Deep Desulfurization Process Research Articles

Deep Steel Desulfurization Practice

This article is aimed to study theoretical knowledges related to deep steel desulfurization and their practical application in specific production conditions. The main goal of this study was to verify the efficiency of added CaSi to processed heats in two batches, i.e., first for deep desulfurization at the beginning of the secondary metallurgy and then in a second smaller batch at the end of that process for final modification. At the beginning of the secondary metallurgy process, it was crucial to prepare a suitable chemical composition of ladle slag with advantageous properties for good assimilation of sulfur-based inclusions from desulfurization reactions. Samples were taken of final basic oxygen furnace slag, ladle slag before the deep desulfurization process at the beginning of secondary metallurgy and ladle slag at the end of processing. Detailed cleanliness analyses of steel samples taken from mold during the casting were performed using the Automated Steel Cleanliness Analyses Tool. For better understanding and interpretation of the obtained cleanliness results and their relationship, the following defined parameters were used: ratio of “Ca/Al” oxide inclusions, percentage of “liquid” inclusions and area of CaS inclusions.

Deep Desulfurization with Record SO2 Adsorption on the Metal-Organic Frameworks.

Selective elimination of sulfur dioxide is significant in flue gas desulfurization and natural gas purification, yet developing adsorbents with high capture capacity especially at low partial pressure as well as excellent cycling stability remains a challenge. Herein, a family of isostructural gallate-based MOFs with abundant hydrogen bond donors decorating the pore channel was reported for selective recognition and dense packing of sulfur dioxide via multiple hydrogen bonding interactions. Multiple O···H-O hydrogen bonds and O···H-C hydrogen bonds guarantee SO2 molecules are firmly grasped within the framework, and appropriate pore apertures afford dense packing of SO2 with high uptake and density up to 1.86 g cm-3, which is evidenced by dispersion-corrected density functional theory calculations and X-ray diffraction resolution of a SO2-loaded single crystal. Ultrahigh adsorption uptake of SO2 at extremely low pressure (0.002 bar) was achieved on Co-gallate (6.13 mmol cm-3), outperforming all reported state-of-the-art MOFs. Record-high IAST selectivity of SO2/CO2 (325 for Mg-gallate) and ultrahigh selectivity of SO2/N2 (>1.0 × 104) and SO2/CH4 (>1.0 × 104) were also realized. Breakthrough experiments further demonstrate the excellent removal performance of trace amounts of SO2 in a deep desulfurization process. More importantly, M-gallate shows almost unchanged breakthrough performance after five cycles, indicating the robust cycling stability of these MOFs.

Extractive desulfurization using choline chloride-based DES/molybdate nanofluids; Experimental and theoretical investigation

Recently, greater attention is being paid for desulfurization by deep eutectic solvents as an efficient extractive desulfurization agent. Deep desulfurization is a critical process to reach fuel with an ultra-low percentage of less than 10 ppm sulfur. Deep eutectic solvents (DESs) are eutectic mixture formed of Lewis or Brønsted acids and bases and have a lower melting point than individual components. Interaction strength among molecules in the DES affects their characteristics and applications. In this work, four DESs were prepared and characterized. The extractive desulfurization affinities of the DESs were evaluated using n-octane solvent as a model fuel containing thiophene as a sulfur compound. The DES consisted of choline chloride and ethylene glycol (ChCl-EG) exhibited the highest desulfurization affinity ~37% using the low volumetric ratio of DES: model fuel (1: 2). Moreover, molybdate nanofluid (0.02 wt%) based on ChCl-EG was prepared and analyzed by XRD, TGA, DLS, and TEM. The sulfur extraction of simulated fuel consisting of thiophene was conducted by MoO3-based DES nanofluid, which exhibited a high extraction efficiency of 98.01% in a single step, so considered as a deep desulfurization process. The concentration of sulfur in the model oil reached less than 4 ppm in one cycle. Furthermore, Molecular dynamics (MD) simulation and computational chemistry were implemented to evaluate the thiophene removal and oil desulfurization by deep eutectic solvent, in addition to investigating the intermolecular interactions between the DES and thiophene. The obtained results provide insights into the desulfurization mechanism by the DES solvents.

Highly efficient photocatalytic oxidative desulfurization of dibenzothiophene with sunlight irradiation using green catalyst of Ag@AgBr/Al-SBA-15 derived from natural halloysite

In recent decades, highly efficient deep desulfurization processes have become very necessary to decrease environmental pollution due to sulfur emissions from fuels. Herein, an enhanced photocatalytic desulfurization of a model fuel was investigated under sunlight irradiation using H2O2 as the oxidant and Ag@AgBr loaded mesoporous silica Al-SBA-15 as a catalyst. In this study, the photocatalyst (Ag@AgBr/Al-SBA-15) was synthesized via a chemical deposition using halloysite clay as the silica–aluminum source and characterized by X-ray diffraction, N2 adsorption, scanning electron microscopy, transmission electron microscopy, and UV–Vis diffuse reflectance spectroscopy (UV–Vis DRS). The UV–Vis DRS results revealed that the light absorption expanded to the visible region (λ>400nm) for the various Ag@AgBr nanoparticles doped in the mesoporous Al-SBA-15 material. The 30% Ag@AgBr/Al-SBA-15 sample with a 30% Ag@AgBr doping exhibited enhanced photocatalytic activity and showed high stability even after four successive cycles. The results demonstrated that initial dibenzothiophene concentrations (500ppm) reached 98.66% removal with 50mg of the catalyst dosage, 1.0mL of H2O2, for 360min of sunlight irradiation at 70°C.

The quantity and type of ILs needed to form magnetic-heteropolyacid mesoporous catalysts and their highly performance for DBT removal

Magnetic-heteropolyacid mesoporous catalysts, formed through the linkage of an ionic liquid, a magnetic Fe3O4@MCM-41 support, and a heteropolyacid, have been prepared and used in the deep oxidative desulfurization process.

Assessment of Ag Nanoparticles Interaction over Low-Cost Mesoporous Silica in Deep Desulfurization of Diesel

Chemical interactions between metal particles (Ag or Ni) dispersed in a low-cost MCM-41M produced from beach sand amorphous silica and sulfur compounds were evaluated in the deep adsorptive desulfurization process of real diesel fuel. N2 adsorption-desorption isotherms, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM) and scanning transmission electron microscopy coupled to energy-dispersive X-ray spectroscopy (STEM-EDX) were used for characterizing the adsorbents. HRTEM and XPS confirmed the high dispersion of Ag nanoparticles on the MCM-41 surface, and its chemical interaction with support and sulfur compounds by diverse mechanisms such as π-complexation and oxidation. Thermodynamic tests indicated that the adsorption of sulfur compounds over Ag(I)/MCM-41M is an endothermic process under the studied conditions. The magnitude of ΔH° (42.1 kJ/mol) indicates that chemisorptive mechanisms govern the sulfur removal. The best fit of kinetic and equilibrium data to pseudo-second order (R2 > 0.99) and Langmuir models (R2 > 0.98), respectively, along with the results for intraparticle diffusion and Boyd’s film-diffusion kinetic models, suggest that the chemisorptive interaction between organosulfur compounds and Ag nanosites controls sulfur adsorption, as seen in the XPS results. Its adsorption capacity (qm = 31.25 mgS/g) was 10 times higher than that obtained for pure MCM-41M and double the qm for the Ag(I)/MCM-41C adsorbent from commercial silica. Saturated adsorbents presented a satisfactory regeneration rate after a total of five sulfur adsorption cycles.

Extraction Coupled with Aerobic Oxidative Desulfurization of Model Diesel Using a B-type Anderson Polyoxometalate Catalyst in Ionic Liquids

An efficient aerobic oxidative desulfurization system was explored with polyoxometalate (DODMAC)3Co(OH)6Mo6O18·3H2O (DODMAC: Dimethyldioctadecylammonium Chloride) combined ionic liquids (ILs) as extraction solvent as well as reaction media for aerobic oxidative desulfurization of model diesel. N-octylpyridinium tetrafluoroborate ([Opy]BF4) was employed in the desulfurization system and the amazing recoverability showed without noticeable decrease in activity after seven cycles has aroused the great interest of us. Systematically investigations were carried out on the factors influencing the removal of DBT. The possible mechanism was also investigated hoping to provide new insights into diesel deep desulfurization processes.

Unified catalytic oxidation–adsorption desulfurization for aromatic sulfur compounds with cyclohexanone peroxide over Ti-HMS

Three kinds of Ti-HMS zeolites have been synthesized by using different templates, and their catalytic performance was investigated in deep oxidation-adsorption desulfurization process. Various analysis techniques have been applied to investigate physical and chemical properties of the catalysts. Using cyclohexanone peroxide as an oxidant, the catalytic performance results show that Ti-HMS-12 exhibits highest desulfurization performance (99.9%) without solvents. Dibenzothiophene (DBT) was almost completely oxidized to the more polar DBT sulfone, which could be subsequently adsorbed on the Ti-HMS-12, achieving a unified processes of oxidative-adsorption desulfurization process. Furthermore, the catalyst was recycled for five runs with slight decreases in the catalytic performance and can be easily regenerated by methanol washing.

Deep desulfurization of natural gas by a commercial ZnO adsorbent: A mathematical study for fixed-bed reactors

Natural gas deep desulfurization process by zinc oxide adsorbent is an example of noncatalytic gas-solid reactions, which plays a crucial role in petrochemical and refinery industries. In this paper, it was tried to model the desulfurization process using grain model. In order to analyze the adsorbent properties, a commercial sample was tested by BET, XRF, SEM and, mercury porosimetry. The results of the numerical model were validated against the experimental data from a packed-bed reactor. The breakthrough time of the model was estimated with less than 5% error, indicating a good correspondence with experiments.The concentration profiles along the bed and inside the pellets have been also explored under the industrial conditions. The predicted breakthrough time for the commercial adsorbent has been estimated around 215 days. To identify the influential process parameters on the lifetime of the adsorbent bed, and degree of the bed conversion, the sensitivity analysis was performed in terms of natural gas flow rate and hydrogen sulfide concentration. Interestingly, the obtained results indicated that increasing the unit capacity by 10%, will decline the breakthrough time by 30 days. Furthermore, varying the H2S content of the inlet gas by 25% will shorten the breakthrough time of the commercial sorbent by 60 days.

Oxidative desulfurization of diesel fuel with caprolactam-based acidic deep eutectic solvents: Tailoring the reactivity of DESs by adjusting the composition

Despite the significance of hydrogen bonding in deep eutectic solvents (DESs) for desulfurization processes, little is understood about the relationship between the DES composition, hydrogen-bonding strength, and oxidative desulfurization activity. In this study, a new family of caprolactam-based acidic DESs was prepared with different molar ratios of caprolactam and oxalic acid. The prepared DESs were characterized by differential scanning calorimetry, Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, and thermogravimetric analyses. These DESs were employed for oxidative desulfurization reactions and the desulfurization efficiency was found to vary regularly with the DES composition. The factors influencing the removal of dibenzothiophene were systematically investigated and the desulfurization efficiency of the caprolactam-based acidic DESs reached as high as 98% under optimal conditions. The removal of different sulfur compounds followed the order: dibenzothiophene > 4,6-dimethyldibenzothiophene > benzothiophene. The combined experimental data and characterization results revealed that the oxidative desulfurization efficiency of the system was influenced by the hydrogen bonding interactions with the DES, which can be optimized by adjusting the DES composition. These findings regarding hydrogen bonding in DESs provide new insight for better understanding of the mechanism of diesel deep desulfurization processes.

Optimization of Deep Oxidative Desulfurization Process Using Ionic Liquid and Potassium Monopersulfate

Response surface methodology (RSM) was selected to optimize a desulfurization process with metal based ionic liquids ([Bmim]Cl/CoCl2) and potassium monopersulfate (PMS) together to remove benzothiophene (BT) from octane (simulating oil). The four experimental conditions of PMS dosage, [Bmim]Cl/CoCl2 dosage, temperature, and reaction time were investigated. The results showed that the quadratic relationship was built up between BT removal and four experimental variables with 0.9898 fitting coefficient. The optimal conditions were 1.6 g (20 wt%) PMS solution, 3.2 g [Bmim]Cl/CoCl2, 46°C, and 23 min, which were obtained based on RSM and experimental results. Under the optimal condition, predicted sulfur removal rate and experimental sulfur removal rate were 96.7% and 95.4%, respectively. The sequence of four experimental conditions on desulfurization followed the order temperature > time > [Bmim]Cl/CoCl2 dosage > PMS solution dosage.

Preparation and Characterization of Bimetallic Catalyst (NiO – CoO) for Desulfurization of Gas Oil

In this study NiO - CoO bimetallic catalysts are prepared with two Ni/Co ratios (70:30 and 80: 20) using the precipitation method of nitrate salts. The effects of Ni /Co ratio and preparation methods on the catalyst are analyzed by using different characterization techniques, i.e. atomic absorption (AA) , XRD, surface area and pore volume measurements according to the BET method . The results indicate that the best catalyst is the one containing the percentage of Ni :Co ( 70 : 30 ). Experiments indicate that the optimal conditions to prepare catalyst are stirring for three hours at a temperature of 60oC of the preparation , pH= (8-9) , calcination temperature at 400oC for two hours using the impregnation method . The catalyst activity is studied through the application in the process of oxidative desulfurization of gas oil fuel . The optimal conditions for deep oxidative desulfurization processes are : catalysts 3% , 2 gm. Na2 CO3 , refluxe time 3 hours at 400 C , using a mechanical stirrer at moderate speed (700 rpm), the volume ratio of gas oil : H2O2 : acetic acid is 10: 1: 0.5 and extracted with 1:1 ratio of acetonitrile to the gas oil for three times . The results indicate that the catalysts are efficient to remove sulfur from gas oil depending on temperature, time, concentration of hydrogen peroxide H2O2 30 % and solvent used for extraction. The efficiency of the best catalyst gives a maximum sulfur removal reaching 68.97%.

Regulating sulfur removal efficiency of fuels by Lewis acidity of ionic liquids

It is urgent to develop a new deep desulfurization process of fuels as the environmental pollution increases seriously. In this work, a series of Lewis acidic ionic liquids (ILs) [C 4 3 MPy]Cl/nZnCl2 (n=1, 1.5, 2, 3) were synthesized and used in extraction and catalytic oxidative desulfurization (ECOD) of the fuels. The effects of the Lewis acidity of ILs, the molar ratio of H2O2/sulfur, temperatures, and different substrates including dibenzothiophene (DBT), benzothiophene (BT) and thiophene (TS), on sulfur removal were investigated. The results indicated that [C 4 3 MPy]Cl/3ZnCl2 presented near 100% DBT removal of model oil under conditions of 323 K, H2O2/DBT molar ratio 6:1. Kinetics for the removal of DBT, BT and TS by the [C 4 3 MPy]Cl/3ZnCl2-H2O2 system at 323 K is first-order with the apparent rate constants of 1.1348, 0.2226 and 0.0609 h-1, and the calculated apparent activation energies for DBT, BT and TS were 61.13, 60.66, and 68.14 kJ/mol from 298 to 308 K, respectively. After six cycles of the regenerated [CC 4 3 MPy]Cl/3ZnCl2, the sulfur removal had a slight decrease. [CC 4 3 MPy]Cl/3ZnCl2 showed a good desulfurization performance under optimal conditions.

Preparation and Characterization of Bimetallic Catalyst (NiO – CoO) for Desulfurization of Gas Oil

In this study NiO - CoO bimetallic catalysts are prepared with two Ni/Co ratios (70:30 and 80: 20) using the precipitation method of nitrate salts. The effects of Ni /Co ratio and preparation methods on the catalyst are analyzed by using different characterization techniques, i.e. atomic absorption (AA) , XRD, surface area and pore volume measurements according to the BET method . The results indicate that the best catalyst is the one containing the percentage of Ni :Co ( 70 : 30 ). Experiments indicate that the optimal conditions to prepare catalyst are stirring for three hours at a temperature of 60oC of the preparation , pH= (8-9) , calcination temperature at 400oC for two hours using the impregnation method . The catalyst activity is studied through the application in the process of oxidative desulfurization of gas oil fuel . The optimal conditions for deep oxidative desulfurization processes are : catalysts 3% , 2 gm. Na2 CO3 , refluxe time 3 hours at 400 C , using a mechanical stirrer at moderate speed (700 rpm), the volume ratio of gas oil : H2O2 : acetic acid is 10: 1: 0.5 and extracted with 1:1 ratio of acetonitrile to the gas oil for three times . The results indicate that the catalysts are efficient to remove sulfur from gas oil depending on temperature, time, concentration of hydrogen peroxide H2O2 30 % and solvent used for extraction. The efficiency of the best catalyst gives a maximum sulfur removal reaching 68.97%.

Adsorption performance of multiwall carbon nanotubes and graphene oxide for removal of thiophene and dibenzothiophene from model diesel fuel

Multiwall carbon nanotubes (MWCNT) and graphene oxide (GO) are promising compressible nano adsorbents that can be used in the deep desulfurization process for mobile applications. In this study, the adsorption isotherm and the adsorption kinetics of thiophene and dibenzothiophene (DBT) introduced in hexane as a model diesel fuel have been investigated. The adsorption performance of thiophene and DBT on MWCNT and GO were compared with the adsorption performance on activated carbon (AC) as a reference material. In addition, the effect of agitation speed and adsorbent dosage amount were studied. The DBT adsorption results on the three adsorbents were represented by Langmuir and Freundlich isotherm models. The Freundlich isotherm was found to be more favorable with squared correlation coefficient (R 2) >0.97. The thiophene adsorption isotherm was fitted only by the Freundlich isotherm model with R 2 > 0.989. The adsorption rate for these sulfur compounds follows the pseudo-second-order adsorption kinetic. The removal efficiency of DBT using the MWCNT was 68.8 % almost twice the GO removal efficiency but lower than the AC removal efficiency by about 25 %. In addition, the ability of these adsorbents to remove the DBT from the model fuel was much higher than their capability to remove the thiophene.

Photocatalytic oxidative desulfurization of dibenzothiophene by C/TiO2@MCM-41 nanoparticles under visible light and mild conditions

Today, due to the environmental pressures on the sulfur content of gasoline and fuel cell applications, petroleum refineries need a very deep desulfurization process to reach the ultra-low sulfur diesel (ULSD, 1 ppm).

Extraction of Sulfur-containing Compounds from Diesel by 1-Ethyl-3-methylimidazolium Diethyl Phosphate in a Lab-scale Extractive Column

Desulfurization of diesel using 1-ethyl-3-methylimidazolium diethyl phosphate in a lab-scale extractive column was investigated to explore a deep desulfurization process that could be used as a supplemental technology to hydrodesulfurization. The results showed that the dibenzothiophene derivatives could be removed by extraction with 1-ethyl-3-methylimidazolium diethyl phosphate, the extraction sulfur-containing components increase with the mass ratio of 1-ethyl-3-methylimidazolium diethyl phosphate to diesel, and lower viscosity could also result in the higher desulfurization result. Optimum feed rate and an appropriate extraction temperature were needed to ensure the desulfurization effect. Extraction yield of sulfur-containing compounds followed the order of C2-DBT > DBT > C1-DBT > 4-MDBT > 4,6-DMDBT > -C2-BT > C2-BT > C3-BT.

A mathematical model for the dynamic desulfurization process of ultra-low-sulfur steel in the LF refining process

In order to obtain the dynamic variation rule of the sulfur content of liquid steel in the LF refining process, a complete mathematical model including a desulfurization kinetic model and temperature model in the deep desulfurization process is presented, based on the practical production and reaction mechanism of ultra-low-sulfur steel in a LF. The results show that the calculated values of the sulfur content in liquid steel using the model fit the experimental values well, and the relative error is less than 8%. The effects of refining slag on the desulfurization process are analyzed in this paper, which shows that slag basicity is most important at the early and middle stages of the process, while slag weight is most important at the middle and late stages. The effect of the above factors on the final sulfur content of liquid steel is further analyzed quantitatively. The simulated results provide a theoretical basis to segment control the refining process in order to achieve the maximum effect, improving efficiency, saving energy and reducing consumption.

Deep Oxidative Desulfurization of Real Diesel Catalyzed by Na2WO4 in Ionic Liquid

An effective deep oxidative desulfurization process, catalyzed by Na2WO4 and ionic liquid, was developed for real diesel prehydrotreated. A lower amount of ionic liquid was used, while good catalytic oxidation activity could be obtained under mild conditions. The sulfur content in the real diesel can decrease from the initial 200 to 23.2 ppm after the oxidative desulfurization process, and the sulfur removal rate can reach 88.4%. The catalytic system can be recycled directly after vacuum drying, and there is no obvious change on catalytic activity after recycling five times.

Removal of Dibenzothiophenes from Fuels by Oxy-desulfurization

Removal of sulfur species from fuels is an increasingly critical environmental issue. Hydrodesulfurization (HDS) removes sulfur compounds, such as mercaptans and sulfides, from hydrocarbons; however, some sulfur-containing compounds are very difficult to remove and need deep desulfurization processes. In this study, another approach is explored, where dibenzothiophene can be removed from the HDS products by a liquid-phase process. Four different sulfur removal approaches are tested: oxidation, extraction, consecutive oxidation and extraction, and simultaneous oxidation and extraction. A detailed parametric experimental study was performed to select the best technique for the specified purpose of this investigation. n-Octane doped with dibenzothiophenes is used as a model fuel, which is extracted by polar solvents [N-methyl-2-pyrolidone (NMP), dimethyl formamide (DMF), and acetonitrile (ACN)]. These solvents are found to have a moderate capability of removing sulfur species. Applying oxidation in the liqui...