Impact Of SO Research Articles

A Review on the Impact of SO2 on the Oxidation of NO, Hydrocarbons, and CO in Diesel Emission Control Catalysis

A Review on the Impact of SO₂ on the Oxidation of NO, Hydrocarbons, and CO in Diesel Emission Control Catalysis

Impact of SO2 on Alteration of Reservoir Rock with Ca-Deficient Conditions and Poor Buffering Capacity under a CO2 Geologic Storage Condition

The objective of this study is to evaluate the impact of SO2-CO2-water-rock interaction on the alteration of a reservoir rock having Ca-deficient conditions and little buffering capacity and its implication for porosity change near the injection well from a CO2 storage pilot site, Republic of Korea. For our study, three cases of experimental and geochemical modeling were carried out (pure CO2, 0.1% SO2 in CO2, and 1% SO2 in CO2, resp.) under realistic geologic storage conditions. Our results show that SO2 accelerated water-rock interactions by lowering the pH. In the 1% SO2 case, pH remained less than 2 during the experiments because of insufficient buffering capacity. Sulfate minerals were not precipitated because of an insufficient supply of Ca. Because the total volume of precipitated secondary minerals was less than that of the dissolved primary minerals, the porosity of rock increased in all cases. Chlorite largely contributed to the decrease in total rock volume although it formed only 4.8 wt.% of the rock. Our study shows that the coinjection of a certain amount of SO2 at CO2 storage reservoirs without carbonate and Ca-rich minerals can significantly increase the porosity by enhancing water-rock interactions. This procedure can be beneficial to CO2 injection under some conditions.

Impact of SO2 in the Presence of Steam on Carbonation and Sulfation of Calcium Sorbents

AbstractThe effect of the presence of steam and SO2 on CO2 sorption capacity during multicycle carbonation‐calcination tests on three limestone types from Germany, Greece, and Poland was studied. The behavior of carbonation conversion under realistic process atmospheres containing SO2 and additionally steam as well as of sulfation under similar temperature conditions was investigated. The deactivation effect of SO2 on CO2 sorption capacity in two cases with and without steam was analyzed. The negative impact of the competitive sulfation reaction towards carbonation increased in the subsequent cycles for both cases, but to a less extent in the presence of steam. Sulfation conversion changed quite monotonically in the subsequent cycle in dry gas, whereas in the presence of steam sulfation conversion decreased slightly while carbonation conversion increased. It was found for the tested sorbents that carbonation conversion decreased to varying degrees in the presence of SO2. The Polish and Greek limestone showed the largest loss of sorption capacity in the presence of SO2. The quantitative influence of SO2 on carbonation conversion in dry and wet gas was determined.

Implications of Near-Term Coal Power Plant Retirement for SO2 and NOX and Life Cycle GHG Emissions

Regulations monitoring SO(2), NO(X), mercury, and other metal emissions in the U.S. will likely result in coal plant retirement in the near-term. Life cycle assessment studies have previously estimated the environmental benefits of displacing coal with natural gas for electricity generation, by comparing systems that consist of individual natural gas and coal power plants. However, such system comparisons may not be appropriate to analyze impacts of coal plant retirement in existing power fleets. To meet this limitation, simplified economic dispatch models for PJM, MISO, and ERCOT regions are developed in this study to examine changes in regional power plant dispatch that occur when coal power plants are retired. These models estimate the order in which existing power plants are dispatched to meet electricity demand based on short-run marginal costs, with cheaper plants being dispatched first. Five scenarios of coal plant retirement are considered: retiring top CO(2) emitters, top NO(X) emitters, top SO(2) emitters, small and inefficient plants, and old and inefficient plants. Changes in fuel use, life cycle greenhouse gas emissions (including uncertainty), and SO(2) and NO(X) emissions are estimated. Life cycle GHG emissions were found to decrease by less than 4% in almost all scenarios modeled. In addition, changes in marginal damage costs due to SO(2), and NO(X) emissions are estimated using the county level marginal damage costs reported in the Air Pollution Emissions Experiments and Policy (APEEP) model, which are a proxy for measuring regional impacts of SO(2) and NO(X) emissions. Results suggest that location specific parameters should be considered within environmental policy frameworks targeting coal plant retirement, to account for regional variability in the benefits of reducing the impact of SO(2) and NO(X) emissions.

NO (or NH 3) + O 2 adsorption on fluorine-doped vanadia/titania and its role in the mechanism of a two-step process characterized by EPR

This study aimed at elucidating a two-step process of the low-temperature selective catalytic reduction (SCR) reaction. The data were collected through studying the EPR signal of NO (or NH 3) + O 2 adsorption on fluorine-doped vanadia/titania and vanadia/titania catalysts used for SCR reaction, as well as the impact of SO 2 and H 2O added to the gas mixtures. The EPR experiments provided a new method to explain the SCR reaction, which were associated with NO (NH 3) + O 2 reacting systems and had been inferred step by step. In summary, the first step of the two-step process was that the vanadium sites were reduced by NO or NH 3 as electron donor; then, the superoxide ions appeared over vanadium. The experimental findings showed that the surface acidity, surface oxygen vacancies and the superoxide could be increased by fluorine doping, accordingly, the two-step process rate would be enhanced by F doping. It was the reason for F-doped catalyst had the higher catalytic activity than vanadia/titania. This two-step process could also be used to elucidate the inhibition mechanism of SO 2 and H 2O for the SCR reaction.

Impact of SO 2 concentration on the corrosion rate of X70 steel and iron in water-saturated supercritical CO 2 mixed with SO 2

The corrosion behavior of X70 steel and iron in water-saturated supercritical CO 2 mixed with SO 2 was investigated using weight-loss measurements. As a comparison, the instantaneous corrosion rate in the early stages for iron in the same corrosion environment was measured by resistance relaxation method. Surface analyzes using SEM/EDS, XRD and XPS were applied to study the morphology and chemical composition of the corroded sample surface. Weight-loss method results showed that the corrosion rate of X70 steel samples increased with SO 2 concentration, while the corrosion rate increased before decreasing with SO 2 concentration for iron sample. Comparing resistance relaxation method results with weight-loss method results, it is found that the instantaneous corrosion rate of iron is much higher than the uniform corrosion rate of the iron tablet specimens which are covered with thick corrosion product films after a long period of corrosion. The corrosion product films were mainly composed of FeSO 4 and FeSO 3 hydrates. The possible reaction mechanism under such environment was also analyzed, and the electrochemical reaction between the dissolved SO 2 in the condensed water film with iron is the critical reaction step.

Impact of SO 2 poisoning of platinum nanoparticles modified glassy carbon electrode on oxygen reduction

An extraordinary recovery characteristic of Pt-nanoparticles from SO 2 poisoning is introduced in this study. Platinum nanoparticles (nano-Pt) modified glassy carbon electrode (nano-Pt/GC) has been compared with polycrystalline platinum (poly-Pt) electrode towards SO 2 poisoning. Two procedures of recovery of the poisoned electrodes were achieved by cycling the potential in the narrow potential range (NPR, 0–0.8 V vs. Ag/AgCl/KCl (sat.)) and wide potential range (WPR, −0.2 to 1.3 V). The extent of recovery was marked using oxygen reduction reaction (ORR) as a probing reaction. SO 2 poisoning of the electrodes changed the mechanism of the oxygen reduction from the direct reduction to water to the stepwise reduction involving the formation of H 2O 2 as an intermediate, as indicated by the rotating ring-disk voltammetry. Using the WPR recovery procedure, it was found that two potential cycles were enough to recover 100% of the activity of the ORR on the nano-Pt/GC electrode. At the poly-Pt electrode, however, four potential cycles of the WPR caused only 79% in the current recovery, while the peak potential of the ORR was 130 mV negatively shifted as compared with the fresh poly-Pt electrode. Interestingly, the NPR procedure at the nano-Pt/GC electrode was even more efficient in the recovery than the WPR procedure at the poly-Pt electrode.

Predicting the impact of SO 3 on mercury removal by carbon sorbents

This paper introduces a combined homogeneous and heterogeneous SO 3 production mechanism to quantify the interference of SO 3 on the capture of Hg by unburned carbon (UBC) and activated carbon sorbents in flue gas from coal-fired power plants. This mechanism was validated against measurements at different locations along the gas cleaning systems at fourteen power plants representing the entire range of coal-S, furnace stoichiometry, and gas cleaning conditions found in commercial applications. The SO 3 production mechanism was then integrated into previously validated Hg transformation mechanisms to account for inhibition of Hg oxidation and removal due to SO 3 condensation on fly ash, UBC and activated carbon. This analysis was subsequently used to interpret Hg removals for more than two dozen test measurements at Daniel and the Mercury Research Center. These tests included different coal blends, ACI concentrations, conventional and brominated activated carbons, and SO 3 concentrations. The simulations clearly identified the tests affected by SO 3 interference and predicted the Hg removal by ACI to within 15% of the test measurements for 22 of the 27 tests at these two sites.

Potential dependence of sulfur dioxide poisoning and oxidation at the cathode of proton exchange membrane fuel cells

Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to investigate changes in the cathode after the introduction of SO 2. The decay in performance of the proton exchange membrane fuel cell (PEMFC) was ascribed to the increasing of the charge transfer resistance ( R ct) caused by the loss of the electrochemical surface area (ECA). The results show that the oxidation and adsorption behaviors of SO 2 depended closely on the potential. Adsorbed sulfur began to be oxidized over 0.9 V and could be oxidized completely with CV maximum potentials up to 1.05 V or higher. At about 0.65 V, the adsorbed SO 2 was probably in a molecular state, which could be reduced in the range of 0.65–0.05 V. Some SO 2 molecules occupied initially two Pt sites through S and O. One of the two sites could be released after the reduction. The increasing of ECA due to reduction could lessen the impact of SO 2 on the PEMFC performance at voltages below 0.65 V.

Ametryn degradation in the ultraviolet (UV) irradiation/hydrogen peroxide (H 2O 2) treatment

Ultraviolet (UV) irradiation (253.7 nm) in the presence of hydrogen peroxide (H 2O 2) was used to decompose aqueous ametryn. The concentrations of ametryn were measured with time under various experiment conditions. The investigated factors included H 2O 2 dosages, initial pH, initial ametryn concentrations, and a variety of inorganic anions. Results showed that ametryn degradation in UV/H 2O 2 process was a pseudo-first-order reaction. Removal rates of ametryn were greatly affected by H 2O 2 dosage and initial concentrations of ametryn, but appeared to be slightly influenced by initial pH. Furthermore, we investigated the effects of four anions (SO 4 2−, Cl −, HCO 3 −, and CO 3 2−) on ametryn degradation by UV/H 2O 2. The impact of SO 4 2− seemed to be insignificant; however, Cl −, HCO 3 −, and CO 3 2− considerably slowed down the degradation rate because they could strongly scavenge hydroxyl radicals (OH ) produced during the UV/H 2O 2 process. Finally, a preliminary cost analysis revealed that UV/H 2O 2 process was more cost-effective than the UV alone in removal of ametryn from water.

Landau Damping Effects on SO Limited Mobility

Surface optical phonons scattering is essential in determning the channel mobility of high-k gate dielectric MOSFETs. Metal gates are believed to modulate the effects of high-k phonons to some extent in comparison to poly-Si gates. In this work nonideal metal gate model is used to study the impact of SO scattering on the nMOSFET channel mobility. Landau damping effects, which are found to be important in the coupled plasmon-phonon scattering, are studied from the perspective of different criteria in selecting the Landau limits.

Impact of copper on the performance and sulfur tolerance of barium-based NOx storage-reduction catalysts

The presence of sulfur in automotive exhaust is known to be detrimental to lean-NOx traps as SO2 is oxidized to SO3 that competes with NO2 for sites on the trap and is difficult to remove. In this study the effect of adding Cu to the prototypical Pt–BaO/γ-Al2O3 formulation on the system's tolerance for sulfur was investigated. It was found that in the absence of sulfur, Cu decreases the performance in terms of both NOx storage capacity and reduction of NOx to N2 during regeneration. In the presence of SO2, Cu provides a significant improvement in sulfur tolerance so that, after sulfur exposure, the storage capacity of the Cu-modified material can exceed that of the baseline material. The sulfur tolerance afforded by Cu is attributed to a moderation in the activity for SO2 oxidation resulting from the formation of a Pt–Cu bimetallic phase. The propensity for NO oxidation is also modified, but to a lesser effect. Evidence for the bimetallic phase is provided by temperature-programmed reduction (TPR) and electron microscopy. The impact of SO2 on the Cu-modified material is greater during the regenerative reduction cycle. In this case, the results suggest that sulfur blocks Pt and possibly Cu sites and that the sulfur is not removed by oxidation during the subsequent storage cycle. Hence, activity lost during the reduction cycle is not restored. In contrast, sulfur that blocks Pt sites on the baseline material during the reduction cycle is subsequently oxidized and desorbs from the Pt, restoring the activity. However, some of the resulting SO3 reacts with the BaO to form BaSO4, and there is a partial loss of storage capacity.

The Spontaneously Hypertensive Rat: An Experimental Model of Sulfur Dioxide-Induced Airways Disease

Chronic obstructive pulmonary disease (COPD) is characterized by airway obstruction, inflammation, and mucus hypersecretion, features that are common in bronchitis, emphysema, and often asthma. However, current rodent models do not reflect this human disease. Because genetically predisposed spontaneously hypertensive (SH) rats display phenotypes such as systemic inflammation, hypercoagulation, oxidative stress, and suppressed immune function that are also apparent in COPD patients, we hypothesized that SH rat may offer a better model of experimental bronchitis. We, therefore, exposed SH and commonly used Sprague Dawley (SD) rats (male, 13- to 15-weeks old) to 0, 250, or 350 ppm sulfur dioxide (SO(2)), 5 h/day for 4 consecutive days to induce airway injury. SO(2) caused dose-dependent changes in breathing parameters in both strains with SH rats being slightly more affected than SD rats. Increases in bronchoalveolar lavage fluid (BALF) total cells and neutrophilic inflammation were dose dependent and significantly greater in SH than in SD rats. The recovery was incomplete at 4 days following SO(2) exposure in SH rats. Pulmonary protein leakage was modest in either strain, but lactate dehydrogenase and N-acetyl glucosaminidase activity were increased in BALF of SH rats. Airway pathology and morphometric evaluation of mucin demonstrated significantly greater impact of SO(2) in SH than in SD rats. Baseline differences in lung gene expression pattern suggested marked immune dysregulation, oxidative stress, impairment of cell signaling, and fatty acid metabolism in SH rats. SO(2) effects on these genes were more pronounced in SH than in SD rats. Thus, SO(2) exposure in SH rats may yield a relevant experimental model of bronchitis.

Study of Meteorological Aspects and Urban Concentration of SO2 in Atmospheric Environment of La Plata, Argentina

This article presents and discusses SO(2) (ppbv) concentration measurements combined with meteorological data (mainly wind speed and direction) for a five-year campaign (1996 to 2000), in a site near an oil refinery plant close to the city of La Plata and surroundings (aprox. 740.000 inh.), considered one of the six most affected cities by air pollution in the country. Since there is no monitoring network in the area, the obtained results should be considered as medium term accumulated data that enables to determine trends by analyzing together gas concentrations and meteorological parameters. Preliminary characterization of the behaviour of the predominant winds of the region in relation with potential atmospheric gas pollutants from seasonal wind roses is possible to carry out from the data. These results are complemented with monthly averaged SO(2) measurements. In particular, for year 2000, pollutant roses were determined which enable predictions about contamination emission sources. As a general result we can state that there is a clear increase in annual SO(2) concentration and that the selected site should be considered as a key site for future survey monitoring network deployment. Annual SO(2) average concentration and prevailing seasonal winds determined in this work, together with the potential health impact of SO(2) reveals the need for a comprehensive and systematic study involving particulate matter an other basic pollutant gases.

Sulfur dioxide: Relevance of toxic and nutritional effects for Chinese cabbage

Shoots of Chinese cabbage formed a sink for atmospheric SO 2 and there was a linear relation between the rate of uptake and the atmospheric SO 2 level (0.03–1.4 μl l −1). Chinese cabbage appeared to be rather susceptible to the toxic effects of SO 2. Shoot biomass production was reduced upon prolonged exposure to ≥0.1 μl l −1 SO 2. SO 2 exposure resulted in an increase in the content of SO 4 2−, water-soluble non-protein thiols and total S in the shoot with atmospheric levels of ≥0.1 μl l −1, however, the ratio of organic S to total S remained unaffected. The organic N content was not affected by SO 2 exposure. The impact of SO 2 on Chinese cabbage seemed to be ambiguous, since the SO 2 taken up by the shoot also could be used as S source for growth and was even beneficial when SO 4 2− supply to the root was deprived. A 5-day exposure of plants to 0.06–0.18 μl l −1 SO 2 resulted in an alleviation of the development of S deficiency symptoms upon SO 4 2− deprivation. An atmospheric SO 2 level as low as 0.06 μl l −1 appeared to be sufficient to cover the plants’ S requirement for growth. The N/S ratio was much lower in SO 4 2-sufficient plants than in SO 4 2-deprived plants in both shoot and root. Exposure of SO 4 2−-deprived plants to SO 2 resulted in a decrease in the N/S ratio of the shoot but did not affect that of the root. The N/S ratio of the shoot decreased with increasing SO 2 levels as a consequence of the increase in total S and SO 4 2− content. In contrast, the N/S ratio of shoot and root of SO 4 2−-sufficient plants was not significantly affected upon exposure to 0.06–0.18 μl l −1 SO 2. SO 4 2− deprivation resulted in a shift in shoot to root biomass partitioning during growth in favor of root production, which was not rapidly alleviated when SO 2 was used as S source for growth. Its possible consequences for Chinese cabbage growing under field conditions are evaluated.

Investigation of the efficiency of existing air pollution monitoring sites in the state of Kuwait

The use of mathematical modelling for investigation of the efficiency of existing monitoring sites for the impact of SO 2 emissions from power stations in the state of Kuwait is described. The Industrial Source Complex Short Term (ISCST3) model is utilised to obtain the spatial and temporal variations of SO 2 over residential areas. Statistical comparison between the 50 highest daily measured and predicted SO 2 concentrations at six monitoring sites shows that the model is capable of generating results with accuracy of 60–94%. An important conclusion of this work is that the existing locations of the Kuwait-EPA monitoring stations are not suitable for measuring the actual impact of SO 2. Therefore, there is a need for relocation of these sites to register the highest levels of SO 2 emitted from the current power stations in the state of Kuwait.

Inhibition effect of SO2 on NOx and VOCs during the photodegradation of synchronous indoor air pollutants at parts per billion (ppb) level by TiO2

Sulfur-containing compounds are well-known catalyst poisons. To evaluate the feasibility of photocatalytic technology for indoor air purification, a typical atmospheric SO2 concentration of 200 parts per billion (ppb) was selected. In order to further evaluate the impact of SO2 on the photocatalytic activity of other typical indoor air pollutants, SO2 was co-injected with 200ppb NO and 20ppb benzene, toluene, ethylbenzene, and o-xylene (BTEX) using TiO2 (P-25) as photocatalyst coated on a glass fiber filter. A concurrent photodegradation of SO2 with NO, SO2 with BTEX, and SO2 with NO and BTEX was also conducted. Results showed that no photodegradation of SO2 was found. However, the blank glass fiber filter adsorbed more than 75% of the SO2. The conversion of NO decreased by 8% and the generation of NO2 increased by 10% with the presence of SO2. A similar inhibition effect was found on the photodegradation of BTEX with the presence of SO2. The presence of SO2 decreased the conversion of BTEX by more than 10%. Ion chromatography analysis on the TiO2 glass fiber filter showed that sulfate ion was formed from the adsorption of SO2. The formation of sulfate ion inhibited the formation of nitrate ion, which increased the generation of NO2. It is suggested that the inhibition effect of SO2 is due to the sulfate ion competing with the pollutant for adsorption sites on TiO2. The promotion effect of NO on BTEX was also reduced by the presence of SO2.

Surface impact induced fragmentation and charging of neat and mixed clusters of SO 2 and H 2O

Cluster impact induced charge separation was studied with neat and mixed clusters of SO 2 and H 2O impinging at hyperthermal velocities on a SiO x target held at different temperatures. At 750 K, impact of SO 2 clusters produces positively and negatively charged cluster fragments of the form [(SO 2) n −K,Na] + and [(SO 2) m −SO 2] − which is explained in terms of the known cluster-impact induced pickup of alkali surface adsorbates. The high sensitivity of this channel promises applications for the analysis of alkali surface contaminations. The dominant fragments observed during the impact of binary SO 2/H 2O clusters at the same target temperature were [(H 2O) n −H] + and [(SO 2) p (H 2O) q −HSO 3] −, which indicates an intracluster proton transfer reaction. Similar fragments were also detected as minor spectral progressions during the surface impact of neat SO 2 clusters at a target temperature of 380 K. This is interpreted in terms of an impact-induced pickup of water surface adsorbates into the neat sulfur dioxide cluster during the surface collision. Upon impact of neat water clusters, fragment ions of the form [(H 2O) n −H] + and [(H 2O) q −OH] − are observed, which can be explained in terms of the autoprotolysis reaction in bulk water.

Large igneous provinces and mass extinctions

Comparing the timing of mass extinctions with the formation age of large igneous provinces reveals a close correspondence in five cases, but previous claims that all such provinces coincide with extinction events are unduly optimistic. The best correlation occurs for four consecutive mid-Phanerozoic examples, namely the end-Guadalupian extinction/Emeishan flood basalts, the end-Permian extinction/Siberian Traps, the end-Triassic extinction/central Atlantic volcanism and the early Toarcian extinction/Karoo Traps. Curiously, the onset of eruptions slightly post-dates the main phase of extinctions in these examples. Of the seven post-Karoo provinces, only the Deccan Traps coincide with a mass extinction, but in this case, the nature of the biotic crisis is best reconciled with the effects of a major bolide impact. Intraoceanic volcanism may also be implicated in a relatively minor end-Cenomanian extinction crisis, although once again the main phase of volcanism occurs after the crisis. The link between large igneous province formation and extinctions remains enigmatic; volume of extrusives and extinction intensity are unrelated and neither is there any apparent relationship with the rapidity of province formation. Violence of eruptions (proportions of pyroclastics) also appears unimportant. Six out of 11 provinces coincide with episodes of global warming and marine anoxia/dysoxia, a relationship that suggests that volcanic CO 2 emissions may have an important effect on global climate. Conversely, there is little, if any, geological evidence for cooling associated with continental flood basalt eruptions suggesting little long-term impact of SO 2 emissions. Large carbon isotope excursions are associated with some extinction events and intervals of flood basalt eruption but these are too great to be accounted for by the release of volcanic CO 2 alone. Thus, voluminous volcanism may in some circumstances trigger calamitous global environmental changes (runaway greenhouses), perhaps by causing the dissociation of gas hydrates. The variable efficiency of global carbon sinks during volcanic episodes may be an important control on environmental effects and may explain why the eruption of some vast igneous provinces, such as the Paraná–Etendeka Traps, have little perceptible climatic impact.

Absorption/desorption of NOx process on perovskites: impact of SO2 on the storage capacity of BaSnO3 and strategy to develop thioresistance

The formation of species when BaSnO3 is exposed to SO2 under a variety of conditions is reported and discussed. Direct contact with 25ppm SO2 during 15 cycles of Lean–Burn operation leads to the complete loss of NOx absorption capacity owing to the formation of stable and irreversible bulk-like sulphates identified by FT-IR (990, 1060, 1125 and 1190cm−1) and TGA–MS. When both NO2 and SO2 are present, the competition between the formation of nitrate and sulphate favours the latter, leading eventually to deactivation. If the catalyst is pre-nitrated before exposure to SO2, the co-existence of nitrates and sulphates between 100 and 300°C is possible and improved sulphur tolerance is obtained.