29817-79-6Relevant academic research and scientific papers
Synthesis and characterization of (Z)-[N3NFO]+ and (E)-[N3NFO]+
Wilson, William W.,Haiges, Ralf,Boatz, Jerry A.,Christe, Karl O.
, p. 3023 - 3027 (2007)
(Figure Presented) A new stable polynitrogen ion: The second known example of a stable nitrogen fluoride oxide ion, [N3NFO]+, was prepared as its [SbF6]- salt and characterized by multinuclear NMR and vibrational spectroscopy and electronic-structure calculations. The cation is planar and exists as two stereoisomers (see picture; N blue, O red, F dark blue).
Mechanism of the reaction NO + H2 on the Pt(100)-hex surface under conditions of the spatially nonuniform distribution of reacting species
Smirnov,Zemlyanov,Vovk
, p. 853 - 863 (2007)
The interaction of hydrogen with NOads/1 × 1 islands produced by NO adsorption on the reconstructed surface Pt(100)-hex was studied by high-resolution electron energy loss spectroscopy (HREELS) and the temperature-programmed reaction (TPR) method. The islands are areas of the unreconstructed surface Pt(100)-1 × 1 saturated with NOads molecules. The hexagonal phase around these islands adsorbs much more hydrogen near room temperature than does the clean Pt(100)-hex surface. It is assumed that hydrogen is adsorbed on the hexagonal surface areas that are adjacent to, and are modified by, the NOads/1 × 1 islands. The reaction of adsorbed hydrogen atoms with NOads takes place upon heating and has the character of so-called surface explosion. The TPR peaks of the products of this reaction-nitrogen and water-occur at T des ～ 365-370 K, their full width at half-maximum being ～5-10 K. In the case of the NO ads/1 × 1 islands preactivated by heating in vacuo above the NO desorption onset temperature (375-425 K), after the admission of hydrogen at 300 K, the reaction proceeds in an autocatalytic regime and the product formation rate increases monotonically at its initial stage. In the case of activation at 375 K, during the initial, slow stage of the reaction (induction period), hydrogen reacts with nitric oxide molecules bound to structure defects (NOdef). After activation at 425 K, the induction period is characterized by the formation and consumption of imido species (NH ads). It is assumed that NHads formation involves N ads atoms that have resulted from NOads dissociation on defects upon thermal activation. The induction period is followed by a rapid stage of the reaction, during which hydrogen reacts with NO 1 × 1 molecules adsorbed on 1 × 1 areas, irrespective of the activation temperature. After the completion of the reaction, the areas of the unreconstructed phase 1 × 1 are saturated with adsorbed hydrogen. The formation of Hads is accompanied by the formation of a small amount of amino species (NH2ads).
Diversion of Catalytic C-N Bond Formation to Catalytic Oxidation of NH3 through Modification of the Hydrogen Atom Abstractor
Bullock, R. Morris,Dunn, Peter L.,Johnson, Samantha I.,Kaminsky, Werner
supporting information, p. 3361 - 3365 (2020/03/06)
We report that (TMP)Ru(NH3)2 (TMP = tetramesitylporphryin) is a molecular catalyst for oxidation of ammonia to dinitrogen. An aryloxy radical, tri-tert-butylphenoxyl (ArO·), abstracts H atoms from a bound ammonia ligand of (TMP)Ru(NH3)2, leading to the discovery of a new catalytic C-N coupling to the para position of ArO· to form 4-amino-2,4,6-tri-tert-butylcyclohexa-2,5-dien-1-one. Modification of the aryloxy radical to 2,6-di-tert-butyl-4-tritylphenoxyl radical, which contains a trityl group at the para position, prevents C-N coupling and diverts the reaction to catalytic oxidation of NH3 to give N2. We achieved 125 ± 5 turnovers at 22 °C for oxidation of NH3, the highest turnover number (TON) reported to date for a molecular catalyst.
MXene-Derived Nanocomposites as Earth-Abundant Efficient Electrocatalyst for Nitrogen Reduction Reaction under Ambient Conditions
Zhao, Guoliang,Wang, Xin,Xu, Chen
supporting information, p. 16672 - 16678 (2020/11/13)
NH3, as one of the most massively used chemical products in the world, not only serves as the main nitrogen source of chemical fertilizers but also is considered as a promising renewable energy source. Most ammonia in industry is produced by the Haber-Bosch process under extremely high temperature and pressure conditions, which is intensively energy consuming and environmentally unfriendly. Electrocatalytic nitrogen reduction reaction (NRR) has been regarded as a promising way to produce NH3 under ambient conditions in recent years, but the research for efficient earth-abundant electrocatalysts is still highly limited. In this work, different TiO2 phases (anatase and rutile)/carbon nanocomposites with a sandwich architecture are produced by annealing MXene at different temperatures, which shows excellent electrocatalytic NRR performance. In 0.1 M Na2SO4, anatase TiO2/C composites show better NRR performance than the rutile ones, which achieve a large NH3 yield of 14.0 μg h-1 cm-2, a high Faradaic efficiency of 13.3% at-0.2 V vs a reversible hydrogen electrode, and a high electrochemical stability. The sandwich architecture of anatase TiO2 nanoparticles well-dispersed on the surface of carbon layers could increase the conductivity of TiO2 and the exposure of active sites, which could explain the improved NRR activity of anatase TiO2/C composites compared with previous work. Density functional theory calculations suggest that the energy barrier of most steps for the surface of anatase TiO2 is relatively lower than that of rutile TiO2, which could explain the better electrocatalytic NRR performance for anatase TiO2/C composites compared with the rutile ones.
Promoting effect of CeO2 on the catalytic activity of Ba-Y2O3for direct decomposition of NO
Doi, Yasuyuki,Haneda, Masaaki,Ozawa, Masakuni
, p. 117 - 123 (2015/01/30)
The effect of CeO2 additive on the catalytic performance of Ba-Y2O3 prepared by coprecipitaion for the direct decomposition of NO was investigated. Although Ba-Y2O3 effectively catalyzed NO decomposition, its activity was clearly increased by addition of CeO2. The optimum CeO2 content was 10 mol%. CO2-TPD measurement revealed that the addition of CeO2 into Ba-Y2O3 caused an increase in the CO2 desorption peak in the temperature range of 473 and 723K derived from highly dispersed Ba species. The predominant role of CeO2 additive was suspected to effectively create the highly dispersed Ba species as catalytically active sites. Kinetic studies of NO decomposition on Ba-CeO2(10)-Y2O3 suggested that coexisting O2 suppresses the NO decomposition reaction by competitive adsorption. Isotopic transient kinetic analysis suggested a reaction pathway in which the surface NOx adspecies act as reaction intermediates for the formation of N2 in NO decomposition over Ba-CeO2-Y2O3. We concluded that CeO2 additive does not directly participate in the NO decomposition reaction as catalytically active species.
A multi-iron system capable of rapid N2 formation and N 2 cleavage
MacLeod, K. Cory,Vinyard, David J.,Holland, Patrick L.
, p. 10226 - 10229 (2014/08/05)
The six-electron oxidation of two nitrides to N2 is a key step of ammonia synthesis and decomposition reactions on surfaces. In molecular complexes, nitride coupling has been observed with terminal nitrides, but not with bridging nitride complexes that more closely resemble catalytically important surface species. Further, nitride coupling has not been reported in systems where the nitrides are derived from N2. Here, we show that a molecular diiron(II) diiron(III) bis(nitride) complex reacts with Lewis bases, leading to the rapid six-electron oxidation of two bridging nitrides to form N2. Surprisingly, these mild reagents generate high yields of iron(I) products from the iron(II/III) starting material. This is the first molecular system that both breaks and forms the triple bond of N2 at room temperature. These results highlight the ability of multi-iron species to decrease the energy barriers associated with the activation of strong bonds.
Regeneration mechanism of a Lean NOx Trap (LNT) catalyst in the presence of NO investigated using isotope labelling techniques
Pereda-Ayo, Benat,Gonzalez-Velasco, Juan R.,Burch, Robbie,Hardacre, Christopher,Chansai, Sarayute
, p. 177 - 186 (2012/02/06)
The presence of NO during the regeneration period of a Pt-Ba/Al 2O3 Lean NOx Trap (LNT) catalyst modifies significantly the evolution of products formed from the reduction of stored nitrates, particularly nitrogen and ammonia. The use of isotope labelling techniques, feeding 14NO during the storage period and 15NO during regeneration allows us to propose three different routes for nitrogen formation based on the different masses detected during regeneration, i.e. 14N2 (m/e = 28), 14N 15N (m/e = 29) and 15N2 (m/e = 30). It is proposed that the formation of nitrogen via Route 1 involves the reaction between hydrogen and 14NOx released from the storage component to form 14NH3 mainly. Then, ammonia further reacts with 14NOx located downstream to form 14N2. In Route 2, it is postulated that the incoming 15NO reacts with hydrogen to form 15NH3 in the reactor zone where the trap has been already regenerated. This isotopically labelled ammonia travels through the catalyst bed until it reaches the regeneration front where it participates in the reduction of stored nitrates (14NOx) to form 14N15N. The formation of 15N2 via Route 3 is believed to occur by the reaction between incoming 15NO and H2. The modification of the hydrogen concentration fed during regeneration affects the relative importance of H2 or 15NH3 as reductants and thus the production of 14N2 via Route 1 and 14N15N via Route 2.
The reduction of 15N14NO by CO and by H2 over Rh/SiO2: A test of a mechanistic proposal
Cant, Noel W.,Chambers, Dean C.,Liu, Irene O.Y.
, p. 162 - 166 (2011/05/13)
A literature proposal that the reduction of nitrous oxide by carbon monoxide over rhodium catalysts proceeds by cleavage of the NN bond has been tested through the use of 15N14NO as the reactant. The results disprove the suggestion in that 14N15N is the dominant product at temperatures from 336 °C to 356 °C with nitrous oxide conversions from 26% to >99%. Little, if any, 14N 2 and 15N2 is formed, in contrast with the 25% of each expected for the model. Results for the corresponding reaction of 15N14NO with H2 are even more clear-cut in demonstrating the absence of NN bond cleavage. The activity of the Rh/SiO 2 used here for the N2O/CO system fell within the rather wide of values reported in the literature for other Rh catalysts. However, activity for the reduction of N2O by H2 was approximately five times higher than the only previous result in the literature, that for a Rh/Al2O3 catalyst.
The reaction mechanism of the high temperature ammonia oxidation to nitric oxide over LaCoO3
Biausque, Gregory,Schuurman, Yves
, p. 306 - 313 (2011/02/27)
Perovskites are promising catalysts for oxidation reactions. Good NO selectivity is reported for the oxidation of ammonia into nitric oxide over LaCoO3. More interestingly over this catalyst very little N 2O is produced, which makes it a potential candidate for industrial ammonia oxidation. In order to further develop perovskite catalysts, an understanding of the reaction mechanism is necessary. Steady-state, TAP and oxygen exchange experiments over LaCoO3 have been carried out. A reaction mechanism that describes the product distribution (NO, N2O and N2) as a function of the oxidation degree of the catalyst has been proposed. The reaction proceeds by a Mars and Van Krevelen mechanism. NO and N2O are formed through parallel routes from ammonia via surface nitroxyl (HNO) species. Formation of nitrogen occurs through at least three routes. Decomposition of both reaction products NO and N2O leads to N2, the latter decomposition being the fastest. The third route to N2 consists of the reaction of adsorbed ammonia with short-lived oxygen surface species, such as peroxide or superoxide species.
Synchrotron XPS and desorption study of the NO chemistry on a stepped Pt surface
Weststrate,Bakker,Rienks,Vinod,Lizzit,Petaccia,Baraldi,Nieuwenhuys
, p. 1991 - 2001 (2008/10/09)
The interaction of NO with Pt(4 1 0) was studied using high-energy resolution fast XPS and temperature programmed desorption/reaction mass spectroscopy. LEED studies show that the surface in the clean state restructures, which results in the formation of some larger {1 0 0} terraces. STM measurements show, that most terraces are small, ～1 nm. Two different binding energy (BE) components were observed in the N 1s region of the core level spectra, both assigned to molecular forms of NO. NO dissociation starts between 350 and 400 K. This is a significantly higher temperature than previous literature reports suggested. This difference is thought to be caused by the restructuring of the surface used in our experiments. The reaction of NO with H2, NH3 and CO was also studied. The onset of these NO reduction reactions is determined by the NOad dissociation temperature (between 350 and 400 K) and NOad dissociation is the rate limiting step for all the reactions that were studied. Reaction with H2 yields NH3 below 600 K, but the selectivity shifts towards N2 at higher temperatures. We did not find any indication that reaction between NOad and NH3 ad proceeds via a special NO-NH3 intermediate. A new surface species was detected during the reaction between NO and CO, both in the N 1s and the C 1s spectrum. It is tentatively assigned to either CN or CNO. The reactivity of NO on Pt(4 1 0) is compared with the reactivity that was observed for Pt(1 0 0) and other noble metal surfaces, such as Pd and Rh.
