Mixed Matrix Membranes for Efficient CO2 Separation Using an Engineered UiO-66 MOF in a Pebax Polymer

Abstract

Mixed matrix membranes (MMMs) have attracted significant attention for overcoming the limitations of traditional polymeric membranes for gas separation through the improvement of both permeability and selectivity. However, the development of defect-free MMMs remains challenging due to the poor compatibility of the metal–organic framework (MOF) with the polymer matrix. Thus, we report a surface-modification strategy for a MOF through grafting of a polymer with intrinsic microporosity onto the surface of UiO-66-NH2. This method allows us to engineer the MOF–polymer interface in the MMMs using Pebax as a support. The insertion of a PIM structure onto the surface of UiO-66-NH2 provides additional molecular transport channels and enhances the CO2 transport by increasing the compatibility between the polymer and fillers for efficient gas separation. As a result, MMM with 1 wt% loading of PIM-grafted-MOF (PIM-g-MOF) exhibited very promising separation performance, with CO2 permeability of 247 Barrer and CO2/N2 selectivity of 56.1, which lies on the 2008 Robeson upper bound. Moreover, this MMM has excellent anti-aging properties for up to 240 days and improved mechanical properties (yield stress of 16.08 MPa, Young’s modulus of 1.61 GPa, and 596.5% elongation at break).

Highly stable Pebax® Renew® thin-film nanocomposite membranes with metal organic framework ZIF-94 and ionic liquid [Bmim][BF4] for CO2 capture

“…28 The decrease of selectivity at high loadings can be attributed to the aggregation of particles inside the Pebax® matrix, which may create a non-ideal interface between the polymer and the ZIF crystals. 60 It is also worth mentioning that ZIF-8 particles are hydrophobic whereas Pebax® polymer is hydrophilic. This fact can also be detrimental to the gas separation performance of the membranes, since the lack of compatibility between the polymer and the filler may create voids in the polymer matrix which results in the loss of separation efficiency.…”

Gas separation improvement of PES/PSF/PVP blend mixed matrix membranes inclusive of amorphous MOFs by O2 plasma treatment

“…All of these postures could be in happening with unequal probability during performing of test and led to membrane selectivity deterioration. In addition of solution‐diffusion mechanism, there might also be some surface diffusion in which gases especially CO 2 were absorbed on the walls of MOF pores or unselective created tunnels 45 …”

“…In addition of solution-diffusion mechanism, there might also be some surface diffusion in which gases especially CO 2 were absorbed on the walls of MOF pores or unselective created tunnels. 45 After evaluation of crystalline UiO-66, the amorphous UiO-66 which was the product of 30 min ball milling at 25 Hz was used as filler. The MMM containing aUiO-66 rendered higher and lower gas permeability compared to filler free blend membrane and UiO-66 included blend membrane.…”

Recent Progress of SAPO-34 Zeolite Membranes for CO2 Separation: A Review

“…Since the first report of MMMs in 1970 [ 59 ], extensive research has been conducted to improve the separation performance and industrial implementation for a range of applications such as hydrogen recovery, treatment of natural gas, and air separation [ 60 , 61 , 62 ]. Different types of polymer matrices have been reported with various fillers, such as MOFs [ 63 , 64 , 65 , 66 , 67 ], COFs [ 68 , 69 , 70 , 71 , 72 ], carbon materials [ 73 ], zeolites [ 59 ], and other materials [ 74 , 75 ]. Zeolite materials with their sieving properties and cost-effectiveness on a large scale make them better candidates for gas separation.…”