H-SAPO-34 membrane was successfully synthesized using microwave heating at 473 K within a period of 2 h. The H-SAPO-34 membrane was ion-exchanged with alkaline earth cations. A comparison study was conducted to obtain the separation performance of different cation-exchanged membranes. The CO2 permeances reduced with cation-exchanged membranes in the order of Ca2+ > Mg2+ > Sr2+ > Ba2+. The highest increase in CO2/CH4 separation selectivity of about 240% was obtained by ion-exchanging the H-SAPO-34 membrane with Ba2+. Separation of equimolar of CO2 and CH4 was conducted at different separation temperatures and pressure differences across the Ba-SAPO-34 membrane. The maximum CO2/CH4 separation selectivity of 103 with CO2 permeance of 37.6 x 10(-8) mol/m(2) s Pa was obtained for equimolar feed mixture of CO2 and CH4 at 303 K and 100 kPa pressure difference across Ba-SAPO-34 membrane. (c) 2011 Elsevier B.V. All rights reserved.