Maximum Desulfurization Efficiency Research Articles

Study on extraction desulfurization of road-paving asphalt by deep eutectic solvents

During the hot mixing process of road-paving asphalt, odorous substances are released, primarily consisting of sulfur-containing compounds that are regarded as atmospheric pollutants, negatively impacting both human quality of life and the eco-environment. In the paper, a kind of simulated asphalt solution was designed with two sulfur-containing compounds, dibenzothiophene (DBT) and benzothiophene (BT), as well as n-eicosane dissolved in cyclohexane. DBT and BT were extracted with deep eutectic solvent (DES) of tetrabutylammonium bromide and polyethylene glycol (TBAB/PEG). The effects of different molecular weight of PEG as donor on desulfurization efficiency were investigated. The effects of DES donor/receptor ratio, extraction temperature and time, solvent oil ratio, mixing speed, recycling performance of DES on desulfurization efficiency were also studied and optimized. The results indicated that the maximum desulfurization efficiency of BT reached 89.40 % at room temperature with a ratio of agent to oil of 2:1, reaction time of 30 min, and mixing speed of 600 rpm. Similarly, the desulfurization efficiency of DBT achieved 95.54 % when the ratio of agent to oil was 3.5:1, with reaction time of 30 min and mixing speed of 600 rpm. After being recycled eight times, the extraction efficiencies of DBT and BT remained at 85.3 % and 65.2 %, respectively. Under optimized conditions, the extraction efficiency of petroleum asphalt exceeded 23 %. Fourier Transform Infrared (FTIR) analysis indicated that the sulfur-containing compounds found in the saturates and aromatics of road-paving asphalt were extracted by DESs, which are generally more volatile than those found in asphaltenes during hot-mixing. Additionally, minimal changes were observed in the structural composition of the four fractions of desulfurized asphalt.

Evaluation of the use of a biofilter made with biodegradable material for biogas desulfurization

Biogas is a promising energy source with the potential to contribute to greenhouse gas emission reduction. In addition, it can be produced from waste biomass and has various applications. However, contaminants have to be removed before use. Hydrogen sulfide (H2S) is perhaps the most critical because of its toxicity and corrosive properties. In this study, we evaluated a prototype of a biofilter for biogas desulfurization made of coconut chips as packing media and digester effluent as a nutrient source. The composition of inlet and outlet biogas was evaluated through gas chromatography in five tests. The maximum desulfurization efficiency observed was 75.80%, but with a considerable variation (mean of 43.08%). Microscopy analysis of the packing media before and after the experiments demonstrated the accumulation of substances and the presence of new elements. Nevertheless, more studies are necessary with longer duration and frequency for a better evaluation of the system stability and saturation.

Extractive desulfurization of stabilized natural gas condensate in a micro-tube contactor

In the present study, extractive desulfurization of stabilized natural gas condensate with initial sulfur content of 1800ppmw was studied using a microchannel made of glass with inner diameter of 800μm. Different solvents have been examined and dimethyl formamide (DMF) was selected considering different solvent selection criteria. It was found that the fuel to solvent flowrate ratio affects the hydrodynamics and the desulfurization efficiency significantly. The observed flow pattern within the examined flowrate was slug flow regime. The maximum desulfurization efficiency (i.e., 66.31%) was achieved at flowrate of 1 mL/min and solvent-to-fuel flow ratio of 1:1, which correspond to the highest value of the specific surface area of slugs. The best desulfurization result is achieved with five cycles of extraction with fresh solvent. In this case, the sulfur content of the treated natural gas condensate decreases below 200 ppmw.

Desulfurization of heavy naphtha by oxidation-adsorption process using iron-promoted activated carbon and Cu+2-promoted zeolite 13X

The removal efficiency of sulfur compounds from heavy naphtha with a sulfur concentration of 600 ppm was evaluated using a combination of oxidation and adsorption processes. Hydrogen peroxide (H2O2) was used as an oxygenated agent. At the same time, iron-promoted activated carbon (IPAC) and Cu+2 promoted zeolite 13X (CPZ13X) were used in dual functions (catalysts for the oxidation reaction and adsorbents for sulfur compounds). This study explored the effect of several factors on desulfurization efficiency. These factors are the volume ratio of H2O2 to heavy naphtha (0.01–0.05), agitation speed (Uspeed = 100–500 ± 2 rpm), pH of heavy naphtha (1–5), the weight of solid materials (0.5–2.0 g), process temperature (290–360 ± 1 K), and contact time (30–180 min). The outcomes show that IPAC is superior for the desulfurization process due to its better performance in oxidation and adsorption of sulfur compounds due to its physicochemical properties, such as its high surface area. The maximum desulfurization efficiency of IPAC and CPZ13X reached by this work were 97 and 93%, respectively. The adsorption capacity of IPAC and CPZ13X reached at the optimum conditions were 21.83 and 20.93 mg/g, respectively.

Non-catalytic desulfurization of model diesel using synthesized biodegradable ionic liquid

ABSTRACT The conventional processes generally used by petroleum refineries for eradication of sulfur compounds from diesel, namely, diesel hydrotreating is associated with the problem of high cost in terms of energy consumption, catalyst regeneration, etc. The present work has spotted a diesel desulfurization process at ambient temperature (25°C) without using any catalyst. Solvent extraction was applied to eliminate heterocyclic sulfur compounds from model diesel using a novel ionic liquid, which was synthesized from basic raw materials and characterized by common techniques like Fourier Transform Infrared (FTIR) spectroscopy and Nuclear Magnetic Resonance (NMR) spectroscopy. A preliminary biodegradation study of the synthesized ionic liquid revealed 49.98% biodegradability after 35 days. The compounds present in the synthesized ionic liquid are 1,3-diethyl-1H-1,2,3-triazol-3-ium acetate ([Etim][OAc]), 1,3-diethyl-1H-imidazol-3-ium ([Eiim][OAc]), and 1-ethyl-3-methyl-3H-pyrazol-1-ium acetate ([EMpim][OAc]). The maximum desulfurization efficiency was 99.09% for dibenzothiophene (DBT) and 97.94% for thiophene using a solvent to feed ratio of 1:1 and applying a stirring time of 60 minutes. The quality of the model diesel has been checked with respect to flash point, aniline point, diesel index, and cetane index both pre- and post-desulfurization.

Triphenyl methyl phosphonium tosylate as an efficient phase transfer catalyst for ultrasound-assisted oxidative desulfurization of liquid fuel.

The novel phosphonium-based ionic liquid (IL), triphenyl methyl phosphonium tosylate ([TPMP][Tos]), has been synthesized and applied as a phase transfer catalyst (PTC) in the ultrasound-assisted oxidative desulfurization (UAODS). Oxidation of model fuel (MF) containing dibenzothiophene (DBT) was carried out using an equimolar mixture of H2O2-CH3COOH as an oxidant at 40-70 °C in the presence of IL. The sulfur compound is converted into polar sulfone, and the maximum desulfurization efficiency was examined. The effect of process parameters such as reaction temperature, reaction time, molar ratio of oxidant to sulfur (n(O/S)), and the mass ratio of ionic liquid to model fuel (m(IL/MF)) was studied, and the conditions for maximizing the DBT conversion rate were found. Maximum conversion (> 99%) was obtained at a temperature of 70 °C with m(IL/MF) of 0.8. The oxidation reactivity of various sulfur compounds was studied at different time intervals. To verify the effect of ionic liquid and ultrasound irradiation, extractive desulfurization (EDS), oxidative desulfurization (ODS), and UAODS in the presence of IL were carried out. The experimental results show that the UAODS process gives the highest desulfurization efficiency. A kinetic study was performed to estimate the rate constant and the order of oxidation reaction.

Study on desulfurization mechanism of adsorbents prepared by high ratio circulating fly ash and lime

Under the conditions of low temperature, low humidity and different mixture ratios, a variety of adsorbents were prepared by using a new preparation method and the Shendong high ratio circulating fly ash of the No Gap Desulfurization process was chosen as raw material. The desulfurization performance of adsorbents were characterized by the fixed-bed desulfurization reactor, and the effects of desulfurization process conditions (moisture content, mixing ratio, desulfurization temperature and initial concentration of SO2) on desulfurization removal efficiency have been experimentally investigated. The optimum desulfurization process conditions were found under the conditions of the hydration time was 3 h, moisture content was 15%, desulfurization temperature was 70 °C and initial concentration was 200 μL/L, and at this time the effective desulfurization time was 93.95 min, the maximum desulfurization efficiency was 99.12%. Through systematic analysis of the whole process of desulfurization reaction, it was concluded that the desulfurization efficiency was controlled by the desulfurization reaction rate and gas diffusion rate at the initial and later stages of the reaction respectively. Reducing the difference between the desulfurization reaction rate and gas diffusion rate can improve the desulfurization efficiency, which laying a theoretical foundation to improve the desulfurization efficiency of No Gap Desulfurization process.

Purifying of Waste Tire Pyrolysis Oil Using an S-ZrO2/SBA-15-H2O2 Catalytic Oxidation Method

Heavy fuel oils contain a high amount of sulfur. In this work, an extent amount of sulfur content waste tire pyrolysis oil (WTPO) was used as a fuel feedstock. A promising alternative oxidative desulfurization (ODS) method was applied in sulfur removal from WTPO using a S-ZrO2/SBA-15 solid acid catalyst, hydrogen peroxide (H2O2) as an oxidant and acetonitrile as an extracting solvent at varied conditions. The prepared catalyst was characterized by X-ray diffraction (XRD), Bruanuer-Emmet-Teller (BET) method and Fourier transform infrared spectroscopy (FTIR) analysis. The influence of reaction parameters such as reaction time (30-60 min), catalyst loading (0.5–1.5 wt.%), oxidant to oil mole ratio (5–15) at fixed reaction temperature 70 °C on desulfurization of WTPO were investigated. Taguchi method was selected to design the experiment for optimizing the reaction parameters by maximizing the sulfur removal efficiency. The maximum desulfurization efficiency 59.49% was obtained under optimum conditions reaction time (60 min), catalyst loading (1.0 wt.%) and oxidant to sulfur mole ratio (10:1). A catalytic S-ZrO2/SBA-15 -H2O2 oxidation system for oxidative desulfurization of waste tire pyrolysis oil using at mild reaction conditions was developed.

An integrated process consisting of Mg(OH)2 –impregnated ceramic foam filters as adsorbent and Mg(OH)2 as scrubbing solution for intensified desulfurization of flue gas

Integration of individual unit operations is an efficient strategy for the process intensification. In current study, an integrated absorption/adsorption process is introduced for the flue gas desulfurization. The flue gas was originated from the combustion of a high-sulfur gasoil/naphtha fuel. The adsorbent was prepared by impregnating Al2O3/SiO2 ceramic foam filters with Mg(OH)2 via chemical vapor deposition. The setup included three sections of combustion chamber, water scrubbing vessel and absorption/adsorption reactor. In the latter section, beside adsorption of sulfur compounds on the ceramic adsorbent, Mg(OH)2 solution was being continuously refluxed and sprayed over the flue gas to intensify the desulfurization process. Total sulfur removal decreased by around 3% when Mg(OH)2 solution was substituted with pure water in the final reactor. Impact of important operating variables including temperature, pressure and, initial pH was investigated. Temperature and pressure were altered in the ranges of 30 to 70 °C and 2 to 6 bar, respectively. Results indicated the positive effects of temperature and pressure increase on the sulfur removal. The optimum pH of the reflux solution was around 8. The maximum desulfurization efficiency of the intensified process was 98%. Generally, the results confirmed the effectiveness of the absorption/adsorption integration for the desulfurization process intensification.

Electrochemical hydrogenation and desulfurization of thiophenic compounds over MoS2 electrocatalyst using different membrane-electrode assembly

The desulfurization-hydrogenation of thiophene and benzothiophene in hexadecane as a model diesel fuel was studied through a divided cell with the incorporation of a membrane electrode assembly (MEA) under different current density at a constant charge. The reduction of the thiophenic compounds was investigated using a prepared MoS2 nano-electrocatalyst, Nafion (commercial proton exchange membrane), and synthesized sulfonated poly ether ether ketone (SPEEK). Field emission scanning electron microscopy (FESEM) and X-ray diffraction (XRD) were used to characterize the MoS2 electrocatalyst, which confirmed the formation of 23-25 nm ball-like nano-threads of MoS2. Also, the electrocatalyst and/or MEA was electrochemically analyzed by cyclic voltammetry (CV), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS). The gas chromatography-mass spectroscopy (GC-MS) analysis of the reactants and products revealed the direct desulfurization on the thiophene reduction process and the desulfurization along with the desulfurization pathway on the benzothiophene reduction experiment. A maximum desulfurization efficiency of 79.6% at 20 mA cm-2 and 51.5% at 30 mA cm-2 under the constant charge of 300 C was obtained for thiophene using the MoS2-Nafion and MoS2-SPEEK system, respectively. Moreover, a maximum hydrogenation and desulfurization efficiency of 28% and 59.1% occurred at 50 mA cm-2 and 70 mA cm-2, respectively, for the benzohiophene-Nafion system under the constant charge of 400 C. The distribution of the products affirmed that the desulfurization reaction contributed more at a higher current density against the hydrogenation process at a lower current density.

Oxyfuel technology: Oil shale desulfurization behavior during staged combustion

A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200°C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO2 and NO emissions. The SO2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O2/73% CO2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ=0.85 and Ca/S=2 at 1m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ=0.85 and Ca/S=3 at 1.5m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO2, SO2 and NOx emissions can be simultaneously controlled.

Oxyfuel technology: Oil shale desulphurisation behaviour during unstaged combustion

Abstract A high sulfur content in Jordanian oil shale is considered one of the biggest challenges preventing its full utilization. To resolve this issue, direct limestone injection during staged combustion has been investigated for the simultaneous control of NO and SO 2 emissions. Staged El-Lajjun oil shale combustion under oxyfuel conditions and conventional air-firing conditions was performed at 1200 °C in a 20-kW vertical reactor. Limestone was mixed with oil shale before combustion. Three different molar ratios of Ca/S, three different burner oxygen ratios (0.75, 0.85 and 0.95) and different positions of the burnout oxidant probe were tested in both firing conditions to determine the optimum conditions for the lowest SO 2 and NO emissions. The SO 2 emissions were significantly lowered by adding limestone during staged air-firing and OF27 (27% O 2 /73% CO 2 environment) combustion. The desulfurization efficiencies ranged from 32 to 61% and from 25 to 60% during the staged air-firing and staged OF27 combustion, respectively. The staging level, the Ca/S molar ratio and the position of the secondary oxidant are important parameters that affect the desulfurization efficiency. Higher desulfurization efficiencies were obtained during OF27 combustion compared with air-firing at burner oxygen ratios of 0.85 and 0.95. At a burner oxygen ratio of 0.75, the opposite trend was observed. The SO 2 emissions during staged combustion were significantly higher than those during unstaged combustion in air and during OF27 combustion. This was due to high competition among many reactions, which minimized the desulfurization efficiency. The maximum desulfurization efficiency during staged OF27 combustion was 60% with λ = 0.85 and Ca/S = 2 at 1 m from the burner. During air-firing combustion, the maximum desulfurization efficiency was 61% with λ = 0.85 and Ca/S = 3 at 1.5 m from the burner. Based on the current and previous studies, the authors recommend that oxyfuel technology be used for oil shale combustion so that CO 2 , SO 2 and NO x emissions can be simultaneously controlled.

Equilibrium and kinetics of Jet-A fuel desulfurization by selective adsorption at room temperatures

The performance of desulfurization of Jet-A fuel at room temperature and atmospheric pressure by using an innovative Nickel–Cerium (Ni–Ce)-based adsorbent is investigated in this work. The adsorbent preparation conditions, including the calcination temperature and length of time, and the compositions of support materials and catalysts were optimized to obtain the best efficiency of sulfur removal. The effects of the adsorbent–fuel mass ratio and the interaction time of adsorbent to fuel on the desulfurization performance were also investigated through batch-test experiment. The sulfur adsorption equilibrium and kinetics were examined. The results showed that the BET model can best represent the equilibrium isotherm, and a pseudo-second order model can best fit the kinetics data. For Jet-A fuel in a total sulfur concentration of 1037ppmw, the lowest achieved sulfur concentration at room temperature in the treated fuel was 22.13ppmw. The corresponding equilibrium adsorptive capacity at this maximum desulfurization efficiency was found to be 1.32mgS/g adsorbent. This is a significant achievement regarding the desulfurization efficiency, especially at room temperature and using commercial Jet-A fuel with no pretreatment.

Ionic Liquids: - The Novel Solvent for Removal of Dibenzothiophene from Liquid Fuel

Abstract Ionic Liquids (ILs), a new class of green solvents, have recently been undergoing intensive research on the removal of thiophenic sulfur species (e.g., dibenzothiophene) from liquid fuels because of the limitations of the tradition hydrodesulfurization process in removing these species. In this work, deep extractive desulfurization of liquid fuels by different ionic liquids are studied and employed as promising extractants for the model liquid fuel containing dibenzothiophene (DBT). 1-butyl-3-methylimidazolium chloride [Bmim]Cl was the most promising and novel ionic liquid and performed the best among the studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the liquid fuel in the single stage extraction process with the maximum desulfurization efficiency 77.15% under mild reaction conditions. It was also found that [Bmim] Cl can be reused without regeneration with considerable extraction efficiency.

Extractive Deep Desulfurization of Liquid Fuels Using Lewis-Based Ionic Liquids

A new class of green solvents, known as ionic liquids (ILs), has recently been the subject of intensive research on the extractive desulfurization of liquid fuels because of the limitation of traditional hydrodesulfurization method. In present work, eleven Lewis acid ionic liquids were synthesized and employed as promising extractants for deep desulfurization of the liquid fuel containing dibenzothiophene (DBT) to test the desulfurization efficiency. [Bmim]Cl/FeCl3was the most promising ionic liquid and performed the best among studied ionic liquids under the same operating conditions. It can remove dibenzothiophene from the model liquid fuel in the single-stage extraction process with the maximum desulfurization efficiency of 75.6%. It was also found that [Bmim]Cl/FeCl3may be reused without regeneration with considerable extraction efficiency of 47.3%. Huge saving on energy can be achieved if we make use of this ionic liquids behavior in process design, instead of regenerating ionic liquids after every time of extraction.

Modeling of the FCC Gasoline Desulfurization Process by Liquid Extraction with Sulfolane

Extractive desulfurization of fluid catalytic cracking (FCC) gasoline with sulfolane was studied in a batch apparatus. The influence of three inlet parameters (temperature, inlet sulfur content, and solvent ratio) on the process response, that is, desulfurization efficiency, was investigated with the use of a Box-Behnken experimental design by response surface methodology. A mathematical model that can be used for predicting sulfur content in raffinate after extractive batch processing with sulfolane was statistically developed and proven with analysis of variance. Statistical analysis showed that the largest influence on desulfurization efficiency was solvent ratio, the second most significant influence was inlet sulfur content, followed by temperature, and last the interaction between solvent ratio and inlet sulfur content. The obtained second-order polynomial model shows that maximum desulfurization efficiency of 65.34% can be achieved at temperature of 50°C and higher values of inlet sulfur content and solver ratio in the researched range of inlet parameter values.

Reactive Adsorption of Sulfur Compounds from FCC Gasoline on NiO/γ-Al<sub>2</sub>O<sub>3</sub>

NiO/γ-Al2O3 adsorbent was prepared by wet impregnated method. XRD, SEM-EDS, nitrogen adsorption techniques were used to characterize the adsorbents and GC-FPD was utilized to analyze the composition of gasoline before and after reaction. X-ray diffraction patterns indicate that noncrystal NiO particles are supported on the surface of γ-Al2O3. The results show that NiO/γ-Al2O3 adsorbent could be used to remove sulfur compounds and is effective on removing benzothiophene (BT). The maximum desulfurization efficiency appears when NiO content reaches 16%, and the total sulfur adsorption capacity is 1.84mg/g, however for 16%Ni/γ-Al2O3 the value reaches 3.495mg/g.

Oxidative Desulfurization of Tufanbeyli Coal by Hydrogen Peroxide Solution

It is becoming popular to use fossil fuels efficiently since the necessary energy is mostly supplied from fossil fuels. Altough there are high lignite reservoirs, high sulfur content limits the efficient use of them. In this article, we aimed to convert combustible sulfur in coal to non-combustible sulfate form in the ash by oxidizing it with a hydrogen peroxide solution. The parameters affecting the sulfur conversion were determined to be: hydrogen peroxide concentration, reaction time, mean particle size at constant room temperature and shaking rate. The maximum desulfurization efficiency reached was 74% of the original combustible sulfur with 15% (w/w) hydrogen peroxide solution, 12 hours of reaction time, and 0.25 mm mean particle size.

Oxidative Desulfurization of Aşkale Coal by Nitric Acid Solution

Efficient use of fossil fuels is of utmost importance in a world that depends on these for the greatest part of its energy needs. Although lignite is a widely used fossil fuel, its sulfur content limits its consumption. This study aims to capture combustible sulfur in the ash by oxidizing it with solution of nitric acid solution. Thus, the combustible sulfur in the coal was converted to sulfate form in the ash. Parameters affecting the conversion of sulfur were determined to be nitric acid concentration, reaction time and mean particle size at constant (near room) temperature and shaking rate. The maximum desulfurization efficiency reached was 38.7% of the original combustible sulfur with 0.3 M nitric acid solution, 16 h of reaction time and 0.1 mm mean particle size.