Wei Shuang, Li Kexin, Zhong Sheng, Zhang Ruirui, Wang Guosheng, Liu Ruixia
Beijing Key Laboratory of Ionic Liquids Clean Process, CAS Key Laboratory of Green Process and Engineering, Institute of Process Engineering, Innovation Academy for Green Manufacture, CAS, Beijing 100190, P. R. China.
Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, P. R. China.
ACS Appl Mater Interfaces. 2024 Feb 14;16(6):7252-7264. doi: 10.1021/acsami.3c17478. Epub 2024 Feb 1.
Selective conversion of inert C-H bonds in alkanes into high-value-added functional groups (alcohols, ketones, carboxylic acids, etc.) plays a vital role in establishing a green and sustainable chemical industry. Catalytic selective oxidation of cyclohexane to KA oil (cyclohexanol and cyclohexanone) is a typical representative of alkane functionalization. In this work, hollow cage-like CoO (CoO-C) and particle CoO (CoO-P) were synthesized by calcining two types of Prussian blue analogues (PBAs), which were used to catalyze the selective oxidation of cyclohexane. The CoO-C predominantly exposed (311) crystal plane is easier to adsorb cyclohexane than CoO-P, which is beneficial to shorten the induction period, accelerate the reaction rate, and improve the conversion. Consequently, CoO-C displayed a 10% conversion of cyclohexane within 1 h, and the KA oil selectivity reached 90%. The CoO-P exposed (220) crystal plane has a higher molar percentage of oxygen vacancies and more active oxygen species, as well as a strong cyclohexanone adsorption capacity, which is conducive to the deep oxidation of cyclohexanone to adipic acid and other diacid products. The mechanism analysis of cyclohexane oxidation catalyzed by PBA-based CoO shows that it exemplifies the feasibility to tailor the surface of catalysts by modulating the PBAs, which ultimately influences their reaction performance for accelerating the reaction and maintaining high cyclohexane conversion and KA oil selectivity.
将烷烃中惰性的C-H键选择性转化为高附加值官能团（醇、酮、羧酸等）在建立绿色可持续化学工业中起着至关重要的作用。环己烷催化选择性氧化制KA油（环己醇和环己酮）是烷烃官能化的典型代表。在这项工作中，通过煅烧两种类型的普鲁士蓝类似物（PBAs）合成了空心笼状CoO（CoO-C）和颗粒状CoO（CoO-P），并将其用于催化环己烷的选择性氧化。与CoO-P相比，主要暴露（311）晶面的CoO-C更容易吸附环己烷，这有利于缩短诱导期、加快反应速率并提高转化率。因此，CoO-C在1小时内环己烷转化率达到10%，KA油选择性达到90%。暴露（220）晶面的CoO-P具有更高的氧空位摩尔百分比和更多的活性氧物种，以及较强的环己酮吸附能力，有利于环己酮深度氧化为己二酸等二酸产物。基于PBA的CoO催化环己烷氧化的机理分析表明，通过调节PBAs来定制催化剂表面是可行的，这最终会影响它们的反应性能，以加速反应并保持高环己烷转化率和KA油选择性。
