Activation, Stability and Regeneration

According to the current state of the art, Pt- and Cu-containing catalysts are of particular interest for chemical hydrogen storage. Pt-containing catalysts play a particularly important role in the hydrogenation of aromatic and the dehydrogenation of alicyclic compounds. These catalysts are activated in situ due to their very easy reducibility under reaction conditions. However, they easily form coke deposits on the catalyst from high-boiling by-products, which can lead to catalyst deactivation. Coke deposits can be regenerated by hot wash procedures or by burning-off procedures with oxygen-containing gas mixtures. In the latter case, care must be taken to ensure that the highly exothermic coke burn-off does not lead to detrimental temperature peaks in the catalyst. Copper-containing catalysts, on the other hand, require a thorough preformation procedure. Under fluctuating conditions, the reduction state of the catalyst must be checked and, if necessary, ensured by regeneration measures. In addition, resistance against copper leaching and mechanical properties after catalyst shaping play a major role for the durability of these catalyst systems in typical chemical hydrogen storage applications under pressure change conditions.