合成气制低碳醇纳米Cu-Co双金属催化剂研究

The critical challenge for the catalyst for higher alcohols synthesis is improving the selectivity to higher alcohols in which one alcohol molecule has two or more then two carbon atoms. Over bimetallic Cu-Co nano catalyst, higher alcohols are generated by copper and cobalt synergistic catalyzing, so it is required that copper and cobalt are in the alloy state or nano particles with copper and cobalt being closely linked. We proposed a new scheme for designing Cu-Co bimetallic catalyst: to load a perovskite-type oxide (PTO) of LaCo1-xCuxO3 on a support such as ZrO2 or SiO2, and then to reduce it, thus supported nano particles of Cu-Co alloy or nano particles with core-shell structure can be made. This is owing to that in LaCo1-xCuxO3 copper and cobalt ions are uniformly mixed at atomic level and that copper and cobalt ions are confined in a nano particle. Additives of the catalyst can also be added as substitution ions of the crystalline lattice in the PTO, which favors the interaction between the additives with the active components. Based on this scheme, we have prepared bimetallic Cu-Co nano catalyst, and the catalyst showed much high selectivity to higher alcohols and very good activity, suggesting that it is a much promising catalyst for industrial application. In this project, we will investigate the stability of the catalyst, to study the variation of the structure and the catalytic performance of the catalyst with reaction time, to study the relationship of the structure and the catalytic performance of the catalyst, and to study the effects of additives and support, in order to obtain basic data as preparatory work for undertaking scale-up test, and to further improving the catalyst. The scheme proposed in this proposal can be applied to many other bimetallic/multi-metallic nano particles, for that most of the metal ions can be acted as the crystalline lattice ions of a PTO, so the study of this project is of great significance in the aspect of academic viewpoint.

合成气制低碳醇催化剂的关键是提高C2+醇的选择性。铜钴双金属催化剂中，铜和钴协同催化生成低碳醇，所以要求铜钴形成合金或密切接触。本项目提出了Cu-Co催化剂设计的新构想：将纳米LaCo1-xCuxO3（钙钛矿型复合氧化物-PTO）晶粒负载于ZrO2、SiO2等载体上，然后还原可得负载型Cu-Co纳米合金或纳米核壳结构等。因为：LaCo1-xCuxO3中，铜和钴离子处于原子水平的均匀混合，且二者被限域于纳米晶粒内。助剂也可以作为PTO的取代离子加入，以利于助剂与活性组分相互作用。申请人按本构想制得的催化剂具有很高的C2+醇选择性及较好的活性，很有应用前景。本项目将在此基础上重点研究催化剂的稳定性，研究催化剂结构和性能随反应时间的演化、构效关系、助剂和载体的作用等，为中试试验提供基础和进一步优化催化剂。学术价值：本方案可拓展于其它纳米双金属的制备，因为大部分金属离子可以是PTO的晶格离子。

本项目提出了一种“纳米团簇”催化剂的设计与构筑方法，利用钙钛矿型复合氧化物（PTOs）为前驱体通过还原得到的金属纳米颗粒、未被还原的金属氧化物等构筑纳米颗粒团聚体，我们称之为“纳米团簇”，并用于催化合成气制低碳醇等反应。. PTOs按组成表示为ABO3，A为碱土金属或镧系离子，B为过渡金属离子，作为催化剂、材料等有大量的研究。在本项目中我们主要利用其如下特点：（a）ABO3中A、B位离子可以调变，也可以被其它离子部分取代，从而可以固定诸多金属离子于该晶格中，如：A1-xA'xB1-yB'yO3；（b）ABO3中的所有金属离子以原子水平均匀混合并被限定于钙钛矿的晶格中；（c）通过一定的方式可以将该钙钛矿晶粒担载于大比表面积载体表面，比如ZrO2、SiO2，于是将均匀混合的金属离子限域于PTOs晶格内，并分散于载体表面。所以，还原得到的单金属或双金属以及其中未被还原的氧化物将团聚为“纳米团簇”。. 通过该方法我们合成了一系列的Cu-Co基、Rh基、Ni基催化剂，并考察了助剂、载体等对催化剂性能的影响。研究了“纳米团簇”的结构、各组分纳米颗粒之间的相互作用、对合成气制低碳醇等反应的性能以及构效关系等。关于催化剂的稳定性，主要研究了“纳米团簇”中纳米Cu-Co双金属的结构和化学状态随反应时间的演化，及其与催化性能的关系。此外，以本项目提出的催化剂设计思路初步探索了用于合成气制低碳醇的Co-Ga基催化剂，发现其具有良好的催化性能。. 我们也以类水滑石为前驱体制备了一系列的Cu-Co和Cu-Fe基催化剂用于合成气制低碳醇，研究了类水滑石在纳米碳管、碳纤维上的原位生长。以碳材料为载体旨在利用碳材料的高导热性减缓热点生成。