Aqueous-phase hydrodeoxygenation of 4-propylphenol as a lignin model to n-propylbenzene over Re-Ni/ZrO2 catalysts

Aqueous-phase hydrodeoxygenation of 4-propylphenol as a lignin model to n-propylbenzene was carried out over various Ni based catalysts. Among the catalysts tested, Re-Ni/ZrO2 showed the best catalytic performance. Addition of Re decreased the Ni particle size and greatly improved the catalytic activity. H-2 pressure, Re to Ni ratio and reaction temperature were tuned in the optimization of reaction conditions for favorable formation of n-propylbenzene. Under the conditions of 300 degrees C and 4 MPa H-2, the yield of n-propylbenzene reached 54% over Re-Ni/ZrO2 (Re/Ni ratio 0.33) catalyst. It is suggested that the formation of n-propylbenzene proceeds via the hydrogenation of 4-propylphenol to form 4-propylcyclohexanol, followed by the dehydration to give 4-propylcyclohexene and the subsequent dehydrogenation to n-propylbenzene. (C) 2013 Elsevier B.V. All rights reserved.