Artículo

Carbon molecular sieve (CMS), as the gas separation membrane materials, still faces challenges for regulation pore diameter precisely. In this work, we propose to reconstruct the 6FDA-DAM-Br-85% polyimide CMS membranes by introducing 6,6'-(1,4-phenylenebis(((4-hydroxyphenyl)amino)methylene))bis(dibenzo[c,e][1,2] oxaphosphinine6-oxide) small molecule compound (DOPO-p-DP) as crosslinking agent to regulate the pore distribution. The crosslinked precursors were obtained via the reaction between C-Br bond in 6FDA-DAM-Br-85% polyimide and N-H bond in DOPO-p-DP compound, the precursors and CMS membranes (550 °C- 2 h) were characterized with ATR-TFIR, XRD and XPS. The pore size distribution of crosslinked CMS membranes was range in 4.5-8.0 Å from the N2 adsorption data. The crosslinked CMS membranes exhibited excellent gas separation performance, which was strongly dependent on the mass fraction of DOPO-p-DP, an increasing mass fraction of DOPO-p-DP leaded to improve in gas selectivity, while reduced its permeability. The 6FDA-DAM-Br-85%/DOPO-p-DP-20% CMS membrane showed the impressive permeability and superior gas selectivity, the permeabilities of O2, CO2, and H2 are 798, 3018, and 13560 Barrer combined with the O2/N2, CO2/CH4, and H2/CH4 selectivities of 7.8, 65.6, and 294.8 respectively, the separation performances surpassed the latest trade-off relationship. In addition, the 20% of the DOPO-p-DP crosslinked CMS membrane revealed the superior aging behaviour than that of the 6FDA-DAM-Br-85% CMS membrane over 480 h aging under vacuum conditions.