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Applications of in situ Time-Resolved X-ray Diffraction/Mass Spectrometry in the Characterization of Catalysts. J.C. Hanson, Chemistry Dept., Brookhaven Nat. Lab., Upton, NY 11973.

The development of techniques for characterizing the structural properties of catalysts under the high-pressure conditions of industrial processes is widely recognized as a top priority in the area of heterogeneous catalysis. Investigations at Brookhaven National Laboratory have established the feasibility of conducting sub-minute, time-resolved in situ x-ray diffraction (XRD) experiments under a wide variety of temperature and pressure conditions (80 K < T < 1200 K; P< 50 atm) This important advance results from combining the high intensity of synchrotron radiation with new parallel data-collection devices [1]. Current measurements also include control of gas flow and measurement of gas composition of the products with mass spectrometry (MS). Using time-resolved XRD, one can get information about: structural details, phase composition, kinetics of transformation, intermediate phases and crystal characteristics. Examples of problems studied to date with time-resolved XRD include: Hydrothermal synthesis[2] and substrate binding of zeolites[3], reduction/oxidation cycles in oxide catalysts[4] and catalyst structure of active catalyst[5].

Acknowledgement. This work was supported by the US Dept. of Energy, Chemical Sciences Div. (DE-AC02-98CH10086).

[1] P. Norby and J.C. Hanson, Catal. Today, 39 (1998) 301.

[2] Norby, P., A. N. Christensen, J. C.Hanson, 38 Inorg. Chem. (1999)1216.

[3] P. Norby, F.I. Pashni, A.F. Gualtieri, J.C. Hanson, and C.P. Grey, J. Phys. Chem. B, 102 (1998) 839.

[4] Rodriguez, J. A.; Hanson, J. C.; Frenkel, A. I.; Kim, J.-Y.; Pérez, M. J. Am. Chem. Soc., 124, (2002) 346.

[5]Chupas, P. J.; Ciraolo, M. F.; Hanson, J. C.; Grey, C. P. J. Am. Chem. Soc., 123 (2001) 1694.