Energy-Efficient membranes for carbon capture by crystal engineering of two-dimensional nanoporous materials
The EU integrated strategic energy technology plan, SET-plan, in its 2016 progress report, has called for urgent measures on the carbon capture, however, the high energy-penalty and environmental issues related to the conventional capture process (amine-based scrubbing) has been a major bottleneck. High-performance membranes can reduce the energy penalty for the capture, are environment-friendly (no chemical is used, no waste is generated), can intensify chemical processes, and can be employed for the capture in a decentralized fashion. However, a technological breakthrough is needed to realize such chemically and thermally stable, high-performance membranes. This project seeks to develop the ultimate high-performance membranes for H2/CO2 (pre-combustion capture), CO2/N2 (post-combustion capture), and CO2/CH4 separations (natural gas sweetening). Based on calculations, these membranes will yield a gigantic gas permeance (1 and 0.1 million GPU for the H2 and the CO2 selective membranes, respectively), 1000 and 10-fold higher than that of the state-of-the-art polymeric and nanoporous membranes, respectively, reducing capital expenditure per unit performance and the needed membrane area. For this, we introduce three novel concepts, combining the top-down and the bottom-up crystal engineering approaches to develop size-selective, chemically and thermally stable, nanoporous two-dimensional membranes. First, exfoliated nanoporous 2d nanosheets will be stitched in-plane to synthesize the truly-2d membranes. Second, metal-organic frameworks will be confined across a nanoporous 2d matrix to prepare a composite 2d membrane. Third, atom-thick graphene films with tunable, uniform and size-selective nanopores will be crystallized using a novel thermodynamic equilibrium between the lattice growth and etching. Overall, the innovative concepts developed here will open up several frontiers on the synthesis of high-performance membranes for a wide-range of separation processes.