CATALYTIC AND STRUCTURAL-PROPERTIES OF RUTHENIUM BIMETALLIC CATALYSTS- PREPARATION AND CHARACTERIZATION

In the framework of an EC Stimulation Action Programme, alumina-suppor ted mono- and bimetallic Ru, RuGe, RuSn and RuPb catalysts have been p repared from both organic and inorganic precursors. Herein are present ed some basic properties of these materials obtained by TPR and TPO ex periments, H-2 and CO chemisorption, TEM examination, XPS and EXAFS st udies. The use of organic precursors led to very small Ru particles, w ith a coordination number between Ru atoms of 4.35 (Ru0-Ru0 + Ru0-Ru(d elta+)). The size of the metallic particles was not modified by adding Ge, Sn or Pb by the controlled surface reaction technique. In very sm all aggregates, some Ru atoms (10-15%) remained partially oxidised eve n after reduction at 623 K in flowing hydrogen. During the coimpregnat ion of alumina with inorganic precursors, the modifier played the role of a nucleation center for Ru, thus allowing small particles to be fo rmed. We believe that CO could modify the surface composition of small bimetallic RuGe particles during the chemisorption.