High Desulfurization Efficiency Research Articles

Investigations of the ODS process utilizing CNT- and CNF-based WO3 catalystsfor environmental depollution: experimental and theoretical aspects.

In this contribution, CoW/X materials (X = CNT or CNF) were utilized as oxidative desulfurization (ODS) catalysts for the removal of dibenzothiophene (DBT) from a model fuel (n-decane), incorporating the H2O2 as an efficient oxidant. Different operating conditions were investigated. Both compounds revealed high desulfurization efficiency using milder operating conditions leading to low levels of the DBT compound since only 1h while using a low ratio of H2O2/S = 6. Among synthesized compounds, the CoW (15)/CNT showed superior DBT conversion through the ODS process. In other words, the highest sulfur removal efficiency of 100% for a feed sulfur content of 500ppm was determined in a 40-min duration under optimum conditions. This was satisfyingly more effective than a recently reported CoW (20)/rGO catalyst. The characterization of synthesized catalysts was performed in order to evaluate their physicochemical properties. Moreover, product identification of the oxidation desulfurization process was performed using the GC-Mass, FTIR, and NMR techniques where it was found that this process was that of a single product. These experimental studies were complemented with density functional theory (DFT) investigations, which indeed shed important light on understanding the adsorption mechanisms as well as electronic properties of the system undertaken.

Study on the desulfurization performance of calcium-based desulfurizer and NaHCO3 desulfurizer.

The commonly used calcium desulfurizers have low desulfurization efficiency. NaHCO3 desulfurizers can meet the requirements of desulfurization efficiency, but the high price and the difficulty in handling desulfurization products make dry flue desulfurization technology quite difficult to realize the large-scale application. Preliminary research found a new calcium desulfurizer, to understand its performance, comparing investigation into the desulfurization performance of different calcium desulfurizer and NaHCO3 desulfurizer. The results showed that with the high-performance calcium desulfurizer, conventional NaHCO3 desulfurizer, and ultrafine NaHCO3 desulfurizer, the operating time with 100% desulfurization efficiency is 25,200, 21,600, and 6000s, when the flue temperature of 373.15-573.15K, the "break-through" temperature is 533.15, 473.15, and 373.15K, expand the use range of desulfurizer flue gas temperature. Regarding the desulfurizer per unit mass, the production costs of ultrafine NaHCO3 desulfurizer are 5.36 times higher than calcium desulfurizer. Compared with NaHCO3 desulfurizer, high-performance calcium desulfurizer is characterized by several advantages, including high desulfurization efficiency, wider applicable temperatures, and low preparation cost, allowing for significant development potential in flue gas desulfurization.

Utilization of sludge templated carbide slag pellets for simultaneous desulfurization and denitrification: Low and moderate temperatures and synergetic mechanism

Higher SO2 and NO removal requirements have been proposed for a low carbon, flexible power generation. In this study, a low-carbon, high-efficiency, and low-cost mixed pellet was prepared through synergistic utilization of carbide slag and sludge. Further, this work systematically explored its combustive properties and SO2 and NO removal capabilities. The results indicated that more efficient mass transfer and catalyzed reactions were integrated into the unique pellet structure. The sludge-added mixed pellets exhibited good denitrification ability, at low and moderate temperatures, and improved the desulfurization performance of carbide slag. The pellets with carbide slag to sludge mass ratio of 10:3 has a 12.3% higher desulfurization efficiency than 10:0 pellets, as sludge extended the duration of the chemical reaction control phase and reduced the diffusion resistance of the product layer during desulfurization. The sludge-added pellets had satisfactory denitrification efficiencies of up to 70% at 550 °C, primarily due to the homogeneous and heterogeneous reductions between NO, pyrolysis gas, and char, which formed in the pre-combustion phase of sludge; these NO reduction processes were significantly catalyzed through carbide slag-CaO surface reduction and reoxidation. Notably, more C(O) and C(N) groups formed on the char surfaces under trace atmospheric O2 concentration (≤1%), enhancing NO reduction. This pellet combustion process conforms to the three-dimensional diffusion reaction model. This study will provide a theoretical direction for high value waste utilization of carbide slag and sludge and facilitates the industrial application of thermal power flexible variable load pollutant control.

Novel photocatalyst system to deep desulfurization of petroleum model and gas condensate by Box–Behnken design

In this research, cobalt (Co)/molybdenum (Mo) and nickel (Ni) doped with titanium dioxide (TiO2) were loaded onto multi-walled carbon nanotubes (MWCNTs). Then, the magnetization catalyst, iron oxide (Fe3O4), was loaded on them, which was used for the deep desulfurization of dibenzothiophene (DBT). These catalysts were characterized by X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, energy-dispersive X-ray spectroscopy, differential reflectance spectroscopy, and Brunauer–Emmett–Teller, Barrett–Joyner–Halenda, and vibrating sample magnetometer techniques. The photocatalytic activity of these catalysts was experienced under visible light using DBT. The response surface methodology based on the Box–Behnken design was used to evaluate parameters, including catalyst dosage (g), time (min), and concentration of DBT (mg L−1). The highest degradation efficiency under optimal conditions for CoMoNi/TiO2/MWCNTs/Fe3O4 catalysts with a catalyst dosage of 0.3 g, a time of 180 min, and a concentration of 50 mg L−1 was 99.99%. Optimum conditions were studied for desulfurization of the gas condensate. The highest desulfurization efficiency (90.33%) was obtained by the CoMoNi/TiO2/MWCNTs/Fe3O4 catalyst.

Dielectric properties of organic sulfur components and application in coal microwave desulfurization

ABSTRACT Changes in the dielectric properties of benzene mercaptan, benzene sulfide, and dibenzothiophene at 915 MHz frequency within 20 °C–100°C was studied for the first time. Coal-like substances were prepared by loading the compounds onto low-sulfur coal, and desulfurization test was performed under the microwave condition of 915 MHz and microwave – HCOOH–H2O2 system. The desulfurization reaction path and mechanism were summarized, and the relationship between the dielectric properties of organic sulfur and desulfurization efficiency was established. Results showed that the microwave-absorption ability of dibenzothiophene was weaker than that of benzene mercaptan and phenyl sulfide, and its dielectric properties changed irregularly with temperature. Dibenzothiophene cannot be removed by microwave radiation. Benzene mercaptan and phenyl sulfide had the highest efficiency of absorbing microwave energy and converting it into heat energy at 60°C. Moreover, they have the highest microwave desulfurization rate of up to 14%. In the microwave – HCOOH–H2O2 oxidation system, the highest desulfurization rates of phenyl sulfide occurred at 100°C because water-soluble products (such as sulfonate and sulfate) increased in the oxidation products. However, phenyl sulfide still had the highest desulfurization efficiency at 60°C. The desulfurization rates at 60°C and 100°C were 38% and 51%, respectively.

High-Efficiency Desulfurization of High-Sulfur Bauxite Calcined in a Conveyor Bed: Kinetics, Process, and Application

The reaction process, mechanism, and kinetics of the desulfurization of high-sulfur bauxite during calcination were investigated using thermal analysis–infrared analysis. A conveyor-bed calcination system was used to study the variations in the physical phase, desulfurization rate, and alumina dissipation rate of high-sulfur bauxite in the range of 500 °C–650 °C. The results show that sclerite monohydrate, kaolinite, rhodochrosite, pyrite, and dolomite mainly decompose during the calcination of high-sulfur bauxite, generating H2O(g), CO2, and SO2 as gaseous products. The decomposition of sclerite monohydrate and kaolinite and the dehydroxylation reactions of rhodochrosite and pyrite occur at <650 °C, with inseparable temperature overlap. High-sulfur bauxite desulfurization follows a three-dimensional spherical diffusion mechanism, with an activation energy of 181.16 kJ/mol, controlled by the diffusion rate of O2 or SO2 through the solid product layer. High-sulfur bauxite was calcined at 600 °C–650 °C for around 3.5 s in a conveyor bed, resulting in a negative divalent sulfur content of <0.03 wt.%, desulfurization rate of >0.98, and relative dissolution rate of alumina of >99%, satisfying the requirements of aluminum extraction via the Bayer method. The desulfurization rate predictions of the kinetic model were consistent with the experimental data.

Encapsulated peroxophosphotungstates catalyst into magnetic MOF: Magnetically recoverable heterogeneous high efficiency desulfurization catalyst

High activity peroxophosphotungstates with different organic cations were encapsulated into the metal-organic framework modified by magnetic nanoparticle (Fe2O3/MIL-101) to prepare the magnetic supported catalysts, which were used to improve the diesel desulfurization efficiency. The desulfurization result shows that one selected catalyst, (BTA)3PW4 @Fe2O3/MIL-101, possesses high catalytic activity in the oxidation of various organic sulfides with H2O2 as green oxidant. The catalyst can be magnetically recycled and reused for ten consecutive cycles without significant decrease in activity. Based on the GC-MS and EPR results, it is confirmed that sulfides are oxidized to corresponding sulfones in the presence of •OH radical. In a word, the high activity, good stability and reusability of catalyst prepared in this work make it have a good prospect of industrial application.

Effective removal of hydrogen sulfide from landfill gases using a modified iron pentacarbonyl desulfurization agent and the desulfurization mechanism

High-efficiency desulfurization is key to the recovery and use of landfill gases. In this study, a nano‑iron oxide desulfurization agent modified from iron pentacarbonyl was prepared in n-decane (DE) and hexadecane (HE) by ultrasonic disruption without any supporting materials and its hydrogen sulfide removal ability and desulfurization mechanism were studied. The yield of the desulfurization agent was higher when HE was used as the solvent; however, the products generated by both solvents had the same crystal type and similar properties. The efficiency of the desulfurization agent was significantly improved at 150–200 °C, exceeding 90% at 150 °C with single sulfur production. The maximum sulfur adsorption capacity of the desulfurization agent produced after 3 h of DE ultrasonic treatment at 200 °C (DE3) was 492 mg/g (desulfurization efficiency = 97.33%), while that of the agent produced after 3 h of HE ultrasonic treatment at 250 °C (HE3) was 522 mg/g (desulfurization efficiency = 99.30%). The desulfurization reaction involved both chemical adsorption and catalytic decomposition and the catalytic decomposition reaction rate was lower than that of chemical adsorption. Therefore, the more FexSy produced in the chemical adsorption process, the better catalytic performance was.

Ultra-deep photocatalytic desulfurization of dibenzothiophene over hollow Core-shell N-doped graphene nanospheres anchored bimetallic single atoms under visible light

HCS-NG-Ni/Cu nanospheres composed of the 100–120 nm hollow core- shell N-doped graphene with lattice spacing d = 0.25 nm were prepared by a facile method and their surfaces were decorated with d = 0.14 nm Ni and d = 0.12 nm Cu single atoms. Characterization of HAADF-STEM, XPS, Raman, and photoelectron-chemi- cal showed the morphology of Ni/Cu was a single atomic state on the hollow core- shell N-doped graphene, which could effectively inhibit the photoelectron-hole pair recombination leading to improve the efficiency of photocatalytic desulfurization. The influence of metal loading, Ni:Cu ratios, time, catalyst amount, and different catalysts on the removal of DBT were investigated. Results indicated the hollow core–shell N-doped graphene decorated with Ni/Cu had higher photocatalytic removal ratios (>99.1%) than the others under the mild conditions and had a high activity even after 10 cycles because of the synergism of single Ni/Cu atoms and the hollow core–shell N-doping-graphene under visible light. The energy barrier and the removal rate constant of DBT were 78 kJ/mol and 3.79*10-2, respectively, and the photocatalytic mechanism was assumed. Researches provided not only a high-efficiency desulfurization catalyst to produce clean fuel, but also a new idea on designing bimetallic single-atom catalysts.

Numerical simulation study on gas-solid flow characteristics and SO2 removal characteristics in circulating fluidized bed desulfurization tower

Circulating fluidized bed flue gas desulfurization technology is widely used in the world. The computational particle fluid dynamics (CPFD) numerical simulation method was used to study the gas-solid two-phase flow and desulfurization characteristics in the circulating fluidized bed desulfurization tower. The CPFD method is based on the MP-PIC method, which uses the stochastic particle method for the particle phase and the Euler method for the fluid phase to solve the dense particle flow. The established model was firstly verified by the experimental results of gas-solid flow field and desulfurization efficiency. Then, the effects of flue gas parameters on the flow field in the desulfurization tower and the effects of flue gas parameters, SO2 inlet concentration, and Ca/S on desulfurization efficiency were numerically simulated. An effective optimization scheme was also proposed to improve the desulfurization efficiency. The research results showed that the CPFD simulation results were in good agreement with the experimental results, which proved the reliability of the method. The particle motion state in the bed of the desulfurization tower presents a core-annular flow. As the flue gas inlet flow increased, the distribution of flue gas and particles has a serious deviation, and the desulfurization efficiency also decreased. The desulfurization efficiency will decrease with the increased of SO2 inlet concentration and increased with the increased of Ca/S. According to the distribution of SO2 concentration in the bed, three characteristic desulfurization zones can be proposed, namely, the initial mixing process zone, the high-efficiency desulfurization process zone, and the low-efficiency desulfurization process zone. Installing a baffle at the bottom of the desulfurization tower can optimize the distribution of gas-solid two-phase flow in the bed and the desulfurization efficiency.

Upgrading of low-grade high-sulfur lignite using differential dynamic field dry cascade cleaning apparatus

Coal is an important cornerstone to ensure national energy security under the new situation. China is rich in lignite reserves. In recent years, with the increasing consumption of high-quality coal resources, the development and utilization of low-grade lignite resources has become extremely urgent. Promoting the clean and efficient utilization of low-grade lignite resources is an important way to achieve the goal of carbon emission peak and carbon neutrality. In this paper, the low-grade high-sulfur lignite is desulfurized and ash-reduced by using the differential dynamic field dry cascade separation bed. The temporal and spatial migration and distribution law of material sulfur content in the cascade separation bed are mainly studied, and the dominant period of particle migration is determined. The effects of vibration intensity and airflow velocity on the density uniformity and stability of differential dynamic field cascade separation bed are systematically analyzed. At the same time, the cascade distribution characteristics of low-grade high-sulfur lignite in different transverse areas of the separation bed are explored, and the transverse separation functional area is determined. The experimental results show that when the separation time T = 0–6 s, the particle system is dominated by mixed migration; when T = 0–12 s, the particle system is dominated by mixed-regional layering migration; when T = 0–18 s, the particle system is dominated by stratified migration; when T = 0–24 s, the particle system is dominated by inspective stratification. It is determined that the area of 0–700 mm along the X axis is the transverse separation domain of the materials; the area of 700–1400 mm along the X axis is the transverse transition domain of the materials, and the area of 1400–2000 mm along the X axis is the transverse diffusion domain of the materials. When the operating parameters are in the range of A = 3.1 mm, f = 29 Hz, and v = 0.212–0.314 m/s, the uniformity and stability of the bed density are the best. The low-grade high-sulfur lignite was separated and upgraded by cascade separation bed and the separation result are shown as follows. The sulfur content of clean coal was 0.98%, the ash content was 8.96%; the yield was 67.32%. The sulfur content of gangue was 16.77%, the ash content was 69.59% and the yield was 32.68%. The probable error Ep is 0.1 g/cm3, which means that the high-efficiency desulfurization and ash reduction of low-grade and high-sulfur lignite are realized.

Synthesis of Surrogate Blends Corresponding to Petroleum Middle Distillates, Oxidative and Extractive Desulfurization Using Imidazole Ionic Liquids

Surrogate fuels are composed of a few pure components, mixed together in order to imitate a real fuel’s characteristics regarding its combustion and emission. In this study, four surrogate feeds were synthesized, corresponding to petroleum middle distillates. The desulfurization of the surrogate blends was performed using the hydrogen peroxide–acetic acid oxidative system. Consequently, extractive desulfurization was carried out using imidazolium-based ionic liquids, namely 1-butyl-3-methylimidazolium bromide [BMIM][Br] and 1-butyl-3-methylimidazolium hydrogen sulfate [BMIM][HSO4], in a multiple extraction cycle procedure. Both ionic liquids were synthesized and characterized with spectroscopic techniques. The influence of the extraction temperature process was studied. In each extraction cycle, the sulfur concentration and the physical properties of the surrogate extraction products were estimated. The used ionic liquids were regenerated with a reasonably effective method. The synthesized and recycled ionic liquids showed high desulfurization efficiency, while [BMIM][Br] prevailed. Additionally, extractive desulfurization in oxidized surrogate LCO using ionic liquids is comparable with that using acetonitrile, since it has an advantage in terms of mass yield.

High efficiency desulfurization behavior by the sustainable low carbon utilization of carbide slag

For the purpose of the gradual decrease of calcium carbonate resources and reduction of carbon emissions in wet flue gas desulfurization process, the utilization process of carbide slag to replace limestone is systematically analyzed. The properties of carbide slag and limestone have been analyzed, and the mass transfer and reaction behaviors in desulfurization process have been calculated and comprehensively evaluated. Desulfurization performances have been also compared through response surface analysis method. The results show that the calcium content and specific surface area of carbide slag are higher than limestone, which is conducive to the dissolution and mass transfer rate. Therefore, carbide slag is suitable for the treatment of flue gas with high SO2 concentration. Desulfurization efficiencies of the two desulfurization agents of carbide slag and limestone under the optimal process are 99.15% and 96.53%, respectively. In conclusion, carbide slag can be used in desulfurization process to replace limestone. The consumption of carbide slag slurry in the desulfurization process is about half of limestone slurry at the same conditions, and the higher desulfurization efficiency of carbide slag is attributed to the higher mass transfer and dissolution rate. Utilization of carbide slag also reduces the carbon emission in desulfurization process and economic cost. The reduction amount of CO2 emission can reach to about 0.76 t /t carbide slag. This work provides a basis for the industrial application and desulfurization efficiency improvement of carbide slag as the desulfurizer.

Evolution of nickel species in reactive adsorption desulfurization of benzothiophene

Reactive adsorption desulfurization (RADS) is one of the main means for the ultra-deep desulfurization of gasoline. Metallic Ni is normally assumed as the main RADS active site, and NiSx is the intermediate phase during RADS process. In this work, the evolution of nickel species, especially NiSx, were examined over NiO/ZnO-Al2O3-SiO2 and NiSO4/ZnO-Al2O3-SiO2 adsorbents. Results showed that both of the adsorbents performed high desulfurization efficiency. However, differences of the activation mechanism were observed. For the NiO adsorbent, BT (benzothiophene) can be adsorbed onto the reduced Ni sites, then the C-S bond ruptures to form NiSx. For the NiSO4 adsorbent, NiSO4 phase are firstly self-sulfied to NiSx in the presence of hydrogen or n-heptane. XRD and XPS results presented that NiO and NiSx could be found after the RADS reaction in two spent adsorbents. As same as the sulfurization of NiO into NiSx is a primary condition for the RADS reaction, NiSO4 can be partly in situ self-sulfied to NiSx. To verify the self-sulfidation of NiSO4, H2 pretreatment showed that there were NiO and NiSx species on the pretreated NiSO4/ZnO-Al2O3-SiO2 adsorbent, and the desulfurization performance of the adsorbent was obviously improved, indicating that the formation and accumulations of NiSx could promote the RADS activity. At last, the RADS mechanism of BT on two kinds of adsorbents are presented and discussed based on the assumption of NiO and NiSx as the main active components.

Pretreatment Techniques and Green Extraction Technologies for Agar from Gracilaria lemaneiformis.

Optimizing the alkali treatment process alone without tracking the changes of algae and agar quality with each pretreatment process will not achieve the optimal agar yield and final quality. In this study, we monitored the changes of the morphology and weight of algae with each treatment process, and comprehensively analyzed the effects of each pretreatment process on the quality of agar by combining the changes of the physicochemical properties of agar. In conventional alkali-extraction technology, alkali treatment (7%, w/v) alone significantly reduced the weight of algae (52%), but hindered the dissolution of algae, resulting in a lower yield (4%). Acidification could solve the problem of algal hardening after alkali treatment to improve the yield (12%). In enzymatic extraction technology, agar with high purity cannot be obtained by enzyme treatment alone, but low gel strength (405 g/cm2) and high sulfate content (3.4%) can be obtained by subsequent acidification and bleaching. In enzyme-assisted extraction technology, enzyme damage to the surface fiber of algae promoted the penetration of low-concentration alkali (3%, w/v), which ensured a high desulfurization efficiency and a low gel degradation rate, thus improving yield (24.7%) and gel strength (706 g/cm2), which has the potential to replace the traditional alkali-extraction technology.

ZiF-8-derived P, N-co-doped hierarchical carbon: synergistic and high-efficiency desulfurization adsorbents

Adsorptive desulfurization is an effective technology for removing aromatic sulfur-containing compounds from liquid hydrocarbon fuels, but the existing adsorbents have poor adsorption performance and stability. Herein, P, N-co-doped metal-free 3D porous carbon was first prepared by ZiF-8 and applied in adsorptive desulfurization. The incorporation of P and N heteroatoms changes the surface chemistry of the carbon skeleton, meanwhile, the P doping effectively adjusts the pore structure of the adsorbents. Accordingly, the P-NPC-1000 exhibited a remarkable adsorption capacity of 60.16 mg S/g for dibenzothiophene (DBT), with a 32% increase in adsorption capacity compared to solely N-doped carbon (45.41 mg S/g). It also demonstrated excellent reusability with adsorption capacity from 54.22 to 48.14 mg S/g after 6 cycles. The Langmuir and the pseudo-second-order kinetic models presented best fitting results for DBT adsorbing on the P-NPC-1000. Moreover, the adsorption mechanism was further investigated through DFT calculations and special adsorption experiments. It was proved that the P- and N- sites cooperate synergistically to enhance the interaction between P, N-co-doped carbon and DBT. The acid-base interaction and polar interaction between P-/N-sites and DBT, together with the pore structure, make the P-NPC-1000 highly promising in adsorptive desulfurization.

Design and preparation of polyoxometalate-based catalyst [MIMPs]3PMo6W6O40 and its application in deep oxidative desulfurization with excellent recycle performance and low molar O/S ratio

A novel polyoxometalate-based ionic liquid salt 3-(1-methylimidazolium-3-yl) propane-1-sulfonate phosphomolybdenum tungsten ([MIMPs]3PMo6W6O40) was designed, prepared, and used as a catalyst in oxidative desulfurization (ODS). The catalyst was characterized by FT-IR, 1HNMR, XRD, XPS, TG-DTA, and Contact angle testing etc. The [MIMPs]3PMo6W6O40 shows high activity in dibenzothiophene (DBT) oxidative desulfurization, which can remove all the DBT in model oil with a low O/S molar ratio. The O/S molar ratio, reaction temperature, and different sulfur compounds were evaluated in detail. In addition, the catalyst still possesses high desulfurization efficiency in the presence of aromatic hydrocarbons. It is noteworthy that when the reaction temperature is 60 °C, the O/S molar ratio is 2.5, and the reaction time is 120 min, the catalyst exhibited excellent recycle lifetime of 33 times without significant decline of the activity. Furthermore, the content of sulfur compounds could also be reduced to 9 μg/g in real diesel.

Optimization of wet flue gas desulfurization system using recycled waste oyster shell as high-grade limestone substitutes

Wet flue gas desulfurization, which is performed in many thermal power plants, has a high desulfurization efficiency and produces desulfurized gypsum as a by-product. Currently, high-grade limestone with a CaCO3 content of 94 wt% or more is used to produce desulfurized gypsum with a purity of 93 wt% or more. However, high-grade limestone resources are depleting, so new substitutes to this are required. The objective of this work is to optimize the wet flue gas desulfurization system using recycled waste oyster shells as high-grade limestone substitutes. The process model was developed for predicting the optimal blending ratio of waste oyster shells to limestone with constraints of desulfurization efficiency and purity of desulfurized gypsum. A mathematical model was addressed for optimized process costs, which was a nonlinear programming problem that minimizes the total annualized cost (TAC) by considering the total product cost (TPC) and equivalent annual cost; these vary according to the blending ratio. The optimal blending ratio of waste oyster shells is 16.160 wt% or 599.536 kg/h, TPC and TAC are reduced by $ 840,721 and $ 760,543, respectively. The waste oyster shell can be utilized 4,901 t/y, which is about 20.66 wt% of the total landfilled waste oyster shell. The results of this study suggest waste oyster shells, which pose landfill and odor problems, can be used as excellent substitutes for high-grade limestone for high economic and environmental benefits.

Research Progress of Phase Transfer Catalysts Used in Oxidative Desulfurization of Fuel Oil

The removal of sulfur compounds from fuel oil has been a major concern of the fuel industry. Hydrodesulfurization (HDS) is the most common desulfurization method currently used in oil refineries. However, HDS requires high temperature and high pressure conditions, consumption of hydrogen, and the removal effect of thiophene sulfides is not ideal. In view of defects of HDS, nonhydrodesulfurization technologies have been developed. Oxidative desulfurization (ODS) is regarded as the most potential desulfurization technology to replace HDS in industry because of mild operating conditions and high desulfurization efficiency. However, most ODS reactions are performed in heterogeneous systems. The common problem is that the oxidant and sulfur-containing compounds cannot contact effectively. Phase Transfer Catalysts (PTCs) are a class of catalysts that can assist in the transfer of reactants, thereby increasing mass transfer and accelerating the reaction rate of the heterogeneous ODS system. In this review, we divide PTCs applied to ODS into quaternary ammonium salts PTCs, ILs PTCs, polymers PTCs, supported PTCs and reaction-controlled PTCs, and will systematically introduce and summarize the research progress of PTCs used in ODS system. It is pointed out that reaction-controlled PTCs have a broad prospect in ODS system. In addition, the synthesis and recovery of PTCs will be briefly described.

Extractive desulfurization of diesel fuel by amide-based type IV deep eutectic solvents

As promising green alternative solvents for ionic liquids, deep eutectic solvents (DESs) have been widely used in separation, catalysis, synthesis, etc. Most of the researches have focused on the application of DESs formed by hydrogen bonding interaction. In this paper, amide-based type IV DESs were synthesized from metal chloride and amides with coordination interaction, and they were used for extractive desulfurization of fuels. The experimental results showed the DES ZnCl2/N-methylformanilide (ZnCl2/MFA) had the highest desulfurization efficiency with the Nernst partition coefficient (KN) as 2.41. The extraction mechanism was firstly explored by Fourier transform infrared spectrometer (FT-IR) and 1H nuclear magnetic resonance (1H NMR). Then density functional theory (DFT) study suggested that π-π interactions and CH···π interactions contribute mainly to effective removal of DBT from fuel oil by DESs.