Deep Desulphurization Research Articles

Confining peroxophosphomolybdate within size-matched Zr-MOFs for extractive oxidative desulfurization

Deep desulphurization of diesel is essential because the sulfides from fuel combustion can cause acid rain, respiratory diseases and corrosion of industrial equipment. Peroxophosphomolybdate (BTA)3{PO4[MoO(O2)2]4}·3H2O, marked as PMo4, was confined in size-matched Zr-MOFs (UiO-66 and UiO-67) to prepared composites for extractive oxidative desulfurization. The composites underwent comprehensive characterization, including ICP-MS, FT-IR, XRD, SEM, XPS, TG and N2 adsorption–desorption analysis. Desulfurization test was conducted with PMo4 as homogeneous catalyst, and the reaction conditions were optimized. Then, the catalytic activity of the prepared composites was compared, and the result showed that the catalyst PMo4@UiO-67 can remove 94.1 % of the sulfides in the diesel within 100 min. After 15 consecutive tests, the total removal rate of sulfides still reached 88.5 %, thanks to the narrow window of carrier UiO-67 limited the leaching of the active component PMo4.

Utilizing polycyclic aromatic sulphur heterocycles to develop hypercrosslinked microporous polymeric adsorbents for deep desulphurization of fuels

Adsorptive desulphurization is a well-known method for removing polycyclic aromatic sulphur heterocycles (PASHs) from petroleum fractions. Nevertheless, due to the non-destructive adsorption mechanism, managing the adsorbed carcinogenic PASHs remains a major challenge. In the present research, a prototype is presented to manage three PASHs (thiophene, benzothiophene and dibenzothiophene) by using them to develop hypercrosslinked microporous polymeric adsorbents (yield > 90%) within 60 min via microwave assisted synthesis. Textural properties including specific surface area (401–628 m2 g−1), controlled pore size (1.1–1.7 nm) and pore volume (0.24–0.29 cm3 g−1) have been estimated. The developed adsorbents are used for desulphurizing diesel fuels. Batch adsorption studies result in the sulphur adsorption capacities of 6.7 and 6.4 mgS g−1, for 100 ppm and 10 ppm-dosed simulated fuels respectively. Thermodynamic, kinetics and adsorption isotherm studies are performed using the batch adsorption studies. Column adsorption studies exhibit sulphur breakthrough capacities of 7.2 and 0.62 mgS g−1 for 100 ppm and 10 ppm-dosed simulated fuels respectively. The combine effect of textural properties and π electron density on the adsorption capacity is discussed. The present work not only demonstrates a sustainable management cycle of PASHs but also utilized them for deep desulphurization of fuels.

Especially deep desulphurization of cast iron by magnesium mono-injection in ladles of different size

The article is devoted to the development and industrial mastering of technological processes of particularly deep desulphurization of cast iron (sulphur content ≤ 0.002 %) by magnesium mono-injection in ladles of various sizes. The paper presents the results of research on the development of technologies for extra deep desulphurization of cast iron by mono-injection of granular magnesium, which was carried out at modern automated cast iron desulphurization and slag rolling complexes. The work was carried out jointly by Ukrainian and Chinese specialists in China at Wuhan Steel Plant No. 1 using 110-ton ladles and in Taiwan at CSC Steel Plant No. 2 using 300-ton ladles. The proven technological parameters of the cast iron desulphurization processes using granular magnesium injection with tuyeres with evaporation chambers at Steel Plant No. 1 of Wuhan Steel and double-nozzle tuyeres at Steel Plant No. 2 of CSC Concern ensured the required processing cycles, reliable and technological magnesium injection and its absorption efficiency. It was found that the degree of desulphurization of cast iron is up to 99 % of treatments and the final sulphur content in cast iron is up to 0.0002 %, with the total estimated degree of magnesium absorption into sulphur, residual magnesium and deoxidation of cast iron being ~95 %. It has been established that an important technological technique that increases the stability of the achieved processing parameters is the adjustment of the ladle slag composition, which was carried out by adding waste granular lime in the amount of 1.0-2.0 kg/t of cast iron and did not require significant costs. The results of industrial cast iron treatments were analysed and nomograms of the dependence of specific magnesium consumption on the initial sulphur content for tuyeres of various designs were constructed. The developed processes are economically justified for use in the practice of preparing cast iron for conversion.

Formulation of heterometallic ZIF-8@Cu/Ni/ZnO@CNTs heterostructure photocatalyst for Ultra-Deep desulphurization of coal and fuels

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.

Development of a new RH desulphurisation process with powder injection through the nozzles of up snorkel

ABSTRACT A novel desulphurisation process in a RH (Ruhstahl-Hausen Process) degasser (RH aside spray technique) has been proposed, plant trials have been carried out and the ruling factors have been analysed. The results indicate that the new desulphurisation process can not only obtain high desulphurisation degree of above 80% but also avoid unfavorable fluorite powder flux. The sulfur in the molten steel can be removed from 40∼80 ppm to less than 10∼20 ppm . The injection amount of the powder flux is about 5 kg per ton steel. The desulphurisation effect is perfect and stable, which is suitable for ultra-low-carbon electrical steel deep desulphurisation in RH degasser. Enlargement of the interfacial reaction area is considered to accelerate the desulphurisation process. Further study is recommended.

Desulphurisation with dispersed in-situ phases induced by composite ball explosive reaction during ultra-low carbon steel production in RH degasser

ABSTRACT A novel desulphurization technology has been put forward using a dispersed in-situ phases induced by an explosive reaction of a composite ball. A composite ball with this function has been designed and prepared using a laboratory model batch type balling disc (at 12 rev min-1) and the composite ball has been fed at the end of Ruhrstahl-Heraeus refining. The plant trials have been carried out in ANSTEEL and the ruling factors have been analyzed. The results indicate that feeding composite ball in RH degasser is a novel technology and the sulphur in the molten steel can be removed from 30 ×10-6~50 ×10-6 to less than 10 ×10-6~20 ×10-6 with desulphurization rate more than 50%. The desulphurization effect is perfect and stable. There is few carbon pick up in molten steel. The feeding amount of the composite ball is about 5kg per ton steel. It is suitable for deep desulphurization in RH degasser.

Review of methods of slag removal from melt surface in hot metal and steel ladles

The removal of slag from melt surface of hot metal and steel ladles is a necessary condition to provide a deep desulphurization and dephosphorization of hot metal and steel in the process of their processing. A review of methods of slag skimming presented, mainly based on slag mechanical shoveling and its removal out of ladles by vacuum sucking. It was shown, that manipulators design for the slag skimming working instrument moving depends on the production scale, mass of the processed heats, amount and properties of the slag to be removed, production process intensity and ecological requirements. Peculiarities of designs and technical parameters of machines for slag skimming presented, designed by Irkutsk plant of heavy machinery, Scientific and Production Enterprise n.a. M.I. Platov, VNIIMETMASH, Kuznetsk and Novolipetsk steel plants. Technological methods of control of slag composition and physical properties considered, first of all of viscosity and fluidity, which have significant effect on selection of a method of slag skimming. Advantages and drawbacks of actions, aimed at more complete slag removal from metal surface by a scraper noted including bath blowing off by an inert gas, liquid slag tapping into am intermediate settling tank following its removal into a slag bowl. In case of satisfactory fluidity it is possible to slag removal by vacuum sucking, which at the same time promoted the melt degassing. Work done in this area abroad noted. Methods of vacuum slag removal developed in the USA and Japan described.

Global impacts of recent IMO regulations on marine fuel oil refining processes and ship emissions

This study presents an overview of the context and global impacts of recent International Maritime Organization (IMO) regulations on the marine fuel oil refining industry, future marine fuel mix and ship emissions. IMO limited marine fuel sulphur content in both Sulphur Emission Control Areas (SECAs) and Nitrogen Oxide Emission Control Areas (NECAs) to 0.1% (wt. %) by 2015, and to 0.5% globally by 2020. It is anticipated that the newly implemented IMO regulations will help to mitigate negative impact of ship emissions on public health and environment. IMO regulations require significant changes to refineries to increase the production of low sulphur fuels through a shift to distillates, use of novel deep desulphurization techniques, or fuel blending. Changes to the refinery processes can bring forth increases in greenhouse gas emissions and high capital investments. Alternative fuels will need to meet the required reduction of air pollutants and greenhouse gas emissions in coastal areas. Alternative marine fuels consisting of liquefied nature gas (LNG) and biofuel may be suitable fuels to meet both targets. These two fuels are predicted to account for 50% of shipping energy demand by 2050, while the remainder will still be supplied by conventional heavy fuel oil (HFO)/marine gas oil (MGO). Switching to low sulphur fuels as a results of the new IMO regulations has led to measureable reductions in ship emissions generally. This fuel switching also resulted in changes in engine emission characteristics, especially on particulate matter chemical composition.

Ultra-deep desulphurization of both model and commercial diesel fuels by adsorption method

Selective adsorption for removing sulfur from diesel fuel has emerged as a potential economically viable and effective alternative method to achieve the stringent environmental regulations for sulfur levels in diesel. In this paper, the sulfur removing activity of three different types of activated charcoal (AC, T103 and T104) and two molecular sieves (MS)- 13X and 5 A- were investigated, using both model diesel and commercial diesel. It was observed that AC, T103 and T104 displayed similar good sulfur removing activity and stability with both the model diesel (initial sulfur content: 1000 ppm) and commercial diesel (initial sulfur content: 43 ppm), with the sulfur removal efficiency varying from 60% up to 90% under the reaction conditions used in this work. These results also suggested that the adsorbents were better suited to polishing low sulfur diesel, to achieve ultra-low sulfur content. The experimental data for the adsorption of DBT fitted the pseudo-second-order kinetic equation more closely, which suggests chemical adsorption activity between DBT and the adsorbents AC, T103, T104 and MS 13X. Further experimental work, using commercial diesel with 43 ppm sulfur content, revealed that the adsorption affinity for different sulfur compounds in conventional diesel decreases in the following order: 4-MDBT≫ 4,6-DMDBT˜4 E,6-MDBT˜2,4,6-TMDBT˜1,4,6-TMDBT. It is believed this is due to steric hindrance. The decrease in activity with molecular weight epitomizes the limitations of the adsorbents in removing refractory organic sulfur. In conclusion, activated charcoals are much more suitable for the task of deep desulphurization of diesel fuels than are molecular sieves.

Deep Desulphurization Study of Liquid Fuels Using Acid Treated Activated Charcoal as Adsorbent

The current study addresses the improved desulphurization activity of activated charcoal modified by acetic acid treatment. The modified activated charcoal was investigated as an adsorbent for the elimination of sulfur compounds from the model oil (consisting of dibenzothiophene (DBT) dissolved in cyclohexane) as well as real oil samples including kerosene and diesel oil. In the case of model oil, about 99.5% of DBT was removed under conditions optimized in the laboratory, which included 15 mL feed (model oil) volume, 0.8 g of adsorbent, 60 °C temperature, stirring speed of 100 rpm, and contact time of 1 h under neutral pH. In the case of real oil samples, i.e., kerosene and diesel oil, sulfur removal of 78.69% and 74.29% was attained under optimized conditions, respectively. Experimental results were interpreted through model adsorption isotherms, which indicated that the adsorption process is in close agreement with the Langmuir adsorption isotherm in comparison to the Freundlich adsorption isotherm. Th...

Diesel Based SOFC Demonstrator for Maritime Applications

Emission regulations for ships are forcing ship-owners and shipyards to drastically reduce harmful species for the Emission Control Areas (ECA) along the US coast, Baltic Sea and North Sea. SOFC systems are seen as most efficient and clean alternative to conventional diesel engines. In this context, the project SchIBZ has been initiated to develop a fuel cell based generator set for seagoing ships. A consortium of industrial and academic partners has been joined to develop a diesel based SOFC demonstrator with a rated power of around 50 kW. Adiabatic prereforming of diesel is one of the most efficient type of fuel processing for SOFC systems. The feasibility of adiabatic prereforming of commercial ultra-low sulphur diesel has successfully been tested with one of Haldor Topsoe’s catalyst.The demonstrator was built to demonstrate the feasibility of the process and the robustness of the SOFC. It consists of 2 submodules supplying each 27 kW gross power. The key feature of the process is the anode gas recirculation that allows us to handle the diesel within the adiabatic prereformer without any deep desulphurization technologies on the one hand side and to increase the overall fuel utilization on the other hand side. Furthermore, an additional anode off-gas blower is used to levelize the pressure between the anode and the cathode, which reduces the risk of oxidation of the anode in case of leakages. The demonstrator was started on commercial road diesel containing 11 ppm_wt sulphur, 6.2%_vol FAME and 24%_wt aromatics. An electrical gross efficiency of 55% and fuel utilization of 73% could be demonstrated already during the first hours of operation.

Diesel Based SOFC Demonstrator for Maritime Applications

Emission regulations for ships are forcing ship-owners and shipyards to drastically reduce harmful species for the Emission Control Areas (ECA) along the US coast, Baltic Sea and North Sea. SOFC systems are seen as most efficient and clean alternative to conventional diesel engines. A diesel based SOFC demonstrator is developed with a rated power of around 50 kW. It consists of 2 submodules supplying each 27 kW gross power. The key feature of the process is the adiabatic prereforming process that allows us to handle the diesel without any deep desulphurization technologies. Adiabatic prereforming of diesel is one of the most efficient types of fuel processing for SOFC systems. The feasibility of adiabatic prereforming of commercial ultra-low sulphur diesel has successfully been tested with one of Haldor Topsoe’s catalyst. The demonstrator was started on commercial road diesel containing 11.3 ppm_wt sulphur, 6.2%_vol FAME and 24%_wt aromatics. An electrical gross efficiency of 55% and fuel utilization of 73% could be demonstrated already during the first hours of operation.

Control of sulphur for spring steel killed by Si–Mn and with low basicity slag

Experiments are carried out in the case of low basicity slag for spring steel killed by Si and Mn, then the changes of the sulphur content, the sulphur distribution ratio LS and inclusions are investigated. Finally, the effect on desulphurisation of oxygen content in molten steel, the calculated and measured lgLS and the deep desulphurisation of the vacuum degassing station are discussed. It is found that the most sulphur in liquid steel is mainly removed during the early stage of LF refining. The average sulphur content in steel and the sulphur distribution ratio after the soft bottom-blown are 0.0047% and 115, respectively. It is very accurate and credible to use the LS model to predict LS. During the early stage of LF refining, to reduce the oxygen content in steel quickly is very crucial for the rapid desulphurisation of the Si and Mn killed spring steel with low basicity slag. The desulphurisation of molten steel can be further carried out during the VD refining station and it is beneficial to reduce the sulphur content for the control of sulphide in spring steel killed by Si–Mn and with low basicity slag.

Synthesis of a hybrid Anderson-type polyoxometalate in deep eutectic solvents (DESs) for deep desulphurization of model diesel in ionic liquids (ILs)

A novel hybrid Anderson-type polyoxometalate, {[(CH3)3N(CH2)2OH]2}[H0.2K0.2Na2.6(H2O)6][IMo6O24] (Abbreviated as (ChO)2K0.2Na2.6IMo6) was synthesized in a deep eutectic solvent and characterized by XRD, FT-IR, thermal analysis, electrochemical measurements and inductively-coupled plasma, atomic emission spectrometer (ICP-AES). This hybrid polyoxometalate was used as a catalyst in ionic liquids (ILs) for desulfurization of model diesel. The catalyst (ChO)2K0.2Na2.6IMo6 in the extraction and catalytic oxidative desulfurization (ECODS) system, containing H2O2 and 1-octyl-3-methylimidazolium tetrafluoroborate (OmimBF4), displayed so high activity that the removal of DBT can reach 100% at 60°C in 60min. Sulfur removal for S-compounds was in the following order: DBT>4,6-DMDBT>BT. The desulfurization system shows so good stability that it can be recycled 20 times without noticeable decrease in activity.

Oxidative desulphurization of model fuel by in situ produced hydrogen peroxide on palladium/active carbon

AbstractThiophenic compounds are considered one of the major obstacles in deep desulphurization of transportation gasoil. In this paper, a single‐stage reactor, in which the induction of hydrogen peroxide, oxidation of thiophenes, and adsorption of sulphones from model fuel was demonstrated in one single step at mild temperatures. In our proposed mechanism, the removal of thiophenes from model fuel undergoes three stages: 2‐propanol dehydrogenation and in situ generation of hydrogen peroxide, oxidative desulphurization, and the adsorption of sulphones on active carbon. Palladium/active carbon (Pd/C) was not only used to catalyze the production of hydrogen peroxide, but also guarantees efficiency in the adsorption of sulphones from the oil phase and aqueous phase owing to its large specific surface area and pore volume. Thus, the goal to get ultra‐low sulphur fuel was well achieved under optimal conditions after almost all the sulphones had entered into the pores of active carbon and stayed in the adsorbent. Accumulation of sulphur in active carbon inhibits further desulphurization operation. Washing with excessive anhydrous ethanol, the efficiency of Pd/C was almost fully recovered.

A Non-catalytic Deep Desulphurization Process using Hydrodynamic Cavitation.

A novel approach is developed for desulphurization of fuels or organics without use of catalyst. In this process, organic and aqueous phases are mixed in a predefined manner under ambient conditions and passed through a cavitating device. Vapor cavities formed in the cavitating device are then collapsed which generate (in-situ) oxidizing species which react with the sulphur moiety resulting in the removal of sulphur from the organic phase. In this work, vortex diode was used as a cavitating device. Three organic solvents (n-octane, toluene and n-octanol) containing known amount of a model sulphur compound (thiophene) up to initial concentrations of 500 ppm were used to verify the proposed method. A very high removal of sulphur content to the extent of 100% was demonstrated. The nature of organic phase and the ratio of aqueous to organic phase were found to be the most important process parameters. The results were also verified and substantiated using commercial diesel as a solvent. The developed process has great potential for deep of various organics, in general, and for transportation fuels, in particular.

Investigating role of sulphur specific carbon adsorbents in deep desulphurization

Adsorptive desulphurization of model fuel (thiophene in isooctane) was studied by using sulphur specific carbon based adsorbents, SHIRASAGI GH2x 4/6 and SRCx 4/6, in an attempt to obtain insight into the adsorptive behaviour of sulphur moiety on the modified surfaces. Both adsorption equilibria and adsorption kinetics have been reported. Characterization of the modified adsorbents was carried out using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction (XRD) and surface area analyser. Adsorption experiments along with characterization results highlight potential for higher sulphur adsorption on the modified adsorbents. Substantially higher capacities for adsorption of thiophene were obtained, ∼5.5 and ∼20mgg−1 of sulphur for SHIRASAGI GH2x 4/6 and SRCx 4/6 respectively. Experimental investigations reveal possible influence of Al/Si ratio, 12.46 and 9.35 in GH2x and SRCx respectively that can have implication in adsorption behaviour. It was found that surface modification plays important role in enhancing sulphur removal capacity as compared to conventional carbon adsorbents. A plausible mechanism to account for surface interactions and role of surface modification has been proposed. The higher mesopore volume along with higher oxygen content is believed to influence preferential adsorption of thiophenic sulphur by SRCx. The work also indicated specific role of Al and Si content in the carbon matrix. The utility of these adsorbents and higher sulphur removal capacity has also been confirmed using synthetic mixture of refractory sulphur compounds such as benzothiophene, dibenzothiophene along with thiophene.

Novel Strategy to Produce Ultrapure Hydrogen from Coal with Pre-combustion Carbon Capture

Abstract Integrated Gasification Combined Cycles (IGCCs) are one of the emerging clean coal technologies which paves the way for producing power from coal with a higher net power efficiency than conventional PC-fired boiler power plants. It is also advantageous that in an IGCC power plant a carbon capture unit can be applied to a stream having a very high CO2 partial pressure upstream of gas combustion that would not be available in case of a PC-fired boiler power plant, leading to less energy penalty involved in the carbon capture. In this study it is aimed to design a cogeneration process where a Hydrogen Pressure Swing Adsorption (H2 PSA) unit is retrofitted to an IGCC power plant with pre-combustion capture for producing ultrapure hydrogen (99.99+ vol%). The ultrapure hydrogen is commonly utilised as feedstock for deep desulphurisation and hydrocracking units at refineries as well as H2 fuel cells. It is found that, at the same H2 purity of 99.99 + %, the hydrogen recovery could be improved up to 93% with the increasing number of columns. Improving the H2 recovery at the H2 PSA to its maximum can contribute to reducing the power consumption for compressing the H2 PSA tail gas by minimizing the yield of the H2 PSA tail gas by-product. Furthermore, it is demonstrated that the H2 PSA can also be designed to achieve 90% H2 recovery even when a portion of the tail gas is recycled to the shift reactors in order to improve the overall advanced IGCC performance by increasing the H2 yield and by reducing the auxiliary power consumption at carbon capture unit.

Desulphurisation and Inclusion Behaviour of Stainless Steel Refining by Using CaO–Al2O3 Based Slag at Low Sulphur Levels

The deep desulphurisation behaviour and steel cleanliness of stainless steel refining in the low sulphur content period (below 45 ppm [%S]) by using the current lime-fluorspar based slag and an optimized lime-alumina slag have been studied and compared. The desulphurisation effect was discussed based on the calculated sulphide capacity of slags and the equilibrated sulphur distribution ratio between the slag and steel. The sulphur evolution during the treatment was predicted with a previously developed kinetic model. The influence of slag chemistry on the compositional evolution of the steel and inclusions was discussed through thermodynamic considerations with respect to deoxidation and desulphurisation reactions. The sulphur content in the inclusions was predicted using the dissolved sulphur in the steel and their oxide chemistry. An equivalent steel cleanliness and desulphurisation effect was obtained with lime-alumina based slag as with lime-fluorspar based slag both in laboratory and industrial tests for low sulphur content stainless refining.

Effects of Steel – Applied for Large-Dimension Castings for the Power Engineering – Refining in The Ladle-Furnace

Abstract The changes of a sulphur content during refining in melting low-alloy and high-alloy steels (G17CrMoV5-10; GX12CrMoNiVNbN9-1) applied for large-dimension castings for the power engineering are presented in the hereby paper. The investigated steel was melted in the oxygen-recovery melting technology with an application of maximum 70% of the process scrap. In addition, after steel melting in the electric arc furnace (EAF), the secondary metallurgy was performed in the ladle furnace (LF). It was shown that the application of the secondary metallurgy by a synthetic slag in the ladle furnace and argon bubbling of a metal bath leads to obtaining in the final analysis: 0.0043-0.0046% of sulphur (a decrease of S content during refining in LF reached 40%). Current measurements of FeO in the slag and maintaining its content below 0.8%, support obtaining such low sulphur content in steel. So low level of the slag oxidizing is one of the necessary conditions for a deep desulphurisation of the metal bath. Without the secondary metallurgy the sulphur content in low-alloy cast steel was 0.007%, while 0.01% in high-alloy cast steel. Controlling of the gas (oxygen, nitrogen) content during steel melting and correcting the amount of additions (e.g. deoxidants), allowed to obtain the low oxygen content (below 45 ppm for two investigated steel grades) and nitrogen content (88 ppm for low-alloy steel and 330 ppm for high-alloy steel), which warrants a good combination of strength and plastic properties.