Sulfur Capacity Research Articles

Preparation and characteristics of CuO/γ-Al2O3 nanocomposite as efficient adsorbent for adsorption of sulfur compounds from Iraqi naphtha

Herein, CuO/γ-Al 2 O 3 nanocomposite adsorbent were synthesized and characterized for adsorptive desulfurization of naphtha fraction. The γ-Al 2 O 3 nanoparticles was first, prepared by coprecipitation route and characterized by XRD, AFM, BET and SEM methods. Then, CuO was supported onto γ-Al 2 O 3 nanoparticles by impregnation method. The effects of different parameters were studied on the sulfur removal efficiency and adsorption capacity in batch and continuous modes. These parameters included contact time and adsorbent dose in batch study, while in continuous study; the breakthrough curves were generated in fixed bed adsorber. The batch adsorption study indicates that the CuO/γ-Al 2 O 3 nanoadsorbent exhibited better max adsorption capacity (78.8 mg/g) than bare γ-Al 2 O 3 (34.2 mg/g). Different adsorption kinetics models and isotherms were investigated for CuO/γ-Al 2 O 3 and γ-Al 2 O 3 nanoadsorbents. The adsorption kinetics of naphtha desulfurization were closely followed the second order kinetic model. Also, Langmuir isotherm was well represented the equilibrium adsorption of sulfur. In continuous study, breakthrough curves were generated for CuO/γ-Al 2 O 3 nanocomposite at LHSV = 2 h −1 and bed height = 7 cm. The time of breakthrough point was 320 min. Moreover, the Yoon–Nelson model fitted best for the continuous experimental data.

Designing conductive networks of hybrid carbon enables stable and long-lifespan cotton-fiber-based lithium-sulfur batteries.

In modern society, flexible rechargeable batteries have become a burgeoning apodictic choice for wearable devices. Conventional lithium–sulfur batteries lack sufficient flexibility because their electrode materials are too rigid to bend. Along with the inherent high theoretical capacity of sulfur, lithium–sulfur batteries have some issues, such as dissolution and shuttle effect of polysulfides, which restricts their efficiency and practicability. Here, a flexible and “dead-weight”-free lithium–sulfur battery substrate with a three-dimensional structure was prepared by a simple strategy. With the cooperative assistance of carbon nanotubes and graphene attached to cotton fibers, the lithium–sulfur battery with 2.0 mg cm−2 sulfur provided a high initial discharge capacity of 1098.7 mA h g−1 at 1C, and the decay rate after 300 cycles was only 0.046% per cycle. The initial discharge capacity at 2C was 872.4 mA h g−1 and the capacity was maintained 734.4 mA h g−1 after 200 cycles with only a 0.079% per cycle decay rate.

Адсорбционная очистка изопентана от диметилсульфида

The adsorption capacity of a number of zeolites during the purification of the n-hexane + dimethyl sulfide model mixture from dimethyl sulfide was studied. Under the selected conditions (21–24°C, flow rate of the model mixture —120 ml/h, adsorbent volume — 50 ml) ultra-stable zeolite exhibits the greatest sulfur capacity 2.3% by weight.

Novel nanocomposite adsorbent for desulfurization of 4,6-dimethyldibenzothiophene from model fuel

In the present study, TiO 2 /Y-zeolite nanocomposite was successfully manufactured from TiO 2 prepared by sol–gel method and commercial HY zeolite. Then, characterized by XRD, AFM, BET, SEM and EDX analysis. The nanocomposite was introduced for ultra-deep adsorptive desulfurization of 4,6- dimethyldibenzothiophene (4,6-DMDBT) from model fuel at mild conditions of 25 °C and atmospheric pressure via batch mode experiments. The results showed that the adsorbent achieved a sulfur removal efficiency higher than 99% with an initial sulfur content in the model fuel of 280 ppm. This high performance was attributed to its large surface area and good mechanical properties. The effect of different initial sulfur content of model fuel and adsorbent amount were also investigated. The most of the sulfur compound was removed before equilibrium time 30 min. A high static saturated sulfur capacity of 11 (mg S/g adsorbent) was achieved. The adsorption equilibrium analysis was investigated and experimental data were best fitted with Langmuir isotherm. The isotherm equations corelate the data with correlation coefficients (R 2 ) values in the order of: Langmuir > Temkin > Freundlich.

Low Temperature Adsorption Desulfurization Performance and Mechanism of CeFe/ZSM‐5 for H2S and SO2 Mixture

Abstract3Ce5Fe/ZSM‐5 adsorbent for simultaneously removal of H2S and SO2 mixture gas was prepared by wet impregnation method. The dynamic removal performance of H2S and SO2 mixture was investigated in a fixed bed reactor. The simultaneous adsorption removal mechanism of 3Ce5Fe/ZSM‐5 before and after Ce addition for H2S and SO2 mixture gas was discussed. Results show that the breakthrough sulfur capacity of 3Ce5Fe/ZSM‐5 is 211.4 mg S/g ads under temperature of 36 °C, space velocity of 500 h−1, the vapor content of 4 vol. % and oxygen sulfur ratio of 1, which is 14.5 % higher than that of 5Fe/ZSM‐5 (184.6 mg S/g ads). The sulfur species on 3Ce5Fe/ZSM‐5‐E exist in forms of S (43.5 %) and SO42− (56.5 %), and the sulfur selectivity is 18.4 % higher than that of 5Fe/ZSM‐5. The addition of Ce can improve the dispersibility and redox performance of Fe3+, resulting in the valence state of Fe3+ stable and increasing the selectivity of sulfur. Moreover, the addition of Ce can significantly improve low‐temperature removal activity of 3Ce5Fe/ZSM‐5 for H2S and SO2 mixture gas.

Deep removal of thiophene and benzothiophene in low-sulfur fuels over the efficient CeAlSBA-15 adsorbent synthesized by sequential alumination and cerium incorporation

Deep removal of thiophenic sulfur compounds in the low-sulfur concentration fuels (e.g., < 50 μg/g S) has been facing a great challenge. Ce-containing adsorbents as a typical representation of “S-M” bonding mechanism have performed an excellent adsorption selectivity, while it cannot be unsatisfactory for the sulfur capacity due to the ambiguous and complexity of effective adsorption active sites. Herein, we aim to address the above difficulty, employing the CeAlSBA-15 materials that are synthesized for the first time by the sequential alumination and Ce incorporation. The data results of XRD, Ar adsorption, TEM and EDX mapping indicate that the Ce species can be highly dispersed onto the micro-mesoporous surface of CeAlSBA-15 by the induction of Al species. Moreover, the UV–vis, XPS and in situ FTIR spectra further reveal that the isolated Ce(III) species (e.g., -Al-O-Ce-O-Si-) located onto the CeAlSBA-15 adsorbents can be considered as effective adsorption active sites, rather than the Ce(IV) species (e.g., -Ce-O2-Ce-) that is difficult to be touched due to the steric hindrance. For the model fuels of thiophene and benzothiophene, 90 and 65 mL/g of sulfur-free fuels can be produced by using the CeAlSBA-15(NH4+) adsorbent, respectively, which are much superior to the best one reported. In particular, the adsorbent shows an excellent regeneration performance after three cycles (90.8% sulfur capacity recovered), and also can perform an outstanding adsorption selectivity (36.7%) in the presence of 5 wt% benzene. The contribution of this work can pave a way for further developing more excellent desulfurization adsorbents with effective adsorption active sites.

Zeolite catalyst containing metals.

Adsorption desulfurization is one of the most promising ways to reduce the sulfur content of gasoline at deeper level. In this work, thiophene (TP) adsorption capacity in cyclohexane onto [Cu3(BTC)2(H2O)3] (HKUST-1) was measured by batch method, and the effect of cyclohexene and toluene on sulfur capacity was investigated. Adsorption isotherms of TP, cyclohexene, and toluene in cyclohexane onto HKUST-1 were conducted at 298.15–313.15 K to explicate the different extent of influence by cyclohexene or toluene addition. The results showed that, compared with cyclohexene, the addition of toluene in model gasoline led to a moderate decline in sulfur capacity of HKUST-1. The isotherm data of TP adsorption were well-correlated using Langmuir equation, while those of cyclohexene or toluene adsorption fitted Freundlich model, indicating different adsorption mechanisms between TP and competitors. The adsorption capacities followed the order of toluene < cyclohexene ≪TP at the same equilibrium concentrations, implying the order of the adsorption affinities, which is in good agreement with the different extent of influence by cyclohexene and toluene. The excellent regeneration performance of HKUST-1 in TP adsorption benefits from the physical adsorption mechanism, which was hinted by the enthalpy of TP adsorption (−37.31 ± 2.04 kJ mol−1) and no detection of new sulfur species.

Effects of the Composition of the Solid Electrolyte Interphase on the Charge-Discharge Performance of a Li Metal Anode in Li[N (CF3SO2)2]-Sulfolane-Based Electrolyte

Lithium–sulfur (Li-S) batterry is a promising alternative energy storage device due to its high theoretical specific capacity, low density, and abundance of sulfur. However, lithium polysulfides (Li2S x ) produced during discharge have been known to dissolve in conventional organic electrolytes, resulting in self-discharge due to the shuttle mechanism. Moreover, the improvement of the Li metal anode is also necessary to realize the Li-S battery. It has been found that the solubility of Li2S x is very low in the solvate ionic liquids (SILs) composed of lithium bis(trifluoromethylsulfonyl)amide (LiTFSA) and tetraglyme (G4, CH3(OCH2CH2)4OCH3).1 We have reported the deposition and dissolution of Li in the SILs with different compositions [2]. Formation of the solid electrolyte interphase (SEI) on the anode in the SILs was analyzed by transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS). Recently, a highly concentrated LiTFSA/sulfolane (SL) is considered as a candidate for the electrolyte of Li-S battery because of the low solubility of Li2S x and fast Li+ conduction caused by the hopping mechanism [3]. In the present study, the charge-discharge performance of a Li metal anode was investigated in a SL-based electrolyte from a point of view of the SEI formation on Li. The electrolyte was prepared by mixing LiTFSA, SL and 1,1,2,2,-tetrafluoroethl 2,2,3,3,-tetrafluoropropyl (HFE) at 20.0-40.0-40.0 mol%. HFE was added to reduce the viscosity of the electrolyte. The SILs were prepared by mixing LiTFSA or LiFSA and G4 at 50.0-50.0 mol%. The water contents in the SL-based electrolyte and SILs were less than 50 ppm, which was determined by Karl Fischer titration. The charge-discharge measurements were conducted using a 2032 coin-type Li|LiFePO4 cell. Celgard 3501 was used as a separator. Li electrode was immersed in LiTFSA-G4 or LiFSA-G4 SILs to form SEI before the measurements. Charge–discharge cycle test was performed at a current density of 0.371 mA cm–2 with a charge density of 1.0 C cm–2. The characterization of SEI on the anode was carried out by TEM and XPS using air-tight transfer holders without exposure to air. The larger polarization and lower columbic efficiency for deposition and dissolution of Li (with the cut-off potential of 2.0 V vs. Li|Li(I)) were observed in the SL-based electrolyte compared with those in LiTFSA-G4 SILs probably due to the inhomogeneous and/or unstable SEI on the anode. On the other hand, the cyclability was improved even in the SL-based electrolyte using the Li electrode immersed in LiTFSA-G4 or LiFSA-G4 SILs for 24 hours before the measurements. In the case of Li immersed in LiFSA-G4 SIL, charge-discharge operation can be achieved for more than 500-cycle. The SEI formed on the anode in the SIL was suggested to be ticker than that in the SL-based electrolyte by TEM observation. The SEI formed in the SILs was considered to work even in the SL-based electrolyte, resulting in the improvement of the reversibility of the Li anode.AcknowledgmentThis study was supported by the Advanced Low Carbon Technology Research and Development of Program (ALCA) of the Japan Science and Technology Agency (JST).Reference K. Dokko, N. Tachikawa, K. Yamauchi, M. Tsuchiya, A. Yamazaki, E. Takashima, J.-W. Park, K. Ueno, S. Seki, N. Serizawa, and M. Watanabe, J. Electrochem. Soc., 160, A1304 (2013).Y. Katayama, N. Tachikawa, and N. Serizawa, 235th ECS meeting, Abst#A02-265, Dallas, (2019). 3. A. Nakanishi, K. Ueno, D. Watanabe, Y. Ugata, Y. Matsumae, J. Liu, M. L. Thomas, K. Dokko, and M. Watanabe, J. Phys. Chem. C, 123, 14229 (2019).

Multi-Reaction Numerical Modeling of Lithium-Sulfur Cells

Lithium-sulfur batteries present a promising alternative to current, widely commercialized lithium-ionbattery technology. Lithium-sulfur batteries take advantage of the high specific capacity (~1675 Ah/kgsulfur)and abundance of sulfur in an attempt to produce lighter, cheaper batteries for portable applications.Despite promising theoretical capacity, commercialization of lithium-sulfur batteries is limited by lowconductivity of cathode end products and low battery cyclability. The first issue requires an electricallyconductive cathode host network, typically carbon, which reduces the specific capacity. The second issueis due to polysulfide shuttling, which can lead to precipitation of insoluble intermediates and loss of activematerial.Current research is largely focused on either preventing the dissolution of intermediate products into theelectrolyte or preventing their migration to the anode where they can be reduced to insoluble species [1-3].Concurrent efforts to reduce the electroltyte/sulfur ratio will maximize the battery’s gravimetric energydensity. For any of these strategies, it is critical to understand and control the impact on the intermediatespecies concentrations in the electrolyte, both to optimize performance and to minimize capacity fade dueto precipitation of species which exceed their solubility limits.The proposed presentation will demonstrate a physico-chemical model of a lithium-sulfur battery withdetailed intermediate chemistry, thermodynamic consistency, and physically derived parameters. Atpresent, most models trade off one or more of these model components for others [4-6]. Model results arevalidated against operando measurements of dissolved polysulfide concentrations in the electrolyte [7,8].Results will demonstrate how C-rate, electrolyte/sulfur ratio, sulfur loading, and cation-selectivemembranes impact cell performance and battery lifetime.Figures 1 and 2 show preliminary model results for varying C-rates. The discharge profiles in Figure 1indicate only moderate losses in potential with increasing C-rate. However, these are associated with ashift toward lower-order, less-soluble polysulfides, as shown in Figure 2, the irreversible precipitation ofwhich leads to capacity fade over multiple cycles. In this manner, the model serves as a quantitative guideto the rational design and operation of next-generation Li-S batteries. In this presentation, we will discussimplications from the model results regarding the battery design and operating strategies to mitigate Li-Sbattery degradation while improving metrics such as gravimetric energy and power density.

Strategy and Issue for Li-S Batteries with High Energy Density

As an inexpensive, abundantly available, and environmental-friendly material, sulfur has become one of the most promising positive electrode active materials because of its high theoretical specific capacity (1675 mAh g-1). However, lithium sulfur batteries (Li-S Battery) still have some issues for practical application: the electronically insulating nature of sulfur and its discharge products (Li2S/Li2S2); the dissolution and shuttle effect of lithium polysulfides (LiPSs) in the conventional dioxolane/dimethoxyethane (DOL/DME) electrolyte. In addition, excess amounts of electrolyte that overcompensate for its minimum requirement are necessary for achieving a high specific capacity of sulfur, which severely reduces the energy density of the battery. However, only poor charge/discharge behavior could be obtained when the E/S ratios lower than 5 with the conventional DOL/DME electrolyte.1 In order to overcome the above problems, we have proposed sparingly solvating electrolytes made with lithium bis(trifluoromethanesulfonyl)amide (Li[TFSA]) and sulfolane (SL), in which LiPSs have limited solubility to inhibit the LiPS shuttling effect. Moreover, to realize high energy density Li-S batteries, it is essential to reduce the E/S ratio (E/S [μL-electrolyte/mg-sulfur]). Here, we fabricated a pouch cell using the sparingly solvating electrolytes and the cyclability with various E/S ratios was studied.The sparingly solvating electrolytes are [Li(SL)2][TFSA] (Li[TFSA] : SL = 1 : 2) in which a poorly solvating diluent, 1,1,2,2,-tetrafluoroethyl-2,2,3,3,-tetrafluoropropyl ether (HFE), was added at different molar ratios. Sulfur cathodes consisted of sulfur and Ketjen black (KB) at a ratio of 3: 1, which are coated on a carbon-coated aluminum foil with carboxymethylcellulose (CMC) and styrene-butadiene rubber (SBR) binders. Pouch cells, which have laminated structures, were prepared using the sulfur cathode, Li metal anode, and Celgard3501 separator. Constant current charge/discharge tests were carried out at cut-off voltage 1.0-3.3 V and at 30 ℃.There were non-negligible differences in electrochemical performances of Li-S batteries between coin cells and pouch cells. Especially, under lean electrolyte conditions (low E/S), only pouch cells gave reasonable results. A high energy density Li-S cell having higher energy density than 300 Wh/kg was successfully demonstrated. Therefore, fabrication of pouch cell is a necessary step to probe the stability of the electrode and to evaluate the electrochemical performances under different low E/S ratios. Fig. 1 shows the capacity retention of Li-S cells with various E/S ratios. Although the initial discharge capacity was almost the same, being independent of E/S ratios. However, the cycle stability significantly deteriorated with decreasing E/S. An internal short circuit due to the dendrite formation also occurred relatively early when E/S < 5. On the other hand, when E/S> 5, a high capacity could be maintained, and an internal short circuit hardly occurred even at the relatively high current density. In pouch cells, the electrode area is generally much larger than that in coin cells. Therefore, the absolute magnitude of current is much higher. As a result, if side reactions between electrolyte and Li anode occur and current density in the cell becomes inhomogeneous, the current concentration in the cell will leads to the dendrite growth. Considering the reduction of E/S is urgent for practical high energy density of Li-S battery, it is necessary to suppress the side reactions and dendrite growth on the lithium anode. By using ab initio molecular dynamics simulations and operando electrochemical mass spectroscopy together with cryo-STEM-EELS techniques, the side reactions between the electrolyte and Li anode were explored. How to reduce the side reactions will be discussed in detail in the presentation.AcknowledgementsThis study was supported by the Advanced Low Carbon Technology Research and Development Program (ALCA) of the Japan Science and Technology Agency (JST). We also appreciate Dr. Keisuke Shinoda for his kind support for Cryo-STEM-EELS measurement at National Institute for Materials Science (NIMS) Battery Research Platform.

High Energy Density Cathode Composite for All-Solid-State Lithium-Sulfur Battery

Lithium-sulfur battery with an all-solid-state configuration is expected to possess high energy density (>1600 mAh/g), safety, and reliability. However, poor ionic/electronic conductivities and a large volume change of sulfur are the problems to be solved to achieve its intrinsic high-potential. Carbon replica (CR) having a three-dimensional pore arrangement within the matrix is a good candidate to design high energy density cathode composite since the high electric conductivity and sufficient pore volume (~2-3 cm3/g) to accommodate a large amount of sulfur [1]. Therefore, sulfur-carbon replica matrix (S-CR) with high sulfur loading rate (80wt.%) is possible theoretically. Also, the incorporated sulfur in the pore (~10-100 nm) could show lower volume changes and smaller resistance for ion diffusion. In the present study, an improved melting method was used to introduce sulfur into CR pores, and the particle size of the sulfur was controlled by simultaneously controlling the particle size and pore size of the CR to improve the sulfur utilization rate.Based on the reported melting method, the powdered S-CR mixture was heated at 155°C for 2h [2]. As an initial step, CRs with different pore sizes (10 and 100 nm; CR10 and CR100) were examined. Furthermore, a vacuum sealing process was conducted before heating to fill the entire mesopores of CR with sulfur. Four kinds of S-CR (S:CR=80:20wt.%) were fabricated to compare their battery performance: (i) the melting method using CR100; (ii) the melting method using CR10; (iii) the vacuum sealing method using CR10; and (iv) the vacuum sealing method using CR10 and particle classification treatment (~10 µm) were used. A lithium superionic conductor of Li10GeP2S12 (LGPS) and Li-In alloy was used as a solid electrolyte and negative electrode, respectively [3]. The S-CR-LGPS composites (S:CR:LGPS=32:8:60wt.%) were fabricated by ball milling. The obtained composites were characterized by SEM, BET, TG/DTA. Electrochemical properties of the composite electrodes were evaluated by the constant current charge-discharge measurements.Initially, we used the reported melting method to fabricate a cathode composite and elucidated the effect of CR pore size to battery performance. A higher capacity was obtained when CR10 was used because the reduction in pore size enables smaller incorporated sulfur size. Since sulfur is an insulator, reducing the size of sulfur can increase the utilization rate of sulfur to obtain a higher capacity [4]. However, when using the reported melting method, a large irreversible capacity (~80 mAh/g) was observed in the first cycle. This indicates that a part of sulfur may exist on the outer surface of the CR, which could show poor reversibility for the reaction. This is due to that the residual gas in the pores prevents the entry of liquid sulfur. Therefore, before introducing sulfur using the melting method, a vacuum step was applied to remove the gas from the pores. As a result, the initial irreversible capacity was decreased to ~10 mAh/g. Then TG, SEM, and BET analysis confirmed the successful filling of sulfur into the CR pores. Nevertheless, since the specific capacity was still smaller than the theoretical capacity of sulfur, the particle sizes of CR and LGPS were adjusted to about 10 µm by a dry classification method before composite fabrication to improve the utilization rate of sulfur. The optimized composite showed a larger capacity of over 1400 mAh/g and its coulomb efficiency was close to 100% after the second cycle. This proves that controlling the particle size of CR and LGPS can improve the utilization rate of sulfur (84%) which results in a higher capacity. The results show that the particle size classification could contribute the constructing the ion/electron pathway in the composite because of better dispersion of each particle. It can be expected that the further optimization of the weight ratio, mixing method, and other conductive additives of the composite electrodes could provide better ion and electron transport paths inside the composite, which lead to better performance. Reference s : [1] J. Power Sources, 2016, 330, 120-126.[2] Energy Technology, 2019, 0, 1900077.[3] Nat Mater, 2011, 10, 682-686.[4] Adv. Energy Mater, 2017, 7.17, 1602923. Figure 1

Stable performance of Li-S battery: Engineering of Li2S smart cathode by reduction of multilayer graphene-embedded 2D-MoS2

Lithium-sulfur (Li–S) batteries are considered promising candidates for next-generation energy storage devices due to their ultrahigh theoretical gravimetric energy density, cost-effectiveness, and environmental friendliness. However, the application of Li–S batteries remains challenging; mainly due to a lack of understanding of the complex chemical reactions and associated equilibria that occur in a working Li–S system. A new approach preparing graphene-based active cathode materials of Li-S battery with spatially confined lithium sulfides is reported. The starting graphene-embedded 2D-MoS2 was synthesized by a solvothermal method in organic solvents followed by the calcination of trapped organic solvent molecules at 800 °C to give graphene single sheets inside the 2D-MoS2 layers with 7 Å distance (MoS2-Gr-32.51). Then, it was electrochemically reduced/lithiated at potential 0.01 V vs Li+/Li generating metallic molybdenum and lithium sulfides. As a result, the structure of MoS2 multi-layers collapsed. The graphene multi-layer (ML-Graphene) was left behind and shut the lithium sulfides between the layers. The sizes of Li2Sn (n = 4–6) are bigger than the inter-layer distance of ML-Graphene, and the escape of sulfur/sulfides from the cathode into the electrolyte is physically blocked alleviating shuttle effects. The specific capacity of ML-Graphene/lithium sulfides cathode was high of 1209 mAh/gMoS2-Gr at 0.1 C (1 C = 670 mA/g). The ML-Graphene exhibited the remarkable lithium intercalation capability, and the theoretical calculation has been carried out to give 2231.4 mAh/g. Such high capacity was hybridized with the theoretical capacity of sulfur (1675 mAh/g), and the ML-Graphene composite with dichalcogenides (2D-MoS2) became a promising platform for the cathode of Li-S batteries.

EFFECT OF MODIFYING ADDITIVES ON CHEMOSORPTION OF SULFUR (IV) OXIDE BY FIBROUS MATERIAL IMPREGNATED WITH POLYETHYLENEPOLYAMINE

The principal possibility of increasing of the absorption capacity of impregnated fibrous chemisorbents (IFCS) acid gases based on nitrogen-containing organic bases by introducing into impregnating solutions of some additives such as sodium chloride, potassium iodide, ethylenediaminetetraacetic acid disodium salt (EDTA), glycine, sodium and potassium carbonates was investigated. Under static conditions using a vacuum sorption unit with McBen-Bakr quartz spring scales the hydrophilicity of fibrous chemisorbents of acid gases based on polyester synthetic fibers impregnated with polyethylenepolyamine containing as modifiers of potassium, such as potassium modifiers, such as promoters sodium and potassium carbonates, glycine and the disodium salt of ethylenediaminetetraacetic acid was studied. It is shown that the introduction of these additives leads to a sharp increase in the hydrophilicity of the samples, which creates the preconditions for further more efficient chemisorption of sulfur(IV) oxide. Within the framework of the Brunauer-Emmett-Teller theory of polymolecular sorption, water vapor sorption isotherms are analyzed, the values of the monolayer capacity and the values of the sorption heat of water molecules in the first layer are determined. Under static and dynamic conditions, chemisorption of sulfur oxide (IV) by dry and moistened samples of chemisorbents was studied. It is established that the process of SO2 chemisorption can occur only in the presence of «free» water formed after the formation of the monolayer. It is shown that the introduction of hydrophilized additives leads to a significant increase in the absorption capacity of sulfur(IV) oxide in both static and dynamic conditions. The obtained results are planned to use in the development of theoretical bases for the creation of functional sorption filtering materials for respiratory purposes.

Probing mesoporous character, desulfurization capability and kinetic mechanism of synergistic stabilizing sorbent CaxCuyMnzOi/MAS-9 in hot coal gas

Developing structurally stable sorbents for high-temperature H2S direct removal is recognized as a valuable energy-saving strategy for efficient utilization of hot coal gas (HCG), which depends upon their mesoporous features and desulfurization capabilities. Herein, tailored hierarchical CaxCuyMnzOi/MAS-9 sorbents were fabricated via a facile sol–gel method using high-activity phase CaxCuyMnzOi anchored onto versatile mesoporous MAS-9. After O/S-exchange procedure, noteworthy straight channels of MAS-9 (SBET = 808 m2 g−1) provided enough available spaces for the storage of generative large MeSy nanoparticles, which was better than other conventional zeolites. The probing of variables (i.e. support type, active ingredient, loadings, and sulfidation temperature) on H2S removal revealed that 50%Ca3Cu10Mn87Oi/MAS-9 shared an excellent breakthrough sulfur capacity (171.57 mg g−1) at 800 °C, even it experienced six reusable cycles, due to synergistic stabilizing effect of Ca-Cu-Mn and high-temperature tolerance of SiOAl framework of MAS-9. Especially, CaO dopant endowed the sorbent with superficial alkalinity and high-temperature resistance. The brilliant desulfurization behavior was also described by the fast H2S diffusion or component deactivation vs. duration time on stream according to the followed kinetic investigation. Thus, the refined Ca3Cu10Mn87Oi/MAS-9 possesses the expected representative desulfurization nature and great potentiality for raw HCG in practical applications.

Polymer electrolytes for Li-S batteries: Polymeric fundamentals and performance optimization

Lithium-sulfur (Li-S) batteries have been considered as one of the most promising candidates to traditional lithium ion batteries due to its low cost, high theoretical specific capacity (1675 mAh g−1) and energy density (2600 Wh kg−1) of sulfur. Compared with traditional liquid electrolytes, polymer electrolytes (PEs) are ever-increasingly preferred due to their higher safety, superior compatibility, long cycling stability and so on. Despite some progresses on PEs, however, there remain lots of hurdles to be addressed prior to commercial applications. This review begins with native advantages for PEs to replace LEs, and then proposes the ideal requirements for PEs. Furthermore, a brief development history of typical PEs for Li-S batteries is presented to systematically summarize the recent achievements in Li-S batteries with PEs. Noted that the structure-performance relationships of polymer matrixes for PEs are highlighted. Finally, the challenges and opportunities on the future development of PEs are presented. We hold the view that composite polymer electrolytes in virtue of the high ionic conductivity and the compatible interfacial property will be promising solution for high performance Li-S batteries.

Enhanced Adsorption Desulfurization Performance over CuCeY Zeolites Prepared by Low‐Temperature Calcination under H2 Atmosphere

AbstractIn order to optimize the location and valence state of metal ions in the Y‐type zeolite, the bimetallic (cerium and copper) modified NaY (CuCeY) zeolites with different Cu/Ce ratios were prepared by calcination at 180 °C under H2 atmosphere. Their adsorptive capacity and selectivity for thiophene were preliminarily explored. Furthermore, the CuCeY zeolites were characterized by various techniques for explaining their adsorption behaviors. The obtained results show that the breakthrough adsorption sulfur capacity (Q) of CuCeY zeolites from model oil contains thiophene (TMO) shows a volcanic tendency with the increase of Cu ion contents in zeolites. This is because more metal ions, especially Cu+ ions, are distributed to the supercages of Y zeolites. When 1‐hexene coexists with thiophene in model oil (TOMO), the Q of CuCeY zeolites increase firstly and then remain almost unchanged as Cu ion contents in zeolites increases. It is related to competitive adsorption, alkylation and oligomerization of thiophene and 1‐hexene. When benzene coexists with thiophene in model oil (TAMO), the Q of CuCeY zeolites are linear with Cu ion contents in zeolites. This is possible because the competitive adsorption between olefins and sulfur compounds on Cu ions or weak Brönsted(B) acid centers are stronger than that between aromatics and sulfur compounds on the same adsorption sites. It′s worth mentioning that the Q values of CuCeY zeolites are larger than that of bimetallic modified CuCeY zeolites and that of most of monometallic modified Y zeolites reported in the references.

Indispensable role of inherent calcite in coal on activated carbon (AC)’s preparation and applications

Calcite (CaCO3) is the main calcium-containing mineral in coal, activated carbons (ACs) were obtained through blending Alxa coal with different content of CaCO3 (2, 4, 6, 8%), molding, carbonization at 600 °C and activation at 900 °C under water–vapor atmosphere. As-derived ACs were investigated physiochemical structure and performance by XRD, SEM, BET, XPS, SO2 and rhodamine-B (RhB) removal test. The results show that: (1) CaCO3 promotes the development of AC’s physiochemical structure and surface chemistry. CaCO3 is beneficial to pore evolution through etching carbon surface, which causing the evolution of micropore/mesopore to mesopore/macropore and/or pores collapse. The total specific surface area and micropore’s specific surface area has decreased from 895 m2/g and 674 m2/g to 671 m2/g and 564 m2/g with CaCO3 addition up to 8%. The total volumes and micropore’s volumes (<2 nm) also decreased from 0.40 cm3/g and 0.33 cm3/g to 0.31 cm3/g and 0.24 cm3/g, respectively. The O/C and π-π* are increased linearly with the addition CaCO3; (2) CaCO3’s addition promotes sulfur capacity through enhancement of pore structure, oxygen-containing functional groups and π-π*. Moreover, the CaO in ACs participates in the desulfurization process and finally forms CaSO4, which further promotes desulfurization, and the mechanism was proposed; (3) CaCO3’s addition slightly decrease the RhB adsorption capacity from 96.7 mg/g to 87.9 mg/g due to competition of OH− with COO−. The results of this work indicate that AC prepared from high-calcium coal is more suitable for desulfurization other than RhB removal.

Polyethyleneimine-functionalized mesoporous carbon nanosheets as metal-free catalysts for the selective oxidation of H2S at room temperature

Nitrogen-functionalized mesoporous carbon nanosheets are designed and constructed by supporting polyethyleneimine (PEI) on mesoporous carbon nanosheets. The carbon nanosheets possess a two-dimensional lamellar structure, interconnected mesoporous framework and highly dispersed PEI with considerable basic sites which work cooperatively to improve the desulfurization capability at room temperature. The appropriate residual pores after PEI loading provide a fast H2S diffusion channel, accessible interfacial area and storeroom for the product. Moreover, the nanosheet structure could shorten the diffusion pathway to promote the reaction kinetics. The nitrogen functional group of PEI as base sites is effective to enhance the interaction with H2S and facilitate its dissociation into HS−, resulting in a high breakthrough sulfur capacity of 13.68 mmol/g. A reaction mechanism by the combination of amine group promoted H2S dissociation and carbon induced O2 activation is proposed. This work raises the possibility of employing nitrogen-functionalized porous carbons as efficient catalyst for H2S selective oxidation.

Recirculating coking by-products and waste for cost-effective activated carbon (AC) production and its application for treatment of SO2 and wastewater in coke-making plant

Utilization of coke-making by-products/wastes and purification of waste gas and wastewater are critical issues for the coke-making industry. Activated carbon (AC) is effective in the removal of various pollutants from gas to aqueous solutions. This paper proposes a feasible and cost-effective approach to produce AC by recirculating coking by-products and waste for pollutants removal in coke-making plant. The results show that AC’s physiochemical structure and its performance could be regulated by altering the coke powder (C) and benzene residue (B)’ addition. Simultaneously addition of C and B slightly promotes AC’s graphitization and has no obvious effect on surface functional groups, and the mechanism was proposed. The sulfur capacity declined obviously with the addition of C and slightly increased with B’s addition, which indicates that about 20% by-products and waste’s addition could achieve similar performance of unmodified AC (51.2 mg/g). As-prepared AC with C and B’s addition could retain coking wastewater’s color and COD removal ability. The engineering practice and implications elucidate the advances and challenges associated with attaining practical, economical, eco-friendly AC production and environmental protection. The objective of this investigation is to explore a scientific basis for better coking by-products and waste utilization and provide an economic sustainability approach through achieves carbon cycle in coking plant for pollutant treatment.

Unsaturated coordination polymer frameworks as multifunctional sulfur reservoir for fast and durable lithium-sulfur batteries

Desirable sulfur electrochemistry strongly relies on host-guest interactions, which calls for rational designs on the surface fine structure of sulfur reservoir materials. Herein, we for the first time, explore the coordinative unsaturation in ferric hexacyanoferrate (FeHCF) for sulfur immobilization and catalyzation towards improved lithium-sulfur (Li–S) batteries. A simple ammonia etching treatment is implemented to selectively remove Fe III –H 2 O moieties, leaving vast coordinatively unsaturated Fe sites with a simultaneous establishment of considerable mesoporosity in the activated matrix (denoted as FeHCF-A). As a sulfur-host, the massive meso-scale channels endow FeHCF-A with abundant active interfaces and ion/mass transfer pathways, while more importantly, the coordinatively unsaturated Fe sites are revealed with higher adsorbability and conversion catalytic activity to polysulfides. Attributed to theses chemical and structural superiorities, the as-developed FeHCF-A enables a fast, stable, and efficient sulfur electrochemistry, e.g., good rate capability up to 5C and excellent cyclability with an ultralow decay rate of 0.024% per cycle over 500 cycles, as well as a commendable areal capacity of 4.5 mAh cm −2 under high sulfur loading. This work affords a new and insightful perspective of coordinative chemistry for material engineering in Li–S batteries as well as other related fields. The synergistically combination of unique porosity and unsaturated active Fe sites of FeHCF-A contributes to enhanced adsorption and rapid catalytic conversion of lithium polysulfides. • Ammonia etching method is firstly implemented to construct coordinatively unsaturated Fe sites. • The coordinatively unsaturated Fe sites contribute to enhanced adsorption and catalytic conversion of lithium polysulfides. • The mesoporosity in FeHCF-A enables the composite electrode with high sulfur loading and areal capacity.