Pyrolysis of poly-l-leucine under combustion-like conditions☆

The protein poly-l-leucine has been used as a model compound for the nitrogen in biomass fuels. It was pyrolysed in a fluidised bed at 700 and 800 °C and the pyrolysis gases were analysed with a FT-IR spectrometer. HCN, NH3 and HNCO were identified as the main nitrogen-containing species, while neither NO nor N2O were found among the pyrolysis gases. At 700 °C, as much as 58% of the nitrogen content was converted into HCN and 31% into NH3. The HCN/NH3 ratio increased from about 1.9 at 700 °C to above 2.2 at 800 °C. Pyrolysis of another protein, poly-l-proline, at 800 °C gave a HCN/NH3 ratio close to 10. This revealed that the proteinʹs amino acid composition has a marked impact on the composition of the pyrolysate.