Measurements of the zeta potential of solid heterogeneous supports are important for preparation of metal supported catalysts and for shaping zeolites into extrudates. In the current work, different types of heterogeneous support materials such as SiO₂, Al₂O₃, and a range of beta zeolites of different silica- to-alumina ratio were analysed. It was observed that parameters such as temperature, pH and acidity significantly affect the zeta potential. In several instances, depending on the materials’ acidity and microstructure, maxima in zeta potential were observed. The solid materials were thoroughly characterized using XRD, SEM, EDX, TEM, nitrogen physisorption, Al-NMR and FTIR with pyridine before zeta potential measurements.

Four different types of shaped catalysts with controlled deposition of platinum and the same composition were prepared by extrusion from Beta zeolite agglomerated with bentonite as an aluminosilicate clay binder. The catalysts were characterized using mechanical strength tests, scanning electron microscopy for morphology, transmission electron microscopy for porosity and periodicity, nitrogen physisorption for surface area, pore volume and pore size distribution, Fourier transform infrared spectroscopy using pyridine as a probe molecule to elucidate presence, strength and amount of Brønsted and Lewis acid sites. Elemental analysis was carried out using energy dispersive X-ray micro-analysis. Activity and selectivity of catalysts in the isomerization of n-hexane were evaluated using a fixed bed reactor at 200 – 350 °C. At low temperature, the performance of metal/acid bifunctional shaped catalysis was strongly affected by the metal-to-acid site ratio. This ratio and the total acidity were strongly influenced by the preparation method of the shaped catalysts, while the textural properties were comparable. The highest conversion of n-hexane and selectivity to C6 isomers (comprising all branched isomers, such as methyl pentane and dimethyl butane) was obtained with extrudates prepared via in-situ synthesis with platinum located on the zeolite. The extrudates prepared in this way have the highest metal-to-acid site ratio and their closest proximity, albeit the lowest mechanical strength.

Composite materials for shaped catalysts were prepared from three commercial beta zeolites using bentonite as an aluminosilicate clay binder. All pristine materials and the synthesized powder mixtures were characterized using X-ray powder diffraction for phase purity and structures, scanning electron microscopy for morphology, transmission electron microscopy for porosity and periodicity, nitrogen physisorption for surface area, pore volume and pore size distribution, and Fourier transform infrared spectroscopy using pyridine as a probe molecule to elucidate the presence, strength and amount of Brønsted and Lewis acid sites. Elemental analysis was carried out using energy dispersive X-ray micro-analysis. Through a systematic comparison of the properties of the individual components and powder zeolite–binder composites, this study elucidated the crucial binder influence on the key properties of the catalytic supports during the synthesis of the composites in the powder form, i.e. prior to shaping. It can be concluded that the promoting effect of the bentonite binder is derived from chemical interactions with the zeolite. The resulting effect of the binder on the composite properties is not a simple additive just reflecting the nominal ratio of the components. The synthesis process, zeolite type (SiO₂/Al₂O₃ ratio of the framework, particle size) and binder concentration play a significant role in the resulting binder effect in composites.