Selective reduction of NOX with C3H6 over Cu incorporated into silicoalumino-phosphate (SAPO)

Abstract

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).