Structural-Level Modeling of Biocrude Hydrodeoxygenation

High Resolution Image Download MS PowerPoint Slide Hydrodeoxygenation is an indispensable technology in the refining of biogenic feedstocks into transportation biofuels. In this study, a modeling approach is proposed for describing the hydrodeoxygenation of biocrude from forest biomass at the structural level. It comprises a feed composition modeling block that creates a molecular representation of the biocrude feed to the hydrodeoxygenation process from available analytical measurements. The thousands of molecules representing the biocrude feed are computationally assembled via stochastic simulation adhering to a hierarchical building sequence and coded in vector notation. The reaction modeling block that follows takes these simulated feed molecules and transforms them into product molecules by applying a set of reaction rules formulated from knowledge of hydrodeoxygenation chemistry. Reactions are organized into families according to the oxygen functional group and structural characteristics of the reactant molecules. Hydrodeoxygenation rate parameters are tuned against experimental data generated in a batch reactor over a wide range of conditions, whereas adsorption and equilibrium parameters are estimated using quantitative structure–reactivity correlations. The computational simulation of the exceedingly large reaction system is handled with the kinetic Monte Carlo algorithm. The resulting simulation model is shown capable of tracking the evolution of oxygen functional groups, gaseous products, and oil and water yields with respect to reaction time and process temperature, while providing insights into reaction pathways and reactivity patterns of oxygen compound families. The model also characterizes structural changes in the oil product throughout the process and provides reasonable estimates of how much hydrogen is consumed in the process.