A series of alkali- and/or alkali-earth-promoted, carbon-supported Ru catal
ysts have been prepared by impregnation from aqueous solutions of the precu
rsors. The supports have been pretreated by heating in inert atmosphere at
various temperatures, followed by partial oxidation in air at 425 degrees C
and then by hydrogen treatment at 900 degrees C. The catalyst samples, dil
uted 1/22 with quartz powder, have been studied in ammonia synthesis by mea
ns of a bench-scale, downflow, continuous, tubular reactor, under standard
reaction conditions (430 degrees C, 100 bar total pressure, H-2/N-2 = 1.5/1
feeding ratio). Caesium and Barium proved to be much more effective promot
ers than Potassium as promoters and the optimal temperature range for suppo
rt pretreatment was found to be about 1900 degrees C. The ammonia productiv
ity, on a catalyst volume basis, of our best Ru catalyst was about twice hi
gher than that of the most widely used Fe-based commercial catalysts. (C) 1
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