Synthesis, characterization, and base-catalytic performance of ordered mesoporous aluminophosphate oxynitride materials
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Liua) State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Shanghai 20050, People’s Republic of China (Received 14 March 2007; accepted 23 April 2007)
The synthesis, physicochemical characterization, and catalytic evaluation of ordered mesoporous aluminophosphate oxynitride (MAPN) materials are presented here. The solid-base materials were prepared through treating aluminophosphate with an ordered mesostructure with ammonia at high temperatures. The MAPNs are well ordered, and possess high surface and pore volume. The amount of nitrogen incorporated increased with prolonged nitridation times. At the same time, the intensity of basicity is consistent with the nitrogen content, which is affirmed by Knoevenagel condensation reaction. The obtained ordered MAPN materials also possess acidity. The easy preparation and control of the nitrogen content of ordered MAPN materials, providing acidity and basicity, make them attractive as alternatives to a solid-base or acid-base catalyst, especially for the interactions of large molecules. I. INTRODUCTION
Solid-acid catalysts have been extensively applied in the petrochemical and fine chemical industries, but the application of solid bases is relatively undeveloped.1–3 In the 1990s, it was found that the incorporation of nitrogen was an effective way to synthesize newly solid basic materials, which are environmentally benign. Thus, much attention was paid to oxynitride materials. Silicon oxynitrides were prepared and characterized.4–6 They were successfully used in Knoevenagel condensation. Afterward, quaternary oxynitride systems were developed. AlPON,7–10 ZrPON,11–13 and AlGaPON14,15 were prepared by treating the precursors in flowing ammonia at high temperatures, and their physicochemical characteristics and acid-base properties were also studied.16–22 In recent years, much attention has been focused on the preparation of shape- or size-selective mesoporous solids for application as, for instance, catalysts or catalyst supports. The majority of these mesoporous materials are oxides and phosphates, such as silicates, zirconia, titania, alumina, aluminophosphate, and zirconium oxophosphate.1 To extend their applicability, many efforts are
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Address all correspondence to this author. e-mail: [email protected] DOI: 10.1557/JMR.2007.0436 3330
http://journals.cambridge.org
J. Mater. Res., Vol. 22, No. 12, Dec 2007 Downloaded: 15 Mar 2015
made to modify these mesoporous materials by postsynthesis grafting or direct synthesis. In 2001, Haskouri and co-workers,23 illumined by the synthesis of amorphous silicon oxynitrides,4–6 made ordered mesoporous silicon oxynitride materials by nitriding mesoporous silica MCM-41 in flowing ammonia. Later, Xia and Mokaya,24,25 and Liu and co-workers26–29 synthesized a series of ordered mesoporous silicon oxynitrides using various mesoporous silicas, such as MCM-48, MCM-41, SBA-15, and mesoporous silica films as precursors. And the stability and base-catalytic activity for Knoe
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