The evolution of a new class of CO2 absorbents: Aromatic amines

Generally, there are numerous applications that require the separation of carbon dioxide from a mixture of gases. Pioneered in the early ninetieth century, separation techniques using aqueous amines absorbents have henceforth undergone numerous improvements in terms of heat integration and gas-liquid contactors. However, to incorporate the aforementioned improvements to realize efficient performance taking into consideration the operation in cost, changes in the absorbent formulation is inevitable. Recent studies have shown that the development of amine-based carbon dioxide absorbents is highly influenced by performance characteristics including carbon dioxide desorption energy, mass transfer rate, corrosion, high temperature, and stability. Unfortunately, great emphasize have been given to aliphatic molecules and absorbent formulation despite their challenges because they favor the performance characteristics. To this end, researchers have been looking for alternative carbon dioxide absorbents and have identified aromatic compounds a suitable candidate due to its stability and excellent chemical properties. Alternatively, the addition of amino groups has also exhibited a greater potential to enhance the performance of aromatic amines by favorably altering their properties.

In a recent paper published in the research journal, International Journal of Greenhouse Gas Control, CSIRO Energy researchers: Dr. Graeme Puxty, Will Conway, Dr. Robert Bennett, Debra Fernandes, Pauline Pearson, Dan Maher, Dr. Paul Feron together with Dr. Qi Yang from CSIRO Manufacturing investigated the feasibility of using aromatic amines as a chemical absorbent in carbon dioxide separation applications. In particular, they considered a broader definition of aromatic amines that includes amine molecules including aromatic functionality. Lastly, they assessed the properties of the aromatic amines and compared its absorption performance to that of aliphatic compounds.

In brief, the research team started by cross-examining the carbon dioxide absorption capabilities of aromatic amines. Secondly, they experimentally demonstrated the carbon dioxide affinity of aromatic amines using two aromatic amines compounds-based absorbents. On the other hand, they investigated properties of the aromatic compounds as well as their corresponding influence on the stability, biodegradability and absorption performance.

The authors observed that aromatic amine compounds could be considered as carbon dioxide absorbents. However, they were much better as compared to aliphatic compounds in terms of performance, stability, and biodegradability. This was attributed to the mobile electron systems that resulted in energy stabilization. As compared to non-aromatic amines, aromatic amines exhibited significant reduction in degradation due to improved stability. Furthermore, it was worth noting that the nitrogen atom could be added to aromatic amines to minimize the organic pollutant property as they caould biodegrade through the act of microbial systems.

In summary, the CSIRO Energy scientists presented aromatic amines as the new class of carbon dioxide absorbents taking into consideration their unique properties. In general, the study will pave the way for future investigation on the applications of these compounds. Additionally, the unique properties will enable exploration of other potential applications of amine compounds such as process designs.