An improved calcination route to obtain high quality mesoporous aluminophosphates materials
Introduction
Mesoporous aluminophosphates materials show great promise as catalysts, catalyst supports and adsorbents [1], [2], [3], [4], [5]. In a variety of bulky organic molecules involved reactions at elevated temperatures, highly stable meso-AlPO materials are needed [1]. Though well-developed mesostructured aluminophosphates can be obtained in the synthesis process, a significant collapse of the mesostructures is usually observed after the removal of organic templates by conventional calcination method [6]. The negative effect in the calcination process may be ascribed to the uncompleted condensation in the pore walls of the mesostructures [7], [8], [9]. Therefore, the removal of templates is critical to obtain highly condensed structure of meso-AlPO materials.
In addition to the conventional calcination method, solvent extraction has also been used to remove the templates from the meso-AlPO in an attempt to avoid the collapse of the pore structures [10]. However, the extraction method is effective only to remove neutral templates, but not the cationic templates.
Here, we report a novel calcination approach to manipulate the decomposition of the cationic templates in the pores of meso-AlPO materials for obtaining high quality mesoporous aluminophosphates.
Section snippets
Synthesis of mesoporous AlPOs
Mesoporous AlPOs materials were synthesized by using cetyltrimethylammonium bromide (CTAB) in the presence of tetramethylammonium hydroxide (TMAOH) at room temperature. The procedure is described as follows: 3 g aluminium triisopropoxide (99.8%) was added into 18 g water under stirring. When the slurry became homogeneous, phosphoric acid (85 wt.%) was added. The mixture was vigorously stirred for 1 h. Then a solution of CTAB was added with stirring. After 1 h, an aqueous solution of TMAOH
Result and discussion
The XRD patterns of the as-synthesized meso-AlPO sample and its calcined products at different stages are shown in Fig. 1. A well-ordered hexagonal feature in the as-synthesized sample is observed (Fig. 1a). Heat treatment of the sample at 140 °C leads to an improvement on the degree of the structural condensation, as evidenced by the enhanced d100 reflection (Fig. 1b). In the second stage, quickly increasing temperature from 200 to 360 °C results in the disappearance of d110 reflection of the
Conclusion
The calcination is a key factor in determining the mesostructural stability of the meso-AlPO materials. The three-stage temperature-programmed calcination method provides a new route to remove the templates from mesostructured AlPO materials and to obtain a thermally stable and long-range ordered hexagonal mesoporous structure. This approach is an easy and effective way to obtain high quality mesoporous AlPO materials, and may be extended to the preparation of other kinds of mesoporous
Acknowledgements
The authors acknowledge the financial supports from the NSFC (20503003, 20333030), the Education Ministry of China (20030141026), NCET, and CNPC Innovation Foundation.
References (16)
Microporous Mesoporous Mater.
(2005)- et al.
J. Mol. Catal., A Chem.
(2004) - et al.
Microporous Mesoporous Mater.
(1998) - et al.
Microporous Mesoporous Mater.
(2001) - et al.
Microporous Mesoporous Mater.
(2005) - et al.
Chem. Commun.
(1997) - et al.
Mater. Chem. Phys.
(2002) - et al.
Chem. Commun.
(1997)
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