Catalyst preparation and deactivation issues for nitrobenzene hydrogenation in a microstructured falling film reactor

Hydrogenation of nitrobenzene to aniline in ethanol was performed continuously in a microstructured failing film reactor at 60 degreesC, 1-4 bar hydrogen pressure and residence time 9-17 s. Palladium catalyst was deposited as films or particles via sputtering, UV-decomposition of palladium acetate, incipient wetness or impregnation. Deactivation was observed and was particularly pronounced for the sputtered and UV-decomposed catalysts. Catalysts prepared through incipient wetness or impregnation were more stable and activity could be recovered by oxidation at 130 degreesC. The main causes of deactivation were determined to be deposition of organic compounds and palladium loss. (C) 2003 Elsevier B.V. All rights reserved.