• 0 Coal and gas fired power plants are the main contributors of CO2 emissions. CAPSOL technology offers a competitive solution for the efficient post-combustion CO2 capture. (Public Power Corporation, Agios Dimitrios Power Plant)…
  • 1 CAPSOL incorporates state-of-the-art thermodynamic property prediction and Computer Aided Molecular Design for advanced solvents and blends. (Source : Imperial College - London)…
  • 2 CAPSOL technology utilizes multi-level design and selection of validated solvent-process schemes with optimum economic and controllability features. (Papadopoulos A.I., and P. Seferlis, “A framework for solvent selection based on optimum separation process design and controllability properties”,Computer Aided Chemical Engineering, 26, 177-182, 2009.)…
  • 3 CAPSOL aims at optimum design of absorption/desorption equipment and column internals through advanced modelling and experimentation (Kenig, E.Y. (2008), Chem. Eng. Res. Des. 86, Part A, 1059–1072)…
  • 4 CAPSOL aims at sustainable CO2 capture technology through the Environmental Performance Strategy Map (De Benedetto L., Klemeš J., 2009. J. Clean. Prod., 17(10), 900-906)…
  • 5 CAPSOL targets plant level (resources) integration of CO2 emitting and capture plants through total-site and plant-wide optimization analysis (Varbanov, P., Perry, S., Klemeš J.,Smith, R., (2005), Applied Thermal Engineering, 25, 985-1001)…

CAPSOL computer aided molecular deisgn selects new highly performing solvents and solvent blends


The aim of CAPSOL is seek for new solvents and solvent blends of increased affinity towards CO2, reduced regeneration energy needs and environmentally benign characteristics. This goal has been approached through an optimization-based Computer Aided Molecular Design (CAMD) method to select post-combustion CO2 capture solvents of optimum performance in molecular and mixture properties associated with thermodynamics, kinetics and sustainability (Figure 1).

The problem is first approached in a fast screening stage where solvent structures are evaluated based on the simultaneous consideration of important pure component properties. For the first time numerous properties are considered as performance criteria reflecting solvent characteristics based on thermodynamic (e.g. vapour pressure, CO2 solubility etc.), kinetic (solvent basicity, steric hindrance etc.) and sustainability (e.g. health and safety hazard, life cycle assessment etc.) behaviour. The simultaneous consideration of properties selected to capture the molecular chemistry effects on the absorption/desorption process compensates for the initial utilization of simpler models and ensures the selection of fewer but more effective solvents.

A few highly-performing solvents are further evaluated using the SAFT-VR and SAFT-γ equations of state to predict accurately the very non-ideal solvent-water-CO2 mixture vapour-liquid equilibrium behaviour. Different functionalities of the employed CAMD method are used both to design optimum, novel molecular structures and to screen a dataset of commercially available amine solvents suitable for CO2 capture.

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Figure 1: Optimization-based Computer-Aided Molecular Design (CAMD) concept


Overall a database of 459 molecular structures was generated from the implementation of CAMD. 126 amines were found in publicly available databases or previously considered as CO2 capture solvents in absorption/desorption systems, while 333 solvents are potential novel structures. All the molecules were evaluated and rank-ordered using a performance index which unifies all the properties considered as solvent selection and design criteria. The obtained results were broken down into 4 classes (categories) of molecules based on their performance ranking.


• The 1st class considers the top 10 structures of the 25 molecules previously employed as CO2 capture solvents (Reference class).


• The 2nd class considers the top 10 molecules resulting from rank-ordering the 459 available molecules, denoted as class of Designed molecules although it also includes the 126 amines found in databases.


• The 3rd class considers only the top 10 structures of the 126 solvents found in databases, denoted as class of Commercially available molecules.


• The 4th class focuses only in the top 10 alkanolamines among the 126 molecules denoted as the Commercial Alkanolamines class.

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Figure 2: Comparative performance of 4 classes based on values averaged over the top 10 solvents.


The obtained results clearly indicate that the class of Designed molecules performs better than all other classes, while commercially available molecules exist that have yet to be considered as CO2 capture solvents and perform better than available solvents. Figure 3 shows the comparative performance of some selected solvents in properties used as performance criteria [1].

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Figure 3: Comparative performance of 2-amino-2-methyl-1-propanol (AMP), 2-(methylamino)-ethanol (MMEA), N-methyl-1,3-Propanediamine (MAPA) and Hexylamine (HEXA)


[1] A.I. Papadopoulos, S. Badr, A. Chremos, E. Forte, T. Zarogiannis, P. Seferlis, S. Papadokonstantakis, C.S. Adjiman, A. Galindo, G. Jackson, 2014, Efficient screening and selection of post-combustion CO2 capture solvents, Chemical Engineering Transactions, 39, 211-216, DOI: 10.3303/CET1439036