Zeolitic imidazolate framework-8 as an efficient and facile heterogeneous catalyst for the acceptorless alcohol dehydrogenation to carboxylates

Abstract

Zeolitic imidazolate framework-8 (ZIF-8) is a representative Zn-based metal–organic framework (MOF) featuring high porosity, good stability, and large surface area. Owing to these fascinating properties, ZIF-8 exhibits promising potential in catalysis. With our continuous interest in catalyst development of alcohol-involving green transformations, we intended to exploit the capability of ZIF-8 in catalyzing the acceptorless dehydrogenation of alcohols to carboxylates. The preparation of ZIF-8 at room temperature possesses advantages such as environmental friendliness and easy operation. Subsequently, various techniques were adopted to characterize the structures, morphology, and chemical states of both fresh and reused catalysts. Notably, the catalyst displayed good reusability since it could be reused at least 5 times without considerable loss of catalytic activity. It was also perceived that KOH was an indispensable component of this catalytic process. More specifically, KOH not only worked as one of the starting materials but also provided the basic environment to promote this catalysis. Furthermore, the aldehyde was confirmed as a key intermediate for this catalytic process. Based on additional experiments and literature reports, we proposed [Zn–N] as the active sites and presented a plausible catalytic cycle.