Desulfurization Properties Research Articles

Formation of optimal slag composition in ladle furnace for improvement of desulfurization properties and optimization of consumption of slag-forming materials

Formation of optimal slag composition in ladle furnace for improvement of desulfurization properties and optimization of consumption of slag-forming materials

One Pot Synthesis of Phosphomolybdenate Based Hybrids for Efficient Oxidative Desulfurization

With increasing stringent standard of sulfur content in fuels, there is a growing need for high-efficiency deep desulfurization to meet ecological and environmental demands. Herein, a series of heteropolyacid catalysts with phosphomolybdic acid base melamine (MHPMo-n) were synthesized by one-pot method and applied to oxidative desulfurization. Further, the optimum conditions for desulfurizations could be explored, which the desulfurization rate of the catalyst could reach 100% within 60 min under the conditions of m(catalyst)= 0.01 g, T = 40 °C, O/S = 3. Furthermore, the catalyst demonstrated excellent catalytic efficiency during the five cycles. One-pot method of phosphomolybdic acid base melamine provides a new idea for the synthesis of catalysts with outstanding catalytic properties for oxidative desulfurization (ODS).

Desulfurization properties, pathways, and potential applications of two novel and efficient chemolithotrophic sulfur-oxidizing strains of Pseudomonas sp. GHWS3 and Sphingobacterium sp. GHWS5.

With the accelerated modernization of agriculture and industry, sulfides have been released into the environment as a by-products of various production processes. Elevated levels of sulfide pose a threat to organisms' health and disrupt ecosystem equilibrium. This study successfully isolated two highly efficient sulfur-oxidizing strains, namely Pseudomonas aeruginosa GHWS3 and Sphingobacterium sp. GHWS5. Neither strain exhibited hemolytic activity or pathogenicity. Additionally, GHWS3 inhibited the common aquaculture pathogen Vibrio anguillarum, while GHWS5 exhibited inhibitory effects against Vibrio harveyi. GHWS3 and GHWS5 demonstrated effective removal of sulfide under the following conditions: temperature range of 20-40°C, pH level of 4.5-8.5, salinity range of 0-50‰, C/N ratio of 5-15, and sulfide concentration of 20-200mg/L. By amplifying the key functional genes of the sulfur-oxidizing Sox and rDsr systems in both GHWS3 and GHWS5 strains, potential desulfurization pathways were analyzed. Furthermore, both strains displayed high efficiency in removing sulfides from actual aquaculture pond substrate mixtures. The findings of this study provide two promising candidate strains for sulfides removal from farm tailwater, industrial wastewater, and domestic wastewater.

Removal of hydrogen sulfide by metal-free amine-functionalized mesoporous carbon at room temperature: Effect of amines

The introduction of nitrogen can effectively improve the alkalinity of carbon materials, introduce catalytic sites and active oxygen radicals, thus enhancing the desulfurization ability. However, the study on the effect of amine species and loading amount on the desulfurization properties is very limited. In this study, mesoporous carbon materials with large specific surface area and pore volume were prepared. Different amines were selected as impregnating agents to investigate the performance of amine-functionalized carbon catalysts for hydrogen sulfide (H2S) removal under various operating conditions. The synthesized carbon material has a large specific surface area of 989 m2/g, with an average pore diameter of 12.94 nm. The well-developed pores could not only provide the space for the dispersion of amine, but also facilitate the diffusion of H2S and the storage of sulfur products. Amine increase the alkalinity of carbon material and the reactivity of reaction sites located on the carbon skeleton. The desirable catalytic performance of catalysts impregnated by amines should be the compromise among spatial structure of the amine, the surface chemistry and porosity of catalysts. Among them, the polyethylene polyamine impregnated carbon catalyst with a high ratio of secondary and tertiary amine (80.54 %) showed the best catalytic performance of 1.58 g H2S/g-catalyst at 30 °C due to due to suitable steric hindrance and higher stability in the H2S adsorption–desorption cycle. This work further refines the previously proposed reaction mechanism and provides a possibility for the application of carbon-based catalysts with directional introduction of nitrogen elements by impregnation method in the removal of H2S.

Investigating catalytic oxidative desulfurization of model fuel using hollow PW12/TiO2@MgCO3 and performance optimization via box-behnken design

A facile and eco-friendly synthesis of PW12/TiO2@MgCO3 hollow tubes (PW12·∼· H3[PW12O40] = polyoxometalate) using a soluble and reusable MgCO3·3H2O micro-rods template was reported for the first time. The resultant hollow tubes were characterized by Fourier transform infrared spectroscopy (FT-IR), UV–visible spectroscopy, powder X-ray diffraction (PXRD), energy-dispersive X-ray spectroscopy (EDX), and scanning electron microscopy (SEM), which indicated that the [PW12O40]3- structure remained intact within the hollow tubes. Furthermore, the specific surface area (88.982 m2/g) and average pore size (2.6 nm) of the PW12/TiO2@MgCO3 hollow tubes were calculated using the Brunauer-Emmett-Teller (BET) analysis. This study explored the catalytic performance of PW12/TiO2@MgCO3 hollow tubes using a three-level Box-Behnken design (BBD), through which optimization curves were designed. The desulfurization of model fuel using hollow tubes was optimally performed when the catalyst dose, time, temperature, and oxidant/sulfur (O/S) were 20–80 gm, 80–120 min, 25–80 °C and 3–8 molar ratio, respectively. These results were further processed, and the experiments were replicated twenty-nine times using a model based on two quadratic polynomials to create a response surface methodology (RSM). This permits a mathematical correlation linking the desulfurization and experimental parameters. The optimal performance of reaction mixture was evaluated to be 80 mg for catalyst concentration, 25 °C of temperature, reaction time of 100 min, and 5.5 for oxidant/sulfur molar ratio from 20 mL of octane simulation oil containing 350 ppm dibenzothiophene (DBT). The predicted desulfurization rate of the model fuel under these optimal conditions was 95.3%. The correspondence between the experimental results and predicted values was verified based on regression analysis, with an R2 value greater than 0.99. These hollow tubes could be used for their desulfurization properties ten times a row without significantly reducing catalytic activity.

Perovskite nanomaterials with exceptional photocatalytic properties for oxidative desulfurization of dibenzothiophene

LaTiO3, LaZnO3, and Zn-doped LaTiO3 (LaZn0.5Ti0.5O3) perovskite catalysts are used for the aerobic photocatalytic oxidative desulfurization (APODS) of organosulfur compounds such as dibenzothiophene (DBT). Several techniques were used to characterize the synthesized photocatalyst, XRD, SEM, TEM, EDX, UV–Vis, DRS, PL, and XPS physisorption analyses. XRD patterns of LaZn0.5Ti0.5O3 is similar to pure LaTiO3 without any impurities confirming the insertion of atomic zinc into the LaTiO3 lattice structure. According to the obtained results, synthesized doped perovskite exhibits a more significant photocatalytic reaction than pure perovskite in removing DBT in the following order LaZn0.5Ti0.5O3 > LaZnO3 > LaTiO3 in the values 99.97, 91.38 and 76.05 % within 180 minutes under sunlight. The pseudo-first-order kinetic reaction model fits well with the results of the kinetic study. A reaction mechanism for LaZn0.5Ti0.5O3 was proposed using UV– Vis and XPS. At wavelengths above 400 nm, UV–Vis DRS confirms the absorption edges of the compound, which in this case equates to a visible light absorber with a band gap of 2.9 (eV). Superoxide radicals and holes were determined to be the primary active species in the photocatalytic process due to the reactive species and oxygen bubbles acting as trapping agents. The developed photocatalytic material was also highly regenerative and recyclable. The photocatalyst LaZn0.5Ti0.5O3 is first utilized in the photocatalytic oxidation of DBT. LaZn0.5Ti0.5O3 is a promising photocatalyst for environmental control and relevant applications, especially in solar energy.

Adsorptive desulfurization properties of refractory sulfur compounds onto Al2O3-Ga2O3 nanomaterials

The impact of the synthesis method on the structural, textural, and surface properties of the Al2O3-Ga2O3 sample was investigated, and the adsorbents were evaluated for their adsorptive desulfurization properties. The incorporation of Ga atoms into the Al2O3 framework (via SGM) resulted in an increase in specific surface area and pore volume, but a decrease in average pore size. XRF analysis confirmed Ga loading, while SEM-EDS and STEM-EDS techniques revealed well-distributed elements with irregular spherical morphologies. XRD diffractograms confirmed the formation of γ-Al2O3, with a slight shift of diffraction peaks due to the presence of Ga (via SGM), suggesting that Ga atoms are part of the structure. The obtained solids exhibit values in the Freundlich equation that indicate a degree of nonlinearity in adsorption for Al2O3, while Al2O3-Ga2O3(SGM) and Al2O3-Ga2O3(IM) suggest a possible chemical process and favorable adsorption. The small KF values demonstrate weak adsorption on the adsorbents, which can be explained by sulfur-to-metal interaction, π-complexation, and non-specific interactions such as Van der Waals forces. The adsorbent showed the greatest affinity for BT and the least for DBT. The selectivity order from strongest to weakest adsorption was BT: Al2O3-Ga2O3(SGM) > Al2O3-Ga2O3(IM) > Al2O3, and DBT: Al2O3-Ga2O3(IM) > Al2O3-Ga2O3(SGM) > Al2O3.

Design and oxidative desulfurization of Ag/Ti heterometallic clusters based on Hard-Soft Acid-Base principle.

Hard-Soft Acid-Base (HSAB) principle plays an important guiding role in the design and synthesis of novel clusters and coordination compounds, in which "soft acids prefer to react with soft bases, while hard acids have an affinity for hard bases". Based on HSAB principle, four Ag/Ti heterometallic clusters, including Ag2Ti10, Ag2Ti11 with "Ti-encapsulated Ag" configurations, and two "Ag-encapsulated Ti" structures Ag2Ti2 and Ag2Ti12, were synthesized under solvothermal conditions. In addition, Ag2Ti12 exhibited an efficient and stable catalytic activity for sulfide oxidation. This work provides not only a new structural model for the modulation of the catalytic oxidative desulfurization properties of Ag/Ti heterometallic clusters but also a new insight of the utilization of phosphine-containing ligands to regulate the structure of Ag/Ti heterometallic clusters.

A strategy of KIT-6-carrier modification towards enhancement of desulfurization properties of mesoporous Zn-based sorbents for H2S removal from hot coal gas

Modification of KIT-6 by Ti/W doping (with one-pot synthesis method) was proposed for improving desulfurization performance of ZnO-KIT-6 sorbent. The characterization results indicate that the dopant atoms are present in the form of Ti4+ and W6+, the ordered mesoporous structure of KIT-6 can be retained at Me/Si doping ratios of 1/50–1/20. The presence of [TiO4]4− units in Ti-doped carriers demonstrates that a part of Ti atoms incorporates into the silica framework. Furthermore, moderate Ti doping causes more porous KIT-6 but W doping results in the decline in the specific surface area. Metal doping of Ti/W both show the effects of pore expansion as well as improvement of ZnO-dispersion, favorable for the sulfidation reaction. Generally, the desulfurization properties of sorbents are greatly enhanced by carrier modification. The highest breakthrough sulfur capacity of sorbents containing Ti or W doped KIT-6 are approximate (7.07 and 7.14 g S/100 g sorbent for Ti and W doping, respectively). However, W modification results in greater decrease in orderness of carriers. Additionally, sorbent with Ti-doped carriers has more stable H2S-uptake capacity during five successive sulfidation/regeneration cycles, showing great potential for industrial applications.

Insights into the effects of metal-ion doping on the structure and hot-coal-gas desulfurization properties of Zn-based sorbents supported on SBA-15

Doping of metal (Co/Ni/Ce) ions into ZnO was proposed for modifying the structure and hot-coal-gas desulfurization properties of ZnO supported on SBA-15 (ZnO/SBA-15). Co and Ce element are presented as Co2+ and Co3+, and Ce3+ and Ce4+ in modified sorbents, respectively, while only Ni2+ is found in Ni-ion-doped sorbents. Doping of Co/Ni ions causes the formation of Zn-Co/Ni-O solid solution and more porous sorbents. Accordingly, the desulfurization performance of ZnO/SBA-15 is greatly improved after the doping of Co/Ni ions. Furthermore, Ni-doped sorbent with Zn/Ni molar ratio of 20:1 (Zn20Ni1/SBA-15) shows the highest breakthrough sulfur capacity (16.0 g of S per 100 g of sorbent). More importantly, the introduction of Co/Ni/Ce ions produces an inhibiting effect on the formation of COS during desulfurization process. Especially, the amount of COS formed before H2S breakthrough for Zn20Ni1/SBA-15 decreases by 99.4% compared to ZnO/SBA-15. The inhibition of COS emission is mainly attributed to the catalytic effect of Co/Ni/Ce-containing species on the hydrogenolysis of COS. In addition, Zn20Ni1/SBA-15 shows stable desulfurization performance during successive sulfidation/regeneration cycles, favorable for its application for hot coal gas desulfurization.

Hierarchical pore configuration in activated coke boosting direct desorption of desulfurization product H2SO4: A combined experimental and computational investigation

Water washing regeneration has been applied to recover H2SO4 from desulfurized activated cokes (AC). However, the low regeneration efficiency is the bottleneck which causes inferior cycled desulfurization properties of AC. Herein, we propose that the washing regeneration efficiency can be significantly improved by pore structure regulation of AC. A series of ACs with variable pore configurations were used as model adsorbents to individually investigate the effect of pore structure on the washing-regeneration of desulfurized AC. Cycling desulfurization-regeneration experiments show that the micropore-dominant AC exhibits poor performance of water-washing regeneration. After 10 cycles, the adsorption sulfur capacity of micropore-dominant AC declines to 10.17 mg g−1, only 50% of fresh activated coke. Whereas the hierarchical porous AC containing equivalent volume of micropore and mesopore (0.40 and 0.50 cm3 g−1) has both excellent SO2 removal kinetics and water-washing regeneration performance. Even after 10 cycles, the hierarchical porous AC can still sustain high adsorption sulfur capacity of 70 mg g−1 and excellent water-washing regeneration efficiency of 90%. Molecular dynamic simulations using pore models close to practical AC suggest that the self-diffusion coefficient of H2SO4 in hierarchical pore is about two times of that in micropore, proving the promoting role of hierarchical porous structure in H2SO4 desorption. This work not only reveals the relationship of pore configuration with washing regeneration behavior but also provides a facile pore configuration regulation strategy that can substantially improve AC’s regeneration efficiency, implying great potentials for applying water-washing regeneration in industrial desulfurization process.

Structure Characteristics and Hot-Coal-Gas Desulfurization Properties of Zn-Based Sorbents Supported on Mesoporous Silica with Different Pore-Arrangement Patterns: A Comparison Study

Ordered mesoporous MCM-41 (two-dimensional (2D) hexagonal pore arrangement) and MCM-48 (three-dimensional (3D) cubic channel arrangement) with similar pore sizes and surface areas were selected for...

Synthesis and Characterization of Mechanically Alloyed, Nanostructured Cubic MoW Carbide

Carbides are used extensively as cutting tools, forming dies, and recently in catalysis applications, among other industrial applications. In this work, the synthesis and characterization of a nanostructured MoW bimetallic carbide were carried out by mechanical alloying with a mixture of elemental powders with a nominal composition of W1.5Mo6C2.5 at different grinding times as follows: 25, 50, and 75 h in a low-energy ball mill at a speed of 500 rpm and 125 and 150 h in a high-energy ball mill at a speed of 1500 rpm. The formation of a solid solution was observed at 150 h of milling; the nanostructured bcc MoW carbide corresponded to the main phase in the sample, besides the presence of the nanostructured MoW alloy as a secondary phase with an average crystal size of 40.8 nm. The phases and morphology at every stage of milling were studied by: X-ray diffraction (XRD), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), and Vickers hardness. As the milling time increased, the hardness of these particles increased from 10.5 to 31.48 GPa for the powder particles milled for 150 h. The samples obtained at 125 and 150 h of milling were evaluated during catalytic aqua-thermolysis of heavy oil to analyze fuel desulfurization properties by Fourier transform infrared (FTIR) techniques. The results showed the breaking of S-S bonds, indicating the existence of a desulfurization reaction of heavy oil.

Enhanced Wet Flue Gas Desulfurization Properties by Additives of Organic Acids, Organic Salts, Inorganic Salts, and Organic Amines

In order to enhance wet flue gas desulfurization efficiency and reduce cost, the effects of different series of additives (typical organic acids, organic salts, inorganic salts, organic amines, and...

Covalent immobilization of Dawson polyoxometalates on hairy particles and its catalytic properties for the oxidation desulfurization of tetrahydrothiophene

Poly (glycidyl methacrylate) (PGMA) was grafted onto the SiO2 surface to prepare the hairy particles PGMA/SiO2 using the “grafting from” method, and then vacant Wells-Dawson-type polyoxometalates (POMs) was covalently bonded to PGMA/SiO2 using the silane coupling agent to prepare heterogeneous catalyst POM-PGMA/SiO2. It is highly efficient and selective for tetrahydrothiophene (THT) oxidation. The oxidation process of THT catalyzed by POM-PGMA/SiO2 using H2O2 presented some special characters. POM-PGMA/SiO2 showed a certain microenvironment effect of the carrier, and effectively promoted the THT oxidation. There are optimal values for both the amount of POM-PGMA/SiO2 and the bonding amount of POM for THT oxidation, and the excessive catalyst and too high density of catalytic active sites can both decrease the catalytic activity. Alkalinity is not conducive to oxidation of THT with H2O2. More attractively, POM-PGMA/SiO2 could be well reused several times, stemming from the strong covalent bonding between the POM clusters and the polymers on SiO2 surface.

Manganese Ore-based Wet Flue-Gas Desulfurization: A Review

The removal of SO2 from flue gases is necessary for eliminating haze and controlling acid rain. However, developing the traditional wet and dry flue-gas desulfurization (FGD) is challenging due to the disposal issue of several byproducts. Manganese (Mn) orebased wet FGD possesses many advantages, including good desulfurization property, low cost, and high economic benefit. The environment friendliness and reusability of MnSO4 provide new ideas and methods in the future research direction of FGD. This review summarizes the background information of Mn ore slurry desulfurization, the desulfurization mechanism, the technological process, and the desulfurization devices. The role of operating parameters, such as temperature, liquid/solid ratio, pH, SO2 concentration, and particle size, in the desulfurization efficiency and manganese leaching rate are also discussed. The temperature (20°C-80°C) has exerted little effect on the desulfurization efficiency, whereas a low pH value is beneficial for SO2 removal. Moreover, a low inlet SO2 concentration and small particle size are beneficial for SO2 removal. The control and digestion techniques related to the byproduct (manganese dithionate) are also presented, along with the future development direction of Mn ore-based wet FGD in different industries.

PEG@ZIF-8/PVDF Nanocomposite Membrane for Efficient Pervaporation Desulfurization via a Layer-by-Layer Technology.

The desulfurization property of conventional mixed matrix membranes (MMMs) cannot meet the necessary demand due to particles aggregation and interface defects. Here, we put forward a layer-by-layer (LBL) approach to make a novel PEG@ZIF-8/poly(vinylidene difluoride)(PVDF) composite membrane for pervaporation desulfurization. In this way, a ZIF-8 layer is covered on the surface of the PVDF porous membrane via an in situ growth method. Then, a PEG layer is covered on the ZIF-8 layer by a casting method. Compared with pristine PEG membranes, the separation performance of the ZIF-8@PEG/PVDF nanocomposite membrane increased significantly. This can be attributed to the homogeneous ZIF-8 particle layer and better compatibility between the poly(ethylene glycol) (PEG) matrix and ZIF-8 particles. The membrane achieves a maximum total flux of 3.08 kg·m-2·h-1 at the third in situ growth cycles of ZIF-8 particles and a maximum sulfur enrichment factor of 7.6 at the sixth in situ growth cycles of ZIF-8 particles.

Enhanced Dibenzothiophene Capture with Multimetal–Organic Frameworks in the Presence of Benzene and Octane

To enhance dibenzothiophene (DBT) capture performance, we innovatively synthesized a series of novel multimetal–organic frameworks (MMOFs) by the incorporation of Ag+, Cu2+, Zn2+, and Ni2+ within one structure. Those novel desulfurizers have been fully characterized and their structural changes further compared in terms of nitrogen adsorption–desorption, powder X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, inductively coupled plasma, X-ray photoelectron spectroscopy, and so forth. The DBT capture properties with as-synthesized MMOFs in different simulated fuels were evaluated through a series of batch tests. All further investigations demonstrated that the Ag/Zn/Ni/Cu-BTC exhibited a remarkably high sulfur capacity attributed to the associative effects of π-complexation and acid–base interaction. Additionally, based on sieving and inertia mechanisms, this adsorbent possessed an extremely high affinity for DBT capture in the presence of benzene and octane. Especially, the Ag/Zn/Ni/Cu-BTC could sustain an outstanding desulfurization property after the fifth cycle. Our study opens up a new perspective for the design of desirable MMOF materials, promoting their potential development in the aspects of adsorption desulfurization.

Comparative Study of the Flue Gas Desulfurization Using Different‐Grade Natural Manganese Oxides

AbstractDifferent grades of natural manganese ores were used to remove SO2 by dry flue gas desulfurization. The grades of the manganese ores were negatively correlated with the desulfurization performance. The produced MnSO4 enriched on the surface would block the gas diffusion channels during desulfurization. The better desulfurization properties of the low‐grade manganese ores are ascribed to the highly active γ‐MnO2, the porous structure, and the high specific surface area as well as the SiO2 bridge‐like effects. This study supports the cooperative use of sulfur‐containing flue gases and low‐grade natural manganese oxides.

Experimental study on desulfurization at low temperature with plasma modified calcium-based adsorbent

Activated carbon and quicklime were used to prepare complex calcium based adsorbent for flue gas desulphurization. The desulfurization properties of adsorbent were analyzed on fixed bed. The results showed that the desulfurization effect of the composite adsorbent was best when the ratio of activated carbon to calcium was 1:2, the water heating time was 24 hours and heating temperature was 90 °C. At the same time, low temperature plasma technology is used to ionize the composite adsorbent, increase the number of surface chemical functional groups of the adsorbent, and then improve its desulfurization efficiency. The effect of modification time and power on desulfurization efficiency was studied. The results show that low temperature plasma ionization modification can obviously improve the desulfurization performance of composite adsorbent.