(225b) Kinetic Study of Hydrodeoxygenation of 4-Propyl Guaiacol in a Microreactor

Pyrolysis oil (PO) derived from fast pyrolysis of lignocellulosic biomass contains about 40-50 wt% oxygen including the oxygen in water. Removal of oxygen from pyrolysis oil is necessary to increase its energy density, thermal stability, volatility, and enhance miscibility with crude oil. Our current study focuses on hydrodeoxygenation of pyrolysis oil however, the presence of more than 300 oxygenates complicates this reaction and provides little understanding of reaction networks and kinetics, a requirement for process design and modeling. We have used a model compound, 4-propyl guaiacol (4PG), to better understand the oxygen removal reaction and kinetics.

 The catalytic hydrodeoxygenation of 4PG is performed in a packed bed microreactor to take advantage of improved heat and mass transfer characteristics. The effects of various processing conditions such as hydrogen partial pressure, reactor diameter, temperature, and residence time on conversion, selectivity, and space-time-yield are investigated using presulfided Ni-Mo/Al₂O₃ catalyst. External and internal mass transfer resistances and heat transfer resistance are investigated. Reaction rate expressions are synthesized based on proposed reaction mechanisms using Langmuir-Hinshelwood approach. The predicted reaction rates from the rate expressions are then compared for consistency with the observed reaction rates obtained from the differential reactor. The best fitted rate equations are further validated by comparing experimental data obtained from integral reactor with predictions based on the rate equations.