Effect of catalyst support on dihydroeugenol hydrodeoxygenation on low cost FeNi catalyst to produce renewable alkane fuel

Abstract

Solventless hydrodeoxygenation of dihydroeugenol was investigated in a continuous reactor at 300 °C under 30 bar over different nickel-iron catalysts, prepared using a two-step impregnation method. The following catalysts were studied: mesoporous FeNi/Al2O3, FeNi/SiO2 and FeNi/H-MCM-48 as well as microporous FeNi/H-Beta-300, FeNi/H-Beta-38, FeNi/H-Y-5.1, FeNi/H-MCM-48 and FeNi/USY-30. The catalysts were characterized by SEM coupled with energy dispersive X-ray analysis, Mössbauer and X-ray absorption spectroscopy, hydrogen TPR, X-ray diffraction, TEM, nitrogen physisorption and FTIR pyridine adsorption. DFT calculations were performed to elucidate the role of Fe and Ni. The results revealed that FeNi/Al2O3 was the most active and stable in dihydroeugenol hydrodeoxygenation. Complete conversion of dihydroeugenol was obtained and the yield of the main product propylcyclohexane was varying in the range 84–88 %. FeNi/Al2O3 catalyst exhibited 3.4 nm metal particles and contained FeNi alloy particles with the fcc metallic structure. No deactivation was observed for FeNi/ Al2O3 during 5 hours time-on-stream due to the presence of Ni-rich particles with iron-enriched outer surface confirmed by EXAFS. Fe was shown to be responsible for deoxygenation, while Ni promotes hydrogenation. Catalyst deactivation was observed for all other catalysts except for FeNi/Al2O3 with increasing time-on-stream under the same reaction conditions due to their higher Brønsted to Lewis acid site ratio and larger average metal particle size in comparison to FeNi/Al2O3.