Development of highly stable catalyst for methanol synthesis from carbon dioxide

• The doped Zr promoted the H2 reduction of CuOx.
• CZZA is proved to be effective resistant against water poisoning.
• A parallel reaction network by CO2 hydrogenation was revealed over CZZA.

Zr-doped Cu-Zn-Zr-Al (CZZA) catalyst showed excellent performances for the methanol synthesis from carbon dioxide and hydrogen such as activity, selectivity and especially stability under mild conditions (such as 230 °C and 3.0 MPa). The catalyst showed excellent tolerance against water vapor. It was found that added alumina promoted the dispersion of Cu whereas it suppressed the reduction of copper oxide. On the other hand, added Zr promoted the catalytic activity of methanol synthesis from CO2 and suppressed the inhibitive effect of water for the reaction as well as the catalyst deactivation. It was concluded that the methanol formation from CO2 proceeds through two routes: one is the direct hydrogenation of CO2 to methanol and another is the one which pass through the CO formation. The Zr-promoted catalyst gave methanol and CO at the selectivity ratio of 0.4 to 0.6, whereas the un-promoted catalyst gave only CO at the initial stage of the reaction. It was claimed that the doped Zr promote the in-situ reduction of oxidized Cu (which should be caused by the reaction with the co-product H2O) by H2 to increase the content of reduced Cu (active site) and thus the catalyst activity. The promoted reductivity of the Zr-containing catalyst prevents the crystal growth of CuOx which cause the irreversible deactivation of catalyst.

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