Synthesis and morphology control of nano CuAl2O4 hollow spheres and their application as an efficient and sustainable catalyst for CO2 fixation

Abstract

Four morphologies of the nano CuAl2O4 hollow microsphere were generated via different synthesis conditions. The results revealed that the morphology, structure and number of the shells of the CuAl2O4 product were strongly associated with the carbon template source, concentration of metal salts and hydrothermal processing time. By changing carbon template source, the hollow spheres of CuAl2O4 transformed from Yolk shell structure into triple shell hollow spheres. Further investigation also revealed that four types of the sample exhibited a varied catalysis performance for chemical fixation of carbon dioxide to produce cyclic carbonates with the efficiency decreasing from the flower like triple-shelled CuAl2O4 hollow spheres to the Yolk shelled CuAl2O4 hollow spheres. Various epoxides were converted at 85 °C, 0.3 MPa CO2 pressure, a catalyst loading of 0.5 mol% and a reaction time of 10 h in a solventless reaction media with isolated yields up to 98 % of the respective carbonate.