Oxidative Desulphurization Research Articles

Impact of ultrasound application on oxidative desulphurization of diesel fuel and on treatment of resulting wastewater

The ultrasound-assisted oxidative desulphurization (UAOD) process of diesel fuel has gained growing attention due to the strict regulation of sulphur content in the fuel. The goal of the present study was to investigate the impact of ultrasound (US) application for oxidative desulphurization (ODS) of hydrocarbon fuels and for the subsequent treatment of produced wastewater, since sonochemical processes are a new and interesting area of research with wide application in the field of environmental engineering. For that purpose, the model diesel fuel with initial sulphur concentration of 1220–3976 mg l−1 was used for ODS and UAOD tests, and hydrogen peroxide/acetic acid was applied as the oxidant/catalyst system, respectively. The comparison of the process performance revealed that US significantly reduced the oxidation reaction time. The conversions of dibenzothiophene during 30 min of ODS and UAOD tests were 36% and 87%, respectively. Moreover, subsequent extraction with acetonitrile resulted in the final sulphur removal of 96.5%. The obtained results clearly indicated that UAOD process is beneficial for effective sulphur removal from the model diesel fuel. Furthermore, subsequent experiments included the application of the sono-Fenton process for resulting wastewater treatment. Monitoring of dibenzothiophene sulphone concentration and total organic carbon during the sono-Fenton treatment of wastewater revealed the decrease of 70–75% and 53–66%, respectively. The hypothesis on the possibility of degradation of dibenzothiophene sulphone by •OH radicals was confirmed by observed generation of benzoic acid and aliphatic carboxylic acids during experiments. Accordingly, the wastewater was purified to a satisfactory degree, enabling the reuse of treated water.

Изучение влияния катионного и анионного модифицирования на активность CuZnAlO-катализатора в реакции окислительного обессеривания дибензотиофена в модельном дизельном топливе

Изучение влияния катионного и анионного модифицирования на активность CuZnAlO-катализатора в реакции окислительного обессеривания дибензотиофена в модельном дизельном топливе

Desulphurization and Usage of Medium-Metamorphized Black Coal. 1. Determination of the Optimal Conditions for Oxidative Desulphurization

The conditions providing proceeding of the reactions between pyrite sulphur of medium-metamorphized coal and air-steam mixture in the kinetic area have been found. Experimental-statistical mathematical model has been designed. The optimal factors of mediumcoalificated coal oxidative desulphurization have been determined on its basis. Under optimal conditions two samples of coking coal have been desulphurized. These samples will be used as components of the coal charge in the production of special types of coke.Знайдено умови, які забезпечують перебіг реакцій у кінетичній області між піритною сіркою середньометаморфізованого вугілля і паро-повітряною сумішшю. Розроблено експериментально-статистичну математичну модель та на її основі встановлено оптимальні значення чинників процесу оксидаційного знесірчення кам’яного вугілля середнього ступеня вуглефікації. У знайдених оптимальних умовах здійснено знесірчення двох зразків коксівного вугілля, які будуть використані як компоненти вугільної шихти у виробництві спеціальних видів коксу.

Chemical synthesis of the 5-taurinomethyl(-2-thio)uridine modified anticodon arm of the human mitochondrial tRNA(Leu(UUR)) and tRNA(Lys).

5-Taurinomethyluridine (τm(5)U) and 5-taurinomethyl-2-thiouridine (τm(5)s(2)U) are located at the wobble position of human mitochondrial (hmt) tRNA(Leu(UUR)) and tRNA(Lys), respectively. Both hypermodified units restrict decoding of the third codon letter to A and G. Pathogenic mutations in the genes encoding hmt-tRNA(Leu(UUR)) and hmt-tRNA(Lys) are responsible for the loss of the discussed modifications and, as a consequence, for the occurrence of severe mitochondrial dysfunctions (MELAS, MERRF). Synthetic oligoribonucleotides bearing modified nucleosides are a versatile tool for studying mechanisms of genetic message translation and accompanying pathologies at nucleoside resolution. In this paper, we present site-specific chemical incorporation of τm(5)U and τm(5)s(2)U into 17-mers related to the sequence of the anticodon arms hmt-tRNA(Leu(UUR)) and hmt-tRNA(Lys), respectively employing phosphoramidite chemistry on CPG support. Selected protecting groups for the sulfonic acid (4-(tert-butyldiphenylsilanyloxy)-2,2-dimethylbutyl) and the exoamine function (-C(O)CF3) are compatible with the blockage of the canonical monomeric units. The synthesis of τm(5)s(2)U-modified RNA fragment was performed under conditions eliminating the formation of side products of 2-thiocarbonyl group oxidation and/or oxidative desulphurization. The structure of the final oligomers was confirmed by mass spectroscopy and enzymatic cleavage data.

Lignite oxidative desulphurization

AbstractThe process of lignite desulphurization via its treatment by an oxidant (air or air–steam mixture) has been studied. The research objective was useful determination of steam application in oxidative lignite desulphurization. It has been proved that the water steam should be included in the oxidant composition to increase the hydrogen sulphide and combustible constituent content in the gases obtained during the processes under research. The impact of factors which affect the reactions between solid (in our case – lignite) and gaseous reagent (oxidant, i.e. air and or air–steam mixture) upon the research process has been investigated, if these reactions occur in the kinetic area. Such factors are linear rate of oxidant movement and coal grain size. The values of oxidant movement linear rate and coal grain size, which the reaction transfer from pyrite sulphur and organic content of lignite from diffusion into kinetic area occurs by, have been determined. Under these “transfer” conditions, the values of coefficients of oxidant mass transfer (β, m/s) as well as Sherwood criteria and boiling layer differences have been calculated.

Anatase titania-vanadium polyphosphomolybdate as an efficient and reusable nano catalyst for desulphurization of gas oil

(Bu4N)4H[PMo10V2O40]-TiO2 nanocomposite has been synthesized by a reaction of (Bu4N)4H[PMo10V2O40] with titanium tetraisopropoxide at 100 ?C via sol-gel method. The crushed nano layer of anatase phase is 20 nm in nature and fixing of (Bu4N)4H[PMo10V2O40] decreases its size. This nano Polyphosphomolybdate was shown be able to oxidative desulphurization of simulated gas oil with high S conversion (more than 98%). In the present work, efficient oxidative desulphurization of gas oil and simulated gas oil with formic acid/hydrogen peroxide system is reported. This system provides an efficient, convenient and practical method for scavenging sulfur compound.

Amphiphilic niobium oxyhydroxide as a hybrid catalyst for sulfur removal from fuel in a biphasic system

Here, we show that a new niobium oxyhydroxide, NbO2OH, can be synthesized and modified with a surfactant to be used as a heterogeneous catalyst for oxidative desulphurization. The material was treated with hydrogen peroxide to generate oxidizing groups (peroxo species) on the surface. Furthermore, this material was converted to a family of solid catalysts that can stabilize water/oil emulsions and catalyze reactions at the liquid/liquid interface by anchoring a surfactant to the catalyst. The material was then able to efficiently remove a sulfurous compound under mild conditions.

Study of enhanced low-quality coal oxidative desulphurization and deashing by using HNO3 and microwave pretreatment

In this paper, the effect of urea-hydrogen peroxide (UHP) solution on desulphurization and demineralization of coal with high sulphur and high ash by using HNO3 and microwave pretreatment was investigated. The oxidation process is strongly dependent on irradiation power and time for microwave pretreatment, UHP concentration, leaching time and temperature of the UHP solution. X-ray diffraction and Fourier transform infrared technique have been performed for the raw and treated coals. Compared with the UHP alone, successive treatments with HNO3 and microwave pretreatment resulted in the significant removal of total sulphur and mineral matter from the coal. The proposed experimental method has the meaning of practical guide to the desulphurization and deashing of coal by microwave.

Hierarchical TS-1 zeolite as an efficient catalyst for oxidative desulphurization of hydrocarbon fractions

The catalytic oxidative desulphurization (ODS) of S-containing aromatic compounds has been investigated over a hierarchical TS-1 zeolite prepared from silanized protozeolitic units, characterized by having, additionally to the zeolitic micropores, a secondary porosity within the supermicro/mesopore region. A standard TS-1 sample has been employed as reference catalyst. The influence of both the solvent (n-heptane and acetonitrile) and the oxidizing agent (hydrogen peroxide and tert-butylhydroperoxide, TBHP) was first studied using dibenzothiophene (DBT) as model substrate. In all cases, the catalytic activity exhibited by the hierarchical TS-1 was much higher than that obtained with the conventional TS-1 as a consequence of the improved accessibility caused by the presence of the secondary porosity. A very high desulphurization activity was obtained with the combination of heptane and TBHP, as solvent and oxidant, respectively, leading to an almost total DBT conversion. This fact has been attributed to the fully miscibility of the oxidant solution (TBHP in decane) in the organic reaction medium. Moreover, it is noteworthy that, in these conditions, the oxidation product (sulphone) is insoluble in the reaction medium, which facilitates its removal by filtration or centrifugation. Additionally, the oxidation of different aromatic organosulphur compounds [benzothiophene (BT), 2-methylbenzothiophene (2-MBT), 2,5-dimethylthiophene (2,5-DMT) and dibenzothiophene (DBT)] was investigated using the hierarchical TS-1 catalyst. The trend in the conversion values obtained was 2,5-DMT<BT<2-MBT<DBT. These results indicate that the oxidation conversion is determined by the nucleophilic character of the sulphur atom, and not by the molecular size of the S-containing compound, provided that the steric and diffusional limitations are overcome by the presence of the hierarchical TS-1 porosity.

Zinc Incorporated Hydroxyapatite Catalysts: Preparation and Characterization

Ca-hydroxyapatite was freshly prepared by precipitation method and used as a support material for preparing zinc catalysts. The catalysts were prepared by two different techniques: incipient impregnation and ionic exchange. The freshly prepared zinc catalysts were characterized via X-ray diffraction pattern, Fourier transform infra-red spectroscopy, differential scanning calorimeter, and thermo-gravimetric analysis. The replacement of Ca2+ by Zn2+ for the catalyst prepared by the ionic exchange method and the formation of Zn oxide species after impregnation were confirmed by X-ray diffraction patterns. The evaluation of the catalytic activity of Zn-hydroxyapatite catalysts were investigated toward oxidative desulphurization reaction of gas oil. The results show that the sulfur removal reached 88.5 wt% over ionic exchanged zinc catalyst under mild conditions.

Water Effect on Oxidative Desulphurization Process of Straight-Run Kerosene Fraction / Wpływ Wody Na Utleniający Proces Odsiarczania Frakcji Nafty

Abstract Sulphur dioxide obtained during fuels burning in combustion engines is one of the main pollutants. In diesel oils and gasolines the sulphur content must be 5-10 ppm and in jet fuels - 300-3000 ppm. However the production of hydrofined jet fuel is problematic. The reason is deterioration of fuel stability and antioxygenic properties. The oxidative desulphurization of straight-run kerosene was investigated. This method combines oxidation by atmospheric oxygen of sulphur compounds under increased temperature and pressure in the presence of water in the reaction medium, and removal of oxidized sulphur compounds from the oxidation-treated fuel via rectification. It was showed that water partially extracts from the hydrocarbon medium acidic compounds, formed in the beginning stage of oxidation, dissociation of which leads to the formation in water acidic medium. As a result, a pathway of the hydroperoxides decomposition partially changes from the formation of carbonic acids and oxyacids to the formation of alcohols, phenols and alkylphenols, which displayed an inhibitory effect in hydrocarbon oxidation. It was assumed that an inhibitory effect of water, in addition to the creation reverse micelles with peroxides and complexes with free radicals, caused by oxidation products created in the beginning stage of oxidation. The effect of water/kerosene ratio on the oxidative desulphurization of straight-run kerosene fraction has been examined. It was found that water improves process selectivity with insignificant influence on the degree of sulphur recovery. The optimum value of water/kerosene ratio for the fuel containing 0.15% mass of sulphuric compounds has been determined.

Deep desulphurization of gas oil and model compounds by anatase nanocomposite sandwich type polyoxometalate as a novel, reusable and green nano mercaptan scavenger

Oxidative desulphurization of gas oil and model compounds that exist in gas oil with hydrogen peroxide/acetic acid using nanoparticle (Bu4N)7H3[P2W18Cd4(Br)2O68]-TiO2 ((Bu4N)7H3[P2W18Cd4]-TiO2) as a nano scavenger has been studied. This sandwich-type nanoparticle was shown be able to scavenge hydrogen sulfide and mercaptans with high yield. The addition of acetic acid enhanced the conversion. This system provides an efficient, convenient and practical method for scavenging of sulphur compound. The (Bu4N)7H3[P2W18Cd4]-TiO2 nanoparticle was very active catalyst system for the model compound oxidation, while other polyoxometalate systems were much less active.

Application of Non-catalytic Oxidative Desulphurization Process for Obtaining Diesel Fuels with Improved Lubricity

The fractions of diesel oil have been desulphurized via air oxidation without the catalysts in the presence of water. The products of sulphuric compounds oxidation were extracted by adsorption or joint adsorption and rectification. The samples of desulphurized diesel oil have been analyzed in accordance with reference documents after their treatment by alkali. The lubricity of the raw materials (straight-run diesel oil and hydrogenised fuel), desulphurized straight-run diesel oil (DSDO), hydrogenised fuel with DSDO additives and two samples of the fraction 553-623 K purified in the presence of water and without it has been determined.

Optimization of Oxidation Desulphurization of Power-generating Coal

An experimental statistic model of powergenerating coal oxidative desulphurization has been developed and its adequacy has been proved. On the basis of the proposed model the desulphurization optimal conditions for three samples of power-generating coal were determined. The low-sulphur solid fuel with the content of general sulphur of 1.0–1.5 mas % was obtained under established optimal conditions. Створено експериментально-статистичну модель процесу оксидаційного знесірчування кам'яного енергетичного вугілля та доведено її адекватність. З використанням запропонованої моделі знайдено оптимальні умови проведення знесірчування трьох зразків кам'яного енергетичного вугілля. Проведення процесу за цих оптимальних умов дозволило отримати низькосірчисте тверде паливо (вміст загальної сірки не перевищував 1.0-1.5% мас.).

Study of the oxidative desulphurization process of coal with different metamorphism degrees

AbstractThe oxidative desulphurization process of coal with different metamorphism degrees treated by an air-steam mixture has been studied. It has been shown that the pyrite present in black coal and anthracite is oxidized with the sulphur dioxide formation, and the process chemical mechanism does not depend on the quality of organic matter. The medium-metamorphized coal, capable of turning into a plastic state and cake in the range of investigated temperatures (350–450°C), is desulphurized with the greatest difficulty. The chemical mechanism dealing with the transformations of pyretic sulphur present in brown coal differs from similar processes taking place in black coal and anthracite, because FeS2 is converted with the help of hydrogen sulphide formation during desulphurization.

Influence of Organic Acid on Thermal Hazard of Hydrogen Peroxide

Abstract The effect of methanoic acid and acetic acid with hydrogen peroxide on oxidative desulphurization was investigated by accelerating rate calorimeter (ARC) in this paper. Their reaction order n , activation energy E a and pre-exponential factor A were calculated from these curves before and after modification of instrument constant, i.e. thermal inertia factor of ARC. The adiabatic decomposition parameters obtained show that hydrogen peroxide is of a character, i.e. it can be easily decomposed by adding methanoic acid or acetic acid. The decomposition is the easiest and activation energy lower for adding methanoic acid, which is from 179.34 kJ·mol -1 to 84.25 kJ·mol -1 and 68.35 kJ·mol -1 , respectively. The rate of temperature rise is the biggest and the rise of adiabatic temperature the highest, and the decomposition the most intense, and the risk the highest. Finally, the temperature of no return T NR and self accelerating decomposition temperature T SADT of hydrogen peroxide with some specific package were calculated by kinetic parameters, which were 312.77 K, 308.23 K respectively. However, in order to control fire or explosion of oxidative desulphurization process, the technological temperature of oil desulphurization should not be larger than their initial decomposition temperature 295.49 K and 324.38 K.

Desulphurization of some low-rank Turkish lignites with crude laccase produced from Trametes versicolor ATCC 200801

In this paper, data obtained during the oxidative desulphurization of some low-rank Turkish lignites with crude laccase enzyme produced from Trametes versicolor ATCC 200801 are presented. In order to optimize desulphurization conditions, effects of incubation time, pulp density, incubation temperature, medium pH, and also lignite source on the desulphurization have been examined. The values for incubation period, pulp density, temperature and pH in optimum incubation condition were found as 30 min, 5%, 35 °C, and pH 5.0, respectively. Under optimum conditions, treatment of coal samples with crude laccase has caused nearly 29% reduction in their total sulphur content. During the study, the rate of desulphurization of coal sample provided from Tunçbilek with crude laccase was found to be relatively higher than the other examined coal samples. Results of analytical assays have indicated that the treatment of coals with crude laccase has caused no change in their calorific values but reduced their sulphur emissions. 35%, 13%, and 25% reductions of pyritic sulphur, sulphate and organic sulphur in a period of 30 min were achieved, for a particle size of 200 μm under optimal conditions with enzymatic desulphurization. Also, statistical analyses such as Tukey Multiple Comparison tests and ANOVA were performed.

Oxidative desulphurization study of gasoline and kerosene: Role of some organic and inorganic oxidants

Desulphurization of gasoline and kerosene was carried out using organic and inorganic oxidants. Among the organic oxidants used were hydrogen peroxide in combination with acetic acid, formic acid, benzoic acid and butyric acid, while inorganic oxidants used included potassium permanganate and sodium perchlorate. The oxidation of each petroleum oil was carried out in two steps; the first step consisted of oxidation of the feed at moderate temperature and atmospheric pressure while in the second step, the oxidized mixture was extracted with azeotropic mixture of acetonitrile–water. A maximum desulphurization has occurred with NaClO 4 and hydrogen peroxide and acetic acid, which are 68% and 61%, respectively in case of gasoline and 66% and 63%, respectively in case of kerosene oil. The FTIR study of the whole and variously desulphurized gasoline and kerosene was also carried out. The results indicate considerable desulphurization by absence of bands that corresponds to sulphur moieties in NaClO 4 and hydrogen peroxide treated samples.

Temperature and water effect on the oxidative desulphurization of straight-run diesel fraction with a high sulphur content

The effect of temperature and water:raw material ratio on the oxidative desulphurization of straight-run diesel fraction 553–623 K has been examined. The optimum values of temperature and diesel fuel:water ratio for the fuel containing 0.87 wt % of sulphuric compounds have been determined.

Characterization and catalytic performance of Au/Ti-HMS catalysts on the oxidative desulphurization using in situ H 2O 2: Effect of method catalysts preparation

Au/Ti-HMS was prepared by in situ method, NH 3 deposition–precipitation (NH 3 DP) and urea deposition–precipitation (Urea DP), respectively. The catalysts were characterized by a series of techniques including ICP, powder XRD, N 2 sorption, UV–visible spectroscopy, TEM and H 2-TPR. Using n-octane containing BT, DBT and 4,6-DMDBT as model compound, the performance of the catalysts in oxidative desulfurization (ODS) using in situ generated H 2O 2 from H 2 and O 2 were investigated. The results show that preparation method influences porous structure of the support and gold particles size. In situ sample has maintained the intrinsic structure of Ti-HMS, whereas, the gold particles are not as uniform and small as that of DP sample. NH 3 DP sample still possesses the wormhole structure of HMS despite the absence of typical XRD peak. The mesoporous structure of urea DP sample has been damaged seriously. Au 3+ on outer surface of the support is easier to be reduced than that in pores, as confirmed by H 2-TPR. In addition, the three samples exhibit different catalytic activities in ODS using in situ H 2O 2 as oxidant. For the removal of BT and DBT, Au/Ti-HMS (NH 3 DP) exhibits the highest catalytic activities. Regarding the removal of 4,6-DMDBT, the optimum catalyst is Au/Ti-HMS (In situ); however, Au/Ti-HMS (Urea DP) nearly loses catalytic activity.