Crystallite size distributions in sintered dispersed nickel catalysts

A technique for the computation of the size distribution of small ferromagnetic crystallites through measurements of magnetization is employed in the study of nickel supported catalysts. Catalyst samples are first reduced in hydrogen, and then sintered in helium at temperatures between 673 and 873K. Measurements of magnetization are performed during 30-hour treatments at each temperature. Crystallite size distributions thus determined are used to compute the metal surface area after sintering. Changes in the crystallite size distribution due to sintering are considered in relation to current leading theories of sintering mechanism. The progressive removal of small nickel crystallites (less than about 2.0nM radius) indicates that sintering occurs through crystallite migration and coalescence. [...]