Influence of Zr on the performance of Cu/Zn/Al/Zr catalysts via hydrotalcite-like precursors for CO2 hydrogenation to methanol

A series of Cu/Zn/Al/Zr hydrotalcite-like precursors with Zr4+:(Al3++Zr4+) from 0 to 0.7 were synthesized by a co-precipitation method. X-ray diffraction and thermogravimetric measurements demonstrated that the yield of the hydrotalcite-like phase decreases with increased Zr content. The Cu/Zn/Al/Zr mixed oxides were then obtained by calcination of the hydrotalcite-like precursors and tested for methanol synthesis from CO2 hydrogenation. With increased Zr4+:(Al3++Zr4+) atomic ratio, the exposed Cu surface area and dispersion of Cu first increase until Zr4+:(Al3++Zr4+) = 0.3 and then decrease. However, the total number of basic sites on catalysts increases continuously. It is also found that the CO2 conversion is related to the exposed Cu surface area and the dispersion of Cu, while the CH3OH selectivity is related to the distribution of basic sites on the catalyst surface. The incorporation of a suitable amount of Zr is beneficial for the production of methanol, and the best catalytic performance is obtained when the Zr4+:(Al3++Zr4+) atomic ratio is 0.3.

Graphical abstractWith increasing Zr content, the exposed Cu surface area first increases until Zr4+:(Al3++Zr4+) = 0.3 and then decreases, and the proportion of strongly basic sites shows a similar trend, except for Zr4+:(Al3++Zr4+) = 0.7. Both the CO2 conversion and the CH3OH selectivity exhibit a volcano trend with increasing Zr content.Figure optionsDownload full-size imageDownload high-quality image (71 K)Download as PowerPoint slideHighlights► The introduction of Zr affects the Cu surface area and Cu dispersion of catalyst. ► The introduction of Zr affects the surface basicity of the reduced catalyst. ► The CO2 conversion is related to the Cu surface area and Cu dispersion of catalyst. ► The methanol selectivity is related to the distribution of basic sites of catalyst. ► The incorporation of suitable amount of Zr is favor for the catalytic performance.