Zn(II)-Cr(III) mixed oxide as efficient bifunctional catalyst for dehydroisomerisation of α-pinene to p-cymene

Zn(II)-Cr(III) mixed oxide possessing acid and dehydrogenation functions is an efficient, noble-metal-free catalyst for the one-step dehydroisomerisation of alpha-pinene to p-cymene. This reaction is a good example of the use of heterogeneous multifunctional catalysis for the conversion of renewable feedstock into value-added chemicals. It involves acid-catalysed alpha-pinene isomerisation followed by dehydrogenation of p-cymene precursor(s). The reaction is carried out over a fixed catalyst bed in the gas phase at 350 degrees C. Amongst Zn-Cr oxides studied (Zn/Cr = 20:1-1:30), the preferred catalyst is Zn-Cr (1: 1) oxide which produces p-cymene with a 78% yield at 100% alpha-pinene conversion. This catalyst shows stable performance for over 30 h without co-feeding hydrogen to the reactor. (C) 2009 Elsevier B.V. All rights reserved.