Thermally stable cross-linked P84 with superior membrane H2/CO2 separation properties at 100 °C

Abstract

Polymers with a strong size-sieving ability and superior H2/CO2 selectivity are of great interests for pre-combustion CO capture at 100 °C or above. Polyimides (such as Matrimid® and 6FDA-durene) have been cross-linked using diamines and show superior H2/CO2 selectivity. However, these cross-linked polymers cannot be used for the pre-combustion CO2 capture because of the lack of thermal stability at 100 C. Herein we demonstrate that commercial P84™ can be chemically cross-linked using 1,4-butanediamine (BuDA) to achieve robust H2/CO2 separation properties at 100 °C to 150 °C. The cross-linked P84 were thoroughly evaluated using Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA). The effects of the cross-linking time on the physical properties and H2/CO2 separation properties at various temperatures were determined and interpreted using a free volume model. An exemplary sample based on P84 crosslinked by BuDA for 6 h exhibits a H2 permeability of 47 Barrers (1 Barrer = 3.35 × 10−16 mol m/m2·s·Pa) and H2/CO2 selectivity of 14 at 100 °C, which is on the Robeson’s upper bound, indicating their potential for practical applications.

Surface Modification of Matrimid® 5218 Polyimide Membrane with Fluorine-Containing Diamines for Efficient Gas Separation

“…Figure 2 represents possible reaction mechanisms between polyimide chains and diamine molecules [ 37 ]. The imide ring on the backbone of the polyimide is easily opened by contact with diamines because of their strong nucleophilicity toward carbonyl groups [ 11 ].…”

Polyoctahedral Silsesquioxane Hexachlorocyclotriphosphazene Membranes for Hot Gas Separation

“…The decrease in the permeance with an increasing kinetic diameter of the permeant is similar to the typical behavior observed for membranes consisting of glassy polymers. 27 , 28 It implies that the gas molecules are permeating through a rigid molecular environment in which slightly smaller molecules have a much higher mobility (diffusion coefficient) as compared to slightly larger molecules. In contrast, for elastomers, generally the diffusion coefficient of permeants changes moderately with their size, and the permeation of larger molecules is actually larger due to their higher solubility.…”

Molecularly engineering polymeric membranes for H2/CO2 separation at 100–300 °C

“…[60][61][62]70,71] Interestingly, when P84™ (a polyimide) was cross-linked with 1,4-butylene diamine (BuDA), the samples were stable up to 150 C and showed H 2 permeability of 47 Barrer and H 2 /CO 2 selectivity of 14 at 100 C, which is on the Robeson's upper bound. [72] The cross-linking of the polyimides was often performed with thick films (50 μm), and the reaction only occurred on the surface and not evenly in bulk (as indicated by the low gel content in the cross-linked samples). [52,62,66,68] Therefore, S C H E M E 1 Schematic illustrations of m-PBI cross-linked with (a) terephthaloyl chloride and (b) phosphoric acid, and (c) 6FDAdurene cross-linked with diamines.…”

“…[ 60–62,70,71 ] Interestingly, when P84™ (a polyimide) was cross‐linked with 1,4‐butylene diamine (BuDA), the samples were stable up to 150 °C and showed H 2 permeability of 47 Barrer and H 2 /CO 2 selectivity of 14 at 100 °C, which is on the Robeson's upper bound. [ 72 ]…”