Biomass conversion is a rising alternative to substitute fuels, chemicals and other products currently obtained from fossil sources. However, biomass conversion technologies such as pyrolysis suffer from low carbon-to-fuel efficiency (38-47%), with the remainder of the carbon ultimately ending up forming CO₂ and resulting in biogenic green-house gas (GHG) emissions [1]. An alternative to decrease the CO₂ emission from biomass conversion, and contribute to the sustainability of the biomass processing, is the capture and conversion of CO₂ to beneficial products such as chemicals and fuels via renewable electricity.

Aqueous electrochemical reduction of CO₂ has been of growing interest as a solution for GHG mitigation and due to the high diversity of products that can be selectively obtained depending on the electrocatalyst used (e.g. alcohols, hydrocarbons, CO etc.) [2]. However, three main technical problems have been identified for the process feasibility: 1) low solubility of CO₂ in aqueous media hinders mass transport, 2) high reaction overpotentials, and 3) obtaining a quality concentrated CO₂ feedstock [3,4]

In this work, switchable polarity solvents (SPS) are used to capture and increase the CO₂ concentration in aqueous media. SPS are emerging as an extremely versatile class of materials which shift polarity and solubility upon being exposed to a chemical agent, namely CO₂ with water [5]. Insoluble tertiary amines react with CO₂ to form soluble ions [HNR₃⁺] and bicarbonate [6]. Hence, an ion exchange membrane assembly can be used to generate a localized acidic environment on the surface of the cathode electro-catalyst releasing CO₂ for reduction.

Results of electrochemical analysis performed on metal supported catalysts will be presented

 

 

References

[1] A.P. Borole, Sustainable and efficient pathways for bioenergy recovery from low-value process streams via bioelectrochemical systems in biorefineries, Sustainability, 7 (2015) 11713-11726.

[2] M. Gattrell, N. Gupta, A. Co, A review of the aqueous electrochemical reduction of CO₂ to hydrocarbons at copper, Journal of Electroanalytical Chemistry, 594 (2006) 1-19.

[3] S. Ma, P.J. Kenis, Electrochemical conversion of CO₂ to useful chemicals: current status, remaining challenges, and future opportunities, Current Opinion in Chemical Engineering, 2 (2013) 191-199.

[4] J. Durst, A. Rudnev, A. Dutta, Y. Fu, J. Herranz, V. Kaliginedi, A. Kuzume, A.A. Permyakova, Y. Paratcha, P. Broekmann, T.J. Schmidt, Electrochemical CO₂ Reduction – A Critical View on Fundamentals, Materials and Applications, CHIMIA International Journal for Chemistry, 69 (2015) 769-776.

[5] P.G. Jessop, S.M. Mercer, D.J. Heldebrant, CO₂-triggered switchable solvents, surfactants, and other materials, Energy & Environmental Science, 5 (2012) 7240-7253.

[6] B. Lv, B. Guo, Z. Zhou, G. Jing, Mechanisms of CO₂ Capture into Monoethanolamine Solution with Different CO₂ Loading during the Absorption/Desorption Processes, Environ. Sci. Technol., 49 (2015) 10728-10735.