High surface area mesoporous titanium phosphate: synthesis and surface acidity determination

Citation
Dj. Jones et al., High surface area mesoporous titanium phosphate: synthesis and surface acidity determination, J MAT CHEM, 10(8), 2000, pp. 1957-1963
Citations number
56
Categorie Soggetti
Apllied Physucs/Condensed Matter/Materiales Science","Material Science & Engineering
Journal title
JOURNAL OF MATERIALS CHEMISTRY
ISSN journal
09599428 → ACNP
Volume
10
Issue
8
Year of publication
2000
Pages
1957 - 1963
Database
ISI
SICI code
0959-9428(2000)10:8<1957:HSAMTP>2.0.ZU;2-7
Abstract
A mesoporous form of titanium phosphate has been prepared by reaction betwe en phosphoric acid solution and either titanium propoxide or titanium chlor ide in the presence of trimethylammonium surfactants. The surfactant can be almost completely removed by extraction using acidified ethanol. The surfa ce area of the extracted samples depends closely on the pH of the reaction medium, and the reaction temperature, and the highest surface areas, around 740 m(2) g(-1) were obtained for materials prepared at pH 3. This surface area is partially lost when the extracted titanium phosphate is calcined, a lthough the mesoporous character is retained. P-31 NMR spectroscopy shows t he ethanol-extracted sample to be rich in hydrogen phosphate (HPO42- and H2 PO4-) groups, which undergo partial condensation after calcination. These h ydrogen phosphate groups are responsible for the high surface acidity deter mined, and for its evolution after calcination: the total numbers of surfac e acidic sites of ethanol-extracted titanium phosphate and calcined titaniu m phosphate, evaluated using two-cycle adsorption of ammonia from the gas p hase at 80 degrees C, are 900 and 340 mu mol g(-1) respectively.