Bi-functional zeolite based catalysts
Zeolite based metal-acid catalysts are widely used to convert fossil or renewable hydrocarbon feedstocks into high quality fuels. To ensure maximal catalytic activity, the most favorable location of the dehydrogenating/hydrogenating metal function is in close vicinity with the Brønsted acid sites of the zeolite. And for more than 50 years, the optimal intimacy between metal and zeolite acid sites was simply believed to be ‘the closer the better’, that is, metal particles were placed inside zeolite micropores.  However, a recent study by Zečević et al. showed that the selectivity can be greatly improved when Pt nanoparticles are located outside the zeolite, on the alumina binder of industrially used zeolite-alumina extrudates.  The location of the Pt particles, on the zeolite or on the alumina was controlled by exploiting the difference between strong electrostatic adsorption and ion exchange synthesis techniques. HAADF-STEM imaging combined with EDX mapping was used to confirm the location of the Pt nanoparticles in the composite support.
In this project, the strong electrostatic adsorption, ion-exchange or impregnation of metal precursors onto zeolite, Al2O3 and Al2O3/zeolite composites will be studied. More specifically, complex Pt/Al2O3/zeolite catalysts will be studied for selective Pt deposition onto the alumina or zeolite component of the support. The location of Pt nanoparticles within within Pt/Al2O3/zeolite catalysts will be systematically studied by TEM analysis combined with various bulk characterization techniques. Furthermore, the selectivity, activity and stability of prepared catalysts will be determined in hydrocracking and hydroisomerization tests.