Photocatalytic Deoxygenation of N–O Bonds with Rhenium Complexes: From the Reduction of Nitrous Oxide to Pyridine N-Oxides

The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. The large spectrum of reduction potentials covered by nitrogen oxides makes it however difficult to find general systems capable of efficiently reducing various N-oxides. Here photocatalysis unlocks high energy species able to both circumvent the inherent low reactivity of the greenhouse gas and oxidant N2O (E°(N2O/N2) = +1.77 V vs. SHE), and reduce pyridine N-oxides (E1/2(pyridine N-oxide/pyridine) = –1.04 V vs. SHE). The rhenium complex [Re(4,4’-tBu-bpy)(CO)3Cl] proved to be efficient to perform both reactions under ambient conditions, enabling the deoxygenation of N2O as well as synthetically relevant and functionalized pyridine N-oxides.

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Photocatalytic Deoxygenation of N–O bonds with Rhenium Complexes: from the Reduction of Nitrous Oxide to Pyridine N-Oxides

Chemical Science ◽

10.1039/d1sc01974k ◽

2021 ◽

Author(s):

Marianne Kjellberg ◽

Alexia Ohleier ◽

Pierre Thuéry ◽

Emmanuel Nicolas ◽

Lucile Anthore-Dalion ◽

...

Keyword(s):

Nitrous Oxide ◽

Nitrogen Oxides ◽

Oxidation States ◽

Rhenium Complexes ◽

Reduction Potentials

The accumulation of nitrogen oxides in the environment calls for new pathways to interconvert the various oxidation states of nitrogen, and especially their reduction. The large spectrum of reduction potentials...

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Differential kinetics of nitrogen oxides reduction leads to elevated nitrous oxide production by a nitrite fed granular denitrifying EBPR bioreactor

Environmental Science Water Research & Technology ◽

10.1039/c9ew00881k ◽

2020 ◽

Vol 6 (4) ◽

pp. 1028-1043 ◽

Cited By ~ 1

Author(s):

Han Gao ◽

Xiaotian Zhao ◽

Lei Zhou ◽

Fabrizio Sabba ◽

George F. Wells

Keyword(s):

Nitrous Oxide ◽

Nitrogen Oxides ◽

Greenhouse Gas ◽

P Uptake ◽

Oxide Production ◽

Slow Kinetics ◽

Nitrous Oxide Production ◽

Nitrogen Oxides Reduction ◽

Kinetics Of

Batch kinetic assays of DPAO-enriched biomass reveal elevated kinetics when nitrite is supplied for P uptake, but extremely slow kinetics for reduction of the potent greenhouse gas nitrous oxide.

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Phosphoryl- and Phosphonium-Bridged Viologens as Stable Two- and Three-Electron Acceptors for Organic Electrodes

10.26434/chemrxiv.12711770.v1 ◽

2020 ◽

Author(s):

Colin R. Bridges ◽

Andryj M. Borys ◽

Vanessa Béland ◽

Joshua R. Gaffen ◽

Thomas Baumgartner

Keyword(s):

Molecular Weight ◽

Organic Molecules ◽

Electrode Materials ◽

High Energy ◽

Electron Acceptors ◽

Low Molecular Weight ◽

Reduction Potentials ◽

Organic Electrode ◽

High Reduction ◽

High Specific Energy

Low molecular weight organic molecules that can accept multiple electrons at high reduction potentials are sought after as electrode materials for high-energy sustainable batteries. To date their synthesis has been difficult, and organic scaffolds for electron donors significantly outnumber electron acceptors. Herein, we report two highly electron deficient phosphaviologen derivatives from a phosphorus-bridged 4,4-bipyridine and characterize their electrochemical properties. Phosphaviologen sulfide (PVS) and P-methyl phosphaviologen (PVM) accept two and three electrons at high reduction potentials, respectively. PVM can reversibly accept 3 electrons between 3-3.6 V vs. Li/Li+ with an equivalent molecular weight of 102 g/(mol e-) (262 mAh/g), making it a promising scaffold for sustainable organic electrode materials having high specific energy densities.

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Mechanosynthesis and Thermoelectric Properties of Fe, Zn, and Cd-Doped P-Type Tetrahedrite: Cu12-xMxSb4S13

Materials ◽

10.3390/ma14133448 ◽

2021 ◽

Vol 14 (13) ◽

pp. 3448

Author(s):

Francisco Arturo López Cota ◽

José Alonso Díaz-Guillén ◽

Oscar Juan Dura ◽

Marco Antonio López de la Torre ◽

Joelis Rodríguez-Hernández ◽

...

Keyword(s):

Thermoelectric Properties ◽

Figure Of Merit ◽

Powder Processing ◽

High Energy ◽

Secondary Phases ◽

Ambient Conditions ◽

Cadmium Sulfate ◽

Electrical Conductivities ◽

Compositional Changes ◽

P Type

This contribution deals with the mechanochemical synthesis, characterization, and thermoelectric properties of tetrahedrite-based materials, Cu12-xMxSb4S13 (M = Fe2+, Zn2+, Cd2+; x = 0, 1.5, 2). High-energy mechanical milling allows obtaining pristine and substituted tetrahedrites, after short milling under ambient conditions, of stoichiometric mixtures of the corresponding commercially available binary sulfides, i.e., Cu2S, CuS, Sb2S3, and MS (M = Fe2+, Zn2+, Cd2+). All the target materials but those containing Cd were obtained as single-phase products; some admixture of a hydrated cadmium sulfate was also identified by XRD as a by-product when synthesizing Cu10Cd2Sb4S13. The as-obtained products were thermally stable when firing in argon up to a temperature of 350–400 °C. Overall, the substitution of Cu(II) by Fe(II), Zn(II), or Cd(II) reduces tetrahedrites’ thermal and electrical conductivities but increases the Seebeck coefficient. Unfortunately, the values of the thermoelectric figure of merit obtained in this study are in general lower than those found in the literature for similar samples obtained by other powder processing methods; slight compositional changes, undetected secondary phases, and/or deficient sintering might account for some of these discrepancies.

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Greenhouse gas emissions from the water–air interface of a grassland river: a case study of the Xilin River

Scientific Reports ◽

10.1038/s41598-021-81658-x ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xue Hao ◽

Yu Ruihong ◽

Zhang Zhuangzhuang ◽

Qi Zhen ◽

Lu Xixi ◽

...

Keyword(s):

Carbon Dioxide ◽

Land Use ◽

Nitrous Oxide ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Ghg Emissions ◽

Nitrous Oxide Emissions ◽

Gas Emissions ◽

Sand Land ◽

Very High

AbstractGreenhouse gas (GHG) emissions from rivers and lakes have been shown to significantly contribute to global carbon and nitrogen cycling. In spatiotemporal-variable and human-impacted rivers in the grassland region, simultaneous carbon dioxide, methane and nitrous oxide emissions and their relationships under the different land use types are poorly documented. This research estimated greenhouse gas (CO2, CH4, N2O) emissions in the Xilin River of Inner Mongolia of China using direct measurements from 18 field campaigns under seven land use type (such as swamp, sand land, grassland, pond, reservoir, lake, waste water) conducted in 2018. The results showed that CO2 emissions were higher in June and August, mainly affected by pH and DO. Emissions of CH4 and N2O were higher in October, which were influenced by TN and TP. According to global warming potential, CO2 emissions accounted for 63.35% of the three GHG emissions, and CH4 and N2O emissions accounted for 35.98% and 0.66% in the Xilin river, respectively. Under the influence of different degrees of human-impact, the amount of CO2 emissions in the sand land type was very high, however, CH4 emissions and N2O emissions were very high in the artificial pond and the wastewater, respectively. For natural river, the greenhouse gas emissions from the reservoir and sand land were both low. The Xilin river was observed to be a source of carbon dioxide and methane, and the lake was a sink for nitrous oxide.

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Effects of strategic tillage on short-term erosion, nutrient loss in runoff and greenhouse gas emissions

Soil Research ◽

10.1071/sr16136 ◽

2017 ◽

Vol 55 (3) ◽

pp. 201 ◽

Cited By ~ 16

Author(s):

A. R. Melland ◽

D. L. Antille ◽

Y. P. Dang

Keyword(s):

Nitrous Oxide ◽

Greenhouse Gas ◽

Heavy Rainfall ◽

Ghg Emissions ◽

Nutrient Loss ◽

Nitrous Oxide Emissions ◽

Nutrient Losses ◽

Short Term ◽

Trade Offs ◽

Carbon Dioxide Co2

Occasional strategic tillage (ST) of long-term no-tillage (NT) soil to help control weeds may increase the risk of water, erosion and nutrient losses in runoff and of greenhouse gas (GHG) emissions compared with NT soil. The present study examined the short-term effect of ST on runoff and GHG emissions in NT soils under controlled-traffic farming regimes. A rainfall simulator was used to generate runoff from heavy rainfall (70mmh–1) on small plots of NT and ST on a Vertosol, Dermosol and Sodosol. Nitrous oxide (N2O), carbon dioxide (CO2) and methane (CH4) fluxes from the Vertosol and Sodosol were measured before and after the rain using passive chambers. On the Sodosol and Dermosol there was 30% and 70% more runoff, respectively, from ST plots than from NT plots, however, volumes were similar between tillage treatments on the Vertosol. Erosion was highest after ST on the Sodosol (8.3tha–1 suspended sediment) and there were no treatment differences on the other soils. Total nitrogen (N) loads in runoff followed a similar pattern, with 10.2kgha–1 in runoff from the ST treatment on the Sodosol. Total phosphorus loads were higher after ST than NT on both the Sodosol (3.1 and 0.9kgha–1, respectively) and the Dermosol (1.0 and 0.3kgha–1, respectively). Dissolved nutrient forms comprised less than 13% of total losses. Nitrous oxide emissions were low from both NT and ST in these low-input systems. However, ST decreased CH4 absorption from both soils and almost doubled CO2 emissions from the Sodosol. Strategic tillage may increase the susceptibility of Sodosols and Dermosols to water, sediment and nutrient losses in runoff after heavy rainfall. The trade-offs between weed control, erosion and GHG emissions should be considered as part of any tillage strategy.

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Fuel Optimization for Power, Heat and CHP Systems Including Emissions Regulations and Ambient Conditions

Advanced Energy Systems ◽

10.1115/imece2005-81707 ◽

2005 ◽

Author(s):

Manuel-Angel Gonzalez-Chapa ◽

Jose-Ramon Vega-Galaz

Keyword(s):

Power Systems ◽

Greenhouse Gas Emissions ◽

Greenhouse Gas ◽

Fossil Fuel ◽

Good Practice ◽

Combined Heat And Power ◽

Ambient Conditions ◽

Gas Emissions ◽

The World ◽

Fuel Optimization

Combined Heat and Power systems have been used all around the world due to their effective and viable way of transforming energy from fossil fuel. Indeed, the advantage of lower greenhouse gas emissions compared to those obtained in conventional power or conventional heat generation systems have been an important factor giving CHP systems an advantage over these conventional ones. Certainly CHP has been, and continues to be, a good practice while renewable technologies become more economically. While these technologies emerge it is important to continue minimizing these greenhouse gas emissions from conventional and CHP units as much as possible. This paper deals with the fuel optimization of power, heat and CHP systems including emissions and ambient conditions constraints. Ambient conditions variations are evaluated before solving the optimization and then introduced to the problem to consider their effects.

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Continuous measurements of nitrous oxide isotopomers during incubation experiments

10.5194/bg-2016-258 ◽

2016 ◽

Cited By ~ 1

Author(s):

Malte Winther ◽

David Balslev-Harder ◽

Søren Christensen ◽

Anders Priemé ◽

Bo Elberling ◽

...

Keyword(s):

Nitrous Oxide ◽

Greenhouse Gas ◽

Isotope Effect ◽

Atmospheric Chemistry ◽

Isotope Effects ◽

Denitrifying Bacteria ◽

Central Position ◽

Site Preference ◽

Continuous Measurements ◽

Incubation Experiments

Abstract. Nitrous oxide (N2O) is an important and strong greenhouse gas in the atmosphere and part of a feed-back loop with climate. N2O is produced by microbes during nitrification and denitrification in terrestrial and aquatic ecosystems. The main sinks for N2O are turnover by denitrification and photolysis and photo-oxidation in the stratosphere. The position of the isotope 15N in the linear N = N = O molecule can be distinguished between the central or terminal position (isotopomers of N2O). It has been demonstrated that nitrifying and denitrifying microbes have a different relative preference for the terminal and central position. Therefore, measurements of the site preference in N2O can be used to determine the source of N2O i.e. nitrification or denitrification. Recent instrument development allows for continuous (on the order of days) position dependent δ15N measurements at N2O concentrations relevant for studies of atmospheric chemistry. We present results from continuous incubation experiments with denitrifying bacteria, Pseudomonas fluorescens (producing and reducing N2O) and P. chlororaphis (only producing N2O). The continuous position dependent measurements reveal the transient pattern (KNO3 to N2O and N2, respectively), which can be compared to previous reported site preference (SP) values. We find bulk isotope effects of −5.5 ‰ ± 0.9 for P. chlororaphis. For P. fluorescens, the bulk isotope effect during production of N2O is −50.4 ‰ ± 9.3 and 8.5 ‰ ± 3.7 during N2O reduction. The values for P. fluorescens are in line with earlier findings, whereas the values for P. chlororaphis are larger than previously published δ15Nbulk measurements from production. The calculations of the SP isotope effect from the measurements of P. chlororaphis result in values of −6.6 ‰ ± 1.8. For P. fluorescens, the calculations results in SP values of −5.7 ‰ ± 5.6 during production of N2O and 2.3 ‰ ± 3.2 during reduction of N2O. In summary, we implemented continuous measurements of N2O isotopomers during incubation of denitrifying bacteria and believe that similar experiments will lead to a better understanding of denitrifying bacteria and N2O turnover in soils and sediments and ultimately hands-on knowledge on the biotic mechanisms behind greenhouse gas exchange of the Globe.

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Environmental controls of greenhouse gas release in a restoring peat bog in NW Germany

Biogeosciences Discussions ◽

10.5194/bgd-5-213-2008 ◽

2008 ◽

Vol 5 (1) ◽

pp. 213-242 ◽

Cited By ~ 3

Author(s):

S. Glatzel ◽

I. Forbrich ◽

C. Krüger ◽

S. Lemke ◽

G. Gerold

Keyword(s):

Nitrous Oxide ◽

Greenhouse Gas ◽

Nitrogen Deposition ◽

Stress Factors ◽

Atmospheric Nitrogen Deposition ◽

Gas Release ◽

Atmospheric Nitrogen ◽

Nw Germany ◽

Surface Peat ◽

Nitrous Oxide Release

Abstract. In Central Europe, most bogs have a history of drainage and many of them are currently being restored. Success of restoration as well as greenhouse gas exchange of these bogs is influenced by environmental stress factors as drought and atmospheric nitrogen deposition. We determined the methane and nitrous oxide exchange of sites in the strongly decomposed center and less decomposed edge of the Pietzmoor bog in NW Germany in 2004. Also, we examined the methane and nitrous oxide exchange of mesocosms from the center and edge before, during, and following a drainage experiment as well as carbon dioxide release from disturbed unfertilized and nitrogen fertilized surface peat. In the field, methane fluxes ranged from 0 to 3.8 mg m−2 h−1 and were highest from hollows. Field nitrous oxide fluxes ranged from 0 to 574 μg m−2 h−1 and were elevated at the edge. A large Eriophorum vaginatum tussock showed decreasing nitrous oxide release as the season progressed. Drainage of mesocosms decreased methane release to 0, even during rewetting. There was a tendency for a decrease of nitrous oxide release during drainage and for an increase in nitrous oxide release during rewetting. Nitrogen fertilization did not increase decomposition of surface peat. Our examinations suggest a competition between vascular vegetation and denitrifiers for excess nitrogen. We also provide evidence that the von Post humification index can be used to explain greenhouse gas release from bogs, if the role of vascular vegetation is also considered. An assessment of the greenhouse gas release from nitrogen saturated restoring bogs needs to take into account elevated release from fresh Sphagnum peat as well as from sedges growing on decomposed peat. Given the high atmospheric nitrogen deposition, restoration will not be able to achieve an oligotrophic ecosystem in the short term.

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