Fabrication and characterization of tungsten-containing mesoporous silica for heterogeneous oxidative desulfurization

A series of functional,tungsten-containing mesoporous silica materials（W-SiO2） have been fabricated directly from an ionic liquid that contained imidazole and polyoxometalate,which acted as mesoporous template and metal source respectively.These materials were then characterized through X-ray diffraction（XRD）,transmission electron microscopy（TEM）,Raman spectroscopy,Fourier transform infrared spectra（FTIR）,diffuse reflectance spectra（DRS）,and N2 adsorption-desorption,which were found to contain tungsten species that were effectively dispersed throughout the structure.The as-prepared materials W-SiO2 were also found to possess a mesoporous structure.The pore diameters of the respective sample W-SiO2-20 determined from the TEM images ranged from 2 to 4 nm,which was close to the average pore size determined from the nitrogen desorption isotherm（2.9 nm）.The materials were evaluated as catalysts for the heterogeneous oxidative desulfurization of dibenzothiophene（DBT）,which is able to achieve deep desulfurization within 40 min under the optimal conditions（Catalyst（W-SiO2-20）= 0.01 g,temperature = 60℃,oxidant（H2O2）= 20 μL）.For the removal of different organic sulfur compounds within oil,the ability of the catalyst（W-SiO2-20） under the same conditions to remove sulfur compounds decreased in the order：4,6-dimethyldibenzothiophene Dibenzothiophene Benzothiophene 1-dodecanethiol.Additionally,they did not require organic solvents as an extractant in the heterogeneous oxidative desulfurization process.After seven separate catalytic cycles,the desulfurization efficiency was still as high as 90.3%.From the gas chromatography-mass spectrometer analysis,DBT was entirely oxidized to its corresponding sulfone DBTO2 after reaction.A mechanism for the heterogeneous desulfurization reaction was proposed.

Simultaneous Removal of H_2S and Organosulfur Compounds from Liquefied Petroleum Gas Using Formulated Solvents: Solubility Parameter Investigation and Industrial Test

The performance of four formulated solvents(labeled as UDS-I, UDS-II, UDS-III, and UDS-IV) for removing methyl mercaptan from liquefied petroleum gas was predicted based on a two-dimensional solubility parameter theory. The calculation results show that UDS-IV has the closest solubility parameter to that of methyl mercaptan as compared with other tested solvents, indicating the strongest affinity and the highest solubility for methyl mercaptan. The industrial tests at a plant for desulfurization of LPG produced from the delayed coker have shown that the UDS solvents have the excellent performance for removal of organosulfur compounds(mainly methyl mercaptan). Although the sulfur loading dramatically increases, the total sulfur content of LPG treated with UDS-IV can be reduced by about 50% in comparison with N-methyl diethanolamine. In addition, UDS-IV has superior regeneration performance and selectivity for sulfur compounds over hydrocarbons. The industrial test and the solubility parameter calculation results are in good agreement with each other.

Insight into the reaction mechanism of sulfur chains adjustable polymer cathode for high-loading lithium-organosulfur batteries

Small molecules with adjustable sulfur atoms in the confined structure were acted as precursor for the synthesis of polymer cathodes for lithium-organosulfur batteries.Among them,poly(diallyl tetrasulfide)(PDATtS)delivered a high capacity of 700 mAh g^(-1),stable capacity retention of 85%after 300 cycles,high areal capacity~4 m Ah cm^(-2) for electrode with up to 10.3 mg cm^(-2) loading.New insight into the reaction mechanism of PDATtS electrode that radicals arisen from the homolytic cleavage of S-S bond in PDATtS reacted with Li+to generate thiolates(RSLi)and insoluble lithium sulfides(Li_(2)S)or lithium disulfide(Li_(2)S_(2))was clearly verified by in-situ UV/Vis spectroscopy,nuclear magnetic resonance(NMR)studies and density-functional theory(DFT)calculations.Therefore,based on the unique reaction mechanism,problems of rapid capacity fading due to the formation of soluble polysulfide intermediates and their serious shuttle effect in conventional lithium-sulfur(Li-S)batteries was totally avoided,realizing the dendrite-free lithium sulfur batteries.This study sets new trends for avenues of further research to advance Li-S battery technologies.

Uncovering the solid-phase conversion mechanism via a new range of organosulfur polymer composite cathodes for lithium-sulfur batteries

The sulfur cathodes operating via solid phase conversion of sulfur have natural advantages in suppressing polysulfide dissolution and lowering the electrolyte dosage,and thus realizing significant improvements in both cycle life and energy density.To realize an ideal solid-phase conversion of sulfur,a deep understanding of the regulation path of reaction mechanism and a corresponding intentional material and/or cathode design are highly essential.Herein,via covalently fixing of sulfur onto the triallyl isocyanurate,a series of S-triallyl isocyanurate organosulfur polymer composites(STIs) are developed.Relationship between the structure and the electrochemical conversion behavior of STIs is systematically investigated.It is found that the structure of STIs varies with the synthetic temperature,and correspondingly the electrochemical redox of sulfur can be controlled from conventional "solid-liquid-solid" conversion to the "solid-solid" one.Among the STI series,the STI-5 composite realizes an ideal solid-phase conversion and demonstrates great potential for building a Li-S battery with high-energy density and long-cyclelife:it realizes stable cycling over 1000 cycles in carbonate electrolyte,with a degradation rate of0.053% per cycle;the corresponding pouch cell shows almost no capacity decay for 125 cycles under the conditions of high sulfur loading(4.5 mg cm^(-2)) and lean electrolyte(8 μL mg_s^(-1)).In addition,the tailoring strategy of STI can also apply to other precursors with allyl functional groups to develop new organosulfur polymers for "solid-solid" sulfur cathodes.The vulcanized triallyl phosphate(STP) and triallylamine(STA) both show great lithium storage potential.This strategy successfully develops a new family of organosulfur polymers as cathodes for Li-S batteries via solid-phase conversion of sulfur,and brings insights to the mechanism study in Li-S batteries.

Low-temperature Li-S batteries enabled by all amorphous con version process of organosulfur cathode

The high degree of crystallinity of discharging in termediates of Li-S batteries(Li_(2)S_(2)/Li_(2)S)causes a severe capacity attenuation at low temperatures.Herein,a sulfur-rich polymer is fabricated,which enables all the discharging in termediates to exist in an amorphous state without long-range order,promoti ng the substantial conversion of discharging intermediates and enhancing Li-S batteries'performance at low temperatures greatly.This cathode material exhibits excellent performance both at room and low temperatures.Even under an extremely low temperature(-40℃),the discharge capacity can remain 67% of that at room temperature.Besides,in-situ UV/Vis spectroscopy and density functional theory calculations reveal that this organosulfur cathode undergoes a new mechanism during discharge.Li_(2)S_(6) and Li_(2)S_(3) are the primary discharging intermediates that are quite different from conventional Li-S batteries.These results provide a new directi on for a broader range of applications of Li-S batteries.

Synthesis and Characterization of a One-dimensional Coordination Polymer Generated from Unsymmetrical Bridging Organosulfur Ligand

A new one-dimensional（1D） coordination polymer [Zn（MMTA）2]n（MMTA=5-mercapto-l-methyl-tetrazole） was synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic space group C2/c, with cell parameters： a=1.4938（7） nm, b=1.3599（5） nm, c=1.2180（4） nm, fl=120.84（3）^＊, V=2.1243（2） nm^3, and Z=8. The deprotonated HMMTA molecule as a/a2-1igand links the zinc center, forming ID chains, which are luther linked by weak C--H...N hydrogen bonds, forming a three-dimensional supramolecular framework. The compound exhibits intense photoluminescence at room temperature. On the basis of the results of TG/DTA analyses, the structure is thermally stable up to -280 ℃.

2,5-Dimercapto-1,3,4-Thiadiazole(DMCT)-Based Polymers for Rechargeable Metal-Sulfur Batteries

Organosulfur materials are a sustainable alternative to the present-day layered oxide cathodes in lithium-based batteries.One such organosulfur material that was intensely explored from the 1990s to early 2010s is 2,5-dimercapto-1,3,4-thiadiazole(DMCT).However,research interest declined as the electrode reactions with DMCT were assumed to be too sluggish to be practical.Armed with the advances in metal-sulfur batteries,we revisit DMCT-based materials in the form of poly[tetrathio-2,5-(1,3,4-thiadiazole)],referred to as pDMCT-S.With an appropriate choice of electrode design and electrolyte,pDMCT-S cathode paired with a Li-metal anode shows a capacity of 715 mA h g^(-1)and a Coulombic efficiency of 97.7%at a C/10 rate,thus quelling the concerns of sluggish reactions.Surprisingly,pDMCT-S shows significantly improved long-term cyclability compared to a sulfur cathode.Investigations into the origin of the stability reveals that the discharge product Li-DMCT in its mesomeric form can strongly bind to polysulfides,preventing their dissolution into the electrolyte and shuttling.This unique mechanism solves a critical problem faced by sulfur cathodes.Encouragingly,this mechanism results in a stable performance of pDMCT-S with Na-metal cells as well.This study opens the potential for exploring other organic materials that have inherent polysulfide sequestering capabilities,enabling long-life metal-sulfur batteries.

Syntheses,Characterizations and Crystal Structures of (E)-2-Methyl-1,3-diphenylisothiouronium Iodide and 1,3-Dibenzyl-2-methylisothiouronium Iodide

Two thiouronium iodide salts,（E）-2-methyl-1,3-diphenylisothiouronium iodide（1） and 1,3-dibenzyl-2-methylisothiouronium iodide（2）,were synthesized and characterized by single-crystal X-ray diffraction,1H NMR,IR,UV-vis and luminescence spectra.Single-crystal X-ray diffraction reveals that compound 1 crystallizes in monoclinic system,P21/n space group with a = 11.273（2）,b = 10.318（2）,c = 12.962（3） A,β = 99.03（3）°,V = 1489.0（5） A^3 and Z = 4;compound 2 crystallizes in monoclinic system,C2/c space group with a = 11.706（2）,b = 14.119（3）,c = 20.930（4） A,β = 103.84（3）°,V = 3358.8（12） A^3 and Z = 8.The thiouroniums of both compounds are Y-shaped planar structures to form a cross-conjugated system.The averaged bond lengths of C-N and C-S indicate the presence of ＂Y＂ aromaticity.The researches on UV-vis and luminescence spectra of compounds 1 and 2 indicate that they can form inclusion complex with β-CD in the aqueous solution.

Synthesis and perspective of organosulfur chemicals in agrochemicals

As well known,with the increase of world population,improving agricultural production has always been of great importance.Due to the effective protection against pests or pathogenic bacteria and promoting the growth of crops,agrochemical holds vital position in modern agriculture.In this field,introducing sulfur moieties into active ingredients to improve the property of pesticides has been a powerful tool for the development of agrochemical.Thus,the efficient methods for the construction of organosulfur scaffolds existed in agrochemicals are highly desirable,which also attract considerable attentions over the past few decades.Herein,we provide comprehensive introduction of organosulfur agrochemicals and representative synthetic access to sulfur-containing molecules frequently found in pesticides with the utilization of various sulfurizing agents,point out the potential direction for further development.

Sulfur-accumulating Model of Superhigh Organosulfur Coal From Guiding, China

Superhigh organosulfur coal has received considerable attention 'chemically as well as geologically,because from it we could get much useful chemical information for removing organosulfur from coal.By studying it, we could also find out the factors af-

Differentiating depositional environments and maturity of crude oils using GC-AED benzothiophenic spectra

Organosulfur compounds of crude oils and light oils (condensates), collected from ten Chinese petroleum-bearing basins and representing different sedimentary environments, were analyzed and identified using a newly-developed GC-AED technique. The results show that the distributions of organosulfur compounds of crude oils from different sedimentary environments are of obvious difference. The crude oils from marine carbonates are rich in organosulfur compounds and those from the source rocks in an ocean-land interchanging facies and a littoral facies have a high abundance of organosulfur compounds, while no or less organosulfur compounds of crude oils from a fresh-water lacustrine facies and a swamp facies were detected in the detectable abundance range of the instrument. This analysis gives a new effective method for oil-source correlation. We also tried to relate the various parameters of benzothiophenic compounds of crude oils with the methane carbon isotope of associated natural gases to discuss the thermoevolutionary degree of crude oils and natural gases.

Catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations

Chiral organosulfur compounds are not only widely distributed in bioactive natural products and pharmaceuticals,but also play a significant role in chiral ligands/catalysts.Throughout the history of synthetic organic chemistry,chemists have been absorbed in the construction of centrally chiral organosulfur compounds.Nevertheless,there are relatively few reports on installing sulfur functional groups into axially chiral compounds.Atropisomerism is one of the fundamental phenomena in nature,which ubiquitously exists in natural products.After more than a century of development,atropisomers have been designed and extensively applied to pharmaceuticals,functional materials and chiral ligands/catalysts.Due to the importance of chiral sulfurcontaining atropisomers,there is an increasing demand for enantioselective synthesis of them.Recently,a diversity of approaches by C-S bond formations have been established for the construction of enantioenriched sulfur-containing atropisomers,however,there is no comprehensive review to summarize this great progress.In this mini-review,we summarize recent progress in catalytic asymmetric synthesis of sulfur-containing atropisomers by C-S bond formations,which includes sulfur nucleophilic reactions,sulfur electrophilic reactions and sulfur radical reactions.Furthermore,the reaction mechanisms are also discussed.We hope that this mini-review will enable more researchers to further explore this field.

Microbial reduction of organosulfur compounds at cathodes in bioelectrochemical systems

Organosulfur compounds,present in e.g.the pulp and paper industry,biogas and natural gas,need to be removed as they potentially affect human health and harm the environment.The treatment of organosulfur compounds is a challenge,as an economically feasible technology is lacking.In this study,we demonstrate that organosulfur compounds can be degraded to sulfide in bioelectrochemical systems(BESs).Methanethiol,ethanethiol,propanethiol and dimethyl disulfide were supplied separately to the biocathodes of BESs,which were controlled at a constant current density of 2 A/m^(2) and 4 A/m^(2).The decrease of methanethiol in the gas phase was correlated to the increase of dissolved sulfide in the liquid phase.A sulfur recovery,as sulfide,of 64% was found over 5 days with an addition of 0.1 mM methanethiol.Sulfur recoveries over 22 days with a total organosulfur compound addition of 1.85 mM were 18% for methanethiol and ethanethiol,17% for propanethiol and 22% for dimethyl disulfide.No sulfide was formed in electrochemical nor biological control experiments,demonstrating that both current and microorganisms are required for the conversion of organosulfur compounds.This new application of BES for degradation of organosulfur components may unlock alternative strategies for the abatement of anthropogenic organosulfur emissions.

Boron-promoted reductive deoxygenation coupling reaction of sulfonyl chlorides for the C(sp3)-S bond construction

Herein,we report a borane-promoted reductive deoxygenation coupling reaction to synthesize sulfides.This reaction features excellent functional group compatibility,high efficiency,broad substrate scope,and application in late-stage functionalization of biomolecules.Preliminary mechanistic studies suggest diaryl sulfides are the intermediates of this reaction.Moreover,the real active aryl sulfide anions may be generated in situ with the aid of B2pin2 and react with alkyl tosylates through a concerted SN2 pathway.

Nonlinear optical material of a low-dimensional coordination polymer:Synthesis,structure,NLO and fluorescence properties

Employing unsymmetrical 2-mercapto-5-methyl-1,3,4-thiadiazole and 2,2′-bipyridine as mixed ligands, a new low-dimensional coordination polymer [Zn(MMTA) 2 (2,2′-bipy)] n (MMTA = 2-mercapto-5-methyl-1,3,4-thiadiazole, 2,2′-bipy = 2,2′-bipyridine), has been synthesized under solvothermal condition and characterized by single crystal X-ray diffraction. This compound crys- tallizes in the noncentrosymmetric space group Cc, with cell parameters: a = 8.291(4) , b = 15.483(9) , c = 15.620(6) , = 96.00(5)°, V = 1994.1(2) 3 , and Z = 4. The mixed ligands link the zinc center into a mononuclear unit, which is futher linked by weak C-H···N and C-H···S hydrogen bonds into a three-dimensional noncentrosymmetric framework. The compound exhibits intense photoluminescence and distinct NLO properties at room temperature. The intensity of the green light produced by the powder sample of the compound is about 3.2 times that produced by KDP powder. On the basis of the results of TG analysis, the structure is thermally stable up to ～260 °C.

Sulfur polymerization strategy based on the intrinsic properties of polymers for advanced binder-free and high-sulfur-content Li–S batteries

Lithium-sulfur(Li-S)batteries are the promising next-generation secondary energy storage systems,because of their advantages of high energy density and environmental friendliness.Among numerous cathode materials,organosulfur polymer materials have received extensive attentions because of their controllable structure and uniform sulfur distribution.However,the sulfur content of most organosulfur polymer cathodes is limited(S content<60%)due to the addition of large amounts of conductive agents and binders,which adversely affects the energy density of Li-S batteries.Herein,a hyperbranched sulfur-rich polymer based on modified polyethyleneimine(Ath-PEI)named carbon nanotubeentangled poly(allyl-terminated hyperbranched ethyleneimine-random-sulfur)(CNT/Ath-PEI@S)was prepared by sulfur polymerization and used as a Li-S battery cathode.The high intrinsic viscosity of Ath-PEI provided considerable adhesion and avoided the addition of PVDF binder,thereby increasing the sulfur content of cathodes to 75%.Moreover,considering the uniform distribution of elemental sulfur by the polymer,the utilization of sulfur was successfully improved,thus improving the rate capability and discharge capacity of the battery.The binder-free,sulfur-rich polymer cathode exhibited ultra-high initial discharge capacity(1520.7 mAh g^(−1) at 0.1 C),and high rate capability(804 mAh g^(−1) at 2.0 C).And cell-level calculations show that the electrode exhibits an initial capacity of 942.3 mAh g^(−1) electrode,which is much higher than those of conventional sulfur-polymer electrodes reported in the literature.

A non-aqueous Li/organosulfur semi-solid flow battery

Non-aqueous flow batteries have attracted extensive attention due to the advantages of wide voltagewindow, high energy density and wide operating temperature and so on. Herein, tetramethylthiuramdisulfide （TMTD） with high intrinsic capacity （223 mAh/g） and high solubility （-1 mol/L in chloroform） isinvestigated as the positive active material of the non-aqueous LiJdisulfide semi-solid flow battery. Theelectrochemical activity and reversibility are investigated by cyclic voltammetry and linear scanvoltammetry. This Li/TMTD battery with a high cell voltage of 3.36 V achieves coulombic efficiency of 99%,voltage efficiency of 73% and energy efficiency of 72% at the current density of 5 mA/cm2 with activematerial concentration of 0.1 mol/L. Moreover, the LiJTMTD battery can operate for 100 cycles withoutobvious efficiency decay, indicating good stability.

Chemical analysis and flavour compound changes of vegetable blend slurry fermented with selected probiotic bacteria

A vegetable blend slurry consisting of aloe vera (Aloe barbadensis miller),garlic (Allium sativum),ginger (Zingiber officinale),liquorice (Glycyrrhiza glabra) and pumpkin seeds (Cucurbita pepo L.) was used as a probiotic medium to evaluate the impact of probiotic fermentation on its chemical composition and flavour compound changes.Two commercial probiotic bacteria,Bifidobacterium animalis subsp.lactis HN019 and Lactobacillus acidophilus La-14,were used for monoculture and coculture fermentation over 72 h.After fermentation,sugars,organic acids and amino acids changed differently due to differences in metabolic pathways.In addition,there was a significant decrease in organosulfur compounds (from 10.56 ± 0.98 mg/L to 6.14 ± 0.83 mg/L,7.80 ± 1.09 mg/L and 6.02 ± 0.61 mg/L for B.lactis HN019 monoculture,L.acidophilus La-14 monoculture,and coculture fermentation,respectively) and total phenolic contents (TPC,from 24.61 ± 1.23 mg gallic acid equivalent (GAE)/g dry extract (DE) to 16.29 ± 1.22 and 15.66 ± 1.03 mg GAE/g DE for L.acidophilus La-14 monoculture and coculture fermentation,respectively).Interestingly,no significant changes in oxygen radical absorbance capacity (ORAC),total dietary fibre content and fat content after fermentation.Coculture fermentation did not show any significant synergistic or antagonistic effect.Our results suggest that the vegetable blend and the bacterial strains used have potential to create a novel probiotic product.

A General Electron Donor-Acceptor Photoactivation Using Oxime Esters Enabled Divergent Thioetherifications

Comprehensive Summary The EDA complex-mediated reactions involving oxime esters have been few studied.Herein,an EDA complex formed by thiophenolate anion and oxime ester is reported for photoinduced divergent synthesis of thioethers,depending on different types of oxime esters.Operational simplicity,mild reaction conditions,and flexible options of leaving group demonstrate the generality and synthetic utility of this approach.Such an approach can also enable an interesting thiol-catalysis for the synthesis of phenanthridines.