Catalyst system and process for preparing dimethyl ether

A catalyst system for a continuous synthesis gas-to-dimethyl ether process, comprising two spatially separated subsequent catalyst layers 1 and 2 in flow direction, the catalyst layers 1 and 2 having a volume ratio of from 9:1 to 1:9, catalyst layer 1 being formed of a packed bed of synthesis gas-to-methanol catalyst 1 particles or an admixture of catalyst 1 particles and inert 1 particles in a weight ratio of from 1:4 to 4:1, catalyst 1 particles comprising based on the total weight of catalyst 1 particles, which is 100 weight-%, 30 to 70 weight-% CuO, 10 to 30 weight-% ZnO, 10 to 30 weight-% Al2O3, the amount of ZrO2, if present, is in the range of from 0.5 to 5 weight-%, 0 to 7 weight-% of further additives, inert 1 particles comprising Al2O3,

• catalyst layer 2 being formed of a packed bed of an admixture of catalyst 1 particles and methanol-to-dimethyl ether catalyst 2 particles in a weight ratio of from 1:9 to 9:1, catalyst 2 particles being formed of an acidic aluminosilicate zeolite with a SiO2≥Al2O3 molar ratio of from 10 to 1500:1 of framework type MFI, comprising based on the total weight of catalyst 2 particles, which is 100 weight-%, 10 to 90 weight-% of at least one binder material, selected from Al2O3, SiO2, TiO2 and ZrO2, and 0.01 to 20 weight-% of copper,
• wherein the catalyst system is employed in one or more containments, which allow for the spatial separation of the subsequent catalyst layers 1 and 2, the containment having at least two sections in which the catalyst layers 1 and 2 are located, and the two sections being linked in a way that reactants can flow from catalyst layer 1 to catalyst layer 2.