On the way towards catalyst design in zeolites
Ecole Normale Supérieure de Lyon
In the past decade ab-initio modelling has proven to be a very powerful tool in the design of heterogeneous catalysts. Up until today it has been mainly restricted to predicting the catalytic activity of simple crystal planes. It is, however, desirable to transfer these concepts into the design of transition metal exchanged zeolite catalysts, which act as single site catalysts. In this talk I will speak about some of the prerequisites of catalyst design in transition metal exchanged zeolites. In the first part I will speak about Cu-exchanged SSZ-13, a highly active catalyst in the selective catalytic reduction of NOx. I will demonstrate how it is possible to identify the distribution of active sites from ab-initio modeling, infrared and diffuse reflectance UV-visible spectroscopy. Pairing this distribution with catalyst activity studies it is furthermore possible to identify the catalytically active sites for these reactions and make statements about the catalyst stability. In the second part I will speak about the adsorption of short alkanes in protonated SSZ-13. Using ab-initio molecular dynamics simulations I show the impact of temperature on free energies of adsorption. Additionally it is possible to calculate the coverage of the active sites and derive adsorption isotherms for the problems at hand. These vary from the standard models on surfaces and will influence deductions based upon the Sabatier principle. In the end I will show how it is possible to calculate free energies of adsorption using the calculated coverages and static calculations [2,3].
 F. Göltl, R.E. Bulo, J. Hafner, P. Sautet, JPCL 4, 2244-2249, (2013)
 F. Göltl and J. Hafner, MMM 166, 176-184 (2013)
 F. Göltl, A. Grüneis, T. Bučko, J. Hafner, JCP 137, 114111 (2012)