Helium extraction from natural gas using DD3R zeolite membranes

Helium (He) is commercially produced from natural gas by low-temperature condensation. The process is energy extensive because of the extremely low He concentration (<0.3%) and the operation at cryogenic temperature. Herein we demonstrated DD3R zeolite membrane was efficient to extract He from natural gas at atmosphere temperature. The membrane performance was evaluated in terms of temperature, pressure and molar fractions. The overall membrane performance was dominated by the diffusivity selectivity. The single He permeance and ideal He/CH₄ selectivity were 5.8×10^-9 mol·m^-2·s^-1·Pa^-1 and 79 under a feed pressure of 1.3 MPa. Even though He concentration was as low as 0.22%, the He permeance and He/CH₄ mixture selectivity were 3.0×10^-9 mol·m^-2·s^-1·Pa^-1 and 44 at 0.7 MPa. During the long-term operation (～130 h) the membrane performance was stable even the feed mixture containing 3.6% ethane as contaminations. The results approved the feasibility of DD3R zeolite membranes for He extraction from natural gas.