Regulation of the copper-oxide cluster structure and DeNOx activity of Cu-ZSM-5 catalysts by variation of OH/Cu2+

摘要: Abstract The present work studies RedOx properties and reactivity in N2O decomposition selective catalytic reduction of NO (NO-SCR) by propane Cu-modified ZSM-5 catalysts prepared hydrolytic polycondensation (HPC). Their characteristics are compared with Cu-ZSM-5 samples having the same copper content (1 wt.%) produced ion exchange (IEX) water–ammonia solutions chloride at NH4OH/Cu2+ equal to 6–30. HPC method consists treatment copper-impregnated zeolite solution for hydrolyzed ions pores. It is shown that varying ratio allows a regulation size structure active complexes. contains as CuO-like particles after calcination. At 1–3, sites dried disordered polynuclear copper-hydroxo complexes, which characterized symmetric ESR signal g0 = 2.18. Increase 6–30 lead orbital ordering Cu2+ copper–ammoniate observed rhombic signals (gzex,1 = 2.18, gyex,1 = 2.08, gxex,1 = 2.03 g∥ex,2 = 2.24, g⊥ex,2 = 2.03), dispersion during following thermal 500 °C. 1%Cu(30)ZSM-5-HPC sample NH4OH/Cu2+ = 30 has higher amount isolated tetraammine–copper complex lower number weak associates among samples. addition ammonia favorable impact on activity DeNOx processes. In decomposition, ion-exchanged CuZSM-5 were more reactive low-temperature region, while ex-polycondensation provided high conversion temperatures. NO-SCR propane, catalysts, rate increased grew 10. suggested ordered associated have selectivity both processes ions.