Application of Mercury Porosimetry to Predict the Porosity and Strength of Ceramic Catalyst Supports

Ceramic based monolithic supports are used in many catalytic reactions, especially in environmental remediation to avoid pressure drop limitations that may arise in the treatment of large effluent gas volumes. In these systems, the active phases or their precursors can be incorporated into the paste prior to kneading, extrusion and calcination, in order to achieve a uniform deposition throughout the final structure. However, these types of incorporated monolithic catalysts can suffer from diffusion limitations that necessitate the inclusion of temporary agents, which when removed by thermal treatments, generate a higher porosity. This results in an increase in the interconnectivity of the pore structure of the final material. However, an upper limit is reached since an increased porosity negatively affects the mechanical strength of these ceramic materials. In this paper, the mechanical strength and porosity of ceramic catalyst supports are related to the primary particle size of the raw materials, initial composition and final heat treatment temperature. Ceramic based monolithic supports are used in many catalytic reactions. Maximum porosity is desired in order to ensure a high diffusional transport. However, an upper limit for porosity is given by the required mechanical strength. Here we show how the mechanical strength and porosity of ceramic catalyst supports are related to the primary particle size of the raw materials, initial composition and final heat treatment temperature.