Decomposition Of Nitrous Oxide Research Articles

Cost modeling of photocatalytic decomposition of atmospheric methane and nitrous oxide

Abstract The photocatalytic decomposition of atmospheric methane (CH4) and nitrous oxide (N2O) could be valuable tools for mitigating climate change; however, to date, few photocatalyst deployment strategies have had their costs modeled. Here, we construct basic cost models of three photocatalytic CH4 and N2O decomposition systems: 1) a ground-based solar system with natural airflow over photocatalyst-painted rooftops, 2) a ground-based LED-lit system with fan-driven airflow, and 3) an aerosol-based solar system on solid particles dispersed in the atmosphere. Each model takes as inputs the photocatalyst’s apparent quantum yield (AQY; a measure of how efficiently photons drive a desired chemical reaction) and the local CH4 or N2O concentration. Each model calculates an overall rate of greenhouse gas drawdown and returns a levelized cost of greenhouse gas removal per equivalent ton of carbon dioxide (tCO2e). Based on prior studies of atmospheric carbon dioxide removal, we adopt $100/tCO2e as a target cost.

We estimate that painting rooftops with photocatalysts might meet the target cost for decomposition of >10ppm CH4 with catalyst AQYs >4%. If painting and cleaning costs were reduced by a factor of ~3 from our scenario, removal of ambient CH4 could meet the cost target with AQYs >1% and removal of ambient N2O could do so with AQYs >0.1%. 
Fan-driven systems with LED illumination appear to be very challenging, achieving removal costs <$100/tCO2e only for AQYs of >10% for CH4 and >1% for N2O. Dispersing photocatalytic aerosols in the troposphere could be cost-effective with AQYs of >0.4% for ambient CH4 or >0.04% for ambient N2O. However, the mass of aerosols required is large and their side effects and social acceptability are uncertain. We note that, for any system, AQYs on the order of 1% will likely be extremely challenging to achieve with such dilute reagents.

A Versatile Passivated Protein‐Adsorption Platform for Rapid Healing of Vascular Stents by Modulating the Microenvironment

AbstractBiodegradable stents have paved the way to treat coronary artery disease. However, rapid reendothelialization is required to solve the problems of mismatched degradation rates, localized inflammation, and insufficient biocompatibility. Herein, a novel passivated protein‐adsorption coating is synthesized by coordination chelation, oxidation, cross‐linking, polymerization, and deposition of dopamine, (‐)‐epigallocatechin gallate (EGCG), and copper ions (Cu2+) using two‐electron oxidation. This coating exhibits hierarchical functionality, that is, at the macroscale, its superhydrophilicity conveys antifouling ability; whereas at the microscale, the active groups (quinone‐, amino‐, hydroxyphenyl groups and aromatic ring) facilitate protein adsorption. Antifouling ability prevents acute thrombosis and inflammation and maintains initial microenvironment stability post‐implantation. The active groups facilitate gradual endothelial cells (ECs) adhesion. Meanwhile, the decomposition of nitric oxide (NO) donors to release NO is catalyzed by Cu2+, and EGCG alleviates or prevents oxidative stress damage, inflammatory responses, thrombosis formation, and excessive smooth muscle cells proliferation in the stent microenvironment. This provides favorable conditions for the rapid and healthy growth of ECs. This study proposes a novel strategy for rapid neointima formation comprising healthy ECs on the surfaces of biodegradable stents by depositing a passivated protein‐adsorption coating (polydopamine/EGCG/Cu), opening new possibilities for the efficient treatment of coronary artery disease.

Effect of ammonia addition on the dispersion and activity of supported copper species on porous silica–alumina hollow spheres for catalytic decomposition of nitrous oxide

In this work, we investigated the influence of ammonia addition in the immersion process of active species on the dispersion and activity of copper-supported porous hollow silica–alumina sphere catalysts for the decomposition of nitrous oxide.

GAS-PHASE OXIDATION OF 2-PICOLINE BY “GREEN OXIDIZERS” H2O2 AND N2O

This communication presents the results of studies of coherently synchronized reactions of 2-picoline oxidation with hydrogen peroxide and nitrous oxide (I) in the gas phase. Optimal conditions for obtaining target products in these reactions are revealed. The influence of the process parameters on the value of the determinant in the reactions: dealcodimerization of 2-picoline with hydrogen peroxide and dimerization of 2-picoline with nitrous oxide (I) is shown. Calculated in the reaction of deal-codimerization of 2-picoline with hydrogen peroxide, the determinant of chemical conjugation has a value of D = 0.17 under optimal conditions, which indicates the induced character of dealcodimerization of 2-picoline. Based on this value, a quantitative assessment of the influence of the primary reaction (decomposition of hydrogen peroxide) on the secondary one (dealcodimerization of 2-picoline) was given. In the reaction of dimerization of 2-picoline with nitrous oxide (I), the chemical conjugation determinant has, under optimal conditions, a value of D = 0.54, which, according to the chemical interference scale, is in the region of chemical conjugation, when the primary reaction (the decomposition of nitrous oxide (I)) accelerates the secondary reaction (dimerization of 2-picoline)

Preparation of Denitrification Materials with Nickel Slag for Nitric Oxide Decomposition in Cement Kilns.

NOx emission from the cement industry have received much attention. In order to reduce the NOx emission in cement kilns, nickel slag was used to prepare the non-ammonia denitrification material, and a denitrification mechanism was proposed in this study. The results showed that the denitrification material prepared at pH 7 exhibited the best denitrification performance. At low temperature, the highest denitrification performance was achieved between 200 and 300 °C with a NO decomposition rate of approximately 40%. Then, the NO decomposition rate increased as the temperature increased, reaching over 95% above 700 °C. The physicochemical characteristics showed that the material had the highest specific surface area and the highest relative Fe content, which benefited the denitrification performance. The divalent iron of the denitrification material was considered the active site for the reaction, and trivalent iron was not conducive to denitrification performance at a low temperature range. After the denitrification reaction, the Fe3+/Fe2+ increased from 0.89 to 1.31. The proposed denitrification mechanism was the redox process between divalent iron and trivalent iron. This study not only recycles industrial waste to reduce solid waste pollution but also efficiently removes nitrogen oxides from cement kilns without ammonia.

LOW-TEMPERATURE deN<sub>2</sub>O CATALYST BASED ON Co<sub>3</sub>O<sub>4</sub> FOR A SINGLE-REACTOR SCHEME FOR THE REMOVAL OF NITROGEN OXIDES IN NITRIC ACID PRODUCTION

Cesium promoted cobalt spinel is promising as a catalyst for the low-temperature decomposition of nitrous oxide for use in the second stage of a single-reactor scheme for complex purification from nitrogen oxides. In this work, the influence of the conditions for the preparation of massive granular and block catalysts based on Co3O4 by extrusion molding has been studied.

Influence of Co3O4-based catalysts on N2O catalytic decomposition and NO conversion.

This study investigated the effect of different Co3O4-based catalysts on the catalytic decomposition of nitrous oxide (N2O) and on nitric oxide (NO) conversion. The experiments were carried out using various reaction temperatures, alkaline solutions, pH, mixing conditions, aging times, space velocities, impregnation loads, and compounds. The results showed that Co3O4 catalysts prepared by precipitation methods have the highest catalytic activity and N2O conversion, even at low reaction temperatures, while the commercial nano and powder forms of Co3O4 (CS) have the lowest performance. The catalysts become inactive at temperatures below 400°C, and their activity is strongly influenced by the mixing temperature. Samples without stirring during the aging process have higher catalytic activity than those with stirring, even at low reaction temperatures (200-300°C). The catalytic activity of Co3O4 PM1 decreases with low W/F values and low reaction temperatures. Additionally, the catalyst's performance tends to increase with the reduction process. The study suggests that cobalt-oxide-based catalysts are effective in N2O catalytic decomposition and NO conversion. The findings may be useful in the design and optimization of catalytic systems for N2O and NO control. The results obtained provide important insights into the development of highly efficient, low-cost, and sustainable catalysts for environmental protection.

Direct decomposition of nitrous oxide by rhodium supported on ZrSnO4

Novel catalysts of Rh/ZrSnO4 were synthesized, and their catalytic activities for the direct decomposition of nitrous oxide (N2O) were investigated. ZrSnO4 with an [Formula: see text]-PbO2-type structure was used as a promoter, since the oxygen supply from its lattice was expected to facilitate N2O decomposition. Among the prepared catalysts, 1.0 wt.% Rh/ZrSnO4 exhibited the highest catalytic activity: N2O was completely decomposed at [Formula: see text]C. This activity was higher than those for 1.0 wt.% Rh/ZrO2 and 1.0 wt.% Rh/SnO2, indicating that the ZrSnO4 solid promoted N2O decomposition. In addition, the 1.0 wt.% Rh/ZrSnO4 catalyst featured high durability in the presence of O2, CO2, and H2O vapors.

Laser absorption study of the N2+ O → NO + N and NO + O → O2+ N Zeldovich reactions in shock-heated N2O mixtures

The fast decomposition of nitrous oxide (N2O) into molecular nitrogen (N2) and atomic oxygen (O) was leveraged to probe the N2 + O and NO + O Zeldovich reactions behind reflected shocks in experiments spanning 2000–6800 K and 0.04–1.67 atm in 1% and 5% N2O diluted in either argon (Ar) or N2, respectively. One infrared (IR) and two ultraviolet (UV) laser absorption diagnostic systems probed N2O and NO. The IR laser system probed N2O in isolation, while the two UV laser systems probed a combination of N2O, NO, and O2 using an online/offline method. The resulting absorbance time-histories were used to infer the NO rotational temperature and the number densities of N2O and NO. The number density time-histories were used to infer (1) the N2O dissociation rate to form N2 and O ( k d N 2 O − [ M ]), (2) the reaction rate of N2O and O to form two NO ( k d N 2 O − O , 1), (3) the NO + O Zeldovich reaction rate ( k z NO − O), and (4) the N2 + O Zeldovich reaction rate ( k z N 2 − O). The experiments were insensitive to the reaction rate of N2O and O to form O2 and N2 ( k d N 2 O − O , 2) at high temperatures. Generally, k d N 2 O − [ M ] was inferred from IR and UV offline data, with k d N 2 O − O , 1, k z NO − O, and k z N 2 − O inferred from UV online data in Ar and N2 dilution. Each inferred reaction rate shows consistency with literature, while extending data to higher temperatures with reduced uncertainty. The reduced uncertainty is sufficient to enable comparisons of the data to various high-temperature quantum chemistry models.

Low-Temperature Decomposition of Nitrous Oxide on Cs/MexCo3−xO4 (Me: Ni or Mg, x = 0–0.9) Oxides

Mixed oxides MexCo3−xO4 (Me: Ni or Mg, x = 0–0.9) with a spinel structure were synthesized by precipitation from Me, Co nitrate solutions using (NH4)2CO3 as the precipitating agent with subsequent modification of the dry precipitate with cesium by the Pechini method and calcination. The samples were studied by XRD, TPR, and TPD methods. Their catalytic activity was studied in the low-temperature (150–350 °C) nitrous oxide decomposition process. It was shown that an increase in the degree of substitution of cobalt (x) leads to a significant decrease in the degree of crystallization of the oxides, an increase in the specific surface area, and the formation of surface weakly bound oxygen species. The highest activity was shown by the catalysts with a degree of substitution x = 0.1, especially by the nickel-substituted sample, which contained the maximum amount of weakly bound surface oxygen species. The difference in the influence of Mg and Ni on the MexCo3−xO4 properties is discussed.

Ability of Shirasu‐based Material for Adsorption of Metal Ions and Its Promotion for Catalytic Decomposition of Nitrous Oxide

AbstractThis work investigated ability of Shirasu‐based material for adsorption of metal ions and their promotion effect for catalytic decomposition of nitrous oxide. Catalytically active cobalt and copper species were adsorbed on the Shirasu‐based material by immerse process of aqueous matal solutions. In all the Co/Cu ratios (Co/(Co+Cu)=1, 0.75, and 0.5), cobalt species were preferentially adsorbed on the Shirasu‐based material. The cobalt species tended to be adsorbed on the silica sites of the sample with Co/(Co+Cu)=0.75. and the catalyst exhibited the highest activity for decomposition of nitrous oxide. Introduced nitrous oxide was completely decomposed at the reaction temperatures above 673 K.

Influence of the LaMn1−xFexO3 (x = 0–1) Composition on Catalytic Activities in the Reactions Involving Oxygen

Perovskite samples of the LaMn1−xFexO3 (x = 0–1) series were prepared by the Pechini method; their physicochemical properties were studied using XRD, HRTEM, XPS, and BET, and their catalytic activity was estimated in nitrous oxide decomposition and methane and CO oxidation reactions. In methane and CO oxidation reactions, all intermediate (0 < x < 1) samples of the series exhibited a lower catalytic activity normalized to the unit surface area as compared to the extreme terms, whereas in the nitrous oxide decomposition all intermediate samples were more active than extreme terms of the series. Different dependences of activities on the composition obtained in the study for the tested reactions involving the catalyst oxygen are caused by differences in the reaction mechanisms.

Extreme Change Events of Stratospheric HCl and N2O in the Mid-Latitude Region of the Northern Hemisphere

Hydrogen chloride (HCl) is the main reservoir species of chlorine and chemical decomposition of nitrous oxide (N2O) is the primary source of NOx (=NO + NO2) in the stratosphere. Changes in stratospheric HCl and N2O play a critical role in modulating variations in stratospheric ozone. Thus, long-term trends in stratospheric HCl and N2O have been investigated in many studies, whereas short-term changes have not received enough attention. Here, using satellite observations and a chemical transport model, we found that two extreme change events for HCl and N2O in the Northern Hemisphere mid-latitude middle and lower stratosphere have occurred over past decades, which are characterized by a sharp increase in HCl and a decrease in N2O over several months; for example, HCl increased (and N2O decreased) by 0.135 ppbv (−33.352 ppbv) in 1987/1988 and by 0.196 ppbv (−28.553 ppbv) in 2010/2011. Further analysis shows that the extreme change events of stratospheric HCl and N2O in these two periods are closely related to anomalous residual circulation caused by the joint effects of the strong easterly phase of the semi-annual oscillation and the strong polar vortex.

Decomposition of Nitrous Oxide using a Copper‐supported Shirasu Catalyst

AbstractThis work firstly reported catalytic activity of copper species supported on Shirasu‐based materials for decomposition of nitrous oxide. From the results of EDS and XPS analyses, the bulk and surface compositions of the supported copper species depends on its impregnation conditions. The copper species were preferably supported on the surface silica sites of the Shirasu‐based materials with addition of ammonia during the impregnation process, and the amount of the copper species increased with increasing the amount of ammonia. The catalysts with the active copper species preferably supported on the silica sites exhibited high activity for decomposition of nitrous oxide. The catalytic activity also depended on the kinds of Shirasu‐based materials, and the copper‐supported catalyst on a Shirasu balloon, A3NN, showed the highest activity. The catalytic activity improved with addition of ammonia into the feed reactant gas, and nitrous oxide in the mixed gas was completely decomposed above 673 K.

High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide: II. Nitrogen dilution from 1900 to 8200 K

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in nitrogen (N2) to target the NO–N2 rates relevant to high-temperature air, thereby building off the argon (Ar) experiments investigated in Part I. [J. W. Streicher et al., “High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K,” Phys. Fluids 34, 116122 (2022)] Again, two continuous-wave ultraviolet laser diagnostics were used to obtain quantum-state-specific time histories of NO in high-temperature shock-tube experiments, including absorbance (α) in the ground vibrational state of NO, translational/rotational temperature (Ttr), and number density of NO (nNO). The experiments probed mixtures of 2% and 0.4% NO diluted in either pure N2 (NO/N2) or an equal parts N2/Ar mixture (NO/N2/Ar). The NO/N2 experiments spanned initial post-reflected-shock conditions from 1900–7000 K and 0.05–1.14 atm, while the NO/N2/Ar experiments spanned from 1900–8200 K and 0.11–1.52 atm. This work leveraged two vibrational relaxation times from Part I (τVTNO−Ar and τVTNO−NO) and extended measurements to include the vibrational–translational and vibrational–vibrational relaxation times with N2 (τVTNO−N2 and τVVNO−N2). Similarly, this work leveraged the four rate coefficients from Part I (kdNO−Ar, kdNO−NO, kfN2O, and kzNO−O) and extended measurements to include NO dissociation with N2 (kdNO−N2). A few studies have directly inferred these rates from experiments, and the current data differ from common model values. In particular, τVTNO−N2 differs slightly from the Millikan and White correlation, τVVNO−N2 is four times slower than Taylor et al.'s inference, and kdNO−N2 is four times slower than the Park two-temperature model. The unique experimental measurements and dilution in N2 in this study significantly improve the understanding of the vibrational relaxation and decomposition of NO in high-temperature air.

High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. I. Argon dilution from 2200 to 8700 K

This work investigates the high-temperature vibrational relaxation and decomposition of nitric oxide (NO) diluted in argon (Ar) to target NO–Ar and NO–NO interactions and to augment the subsequent inference of rates for NO diluted in nitrogen (N2). [J. W. Streicher et al., “High-temperature vibrational relaxation and decomposition of shock-heated nitric oxide. II. Nitrogen dilution from 1900 to 8200 K,” Phys. Fluids (submitted)]. In both Part I and Part II, two continuous-wave ultraviolet laser diagnostics were used to probe quantum-state-specific time-histories of NO behind reflected shocks in high-temperature shock-tube experiments, enabling inferences of multiple vibrational relaxation times and reaction rate constants for NO decomposition reactions. These diagnostics both probed absorbance (α) in the ground vibrational state of NO but in multiple rotational states utilizing light at 224.8150 and 226.1025 nm. The absorbance was subsequently used to infer quantum-state-specific time-histories for translational/rotational temperature (Ttr) via the absorbance ratio and number density of NO (nNO) via α, Ttr, and the absorbance cross sections (σ). The experiments for Ar dilution probed mixtures of 2% NO/Ar, 1% NO/Ar, and 0.4% NO/Ar for initial post-reflected-shock conditions from 2200–8700 K and 0.12–0.97 atm. Further analysis of the absorbance, temperature, and number density time-histories yielded two vibrational relaxation times (τVTNO−Ar and τVTNO−NO) and four rate coefficients for multiple NO decomposition reactions (kdNO−Ar, kdNO−NO, kfN2O, and kzNO−O)—each of which is extended to higher temperatures than any previous study and with reduced scatter and uncertainty. Generally, these rate data are consistent with data from the literature, although τVTNO−Ar and τVTNO−NO are observed to differ strongly from both the Millikan and White correlation and Park two-temperature model.

Simultaneous generation of electricity, ethylene and decomposition of nitrous oxide via protonic ceramic fuel cell membrane reactor

Ethylene, one of the most widely produced building blocks in the petrochemical industry, has received intense attention. Ethylene production, using electrochemical hydrogen pump-facilitated nonoxidative dehydrogenation of ethane (NDE) to ethylene, is an emerging and promising route, promoting the transformation of the ethylene industry from energy-intensive steam cracking process to new electrochemical membrane reactor technology. In this work, the NDE reaction is incorporated into a BaZr0.1Ce0.7Y0.1Yb0.1O3−δ electrolyte-supported protonic ceramic fuel cell membrane reactor to co-generate electricity and ethylene, utilizing the Nb and Cu doped perovskite oxide Pr0.6Sr0.4Fe0.8Nb0.1Cu0.1O3−δ (PSFNCu) as anode catalytic layer. Due to the doping of Nb and Cu, PSFNCu was endowed with high reduction tolerance and rich oxygen vacancies, showing excellent NDE catalytic performance. The maximum power density of the assembled reactor reaches 200 mW cm−2 at 750 °C, with high ethane conversion (44.9%) and ethylene selectivity (92.7%). Moreover, the nitrous oxide decomposition was first coupled in the protonic ceramic fuel cell membrane reactor to consume the permeated protons. As a result, the generation of electricity, ethylene and decomposition of nitrous oxide can be simultaneously obtained by a single reactor. Specifically, the maximum power density of the cell reaches 208 mW cm−2 at 750 °C, with high ethane conversion (45.2%), ethylene selectivity (92.5%), and nitrous oxide conversion (19.0%). This multi-win technology is promising for not only the production of chemicals and energy but also greenhouse gas reduction.

Strong Electronic Orbit Coupling between Cobalt and Single-Atom Praseodymium for Boosted Nitrous Oxide Decomposition on Co3O4 Catalyst.

Nitrous oxide (N2O) has gained increasing attention as an important noncarbon dioxide greenhouse gas, and catalytic decomposition is an effective method of reducing its emissions. Here, Co3O4 was synthesized by the sol-gel method and single-atom Pr was confined in its matrix to improve the N2O decomposition performance. It was observed that the reaction rate varied in a volcano-like pattern with the amount of doped Pr. A N2O decomposition reaction rate 5-7.5 times greater than that of pure Co3O4 is achieved on the catalyst with a Pr/Co molar ratio of 0.06:1, and further Pr doping reduced the activity due to PrOx cluster formation. Combined with X-ray photoelectron spectroscopy, X-ray absorption fine structure, density functional theory and in situ near-ambient pressure X-ray photoelectron spectroscopy, it was demonstrated that the single-atom doped Pr in Co3O4 generates the "Pr 4f-O 2p-Co 3d" network, which redistributes the electrons in Co3O4 lattice and increases the t2g electrons at the tetracoordinated Co2+ sites. This coupling between the Pr 4f orbit and Co2+ 3d orbit triggers the formation of a 4f-3d electronic ladder, which accelerates the electron transfer from Co2+ to the 3π* antibonding orbital of N2O, thus contributing to the N-O bond cleavage. Moreover, the energy barrier for each elementary reaction in the decomposition process of N2O is reduced, especially for O2 desorption. Our work provides a theoretical grounding and reference for designing atomically modified catalysts for N2O decomposition.

Fabrication of Copper-Cerium Oxide Hollow Spheres with Carbon Template and Their Catalytic Activity for Decomposition of Nitrous Oxide

Fabrication of Copper-Cerium Oxide Hollow Spheres with Carbon Template and Their Catalytic Activity for Decomposition of Nitrous Oxide

Catalytic Performance and Sulfur Dioxide Resistance of One-Pot Synthesized Fe-MCM-22 in Selective Catalytic Reduction of Nitrogen Oxides with Ammonia (NH3-SCR)-The Effect of Iron Content.

The catalytic performance of Fe-catalysts in selective catalytic reduction of nitrogen oxides with ammonia (NH3-SCR) strongly depends on the nature of iron sites. Therefore, we aimed to prepare and investigate the catalytic potential of Fe-MCM-22 with various Si/Fe molar ratios in NH3-SCR. The samples were prepared by the one-pot synthesis method to provide high dispersion of iron and reduce the number of synthesis steps. We have found that the sample with the lowest concentration of Fe exhibited the highest catalytic activity of ca. 100% at 175 °C, due to the abundance of well-dispersed isolated iron species. The decrease of Si/Fe limited the formation of microporous structure and resulted in partial amorphization, formation of iron oxide clusters, and emission of N2O during the catalytic reaction. However, an optimal concentration of FexOy oligomers contributed to the decomposition of nitrous oxide within 250–400 °C. Moreover, the acidic character of the catalysts was not a key factor determining the high conversion of NO. Additionally, we conducted NH3-SCR catalytic tests over the samples after poisoning with sulfur dioxide (SO2). We observed that SO2 affected the catalytic performance mainly in the low-temperature region, due to the deposition of thermally unstable ammonium sulfates.