Calorimetry - Adsorption Dynamics

Dr. Sabine Wrabetz

The quantitative investigation of the adsorption processes of reactants at reaction temperature on catalytically active surfaces is an important strategy to understand and control catalyst performance. To distinguish the impact of nanoparticle morphology and size from electronic effects, well-defined Pd-based laterally condensed catalyst (LCC) materials were prepared. These model catalysts were then used in the semi-hydrogenation of acetylene to ethylene.

Here, calorimetry focusses on the adsorption of reaction gas mixture C2H2:H2=1:30, pure H2 and pure C2H2 at a reaction temperature of 398 K and pressure of 1 bar. The metal surface of LCC, foil and bulk material is analyzed with regard to its adsorption behavior and thus allows conclusions about favorable reaction behavior to be drawn. In addition, CO at 40°C is used as a standard probe molecule to evaluate the noble metal surface structure.

To visualize these dynamics, noble metal surface is titrated using selected probe molecules during fresh, formation and steady state phase. Titration on various times on stream (TOS) proves dynamic behavior of the catalytically relevant adsorption sites — adsorption dynamics.