Products distribution and gas release in pyrolysis of thermally thick biomass residues samples

The pyrolysis of thermally thick (approximately 75 g) biomass residues samples (i.e. brewer spent grains, fibreboard and coffee beans waste) has been investigated in an in-house designed and fabricated macro-TGA both by rapid sample introduction at reactor temperatures from 600 to 900 °C and by applying a constant heating rate of 10 K/min. The composition of the product gas is determined by simultaneous online use of a micro-GC and a FTIR analyser. The product yields (liquid, char and gas) and the gas composition show a clear dependence on temperature and heating rate. The main gas products are CO₂, CO, CH₄, H₂, C₂H₂, C₂H₆ and C₂H₄. The results show that a rise in temperature leads to increasing gas yields and decreasing liquid and char yields. Lower heating rates favour liquid and char yields. The release patterns of the gaseous species are also greatly affected by the temperature history of the sample.