Characterization of fast pyrolysis oil from short-rotation willow by high-resolution Fourier transform ion cyclotron resonance mass spectrometry

Fast pyrolysis oil (FPO) produced from short-rotation willow was characterized by using high-resolution Fourier transform ion cyclotron resonance (FT-ICR) mass spectrometry and various bulk chemical analyses. The pyrolysis experiments were carried out on a bench-scale bubbling fluidized bed pyrolysis reactor operating at the temperature of 500 °C. The resulting pyrolysis oil was a single-phase liquid with relatively low oxygen content and had pH and total acid number values of 3.0 and 129 mg/g, respectively. A wealth of compositional information of the willow FPO was obtained using FT-ICR MS in combination with electrospray ionization (ESI) and atmospheric-pressure photoionization (APPI) techniques. While ESI preferentially ionized acidic extractives, small phenolics and anhydrosugars, APPI ionized clearly larger compounds, including neutral lipophilic extractives, triterpenoids and high molecular mass pyrolytic lignin, most of which are beyond conventional gas chromatography-mass spectrometry analyses.