Kinetics of the direct DME synthesis from CO$_{2}$ rich syngas under variation of the CZA-to-γ-Al$_{2}$O$_{3}$ ratio of a mixed catalyst bed

The one-step synthesis of dimethyl ether over mechanical mixtures of Cu/ZnO/Al$_{2}$O$_{3}$ (CZA) and γ-Al$_{2}$O$_{3}$ was studied in a wide range of process conditions. Experiments were performed at an industrially relevant pressure of 50 bar varying the carbon oxide ratio in the feed (CO$_{2}$ in COx from 20 to 80%), temperature (503–533 K), space-time (240–400 kg$_{cat}$s m$_{gas}$$^{-3}$), and the CZA-to-γ-Al$_{2}$O$_{3}$ weight ratio (from 1 to 5). Factors favoring the DME production in the investigated range of conditions are an elevated temperature, a low CO$_{2}$ content in the feed, and a CZA-to-γ-Al$_{2}$O$_{3}$ weight ratio of 2. A lumped kinetic model was parameterized to fit the experimental data, resulting in one of the predictive models with the broadest range of validity in the open literature for the CZA/γ-Al$_{2}$O$_{3}$ system.