At present, greater pressure is continuously applied to the desulphurization process to produce fuel with low sulphur content. Relying on the conventional hydro-desulphurization (HDS) method totally ...would result in significant increase in the cost due to the required modifications to the HDS unit, as well as increased consumption of hydrogen, electricity and catalyst. Despite extraction-desulphurization method by employing ionic liquids (ILs) as solvent has gathered attention for the past two decades, the toxicity of ILs led to research works to seek alternative green absorbent as a substitute. Deep eutectic solvents (DESs), a less toxic solvent than ILs discovered in 2001 have been actively researched as a substitute solvent since 2013. This review aims to comprehensively discuss DESs for desulphurization application emphasizing on the factors affecting extraction-desulphurization. DESs as a solvent for extraction-desulphurization exhibited high sulphur removal capabilities. Selection of DESs, extraction time, extraction temperature, model oil ratio, multistage extraction and DESs regeneration are deemed to affect the desulphurization yield. Economical raw material and synthesis cost, low solvent to feed treat ratio and beneficial green solvent characteristic exhibit DESs' suitability for desulphurization.
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•Sulphur dioxide adversely affects human health and ecosystem.•Stringent regulations enforced to reduce allowable sulphur content in fuel•Reliance on hydrodesulphurization solely causes significant increase in cost.•Toxicity of ionic liquids leads to research seeking green solvent as substitute.•Deep eutectic solvents suitable for extractive-desulphurization
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•Two core–shell MOFs were synthesized by transmetalation and secondary-growth.•MOFs contained the redox pairs Fe(II)/Cu(I) and Fe(III)/Cu(II)•Two core–shell MOFs were recovered and ...regenerated for at least five cycles.•More than 85% NO and 100% of SO2 are removed in the MOFs/PMS solution.•ROS responsible for NO/SO2 removal included SO4•-,•OH and 1O2.
Advanced oxidation process is a simple and cost-effective approach for the simultaneous removal of SO2 and NO from the flue at low temperatures. Herein, two core–shell hierarchical metal organic frameworks (MOFs), namely FeBDC@CuBDC (Iron terephthalate@Copper terephthalate) and FeBDC@CuBTC (Iron terephthalate@Copper triphenylenetriate), were successfully synthesized through Cu partial exchange and the secondary growth on surface of FeBDC, respectively. These MOFs were utilized to activate efficiently peroxymonosulfate (PMS). In the two MOFs, the metals existed in multiple valence states, specifically Fe(II)/Fe(III) and Cu(I)/Cu(II), favoring the high catalytic activity. In these MOFs/PMS solutions, more than 85% NO was removed and SO2 was completely eliminated. FeBDC@CuBTC and FeBDC@CuBDC were recovered and regenerated for at least 5 cycles. The high catalytic activity of these MOFs was attributed to the high content of Fe(II)/Cu(I) achieved by the rapid reduction of Fe(III)/Cu(II) with O2•-. Through the analysis of reactive oxygen species in the MOFs/PMS, it was observed the NO removal was influenced by both free radical processes (SO4•-,•OH) and non-free radical processes(1O2), whereas the SO2 removal was controlled primarily by free radical processes (SO4•- and •OH).
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•Core-shell h-ZIF-8@Cu/Ni/ZnO@CNTs heterostructure was prepared & characterized.•h-ZIF-8@Cu/Ni/ZnO@CNTs photocatalytic reactor was operated for desulphurization.•Deep desulphurization ...of coal with removal rate of 0.7 kg m−3 day−1 was achieved.•Dibenzothiophene with removal rate of 3.3 kg m−3 day−1 was converted in sulphate.•h-ZIF-8 shell porous network act as organic sulphur adsorption & conversion center.
Developing efficient methods for deep desulphurization of commercial fuel is critical because of the requirements to limit sulphur concentrations below 10 ppm. Among various methods, recently photocatalytic oxidative desulphurization (PODS) has attracted great attention as it does not require high temperature and pressure. Herein, we report a novel heterostructure h-ZIF-8@Cu/Ni/ZnO@CNTs, having heterometallic ZIF-8 (h-ZIF-8) coated on Cu/Ni/ZnO (h-ZIF-8@Cu/Ni/ZnO), supported over carbon nanotubes (CNTs) sponge for selective PODS of both coal and fuel. The Cu/Ni/ZnO-based ternary hybrid metal oxide was first stabilized on a CNTs sponge followed by a surface reaction of metal particles with 2-methyl imidazole to in-situ form h-ZIF-8 shell on the surface of Cu/Ni/ZnO. The resulting h-ZIF-8@Cu/Ni/ZnO@CNTs exhibited high surface area (1283.47 m2/g), meso/microporous backbone, narrow bandgap (2.52 eV), and a large number of available active sites. Owing to these characteristics, the h-ZIF-8@Cu/Ni/ZnO@CNTs exhibited excellent photocatalytic response for the removal of organic sulphur with a removal rate of 0.76 Kg m−3 day−1 compared to control ZIF-8@ZnO@CNTs (0.4 Kg m−3 day−1). The removal rate was further enhanced to 3.3 Kg m−3 day−1 for dibenzothiophene, confirming the higher PODS potential of the designed photocatalyst for refractory organic sulphur. In summary, the h-ZIF-8@Cu/Ni/ZnO@CNTs possess promising characteristics to be applied for the desulphurization of commercial fuels.
This review discusses some of the processes that have been, or are being, developed as an alternative/addition to present-day hydrodesulphurization processes that are based on (selective) ...heterogeneous catalysis. The technologies applied in these alternatives range from reactive adsorption, oxidative routes (especially for diesel) and other chemical conversion methods, to “simple” physical separation methods (non-destructive adsorption, extraction,
etc.). It is concluded that it appears that for the time being, as long as sulphur levels of 10
ppmw or slightly below are aimed at, the classical hydrotreating options and their off shoots still hold the field of transportation-fuel desulphurization, although a few of the possible alternatives do have achieved commercial status in the gasoline area. If, on the other hand, S in product levels should be as low as <1
ppmw, then polishing processes will come into their own.
•Changing Fenton reagent from uniparental to amphiphilic by Amphiphilic Janus material.•Supporting the Production of Hydroxyl Radicals by Ultrasound.•Improving the oxidative desulfurization ability ...and reusability of Fenton reagent.
Fe3O4 was obtained by reacting FeCl2 and FeCl3 with polyethylene glycol, and labeled onto a amphiphilic Janus nanosheet. It was confirmed by infrared spectroscopy, SEM, AFM and EDS that the Fe3O4 nanoparticles changed from hydrophilic to amphiphilic. The oxidative desulfurization performance of amphiphilic iron oxide was studied. Results showed that the Janus nanosheets labeled with Fe3O4 could significantly improve the removal rate of thiophene sulfide in simulated oil synergistically with ultrasonic waves, and the desulfurization rate could reach 100%. Further, the effect of ultrasound on the sensing ability of the oil–water interface was studied and the ultrasonic attenuation coefficient was calculated. In addition to the desulfurization mechanism of Fe3O4, it was found that although the ultrasonic attenuation coefficient of the amphiphilic nanosheets was high, the number of hydroxyl radicals determined the desulfurization efficiency. The amphiphilic Fe ions were more favorable for the formation of hydroxyl radicals than the single hydrophilic ones.
A sustainable method is employed to remove polycyclic aromatic sulphur heterocycles (PASHs) from fuels by using a series of high surface area nanoporous adsorbents synthesized from polycyclic ...aromatic hydrocarbons (PAHs). The hypercrosslinking of PAHs has been used to synthesize high surface area (SABET of 620–1565 m2 g−1) nanoporous polymeric materials via a microwave assisted method. The adsorbent poly-naph (highest SABET, i.e., 1565 m2 g−1) display best performance for desulphurization of fuels from batch to fixed bed column mode. In batch mode, the adsorption capacity of 12.1 (up to 9 ppm sulphur) and 8.9 mgS g−1 (up to 43 ppm sulphur), has been estimated for model (100 ppm sulphur) and real fuels (110 ppm sulphur), respectively. Furthermore, from ultra-low sulphur model (10 ppm sulphur) and real fuel (9 ppm sulphur), the adsorption capacity of 16.1 (up to 0.3 ppm sulphur) and 10 mgS g−1 (up to 3 ppm sulphur) has been estimated. In fixed-bed column mode, the high concentrated model and real fuel have been desulphurized to final concentration of 1 and 12 ppm, respectively. While, at low concentrations, the final concentration of 100 ppb and 1 ppm is achieved for model and real fuels, respectively. The adsorption mechanism revealed that π-electron density in the polymeric framework plays prominent role in the adsorption process apart from high surface area. This approach to control carcinogenic aromatic pollutants like PAHs and PASHs can be sustained over time through technological advancement, financial assistance and governmental regulation.
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•Polycyclic aromatic hydrocarbon pollutants are used to develop adsorbents.•A rapid microwave assisted 60 min synthesis is used.•Desulphurization of fuel at high (∼100 ppm) and low (∼10 ppm) sulphur concentration.•Batch to fixed-bed column mode desulphurization of model and real fuels.•Polycyclic aromatic sulphur heterocycles are removed by developed adsorbents.
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•A database of SO2 absorption by DESs containing 1382 data points is established.•A novel model of SO2 capacity is developed by MLP method and COSMO-RS.•Molecular design on DESs is ...provided by SHAP analysis.•DESs candidates are screened for selective SO2 absorption.
Sulfur dioxide (SO2) is a common air pollutant, primarily emitted from fossil fuel combustion and industrial flue gas. Deep eutectic solvents (DESs) have been proven to be innovative, sustainable SO2 absorbents. Meanwhile, the relationships between DESs molecules and their SO2 capacity or SO2 absorption selectivity in the gas source containing carbon dioxide (CO2) are unclear. In this work, a multilayer perceptron (MLP) model was developed to predict the SO2 capacity of DESs based on the database containing 1382 SO2 capacity data from the literature. The SO2 capacity with respect to the chemical and physical absorption was investigated. The optimal MLP model (R2 (coefficient of determination) = 0.9924, MSE (mean square error) = 0.0009) with 13 input descriptors including COSMO-RS (Conductor-like Screening Model for Realistic Solvents) theory descriptors and temperature, pressure, and water concentration validated its superior predictive capability in forecasting both physical and chemical absorption. From the SHAP (Shapley Additive Explanations) analysis, the DESs candidates with high SO2 capacity should consider anionic and relatively long-branched components. A database containing 924 novel DESs was constructed. Through the integration of this model with a predictive model for CO2 capacity, the promising candidates with high selectivity of SO2, such as N444Cl (tetrabutylammonium chloride) and 2-Mim (2-methylimidazole), were effectively identified within the novel database. This work offers insights for screening suitable DESs for the flue gas desulphurization (FGD) process.
•Evaluated removal of dual ring thiophene’s from dodecane using cavitation based processes.•Hydrodynamic cavitation without additives was unable to remove dual ring thiophene’s.•Used various ...additives with cavitation and quantified removal of dual ring thiophene’s.•The recommended additives are useful for enhancing desulphurization performance.
Utilising cavitation for enhancing oxidative desulphurization has been investigated for nearly-two decades with recent investigations shifting focus from low-capacity acoustic cavitation (AC) to scalable hydrodynamic cavitation (HC). This work focuses on developing a viable means for removing thiophene’s from fuels. In the first phase of this work, use of vortex based HC devices for removal of single and dual ring thiophenes from dodecane was investigated. HC was shown to be able to remove single ring thiophene from dodecane without using any external catalyst or additives. However, in absence of catalyst or additives, it was not possible to remove dual ring thiophenes such as dibenzothiophene using HC. Therefore, in the second phase of this work, various strategies based on use of catalyst or additives to augment cavitation based process were investigated. AC based experiments were opted for shortlisting suitable catalysts and additives for intensifying cavitation based processes. The influence of using oxidant (H2O2) and carboxylic acid catalysts on efficacy of removal of dual ring thiophenes is presented. Several conditions were tested, and the optimal volumetric ratios of 0.95 v/v % H2O2 and 6.25 v/v % HCOOH was identified and utilised throughout the remainder of the study. Regeneration of extractant which accumulates oxidised sulphur species from dodecane was also investigated using AC. The additives and process conditions reported in this work are useful for enhancing desulphurization performance.
In this study, the influence of several operational variables of secondary steelmaking on the desulfurization process in a gas stirred ladle furnace was analyzed by mathematical simulation. The ...solution of the Navier-Stokes and energy equations were carried out using the multiphasic Eulerian model, while an User Defined Function, UDF, was developed and incorporated to numerical simulation to solve the kinetics of desulfurization. Drag and non-drag forces were also included, as well as interfacial exchange models to solve the interaction among phases. The fluidynamics results were validated by means of an experimental model by employing the Particle Image Velocimetry, PIV, technique. It was found that employed models accurately predicted slag layer behavior and steel velocity field. The results showed that the distribution of the sulfur contained into steel depends on the fluidynamics structure, initial steel temperature and injected argon gas rate. Also, the incorporation of the desulfurization kinetics through UDF’s coupled to the non-isothermal multiphase modeling, is more realistic in the prediction of the sulfur removal rate compared to the use of only kinetic models.
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•The Na-Mg-Ci3- compound absorbents were proposed and applied to repeatedly absorb SO2.•This study interpreted why the regeneration efficiency of Na3Ci absorbent was lower than that ...of Mg3Ci2 absorbent.•The performances of compound absorbents with different involved alkaline earth metals were compared.•The influence of ingredient ratios on the absorption capacity and regeneration efficiency of Na-Mg-Ci3- compound absorbents were studied.
Sulfur dioxide (SO2), as a primary pollutant in the air, has attracted much attention due to the adverse effects on the atmospheric environment and human health. The wet flue gas desulfurization (WFGD) has been proved to be the most effective method to control the emission of SO2. However, the traditional absorbents in WFGD posed the problems of limited recycling utilization and susceptible to oxidation. In this study, we proposed the Na-Mg-Ci3- compound system to repeatedly absorb SO2 for rounds. The results demonstrated that the compound system can integrate the absorption capacity of Na3Ci absorbent and the regeneration efficiency of Mg3Ci2 absorbent. We compared the performances of the compound systems with different alkaline earth metals (Li, Na, K), and the sodium was most suitable for the circulating desulfurization with the consideration of performance and economy. After that, we investigated the influence of ingredient proportions on the absorbent performance, and the results showed that the 0.4 mol/L Na3Ci and 0.2 mol/L Mg3Ci2 were the best combination for the compound system in these experiments. In this condition, the compound system had the excellent effective sulfur capacity and regeneration speed in the recycling process. Moreover, the anti-oxidation effect of sodium ascorbate was explored, and the reusability performance of compound system can be improved with antioxidants. This study contributes to providing a novel method for the removal and recycling of SO2 in the wet flue gas desulphurization.
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