Technical Papers and Presentations

Microreactors have gained popularity in fuel production industry. This is due to its high surface area to volume ratio, enhanced mass and heat transfer, short residence time and a more sustainable practice. The catalytic hydrodeoxygenation (HDO) reaction of 4-Propylguaiacol (4PG) to 4-Propylphenol using pre-sulphided NiMo/Al₂O₃ catalyst has been investigated using a packed-bed plug flow microreactor. A 2D reactor model was created to simulate the mass transfer and reaction within the catalyst in the reactor. A steady-state and isothermal microreactor was modeled using Langmuir Hinshelwood Hougen Watson kinetics. The microreactor has a heterogeneous configuration, and the Chemical Reaction Engineering Module has been used to simulate the reaction. To simulate the reaction within the catalyst particles the Reaction Pellet Bed feature was utilized. The effect of transport phenomena around and inside the catalyst particles is investigated with regards to the behavior of the microreactor studied. In addition, the Transport of Diluted Species, Reaction Engineering, and Chemistry physics interfaces have all been applied successfully to the model. The mass balance equations coupled with the appropriate boundary conditions were solved using COMSOL Multiphysics^® software version 5.3. The finalized geometry contained a mesh consisting of 12022 elements and 168432 degrees of freedom was used, and the results were found to be mesh independent. The operational factors such as reaction temperature, pressure, residence time and liquid flow rate of 4PG were investigated to determine their effects on conversion of 4PG. Concentration profiles of the reactants within the catalyst particle are also obtained, and mass transfer resistance is also investigated. The results were then compared with experimental data from literature to assess the validity of the microreactor model. The model was aligned with experimental data for reactor conditions of 22.8 atm and 250-400 °C. The results demonstrated very good validation with the experimental data, and showed that 4PG concentration increases with increasing temperature. The same trend was observed for pressure and residence time; however, 4PG conversion decreased with increasing liquid flow rate. Higher conversions can be achieved when adiabatic conditions are used as more heat is available for the catalytic reaction. The results obtained from the microreactor model show good agreement with experimental data. The differences in results between the model and experimental are observed for temperatures > 350 °C. This is due to the results being influenced by the yield (%) of other reaction products, which are not considered in the model due to the lack of reaction kinetics available. To conclude, this model can be used to predict the hydrodeoxygenation of other components present in biomass-derived pyrolysis oils. Furthermore, there is a good possibility that microreactors can replace conventional macroscopic reactors to produce biofuels. They have the potential to enhance fuel output by means of scaling up, and they can be used for offshore fuel production.