Combined methanol and dimethyl ether synthesis from CO/H2: Phosphorus mediated deactivation

The combined synthesis of methanol and DME from CO/H2 has been studied over physical mixtures of Cu/ZnO/Al2O3 and γ-Al2O3. Intimate contact between Cu/ZnO/Al2O3 and γ-Al2O3 is found to cause a rapid simultaneous deactivation of both components, which is significantly reduced by use of phosphated γ-Al2O3. The decline in methanol synthesis activity is shown to be associated with loss of Cu surface area accompanied by an increase in the Cu crystallite size. Mixtures containing phosphated γ-Al2O3 retain greater Cu area. TPD studies show that weakly-held water on γ-Al2O3 increases with the phosphorus content, which may also help to maintain the stability of Cu/ZnO by inverse spillover.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Combined synthesis of methanol and DME over mixtures of Cu/ZnO/Al2O3 and γ-Al2O3. ► Simultaneous deactivation of methanol forming and dehydrating components. ► Deactivation of methanol catalyst related to loss of Cu surface area. ► P addition to γ-Al2O3 enhances stability of both catalysts and Cu surface area.