Selective hydrogenation of acetophenone over nickel supported on titania

Abstract

The catalytic activity of Ni impregnated on various phases of titania, viz. rutile, anatase and high surface area, has been investigated for the hydrogenation of acetophenone. The TPR profile of Ni/rutile suggests a strong metal–support interaction. The observed catalytic activity order is Ni/rutile > Ni/anatase > Ni/TiO₂. The greater activity of Ni/rutile is attributed to higher concentration of Ni on the surface and SMSI. The catalyst samples showed sintering of Ni when calcined at 900 °C, which resulted in a drop in their catalytic activity. The catalyst stability studies showed that activity is lost only marginally in rutile and anatase. The electronic interaction between Ni and rutile promotes the formation of electron enriched Ni–H species which interact with the carbonyl group of acetophenone. The hydrogenation proceeds with atom economy to form phenylethanol irrespective of the reaction conditions suggesting that these catalysts are of significant importance in green chemistry. The results obtained in this investigation clearly establish that Ni/rutile, a non-porous support, is better for this class of reaction.