Methanol to olefins using ZSM-5 zeolite catalyst membrane reactor

A ZSM-5 zeolite catalyst membrane without pinholes was successfully prepared by synthesizing ZSM-5 zeolite layer on the outer surface of a cylindrical alumina ceramic filter. In the preparation of the membrane, to enhance the smoothness of the outer surface of the filter, a filter with pores of 0.1 (mu)m in diameter was employed. Furthermore, the hydrothermal synthesis was repeated using the same samples. The obtained zeolite membrane showed a molecular sieving effect for the permeation of gaseous xylene and diethylbenzene isomers. The ratio of the permeability of the para-isomer to the meta-isomer was about 2.7 for xylene and 6.0 for diethylbenzene, respectively. The membrane was used as a catalytic membrane reactor to recover olefins from methanol. By adjusting the diffusion rate to the chemical reaction rate for producing olefins within the ZSM-5 zeolite layer, olefins were successfully produced at a high selectivity (about 80–90%) from methanol at high conversions of 60–98%.