Katarína Stančiaková

PhD Candidate

Employed since: September 2015
E-mail: k.stanciakova@uu.nl
Room: 4th   floor study area

Acidic Water in Zeolite Pores: Multi-scale Modelling of Water-Active Site Interactions

Due to their shape selectivity and acidity, zeolites are widely used as catalyst in petrochemical or oil refining processes such as fluid catalytic cracking or aromatization.  However, they are sensitive to steaming and hot liquid water, which can lead to modification of their structure with subsequent decrease in their catalytic activity [1]. Despite a considerable empirical knowledge regarding the optimization of the zeolite synthesis was achieved over the past years [2], the mechanism of the underlying reactions is still unknown.

In our study we would like to systematically address the problem of zeolite degradation upon attack of water molecules by usage of molecular simulations. The ultimate goal is to develop a more stable and water resistant catalyst.  At the first part of our work we will study the reactivity of water on various T sites of zeolite ZSM-5 by means of periodic density functional theory (DFT) as well as by classical molecular dynamics simulations (MD) and adaptive QM/MM methods [3]. In the second part of our work we will explore the attachment of water droplets on zeolite surfaces with different shapes and Si/Al ratio.

Such an exhaustive study should provide us the information about the structure, location as well as dynamics of water molecules inside the zeolites as well as on their surfaces. It would also help us to understand the mechanism of the water attack at atomistic level.

[1] Zhang, L., Chen, K., Chen, B., White, J. L., Resasco, D. E. Factors that Determine Zeolite Stability in Hot Liquid Water (2015) Journal of the American Chemical Society, 137 (36), pp. 11810-11819.
[2]  Van Der Bij, H.E., Meirer, F., Kalirai, S., Wang, J., Weckhuysen, B.M.Hexane cracking over steamed phosphated zeolite H-ZSM-5: Promotional effect on catalyst performance and stability (2014) Chemistry - A European Journal, 20 (51), pp. 16922-16932.
[3]  Bulo, R.E., Ensing, B., Sikkema, J., Visscher, L. Toward a practical method for adaptive QM/MM simulations (2009) Journal of Chemical Theory and Computation, 5 (9), pp. 2212-2221.