Carbon Monoxide Species Research Articles

Al‐Decorated C20 Fullerene as a Promising Noble Metal‐Free Catalyst for CO Oxidation: A DFT Study

AbstractTo remove the toxic carbon monoxide (CO) gas from the environment, recently, researchers have taken great interest in single‐atom catalysts (SACs). In this study, we investigated various reaction pathways and barrier energies for the CO oxidation process onto Al‐decorated C20 fullerene (Al@C20) employing density functional theory (DFT). The outcomes validate that Al decoration on C20 is energetically stable while the corresponding electronic properties show that the Al atom acts as the reactive site for catalytic activity. The bond distances and larger negative adsorption energies (−0.65 and −2.53 eV) evince that CO and O2 species adsorbed strongly to the Al atom. For the oxidation of CO, two popular mechanisms are examined: Eley Rideal (ER) and Langmuir Hinshelwood (LH). The assessment of energy barriers discloses that the CO oxidation reaction progresses via the LH mechanism. Additionally, the CO + O* → CO2 reaction proceeds very quickly onto the Al@C20 catalyst, with a very small energy barrier (0.13 eV), indicating the excellent catalytic reactivity of the studied catalyst. These results propose that the designed catalyst can be valuable in the progress of novel noble metal‐free catalysts for harmful CO elimination from the environment.

Investigation on laminar burning velocity measurements of premixed Ethane-Air mixture at higher pressure and temperature conditions

The externally heated diverging channel (EHDC) method was utilized to evaluate the laminar burning velocity (LBV) of premixed ethane-air flames at higher mixture temperature (350-620 K) and pressure (1-5 atm) conditions over different mixture strengths (ϕ = 0.7-1.3). The maximum LBV was noted at ϕ = 1.1 for all pressure and temperature conditions. The inverted parabolic behavior of the temperature exponent was obtained with the minima at ϕ = 1.1. The pressure exponent (β) exhibits a parabolic variation with its maxima at ϕ = 1.0. The current results are further analyzed and compared with the literature measurements, and the comprehensive kinetic model predictions of USC mech II, San Diego mech, and Aramco mech 1.3. The present LBV measurements match well with the kinetic model predictions of Aramco mech 1.3 at most of the mixture and pressure conditions. The present results propose the variation of pressure exponent (β) as a function of temperature ratio, and temperature exponent (α) as a function of pressure ratio for different mixture conditions (ϕ). A revised power-law correlation for α and β variations is also recommended as, Su=Su0Tu/Tu0∝0+∝11-Pu/Pu0)Pu/Pu0β0+β11-Tu/Tu0. The sensitivity analysis indicates the maximum decrement in the positive sensitivity for the chain branching reaction HCO + M ↔ H + CO + M (R30) across all the stated mixture conditions, owing to an increment in the third body effects along with pressure and temperature. The reaction pathway analysis reveals a maximum net reduction in the elemental flux (∼56 %) for the reaction between the species carbon monoxide (CO) and carbon dioxide (CO2) through different reactions, due to a rise in pressure and temperature.

Plasma functionalization mechanism to modify isocyanate groups on multiwalled carbon nanotubes

This article reports a possible functionalization mechanism of isocyanate (NCO) groups on multiwalled carbon nanotubes (CNTs) with low-temperature plasma. The mechanism was clarified according to the analysis with two plasmas generated with the gas mixture of (1) nitrogen and carbon dioxide and (2) nitrogen and oxygen. We analyzed the mechanism through optical emission spectroscopy from these plasmas and the NCO functionalization ratio measured with the fluorescent method after plasma exposure over CNTs. The optical emission gave us information on the quantitative analysis of the gas species of atomic nitrogen (N), atomic oxygen (O), and carbon monoxide (CO) and the qualitative analysis of carbon nitride (CN) species in the plasma. Compared with our results from the gas species in the plasma and the NCO functionalization ratio on CNTs, CO and CN species in the gas phase in plasma are less likely to contribute to forming NCO groups on CNTs. Rather, the equal densities of atomic nitrogen and oxygen species in the plasma could be effective in forming NCO groups on the CNT surface: the NCO groups should form by N, O, and carbon (C) species on the CNT surface. The groups likely build up gradually by N, O, and C individually reaching a CNT surface, or the NCO radicals form in the gas phase and then attach to the CNT surface.

Lighting up trace carbon monoxide and residual palladium species by a low cytotoxic mitochondria targetable red fluorescent probe: Its large scaled applications.

High levels of residual palladium can lead to serious negative health effects. Carbon monoxide (CO) is a significant gasotransmitter in transporting intermolecular and intramolecular signals to balance several physiological processes. Therefore, there is a need for rapid detection of CO and palladium residue. To address these issues, we have designed a novel light-up fluorescent probe for the detection of Pd and CO. It can not only detect Pd and CO selectively with a remarkable chromogenic and red fluorescent response over other metal ions allowing detection with naked eyes but also discriminate Pd0 and Pd2+/Pd4+ species. The detection reaction is confirmed by HPLC analysis. The probe demonstrates biocompatibility and mitochondrial target ability for potential biological applications. The practical applications based on drug residue and soil analysis, and smartphone have been successfully performed. Bioimaging of the concentration change of Pd and CO in HeLa cells using the probe is successfully applied. Therefore, the present approach can provide early diagnosis of Pd and CO with low detection limit, low cytotoxicity, high selectivity, and sensitivity.

Promoting mechanism of CuO on catalytic performance of CeFe catalyst for simultaneous removal of NOx and CO

Nitrogen oxides (NOx) and carbon monoxide (CO) coexisted in numerous industrial waste gases. And selective catalytic reduction of NOx with ammonia (NH3-SCR) and CO catalytic oxidation were considered as the effective technologies for simultaneous elimination of NOx and CO, respectively. However, an efficient bifunctional catalyst was crucial for achieving simultaneous removal of NOx and CO. Herein, we developed a series of Cu-modified CeFe catalysts for simultaneous removal of NOx and CO. The results demonstrated that 5Cu-CeFe catalyst presented the best catalytic performance, achieving approximately 81% NOx removal efficiency and nearly 99% CO conversion rate at 200 °C under a gas houely space velocity of 90,000 h−1. The XPS analysis demonstrated that copper oxides played a critical role in promoting the formation of Ce3+ and Oβ, thereby facilitating the NH3-SCR catalytic performance and CO catalytic oxidation. Moreover, the copper oxide modification of CeFe catalyst attained a trade-off between the surface acidity and redox ability, resulting in improving adsorption and activition capacity of the reactant gases. In situ DRIFTS experiments revealed that the NH3-SCR process primarily obeyed the Eley-Rideal (E-R) pathway over both CeFe and 5Cu-CeFe catalysts, while Langmuir-Hinshelwood (L-H) pathway hardly participated in NH3-SCR process. The presence of Cu+–CO species and surface lattice oxygen was crucial for CO oxidation, and both Mars-van Krevelen (M−K) and L-H pathways might be involved in the CO catalytic oxidation process over 5Cu-CeFe catalyst.

Insertion of carbon monoxide into an unsymmetrical diborene to form an oxaborirane.

The insertion of carbon monoxide (CO) into an unsymmetrical diborene, concomitant with B-O bond formation under ambient conditions, gives an oxaborirane species. A similar insertion reaction with isocyanide, the isoelectronic species of CO, generates azaboriridine derivatives.

Hollow spheres as inert packed bed from lean to rich combustion in porous media

• Hollow spheres were used in filtration combustion processes. • Lean and rich fuel-air filtration combustion was investigated. • Numerical and experimental comparison of solid and hollow spheres. • Hydrogen and syngas were produced at high temperatures. Hollow spheres as inert packed bed is an innovative technology with high potential in filtration combustion. Their lower specific density, geometry, and the radiation inside the sphere enhance the overall heat transfer of the sphere, and therefore, increase the effective conductivity of the packed bed, while the other thermo-physical properties remain unchanged. The present work investigates numerically and experimentally the effects of the packed bed made of hollow alumina spheres filled with air, from lean to rich premixed methane-air combustion within this porous media, with focus on the production of hydrogen and carbon monoxide species on rich conditions. The experimental part considers the equivalence ratio from 0.8 to 1.3. The numerical approach contemplates a one-dimensional model based on two-temperature approximation (gas and solid) with a four-step chemical reaction mechanism for homogeneous reactions at equivalence ratios between 0.4 and 1.6, for different spheres geometries. The results of experimental and numerical investigations are in good agreement. Both indicate that the use of hollow spheres packed bed (HS), in contrast to the packed bed made of the solid spheres (SS), shows higher temperatures and flame front velocities in all the equivalence ratio ranges. At the stoichiometric equivalence ratio, the numerical investigation in the HS case results in higher temperatures of 168 K and 21 K, in the solid and gas phases, respectively, in comparison with the SS case. The combustion products for different spheres geometries and equivalence ratios present the same trend and values for both HS and SS cases. The yields of carbon monoxide and hydrogen goes up to 37% and 42%, respectively.

Revisited Mechanisms for Glucose Electrooxidation at Platinum and Gold Nanoparticles

The electrooxidation of glucose on gold (Au) and platinum (Pt) nanoparticles (NPs) is investigated in alkaline medium by cyclic voltammetry after chronoamperometry at different potentials (+0.100 V, +0.200 V, and +0.400 V vs the reversible hydrogen electrode, RHE), in situ Fourier transform infrared spectroscopy, and differential electrochemical mass spectrometry measurements. We show that glucose can adsorb on both metallic Au and Pt surfaces at low potentials, but that the adsorbed species are different: hydrogen atoms, carbon monoxide (CO), lactones and gluconate species on Pt-NPs, and only hydrogen atoms and gluconate species on Au-NPs. On Pt-NPs, the first oxidation peak between +0.050 V vs RHE and +0.250 V vs RHE is due to glucose adsorption and hydrogen atoms oxidation into protons (H+), whereas the second electrochemical feature between +0.250 V vs RHE and +0.800 V vs RHE is due to the oxidation of glucose into lactone and gluconate and of adsorbed CO into carbon dioxide (CO2). For Au-NPs, adsorbed hydrogen atoms are not oxidized into H+ but transformed into molecular hydrogen H2, and glucose is adsorbed as gluconate species that are desorbed into gluconates for potentials higher than +0.300 V vs RHE.Graphical Abstract

Structure-activity relationship of Pt catalyst on engineered ceria-alumina support for CO oxidation

In heterogeneous catalysis, the promotion of low temperature activity and enhancement of thermal stability simultaneously especially for precious metal catalysts is always highly demanded but very challenging. Herein we report a novel Pt catalyst on ceria-alumina (CeO2/Al2O3) support (Pt/CA-T) engineered by a two-step ceria deposition strategy, exhibiting superior thermal stability and low-temperature carbon monoxide (CO) oxidation activity after activation. Pt single sites anchored to engineered CeO2 edge sites are much more stable than that to CeO2 (111) surface, and such stable single sites can be transformed into highly active Pt clusters for efficient low-temperature CO oxidation. Active site identification indicates that the CO oxidation activity of different Pt sites follows such sequence: Pt cluster step sites ≈ Pt cluster terrace sites > Pt cluster corner sites ≫ Pt single sites on CeO2. The excellent low temperature activity of activated Pt/CA-T catalyst for CO oxidation is associated with its abundant Pt cluster step and terrace sites as well as rich Pt-CeO2 interfaces, which facilitate the adsorption of active CO species and superior oxygen activation/transfer ability. The present study provides new insights into the structure–activity relationship of Pt-CeO2-Al2O3 catalyst, which can also guide the preparation of other highly robust supported catalysts for important industrial applications.

Cosmic ray sputtering yield of interstellar ice mantles

Aims. Cosmic-ray-induced sputtering is one of the important desorption mechanisms at work in astrophysical environments. The chemical evolution observed in high-density regions, from dense clouds to protoplanetary disks, and the release of species condensed on dust grains, is one key parameter to be taken into account in interpretations of both observations and models. Methods. This study is part of an ongoing systematic experimental determination of the parameters to consider in astrophysical cosmic ray sputtering. As was already done for water ice, we investigated the sputtering yield as a function of ice mantle thickness for the two next most abundant species of ice mantles, carbon monoxide and carbon dioxide, which were exposed to several ion beams to explore the dependence with deposited energy. Results. These ice sputtering yields are constant for thick films. It decreases rapidly for thin ice films when reaching the impinging ion sputtering desorption depth. An ice mantle thickness dependence constraint can be implemented in the astrophysical modelling of the sputtering process, in particular close to the onset of ice mantle formation at low visual extinctions.

Mixture fraction analysis of combustion products in medium-scale pool fires

A mixture fraction analysis is performed to investigate the characteristics of time-averaged gaseous species measurements made along the centerline of medium-scale pool fires steadily burning in a quiescent environment. A series of fire experiments are conducted using 30 cm diameter liquid and 37 cm diameter gas pool burners. All gaseous species measurements are extracted at various heights within the fire and analyzed using an Agilent 5977E Series Gas Chromatograph with mass selectivity and thermal conductivity detectors. Soot mass fractions are simultaneously measured during gas sampling. For all fuels, the results show that the local composition plotted as a function of mixture fraction collapses the experimental data into a few coherent lines that nearly match the idealized reactions. Differences between the theoretical and experimental data are attributed to the presence of carbon monoxide, soot, and other intermediate carbon-containing species. The ratio of carbon monoxide and soot is presented as a function of mixture fraction in which a trend is observed.

Tailoring the Antipoisoning Performance of Pd for Formic Acid Electrooxidation via an Ordered PdBi Intermetallic

Pd-based materials are promising electrocatalysts for the formic acid oxidation reaction (FAOR) but suffer from poor durability due to the poisoning of adsorbed carbon monoxide species (COads). In ...

Carbon monoxide concentration in mainstream E-cigarette emissions measured with diode laser spectroscopy

The e-fluid heated in electronic cigarettes (e-cigarettes) is largely composed of organic compounds, specifically propylene glycol, vegetable glycerin and flavouring compounds. When heated, as it is in an e-cigarette, the...

Hydrogen thermo-photo production using Ru/TiO2: Heat and light synergistic effects

A series of ruthenium – anatase solids with noble metal loadings from 1 to 10 wt. %. was tested in the gas phase thermo-photo production of hydrogen using methanol as a sacrificial agent. Samples were characterized using X-Ray diffraction, UV–vis, X-ray photoelectron and absorption spectroscopies as well as transmission electron microscopy. A pure, high surface area anatase was present in all catalysts. It supports a ruthenium co-catalyst displaying a core-shell structure having an hcp metallic core and a RuO2-type shell structure. Activity, particularly under the combined use of light and heat, was analyzed by means of “excess” functions; the reaction rate and the quantum efficiency of the process were studied for thermo-photo vs. thermo/photo processes to provide conclusive evidence that the ruthenium-anatase materials display a strong synergistic use of both energy sources when utilized simultaneously. Optimum thermo-photo performance was achieved with a 5 wt. % Ru/TiO2 catalyst. An in-situ infrared study of the behavior of the gas-solid interface under the isolate or simultaneous action of heat and light was carried out to interpret the activity and analyze reaction mechanism. The study points out the key role of the ruthenium-anatase interface in activating carbon-containing species leading to carbon monoxide species subsequently transformed through a water gas shift type reaction. Activity seems directly correlated with the promotion of this step by light and heat within the context of a mechanism where methanol is previously oxidized in titania sites and such species evolves at the mentioned interface to generate hydrogen and carbon oxide molecules.

A reaction kinetics study and model development to predict the formation and destruction of organosulfur species (carbonyl sulfide and mercaptans) in Claus furnace

AbstractCarbonyl sulfide (COS), carbon disulfide (CS2), and mercaptans (e.g., CH3SH) are unwanted sulfurous species that are produced in sulfur recovery units (SRUs). They can cause equipment corrosion, reduce catalyst activity, and are pollutants for the environment. This necessitates process optimization to minimize their formation in the SRUs using an accurate kinetic model. In this paper, new reactions of COS and mercaptans are studied using the CBS‐QB3 level of theory, and their kinetics are evaluated using transition state theory. Such reactions are added to a detailed SRU reaction mechanism, and the updated mechanism is validated using the data on COS and mercaptans from lab‐scale experimental setups and an industrial plant. Compared to the previous models, significant improvements in the predicted concentrations of the important species such as COS, carbon monoxide (CO), and sulfur oxides (SO and SO2) are observed due to the inclusion of the new reactions in the mechanism. The simulation studies in a homogeneous reactor within the temperature range of 800–2000 K revealed that furnace temperatures near 1300 K are required to minimize CO and COS formation, while ensuring the oxidation of methane (CH4), mercaptans, and aromatics. Mercaptan formation mainly took place at low temperatures near 900 K. Claus furnace simulations are conducted using industrial feed and operating conditions to show that the optimized inlet air temperature and fuel gas flow rate can assist in simultaneously reducing the emissions of CO and harmful sulfurous species such as COS, CH3SH, and CS2 from the furnace.

Study on Carbon Dioxide, Methane, Sulfur Dioxide, Temperature, Ozone and Rainfall Variations in Hawaiian Island (190 34’ Latitude, 1550 30’ Longitude)

The Hawaii observatory is located at 190 34’ latitude, 1550 30’ longitude and 4207 sq m area. The island of Hawaii is built from fine separate shield volcanoes that erupted somewhat sequentially one overlapping the other. Moderate to strong trade winds carry as and vog from Kilauea volcano around the southern tip of the island. Ninety-nine percent of the gas molecules emitted during a volcanic eruptions are water vapor (H2O), carbon dioxide (Co2), and sulfur dioxide (So2). The remaining one percent is comprised of small amounts of hydrogen sulfide, carbon monoxide, hydrogen chloride, hydrogen fluoride, and other minor gas species. The most critical factors that determine how much vog impacts any area are wind direction and speed. Where and how bad the vog is ultimately depends on several additional factors including air temperature, humidity, and rainfall emitted from Kīlauea Volcano. The Co2 atmosphere concentration measured at Mauna Lao observatory (MLO). Hawaii have been used by advocates of anthropological global warming (AGW) as a bell weather of climate. Carbon dioxide concentrations in units of parts per million (PPM) have been measured daily and monthly have been averages reported since 1958. We have analyzed Co2 data from 1958 to 2014, So2 data from 1979 to 1997, CH4 data from 1992 to 2001, rainfall data from 1920 to 2012, temperature data from 1955 to 2015 and ozone data from 1958 to 2014. Here We have analyzed and interpret to draw the line graphs and bar graphs in the following parameters ozone, carbon dioxide, methane, temperature and rainfall. We find the following parameters i) Co2 gradually increased from 1958 to 2014 ii) CH4 gradually increased from 1992 to 2001 iii) The So2 gradually increased and decreased from 1979 to 1997 iv) Mauna loa Temperature increased from 1955 to 2015 and Opihihale Temperature increased from 1965 to 2010 v) Rainfall increased and decreased from 1920 to 2012 vi) Ozone increased and decreased from 1958 to 2014.

Monitoring the Interaction of CO with Graphene Supported Ir Clusters by Vibrational Spectroscopy and Density Functional Theory Calculations

The interaction of carbon monoxide (CO) with graphene supported Ir cluster (Ir/graphene/Ir(111)) and a Ir(111) single crystal surface was studied by infrared reflection–adsorption spectroscopy (IRRAS). The cluster morphology was characterized by scanning tunneling microscopy and density functional theory (DFT) calculations predicted the adsorption frequencies of CO molecules on the Ir single crystal surface and clusters. After exposing the clean Ir(111) surface to CO at 195 K, one intense vibrational band is observed at 2043 cm–1, which is assigned to on top CO species. This band shifts to a much higher frequency at 2082 cm–1 at higher CO exposure. After exposing clean graphene/Ir(111) to CO at 195 K, no CO band was observed in the IR spectra, which confirms a full graphene layer over the Ir(111) surface. However, CO molecules adsorb on Ir clusters supported on graphene/Ir(111) at 195 K. For the 0.05, 0.1, 0.15, and 0.2 ML Ir clusters, two IR bands were observed at 2060 and 2088 cm–1, 2050 and 2070 cm–1, ...

Evidence for a gas-flaring source of alkanes leading to elevated ozone in air above West Africa

As part of the African Monsoon Multidisciplinary Analysis (AMMA) project, the FAAM BAe-146 research aircraft sampled the lower and mid-troposphere around the West Africa sub-region. Back trajectory analysis of the air parcels sampled on-board during the entire duration of the flights showed the history and fate of the air parcels. Data from flights B228 and B231 showed strongly enhanced carbon monoxide (CO) and ozone levels attributable to emissions of anthropogenic origin from the city of Lagos and gas flaring activities in the Nigeria oil fields. The elevated levels of ozone and CO observed at about 6 km above the sea-level on flight B231 were attributed to long-range transport of biomass burning plume from the East, around Sudan. The strongly enhanced mixing ratios of short-chained alkanes and CO (> 400 ppbv) observed from measurements on flights B228 and B231 are indicative of natural gas/combustion sources. Flight B222 sampled air parcels strongly impacted by emissions from Lagos but not from the Nigeria oil field and measured relatively lower mixing ratios of ozone, CO and short-chained alkanes species. Results from this study strongly suggests gas flaring emissions in the Niger Delta area to be a prominent contributor to the enhanced levels of short-chained alkane species observed in Lagos metropolis, especially during the West Africa Monsoon (WAM) months and, hence, a significant source of atmospheric aerosol in the sub-region. Key words: African Monsoon Multidisciplinary Analysis (AMMA), gas flaring, West Africa Monsoon, alkanes, ozone, Niger Delta.

Background PM2.5 source apportionment in the remote Northwestern United States

This study used the Environmental Protection Agency's positive matrix factorization model (EPA PMF5.0) to identify five primary source factors contributing to the ambient PM2.5 concentrations at Cheeka Peak Atmospheric Observatory (CPO), Neah Bay WA between January 2011 and December 2014. CPO is home to both an IMPROVE (Interagency Monitoring for Protected Visual Environments) and a NCore multi-pollutant monitoring site. Chemically resolved particulate data from the IMPROVE site was the input data to EPA PMF5.0 and the resulting source factors were derived solely from these data. Solutions from the model were analyzed in context with trace gas and meteorological data collected at the NCore site located roughly 10 m away. Seasonal and long-term trends were analyzed for all five factors and provide the first complete source apportionment analysis of PM2.5 at this remote location. The first factor, identified as marine-traffic residual fuel oil (RFO), was the highest contributor to PM2.5 during late summer. Over the 4-year analysis, the RFO percent contribution to total PM2.5 declined. This is consistent with previous studies and may be attributed to regulations restricting the sulfur content of ship fuel. Biomass combustion emissions (BMC) and sea salt were the largest PM2.5 sources observed at CPO in winter, accounting for over 80% of the fine particulate. BMC accounted for a large percent of the fine particulate pollution when winds were easterly, or continental. Sea salt was the dominant winter factor when winds blew from the west. Measured trace carbon monoxide (CO) and reactive nitrogen species (NOy) were most strongly correlated with the BMC factor and continental winds. The fourth factor was identified as aged crustal material, or dust. In all three years, dust peaked in the spring and was associated exclusively with north-easterly winds. The last factor was identified as aged sea salt mixed with nitrate, sulfate, and other components common to RFO and BMC source factors. It did not exhibit a strong seasonal cycle or dependence on wind direction.

Effects of Oxygen and Carbon Monoxide Species on the Gas Sensing Properties of SnO2 Nanoparticles

Effects of Oxygen and Carbon Monoxide Species on the Gas Sensing Properties of SnO₂ Nanoparticles