Shaping of sulfated zirconia catalysts by extrusion: understanding the role of binders

Sulfated zirconia hydroxide shaping by extrusion is studied based on elucidating the impact of zeta-potential and rheological characteristics on physical and chemical properties of technical catalysts. Zeta potential measurements of sulfated zirconium hydroxide prior and after poly(vinyl alcohol) (PVA) additions were made. Rheological curves of sulfated zirconium hydroxide suspensions with different amounts of PVA were recorded at different zeta-potential values. The addition of PVA nonlinearly decreased shear yield stress. Experimental data were quantified with the Krieger–Dougherty equation. The influence of a boehmite-type binder on the zeta-potential confirmed that the surface properties of the particles to a large extent are determined by the presence of binder. The pore structure of shaped catalysts was unaffected by rheological parameters when zeta-potential is close enough to zero. At the same time deviations of the zeta potential from the zero-value afforded more uniform pore size distribution.