Molecular simulation of carbon capture in MOFs: challenges and pitfalls – Dr Tina Düren at Cambridge Biannual

Written by Andrea de Santis, PhD student from University of Leeds, whose attendance at the Biannual Meeting was supported by the UKCCSRC ECR Meeting fund

The presentation was given by Dr Tina Düren as part of the Solid Adsorption Technical Session at the UKCCSRC Biannual in Cambridge 2-3 April 2014. Dr Düren is a Reader in Chemical Engineering at the Institute for Materials and Processes at the University of Edinburgh. Her research focuses on adsorption science and technology and in particular on the development of computational tools for the design of innovative materials for applications such as energy storage, carbon capture, and nanomedicine. 

Molecular simulation is a modelling technique which can provide information on carbon dioxide absorption at a molecular level.

In this presentation the focus was on molecular simulation of Metal Organic Framework (MOF) compounds, as they recently gained much attention for their potential in gas absorption; in particular, MOFs can be tailored for specific absorption application by choosing suitable building blocks.

Molecular simulations can be used to choose a specific structure for one application by evaluating its uptake properties.

Porous MOFs have proved to be the best choice for carbon dioxide absorption; however classical models did not shown a good agreement with experimental data for this class of materials. Porous MOFs presents challenges for classical simulations such as very strong and localised interaction and a behaviour which is halfway between physisorption and chemisorption.

For these reasons classical simulation had to be combined with quantum mechanical methods to improve the modelling and thus obtain a close agreement with experimental data.

Another challenge in the molecular simulation of absorption with MOFs is that their structure undergoes changes with CO₂ absorption, and these changes are very difficult to observe experimentally.

To summarise, molecular simulation is a very interesting tool which can provide quantitative predictions (e.g.: adsorption isotherms, diffusion coefficients) and a detailed picture of the absorption phenomena at molecular level; furthermore, this technique can be useful to evaluate absorption characteristics of different materials and thus choose the most suitable for one specific application. On the other hand, care needs to be taken when using this technique: the structure of the absorbent material must be known, the simulation of flexible structure is computationally expensive and even rigid absorbents can show some degree of flexibility.