Theme B – Carbon Capture & Release
The Programme’s second theme, comprising SPs 3 & 4 tackles the problems inherent in producing a pure stream of CO2 from the waste source to feed the recycling process. The structure of the theme has developed since the original proposal and it now has three strands. These concern: solid sorbents (WP3.1); liquid sorbents (WP 3.2, WP3.3 and SP4) and modelling (WP 3.4).
In the first two strands, we are seeking to design and test materials, both solid and liquid, which exhibit excellent capture and release of CO2. Because of literature results showing high levels of CO2 solubility, their lack of volatility and their ability to be custom designed with specific properties, much of our work has focussed around Ionic Liquids (ILs) but we are also looking at other types of sorbent. Our methodology here involves investigation of structure-CO2 capture correlation to determine optimum configurations and understanding of the response of the developed materials to gas feed impurities considering, in particular, anaerobic digester/flue gas feeds (H2O, CH4, H2S, NOx and SOx). In collaboration, SP4 investigates the use of low melting point ionic liquids, for both biogas sweetening and also for CHP exhaust gas capture. Here the emphasis is on both absorption and solvent regeneration using microbubbles to mediate the mass transfer for both the adsorption for capture and for subsequent desorption for regeneration. The use of microbubbles enables application of a novel advanced separation technique giving very high levels of mass transfer at low energy costs.
The third strand is dedicated to the theoretical investigation of ILs and their interaction with CO2, aiming to describe, understand and predict properties of the ILs including CO2 capacity. The choice of the systems is driven by the literature and the IL research described below, for example amino-acid based ionic liquids (AAIL) and super-base ionic liquids (SBIL). We will then amalgamate the knowledge gained further to adapt materials to reduce negative effects on CO2 capacity and to increase recyclability.