RSM Modeling and Optimization of CO(2) Separation from High CO(2) Feed Concentration over Functionalized Membrane

The challenges in developing high CO(2) gas fields are governed by several factors such as reservoir condition, feed gas composition, operational pressure and temperature, and selection of appropriate technologies for bulk CO(2) separation. Thus, in this work, we report an optimization study on the separation of CO(2) from CH(4) at high CO(2) feed concentration over a functionalized mixed matrix membrane using a statistical tool, response surface methodology (RSM) statistical coupled with central composite design (CCD). The functionalized mixed matrix membrane containing NH(2)-MIL-125 (Ti) and 6FDA-durene, fabricated in our previous study, was used to perform the separation performance under three operational parameters, namely, feed pressure, temperature, and CO(2) feed concentration, ranging from 3.5–12.5 bar, 30.0–50.0 °C and 15–70 mol%, respectively. The CO(2) permeability and CO(2)/CH(4) separation factor obtained from the experimental work were varied from 293.2–794.4 Barrer and 5.3–13.0, respectively. In addition, the optimum operational parameters were found at a feed pressure of 12.5 bar, a temperature of 34.7 °C, and a CO(2) feed concentration of 70 mol%, which yielded the highest CO(2) permeability of 609.3 Barrer and a CO(2)/CH(4) separation factor of 11.6. The average errors between the experimental data and data predicted by the model for CO(2) permeability and CO(2)/CH(4) separation factor were 5.1% and 3.3%, respectively, confirming the validity of the proposed model. Overall, the findings of this work provide insights into the future utilization of NH(2)-MIL-125 (Ti)/6FDA-based mixed matrix membranes in real natural gas purification applications.