Effect of promoter SiO2, TiO2 or SiO2-TiO2 on the performance of CuO-ZnO-Al2O3 catalyst for methanol synthesis from CO2 hydrogenation

The influences of SiO2, TiO2 or SiO2-TiO2 promoters on the catalytic performance of CuO-ZnO-Al2O3 catalyst in the methanol synthesis from CO2 hydrogenation were studied. The catalysts were prepared by co-precipitation method, SiO2 and TiO2 were loaded by hydrolyzation of tetraethyl orthosilicate (TEOS) and hydrolyzation of tetra-n-butyl titanate (C16H36O4Ti), respectively. The catalytic performances of the prepared catalysts were investigated under conditions of T = 533 K, P = 2.6 MPa, H2:CO2 = 3:1 (volume ratio) and SV = 3600 h−1. The experimental results showed that the promoted catalysts showed a higher performance than CuO-ZnO-Al2O3. Especially, the one promoted with SiO2-TiO2 maximized both activity and methanol selectivity with 40.70% in CO2 conversion and 41.17% in methanol selectivity as compared to the one without promoter (15.81% in CO2 conversion and 23.31% in methanol selectivity). Characterizations of XRD, H2-TPR, H2-TPD, NH3-TPD, CO2-TPD and SEM revealed that all the promoters improved the CuO dispersion in the catalyst body and improved the adsorption/activation of H2 on the catalyst. Especially SiO2-TiO2 exhibited higher performance as compared to SiO2 or TiO2.