Oefner Niklas, Shuck Christopher E, Schumacher Leon, Heck Franziska, Hofmann Kathrin, Schmidpeter Jana, Li Weiqun, Bahri Mounib, Mehdi B Layla, Drochner Alfons, Albert Barbara, Hess Christian, Gogotsi Yury, Etzold Bastian J M
Technical University of Darmstadt, Department of Chemistry, Ernst-Berl-Institut für Technische und Makromolekulare Chemie, 64287 Darmstadt, Germany.
A.J. Drexel Nanomaterials Institute and Department of Materials Science and Engineering, Drexel University, Philadelphia, Pennsylvania 19104, United States.
ACS Appl Mater Interfaces. 2023 Apr 5;15(13):16714-16722. doi: 10.1021/acsami.2c22720. Epub 2023 Mar 24.
Selective oxidation reactions are an important class of the current chemical industry and will be highly important for future sustainable chemical production. Especially, the selective oxidation of primary alcohols is expected to be of high future interest, as alcohols can be obtained on technical scales from biomass fermentation. The oxidation of primary alcohols produces aldehydes, which are important intermediates. While selective methanol oxidation is industrially established, the commercial catalyst suffers from deactivation. Ethanol selective oxidation is not commercialized but would give access to sustainable acetaldehyde production when using renewable ethanol. In this work, it is shown that employing 2D MXenes as building blocks allows one to design a nanostructured oxide catalyst composed of mixed valence vanadium oxides, which outperforms on both reactions known materials by nearly an order of magnitude in activity, while showing high selectivity and stability. The study shows that the synthesis route employing 2D materials is key to obtain these attractive catalysts. VCT MXene structured as an aerogel precursor needs to be employed and mildly oxidized in an alcohol and oxygen atmosphere to result in the aspired nanostructured catalyst composed of mixed valence VO, VO, and VO. Very likely, the bulk stable reduced valence state of the material together coupled with the nanorod arrangement allows for unprecedented oxygen mobility as well as active sites and results in an ultra-active catalyst.
选择性氧化反应是当前化学工业中的一类重要反应，对于未来可持续化的化工生产也将至关重要。尤其是，伯醇的选择性氧化有望在未来备受关注，因为醇类可通过生物质发酵实现工业化规模生产。伯醇氧化生成醛类，醛是重要的中间体。虽然选择性甲醇氧化在工业上已得到应用，但商业催化剂存在失活问题。乙醇选择性氧化尚未实现商业化，不过使用可再生乙醇时，它将有助于实现可持续的乙醛生产。在这项工作中，研究表明，以二维MXenes为构建单元能够设计出一种由混合价态钒氧化物组成的纳米结构氧化物催化剂，该催化剂在这两种反应中的活性比已知材料高出近一个数量级，同时具有高选择性和稳定性。研究表明，采用二维材料的合成路线是获得这些有吸引力的催化剂的关键。需要使用结构为气凝胶前驱体的VCT MXene，并在醇和氧气气氛中进行温和氧化，以得到由混合价态VO、VO和VO组成的理想纳米结构催化剂。很可能，材料稳定的 bulk 还原价态与纳米棒排列共同作用，实现了前所未有的氧迁移率以及活性位点，从而产生了一种超活性催化剂。
