Thermal decomposition of tobacco/glycerol/SBA-15 mixtures in nitrogen and air atmospheres
During cigarette smoking, complex chemical and physical processes take place, and these may depend on the temperature and the oxygen availability in the different zones of the cigarette. Numerous efforts have been carried out to model the complex processes involved in tobacco smoldering.
In the present work, the effect of SBA-15 zeolite catalyst on the qualitative composition of the gases evolved in the pyrolysis of tobacco and tobacco-glycerol mixtures was studied by TGA/FTIR under N2 and air atmospheres. The behavior of nicotine and tobacco-nicotine mixtures in the absence and the presence of SBA-15 was also studied.
In an inert atmosphere, the addition of SBA-15 does not noticeably change the temperature of the maximum decomposition rate of the main decomposition events. Nevertheless, the relative weight loss involved in the reaction steps associated with the glycerol loss and hemicellulose, cellulose, lignin and other events seems to decrease. The evolution with temperature of the more significant IR bands of the gases evolved (water, carbonyl compounds, alcohols and ethers, CO and CO2 aromatics, methane and methyl group-containing compounds) shows interesting reductions of some compounds in certain temperature ranges as a consequence of the addition of catalyst. Nicotine is also noticeably affected by the catalyst under pyrolysis conditions.
The use of an oxidizing atmosphere produces noticeable modifications in the thermal processes studied, thus appearing a significant weight loss associated with oxidation processes. The catalyst decreases the relative weight loss involved in most of the decomposition steps of tobacco, and also shifts these oxidizing processes to higher temperatures. Moreover, the presence of glycerol strongly modifies the behavior of the samples, especially the last steps of the oxidation of the residues.
Acknowledgements - Financial support for this investigation has been provided by the Spanish “Secretaría de Estado de Investigación” del Ministero de Economia y Competitividad (MAT2011-24991) and by the Generalitat Valenciana (PROMETEO/2012/015).