Bimetallic-organic Frameworks CoMo-ZIF-67: An Efficient and Stable Catalyst for Selective Oxidation of Alkenes

摘要

Developing catalysts for the selective oxidation of alkenes with environment-friendly, unique structural characteristics, high economic benefit and better catalytic performance is important. Herein, we employed ZIF-67 as the sacrificial template to synthesize bimetallic-organic frameworks CoxMo100-x-ZIF nanocages by a facile dissolution-regrowth strategy. The Co51.8Mo48.2-ZIF catalyst was tested under various experimental parameters for the selective oxidation of cyclooctene to screen the optimal reaction conditions. Under the optimal reaction conditions, Co51.8Mo48.2-ZIF nanocages exhibited a high cyclooctene conversion of 99.3 % and a selectivity of 99.0 % to epoxy cyclooctane. Furthermore, Co51.8Mo48.2-ZIF nanocages can maintain their catalytic performance after reused five catalytic cycles. This bimetallic catalyst could also be used for the epoxidation of a wide range of alkenes, such as hexene or cyclohexene. In addition, the kinetic studies were conducted, and a reasonable reaction mechanism was proposed based on density functional theory calculations. The outstanding catalytic performance of CoxMo100-x-ZIF nanocages can be attributed to the cooperativity between Co and Mo sites and the hollow structure with high surface areas.