Pd/Co3O4/Ni Foam Catalyst for Highly Efficient Vanillin Hydrodeoxygenation in a Micropacked Bed Reactor

Abstract

In this work, monolithic Pd/Co3O4/Ni foams were prepared by the hydrothermal-impregnation method. The structure, composition, and surface characteristics of Pd/Co3O4/Ni foam catalysts were analyzed. Also, the effects of reaction temperature, pressure, initial vanillin (VL) concentration, catalyst type, and H2 and liquid flow rates on VL hydrodeoxygenation performance were discussed in micropacked bed reactors (μPBRs) with the Pd/Co3O4/Ni foam. The highest VL conversion of 99.9% and best 2-methoxy-4-methylphenol (MMP) yield of 99.4% can be obtained in μPBRs within a residence time of 53.2 s at 130 °C in the isopropyl alcohol (IPA) solvent. The kinetic model of VL hydrodeoxygenation to MMP was established based on ignoring external and internal mass transfer. The intrinsic activity energies for VL to HMP and HMP to MMP were 11.66 and 39.78 kJ/mol, respectively. μPBRs with Pd/Co3O4/Ni foam catalysts showed a high MMP space-time yield (STY) of 5.03 kg/L/h/gcat, which was higher than that of traditional batch reactors and other continuous flow reactors.