Genetically engineered hybrid poplars for the pyrolytic production of bio-oil: Pyrolysis characteristics and kinetics

Abstract

In this study, hybrid poplars were genetically engineered to increase their biomass volume and change their biochemical composition to improve the pyrolytic production of bio-oil. Wild-type hybrid poplars (WT) and genetically engineered hybrid poplars (TP) were comparatively investigated with regard to their pyrolysis characteristics and kinetics via thermogravimetric analysis (TGA) and isothermal pyrolysis within a micro-tubing reactor. Model-free methods were used to determine the activation energy for the thermal decomposition of the WT and TP samples. The results showed that the activation energy of the WT sample was always greater than that of the TP sample at the same level of conversion. Isothermal pyrolysis experiments of the two biomass samples were performed at various temperatures (360–400°C) and durations (1–5min) using a micro−tubing reactor. The pyrolytic product distributions and chemical compositions were compared. The obtained results showed that the TP sample yielded a higher quantity of bio-oil compared to the WT sample under the same conditions with different chemical compositions. A reaction network and quantitative kinetic model were proposed for pyrolysis of the WT and TP samples. Kinetic parameters were obtained through an optimization function and used to explore the parameter space in order to predict product yields as a function of reaction time and temperature for both WT and TP feedstocks.