Base-Tailored Hierarchical MgO Microspheres as Efficient Catalysts for CO2 Fixation into Oxazolidinone at Atmospheric Pressure

Wide-range implementations are ongoing to utilize recombinant CO2 for value-added chemical synthesis via various catalytic approaches. Among others, thermal catalysis is a highly compelling and decisive approach to depleting CO2 in the atmosphere. This study describes a solvent- and cocatalyst-free CO2 fixation reaction employed by efficient hierarchical magnesium oxide microspheres. A straightforward precipitation process assisted the synthesis of base MgO materials using different precipitating agents. Successfully designed material inherent properties were investigated by TGA, XRD, FE-SEM, N2 sorption, NH2/CO2-TPD, TEM/HR-TEM, and XPS analyses. The SC-MgO material that showed essential features was tested as a promising catalyst for the oxazolidinone reaction. Interestingly, the SC-MgO catalyst attained outstanding catalytic activity with 100% conversion of aniline and 97% yield and selectivity of the oxazolidinone product under atmospheric pressure. To comprehend the catalytic activity of the SC-MgO catalyst, various reaction parameters such as the effect of catalyst dosage, time, temperature, and solvents were investigated in detail. Additionally, the SC-MgO catalyst showed excellent catalytic activity toward the desired substituted oxazolidinone derivatives under optimized reaction conditions. The SC-MgO significant catalytic activity was completely reliant on inherent properties such as microsphere morphology, high specific surface area, and Lewis acidic and Lewis basic sites. The tentative oxazolidinone reaction mechanism was evidently proposed with the help of characterization and experimental results. Remarkably, the SC-MgO catalyst showed excellent recyclability with a stable catalytic activity performance along with structural and physicochemical properties for up to 10 consecutive cycles. We successfully demonstrated the highly feasible CO2 fixation process using recyclable MgO catalyst for the oxazolidinone synthesis.