Catalytic effect of MCM-41 in the pyrolysis of tobacco and several substances used as additives in the preparation of commercial cigarettes

Abstract

The reduction of harm of tobacco is a matter of great interest for the health departments of several countries and for the WHO, which, recognizing that we are very far from the time where the tobacco is fully eradicated, tend to stablish policies and consider different measurements in order to develop harm reduced products [1]. In this way, the addition of pyrolysis/combustion catalysts as cigarette ingredients is a not much extended option, which has demonstrated its ability for reducing tobacco toxicity whereas keeping the organoleptic characteristics of the cigarettes [2]. Several studies focused on the use of MCM-41 as tobacco additive for reducing the toxicity of the smoke generated when tobacco is smoked showed the interesting properties of this catalyst for the above-mentioned purposes [3]. On the other hand, the importance of the knowledge of the effect of tobacco ingredients on smoke chemistry has been recognized, and the need of carrying out studies focused on the individual behavior of such ingredients in the smoking process has been pointed out [4]. In this work, the catalytic effect of a mesoporous MCM-41 on the pyrolysis of a reference tobacco and three substances widely employed as cigarette ingredients (two humectants: glycerol and sorbitol, and a flavor: sucrose) has been studied by thermogravimetric analysis. The catalytic pyrolysis of the mixtures tobacco-ingredient has also been analyzed. The results obtained showed that, in general, the catalyst has more influence on the evolution of the process (number and relative importance of the reaction steps) than in the temperature of reactions. Moreover, the analysis of the behaviour of the tobacco-ingredients mixtures has been revealed very complex, because the role of the catalyst may be different for each compound, and all the processes occur at very close temperatures. However, the MCM-41 catalytic effect on the studied ingredients is more noticeable than on tobacco. The main observations about the influence of the presence of MCM-41 on the materials studied in this work could be summarized as follows: Tobacco: decrease of the area of the peak which appears at around 200ºC and increase of the area of the peak appearing in the range 360-550ºC. Glycerol: the number of reaction steps increases from one to three overlapped steps. Sorbitol: decrease of the temperature of reaction and appearance of a slow decomposition step at higher temperatures. Sucrose: increase of the number of steps at low temperatures.