Revalorization of CO2 for methanol production via ZnO promoted carbon nanofibers based Cu-ZrO2 catalytic hydrogenation

Abstract

Abstract A series of novel carbon nanofibers (CNFs) based Cu-ZrO2 catalysts were synthesized by deposition precipitation method. To investigate the influence of promoter, catalysts were loaded with 1, 2, 3 and 4 wt% ZnO and characterized by ICP-OES, HRTEM, BET, N2O chemisorption, TPR, XPS and CO2-TPD techniques. The results revealed that physicochemical properties of the catalysts were strongly influenced by incorporation of ZnO to the parent catalyst. Copper surface area (SCu) and dispersion (DCu) were slightly decreased by incorporation of ZnO promoter. Nevertheless, SCu and DCu were remarkably decreased when ZnO content was exceeded beyond 3 wt%. The catalytic performance was evaluated by using autoclave slurry reactor at a pressure and temperature of 30 bar and 180 °C, respectively. The promotion of Cu-ZrO2/CNFs catalyst with 3 wt% of ZnO enhanced methanol synthesis rate from 32 to 45 g kg−1 h−1. Notably, with the ZnO promotion the selectivity to methanol was enhanced to 92% compared to 78% of the un-promoted Cu-ZrO2/CNFs catalyst at the expense of a lowered CO2 conversion. In addition, the catalytic activity of this novel catalyst system for CO2 hydrogenation to methanol was compared with the recent literature data.