The Ammonia Storage and Ammonia Species Reactivity within Cu-ZSM-5 with Different Copper Electronic States Full article
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Applied Catalysis A: General
ISSN: 0926-860X , E-ISSN: 1873-3875 |
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| Output data | Year: 2021, Volume: 615, Article number : 118054, Pages count : 18 DOI: 10.1016/j.apcata.2021.118054 | ||
| Tags | Cu-ZSM-5; Selective catalytic reduction of NOx; NO-NH3 SCR; Ammonia storage capacity; Copper electronic state; Copper-ammonia complex | ||
| Authors |
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| Affiliations |
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Funding (1)
| 1 | Ministry of Science and Higher Education of the Russian Federation | ГЗ-2021-2023 |
Abstract:
Three Cu-ZSM-5 catalysts having different copper species: 1) the isolated Cu2+ ions, 2) the structures of Cu2+ ions with extra-lattice oxygen (ELO), and 3) the CuO-like nanoparticles, were comparatively studied for their ammonia storage capacity under NH3-Ar, NH3-O2-Ar, and NH3-NO-O2-Ar (SCR-like) feeds. EPR, DR UV–vis, DRIFT techniques and TPD modes were used to evaluate the effect of Cu-state in the O2-activated catalysts on their ammonia storage capacity and conversion of the adsorbed ammonia under Ar, O2-Ar, or NO-O2-Ar feeds. Several types of NH3-species were generated in the NH3-saturated and SCR-treated catalysts. It was shown that NH3-species within the NH3-saturated catalysts, which contained the Cu-structures with ELO or CuO-like nanoparticles, were more reactive compared with the catalyst with isolated Cu2+ ions. For the first two samples, the ammonia sorption capacity determined from the sorption-desorption dynamics at given temperature (25, 200, 300 °C) was higher than amount of the TPD(Ar)-desorbed ammonia under Ar. It is due to selective oxidation of some amount from the coordinated NH3-species, for which ELO of Cu-structures is consumed, the process is accompanied by reduction of Cu2+ to Cu+. The total quantity of the TPD-desorbed ammonia as well as the amount of ammonia coordinated in [Cu(NH3)n]2+ complex decreased with increasing sorption temperature and under O2-Ar or NO-O2-Ar feeds used for TPD mode. Regardless of Cu-states in the catalysts, the molar ratio of the ammonia storage capacity to copper loading was shown by the sorption-desorption dynamics to be ca. 2 at 200 °C, versus 4 typical of the catalyst saturated at 25 °C. These values are consistent with DR UV–vis data, showing a.b. at 14100-14500 cm−1 and 15700−15800 cm−1, respectively. The NH3-TPD(Ar) mode with the NH3-saturated catalysts showed the molar ratio of the TPD-desorbed ammonia to copper loading (ν(NH3)/ν(Cu) equal to 2 for the sample with isolated Cu2+ions; but for two others, the ν(NH3)/ν(Cu) was < 1. Finally, this work is trying to manifest the role of isolated Cu2+ ions and Cu-structures with ELO for SCR-activity.
Cite:
Yashnik S.A.
, Ismagilov Z.R.
The Ammonia Storage and Ammonia Species Reactivity within Cu-ZSM-5 with Different Copper Electronic States
Applied Catalysis A: General. 2021. V.615. 118054 :1-18. DOI: 10.1016/j.apcata.2021.118054 WOS Scopus РИНЦ AN OpenAlex
The Ammonia Storage and Ammonia Species Reactivity within Cu-ZSM-5 with Different Copper Electronic States
Applied Catalysis A: General. 2021. V.615. 118054 :1-18. DOI: 10.1016/j.apcata.2021.118054 WOS Scopus РИНЦ AN OpenAlex
Dates:
| Submitted: | Nov 30, 2020 |
| Accepted: | Feb 14, 2021 |
| Published online: | Feb 21, 2021 |
| Published print: | Apr 5, 2021 |
Identifiers:
| Web of science: | WOS:000674236500005 |
| Scopus: | 2-s2.0-85102004697 |
| Elibrary: | 46758679 |
| Chemical Abstracts: | 2021:600622 |
| OpenAlex: | W3131828223 |