Lingyu Liu,Qixuan Li,Luxin Sun,Aqib Riaz,Jianxin Li,Yingge Wang,Ingo Pinnau,Xiaohua Ma
One major challenge of helium recovery from natural gas by membranes is the development of materials offers both high He permeability and He/CH 4 selectivity. Here, ultrahigh performance He separation membranes were achieved by directly fluorination of a carbon molecular sieve (CMS) membrane that derived from pyrolyzing a polyimide at 550 °C. The FCMS550-60, fluorinated for 60 s, showed an unprecedented combination of high He permeability of 3432 Barrer and ultrahigh He/CH 4 selectivity of 5329 that is located far beyond any He/CH 4 trade-off lines. Additionally, it also exhibited outstanding mixed-gas separation properties with a He permeability of 1765 Barrer and He/CH 4 selectivity of 4114 at 20 bar. The largely enhanced He/CH 4 selectivity resulted exclusively from a boost in diffusion selectivity, which is originated from the formation of C–F bonds inside the micropores of the CMS membrane that remarkably enhanced the sieving ability of the FCMS membrane. This work provides a broad prospect for the application of FCMS membranes for He recovery from natural gas and other resources.
Jun Ma,Jiahe Zhang,Ye Yuan,Yunqi Zhou,Shenzhen Cong,Guangyu Xing,Jixiao Wang,Zhi Wang
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.
危险品化学品经营许可证（带存储）