ESR study of competition between Fe3+ and Cu2+ active sites for NOx selective catalytic reduction by NH3 in Cu–Fe-Beta catalyst

A series of Fe-Beta catalysts modified with different amount of Cu was prepared and tested in NOx selective catalytic reduction by NH3. ESR study reveals that replacement of isolated tetrahedral Fe3+ ions by Cu2+ ions in cationic sites of the zeolite takes place upon Fe-Beta treatment by copper. This modification results in gain in deNOx activity in low-temperature region, due to formation of cationic Cu2+, and significant loss in activity at high temperatures, which is determined by substitution of active Fe3+ for less active Cu2+.

Graphical abstractReplacement of Fe3+ by Cu2+ in zeolitic cationic sites occurs upon Fe-Beta treatment by copper. This results in gain in low-temperature deNOx activity and loss in activity at high temperatures.Figure optionsDownload full-size imageDownload high-quality image (40 K)Download as PowerPoint slide