Pyrolysis of pellets made with biomass and glycerol: Kinetic analysis and evolved gas analysis

Glycerol is a co-product compound of biodiesel production with an interesting heating value. In this work pyrolysis kinetic parameters for a pellet made with a mass fraction of 90% sawdust and a mass fraction of 10% glycerol are derived through thermogravimetric analysis. A new parallel reaction scheme with four components (cellulose, hemicellulose, lignin and glycerol) is adopted and the kinetic triplet for each component is derived using a model fitting approach applied to this particular kind of pellet. The isoconversional Method Kissinger-Akahira-Sunose is employed both to provide initial values for model fitting simulations and to check final results. Results show that activation energies and pre-exponential factors are respectively: 149.7 kJ ma(-1) and 1.98*10(11) s(-1) for hemicellulose, 230.1 kJ mol(-1) and 1.84*10(17) s(-1) for cellulose, 154.3 kJ mol(-1) and 5.14*10(9) s(-1) for lignin, 74.5 kJ mol(-1) and 2.17*105 s(-1) for glycerol with a first reaction order for all components, except for lignin (n = 2.6). Through evolved gas analysis it was demonstrated that the thermal degradation of glycerol contained in the pellet can increase hydrogen content in pyrolysis gases. (C) 2016 Elsevier Ltd. All rights reserved.