Conversion Of Sulfide Research Articles

Adsorption and Separation of Ethyl Mercaptan from Methane by Hydroxyl Groups on the Surface of HTiNbO5-Nanosheets.

Adsorption and separation of light mercaptan (R-SH, R = C1-C4) from methane gas can effectively improve the utilization efficiency of methane and the resource conversion of organic sulfide. To further investigate the effects of composition and structural characteristics of laminates on desulfurization performance, in this paper, a two-dimensional (2D) HTiNbO5-nanosheet (HTiNbO5-NS) was constructed. In addition, the hydrogen-bonding interaction between the exposed hydroxyl active sites on the surface of HTiNbO5-NS and ethyl mercaptan (Et-SH) was constructed to realize the adsorption and separation of Et-SH from methane gas. The breakthrough adsorption capacity (Cap (BT)) of HTiNbO5-NS is 14.35 mg·g-1 in a micro fixed bed with a space velocity of 6000 h-1. The regeneration desulfurization rate (q) of the 10-cycle regeneration adsorption was ca. 96%. Furthermore, density functional theory (DFT) calculation results show that the S atoms of Et-SH and HTiNbO5-NS with the terminal hydroxyl and bridge hydroxyl have electron cloud covering to form the hydrogen-bonding interaction. In addition, the formation details of this hydrogen-bond interaction are discussed. The effects of Ti on the microstructure, hydroxyl acid, hydroxyl content, surface area, and pore volume of nanosheets were studied to explain the reasons for the differences in the properties of the two kinds of nanosheets. This work broadens the design of 2D niobium-based efficient adsorbents for R-SH based on hydrogen-bonding interaction and is helpful to enrich the application of the hydrogen-bonding interaction.

Study on antimony cake as a technogenic raw material for the production of antimony oxides

In the process of hydrometallurgical and pyrometallurgical production of antimony at the Kadamzhai antimony plant of the Kyrgyz Republic, large-tonnage waste was generated: tailing sand, matte, slag, off-balance ore, cakes, furnace fragments, and electrolytes in salt warehouses. The waste cake is poorly studied; accordingly, the elemental and phase compositions of antimony cake have not been established. In this regard, it was noted that antimony in the cake occurs in the form of calcium antimonate and antimony hydroxide. The content of antimony in the mine tailings cakes is from 3.53 to 4.4%, with a high content of iron (27.5%) and sodium (8.86%). Based on the established elemental and phase compositions, a chemical matrix of antimony cake was compiled. The equilibrium compositions were calculated and the concentration distribution of the main elements of the cake (Fe, Na, Si, Sb) and their compounds in the gas phase was found depending on the temperature of the destruction of the solid phase. It was found that condensed antimony oxides are formed in the range of 1098 - 1348 K. Taking into account the range of temperatures for decomposition of the solid phase, a two-stage smelting of antimony cake is proposed (melting and cupellation). The conversion of antimony cake sulfides from the gas phase into a solution was carried out based on a study of the system: antimony sulfide- manganese (IV) dioxide- sulfuric acid - sodium chloride. The pH value and the redox potential (Eh) of the solution were calculated. It is noted that the sulfur compounds of antimony from the cake are converted to antimony oxychloride with the formation of antimony (III) oxide in an alkaline medium. The use of sodium chloride as a chlorinating agent of antimony sulfur compounds does not lead to the formation of toxic phosgene and hydrogen sulfide; in the solid phase, elemental sulfur is released, which is important for minimizing the technogenic load of pollutants on the environment.

Oxygen Vacancy Engineering of Molybdenum Oxide Nanobelts by Fe Ion Intercalation for Aerobic Oxidative Desulfurization

Aerobic oxidative desulfurization (AODS) represents a sustainable way to deeply desulfurize transportation fuels through a high-performance catalyst to convert thiophenes into sulfones in an efficient way. Here, we report that iron (Fe) intercalated molybdenum oxides (MoOx) nanobelts can be a durable and robust catalyst for AODS, catalyzing the reaction efficiently at 80 °C with air as a sustainable oxygen source. By combining systematic characterization, kinetic analysis, and density functional theory calculation, we demonstrate that the guest Fe ions could precisely modulate the electronic structure of Mo sites, leading to a significant increase in surface oxygen vacancy density. An optimized doping amount enables our catalyst with excellent catalytic performance via thorough conversion of various sulfides. The catalyst maintained almost unchanged activity in repeated uses, qualifying it as a candidate for the sustainable AODS of fuel. We anticipate that the strategy demonstrated here will provide practical guidance on the rational design and optimization of Mo-based catalysts to promote aerobic oxidation reactions.

Warm Plasma Application in Tar Conversion and Syngas Valorization: The Fate of Hydrogen Sulfide

Warm plasma techniques are considered a promising method of tar removal in biomass-derived syngas. The fate of another problematic syngas impurity—hydrogen sulfide—is studied in this work. It is revealed that processing simulated syngas with a microwave plasma results in hydrogen sulfide conversion. For different gas flow rates (20–40 NLPM) and hydrogen sulfide concentrations ranging from 250 ppm to 750 ppm, the conversion rate varies from ca. 26% to 45%. The main sulfur-containing products are carbon disulfide (ca. 30% of total sulfur) and carbonyl sulfide (ca. 8% of total sulfur). Besides them, significantly smaller quantities of sulfates and benzothiophene are also detected. The main components of syngas have a tremendous impact on the fate of hydrogen sulfide. While the presence of carbon monoxide, methane, carbon dioxide, and tar surrogate (toluene) leads to the formation of carbonyl sulfide, carbon disulfide, sulfur dioxide, and benzothiophene, respectively, the abundance of hydrogen results in the recreation of hydrogen sulfide. Consequently, the presence of hydrogen in the simulated syngas is the main factor that determines the low conversion rate of hydrogen sulfide. Conversion of hydrogen sulfide into various sulfur compounds might be problematic in the context of syngas purification and the application of the right technique for sulfur removal.

L-Cysteine Synthase Enhanced Sulfide Biotransformation in Subtropical Marine Mangrove Sediments as Revealed by Metagenomics Analysis

High sulfides concentrations can be poisonous to environment because of anthropogenic waste production or natural occurrences. How to elucidate the biological transformation mechanisms of sulfide pollutants in the subtropical marine mangrove ecosystem has gained increased interest. Thus, in the present study, the sulfide biotransformation in subtropical mangroves ecosystem was accurately evaluated using metagenomic sequencing and quantitative polymerase chain reaction analysis. Most abundant genes were related to the organic sulfur transformation. Furthermore, an ecological model of sulfide conversion was constructed. Total phosphorus was the dominant environmental factor that drove the sulfur cycle and microbial communities. We compared mangrove and non-mangrove soils and found that the former enhanced metabolism that was related to sulfate reduction when compared to the latter. Total organic carbon, total organic nitrogen, iron, and available sulfur were the key environmental factors that effectively influenced the dissimilatory sulfate reduction. The taxonomic assignment of dissimilatory sulfate-reducing genes revealed that Desulfobacterales and Chromatiales were mainly responsible for sulfate reduction. Chromatiales were most sensitive to environmental factors. The high abundance of cysE and cysK could contribute to the coping of the microbial community with the toxic sulfide produced by Desulfobacterales. Collectively, these findings provided a theoretical basis for the mechanism of the sulfur cycle in subtropical mangrove ecosystems.

Reversible Metal Sulfide Transition in a Two-Step Thermochemical H2S Splitting

Two-step thermochemical H2S splitting process is a promising method to recover both H2 and S from a toxic waste H2S gas via low/high metal sulfide conversion. Several studies have examined the potential of the process experimentally. Still, there is a lack of comprehensive research into such as to provide a guideline for selecting the appropriate metal for the process. The most common metals in the periodic Table (28 metals) have been examined to find stable low/high metal sulfide couples. A list consisting of 17 metals that can form thermodynamically stable couples has been shortlisted, in which six metals: K, Zr, Hf, Nb, Fe, and Ni, were found to be promising candidates with a high H2S splitting efficiency, high H2 yield and good reversible transition between low and high sulfides. The transition between sulfide crystals has been experimentally demonstrated with the Ni3S2/Ni3S2+x couple. This couple can decompose up to 90 mg H2S/g-Ni3S2 at 500 °C to produce H2 and high sulfides Ni3S2+x that was successfully regenerated at 700 °C for multiple cycles. The thermodynamic calculations revealed that the sulfides of Zr, Hf, and Nb are favorable for the two-step H2S splitting process, but have not been explored experimentally. The sulfide of Zr was examined in this work, but they got oxidized by residual oxygen in the test gas before the crystalline transition was detected and remained as a challenge in the future works.

Effect of process conditions on the performance of a dual-reactor biodesulfurization process

The biotechnological gas desulfurization process under haloalkaline conditions is widely applied for removal of toxic H2S from sour gas streams. In this process H2S is biologically oxidized into elemental sulfur. Recently, the process has been extended with an anaerobic process step (dual-reactor line-up), increasing the selectivity for elemental sulfur (S8) from ~85–97% and decreasing the formation of (thio)sulfate. It was also found that biological sulfide uptake took place in the anaerobic bioreactor. In order to apply this process in industry, more insight is needed of the effect of the process conditions on the process performance. The effect of the process conditions HRT and sulfide concentration in the anaerobic bioreactor and pH on the overall product selectivities and on biological sulfide uptake in the anaerobic bioreactor were investigated. 7 experiments were performed in a pilot-scale biodesulfurization set-up. In all experiments, high selectivities (>95%) for S8 formation were obtained, except when the pH in the aerated bioreactor was increased from 8.5 to 9.1 (selectivity of 88%). Furthermore, biological sulfide uptake in the anaerobic bioreactor increased at higher sulfide concentrations and at higher pH. We hypothesize the biological sulfide uptake under anaerobic conditions is related to polysulfide formation. Our results increase the understanding how to control biological sulfide conversion in the dual-reactor biodesulfurization process.

2D sp2 carbon-conjugated triazine covalent organic framework photocatalysis for blue light-induced selective oxidation of sulfides with O2

Triazine, possessing planar and fully conjugated attributes, purveys ample space to construct well-defined crystalline polymers like graphic carbon nitrides (g-C3N4), covalent triazine frameworks (CTFs), and covalent organic frameworks (COFs). Herein, g-C3N4, CTF-1, and TP-COF were successfully synthesized and systematically confirmed by a series of characterizations, aiming at visible light photocatalytic activation of O2. Compared to CTF-1 and g-C3N4, TP-COF was endowed with the best photocatalytic performance by several inherent properties, including a large specific surface area, a suitable bandgap, and superior charge transfer. The blue light-induced selective conversion of organic sulfides has been achieved expeditiously with O2 over TP-COF photocatalyst. Moreover, rigorous control experiments and in situ electron paramagnetic resonance (EPR) suggest that electron and energy transfer pathways contribute to the selective formation of desired sulfoxides. This work emphasizes that the tailor-made trait of COFs provides an ideal plarform of customizing two-dimensional (2D) photoactive COFs based on triazine for visible light-induced selective chemical transformations.

Thermodynamics of Claus conversion of reduced sulfur dioxide

To the sustainable economic development it is necessity to provide the total utilization every kind the waste including sulphurous off-gases of non-ferrous metallurgy. For the distant metallurgical works the most acceptable way for the utilization of the “strong” sulfurous gases of autogenous smelting that contain of over than 20% sulfur dioxide is elemental sulfur production because sulfur in elemental form is commercial product that the most tailored for transportation or long-time storage. To estimate of the potential resources of the sulfur recovery from the sulfurous off-gases autogeneous smelting, in the temperature range 250÷1350 oС, the thermodynamics of the reduction by methan of oxygen-beared sulfurous gases containing ~36 % by volume SO2 is analyzed at a total pressure of 1.0 and 1.3 bar. As it is show the thermodynamics calculation results excess of reducing agent strongly diminishing of the sulfur yield in last stage of the catalytic Claus processing of a real reducted sulfurous gas. According to the results of thermodynamic calculations at 3000 oC and under Claus ratio CR≡[H2S]/[SO2]=0,36÷1,98, it is find that equilibrium concentration of hydrogen sulfide in reducted gas is increase by the Claus ratio increasing. Comparing of the thermodynamic analysis results with the factual data of the reducted sulfurous gases conversion at the temperature 230÷260 oС in the catalytic reactor of the Elemental Sulfur Production Site at Copper Plant of Nornickel’ Polar Division is made. It is determine that in acid gases processing in Claus reactors the real values of the hydrogen sulfide conversion substantially exceed equilibrium conversion values, that may be because limits of the rate of the sulfur hydrolysis reaction inverse of the Claus reaction and make urgent to develop of the kinetic model of the Claus conversion. As it is found by the industrial experimental data analysis, the optimize temperature for the stage of the reducted sulfurous gas Claus conversion is temperature of the Claus reactor 230–250 oC.

Surface decorated magnetic nanoparticles with Mn-porphyrin as an effective catalyst for oxidation of sulfides

Mn-porphyrin complex was anchored coordinatively to silica-coated surface of magnetic nanoparticles (SMNP). Afterward, a heterogeneous nanocatalyst (Fe3O4@SiO2-MnTCPP) has been characterized by Fourier transform infrared (FT-IR), ultraviolet-visible (UV-vis) spectroscopy, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), vibrating sample magnetometry (VSM), thermogravimetric analysis (TGA), and transmission electron microscope (TEM). A thermal stability up to around 350[Formula: see text]C was verified for prepared nanocatalyst based on thermogravimetric analysis. Finally, the catalytic performance of magnetically recoverable Mn-catalyst was exploited in the green oxidation of different sulfides with urea hydrogen peroxide (UHP) in the presence of imidazole as co-catalyst in ethanol under heterogeneous conditions. The eco-friendly property of ethanol strongly induced us to employ it as the reaction solvent in this oxidation system. Complete conversion ([Formula: see text]99) of sulfides to the corresponding sulfoxide or sulfones was obtained for ethyl phenyl sulfide, phenyl vinyl sulfide, diallyl sulfide, thiocyanatoethane, 2-ethyl mercaptoethanol and tetrahydrothiophene. Moreover, the recovered catalysts keep constant conversion yield up to at least three cycles.

Performance of Sulfide-Driven Fuel Cell Aerated by Venturi Tube Ejector

Hydrogen sulfide is frequently met in natural waters, like mineral springs, but mostly it is found in marine water with low renewal rate. The Black Sea has extremely high hydrogen sulfide content. It can be utilized in different ways, but the most promising one is direct conversion into electricity. This result can be attained by a sulfide-driven fuel cell (SDFC), converting sulfide to sulfate thus releasing electric energy up to 24 GJ/t. One of the most important problems is the mass transfer limitation on oxygen transfer in the cathode space of the fuel cell. This problem can be solved using a gas diffusion electrode or highly efficient saturation by oxygen in an ejector of the Venturi tube type. This work presents experimental data in laboratory-scale SDFC for sulfide conversion into sulfate, sulfite and polysulfide releasing different amounts of electric energy. Two types of aeration are tested: direct air blow and Venturi-tube ejector. Besides pure graphite, two catalysts, i.e., cobalt spinel and zirconia-doped graphite were tested as anodes. Experiments were carried out at initial sulfide concentrations from 50 to 300 mg/L. Sulfate, sulfite and thiosulfate ions were detected in the outlet solutions from the fuel cell. The electrochemical results show good agreement with the chemical analyses. Most of the results show attained high efficiencies of the fuel cell, i.e., up to 80%. The practical applications of this method can be extended for other purposes, like treatment of polluted water together with utilization as energy.

An alternative electron-donor and highly thermo-assisted strategy for solar-driven water splitting redox chemistry towards efficient hydrogen production plus effective wastewater treatment

An alternative technology has been sought for highly efficient and sustainable hydrogen production and wastewater treatment worldwide. This paper is focused on the intersection of solar energy, wastewater treatment and hydrogen production. The solar thermo-assisted and electron-donor alternative strategy was conducted for water-splitting redox chemistry to target highly efficient hydrogen production and effective wastewater treatment. The thermodynamic calculation displays that the solar thermal application and shuttle sulfide electron donor alternative are favorable for the hydrogen production and sulfide-to-sulfate oxidation by the falling trend in the potential (from 1.5V to 0.6V). The curves revealed that high current peaks in the low potential range were dominated by the thermal-assisted process and the alternative of the oxidation half-reaction. The experiments illustrated that solar thermal utilization and sulfide donors were dominant factors for the high efficiencies. Under the outdoor sunlight, the high hydrogen production rate and sulfide conversion efficiency were experimentally achieved at rates of 0.25 mL/h H2 and 93% sulfide-to-sulfate oxidation, reasonably more than that of the direct electrochemical water splitting to hydrogen (nearly no evolution) under the same applied bias (＜1.2V). The system realized that one sustainable technology conducts simultaneously both highly efficient hydrogen production and highly effective water treatment.

Thermodynamics and Kinetics of the Claus Conversion of Hydrogen Sulfide from Coke-Oven Gas

Thermodynamics and Kinetics of the Claus Conversion of Hydrogen Sulfide from Coke-Oven Gas

H2S removal performance of Ca3Al2O6-stabilized carbide slag from CO2 capture cycles using calcium looping

A Ca3Al2O6-stabilized carbide slag from calcium looping cycles for CO2 capture was proposed as a H2S sorbent in zero emission carbon process. The H2S removal performance of Ca3Al2O6-stabilized carbide slag experienced different calcium looping cycles was investigated in a muti-fixed-bed reactor. The fabricated sorbent containing the mass ratio of CaO to Ca3Al2O6 = 73:27 shows higher CO2 capture capacity. The sulfidation temperature and H2S concentration exhibit the important effects on H2S removal by the fabricated sorbent from CO2 capture cycles. The number of CO2 capture cycles has a little effect on H2S removal by the fabricated sorbent. The sulfidation conversions of the fabricated sorbent after 100 CO2 capture cycles at 60 and 120 min can reach 1.3 and 1.6 times as high as those of carbide slag, respectively. Ca3Al2O6 restrains the rapid growth of CaO grains in the fabricated sorbent in CO2 capture cycles. Compared with carbide slag, the fabricated sorbent possesses larger surface area and more stable structure during CO2 capture cycles because of the support of Ca3Al2O6, so it exhibits higher sulfidation conversion. H2S removal using Ca3Al2O6-stabilized carbide slag from calcium looping cycles seems promising in zero emission carbon process.

A Baeyer-Villiger monooxygenase from Cupriavidus basilensis catalyzes asymmetric synthesis of (R)-lansoprazole and other pharmaco-sulfoxides.

Biocatalytic synthesis of pharmaco-chiral sulfoxides has gained interest in recent years for its environmental friendliness. However, only a few natural biocatalysts can be used for the efficient synthesis of pharmaco-sulfoxides, including (R)-lansoprazole, a chiral proton pump inhibitor used to treat gastrointestinal diseases. In this study, the sequence of BoBVMO (Baeyer-Villiger monooxygenase from Bradyrhizobium oligotrophicum) was used as a probe to identify BVMOs via genomic mining for the highly efficient synthesis of (R)-lansoprazole and other pharmaco-sulfoxides. After virtual sequence filtering, target gene cloning, heterologous expression, and activity screening for lansoprazole sulfide (LPS) monooxygenation, seven new BVMOs were identified among more than 10,000 homologous BVMOs. According to the conserved sequence and phylogenetic tree analysis, these discovered enzymes belong to the family of type I BVMOs and the ethionamide monooxygenase subtype. Among them, CbBVMO, Baeyer-Villiger monooxygenase from Cupriavidus basilensis, showed the highest efficiency and excellent enantioselectivity for converting LPS into (R)-lansoprazole. Moreover, CbBVMO showed a wide substrate spectrum toward other bulky prazole-family sulfides. The results indicate that CbBVMO is a potential enzyme for extending the application of BVMOs in pharmaceutical industry. KEY POINTS: • CbBVMO is the most efficient biocatalyst for (R)-lansoprazole biosynthesis. • CbBVMO catalyzes the conversion of various bulky prazole sulfides. • CbBVMO is a promising enzyme for the biosynthesis of pharmaco-sulfoxides.

Kinetic Features of the Hydrogen Sulfide Sorption on the Ferro-Manganese Material

The kinetics of hydrogen sulfide sorption by the surface of a ferromanganese material containing in its composition a mixture of iron (II) and (III) oxides FeO × Fe2O3, takanelite (Mn, Ca) Mn4O9 × 3H2O and quartz SiO2, and which is samples of unrefined ferromanganese ore, was studied in this work. Sorption rate constant and activation energy constant values were calculated. The catalytic effect of iron (III) oxide was established, the presence of which in natural material contributes to a decrease in the H2S sorption activation energy. Based on the results of X-ray phase and chromatographic analysis methods, a chemical (redox) reaction of the conversion of hydrogen sulfide into elemental sulfur and H2O was revealed. The overall process rate is expressed in terms of the physical sorption stage and chemical transformation of the components; the influence of the rate of the third stage—reaction products desorption—on the overall rate of the process is taken into account. The limiting stage of the process is determined—a chemical reaction. The relation between the heat and the activation energy of the chemical transformation is used according to the Bronsted—Polanyi rule for catalytic processes. It was found that with an increase in the chemisorption heat, the activation energy of the chemisorption stage decreases and, as a consequence, its rate increases. The sorption process parameters were calculated—the Fe2O3 coverage degree with the initial substances and reaction products providing the maximum sorption rate, which can be a criterion for evaluating the catalytically active sites of the catalyst surface for carrying out catalytic reactions.

Screening of Metal Chloride Anion-based Ionic Liquids for Direct Conversion of Hydrogen Sulfide by COSMO-RS

In order to identify the best possible reaction media for performing H2S conversion, a total number of 300 different ILs from a combination of 20 cations and 15 anions were screened via COSMO-RS model simulations. By COSMO-RS method, thermodynamic and physicochemical properties of 300 ILs such as Henry’s law constants, activity coefficient, selectivity, capacity and performance index are obtained and analyzed. Thus, by comparing the performance of ILs via COSMO-RS, a series of TSILs containing cation of [P66614] with metal chloride anions such as Fe, Ga and Sn were chosen and selected for synthesis based on their performance predicted by COSMO-RS and their economic values. Consequently, the physiochemical properties such as density, viscosity, thermal properties, as well as H2S absorptive oxidation performances in those TSILs will be systematically investigated.

Phase evolution of Cu2ZnSnS4 (CZTS) nanoparticles from in situ formed binary sulphides under solvothermal conditions

Cu2ZnSnS4 (CZTS) nanocrystals form both by direct nucleation and growth and by conversion of binary sulphides into the quaternary phase via internal recrystallization processes.

Effects of Nutrient Component on the Performance of Biological Sulfur Recovery Unit

Biological Sulfur Recovery Unit (Bio-SRU) with Thiobacillus as biocatalysts is believed to be suitable for handling hydrocarbon feed gas with moderate to low-H2S concentration. The purpose of this study is to evaluate the effect of SO4 2-, PO4 3-, and Fe2+ concentration on Bio-SRU performance particularly on the conversion of sulfide to elemental sulfur. Biological pathway of sulfur recovery from natural gas-treating facility wastewater was then studied by measuring the pH and redox potential of the sample. It shows that the variation of SO4 2- concentration does not significantly affect the conversion process, while a small increment of PO4 3- (KH2PO4 1.7 g/L and K2HPO4 1.36 g/L) results in a higher yield of elemental sulfur production. Fe2+also gave a significant effect on sulfur formation and conversion rate.

Dipyridine Amine Octamolybdates Hybrid Material Effectively Catalyzed Oxidation of Sulfide Derivatives with Hydrogen Peroxide

With the increasing interest in polyoxometalates (POMs) materials over the past few decades, scientific researchers have focused their attention on the fruitful utilization of POMs hybrids as efficient catalysts in many organic reactions. In this paper, dipyridine amine (dpa) organic ligand hybrid polyoxomolybdate material was solvothermally synthesized and structurally identified by elemental analysis, X-ray diffraction and infrared spectrum. Structural refinement of the hybrid polyoxomolybdate compound 1 with general formula [Hdpa]4Mo8O26 · 2DMF (DMF = N,N-dimethylformamide) shows that compound 1 presents in the space group P-1 with triclinic system, and is built up from a well-known β-[Mo8O26]4– anionic cluster, four free protonated dpa cations and two free DMF molecules. Remarkably, the β-Mo8O26-based hybrid material was further applied as the catalyst in the conversion of sulfides utilizing hydrogen peroxide (30%) as green terminal oxidant and exhibited efficient catalytic activities for selective oxidation of sulfides.