In Situ Growth of Continuous b-Oriented MFI Zeolite Membranes on Porous α-Alumina Substrates Precoated with a Mesoporous Silica Sublayer

Continuous b -oriented MFI membranes were prepared on a mesoporous silica sublayer-coated porous α-alumina substrate by in situ crystallization. Single gas permeation of butane isomers through the MFI membrane was carried out as a function of temperature from 298 to 473 K. A decreased permeance of butane isomers on the b -oriented MFI membrane with increasing temperature is observed in this temperature range, which is attributed to a weak adsorption effect. Meanwhile, it was revealed that the b -oriented membrane can maintain a high ideal selectivity of n -butane/ i -butane at elevated temperatures. On the contrary, a discrete membrane with a randomly oriented top layer was obtained on the uncoated α-alumina substrate. Further investigation on the evolution of the MFI membranes on the two kind substrates was performed with the focus on the understanding of the oriented growth of zeolite crystals. The surface properties of the substrates used played an important role in the formation of MFI membranes with different morphologies.