Hierarchical Co@C-N synthesized by the confined pyrolysis of ionic liquid@metal–organic frameworks for the aerobic oxidation of alcohols

Abstract

Rationally designing low-cost heterogeneous catalysts for the selective oxidation of alcohols to aldehydes is highly required in numerous industrial fields. Herein, non-precious metal-based catalysts Co, N-doped carbon (denoted as Co@C-N) with highly dispersed active sites and hierarchical pores were synthesized by the pyrolysis of an ionic liquid@metal–organic framework (IL@MOF) as precursors. The hierarchical structure of Co@C-N could be tuned by easily changing the pyrolysis temperature and the mole fraction of [Bmim][CoCl₃]. Moreover, Co@C-N could efficiently catalyze the oxidation of alcohols to aldehydes. As a result, the optimized Co@C-N(0.1)-900 exhibited excellent catalytic activity for the oxidation of alcohols to aldehydes, affording 99% yield of aldehydes at 110 °C and in 12 h under molecular oxygen and base-free conditions. The mechanism studied showed that the highly dispersed CoC_x sites as well as the strong interaction between Co and N species in the Co@C-N materials could efficiently improve the catalytic activity. This strategy opens up opportunities for preparing low-cost metal@C-N materials for the selective oxidation of alcohols to aldehydes.