Description
(project abstract) This project aims at understanding the dehydroxylation behaviour of the Metal-Organic Framework UiO-66 (Zirconium terephthalate), with structural formula Zr6O4(OH)4[terephthalate]6. When placed in vacuum at high temperatures, this material loses its hydroxyl (OH) groups. During this dehydroxylation process water is removed from the framework. It is highly important to investigate dehydroxylation processes, as these lead to more catalytically active UiO-66 type materials.
In this project, we want to elaborate on our previous Tier1-project (Structural transformations during dehydroxylation reactions of UiO-66 type metal-organic frameworks), where we computed minimum energy pathways for a variety of dehydroxylation reactions using climbing image Nudged-Elastic Band (cNEB) simulations. More specifically, we would like to refine this approach and further optimize the local minima and transition states along the obtained minimum energy pathways. Therefore, these optimized structures will be submitted to a normal mode calculation (or frequency calculation), to yield both the frequencies and the elastic tensor. With these properties of the various states, we can compute free energy differences and see how the material stability changes along the reaction path. Accounting for the elastic tensor in the partition function of the structures will also enable us to see these more subtle effects in the free energy profile.
The obtained insight into the active sites after such a dehydroxylation treatment and their energetic relevance is highly relevant for the Zr-MOF community, and can then be used for further computational studies.
