Oxygen vacancy-enriched MOF-derived Mn2O3 catalysts for high-efficiency direct synthesis of ethylene urea from CO2

Abstract

The direct reaction of CO₂ with ethylene diamine (EDA) to produce ethylene urea (EU) provides significant potential for the resourceful utilization of CO₂. Herein, we systematically synthesized a series of Mn₂O₃ catalysts by pyrolyzing the corresponding metal–organic framework (MOF) precursor with different calcination temperatures to evaluate their catalytic activity in the synthesis of EU from CO₂. Among them, MnBDC-400 exhibited the highest reactivity for EU formation, which reached 96% EDA conversion and 98% EU selectivity, even at a lower temperature (120 °C). This result was superior to all previously reported catalysts. The excellent activity benefited from more surface oxygen vacancies and Mn³⁺ species on the surface of MnBDC-400, which facilitated the formation of ethylenediamine carbamate (EDA-CA) intermediates, leading to improved EU yields. This work has a certain guiding significance for the preparation of highly active MOF-derived oxide catalysts for CO₂ conversion.