The effect of olefin addition to a stream dimethyl ether on the methanol homologation reaction is investigated using iron-substituted zeolites Fe-beta and Fe-ZSM-5. was plug-flow microreactors in temperature range 240–400 °C, at total pressure 0.239 MPa WHSV 6.12 (g DME/g cat -hr). For (Si/Fe= 9.2) catalysts, isobutene co-feeding almost doubles (DME) consumption rate shifts selectivity towards ...