Carbon-supported promoted Ru catalyst for ammonia synthesis

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) 1 999 Elsevier Science B.V. All rights reserved.