Ultra-thin enzymatic liquid membrane for CO₂ separation and capture.

Abstract

The limited flux and selectivities of current carbon dioxide membranes and the high costs associated with conventional absorption-based CO₂ sequestration call for alternative CO₂ separation approaches. Here we describe an enzymatically active, ultra-thin, biomimetic membrane enabling CO₂ capture and separation under ambient pressure and temperature conditions. The membrane comprises a ~18-nm-thick close-packed array of 8 nm diameter hydrophilic pores that stabilize water by capillary condensation and precisely accommodate the metalloenzyme carbonic anhydrase (CA). CA catalyzes the rapid interconversion of CO₂ and water into carbonic acid. By minimizing diffusional constraints, stabilizing and concentrating CA within the nanopore array to a concentration 10× greater than achievable in solution, our enzymatic liquid membrane separates CO₂ at room temperature and atmospheric pressure at a rate of 2600 GPU with CO₂/N₂ and CO₂/H₂ selectivities as high as 788 and 1500, respectively, the highest combined flux and selectivity yet reported for ambient condition operation.