Enhanced catalytic performance in low-temperature NH3-SCR process of spherical MCM-41 modified with Cu by template ion-exchange and ammonia treatment

Jankowska, Aleksandra; Chłopek, Agata; Kowalczyk, Andrzej; Rutkowska, Małgorzata; Mozgawa, W.; Michalík, Marek; Liu, Shiquan; Chmielarz, Lucjan

doi:10.1016/j.micromeso.2021.110920

Cited by 26 publications

(40 citation statements)

References 32 publications

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“…In the case of the 100Cu sample with the highest copper loading the presence of bulky CuO crystallites was found ( Figure 5C). A similar effect was reported in our previous papers for the deposition of copper by the TIE method into pure silica spherical MCM-41 [12]. It seems possible that surfactants extracted from mesoporous silica are organised to form micellar structures in alcohol solution.…”

Section: Resultssupporting

confidence: 87%

“…In positions characteristic of the (110) and (200) reflections only slightly increased baseline level can be observed. Thus, the incorporation of aluminum into silica walls of spherical MCM-41 decreased ordering of pores in comparison to pure silica spherical MCM-41 [12]. Modification of alumina-silica spherical MCM-41 (Al-S-MCM-41) with copper by template ion-exchange (TIE) did not result in any significant changes of diffractograms ( Figure 1A), indicating stability of the MCM-41 porous structure under conditions of TIE procedure.…”

Section: Resultsmentioning

confidence: 98%

“…The temperature ranges of the NO conversion over 90% for the most active catalysts obtained by TIE-NH 3 and TIE methods in current and previous studies [11,12] are compared in Figure 12. The catalytic tests for all the samples presented in this figure were done under the same conditions.…”

Section: Resultsmentioning

confidence: 99%

“…Moreover, it was shown that the dispersion of deposited copper species can be improved by post-treatment of the copper modified silica samples, directly after TIE, with ammonia solution, which significantly improved their low-temperature activity in the NH 3 -SCR process [11]. Further improvement of the catalytic performance was obtained by the replacement of classical MCM-41 for its spherical form [12], possibly due to improved internal diffusion of reactants in shorter channels. Thus, similarly to zeolites, mesoporous silica is characterized by high specific surface area and porosity.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, the developed modified TIE method results in the deposition of copper in highly dispersed forms, also in the case of high loadings of this metal. On the other side, in contrast to zeolites, up-till-now only the pure silica supports were used for catalysts preparation by modified TIE method [11,12]. Thus, the next step of the studies, presented in this manuscript, has been focused on the analysis of aluminum containing silica spherical MCM-41 as support of the catalysts for the NH 3 -SCR process.…”

Section: Introductionmentioning

confidence: 99%

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Spherical Al-MCM-41 Doped with Copper by Modified TIE Method as Effective Catalyst for Low-Temperature NH3-SCR

et al. 2021

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Aluminum containing silica spherical MCM-41 was synthesized and modified with copper by the template ion-exchange method (TIE) and its modified version, including treatment of the samples with ammonia solution directly after template ion-exchange (TIE-NH3). The obtained samples were characterized with respect to their chemical composition (ICP-OES), structure (XRD), texture (low temperature N2 sorption), morphology (SEM-EDS), form and aggregation of deposited copper species (UV-vis DRS), reducibility of copper species (H2-TPR), and surface acidity (NH3-TPD). The deposition of copper by the TIE-NH3 method resulted in much better dispersion of this metal on the MCM-41 surface comparing to copper introduced by TIE method. It was shown that such highly dispersed copper species, mainly monomeric Cu2+ cations, deposited on aluminum containing silica spheres of MCM-41, are significantly more catalytically effective in the NH3-SCR process than analogous catalysts containing aggregated copper oxide species. The catalysts obtained by the TIE-NH3 method effectively operated in much broader temperature and were less active in the side process of direct ammonia oxidation by oxygen.

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Section: Resultssupporting

confidence: 87%

Section: Resultsmentioning

confidence: 98%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spherical Al-MCM-41 Doped with Copper by Modified TIE Method as Effective Catalyst for Low-Temperature NH3-SCR

et al. 2021

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Studies of NO Reduction with Ammonia Over Copper Species Deposited on MCM‐41 Nanospheres ‐ Experimental Evidence of Reaction Mechanism

et al. 2023

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Nanospheres of MCM-41 were modified with copper by template ion-exchange (TIE) and cocondensation methods. In the samples modified by TIE, dispersion of copper was significantly improved by their post-treatment in ammonia solutions. Highly dispersed copper species were significantly more active in low-temperature NH 3 -SCR than CuO aggregates. Copper dispersed on silica MCM-41 catalytically operated at lower temperatures than copper deposited on silica-alumina MCM-41. The studies of reaction mechanism showed that ammonia and NO x species compete for these same adsorption sites (copper cations) and NH 3 can remove NO x from such sites. Dispersed copper species are more active in NO to NO 2 oxidation than CuO aggregates. Accumulation of oxidised NO x species in the absence of ammonia was more privileged on CuO aggregates. It is postulated that the main reaction pathway in the lowtemperature range is reaction of ammonia bounded to copper with NO x from gas phase or loosely bounded to the catalyst surface.

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Mesoporous silicas of MCM-48 and MCM-41 types doped with copper by modified template ion-exchange method as effective catalysts for low-temperature reduction of nitrogen oxide with ammonia

Pietraszek,

Kowalczyk,

Piwowarska

et al. 2023

Reac Kinet Mech Cat

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Mesoporous silica materials of MCM-48 and MCM-41 types were synthetized by surfactant directed methods and modified with copper by template ion-exchange (TIE) protocol and its extended version including post-treatment of modified silicas with ammonia solution. Obtained samples were characterized with respect to their textural parameters (low-temperature N2 sorption), porous structure, chemical composition, surface acidity (NH3-TPD), form and aggregation of deposited copper species (UV–vis-DRS) as well as their reducibility (H2-TPR). It was shown that application of TIE method resulted in deposition of copper into MCM-48 in more dispersed forms comparing to MCM-41. Both, in the case of MCM-41 and MCM-48, treatment of the samples with ammonia directly after copper introduction resulted in deposition mainly monomeric copper cations. The catalysts containing such dispersed copper species were more active in the low-temperature NH3-SCR process. The NO conversion above 90% with selectivity to N2 above 97% was obtained in the temperature range of 225–325 °C. CuO aggregates, deposited on mesoporous silicas, were found to be active in the side process of direct ammonia oxidation at higher temperatures.

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Enhanced catalytic performance in low-temperature NH3-SCR process of spherical MCM-41 modified with Cu by template ion-exchange and ammonia treatment

Cited by 26 publications

References 32 publications

Spherical Al-MCM-41 Doped with Copper by Modified TIE Method as Effective Catalyst for Low-Temperature NH3-SCR

Spherical Al-MCM-41 Doped with Copper by Modified TIE Method as Effective Catalyst for Low-Temperature NH3-SCR

Studies of NO Reduction with Ammonia Over Copper Species Deposited on MCM‐41 Nanospheres ‐ Experimental Evidence of Reaction Mechanism

Mesoporous silicas of MCM-48 and MCM-41 types doped with copper by modified template ion-exchange method as effective catalysts for low-temperature reduction of nitrogen oxide with ammonia

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