Palladium-copper and palladium-tin catalysts in the liquid phase nitrate hydrogenation in a batch-recycle reactor

Catalytic liquid phase nitrate reduction was investigated at T = 298 K and atmospheric pressure in an isothermal batch-recycle reactor in the presence of various Pd-Cu and Pd-Sn bimetallic catalysts supported on alumina spheres with particle diameter of 1.7 mm. It was discovered that Pd-Sn solids synthesized accordingly to various catalyst preparation methods, exhibit considerably lower activity for nitrate removal in comparison to Pd-Cu catalysts. Formation of undesired ammonium ions is favored over Pd-SnPy-Al2O3 catalysts prepared by impregnation and co-impregnation techniques. Acidity and textural properties of alumina supports as well as the presence of chloride ions in the catalyst-solution interface detrimentally influence catalytic performance in the process of liquid phase nitrate hydrogenation. (C) 2004 Elsevier B.V. All rights reserved.