Constructing Bimetallic ZrCo-MOF Acidic Materials for the Selective Epoxidation of Limonene

Abstract

The selective epoxy product of limonene, specifically 1, 2-limonene epoxide, serves as a crucial intermediate with diverse applications. However, achieving high conversion rates and selectivity in selective epoxidation reactions presents significant challenges. In this study, the bimetallic metal-organic framework (MOF) material was synthesized via a hydrothermal method, which was designated as Zr₂Co₈-MOF-BTC-H. The incorporation of zirconium (Zr) markedly alters both the morphology and structure of the bimetallic Zr₂Co₈-MOF-BTC-H catalytic material. Notably, there were pronounced changes in the binding energies of the bimetallic elements within the Zr₂Co₈-MOF-BTC-H framework, which suggests that cobalt (Co) and Zr coexist within the coordination structure and exhibit substantial interactions. Compared to single-metal MOF materials, the acidity of the bimetallic Zr₂Co₈-MOF-BTC-H was significantly enhanced, thereby facilitating the selective epoxidation of limonene. Under optimal reaction conditions, epoxidation conversion achieved 91.8%, while selectivity for epoxy compounds reached 88.6%. Furthermore, after five cycles of use, there was no significant decline in activity for the Zr₂Co₈-MOF-BTC-H material, indicative of its remarkable recyclable stability.