Post combustion capture (PCC) of carbon dioxide from power station flue gas has been identified as a key technology in reducing greenhouse gas emissions. The most developed PCC technology is chemical absorption with compounds such as monoethanolamine (MEA). PCC with MEA is associated with high capital costs and high energy requirements. It is these capital costs and high energy requirements that currently prohibit PCC as an economically feasible solution to greenhouse gas mitigation.

One approach to reducing the cost and energy requirement of carbon capture is the development of new solvents. The ideal properties of a new solvent include high carbon dioxide carrying capacity, high absorption rates, low heat of regeneration, and resistance to degradation. It is the rate that a solvent absorbs carbon dioxide that determines how large the contact area between the flue gas and the solvent needs to be. This in turn affects the capital cost of the plant.

In this study a wetted wall contactor was used to determine the absorption rates of carbon dioxide in to solutions of 5M MEA and 0.6M, 3M, 6M ammonia. The flux rates were measured and mass transfer coefficients calculated. These indicate that the absorption of carbon dioxide into 5M MEA is 2 to 10 faster than the ammonia solutions. Hence, a larger gas to liquid contact area is required for ammonia systems. Making the capital cost for an ammonia based PCC plant greater than that of an MEA plant.