dissociatively, a complex metal oxide which can form oxygen vacancies and some additives. The three kinds of components aggregate together to form aggregations in nano size, and the aggregations are dispersed on the surface of a support, such as M-LaFeO3-La2O3（M：Co、Rh）dispersed on SiO2, Co-La4Ga2O9-La2O3 dispersed on ZrO2, and so on. Our tentative studies suggest that possibly this is new kind of bi-active centers, and we have mastered the preparation technique for this kind of catalyst. In this project, the mechanism of ethanol generation from syngas and the relationship between the structure/chemical state of the bi-active centers with catalytic performance would be studied in detail and with depth. On the construction of the “aggregations”, the structure/chemical state of the bi-active centers would be tailored by adjusting the kind and content of the three components of the metal, the complex metal oxide and the additives, by adjusting the dispersion state of the metal under nanoparticle and cluster of metal atoms, and by adjusting the interaction between the components, to reveal the characters of the excellent catalysts by correlating the structure/chemical state with the catalytic performance.

合成气（CO+H2）定向合成乙醇需要由双活性位协同催化，要求双活性位紧密接触并处于特定结构或状态等，催化剂设计难度很大。申请人近期发现了一种新型催化剂具有很好的性能，有实际应用前景，但其中的原理未知。这种催化剂由可解离吸附CO的金属、可形成氧空位的复合氧化物和助剂，三者构成纳米尺寸的团聚体，该团聚体分散于载体表面。比如分散于SiO2表面的M-LaFeO3-La2O3（M：Co、Rh），分散于ZrO2表面的Co-La4Ga2O9-La2O3等。初步研究迹象显示，这很可能是一种新的双活性位组合方式。我们拥有这类催化剂的制备技术，本项目拟研究这类催化剂上生成乙醇的机理、构效关系；在所述的“团聚体”的构筑方面，通过调变金属、复合氧化物以及助剂种类，调变金属的分散状态（纳米颗粒、原子团簇等），调变组分之间的相互作用，实现对双活性位的结构和状态/性质的调控；并将其与性能关联，揭示优良催化剂的特征。

合成气（CO+H2）直接制乙醇（DES）需要由双活性位协同催化，要求双活性位紧密接触，催化剂设计与制备的难度很大。针对这个问题，本项目利用钙钛矿型复合氧化物（PTOs）可以限域和均匀分散诸多金属离子的性质，提出了几个新的解决思路：构筑负载型金属（Co或Rh）-氧空位组成的双活性位催化剂，其中的氧空位由钙钛矿型复合氧化物LaFeO3或复合氧化物La4Ga2O9表面上形成；将两种金属离子分散于PTOs晶格中，再经还原构筑双金属催化剂，包括Co-Ni、Co-Rh等；利用CaTiO3等PTOs与钴的相互作用，调控获得Co/Coδ+双活性位组合。研究了这些催化剂的制备化学、对DES的性能以及构效关系。基于所提出的DES催化剂设计思想，拓展应用于CO2甲烷化、CO2加氢制乙醇和CO氧化等催化剂的设计与制备，取得了良好的效果，并研究了对应的催化性能和构效关系。项目的核心贡献在于提出了如何利用复合氧化物为前驱体，构筑双活性位等复杂构成的催化剂。在国际主流期刊，发表了标注本基金资助的研究论文25篇(一区11篇，2区9篇，3区3篇，4区2篇)，申请了发明专利7项，其中2项已获授权。