Synthesis of dimethyl ether (DME) via methanol dehydration were investigated over HY zeolite and over Fe-, Co-, Ni-, Cr-, or Zr-modified HY zeolite, and via direct CO hydrogenation over modified HY zeolite-supported Cu-Mn-Zn catalysts. Zr- and Ni-modified Hy zeolite exhibited higher activity and stability for methanol dehydration, while Fe-, Co-, and Cr-modified HY zeolite deactivated quickly due to carbon deposition. For DME synthesis directly from CO hydrogenation, it was found that the amount of dehydration component had an important influence on. the performance of the dual catalyst. Zr-HY supported Cu-Mn-Zn catalyst was more active and stable than Cu-Mn-Zn/HY in the "synthesis gas to dimethyl ether" process. (c) 2006 Elsevier B.V. All rights reserved.