Carbon molecular sieve (CMS) membranes are considered game-changers to overcome the challenges that conventional polymeric membranes face. However, CMS membranes also confront a challenge in successfully separating extremely similar-sized molecules. In this article, high-precision tuning of the microstructure of CMS membranes is proposed by controlled electron irradiation for the separation of molecules with size differences less than 0.05 nm. Fitting CMS membranes for targeted molecular separation can be accomplished by irradiation dosage control, resulting in highly-efficient C2H4/C2H6 separation for low dosages (∼250kGy, with selectivity ∼14) and ultra-selective H2/CO2 separation for high dosages (1000∼2000kGy with selectivity ∼80).The electron irradiated CMS also exhibits highly stabilized permeability and selectivity for long-term operation than the pristine CMS, which suffers from significant performance degradation due to physical aging. This study successfully demonstrates electron irradiation as a possible way to construct “designer” nanoporous carbon membranes out of the standard components mostly confined to pyrolysis conditions.

Liquid-phase chemical separations from complex mixtures of hydrocarbon molecules into singular components are large-scale and energy-intensive processes. Membranes with molecular specificity that efficiently separate molecules of similar size and shape can avoid phase changes, thereby reducing the energy intensity of the process. Here, forward osmosis molecular differentiation of hexane isomers through a combination of sizeand shape-based separation of molecules is demonstrated. An ultramicroporous carbon membrane produced with 6FDA-polyimides realized the separation of isomers for different shapes of di-branched, mono-branched, and linear molecules. The draw solvents provide the driving force for fractionation of hexane isomers with a sub-0.1 nm size difference at room temperature without liquid-phase pressurization. Such membranes could perform bulk chemical separations of organic liquids to achieve major reductions in the energy intensity of the separation processes.

Polymeric membranes may lower the energy requirement for oil refineries

Organic Solvent Forward Osmosis In article number 2004999, Hyeokjun Seo, Dong‐Yeun Koh, and co‐workers introduce a new concept in separation science that accomplishes energy‐efficient separation of similarly sized organic liquid molecules using ultramicroporous carbon membranes. In the article, the organic solvent forward osmosis (OSFO) is demonstrated to differentiate complex organic liquid mixture composed of hexane isomers using ‘shape selectivity’ within ultramicropores of the carbon membranes.

A successful changeover to a future energy system that does not add extra CO2 to the atmosphere, a net-zero emission energy system, is likely to depend on a combination of known technologies enabled by scalable and modular devices. In this article, we discuss prominent technological opportunities and barriers for an integrated approach to carbon capture and utilization (CCU) that can simultaneously exploit both CO2 and industrial wastes. We show that a hollow fiber module based on an ultrapermeable membrane synthesized with the polymers of intrinsic microporosity (PIM-1) has the potential to directly utilize CO2 from the flue gas stack via a continuous solid carbonation reaction. By a quantitative comparative assessment of the continuous PIM-1 module performance for different testing conditions, feasible routes for large-scale CO2 utilization are proposed. We also identified surmountable hurdles in our approaches, such as membrane stability and possible scale formation. An integrated approach of two parallel research streams, CO2 capture and utilization, could provide reliable and cost-effective strategies for large-scale CCU.