1. 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. © Surface Investigation On Thermal Stability Of Tungstophosphoric Acid Supported On MCM-41 Using Synchrotron Radiation Jalil, PA; Tabet, N; Faiz, M; Hamdan, NM; Hussain, Z ELSEVIER SCIENCE BV, APPLIED CATALYSIS A-GENERAL; pp: 1-6; Vol: 257 King Fahd University of Petroleum & Minerals http://www.kfupm.edu.sa Summary The surface of supported tungstophosphoric acid H3PW12O40 (HPW) on all-silica MCM-41 has been investigated using high-resolution X-ray photoelectron spectroscopy (XPS) and X-ray absorption near edge structure (XANES). The results show the interaction between HPW and MCM-41 upon impregnation. Nuclear magnetic resonance (NMR) spectroscopy results also seem to confirm the above conclusion. Heating the supported acid increased the structural damage of HPW and MCM-41. Our results also suggest the formation of tungsten oxides on the surface upon heat treatment at 400 degreesC. A detailed analysis of the infrared (IR) spectra showed a gradual increase in the absorbance of the W-O-W corner shared vibration relative to the absorbance of the other bands. This indicates that the symmetry, and hence the stability of the bulk molecules were also decreased upon heating. (C) 2003 Elsevier B.V. All rights reserved. References: BLASCO T, 1998, J CATAL, V177, P306 BRANTON PJ, 1994, J CHEM SOC FARADAY T, V90, P2965 CHAKRABORTY B, 1999, CATAL TODAY, V49, P253 CORMA A, 1994, J CATAL, V148, P569 CORMA A, 1995, CHEM REV, V95, P559 CORMA A, 1997, CHEM REV, V97, P2373 COUSTEL N, 1994, J CHEM SOC CHEM COMM, P967 DIAS JA, 1999, J CATAL, V183, P83 DRAGO RS, 1997, J AM CHEM SOC, V119, P7702 HUNGER M, 1999, MICROPOR MESOPOR MAT, V27, P261 Copyright: King Fahd University of Petroleum & Minerals; http://www.kfupm.edu.sa

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