Preparation of chlorine-free alumina-supported ruthenium catalyst for ammonia synthesis base on RuCl3 by hydrazine reduction

A series of Ru/Al2O3 catalysts for ammonia synthesis were prepared by hydrazine reduction of RuCl3 in KOH solution under the mild conditions, and characterized by XRF, TEM and CO chemisorption. The results showed that no chloride remained on the catalysts obtained by hydrazine reduction and the activities of the catalysts with hydrazine treatment were higher than those of conventional hydrogen-reduced catalysts. The particles sizes and the activities of the catalysts were determined by the molar ratios between hydrazine and ruthenium. The most promising catalyst was obtained when the hydrazine/ruthenium ratio was in the range of 1–3.