Alkali metal salt-assisted low-temperature pyrolysis of reconstituted tobacco sheets: research into salt addition, and reaction kinetics

Recent years have witnessed major advances in heated tobacco products. However, optimizing the aroma release and smoke generation of these products remains a formidable challenge. Alkali metal salts have emerged as effective catalysts for pyrolysis, demonstrating the dual benefits of enhanced catalytic efficiency and alleviating coke deposition. To effectively illustrate the effect of adding salt on the low-temperature catalytic pyrolysis performance of reconstituted tobacco sheets, thermogravimetric analysis and pyrolysis gas chromatography–mass spectrometry analyses were carried out, and the Flynn–Wall–Ozawa method and the Kissinger method were also applied to calculate reaction kinetics. The addition of the sodium (Na) salt or potassium (K) salt in reconstituted tobacco sheets was observed to significantly decrease the temperature corresponding to the maximum weight loss rate and increase the total weight loss with the range of 100–300 °C. Meanwhile, the content of key components in the pyrolysis gas gradually increased, indicating that the ability to catalyze cellulose and lignin pyrolysis improved. The results of dynamic analysis show that the apparent activation energy of reconstituted tobacco sheets decreased by an average of 80.95 or 49.12 kJ·mol−1 after adding Na or K salt when the conversion rate was 0.1–0.8. The approach reported herein not only exhibits a fundamental advance in the low-temperature pyrolysis of reconstituted tobacco sheets for heated tobacco products but also increases the concentration of pyrolysis gas and aromatic substances.