Enhancement of fast pyrolysis oil fuel properties through co-pyrolysis and improved analysis

Krutof, Anke (2019) Enhancement of fast pyrolysis oil fuel properties through co-pyrolysis and improved analysis. Doctoral (PhD) thesis, Memorial University of Newfoundland.

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Abstract

Fast pyrolysis is a thermochemical process converting biomass into fast pyrolysis biooil (FPBO, 50-75 wt%), non-condensable gases (13-16 wt%), and biochar (12-20 wt%) at 450-550°C in an inert atmosphere with short residence times and high heating rates. FPBO is a complex organic mixture of lignocellulose degradation products with high water (20-30 wt%) and oxygen content (35-40 wt%) causing chemical instability and corrosion to storage tanks and burners. In this work, the improvement of FPBO quality was investigated through co-pyrolysis of forestry residues with waste mussel shells and through improved understanding of phase behaviour and composition of forestry based FPBO using an advanced distillation curve analysis. Co-pyrolysis with waste mussel shells was studied by: (1) direct contact with the forestry residues in the reactor and (2) contacting only the hot vapours with the mussel shells at the reactor exit. The impact of temperature, residence time, mussel shell loading, and type of contact (operational mode) on the FPBO and biochar were studied. There was a reduction in FPBO oxygen and acid content through dehydration and decarboxylation with mussel shell addition and an increase in biochar pH and functionality (O- and N-containing functional groups) for soil amendment and adsorption applications, respectively. The FPBO phase behaviour was studied using an advanced distillation method and a model developed to simulate the distillation curves of the whole FPBO. The 17 surrogates used in the model to represent the range of functional groups and boiling points of FPBO components showed a good fit of simulated and experimental distillation curves and some bulk properties. GC analysis of the vacuum distillate fractions concluded six distillable steps as a basis for chemical separation procedures.

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