Cryogenic carbon capture

C&EN reports that Air Liquide is using cryogenic carbon capture to collect carbon dioxide from its hydrogen plant in Rotterdam.

Carbon dioxide is acidic and is usually captured by a high boiling amine forming a carbonate salt. Splitting the salt to recover the carbon dioxide and reuse the amine requires energy.

The hydrogen probably comes from synthesis gas, a mixture of hydrogen, carbon dioxide, and water vapor. Chilling the gas in stages (as with liquid nitrogen) probably has potential to separate the three giving carbon dioxide. When liquid nitrogen is abundant it might be practical. It will be interesting to see the economics.