Carbon nanotube reinforced PVAm/PVA blend FSC nanocomposite membrane for CO2/CH4 separation

• A blended PVAm/PVA membrane reinforced with carbon nanotubes was successfully prepared.
• A selectivity of CO2/CH4 up to 45 was documented in the low pressure range (2–5 bar).
• A CO2 permeance of up to 0.35 m3 (STP)/m2 h bar was documented in this range.
• The addition of CNTs (1.0 wt.%), provided good durability against compaction at elevated pressures.

A carbon nanotube (CNT) reinforced polyvinyl amine/polyvinyl alcohol (PVAm/PVA) blend nanocomposite membrane with facilitated transport fixed-site-carriers (FSC) for CO2/CH4 separation was developed with the focus on improving membrane separation performance at elevated pressures and the challenges related to the up-scaling of the membrane for potential industrial applications. This nanocomposite membrane was prepared by dip-coating with the modified CNTs dispersed uniformly in a hydrophilic PVAm/PVA blended solution with a precise control of the coating layer thickness (coating layer thickness 0.5–2.5 μm). Membranes with an up-scaled size (300 × 300 mm) were prepared. A selectivity of CO2/CH4 up to 45 and a CO2 permeance of up to 0.35 m3 (STP)/m2 h bar were documented in the low pressure range (2–5 bar). With the addition of a small amount of CNTs (1.0 wt.%), the membrane showed an enhanced water swelling, capacity as well as good durability against the compaction effect in operations at elevated pressures. The CO2 permeance of the CNTs reinforced nanocomposite membranes improved significantly compared to its counterpart membrane without CNTs, while the CO2/CH4 selectivity remained similar. The effects of increased pressure (up to 15 bar) on membrane separation performance were investigated in the same way. The SEM images of the nanocomposite membrane confirmed that the CNTs and PVAm/PVA blend polymer were compatible.