In this study a multi-step method was proposed to synthesize thin, high-permeable and well-oriented SAPO-34 membranes. The advantages of the different binary to quinary combinations of the available effective methods including support-masking, ionic-linkage, chemical-functionalization, dip-coating, hydrothermal and dry-gel on the structure and performance of SAPO-34 membranes in CO2/CH4 gas separation process were investigated. We applied for the first time, the crystallographic preferred orientation index (CPO) for comparative evaluation of proposed methods on the performance of membranes. The adsorption properties of supported membranes were also estimated and compared with those of SAPO-34 powder and of alumina support for better understanding of the effect of CPO on the mass transfer mechanism. It was found that the CO2 adsorption capacity is sensitive to CPO. Lower diffusion resistance, shorter diffusion path and less tortuosity were achieved at higher CPO, which made the penetration rate overcome on the absorption rate, and consequently enhanced the selectivity. (C) 2019 Elsevier Ltd. All rights reserved.