CO2 absorption enhancement by the enzyme carbonic anhydrase
Carbon capture technology to large greenhouse gas emitter like fossil fuel burning power plants can be applied in near future and retrofitted when post combustion carbon capture (PCC) technology is used. The principles of the chemical absorption, the most mature technology in post combustion carbon capture (Rochelle), are well understood and are applied in gas treating since the early 1930s (Kohl and Nielsen). Selectively capturing carbon dioxide from flue gas streams poses though challenges to the process as the treated gas streams are very large and the driving force for the process, i.e. the partial pressure of CO2, is very low(Mumford et al.). As no valuable product is formed in this process are the costs of applying this technology based on the capital costs and operating costs. The capital costs can be reduced if the mass transfer rates are high as smaller equipment can be used for the separation. The energy requirement for the solvent regeneration is the main contributor to the overall operating costs (Svendsen, Hessen, and Mejdell), changing to a solvent with lower heat of reaction could reduce the energy input for regeneration (Kim and Svendsen). The reaction kinetics of a solvent are linked to the heat of reaction though, higher reaction kinetics comes generally with higher heat of reaction (Svendsen, Hessen, and Mejdell).
Solvents with low heat of reaction like tertiary amine or carbonate salt solutions have such low reaction kinetics and mass transfer rates that they are practically infeasible for PCC. The use of kinetic promoters that speed up the solvent reaction rates can help overcome the kinetic limitation of slow reacting solvents. These kinetic rate promoters can either be small amounts of fast reacting amines, like Piperazine (PZ), or a biocatalyst like the enzyme carbonic anhydrase (CA) that catalyzes the reversible reaction between water and CO2.
In this morning seminar I will describe you the application of carbonic anhydrase in the CCS technology and will summarize the findings I derived in my studies so far. I will also give an outline on the next steps.
References:
Kim, Inna, and Hallvard F. Svendsen. “Comparative Study of the Heats of Absorption of Post-Combustion CO2 Absorbents.” International Journal of Greenhouse Gas Control 5.3 (2011): 390–395. Web.
Kohl, Arthur, and Richard Nielsen. Gas Purification. 5th ed. Gulf Publishing Company, 1997. Print.
Mumford, Kathryn a. et al. “Review of Solvent Based Carbon-Dioxide Capture Technologies.” Frontiers of Chemical Science and Engineering 9.2 (2015): 125–141. Web.
Rochelle, Gary T. “Amine Scrubbing for CO2 Capture.” Science (New York, N.Y.) 325.5948 (2009): 1652–1654. Web.
Svendsen, Hallvard F., Erik T. Hessen, and Thor Mejdell. “Carbon Dioxide Capture by Absorption, Challenges and Possibilities.” Chemical Engineering Journal 171.3 (2011): 718–724. Web.