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 e nhanced reactivity, a high adsorption capacity, and a lowered sinter t emperature. This contribution gives a survey over selected aspects of porous solids, with the main emphasis on methods of characterization a nd their applications. We treat porous solids with a regular pore netw ork (zeolites) and irregular pore structure (sintered compacts, rocks) . After a short review of the possibilities of characterization, we wi ll 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 charac ter of large-surface and porous solids and the related uncertainty of the outcomes of measurements result in the necessity of standardizatio n of experimental procedures and in the need for reference materials. The section on applications treats examples of porous solids from diff erent areas: densification of ceramic materials, porous ceramic carrie rs for flue gas desulfurization, technical catalysts (zeolite/binder), zeolites for the separation of substances, sedimentary and crystallin e rocks.