On comprehensive understanding of catalyst shaping by extrusion
A brief introduction into catalyst shaping and its importance is given. Some challenges and key aspects are discussed. A special attention is paid to visualization of the structure of catalyst extrudates. Hydrous sulfated zirconia, as a promising catalyst for acid catalyzed transformations of hydrocarbons such as alkylation, is considered from the viewpoint of its shaping via extrusion. Rheology and zeta potential measurements are presented for this material, addressing also the influence of PVA addition as a surface-modifying agent. The quality of the green bodies of the shaped catalysts is shown to be strongly dependent on particles surface properties in molding masses.
Immense importance of catalysis in chemical industry is manifested by the fact, that roughly 85-90% of all chemical products have seen a catalyst during a course of the production. The number of catalytic processes in industry is very large with mainly heterogeneous catalysts applied. Such catalysts come in many different forms as porous solids. Contribution of catalysts to the overall cost of a product made with an aid of catalysts on average is not very high (ca. 3%). In theory catalysts are not consumed in a chemical reaction, while in industrial practice many industrial catalysts deactivate, requiring gradual replacement. Even taking such replacement into account a part of catalyst sales in relation to the gross domestic product (GDP) is marginal (ca. 0.1%). At the same time the share of products made by catalysts in GDP could be as high as 25%.
In the areas where heterogeneous catalysts are used in industry, almost one third is used in crude oil refining and petrochemistry (1). Among the current trends driving catalysts demands in the future, the following should be mentioned: improving process efficien ...