Effect of framework charge density on catalytic activity of copper loaded molecular sieves of chabazite structure in nitrogen(II) oxide decomposition

NO decomposition over Cu-loaded molecular sieves of chabazite structure wit h different framework negative charge density was investigated. Cu-ZnAlPO-3 4 with framework charge density (Al + P)/Zn = 15 exhibited high and stable catalytic activity in NO decomposition while Cu-chabazite with Si/Al = 2.7 was inactive. This evidences that the number of aluminum atoms balancing Cu ions in cationic sites controls the catalytic activity of Cu ion. Ions bal anced by single framework aluminum atoms exhibit high activity in NO decomp osition while ions balanced by two framework aluminum atoms are inactive. T opology of cationic sites is not the limiting parameter for NO decompositio n over Cu ions located in molecular sieves.