Acidic bimetallic LaCo-MOF materials showing synergistic catalytic effect on the air epoxidation of cyclooctene

Abstract

In view of the difficulty of efficient epoxidation of cyclooctene with molecular oxygen, we introduce the rare earth metal La element to synthesize an acidic bimetallic LaCo-MOF material, which has an excellent synergistic catalytic effect in the air epoxidation reaction of cyclooctene. Various characterization results prove that Co and La in the bimetallic LaCo-MOF-BTC-H material are not mixed physically, but co-exist in the MOF framework in the form of coordination with obvious interactions. Moreover, the introduction of the La element enhances the acidity of bimetallic LaCo-MOF-BTC-H material significantly. By exploring the effects of different metal ratios, different metal combinations, different crystallization temperatures and time on the material structure and reactivity, the synthesis conditions of the La2Co8-MOF-BTC-H material with the best catalytic performance are determined. Under the reaction conditions of 80 °C and 30 ml/min air flow rate, the conversion of cyclooctene could reach 96.2% after 5 h of reaction, and the selectivity of epoxy cyclooctane was as high as 98.7%. The La2Co8-MOF-BTC-H material showed good recyclable stability, and the catalytic activity did not decrease significantly after repeated-use 5 times.