Experimental and Kinetic Studies on Tobacco Pyrolysis under a Wide Range of Heating Rates

In the present work, experimental and kinetic studies are conducted to explore and model tobacco pyrolysis characteristics under a wide range of heating conditions. First, thermal decomposition processes of a tobacco sample were investigated using thermogravimetric analysis/difference thermogravimetry (TGA/DTG) experiments under a wide range of heating rates (10-500 K/min), and the TGA/ DTG profiles were compared to highlight the effect of heating rate on the pyrolysis characteristics. The results showed that the tobacco sample was sufficiently devolatilized at 1173.15 K (900 degrees C) and the final volatiles yields were not sensitive to the heating rate. Moreover, it was illustrated that the DTG curve presents a polymerization trend with the increase in heating rate. Then, kinetic parameters, including total component mass fraction, preexponential factor, and activation energy, were derived by deconvolution from TG/DTG profiles for each component with a one-step kinetic framework, and the correlations between kinetic parameters and heating rates were further explored and modeled. The results illustrated that four subpeaks can be found in the deconvolution, indicating the four components (volatile components, hemicellulose, cellulose, and lignin). In addition, the activation energy of each component was found to be insensitive with heating rate (with standard deviation less than 20%). Therefore, an average activation energy was used for each component to avoid the compensation effect and a power correlation between the heating rate and the preexponential factor could be found. A posteriori analysis also confirmed the validity of this correlation.

Automated summary

The study conducted experimental and kinetic research to investigate and model tobacco pyrolysis characteristics under a wide range of heating conditions. Results showed that tobacco was sufficiently devolatilized at high temperatures and final volatiles yields were not significantly impacted by heating rate, while DTG curve displayed a polymerization trend with increasing heating rate. Additionally, the study derived kinetic parameters and found that activation energy of each component was insensitive to heating rate, leading to the establishment of a power correlation between heating rate and preexponential factor.