Separation of <scp> C ₂ –C ₄ </scp> hydrocarbons from methane by zeolite <scp>MFI</scp> hollow fiber membranes fabricated from <scp>2D</scp> nanosheets

Separation of higher hydrocarbons from methane is an important and energy-intensive operation in natural gas processing. We present a detailed investigation of thin and oriented MFI zeolite membranes fabricated from 2D MFI nanosheets on inexpensive α-alumina hollow fiber supports, particularly for separation of n-butane, propane, and ethane (“natural gas liquids”) from methane. These membranes display high permeances and selectivities for C2–C4 hydrocarbons over methane, driven primarily by stronger adsorption of C2–C4 hydrocarbons. We study the separation characteristics under unary, binary, ternary, and quaternary mixture conditions at 298 K and 100–900 kPa feed pressures. The membranes are highly effective in quaternary mixture separation at elevated feed pressures, for example allowing n-butane/methane separation factors of 170–280 and n-butane permeances of 710–2,700 GPU over the feed pressure range. We parametrize and apply multicomponent Maxwell–Stefan transport equations to predict the main trends in separation behavior over a range of operating conditions.