Novel Cellulose Triacetate (CTA)/Cellulose Diacetate (CDA) Blend Membranes Enhanced by Amine Functionalized ZIF-8 for CO2 Separation

Abstract

Currently, cellulose acetate (CA) membranes dominate membrane-based CO2 separation for natural gas purification due to their economical and green nature. However, their lower CO2 permeability and ease of plasticization are the drawbacks. To overcome these weaknesses, we have developed high-performance mixed matrix membranes (MMMs) consisting of cellulose triacetate (CTA), cellulose diacetate (CDA), and amine functionalized zeolitic imidazolate frameworks (NH2-ZIF-8) for CO2 separation. The NH2-ZIF-8 was chosen as a filler because (1) its pore size is between the kinetic diameters of CO2 and CH4 and (2) the NH2 groups attached on the surface of NH2-ZIF-8 have good affinity with CO2 molecules. The incorporation of NH2-ZIF-8 in the CTA/CDA blend matrix improved both the gas separation performance and plasticization resistance. The optimized membrane containing 15 wt.% of NH2-ZIF-8 had a CO2 permeability of 11.33 Barrer at 35 °C under the trans-membrane pressure of 5 bar. This is 2-fold higher than the pristine membrane, while showing a superior CO2/CH4 selectivity of 33. In addition, the former had 106% higher CO2 plasticization resistance of up to about 21 bar and an impressive mixed gas CO2/CH4 selectivity of about 40. Therefore, the newly fabricated MMMs based on the CTA/CDA blend may have great potential for CO2 separation in the natural gas industry.

Fabrication and testing of mixed matrix membranes of UiO‐66‐NH2 in cellulose acetate for CO2 separation from model biogas

“…Meanwhile, CA-based MMMs with CO 2 /CH 4 separation performance reported in the literature also failed to surpass. They were far below the upper bound limit, [45][46][47][48] except one with Mubashir and co-workers, 14 which touched the Robeson's upper bound 1991 for pure gas separation. Though the UiO-66-NH 2 /CA MMMs fabricated are not crossing the Robeson upper bound, the gas separation performance in CO 2 permeability and CO 2 /CH 4 selectivity is better optimized than pure CA membranes.…”

Covalent and non-covalent approaches to suppress plasticization of polymer membranes for gas separation

“…The intermolecular interaction between the two polymers increases the packing of the matrix polymer chains, which slightly decreases the CO 2 permeability, but the CO 2 /N 2 selectivity tends to increase as the Rhodeftal content increases. 51 An MMM prepared by adding 30 wt% SNW-3, a Schiff-based network, to a polysulfone matrix has been reported to exhibit lower plasticization. Polysulfone has excellent mechanical properties, high chemical stability, and high plasticization resistance, and SNW-3 has a very high CO 2 capture capacity so, when used as a mixed film, SNW-3 can stiffen the surrounding polymer chains and improve their plasticization resistance.…”

“…The intermolecular interaction between the two polymers increases the packing of the matrix polymer chains, which slightly decreases the CO 2 permeability, but the CO 2 /N 2 selectivity tends to increase as the Rhodeftal content increases. 51…”

Development of Amine-Functionalized Metal-Organic Frameworks Hollow Fiber Mixed Matrix Membranes for CO2 and CH4 Separation: A Review

“… Schematic diagram of MOFs: ( a ) UiO-66 and NH 2 -UiO-66, ( b ) ZIF-8 and NH 2 -ZIF-8, ( c ) MIL-101 and NH 2 -MIL-101 [ 74 , 75 , 76 , 77 , 78 ]. …”