抄録
Zeolites have micro pores within their crystals, diameters of which are almost equal to molecular diameters of lighter hydrocarbons. Therefore, zeolite membranes without any pinholes are expected to show high performance for shape selective separation of hydrocarbons. Moreover, by applying the zeolite membrane with catalysis to reaction in series, there is the possibility for producing intermediate species at higher yields than in those using conventional reactors. In this study, catalytic ZSM-5 zeolite membranes were employed to a reaction of methanol to olefins (MTO reaction). The ZSM-5 zeolite catalyst membrane without pinholes was successfully prepared by synthesizing a ZSM-5 zeolite layer on an outer surface of a cylindrical alumina ceramic filter. The membrane was used as the catalytic membrane reactor to recover olefins from methanol. Though olefins were successfully produced at a high selectivity from methanol, the paraffin production was observed at the feed side of the zeolite membrane. In order to inhibit the production of paraffin and aromatics, the acid site distribution of the ZSM-5 zeolite membrane was controlled by CCS method (Catalytic Cracking of Silane method developed in our laboratory). Deactivation of acid sites at the outer surface of the zeolite membrane (feed side of reactant) by the CCS method enable to increase the selectivity of olefins and decrease in the selectivities of paraffin and aromatics.
