Propylene epoxidation with in situ generated H2O2 in supercritical conditions

Several bi-functional materials based on palladium nanoparticles supported onto nanocrystalline titanium silicalite zeolite (Pd@TS-1) were prepared and used as active and reusable catalysts to direct PO production from hydrogen, oxygen and propylene through one-pot two-step combined process. This type of catalysts was able to carry out the consecutive process where palladium nanoparticles catalyzed the formation of H2O2 that was used as intermediate reagent for propylene epoxidation catalyzed by TS-1 nanocrystals, used as supporting active matrix. Influence of supercritical CO2 conditions in batch reactions was evaluated together with the associated effect due to the presence of platinum promoters (Pd(Pt)@TS-1). Other reaction parameters were also considered, such as palladium loading, use of acidity inhibitors and modification of H2/O2/C3 ratio. Reusability studies showed the high stability of the catalysts in consecutive catalytic cycles, their regeneration being possible.