Multiwalled carbon nanotube mixed matrix membranes containing amines for high pressure CO2/H2 separation

CO2-selective mixed matrix membranes capable of facilitated transport were synthesized for CO2/H2 separation at high pressures of at least 1.52 MPa and high temperatures above 373.15 K. A significant improvement in membrane stability was achieved by thoroughly dispersing multiwalled carbon nanotubes (MWNTs) as mechanical reinforcing fillers in a polyvinylalcohol matrix containing amines. With 2 wt% MWNTs incorporated, the membrane performance, including a CO2/H2 selectivity of 43 and a CO2 permeability of 836 Barrers (1 Barrer = 7.5×10−11 cm3(STP) cm/(cm2 s kPa)), showed no change for 444 h (18.5 days) when operated at 1.52 MPa and 380.15 K. At the same conditions, the membrane containing 4 wt% acid-treated MWNTs also showed good stability. The membranes synthesized in this work are the first of this kind, displaying exceptional CO2/H2 separation performance and high tolerance to feed gas at high pressures and high temperatures. Potentially, they could be used in a stand-alone membrane unit for energy-efficient precombustion carbon capture from coal-derived syngas or in conjunction with water-gas-shift reaction for CO clean-up to produce high-purity H2 for fuel cells and to simultaneously capture CO2.