Engineering Oxygen Vacancies in Non-Noble CuxFe1/ZrO2 Catalysts for Synthesis of N,N′-Diphenylurea from CO2 and Aniline

In this study, a non-noble bimetallic-supported metal oxide catalyst, CuxFe1/ZrO2 rich in oxygen vacancies, was synthesized via dry ball milling for the direct synthesis of N,N′-diphenylurea (DPU) from CO2 and aniline. The optimal Cu5Fe1/ZrO2 catalyst achieved 12.7% aniline conversion with near-100% DPU selectivity (99.9%). Comprehensive characterizations revealed that abundant oxygen vacancies enhance metal–support interaction and serve as primary sites for CO2 adsorption and activation. Combined temperature-programmed desorption of NH3 and CO2 (CO2/NH3-TPD) and in situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) studies elucidated a synergistic acid–base catalytic mechanism. Lewis basic Cu/Fe sites activate CO2, while Lewis acidic Zr4+ sites adsorb and activate aniline, promoting the formation of the key C6H5NH–(CO) intermediate. The catalyst maintained high performance over five cycles, demonstrating excellent stability. This work offers an effective strategy for designing robust non-noble catalysts for CO2 valorization into value-added chemicals.