Abstract: The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and
nitrogen,dispersion of metallic Ru and catalytic activity of active carbon (AC) supported
ruthenium catalyst for ammoniasynthesis have been studied by means of pulse chromatography,
temperature-programmed desorption, and activitytest. Promoters K, Ba and Sm increased the
activity of Ru/AC catalysts for ammonia synthesis significantly, andparticularly, potassium
exhibited the best promotion on the activity because of the strong electronic donation
tometallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or
triple promoters. The activityof Ru/AC catalyst is dependent on the adsorption of hydrogen
and nitrogen. The high activity of catalyst could beascribed to strong dissociation of
nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit theadsorption
of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by
Sm2O3 showsthe best dispersion of metallic Ru, since the partly reduced SmOx on the surface
modifies the morphology of activesites and favors the dispersion of metallic Ru. The
activity of Ru/AC catalysts is in accordance to the correspondingamount of nitrogen
chemisorption and the desorption activation energy of nitrogen. The desorption activation
energyfor nitrogen decreases in the order of Ru＞Ru-Ba＞Ru-Sm＞Ru-Ba-Sm＞Ru-K＞Ru-K-Sm＞Ru
-K-Ba＞Ru-K-Ba-Sm,just opposite to the order of catalytic activity, suggesting that the
ammonia synthesis over Ru-based catalyst iscontrolled by the step of dissociation of
nitrogen.

Key words: ruthenium, catalyst, ammonia synthesis, chemisorption, desorption

摘要： The effects of promoters K, Ba, Sm on the chemisorption and desorption of hydrogen and
nitrogen,dispersion of metallic Ru and catalytic activity of active carbon (AC) supported
ruthenium catalyst for ammoniasynthesis have been studied by means of pulse chromatography,
temperature-programmed desorption, and activitytest. Promoters K, Ba and Sm increased the
activity of Ru/AC catalysts for ammonia synthesis significantly, andparticularly, potassium
exhibited the best promotion on the activity because of the strong electronic donation
tometallic Ru. Much higher activity can be obtained for Ru/AC catalyst with binary or
triple promoters. The activityof Ru/AC catalyst is dependent on the adsorption of hydrogen
and nitrogen. The high activity of catalyst could beascribed to strong dissociation of
nitrogen on the catalyst surface. Strong adsorption of hydrogen would inhibit theadsorption
of nitrogen, resulted in decrease of the catalytic activity. Ru/AC catalyst promoted by
Sm2O3 showsthe best dispersion of metallic Ru, since the partly reduced SmOx on the surface
modifies the morphology of activesites and favors the dispersion of metallic Ru. The
activity of Ru/AC catalysts is in accordance to the correspondingamount of nitrogen
chemisorption and the desorption activation energy of nitrogen. The desorption activation
energyfor nitrogen decreases in the order of Ru＞Ru-Ba＞Ru-Sm＞Ru-Ba-Sm＞Ru-K＞Ru-K-Sm＞Ru
-K-Ba＞Ru-K-Ba-Sm,just opposite to the order of catalytic activity, suggesting that the
ammonia synthesis over Ru-based catalyst iscontrolled by the step of dissociation of
nitrogen.

关键词: ruthenium;catalyst;ammonia synthesis;chemisorption;desorption