Presence Of SO2 Research Articles

Particle Formation from Photooxidation of αpinene, Limonene, and Myrcene.

We present measurements of the effect of first-generation secondary organic aerosol (SOA) material on the growth of ∼10 nanometer diameter seed particles composed of sulfuric acid and water. Experiments were performed in an atmospheric pressure, vertically aligned flow reactor where OH was produced from HONO photolysis in the presence of either SO2 or a monoterpene. For typical conditions, organic compounds at ∼300 ppbv are exposed to photooxidation for a time of ∼80 s at a [OH] of about 6 × 106 cm-3: thus, oxidation products have minimal OH exposure. The measured size changes of the sulfuric acid seed particles can then be attributed to the uptake of first-generation products. Along with descriptions of the apparatus and the procedure, the analysis to obtain SOA yields by comparing them to growth with H2SO4(g) is detailed. Results from photooxidation experiments of αpinene, limonene, and myrcene give SOA yields of 0.040, 0.084, and 0.16, respectively. These SOA yields roughly double with each addition of a double bond to the compound. The αpinene and limonene results are in accord with the results of many previous SOA experiments, while the myrcene SOA yield stands alone. Photooxidation of myrcene also led to significant nucleation, and the species responsible is comparable to H2SO4 at a 35% relative humidity in its nucleation capability.

Effects of slag on the degradation mechanism of ordinary Portland cement-calcium aluminate cement-gypsum ternary binder under the multiple erosive ions

It is of great significance for the repair of concrete in marine engineering to reveal the effects of slag on the degradation mechanism of ordinary Portland cement-calcium aluminate cement-gypsum (OPC-CAC-C S-) ternary binder under the combined action of multiple erosive ions and dry-wet cycles. In this study, mechanical property, mass change, Cl− content, hydration products and morphology were investigated. The results show that the compressive strength, the Cl− erosion resistance and the stability of hydration products of the ternary binder were significantly improved by the partial substitution of slag, especially in the erosion environment containing SO42− and Mg2+. As the aluminum phase was sufficient when slag added, the combination rate of Cl− improved by the presence of SO42−, while slightly decreased by Mg2+ at early ages. Compared with corrosive solution including only Cl−, the presence of SO42− and Mg2+ reduced the generation of Friedel's salt. Moreover, the stability of ettringite was obviously enhanced by SO42−, while slightly reduced by the additional Mg2+ in corrosive solution.

Degradation of sulfamethazine by vacuum ultraviolet-activated sulfate radical-advanced oxidation: efficacy, mechanism and influences of water constituents

• VUV/PMS enhanced the SMT removal in greywater than UV/PMS. • HO• was the most effective radical for SMT degradation, followed by SO 4 • − . • VUV/PMS enhanced the oxidative degradation rather than photolysis. • SMT degradation pathways and intermediates toxicology for VUV(UV)/PMS were analysed. In-situ collection, purification and reuse of indoor greywater of public buildings or household is an effective way to save water resources. Refractory organic micropollutants in greywater, such as antibiotic sulfamethazine (SMT), can be potentially removed by sulfate radical-advanced oxidation process (SR-AOP) in the presence of peroxymonosulfate (PMS) or peroxydisulfate. Herein, vacuum ultraviolet (VUV) with irradiation at 185 nm and 254 nm activating PMS was systematically investigated in terms of degradation efficacy and influences of water constituents, and the contribution of photolysis and radical oxidative species was determined. We show that SMT removal efficiency and PMS photolysis efficiency of VUV/PMS were 2.2-fold and 1.45-fold compared to UV/PMS, respectively, and VUV/PMS reached a higher mineralization. The main active radicals of VUV/PMS were HO•, SO 4 •− , and •O 2 − . Compared to UV/PMS, VUV/PMS resulted in a higher proportion of oxidative degradation and a lower proportion of photolysis. Higher SMT concentrations competed for absorption of VUV or UV-generated photons with H 2 O and PMS molecules, resulting in a less efficient reaction. VUV/PMS was more efficient at lower initial SMT concentrations and had an optimal pH of 5. The presence of SO 4 2− slightly accelerated degradation performance while HCO 3 − and NO 3 − inhibited both processes; the inhibitory effect of HCO 3 − and NO 3 − on VUV/PMS are more significant than on UV/PMS. In contrast, the presence of Cl − had no significant effect on each process. In total, 13 intermediates of SMT were identified and four degradation pathways were proposed. VUV/PMS had an advantage over UV/PMS in removing the produced harmful and toxic intermediates. Furthermore, VUV/PMS could remove SMT from real water matrix more effectively than UV/PMS. Generally, the results demonstrate the potential of VUV to displace UV for more effective in-situ treatment of indoor greywater.

No detection of SO2, H2S, or OCS in the atmosphere of Mars from the first two Martian years of observations from TGO/ACS

Context. The detection of sulphur species in the Martian atmosphere would be a strong indicator of volcanic outgassing from the surface of Mars. Aims. We wish to establish the presence of SO2, H2S, or OCS in the Martian atmosphere or determine upper limits on their concentration in the absence of a detection. Methods. We perform a comprehensive analysis of solar occultation data from the mid-infrared channel of the Atmospheric Chemistry Suite instrument, on board the ExoMars Trace Gas Orbiter, obtained during Martian years 34 and 35. Results. For the most optimal sensitivity conditions, we determine 1σ upper limits of SO2 at 20 ppbv, H2S at 15 ppbv, and OCS at 0.4 ppbv; the last value is lower than any previous upper limits imposed on OCS in the literature. We find no evidence of any of these species above a 3σ confidence threshold. We therefore infer that passive volcanic outgassing of SO2 must be below 2 ktons day−1.

Understanding the dual-acting of iron and sulfur dioxide over Mn-Fe/AC catalysts for low-temperature SCR of NO

Poor N2 selectivity and low SO2-tolerant are dominated weaknesses for low-temperature selective catalytic reduction of NO with NH3 (NH3-SCR) catalysts, which must be overcome for practical applications. Herein, a Mn-Fe mixed catalyst supported on active carbon (Mn-Fe/AC) for low-temperature NH3-SCR of NO was prepared, and the influence of SO2 on this process was also studied. Both iron and sulfur dioxide exhibited a dual-acting over Mn-Fe/AC catalyst for NH3-SCR of NO. Sulfur dioxide had two effects when SO2 was introduced in the feed gas under SCR conditions, including inhibiting the low temperature activity of the catalysts and improving N2 selectivity which exceeded 90% during the whole testing temperature. The introduction of SO2 could promote the formation of NH2NO which was the main intermediate and then decomposed into N2. Fe species in Mn-Fe/AC catalyst could improve N2 selectivity. In the presence of SO2, it showed considerable SO2 resistance compared to Mn/AC catalyst. On the one hand, iron species improved the selectivity through forming new active sites promoting the formation of NH2NO and suppressing the free NO3- generation. On the other hand, iron existing in Mn-Fe/AC catalyst could decrease the amount of sulfur species adsorbent and SO2 oxidation, thereby exhibiting better SO2 resistance.

Structural control for inhibiting SO2 adsorption in porous MnCe nanowire aerogel catalysts for low-temperature NH3-SCR

The presence of SO2 in industrial flue gases will cause permanent deactivation of the catalyst active centre. Therefore, an effective method to improve the SO2 resistance of manganese-based catalysts at low temperatures is urgently needed. In this work, a hierarchical porous nanowire structure catalyst was designed by the in situ self-assembly method to inhibit SO2 adsorption. This hierarchical porous nanowire aerogel catalyst with great BET surface area and surface acidity exhibited NOx conversion above 90% at 100–400 °C. Notably, the NOx conversion of the MnCe-N catalyst was almost not inhibited by SO2 (250 ppm) compared to the 33% decrease of the MnCe-P catalyst. On the MnCe-P catalyst, SO2 has strong competitive adsorption with NH3 and NO, and the stronger adsorption capacity of SO2 inhibits the adsorption activation of the reaction gas and hinders the reaction proceeding through the L-H mechanism. Meanwhile, a large quantity of sulfate is formed on the catalyst surface, which prevents the active centre to participate in the redox reaction. The structure of nanowires enhances the number of acid sites, facilitates the adsorption and activation of NH3, and effectively inhibits the adsorption of SO2 on the MnCe-N catalyst. Fewer sulfate species are generated and difficult to deposit and aggregate on the catalyst surface, as a result, the active centre is less affected by sulfate species. The stable adsorption of NH3-related species ensures reliable reaction on MnCe-N through the E-R mechanism. This work emphasizes the importance of hierarchically porous structures in improving the NH3-SCR performance and SO2 resistance of monolithic catalysts, and provides new insights into the design of highly efficient and stable catalytic materials.

Coordinative sulfur site over flower-structured MoS2 for efficient elemental mercury uptake from coal-fired flue gas

Metal sulfides have recently been considered as promising options for mercury removal owing to their large number of active sulfur sites, environmental friendliness, morphological diversity, resistance to high concentrations of sulfur dioxide, high activity and low cost. Herein, due to the strong affinity between Hg and S, MoS2 was selected to adsorb Hg0 from coal-fired flue gas in power plants. The mercury removal experiments indicate that compared with ZnS, CuS and SnS, MoS2 has the strongest ability to remove elemental mercury. The effects of different adsorption temperatures and different gas components (O2, NO, SO2) and other reaction conditions on the removal performance of Hg0 were further discussed. It was found that the presence of O2, NO or SO2 had no significant effect on the removal of Hg0 by MoS2. Thanks to the abundant edge unsaturated sulfur sites, the flower-like MoS2 not only exhibits good sulfur resistance, but also has excellent long-term stable properties. The equilibrium adsorption capacity of MoS2 is 54.308 mg g−1, and the initial adsorption rate is 66.79 μg g−1 min−1. It is better than most metal sulfide adsorbents, in which the equilibrium adsorption capacity is 24 times that of sulfur modified activated carbon (S-AC), and the initial adsorption rate is 133 times that of S-AC. Moreover, density functional theory (DFT) calculations proved that elemental mercury was chemically adsorbed on surface of MoS2 nanosheets, forming stable HgS. This work can promote the proper design and innovation of adsorbent materials and achieve fruitful treatment of environmental pollutants.

Amino-acid modulated hierarchical In/H-Beta zeolites for selective catalytic reduction of NO with CH4 in the presence of H2O and SO2.

Selective catalytic reduction of NO with CH4 (CH4-SCR) has been studied over a series of amino-acid mediated hierarchical beta zeolites with indium exchange. Amino acid mesoporogens greatly affect the NO reduction (DeNOx) efficiency of In/H-Beta catalysts. Mesoporous In/H-Beta-P synthesized using proline exhibits the highest NOx removal efficiency of 40% in excess oxygen and poisonous SO2 and H2O, 10% higher than our previously optimized In/H-Beta catalyst using commercial beta zeolites with a similar Si/Al ratio. Analyses using XRD, N2 adsorption-desorption, EPR, SEM, TEM, EDX, ICP, 27Al and 29Si MAS NMR, XPS, H2-TPR, NH3-TPD, and Py-IR reveal that amino acids promote beta crystallization, modulate zeolite acid sites and surface oxygen species, and generate hierarchical pore architectures without affecting the Si/Al ratio, indium content, and percentage of the active InO+ species. The mosaic-structured In/H-Beta-P exhibits the strongest Brønsted acidity and surface labile oxygen which enhance the oxyindium interaction with the zeolite framework, promoting CH4-SCR activity. The strong acidity, surface active oxygen species, and mesopores lead to excellent stability of the In/H-Beta-P catalyst in the presence of SO2 and H2O, withstanding several catalytic DeNOx cycles under harsh reaction conditions.

High‐sulfidation epithermal–porphyry transition in the Kumbokarno Prospect, Trenggalek district, East Java, Indonesia: Constraints from mineralogy, fluid inclusion, and sulfur isotope studies

AbstractAn indication of high‐sulfidation epithermal–porphyry transition was observed in the Kumbokarno prospect, East Java, Indonesia. The prospect is composed of two Middle Miocene intrusions with tonalitic and dioritic compositions. Tonalite, the main host‐rock was subjected to argillic, advanced argillic, and vuggy quartz alteration, whereas the juxtaposing diorite was subjected to peripheral propylitic alteration. Three types of vein exist in the research area, which are massive quartz, comb quartz, and stockwork vein. In addition, supergene alteration represented by goethite and hematite pervasively superimposed both the hydrothermal alteration and mineralization. Fluid inclusion petrography and microthermometry analysis on three types of quartz veins distinguished primary fluid inclusions into two groups, that is, V30 group composed of vapor (30 vol%)–liquid (70 vol%), and the second group V30H group composed of vapor (30 vol%)–halite (30 vol%)–liquid (40 vol%). The homogenization temperatures of both the groups show a similar range of ca. 350–480°C, but the V30H group has significantly higher salinity (35–50 wt% NaCl eq.) compared to the V30 group (10–20 wt% NaCl eq.). In terms of the vein types, the massive quartz vein has the highest homogenization temperatures, followed by the comb quartz vein and lastly the stockwork veins. The presence of alunite and its sulfur isotope compositions, δ34S = 19.6 (σ = 2.1‰), indicate acidic pH and presence of SO42− in the hydrothermal fluids. The prospect is an intrusion‐centered magmatic‐hydrothermal system reflecting the porphyry‐epithermal transition. The fluid inclusions with high homogenization temperatures up to 480°C and high salinity up to 50 wt% NaCl eq. also support the transition of porphyry to high‐sulfidation epithermal mineralization. The presence of two different types of primary fluid inclusions suggests that boiling process occurred and separated the original magmatic fluid into the liquid and vapor phases. More, this fluid underwent dilution and mixing with meteoric waters. The migration of both the fluids were likely unrelated to the formation of the advanced argillic–argillic alteration halo because the quartz veins cut across this alteration. The prospect was later subjected to intensive weathering process that altered most of the sulfides into iron oxides and hydroxides. Small amounts of copper and minor gold were detected, especially in the iron oxides and hydroxides ones with colloform and bladed textures. The Kumbokarno prospect evidences the potential for high‐sulfidation to porphyry deposits at the Southern Mountain Arc, Indonesia.

Surface solvation of Martian salt analogues at low relative humidities.

Salt aerosols play important roles in many processes related to atmospheric chemistry and the climate systems on both Earth and Mars. Complicated and still poorly understood processes occur on the salt surfaces when interacting with water vapor. In this study, ambient pressure X-ray photoelectron spectroscopy (APXPS) is used to characterize the surface chemical environment of Martian salt analogues originating from saline lakes and playas, as well as their responses to varying relative humidities. Generally, APXPS shows similar ionic compositions to those observed by ion chromatography (IC). However, XPS is a surface-sensitive method while IC is bulk-sensitive and differences are observed for species that preferentially partition to the surface or the bulk. Element-selective surface enhancement of Cl− is observed, likely caused by the presence of SO42−. In addition, Mg2+ is concentrated on the surface while Na+ is relatively depleted in the surface layer. Hence, the cations (Na+ and Mg2+) and the anions (Cl− and SO42−) show competitive correlations. At elevated relative humidity (RH), no major spectral changes were observed in the XPS results, except for the growth of an oxygen component originating from condensed H2O. Near-edge X-ray absorption fine structure (NEXAFS) measurements show that the magnesium and sodium spectra are sensitive to the presence of water, and the results imply that the surface is fully solvated already at RH = 5%. The surface solvation is also fully reversible as the RH is reduced. No major differences are observed between sample types and sample locations, indicating that the salts originated from saline lakes commonly have solvated surfaces under the environmental conditions on Earth.

Adsorption of SO2 on ZnO Nanowires Using Activated Carbon by Langmuir Adsorption Isotherm

Sulphur dioxide (SO2) is one of the contaminants present in the environment. They are the by-product of combustion, industrial pollution, generation of electricity, etc. After some reactions in the atmosphere, SO2 changes its form and produces acid rain. The presence of SO2 needs to be detected to combat its effect. Many nanosensors are designed to detect the presence of SO2 in the environment. Zinc oxide (ZnO) nanowire sensor is one of those sensors used for SO2 detection. The size, structure, cost-effectiveness, and unique properties made it a choice for sensing purposes. Activated carbon is another compound that has porous substances that helps the adsorbate to settle down on the large surface area of its adsorbent surfaces. Combining the nature of ZnO nanowire and activated carbon, the adsorption of SO2 can be increased. This paper proposes a novel technique involving the activated carbon in the ZnO nanowire sensor to increase its SO2 adsorption capacity and rate. The Langmuir adsorption isotherm is used to find the adsorption efficiency between the solid adsorbent and gaseous adsorbate. MATLAB simulation was carried out for the proposed work in which it is seen that the novel method shows 33.34% efficiency in terms of SO2 adsorption capacity. The response of the proposed sensor shows 23% efficiency over time. The analysis shows that the usage of the activated carbon increases the adsorbent site for SO2 adsorbate to adsorb on the surfaces. According to the adsorption quantity, SO2 level has been obtained in the environment.

V2O5/CeO2 catalysts for catalytic oxidation of hydrogen sulfide to sulfur and water at low temperature

In order to comply with the international standards imposed on sulfur gas emissions into the atmosphere, certain treatments are necessary. Consequently, it is becoming more and more essential to recover and treat these gaseous effluents before their emission into the atmosphere in order to produce energy and further protect the environment. The activity of the catalysts used for the partial oxidation of these gases to produce energy through the conversion of hydrogen and other sulfur products. Thus, the possibility of producing of dihydrogen and the simultaneous elimination of highly toxic contaminants is attractive. The simultaneous production of sulfur and water by catalytic oxidation of H2S in the presence of SO2 is studied under different operating conditions. The experiments will be carried out in a test bench, which was built in our laboratory with the aim of studying all the stages of the catalytic H2S oxidation.

Highly Active and Stable Cuxfey/Ac-H Catalysts with Cufe2o4 for No Reduction by Co in the Presence of H2o and So2 Under Regeneration Gas

Highly Active and Stable Cuxfey/Ac-H Catalysts with Cufe2o4 for No Reduction by Co in the Presence of H2o and So2 Under Regeneration Gas

Study on SO2 and Cl2 sensor application of 2D PbSe based on first principles calculations.

In this paper, we use 2D PbSe to design a gas sensor to monitor the presence of SO2 and Cl2. We use first principles to verify the feasibility of this material, such as atomic structure, band gap, differential charge density and Bader charge. The results show that 2D PbSe can distinctly adsorb SO2 and Cl2. Furthermore, the adsorption of SO2 and Cl2 will affect the electronic structure of 2D PbSe, and some electrons in the PbSe are transferred to gas atoms. The band gap of the system after adsorption is smaller than that of the PbSe before adsorption. The band gap of single layer PbSe decreases by 41.92% after SO2 adsorption and 60.61% after Cl2 adsorption. The band gap of multi-layer PbSe decreases by 72.97% after SO2 adsorption and 43.24% after Cl2 adsorption. This shows that single layer PbSe is more sensitive to Cl2 and multi-layer PbSe is more sensitive to SO2. It provides a potential possibility for designing gas sensors for SO2 and Cl2 based on 2D PbSe.

Development of an SO2 indicator label applied to shrimp

Sulfiting agents are added to crustaceans products to prolong their shelf life. However, depending on the concentration, these agents can be toxic to consumers due to the presence of SO2. In this context, a colorimetric indicator label based on starch and iodine was developed to detect SO2 in shrimp, showing whether the product is safe or not for consumers. The incorporation of iodine into the starch matrix resulted in labels with a smooth and homogeneous surface, and reduced water solubility from 9.26% to around 0.12%. In both in vitro and shrimp paste test, a visual detection response was observed in the label containing 0.02% of iodine when evaluated in the presence of 100 to 160 ppm of SO2, with ΔE* values greater than 5 (can be identifiable by the human eye). Therefore, the elaborated label showed potential as an economical and simple method to detect SO2 concentration in shrimp-based foods.

Promotional effect of phosphorus addition on improving the SO2 resistance of V2O5-MoO3/TiO2 catalyst for NH3-SCR of NO

The oxidation of SO2 into SO3 promote the formation of NH4HSO4 (ABS), which can cover surface active sites catalyst, and then leading to the decrease of NH3-SCR De-NOx activity. In this work, phosphorus species were loaded on the V2O5-MoO3/TiO2 De-NOx catalyst to enhance its SO2 resistance via inhibiting the SO2/SO3 conversion. XRD and N2-adsorption results showed that phosphorus has little impact on the structure and pore property of the catalyst. The results of XPS, H2-TPR, and NH3-TPD analyses illustrated that suitable amount of phosphorus (1%) increases the content of polymeric vanadate and chemisorbed oxygen (Oα) of the catalyst, which is benefit to the SCR process. Phosphorus species decreases the SO2 absorbability and SO2 oxidation activity of V-Mo-P/Ti catalysts, thus it exhibits higher NH3-SCR activity than that of the P-free catalyst at presence of SO2 due to the lower SO2/SO3 conversion and fewer amount of NH4HSO4 deposition.

Yeast and Filamentous Fungi Microbial Communities in Organic Red Grape Juice: Effect of Vintage, Maturity Stage, SO2, and Bioprotection.

Changes are currently being made to winemaking processes to reduce chemical inputs [particularly sulfur dioxide (SO2)] and adapt to consumer demand. In this study, yeast growth and fungal diversity were investigated in merlot during the prefermentary stages of a winemaking process without addition of SO2. Different factors were considered, in a two-year study: vintage, maturity level and bioprotection by the adding yeast as an alternative to SO2. The population of the target species was monitored by quantitative-PCR, and yeast and filamentous fungi diversity was determined by 18S rDNA metabarcoding. A gradual decrease of the α-diversity during the maceration process was highlighted. Maturity level played a significant role in yeast and fungal abundance, which was lower at advanced maturity, while vintage had a strong impact on Hanseniaspora spp. population level and abundance. The presence of SO2 altered the abundance of yeast and filamentous fungi, but not their nature. The absence of sulfiting led to an unexpected reduction in diversity compared to the presence of SO2, which might result from the occupation of the niche by certain dominant species, namely Hanseniaspora spp. Inoculation of the grape juice with non-Saccharomyces yeast resulted in a decrease in the abundance of filamentous fungi generally associated with a decline in grape must quality. Lower abundance and niche occupation by bioprotection agents were observed at the overripened stage, thus suggesting that doses applied should be reconsidered at advanced maturity. Our study confirmed the bioprotective role of Metschnikowia pulcherrima and Torulaspora delbrueckii in a context of vinification without sulfites.

Novel Counteraction Effect of H2O and SO2 toward HCl on the Chemical Adsorption of Gaseous Hg0 onto Sulfureted HPW/γ-Fe2O3 at Low Temperatures: Mechanism and Its Application in Hg0 Recovery from Coal-Fired Flue Gas.

In this work, sulfureted phosphotungstic acid-grafted γ-Fe2O3 (HPW/γ-Fe2O3) was investigated as a regenerable monolithic sorbent to recover gaseous Hg0 upstream of wet flue gas desulfurizations (FGDs), and the effects of HCl, SO2, and H2O on the chemical adsorption of Hg0 onto sulfureted HPW/γ-Fe2O3 were investigated with Hg balance analysis and kinetic analysis. Hg0 conversion over sulfureted HPW/γ-Fe2O3 was remarkably promoted in the presence of HCl, and most Hg0 was catalytically oxidized to HgCl2. Moreover, the chemical adsorption of Hg0 was notably restrained as the key species for Hg0 transformation to HgS (i.e., S22-) was rapidly oxidized by Cl*. However, the effect of HCl on Hg0 conversion over sulfureted HPW/γ-Fe2O3 was almost counteracted by H2O and SO2 as they competed with physically adsorbed Hg0 and S22- for the consumption of Cl*. Therefore, the chemical adsorption of Hg0 onto sulfureted HPW/γ-Fe2O3 in the presence of SO2 and H2O was slightly inhibited by HCl, and only a small amount of HgCl2 was formed. Moreover, sulfureted HPW/γ-Fe2O3 exhibited a moderate ability for gaseous HgCl2 adsorption. As a result, sulfureted HPW/γ-Fe2O3 showed excellent performance in recovering Hg0 from the flue gas upstream of the FGDs for the centralized control of Hg0 emitted from coal-fired plants.

Day-to-day variability of upper troposphere and lower stratosphere temperature in response to Taal volcanic eruption inferred from COSMIC-2 RO measurements

For the first time after 43 years of its previous eruption in 1977, the Taal volcano in the Philippines (14°N, 120°.59E) erupted in the afternoon of 12 January 2020. Due to the strong anticyclonic circulation in the upper troposphere (~150 hPa), the resultant volcanic ash and sulfur dioxide (SO2) were transported to the downwind tropical central Pacific Ocean within a few days after the initial eruption. In this study, day-to-day variability of upper troposphere lower stratosphere (UTLS) temperature in response to the Taal volcanic eruption event over the source region (±5o latitude and longitude around the volcano) and the downwind Pacific region (10-20oN, 160-180°E) is delineated by using the recently launched Constellation Observing System for Meteorology, Ionosphere, and Climate (COSMIC)-2 radio occultation (RO) data. The daily mean temperature over the source and downwind regions were compared with the background long-term January mean temperature (obtained from 2007 to 2019 COSMIC-1 RO data) over the respective regions. Significant positive temperature anomalies in the lower stratosphere are evident over the source (between 12 and 14 January) and downwind (between 14 and 19 January) regions after the eruption. These positive anomalies may be due to the association of absorption and local radiative heating by volcanic aerosols. The Ozone Monitoring Instrument (OMI) measurements clearly show the presence of SO2 in the UTLS region. The presence of sulfate aerosols in the UTLS region a few days after eruption is also supported by the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP) images. Furthermore, we also describe the temperature structure near the volcano and away from the volcano and found a quite different structure in the UTLS region. A significant temperature inversion at ~15 km altitude is evident near the volcano, whereas it is noticed at ~16 km away from the volcano. In conclusion, in line with the previous studies, the present study provides further insights to the UTLS temperature in response to volcanic eruptions.

Revealing the Synergistic Deactivation Mechanism of Hydrothermal Aging and SO2 Poisoning on Cu/SSZ-13 under SCR Condition.

In real-world application, Cu/SSZ-13 simultaneously suffers severe deactivation from hydrothermal aging and SO2 poisoning during the periodic regeneration of diesel particulate filter (DPF). Herein, we first investigated the synergistic deactivation mechanism of hydrothermal aging and SO2 poisoning on Cu/SSZ-13 under SCR condition. Hydrothermal aging alone induces more severe degradation of selective catalytic reduction (SCR) performance than SO2 poisoning alone, while the presence of SO2 during hydrothermal aging causes further worse SCR performance compared with hydrothermal aging alone. Hydrothermal aging not only damages Si-OH-Al sites, particularly in four-membered ring (4MR) of the CHA cage, but also brings the conversion of ZCuOH, leading to the formation of inactive CuO/CuAlOx species. By contrast, SO2 poisoning alone is more prone to promote the transformation of ZCuOH to Z2Cu. Synergistic deactivation of hydrothermal aging and SO2 poisoning would exacerbate the damage of Si-OH-Al sites and then the formation of CuO/CuAlOx species. These results are expected to assist the knowledge-based catalyst design for diesel aftertreatment applications.