Membrane technology, particularly polymeric membranes, is utilized in major industrial ethylene recovery owing to the very convenient and robust process. Thus, in this paper, a composite membrane (CM) comprising SAPO-34 and Pebax-1657 was employed to conduct a separation performance under two operating conditions, including temperatures and pressures, ranging from 25.0�60.0 °C and 3.5�10.0 bar, respectively. CO2 permeability and CO2/C2H4 ideal selectivity values that ranged from 105.68 to 262.86 Barrer and 1.81 to 3.52, respectively, were obtained via the experimental works. The separation of carbon dioxide (CO2) from ethylene (C2H4) has then been optimized using response surface methodology (RSM) by adopting a central composite design (CCD) method. As a result, the ideal operational conditions were discovered at a temperature of 60.0 °C and pressure of 10.0 bar with the maximum CO2 permeability of 233.62 Barrer and CO2/C2H4 ideal selectivity of 3.22. The typical discrepancies between experimental and anticipated data for CO2 permeability and CO2/C2H4 ideal selectivity were 1.67 and 3.10, respectively, demonstrating the models� validity. Overall, a new combination of Pebax-1657 and SAPO-34 composite membrane could inspire the latest understanding of the ethylene recovery process. © 2023 by the authors.