Metal-organics based solvents for CO2 capture

Processes utilizing chemical absorbents (amine solvents) for post combustion CO2 capture have the drawback that temperatures above 100 degC are needed to regenerate the solvent. In the present project we study the use of metal organics based solvents for post combustion CO2 capture. The aim is to develop new solvents that can be regenerated at temperatures below 100 degC which might reduce the energy penalty caused by the capture process. So far we have shown that a metal organic solvent (MOSolv01) can reach CO2/metal organic component ratios >2. We have now developed an up-scaled preparation route of MOSolv01 which allow benchmarking the solvent against state-of-art MEA solvents. We have found that the volumetric CO2 uptake is significantly lower for 30wt% MOSolv01/water solution as compared to 30wt% MEA/water which is a consequence of the high molecular mass of the MOSolv01 complex. The lower volumetric uptake imply a larger energy penalty for the release of a certain amount of sorbed CO2 since a larger volume of solvent needs to be heated, despite the use of lower temperature of regeneration. Later experikmjents have shown that the MOSolv01 complex can act as a catalyst for CO2 sorption by MDEA solutions, however, the modest 3.4 times increase in adsorption rate is only achieved when using relatively large amounts of the MOSolv01 complex.

Alkanolamine base solvents for post combustion CO2 capture has two main drawbacks: Firstly the high energy requirement for alkanolamine regeneration, and secondly the low thermochemical stability leading to high amine consumption and subsequent waste depo sition. An alternative type of solvent based on water soluble metal-organic complexes that are able to sorb CO2 reversibly might be an attractive alternative. Initial results have shown that specific complexes can bind CO2 at ambient temperatures and that CO2 can be reversibly released already at 80 ºC. The main objective of the present project is therefore to evaluate this type of solvents further and make a real comparison with state-of art alkanolamine base technology. The research part will be carried out within the SINTEF foundation coupling metal-organic competence in the Department for Process Chemistry with the competence on the development of CO2 capture processes using alkanolamine solutions in the Department for Process Technology. Together the two groups cover the needed expertise. In addition, industry relevance will be ensured by the participation of Statoil.