VARIATION IN THE CHEMICAL NATURE OF ASPHALTENES WITH THE PROCESS,THE COAL AND THE REACTION CONDITIONS

ABSTRACT

Average structure data for twelve asphaltenes are reported, based on ¹³C- and H- n.m.r. spectroscopy combined with elemental, molecular weight and functional group analyses. The asphaltenes were from supercritical gas extraction, flash pyrolysis and hydrogenation of a brown and a bituminous coal. The effect of the reaction temperature and, for hydrogenation, the catalyst and solvent on the nature of the asphaltene produced was studied. The asphaltene obtained from supercritical gas extraction of the brown coal at 350°C was the least aromatic (f_a = 0.44) with the highest H/C atomic ratio (1.16) and probably consists mainly of single ring aromatlcs with about half of the aromatic sites substituted. A significant proportion of the carbon in this asphaltene is in long alkyl chains and the hydroxyl content is high. Whereas, the asphaltenes produced by hydrogenatlon of the bituminous coal at 450°C were far more aromatic with more highly condensed but less substituted aromatic ring systems and few, if any, long alkyl chains, together with a lower hydroxyl content. The asphaltenes obtained from the brown coal are less aromatic with less condensed aromatic ring systems but a higher degree of aromatic substitution than those produced from the bituminous coal under the same conditions. The asphaltenes formed at 450°C had lower H/C atomic ratios, molecular weights and degree of aromatic substitution, but higher aromaticities Ohan those produced at 35O°C or 400°C under like processing conditions. The asphaltene produced in the presence of both stannous chloride catalyst and tetralin was less aromatic than when either of these species was absent.     

EXTRACTION ENHANCEMENT OF COAL THROUGH CHEMICAL REACTIONS WITH CETENE AND CETANOL IN THE ANTHRACENE OIL UNDER ATMOSPHERIC PRESSURE CONDITIONS

ABSTRACT

Assam coal has been reacted with cetene or cetanol in anthracene oil. These reactions were attempted to alkylate the coal in the absence of a catalyst under the conditions of extractive disintegration of coal. Coal derived chemicals were used in the reactions as far as possible. The reactions resulted in enhancing the extractability of coal in quinoline by more than 70–90%. These reactions resulted in the alkylation of coal and increase of carbon contents in coal along with the addition of nitrogenous bases from anthracene oil to coal.     

EXTRACTION ENHANCEMENT OF COAL THROUGH CHEMICAL REACTIONS WITH CETENE AND CETANOL IN THE ANTHRACENE OIL UNDER ATMOSPHERIC PRESSURE CONDITIONS

Assam coal has been reacted with cetene or cetanol in anthracene oil. These reactions were attempted to alkylate the coal in the absence of a catalyst under the conditions of extractive disintegration of coal. Coal derived chemicals were used in the reactions as far as possible. The reactions resulted in enhancing the extractability of coal in quinoline by more than 70-90%. These reactions resulted in the alkylation of coal and increase of carbon contents in coal along with the addition of nitrogenous bases from anthracene oil to coal.     

Knoevenagel法合成肉桂酸及其工艺优化

以苯甲醛和丙二酸为原料,吡啶为催化剂,利用Knoevenagel反应合成肉桂酸,从而降低了反应温度,提高了收率和产物纯度,简化了合成工艺。同时通过正交实验探讨了不同工艺参数如反应物配比、反应时间、催化剂种类和用量等对肉桂酸收率的影响,确定的最佳工艺条件为:以吡啶为催化剂,n(苯甲醛):n(丙二酸)= 1:3,催化剂用量0．02mol,反应时间为90min,肉桂酸收率可达90%。     

THE VARIATION OF SULFUR FORMS IN SUPERCRITICAL DESULFURIZATION OF COAL WITH ETHANOL

Using Mossbauer and X-ray Photoelectron Spectroscopy ( XPS) techniques the sulfur forms in solid products obtained at different reaction were analyzed. The results show that: during supercritical desulfurization the pyritic sulfur is removed as following process: FeS₂ -FeS+ Fe_1-x S, the transformation amounts and the value of x are dependent on reaction conditions, especially on temperature. The conversion of pyrite is very little at 275° C. Pyrrhotite ( Fe_1-xS) is Fes_1.101 at 275° C and Fe_1.085 at 450° C. Among the organic sulfur groups PhSH. Ph₂ S and thiolane are easily removed; Ph ₂ SO is more difficult to be removed, its removal may be realized by increasing temperature and adding some water into ethanol; thiophene is most difficult to be removed, its removal needs high reaction temperature     

THE VARIATION OF SULFUR FORMS IN SUPERCRITICAL DESULFURIZATION OF COAL WITH ETHANOL

ABSTRACT

Using Mossbauer and X-ray Photoelectron Spectroscopy ( XPS) techniques the sulfur forms in solid products obtained at different reaction were analyzed. The results show that: during supercritical desulfurization the pyritic sulfur is removed as following process: FeS₂ -FeS+ Fe_1-x S, the transformation amounts and the value of x are dependent on reaction conditions, especially on temperature. The conversion of pyrite is very little at 275° C. Pyrrhotite ( Fe_1-xS) is Fes_1.101 at 275° C and Fe_1.085 at 450° C. Among the organic sulfur groups PhSH. Ph₂ S and thiolane are easily removed; Ph ₂ SO is more difficult to be removed, its removal may be realized by increasing temperature and adding some water into ethanol; thiophene is most difficult to be removed, its removal needs high reaction temperature     

EFFECT OF EXPERIMENTAL CONDITIONS AND SOLVENTS ON THE PRECIPITATION AND COMPOSITION OF ASPHALTENES

The ASTM D 3279 test method for “n-Heptane Insolubles” is being currently used to determine the asphaltene content of fuel oils as defined by insolubility in normal (n) heptane solvent. Precipitation of n-heptane insolubles can produce sediments which vary in color, morphology and composition. The SEM analysis of n-heptane insolubles indicated that the sediments were heterogeneous containing some large particles >300 μ and the majority of particles to be small, <10 μ, “chained” together forming agglomerates. Significant fractions of n-heptane insolubles were found insoluble in toluene indicating their non-asphaltenic nature (“solids”). FTIR and XRF analyses of “solids” indicated the presence of multiring aromatics, Ni and carboxylate and sulfate salts. FTIR analysis of toluene soluble asphaltenes showed the presence of multiring aromatics. GC/MS analysis of toluene soluble asphaltenes indicated desorption of alkylbenzenes and O-containing molecules but no desorption of N- and S-containing molecules was observed. The tendency for N- and S-containing molecules to remain in the nonvolatile residue during the GC/MS analysis indicates that the N- and S-containing compounds have higher stability. The XRF analysis of the toluene soluble asphaltenes indicated that the molecules are similar to asphaltenes found in crude oils in terms of C, H, N and S contents, however, no presence of V- and Ni-containing molecules was found.     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

ABSTRACT

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.     

催化裂化汽油加氢脱硫及芳构化工艺反应条件的研究

在100 mL固定床反应器试验装置上,针对中国石化集团洛阳石油化工工程公司工程研究院开发的催化裂化汽油加氢脱硫及芳构化技术(Hydro-GAP),考察了反应温度,氢分压、进料空速、氢油体积比等工艺条件对加氢脱硫及芳构化反应的影响.结果表明:随着反应温度、氢分压的升高和空速的减小,加氢脱硫性能提高;芳构化性能随反应温度的升高、氢分压的降低而增加.氢油体积比对加氢脱硫及芳构化性能影响不大.     

减压渣油中胶状沥青状物质的化学结构研究

利用对芳香碳有高选择性转化能力的钌离子催化氧化法研究了减压渣油中轻、中、重胶质和戊烷沥青质的化学结构,定量了与芳香环相连的正构烷基侧链和桥链的分布,并了芳香环系的缩合型式,结果表明,这些石油重质组分中均存在碳数为Ｃ１￣Ｃ３０的与芳香 相连的正构烷基侧链,其摩尔浓度随链长的增加而下降,也存在由正构烷基桥连接的至少具有两个芳香环系的芳香性分子,在芳香结构中存在着渺位缩合,迫位缩合以联苯型结构,其中联苯     

PYROLYSIS AND LIQUEFACTION OF BRAZILIAN COAL AND COAL-DERIVED ASPHALTENES

The present work describes a study of the liquefaction and pyrolysis of a Southern Brazilian mineral coal and its derived asphaltenes, using conversion systems developed in our laboratory.

The results show that significant quantities of the intermediate polarity fraction named resins is obtained through the pyrolysis of coal, while after the liquefaction process higher quantities of the higher fractions was found. A model is proposed to explain the liquefaction and pyrolysis processes of both coal and coal-derived asphaltenes.     

CORRELATION OF COAL AND OVERBURDEN MINERALOGY WITH INORGANIC CONSTITUENTS IN UCG PROCESS EFFLUENTS

Inorganic constituents present in UCG process effluents can be strongly correlated with changes in coal and overburden mineralogy. An analysis of the Hanna, Wyoming, UCG site provides insight on how inorganic constituents enter the system. A comparison of preburn versus postburn mineralogy indicates that carbonates, clay minerals, micas, and sulfurous minerals break down structurally because of high temperatures. This decomposition releases calcium, magnesium, silica, and aluminum for rebonding in high-temperature stable silicate and al um1 nosi1icate minerals. It also releases constituents such as iron, sodium, sulfur, and boron into the UCG process effluent. Other constituents such as calcium, copper, magnesium, manganese, potassium, and sodium are predominantly introduced into the groundwater by leaching. Groundwater quality data and analyses of other process effluents support these interpretations. Complete chemical and mineralogical characterization of the coal, coal ash, and immediate overburden is an important tool in determining inorganic constituents that affect groundwater quality at UCG sites. Early planning offers substantial economic incentives by allowing treatment while the constituents are confined to the cavity before migration affects much larger areas.     

CORRELATION OF COAL AND OVERBURDEN MINERALOGY WITH INORGANIC CONSTITUENTS IN UCG PROCESS EFFLUENTS

ABSTRACT

Inorganic constituents present in UCG process effluents can be strongly correlated with changes in coal and overburden mineralogy. An analysis of the Hanna, Wyoming, UCG site provides insight on how inorganic constituents enter the system. A comparison of preburn versus postburn mineralogy indicates that carbonates, clay minerals, micas, and sulfurous minerals break down structurally because of high temperatures. This decomposition releases calcium, magnesium, silica, and aluminum for rebonding in high-temperature stable silicate and al um1 nosi1icate minerals. It also releases constituents such as iron, sodium, sulfur, and boron into the UCG process effluent. Other constituents such as calcium, copper, magnesium, manganese, potassium, and sodium are predominantly introduced into the groundwater by leaching. Groundwater quality data and analyses of other process effluents support these interpretations. Complete chemical and mineralogical characterization of the coal, coal ash, and immediate overburden is an important tool in determining inorganic constituents that affect groundwater quality at UCG sites. Early planning offers substantial economic incentives by allowing treatment while the constituents are confined to the cavity before migration affects much larger areas.     

PHYSICAL AND CHEMICAL CHARACTERIZATIONS OF ASPHALTENES FROM DIFFERENT SOURCES

ABSTRACT

Asphaltenes and resins are two of the several, but important, heavy organics present in petroleum fluids. Asphaltenes are operationally defined as the non-colatile and polar fraction of petroleum that is insoluble in n-alkanes (i.e., n-pentane). Conversely resins are defined as the non-colatile and polar fraction of petroleum that is soluble in n-alkanes (i.e., n-pentane), and aromatic solvents (i.e., toluene), and insoluble in ethyl acetate. A commonly accepted view in the petroleum chemistry is that crude oil asphaltenes form micelles which are stabilized by adsorbed resins kept in solution by aromatics. Two key parameters that control the stability of asphaltene micelles in a crude oil are the ratio of aromatics to saturates and that of resins to asphaltenes. When these ratios decrease, asphaltene micelles will coalesce and form larger aggregates. The precipitation of asphaltene aggregates can cause problems such as reservoir plugging and wettability reversal.     

PHYSICAL AND CHEMICAL CHARACTERIZATIONS OF ASPHALTENES FROM DIFFERENT SOURCES

Asphaltenes and resins are two of the several, but important, heavy organics present in petroleum fluids. Asphaltenes are operationally defined as the non-colatile and polar fraction of petroleum that is insoluble in n-alkanes (i.e., n-pentane). Conversely resins are defined as the non-colatile and polar fraction of petroleum that is soluble in n-alkanes (i.e., n-pentane), and aromatic solvents (i.e., toluene), and insoluble in ethyl acetate. A commonly accepted view in the petroleum chemistry is that crude oil asphaltenes form micelles which are stabilized by adsorbed resins kept in solution by aromatics. Two key parameters that control the stability of asphaltene micelles in a crude oil are the ratio of aromatics to saturates and that of resins to asphaltenes. When these ratios decrease, asphaltene micelles will coalesce and form larger aggregates. The precipitation of asphaltene aggregates can cause problems such as reservoir plugging and wettability reversal.     

IMPREGNATION AND RECOVERABILITY OF ELEMENTAL SULFUR IN COAL USING THE PERCHLOROETHYLENE DESULFURIZATION PROCESS

ABSTRACT

During the perchloroethylene extraction process, C-S bond cleavage reactions occur, which liberate labile sulfur from the organic matrix of coal into the solvent medium i.e., perchloroethylene, where it is dissolved and extracted. In this paper, the effect of impregnation of elemental sulfur in raw coal on its forms of sulfur analyses has been investigated. The effect of the same sulfur-impregnated coal on its organosulfur extractability has also been explored. Studies were conducted to observe whether the impregnated elemental sulfur was fully recoverable by the perchloroethylene extraction process. It was observed that sulfur can be very easily impregnated into the microstructure of coal. On the basis of tests on raw and impregnated coals, based on ASTM D-2492 standard, the impregnated sulfur reflects mostly in the form of organic sulfur. The impregnated sulfur which appears in the form of organic sulfur is fully recoverable via the perchloroethylene extraction     

IMPREGNATION AND RECOVERABILITY OF ELEMENTAL SULFUR IN COAL USING THE PERCHLOROETHYLENE DESULFURIZATION PROCESS

During the perchloroethylene extraction process, C-S bond cleavage reactions occur, which liberate labile sulfur from the organic matrix of coal into the solvent medium i.e., perchloroethylene, where it is dissolved and extracted. In this paper, the effect of impregnation of elemental sulfur in raw coal on its forms of sulfur analyses has been investigated. The effect of the same sulfur-impregnated coal on its organosulfur extractability has also been explored. Studies were conducted to observe whether the impregnated elemental sulfur was fully recoverable by the perchloroethylene extraction process. It was observed that sulfur can be very easily impregnated into the microstructure of coal. On the basis of tests on raw and impregnated coals, based on ASTM D-2492 standard, the impregnated sulfur reflects mostly in the form of organic sulfur. The impregnated sulfur which appears in the form of organic sulfur is fully recoverable via the perchloroethylene extraction     

ENVIRONMENTAL AND ECONOMIC ISSUES IN THE USE OF PERCHLOROETHYLENE AS THE SOLVENT IN PERCHLOROETHYLENE COAL CLEANING PROCESS

The Perchloroethylene coal cleaning process effectively removes both organic and inorganic forms of sulfur in coal. Complete recyclability of the solvent is the key to both economic and environmental issues concerning the use of perchloroethylene in this process. Recyclability of the solvent has been fully established by repeated batch operation as well as FTIR structural investigations of solvent molecules. In the current investigation, the solvent has been subjected to various analyses after each stage in the operation i.e., before extraction, after extraction and after distillation. The organic desulfurization is based on an extraction-reaction mechanism and is catalyzed by the mineral matter inherently and naturally present in coal. This paper also aims at studying the role played by the solvent (perchloroethylene) in the extraction process as well as in the catalytic reaction occurring in the system. This paper also presents data on the effect of re-using 'sulfur-rich mother liquor', rich in extracted sulfur, on the organosulfur extraction efficiency. These data are very important from the point of view of process engineering and economics.     

ENVIRONMENTAL AND ECONOMIC ISSUES IN THE USE OF PERCHLOROETHYLENE AS THE SOLVENT IN PERCHLOROETHYLENE COAL CLEANING PROCESS

ABSTRACT

The Perchloroethylene coal cleaning process effectively removes both organic and inorganic forms of sulfur in coal. Complete recyclability of the solvent is the key to both economic and environmental issues concerning the use of perchloroethylene in this process. Recyclability of the solvent has been fully established by repeated batch operation as well as FTIR structural investigations of solvent molecules. In the current investigation, the solvent has been subjected to various analyses after each stage in the operation i.e., before extraction, after extraction and after distillation. The organic desulfurization is based on an extraction-reaction mechanism and is catalyzed by the mineral matter inherently and naturally present in coal. This paper also aims at studying the role played by the solvent (perchloroethylene) in the extraction process as well as in the catalytic reaction occurring in the system. This paper also presents data on the effect of re-using ‘sulfur-rich mother liquor’, rich in extracted sulfur, on the organosulfur extraction efficiency. These data are very important from the point of view of process engineering and economics.     

THE EFFECT OF LOW TEMPERATURE OXIDATION ON THE CHEMICAL AND PHYSICAL PROPERTIES OF MALTENES AND ASPHALTENES DERIVED FROM HEAVY OIL

The chemical changes that occur when the maltene and asphaltene fractions (separated from heavy oil) are subjected to low temperature oxidation (LTO) in the presence and absence of water have been investigated by a combination of classical separation techniques and analytical pyrolysis. In general, it is observed that water has a mitigating effect on the destructive nature of LTO. A detailed analysis of the pyrolytic products suggests that the presence of water reduces the ease with which oxygen reacts with sulfides to give sulfones and thereby supresses the formation of coke. An analysis of the data indicates that most of the coke produced results from LTO of the asphaltenes; only a small portion originates in the maltenes.