Lewis acid-base modulated lanthanum-doped zinc oxide catalyzed CO₂ conversion to ethylene carbonate

The massive emission of the greenhouse gas CO₂ has caused problems such as global warming and ecological damage. How to effectively utilize CO₂ as a resource and create economic benefits has attracted much attention in recent years. In this paper, a series of La-doped ZnO catalysts were designed and synthesized targeting the synthesis of ethylene carbonate (EC) from CO₂ and ethylene glycol (EG), which could modulate the Lewis acid-base sites on the ZnO surface, and the catalyst activity was investigated under additive-free conditions. La-ZnO-1%-550℃ had the best catalytic activity with 0.54% conversion of EG, 7.326 mmol/(h∙g) and 99% space-time yield and selectivity of EC at 130 ℃, 4 MPa CO₂, and 1 h with good stability. Combined with the analysis of the crystal structure, morphology and surface acid-base of the catalysts, the results showed that La was uniformly distributed in the ZnO hollow nanosheets, and the surface of the La-doped ZnO calcined at 550 ℃ had the most Lewis acid-base sites, and the catalytic activity of the catalysts increased with the increase of moderate to strong Lewis acid-base sites.