Effect of Peptization on Physical and Chemical Properties of Extruded Alumina.

In connection with the technology of catalyst preparation, factors influencing the peptization of aluminum hydroxide were studied together with the properties of the resulting alumina extrudates. The dependence of mechanical strength of extrudates upon the kneading time has been found to follow the first-order rate equation. The amount of peptization agent necessary for obtaining extrudates of a given mechanical strength decreases with diminishing dimensions of the primary aluminum hydroxide particles. The final physical properties of extrudates (e. g. , the specific surface area, pore volume, and mechanical strength) depend on the Hammett acidity function H//o of the peptization agent employed. The most significant changes in the properties of alumina extrudates have been observed in the range 0 less than H//0 less than 3. Peptization solutions with H//o less than 0. 25 are not suitable owing to poor properties of resulting extrudates.