Support and promoter effect of ruthenium catalyst II. Ruthenium/alkaline earth catalyst for activation of dinitrogen

The turnover frequency (TOP) of the ammonia synthesis on Ru was promoted by using alkaline earths as supports. The TOF of this reaction on RuMgO and RuCaO was as high as those on RuCsOHAl2O3 catalyst. The activity was shown to be correlated with the electronegativity of oxide support. XPS results seem to support the electron transfer from alkaline earth to Ru. Activity of RuMgO was further promoted with CsOH, which increased not only TOF but also Ru dispersion. On the other hand, Ru/alkaline earth with K, which may be called “superbase-supported Ru catalysts,” proved to have excellent activities for N2 activation. TOF of ammonia synthesis over those catalyst was as high as that on RuKAC (activated carbon) which has been known to be the best catalyst under these conditions. Furthermore, TOF of N2 isotopic equilibration reaction on these catalyst were several times as high as those on RuKAl2O3 or RuKAC which have been believed to be the most active catalysts for this reaction.