Effect of the Electronic State and Copper Localization in ZSM-5 Pores on Performance in NO Selective Catalytic Reduction by Propane
Научная публикация
| Общее |
Язык:
Английский,
Жанр:
Статья (Full article),
Статус опубликования:
Опубликована,
Оригинальность:
Оригинальная
|
| Журнал |
Applied Catalysis B: Environmental
ISSN: 0926-3373
, E-ISSN: 1873-3883
|
| Вых. Данные |
Год: 2011,
Том: 103,
Номер: 1-2,
Страницы: 1-10
Страниц
: 10
DOI:
10.1016/j.apcatb.2010.12.046
|
| Ключевые слова |
Extraframework aluminum, HZSM-5, Localization, Modifying copper species, NO removal, Post-synthetic modification |
| Авторы |
Krivoruchko Oleg P.
1
,
Larina Tatyana V.
1
,
Shutilov Roman A.
1
,
Gavrilov Vladimir Yu.
1
,
Yashnik Svetlana A.
1
,
Sazonov Vladimir A.
1
,
Molina Irina Yu.
1
,
Ismagilov Zinfer R.
1
|
| Организации |
| 1 |
Boreskov Institute of Catalysis SB RAS, Novosibirsk, Russia
|
|
This study was devoted to determination of localization of the individual copper species in the pores of ZSM-5 zeolite after post-synthetic zeolite modification by incipient wetness impregnation with CuCl2 solution followed by hydrolytic polycondensation of the ions in the pores. A series of Cu(n)ZSM-5 samples, where n is the copper concentration varied from 0.5 to 5.0 wt.%, were synthesized using this method. A commercial HZSM-5 zeolite having Si/Al = 17 was used for the synthesis of the catalysts. After modification the Cu(n)ZSM-5 samples were dried and calcined in air at 110 and 450 °C, respectively. The samples were studied by UV–vis–NIR DR spectroscopy, XRD and by measuring and processing the low-temperature (77 K) adsorption of nitrogen and hydrogen. It was shown for the first time that at the concentration of 1.0 wt.% or lower copper was localized in the form of isolated Cu2+Oh cations in the ion-exchange positions in the zeolite micro- and mesopores as well as on oxygen complexes of extraframework aluminum in thin mesopores with D < 3.2 nm in the form of superficial spinel-like structures in octahedral oxygen coordination Cu2+Oh. At the copper concentration above 1.0 wt.% linear associates of weakly bound Cu2+Oh ions with unusual orbital ordering were formed in addition to the two forms discussed above. These associates existing in the forms of one- and two-dimensional nanohydroxocompounds were localized partially in the zeolite micropores but mostly in thin mesopores.
The effect of the individual copper species on the catalytic properties of Cu(n)ZSM-5 samples in selective catalytic reduction of NO by propane was also studied. It was found that isolated Cu2+Oh cations in the ion-exchange positions and Cu2+Oh cations localized on the oxygen complexes of extraframework aluminum had the highest catalytic activity in NO SCR by propane. The weakly bound linear associates of Cu2+Oh ions had lower catalytic activity, compared with isolated Cu2+Oh ions. When their amount was high, they caused steric hindrance for contact of the reagents with the more active sites. The Cu2+Oh ion associates were found to transform to nanodispersed Cu2(OH)3Cl during catalytic experiments.