An approach for the improved measurement of pyrolysis products

The composition of a fuel and the combustion environment are factors that impact pyrolysis processes. The pyrolysis of a natural polymer, timber, and the synthetic polymers, polymethylmethacrylate (PMMA) and polystyrene (PS), was performed at a constant mass loss rate (MLR) using a feedback control loop utilising the Fire Propagation Apparatus (FPA) under inert and oxidative environments. The controlled MLR (2 g s−1 m−2) enabled a representative means of monitoring emissions via a combination of spectroscopic techniques. Reported yields were calculated utilising adapted Fourier-transform infrared spectroscopy (FT-IR) data based upon the species detected via gas chromatography-mass spectrometry (GC-MS). The speciation offered by the GC-MS was used to adjust recorded FT-IR yields, facilitating an insight into the composition of pyrolysis emissions. The presence of molecular oxygen was not found to drastically influence the decomposition behaviours of the investigated synthetic polymers with the yields of primary monomers being relatively unaffected by the atmospheric environment. However, a difference was noted when using timber, as the generated char was visually different under the oxidative atmospheres. The presence of char oxidation was confirmed as a lower applied heat flux was required to sustain the desired mass loss rate. We conclude that the proposed combined analytical approach shows great potential for tracking and quantifying effluent emissions. •The Fire Propagation Apparatus (FPA) was successfully modified to enable samples of timber, polymethyl methacrylate (PMMA) and polystyrene to decompose at a constant mass loss rate (MLR).•A constant mass loss rate (2 g s−1) enabled a representative means of monitoring pyrolysis emissions via a combination of spectroscopic techniques.•The combination of Fourier-transform infrared spectroscopy (FT-IR) and gas chromatography – mass spectrometry (GC-MS) facilitated the adjustment of effluent yields to increase sample representation.•Timber samples were shown to require a lower heat flux to maintain the same constant mass loss rate (2 g s−1) under oxidative environments, confirming that secondary processes such as charring were occurring alongside pyrolysis.