Influence of Cr addition to Raney Ni catalyst on hydrogenation of isophorone

The influence of Cr (1-6 at.%) on the catalytic activity and selectivity of Ni-Al alloy in isophorone (3,5, 5-trimethyl-2-cyclohexen-1-one) hydrogenation was studied. The catalysts were obtained from the rapidly quenched precursors by leaching in NaOH aqueous solution. The catalytic tests were performed at various temperatures (20-80 degrees C) under the atmospheric or elevated pressure using gaseous hydrogen and 2-propanol as a solvent. Ni-Al-Cr alloy with 1 at.% Cr appeared to be the most active and selective catalyst, with the conversion level and selectivity to dihydroisophorone (3,3,5-trimethylcyclohexanone) exceeding 99%. On the other hand, further hydrogenation of dihydroisophorone to homomenthol (3,3, 5-trimethylcyclohexanol) was strongly restrained by the Cr-containing catalysts. Scanning electron microscopy, Auger electron spectroscopy, energy dispersive X-ray spectroscopy and X-ray diffraction allowed changes occurring during the catalyst preparation to be identified and their implications for catalytic function to be considered. (C) 2008 Elsevier B.V. All rights reserved.