Copper-doped ZnO-ZrO2 solid solution catalysts for promoting methanol synthesis from CO2 hydrogenation

Abstract

Copper-doped ZnO-ZrO₂ solid solution catalysts were synthesized via co-precipitation for promoting CH₃OH synthesis via hydrogenation of CO₂. Various testing methods were applied to investigate the effect of various copper contents on the catalysts. The catalytic performance was evaluated by a fixed bed reactor. XRD, HRTEM and Raman spectra collectively indicated that a ZnO-ZrO₂ solid solution catalyst with 3% Cu had a higher Cu dispersion, while the H₂-TPR results confirmed that a catalyst with 3% Cu had more Cu active sites under low temperature H₂ pretreatment. When the copper content increased to 5% and 10%, the catalyst showed a better Cu crystallinity and a worse Cu dispersion, which could have a negative effect. Therefore, the CO₂ conversion and methanol yield with a 3% CuZnO-ZrO₂ catalyst at 5 MPa, 250°C and 12 000 ml/(g h) increased by 8.6% and 7.6%, respectively. Moreover, the CH₃OH selectivity and catalytic stability of the solid solution catalyst were better than those of the traditional CZA catalyst.

Keywords: CO2 hydrogenation; ZnO-ZrO2; copper-doped; solid solution.