Abstract
In the present study, the separation performance of new self-standing polyvinylamine (PVAm) membranes loaded with few-layer graphene (G) and graphene oxide (GO) was evaluated, in view of their use in carbon capture applications. PVAm, provided by BASF as commercial product named LupaminTM, was purified obtaining PVAm films with two degrees of purification: Low Grade (PVAm-LG) and High Grade (PVAm-HG). These two-grade purified PVAm were loaded with 3 wt% of graphene and graphene oxide to improve mechanical stability: indeed, pristine tested materials proved to be brittle when dry, while highly susceptible to swelling in humid conditions. Purification performances were assessed through FTIR-ATR spectroscopy, DSC and TGA analysis, which were carried out to characterize the pristine polymer and its nanocomposites. In addition, the membranes′ fracture surfaces were observed through SEM analysis to evaluate the degree of dispersion. Water sorption and gas permeation tests were performed at 35 °C at different relative humidity (RH), ranging from 50% to 95%. Overall, composite membranes showed improved mechanical stability at high humidity, and higher glass transition temperature (Tg) with respect to neat PVAm. Ideal CO2/N2 selectivity up to 80 was measured, paired with a CO2 permeability of 70 Barrer. The membranes’ increased mechanical stability against swelling, even at high RH, without the need of any crosslinking, represents an interesting result in view of possible further development of new types of facilitated transport composite membranes.
Highlights
In last decades, the fast economic growth of both industrialized and developing countries has brought a significant increase of global energy demand, which has been usually fulfilled by burning fossil fuels
A mid-term solution can be represented by Carbon Capture and Storage (CCS) technologies, which focus on the efficient recovery of carbon
These sheet-like graphenic nanofillers have been reported resulted being able toblocks reach for extremely high values of permeances and selectivity, beyond those to be veryingood building mixed matrix membranes able to influence permeation properties usually requested for post combustion
Summary
The fast economic growth of both industrialized and developing countries has brought a significant increase of global energy demand, which has been usually fulfilled by burning fossil fuels. In post combustion CCS, CO2 permeability and CO2 /N2 selectivity are the most critical parameters and, to reach both high-quality separation and performance above the upper bound, several approaches have been used, from the use of composite materials and mixed matrix membranes [17,18,19,20,21], ionomer and ionic liquids with high CO2 affinity [22,23,24,25], to the use of Facilitated Transport Membranes (FTMs) [26,27,28,29,30,31,32,33] The latter membranes, in particular, rely on reversible chemical reactions between the target gases and specific functional groups (carriers) embedded in the membrane’s matrix.
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