The EU integrated strategic energy technology plan, SET-plan, in its 2016 progress report, has called for urgent measures on the carbon capture and storage (CCS). There are only 3 commercial (0.5-1 million tonnes CO2/year) CCS projects in Europe, all commissioned in offshore Norway for natural gas sweetening. Currently, the amine-based CO2 scrubbing is employed to capture CO2, leading to a high energy penalty (2.5–4.0 MJ/kg of captured CO2)2 attributing to thermal regeneration of the saturated amine stream. Moreover, the scrubbing technology suffers from the oxidative degradation of amines, and is not environmentally friendly due to loss of amines during the regeneration step. In comparison, the use of a high-performance membranes, defined as chemically and thermally stable films yielding a high gas permeance and selectivity, is environmentally friendly (no chemical is used, no waste is generated) and energy-efficient, and can reduce the energy-penalty for the carbon capture to less than 2 MJ/kg of CO2. Moreover, upon optimization, membranes modules can be installed in a decentralized fashion to a broad-range of emission sources (e.g. biogas plants, waste incinerators, residential and commercial heating, etc.).
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.
