HOF-21 nanofillers incorporated mixed matrix membranes for high-performance N2/CH4 separation

N 2 /CH 4 separation membranes based on N 2 preferential permeation can effectively reduce the recompression cost of CH 4 gas and show promising application prospects in the field of natural gas purification. However, the performance of N 2 /CH 4 separation membranes still needs to be improved. Here, we report a kind of mixed matrix membranes (MMMs) for N 2 /CH 4 separation via using HOF-21 as nanofiller and 6FDA-DAM polyimide as polymer matrix . In this work, the effects of HOF-21 loading, feed side pressure and temperature based on membrane performance were explored, and finally performance variation of the MMMs with operation time was tested. The incorporated HOF-21 nanoparticles with the most probable pore size of about 3.6 Å can significantly increase the diffusion rate of smaller N 2 molecules and enhance the N 2 /CH 4 diffusivity selectivity of the membrane. In addition, compared with polyimide, HOF-21 exhibits almost the same dynamic adsorption of N 2 and CH 4 , which can weaken the solubility of CH 4 and enhance the N 2 /CH 4 solubility selectivity of the membrane. When feed gas pressure was 0.2 MPa, the optimum membrane performance was achieved at the HOF-21 loading of 7 wt%, with N 2 permeance of 5.13 GPU and N 2 /CH 4 (50/50, vol%) selectivity of 20.52 at 298.15 K. Compared with N 2 permeation and N 2 /CH 4 selectivity of the 6FDA-DAM/PAN membrane, the MMMs increased by 67% and 54%, respectively, possessing potential applications in the field of N 2 removal in CH 4 purification.