Sulfur Capacity Research Articles

Investigation on the desulphurisation process by powder injection during RH refining process of non-oriented silicon steel

In the present study, the desulphurisation process by powder injection during RH (Ruhrstahl-Heraeus) refining process was studied by establishing a kinetic model. The predicted results by the model were compared with experimental data obtained from industrial trials to verify its accuracy. The effects of the desulphuriser particle diameter, desulphuriser composition and powder injection rate on the desulphurisation process were analysed and discussed. Results show that the desulphuriser particle diameter and powder injection rate considerably affected the desulphurisation process. By decreasing the desulphuriser particle diameter and increasing the powder injection rate, the reaction area between desulphuriser particles and liquid steel considerably increased. Therefore, the desulphurisation rate and ratio increased. When the desulphuriser particle diameter decreased from 3.0 to 0.1 mm, the desulphurisation ratio increased from 44.6% to 88.4%. The ratio increased from 32.8% to 62.2% for 3.0 mm desulphuriser particles when the powder injection rate increased from 100 to 250 kg min−1. Furthermore, an increase in the desulphuriser basicity and CaO/Al2O3 ratio improved the sulphur capacity and accelerated the desulphurisation process. The desulphuriser used herein had a low sulphur partition ratio, and thus it yielded a lower desulphurisation ratio than the CaO-SiO2-Al2O3 desulphuriser.

Medium and high temperature H2S removal via phosphazene polyoxometalate ionic liquids: Performance evaluation and mechanism exploration

The development of non-aqueous solvent desulfurizer is crucial to addressing the challenges associated with traditional liquid-phase wet desulfurization technologies. Based on this, we prepared a series of phosphazene polyoxometalate ionic liquids (PPILs) based of 1-butyl-3-methylimidazolium chloride using different kinds of phosphazenes (PNs) combined with polyoxometalate (POM), and used for hydrogen sulfide (H2S) dynamic absorption experiments. The effects of PN type and ratio, temperature and desulfurizer concentration on the desulfurization performance of different PPILs were explored. Among them, PPILs@IBuPN-9 as the optimal desulfurizer could keep almost 100 % desulfurization efficiency in the medium and high temperature range (100–200 °C). The results showed that the combination of PNs with POM significantly improved and widened the H2S removal performance and the operational temperature window of the desulfurizer. Besides, PPILs@IBuPN-9 required only air regeneration to maintain relatively stable cycle performance for at least four times and the sulfur capacity could be efficiently increased during multiple regenerations. It was found that the hydrogen bonding sites on IBuPN network formed significantly enhanced the H2S capture ability of PPILs and the sulfur capacity was substantially improved by S2− substitution of oxygen atoms in the POM according to the characterization results and density functional theory calculations. This study promotes the deep integration of polyoxometalate chemistry with ionic liquids in the field of gas purification and promotes the development of non-aqueous phase desulfurization process.

Sulfur fixation performance of calcium-bearing carbonates in iron ore roasting process: Thermodynamics, phase transition, microstructure evolution, and kinetics

Roasting technology is increasingly used in the beneficiation of refractory iron ores. During the roasting process, the presence of pyrite in some iron ores leads to the formation of SO2, requiring effective sulfur fixation techniques. This study proposed an innovative in-situ sulfur fixation method by pre-oxidation roasting, in which sulfur was fixed during the oxidation roasting process before reduction roasting. The effects of the main iron mineral (hematite), primary gangue mineral (quartz), and common calcium-containing carbonate minerals (calcite and dolomite) on sulfur migration during pyrite roasting were investigated, with particular emphasis on the sulfur fixation capabilities of calcite and dolomite. The study included thermodynamic equilibrium analysis, phase transitions and microstructural evolution in different reaction systems. The results showed that calcite and dolomite effectively reduced SO2 emissions by forming CaSO4 and MgSO4, with calcite exhibiting a stronger sulfur fixation capacity for the same mass. Kinetic analysis indicated that pyrite pyrolysis followed a two-step random nucleation and growth model. Furthermore, the addition of calcite increased the apparent activation energy of SO2 formation and altered the reaction pathway, providing insight into the sulfur fixation mechanism of calcite from a kinetic perspective.

Single-Atom Cobalt Catalyst with Boron and Nitrogen Codoped Graphene (Co-BN-G) Enables Adsorption and Catalytic Conversion of Polysulfides for High-Performance Lithium-Sulfur Batteries.

In lithium-sulfur batteries, the shuttling effect and sluggish redox conversion of soluble polysulfides lead to unsatisfactory sulfur utilization and capacity retention. In this research, we used a one-pot hydrothermal method to prepare graphene with single-atom Co and B, N codoped as a sulfur host in Li-S batteries, thereby suppressing the shuttling effect and facilitating the redox conversion of lithium polysulfides (LiPSs). A series of characterizations demonstrated that dual doping of B and N introduces more lattice defects and structural deformations in graphene oxide, thus enhancing its adsorption of polysulfides. Simultaneously, single-atom cobalt can also polarize adsorption and accelerate the conversion reaction of LiPSs. The Li-S cell with the as-prepared Co-BN-G sulfur host materials exhibited an excellent capacity of 1034 mAh g-1 at 0.5 C and satisfactory cycle performance (retention of 69% over 500 cycles). Even at a rate of 2 C, a discharge capacity of 851 mAh g-1 is achieved. The results show that the Co-BN-G configuration efficiently captures LiPSs and enhances their rate conversion kinetics in redox reactions, demonstrating significant practical potential.

Porous activated carbon integrated carbon nitride nanosheets as functionalized separators for the efficient polysulfide entrapment in Li[sbnd]S batteries

Electrification of vehicles, hybrid aircraft and the advancement of portable electronics are exacting the deployment of high energy-dense batteries. The high theoretical capacity of sulfur (1675 mAh g−1), cost-effectiveness and environmental benignity of the lithium‑sulfur batteries (LSBs) are propitious for electrochemical energy storage beyond Li-ion battery technology. In this work, we described a simple, scalable preparation and electrochemical performance of porous activated carbon (PC)-infused graphitic carbon nitride (GCN) nanosheets with various ratios (PC@GCN 11, PC@GCN 12 and PC@GCN 21) as a polysulfide anchoring functionalized separator for LSBs. The high specific area (822 m2/g), hetero porosity, conductive carbon framework, surface functionalities and enriched N-doping of the PC@GCN synergistically induce mitigation of polysulfides via chemical and physical adsorption pathways in LSBs. The PC@GCN 21 modified separator demonstrates a high initial discharge capacity of 1389 mAh g−1 at a 0.1C rate and exhibits better capacity retention over 500 cycles at a 1C rate (655 mAh g−1) with sulfur loading of 3.8 mg/cm2 accompanied by high coulombic efficiency (94 %). The assembled cell with high S-loading (5.12 mg/cm2) shows a high initial discharge capacity of 712 mAh g−1 at 0.1C rate conditions. High Li-ion transference number (0.714), stable shuttle current, minimal coulombic efficiency loss (0.84 %), low shuttle factor and negligible self-discharge behaviour support the superior performance of the PC@GCN 21 coated cells. This report demonstrates that combining the high surface area, non-polar porous carbon with polar graphitic carbon nitride is a practical approach for designing metal-free functionalized separators for energy-dense LSBs.

Enhancement and sulfur poisoning mechanism of Ce doped ZrO2 catalyst in COS hydrolysis at low-temperature

In order to achieve efficient and longer-lifespan removal of carbonyl sulfide (COS), a high-performance catalyst for hydrolysis is needed urgently. In this study, Ce doped ZrO2 oxides are used to remove COS with or without H2O. The results showed that the doping of Ce significantly improves the removal of COS by ZrO2 and obtains a sulfur capacity of 155.4 mgS/g at 70 °C, but there is still accompanied by sulfur poisoning. The characterization reveals that CeO2 has a cubic phase, ZrO2 has a mixed phase of tetragonal and monoclinic, and Ce-doped Zr with different ratio of Ce/Zr forms a Ce-Zr solid solution. Ce and Ce-Zr oxides have Ce3+/Ce4+ pairs, adsorbed oxygen species and surface oxygen vacancies, while ZrO2 has adsorbed oxygen and surface oxygen vacancies, the presence of which can promote the dissociation of H2O and surface adsorption of COS. ZrO2 has abundant medium-strong basicity while CeO2 has abundant weak and strong basicity, and different proportions of Ce/Zr adjust the surface basic strength, basic amount and surface redox property of Ce-Zr solid solution, which changes the adsorption and hydrolysis of COS and H2O and related oxidation reactions on Ce and Zr, thereby changing the sulfur poisoning. Ce has abundant –OH groups, which can rapidly adsorb COS, leading to hydrolysis and direct oxidation of COS in the absence of H2O, while the OH groups on ZrO2 promote the hydrolysis of COS to H2S. Although suitable Ce-doped ZrO2 improves the removal efficiency of COS, it still inevitably leads to the sulfur poisoning, but the presence of Zr could change the sulfation degree of CeO2 and the Claus reaction.

A novel method for gas-solid contact visualization and efficiency quantification in dry fixed-bed desulfurization

A novel method for the visualization of gas–solid contact states and the quantitative evaluation of contact efficiency in the dry fixed-bed desulfurization process is proposed in this study. This method utilizes the chromogenic properties of phenolphthalein (PP) on the surfaces of various sodium salt products during the sodium bicarbonate dry desulfurization process, enabling visualization of gas–solid contact status. Samples of desulfurization products are photographed, and ImageJ software is employed for image processing to calculate color residual rates, thereby quantifying gas–solid contact efficiency. The specific operating conditions that produced the best visualization effect of gas–solid contact states were determined through experimentation, including: an appropriate PP solid content of ≤ 0.336 % for ultrafine NaHCO3 with D90 = 6.14 μm; a steam volume ratio of approximately 13.94 % to 24.46 %, a temperature inside the reactor of 110 °C–175 °C. Moreover, the fading effect of the indicative sodium-based absorbent was consistent across SO2 concentrations from 850 mg/m3 to 5100 mg/m3, with higher concentrations reducing the time needed for visualizing gas–solid contact and quantifying efficiency. The gas–solid contact efficiency (Egs = 87.85 %) calculated by the method showed a small deviation of only 0.55 % from the efficiency (E’gs = 88.4 %) calculated based on sulfur capacity, validating the method’s reliability. The study’s outcomes present a novel method for analyzing the gas–solid contact state, which can serve future efforts in the design optimization of dry fixed-bed desulfurization reactors.

Sheet-assembled Zn-based sorbents towards highly efficient desulfurization of hot coal gas: H2S-absorption/COS-release behavior and sulfur-release inhibiting mechanism

It is still challenging to obtain high-temperature sorbents with strong abilities of absorbing H2S and suppressing COS-release during coal-gas desulphurization process. Furthermore, the related inhibiting mechanism is unclear. Herein, functional Zn-based sorbents, with HTLCs (hydrotalcite-like compounds) as the precursor, were designed and fabricated via microwave-assisted co-precipitation method. Doping of metals (Mo/Ni/Co) with function of catalyzing COS-hydrogenolysis was proposed for sorbent modification. The resultant sorbents exhibit hierarchical structure self-assembled from nanosheets. As expected, Mo-, Ni-, and Co-doping result in significant decrease (by 78 %–85 %, 83 %–90 %, and 59 %–74 %, respectively) in the amount of released COS for sorbents. Moreover, Ni-doping generally causes the smallest negative effect on H2S-uptake behavior. It is related to a decline (by about 40 %) in the length of laminas unit and more porous structure of sorbents because of Ni-doping. Especially, the sorbent with the lowest Ni-doping ratio shows high sulfur capacity (27.1 g S/100 g sorbent, desulfurization efficiency: > 99.5 %) and low COS-release amount (1.5 × 10−3 g COS/100 g sorbent). More importantly, it also maintains relatively stable performance over successive sulfidation-regeneration cycles. In addition, the analysis of COS-hydrogenation behavior over individual components in desulfurizers reveals that the doped metals greatly accelerate the COS-hydrogenolysis reaction, responsible for less COS emission of modified sorbents.

Experimental study on the preparation of desulfurizer for low temperature dry desulfurization by digesting CaO in urea solution

Calcium hydroxide (Ca(OH)2) with outstanding sulfur dioxide (SO2) adsorption properties was synthesized through the utilization of calcium oxide (CaO) with a urea solution via a digestion method. This innovative calcium-based desulfurizer aims to meet the needs of low-temperature dry flue gas desulfurization in the steel industry. Fixed-bed experiments were conducted to investigate the impact of different water-ash ratios, urea solution concentrations, and digestion time on the desulfurization efficiency and particle structure of the desulfurizers. Sample CAC-2–0.1 U exhibited outstanding desulfurization performance, achieving 100 % removal efficiency, a sulfur capacity of 34.64 mg/g, and a breakthrough time of 142.6 minutes under target flue gas conditions. The sample also displayed a high specific surface area of 22.10 m2/g and demonstrated adaptability under varying operating conditions. Characterization and reaction mechanisms of the desulfurizer were studied using XRD, SEM, BET, XPS, ICP-OES, and Materials Studio software. Experimental data was analyzed through pseudo-first-order and pseudo-second-order kinetic equations, and intra-particle diffusion model. The product's strong adsorption capacity for SO2 positions it as a highly promising adsorbent for controlling low-temperature flue gas emissions in the steel industry.

Study on the adsorption performance and regeneration of lignin-derived graphitic carbon for H2S

In pursuit of effective adsorption materials for malodorous gases such as H2S and to broaden the utilization avenues of lignin waste, this study employed the direct pyrolysis method to synthesize three types of alkali lignin graphitized carbons, namely C-800, KC-700, and KEC-700. Among them, KEC-700 exhibits a high specific surface area of 1672.9 m2/g, significantly superior H2S adsorption performance compared to other materials, an adsorption breakthrough time of up to 220 min, and a sulfur capacity of 67.1 mg/g. Structural analysis showed that the more oxygen-containing functional groups of lignin charcoal and the larger specific surface area facilitated the adsorption of H2S. After reaching adsorption saturation, the degree of graphitization of lignin carbon diminishes. The H2S adsorption products primarily manifest as elemental sulfur and sulfate within the pores of lignin carbon measuring less than 2 nm. Through thermal regeneration, the charcoal effectively eliminates the elemental sulfur adsorption product. Nevertheless, sulfate removal proved unsatisfactory, as the adsorption efficiency of KEC-700 following two thermal regenerations was approximately 41% of that observed for fresh samples.

Carbon Nanosheet Preparation By Low-Temperature Two-Step Carbonization: A Study of Their Properties and Mechanism of Adsorption of Oxidized H2S.

Straw, as a kind of biomass waste, has the advantages of low cost and abundant storage, which makes it a promising renewable resource. Using rice straw as a carbon source, carbon nanosheets were prepared by a two-step carbonization method combining low-temperature pyrolysis and low-temperature hydrothermal, and they were used as H2S removal agents. The results showed that during the two-step carbonization process, the adsorption performance of carbon nanosheets for H2S showed a tendency of enhancing and then weakening with the increase of pyrolysis temperature in the first step, and the sulfur capacity could reach 3.1 mg/g at the maximum of the pyrolysis temperature of 200 °C, which was superior to or close to that of the modified or activated carbon. The XPS, EPR, and CO2-TPD tests showed that the surface of carbon nanosheets was alkaline, containing a large number of hydroxyl groups and the presence of phenoxy persistent free radicals or semiquinone persistent free radicals. It was analyzed that the direct or indirect oxidation of H2S by the persistent radicals under an alkaline environment could convert the -2-valent sulfur into -1-, 0- and +6-valent sulfur to realize the adsorption and removal of H2S. This work, while offering the possibility of utilizing carbon nanosheets made from straw as a material for H2S adsorption and removal, also expands the application of straw waste in exhaust gas treatment.

Synergistic Electrocatalyst-Cathode Architecture for Stable Long-Term Cycling Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are a promising candidate for next-generation energy storage owing to the high theoretical capacity of sulfur (1,675 mAh g−1). However, the intrinsically low electrical conductivity of sulfur and complex multistep electrolyte-mediated redox reactions involving soluble lithium polysulfide intermediates engender critical challenges toward practical realization. Specifically, migration and diffusion of higher-order lithium polysulfides provokes continuous loss of active sulfur species, yielding premature capacity fade. Electrochemical kinetics also remain sluggish due to the insulating nature of sulfur cathodes, which require engineering designs to accelerate charge transfer.Rational morphological and compositional cathode tuning represents a compelling strategy for addressing fundamental Li-S limitations. Herein, we develop an extended cathode architecture composed of a porous carbon nanotube network decorated with homogenously dispersed nanocatalysts. Electron microscopy and spectroscopy analysis verify platinum group metals are well-incorporated both within internal channels and external surface sites of conductive carbon nanotubes. The composite framework affords multifaceted functionality arising from synergistic chemical and structural attributes of components. Nanocatalyst sites demonstrate a pronounced chemical affinity toward soluble polysulfide intermediates, effectively localizing them within cathode, minimizing diffusional losses toward the anode. This anchoring phenomenon is complemented by the inherent microporosity of the high-surface-area nanotube network, further obstructing polysulfide migration through a confinement effects. Concurrently, noble metal nanoparticles facilitate the redox conversion of trapped higher-order polysulfides into solid Li2S alleviating the precipitation of electrically insulating discharge products. The excellent electrical conductivity of CNTs ensures efficient charge transport to all incorporated sulfur active materials, further maximizing reversible utilization.As a result of complementary polysulfide confinement and electrocatalytic conversion functionalities, Li-S coin cells exhibit enhanced reversible capacities exceeding 900 mAh g−1 for over 500 cycles at 0.558 A g−1. Notably, over 500 cycles, minimal capacity decay of 0.018% per cycle and 92% retention of the initial capacity are obtained at moderate sulfur loadings highlighting the exceptional cycling stability enabled by engineered cathodes. Outstanding rate performance is also demonstrated with the delivery of 854 mAh g−1 capacity at a very high current density of 1.675 A g−1. Our rationally designed cathode architecture provides critical mechanistic insight toward addressing fundamental bottlenecks to progress Li-S technologies.

Constructing Ni/ZnMOx composite metal oxide adsorbents with excellent desulfurization capacity and thermal stability for reactive adsorption desulfurization

For a long time, Ni/ZnO reactive adsorption desulfurization adsorbent have suffered from low desulfurization performance and poor regeneration efficiency. In this paper, a series of Ni/ZnMOx composite metal oxide adsorbents are prepared by introducing the third metal M (Mn, Co, Mo) into ZnO to enhance their sulfur capacity and thermal stability. By employing DFT calculation, the feasibility of forming composite metal oxides in terms of thermodynamics is confirmed. The formation mechanism of composite metal oxides ZnMOx are finely investigated by XRD and TG-MS. Thanks to the unique structure of ZnMOx, the particle size and thermal stability of ZnO-based adsorbents are improved prominently. Experimental results demonstrate that the addition of the third metal can promote the desulfurization performance. It’s important to note that the desulfurization rate of NZCo and NZMo remains above 98% after high temperature calcination. Through characterizing the adsorbents before and after reaction, the desulfurization reaction mechanism for the Ni/ZnO adsorbent doped with metal M (Mn, Co, Mo) has been proposed. In this mechanism, Ni mainly acts as the desulfurization active centre, while ZnO and the generated composite metal oxides play the role of sulfur adsorbents. This study will provide a new idea for the rational design of conventional Ni/ZnO adsorbent to improve its desulfurization performance and thermal stability.

CuY@NiAl-Layered double oxides bi-functional composites for “Catalytic–Adsorptive” removal of carbonyl sulfide

Carbonyl sulfide (COS) removal processes, typically containing catalytic hydrolysis and subsequent capture of hydrogen sulfide (H2S) generated, are energy-intensive and of high complexity. Bi-functional materials with the capability for synergistic catalytic conversion of COS and subsequent adsorption capture of H2S can enable effective removal of COS at low energy cost. Here, we report the development of a bi-functional CuY@NiAl-LDO composite material with integrated catalytic conversion of COS and adsorptive separation of H2S with high efficiency and stability. Fundamental material characterizations elucidate that the CuY@NiAl-LDO composite materials feature a core–shell structure. Coupled dynamic breakthrough experiments and DFT simulations highlight the unique synergistic “catalytic–adsorptive” effect between CuY and NiAl-LDO in the COS removal processes. Specifically, compared with the pure zeolite CuY and NiAl-LDO, the CuY@NiAl-LDO composites present significantly higher COS removal performance. The highest degree of desulfurization was observed on CuY@NiAl-LDO(46 %) at 80 °C with a breakthrough sulfur capacity of 20.57 mg-S/g and no detectable H2S in the outlet gas. In sum, this study highlights the synergistic “catalytic–adsorptive” mechanism of the bi-functional CuY@NiAl-LDO core–shell composite in desulfurization. The insights obtained may benefit chemical engineers by providing a new strategy for the development of multi-functional desulfurization materials.

Carbon nanofibers supported sorbents with enhanced performance via microwave-assisted in-situ structural modifications for H2S removal

The construction of sorbent with excellent structure and highly dispersed active components is vital to improving its desulfurization activity. Herein, the Fe nanoparticles/carbon nanofibers (Fe/CNFs) desulfurization sorbents were fabricated via electrospinning, template method and microwave carbonization. The structure of sorbents was successfully regulated with the adjustments of Fe content and the types of sacrificial phases. It was found that the Fe content impacted strongly on both structural and desulfurization performance of the sorbents. The sorbents with various Fe contents showed a trend of first increasing and then decreasing with the increased Fe content in breakthrough sulfur capacity. Among the various samples, the sample with the highest sulfur content was 7.21 g S/100 g sorbent. Furthermore, the Fe/CNFs sorbents were optimized via soft and hard template methods, by taking polymethyl methacrylate (PMMA) and SiO2 nanospheres as sacrificial phases. Desulfurization tests implied that the PMMA and SiO2 modified sorbents involved sulfur capacity of 13.76 and 14.18 g S/100 g sorbent, respectively. According to the characterizations, the modified sorbents were imparted with micro- and open-type macro-porous structure, respectively, upon which, the active components were uniformly dispersed and exposed. The excellent performance of sorbent could be attributed to the synergistic effect of porous structure and widely distributed Fe nanoparticles on CNFs. This work highlights new strategy for the synthesis of desulfurization sorbent.

Waste to wealth: Efficient wet desulfurization of electric arc furnace dust (EAFD) and recycling of desulfurization solid residue

In this study, we used calcined hazardous waste electric arc furnace dust (EAFD) as a desulfurizer for an effective wet desulfurization process. Testing for desulfurization efficacy revealed that the calcined EAFD, particularly when treated at 800 °C in an oxygen (O2) environment (termed EAFD-O2), achieved an unprecedented breakthrough sulfur capacity (BSC) of 3.71 gSO2·g−1 at 55 °C-the highest to date for EAFD applications in desulfurization efforts. Further investigation indicated that the calcination method expels certain volatile contaminants, thereby enhancing the crystallinity and lattice oxygen content of zinc oxide, the strong active phase of desulfurization in EAFD, which is principally responsible for the superior desulfurization results of EAFD-O2. Moreover, the observed reduction in the desulfurization slurry’s activity primarily stems from the depletion of the strong active phase of desulfurization (ZnO) and the resultant rise in the liquid phase’s sulfate concentration. Notably, the deactivated slurry’s solid residue predominantly consists of high-purity ZnFe2O4, a form of zinc ferrite utilized extensively for its proficiency in photocatalytic. Following straightforward processing, this substance displayed exceptional performance in photocatalytic-Fenton degradation tests on tetracycline (TC). In sum, the study not only turns hazardous EAFD into a powerful agent for removing SO2, a gaseous pollutant but also converts it into a value-added material, ZnFe2O4, thus proposing an integrated and efficient approach to solid waste management.

3D-interconnected N-doped porous carbon with hierarchical pore structure as a high-efficiency catalyst for H2S oxidation at room temperature

Nitrogen-doped porous carbons (NPCs) have been regarded as an efficient metal-free catalyst for H2S oxidation. However, critical factors affecting their desulfurization ability are still unclear, making it difficult to accurately adjust their desulfurization performance to meet industrial requirements. Herein, a novel 3D-interconnected NPC with hierarchical pore structure was synthesized by one-step “leavening” strategy using rice husk and (NH4)2C2O4 as a carbon source and foaming agent, respectively, for H2S oxidation at room temperature. Pyrolysis temperature is the major factor for physicochemical properties of NPCs, and breakthrough sulfur capacity of the optimal NPC reaches up to 1036.68 mg/g, which can remain stable during three desulfurization-regeneration cycles. Comparative experiment shows that H2S capacity of NPC is 1.8 and 4.0 times those of PC and NC, respectively, revealing the excellent desulfurization performance of NPC. The structure-effect relationships between H2S and NPC reveal that both textural and chemical properties of NPC, especially specific surface area, structural defect, and pyrrolic N, play dominant roles in H2S removal. It is very necessary to balance the relationship between textural performances and pyrrolic N to synthesize optimal NPC catalyst. This work provides a valuable reference for rational design of high-efficiency carbon-based catalysts for persistent desulfurization at room temperature.

On the mechanism of Ca(OH)2 structure modulation by surfactants: Experimental and calculative studies

Surfactants are widely used for structure modulation of calcium-based materials. However, the modification mechanisms underlying the CaO digestion improved by surfactants for Ca(OH)2 production remain unclear. This study employed experiment methods, Density Functional Theory (DFT), and Molecular Dynamics methods (MD) to reveal the mechanism of surfactant modulation at a molecular level. The adsorption energy of Primary Alcohol Ethoxylate (AEO), Sodium Dodecyl Sulfate (SDS), H2O, and Dodecyl Trimethyl Ammonium Bromide (DTAB) on CaO(001) surface were −52.62, −51.98, –23.79, and 3.96 kcal/mol, respectively. The strong chemisorption of AEO and SDS on the surface of CaO improved its structure stability. AEO and SDS weakened the diffusion of H2O to CaO surface, thus causing the reaction between CaO and H2O to be suppressed. After being modulated by SDS and AEO, better crystallinity of Ca(OH)2 and finer crystalline grains were observed with the formation of developed pore structure. AEO has a longer molecular chain, giving better modification performance. On the contrary, DTAB accelerated the diffusion of H2O to CaO surface, leading to more energy released and causing the fast growth of Ca(OH)2 crystals, as evidenced by the much larger particle size compared to that of AEO and SDS. This process led to the creation of a larger pore structure. Desulfurization was used as a performance indicator to evaluate the surfactants modulation efficacy. The sulfur capacity of Ca(OH)2 regulated by 1 % AEO was 100.05 mg/g, being the highest among the used surfactants. For comparison, the sulfur capacity without additives was 49.64 mg/g. This study shows that nonionic surfactants are an ideal choice for regulating the structure of Ca(OH)2, as they can effectively inhibit crystal growth.

Deep removal of COS by carbon aerogel in natural gas: Performance and regeneration on K2O-Cu/CA adsorbent at room temperature

COS in natural gas is difficult to be effectively removed at room temperature. Catalytic hydrolysis is a promising method, however, the discrepancy of catalytic active site as well as deactivation factors are the restricting factors. In this paper, the CuO load and alkali metal modification was successfully prepared on carbon aerogel with more mesoporous structure(5 %K2O-Cu/CA). The doping of K could improve the pore structure of the sample and is more conducive to the storage of sulfate, obtaining good anti-poisoning properties. Meanwhile, the K load achieved enriched surface hydroxyl groups, which played an important role in COS conversion, and provided enough electronic electron transfers to accelerate the H2O dissociation, producing more hydroxyl groups. Then the adsorbed COS could be efficiently captured by the increasing number of weak basic sites at low temperature. Furthermore, after COS transformation the escaped H2S could be subsequently adsorbed on 5 %K2O-Cu/CA surface and converted to be S2- and SO42- on CuO surface. Finally, the adsorbent capacity and deactivation were studied, and the N2 regeneration method owns the higher sulfur capacity of 6.01 mg/g with a COS removal efficiency of 100 % for the first time.

Enhanced SO2, NO, and Cr (VI) removal by lignin-derived high N-doped activated carbon through one-pot strategy: Structure development, structure–performance relationship and mechanism insight

The production of high-performance activated carbon (AC) is recognized as an essential strategy for the effective utilization of lignin resources. In this work, the N-doped AC was successfully prepared by blending sodium lignosulfonate (SL) and different ratios of FeCl3 through one-pot strategy. The AC structure evolution and performance were obtained by a series of characterization and tests. The results showed that, during the activation process, FeCl3 first complexed with urea and catalyzed the depolymerization of SL, and the rapid pore development was mainly caused by the template, including formed FeCl2, Na2Fe3Cl8 and Na6FeCl8. The ratio of FeCl3/SL adjusts the AC physicochemical texture. AC-3 processed a super total specific surface area and pore volume, respectively up to 2048 m2/g and 1.47 cm3/g. Meanwhile, AC-2 showed a higher nitrogen content of 11.4 %. The as-prepared AC shows super desulfurization, denitrification and Cr (Ⅵ) removal ability. AC-2 displayed maximum sulfur capacity and NO conversion, up to 199.1 mg/g and 42.4 %. This enhanced performance is primarily attributed to the pore structure induced by FeCl3 activation, which provides a foundation for adsorption and catalytic processes, further augmented by the increased active sites due to nitrogen doping. AC-3 achieved an extremely high Cr (VI) adsorption capacity, up to 386.2 mg/g, which was primarily attributed to the redox effect of N-containing and O-containing groups on Cr (VI), in addition, the effect of physical adsorption including pore structure is not neglectable. This study highlights the significant potential of environmentally friendly lignin-based porous carbon materials for removing contaminants in both gas and liquid phases.