Characterization of Chromium Oxide Supported on Silica

• Autorzy: Jóźwiak W. , Ignaczak W. , Kincel D. , Góralski J. , Paryjczak T.
• Języki publikacji: EN

Abstrakty

EN

Thermal stability and redox behavior of the surface Cr-oxo structures supported upon silica were investigated by: TPR, TPO, XRD, IR and XPS techniques. During reduction in hydrogen, the surface Cr(VI) oxide phase is completely transformed into the Cr(III) oxidation state. For low loaded Cr/SiO2 samples almost fully reversible interconversion Cr(VI)Cr(III) was found during TPR - TPO cycling up to 900_C. For higher loaded samples, temperature depended oxygen - hydrogen cycling strongly influences the relative composition of chromium oxide phase supported on silica. The coexistence of three major forms of chromium oxide phase in supported CrO3/SiO2 system has been confirmed: monomolecularly dispersed chromates strongly bonded to silica surface, relatively inactive stable crystallites of _-chromia and intermediate metastable amorphous aggregates of CrO3. The relative contribution of each form strongly depends on the chromium content, method of preparation, treatment conditions (temperature, atmosphere and water traces). The anchoring of chromate-like species requires suitable support adsorption sites and their concentration is governed by hydroxyl group population. Mobile hydroxo species of CrO3 may migrate on the silica surface, anchoring to preferable adsorption sites and forming stable chromate-like species. It was also found that water is involved in the hydrolytic process of monochromated species destabilization, resulting in partial transition Cr(VI) _ Cr(III). Thermodynamically favored chromium sintering process, chromates CrO4 2_ _crystalline _-Cr2O3, requires water as destabilization agent for hydrolytic splitting of Cr - O - Si linkages and chromium oxide agglomeration.

Słowa kluczowe

EN

chromium oxide species; Cr/silica oxidation; temperature-programmed reduction (TPR); IR; XPS spectroscopy

• Wydawca: Polskie Towarzystwo Chemiczne
• Czasopismo: Polish Journal of Chemistry
• Rocznik: 2002
• Tom: Vol. 76 / nr 6
• Strony: 857--873
• Opis fizyczny: Bibliogr. 40 poz., rys.

Twórcy

autor

Jóźwiak W.

• Institute of General and Ecological Chemistry, Technical University of Łódź ul. Żwirki 36, 90-924 Łódź, Poland

autor

Ignaczak W.

• Institute of General and Ecological Chemistry, Technical University of Łódź ul. Żwirki 36, 90-924 Łódź, Poland

autor

Kincel D.

• Institute of General and Ecological Chemistry, Technical University of Łódź ul. Żwirki 36, 90-924 Łódź, Poland

autor

Góralski J.

• Institute of General and Ecological Chemistry, Technical University of Łódź ul. Żwirki 36, 90-924 Łódź, Poland

autor

Paryjczak T.

• Institute of General and Ecological Chemistry, Technical University of Łódź ul. Żwirki 36, 90-924 Łódź, Poland

Bibliografia

• 1. Thomas C.L., Catalytic Processes and Proven Catalyst, Academic Press, NY, 1970.
• 2. McDaniel M.P. and Jonson M.M., J. Catal., 101, 446 (1986).
• 3. Józwiak W.K. and Dalla Lana I.G., J. Chem. Soc., Farad. Trans., 93, 2583 (1997).
• 4. Józwiak W.K., Dalla Lana I.G., Przystajko W. and Fiedorow R., in Proceedings, 9th International Congress on Catalysis, Calgary, 1988 (Phillips M.J. and Teman Eds.), p. 1340. Chem. Institute of Canada, Ottawa, 1988.
• 5. Ellison A., Overton T.L. and Bencze L., J. Chem. Soc. Farad. Trans., 89, 843 (1993).
• 6. Prinetto F., Ghiotti G., De Rossi S. and Di Módica G., Applied Catalysis B: Environmental, 14, 225 (1997).
• 7. Ruddick V.J. and Badyal J.P.S., J. Phys. Chem. B, 102, 2991 (1998).
• 8. McDaniel M.P., Witt D.R. and Benham E.A., J. Catal., 176, 344 (1998).
• 9. Bade O.M., Blom R., Dahl I.M., and Karlsson A., J. Catal., 173, 460 (1998).
• 10. Storaro L., Ganzerla R., Lenarda M., Zanoni R., López A.J., Olivera-Pastor P. and Castellón E.R., J. Mol. Catal., 115, 329 (1997).
• 11. Petrosius S.C., Drago R.S., Young V.Y. and Grünewald G.C., J. Am. Chem., Soc., 115, 6131 (1993).
• 12. Cavani F., Koutyrev M., Trifiro F., Bartolini A., Ghisletti D., Iezzi R., Santucci A. and Piero G.D., J. Catal., 158, 236 (1996).
• 13. FouadN.E., Knözinger H., Zaki M.I. and Mansour S.A.A., Z. Phys. Chem., 171, 75 (1991).
• 14. Köhler K., Engweiler J., Viebrock H. and Baiker A., Langmuir, 11, 3423 (1995).
• 15. Rachman A., Mohamed M.H., Achmed M. and Aitani A.H,,Appl. Catal., 121, 203 (1995).
• 16. Vuurman M.A., Harcastle F.D. and Wachs I.E., J. Mol. Catal., 84, 193 (1993).
• 17. Zecchina A., Garrone E., Ghiotti G., Morterra C. and Borello E., J. Phys. Chem., 79, 966 (1975).
• 18. Cimino A.,Cordischi D., De Rossi S., Ferraris G., Gazzoli D., Indovina V., Occhiuzzi M. and Valigi M., J. Catal., 127, 761 (1991).
• 19. Hardcastle F.D. and Wachs I.E., J. Mol. Catal., 46, 173 (1988).
• 20. Kim D.S. and Wachs I.E., J. Catal., 142, 166 (1993). Characterization of chromium oxide supported on silica
• 21. Köhler K., Schläpfer C.W., von Zelewsky A., Nicki J., Engweiler J. and Baiker A., J. Catal., 143, 201 (1993).
• 22. Fouad N.E., J. Anal. Cal., 60, 541 (2000).
• 23. Hewston T.A. and Chamberland B.L., J. Magnetism and Magnetic Mater., 43, 89 (1984).
• 24. Köhler K., Maciejewski M., Scheider H. and Baiker A., J. Catal., 157, 301 (1995).
• 25. Mc Daniel P., J. Catal., 67,71 (1981).
• 26. Hierl G. and Krauss H.L., Z. anorg. allg. Chem., 415, 57 (1975).
• 27. Vuurman M.A., Wachs I.E., Stufkens D.J. and Oskam A.J., J. Mol. Catal., 80, 209 (1993).
• 28. Ellison A. and Overton T.L., J. Mol. Catal., 90, 81 (1994).
• 29. Zaki M.I., Fouad N.E., Bond G.C. and Tachir S.F., Thermochim. Acta, 285, 167 (1996).
• 30. Bensalem A., Weckhuysen B.M. and Schoonheydt R.A., J. Phys. Chem., 101, 2824 (1997).
• 31. Lugo H.J. and Lundsford J.H., J. Catal., 91, 155 (1985).
• 32. Groeneveld C., Wittigen P.P.M.M., Swinnem H.P.M., Wemsen A. and Schuit G.C.A., J. Catal 83 346 (1983).
• 33. Pollukat T.J. and Hoff R.E., Catal. Rev.-Sci. Eng., 41, 389 (1999).
• 34. Jóźwiak W.K., Dalla Lana I.G. and Fiedorow R., J Catal., 121, 183 (1990).
• 35. Chen J.D. and Sheldon R.A., J. Catal., 153, 1 (1995).
• 36. Welch M.B. and McDaniel M.P., J. Catal., 82, 110 (1983).
• 37. Zecchina A., ColucciaS., Cerruti L. andBorello E., J. Phys., 75, 2783 (1971).
• 38. Schneider H., Maciejewski M., Köhler K. Vokaun A. and Baiker A., J. Catal., 157, 312 (1995).
• 39. Curry-Hyde H.E., Baiker A., Schraml-Marth M. and Vokaun A., J. Catal., 133, 397 (1992).
• 40. Schraml-Marth M., Vokaun A., Curry-Hyde H.E. and Baiker A., J. Catal., 133, 415 (1992).