Influence of sodium on activation of gold species in Y–zeolites

Catalytic tests of the Au–zeolites pure or doped with Na revealed the existence of two types of active sites of gold in CO oxidation – partly charged gold clusters Aunδ+ (low-temperature activity) and gold nanoparticles Aum0 (high-temperature activity). The data obtained demonstrates clear direct dependence of gold species reactivity on zeolite acid properties (Si/Al molar ratio and Na addition). Na modified Au–zeolites with different Si/Al molar ratio were found to be activated in CO oxidation in different degrees due to diverse redox state of supported gold species. The revealed effect of activation of one of two active species in CO oxidation (Aunδ+) is promising for improvement of activity and stability of the gold–zeolites catalysts.