Effect Of Sulfur Addition Research Articles

Effect of sulfur addition on glass-forming ability, structure and thermal stability of multicomponent silicate-phosphate glasses

Effect of sulfur addition on glass-forming ability, structure and thermal stability of multicomponent silicate-phosphate glasses

Hydrodeoxygenation of lignin-derived diphenyl ether on in situ prepared NiMoS catalyst: The effect of sulfur addition on catalyst formation

The catalytic activity of unsupported NiMoS catalysts prepared in situ by thermal decomposition of the [(CH3)3S]2Ni(MoS4)2 precursor was studied in the course of diphenyl ether hydrodeoxygenation. The resulting catalysts were characterized using the transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). It was demonstrated that the diphenyl ether conversion naturally decreases with a decrease in the precursor loading. The effect of changes in the amount of the added sulfiding agent on the morphological and structural features of the formed catalysts was studied. It was found that reducing the amount of elemental sulfur from 2.5 to 0.5 wt% results in a more active sulfide NiMo catalyst, which is explained by an increase in the dispersion of the active phase particles from 0.24 to 0.34. A route of diphenyl ether hydrodeoxygenation on unsupported NiMoS catalysts was studied and suggested by varying the reaction time and hydrogen pressure in the system.

Influence of sulfur addition on the glass formation, phase transformation and mechanical properties of Cu50Zr50 alloy

In this work, a thorough study on the effects of sulfur-addition in the Cu50Zr50 glass-forming system was conducted using laboratory-based X-ray diffraction (XRD), synchrotron-based high-energy XRD (HESXRD), differential scanning calorimetry, and uniaxial compression testing. We report that the glass-forming ability (GFA), thermal stability, phase transformation sequence during heating and cooling, as well as the mechanical properties of the Cu50Zr50 system are highly sensitive to the sulfur concentration. Proper addition of sulfur can not only stabilize the B2-CuZr phase, but also enhances the GFA of the system. This enables the formation of BMG composites that solely contain a B2 phase, which results in a combination of high strength and substantial plastic strain under compressive loading. The total strains of the newly developed BMG composites with sulfur contents of 0.5 and 1.0 at.% are as large as ∼10 at.%, exceeding the previously reported strains of the Cu50Zr50 BMG by far. These superior properties make the Cu-Zr-S BMG composites a promising candidate material for industrial applications. In addition, it is found that excessive addition of sulfur leads to the precipitation of the Cu10Zr7 phase upon cooling from the alloy melt and a sulfide phase during heating from the glassy state. HESXRD experiments suggest that the preferential bonding between Zr and S atoms could be the determining structural mechanism on the atomic scale, leading to the changing primary crystallization sequence for heating and cooling. The findings in this work further strengthen the high relevance of sulfur in alloy development and tuning of properties in BMGs, especially considering the low cost, good availability, and non-toxicity of sulfur in the relevant modifications.

Effect of sulfur addition and foliar spray of Super Docson nutrient solution on some vegetative growth and yield properties of two grape cultivars.

The study was conducted during the two growing seasons (2019 and 2020) on grape vines (Halawani and Kamali varieties) in the vine yard of the Department of Horticulture and Landscape Design- College of Agriculture- Tikrit University. The vines cultivated in 2016. The experiment was conducted with three factors, the first, is the varieties (Halawani and Kamali), the second is agricultural Sulfur (S) with three levels, (S0:, S1: 250 g. vine-1,and S2: 500 gm. vine-1) and the third factor is the spraying of “Super Docson” nutrient solution with three concentrations (P0 : spraying with distilled water, P1 : 1.2 ml. L-1 , P2 : 2.4 ml. L-1). The spraying was done in Early morning to until complete wetness. The experiment was carried out with the split plot system in Randomized Complete Block Design (RCBD). The varieties took the main plots, while the sulfur and nutrient treatments were randomly distributed on the sub plots, by three replications and the results showed That, the Halawani variety was excellence on Kamali in most studied traits, and which included (leaf area of vine(m2.vine -1) , main branch length(cm), leaf chlorophyll content, vine yield(kg) and total yield(tons.ha-1). And the results showed excellence at concentrate 2.4 ml. L-1 for nutrient and at level 500 g for sulfur in most studied traits.

Investigation of the reduction roasting of saprolite ores in the Caron process: effect of sulphur addition

ABSTRACT Laboratory studies have been undertaken to determine the mechanisms and kinetics of reactions occurring during the reduction roasting of saprolite ores with 1 wt% elemental sulphur addition. The reduction was undertaken using a 15%H2/85%N2 gas mixture at temperatures between 400 and 800°C; nickel was recovered by subsequent leaching in an ammoniacial aqueous solution. The effect of sulphur on dehydroxylation, reduction and sintering was investigated. Improvements in nickel recoveries were obtained when 1 wt% S was added to the nickel-bearing serpentine ore prior to the reduction roasting. Characterisation of the reduced and leached ore samples indicated that this improved Ni recovery with S addition is due to the formation of a leachable nickel sulphide phase, and the suppression of sintering and recrystallisation of the olivine phase formed at high reduction temperatures.

Effect of sulfur addition and nanocrystallization on the transport properties of lithium–vanadium–phosphate glasses

The glasses defined by the formula 37.5Li2O–25V2O5–37.5P2O5 mol% containing different sulfur (0, 10, 50 and 100 mol%) content were studied before and after nanocrystallization. X-ray diffraction and transmission electron micrograph of the heat treated samples indicated nanocrystals embedded in the glass matrix. The average crystallite size was found between 18 and 37 nm. Sulfur (S) behaved as a reducing agent for redox reaction during preparation of glass and affected the conductivity, i.e., the V4+–V5+ or V3+–V4+ion pairs increased with increasing S content and led to increasing conductivity of glasses. After creation of the nanocrystalline phase, S-free glass–ceramic nanocomposite exhibited improvement in electrical conductivity around three orders of magnitude than initial glass. This great improvement of electrical conductivity is related to increase in a concentration of V4+–V5+or V3+–V4+ ion pairs and also, forming of defective and well-conducting regions along the crystallite/glass interfaces. The decrease in electrical conductivity in the 50S glass–ceramic nanocomposite, which possessed the highest crystallite size, could be related to the increase of grain boundaries scattering because of the increasing crystallite size. The conduction was attributed to non-adiabatic small polaron hopping and mostly determined by hopping carrier mobility.

Effect of sulfur addition on the electrochemical performance of lithium‑vanadium-phosphate glasses as electrodes for energy storage devices

Glasses of the composition 37.5Li2O-25V2O5-37.5P2O5 mol% containing different sulfur (0, 10, 50, 100mol%) content were successfully synthesized and investigated as electrodes for electrochemical devices. Both galvanostatic charge/discharge (GCD) and cyclic voltammetry (CV) were performed to study of electrochemical properties. The results showed that glasses containing sulfur (S) exhibited a high performance, such as specific capacitance, energy density and power density, compared with the S-free glass. These properties increased with increasing of S content. The outstanding electrochemical performance of the glasses containing S can be attributed to the partial substitution of oxygen (O) atoms by S atoms. Since the radius of S ion is higher than O ion, this substitution can significantly enlarge the size of Li-ion transfer pathway. Besides, S ion has better polarization ability than O ion, thus weakens the interaction between Li ions and glass network. Therefore, the addition of S into oxide glasses may be an effective way to improve the performance of electrochemical devices electrodes.

Effects of sulfur addition on the wettability and corrosion resistance of Sn-0.7Cu lead-free solder

The effects of sulfur on the wettability of Sn-0.7Cu on Cu and on the corrosion behavior of Sn-0.7Cu in 3.5wt% NaCl solution were investigated. The results reveal that sulfur considerably improves the wettability of Sn-0.7Cu and the optimal sulfur content is 0.08wt%. SnS and SnSO4 phases form on the surface of the sulfur containing Sn-0.7Cu solder alloy after soldering characterized by XPS and XRD analysis. The addition of sulfur decreases the dross formation of the solder melt and the formation of SnO2 is inhibited. The potentiodynamic polarization tests show that the corrosion resistance of Sn-0.7Cu solder alloy is obviously enhanced by sulfur element. Analyses by SEM and XRD indicate that sulfur promotes the formation of the corrosion product, Sn3O(OH)2Cl2, on the surface of sulfur containing Sn-0.7Cu solder and it keeps the solder alloy from further corrosion.

Effects of Individual Use, Mixed Culture and Sulfur Addition on the Effectiveness of Nickel Laterite Ore Bioelaching with <i>Penicillium verruculosum</i> and <i>Galactomyces geotrichum</i>

The type of fungi used in fungal bioleaching influence the effectiveness of metals extraction due to the dissimilarity of each microorganism survival in environments with certain metals content. Several metals have prominent toxicities to certain type of fungi, which result in low metals extraction and leaching rate. In the present work, the influences of individual use of Penicillium verruculosum and Galactomyces geotrichum on the nickel extraction from Indonesian laterite ore are compared with the fungis mixed culture. The effect of sulfur addition in the mixed culture of Penicillium verruculosum and Galactomyces geotrichum on the sulfate ion formation was also investigated. Shake flask bioleaching assays have been performed in a medium growth of Indonesian food production waste over the course of 28 days. It was observed that mixed culture of Penicillium verruculosum and Galactomyces geotrichum has a higher effect in nickel extraction compared with the use of individual fungi for both saprolite and limonite ores. For saprolite ore, the fungi species of Galactomyces geotrichum demonstrated a greater nickel extraction than Penicillium verruculosum. In contrast, the extraction of nickel from limonite ore by Penicillium verruculosum was slightly more effective than Galactomyces geotrichum. The addition of elemental sulfur in the mixed culture was found to generate sulfate anion, having a significant increase in its concentration with time and decreasing solution pH within 28-day of incubation. The proportion of sulfur addition must be optimized in order to avoid ore surface passivation with the excess of sulfur. XRD analysis detected the presence of un-oxidized sulfur on surface of the leaching residues along with the biomass.

Effect of sulphur addition on roasting reduction of saprolitic nickel ores in CO/CO2 gas mixture

The objective of the work presented here was to examine the effect of sulphur on formation of high temperature recrystallised phases and further on reducibility of saprolitic nickel ores. The ores blending with FeS2 were first heated up to 1300°C to investigate the changes that might happen upon heating. As a result of sulphur addition, the exothermic peak, which is evidently associated with crystallisation of new phases, changed in size compared to ores without sulphur addition. In addition, the dehydration and recrystallisation of minerals was also observed to begin earlier, when sulphur is added in the ores. Additionally, the ores were reduced in CO/CO2 atmosphere at temperatures 750 and 900°C, in order to determine the effect of sulphur and temperature on the reducibility. Although sulphur prevented the formation of difficult reducible olivine, as well as pyroxene phases in Colombia-2 and Mirabela, the degree of removable oxygen was not enhanced when increasing the temperature from 750 to 900°C. This is due to low reduction of iron oxides to metalic iron at 900°C. The beneficial effect of sulphur on metallisation degree of the ores was observed by comparison of these results with the experiments carried out with the pellets without sulphur addition. The results obtained in this study clearly indicate that the reduction of saprolitic nickel ores appears to be strongly dependent on the characteristics of the starting materials, amount of additive used and the process conditions.

Effects of Sulfur Addition on the Formation of Inclusions and the Corrosion Behavior of Super Duplex Stainless Steels in Chloride Solutions of Different pH

Effects of sulfur addition on the formation of inclusions and the corrosion behavior of super duplex stainless steels in chloride solutions of different pH were investigated using potentiodynamic and potentiostatic polarization techniques. As sulfur content increased, the corrosion resistance decreased due to the formation of numerous manganese sulfides deteriorating the corrosion resistance. The solutions used for this study are NaCl and NaCl + HCl solutions. The corrosion behavior is dominated by the pitting corrosion in NaCl solution of pH 7 and by both uniform and pitting corrosion in NaCl + HCl solution of pH 1. The pitting corrosion of the alloys was initiated at all types of inclusions of manganese sulfides, manganese oxy-sulfides and manganese oxides and then propagated to the ferrite phases, and finally propagated to the austenite phases. [doi:10.2320/matertrans.M2012194]

Effect of sulphur on the performance of Rh–LaCoO3 based catalyst for tar conversion to syngas

The effect of sulphur addition on the catalytic activity of 1%Rh/Al2O3, LaCoO3/Al2O3 and 1%Rh–LaCoO3/Al2O3 catalysts in reforming of tar produced by biomass pyrolysis has been investigated by adding 20 or 200ppm H2S in a fixed bed reactor at 700°C using a S-free biomass slowly pyrolyzed. The catalysts have been characterized by ICP-MS and BET analyses. The poisoning effect of sulphur has been also studied by in situ DRIFT and TPR analyses. A very high sulphur exposure of the catalysts leads to the partial inhibition of the reforming properties related to the poisoning of dispersed rhodium sites. The LaCoO3 layer effectively preserves rhodium from sulphur poisoning in the 1%Rh–LaCoO3/Al2O3, the catalyst containing both phases showing mostly unchanged catalytic properties also upon 200ppm S-treatment under reaction conditions. The LaCoO3/Al2O3 catalyst shows reduced reforming properties coupled to an increase of cracking and total oxidation reactions associated to the partial destruction of the perovskite structure.

Effect of sulfur addition on the transport properties of semiconducting iron phosphate glasses

Transport properties and redox state of iron in glasses with compositions × S– (40 Fe 2O 3 – 60 P 2O 5)(mol%), where x = 0, 2,4,6 and 8 (mass%), were studied. The overall features of the XRD curves confirm the amorphous nature of the present glasses. Sulfur acted as a reducing agent for redox reaction during glass synthesis and affected the conductivity. Mössbauer spectral analyses revealed that the Fe 2+ ratio increases with increasing sulfur content. The high temperature above θ/2 ( θ D Debye temperature) dependence of conductivity could be qualitatively explained by the small polaron hopping model. The physical parameters obtained from the best fits of this model are found reasonable and consistent with the glass compositions. The conduction is confirmed to be due to adiabatic small polaron hopping of electrons between iron ions. The electron–phonon interaction coefficient γ p was large (21.42–26.26). The estimated hopping mobility was low, 1.12 × 10 −9–24.83 × 10 −9 cm 2 V −1 s −1 and increased with increasing S(mass%) content. Moreover, the low temperature (below θ/2) conductivity could not be explained either by Mott’s or greaves variable – range hopping model giving rise to unusually large values of the density of states at the Fermi level compared to those of transition metal oxide glasses. The conductivity of the present glasses was primarily determined by hopping carrier mobility.

Effect of sulfur addition and heat treatment on electrical conductivity of barium vanadate glasses containing iron

Six glass samples with a composition of 75V 2O 5 + 10BaO + 15Fe 2O 3 mol%, with 0, 10, 15, 20, and 25 wt% of sulfur were prepared by using a quenching method. The samples were measured by XRD, DSC, TEM, Mössbauer spectrometry and D.C. conductivity. The prepared samples were heat treated at temperature close to their crystallization temperatures for 1 h, and then the previous measurements were repeated. The results showed that the treatment process caused the formation of V 2O 5 and FeVO 4 nanocrystals with size of 17–25 nm dispersed in the glass matrix. The addition of sulfur reduced only the vanadium ions to V 4+, while it was found that iron ions were Fe 3+ only. D.C. conduction enhanced due to the small polaron or electron hopping from V 4+ to V 5+ ions. The heat treated samples exhibit much higher conductivity and much lower activation energy than the as-prepared glasses. The heat treated samples showed decreased thermal stability with the addition of sulfur. This considerable enhancement of electrical conductivity after nanocrystallization referred to the formation of extensive and dense network of electronic conduction paths which are situated between V 2O 5 nanocrystals and their surfaces.

The Effect of Sulfur on ZrO2-Based Biomass Gasification Gas Clean-Up Catalysts

The effect of sulfur on biomass gasification gas clean-up over ZrO2, Y2O3–ZrO2 and SiO2–ZrO2 catalysts was examined. Experiments were carried out at the temperature range of 600–900 °C with sulfur free and 100 ppm H2S containing simulated gasification gas feeds. A mixture of toluene and naphthalene was used as a tar model compound. Results revealed that the sulfur addition affected positively on the catalyst properties mainly at 600 and 700 °C: over Y2O3–ZrO2 and ZrO2 sulfur addition improved naphthalene and ammonia conversion. However, over SiO2–ZrO2 no clear effect with H2S addition was observed. The effect of sulfur addition on the catalyst properties was connected to the formation of SO2 from H2S when oxygen was available. The intensity of the sulfur effect increased with the Lewis basicity strength of the catalysts. This indicates that the sulfur adsorption has a role in generating new type of active sites and/or plays role in changing the redox properties of the zirconia. Since the biomass gasification gas contains usually significant amounts of H2S the sulfur tolerance of the zirconia based catalysts is a remarkable benefit.

Sulphur inhibition on the catalytic partial oxidation of methane over Rh-based monolith catalysts

The effect of sulphur addition (2–58 ppm) during the catalytic partial oxidation (CPO) of methane was investigated on Rh-based honeycomb catalysts tested under self-sustained high temperature condition. Both steady state and transient operation of the CPO reactor were investigated particularly with regard to poisoning/regeneration cycles and low temperature light-off phase. The analysis of products distribution in the effluent and a heat balance demonstrates that sulphur reversibly adsorbed on Rh selectively inhibits the steam reforming (SR) reaction path to syngas production. The extent of SR inhibition is greater when operating in air and diminishes at lower CH 4/O 2 feed ratios. The poisoning effect has been shown to be independent from the type of sulphur bearing compound and only indirectly affected by the type of catalyst support (La 2O 3 or SiO 2 stabilized alumina) through the value of Rh dispersion.

The effect of sulfur addition during the preparation of Co/Zn/TiO2 Fischer–Tropsch catalysts

The effect of sulfur on Co(10%)/Zn(x wt%)/TiO2 (x = 0 and 10) catalysts was investigated by TPR, XPS and Fischer–Tropsch (FT) reactor studies. The catalysts were prepared by impregnating different amounts of sulfur on Co(10%)/Zn(x wt%)/TiO2(x = 0 and 10) catalysts, using ammonium sulfide (20% in water) as a sulfur precursor. The effect of changing the order of impregnating cobalt, zinc and the sulfur precursor was also investigated. Based on the XPS results, impregnation of different amounts of sulfur on Co/Zn(x wt%)/TiO2(x = 0 and 10) catalysts indicated that sulfur preferentially reacts with cobalt and zinc instead of titania and blocked the active sites for FT reactions. These catalysts were inactive towards FT synthesis. Impregnating sulfur onto TiO2 prior to Co and Zn addition gave a Co/Zn/S/TiO2 catalyst that showed lower FT activity when compared to the unsulfided Co/Zn/TiO2 catalyst. XPS data revealed that sulfur reacted with titania and zinc as well as cobalt species prior to FT synthesis. A drastic increase in the C1–C11 selectivity and a decrease in the C12+ selectivities were observed for the sulfided catalysts (Co/Zn/S/TiO2 and Co/S/Zn/TiO2). The FT results correlated with the XPS and TPR results. The unsulfided catalysts with or without zinc produced higher molecular weight products (C12+) and less methane when compared to the sulfided catalysts. A model is proposed that explains the reactions of sulfur with Zn, Co and TiO2 and is consistent with the characterisation and activity results.

Effects of Transformation Stress and Deformation before Austenitization on Nucleation of Intragranular Bainite

Intragranular bainite is known to be effective to develop toughness greatly in steels. Effects of aging below eutectoid temperature before austenitization, the deformation before solution treatment and the duration of solution treatment on nucleation of intragranular bainite have been examined. In the austenite (γ) region where carbide pre-existed, the stress due to inverse transformation, ferrite (α) to γ, would be introduced into fine austenitized region with lower transus temperature to γ, resulting in the introduction of stable small-angle boundary at high temperatures acting as the nucleation site for intragranular bainite lath. Deformation of α by cold rolling before solution treatment enhances the nucleation of intragranular bainite, suggesting that the above γ region through the inverse transformation is easily deformed by the hardened neighboring α. In the deformed γ region, small-angle boundary would be more easily introduced, acting as nucleation site for intragranular bainite. Intragranular bainite lath grew and hardness decreased by prolonging the duration of solution treatment, indicating that transformation stress introduced by the pre-treatment was influenced by solution treatment. The effect of sulfur addition on formation of intragranular bainite was also analyzed.

Effect of Sulfur Addition on the Redox State of Iron in Iron Phosphate Glasses

Mossbauer, IR, and electrical conductivity were investigated in iron phosphate glasses, 40Fe2O3-60P2O5 (in mol%), containing sulfur ranging from 0 to 2, 4, 6, and 8 mass%. Sulfur proved to act as a reducing agent for the redox reaction during the glass preparation. Mossbauer spectroscopy was used in order to determine the relative fraction of Fe2+, i.e. Fe2+/Fe(total), isomer shift (δ), and quadrupole splitting (Δ). Mossbauer results revealed that the relative fraction of Fe2+ increases with an increasing sulfur content. Electrical conductivity showed a similar composition dependency as the fraction of Fe2+. These results indicate that higher electrical conductivity of sulfur-containing iron phosphate glasses is due to small polaron hopping (SPH) between iron atoms of different valance states, i.e., a step-by-step electron hopping from Fe2+ to Fe3+. IR spectra of these glasses are very similar to those of sulfur-free iron phosphate glasses, proving that the structure of sulfur-containing iron phosphate glasses is essentially the same as that of sulfur-free phosphate glasses.

Formation of Conjugated Linoleic Acids in Soybean Oil during Hydrogenation with a Nickel Catalyst As Affected by Sulfur Addition

The effects of sulfur addition on the formation of conjugated linoleic acid (CLA) isomers were studied during the hydrogenation of soybean oil with a nonselective type nickel catalyst. Sulfur addition greatly promoted CLA formation in soybean oil during hydrogenation. As the amount of sulfur increased to a certain level, the maximal quantity of CLA in soybean oil during hydrogenation increased greatly. However, further increase in sulfur addition above the certain level decreased CLA formation. The optimal sulfur level for the promotion of CLA formation differed greatly with the amount of nickel used. It was of great interest to find that the optimal ratio of sulfur to nickel for the promotion of CLA formation was always 0.06:1, regardless of the nickel amount used. At the same ratio of sulfur to nickel, higher nickel content induced significantly higher production of CLA (p < 0.05). At the optimal sulfur to nickel ratio, an increase in the nickel amount from 0.05 to 0.15% produced approximately 1.5 times higher levels of CLA during hydrogenation under the tested conditions. The CLA isomer compositions were greatly affected by both sulfur addition and amounts of nickel used for treatment. This is the first report of the possibility that the total quantity of CLA and their isomer composition could be manipulated during hydrogenation by controlling the amounts of sulfur and nickel.