The effect of spatially patterned catalyst beds was investigated using direct dimethyl ether (DME) synthesis from synthesis gas as an example. A layered arrangement of methanol synthesis (MS) and dehydration catalyst was chosen and studied by numerical simulation under typical operating conditions for single-step DME synthesis. It was revealed that catalyst layers significantly influence the DME productivity. With an increasing number of layers from two to 40, an increase in DME productivity was observed approaching the performance of a physical catalyst mixture for an infinite number of layers. The results prove that a physical mixture of MS and dehydration catalyst achieves the highest DME productivity under operating conditions chosen in this study. Essentially, the layered catalyst arrangement is comparable to a cascade model of the two-step process, which is less efficient in terms of DME yield than the single-step process. However, the layered catalyst arrangement could be beneficial for other reaction systems. (c) 2012 American Institute of Chemical Engineers AIChE J, 00: 000000, 2012