Desulfurization Yield Research Articles

Oxidative desulfurization of model and real fuel samples with natural zeolite-based catalysts: experimental design and optimization by Box–Behnken method

Abstract In this study, oxidative desulfurization was performed on simulated oil fraction consist of 1000 ppm dibenzothiophene. Cobalt supported on natural zeolite of Kaolin has been used as heterogeneous catalysts. 10% Co/metaKaolin with hydrogen peroxide as oxidant and acetonitrile as extraction solvent have shown excellent performance on desulfurization. Response surface methodology in experimental design and its subset Box–Benken was used to evaluate the performance of the selected catalyst in different operating conditions such as temperature, oxidant to sulfur molar ratio, time and catalyst amount. Also, optimum conditions was obtained are equal to 60 °C, O/S molar ratio (10.8 mol/mol), time (46 min) and catalyst amount 0.04 g with 97.1% sulfur removal. Oxidative desulfurization of model oil containing 1000 ppm of each sulfur component benzothiophene and thiophene was also tested at the optimum conditions, Oxidative desulfurization yield was ordered as DBT > BT > Th. In addition, after four steps consecutive recycle under optimum conditions oxidative desulfurization capacity of 10% Co/metaKaolin catalyst decreased from 97% to 92%, which is still high desulfurization capability. Finally, the performance of 10% Co/metaKaolin catalyst in oxidative desulfurization was evaluated for real oil fractions, gasoline and gasoil that was provided from regional oil refinery with sulfur content of 286 ppm and 7900 ppm, respectively. At the optimum conditions of operating variables desulfurization yield was 58% and 79% of total sulfur removal for gasoline and gasoil respectively with no significant changes in fuels properties.

Study on the performance of petroleum coke after electrolytic desulfurization in NaBr-CH3COOH system

ABSTRACT In this paper, CH3COOH is used to adjust the electrolyte, control different acid concentrations, and use the ·OOH, HBrO, BrO3 − produced by the electrolyte on the anode to oxidatively desulfurize the petroleum coke particles suspended in the electrolyte. The desulfurized petroleum coke was analyzed by NB/SH/T 0527–2019 indicators and SEM, TGA, XRD, FTIR, and XPS to explore the degree and regularity of desulfurization conditions on the quality of petroleum coke, and explore the mechanism of the desulfurization process. The experimental results show that the NaBr-CH3COOH system has different desulfurization effects under different acid concentration conditions of pH = 2 ~ 6, and the impact on the quality of petroleum coke is also significantly different. A large acid concentration has a high desulfurization yield of petroleum coke. The desulfurization effect is best at pH = 2, and the desulfurization yield can reach 88.92%, but it has a certain impact on the quality indicators of the petroleum coke industry. The heating value of petroleum coke is slightly reduced, and the volatile content the ash yield content has increased compared with the original coke. The change is mainly due to the scission of the branch, the reduction of carbon atoms due to the oxidation reaction, and other side reactions that occur during the electrolytic oxidation reaction, which makes the oxygen content increase and the combustion performance becomes better. XPS analysis results show that the macromolecular structure of petroleum coke is hardly destroyed. According to the changes of oxygen-containing functional groups and sulfur-containing functional groups on the surface of petroleum coke, the mechanism of petroleum coke desulfurization was preliminarily explored.

Elaboración de escorias sintéticas con residuos de mármol y óxido de aluminio utilizados en el proceso de desulfuración de acero

El objetivo de este trabajo es investigar el proceso de desulfuración del acero utilizando escorias sintéticas que contienen residuos de mármol y óxido de aluminio. Las pruebas se realizaron usando un acero SAE 1020 que contenía 80 ppm de azufre. La temperatura fue 1600 °C bajo un flujo de argón de 1NL/minuto. Cada prueba de desulfuración duró 30 min. Se retiraron muestras de acero del baño cada 5 min. Posteriormente, cada muestra se caracterizó en un espectrómetro infrarrojo LECO CS240 para determinar el contenido de azufre. Los resultados indicaron un rendimiento de desulfuración de 78,7% y 70% en peso para escorias que contienen óxido de aluminio y residuos de mármol, respectivamente. Con estos resultados fue posible concluir que la fracción de la fase líquida influye en el rendimiento de desulfuración. El rendimiento máximo de desulfuración se alcanzó con 83,2% y 82,0% en peso de la fase líquida para escorias que contenían óxido de aluminio y residuos de mármol, respectivamente. Además, en las escorias que contienen cal, el rendimiento máximo de desulfuración se alcanzó con 85,0% en peso de la fase líquida. Las pruebas también demostraron que en los procesos de desulfuración es necesario contener una fase sólida de CaO en la composición de escoria sintética para alcanzar el rendimiento máximo de desulfuración. Por lo tanto, el uso de óxido de aluminio en lugar de fluorita es una alternativa interesante para la desulfuración del acero, así como el reemplazo de la cal por los residuos de mármol.

Catalytic Oxidative-Extractive Deep Desulfurization of Diesel Fuel by N-methyl-2-pyrrolidone-Based Protic Acidic Ionic Liquids (PAILs)

Inexpensive and low-viscosity Protic Acidic Ionic Liquids (PAILs) of N-metheyl-2-pyrrolidone formate, acetate, and propionate abbreviated as [Hnmp][HCOO], [Hnmp][CH3COO] and [Hnmp][CH3CH2COO] respectively, were prepared and characterized by FT-IR and H-NMR. Deep oxidative and extractive desulfurization of a simulated oil and a real diesel containing 1000 ppmw sulfur were studied under the catalysis of the proposed PAILs without additional carboxylic acid and extraction solvent in the system. The desulfurization efficiency in this study was influenced by both amounts of PAILs and concentration of the produced peroxy acids from H2O2. Comparing to [Hnmp][HCOO], [Hnmp][CH3COO] and [Hnmp][CH3CH2COO] had a relatively higher extraction ability however the weaker acidic properties of them resulted in a lower activation of H2O2 to produce peroxy acids and finally led to lower oxidative desulfurization (ODS) efficiency in the same condition. Additionally, the neutralization reaction may not be efficiently gone to the right hand by weaker acids. The effects of the main process variables were studied in detail. The highest desulfurization yield of 97% for BT and 99% for DBT and 4,6-DMDBT, were achieved using [Hnmp][HCOO] in the ODS system at a temperature of 40 °C, H2O2/sulfur molar ratio of 10, VPAIL/Voil of 0.2, and a reaction time of 90 min. The immiscibility of the proposed PAILs in this study with the oil phase caused the easy separation of them after desulfurization. The possible ODS pathway was also proposed.

Towards a room temperature oxidative desulfurization of refractory compounds over 1-octyl-3-methylimidazolium tetrachloroferrates/silica gel: The beneficial effects of immobilization

A successful immobilization of 1-octyl-3-methylimidazolium tetrachloroferrates ([Omim][FeCl4]) thin films on a silica gel while remaining its mesoporousity, was accomplished in this work. The developed catalyst was highly active and cost-effective for deep oxidative desulfurization of refractory thiophenic compounds at room temperature utilizing H2O2 oxidation agent. The reaction products were well separated from fuel by the catalyst itself under a beneficial solvent-free condition. The catalyst was characterized applying different analyses of FT-IR, TGA, XRD, SEM, EDS, AFM, N2 adsorption desorption, BET, and BJH. A sufficiently large pore diameter (∼6.2 nm) and high surface area (∼490 m2/g) of the silica gel for supporting the Lewis acidic [Omim][FeCl4] having a proper anion and cation structure, synergistically enabled a high efficient and selective catalyst for removal of refractory thiophenes. The influences of reaction temperature and time, loading amount of ionic liquid (IL), catalyst and oxidant amount as crucial reaction factors were evaluated in order to have a maximum desulfurization yield. Impressively, only a very low IL loading of 5 wt.% on the silica gel support achieved complete elimination of dibenzothiophene at the optimal mild conditions and room temperature. In the presence of a non-sulfur aromatic hydrocarbon beside different thiophenic models, the desulfurization selectivity of [Omim][FeCl4] increased from 0.92 to 0.95 via immobilization on the silica gel support. A significant decline in the IL consumption was verified as another beneficial effect of this immobilization. The catalyst could be easily separated having a capability for 100 % removal of dibenzothiophene after recycling four times. Meanwhile, GC–MS analysis was employed for further founding of the desulfurization pathway.

Alternative Methods for the Removal of Sulfur Compounds from Petroleum Fractions

Alternative methods are examined for the removal of sulfur compounds from hydrocarbon fractions in order to meet the strict specifications for sulfur content and reduce the sulfur content in petroleum raw material. The advantages of such alternative sulfur removal methods include low temperature and pressure, no need for introducing hydrogen, and feasibility for small refineries. Two types of methods were examined. One type involves the use of adsorbents, selective solvents, oxidizing agents, and biodesulfilrization. The other group involves wave technologies based on electric pulse effects, cavitation, hydrowave, magnetic, and electromagnetic effects as well as combined wave technologies. The most effective methods for desulfurization yield fuel components corresponding to ecology class 5.

Deep and fast oxidative desulfurization of fuels using graphene oxide-based phosphotungstic acid catalysts

Extractive-catalytic oxidative desulfurization (ECOD) technology is a potential industrial application for attaining low-sulfur fuel oils. In this research, novel graphene oxide (GO)-based heterogeneous catalysts were synthesized by immobilization of different amounts of phosphotungstic acid H3PW12O40 (HPW) on GO. The obtained HPW-GO catalysts were characterized by FT-IR, SEM, EDX, TEM, AFM, and RAMAN analyses. The ECOD was applied for removal of dibenzothiophene (DBT) from a model fuel with H2O2 as the oxidant, acetonitrile as the extracting solvent, and HPW-GOs as the catalysts. Among the catalysts with different HPW contents (5, 10, 20, 25, 30, 40 wt%), the catalyst with 40 wt% HPW had the best performance. The optimum reaction time, temperature, H2O2/sulfur molar ratio (O/S) as well as the kinetic parameters (kinetic constants and apparent activation energy) were evaluated. 100 percent desulfurization yield was achieved in a short time (t = 30 min) using the 40 wt% catalyst under moderate conditions (catalyst loading = 5 g/l, O/S = 6, T = 333 K). Aiding by synergism, the heterogeneous HPW-GO catalyst showed a higher desulfurization yield compared to that by the homogeneous HPW. The reactivity of 4,6-dimethyldibenzothiophene (4,6-DMDBT) in the ECOD process was found to be equal to that of DBT but much higher than the reactivity of benzothiophene (BT) within 60 min. The catalyst could be recycled for eight times without significant decrease in activity. A reasonable reaction pathway was proposed based on the GC–MS analysis. Almost all of the sulfur content of a real fuel could be completely oxidized and removed by the ECOD. Comparing to the results reported in literature, the features of proposed one-step fast ECOD process, which requires very low catalyst at moderate conditions for complete desulfurization without any phase transfer agent, makes it distinctive for practical applications.

Facile Combustion Synthesis of ZnFe2O4 for Photocatalytic Oxidative Desulfurization of Thiophene in Model Oil

Nano-ZnFe2O4 photocatalysts are one-step synthesized via solution combustion route, which are characterized by XRD, TEM, and UV-vis DRS. The photocatalytic activity of these samples are evaluated by the removal of thiophene in model oil under visible light irradiation. The influences of fuel amount on the particle size and photocatalytic performance of the as-synthesized catalysts are investigated. The results show that the ZnFe2O4 with the particle size of 21.9 nm exhibits the highest photocatalytic ability, which is acquired using triethylamine hydrochloride as fuel in the fuel-rich combustion condition. The desulfurization yield of model oil can reach 92.5% in 5 h photo-irradiation and the sulfur content can be decreased from 200 ppm to 15 ppm.

Development of Synthetic Slag with Marble Waste and Calcium Aluminate Agents for Cast Iron Desulfurization

The aim of this work was to study the use of slags to desulfurize cast iron. It was proposed to use alumina instead of fluorspar. In addition, marble waste was used instead of lime. Simulations applying Thermo-Calc® software were carried out in order to obtain the theoretical phases using thermodynamic data. Then, a comparison between theoretical data and experimental tests were performed. Cast iron was melted in induction furnace at 1550oC. Slags composed mainly for CaO and Al2O3 were used to desulfurize cast iron. The results showed that the desulphurization reaction was favored when the liquid phase was increased. Furthermore, it was found that cast iron desulfurization occurs by top slag mechanism. Furthermore, the desulfurization tests showed a decrease up to 90.10% in the sulfur content to the mixture containing conventional lime and 87.25% to the mixture RMF15. The slags obtained from marble waste contained MgO, which it interfered negatively in the desulfurization yield. In addition, increasing the CaO particle diameter improved the desulfurization process. The desulphurization process more favored to particle size of 500-1000 µm.

Desulfurization of liquid fuels by air assisted peracid oxidation system in the presence of Fe-ZSM-5 catalyst

Catalytic oxidative desulfurization of the model oil or synthetic sulfur oil (SSO) and the different real/industrial industrial oil fractions was investigated using air assisted hydrogen peroxide and formic acid oxidation in the presence of Fe-ZSM-5 as catalyst. The reactivity of the different model sulfur compounds increased in the order of thiophene< dibenzothiophene (BT)<4-methyl dibenzothiophene (4-MDBT). The desulfurization yield in case of the model oil was increased in the presence of Fe-ZSM-5 and the sulfur content of the model oil was reduced from 1275 to less than 50 ppm in 60 min at 60 °C temperature. The catalyst also performed efficiently in ODS of real industrial oil fractions, i.e., untreated naphtha (UN), light gas oil (LGO), cooker derived combined heavy gas oil (HGO) and Athabasca oil sands derived bitumen (At. Bit.), and sulfur removal of 80, 78, 62 and 60% was attained, respectively. Kinetic investigation revealed that the ODS catalyzed by Fe-ZSM-5 followed the first-order kinetics.

Desulfurization reaction model and experimental analysis of high sulfur coal under hydrogen atmosphere

The reaction between hydrogen and high-sulfur coal at high temperature was investigated. Crashed and sieved high-sulfur coal sample was placed in a 23mm I.D. differential reactor. The release of hydrogen sulfide at run temperature and under different hydrogen atmospheres was recorded by a hydrogen sulfide detector. Desulfurization yield was obtained through the elemental analysis of residual char. The grain reaction and random pore models were modified to facilitate the description of reaction kinetics characteristics. Hydrogen was observed to promote the desulfurization rate considerably; i.e., more than 65% of sulfur in coal could be removed. The releasing curves of H2S in the hydropyrolysis process exhibited two peaks. The desulfurization process in the hydropyrolysis of high-sulfur coal could be regarded as two stages based on the evolution profiles of H2S. The first peak at 250–450°C was derived from the desulfurization of aliphatic sulfide. The second peak at 450–650°C was produced from the sulfur in pyrite and aromatic thiophenic structure. The desulfurization of high sulfur could be described more effectively with the grain reaction model than with the random pore model. The random pore model was only adopted in the initial stage of sulfur removal of high-sulfur coal under hydrogen atmosphere. The grain reaction model was adequate for the entire stage.

Deep Desulfurization of Light Oil Using the Imitating Silver Salt ILs Method

Sulfides in oils are harmful in many ways, in particular, deterioration of the environment resulting from sulfur dioxide. A novel desulfurization process for light oil has been investigated. A mixture consisting of benzothiophene (BT), dibenzothiophene (DBT), and oil fractions (235°C–270°C) refined by acid–alkali treatment was employed for alkylation desulfurization tests in a nitrogen atmosphere. The results showed that at a reaction temperature of 30°C, ratio of bromoethane (CH3CH2Br) to sulfur of 30:1 (mol/mol), ratio of silver tetrafluoroborate (AgBF4) to sulfur of 6:1 (mol/mol), and reaction time of 16 hr, the desulfurization yield could reach 76.3%.

Study on a new desulfurization method based on imitating ionic liquids for light diesel oil

A simulated light oil consisting of model sulfur compounds of benzothiophene (BT), dibenzothiophene (DBT) and 4,6-dimethyldibenzothiophene (4,6-DMDBT) and straight-run light diesel oil fractions as solvent was employed for desulfurization tests imitating silver-salt method for ionic liquids (ILs). Under the conditions of a nitrogen atmosphere, reaction temperature of 303 K, reaction time of 24 h, the effects of different alkylating agents and amount of agent on the sulfur removal were investigated in more details. The results showed that when ratio of bromoethane (CH3CH2Br) to sulfur is 80: 1 (mol/mol) and ratio of potassium tetrafluoroborate (KBF4) to sulfur 30: 1 (mol/mol), the desulfurization yield were 72.6%.

One-Step Oxidation–Desulfurization of FCC Gasoline Catalyzed by Tungstophosphoric Acid

The sulfur compounds in fluid catalytic cracked (FCC) gasoline were removed with a one-step oxidation–extraction method. Tungstophosphoric acid (HPWA), tert-butyl hydroperoxide (TBHP), and ethanol were used as catalyst, oxidant, and solvent, respectively. TBHP has a higher desulfurization degree and oil yield than hydrogen peroxide, and HPWA exhibited higher desulfurization degree and oil yield than the other kinds of acids. The one-step process has a higher desulfurization degree than the two-step process. The optimal operating parameters were obtained as follows: the catalyst amount was 5 wt%, the mole ratio of oxygen in the oxidant to the sulfur in the gasoline (O/S) was 10, the reaction temperature was 60°C, and the reaction time was 2 hr. Under these conditions, the desulfurization degree and yield of oil were both in the range of 85–90%.

The Photooxidative Desulfurization of Thiophene with Tetrabutylammonium Bromide as a Phase Transfer Catalyst

Photochemical oxidative desulfurization of thiophene with tetrabutylammonium bromide (TBAB) as phase transfer catalyst was studied. The effects of the TBAB addition and pH on the desulfurization yield of thiophene were investigated. The cycle model of desulfurization of thiophene with TBAB was proposed. The results show that the desulfurization yield of thiophene in n-octane is 80.6% for a 2-hr photoirradiation under the conditions of air flow at 150 mL/min, V (n-octane):V (water) = 1:1, pH = 12, and 0.1 g of TBAB as catalyst. The photooxidation kinetics of thiophene is first-order with rate constant of 0.5702 hr−1 and half-life of 1.22 hr.

Catalytic hydro desulphurization study of heavy petroleum residue through in situ generated hydrogen

Abstract Hydrodesulphurization of heavy residue was carried out using various catalysts in the presence of co-reactants as the internal sources of hydrogen. Reactions were carried out in a micro autoclave at 320 °C and 10 kg f/cm2 pressure inert atmosphere of N2 for 3 h reaction time. Tetralin, propane, methanol, ethylene glycol and formic acid were separately used as co-reactants as hydrogen donors. Among the solvents studied, methanol gave the highest hydrodesulphurization yield (52%). The reaction was then carried out in the presence of various catalysts to view the influence of each individual catalyst on the desulphurization yield under the same conditions of pressure and temperature. The catalysts used were Mo-Montmorillonite, Co-Montmorillonite, nickel oxide (NiO), cadmium oxide (CdO), Zn-ZSM5, kaolin and montmorillonite clays. The results show that all the catalysts exhibited desulphurization activity. In case of Mo-Montmorillonite and Co-Montmorillonite charges, the desulfurization yields of 63% and 46% were obtained, respectively. NiO, CdO, Zn-ZSM5, kaolin and montmorillonite clays gave desulphurization yields of 54%, 50%, 56%, 20% and 36%, respectively. The desulphurization activities of Mo-Montmorillonite and Co-Montmorillonite were compared with other catalysts used. The results show that Mo-Montmorillonite gave the highest hydrodesulphurization yield. FTIR studies also confirmed the hydrodesulphurization efficiency of the Mo-Montmorillonite.

Sulfur-bound biomarkers of a Monterey shale and a Greenland lake sediment

AbstractSeeking to reconstruct the biogeochemical processes that produced organic sulfur compounds in two unique depositional environments, we used the nickel boride desulfurization reaction to release hydrocarbons from sulfur-bound macromolecules not otherwise amenable to chromatographic analysis. We desulfurized two geochemical extracts: one sample is a Monterey shale of late Miocene age, and the other sample is a surface sediment from the Greenland lake Brayasø. Both samples contained organic sulfur compounds, but the Monterey shale was biologically and thermally modified after deposition. A comparison of the free and sulfur-bound hydrocarbons from each sample revealed a precursor-product relationship between tocopherol and pristane, for Monterey. Greenland’s composition may indicate that photochemical sulfurization occurs in the Brayasø oxic zone. We found that sulfurization may proceed at different rates for different compound families; for example, we did not see any sulfurized alkenones in Brayasø, but we found an abundance of sulfurized isoprenoids. Greenland’s relatively high overall desulfurization yield suggests that sulfurization in Brayasø occurs in under 40 years. Our Greenland findings suggest that photochemical sulfurization may be more widespread than previously thought, and that sulfurization might not interfere with alkenone paleotemperature reconstructions.

Sulfur-bound biomarkers of a Monterey shale and a Greenland lake sediment

Seeking to reconstruct the biogeochemical processes that produced organic sulfur compounds in two unique depositional environments, we used the nickel boride desulfurization reaction to release hydrocarbons from sulfur-bound macromolecules not otherwise amenable to chromatographic analysis. We desulfurized two geochemical extracts: one sample is a Monterey shale of late Miocene age, and the other sample is a surface sediment from the Greenland lake Brayasø. Both samples contained organic sulfur compounds, but the Monterey shale was biologically and thermally modified after deposition. A comparison of the free and sulfur-bound hydrocarbons from each sample revealed a precursor-product relationship between tocopherol and pristane, for Monterey. Greenland’s composition may indicate that photochemical sulfurization occurs in the Brayasø oxic zone. We found that sulfurization may proceed at different rates for different compound families; for example, we did not see any sulfurized alkenones in Brayasø, but we found an abundance of sulfurized isoprenoids. Greenland’s relatively high overall desulfurization yield suggests that sulfurization in Brayasø occurs in under 40 years. Our Greenland findings suggest that photochemical sulfurization may be more widespread than previously thought, and that sulfurization might not interfere with alkenone paleotemperature reconstructions.

Desulfurization of dibenzothiophene by chemical oxidation and solvent extraction with Me3NCH2C6H5Cl·2ZnCl2 ionic liquid

Desulfurization of dibenzothiophene (DBT) by a combination of both chemical oxidation and solvent extraction was investigated. Me3NCH2C6H5Cl·2ZnCl2 ionic liquid was prepared from cheap starting materials and used as extractant for oxidative desulfurization of DBT in n-octane. DBT in oil phase was extracted into ionic liquid phase and then oxidized to its corresponding sulfone by H2O2 and equal volume of acetic acid. The desulfurization yield of DBT in n-octane was 94% at 30 min under the conditions of H2O2/DBT molar ratio at 6 and V (ionic liquid) : V (n-octane) = 1 : 5, which was remarkably higher than that by mere extraction with ionic liquid (28.9%). The Me3NCH2C6H5Cl·2ZnCl2 ionic liquid could be recycled six times without a significant decrease in activity. Kinetics of oxidative desulfurization of DBT by H2O2 and acetic acid was first-order with an apparent rate constant of 0.0842 min−1 and half-time of 8.23 min.

Study on photosensitized oxidative desulfurization of thiophene by riboflavin

Photosensitized oxidative desulfurization of thiophene in n-octane/water extraction system with riboflavin as photosensitizer and O 2 in air as oxidant was studied. A 500 W high pressure Hg lamp was used as the light source for irradiation and air was introduced by a gas pump for supplying O 2. The desulfurization yield of thiophene was 85.4% for a 3 h photoirradiation under the conditions with an air flow of 150 mL/min, water/oil ratio of 1:1 and riboflavin concentration of 30 μmol/L. The mechanism of photosensitized oxidation of thiophene is 1O 2 exited from 3O 2 by the addition of riboflavin. Under the above conditions, the photooxidation kinetics of thiophene with O 2/riboflavin is first-order with a rate constant of 0.3277 h −1 and half-time of 1.37 h.