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Cas Database

7727-37-9

7727-37-9

Identification

  • Product Name:Nitrogen

  • CAS Number: 7727-37-9

  • EINECS:231-783-9

  • Molecular Weight:28.0134

  • Molecular Formula: N2

  • HS Code:2804300000

  • Mol File:7727-37-9.mol

Synonyms:Diatomicnitrogen;Dinitrogen;Molecular nitrogen;Nitrogen (N2);Nitrogen gas;Nitrogennutrition (plant);Nitrogen-14;CHEBI:17997;HSDB 5060;

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Safety information and MSDS view more

  • Signal Word:Warning

  • Hazard Statement:H280 Contains gas under pressure; may explode if heated

  • First-aid measures: General adviceConsult a physician. Show this safety data sheet to the doctor in attendance.If inhaled Fresh air, rest. Artificial respiration may be needed. Refer for medical attention. In case of skin contact ON FROSTBITE: rinse with plenty of water, do NOT remove clothes. Refer for medical attention . In case of eye contact First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. If swallowed Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician. Excerpt from ERG Guide 121 [Gases - Inert]: Vapors may cause dizziness or asphyxiation without warning. Vapors from liquefied gas are initially heavier than air and spread along ground. (ERG, 2016)Inhalation can cause asphyxiation, if atmosphere does not contain oxygen; dizziness, unconsciousness, or even death can result. Contact of liquid with skin or eyes causes frostbite burns. (USCG, 1999) Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Simple asphyxiants and related compounds/

  • Fire-fighting measures: Suitable extinguishing media If material involved in fire: Extinguish fire using agent suitable for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Cool all affected containers with flooding quantiites of water. Apply water from as far a distance as possible. /Nitrogen, compressed/ Excerpt from ERG Guide 121 [Gases - Inert]: Non-flammable gases. Containers may explode when heated. Ruptured cylinders may rocket. (ERG, 2016)Behavior in Fire: Containers may explode when heated. (USCG, 1999) Wear self-contained breathing apparatus for firefighting if necessary.

  • Accidental release measures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapours, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust. For personal protection see section 8. Ventilation. Personal protection: self-contained breathing apparatus. Soak up with inert absorbent material and dispose of as hazardous waste. Keep in suitable, closed containers for disposal.

  • Handling and storage: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Avoid exposure - obtain special instructions before use.Provide appropriate exhaust ventilation at places where dust is formed. For precautions see section 2.2. Fireproof if in building. Cool. Keep in a well-ventilated room.Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage.

  • Exposure controls/personal protection:Occupational Exposure limit valuesBiological limit values Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday. Eye/face protection Safety glasses with side-shields conforming to EN166. Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU). Skin protection Wear impervious clothing. The type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace. Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique(without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it. Respiratory protection Wear dust mask when handling large quantities. Thermal hazards

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Relevant articles and documentsAll total 805 Articles be found

Can TiO2 promote the reduction of nitrates in water?

Sa, Jacinto,Berger, Thomas,Foettinger, Karin,Riss, Alexander,Anderson, James A.,Vinek, Hannelore

, p. 282 - 291 (2005)

Monometallic palladium catalysts were synthesized using different titanium supports and tested for the reduction of nitrates from aqueous solutions using hydrogen as a reductant. The Pd/TiO2 catalysts were characterized by electron paramagnetic resonance (EPR), low-temperature Fourier transform infrared (FTIR) spectroscopy of adsorbed CO, and X-ray diffraction (XRD). The catalysts studied exhibited a high activity for nitrate removal with a lower tendency for nitrite formation than the conventional bimetallic Pd catalysts. Although ammonium formation was greater than desired, the use of a monometallic catalyst for this two-step reduction process is significant and suggests that a single site may be responsible for both reduction stages. The titanium support (particularly the Ti3+ centers generated during prereduction in the presence of Pd) appear to play an important role in the nitrate degradation process. The potential role of Pd β-hydride in generating these Ti 3+ centers is discussed.

Complexation of nitrous oxide by frustrated lewis pairs

Otten, Edwin,Neu, Rebecca C.,Stephan, Douglas W.

, p. 9918 - 9919 (2009)

(Figure Presented) Frustrated Lewis pairs comprised of a basic yet sterically encumbered phosphine with boron Lewis acids bind nitrous oxide to give intact PNNOB linkages. The synthesis, structure, and bonding of these species are described.

Reaction between NOx and NH3 on Iron Oxide-Titanium Oxide Catalyst

Kato, Akira,Matsuda, Shimpei,Kamo, Tomoichi,Nakajima, Fumito,Kuroda, Hiroshi,Narita, Tsuneo

, p. 4099 - 4102 (1981)

The reduction of NOx (NO2 alone or mixture of NO and NO2) with NH3 on iron oxide-titanium oxide catalyst was studied using a flow reactor.The reaction between NO2 and NH3 proceeds at 3:4 mole ratio in the presence or absence of oxygen.When the reaction gas mixture contain equal amounts of NO and NO2, the reaction consuming equimolal NO and NO2 proceeds preferentially at a NH3/NOx ratio of unity.The rate of the reaction is faster than either the NO-NH3 or NO2-NH3 reaction.The overall reactions between NOx (NO2, NO+NO2) and NH3 are given as 6NO2+8NH3->7N2+12H2O and NO+NO2+2NH3->2N2+3H2O.Reaction mechanisms are proposed to explain the experimental results.

Characterization of vanadium and titanium oxide supported SBA-15

Segura,Cool,Kustrowski,Chmielarz,Dziembaj,Vansant

, p. 12071 - 12079 (2005)

Supported vanadium and titanium oxide catalysts were prepared by adsorption and subsequent calcination of the vanadyl and titanyl acetylacetonate complexes, respectively, on mesoporous SB A-15 by the molecular designed dispersion (MDD) method. Liquid and gas phase depositions at different temperatures were carried out with vanadyl acetylacetonate, and the different results together with those of titanyl acetylacetonate in the liquid phase deposition were discussed. The bonding mechanism, the influence of the metal interaction with the support material, and differences due to the way of deposition and the temperature were investigated by TGA, chemical analysis, FTIR, and Raman spectroscopy. Elevated dissolving temperatures in the liquid phase led to higher final loadings on the SBA-15 without the formation of clusters, even at high loadings. The decomposition of the anchored vanadium and titanium complexes, their thermal stability, and the conversion to the covalently bound VOX and TiOx species on SBA-15 were studied and investigated by in situ transmission IR spectroscopy. In general, the titanium complex is more reactive than the vanadium complex toward the surface of SBA-15 and has a higher thermal stability. The MDD method of the VO(acac)2 and TiO(acac)2 enables to create a dispersed surface of supported VOx and TiOx, respectively. The structure configurations of VOx and TiOx oxide catalysts obtained at different metal loadings were studied by Raman spectroscopy. Pore size distributions, XRD, and N2 sorption confirmed the structural stability of these materials after grafting. VOx/SBA-15 and TiO x/SBA-15 samples, with different metal loadings, were also catalytically tested for the selective catalytic reduction (SCR) of NO with ammonia. ? 2005 American Chemical Society.

The 193 (and 248) nm photolysis of HN3: Formation and internal energy distributions of the NH (a1Δ, b1Σ+, A3Π, and c1Π) states

Rohrer, F.,Stuhl, F.

, p. 4788 - 4799 (1988)

The UV photolysis of HN3 at 193 nm was investigated in detail in the bulk phase at 300 K.NH radicals in the X, a, b, A, and c states were found to be formed with quantum yields 0.0019 , 0.4, 0.017, 0.00015, and 0.000 61, respectively.Relative rotational and vibrational populations were measured for all states except for NH(X).Average translational energies were estimated for NH(a,ν = 0 and 1 ) and NH(b,ν = 0).The 248 nm photolysis of HN3 was reinvestigated with respect to processes forming NH radicals other than NH(a).The observed energy distributions differ for both laser wavelengths and for high and low lying NH states.The distribution can be better described by a simple impulsive than by a statistical model.Some conclusions are drawn concerning the upper HN3 potential surfaces involved.

Photocatalytic reduction of nitrate over chalcopyrite CuFe0.7Cr0.3S2 with high N2 selectivity

Wang, Rong,Yue, Mufei,Cong, Rihong,Gao, Wenliang,Yang, Tao

, p. 731 - 736 (2015)

Photocatalytic reduction of nitrate (NO3-) is a green and potentially inexpensive technique for reducing NO3- pollution in ground water. TiO2-based photocatalysts have been studied extensively for this purpose. In the present study, the semiconducting catalyst CuFe0.7Cr0.3S2 was applied to NO3- reduction. Loading this catalyst with metal co-catalysts (Ru, Au, Cu, Ag, Pt, and Pd) greatly increased the rate of NO3- reduction and the N2 selectivity. In addition, there was a synergistic enhancement of the photocatalytic performance when the catalyst was loaded two co-catalysts. For example, the catalyst loaded with Pd and Au at mass fractions of 0.75% and 3%, respectively, could photocatalyze the complete reduction of NO3- in a 100 ppm N aqueous solution with 100% N2 selectivity in less than 5 h with UV irradiation. However, with an inner irradiation from a full-arc Xe lamp, the NO3- conversion rate reduced to 0.065 mg N/h, probably because of the low density of the photoexcited electrons. The results show the potential of metal sulfides for photocatalytic reduction of NO3-, and the possibility of use of visible light.

Oscillations in the N2O-H2 reaction over Ir(1 1 0). Route to chaos

Carabineiro, Sónia A.C.,Van Noort, Wibo D.,Nieuwenhuys, Bernard E.

, p. 96 - 102 (2003)

The study described in the present paper is focused on the N2O-H2 reaction on the Ir(1 1 0) surface and, in particular, on different kinds of oscillatory behaviour, including the route to chaos. Oscillations in rate were observed in the temperature range between 460 and 464 K, at a N2O pressure of 1 × 10-6 mbar with H2/N2O ratios close to 1. Upon minor changes in the H2/N2O ratio, a series of period doublings is observed, resulting finally in aperiodic behaviour.

Nature and catalytic role of active silver species in the lean NO x reduction with C3H6 in the presence of water

Iglesias-Juez,Hungria,Martinez-Arias,Fuerte,Fernandez-Garcia,Anderson,Conesa,Soria

, p. 310 - 323 (2003)

A study of the lean NOx reduction activity with propene in the presence of water over Ag/Al2O3 catalysts with different silver loadings (1.5-6 wt%) has been done using X-ray diffraction, ultraviolet-visible spectroscopy, transmission electron microscopy, and in situ diffuse reflectance infrared and X-ray absorption spectroscopies under reaction conditions. The catalysts were prepared by an impregnation method employing EDTA complexes that allow highly dispersed silver phases to be obtained, which are stabilized under reaction conditions by strong interactions with the support. It is shown that the active species corresponds to silver aluminate-like phases with tetrahedral local symmetry. The role of silver in the reaction mechanism is shown to be mainly in the activation of NO x and propene species. In particular, the silver entities have been found to offer a new reaction path for propene activation which involves generation of acrylate species as a partially oxidized active intermediate. Differences between two active catalysts containing 1.5 and 4.5 wt% of Ag suggest that optimization of the SCR activity can be related to the oxygen lability of the tetrahedral silver aluminate-like phase present in the catalyst. As postulated previously, the high nonselective propene oxidation activity of the highest loaded sample (with 6 wt% Ag) appears to be related to formation of metallic silver surface states at low reaction temperatures which are active for NO dissociation.

Nano-spatially confined Pd-Cu bimetals in porous N-doped carbon as an electrocatalyst for selective denitrification

Bai, Nan,Chen, Zehan,Fan, Jianwei,Gu, Tianhang,Teng, Wei,Zhang, Wei-Xian,Zhao, Dongyuan

, p. 9545 - 9553 (2020)

Bimetals have attracted considerable attention as electrocatalysts towards selective reduction of nitrate to benign dinitrogen. Design of highly efficient and stable bimetallic catalysts by taking the effects of both active sites increasing and synergistic composition into account is of paramount importance but still a grand challenge. Herein we report novel bimetallic Pd-Cu nanoparticles (NPs) incorporated in porous N-doped carbon octahedra prepared by a spatial confinement strategy ofin situpyrolysis of metal-organic frameworks with the assistance of polyvinyl pyrrolidone (PVP) as electrocatalysts achieving targeted denitrification. Pd-Cu NPs exhibit superior dispersity with a N-doped matrix and are strongly dependent on the variation of PVP, Pd precursor and pyrolysis temperature. The material shows high efficiency (~97.1%) for the reduction of nitrate from 100 to 2.9 mg NO3--N L-1(well below drinking water standards of 10 mg NO3--N L-1), and especially the selectivity over 83% for benign N2at neutral pH within 24 h. Encapsulated and well-dispersed Pd-Cu NPs and doped N in the carbonaceous matrix synergistically enhance the interfacial electron transfer for transformation of NO3--N(v). Porous structures endow the catalyst with outstanding stability after eight cycles and over a wide pH of 4-10. More importantly, the nanocatalyst performs well with real contaminated water (selectivity of 91% for nitrogen) in laboratory batch reactors. This nanocatalyst shows promise in wastewater treatment and environmental remediation due to the spatial confinement strategy and introduction of heterogeneous atoms.

Topsoee, N.-Y.,Dumesi, J. A.,Topsoee, H.

, p. 241 - 252 (1995)

Promotional effects of Zr on K+-poisoning resistance of CeTiOx catalyst for selective catalytic reductionof NOx with NH3

Xu, Baoqiang,Xu, Haidi,Lin, Tao,Cao, Yi,Lan, Li,Li, Yuanshan,Feng, Xi,Gong, Maochu,Chen, Yaoqiang

, p. 1354 - 1361 (2016)

CeTiOx and CeZrTiOx catalysts were prepared by a coprecipitation method and used for selective catalytic reduction of NOx by NH3 (NH3-SCR). Various amounts of KNO3 were impregnated on the catalyst surface to investigate the effects of Zr addition on the K+-poisoning resistance of the CeTiOx catalyst. The NH3-SCR performance of the catalysts showed that the NOx removal activity of the Zr-modified catalyst after poisoning was better than that of the CeTiOx catalyst. Brunauer-Emmett-Teller data indicated that the Zr-containing catalyst had a larger specific surface area and pore volume both before and after K+ poisoning. X-ray diffraction, Raman spectroscopy, and transmission electron microscopy showed that Zr doping inhibited anatase TiO2 crystal grain growth, i.e., the molten salt flux effect caused by the loaded KNO3 was inhibited. The Ce 3d X-ray photoelectron spectra showed that the Ce3+/Ce4+ ratio of CeZrTiOx decreased more slowly than that of CeTiOx with increasing K+ loading, indicating that Zr addition preserved more crystal defects and oxygen vacancies; this improved the catalytic performance. The acidity was a key factor in the NH3-SCR performance; the temperature-programmed desorption of NH3 results showed that Zr doping inhibited the decrease in the surface acidity. The results suggest that Zr improved the K+-poisoning resistance of the CeTiOx catalyst.

Deactivation of Cu-Exchanged Automotive-Emission NH3-SCR Catalysts Elucidated with Nanoscale Resolution Using Scanning Transmission X-ray Microscopy

Chen, Tiehong,Meirer, Florian,Oord, Ramon,Schmidt, Joel E.,Wang, Ru-Pan,Weckhuysen, Bert M.,Ye, Xinwei,de Groot, Frank,van Ravenhorst, Ilse K.

, p. 15610 - 15617 (2020)

To gain insight into the underlying mechanisms of catalyst durability for the selective catalytic reduction (SCR) of NOx with an ammonia reductant, we employed scanning transmission X-ray microscopy (STXM) to study Cu-exchanged zeolites with the CHA and MFI framework structures before and after simulated 135 000-mile aging. X-ray absorption near-edge structure (XANES) measurements were performed at the Al K- and Cu L-edges. The local environment of framework Al, the oxidation state of Cu, and geometric changes were analyzed, showing a multi-factor-induced catalytic deactivation. In Cu-exchanged MFI, a transformation of CuII to CuI and CuxOy was observed. We also found a spatial correlation between extra-framework Al and deactivated Cu species near the surface of the zeolite as well as a weak positive correlation between the amount of CuI and tri-coordinated Al. By inspecting both Al and Cu in fresh and aged Cu-exchanged zeolites, we conclude that the importance of the preservation of isolated CuII sites trumps that of Br?nsted acid sites for NH3-SCR activity.

MnO2-GO-scroll-TiO2-ITQ2 as a low-temperature NH3-SCR catalyst with a wide SO2-tolerance temperature range

Sun, Liwei,Zhang, Zeshu,Tian, Heyuan,Liu, Peng,Zhang, Yibo,Yang, Xiangguang

, p. 1733 - 1738 (2020)

Three steps are needed to improve the steam-resistance and SO2-resistance of a catalyst for the selective catalytic reduction of NOx through NH3 at low temperature: the first is to introduce a protective layer to reduce the direct contact between SO3 and the catalyst. Then, there is delayed oxidation, which fundamentally reduces the oxidation of SO2 to SO3. If the catalyst is used at a relatively high temperature, it will inevitably produce SO3. The third step is to add a strong acid site in addition to reducing the acidity of the catalyst, which first absorbs NH3 and then absorbs SO3, to seize NH4HSO4, so that it does not cover the active site. GO was used to curl and wrap around the outside of MnO2 nanowires as a protective layer. TiO2 was selectively deposited on oxygen-containing functional groups on GO, which delayed the oxidation ability of the catalyst. ITQ2 molecular sieves acted as strong acid sites to absorb NH4HSO4. The curling behavior of GO outside MnO2 nanowires, the deposition location of TiO2 and the distribution of ITQ2 were explained by morphology and elemental analysis. In the range of 150 °C to 280 °C, the MnO2-GO-scroll-TiO2-ITQ2 catalyst conversion of NO to N2 was more than 85%. Combined with H2-TPR and activity testing, the source of the wide SO2-tolerance temperature range of the catalyst was described in detail.

Study of anode catalysts and fuel concentration on direct hydrazine alkaline anion-exchange membrane fuel cells

Asazawa, Koichiro,Sakamoto, Tomokazu,Yamaguchi, Susumu,Yamada, Koji,Fujikawa, Hirotoshi,Tanaka, Hirohisa,Oguro, Keisuke

, p. B509-B512 (2009)

A platinum-free fuel cell using liquid hydrazine hydrate (N 2H4·H2O) as the fuel and comprised of a cobalt or nickel anode and a cobalt cathode exhibits high performance. In this study, the fuel cell performances using nic

Enhanced NH3 Selective catalytic reduction for NO xAbatement

Forzatti, Pio,Nova, Isabella,Tronconi, Enrico

, p. 8366 - 8368 (2009)

Enhanced NO reduction efficiencies, close to those obtained under the conditions of fast selective catalytic reduction (SCR; see diagram), were achieved over commercial vanadium and ironexchanged zeolite SCR catalysts at low temperatures (200-300°C) in th

Photoelectrochemical conversion of NO3- to N 2 by using a photoelectrochemical cell composed of a nanoporous TiO2 film photoanode and an O2 reducing cathode

Saito, Rie,Ueno, Hirohito,Nemoto, Junichi,Fujii, Yuki,Izuoka, Akira,Kaneko, Masao

, p. 3231 - 3233 (2009)

Photoelectrochemical conversion of nitrate anions into dinitrogen was successfully achieved by using a photoelectrochemical cell composed of a nanoporous TiO2 film photoanode and an O2 reducing cathode in the presence of NH3/su

Promoting effects of Na and Fe impurities on the catalytic activity of CaO in the reduction of NO by CO and H2

Acke, Filip,Panas, Itai

, p. 5127 - 5134 (1998)

The heterogeneous reduction of NO by H2 and CO over different CaO materials is investigated. The dependence of the specific NO reduction rate on the impurity content is demonstrated for both reducing species. The roles of two specific impurities, i.e., Na and Fe, as well as their combined effect are investigated. The apparent activation energies for the NO + CO and NO + H2 reactions are determined for three different calcium oxides. Values between 26 and 28 kcal/mol are obtained. The influence of impurity content is found in the preexponential factor of the Arrhenius equation. A reaction mechanism based on a rate-determining surface-oxygen-abstraction step is suggested. This mechanistic understanding is explored to compare the activities of other alkaline-earth oxides. Particularly, a linear correlation between the apparent activation energy and the lattice parameter is observed.

Catalytic oxidation of ammonia on RuO2(110) surfaces: Mechanism and selectivity

Wang,Jacobi,Sch?ne,Ertl

, p. 7883 - 7893 (2005)

The selective oxidation of ammonia to either N2 or NO on RuO2(110) single-crystal surfaces was investigated by a combination of vibrational spectroscopy (HREELS), thermal desorption spectroscopy (TDS) and steady-state rate measurements under continuous flow conditions. The stoichiometric RuO2(110) surface exposes coordinatively unsaturated (cus) Ru atoms onto which adsorption of NH3 (NH3-cus) or dissociative adsorption of oxygen (O-cus) may occur. In the absence of O-cus, ammonia desorbs completely thermally without any reaction. However, interaction between NH3-cus and O-cus starts already at 90 K by hydrogen abstraction and hydrogenation to OH-cus, leading eventually to N-cus and H 2O. The N-cus species recombine either with each other to N 2 or with neighboring O-cus leading to strongly held NO-cus which desorbs around 500 K. The latter reaction is favored by higher concentrations of O-cus. Under steady-state flow condition with constant NH3 partial pressure and varying O2 pressure, the rate for N2 formation takes off first, passes through a maximum and then decreases again, whereas that for NO production exhibits an S-shape and rises continuously. In this way at 530 K almost 100% selectivity for NO formation (with fairly high reaction probability for NH3) is reached.

Facile synthesis of Pd-Co-P ternary alloy network nanostructures and their enhanced electrocatalytic activity towards hydrazine oxidation

Zhang, Lu,Lu, Dingkun,Chen, Yu,Tang, Yawen,Lu, Tianhong

, p. 1252 - 1256 (2014)

Porous ternary Pd-Co-P alloy network nanostructures were synthesized by reducing K2PdCl4/K3Co(CN)6 cyanogel with a mixture of NaH2PO2 and NaBH4 at room temperature, which show superior electrocatalytic activity and stability towards hydrazine oxidation reaction.

A remarkable catalyst combination to widen the operating temperature window of the selective catalytic reduction of NO by NH3

Zhang, Runduo,Liu, Ning,Luo, Zhen,Yang, Wei,Liang, Xin,Xu, Ruinian,Chen, Biaohua,Duprez, Daniel,Royer, Sebastien

, p. 2263 - 2269 (2014)

On the basis of the idea of combining high selective catalytic reduction (SCR) activity, high N2 selectivity, and broad operating temperature window, we developed a combined catalyst process that was found to be a convenient way to design a highly efficient SCR process for NO with NH 3. The single catalysts of MnOx-CeO2/TiO 2 and V2O5-WO3/TiO2 as well as combined catalysts with different configurations were fully characterized by XRD, temperature-programmed reduction of H2, and temperature-programmed desorption of NO/O2. In addition, they were tested for the oxidation of NO or NH3 as well as the SCR of NO with NH3. The correlations between combining configurations and SCR activity results were also revealed. Furthermore, fundamental evidences were given for the rational design of the process and its efficiency maximization (assembly order and catalytic bed volume). An adequate configuration, with MnOx-CeO2/TiO2 and V2O 5-WO3/TiO2 active materials, ensures an excellent SCR performance (NO conversion >85%, N2 yield >70%, and decreased N2O production) over a wide operating temperature window (from 150 to 400°C).

Structural properties and photocatalytic activity of ceria nanoparticles on vermiculite matrix

Valá?ková, Marta,Kupková, Jana,Ko?í, Kamila,Ambro?ová, Nela,Klemm, Volker,Rafaja, David

, p. 7844 - 7848 (2016)

Clay mineral matrices and metal oxides are of current interest because of their high thermal stability, large surface area, and good catalytic and adsorption properties. Cerium oxide (ceria, CeO2) nanoparticles was obtained by interaction of ve

Selective catalytic reduction of NO by ammonia over Fe-ZSM-5 catalysts

Ma, Ai-Zeng,Gruenert

, p. 71 - 72 (1999)

In the selective catalytic reduction (SCR) of NO by ammonia, over-exchanged Fe-ZSM-5 prepared by sublimation of FeCl3 into H-ZSM-5, shows superior catalytic activity and stability in a wide temperature range; its activity is promoted by the presence of water in the feed while SO2 is a weak poison at low but a promoter at high temperatures; its remarkable durability towards H2O and SO2 makes this zeolite catalyst a potential choice in Denox applications for stationary sources and heavy Diesel engines with ammonia or urea reductants.

Anisotropy and Energy Disposal in the 193-nm N2O Photodissociation Measured by VUV Laser-Induced Fluorescence of O(1D)

Springsteen, L. L.,Satyapal, S.,Matsumi, Y.,Dobeck, L. M.,Houston, P. L.

, p. 7239 - 7241 (1993)

Laser induced fluorescence near 115 nm has been used to measure the Doppler profile of the O(1D) product of 193-nm N2O photolysis.The anisotropy of product recoil vectors is characterized by the paramter β = 0.50 +/- 0.05.The measured velocity distribution can be used to calculate a distribution of recoil energies that is in reasonable agreement with that reported recently by Felder, Haas, and Huber; an average of 27.3 kcal/mol is deposited into translation, leaving ca. 37 kcal/mol for the internal excitation of the N2 fragment.

Catalytic Oxidation of Ammonia over the SiO2-Pillared Oxycompounds Containing Titanium and Manganese with Layered Structure

Yahiro, Hidenori,Nakai, Toshihiro,Shiotani, Masaru,Yamanaka, Shoji

, p. 249 - 252 (1999)

A SiO2-pillared manganese titanate (SiO2-MTO) with layered structure, which has a surface area as large as more than 700 m2/g, effectively catalyzed the NH3 oxidation with high selectivity to N2. The H2 temperature-programmed reduction results suggested that the manganese ions in SiO2-MTO were in an oxidation state of +3 even in the absence of either Rb+ or C10H21NH3+ ions as a charge-balancing cation. The observed high selectivity to N2 is attributable to oxygen vacancies associated with Mn3+ ions in the layer.

Low-temperature hydrogen-selective catalytic reduction of NOx on Pt/sulfated-ZrO2 catalysts under excess oxygen conditions

Saito, Makoto,Itoh, Masahiro,Iwamoto, Jun,Machida, Ken-Ichi

, p. 1210 - 1211 (2008)

Platinum catalysts supported on sulfated zirconia powders highly promote the hydrogen-selective catalytic reduction (H2-SCR) of NOX at 100°C with formation of ammonia intermediate species derived from protons of the sulfonate groups

The selective catalytic reduction of NO2 by NH3 over HZSM-5

Stevenson, Scott A.,Vartuli, Jim C.

, p. 100 - 105 (2002)

We have studied the reduction of NO2 by NH3 over HZSM-5 and find that this reaction is several hundred times faster than the corresponding reduction of NO under similar conditions. In addition, the kinetics of the reduction of NOsub

Kinetics, Kinetic Deuterium Isotope Effects, and Mechanism of Nitrous Oxide Reaction with Hydrogen on Supported Precious-Metal Catalysts

Miyamoto, Akira,Baba, Shigeo,Mori, Mitsushi,Murakami, Yuichi

, p. 3117 - 3122 (1981)

The kinetics and kinetic deuterium isotope effects have been precisely measured for the reaction of nitrous oxide with hydrogen on Ru/Al2O3, Rh/Al2O3, Ir/Al2O3, and Pt/Al2O3 catalysts.The reaction apparently proceeds through the two following elementary s

Temperature-programmed desorption/surface reaction (TPD/TPSR) study of Fe-exchanged ZSM-5 for selective catalytic reduction of nitric oxide by ammonia

Long,Yang

, p. 20 - 28 (2001)

NO, NO2, and N2O from combustion of fossil fuels have been a major source of air pollution. The abatement of these NOx emissions is urgent due to their implication in photochemical smog, acid rain, ozone depletion, and greenhouse effects. TPD and temperature-programmed surface reaction (TPSR) were used to study Fe-exchanged ZSM-5 for SCR of NO with ammonia. TPD profiles revealed that NOx and NH3 adsorbed on Fe-ZSM-5. Physisorbed NOx and NH3 were not considerably affected by Fe content. Chemisorbed NOx increased with increasing Fe content, while chemisorbed NH3 decreased due to substitution of protons by Fe ions. TPSR results showed that NH3 adsorbed species were quite active in reacting with O2, NO, NO + O2, and NO2, following the reactivity rank order NO2 ~ NO + O2 > NO > O2. NOx adsorbed species were also reactive to NH3 at high temperatures. With NOx and NH3 coadsorbed on Fe-ZSM-5, TPSR with gaseous He, NO2, and NO exhibited two types of reactions for N2 formation. One reaction near 55°C originated from decomposition of ammonium nitrate that was not affected by Fe3+ content. The other reaction at 170°-245°C was due to an adsorbed complex, possibly [NH4/+]2NO2, reacting with NO2 or NO. A possible reaction path was proposed for NO reduction involving NO2 and [NH4/+]2NO2 as intermediates. Since the reactivity of [NH4/+]2NO2 to NO was higher than that to NO2, it was deduced that [NH4/+]2NO2 preferred to react with NO and not NO2, both of which were present in the SCR reaction. This could be the reason for N2 being the only product for SCR on Fe-ZSM-5.

Synthesis of Complex Boron-Nitrogen Heterocycles Comprising Borylated Triazenes and Tetrazenes under Mild Conditions

Bélanger-Chabot, Guillaume,Braunschweig, Holger,Dietz, Maximilian,Guo, Xueying,Krummenacher, Ivo,Lin, Zhenyang,Müller, Marcel,Prieschl, Dominic

, p. 1065 - 1076 (2020)

The reactions of organic azides with diaryl(dihalo)diboranes(4) were explored, resulting in the observation of a number of surprising reactivity patterns. The reaction of phenyl azide with 1,2-diaryl-1,2-dihalodiboranes(4) resulted in the formation of five-membered rings comprising diboryl-triazenes with retention of the boron-boron bond, while the reaction of the peculiar 1,1-di(9-anthryl)-2,2-difluorodiborane(4) with phenyl azide yielded a six-membered ring bearing a diboryl-triazene, whereby the B-B bond was ruptured by the insertion of an arylnitrene-like reactive intermediate. Both types of heterocycles feature unprecedented connectivity patterns and are very rare examples of boryl triazenes beyond the more common 1,2,3-triazolatoboranes. They are also the product of a unique type of aryl migration from a boron center to the phenyl azide ?-nitrogen center. Lastly, the substitution of 1,2-diaryl-1,2-dihalodiboranes(4) with azide groups, using trimethylsilyl azide as the transfer reagent, yielded boryl-tetrazaboroles and diboryldiazadiboretidines (as side-products), invoking the intermediacy of the first N-boryl-substituted iminoboranes, which are BN isosteres of monoborylated alkynes. The synthetic results are complemented with mechanistic proposals derived from quantum-chemical calculations.

Very active CeO2-zeolite catalysts for NOx reduction with NH3

Krishna,Seijger,Van den Bleek,Calis

, p. 2030 - 2031 (2002)

Selective catalytic reduction of NO with NH3 over high weight percentage CeO2-zeolites showed excellent NOx conversions at very high space velocities under simulated exhaust gas conditions in the presence of H2O

Fe-Ce-ZSM-5 a new catalyst of outstanding properties in the selective catalytic reduction of NO with NH3

Carja,Delahay,Signorile,Coq

, p. 1404 - 1405 (2004)

A Fe-Ce-ZSM-5 catalyst elaborated from a new synthesis route exhibits very high NO conversion (75-100%) in the selective catalytic reduction of NO by NH3 in a wide temperature window (523-823 K), even in the presence of H2O and SO2.

N2O Reductase Activity of a [Cu4S] Cluster in the 4CuI Redox State Modulated by Hydrogen Bond Donors and Proton Relays in the Secondary Coordination Sphere

Hsu, Chia-Wei,Rathnayaka, Suresh C.,Islam, Shahidul M.,MacMillan, Samantha N.,Mankad, Neal P.

, p. 627 - 631 (2020)

The model complex [Cu4(μ4-S)(dppa)4]2+ (1, dppa=μ2-(Ph2P)2NH) has N2O reductase activity in methanol solvent, mediating 2 H+/2 e? reduction of N2O to N2+H2O in the presence of an exogenous electron donor (CoCp2). A stoichiometric product with two deprotonated dppa ligands was characterized, indicating a key role of second-sphere N?H residues as proton donors during N2O reduction. The activity of 1 towards N2O was suppressed in solvents that are unable to provide hydrogen bonding to the second-sphere N?H groups. Structural and computational data indicate that second-sphere hydrogen bonding induces structural distortion of the [Cu4S] active site, accessing a strained geometry with enhanced reactivity due to localization of electron density along a dicopper edge site. The behavior of 1 mimics aspects of the CuZ catalytic site of nitrous oxide reductase: activity in the 4CuI:1S redox state, use of a second-sphere proton donor, and reactivity dependence on both primary and secondary sphere effects.

Oxygen photoevolution on a tantalum oxynitride photocatalyst under visible-light irradiation: How does water photooxidation proceed on a metal-oxynitride surface?

Nakamura, Ryuhei,Tanaka, Tomoaki,Nakato, Yoshihiro

, p. 8920 - 8927 (2005)

The mechanism of water photooxidation (oxygen photoevolution) on a TaON photocatalyst was studied on the basis of our previous studies on the mechanism of this reaction on TiO2 and N-doped TiO2. We have confirmed that photocatalytic O2 evolution occurs from an aqueous TaON suspension in the presence of Fe3+, as reported. In-situ MIR-IR experiments have indicated that the TaON surface is slightly oxidized under visible-light irradiation, indicating that the oxygen photoevolution on TaON actually occurs on a thin Ta-oxide overlayer. The in-situ MIR-IR experiments have also shown that a certain surface peroxo species, tentatively assigned to adsorbed HOOH, is formed as an intermediate of the O2 photoevolution reaction. Studies on the effect of addition of reductants to the electrolyte on the IPCE have shown that photogenerated holes at the TaON surface cannot oxidize reductants such as SCN-, Br-, methanol, ethanol, 2-propanol, and acetic acid, though they can oxidize H2O into O 2. Detailed considerations of these results have strongly suggested that the water photooxidation reaction on TaON proceeds by our recently proposed new mechanism, that is, the reaction is initiated by a nucleophilic attack of a water molecule (Lewis base) on a surface-trapped hole (Lewis acid). ? 2005 American Chemical Society.

Young, D. A.

, p. 499 - 508 (1964)

Nickel-doped Mn/TiO2 as an efficient catalyst for the low-temperature SCR of NO with NH3: Catalytic evaluation and characterizations

Thirupathi, Boningari,Smirniotis, Panagiotis G.

, p. 74 - 83 (2012)

The Mn/TiO2 and a series of Mn-Ni/TiO2 catalysts were prepared by adopting incipient wetness technique and investigated for the low-temperature SCR of NO with NH3 in the presence of excess oxygen. Our XPS results illustrated that the MnO2 is the dominant phase with respect to the Mn2O3 phase (Mn4+/Mn 3+ = 22.31, 96%), thus leading to a large number of Mn4+ species (Mn4+/Ti) over the titania support for the Mn-Ni(0.4)/TiO2 catalyst. It is remarkable to note that the SCR performance of all the nickel-doped Mn/TiO2 catalysts is accurately associated with the surface Mn4+ concentrations. The co-doping of nickel into the Mn/TiO2 with 0.4 Ni/Mn atomic ratio promotes the formation of surface MnO2 phase and inhibits the formation of surface Mn2O3 sites. Our TPR results revealed that the addition of nickel oxide to titania-supported manganese results in the stabilization of the former in the form of MnO2 rather than Mn2O 3. Our TPR data results are in agreement with XPS results that the absence of the high-temperature (736 K) peak indicates that the dominant phase in the Mn-Ni/TiO2 catalysts is MnO2. The low-temperature reduction peak is shifted to much lower temperatures in nickel-doped Mn/TiO 2 catalysts. This increase in reducibility and the extremely dominant MnO2 phase seem to be the reason for the high SCR activity of the Mn-Ni/TiO2 catalysts.

Mah, A. D.,Gellert, N. L.

, p. 3261 - 3263 (1956)

Effect of postsynthesis preparation procedure on the state of copper in CuBEA zeolites and its catalytic properties in SCR of NO with NH3

Baran, Rafal,Averseng, Frederic,Wierzbicki, Dominik,Chalupka, Karolina,Krafft, Jean-Marc,Grzybek, Teresa,Dzwigaj, Stanislaw

, p. 332 - 342 (2016)

Copper-containing BEA zeolites, Cu2.0SiBEA and Cu2.0HAlBEA, with 2?wt% of Cu were prepared by a two-step postsynthesis method and a conventional wet impregnation, respectively. These zeolites were characterized by XRD, DR UV–vis, EPR, FTIR and TPR physicochemical techniques. The incorporation of Cu into framework of SiBEA was evidenced by XRD. The state of copper in both zeolites was investigated by DR UV–vis and EPR. The acidity of Cu2.0SiBEA and Cu2.0HAlBEA was determined by FTIR of adsorbed CO and pyridine. The reducibility of the Cu species present in both zeolites was studied by TPR and their catalytic properties were investigated in selective catalytic reduction of NO with NH3. Both Cu2.0SiBEA and Cu2.0HAlBEA zeolite catalysts showed very high activity in this reaction with the NO conversion higher than 80% and N2 selectivity higher than 95% in the temperature range between 473 and 623?K. The higher NO conversion and N2 selectivity in SCR of NO with ammonia at the high temperature range for the Cu2.0HAlBEA than for Cu2.0SiBEA suggest that the strong Br?nsted and Lewis acidic sites related to the framework and extra-framework aluminum atoms play an important role in SCR of NO process.

Selective Catalytic Reduction over Cu/SSZ-13: Linking Homo- and Heterogeneous Catalysis

Gao, Feng,Mei, Donghai,Wang, Yilin,Szanyi, János,Peden, Charles H. F.

, p. 4935 - 4942 (2017)

Active centers in Cu/SSZ-13 selective catalytic reduction (SCR) catalysts have been recently identified as isolated Cu2+ and [CuII(OH)]+ ions. A redox reaction mechanism has also been established, where Cu ions cycle between CuI and CuII oxidation states during SCR reaction. While the mechanism for the reduction half-cycle (CuII → CuI) is reasonably well-understood, that for the oxidation half-cycle (CuI → CuII) remains an unsettled debate. Herein we report detailed reaction kinetics on low-temperature standard NH3-SCR, supplemented by DFT calculations, as strong evidence that the low-temperature oxidation half-cycle occurs with the participation of two isolated CuI ions via formation of a transient [CuI(NH3)2]+-O2-[CuI(NH3)2]+ intermediate. The feasibility of this reaction mechanism is confirmed from DFT calculations, and the simulated energy barrier and rate constants are consistent with experimental findings. Significantly, the low-temperature standard SCR mechanism proposed here provides full consistency with low-temperature SCR kinetics.

Obuchi, Akira,Naito, Shuichi,Onishi, Takaharu,Tamaru, Kenzi

, p. 29 - 40 (1983)

Selective reduction of NO with propene over Ga2O3-Al2O3: Effect of sol-gel method on the catalytic performance

Haneda, Masaaki,Kintaichi, Yoshiaki,Shimada, Hiromichi,Hamada, Hideaki

, p. 137 - 148 (2000)

SCR of NOx to N2 by hydrocarbons has received extensive attention because of its potential for practical applications to diesel and lean-burn engine exhausts. The advantage of this process is the ability to reduce NOx in t

Meyer, L.

, p. 791 (1932)

Collier, F. N.,Sisler, H. H.,Calvert, J. G.,Hurley, F. R.

, p. 6177 - 6187 (1959)

Ruthenium-catalysed oxidative conversion of ammonia into dinitrogen

Nakajima, Kazunari,Toda, Hiroki,Sakata, Ken,Nishibayashi, Yoshiaki

, p. 702 - 709 (2019)

Conversion of ammonia into dinitrogen has attracted broad scientific interest in relation to molecular models of the heterogeneous nitrogen fixation process, environmental treatment for denitrification and utilization of ammonia as an energy carrier. Here we show that some ruthenium complexes bearing 2,2′-bipyridyl-6,6′-dicarboxylate ligands work as catalysts for the ammonia oxidation reaction. Production of dinitrogen is observed when ammonium salts are treated with a triarylaminium radical as an oxidant and 2,4,6-collidine as a base in the presence of the ruthenium catalysts. Based on the characterization of some intermediates, we propose a reaction pathway via a bimetallic nitride–nitride coupling process. The proposed reaction pathway is supported by density functional theory calculations. Further investigation of the ammonia oxidation reaction under the electrochemical conditions revealed that the ruthenium complex works as a new anode catalyst for ammonia oxidation.

Ammonia blocking of the "Fast SCR" reactivity over a commercial Fe-zeolite catalyst for Diesel exhaust aftertreatment

Grossale, Antonio,Nova, Isabella,Tronconi, Enrico

, p. 141 - 147 (2009)

The ammonia blocking effect on the Fast SCR catalytic mechanism at low temperature has been studied by means of dedicated transient reactivity runs performed over a state-of-the-art commercial Fe-zeolite catalyst. We show that the reduction of surface nitrates by NO is the key step in the mechanism, and is active already at 50 °C. However, in the presence of ammonia the reaction between NO and nitrates is stopped, and proceeds only on raising the temperature up to 140-160 °C, which thus represents an intrinsic lower bound to the Fast SCR activity. Evidence is provided that such a blocking effect is associated with a strong interaction between ammonia and surface nitrates, which prevents nitrates from reacting with NO: only upon increasing the temperature or decreasing the NH3 concentration nitrates are released due to dissociation of the ammonia-nitrate complex. The present data thus provide evidence that the blocking effect of NH3 on the Fast SCR activity at low temperature occurs not because of the ammonia competitive chemisorption on the catalytic sites, but because ammonia captures a key intermediate in an unreactive form.

In situ IR spectroscopic and XPS study of surface complexes and their transformations during ammonia oxidation to nitrous oxide over an Mn-Bi-O/α-Al2O3 catalyst

Slavinskaya,Chesalov,Boronin,Polukhina,Noskov

, p. 555 - 564 (2005)

Surface complexes resulting from the interaction between ammonia and a manganese-bismuth oxide catalyst were studied by IR spectroscopy and XPS. At the first stage, ammonia reacts with the catalyst to form the surface complexes [NH] and [NH2] via abstraction of hydrogen atoms even at room temperature. Bringing the catalyst into contact with flowing air at room temperature or with helium under heating results in further hydrogen abstraction and simultaneous formation of [N] from [NH2] and [NH]. The nitrogen atoms are localized on both reduced (Mn2+) and oxidized (Mn δ+, 2 δ+-N) active site. The nitrogen atoms localized on oxidized sites play the key role in N2O formation. Nitrous oxide is readily formed through the interaction between two Mnδ+-N species. N2 molecules result from the recombination of nitrogen atoms localized on reduced (Mn2+-N) sites.

VIBRATIONAL-STATE DISTRIBUTION OF N2(B3Πg) PRODUCED FROM THE Ar(3P2,0)+N2O REACTION

Wu, Konrad T.

, p. 2657 - 2662 (1988)

The N2(B3Πg) product-state distribution for ν'=0-12 has been analyzed from the fluorescence observed in an Ar(3P2,0)+N2O afterglow.This vibronic distribution shows a non-Boltzmann property, inverted at ν'=4.N2(B) was found to be formed via predissociation of the Rydberg state converging into the ground state of N2O+.The golden-rule model and the half-collision model in the collinear configuration are applied to this reaction system to explain the dynamical features.The results show that both Franck-Condon-like effects and final-state interactions are important in the predissociative excitation of N2O.Potential curves are proposed for the effective harmonic oscillator and the repulsive states to reproduce the experimental vibronic-state distribution of N2(B) and to interpret the predissociation mechanism.

Electron beam initiated discharges in HN3 gas mixtures

Schlie, L. A.,Wright, M. W.

, p. 394 - 400 (1990)

The behaviour of electron beam initiated discharges in HN3 and inert gas mixtures for different E/N values are presented.These results are the first reported investigations of this highly energetic azide gas under plasma conditions.Using a 3 ns. 600 KeV ionizing electron beam, the temporal decay of the discharge current shows HN3 is electronegative.HN3 attachment rate constants in Ar are 5.0-10.0x10-11 cm3 s-1 for E/N values in the range 1-4 Td (10-17 V cm2).With the other inert gases (He, Ne, Kr, and Xe), HN3 attachment rate constants are 0.5-4.5x10-10cm3 s-1 for the E/N range of 0.5-7.0 Td.Plasma excitation of Ar and HN3 gas mixtures produce intense N2(C -> B, υ' = 0 -> υ'' = 0) electronic transition radiation at 3371 Angstroem.

Kinetics of selective catalytic reduction of nitric oxide by ammonia over vanadia/titania

Dumesic,Topsoe,Topsoe,Chen,Slabiak

, p. 409 - 417 (1996)

A kinetic model based on a previously proposed reaction scheme was used to describe reaction kinetics measurements for the selective catalytic reduction of nitric oxide by ammonia over a 6 wt% vanadia/titania catalyst in the presence of oxygen (2 mol%) at nitric oxide and ammonia concentrations from 100 to 500 ppm and at temperatures of 523 and 573 K. This reaction scheme involves adsorption of ammonia on Bronsted acid sites (V5+-OH), followed by activation of ammonia via reaction with redox sites (V=O). This activated form of ammonia reacts with gaseous or weakly adsorbed NO, producing N2 and H2O, and leading to partial reduction of the catalyst. The V4+-OH species formed by the selective catalytic reduction (SCR) reaction combine to form water, and the catalytic cycle is completed by reaction of the reduced sites with O2. Water adsorbs competitively with ammonia on acid sites. This reaction scheme can be used to describe the kinetics of the SCR reaction under laboratory as well as under industrially relevant reaction conditions.

Measurement of heterogeneously catalyzed gas reactions by DSC

Hakvoort

, p. 445 - 452 (1996)

Gas reactions, catalyzed by solid catalysts, can be measured by DSC. In the experimental setup an open sample pan with catalyst (powder or pellet) is placed on the sample side of the DSC sensor. The reactive gas mixture flows through the cell and reacts on the catalyst surface. The heat effect, caused by this reaction, results into a DSC signal. The calibration procedure is described for quantitative evaluation of the DSC measurements. For illustration four different reaction systems are discussed.

Harrison, D. E.,Weissberger, E.,Taube, H.

, p. 320 - 322 (1968)

Dual Nanoislands on Ni/C Hybrid Nanosheet Activate Superior Hydrazine Oxidation-Assisted High-Efficiency H2 Production

Li, Yapeng,Li, Ziyun,Liu, Yi,Qian, Qizhu,Xiao, Chong,Xie, Yi,Zhang, Genqiang,Zhang, Jihua,Zhu, Yin

supporting information, (2021/12/09)

Clean hydrogen evolution through electrochemical water splitting underpins various innovative approaches to the pursuit of sustainable energy conversion technologies, but it is blocked by the sluggish anodic oxygen evolution reaction (OER). The hydrazine oxidation reaction (HzOR) has been considered as one of the most promising substitute for OER to improve the efficiency of hydrogen evolution reaction (HER). Herein, we construct novel dual nanoislands on Ni/C hybrid nanosheet array: one kind of island represents the part of bare Ni particle surface, while the other stands for the part of core–shell Ni@C structure (denoted as Ni-C HNSA), in which exposed Ni atoms and Ni-decorated carbon shell perform as active sites for HzOR and HER respectively. As a result, when the current density reaches 10 mA cm?2, the working potentials are merely ?37 mV for HER and -20 mV for HzOR. A two-electrode electrolyzer exhibits superb activity that only requires an ultrasmall cell voltage of 0.14 V to achieve 50 mA cm?2.

Cu, Fe and Mn oxides intercalated SiO2 pillared magadiite and ilerite catalysts for NO decomposition

Katabathini, Narasimharao,El Maksod, Islam Hamdy Abd,Mokhtar, Mohamed

, (2021/03/22)

Synthesized magadiite and ilerite samples were pillared with SiO2 and then intercalated with Cu, Fe and Mn oxides to utilize for direct NO decomposition between 400 and 600 °C. Cu-SiO2-pil-ile and Cu-SiO2-pil-mag catalysts exhibited high NO decomposition activity compared to Fe and Mn oxide intercalated catalysts. Remarkably, Cu-SiO2-pil-ile offered 90 % NO conversion and 83 % N2 selectivity at 600 °C. Elemental analysis, XRD, FESEM, DR UV-vis, Raman spectroscopy, N2-adsorption, H2-TPR, O2-TPD and XPS were utilized to study physicochemical characteristics of the materials. The results from XRD and N2 adsorption demonstrated that the samples possessed different pore structures from SiO2-pillared silicates, due to different nature of metal oxides. The Cu-SiO2-pil-ile and Cu-SiO2-pil-mag samples possess a smaller number of Lewis and Br?nsted acid sites compared with Fe and Mn oxide intercalated samples. Presence of Cu2+/Cu+ and Fe3+/Fe2+, and synergism between redox centers are major reason for superior performance in NO decomposition. Therefore, the impact of redox properties and NO adsorption on the surface of the catalyst are significant.

Synthesis of Zeolitic Mo-Doped Vanadotungstates and Their Catalytic Activity for Low-Temperature NH3-SCR

Tao, Meilin,Ishikawa, Satoshi,Murayama, Toru,Inomata, Yusuke,Kamiyama, Akiho,Ueda, Wataru

supporting information, p. 5081 - 5086 (2021/04/09)

Mo was successfully introduced into a vanadotungstate (VT-1), which is a crystalline microporous zeolitic transition-metal oxide based on cubane clusters [W4O16]8- and VO2+ linkers (MoxW4-x. x: number of Mo in VT-1 unit cell determined by inductively coupled plasma-atomic emission spectroscopy (ICP-AES)). It was confirmed that W in the cubane units was substituted by Mo. The resulting materials showed higher microporosity compared with VT-1. The surface area and the micropore volume increased to 296 m2·g-1 and 0.097 cm3·g-1, respectively, for Mo0.6W3.4 compared with the those values for VT-1 (249 m2·g-1 and 0.078 cm3·g-1, respectively). The introduction of Mo changed the acid properties including the acid amount (VT-1: 1.06 mmol g-1, Mo0.6W3.4: 2.18 mmol·g-1) and its strength because of the changes of the chemical bonding in the framework structure. MoxW4-x showed substantial catalytic activity for the selective catalytic reduction of NO with NH3 (NH3-selective catalytic reduction (SCR)) at a temperature as low as 150 °C.

Selective catalytic reduction of NOx by H2 over a novel Pd/FeTi catalyst

Zhang, Yiyang,Zeng, Hui,Jia, Bin,Liu, Zhiming

, p. 213 - 219 (2020/05/18)

Selective catalytic reduction (SCR) of NOx by H2 over Pd/Ti, Pd/Fe and Pd/FeTi catalysts was systematically investigated. Compared with Pd/Ti and Pd/Fe catalysts, Pd/FeTi catalyst exhibited higher H2-SCR activity and the optimal ratio of Fe/Ti is 1. Over Pd/FeTi catalysts FeTi solid solution is formed, and Pd is highly dispersed on the support. XPS analysis showed that there is strong interaction among Pd, Fe and Ti species. In-situ DRIFTS results revealed that more and new adsorbed NOx species, which are reactive to reacting with H2, formed over Pd/FeTi. All these factors account for the improved H2-SCR activity of Pd/FeTi catalyst.

Atomically Dispersed Copper Sites in a Metal-Organic Framework for Reduction of Nitrogen Dioxide

Chansai, Sarayute,Cheng, Yongqiang,Da Silva, Ivan,Haigh, Sarah J.,Han, Xue,Hardacre, Christopher,Lee, Daniel,Li, Weiyao,Ma, Yujie,Manuel, Pascal,McInnes, Eric J. L.,Nikiel, Marek,Ramirez-Cuesta, Anibal J.,Rudi?, Svemir,Schr?der, Martin,Sheveleva, Alena M.,Tuna, Floriana,Wang, Zi,Xu, Shaojun,Yang, Sihai,Zou, Yichao

supporting information, p. 10977 - 10985 (2021/08/03)

Metal-organic framework (MOF) materials provide an excellent platform to fabricate single-atom catalysts due to their structural diversity, intrinsic porosity, and designable functionality. However, the unambiguous identification of atomically dispersed metal sites and the elucidation of their role in catalysis are challenging due to limited methods of characterization and lack of direct structural information. Here, we report a comprehensive investigation of the structure and the role of atomically dispersed copper sites in UiO-66 for the catalytic reduction of NO2 at ambient temperature. The atomic dispersion of copper sites on UiO-66 is confirmed by high-angle annular dark-field scanning transmission electron microscopy, electron paramagnetic resonance spectroscopy, and inelastic neutron scattering, and their location is identified by neutron powder diffraction and solid-state nuclear magnetic resonance spectroscopy. The Cu/UiO-66 catalyst exhibits superior catalytic performance for the reduction of NO2 at 25 °C without the use of reductants. A selectivity of 88% for the formation of N2 at a 97% conversion of NO2 with a lifetime of >50 h and an unprecedented turnover frequency of 6.1 h-1 is achieved under nonthermal plasma activation. In situ and operando infrared, solid-state NMR, and EPR spectroscopy reveal the critical role of copper sites in the adsorption and activation of NO2 molecules, with the formation of {Cu(I)···NO} and {Cu···NO2} adducts promoting the conversion of NO2 to N2. This study will inspire the further design and study of new efficient single-atom catalysts for NO2 abatement via detailed unravelling of their role in catalysis.

Process route upstream and downstream products

Process route

silver(I) nitrite
7783-99-5

silver(I) nitrite

silver hyponitrite

silver hyponitrite

nitrogen
7727-37-9

nitrogen

silver nitrate

silver nitrate

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In neat (no solvent); thermic decomposition, further products;;
silver hyponitrite

silver hyponitrite

silver(l) oxide
20667-12-3

silver(l) oxide

nitrogen
7727-37-9

nitrogen

silver nitrate

silver nitrate

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In neat (no solvent); thermic decomposition, further products;;
difluoroether
7783-41-7

difluoroether

cesium azide
22750-57-8

cesium azide

nitrogen
7727-37-9

nitrogen

cesium fluoride
13400-13-0

cesium fluoride

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In neat (no solvent); stainless steel autoclave; condensing OF2 onto 3 equiv. CsN3 at -196°C, warming to room temp., heating to 250°C for 15 min; cooling to -196°C, pumping off products; identification by gas-discharge colors, IR spectroscopy and F-sensitive potentiometry;
trans-Mo(N<sub>2</sub>)2(PMePh<sub>2</sub>)2(PPh<sub>2</sub>CH<sub>2</sub>CH<sub>2</sub>SMe)
89958-79-2

trans-Mo(N2)2(PMePh2)2(PPh2CH2CH2SMe)

nitrogen
7727-37-9

nitrogen

ammonia
7664-41-7

ammonia

hydrogen
1333-74-0

hydrogen

Conditions
Conditions Yield
With H2SO4; KOH; In methanol; after reaction with acid (23°C, 18 h), solution is evapd., treated with 40% KOH and tested for NH3 according Chatt, J.; Pearman, A. J.; Richards, R. L., Chem. Soc., Dalton Trans. 1977, 1852;
potassium nitrite
7758-09-0

potassium nitrite

hydroxyammonium sulfate

hydroxyammonium sulfate

nitrogen
7727-37-9

nitrogen

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In not given; in acidic soln. from equimolar amounts of components; mole ratio N2O : N2 depends on the mole ratio of nitrite : hydrazonium salt;;
80%
20%
In not given; in acidic soln.; mole ratio N2O : N2 = 2:1 at mole ratio of nitrite : hydrazonium salt = 2:1;;
sodium azide

sodium azide

nitrogen
7727-37-9

nitrogen

ammonia
7664-41-7

ammonia

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In water; other Radiation; irradiation with X-ray in vac. at pH=8; Kinetics;
In water; other Radiation; irradiation with X-ray in vac. at pH=8; Kinetics;
sodium azide

sodium azide

water
7732-18-5

water

nitrogen
7727-37-9

nitrogen

ammonia
7664-41-7

ammonia

Nitrate
14797-55-8

Nitrate

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
With Pt/TiO2 (catalyst); In water; Irradiation (UV/VIS); Pt/TiO2 and 0.1 M NaN3 aq. soln. vigorously stirred and irradiated with500 W high pressure Hg lamp at 43°C;
sodium azide

sodium azide

nitrosylchloride
2696-92-6

nitrosylchloride

nitrogen
7727-37-9

nitrogen

sodium chloride
7647-14-5

sodium chloride

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
In diethyl ether; below 0°C;;
In diethyl ether; satd. soln. of NOCl, suspn. of NaN3 in dry ether, 0°C, products formed in equiv. amount;
In diethyl ether; satd. soln. of NOCl, suspn. of NaN3 in dry ether, 0°C, products formed in equiv. amount;
In diethyl ether; below 0°C;;
carbon monoxide
201230-82-2

carbon monoxide

water
7732-18-5

water

nitrogen(II) oxide
10102-43-9

nitrogen(II) oxide

carbon dioxide
124-38-9,18923-20-1

carbon dioxide

nitrogen
7727-37-9

nitrogen

dinitrogen monoxide
10024-97-2

dinitrogen monoxide

Conditions
Conditions Yield
With catalyst:Ir/WO3-SiO2; In neat (no solvent); 500 ppm NO, 3000 ppm CO, 5 % O2, 6 % H2O, 1 ppm SO2, He balance, catalyst: Ir/WO3-SiO2, heating from 140 °C to 600 °C; detected by gas chromy.; Kinetics;
With catalyst:Ba-Ir/WO3-SiO2; In neat (no solvent); 500 ppm NO, 3000 ppm CO, 5 % O2, 6 % H2O, 1 ppm SO2, He balance, catalyst: Ba-Ir/WO3-SiO2, heating from 140 °C to 600 °C; detected by gas chromy.; Kinetics;

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  • Country:China (Mainland)
  • Changsha Easchem Co.,Limited
  • Business Type:Lab/Research institutions
  • Contact Tel:+86-731-89722861 89722891
  • Emails:marketing@easchem.com
  • Main Products:1
  • Country:China (Mainland)
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