A novel semi-mobile carrier facilitated transport membrane containing aniline/poly (ether-block-amide) for CO2/N2 separation: Molecular simulation and experimental study

The choice of carrier type in facilitated transport membranes has an important role in the CO2 separation performance so that the use of a suitable carrier in this field can play a key role in achieving high performance membranes. In this study, a new type of facilitated transport membrane was developed in which aniline molecules were added to the poly (ether-block-amide) (Pebax) matrix as the semi-mobile carrier. Aniline molecules played an essential role in removing the trade-off limit so that in aniline-containing membranes, permeability and selectivity were promoted simultaneously. By adding aniline carrier to the Pebax matrix, the facilitated transport mechanism was added to the solution-diffusion mechanism, resulting in a significant improvement in CO2 permeability. Based on the results of the molecular simulation, aniline molecules had a high diffusion coefficient and were able to move freely between polymer chains and so facilitate the transport of CO2 molecules through two hopping and vehicle mechanisms. In the presence of aniline, the CO2 diffusivity has increased 7.5 times compared to the neat membrane. Investigation on the mechanical properties of the membranes showed that the hydrogen bonding in the structure of the aniline contained membranes led to the improvement of Young?s modulus in these membranes. Moreover, the results of the gas permeation test showed that the optimal membrane with 50 wt% of aniline had a permeability of 151 Barrer and a selectivity of 92.5, which increased by 76% and 101%, respectively, in comparison with the neat Pebax membrane. It can be concluded that aniline can be an excellent candidate to be added to the Pebax matrix to surpass the Robeson upper bound line and reach industrial membranes with good performance.

Automated summary

The addition of aniline molecules as carriers in facilitated transport membranes can greatly improve CO2 separation performance by enhancing permeability and selectivity simultaneously. This innovative approach surpasses the Robeson upper bound line, leading to high-performance industrial membranes.