Synthesis and Characterization of SAPO-34/ Fluorinated Polyimide Composite Membrane for Biogas Purification

The growing demand for renewable energy has increased the need for efficient biogas upgrading to produce high purity biomethane. While polymeric membranes offer an energy efficient separation method, their performance is limited by the permeability and selectivity trade-off. Incorporating inorganic fillers into polymers to form composite membranes is a promising strategy to overcome this limitation. In the present work, a series of SAPO-34/fluorinated polyimide composite membranes were synthesized for CO2 removal from CH4 in biogas by incorporating inorganic filler loadings of 1 4 wt.% into the polymer matrix. The morphology of the membranes were characterized using Field Emission Scanning Electron Microscopy (FESEM) and their CO2/CH4 separation performance was evaluated. FESEM images show that SAPO-34 particles were uniformly dispersed within the polymer matrix, with no particle agglomeration or significant interfacial voids between the filler and polymer phases. All composite membranes exhibited higher selectivity compared to the virgin polymer membrane, with the membrane containing 3 wt.% SAPO-34 achieving the highest selectivity of 84.99. Furthermore, the membranes loaded with 3 wt.% and 4 wt.% SAPO-34 were able to surpass 2008 Robeson upper bound. Overall, the incorporation of an optimal SAPO-34 loading enhances CO2/CH4 separation performance, demonstrating strong potential for efficient biogas upgrading applications.