Methanol conversion over ZSM-12, ZSM-22 and EU-1 zeolites: from DME to hydrocarbons production

Conversion of methanol to dimethyl ether (DME) and hydrocarbons was investigatedover zeolites with several 1-dimensional channel systems: ZSM-12, ZSM-22 and EU-1. The effect of reaction temperature, contact time and Time-On-Stream towards methanol conversion and products selectivity was investigated. It was found that ZSM-22 zeolite exhibits the best performances during conversion of methanol to DME (temperature range 180-240 degrees C) as consequence of the particular shape selectivity that inhibits coke formation and deactivation. On the contrary, when formation of hydrocarbons is desired (temperature up to 320 degrees C), ZSM-12 shows the highest activity in terms of light olefin yield with the highest C-3/C-2 ratio. The low selectivity towards C-2 formation can be associated to the absence of both di-and tri-methyl benzenes formed during the reaction because when these species were detected, a higher ethylene productivity was observed lowering the C-3/C-2 ratio on the reactor outstream.