Large-size 19-channel monolithic silicalite-1 membranes for butane separation: Separation performance and quantification of concentration polarization

Developing an energy-saving membrane technology is important for the separation of hydrocarbon isomers. For the first time, separation performance of large-size 19-channel monolithic silicalite-1 membranes and the correlation of the performance with concentration polarization index were reported for separating industrial n-/i-butane (n-/i-C4) mixtures. The effective membrane area of each element was up to 0.1 square meters. Four membranes showed average n-C4 permeance and n-/i-C4 separation factor of (3.8 ± 0.1) × 10^-8 mol/(m² s Pa) and 27.5 ± 0.58 at 333 K, respectively. The impact of operating parameters and concentration polarization on separation performance of the typical monolithic membrane were investigated. Two solutions were proposed to reduce the influence of concentration polarization. The correlation of separation performance and concentration polarization can be used for performance prediction. The large-size silicalite-1 membranes exhibited long-term stability in the separation of butane isomers.