POROUS SOLIDS AND THEIR CHARACTERIZATION - METHODS OF INVESTIGATION AND APPLICATION

Porous and finely divided solids are distinguished by a large surface to volume ratio. As a result, they have specific properties, such as enhanced reactivity, a high adsorption capacity, and a lowered sinter temperature. This contribution gives a survey over selected aspects of porous solids, with the main emphasis on methods of characterization and their applications. We treat porous solids with a regular pore network (zeolites) and irregular pore structure (sintered compacts, rocks). After a short review of the possibilities of characterization, we will describe the methods of gas adsorption and Hg intrusion in detail. Furthermore, we will give a critical assessment of the measurement of typical characterization parameters, such as the specific surface area, the pore volume and the pore volume distribution. The fractal character of large-surface and porous solids and the related uncertainty of the outcomes of measurements result in the necessity of standardization of experimental procedures and in the need for reference materials. The section on applications treats examples of porous solids from different areas: densification of ceramic materials, porous ceramic carriers for flue gas desulfurization, technical catalysts (zeolite/binder), zeolites for the separation of substances, sedimentary and crystalline rocks.