Organic Sulfur In Coal Research Articles

The investigation on the removal mechanism of organic sulphur in coal under the external energy

The investigation on the removal mechanism of organic sulphur in coal under the external energy

A novel and effective method for removing organic sulfur from low rank coal

The organic sulfur in coal is difficult to remove using gravity separation, oil agglomeration and flotation. Even though chemical leaching/oxidation and bio-desulfurization by bacteria are considered as the efficient methods in organic sulfur removal from low rank coal, these chemical and biological desulfurization technologies are usually difficult to be quickly applied in coal cleaning industry. In this investigation, the reduced iron (Fe) powder, acting as a promoter, was introduced to enhance the desulfurization of low rank coal. Low rank coal was pre-heated with the Fe powder, and then the coal char was forwarded to dry magnetic separation. The organic sulfur in coal could be bonded with Fe and form the Fe-related magnetic compounds which is effectively separated by dry magnetic separator.

Research on the Composition and Distribution of Organic Sulfur in Coal.

The structure and distribution of organic sulfur in coals of different rank and different sulfur content were studied by combining mild organic solvent extraction with XPS technology. The XPS results have shown that the distribution of organic sulfur in coal is related to the degree of metamorphism of coal. Namely, thiophenic sulfur content is reduced with decreasing metamorphic degree; sulfonic acid content rises with decreasing metamorphic degree; the contents of sulfate sulfur, sulfoxide and sulfone are rarely related with metamorphic degree. The solvent extraction and GC/MS test results have also shown that the composition and structure of free and soluble organic sulfur small molecules in coal is closely related to the metamorphic degree of coal. The free organic sulfur small molecules in coal of low metamorphic degree are mainly composed of aliphatic sulfides, while those in coal of medium and high metamorphic degree are mainly composed of thiophenes. Besides, the degree of aromatization of organic sulfur small molecules rises with increasing degree of coalification.

Study on occurrence of sulfur in different group components of Xinyu clean coking coal

This paper illustrates the occurrence and distribution of sulfur in coal from the perspective of composition and structure of the coal body. With the organic sulfur-rich Xinyu clean coking coal as the sample, and the method of separating all group components from coal through extraction and stripping process as well as X-ray photoelectron spectroscopy (XPS) and gas chromatography/mass spectrometer (GC/MS) analysis techniques, the content of inorganic sulfur and organic sulfur of different forms in raw coal and various group components is studied and the occurrence of organic sulfur in organic matter of coal is carefully observed. The results show the distribution of inorganic sulfur is mainly dependent upon its particle size and density in coal and has less relationship with the structure of group components of coal. Thiophene sulfur is the major form of organic sulfur either in raw coal or group components. The external environment of molecules dominated by conjugated structure can decrease the electron binding energy of organic sulfur in conjugated structure, while increase that of sulfur in aliphatic structure. The distribution of organic sulfur in coal is balanced as a whole and will not be significantly influenced by structural differences of group components. However, the occurrence of organic sulfur compounds is associated with the structure of group components, showing relatively small difference. And there is only one type of small molecule organic sulfur compounds in light component, with small abundance.

Mechanism Research on Electrochemical Catalytic Oxidation Desulfurization of High Sulfur Coal

Electrochemical desulfurization is a mild chemical desulfurization method. This paper introduces the electrochemical catalytic oxidation method which is used to process High Sulfur Coal samples under acidic condition. Study tells that during the processing of electrochemical catalytic oxidation desulfurization ,pyrite and organic sulfur in coal are oxidized and converted into water soluble sulfur compounds by some active oxygen and other oxidizing agent or high valence ions which are produced on the surface of electrolytic anode.After analyzing the experiments ,another conclusion that the desulfurization process is faster for the added catalyst ion also involving in the reaction is reached.

Increased total sulfur content in coal from Donets and other basins

The ash composition is used to assess the conditions of coal-bed formation in the Donets and L’vovsk-Volynsk basins. The experimental data are inconsistent with some aspects of the hypothesis that pyrite and secondary organic sulfur are formed in the coal. The lack of a relationship between the total sulfur content Std in the coal and the MgO content in its ash does not agree with the notion that sulfates from sea water provide the basis source of nonvegetative sulfur in coal. The actual Std values do not always correspond to the theory that the source of sulfur depends on the alkalinity of the water and the reducing medium where the deposits accumulate. In the conditions that are most favorable to the formation of coal with high total sulfur content (Std > 4 wt %) according to the existing hypothesis, the actual value of Std is no more than 1.5%. The source of pyrite and organic sulfur in coal requires further discussion.

Desulfuration of electrolyzed coal water slurry in HCl system with ionic liquid addition

Effects of ionic liquid-assisted on electrolyzed desulfuration of coal water slurry (CWS) in HCl system were investigated by constant-current electrolysis. The results indicated that the desulfuration effects from CWS electrolysis in the HCl system were improved, and the removal effects of organic sulfur in coal were improved as ionic liquids increased. On the other hand, reduction of electrolysis on cathode showed that hydro-desulfuration ratio with 1-butyl-3-methylimidazolium bromide (C8H15N2Br) was higher than that with 1-butyl-3-methylimidazolium chloride (C8H15N2Cl), and hydro-desulfuration ratio with pyridine ring ionic liquids was higher than that with imidazole ring. The results of ash composition showed Fe-containing mineral matters were removed by electrolysis on anode. However, they were not removed by electrolysis on cathode. In addition, the desulfuration ratio of CWS electrolysis without membrane was between anode and cathode electrolysis ratio. Finally, the mechanism of ionic liquid-assisted on electrolyzed desulfuration of CWS in HCl system was proposed.

Microwave Applied in Coal Desulfurization Process

In this paper, the desulfurization of Fangshan coal was carried out by tetrachloroethylene extraction under ultrasonic and microwave irradiation. The GC-MS analysis of the tetrachloroethylene extraction reveals that organic sulfur in coal can be removed by tetrachloroethylene extract under ultrasonic and microwave irradiation. It is found that microwave irradiation time has great effect on organic sulfur removal. With the microwave irradiation time increases, the efficiency of organic sulfur removal increases. The desulphurization yield reaches maximum, 45%, when the time is 30 minutes or more. It can be clearly seen that Fangshan coal was oxidated by peroxyacetic acid under ultrasonic and microwave irradiation. From the XPS analysis of the macerals of the coal, most of the inorganic sulfur and organic sulfur are removed, especially thioether and thioalcohol which can be completely removed. These results suggest that microwave is an effective way to remove sulfur in coal.

Desulphurization of coal via low temperature atmospheric alkaline oxidation

Different from other options which usually required strict conditions, a method combining atmospheric oxidization and chemical cleaning with alkali solutions was employed to desulphur coals at temperature around 90 °C. The data show that 66% organic sulphur, 44% sulphide sulphur, and 15% pyrite sulphur were lost when the coal was treated in 0.25 M NaOH at 90 °C, while the solution being aerated at the flow rate of 0.136 m 3 h −1. The rate increased to 73% for organic sulphur, 83% for sulphide sulphur and 84% for pyrite sulphur when the previous coal was further treated in acidic solution containing HCl at pH 1 for another hour. The mechanism of desulphurization was explored using inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy and infrared. It was found out that the bond of –C S was broken by atmospheric oxygen in basic environment, leading to the lost of organic sulphur in coal. Scanning electron microscope data show that the physical structure of the coal was not adversely affected by the treatment and thermogravimetric analysis results prove that the pyrolysis behavior remained unchanged, indicating that the burning process of the coal would not be adversely affected. Unlike other oxidizing methods, this technique does not lower the heating value of the coal which was manifested by relevant data.

Ultrasonic and Microwave Desulfurization of Coal in Tetrachloroethylene

The extractive desulfurization of four high sulfur coals from China were promoted with ultrasonic and microwave in tetrachloroethylene organic solvents. It was shown that the joint promotion with ultrasonic and microwave had an active effect on extractive desulfurization. The rate of desulfurization increased with the increase of time in ultrasonic field as well as with the power of ultrasonic, but declined with the increase of the particle size of coal. The rate of desulfurization was not identical for different coal, which was perhaps related to the existed forms of organic sulfur in coal.

Effect and influence factors of sulfur removal in coal with fungus

The influence of coal desulfurization by fungus was experimentally studied. The results suggest that fungus can effectively remove inorganic and organic sulfur in coal, and main influences of desulfurization by fungus of pH value, temperature, coal slurry concentration and coal granularity were studied by orthodox experiment and the optimal experimental conditions are as follows: pH value 6, temperature 45 °C, coal slurry concentration 10% and coal granularity 100 µm. Under above conditions, fungus can remove up to 44.96% total sulfur and 54.87% inorganic sulfur within two days, and their desulfurization rates will increase along with time. Compared with sulfolobas, desulphurization by fungus is steady and more effective, and has advantage of high speed.

Main influence factors on desulfurization of coal by sul folobas

By orthodox experiment, the main influence factors of desulfurization by sul folobas of pH value, temperature, coal slurry concentration and coal granularity are studied in detail and the optimal experimental conditions were also obtained. The experimental results demonstrate that sul folobas being kind of linking-heat, acidophilic and self-supported bacterium with double characters can effectively remove inorganic and organic sulfur in coal. The superlatively desulfurization rate is up to 48.57% total sulfur and 41.71% inorganic sulfur within 10 d and its desulfurization rate can be greatly affected by the four factors above mentioned. Therefore, the optimum conditions of desulfurization are obtained by comprehensive experiment and they are as following: pH value 3, temperature 70°C, coal slurry concentration 10% and coal granularity 150 µm, respectively. Moreover, the repetition experimental results confirm that the desulfurization by sul folobas is steady.

Organic sulphur in the hard coal of the stratigraphic layers of the Upper Silesian coal basin

The paper presents the results of investigation of organic sulphur occurrence in the coal of Upper Silesian coal basin. Six hundred coal samples from 52 mines were tested. It has been found that the content of organic sulphur in the coal depends on the stratigraphic layer, coalification grade and geographic location in the Upper Silesia region. The highest mean content of organic sulphur has been found in the most recent (ca. 0.85%) and in the oldest (ca. 0.5%) strata. The lowest mean contents of organic sulphur have been found in the intermediate strata. In the case of the most recent coals, the content of organic sulphur decreases with increasing of coalification grade. When the carbon content (C daf) exceeds 82%, the increase of coalification grade causes no further decrease of the mean content of organic sulphur. The share of organic sulphur in the total sulphur is lower in the case of more recent (<50%) and higher in the case of older coals (>50%).

Determination of Sulfur Species in Coal by X-ray Absorption Near Edge Structure Spectroscopy

The principle and analysis of sulfur K-edge X-ray absorption near edge structure (XANES) spectroscopy for structure determination of organic sulfur species in coals are reviewed. A third derivative method of the sulfur K-edge XANES spectra is compared with a least-squares method using the same Argonne Premium Coal Samples. The sulfur forms in raw, thermal treated and desulfurized coals by several treatment (bioprocessing, chemical treatment, and rapid pyrolysis) are determined. The applicability and usefulness of high-resolution sulfur XANES spectroscopy is demonstrated for direct, nondestructive and quantitative determination of the nature of organic sulfur in coal.

97/04422 Removal of organic sulfur in coal by the use of anhydrous HF and superacid HF/BF 3: Shimizu, K. et al. Chemical Lett., 1997, (9), 943–944

97/04422 Removal of organic sulfur in coal by the use of anhydrous HF and superacid HF/BF 3: Shimizu, K. et al. Chemical Lett., 1997, (9), 943–944

Removal of Organic Sulphur in Coal by the Use of Anhydrous HF and Superacid HF/BF3

Abstract Anhydrous hydrogen fluoride (HF) and HF combined with a small amount of boron trifluoride(BF3) desulphurized high-sulphur coal in the presence of hydrocarbons without H2 in mild reaction conditions. HF removed mainly sulphidic and oxidized sulphur. HF/BF3 decreased thiophenic sulphur as well as sulphidic and oxidized sulphur although the extent of desulphurization was almost the same as that with HF alone.

5606258 Control interface for an MRI system

This chapter discusses a 15N NMR method for the characterization of organic sulfur in coal and coal products through iminosulfurane formation. The conversion of organic sulfides to iminosulfuranes provides a method for attachment of an NMR-detectable nucleus directly to sulfur. The N nucleus exhibits a broad distribution of chemical shifts, and individual functional groups may exhibit a range of chemical shifts of 50–100 ppm. The 15N chemical shifts could potentially reveal the distribution of aromatic and aliphatic structure types in complex materials such as asphaltenes and preasphaltenes. The chapter presents a study to determine the sensitivity of 15N chemical shifts to substituents on sulfur and nitrogen, to identify procedures for formation of iminosulfuranes for a variety of aromatic and alkyl sulfides, and, given sufficient sensitivity of the 15N shifts to structure, to apply the method to characterization of sulfur-containing asphaltenes. The solid-state N spectrum of Ph2S=NCOCH3, obtained after 200 transients. The optimal contact time was 7.5 ms, compared to 1.5 ms for acetamide. A recycle time of at least 20 s was required to obtain satisfactory spectra. The unprotonated nitrogen exhibits a rather long cross-polarization time together with an apparently long proton relaxation time.

96/03487 Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

Sr geochemistry in coal has been studied on the basis of its distribution in 457 samples of coal, coaly shales and mineral interlayers from several Bulgarian coal deposits. Model experiments were also carried out. The analysed Sr contents are lower than the average values for coals. Only the Burgas deposit is enriched in Sr due to marine influence. The coal lithotypes liptain, vitrain, xylain and fusain are usually enriched in Sr as compared to the whole samples from which they were separated.Sr occurs in both organic (Srorg) and inorganic (Srinorg) forms. The relation to organic matter is demonstrated by: (1) Sr enrichment in low-ash coals and in lighter specific gravity fractions; (2) leaching of Sr bound to humic acids by treatment with 2% NaOH; (3) sorption experiments on xylain at pH 4-5.5 - up to 92% of Sr in solution was taken up by the sorbents; a mechanism of cation exchange as well as formation of metallo-organic complexes is proposed. Host minerals of Srinorg are aragonite, gypsum, calcite and feldspar. The highest Srinorg content is related to aragonite.

Determination of forms of organic sulfur in coal by step-wise oxidation with perchloric acid-ferric perchlorate mixture

Differentiation of organic sulfur forms in coal by step-wise oxidation with a mixture of perchloric acid (HClO4) and ferric perchlorate (Fe(ClO4)3) was studied. Various organic sulfur compounds were oxidized with HClO4 solution containing Fe(ClO4)3, and the amounts of sulfate formed during reaction were measured. The compounds can be grouped into three categories according to their reactivities as follows: (1) easily oxidized ones, i.e. disulfides, for which almost all of the sulfur was converted to sulfate after oxidation, (2) less reactive ones including aliphatic sulfides, aliphatic and aromatic thiols (20–30% of sulfur in these compounds was oxidized to sulfate), and (3) relatively stable ones, i.e. thiophenes and aromatic sulfides, from which no sulfate was formed. Samples of Illinois No. 6 and Bevier coals were also reacted with HClO4 solutions containing increasing concentration of Fe(ClO4)3. The organic sulfur in these coals could be differentiated into various groups according to their reactivities.

95/04441 Study on chemical stability of organic sulfur in coal and its structure

95/04441 Study on chemical stability of organic sulfur in coal and its structure