Template removal in MCM-41 type materials by solvent extraction: Influence of the treatment on the textural properties of the material and the effect on its behaviour as catalyst for reducing tobacco smoking toxicity

In this work a series of MCM-41 catalysts have been prepared by eliminating the template by calcination and by different extraction treatments. The extracted samples were also calcined and aluminium ion exchanged. A hydrothermal stability test of the final materials has also been performed. N2 adsorption isotherms, NH3 thermal desorption, X-ray fluorescence, X-ray diffraction, 27Al NMR and thermogravimetry of each material have been determined in order to establish the influence of the procedure used for template elimination on the physicochemical and textural properties of the material. Moreover, the ability of the different catalysts prepared for reducing the toxicity of the mainstream smoke evolved when cigarettes are smoked has been checked too. The results obtained show that the final properties of the catalyst depend noticeably on the experimental conditions used in the template extraction process (i.e., the solvent selected, the solvent:catalyst ratio, the temperature, the contact time and the number of successive extraction steps). Thus, the adequate selection of such conditions permits a material to be obtained with properties very similar to that of the calcined MCM-41 material. As a conclusion, the material showing the best properties, among the catalysts studied in this work, produces a mean reduction of the yield of the different compounds analyzed in the gases and in the condensed products retained in the filters and in the traps of around 35%, 75% and 45%, respectively, which are slightly higher than the values corresponding to the calcined MCM-41 used as reference (i.e., 25%, 56% and 40%, respectively). These reductions results in an increase of the amount of ashes of around 2 mg/cigarette due to the presence of the catalyst.

► Template elimination with solvent was studied as an alternative to the calcination.
► Textural properties of resultant materials were analyzed by N2 adsorption isotherms.
► The role of the catalysts in order to reduce tobacco toxicity was studied.
► The material prepared by extraction with H2O2 presents the best effects.