Evolution of zincian malachite synthesis by low temperature co-precipitation and its catalytic impact on the methanol synthesis

Low temperature co-precipitation enabled, for the first time, the preparation of phase pure zincian malachite precursors with Zn contents of up to 31 at.-%. The high Zn content was beneficial for maximizing the dispersion of Cu and oxygen defect sites on the ZnO surface. Further, an increase of the Zn loading from 10 to 31 at.-% doubled the specific surface areas obtained from N2O-RFC (Reactive Frontal Chromatography) and H-2-TA (Transient Adsorption). As the Zn content was increased from 10 to 31 at.-%, the apparent activation energy for methanol formation was strongly decreased. Furthermore, water formation was reduced indicating a retardation of the rWGS in favor of methanol formation at high Zn loadings. Additionally, compared to high temperature co-precipitation, low temperature precipitated catalysts exhibited increased catalytic activities.