Cu/Zn/Al/Zr catalysts via phase-pure hydrotalcite-like compounds for methanol synthesis from carbon dioxide

• Phase-pure Cu/Zn/Al/Zr hydrotalcite-like compounds were formed when Al > 22.5 mol%.
• The yields of hydrotalcite-like phase increased with increasing Al content.
• The specific surface area and Cu dispersion increased gradually with increased Al.
• Cu/Zn/Al/Zr catalyst via mixed phase exhibited much worse catalytic performance.
• The Cu/Zn/Al/Zr catalyst with Al = 27.9 mol% afforded the best catalytic performance.

Cu/Zn/Al/Zr catalysts with Cu2+:Zn2+:Al3+:Zr4+ = 2:1:x:0.1 (x = 0.6–1.5) were prepared from hydrotalcite-like precursors by co-precipitation method and tested for the CO2 hydrogenation to methanol. Both Cu/Zn/Al/Zr hydrotalcite-like and malachite phase were formed at low Al content. However, with the increase of Al content, the yield of hydrotalcite-like phase increased and phase-pure Cu/Zn/Al/Zr hydrotalcite-like compound was obtained for x ≥ 0.9. In addition, both the specific surface area and the dispersion of Cu increased gradually with the increase of Al, while the exposed Cu surface area first increased until Al content was 27.9 mol%, then decreased. The results of catalytic test for CO2 hydrogenation revealed that Cu/Zn/Al/Zr catalysts via phase-pure hydrotalcite-like compounds exhibited much better catalytic performance with higher CO2 conversion and CH3OH selectivity compared with the catalyst derived from mixed phase (hydrotalcite-like and malachite). The Cu/Zn/Al/Zr catalysts with Cu2+:Zn2+:Al3+:Zr4+ = 2:1:1.2:0.1 resulting from phase-pure hydrotalcite-like precursors afforded the substantial stability and the best catalytic performance.

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