Solventless hydrodeoxygenation of dihydroeugenol in a continuous reactor over Ni catalysts modified by Fe and Ce

Abstract

Solventless hydrodeoxygenation of dihydroeugenol was investigated in a continuous reactor in the temperature range of 275–300 °C under 30 bar hydrogen using either monometallic Ni- or Fe supported on Al₂O₃, as well as their bimetallic counterpart. Furthermore, a bimetallic FeNi/H-ZSM-5 and NiCeAl catalyst were tested in this reaction. FeNi catalysts were prepared by both incipient wetness and evaporation impregnation methods, while NiCeAl was prepared by the solution combustion method. The catalysts were characterized by nitrogen adsorption–desorption, pyridine adsorption–desorption by FTIR, X-ray diffraction, transmission electron microscopy, temperature programmed reduction, ⁵⁷Fe Mössbauer spectroscopy, and the CHNS method. The best results were obtained at 300 °C, where the bimetallic FeNi/Al₂O₃ catalyst with equal nominal loadings of iron and nickel, and the NiCeAl catalyst both achieved complete conversion after prolonged time-on-stream, yielding oxygen-free products in the range of 79–95%. The spent NiCeAl catalyst exhibiting the perovskite structure AlCeO₃ was efficient in coke removal. In average metal particle size and extensive catalyst deactivation with increasing time-on-stream. Noteworthy is that although NiCeAl possesses both large and small metal particles as well as a very low specific surface area, it, however, retained its high activity with increasing time-on-stream.

Graphical abstract