Evaluation of straw with absorbed glycerol thermal degradation during pyrolysis and combustion by TG-FTIR and TG-GC/MS

Despite the interest in second generation biofuels produced from straw, an increased attention on the by-products (glycerol) of the biodiesel production still remains. With the increase of biodiesel production year by year, new possibilities for glycerol utilization attract more attention. One possible use of glycerol is as a binder material for straw or other biomass pellets production. Thermal behaviour of straw pellets containing 0 and 14 wt% of glycerol was analysed using a Netzsch STA 449 F3 Jupiter thermal analyser. The scope of this work is investigation of formation and development of the most toxic carbonyl group compounds (with special focus on acrolein, propane, formaldehyde, acetaldehyde) during combustion and thermal destruction of straw pellets depending on the absorbed amount of raw glycerol, atmosphere and heating rate by thermogravimetric (TG) and evolved gas analysis (TG-FTIR and TG-GC/MS) methods. Possible pathways of main carbonyl products formation were analysed. Evolved gas analysis by Fourier transform infrared spectroscopy (FTIR) and Gas chromatography-mass spectrometry (GC/MS) methods revealed the maximum absorbance of alcohol at the wavelength of 1055 cm−1 and the increasing abundance of ion current of m/z = 61 which corresponds mainly to glycerol. Besides, analysis of the formation of aldehydes showed that the addition of the glycerol to the straw does not stimulate the excessive formation of toxic and unwanted emissions.