Membrane separation technology has been recently attracted more attention as an option for gas separations due to its compact system, ease of operation and low power consumption. In this study, polymer membranes with different percentages of polyurethane were synthesized and submitted to permeability and selectivity tests for the following gases, CO2, N2, O2 and CH4, at two pressures of 4 and 8 bar and at room temperature. The membranes were characterized by FTIR-ATR, Scanning electron microscope (SEM), Thermogravimetric analysis (TGA) and X-ray diffractometer (XRD). At low pressure of 4 bar and room temperature, the membrane with low percentage of PU, 10 %, presented the higher selectivity to CO2 in relation to both N2 and CH4. The same behavior was observed at a high pressure of 8 bar, with higher selectivity to CO2 in relation to all studied gases, N2, O2 and CH4, compared to the already analogous reported membranes submitted at greater pressures.