Ceria-based nanorods catalysts for efficient catalytic production of ethylene urea from CO₂ and ethylenediamine: the influence of doped zirconium ions

Converting carbon dioxide into value-added products is one of the most important inventions to solve global warming and energy demand. Herein, we prepared a series of Zr-doped CeO₂ catalyst (Ce₁Zr_x, x = 0.01, 0.05 and 0.2) for the catalytic production of ethylene urea (EU) from ethylenediamine (EDA) and CO₂. Several characterization techniques, such as XRD, FTIR, Raman, TEM, N₂ adsorption, CO₂-TPD and XPS, were used to investigate the relationship between catalytic activity and structural characteristics, especially the doping form and promotion mechanism of Zr in CeO₂ lattice. The results present that the Ce₁Zr_0.01 catalyst revealed excellent catalytic activity with 91.5% EDA conversion and 100% EU selectivity and cyclic stability in comparison with undoped CeO₂. The doped Zr was beneficial to the formation of enriched defects and led to more oxygen vacancies and weak basic sites, thus enhancing CO₂ adsorption and activation. This work laid a foundation for the design of highly active catalysts for the synthesis of EU from CO₂ and EDA.