Scalable step-change carbon materials achieving high CO₂ adsorption capacity and selectivity (Flexible Funding 2018)

Chenggong Sun, Xin Liu, Hao Liu and Colin Snape, at the University of Nottingham, were awarded funding in the UKCCSRC’s Flexible Funding 2018 Call to look at “Scalable step-change carbon materials achieving high CO2 adsorption capacity and selectivity at practical flue gas temperatures for potential breakthrough cost reduction”.

Adsorption-based CO2 capture is commonly recognised for its enormous potential to achieve breakthrough cost reductions, with the use of carbon-based physical adsorbents showing the most promise due to their unparalleled properties such as fast adsorption rate, moderate heat of adsorption and superior stability against thermal, oxidative and hydrolytic degradations. However, none of the carbon materials reported so far are able to achieve appreciable CO2 capacities without flue gas deep cooling down to ambient or even lower temperatures. In the research funded by UKCCSRC, a new class of novel carbon materials able to operate with high selective CO2 capacity at realistic flue gas temperatures (greater or equal to 40^oC) has been developed from using polyisocyanurate/polyurethane as the carbon precursor.

Prepared from using a facile one-step compaction–activation methodology, the new carbon materials are highly characterised by its hierarchical three-dimensional CO2-sieving carbon architectures with strong CO2-polarising surface chemistry. Tested at realistic flue gas temperatures of 40–70^oC and a CO2 partial pressure of 0.15 bar, the best performing materials with moderate heat of adsorption (35 – 45 KJ/mol) were found to have exceedingly high reversible CO2 capacities of up to 2.30 mmol/g at 40^oC and 1.90 mmol/g at 70^oC, which represent the highest capacity ever reported at the adsorption temperatures. Advanced characterisations suggest that the unique geometry and chemistry of the carbon precursor, coupled with the characteristics of the compaction–activation protocol, are responsible for the CO2-sieving structures and capacities of the 3D carbon architectures.

Pilot tests and advanced characterisations demonstrate that the energy requirement of CO2 capture with the carbon materials in a fluidised bed or moving bed system can be reduced down to 0.93 ~ 1.06 GJ/ton-CO2, which is less than half of the energy requirement of other capture systems with advanced solvents and/or immobilised polyamine sorbents (2 – 3 GJ/ton-CO2).

Chenggong Sun, Faculty of Engineering, University of Nottingham, Nottingham, NG7 2RD
cheng-gong.sun@nottingham.ac.uk; Tel: 0115 7484577