Formation of catalytically active copper nanoparticles in natural zeolites for complete oxidation of hydrocarbons

Copper catalysts for complete oxidation of hydrocarbons supported on natural zoolites of different structure and origin were prepared by ion-exchange procedure. The catalytic experiments demonstrate that the temperature of beginning of hydrocarbons conversion is in the range of 170-300 degrees C, depending on the composition of the catalyst. The complete conversion can be observed for both zeolites, depending (probably) on Si/Al ratio of the zeclite matrix. Different states of the copper have been identified by the methods of UV-VIS and XPS spectroscopies; and TPR by hydrogen. Whereas no changes in XRD and Al-27 MAS NMR was observed under condition of catalytic runs, that supports conclusion about stability of bulk material, XPS spectroscopy reveals significant altering in surface composition under different treatments due to appearance of complicated nano-species of copper, which are responsible for catalytic activity.