Catalyst deactivation in the direct synthesis of dimethyl ether from syngas over CuO/ZnO/Al2O3 and γ-Al2O3 mechanical mixtures

It was demonstrated that water adsorbs over the γ-Al2O3 surface, blocking its active sites and causing a sharp conversion drop (mainly observed during the first hours on stream). This effect was reversible and could be avoided by increasing temperature (270 °C or above). The other deactivation mechanism was the deposition of carbonaceous species over the catalyst surface. A deactivation model was proposed and fitted to the experimental data.