Hartmut Lausch

The state of metallic phase in alumina-supported platinum-chromium catalysts

Abstract The reduction behaviour and the phase composition of platinum-chromium samples (unsupported and on alumina carrier) were investigated with the help of temperature-programmed reduction (TPR), X-ray diffraction, ferromagnetic resonance (FMR) spectroscopy and ethane hydrogenolysis. Co-reduction and the formation of alloys was found to occur when H 2 PtCl 6 and (CrO 3 ) x were used as starting materials. Annealing of the samples above 500°C led to the formation of a ferromagnetic Pt 3 Cr superlattice. Addition of chromium to platinum/alumina attenuates the hydrogenolysis activity; annealing results in an additional strong decrease of this demanding reaction.

A model of reduction mechanism of rhenium in Re/Al2O3 catalysts

In Re/Al2O3 there exist a monolayer type of Re and a second one which is inserted in the alumina lattice. The latter is reduced by a two-step mechanism including Re(IV) species.AbstractРений в Re/Al2O3 находится в виде монослоя и в виде частиц, встроенных в решетку. Последний восстанавливается по двухступенчатому механизму, включая Re(IV).