Co–Mn–Al mixed oxides as catalysts for ammonia oxidation to N2O

Ludvíková, Jana; Jabłońska, Magdalena; Jirátová, Květa; Chmielarz, Lucjan; Balabánová, Jana; Kovanda, František; Obalová, Lucie

doi:10.1007/s11164-015-2174-3

Cited by 12 publications

(8 citation statements)

References 41 publications

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“…Selective catalytic oxidation (SCO) of ammonia is a technology which can be used as an environmentally friendly method of ammonia abatement where N 2 and H 2 O are produced as the major products. Both transition metals − and noble metals − were utilized as catalysts in the SCO of ammonia. Various catalytic systems in SCO of ammonia, including noble metals, transition metal oxides, and modified zeolites, were reviewed by Chmielarz et al Among these metals, silver is considered as a promising low-temperature catalyst due to its high activity and high N 2 selectivity. , The catalytic effect of silver nanoparticles on SCO reactions as well as their interactions with other metal systems were also investigated in the literature. ,,, However, a detailed fundamental understanding of the ammonia SCO reaction mechanism on silver single crystals at the atomic/molecular level is still missing.…”

Section: Introductionmentioning

confidence: 99%

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Karatok¹,

Vovk

Koç³

et al. 2017

J. Phys. Chem. C

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Ammonia-selective catalytic oxidation was studied on the planar Ag(111) single-crystal model catalyst surface under ultra-highvacuum (UHV) conditions. A variety of oxygen species were prepared via ozone decomposition on pristine Ag(111). Surface coverages of oxygen species were quantified by temperature-programmed desorption (TPD) and X-ray photoemission spectroscopy techniques. Exposure of ozone on Ag(111) at 140 K led to a surface atomic oxygen (O a ) overlayer. Lowenergy electron diffraction experiments revealed that annealing of this atomic oxygen-covered Ag(111) surface at 473 K in UHV resulted in the formation of ordered oxide surfaces (O ox ) with p(5×1) or c(4×8) surface structures. Ammonia interactions with O/Ag(111) surfaces monitored by temperature-programmed reaction spectroscopy indicated that disordered surface atomic oxygen selectively catalyzed N−H bond cleavage, yielding mostly N 2 along with minor amounts of NO and N 2 O. Higher coverage O/Ag(111) surfaces, whose structure was tentatively assigned to a bulklike amorphous silver oxide (O bulk ), showed high selectivity toward N 2 O formation (rather than N 2 ) due to its augmented oxygen density. In contrast, ordered surface oxide overlayers on Ag(111) (where the order was achieved by annealing the oxygen adlayer to 473 K) showed only very limited reactivity toward ammonia. The nature of the adsorbed NH 3 species on a clean Ag(111) surface and its desorption characteristics were also investigated via infrared reflection absorption spectroscopy and TPD techniques. Current findings demonstrate that the Ag(111) surface can selectively oxidize NH 3 to N 2 under well-defined experimental conditions without generating significant quantities of environmentally toxic species such as NO 2 , NO, or N 2 O.

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Section: Introductionmentioning

confidence: 99%

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Karatok¹,

Vovk

Koç³

et al. 2017

J. Phys. Chem. C

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“…The first, expected at about 240 nm, is assigned to the O-Mn 2+ ligand-to-metal charge-transfer transition and the 6 A 1g → 4 T 1g ligand field transition of distorted octahedral Mn 2+ . The band at 315 nm is related to O-Mn 3+ ligand-to-metal charge-transfer transition [29]. Moreover, the broad shoulder above 350 nm is possibly related to the O-Mn 2+ ligand-to-metal 6 A 1g → 4 T 2g transition [29].…”

Section: Resultsmentioning

confidence: 93%

Catalytic Performance of Bimetallic Systems (Cu-Fe, Cu-Mn, Fe-Mn) Based on Spherical MCM-41 Modified by Template Ion-Exchange in NH3-SCR Process

et al. 2022

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Mesoporous silica of MCM-41 type with spherical morphology was modified with copper, iron, or manganese as well as pairs of these metals by template ion-exchange (TIE) method. The obtained samples were characterized with respect to their structure (XRD), morphology (SEM-EDS), textural parameters (low-temperature N2 sorption), surface acidity (NH3-TPD), transition metal loadings (ICP-OES), their deposited forms (UV-vis DRS) and reducibility (H2-TPR). The catalytic performance of monometallic and bimetallic samples in the selective catalytic reduction of NO with ammonia (NH3-SCR) was tested. The best catalytic results presented a bimetallic copper-manganese sample, which was significantly more active than the mechanical mixture of monometallic copper and manganese catalysts. The synergistic cooperation of manganese and copper species is possibly related to charge relocation between them, resulting in activation of the catalyst in oxidation of NO to NO2, which is necessary for the fast NH3-SCR reaction.

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“…In this study, the products of oxidation of ammonia in aqueous solution are gaseous nitrogen in the gas phase and the residual NH 4 + , NO 2 − , and NO 3 − in the liquid phase. Among them, gaseous nitrogen may include N 2 , N 2 O, NO, NO 2 , NH 3 [13,43,44]. The production of NO 2 − and NO 3 − was derived from the oxidation of NH 4 + and NH 3 (aq).…”

Section: Resultsmentioning

confidence: 99%

Ultrasound-Enhanced Catalytic Ozonation Oxidation of Ammonia in Aqueous Solution

Liu

Chen

et al. 2019

IJERPH

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Excessive ammonia is a common pollutant in the wastewater, which can cause eutrophication, poison aquatic life, reduce water quality and even threaten human health. Ammonia in aqueous solution was converted using various systems, i.e., ozonation (O3), ultrasound (US), catalyst (SrO-Al2O3), ultrasonic ozonation (US/O3), ultrasound-enhanced SrO-Al2O3 (SrO-Al2O3/US), SrO-Al2O3 ozonation (SrO-Al2O3/O3) and ultrasound-enhanced SrO-Al2O3 ozonation (SrO-Al2O3/US/O3) under the same experimental conditions. The results indicated that the combined SrO-Al2O3/US/O3 process achieved the highest NH4+ conversion rate due to the synergistic effect between US, SrO-Al2O3 and O3. Additionally, the effect of different operational parameters on ammonia oxidation in SrO-Al2O3/O3 and SrO-Al2O3/US/O3 systems was evaluated. It was found that the ammonia conversion increased with the increase of pH value in both systems. The NH3(aq) is oxidized by both O3 and ·OH at high pH, whereas the NH4+ oxidation is only carried out through ·OH at low pH. Compared with the SrO-Al2O3/O3 system, the ammonia conversion was significantly increased, the reaction time was shortened, and the consumption of catalyst dosage and ozone were reduced in the SrO-Al2O3/US/O3 system. Moreover, reasonable control of ultrasonic power and duty cycle can further improve the ammonia conversion rate. Under the optimal conditions, the ammonia conversion and gaseous nitrogen yield reached 83.2% and 51.8%, respectively. The presence of tert-butanol, CO32−, HCO3−, and SO42− inhibited the ammonia oxidation in the SrO-Al2O3/US/O3 system. During ammonia conversion, SrO-Al2O3 catalyst not only has a certain adsorption effect on NH4+ but accelerates the O3 decomposition to ·OH.

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Co–Mn–Al mixed oxides as catalysts for ammonia oxidation to N2O

Cited by 12 publications

References 41 publications

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Selective Catalytic Ammonia Oxidation to Nitrogen by Atomic Oxygen Species on Ag(111)

Catalytic Performance of Bimetallic Systems (Cu-Fe, Cu-Mn, Fe-Mn) Based on Spherical MCM-41 Modified by Template Ion-Exchange in NH3-SCR Process

Ultrasound-Enhanced Catalytic Ozonation Oxidation of Ammonia in Aqueous Solution

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