High Crush Strength Multi Metal Oxide Extrudates

High crush strength and attrition resistant catalyst supports having still decent porosity are desirable to minimize pellet breakage and metal loss during catalyst production and plant operation in fixed bed reactors. We have been applying high throughput methodologies in miniaturized extruders to develop strong porous extrudates from common commercial oxidic powders. We have developed extrusion formulations for doped and undoped, bound and binder-less alumina, titania and zirconia showing remarkably high crush strength. Readily available powders such as Pural (Sasol), Hombikat (Venator) and FZO-grades (Luxfer) have been used as starting materials. Dopants have been added as aqueous salt solutions to the dough in the kneader. The high throughput screening matrix encompassed state-of-art as well as novel peptization agents and extrusion aids (temporary binders, mold release agents, lubricants, porogens). In particular, a variety of non-cellulosic additives has been screened. Boehmite (Sasol) and thermally decomposable, water soluble Zr salt cross-linkers (Luxfer) served as permanent (inorganic) binders. Crush strengths as high as 35N/mm for 1mm diameter alumina and 25N/mm for zirconia porous catalyst supports have been achieved which compares favorably with commercial extrudates. For silica-bound titania extrudates, high crush strength of 25N/mm was obtained while unbound titania resulted in brittle extrudates post calcination. We see a broad spectrum of applications in heterogeneous catalysis for these new materials ranging from exhaust gas purification via hydrogenation to biochemical processes.