Characterization of commercial Cu-SSZ-13 and Cu-SAPO-34 catalysts with hydrothermal treatment for NH3-SCR of NOx in diesel exhaust

Ma, Lei; Cheng, Yunhui; Cavataio, Giovanni; McCabe, Robert W.; Fu, Liqun; Li, Junhua

doi:10.1016/j.cej.2013.03.078

Cited by 292 publications

(213 citation statements)

References 35 publications

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“…It is likely that calcination at 750 • C causes oxidic copper species to move into the structure. This interpretation is consistent with findings that Cu ions migrate from the catalyst surface into ion [28,42,49,50] (for example during solid-state ion-exchange) and with our observation that Cu/SAPO-34 1.49 and 1.60 wt % Cu are grey in colour after calcination at 550 • C and turn blue after the second calcination at 750 • C. UV-vis spectra were acquired for the two samples calcined at 550 and 750 • C and are shown in the top panel of Figure 12. The two spectra differ mainly in the region between 350 and 550 nm.…”

Section: Impact Of Calcination Temperaturesupporting

confidence: 81%

“…Several studies have assigned the charge transfer band at around 225 nm to the O (SAPO-34) → Cu + /Cu 2+ charge transition [25][26][27]. A broad band centred at around 800 nm has been assigned to the d → d transition of isolated Cu 2+ , and also coincides with the bands observed in the reference material Cu(OH) 2 [25][26][27][28]. This band, representative of isolated, hydrated Cu(II), has been identified on a number of copper-exchanged zeolites, including Cu/BEA, Cu/ZSM-5 and Cu/SSZ-13 [29][30][31].…”

Section: Catalyst Composition and Copper Speciesmentioning

confidence: 86%

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Impact of Copper Loading on NH3-Selective Catalytic Reduction, Oxidation Reactions and N2O Formation over Cu/SAPO-34

et al. 2017

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Abstract:We developed a procedure for aqueous ion exchange to obtain different Cu loadings of Cu/SAPO-34 (between 0 and 2.6 wt %). The catalysts were washcoated on monoliths and characterised with respect to their activity and selectivity under standard selective catalytic reduction (SCR), fast SCR, NH 3 oxidation and NO oxidation reactions. They were further characterised using X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET), H 2 -temperature programmed reduction (H 2 -TPR), ultraviolet (UV)-vis spectroscopy and NH 3 adsorption. As expected, activity of all reactions increased with copper loading, due to increased number of active sites. However, the N 2 O formation during standard and fast SCR yielded interesting mechanistic information. We observed that N 2 O formation at low temperature increased with copper loading for the standard SCR reaction, while it decreased for fast SCR. The low-temperature N 2 O formation during fast SCR thus occurs predominantly over Brønsted sites. Species responsible for N 2 O formation during standard SCR, on the other hand, are formed on the copper sites. We further found that the fast SCR reaction occurs to a significant extent even over the H/SAPO-34 form. The Brønsted sites in SAPO-34 are thus active for the fast SCR reaction.

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Section: Impact Of Calcination Temperaturesupporting

confidence: 81%

Section: Catalyst Composition and Copper Speciesmentioning

confidence: 86%

Impact of Copper Loading on NH3-Selective Catalytic Reduction, Oxidation Reactions and N2O Formation over Cu/SAPO-34

et al. 2017

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“…This first result already predicts an effect of the sodium solvent toward physico properties of the materials. The specific surface areas for the higher Na amounts decrease 250 m 2 g −1 (Table 1).…”

Section: Catalytic Activitymentioning

confidence: 99%

“…The main involved reactions are the "Standard-SCR" reaction (Equation (1)) and the "Fast-SCR" reaction (Equation (2) …”

Section: Introductionmentioning

confidence: 99%

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

et al. 2017

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Abstract:The effect of the sodium addition mode was investigated on model Cu/FER selective catalytic reduction (SCR) catalysts with two copper loadings (2.8 wt. % and 6.1 wt. %) in order to compare samples with or without over-exchanged copper. Na was added by wet-impregnation using two solvents: water or ethanol. Catalysts were evaluated in Standard and Fast-SCR conditions, as well as in NO and NH 3 oxidation. They were characterized by H 2 -TPR, NO and NH 3 adsorption monitored by FT-IR. As expected, whatever the copper loading, ammonia adsorption capacity was decreased by Na additions. Interestingly, characterizations also showed that Na impregnation in water favors the migration of the Cu-exchanged species, leading to the formation of CuO extra-framework compounds. Consequently, for both copper loadings, Na impregnation in water led to a stronger catalyst deactivation than impregnation in ethanol. Finally, the NO x conversion at low temperature (250 • C) appeared mainly affected by the loss in NH 3 adsorption capacity whereas the deNO x deactivation at high temperature (500 • C) was rather governed by the decrease in the exchanged copper ratio, which also induced a partial inhibition of NO and NH 3 oxidation behaviors.

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“…The Cu-SAPO-34 catalyst showed excellent SCR activity over a wide range of temperature and quite outstanding hydrothermal stability at high temperatures [7][8][9].…”

Section: Introductionmentioning

confidence: 99%

A novel one-pot synthesized CuCe-SAPO-34 catalyst with high NH3-SCR activity and H2O resistance

Niu

Shi

et al. 2016

Catalysis Communications

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CuCe-SAPO-34 catalysts based on the one-pot hydrothermal synthesis method were prepared for the first time. The addition of Ce suppressed the formation of CuO and increased the amount of active Cu 2+ , resulting in better NH 3 -SCR activity than Cu-SAPO-34. Ce greatly improved the H 2 O resistance during the SCR process by stabilizing the zeolite structure and obstructing the transformation of active Cu 2+ into inactive forms.

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Characterization of commercial Cu-SSZ-13 and Cu-SAPO-34 catalysts with hydrothermal treatment for NH3-SCR of NOx in diesel exhaust

Cited by 292 publications

References 35 publications

Impact of Copper Loading on NH3-Selective Catalytic Reduction, Oxidation Reactions and N2O Formation over Cu/SAPO-34

Impact of Copper Loading on NH3-Selective Catalytic Reduction, Oxidation Reactions and N2O Formation over Cu/SAPO-34

Influence of the Sodium Impregnation Solvent on the Deactivation of Cu/FER-Exchanged Zeolites Dedicated to the SCR of NOx with NH3

A novel one-pot synthesized CuCe-SAPO-34 catalyst with high NH3-SCR activity and H2O resistance

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