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Sintering kinetics of silica- and alumina-supported nickel in hydrogen atmosphere

1983; Elsevier BV; Volume: 81; Issue: 1 Linguagem: Inglês

10.1016/0021-9517(83)90152-5

1090-2694

Calvin H. Bartholomew,

Advanced materials and composites

The sintering kinetics of NiSiO2 and Niγ-Al2O3 catalysts in H2 atmosphere were studied in the temperature range between 923 and 1023 K. Metal surface areas were measured as a function of time using H2 chemisorption. BET surface areas, pore size distributions, and metal crystallite size distributions were determined for fresh and sintered catalysts using Argon adsorption and transmission electron microscopy. Loss of nickel surface area occurs as a result of metal crystallite growth and support collapse. The latter is more significant at low temperatures and in the NiAl2O3 system. Growth of metal crystallites is predominant at high temperatures. NiSiO2 sinters more rapidly than NiAl2O3 at temperatures above 923 K but less rapidly in H2 atmosphere compared to He atmosphere (the latter comparison based on data obtained in He from a previous study). Orders of sintering decrease with increasing temperature and time of sintering. The kinetic and TEM data are consistent with a shift in mechanism from crystallite migration to atomic migration with increasing temperature and time of sintering.