posted on 2024-02-01, 16:05authored byShuang Wei, Kexin Li, Sheng Zhong, Ruirui Zhang, Guosheng Wang, Ruixia Liu
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 Co3O4 (Co3O4-C) and particle
Co3O4 (Co3O4-P) were synthesized
by calcining two types of Prussian blue analogues (PBAs), which were
used to catalyze the selective oxidation of cyclohexane. The Co3O4-C predominantly exposed (311) crystal plane
is easier to adsorb cyclohexane than Co3O4-P,
which is beneficial to shorten the induction period, accelerate the
reaction rate, and improve the conversion. Consequently, Co3O4-C displayed a 10% conversion of cyclohexane within
1 h, and the KA oil selectivity reached 90%. The Co3O4-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
Co3O4 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.