Recycling by pyrolysis of thermoset composites: characteristics of the liquid and gaseous fuels obtained

A sheet moulding compound (SMC) of fibre-glass and ortho-phthalic polyester has been pyrolysed in a laboratory installation at 300, 400, 500, 600 and 700°C for 30 min. Solid residues of 72–82 wt%, gas yields of 6–12 wt% and liquid yields of 9–13 wt% were obtained. No significant influence of temperature was observed over 400°C, however, there certainly was influence under 400°C, both in pyrolysis yields and in the composition and characteristics of the liquids and gases obtained. The pyrolysis liquids are a complex mixture of C5–C20 organic compounds, mainly aromatic and with numerous oxygenated compounds. They have high gross calorific values (34–37 MJ kg−1) and are non-polluting liquid fuels. About 40% weight of such liquids could be used as petrol and the remaining 60% could be mixed with fuel oils. The gas fraction produced is very rich in CO and CO2. Consequently, its gross calorific values are rather low (13.9–16.4 MJ m3 N); however, it can have energy source to self-sustain the process.