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.