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AIChE JOURNAL Highlight
The capture of C02 from flue- and fuel-gas streams in large-scale power generation offers a compelling means to combat climate change. Technically plausible strategies for C02 capture include post-combustion carbon capture (PCC), oxy-combustion, and pre-combustion carbon capture (PrCC) - all of which present gas separation challenges. PCC in conventional power plants requires separating C02 from N2, as air is used for combustion. Oxycombustion, on the other hand, uses 02 instead of air for combustion and thus produces a pure stream of C02; the only significant separation challenge for oxy-combustion relates to the production of pure 02 before fuel combustion. In PrCC in integrated gasification combined cycle (IGCC) power plants, C02 must be separated from H2 following the gasification and water-gas-shift (WGS) reaction steps.
Three separation methods are being considered for these applications: membrane separation, adsorption, and solvent absorption. Detailed techno-economic studies have found that state-of-the-art absorption technologies based on amines or physical solvents are too expensive for practical use. Adsorption processes also suffer from high energy consumption, although not as high as for absorption. That leaves membranes, in particular C02-selective membranes, which is the topic of the April AIChE...