Selective reduction of NO_X with C₃H₆ over CU incorporated into silicoaluminophosphate (SAPO)

Cu ion-exchanged SAPO-34 which is a highly active catalyst for selective reduction of NO with C₃H₆, was synthesized and the Cu ion was characterized in the SAPO-34 by ESR, XPS, IR, and XAFS. ESR study indicated that two kinds of Cu(II) with different environments exist in SAPO-34. The Cu(II) species disappeared immediately by C₃H₆ treatment and recovered by oxygen treatment. XAFS study indicated that most of the Cu(II) was reduced to Cu(I) under the presence of C₃H₆. These studies revealed that a selective NO reduction by C₃H₆ over SAPO-34 should proceed by the redox reaction of a copper ion between Cu(I) and Cu(II).