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Which solvents can separate carbon dioxide from coal combustion emissions?

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coal utilization Cross-regenerative coke oven. (A) Cross section, showing the alternating arrangement of flue walls and ovens; (B) longitudinal section, showing (left) a series of combustion flues in a single flue wall and (right) part of a long, slotlike oven.

In the context of coal utilization, post-combustion carbon capture is the primary method that utilizes chemical solvents to separate carbon dioxide ( $C O_{2}$ ) from flue gas after the fuel has been burned.12

Commonly used solvents for this process include:

Monoethanolamine: An amine-based solvent frequently employed in pollution-control equipment to selectively absorb $C O_{2}$ .1
Ammonia: Used as a solvent to facilitate the separation of $C O_{2}$ from the gas stream.1
Potash: Another chemical agent utilized in the capture process.1

During post-combustion capture, the flue gas is passed through these solvents, which selectively absorb the $C O_{2}$ . The mixture is then heated in recovery columns to separate the solvent from the $C O_{2}$ , allowing the gas to be compressed for transport or storage. While these chemical solvents are effective, the process is relatively costly due to the significant investment required for both the specialized equipment and the solvents themselves.1

It is important to note that other methods, such as oxyfuel combustion, achieve $C O_{2}$ separation through dehydration and do not require the use of solvents.1