Active‐Site Engineering in Ba 2+ ‐Doped ZnO for Urea‑to‑Ethylene Carbonate Conversion: Mechanistic and Kinetic Evidence

This study investigates the catalytic performance of barium‐doped zinc oxide (Ba‐ZnO) solid catalysts for the cycloaddition of CO from urea to ethylene glycol (EG) to produce ethylene carbonate (EC). The Ba‐doped ZnO was prepared by a simple co‐precipitation method, and the physicochemical properties of the catalysts were characterized using various techniques such as N 2 sorption, TG‐DTA, XPS, FESEM, TPD, and FTIR. The peroxo and Brönsted base hydroxyl species are generated on the surface and act as protective sites to mitigate NH 3 poisoning on the catalyst surface. The effect on the surface morphology confirmed a substantial change in the formation of clustered rod‐like structures for Ba‐ZnO. The catalytic performance of screened catalysts correlated well with active site density, acidity, and basicity. The surface kinetics based on the Langmuir‐Hinshelwood model were used to predict the surface reaction mechanism occurring on the Ba‐ZnO catalyst. The findings demonstrate the potential of Ba‐ZnO catalysts in the efficient conversion of EG to EC. Under the optimized reaction conditions, the catalyst exhibited the highest conversion and selectivity of 87.3% and 94.5%, respectively. The Ba‐ZnO catalyst exhibited good recyclability and maintained structural integrity as assessed by the spent catalyst characterizations.