Cu and Fe modified derivatives of 2D MWW-type zeolites (MCM-22, ITQ-2 and MCM-36) as new catalysts for DeNO x process

Rutkowska, Małgorzata; Díaz, Urbano; Palomares, Emilio; Chmielarz, Lucjan

doi:10.1016/j.apcatb.2015.01.016

Cited by 66 publications

(60 citation statements)

References 38 publications

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“…Introduced copper occupied not only the ion-exchange positions but also formed small oligomeric or bulky CuO species on the samples surface. Similar observations were done in the previous studies concerning Cu-modified MCM-22 zeolite [18]. The highest values (also the highest increase in acidity) of CA were obtained for the samples desilicated for 2 h, which, as it was shown by AAS measurements, were loaded with the highest Cu content (the highest Cu/Al ratio).…”

Section: Characteristics Of the Cu-modified Samplessupporting

confidence: 89%

“…The investigations on the catalytic efficiency of mesoporous zeolites in the DeNOx process showed their higher activity and stability in comparison to conventional microporous zeolites. Zeolites with the hierarchical porous structure were found to be more active at high temperatures (at which conventional zeolites promote ammonia oxidation) and in long term stability tests [13][14][15][16][17][18]. Various mesoporous zeolites with different pore structure, such as ZSM-5 [13][14][15][16][17], ZSM-12 [17], ITQ-2 or MCM-36 [18] were examined in the NH3-SCR process.…”

Section: )4 No + 4 Nh3 + O2 → 4 N2 + 6 H2omentioning

confidence: 99%

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Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH 3 -SCR and NH 3 -SCO processes

Rutkowska

Pacia

Basąg

et al. 2017

Microporous and Mesoporous Materials

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In the presented manuscript an influence of the mesoporosity generation in commercial ZSM-5 zeolite on its catalytic performance in two environmental processes, such as NO reduction with ammonia (NH3-SCR, Selective Catalytic Reduction of NO with NH3) and NH3 oxidation (NH3-SCO, Selective Catalytic Oxidation of NH3) was examined. Micro-mesoporous catalysts with the properties of ZSM-5 zeolite were obtained by desilication with NaOH and NaOH/TPAOH (tetrapropylammonium hydroxide) mixture with different ratios (TPA+/OH-= 0.2, 0.4, 0.6, 0.8 and ∞) and for different durations (1, 2, 4 and 6 h). The results of the catalytic studies (over the Cu-exchanged samples) showed higher activity of this novel mesostructured group of zeolitic materials. Enhanced catalytic performance was related to the generated mesoporosity (improved Hierarchy Factor (HF) of the samples), that was observed especially with the use of Pore Directing Agent (PDA) additive, TPAOH. Applied desilication conditions did not influence significantly the crystallinity of the samples (X-ray diffraction analysis (XRD)), despite the treatment for 6 h in NaOH solution, which was found to be too severe to preserve the zeolitic properties of the samples. The modified porous structure and accessibility of acid sites (increased surface acidity determined by temperature programmed desorption of ammonia (NH3-TPD)) influenced the red-ox properties of copper species introduced by ion-exchange method (temperature programmed reduction with hydrogen (H2-TPR). Increased acidity of the micro-mesoporous samples, as well as the content of easily reducible copper species resulted in a significant improvement of Cu-ZSM-5 catalytic efficiency in the NH3-SCR and NH3-SCO processes.

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Section: Characteristics Of the Cu-modified Samplessupporting

confidence: 89%

Section: )4 No + 4 Nh3 + O2 → 4 N2 + 6 H2omentioning

confidence: 99%

Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH 3 -SCR and NH 3 -SCO processes

Rutkowska

Pacia

Basąg

et al. 2017

Microporous and Mesoporous Materials

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“…The system is highly active in the SCR process, but the use of noble metals in nitric acid plants is operationally unfavorable due to the high cost of the catalysts and their low selectivity to N 2 [19][20][21]. Many innovative supports have been proposed in the scientific literature so far, such as acti-vated carbon [22,23], carbon nanotubes [24,25], layered double hydroxides [26,27], layered clays [28][29][30][31], and zeolites [32][33][34][35][36]. Among them, significant attention was paid to zeolites that are microporous aluminosilicate minerals, either naturally occurring or industrially produced on a large scale.…”

Section: Introductionmentioning

confidence: 99%

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

et al. 2021

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Natural zeolite of the heulandite-type framework was modified with iron and tested as a catalyst for the selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) in the temperature range of 150–450 °C. The catalyst was prepared at a laboratory scale in a powder form and then the series of experiments of its shaping into tablets was conducted. Physicochemical studies of the catalyst (N2 sorption at −196 °C, FT-IR, XRD, UV-vis) were performed to determine the textural and structural properties and identify the surface functional groups, the crystalline structure of the catalysts and the form and aggregation of the active phase. The activity tests over the shaped catalyst were performed industry-reflecting conditions, using tail gases from the pilot nitric acid plant. The influence of a temperature, catalyst load, and the amount of reducing agent (ammonia) on the NOx reduction process were investigated. The results of catalytic tests that were performed on model gas mixture showed that non-modified clinoptilolite exhibited around 58% conversion of NO at 450 °C. The temperature window of the shaped catalyst shifted to a higher temperature range in comparison to the powder sample. The catalytic performance of the shaped Fe-clinoptilolite in the industry-reflecting conditions was satisfactory, especially at 450 °C. Additionally, it was observed that the ratio of N2O concentration downstream and upstream of the catalytic bed was below 1, which indicated that the catalyst exhibited activity in both DeNOx and DeN2O process.

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“…Corma and co-workers [28] found that Cu/MCM-22 zeolites were active catalysts with relatively high hydrothermal stability in selective catalytic reduction of NO with propane. Rutkowska and co-workers [29] found that Cu/MCM-22 zeolites could reach about 75% NO conversion with >90% N 2 selectivity at only 180 • C in NH 3 -SCR. In addition, Cu/MCM-22 zeolites could still maintain 100% NO conversion and >90% N 2 selectivity at 250-450 • C after hydrothermal aging in air with H 2 O at 550 • C for 3 h, which indicated that they were potential catalysts in NH 3 -SCR with good hydrothermal stability.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Performances of Cu/MCM-22 Zeolites with Different Cu Loadings in NH3-SCR

et al. 2020

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The NH3-SCR activities and hydrothermal stabilities of five xCu/MCM-22 zeolites with different Cu loadings (x = 2–10 wt%) prepared by incipient wetness impregnation method were systematically investigated. The physicochemical properties of xCu/MCM-22 zeolites were analyzed by XRD, nitrogen physisorption, ICP-AES, SEM, NH3-TPD, UV-vis, H2-TPR and XPS experiments. The Cu species existing in xCu/MCM-22 are mainly isolated Cu2+, CuOx and unreducible copper species. The concentrations of both isolated Cu2+ and CuOx species in xCu/MCM-22 increase with Cu contents, but the increment of CuOx species is more distinct, especially in high Cu loadings (>4 wt%). NH3-SCR experimental results demonstrated that the activity of xCu/MCM-22 is sensitive to Cu content at low Cu loadings (≤4 wt%). When the Cu loading exceeds 4 wt%, the NH3-SCR activity of xCu/MCM-22 is irrelevant to Cu content due to the severe pore blockage effects caused by aggregated CuOx species. Among the five xCu/MCM-22 zeolites, 4Cu/MCM-22 with moderate Cu content has the best NH3-SCR performance, which displays higher than 80% NOx conversions in a wide temperature window (160–430 °C). Furthermore, the hydrothermal aging experiments (xCu/MCM-22 was treated at 750 °C for 10 h under 10% water vapor atmosphere) illustrated that all the xCu/MCM-22 zeolites exhibit high hydrothermal stability in NH3-SCR reactions.

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Cu and Fe modified derivatives of 2D MWW-type zeolites (MCM-22, ITQ-2 and MCM-36) as new catalysts for DeNO x process

Cited by 66 publications

References 38 publications

Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH 3 -SCR and NH 3 -SCO processes

Catalytic performance of commercial Cu-ZSM-5 zeolite modified by desilication in NH 3 -SCR and NH 3 -SCO processes

Modified Zeolite Catalyst for a NOx Selective Catalytic Reduction Process in Nitric Acid Plants

Catalytic Performances of Cu/MCM-22 Zeolites with Different Cu Loadings in NH3-SCR

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