Pyrolysis performance, kinetic, thermodynamic, product and joint optimization analyses of incense sticks in N2 and CO2 atmospheres

Abstract Thermogravimetric and pyrolysis-gas chromatography/mass spectrometry analyses were performed to quantify the pyrolysis performances, kinetics, thermodynamics, products and optimization of incense sticks (IS) in N 2 and CO 2 atmospheres at five heating rates. The increased heating rate caused a lagged IS pyrolysis, moving its curves to a higher temperature. According to four model-free methods, activation energy estimates ranged from 34.17 to 439.19 kJ· mol −1 and 28.46–187.34 kJ· mol −1 in the N 2 and CO 2 atmospheres, respectively. The three-dimension diffusion (spherical symmetry) (D3) was determined using the Horowitz-Metzger method as the most probable degradation mechanism in both atmospheres. The main pyrolytic products were found as benzene and its derivatives whose mass accounted for 49.94% of the total 18 products. Significant two-way interaction effects were found between temperature, heating rate, and atmosphere type on the three responses of remaining mass, derivative thermogravimetry, and differential scanning calorimetry ( p  = 0.001). The best joint optimization was obtained at 899.5 °C with the heating rate of 5 °C·min −1 in the CO 2 atmosphere and was more sensitive to the increased heating rate in the N 2 than CO 2 atmosphere.