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.