Characterisation of beech wood pyrolysis oil: Chemical and physical properties and decomposition kinetics

Biogenic and anthropogenic pyrolysis oils can be used as renewable feedstocks in combustion and entrained flow gasification processes. The design, evaluation and scale-up of these processes can be done using process and CFD models. However, this requires comprehensive and consistent data sets for the chemical and thermo-physical properties and the decomposition kinetics. Such data sets have not yet been compiled for research or for commercial pyrolysis oils. Therefore, this study characterised an industrial beech wood pyrolysis oil using (i) proximate, ultimate and heating value analyses, (ii) gas chromatography-mass spectrometry (GC-MS), gel permeation chromatography (GPC) and thermogravimetric (TG) analyses, (iii) vacuum and Engler distillations and (iv) measurements of density, dynamic viscosity, thermal conductivity, specific heat capacity and surface tension under atmospheric-pressure and low-temperature conditions. The chemical analyses demonstrated significant uncertainties in the sampling and the analysis methods, which strongly affect the design and evaluation of pilot-scale entrained flow gasification experiments. The vacuum distillations provided representative samples of the vaporisable and non-vaporisable components to a large extent. ... mehrThe TG analyses showed the superposition of vaporisation and decomposition based on separate analyses of the vacuum distillate and the vacuum distillation residue. Furthermore, thermo-physical property models were developed for the beech wood pyrolysis oil, the vacuum distillate and the vacuum distillation residue. Finally, thermogravimetric kinetics were derived based on multi-reaction Arrhenius law models and multi first-order reaction Gauss distributed activation energy models. Single-particle predictions based on these kinetics indicated that multi first-order reaction Gauss distributed activation energy models should be preferred for extrapolation to high heating rates in the absence of kinetics based on drop-tube reactor experiments.