Negative Effect Of CO Research Articles

Development of Hydrogen Oxidation Reaction Catalysts to Overcome CO Poisoning and Elucidation of Reaction Mechanism

Passive autocatalytic recombiner (PAR) represents a potential technology for ensuring process safety in the hydrogen society. PARs function through the catalytic oxidation of generated or leaked hydrogen, facilitating its conversion into water and effectively mitigating the risk of hydrogen explosions. CO is recognized as a catalyst poison that hampers surface catalytic reactions. To investigate the negative effects of CO on the local structure of platinum metal nanoparticle catalysts during water formation, in situ and time-resolved X-ray absorption spectroscopy analyses were conducted. The results revealed that the Pt–Fe/CZY catalyst exhibited notable hydrogen oxidation activity even in the presence of CO. The enhanced performance can be attributed to the combined effects of Pt–Fe alloy composition and CZY support materials.

Evaluation of the simultaneous presence of SO2 and CO as impurities in the carbon capture and storage technology. CO2/SO2/CO cocapture

From the presented experimental data of two CO2-rich mixtures containing SO2 and CO as impurities of anthropogenic CO2, we evaluated the impact of the simultaneous presence of these impurities on the transport, injection and storage of carbon capture and storage (CCS) technology. We determined the density, vapor-liquid equilibrium and speed of sound of a cocapture mixture (non-purified captured flue gas) [CO2 + 4.93 mol% SO2 + 3.01 mol% CO] and a mixture representative of European emissions (purified) [CO2 + 0.09 mol% SO2 + 1.12 mol% CO], measured from 263 to 373 K and pressures up to 30 MPa for the density and up to 190 MPa for the speed of sound. Using our experimental results, we validated two extended versions of the equation of state for combustion gases (EOS-CG) and the perturbed-chain statistical associating fluid theory (PC-SAFT) equation of state (EoS). From the calculation of selected operational CCS parameters, we concluded that, in the cocapture mixture, SO2 overcomes or compensates for the negative effect of CO, and then this mixture could be a favorable fluid for CCS. The negative effect of CO predominates in the emissions mixture. Differences in the chemical reactivity due to the studied impurities were not considered.

Simultaneous CO2 capture and thermochemical heat storage by modified carbide slag in coupled calcium looping and CaO/Ca(OH)2 cycles

• A process coupled calcium looping and CaO/Ca(OH) 2 heat storage is proposed. • Modified carbide slag with by-product of biodiesel is employed in coupled process. • Treatment of by-product of biodiesel improves heat storage capacity of carbide slag. • Heat storage capacity of modified carbide slag rises by introducing calcium looping. • CO 2 uptake of modified carbide slag is activated by introducing heat storage cycles. The simultaneous CO 2 capture and heat storage performances of the modified carbide slag with by-product of biodiesel were investigated in the process coupled calcium looping and CaO/Ca(OH) 2 thermochemical heat storage using air as the heat transfer fluid. The modified carbide slag with by-product of biodiesel exhibits superior CO 2 capture and heat storage capacities in the coupled calcium looping and heat storage cycles. The hydration conversion and heat storage density of the modified carbide slag after 30 heat storage cycles are 0.65 mol·mol −1 and 1.14 GJ·t −1 , respectively, which are 1.6 times as high as those of calcined carbide slag. The negative effect of CO 2 in air as the heat storage fluid on the heat storage capacity of the modified carbide slag is overcome by introducing CO 2 capture cycles. In addition, the CO 2 capture reactivity of the modified carbide slag after the multiple calcium looping cycles is enhanced by the introduction of heat storage cycles. By introducing 10 heat storage cycles after the 10th and 15th CO 2 capture cycles, the CO 2 capture capacities of the modified carbide slag are subsequently improved by 32% and 43%, respectively. The porous and loose structure of modified carbide slag reduces the diffusion resistances of CO 2 and steam in the material in the coupled process. The formed CaCO 3 in the modified carbide slag as a result of air as the heat transfer fluid in heat storage cycles decomposes to regenerate CaO in calcium looping cycles, which improves heat storage capacity. Therefore, the modified carbide slag with by-product of biodiesel seems promising in the coupled calcium looping and CaO/Ca(OH) 2 heat storage cycles.

Protective roles of grape seed (Vitis vinifera L.) extract against cobalt(II) nitrate stress in Allium cepa L. root tip cells.

Excessive doses of toxic metals such as cobalt may cause detrimental hazards to exposed organisms. Six groups of onion bulbs were formed to investigate the therapeutic effects of grape seed extract (GSE) against cobalt(II) nitrate (Co(NO3)2) exposure in Allium cepa L. root tips. Control group was irrigated with tap water, while the latter groups were exposed to 150mg/L GSE, 300mg/L GSE, 5.5ppm Co(NO3)2, 5.5ppm Co(NO3)2 + 150mg/L GSE and 5.5ppm Co(NO3)2 + 300mg/L GSE, respectively. Co(NO3)2 treatment seriously inhibited the root growth, germination and weight gain of the bulbs. Mitotic index was significantly decreased, whereas the chromosomal aberrations and micronuclei incidence exhibited a remarkable increase. In addition, Co(NO3)2 induced a variety of anatomical disorders in onion roots. Lipid peroxidation levels of the cellular membranes were assessed measuring the malondialdehyde content (MDA). MDA amount in Co(NO3)2-treated group reached the highest level among all groups. Co(NO3)2 treatment enhanced the activity of superoxide dismutase and catalase. The addition of GSE to Co(NO3)2 solution substantially suppressed the negative effects of Co(NO3)2 in a dose-dependent manner by strengthening the antioxidant defence system and reducing the cytotoxicity. Moreover, there was a significant recovery in growth parameters following the grape seed addition to Co(NO3)2. GSE had a remarkable reduction in genotoxicity when treated as a mixture with Co(NO3)2. Overall data obtained from this investigation proved that GSE, as a promising functional by-product, had a protective effect on Allium cepa L. against the toxic effects of Co(NO3)2.

Cobalt-induced retrotransposon polymorphism and humic acid protection on maize genome.

Retrotransposon activity and genomic template stability (GTS) are one of the most significant rearranging mechanisms in environmental stress. Therefore, in this study, it is aimed to elucidate effecting of Cobalt (Co) on the instability of genomes and Long Terminal Repeat retrotransposon polymorphism in Zea mays and whether humic acid (HA) has any role on these parameters. For this purpose, Retrotransposon-microsatellite amplified polymorphism (REMAP) and Inter-Retrotransposon Amplified Polymorphism (IRAP) markers were applied to evaluate retrotransposon polymorphism and the GTS levels. It was found that IRAP and REMAP primers generate unique polymorphic band structures on maize plants treated with various doses of Co. Retrotransposon polymorphism increased and GTS decreased while increasing Co concentration. On the other hand, there was a reduction in negative effects of Co on retrotransposon GTS and polymorphism after treatment with HA. The results indicate that HA may be used effectively for the protection of maize seedlings from the destructive effects of Co toxicity.

Developing Practical Lithium-Air Batteries by Avoiding Negative Effects of CO<sub>2</sub>

Developing Practical Lithium-Air Batteries by Avoiding Negative Effects of CO<sub>2</sub>

Maternal supplementation with corn oil associated or not with di-n-butyl phthalate increases circulating estradiol levels of gerbil offspring and impairs sperm reserve

This study evaluated the consequences of gestational exposure to di-n-butyl phthalate (DBP) for testicular steroidogenesis and sperm parameters of the adult gerbil and the interference of corn oil (co), a vehicle widely used for administration of liposoluble agents, on DBP effects. Pregnant gerbils received no treatment or were treated from gestational day 8 to 23 via gavage with 0.1 mL/day of co only or containing DBP (100 mg/kg/day). Maternal co intake enhanced serum estradiol levels and testicular content of ERα, and reduced sperm reserve of adult offspring. Gestational DBP exposure caused dyslipidemia, increased serum and intratesticular estradiol levels and reduced sperm reserve and motility. Thus, maternal co supplementation alters circulating estradiol and impairs sperm quantity and quality of offspring. Gestational DBP exposure alters lipid metabolism and testicular steroidogenesis and worsens the negative effects of co on the sperm reserve and motility of gerbil. Therefore, co interferes with the reproductive response to DBP.

CO-Terminated Pt/Au Codeposition on Titania Nanotube Arrays (TNAs)

Forming platinum monolayers on less-expensive materials is an ingenious way to enhance the mass activities for oxygen reduction reaction (ORR) and decrease the amount of this scarce and precious metal in fuel cell technology. Previously, we observed low activities of Pt catalysts deposited directly on titania nanotube arrays (TNAs). Here, we propose a gold interlayer between Pt and TiO2. The synthesis is attempted by the codeposition of Pt and Au from CO-saturated solution. The activity of the Pt/Au codeposited catalyst is higher than in the case when Pt is deposited alone. This result suggests that Au is a promising way to enhance ORR activity. The activity of this catalyst, however, is still much lower than that of the Pt monolayer on bulk gold. This is explained by the negative effects of CO, disrupting the chance of monolayer formation by preadsorption to the TNA substrate.

Hydrogen flux through the membrane based on the Pd–In–Ru foil

The hydrogen flux through the foil (thickness 30 μm) with the composition Pd–6.0 wt % In–0.5 wt % Ru in the temperature range from 593 to 823 K is studied. The permeability of Pd–In–Ru foil at 823 K is 3 times higher than the foil of the Pd–23 wt % Ag alloy. The H2 flux in the Pd–In–Ru foil is controlled by the diffusion of atomic hydrogen in the membrane bulk. The apparent activation energy of the hydrogen permeance is 18.7 kJ/mol. The influence of impurities (CO, N2, Ar) on the hydrogen flux is studied using both a sweep gas (N2) and transmembrane pressure. An insignificant negative effect of CO is observed in experiments using a sweep gas. When the transmembrane pressure is used, CO exerts a negative effect on the H2 flux, and this influence decreases with increasing temperature. The negative effect of CO decreases with the simultaneous use of transmembrane pressure and sweep gas. Contact of the foil with pure CO results in an insignificant formation of carbon deposits on the membrane surface, which exerts almost no effect on the H2 flux. No carbon deposits are formed on contact of the foil with the mixture H2–22.5% CO due to CO methanation with the formation of CH4 and H2O.

Cyclic Oxidation of High Mo, Reduced Density Superalloys

Cyclic oxidation was characterized as part of a statistically designed, 12-alloy compositional study of 2nd generation single crystal superalloys as part of a broader study to co-optimize density, creep strength, and cyclic oxidation. The primary modification was a replacement of 5 wt. % W by 7% or 12% Mo for density reductions of 2%–7%. Compositions at two levels of Mo, Cr, Co, and Re were produced, along with a midpoint composition. Initially, polycrystalline vacuum induction samples were screened in 1100 °C cyclic furnace tests using 1 h cycles for 200 h. The behavior was primarily delimited by Cr content, producing final weight changes of −40 mg/cm2 to −10 mg/cm2 for 0% Cr alloys and −2 mg/cm2 to +1 mg/cm2 for 5% Cr alloys. Accordingly, a multiple linear regression fit yielded an equation showing a strong positive Cr effect and lesser negative effects of Co and Mo. The results for 5% Cr alloys compare well to −1 mg/cm2, and +0.5 mg/cm2 for Rene′ N4 and Rene′ N5 (or Rene′ N6), respectively. Scale phases commonly identified were Al2O3, NiAl2O4, NiTa2O6, and NiO, with (Ni,Co)MoO4 found only on the least resistant alloys having 0% Cr and 12% Mo. Scale microstructures were complex and reflected variations in the regional spallation history. Large faceted NiO grains and fine NiTa2O6 particles distributed along NiAl2O4 grain boundaries were typical distinctive features. NiMoO4 formation, decomposition, and volatility occurred for a few high Mo compositions. A creep, density, phase stability, and oxidation balanced 5% Cr, 10% Co, 7% Mo, and 3% Re alloy was selected to be taken forward for more extensive evaluations in single crystal form.

Y2O3系酸化物によるNOの直接分解(第6報)添加物によるCO2の共存効果の低減

Y2O3系酸化物によるNOの直接分解(第6報)添加物によるCO2の共存効果の低減

Impact of pressure and gas type on adhesion formation and biomaterial integration in laparoscopy

Laparoscopic mesh repair of inguinal and incisional hernias has been widely adopted. Nevertheless, knowledge about the impact of pneumoperitoneum on mesh integration is rare. The present study investigates pressure and gas-dependent effects of pneumoperitoneum on adhesion formation and biomaterial integration in a standardized animal model. Laparoscopic intraperitoneal onlay mesh implantation (IPOM) was performed in 32 female chinchilla rabbits using CO(2) or helium for pneumoperitoneum. Intra-abdominal pressures were 3 or 6 mmHg. Animals were killed after 21 days, and the abdominal wall was explanted for subsequent histopathological examinations. Adhesions were assessed qualitatively with a scoring system, and the adhesion surface was analyzed semiquantitatively by planimetry. Infiltration of macrophages (CD68), expression of matrix metalloproteinase 13 (MMP-13), and cell proliferation (Ki67) were analyzed at the mesh to host interface by immunohistochemistry. The collagen type I/III ratio was analyzed by cross-polarization microscopy to determine the quality of mesh integration. After 21 days, perifilamental infiltration with macrophages (CD68) and percentage of proliferating cells (Ki67) were highest after 6 mmHg of CO(2) pneumoperitoneum. The extent of adhesions, as well as the expression of MMP-13 and the collagen type I/III ratio, were similar between groups. Our experiments showed no pressure or gas-dependent alterations of adhesion formation and only minor effects on biomaterial integration. Altogether, there is no evidence for a clinically negative effect of CO(2) pneumoperitoneum.

Preferential oxidation of CO in H2-rich stream over CuO/Ce1−xTixO2 catalysts

CuO/Ce1−xTixO2 prepared by sol–gel impregnation was used as catalysts for the preferential oxidation (PROX) of CO in H2-rich stream. The effects of support composition, catalyst calcination temperature as well as the presence of H2O and CO2 in the reaction stream on the catalytic performance of CuO/Ce1−xTixO2 were investigated. The results indicated that the catalyst CuO/Ce0.8Ti0.2O2 exhibits the highest activity and the optimal temperature for the catalyst calcination is 500°C. The presence of H2O and CO2 in the reaction stream has a negative effect on the catalytic activity and stability of CuO/Ce0.8Ti0.2O2. The negative effect of CO2 on the catalyst stability is stronger than that of H2O, suggesting that the accumulation of carbonate species may be the main reason for catalyst deactivation. The characterization by means of XRD, HRTEM, and H2-TPR indicated that the doping of TiO2 in CeO2 enhances the surface area of the composite oxide support, decreases its particle size, and promotes the dispersion of active copper species. The strong interaction between TiO2 and CeO2 in the support as well as the interfacial interaction between CuO and the support may also contribute to the high catalytic activity of CuO/Ce0.8Ti0.2O2.

Economic assessment of enhanced Coalbed Methane recovery for low rank coal system

Abstract Enhanced Coalbed Methane Recovery (ECBMR) is usually targeted for the bituminous coals, for the methane content in such coals is rather high and it leads to the higher profit by methane sales. Generally, methane content of low rank coals is small. However, adsorption ratio of CO 2 /CH 4 is high for low rank coal. It suggests that the CO 2 adsorption volume of low rank coal is large. Moreover, some low rank coal seams have high permeability. Low rank coal seams have advantage of high CO 2 adsorption volume and high permeability, and disadvantages of low methane content, possibility of large swelling from the viewpoint of ECBMR. When the carbon credit is expected, CO 2 storage in low rank coal systems is very promising due to their high CO 2 storage capacity. At the same time we must consider negative effect of CO 2 storage on the decrease of permeability caused by large swelling (CO 2 adsorption). A case study of economic assessment was made for low rank coal seams with sensitivity analysis. Well type of five spot patterns was employed. Well spacing, CO 2 concentration of injected gas and carbon credit is the parameter of sensitivity analysis. The results showed CO 2 concentration was the most important factor to determine the economy of the project affecting the permeability and the CO 2 storage rate. By selecting the optimum CO 2 concentration of the injected gas, the low rank coal would be one of the options for underground CO 2 storage under certain carbon credit.

The effect of copper on the selective carbon monoxide oxidation over alumina supported gold catalysts

The selective oxidation of CO in the presence of H 2 was investigated on Au catalysts promoted with different amounts of Cu. Au catalysts were prepared by the deposition–precipitation method and exhibited a satisfactory activity at low temperature with adequate selectivity. A considerable improvement in CO conversion was achieved when the O 2/CO ratio was increased from the value of 0.5–1.0. The addition of Cu to Au/Al 2O 3 catalysts caused an increase in the selectivity to CO oxidation due to an interaction between Au and Cu on the surface of the catalysts. However, this beneficial effect was limited to an optimal content of Cu. The catalysts were characterized by temperature programmed reduction and DRS UV–vis spectroscopy, indicating the formation of small bimetallic Au–Cu particles. The presence of water vapor in the feed stream played a positive effect in the CO conversion and selectivity while the CO 2 presence diminished the CO conversion and selectivity. In the case of a realistic reformate, when both H 2O and CO 2 are present, the positive effect of H 2O was able to compensate the negative effect of CO 2 depending on the temperature of reaction.

Catalytic performance and characterization of Au/doped-ceria catalysts for the preferential CO oxidation reaction

The physicochemical properties and catalytic performance in the preferential CO oxidation (PROX) reaction of nanosized gold supported on doped-ceria were investigated. Zn- and Sm-doped Au/ceria catalysts were found to be more active than undoped Au/ceria, whereas the addition of lanthanum oxide had the opposite effect. A reductive pretreatment at 373 K for 1 h promoted catalytic activity. The ability of Au/doped ceria catalysts to tolerate the presence of CO 2 and H 2O in the feed was also studied. Adding CO 2 in the reactant feed provoked a decrease in catalyst activity; however, catalyst doping improved the resistance toward deactivation by CO 2. On the other hand, co-addition of CO 2 and H 2O counteracted the negative effect of CO 2, especially in the case of doped samples. IR studies of CO adsorbed at 90 K on the catalysts after different pretreatments gave information on the type of gold species present on the catalyst. The dispersion of gold depended on the nature of the dopant. Au/Zn–CeO 2 catalyst demonstrated the greatest dispersion as revealed by HRTEM measurements and comparison of FTIR intensity of the CO adsorption bands on the reduced samples. AuCe x clusters were formed on this catalyst by increasing the prereduction temperature. Large amounts of CO 2 were produced during the CO–O 2 interaction in the presence of a high concentration of zero-valent gold sites on the surface of the modified Au catalysts, confirming their important role in the CO oxidation reaction. IR spectra were collected after exposure to CO + O 2 + H 2 and also after addition of water in the PROX reaction mixture over Au/Zn–CeO 2 at 400 K. The evolution of the FTIR spectra run at 90 K after admission of O 2 on preadsorbed CO on the most active catalyst (i.e., Au/Zn–CeO 2) demonstrates the roles of the highly dispersed gold and the reduced support in activating oxygen.

Catalytic performances of Pt–Pd/CeO 2 catalysts for selective CO oxidation

Platinum–Palladium supported on ceria catalysts has been studied for preferential oxidation of CO in the presence of hydrogen. The catalysts were prepared by impregnation method using different supports. The catalytic activity tests were performed using a fixed bed reactor in the temperature range of 50 – 190 ∘ C atmospheric pressure. Effects of support, ratio of Pt–Pd, O 2 concentration water vapor concentration, CO 2 concentration, and the combination of H 2O and CO 2 in the feed stream on the catalytic performance of Pt–Pd/CeO 2 catalysts were also investigated. The experimental results showed that 1% (1:7) Pt–Pd/CeO 2 (sol–gel) exhibited higher activity than other catalysts examined. Water vapor in the feed substantially increased the activity of the catalysts, whereas CO 2 in the feed stream drastically decreased the activity of the catalysts. When both H 2O and CO 2 were added in the feed stream, the positive effect of H 2O is more pronounced than the negative effect of CO 2.

Studies on the effects of CO 2 and CO on n-butane isomerisation activity over sulfated zirconia

Sulfated zirconia with 10 wt.% nominal sulfate loading was synthesised, characterised and tested for n-butane isomerisation activity varying butane diluents such as CO 2, CO and nitrogen, and reaction temperatures. Results revealed that a fresh, air-pre-treated catalyst was poisoned by CO 2, and exhibited low catalytic activity, whereas an air-regenerated catalyst showed high butane conversion with negligible catalyst deactivation in presence of CO 2. Incorporation of CO in the feed stream poisoned the catalyst immediately and removal of CO from the feed regenerated the catalyst activity. The reversible poisoning effect of CO was prominent at low temperature and was absent at elevated temperatures. It seems that the surface oxy species of sulfated zirconia, both the lattice and the adsorbed, play an important role in butane isomerisation and catalyst poisoning by CO 2, whereas, formation of surface stabilised adspecies causes the negative effect of CO.

N-Pentane Conversion on Sulfated Zirconia in the Absence and Presence of Carbon Monoxide: Evidence for Monomolecular Mechanism of Isomerization from the 13C MAS NMR Study

In situ 13C MAS NMR analysis of hydrocarbon products formed from the selectively 13C-labeled n-pentane on sulfated zirconia in the absence and presence of carbon monoxide provide the evidence that iso-pentane forms by two parallel processes: isomerization and conjunct polymerization. Peculiarities of the 13C label scrambling from n-pentane into iso-pentane provide unequivocal evidence for monomolecular mechanism of the alkane isomerization. Besides iso-pentane, conjunct polymerization affords also the products of n-pentane “disproportionation,” butanes and hexanes and stable cyclopentenyl cations; the latter are in charge of the catalyst deactivation. Carbon monoxide suppresses completely the process of conjunct polymerization, whereas the process of intramolecular isomerization does not. In the presence of carbon monoxide carbonylation of n-pentane occurs in parallel with its isomerization, giving rise to a mixture of aldehydes, ketones, and carboxylic acids. Carbonylation of n-pentane with CO contributes to the earlier observed negative effect of CO on the alkane isomerization rate.