Optimising ex-situ catalytic fast pyrolysis of pine wood at pilot scale: Impacts on the energy content, chemical composition and stability of the liquid fuel product

Abstract

A central composite design was used to optimise the yield and higher heating value (HHV) of the liquid fuel produced through ex-situ catalytic fast pyrolysis of pine wood. The variables were the temperature and loading of H-ZSM-5 zeolite catalyst. GC/MS, 1H NMR and stability tests were undertaken to compare the fuel properties of organic phases with similar HHVs, generated from catalytic treatments at low (≤ 370 °C) and high (≥ 470 °C) temperatures. When targeting an HHV of 32 MJ/kg, higher yields were obtained at low temperature and high catalyst loading, despite higher coke yield. Treatment at low temperature preserved more alkyl groups and made the fuel less aromatic (−13 % of aromatic hydrogen and lower content of Crich hydrocarbons). Undesirable catalytic cracking of alkyl groups at higher temperature was evidenced by a 60 % increase in the production of hydrocarbon gases. Despite a higher oxygen content, the fuel produced at low temperature was also found to be more stable.