XANES and EXAFS measurements on heterogeneous catalysts often require time-consuming in situ pre-treatments of the catalyst. In our research¹ concerning the development and characterisation of new generation, CeO₂-ZrO₂ based three-way catalysts, we designed an in situ XAS cell. The major advantage of this system is its compact design (see figure) and the motorised elevator which allows to move the cell out of the X-ray beam during the pretreatments. In this way a very high productivity of the measurements can be achieved since standards and/or other samples may be measured without interfering with the pretreatments of the catalyst. This cell has been successfully employed for measurements carried out at the EXAFS I, EXAFS III stations at the LURE accumulation ring in Orsay (France).

The cell is constructed in AISI 304, the sample holder and windows are in boron nitride/carbon. Dimensions of the cell: approx. 10 x 10 cm. Gas tightness in ensured by graphite seals. Typically the following reaction conditions are employed: range of temperatures: subambient to 500°C; heating/cooling rate: 0.5-20 K min-1, flow of gas: up to 50-70 ml min-1, pressures: vacuum (10-2 torr, tested) - atmospheric; 15-70 mg of powdered catalyst.

The cell is manufactured by our Departmental workshop. For details and prices contact Mr. Elvio Merlach - e-mail enquiries to kaspar@dschsun1.univ.trieste.it

¹see for example : G.Ranga Rao, P.Fornasiero, R.di Monte, J. Kašpar, G. Vlaic, G.Balducci, S.Meriani, G.Gubitosa, A.Cremona, and M.Graziani, "Reduction of NO over Partially Reduced Metal-loaded CeO₂-ZrO₂ Solid Solutions.", J.Catal. 162, 1 (1996).

3/10/96 - Jan Kaspar (kaspar@dschsun1.univ.trieste.it)