Highly ordered, thermally/hydrothermally stable cubic Ia3d aluminosilica monoliths with low silica in frameworks Sherif El-Safty a,⇑ , Ahmed Shahat a , Kazuyuk Ogawa a , Takaaki Hanaoka b a Materials Research Laboratories for Energy and Environment, National Institute for Materials Science (NIMS), 1-2-1 Sengen, Tsukuba-shi, Ibaraki-ken 305-0047, Japan b Research Center for Compact Chemical System, National Institute of Advanced Industrial Science and Technology (AIST), 4-2-1 Nigatake, Miyagino-ku, Sendai 983-8551, Japan article info Article history: Received 15 May 2010 Received in revised form 16 July 2010 Accepted 29 September 2010 Available online 23 October 2010 Keywords: Monoliths Cubic Ia3d Aluminosilica Thermal/hydrothermal steam stabilities abstract High order aluminosilica monoliths (Al/HOM-5) with cubic Ia3d structures were fabricated with low sil- ica content (Si/Al = 1) by means of a simple, reproducible, and one-pot synthesis strategy. A realistic con- trol over the cubic Ia3d geometry of aluminosilica monoliths was achieved by using microemulsion phases of copolymer P123 (EO 20 PO 70 EO 20 ) as soft templates. The textural and geometrical pore structures and acidic properties of Al/HOM-5 were characterized by means of various tools of XRD, N 2 isotherms, HRTEM, FTD, FESEM, 27 Al and 29 Si MAS NMR, EDX, and NH 3 -TPD. The incorporated amounts of Al species in Al/HOM-5 monoliths play a key determinant in the formation of the coordination state of the alumi- num species in four (Al IV , AlO 4 )-, five (Al V , AlO 4 )-, and six (Al VI , AlO 6 )-coordinate environments. Results show evidence of the formation of aluminosilicas with disordered distribution of Si and Al sites in the frameworks. In addition, the increase of the aluminum contents enhanced the distortion in the pore uni- formity of Al/HOM-5 monoliths. The large amount of acid sites was revealed with the high aluminum contents into the pore framework walls. With high-temperature treatments (P1073 K), the c-Al 2 O 3 phase with face-centered-cubic Fd3m symmetry can be formed in the monolithic aluminosilica matrices. This finding might indicate that the dealumination effect at high thermal treatment would be expected to generate many defect sites existing in the Al/HOM-5 frameworks. Accordingly, a large mass transport of aluminum from tetrahedral aluminum (framework) to octahedral aluminum (extra framework) was occurred, leading to form a separate aluminum species into the crystalline alumina matrices. Moreover, cubic Ia3d aluminosilica structures exhibit outstanding steam stability even with high Al content (Si/ Al = 1). However, the mesostructured integrity of Al/HOM-5 can be retained under 100% steam treat- ments with N 2 flow for 8 h at 1073 K, permitting their desirability in various applications such as catal- ysis, adsorption, and sensing technologies. Ó 2010 Elsevier Inc. All rights reserved. 1. Introduction In recent years, there was a great deal of interest in the increase of the potential functionalities of mesoporous materials with high acidity, long-range periodicity, controllable pore sizes, high surface area (P1000 m 2 /g) and pore volumes, and thermal/hydrothermal framework stability [1–5]. A major advance in the area of synthesis of such precise functionality of materials was the incorporation of the heteroatoms in the natural silica network of mesoporous molecular sieves [6–10]. This can be useful for the design of mes- oporous solids with specially combined domains and distinctly desirable properties. Such mesoporous materials show promises in expanding the range of their application utilities in catalysis [7,11–13], photocatalysis [8], sensing [14] and adsorption [15]. Since the discovery of a novel class of the M41S family of mes- oporous molecular sieves, it was found that the incorporation of aluminum into the framework provides materials with acidic ac- tive sites [7,16,17]. These aluminosilica materials were reported to show an exciting range of catalytic applications, despite the existence of the structural disorder that is being similar to those amorphous alumina and aluminosilicas [16,18]. The acidity of these solid materials produced from cationic Brønsted or Lewis acid sites of tetrahedrally coordinated aluminum species ðAlO  4 Þ in the aluminosilica frameworks [2–7]. Significant key factors con- trolled the extent of acidity such as the fabrication strategy of alu- minosilicas, and the nature and amount of incorporated aluminum in the framework matrices. In principle, the acidity of aluminosili- cas results from the charge imbalance created by substitution of a Si 4+ atom by an Al 3+ atom in the silica-rich host lattice. The gener- ated AlO  4 units localize a negative charge, which could be compen- sated by a proton or a cation. Thus, the aluminosilicas acquire acidic and ion exchange properties [7,16,17]. It is reasonably 1387-1811/$ - see front matter Ó 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.micromeso.2010.09.030 ⇑ Corresponding author. E-mail address: sherif.elsafty@nims.go.jp (S. El-Safty). Microporous and Mesoporous Materials 138 (2011) 51–62 Contents lists available at ScienceDirect Microporous and Mesoporous Materials journal homepage: www.elsevier.com/locate/micromeso