CO cold box - Methane wash

High-purity CO separation

The Methane Wash process utilizes cryogenic separation technology based on the difference in boiling points of synthesis gas components. The process begins by pretreating the feed gas to remove impurities that would otherwise freeze at cryogenic temperatures.

The gas is then cooled in heat exchangers and washed with liquid methane. Final purification is achieved step-by-step through a series of distillation columns to reach carbon monoxide purity levels of up to 99.99%. This proven technology is the industry standard for reliability, featuring Air Liquide's highly safe and efficient in-house CO expander.

Unmatched scale and flexibility

Our Methane Wash solutions are engineered for versatility, processing synthesis gas derived from natural gas, naphtha, or coal and residue gasification.

Designed for significant industrial demand, a single unit can achieve a production capacity of up to 34,000 Nm³/h (1,020 tonnes per day) of CO. Beyond high-purity CO, the system offers flexible co-production of hydrogen, oxogas, methane, and LNG. Every unit is tailor-made to meet specific customer requirements for co-products and discharge pressure.

The industry benchmark for CO/N₂ separation

Air Liquide is a global leader in cryogenic syngas separation. With 36 references worldwide as of 2026, our CO Cold Box – Methane Wash technology holds the greatest number of references in the industry for CO/N₂ separation, delivering safety and performance at scale.