Monolithic catalysts for hydrogenation of nitrobenzene to aniline: influence of aluminum suspension properties

摘要

Aluminum suspensions with different properties were prepared and characterized by UV-Vis spectra, BET, XRD and NH3-TPD. A layer of Al2O3 was coated onto the cordierite monolith by sol-gel method. Pd/Al2O3/cordierite monolith catalysts with the same Pd loading and particle size were prepared, and tested by nitrobenzene hydrogenation under solvent-free conditions. The adsorption of nitrobenzene on acid sites might be the primary effect under the reaction conditions, and a good linear relationship between hydrogenation rate and the acid content of the Al2O3 layer was observed. Furthermore, the stronger acid sites were responsible for the lower aniline selectivity.