CO2 hydrogenation to methanol over CuZnGa catalysts prepared using microwave-assisted methods

A series of CuZnGa catalysts was synthesized by microwave-assisted method and their performance for CO 2 hydrogenation to methanol was measured under a range of reaction conditions (temperatures between 250 °C and 270 °C and pressure up to 4.5 MPa). The influence of the preparation method on the physicochemical properties of catalysts was studied by N 2 adsorption, XRD, TPR, XPS, N 2 O titration and CO 2 adsorption followed by temperature programmed desorption and calorimetry. The results indicate that the one-pot microwave-assisted precipitation method used in the preparation of the (CuZnGa) MW catalyst, promoted copper and Ga 2 O 3 dispersion. Moreover, the mean basic site strength of (CuZnGa) MW was higher than that of the other catalysts prepared. All of these factors were found to affect its catalytic performance greatly in terms of CO 2 conversion and methanol selectivity. (CuZnGa) MW was highly stable and produced 4.87 mol methanol kg cat −1  h −1 at 250 °C with a selectivity of approximately 50% ( P  = 4.5 MPa, GHSV = 3000 h −1 , CO 2 /H 2  = 1/3). The strong interaction between copper and support prevented metallic copper sintering, affording high stability of catalyst. The promoting effect was related to an intimate association between highly dispersed copper species and strong basic ZnO species in the presence of small particles of Ga 2 O 3 .