High Sulfur Capacity Research Articles

Improvement on Sulfur Capacity of Cu-Al-Based Desulfurization Sorbents with Various Transition Metal Additives for Coal Derived Synthetic Gas Cleaning.

This study examined the effects of additives to improve the COS absorption capacity of Cu-Al-based sorbents for the integrated gasification fuel cell (IGFC) process. To absorb a small amount of COS, an Al-based precursor was added to the precursor solution for Cu-Al-based sorbents because a high surface area absorber was required. Various transition metals (Zn, Fe, Mn) were used as additives to improve the stability of the Cu-Al-based absorbent. The changes in surface properties and sulfur absorption capacity of the Cu-Al-based absorbent were investigated according to the composition of transition metals. As a result of the sulfur absorption test, the difference in the sulfur absorption capacity of the Cu-based sorbents was confirmed depending on the type of additive, and changes in their surface area. Moreover, the pore characteristics were observed by the nitrogen adsorption method. Sorbents with high surface areas generally have high sulfur capacity, but the additive component has a strong effect. These results can be explained by the transition metal additive binding to Cu to form a composite metal oxide. Furthermore, manganese was found to be suitable for improving the stability and surface area of the copper-based absorbent.

Waste to Wealth: Exhausted Nitrogen-Doped Mesoporous Carbon/MgO Desulfurizers Turned to High-Sulfur-Loading Composite Cathodes for Li-S Batteries.

We demonstrate a sustainable and cost-effective route to fabricate high-sulfur-loading cathode materials with the cooperative interfaces of "sulfiphilic" and "lithiophilic" sites from the removal industry of the pollutant H2S gas. The MgO-impregnated and nitrogen-doped mesoporous carbon composite desulfurizers (NMC/MgO), acting as effective catalysts and large storehouses, could catalytically oxidize H2S into elemental S with high catalytic selectivity and sulfur capacity. The obtained byproduct NMC/MgO/S-CO composites possess high sulfur loading (73.8 wt %) and significant structure advantages for practical application in Li-S batteries. First, the uniform distribution of S in the NMC/MgO frameworks via the in situ catalytic oxidation approach could offer large interface area for charge transport and Li+ reaction. Then, the cooperative effects of the "sulfiphilic" MgO nanoparticles and the "lithiophilic" nitrogen dopants in the NMC/MgO could effectively suppress the polysulfide shuttling. Under the further assistance of physical confinement of the mesoporous NMC/MgO, the NMC/MgO/S-CO composites present excellent electrochemical performances with a high reversible capacity of 772 mAh g-1 and a Coulombic efficiency of 93.6% at the 100th cycle at 0.2 C. These encouraging results not only develop a sustainable way to turn waste into wealth but also provide a promising strategy to product high-sulfur-loading cathode materials with uniform distribution of S through the in situ catalytic strategy for high-performance Li-S batteries.

Rational Design of a Dual-Function Hybrid Cathode Substrate for Lithium-Sulfur Batteries

Reliable sulfur cathodes hold the key to realize high-performance lithium-sulfur (Li-S) batteries, yet the electrochemical inefficiency and instability arising from the poor conductivity of sulfur and lithium sulfide together with polysulfide shuttle remain challenging. Here, a unique three-dimensional (3D) hybrid sponge with chemically coupled nickel disulfide-reduced graphene oxide (NiS2-RGO) framework is rationally developed as an effective polysulfide reservoir through a biomolecule-assisted self-assembly synthesis. An optimized amount of NiS2 (~ 18 wt.%) with porous nanoflower-like morphology is uniformly in-situ grown on the RGO substrate, providing abundant active sites to adsorb and localize polysulfides. The improved polysulfide adsorptivity from sulfiphilic NiS2 is confirmed by experimental data and first-principle theoretical calculations. Moreover, due to the chemical coupling between NiS2 and RGO formed during the in-situ synthesis, the conductive RGO substrate offers a 3D electron pathway to facilitate charge transfer towards the NiS2-polysulfide adsorption interface, triggering a fast redox kinetics of polysulfide conversion and excellent rate performance (C/20 – 4C). Therefore, the self-assembled hybrid structure simultaneously promotes static polysulfide-trapping capability and dynamic polysulfide-conversion reversibility. As a result, the 3D porous sponge enables a high sulfur content (75 wt.%) and a remarkably high sulfur loading (up to 21 mg cm-2) and areal capacity (up to 16 mA h cm-2), exceeding most of the reported values in the literature involving either RGO or metal sulfides/other metal compounds (sulfur content of < 60 wt.% and sulfur loading of < 3 mg cm-2). This integrated hybrid system could be extended to other metal-sulfides and it provides a new possibility to engineer advanced sulfur cathodes for high-performance Li-S technology with a necessary high sulfur loading. Figure 1

Enhancement Effect of Ordered Hierarchical Pore Configuration on SO2 Adsorption and Desorption Process

Carbonaceous adsorbents with both high sulfur capacity and easy regeneration are required for flue gas desulfurization. A hierarchical structure is desirable for SO2 removal, since the micropores are beneficial for SO2 adsorption, while the mesopore networks facilitate gas diffusion and end-product H2SO4 storage. Herein, an ordered hierarchical porous carbon was synthesized via a soft-template method and subsequent activation, used in SO2 removal, and compared with coal-based activated carbon, which also had a hierarchical pore configuration. The more detailed, abundant micropores created in CO2 activation, especially the ultramicropores (d &lt; 0.7 nm), are essential in enhancing the SO2 adsorption and the reserves rather than the pore patterns. While O2 and H2O participate in the reaction, the hierarchical porous carbon with ordered mesopores greatly improves SO2 removal dynamics and sulfur capacity, as this interconnecting pore pattern facilitates H2SO4 transport from micropores to mesopores, releasing the SO2 adsorption space. Additionally, the water-washing regeneration performances of the two types of adsorbents were comparatively determined and provide a new insight into the mass-transfer resistance in the pore structure. The ordered hierarchical carbon promoted H2SO4 desorption efficiency and cycled SO2 adsorption–desorption performance, further indicating that interconnecting micro- and mesopores facilitated the diffusion of adsorbates.

Superior Silver Sorbents for Removing 2-Vinyl Thiophene from Styrene by π-Complexation

Styrene made from raw pyrolysis gasoline contains sulfur impurities such as 2-vinyl thiophene. We prepared three sorbents, namely, AgY, AgNO3/γ-Al2O3, and AgNO3/SiO2, to remove 2-vinyl thiophene from styrene. All three sorbents showed good desulfurization performance while AgY had the highest sulfur capacity. This was due to π-complexation, where the silver cations in AgY can bond 2-vinyl thiophene more strongly than styrene. The desulfurization capacity of AgNO3/γ-Al2O3 was better than that of AgNO3/SiO2 when taking its lower silver loading and surface area into consideration. Moreover, prewetting the sorbents was critical for desulfurization but can cause polymerization. Comparison between desulfurization of gasoline and styrene, using AgY, shows its superior sulfur adsorption capacity for desulfurization of styrene. A possible mechanism on the preferential adsorption for 2-vinyl thiophene over styrene by Ag+ is given via the comparison between thiophene and benzene.

Reactive adsorption desulfurization of thiophene over NiMo/ZnO, a new adsorbent with high desulfurization performance and sulfur capacity at moderate temperature

3Ni7Mo/ZnO adsorbent was synthesized by a two-step impregnation method for reactive adsorption desulfurization (RADS) experiments.

High-sulfur capacity and regenerable Zn-based sorbents derived from layered double hydroxide for hot coal gas desulfurization.

The Zn-Al mixed metal oxide (ZnAl-MMO) with a plate-like structure was derived from Zn-Al layered double hydroxide. The ZnAl-MMO with a Zn/Al molar ratio of 3:1 exhibits superior absorption ability for H2S in a simulated coal gas at 600 ℃ due to the special structure of the ZnAl-MMO. Besides ZnS, elemental sulfur is also produced during the desulfurization process. The deactivation model could well simulate the absorption behavior of H2S. The sulfidation reaction over the sorbent shows large initial reaction rate constants (1110-5390 m3 min-1 kg-1) and low activation energy (29.5 kJ mol-1). The regeneration rate of the used sorbent can reach 99.8% under the optimum conditions. The regenerated sorbents still show high sulfur capacity (ca. 30%), implying its great application potential for industrial-scale desulfurization of the hot coal gas.

Ion‐Selective Prussian‐Blue‐Modified Celgard Separator for High‐Performance Lithium–Sulfur Battery

Application of Li-S batteries has been restricted because of their major problem, that is, shuttling of soluble polysulfides between electrodes, which results in serious capacity fading. For the development of high-performance Li-S batteries, we first time utilize a simple growth method to introduce a Prussian blue (PB)-modified Celgard separator as an ion-selective membrane. The unique structure of PB could effectively suppress the shuttle of polysulfides but scarcely affect the transfer ability of lithium ions, which is beneficial to achieve high sulfur conversion efficiency and capacity retention. The Li-S battery with PB-modified Celgard separator has an average capacity decay of only 0.03 % per cycle at 1 C after 1000 cycles.

Ordered mesoporous Zn-based supported sorbent synthesized by a new method for high-efficiency desulfurization of hot coal gas

A new approach (microwave-hydrothermal plus oxidation) was proposed for the preparation of the Zn-based sorbents supported on the ordered mesoporous Si-based material. The hydrothermal synthesis and oxidation conditions of the sorbent precursor (ZnS/MCM41 mesophase) with Zn(AC)2 and thioacetamide (TAA) as the Zn and S sources, respectively, were optimized. The sorbents were evaluated in a fixed bed using the simulate gas of 2000 ppm H2S, 39% H2, 27% CO, 12% CO2, and N2 as balance gas. The structure of the sorbents was characterized by means of XRD, N2 adsoprtion, SEM, EDX, and TEM analysis. The results indicate that the optimal microwave-hydrothermal conditions are 400 W, 2.5 h, and 1:3 (the mole ratio of the Zn(AC)2 to TAA). The oxidation of ZnS in the sorbent precursor to ZnO is invalid at 550 °C due to unfavorable reaction kinetics. Both the fresh and used sorbents show ordered hexagonal mesoporous structure. It is confirmed that Zn2SiO4 present in the fresh and regenerated sorbents could be consumed during the desulfurization process via the reaction (Zn2SiO4 + 2H2S → 2ZnS + SiO2 + 2H2O), giving a positive effect on the desulfurization of the sorbents. The optimized Zn-based mesoporous sorbent (actual Zn content: 20.3%) exhibits superior (high breakthrough sulfur capacity: 5.4–5.7%) and stable desulfurization ability during five sulfidation/regeneration cycles. In addition, sulifidation reaction only leads to low-degree plugging of the pore structure of the regenerated sorbents, and the regeneration reaction could restore (at least mostly) the aforementioned changes in the pore properties.

Rational Design of a Dual‐Function Hybrid Cathode Substrate for Lithium–Sulfur Batteries

AbstractA unique 3D hybrid sponge with chemically coupled nickel disulfide‐reduced graphene oxide (NiS2‐RGO) framework is rationally developed as an effective polysulfide reservoir through a biomolecule‐assisted self‐assembly synthesis. An optimized amount of NiS2 (≈18 wt%) with porous nanoflower‐like morphology is uniformly in situ grown on the RGO substrate, providing abundant active sites to adsorb and localize polysulfides. The improved polysulfide adsorptivity from sulfiphilic NiS2 is confirmed by experimental data and first‐principle calculations. Moreover, due to the chemical coupling between NiS2 and RGO formed during the in situ synthesis, the conductive RGO substrate offers a 3D electron pathway to facilitate charge transfer toward the NiS2‐polysulfide adsorption interface, triggering a fast redox kinetics of polysulfide conversion and excellent rate performance (C/20–4C). Therefore, the self‐assembled hybrid structure simultaneously promotes static polysulfide‐trapping capability and dynamic polysulfide‐conversion reversibility. As a result, the 3D porous sponge enables a high sulfur content (75 wt%) and a remarkably high sulfur loading (up to 21 mg cm−2) and areal capacity (up to 16 mAh cm−2), exceeding most of the reported values in the literature involving either RGO or metal sulfides/other metal compounds (sulfur content of &lt;60 wt% and sulfur loading of &lt;3 mg cm−2).

Rare earth oxide doping and synthesis of spinel ZnMn2O4/KIT-1 with double gyroidal mesopores for desulfurization nature of hot coal gas

In this work, spinel ZnMn2O4/KIT-1 using KIT-1 with 3-dimensional wormhole-like channels as support was fabricated for hot coal gas desulfurization at high temperature via a sol-gel method. Effects of ZnMn2O4 contents, desulfurization temperature, rare earth oxide doping and steam volume on the desulfurization performances of ZnMn2O4/KIT-1 were investigated systematically. A superior sorbent of ZnMn(Ce)2O4/KIT-1 was obtained with the addition of 45%ZnMn2O4 and doping of CeO2, which was suitable for 550 °C desulfurization and endured a small impact of steam. Moreover, the crystal lattice replace between Ce3+ and Mn3+ facilitated the dispersion of active species and avoided Zn2+ converting to elemental Zn. The high sulfur capacity of ZnMn(Ce)2O4/KIT-1 was maintained after five consecutive desulfurization-regeneration cycles. The textural properties of sorbents were evaluated successively by means of XRD, BET, HRTEM, XPS, H2-TPR and TG/DSC techniques. Results revealed that the main active components in sorbent were robustly existed in form of ZnMn2O4 spinel which effectually prevented the vaporization of Zn in high temperature. Therefore, a low-cost sorbent of ZnMn(Ce)2O4/KIT-1 with the high BSC (171.7 mg S/g sorbent) has an excellent performance for H2S removal from hot coal gas.

Comparison on surface properties and desulfurization of MnO2 and pyrolusite blended activated carbon by steam activation

ABSTRACTIn this study, MnO2 and pyrolusite were used as the catalysts to prepare modified activated carbon, that is, AC-Mn and AC-P, respectively, from coals by blending method and steam activation. The Brunauer–Emmett–Teller (BET) results indicated that the AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The relative contents of basic functional groups (i.e., C = O, π-π*) on AC-P were slightly lower than those on AC-Mn, while both contained the same main metal species, namely, MnO. The desulfurization results showed that with 3 wt% of blending ratio, AC-Mn3 and AC-P3 had higher sulfur capacities at 220 and 205 mg/g, respectively, which were much higher than for the blank one (149.6 mg/g). Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn, which might be attributed to the existence of other metals in pyrolusite. After the desulfurization process, MnO were gradually transferred into MnSO4, and the relative contents of basic functional groups decreased evidently for both AC-Mn3 and AC-P3. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurization.Implications: MnO2 and pyrolusite were used as the additives to prepare modified activated carbon from coals by a blending method and by steam activation, that is, AC-Mn and AC-P, respectively. The AC-P had higher surface areas and micropore volumes than the AC-Mn with the same blending ratio. The AC-Mn and AC-P had higher sulfur capacities than a blank one. Moreover, the AC-P had relatively higher sulfur capacity than the AC-Mn with the same contents of Mn. The results demonstrated that pyrolusite could be one good alternative to MnO2 to prepare modified activated carbon for desulfurizatio.

One-step strategic synthesis of x%Ni–AlSBA-15 sorbents and properties of high adsorption desulfurization for model and commercial liquid fuels

Hexagonally mesoporous 5–30%Ni-AlSBA-15 (30) sorbents were prepared by one-step strategy synthesis and the adsorptive desulfurization performances were investigated in a fixed bed adsorber via model and commercial liquid fuels at ambient pressure. The highest sulfur capacity (17.46 mg-S/g-sorbent) over 20%Ni-AlSBA-15 (30) correlated closely with high Lewis acid sites and larger SBET of 20%Ni-AlSBA-15 (30). The characterization results of N2 adsorption, FT-IR, Py-FT-IR, ICP, HRTEM, EDXA, small- and wide-angle XRD revealed that aluminum or nickel atoms could enter effectively the Si-O-Al (or Ni) framework of SBA-15 and were randomly dispersed highly on the hexagonal pore walls of SBA-15. The hexagonal p6mm symmetry mesoporous structure of 20%Ni-AlSBA-15 (30) still remained intact after four successive desulfurization/regeneration cycles, indicating that 20%Ni-AlSBA-15 (30) presents ultrahigh structural stability and regenerable ability. As comparison, SBA-15 and AlSBA-15 (SiO2/Al2O3 = ∞, 100, 50, 30, 20, 10) were also prepared and evaluated on physical properties.

Desulfurization by MOFs as Sorbents for Thiophene Sulfides

Metal-organic frameworks UMCM-150 [Cu3(BHTC)2] and its heterobimetallic analogue Co1Cu2(BHTC)2 based on an asymmetrical ligand, biphenyl-3,4’,5-tricarboxylate (H3BHTC), were studied for desulfurization of model oils. The adsorption experiments were conducted under room temperature and atmospheric pressure. The total sulfur concentration of model oils was 250 ppmw determined by WK-2D coulomb integrated micro-analyzer through adding benzothiophene (BT) and dibenzothiophene (DBT) into liquid alkanes. Adsorptive desulfurization experiments were conducted in a consecutive fixed bed adsorption system. The results indicate that Cu3(BHTC)2 has a higher sulfur-capacity than Co1Cu2(BHTC)2. Taking DBT as an example, Cu3(BHTC)2 and Co1Cu2(BHTC)2 have breakthrough adsorption capacities of 10.6 and 5.8 g S/kg of sorbent for model oils.

Desulfurization of Hot Coal Gas over Regenerable Low-Cost Fe2O3/Mesoporous Al2O3 Prepared by the Sol–Gel Method

Low-cost Fe-based sorbent supported on mesoporous alumina (Fe2O3/Al2O3) was prepared by the sol–gel method. The performance of sorbents was evaluated at 500 °C over a fixed-bed reactor. A mixture of SO2, O2, and N2 in various proportions was used to regenerate the sorbents after desulfurization. The structure of sorbents before and after desulfurization was characterized using N2 adsorption, XRD, SEM, and XPS techniques. The results indicate that high sulfur capacity (12.5%) and utilization rate (88.6%) of Fe2O3 are achieved for the sorbents (35% Fe2O3) calcinated at 500 °C for 3 h. The sorbents should be regenerated at above 500 °C due to the formation of Fe2(SO4)3 at low temperature, while increasing regeneration temperature from 600 to 650 °C leads to a decrease of the regeneration rate resulting from the production of Al2(SO4)3 and Al3Fe5O12. The main sulfur-containing regeneration product is elemental sulfur under the optimum regeneration conditions. γ-Fe2O3 and α-Fe2O3 coexist in the regenerated sor...

Preparation of walnut shell-based activated carbon and its properties for simultaneous removal of H2S, COS and CS2 from yellow phosphorus tail gas at low temperature

Walnut shell-based activated carbon (WSBAC) was prepared used to simultaneously remove H2S, COS and CS2 from yellow phosphorus tail gas and closed carbide furnace tail gas. The influences of different preparation conditions (carbonization temperature, activating agent species, activating agent content, activation temperature) on the simultaneous removal efficiency of H2S, COS and CS2 were investigated. The results showed that the WSBAC carbonizated at 600 °C, then activated with 0.5 times KOH at 700 °C had the highest sulfur capacity (52.67 mgS/gWSBAC). The structure and surface properties of the catalysts were characterized by Brunauer–Emmett–Teller (BET) method, and the results showed that the high BET surface area (484.26 m2/g), high micropore volume (0.261 cm3/g) and more pore sizes of 0.3–1.8 nm were conducive to the simultaneous removal of H2S, COS and CS2. X-ray photoelectron spectroscopy results showed that the most of products on the exhausted WSBAC were S/SO4 2− species which accumulated on the WSBAC’s surface and had a negative effect on the adsorption activity.

Hot Coal Gas Desulfurization Using Regenerable ZnO/MCM41 Prepared via One-Step Hydrothermal Synthesis

ZnO/MCM41 sorbents with bimodal pore structure were prepared via one-step hydrothermal synthesis. The structure of fresh, sulfided, and regenerated sorbents was characterized using XRD, TEM, SEM, nitrogen adsorption isotherms, and XPS techniques. The results indicate that the desulfurizer with 35% ZnO shows the highest sulfur capacity (11.0 g of S/100 g of sorbents). The optimum regeneration conditions were 650 °C, 3000 h–1, and 6% O2 concentration. Both ZnO and ZnSiO4 were observed in the regenerated sorbents. The increase of regeneration cycles leads to higher content of the Zn2SiO4. However, it results in no significant effect on the performance of sorbents during five sulfidation/regeneration cycles. It may be due to the transformation of Zn2SiO4 into ZnO under conditions of desulfurization. After five successive sulfidation/regeneration cycles, the sorbents still maintain high sulfur capacity (9.8 g of S/100 g of sorbents) and mechanical strength (80 N/cm).

Desulfurization and Regeneration Performance of Titanium-Ore-Modified Activated Coke

In this study, the modified activated coke (AC-Tit) was prepared from coals using titanium ore by the blending method with a one-step carbonization–activation process. The results show that the addition of titanium ore affects the physicochemical properties of AC-Tit. The AC-Tit samples have higher Vmic and Vmic/Vtot ratios as well as oxygen and C═O functional group. The metal oxides (i.e., FeTiO3, TiO2, Fe2O3, and Fe) were detected on the surface of samples, attributed to the existence of Fe and Ti in the titanium ore. The titanium ore addition improved the desulfurization performance of the AC-Tit effectively; the highest sulfur capacity was 203.3 mg/g, which was much higher than that of the blank sample (120.1 mg/g). After desulfurization, some metal sulfates, i.e., Fe2(SO4)3 and CaSO4, were detected on the AC-Tit samples. When the sample was regenerated, its surface area (SBET) and Vmic did not change significantly, the relative content of C═O decreased, and COOH increased evidently. In addition, meta...

Effect of different precursor species on the metal dispersion of a Ni/\u03b3-Al2O3 adsorbent for sulfur adsorption

Nickel adsorbents supported on the γ-Al2O3 with different nickel precursor species were prepared by the incipient impregnation method to investigate the influence of different precursor species on the metal dispersion and the sulfur capacity of the adsorbents. The adsorbents were characterized by N2 adsorption–desorption, H2 temperature-programmed reduction (TPR), transmission electron microscopy (TEM), O2–H2 chemisorption, and FT-IR of adsorbed pyridine. The sulfur adsorption performance was investigated at ambient temperature and pressure. The results showed that adsorbent’s metal dispersion and sulfur capacity were influenced significantly by the metal precursor species. The adsorbents prepared by nickel nitrate exhibited higher sulfur capacity and metal dispersion compared to the adsorbents prepared by nickel formate and nickel acetate. The higher performance of adsorbent prepared by nickel nitrate can be mainly attributed to the relatively more uniform metal dispersion and the smaller particle size of the nickel particles. This study demonstrates that the precursor species is an important factor for affecting the adsorption performance and provides a novel design idea of high metal dispersed catalysts.Graphical abstract

Nitrogen-doped mesoporous carbon nanosheets derived from metal-organic frameworks in a molten salt medium for efficient desulfurization

In this work, we report a novel synthesis of two-dimensional (2D) N-doped mesoporous carbon nanosheets (NMCS) with high nitrogen content and developed porosity from microporous Zn-based zeolitic imidazolate framework (ZIF-8) polyhedrons in a molten salt medium. The ZIF precursors allow high nitrogen content of the NMCS while the molten salt medium leads to the formation of 2D nanosheets with mesoporosity during the pyrolysis process. The obtained NMCS exhibit highly catalytic activity in the metal-free catalytic oxidation of H2S toward elemental sulfur at room temperature, high breakthrough sulfur capacity is achieved over NMCS, much superior to that of ZIF-8 derived N-doped porous carbons obtained by direct pyrolysis. The transformation of three-dimensional ZIF-8 into nitrogen-doped 2D carbon nanosheets via molten salt media has great potential for the large-scale and green production of porous carbon nanosheets for highly efficient desulfurization and energy storage-conversion.