Monitoring pine wood thermolysis under hydrogen atmosphere by in situ and ex situ techniques

The behavior of lignocellulose and the products released during decomposition under hydrogen or argon were investigated through two different approaches: (i) in situ techniques by TGA coupled with gas phase FTIR spectroscopy and temperature resolved DRIFTS with online GCMS. These techniques provide the decomposition profile, the evolution of the wood surface structure and identification of the released compounds. (ii) Ex situ experiments where three fractions (gas, liquid, solid) were obtained in notable quantity and separated after the decomposition. GC, GCMS, NMR, FTIR and elemental analysis were used to characterize the products. The combination of these characterization techniques showed that the decomposition of the pine wood starts from the holocellulosic part around 275 °C producing light oxygenated compounds such as furfural derivate. Lignin structure degrades at temperatures higher than 350 °C leading to formation of phenolic compounds.

► Pyrolysis of lignocellulosic biomass, pine wood, is studied using in situ and ex situ techniques. ► The main compounds released during the thermolysis were identified and composed of oxygenated molecules. ► It was shown that the pine wood was thermally stable up to 250 °C. ► Solid state 13C NMR showed that the cellulose and hemicellulose start to decompose around 300 °C, and the lignin at 350 °C. ► It was observed that the decomposition is faster under hydrogen than under argon.