X-ray heating chamber investigations of reforming Pt-Al2O3 catalysts

Model catalysts with increased Pt content and commercial catalysts have been tested in an X‐ray heating chamber at different temperatures and in various fluids (O2, N2, N2/H2 and Ar) at atmospheric pressure. In an air atmosphere and at temperatures between ambient and approx. 850 K, the Pt crystallites are subjected to superficial oxidation, sintering starts at approx. 850 K. In a hydrogen atmosphere, an increase in temperature at first results in the formation of crystalline Pt particles having a degree of crystallinity of 100% (error range 5%). Depending on the kind of sample and beginning at approx. 700 K, a Pt hydride phase which is stable in H2 only and has a lattice constant of a = 3.875 Å is formed later on. Furthermore, conclusions for the evaluation and interpretation of X‐ray measurements of catalysts are drawn.