Lumped Kinetics for Biomass Tar Cracking Using 4‑Propylguaiacol as a Model Compound

Lumped kinetics for the vapor-phase cracking of 4-propylguaiacol, a model compound representative of components found in primary tar derived from lignin, has been investigated. Analysis of the products from pyrolysis experiments in a laminar-flow reactor at temperatures between 300 and 900 °C and a residence time of 1 s revealed that the products can be lumped into three compound classes: oxygen-containing compounds, single- and multiring aromatic hydrocarbons, and permanent gases. Temperature was found to have a marked effect in governing the overall product composition. The oxygen-containing compounds peaked in yield between 500 and 700 °C. The aromatic hydrocarbons and permanent gases dominated the product composition above 600 °C, especially at 900 °C, the highest temperature investigated. A lumped kinetic model with three irreversible first-order reactions was developed to model the experimental data. This model was extended to one with eight first-order irreversible reactions. Optimized reaction-rate parameters for each reaction in both models were determined by fitting the experimental data using a plug-flow reactor model.