# Graphene-Based Membranes for CO2/CH4 Separation: Key Challenges and Perspectives
## Mixed-Matrix Membranes
### Challenges
** & **(bserver)** & **Enhanceance** & **atCO\({}_{3}\)/CH\({}_{4}\)** & **Enhanceance** & **atCO\({}_{3}\)/CH\({}_{4}\)** & **Enhanceance** & **atCO\({}_{3}\)/CH\({}_{4}\)** & **Enhanceance** & **atCO\({}_{3}\)/CH\({}_{4}\)** & **Enhance** \\ \hline Nonfunctionalized & PDMS & 0.5 & 1.1 & 37 & 4460 & 47.68 & 4.2 & 16.67 & 0.80 & [64] \\ genome & PDMS & 1 & 10 & 35 & 2429.76 & -40.69 & 3.58 & 17.6 & -4.10 & [87] \\ GO & PDMS & 8 & 10.1 & 35 & 1422.22 & -40.60 & 9.40 & 299.00 & 2.07 & [86] \\ GO & PRax 1657 & 1 & 3 & 25 & 100.00 & 120.06 & 24.66 & 14.42 & 1.06 & [54] \\ PE-TRG & PRax 1657 & 10 & 2 & 30 & 145.00 & 76.83 & 24.0 & 26.32 & 1.19 & [53] \\ In-CO & PRax 1657 & 0 & 2 & 30 & 1330.00 & 17.08 & 45.0 & 136.84 & 3.27 & [58] \\ In-CO & PRax 1657 & 0.8 & 4 & 25 & 640.00 & 3.56 & 25.10 & -3.83 & -0.07 & [69] \\ Few-layer graphene & PM-1 & 0.0006 & 1 & 25 & 12700 & 148.05 & 8.76 & -41.84 & -0.52 & [70] \\ Few-layer graphene & PM-1 & 0.0071 & 1 & 25 & 3410 & 33.40 & 21.31 & 41.53 & 1.20 & [70] \\ Few-layer graphene & PM-1 (200-day-sign) & 0.0006 & 1 & 25 & 9240 & 511.77 & 9.43 & -48.62 & -0.83 & [71] \\ GO & Mutimid® & 0.5 & 0.5 & 26 & 76.00 & -49.33 & 21.71 & 21.6 & -0.16 & [71] \\ GO & Mutimid® & 2 & 2 & 30 & 11.73 & 32.69 & 48.53 & 43.62 & 1.24 & [58] \\ GO & Mutimid® & 10 & 2 & 30 & 6.46 & -26.92 & 70.30 & 16.76 & 1.60 & [58] \\ MWCNTGO (1-1) & Mutimid® & 10 & 2 & 30 & 38.07 & 303.66 & 84.00 & 148.82 & 3.66 & [58] \\ Graphene & Mutimid® & 10 & 2 & 30 & 39.89 & 20.76 & 20.16 & -28.6 & -0.70 & [58] \\ MWCNTGO (1-1) & Mutimid® & 10 & 2 & 30 & 35.49 & 332.60 & 78.57 & 178.12 & 4.16 & [58] \\ GO & PRax-PFP & 0.075 & 0.5 & 25 & 130.00 & -13.33 & 21.70 & 21.5 & 0.37 & [71] \\ GO & PEO-PFP/PAN & 0.075 & 0.5 & 25 & 603.07 & -25.00 & 21.71 & 18.4 & 0.16 & [71] \\ GO & Pero-PFP/PAN & 0.5 & 0.5 & 25 & 242.12 & -70.00 & 21.29 & 16.1 & -0.81 & [71] \\ GO & Mutimid® & 8 & 34 & 35 & 3.89 & -47.07 & 20.50 & -36.34 & -1.83 & [72] \\ GO & FF & 8 & 34 & 35 & 2.98 & -51.70 & 16.67 & -45.34 & -2.32 & [72] \\ MWCNTGO nanotubes & PI & 1 & 1 & 35 & 17 & 13.3 & 25.0 & 92.3 & 1.85 & [72] \\ Dx-CO\({}_{3}\)/CO & SPEX & 8 & 1.5 & 25 & 22.26 & 43.87 & 48.8 & 82.77 & 1.56 & [56] \\ Dx-CO\({}_{3}\)/CO & SPEX & 8 & 1 & 25 & 1267.60 & 120.7 & 81.8 & 207.52 & 3.75 & [56] \\ Dx-CO\({}_{3}\)/CO & SPEX & 8 & 1 & 25 & 1227.06 & 117.08 & 80.7 & 203.38 & 3.70 & [56] \\ GO & ODOR-TMPA & 5 & 1 & 25 & 985.81 & 7.49 & 41.10 & 29.58 & 0.76 & [59] \\ ZTF-GO (1-2) & ODOR-TMPA & 5 & 1 & 25 & 146.57 & 60.00 & 40.92 & 29.01 & 1.14 & [59] \\ GO & Mutimid® & 10 & 1 & 25 & 27.84 & -27.78 & 46.51 & 24.20 & 0.25 & [74] \\ NDD/COCO (1-1) & Mutimid® & 10 & 1 & 25 & 10.34 & 3.57 & 49.93 & 35.97 & 0.85 & [74] \\ Graphene & PS & 5 & 25 & 86.80 & -34.64 & 25.89 & 35.31 & 1.09 & [83] \\ GO & PRax & 0.25 & 5 & 35 & 84.44 & -21.92 & 13.69 & 83.00 & 1.35 & [14] \\ GO & PRax/PFC (1/1) & 0.25 & 5 & 35 & 11.98 & 10.82 & 14.02 & 84.72 & [12] & [12] \\ PEI: polyethylineine, PEG: polyethylene glycol; In: imidazole: MWCNT: multi-walled carbon nanotube; Dy: dopamine, Cy: cy cysteine; PDMS, polydimethyl:ykolome; Pebac: poly(antiplexo); PDG-PFP: poly(ethylene oxide); PDG-PFP: poly(ethylene oxide); poly(butylene methylhalate); PS: polyvoloridine; PEPEX: sulfonated poly(ether ketone); OPDG-TMPA: 4,4,4,4,4,-oxydiphthal anhydride-2,4,4,4,-trimphenylenediamine; PAN: polyvoloridine; Permeability enhancements are calculated by taking the difference between the permeability of the mixed-matrix membranes divided by the permeability of the untillled membranes and converting the values as percentages. The same method was also applied for selectivity enhancements. 1 Performance evaluated under CO\({}_{3}\)/CH\({}_{4}\) mixed gas feed of 30/70 CO\({}_{3}\)/CH\({}_{4}\). \({}^{\prime}\) Asymmetric membranes with (PCO\({}_{3}\)) reported as permeance with units of GPU. 4 Performance evaluated under CO\({}_{3}\)/CH\({}_{4}\) mixed gas feed of 69/50 CO\({}_{3}\)/CH\({}_{4}\).