Flash induction calcination: A powerful tool for total template removal and fine tuning of the hydrophobic/hydrophilic balance in SBA-15 type silica mesoporous materials Taissire Benamor, Laure Michelin, Bénédicte Lebeau ⇑ , Claire Marichal Equipe Matériaux à Porosité Contrôlée (MPC), Institut de Science des Matériaux de Mulhouse (IS2M), LRC CNRS 7228, Université de Haute Alsace, ENSCMu, 3 rue Alfred Werner, 68093 Mulhouse Cedex, France article info Article history: Received 12 May 2011 Received in revised form 5 July 2011 Accepted 6 July 2011 Keywords: Mesoporous silica SBA-15 Surfactant removal Induction calcinations Hydrophobic/hydrophilic balance abstract A new rapid calcination method has been used to completely remove the organic template from SBA-15 ordered mesoporous silica, and to preserve a high number of silanol in these materials. This calcination method provided by an induction furnace was found to considerably reduce the calcination time and therefore the energy consumption associated. Moreover, adjustment of both calcination temperature and duration allowed tuning the hydrophobic/hydrophilic balance of the mesoporous SBA-15 silica mate- rials. For comparison, short and long time conventional muffle furnace calcination was performed. The induction calcination was also successfully applied to different type of mesoporous silica materials such as SBA-16 and MCM-41. Ó 2011 Elsevier Inc. All rights reserved. 1. Introduction Ordered Mesoporous Silica (OMS) materials are obtained from molecular silica source in solution by a templating route with amphiphilic molecules or polymers [1,2]. Depending on the synthesis conditions well organized array of mesopores is ob- tained. Their numerous applications in catalysis [3] for example rely on their structural, textural and porosity characteristics such as high specific area (from 500 to 1500 m 2 g 1 ) and a large monodisperse pore size (from 20 to 150 Å), which require to release the porosity filled by surfactant molecules. Several methods have been suggested in the literature to remove the organic template occluded within the pores such as calcination [4,5] and/or chemical extraction by an organic solvent under reflux [6–10], microwave digestion [11] or ultraviolet radia- tion [12,13]. Most of them present drawbacks: chemical extraction is often incomplete and calcination modifies the textural and hydrophilic/hydrophobic properties of the OMS since high temper- ature (typically P500 °C) and long time treatment (P4 h) are required for inducing shrinkage and dehydroxylation of the silica network. Moreover, most of these processes are lengthy and energy consuming. A fast procedure for complete surfactant extraction from silica MCM-41 type materials was suggested by Lang et al. [10]. Perform- ing three successive treatments of 15 min each using ethanolic solution of ammonium nitrate at 60 °C enable surfactant elimina- tion. Filtration and washing with cold ethanol was done between each extraction. Surfactant extraction was checked by Fourier Transformed InfraRed spectroscopy (FT-IR). A microwave digestion process was suggested by Tian et al. [11] as a rapid method (2 min of microwave treatment) for an almost complete removal of the surfactant. However, 13 C CPMAS NMR analysis of samples treated according to this procedure revealed the presence of characteristic resonances of the surfactant (our own work). In addition the use of concentrated acid and H 2 O 2 at such elevated temperature could be very hazardous and involves a multistep procedure (filtration, drying...). As already mentioned by Yang et al. [7] chemical extraction- based methods fail to remove the P123 template completely. For these reasons they developed another step by step method to empty the bimodal pore system of SBA-15 [6]. The mesoporous channels are first vacated by decomposition of the triblock copoly- mer template via ether cleavage with sulphuric acid. Then the occluded Ethylene Oxide (EO) chains in the pore walls which are not accessible to the acid can be thermally decomposed by calcina- tion at 200 °C for 6 h to generate the microporosity [7]. This multistep strategy is time consuming and consequently other methods for template removal in OMS are highly desirable. 1387-1811/$ - see front matter Ó 2011 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2011.07.004 ⇑ Corresponding author. Tel.: +33 3 89 33 68 82; fax: +33 3 89 33 68 85. E-mail address: Benedicte.Lebeau@uha.fr (B. Lebeau). Microporous and Mesoporous Materials 147 (2012) 334–342 Contents lists available at ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso