Ligand-Engineered Mn-MOFs Derived Mn2O3 for Enhanced Carbon Dioxide Conversion to Ethylene Urea

The utilization of carbon dioxide (CO2) for synthesizing value-added chemicals represents a promising environmentally sustainable strategy. Herein, we synthesized a series of Mn2O3 catalysts derived from metal-organic frameworks (MOFs) incorporating three different ligands—homophthalic tricarboxylic acid (H3BTC), 1,4-benzenedicarboxylic acid (H2BDC), and a combination of polyvinyl pyrrolidone (PVP) with H3BTC—via a hydrothermal method for ethylene urea (EU) production from CO2 and ethylenediamine (EDA). The Mn2O3 catalyst derived from the H3BTC+PVP ligand system (designated MnTP) demonstrated superior catalytic performance, achieving 97% EDA conversion and 97% EU selectivity under mild conditions (100 °C, 1 min), which surpassed all previously reported catalysts under comparable conditions. The enhanced activity originated from structural improvements induced by the H3BTC+PVP precursors, particularly the promotion of oxygen vacancies and Mn3+ species, thereby facilitating efficient CO2 activation and binding. This work establishes a novel strategy for the sustainable conversion of CO2 into high-value cyclic ureas through rational catalyst design.