Effect of the electronic state and copper localization in ZSM-5 pores on performance in NO selective catalytic reduction by propane

Cu-substituted ZSM-5 catalyst: Controlling of DeNO reactivity via ion-exchange mode with copper–ammonia solution

“…Oh cations [8], respectively. The both structures have extra-lattice oxygen and are formed from mono-, bi-and polynuclear copper hydroxocomplexes (absorption at 31,000-33500 cm −1 , Fig.…”

“…After the addition of ammonia solution to the aqueous copper acetate solution, precipitation of copper hydroxide is observed, which is followed by its dissolution with the formation of ammonia-copper complexes [Cu(NH 3 ) n (H 2 O) 6 8 ] 2+ and polynuclear hydroxocomplexes. After the formation of tetraammine complex at NH 4 + /Cu 2+ near 6-15 the concentration of Cu 2+ ions is quite low and insufficient for attaining the product of copper(II) hydroxide solubility equal to 5.6 × 10 −20 .…”

“…9. Rate constant of NO (A and B) and propane (C and D) conversion over n% Cu(˛)ZSM-5 catalysts at 275 • C. The n% Cu(˛)ZSM-5 samples have been prepared by the ion-exchange of H-ZSM-5 (curves 1, 4-9), NH4-ZSM-5 (curve 2) or Na-ZSM-5 (curve 3) with water-ammonia solution of copper acetate at NH4 + /Cu 2+ ratio (˛) equal to 0 (curves 1, 2, 3), 3 (curve 5), 6 (curve 6,8,9), 15 (curve 7) and 30 (curve 4), including those containing additive of 1 M (curve 8) and 3 M (curve 9) of ammonium acetate. a˛(* 10 -2 s -1 g Cu -1 ) is slope of correlation between kNO or kC3H8 and copper content for each NH4 + /Cu 2+ ratio.…”

“…Up to date, various research groups have been involved in investigation of the active state of copper ions [3,4], a search for new catalytic reactions with participation of Cu-ZSM-5 [5,6], and development of advanced methods for the synthesis of copper-containing catalysts [7][8][9]. Although post-synthetic modification of zeolites was considered in many works, ion exchange remains the most widely used method of copper acetate [4,10,20], nitrate [4,10,13], chloride [4,9,10] or sulfate [4,10,21].…”

Adsorption of molecular hydrogen on aluminophosphate zeolites at 77 K

“…Of significance are both active component distribution in the mesopore space (i.e., on the surface of zeolite crystallites) and active component distribution in the micropore channel space. These active component distributions are a considerable factor in the catalytic and service charac teristics of zeolite containing catalysts [11,12]. It is, therefore, a challenging problem to advance methods for analyzing the active component distribution in the pore space of a support.…”