Understanding the impact of industrial gas streams on CO2 capture solvent performance

Carbon capture and storage will play a key role in achieving the IPCC goal to limit climate change to below 2 C. There are many large scale point source emitters of CO2 where it can be captured, including power stations (fuelled by gas, coal, and biomass), industrial manufacturing (iron and steel, cement), hydrogen production (via steam methane reforming), natural gas sweetening and biogas upgrading.
Although there are numerous different approaches to CO2 capture, the use of chemical solvents is the most developed. However there are numerous drawbacks to the technology used, including chemical hazards (toxicity and emissions), energy performance, and material of construction compatibility.
C-Capture has developed technology which uses approximately half the energy of current commercial technologies for the CO2 separation process, and utilises chemicals which are inexpensive, readily available, and much more environmentally benign than current solvents. The proposed project is designed to understand some of the key fundamental aspects of solvent performance which is of relevance to solvent based CO2 separation, which may help C-Capture develop improved processes in the future.
The current objectives of the research are as follows:
1. To prepare a range of solvents which have the capability to physically and/or chemically absorb CO2 at atmospheric pressure or higher pressure.
2. To measure and potentially rationalise key structural features which affect solubility of CO2 in the new solvents.
3. To understand potential solvent degradation mechanisms and how these may impact on the performance of a solvent.
The project will begin with synthesis of some new chemical solvents, using synthetic organic chemistry techniques. These will be related to known solvents, and particular structural features for investigation include the nature of any heteroatoms present (e.g. N, O, S), any electronic and steric affects which may influence solubility and reactivity, and how this may be relevant to deployment in a real process situation.
The potential of the solvents for dissolving CO2 will be measured at a variety of temperatures and pressures using vapour-liquid equilibria equipment, and compared with that of existing solvents. This will be used to determine how the chemical structure of the solvent influences its ability to dissolve CO2, particularly its relationship with temperature and pressure. Initially this will be empirical, but computational modelling may also be feasible depending on significance of results and progress.
As key solvents are identified, they will be studied in more detail, particularly with regard to chemical stability (thermal and oxidative), using accelerated ageing techniques in the presence of oxygen and/or CO2. The effect of degradation on CO2 solubility, and hence capture performance, will be investigated. In addition, any degradation products will be identified and attempts will be made to understand their origin. In PhD work by another student (unpublished, now writing up), we have recently used such techniques to investigate amine degradation, and have identified one new major degradation product from MEA that is previously unreported.
These learnings will then be applied to real commercial systems, through collaboration with C-Capture. For example, C-Capture currently have a solvent contactor unit currently on location at Drax power station, which has the capability to continuously expose solvents to biomass flue gas for extended periods of time. Samples prepared using this method can be compared with those from accelerated ageing to determine effectiveness of the method.
This project will also involve working with an innovative SME, commercialising research that originated from the University, which has the potential to have enormous impact around the world, with major opportunity for wealth creation for the UK.