The effect of various templates on the NH3-SCR activities over Cu/SAPO-34 catalysts

Yu, Tie; Fan, Di; Hao, Teng; Wang, Jun; Shen, Meiqing; Li, Wei

doi:10.1016/j.cej.2014.01.008

Cited by 101 publications

(43 citation statements)

References 32 publications

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“…Only small amounts of side products are formed, with NO, NO 2 and N 2 O not exceeding eight, two and three ppm, respectively. The side product selectivities found by Yu et al for copper loadings of around 0.90 wt % are higher compared to ours, with maximum NO mole fractions ranging between 22 and 46 ppm depending on Si content [34]. Wang et al find comparably little formation of side products [20], which is in line with our study.…”

Section: Standard Scrsupporting

confidence: 79%

“…The asymmetric shape of the temperature-programmed desorption (TPD) profile indicates that there may be another, lower peak centred at around 250 °C. Such a peak has indeed been observed when adsorbing at temperatures lower than the 150 °C used here [20,33,34]. It has been assigned to desorption from either weak Brønsted sites or weak Lewis sites.…”

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 83%

“…Given that the Si content of this sample is much larger, at 1.75 mmol Si/gcat, it is likely that H/SAPO-34 contains silicon islands [33,35,36]. The high-temperature desorption peak centred on average at about 340 °C can be attributed to strongly-bound NH3 molecules adsorbed on both strong Brønsted sites and new Lewis acid sites generated by the incorporation of copper [33,34]. The asymmetric shape of the temperature-programmed desorption (TPD) profile indicates that there may be another, lower peak centred at around 250 °C.…”

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

“…The high-temperature desorption peak centred on average at about 340 • C can be attributed to strongly-bound NH 3 molecules adsorbed on both strong Brønsted sites and new Lewis acid sites generated by the incorporation of copper [33,34]. The asymmetric shape of the temperature-programmed desorption (TPD) profile indicates that there may be another, lower peak centred at around 250 • C. Such a peak has indeed been observed when adsorbing at temperatures lower than the 150 • C used here [20,33,34]. It has been assigned to desorption from either weak Brønsted sites or weak Lewis sites.…”

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

“…The desorption profiles are shown in Figure 3. Ammonia molecules physisorbed onto weak Brønsted and Lewis acid sites and desorbed during the purge at 150 °C (not shown here) [20,33,34]. Integration of the signal for H/SAPO-34, yields a storage capacity of 0.59 mmol NH3/gcat.…”

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

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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: Standard Scrsupporting

confidence: 79%

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 83%

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

Section: Characterisation By Nh3 Adsorptionmentioning

confidence: 99%

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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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Tailoring the Porosity and Active Sites in Silicoaluminophosphate Zeolites and Their Catalytic Applications

Advani,

Kumar,

Srivastava

2023

Catalysis in Confined Frameworks

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Selective Catalytic Reduction of NO_x with Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range

et al. 2018

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Copper‐exchanged H‐SAPO‐47 zeolites were synthesized by an aqueous solution ion exchange method and applied in the selective catalytic reduction of NO with NH3 (SCR). The microporous chabazite (CHA) structure of the catalysts was characterized and confirmed using synchrotron X‐ray diffraction and nitrogen adsorption–desorption experiments. The synthesized Cux‐SAPO‐47 catalysts exhibited excellent SCR activity and nearly 100 % N2 selectivity in a wide temperature range. The Cu0.1‐SAPO‐47 sample exhibited higher activity than the other samples below 250 °C. The weak Lewis acid sites originating from the introduction of Cu2+ were more active than the Brønsted acid sites of the zeolites framework at low temperature. Two types of isolated Cu2+ species with different coordination surroundings were found, namely, Cu2+ cations bonded with the six‐membered rings and those bonded in the CHA cages. The former species exhibited good stability and activity at high temperature, whereas the latter ones were more active at low temperature. The Cu0.1‐SAPO‐47 catalyst provided a considerable amount of isolated Cu2+ bonded in the CHA cages. These results indicated that active Lewis acid sites and isolated Cu2+ species are responsible for their excellent SCR activity.

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The effect of various templates on the NH3-SCR activities over Cu/SAPO-34 catalysts

Cited by 101 publications

References 32 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

Tailoring the Porosity and Active Sites in Silicoaluminophosphate Zeolites and Their Catalytic Applications

Selective Catalytic Reduction of NO_x with Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range

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The effect of various templates on the NH3-SCR activities over Cu/SAPO-34 catalysts

Cited by 101 publications

References 32 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

Tailoring the Porosity and Active Sites in Silicoaluminophosphate Zeolites and Their Catalytic Applications

Selective Catalytic Reduction of NOx with Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range

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Selective Catalytic Reduction of NO_x with Ammonia over Copper Ion Exchanged SAPO‐47 Zeolites in a Wide Temperature Range