Synthesis of hollow CuO/ZnO/Al2O3 composite microspheres for catalysing carbon dioxide hydrogenation

Homogeneous hollow CuO–ZnO–Al2O3 microspheres, which were synthesised, used carbonaceous saccharide as a template by the hydrothermal treatment at 180°C. The hollow microspheres structure of composite metal oxides was characterised by the methods of X-ray powder diffraction, thermogravimetric analysis, scanning electron microscopy, transmission electron microscopy and N2 adsorption–desorption isothermal. In the evaluation of the hydrogenation of carbon dioxide, the synthesised hollow CuO/ZnO/Al2O3 composite microspheres exhibited higher selectivity and yield of methanol than CuO/ZnO/Al2O3 prepared by a co-precipitation method. An optimum yield of methanol of 15.3% with the 24.7% CO2 per pass conversion was obtained under the reaction conditions of pressure at 3.0 MPa, space velocity at 1800 ml gcat −1 h−1, the volume ratio of CO2/H2 at 1:3 and temperature at 262°C.