The vapor-phase cracking of 4-vinylguaiacol has been investigated in a nonisothermal, laminar-flow reactor at temperatures between 300 and 900 °C and a residence time of one second. Products identified by gas chromatography were oxygenated compounds such as phenols, cresols, furans, ketones, and aldehydes, single-ring and polycyclic aromatic hydrocarbons, C1–C6 hydrocarbon gases, and carbon monoxide. Temperature had a marked effect in governing the overall product composition. Conversion of 4-vinylguaiacol to products increased above 400 °C and was completed at 550 °C. Reaction rate parameters derived from the conversion data were A = 1013 s–1 and E a = 45.3 kcal mol–1. The oxygenated compounds were observed as products in the range 450–800 °C, peaking in yields below 700 °C. The aromatic hydrocarbons and light gases dominated the product composition above 600 °C, especially at 900 °C, the highest temperature investigated. On the basis of the experimental data showing the effect of temperature on product composition, reaction pathways leading to products formation are proposed.

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.