Studies on individual pyrolysis and co-pyrolysis of peat–biomass blends: Thermal decomposition behavior, possible synergism, product characteristic evaluations and kinetics

Abstract

Chemical reaction engineering of pine branches and peat is crucial yet challenging in enhancing pyrolysis products quality for the synergistic effect and kinetic parameters distribution. Herein, the three-phase product yield and tar component distribution were studied through a series of characterization methods. Thermogravimetric analysis (TGA) data at different heating rates was obtained and synergistic effect in the CPBP were discussed. Through the three kinetic models to calculate the obtained TGA data and determine the kinetic parameters. The characteristics of mass loss from individual pyrolysis and co-pyrolysis registered in TGA during temperature programmed heating is attributed mainly to devolatilization of volatile fragments, and the heating rate and the mixing ratio of the samples experienced significant change on the weight loss. A weaker interaction in the process of co-pyrolysis of pine branches and peat (CPBP) is observed under the condition of multiple factors investigated in this work. The pyrolysis temperature is lower than 400 °C, the volatiles are not released in time, and remain in the pores of the pyrolysis char, which increases the yield difference of char. The relative abundance of the number of substituents in the monocyclic aromatic structure in tar is C3 < C0 < C1 < C2. The relative abundance of two methyl groups in the benzene series in tar exhibited the largest value, as indicated from GC–MS results. Conventional gas products such as H2O, CO2, CO, CH4 and H2 were detected. The activation energy was not a constant value, but changed with the progress of the reaction, indicating that the decomposition reaction mechanism changed as the reaction progressed. The activation energy and linear correlation determined using the KAS and FWO methods were higher. The aforementioned methods were more appropriate and reliable for the thermo-kinetics studies in CPBP.