An alkali-promoted ruthenium catalyst for the synthesis of ammonia, supported on thermally modified active carbon

Ruthenium catalysts deposited on active carbon and pre-calcined at 1900°C in He atmosphere were studied. The precursors of the active phase were RuCl3·0.5H2O and Ru3(CO)12. Potassium and cesium (hydroxides or nitrates) were used as promoters. The catalysts were characterized by TEM, WAXS and H2 chemisorption. Activity measurements in NH3 synthesis were performed in a flow integral reactor under a pressure of 10 MPa at 470, 430, and 400°C (H2:N2=3:1). It has been found that the alkali-promoted catalyst deposited on the thermally modified carbon is much more active than that based on untreated carbon. The form of the Ru precursor used in the manufacture of the K-promoted catalyst had no effect on its dispersion or activity. The promoting effect of potassium was comparable to that of cesium. A monotonous increase in the activity of alkali-promoted catalyst vs. Ru content (5--15%) was observed, accompanied by a decrease in dispersion.