Poly(ether- block -amide) copolymer membrane for CO ₂ /N ₂ separation: the influence of the casting solution concentration on its morphology, thermal properties and gas separation performance

Abstract

The present work is focused on the study of the effect that the casting solution concentration has on the morphology and gas separation performance of poly(ether- block -amide) copolymer membranes (Pebax ® MH 1657). With this aim, three different concentrations of Pebax ® MH 1657 in the casting solution (1, 3 and 5 wt%) were used to prepare dense membranes with a thickness of 40 µm. The morphology and thermal stability of all membranes were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, rotational viscometry and thermogravimetric analyses. An increase in crystallinity was notable when the amount of solvent in the Pebax ® MH 1657 solution was higher, mainly related to the polymer chains arrangement and the solvent evaporation time. Such characteristic seemed to play a key role in the thermal degradation of the membranes, confirming that the most crystalline materials tend to be thermally more stable than those with lower crystallinity. To study the influence of their morphology and operating temperature on the CO 2 separation, gas separation tests were conducted with the gas mixture CO 2 /N 2 . Results indicated that a compromise must be found between the amount of solvent used to prepare the membranes and the crystallinity, in order to reach the best gas separation performance. In this study, the best performance was achieved with the membrane prepared from a 3 wt% casting solution, reaching at 35°C and under a feed pressure of 3 bar, a CO 2 permeability of 110 Barrer and a CO 2 /N 2 selectivity of 36.

Synthesis of ZIF‐94 from Recycled Mother Liquors: Study of the Influence of Its Loading on Postcombustion CO2 Capture with Pebax Based Mixed Matrix Membranes

“…Moving to 9 wt% Pebax MH 1657, it was found that selectivity this bare membrane decreased significantly compared to 6 wt% bare membrane (see Figure 7 and Table 4). This trend is also reported by Martínez-Izquierdo et al [31] The highest CO 2 / N 2 selectivity of 36 ± 7 and the permeability of 137 ± 31 Barrer were obtained for 9 wt% Pebax MH 1657 based MMMs and 10 wt% loading of ZIF-94 (1). Comparison with bare membrane indicates that 10 wt% ZIF-94 (1) dose in the MMM increases selectivity and permeability by 71% and 80%, respectively.…”

“…The MMMs were prepared following a two-step process. [31] First, 6 and 9 wt% Pebax MH 1657 (of total weight of 3 g (polymer + solvent)) was dissolved in EtOH/ water (70/30 (v/v)) by stirring under reflux for 1 h. Afterward, the dissolved polymer was used to cast bare polymeric membranes. In case of MMMs fabrication process, ZIF-94 was dispersed in the dissolved polymer.…”

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

“…The results indicate that the developed MMMs could be a potential candidate for CO 2 separation applications. The separation performance of CO 2 /N 2 lies on the 2008 upper bound and is better than that of pristine Pebax [44,[50][51][52], various Pebax-based MMMs [46,50,[52][53][54][55][56], and commercial polymers, including CA [57,58], Matrimid [18,59], etc.…”

Pebax® 1041 supported membranes with carbon nanotubes prepared via phase inversion for CO2/N2 separation

“…6 Our research group published recently the influence of the casting solution concentration in the preparation of Pebax ® 1657 membranes, showing a gas separation performance of 100 Barrer of CO2 with a CO2/N2 selectivity of 35. 7 Khosravi et. al.…”