Solid acid catalysts for low-temperature regeneration of non-aqueous sorbents: An innovative technique for energy-efficient CO2 capture processes

Abstract

Chemical absorption of CO2 from flue gases by using aqueous amine sorbents is regarded as the most mature and effective technology for reducing CO2 emissions, but the high energy cost of sorbent regeneration has so far greatly limited its industrial application. One of the best strategies developed by researchers in recent years to reduce energy requirements is to improve CO2 desorption kinetics by adding catalysts during sorbent regeneration. Moreover, non-aqueous sorbents have recently been gaining increasing attention as alternatives to conventional aqueous amines as they have the potential to lower the energy demand for sorbent regeneration. In this paper, we propose an innovative technique that combines and further develops these two emerging technologies, non-aqueous absorbent and catalyst-assisted regeneration, to enable less energy-intensive CO2 capture processes. In particular, in this screening study, we evaluate the regeneration behaviour of a CO2-saturated solution of 2-(2-aminoethoxy)ethanol (DGA) in diethylene glycol monomethyl ether (DEGMME) when heated to 85 °C in the absence and presence of different types of solid acid catalysts. In order to assess the potential benefits of this innovative technique over conventional systems, the results obtained were compared with the desorption performance of an aqueous solution of DGA under the same operating conditions and with the same catalysts, which highlighted the possibility of obtaining rapid desorption at relatively low temperatures when conducted with suitable acid catalysts using amines in organic diluents.

Keywords

• CO2 capture
• Non-aqueous sorbent
• Catalytic regeneration
• 13C NMR speciation
• 2-(2-aminoethoxy)ethanol