Rules to Select Solvents for Scrubbing CO2 from Fossil Power Stations

The present amine-based technology scrubbs CO2 from flue gas by a chemical equilibrium reaction. Some disadvantages are obvious:

1. the recovery of the CO2-rich solution requires so much energy that the electrical output is reduced by 25-35 %

2. Amines are harmful to the environment and should be removed from the flue gas

3. Some amines form irreversible products

The focus of this lecture is to show how a thermodynamical analysis will lead to more economical solvents.

It turns out that the following properties are advantageous:

1. “no” vapour pressure

2. molecular weight around some few thousand Dalton

3. low viscosity