Formation Of SO Research Articles

Arsenic removal from coal-fired flue gas by metal oxides modified wood chips coke: Experimental and DFT study

Coal-fired power plant is one of the main anthropogenic arsenic emission sources, where gaseous As2O3 is the main form in the flue gas to the atmosphere. In this work, a series of metal salt impregnated wood chips coke (Me-BC) were developed for As2O3 removal from flue gas, which selected BC with low cost and high arsenic removal potential as the carrier and modified by metal nitrate through impregnation and pyrolysis to load active components. The results indicate that As2O3 removal performance of the Me-BC obeys Fe-BC-0.15 > BC > Al-BC-0.15 > Ca-BC-0.15 > K-BC-0.15 under the basic flue gas composition (N2 + O2 + CO2) at 150℃, with the highest As2O3 removal capacity (141.5 μg/g) and efficiency (92.9%) for Fe-BC-0.15 compared to 92.4 μg/g, 60.7% of the BC. The arsenic removal ability of Fe-BC firstly increases and then decreases as Fe(NO3)3 impregnation concentration increases with its maximum value at 0.15 mol/L. Generally, the NO has a significant inhibitory effect on the arsenic removal of Fe-BC-0.15 due to consumption of surface active oxygen species by or the competitive adsorption between NO and As2O3. Low-concentration SO2 complete with As2O3 for the adsorption on active sites while high-concentration SO2 will promote SO3 and Oβ formation which benefits for As2O3 capture. Overall, Oɑ and Oβ and C-O play an important promoting role in the arsenic removal by adsorbents. DFT calculations indicates that C-O have strongest adsorption energy for As2O3 among oxygen-containing functional groups. The adsorption of SO2 and NO on naked BC and BC-O is easier than As2O3. Both Fe2O3 and BC play an important role in the arsenic removal process by Fe-BC-0.15.

Bioleaching residue-introduced thermal activation-leaching of refractory chalcopyrite

Currently, about 10% − 20% of the world's copper production comes from bioleaching processes. On the one hand, the bioleaching residues accumulated over the years require harmless treatment. On the other hand, the gradual depletion of secondary copper sulphide ores has made refractory chalcopyrite the most important copper resource, but bioleaching of chalcopyrite has not yet achieved commercial success, and more efficient and cost-effective technologies need to be developed. To this end, the bioleaching residue-introduced thermal activation-leaching of chalcopyrite was investigated for the first time in this work. As the main or typical components of bioleaching residues, elemental sulphur, jarosite and covellite were selected as additives to chalcopyrite, which were thermally activated at 375 °C, 475 °C and 575 °C. The solubility of the activated products was evaluated using three leaching media including deionised water, dilute H2SO4 (pH 1.85) and 10 wt% H2SO4, with a solid/liquid ratio of 0.5 g/10 mL. The leaching results showed that the highest Cu recoveries of the different groups were 96.10% (with jarosite added), 93.10% (with all three components added), 90.30% (with elemental sulphur added), 88.40% (chalcopyrite alone) and 88.00% (with covellite added). An improved Cu recovery of 5.32% with a significantly reduced iron leaching rate of 71.24% was obtained when all three additives were present. Combining the results of XRD, SEM, EDS, TG-DSC and predominance area diagram analysis, the sulphation mechanism of chalcopyrite induced by the thermal decomposition intermediates KFe(SO4)2 and K2SO4 was proposed and the favourable sulphation atmosphere attributed to the formation of SO2 and SO3 was discussed. In addition, high-purity hematite was shown to be the main phase of the final solid product, achieving the simultaneous valuable and harmless transformation of the bioleaching residue.

Effect of ammonia co-firing ratio on the formation of condensable particulate matter in pollutants during coal/ammonia co-combustion

In this paper, the influence of zero-carbon ammonia co-firing ratio during coal/ammonia combustion on the generation of condensable particulate matter(CPM) was investigated. 0%, 10%, 20%, 30% and 50% ammonia were mixed into the coal combustion according to the energy input ratio to collect the discharged CPM and FPM in laboratory and the composition of flue gas was tested. The results show that mixing ammonia into coal combustion had little impact on the total concentration of CPM. The main reason is that the ammonia co-firing into coal can promote the formation of inorganic matter of CPM, and the concentration of organic matter decreased. The mass of FPM decreased when the proportion of ammonia is increased. In addition, co-combustion of ammonia inhibited the formation of SO2 that discharge to the atmosphere. The main reason is that the mass of coal decreased with the increasing of calorific value of ammonia. In addition, the co-firing of ammonia can promote the conversion of S to FPM and CPM. The reason is that H came from NH3 burned to produce water vapor, then water vapor can combine with sulfur dioxide. Peak areas of some organic substances are drawn with the variety of ammonia co-firing ratio. Most of the substances in alkanes are N-alkanes. The conclusions in this paper are of great significance to the further understanding of migration and transformation of pollutants under the influence of ammonia co-combustion. In addition, the research in this paper provides a theoretical basis for achieving the goal of carbon neutrality.

Characterization of Products from Catalytic Hydrothermal Carbonization of Animal Manure

This paper presents hydrothermal carbonization (HTC) of cow and pig manure in an acidic environment and compares the results with HTC performed without acid. HTC experiments were carried out at 170 °C for 10 min. The presence of an acid increased the extent of carbonization and energy densification for both types of manure. The heating value of the hydrochar was increased by an amount ranging from 9–21%, with sulfuric acid having a greater impact than acetic acid. The increased fuel densification may provide for more economic use as a fuel. Both acids increased the leaching of ionic species including PO4, Ca, K, Mg, and Fe. The results demonstrated conversion greater than 90% of total phosphorous to phosphate in hydrothermal conditions. HTC with sulfuric acid resulted in increased nitrogen leaching for both types of manure and resulted in the generation of ammonia. Further analysis of the aqueous products signified the formation of acetic acid, furfural, and 3-aminopyrazine 1-oxide compounds for the sulfuric acid-catalyzed hydrothermal treatment. Analysis of the residual gas confirmed the presence of a trace amount of H2S, NO2, and SO2 formation. The addition of sulfuric acid increased NO2 significantly. Finally, detailed mass balances are presented for carbon and macronutrients (NPK).

Investigation on the mechanism of Nb and Si co-doping on low SO3 generation from V-based catalyst during NH3-SCR process

Generally, SO3 tends to be formed in the process of selective catalytic reduction (SCR), and SO3 has negative effects on atmospheric environmental production and the safe operation of coal-fired power plants. In this study, a series of Nb and Si codoped V-based catalysts were prepared via the impregnation method, and Nb and Si species were applied to reduce the SO3 generation ratio from the catalyst. Moreover, the controlled condensation method was used to collect the SO3, which formed during the NH3-SCR reaction process. The results indicated that the Nb and Si codoped catalysts exhibited the best NO reduction performance with the lowest SO3 generation ratio. The SO3 generation ratio and the NO conversion ratio for the VW2NbTi-10Si catalyst were 0.39% and 92%, respectively. The physicochemical properties of the catalysts were analysed by a series of characterization techniques. The X-ray diffraction (XRD) results revealed that the Nb and Si species could inhibit the crystallization of TiO2, and the X-ray photoelectron spectroscopy (XPS) results indicated that Nb and Si could decrease the ratio of Oα and V5+ on the surface of the catalyst. From the CO2 and NH3 temperature programmed desorption (CO2 and NH3-TPD) results, the Nb and Si species could reduce the number of alkaline sites on the catalyst surface, and the Si species could significantly enhance the acidity of weak and strong acid sites over the catalyst. Combined with the results of N2-adsorption and desorption, CO2-TPD, H2 temperature programmed reduction (H2-TPR) and XPS experiments, the addition of Nb and Si species was beneficial to inhibiting the adsorption and oxidation of SO2 on the surface of catalysts, resulting in a significant decrease in SO3 emissions. Therefore, in-situ diffuse reflective infrared Fourier transform spectroscopy (DRIFTS) analysis demonstrated that the Nb and Si species could restrict the reaction between SO2 and V species, decreasing the formation of the intermediate product VOSO4. Furthermore, the enhancement of reaction temperature and NH3 volumetric fraction would significantly promote the formation of SO3. However, the variations in the volumetric fraction of O2 and NO expressed ignorable effects on the SO3 generation ratio.

The Detection of Hot Molecular Cores in the Small Magellanic Cloud

We report the first detection of hot molecular cores in the Small Magellanic Cloud (SMC), a nearby dwarf galaxy with 0.2 solar metallicity. We observed two high-mass young stellar objects in the SMC with the Atacama Large Millimeter/submillimeter Array and detected emission lines of CO, HCO+, H13CO+, SiO, H2CO, CH3OH, SO, and SO2. Compact hot-core regions are traced by SO2, whose spatial extent is about 0.1 pc, and the gas temperature is higher than 100 K based on the rotation diagram analysis. In contrast, CH3OH, a classical hot-core tracer, is dominated by extended (∼0.2–0.3 pc) components in both sources, and the gas temperature is estimated to be K for one source. Protostellar outflows are also detected from both sources as high-velocity components of CO. The metallicity-scaled abundances of SO2 in hot cores are comparable among the SMC, Large Magellanic Cloud (LMC), and Galactic sources, suggesting that the chemical reactions leading to SO2 formation would be regulated by elemental abundances. On the other hand, CH3OH shows a large abundance variation within SMC and LMC hot cores. The diversity in the initial condition of star formation (e.g., degree of shielding, local radiation field strength) may lead to the large abundance variation of organic molecules in hot cores. This work, in conjunction with previous hot-core studies in the LMC and outer/inner Galaxy, suggests that the formation of a hot core would be a common phenomenon during high-mass star formation across the metallicity range of 0.2–1 Z⊙. High-excitation SO2 lines will be a useful hot-core tracer in the low-metallicity environments of the SMC and LMC.

High-temperature sulfur capture by a Mn-Mo sorbent: An investigation of regeneration conditions and SO2 formation and prevention

The regeneration performance of a solid sorbent (alumina-supported 15Mn8Mo) for sulfur capture at high temperature has been studied. The regeneration of the sulfided sorbent was performed by oxidizing at different temperatures (400 – 800 °C) and O2concentrations (0.21 – 21 %). Temperature had a larger impact on the regeneration thanO2concentration. An unwanted side reaction during sulfur capture is SO2formation. Two pathways to SO2formation were identified, either via sulfate formation and decomposition or via oxidation of H2S. A new regeneration method which avoids SO2formation and achieves low residual H2S level in the gas phase involves adding an extra H2pre-reduction step between the regular O2-regeneration and the subsequent sorption step, i.e., a O2– H2regeneration. The stability of the sorbent was verified by 10 repeated sorption/regeneration cycles, with the sorbent regenerated either via the oxidative method or the new O2– H2regeneration method.

Treatment of gaseous streams polluted with H2S: Comparison of electrolytic and electro-Fenton assisted absorption processes

H2S is a gaseous compound that contributes to air pollution. In this work, the electrochemical oxidation treatment of gaseous streams polluted with H2S is evaluated using a jet mixer and electrochemical cell device, in which the performance of electrolytic and electro-Fenton assisted absorption processes are compared. Results demonstrate the feasibility of both processes to remove H2S, reaching coulombic efficiencies of nearly 100% in the electrolytic assisted absorption, and 70–80% in the electro-Fenton assisted absorption. Aqueous solutions containing phosphate salts as electrolyte were found to be suitable as absorbents for the process. Efficiency in the cathodic production of H2O2 in these solutions using the experimental device was found to be as high as 32.8% (1.184 mgH2O2/min) at 12 °C and atmospheric pressure. Sequential formation of SO2 and SO3 is obtained by the oxidation of H2S contained in the gas. These species are hydrolysed, and a part remained in the absorbent as SO32− and SO42−, while the rest is dragged in the outlet gas. SO3 production is promoted by electrolytic assisted absorption and polysulphides by the electro-Fenton technology. Low concentrations of elemental sulphur are detected in the solid suspensions formed during the process.

Interactions of co-firing coal gangue and high sodium coal: Combustion characteristics and emission behaviors of polluting gases

To promote the utilization of coal gangue (CG) as alternative fuels for heat or power generation, this work investigated the interactions between a CG (denoted as XJG) and a high sodium coal (HSQ) during co-combustion as well as the evolution behaviors of gaseous pollutants (SO2 and NO). Results show that co-firing HSQ with less than 30 % XJG does not deteriorate its combustion performance. Synergistic conversion is observed due to the complementarity of the fuels in volatile matter, fixed carbon, ash content and reactivity. Moreover, alkali and alkaline-earth metals promote co-firing and lower activation energy of combustion from 100 to 70 kJ/mol. Both SO2 and NO are evolved in two stages during co-combustion as described by the shrinking core model and 3D-diffusion model. NO is reduced by char and CO and the reduction is catalyzed by the alkaline species(especially CaO) in ash. SO2 emission behavior is significantly varied by the competitive reactions of calcium oxide with silica/alumina species. Overall, NO is decreased by about 10 % relatively at 900–1100 °C while SO2 is notably enhanced at 1000 °C by 23 %. The mechanism of formation and reaction of SO2 and NO are proposed. These results provide useful reference for clean utilization of CG and controlling of polluting gas emission, thus boosting sustainable development of energy, ecology and environment.

Feedstock flexible numerical analysis of sewage sludge gasification

Sewage sludge properties vary with the origin and treatment method of the wastewater. When converting the sewage sludge thermally for material and energy recovery, these properties affect the composition of the products and the efficiency of the process. Rotary kiln gasifiers can handle these variations in the raw materials. For further development, process integration, optimization of the process, upscaling, and industrial application, it is helpful to understand and describe the impact of the sewage sludge properties on operating parameters and product quality. This work analyses the impact of sewage sludge properties numerically using detailed chemistry and the surrogate approach. Sewage sludge is described using woody biomass components, sugars, lipids, proteins, inorganic species, moisture, and ash. The stochastic reactor model (SRM) is used to model the gasification process. In contrast to ideal reactors, stochastic reactors allow for resolving inhomogeneity. Hence, the predicted gas composition results from local temperature and available oxygen. For the analysis, temperature, airflow rate, and fuel properties, i.e., the amount and composition of volatiles, including fuel-bonded nitrogen and sulfur, and the moisture level are varied. Their results are analysed regarding the produced gas composition, emission precursor formation, and cold gas efficiency of the process. The highest efficiencies are found for temperatures of 1223 K and rich conditions. High concentrations of methane and hydrogen accompany this maximum. However, the producer gas’s highest heating value is found at low temperatures thanks to the presence of small hydrocarbons. Furthermore, a high volatile amount and a dry feedstock favour methane and carbon monoxide formation. The hydrogen concentration is found to be sensitive to the moisture content and is the highest at 30%. The cold gas efficiency is predicted to depend strongly on the feedstock and varies for the same operating conditions up to 60%. With increasing fuel-bonded nitrogen and sulfur content, the concentrations of NO and SO2 formation and their precursors increase, respectively. The released ammonia leads to significantly reducing emitted NO through the ThermalDeNOx mechanism. Overall, the generated maps provide a detailed insight in species formation and allows for the prediction of process parameters sensitive to the sewage sludge properties.

Thermodynamic analysis of the processes of interaction and formation of nitrogen and sulfur compounds during the combustion of Kansk-Achinsk coals

The paper identifies and examines the mechanisms of the interaction of nitrogen and sulfur compounds during the combustion of Kansk-Achinsk coals (KAC). The researches were carried out on the basis of the model of extreme intermediate states (MEIS) developed at The L.A. Melentiev Institute of Energy Systems and presented in a number of publications. The KAC of various deposits characterized by different content of sulfur and mineral components are considered. On the basis of computational experiments, the influence of alkaline elements of the mineral part (Ca, Na, K) on the formation of NO and SO2 was determined. The temperature interval of the transition of condensed calcium sulfate to sulfur dioxide during the combustion of KAC of various (including new) deposits has been clarified. Based on the modeling of thermodynamic states, the results of industrial tests are considered, in which inversely proportional dependences of NO and SO2 on the resulting calcium sulfate have been recorded. These dependences can be explained by multidirectional energy flows during the formation of CaSO4/c and NOx.

Bifunctional electrolyte additive with redox mediation and capacity contribution for sulfur cathode in aqueous Zn-S batteries

Aqueous zinc-sulfur (Zn-S) battery has attracted much attention due to the ultrahigh theoretical capacity of S (1675 mA h g−1). Nevertheless, its lifespan is far from satisfactory owing to the sluggish reaction kinetics for ZnS conversion to S, and the formation of irreversible by-product of SO42− during charging. Herein, a novel bifunctional electrolyte additive thiourea (TU) was introduced to solve the above problems. It has been found that TU can undergo reversible redox reactions during cycles, which not only enhances the reversibility between ZnS and S but also contributes to extra capacities. Based on the ex-situ FTIR and XPS characterization, in combination with the electrochemical performance of thiourea and its derivatives, the influential mechanism of TU on the S@KB electrode was proposed. Its negative centers and positive centers of the intermediates can interact with ZnS to weaken the Zn-S bonds to improve the electrochemical dynamics. Simultaneously, the carbonium ions in the intermediate of TU show strong reactivity to ZnS so that the formation of SO42− can be inhibited. As a result, the S@KB electrode shows excellent cyclic performance with 763.7 mA h g−1 capacity after 300 cycles at 5 A/g, corresponding to a low decay rate of only 0.11 % per cycle. This work provides a promising electrolyte additive and an effective strategy to improve the reaction kinetics and cycle stability of Zn-S batteries.

Sulfur Ion Implantations Into Condensed CO2: Implications for Europa

AbstractThe ubiquity of sulfur ions within the Jovian magnetosphere has led to suggestions that the implantation of these ions into the surface of Europa may lead to the formation of SO2. However, previous studies on the implantation of sulfur ions into H2O ice (the dominant species on the Europan surface) have failed to detect SO2 formation. Other studies concerned with similar implantations into CO2 ice, which is also known to exist on Europa, have offered seemingly conflicting results. In this letter, we describe the results of a study on the implantation of 290 keV S+ ions into condensed CO2 at 20 and 70 K. Our results demonstrate that SO2 is observed after implantation at 20 K, but not at the Europa‐relevant temperature of 70 K. We conclude that this process is likely not a reasonable mechanism for SO2 formation on Europa, and that other mechanisms should be explored instead.

Synthesis, structure, and Mössbauer spectroscopic studies on the heat-induced solid-phase redox reactions of hexakis(urea-O)iron(III) peroxodisulfate

Anhydrous hexakis(urea-O)iron(III)]peroxydisulfate ([Fe(urea-O)6]2(S2O8)3 (compound 1), and its deuterated form were prepared and characterized with single-crystal X-ray diffraction and spectroscopic (IR, Raman, UV, and Mössbauer) methods. Six crystallographically different urea ligands coordinate via their oxygen in a propeller-like arrangement to iron(III) forming a distorted octahedral complex cation. The octahedral arrangement of the complex cation and its packing with two crystallographically different persulfate anions is stabilized by extended intramolecular (N–H⋯O = C) and intermolecular (N–H⋯O–S) hydrogen bonds. The two types of peroxydisulfate anions form different kinds and numbers of hydrogen bonds with the neighboring [hexakis(urea-O)6iron(III)]3+ cations. There are spectroscopically six kinds of urea and three kinds (2 + 1) of persulfate ions in compound 1, thus to distinguish the overlapping bands belonging to internal and external vibrational modes, deuteration of compound 1 and low-temperature Raman measurements were also carried out, and the bands belonging to the vibrational modes of urea and persulfate ions have been assigned. The thermal decomposition of compound 1 was followed by TG-MS and DSC methods in oxidative and inert atmospheres as well. The decomposition starts at 130 °C in inert atmosphere with oxidation of a small part of urea (~ 1 molecule), which supports the heat demand of the transformation of the remaining urea into ammonia and biuret/isocyanate. The next step of decomposition is the oxidation of ammonia into N2 along with the formation of SO2 (from sulfite). The main solid product proved to be (NH4)3Fe(SO4)3 in air. In inert atmosphere, some iron(II) compound also formed. The thermal decomposition of (NH4)3Fe(SO4)3 via NH4Fe(SO4)2 formation resulted in α-Fe2O3. The decomposition pathway of NH4Fe(SO4)2, however, depends on the experimental conditions. NH4Fe(SO4)2 transforms into Fe2(SO4)3, N2, H2O, and SO2 at 400 °C, thus the precursor of α-Fe2O3 is Fe2(SO4)3. Above 400 °C (at isotherm heating), however, the reduction of iron(III) centers was also observed. FeSO4 formed in 27 and 75% at 420 and 490 °C, respectively. FeSO4 also turns into α-Fe2O3 and SO2 on further heating.Graphical abstract

Coal-Scenedesmus Microalgae Co-Firing in a Fixed Bed Combustion Reactor: A Study on CO2, SO2 and NOx Emissions and Ash

This study investigated the effect of coal–Scenedesmus microalgae (with blending ratios of 100:0 (coal), 95:5 (Coalgae® 5%), 90:10 (Coalgae® 10%), 85:15 (Coalgae® 15%) and 80:20 (Coalgae® 20%)) on combustion temperature, mass loss, the formation of CO2, SO2 and NOx gases, and ash content under constant atmospheric air flow. Coalgae® refers to a material formed after blending coal and microalgae. The results showed that NOx came mainly from Coalgae® 10% and 15%, and this observation could be attributed to a variable air concentration level (O2 level) in the environment that could influence NOx during the combustion process, irrespective of the blending ratios. CO2 emission reductions (12%, 17%, 21% and 29%) and SO2 emission reductions (3%, 12%, 16% and 19%) increased with the increasing coal-microalgae blending ratio (Coalgae® 5–20%), respectively. Bubble-like morphology was observed in the ash particles of coal–microalgae blends through SEM, while the TEM confirmed the formation of carbon-based sheets and graphitic-based nanocomposites influenced by the microalgae amounts. Ash residues of the coal–microalgae blends contained high amounts of fluxing compounds (Fe2O3, K2O, CaO and MgO), which resulted in an increased base/acid ratio from 0.189 (coal) to 0.568 (Coalgae® 20%). Based on the above findings, the co-firing of coal–Scenedesmus microalgae led to a reduction in CO2, SO2, and NOx emissions. As such, lower Coalgae® blends can be considered as an alternative fuel in any coal-driven process for energy generation.

Allocation of SO2 emission rights in city agglomerations considering cross-border transmission of pollutants: A new network DEA model

Currently SO2 emission rights are allocated without considering the cross-border transmission characteristics of pollutants, and the allocation scheme cannot reflect the fact that air pollutant overflows in space. In this paper, the WRF (Weather Research and Forecasting Model)-CMAQ (Community Multiscale Air Quality) is combined with the data envelopment analysis (DEA) allocation model for the first time, and a two-stage (Stage-1: SO2 formation, Stage-2: SO2 treatment) network DEA allocation model is proposed with the SO2 spatial transmission taken as the intermediate output or input index between decision-making units. Based on the principles of efficiency, economic protection and fairness, the model is applied to the study of SO2 emission rights allocation in the Yangtze River Delta city agglomeration with high homogeneity in China. The results show that: (1) When the weight coefficient (α1) in stage-1 is 0.7, 0.8 or 0.9, the per capita relative deprivation coefficient (PRDC) of each decision-making unit (DMU) is less than 0.5 in the allocation scheme, indicating that our scheme can be used as a reference to allocate emission rights in the Yangtze River Delta city agglomeration. (2) With great robustness and universality, our allocation model allows decision-makers to adjust the GDP constraint coefficient and the weight coefficients in the two stages according to their preferences, so as to obtain the optimal allocation results. The model proposed in this paper can help decision-makers to formulate effective policies to reduce pollutant emission, and promote energy conservation & emission reduction and coordinate environmental governance in regions of city agglomerations.

UV absorption spectrum of monochlorodimethyl sulfide (CH3SCH2Cl)

Monochlorodimethyl sulfide (CH3SCH2Cl, MCDMS) is a trace gas thought to be formed in the marine environment via the reaction of Cl2 with dimethyl sulfide (DMS, CH3SCH3) with implications for the temporal and spatial production of SO2 and sulfate aerosol formation. In this study, the room temperature UV absorption spectrum of MCDMS in the 200–330 nm wavelength region was measured. The spectrum measured in this work differs significantly in the long-wavelength actinic region, >295 nm, from that reported previously by Copeland et al. (Environ. Sci. Technol., 2014, 48, 1557–1565). On the basis of the present results, the MCDMS first-order tropospheric photolysis rate coefficient is a factor of ∼250 less than reported in Copeland et al. The diurnally averaged MCDMS photolysis lifetime is estimated to be ∼125 days at ground level for Summer mid-latitude conditions over the ocean. UV photolysis is, most likely, a minor gas-phase degradation pathway for MCDMS compared to its OH radical and Cl-atom reactive losses.

Comparison of the formation characteristics of condensable particulate matter from the combustion of three solid fuels

Exploring the formation characteristics of condensable particulate matter (CPM) and guiding its directional regulation are beneficial. Therefore, coal, pine, and sewage sludge fuels were combusted, and the differences in the contents and compositions of the generated CPM were analyzed. The results show that the CPM concentrations generated by the combustion of the three fuels are different. Maximum total CPM concentration (19.79 mg/m3) was generated by sewage sludge. The CPM concentrations generated by coal and pine were 14.1 mg/m3 and 7.57 mg/m3, respectively. The SO42− content generated by combusting sewage sludge was considerably higher than that by coal, and the SO42− content generated by the pine was the lowest. The high nitrogen content in sewage sludge influenced the SO42− content, and the oxides in the filterable particulate matter affected the formation of SO3. The NH4+ content in the CPM generated by the sewage sludge was the highest among the three fuels and is more related to the nitrogen content in fuels. The differences in the compositions and properties of the fuels lead to the differences in the CPM generated. Hydrocarbons accounted for the largest proportion of the organic fractions of CPM generated by the three solid fuels. The emission concentration of CPM can be reduced by removing N, S, and Cl from the fuel and adjusting the combustion atmosphere. This study lays the foundation for understanding the formation mechanisms of CPM.

Experimental and density functional study of sulfur trioxide formation catalyzed by hematite in pressure oxy-combustion

Pressurized oxy-combustion is one of the most promising carbon capture technologies which could reduce global CO2 emission. SO3 is one of the main conventional pollutants and might be produced in large concentration in pressurized oxy-combustion than air combustion, posing risks to the environment and safe operation of boiler. However, no research has been conducted on SO3 catalytic formation in pressurized oxy-combustion, despite the fact that SO3 heterogeneous formation accelerated by hematite is more significant than homogeneous formation. Consequently, it is critical to understand SO3 catalytic formation in pressurized oxy-combustion. In this study, SO3 homogeneous and heterogeneous formation catalyzed by hematite were explored at 1 bar and 4 bar in a pressured fixed bed reactor. Temperature, pressure, and the addition of NO were discussed in this study. Density functional study method was employed to further elucidate the hematite catalysis mechanism. The findings show that hematite can catalyze the SO3 formation, but the catalytic effect weakens at high pressure. The inclusion of NO could enhance SO3 catalytic formation. Density functional study indicated that changing the main gas from N2 to CO2 has little impact on SO2 and O2 adsorption and subsequent SO3 production. SO3 adsorption becomes more stable with increasing O atom coverage, making SO3 desorption more difficult. Since NO has a lower adsorption energy than SO2 and O2, it has less effect on catalysis, however, NO2 formation could act as a strong catalyst and can enhance SO3 formation. This study could provide a better understanding of how the atmosphere and pressure influence SO3 heterogenous formation in pressured oxy-combustion.

Effects of Adding Calcined Dolomite and Mill Scale to Sinter Mix on the Formation of NO and SO2 in Iron Ore Sintering Process

Effects of Adding Calcined Dolomite and Mill Scale to Sinter Mix on the Formation of NO and SO2 in Iron Ore Sintering Process