Copyright WILEY-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany, 2014. Supporting Information for Adv. Mater., DOI: 10.1002/adma.201404493 Micro/Macroporous System: MFI-Type Zeolite Crystals with Embedded Macropores Albert G. Machoke, Ana M. Beltrán, Alexandra Inayat, Benjamin Winter, Tobias Weissenberger, Nadine Kruse, Robert Güttel, Erdmann Spiecker, and Wilhelm Schwieger*
Copyright WILEY-VCH Verlag GmbH & Co. KGaA, 69469 Weinheim, Germany, 2013. Supporting Information Micro/Macroporous System: MFI-type zeolite crystals with embedded macropores Albert G. Machoke, Ana M. Beltrán, Alexandra Inayat, Benjamin Winter, Tobias Weissenberger, Nadine Kruse, Robert Güttel, Erdmann Spiecker & Wilhelm Schwieger* *Correspondence to: Wilhelm Schwieger e-mail: wilhelm.schwieger@crt.cbi.uni-erlangen.de Author(s), and Corresponding Author(s)* Synthesis of mesoporous silica particles (MSPs) The starting MSPs were prepared by a modified procedure reported in the literature. [1] In a typical procedure, cetyltrimethylammonium bromide (CTAB) (6 g, 98 %, Sigma Aldrich) was dissolved under vigorous stirring in distilled water (828 ml) and ethanol (2880 ml, 96 %, technical grade). After 10 minutes of stirring, ammonium water (144 ml, 25 wt. %, Merck) was added and allowed to stir further at room temperature for 1 h. Then, tetraethyl orthosilicate (TEOS) (20 ml, 98 %, Alfa Aesar) was added to form a clear solution with molar composition of 1 TEOS: 21 NH 3 : 0.18 CTAB: 540 ethanol: 584 H 2 0. This solution was further stirred at room temperature for 2 h. Then, the obtained white precipitate was separated by centrifugation and dried at 348 K overnight. Finally, CTAB was removed from the assynthesized MSPs via calcination at 823 K for 6 h under flowing air (120 ml/min). Characterization 1
XRD patterns were measured using a Phillips diffractometer equipped with a Cu-Kα X-ray tube (40 kv, 40 ma). The textural properties of MSPs and calcined macroporous zeolites were determined by N 2 -physisorption at 77 K on an Autosorb-1-MP system (Quantachrome Instruments). Pre-treatment of all samples was performed under high vacuum at 573 K for 12 h. The specific surface area was obtained by using the Brunauer Emmett Teller (BET) equation at relative pressure p/p 0 values below 0.2. Pore size distribution was obtained by using the DFT kernel for N 2 -adsorption at 77 K cylindrical silica pores. The total pore volume was estimated at p/p 0 of 0.99. Scanning electron microscopy (SEM) images were taken using a Carl Zeiss ULTRA 55 microscope at a voltage between 1.5 and 3 kv without any sample pre-treatment. For transmission electron microscopy (TEM) studies, the sample was dispersed in ethanol onto a 200 mesh lacey carbon copper grid and dried overnight. Conventional transmission electron microscopy (CTEM) and selected-area electron diffraction (SAED) patterns have been recorded with a Phillips CM30 transmission electron microscope operated at an acceleration voltage of 300 kv. Annular dark-field (ADF) scanning transmission electron microscopy (STEM) imaging and STEM tomography were performed using a FEI Titan 3 80-300 microscope operated at 200 kv. The semi-convergence angle of the electron beam was selected to have an optimized depth of field, using the so-called microprobe mode, [2] so that the full particle was in focus throughout the entire tilt series acquisition procedure. The ultrathin single-tilt tomography holder from Fischione (model 2020) was used to acquire the tilt series for the three-dimensional (3D) reconstruction with tilt angles ranging from -70 to + 72 in a continuous tilting scheme (tilt-angle increments 1-2 ). The software Xplore3D from FEI was employed for the automated acquisition of the tilt series. FEI Inspect 3D software was used to align the images of the tilt series by cross-correlation and to reconstruct the tomograms using the Simultaneous Iterative Reconstruction Technique [3] (SIRT) (50 2
iterations) algorithm. The final 3D visualization of the dataset was performed with the Amira ResolveRT software (Visualization Sciences Group). Porosity and pore size measurements were determined using Image J version 1.46 64 bit (Plugin BoneJ version 1.3.10 [4] ) and Avizo for FEI systems 8.1 from FEI Visualization Sciences Group. Therefore, adaptive local thresholding (manually determined) of regions of constant contrast and manual segmentation were applied. Supplementary Figure S1. Porosity of MSPs and microporosity of the macroporous zeolite crystals. a-b, N 2 -sorption isotherms and pore size distribution of the MSPs measured at 77 K. a, N 2 - sorption isotherm of MSPs displaying the characteristic isotherm for mesoporous materials. b, N 2 -sorption isotherm of the macroporous zeolite crystals measured at 77 K indicating the presence of a microporous walls in the final products. These macroporous crystals were found to have a BET specific surface area of 458 m 2 /g and a total micropore volume (DR-method) of 0.169 ml/g. 3
Supplementary Figure S2. Preparation of macroporous zeolite crystals from MSPs. a-d, Schematic representation of the different steps involved during the preparation of macroporous zeolite crystals. a, preparation of MSPs followed by the impregnation with TPAOH solution (b). c, transformation of the impregnated MSPs under SAC and the final micro-macroporous products (d). Supplementary Video 1 Surface rendering (parallel view) of 3D reconstruction (STEM tomography) of an isolated open porous zeolite crystal (cf. Figure 3). Supplementary Video 2 3D visualization (perspective view; box size 1887 x 727 x 1540 nm³) of inner pore space (yellow/red surface and volume rendering) and zeolite phase (green volume rendering) of the same reconstructed particle (cf. Figure 3 b) most of the pores are interconnected. Supplementary Video 3 4
Animated slide through the XY planes of the reconstructed volume of the zeolite particle (717 slices). The superimposed cuboid shape of the zeolite crystal can be seen as well as the macropores inside the crystal. References [1] Q. Gao, Y. Xu, D. Wu, Y. Sun, X. Li, The Journal of Physical Chemistry C 2009, 113, 12753. [2] J. Biskupek, J. Leschner, P. Walther, U. Kaiser, Ultramicroscopy 2010, 110, 1231. [3] P. Gilbert, Journal of Theoretical Biology 1972, 36, 105. [4] M. Doube, M. M. Kłosowski, I. Arganda-Carreras, F. P. Cordelières, R. P. Dougherty, J. S. Jackson, B. Schmid, J. R. Hutchinson, S. J. Shefelbine, Bone 2010, 47, 1076. 5