AluminoPhosphate (AlPO)-17 and silicoalufninophosphate (SAPO)-17, for the first time, were made into selective membranes for CO(2)separations. Pure and submicron SAPO-17 seeds were synthesized using nano zeolite T crystals as silica precursor. Membrane microstructure (thickness and crystal size) and separation performance were strongly affected by the support chemistry and seeds. The selective membranes were prepared by a single hydrothermal synthesis step using the low-cost symmetric macroporous ceramic tubes as substrates. Single(-)gas and CO2/CH4 mixed-gas permeations through SAPO-17 membranes were investigated as functions of pressure and temperature. Carbon dioxide permeance and CO2/CH4 selectivity were decreased with the increase of pressure and temperature. The best membrane showed the smaller-component permeances of 1.1 x 10(-6) and 8.0 x 10(-7) mol/(m(2) s Pa), and mixture selectivities of 53 and 14 for equimolar CO2/CH4 and CO2/N-2 mixtures, respectively, at 298 K and 0.2 MPa pressure drop. (C) 2016 Elsevier B.V. All rights reserved.