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. The present MFI 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, including the pressure dependence. 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 710–2700 GPU
in the 1-9 bar feed pressure range. Furthermore, we parametrize and
apply multicomponent Maxwell-Stefan transport equations to predict the
main trends in separation behavior over a range of operating conditions.