Abstract: The crystal size distribution(CSD)was determined with small angle X-ray scattering technique.Theanticoking property of Ni-catalysts was investigated with the steam reforming of n-heptane in a TG-monitoredflow reactor.The results of this study show that the rate of coking on the supported Ni-catalysts depends main-ly on the percentage content of the large size fraction(25-70nm)of Ni-crystallites,and that the dispersion ofNi-crystallites and the anticoking property of the Ni/α-Al_2O_3 catalysts were promoted obviously by theLa_2O_3-modification method.The variation of the Ni-CSD and the anticoking property of the catalysts were fur-ther tested through different periods of hydrothermal treatment.It is found that the content of the largeNi-crystal size fraction and the coking rate pass correspondingly through a maximum.

Key words: anticoking behavior, crystal size distribution, La-modified Ni/α-Al2O3 catalysts, period of hydrothemal treatment

摘要： The crystal size distribution(CSD)was determined with small angle X-ray scattering technique.Theanticoking property of Ni-catalysts was investigated with the steam reforming of n-heptane in a TG-monitoredflow reactor.The results of this study show that the rate of coking on the supported Ni-catalysts depends main-ly on the percentage content of the large size fraction(25-70nm)of Ni-crystallites,and that the dispersion ofNi-crystallites and the anticoking property of the Ni/α-Al_2O_3 catalysts were promoted obviously by theLa_2O_3-modification method.The variation of the Ni-CSD and the anticoking property of the catalysts were fur-ther tested through different periods of hydrothermal treatment.It is found that the content of the largeNi-crystal size fraction and the coking rate pass correspondingly through a maximum.

关键词: anticoking behavior;crystal size distribution;La-modified Ni/α-Al2O3 catalysts;period of hydrothemal treatment