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01670 Promising research trends in the field of coal chemistry and technology
0 1 Solid fuels (prepara non) tuff layers are usually less kaolinized than the redeposited ones. In the higher stratigraphic horizons and in the overlying formations of every coal seam, the dominant components of the rocks are terrigenous elastic sediments. The terrigenous elastic rocks are usually composed of 2O-20% carbonates (calcite-dolomite). 00/01665
carbons. The dominance of polyaromatic sulfur compounds is consistent with the relatively mature stage of the coal (R,, z 0.7%) and their abundance at this rank indicates that the initial peat must have been extremely organic sulfur-rich (at. S,,,,/C ratio y 0.15). In conclusion, the very low abundance of lignin-derived components in the coal pyrolysate suggests that Rasa coal should not be classed a\ a typical coal.
Nanostructures in coal-derived carbons Promising
00/01670
research
trends
in the field
of coal
chemistry and technology This paper examines the fundamental mechanisms used in determining carbon nanostructures. such as the local spatial arrangement and orientation of graphene layers. The study took a special interest in coal as the organic precursor in pyrolysis and carbonization. The nanostructures are helieved to arise from liquid crystal formation during the fluid stage of carbonization. Rotating hard-line-type numerical simulations of ordering and mesophase formation during carbonization of coals were carried out in which the anisotropy were related to the initial ordering of the coals (e.g. coal rank) and the molecular mobility of the coal mass during heating. Time-dependent simulations indicated three aspects: (1) low-rank coal was virtually isotropic and remained in that state during carbonization, (2) highrank bituminous coal loses its initial anisotropy but regains it during the latter stages of carbonization, and (3) anthracite retains its anisotropy during carbonization.
00/01666 Natural gas from pre-Westphalian sources in northwest Europe. A new exploration target? Gerling, P. P,oc,. Irrr. G
Network structure of of coal-derived materials
00/01667
Coals
and association behavior
line, M. Fur/. Pwr. Twhrrol.. 2000. 62, (2-3). 89-101 The characteristics of two kinds of network structure models, i.e. covalent and non-covalent network models, were given. The applicability of these network models was examined mainly from the amount of solvent-soluble components that originally existed in coal. More than 50% of extraction yields obtained with carbon disulfide-N-methyl-2-pyrrolidinone (CSz-NMP) mixed solvent with an additive for several bituminous coals suggest that the non-covalent network model is better than the covalent one for those coals. But network structures for other coals, which gave a low extraction yield such as Iignites, are not clear. Association hehaviours of coal-derived materials are also reviewed from their solubility. molecular weight. viscosity, and vapour pressure. Small-angle neutron scattering (SANS) measurements of coal extracts in the solution show the formation of large associates. Interactions responsible for the association of coal-derived materials such as coal extracts and liquefaction products are considered to be hydrogen bonds, T-?T interactions between aromatic rings, and electrostatic interactions. No clear evidence for the contribution of charge transfer interactions has been obtained.
00/01666 Observations of heterogeneity coal particles
in large
pulverized
Gibbins, J. R. 0c~g.r Fw/.r. 1999. 13. (3). 592-601. Density separation and optical and scanning electron microscopes were used to examine the heterogeneity of the 125-212 I’m size cuts from four pulverized coal samples from the United Kingdom, United States, and South Africa. While average properties of the overall size cut samples are similar to those of the parent coals, a high degree of heterogeneity exists between average compositions for the different density cuts within each sample, between different particles within the same density cuts, and in many cases, within the particles themselves. Conventional analyses are unsuited for describing this heterogeneity and an alternative descriptive method based on maceral associations has been used, together with illustrative micrographs.
00/01669
Organosulfur compounds in sulfur-rich Rasa coal
Damste, J. S. S. Errc’rgj Fw/.Y. 1999. 13. (3). 728-738. Gas chromatography-high-resolution mass spectrometry has heen used to identify the organosulfur compounds in the extract and pyrolysate of the unusually organic sulfur-rich (I I .4 wt%) Upper Palaeocene Rasa coal. The major organosulfur compounds (OSC) present in the extract are alkylated benzo-[b]and dihenzothiophenes and in the pyrolysates alkylated thiophenes and benzo[b]thiophenes. Furthermore, a large suite of sulfurcontaining polyaromatics was identified, which occasionally contain more than one sulfur atom per molecule. The degree of alkylation of many homologous series was found to maximize at either three, four, or five alkyl
Marzec. A. Ko,ho-E,te~~ocli[,~~f.~~~f)/., I9YX. 43. (17). 379 3X1, (In Polrsh) Coal research trends are hriefly reviewed in this article. The main arcas focused on include: optimization of combustion and gasrfication NO, and SO, emission control, coal-derived sorbents. coal minerals. waste and biomass fuels for COZ emission ahatcment. coking. coal liquetaction and fundamental research.
The use of coals as catalysts for the oxidative dehydrogenation of n-butane
00/01671
Maldonado-Hodar, F. J. Appl. Carcll., A. 1999, 178. (I ). 49960. The study focused on in this paper is the oxidative dehydrogenation (ODH) of n-butane using coals as catalysts. The influence of oxygen and butane partial pressures, temperature. contact time and coal rank were investigated. The used coals were characterized texturally. which includes surface area and mercury porosimetry and chemically (ash content and elemental analysis). The coals proved to have an excellent catalytrc hehaviour, hut only in the presence of gaseous O1. which lead\ to the occurrence of two simultaneous processes: butane conversion. which includes both ODH and deep oxidation and coal combustion. Butane conversion favours an increase in oxygen partial pressure and temperature. However, at >SOO , cracking and isomerization reactions occurred. leading to decreased selectivity to (C,) dehydrogenation products. A strong increase in (‘4 selectivity wa\ encouraged by an increase in contact time. Increasing coal rank (from lignite to high-volatile bituminous coals) also favoured butane conversion: however, higher-rank coals led to smaller conversions. The highest dehydrogenation yields were obtained with high-volatile hituminous coal. Under any experimental conditions, when the reaction starts, hutadiene i\ the main product formed.
Thermogravimetric and rock-eval studies of coal properties and coal rank
00/01672
Huang, H. Errerg), Frrcls. 1999. 13. (2). 396 ~400 Thermo-gravimetric analysis (TGA) has been used to inve\tigatc a wide range of coal ranks from lignite to anthracite. There is a strong correlation (r’ = 0.998) between the derived peak maximum for volatrle matter evolution vitrinite reflectance. Thus. providing a convenient measure of degree of coalification (coal rank). 7’,,,,\, by the Rock-Eva1 method also shows a positive although somewhat poorer correlation (r’ = 0.856) with vitrinite reflectance.
Preparation 00101673 A new coal tailings washing plant M. Iwowriw.\ Mirwr. CoralPm L’\j., PIWC~. Inr. MI~JI. Proc(‘5<. 1998, 351-356. Edited by Atak S.. Onal G.. Celrk M. S. Older coal dumps very often contain schistose rejects, which, when ‘washed’, produce leftover coal in a quantity that varies between 6%12% of retrieved coal. As a result of this, EXTERBEL. a Belgian company, has created and established a novel technology, washing in two stages in a dense suspension, created with a pulp made up of sludge and water. A scrolled barrel is used to gravimetrically separate the material from the first stage. it then undergoes centrifugation in a cyclone system. The coal then is drained and dried. the schist reintegrated to match the local terrain on the site. The system is very flexible and economic. easy to handle. environmentally excellent and more or less applicable for most raw material processing purposes. Rumberger,
Swap..71/r.
:0//:\;4,
Bacterial desulphurization of coal from Lupeni in
Fecko,
Prm Iflt Miwr. P,ow\\ P. 1m1o~rior1.r Mirw Cm/ Prows\ 7rh. 1998. 361-366. Edited by Atak S.. Onal G.. Celik M. S. This paper describes the bacterial desulfurization of coal from Lupeni. The results indicate that clean cultures of Thiobacillus ferrooxidans almost completely removed pyrite after one month of leaching. Total desulfurization of coal was approximately 63%. Su77p..
00101675 Calcination of calcium acetate and calcium magnesium acetate: effect of the reacting atmosphere Adanez, J. Fuel. 1999, 78. (5). 583~ 592 As a previous step for coal gas desulfurization during sorhent injection at high temperatures, the calcination process of the calcium acetate and calcium magnesium acetate was investigated. The reason behind this study was the excellent results demonstrated by these sorbents as sulfur removal agents both in combustion and gasification processes. As the development of pore structure during calcination is one of the most significant characteristics of the sorbent related with the later reaction with the
Fuel and Energy Abstracts
July 2000
193
carbons. The dominance of polyaromatic sulfur compounds is consistent with the relatively mature stage of the coal (R,, z 0.7%) and their abundance at this rank indicates that the initial peat must have been extremely organic sulfur-rich (at. S,,,,/C ratio y 0.15). In conclusion, the very low abundance of lignin-derived components in the coal pyrolysate suggests that Rasa coal should not be classed a\ a typical coal.
Nanostructures in coal-derived carbons Promising
00/01670
research
trends
in the field
of coal
chemistry and technology This paper examines the fundamental mechanisms used in determining carbon nanostructures. such as the local spatial arrangement and orientation of graphene layers. The study took a special interest in coal as the organic precursor in pyrolysis and carbonization. The nanostructures are helieved to arise from liquid crystal formation during the fluid stage of carbonization. Rotating hard-line-type numerical simulations of ordering and mesophase formation during carbonization of coals were carried out in which the anisotropy were related to the initial ordering of the coals (e.g. coal rank) and the molecular mobility of the coal mass during heating. Time-dependent simulations indicated three aspects: (1) low-rank coal was virtually isotropic and remained in that state during carbonization, (2) highrank bituminous coal loses its initial anisotropy but regains it during the latter stages of carbonization, and (3) anthracite retains its anisotropy during carbonization.
00/01666 Natural gas from pre-Westphalian sources in northwest Europe. A new exploration target? Gerling, P. P,oc,. Irrr. G
Network structure of of coal-derived materials
00/01667
Coals
and association behavior
line, M. Fur/. Pwr. Twhrrol.. 2000. 62, (2-3). 89-101 The characteristics of two kinds of network structure models, i.e. covalent and non-covalent network models, were given. The applicability of these network models was examined mainly from the amount of solvent-soluble components that originally existed in coal. More than 50% of extraction yields obtained with carbon disulfide-N-methyl-2-pyrrolidinone (CSz-NMP) mixed solvent with an additive for several bituminous coals suggest that the non-covalent network model is better than the covalent one for those coals. But network structures for other coals, which gave a low extraction yield such as Iignites, are not clear. Association hehaviours of coal-derived materials are also reviewed from their solubility. molecular weight. viscosity, and vapour pressure. Small-angle neutron scattering (SANS) measurements of coal extracts in the solution show the formation of large associates. Interactions responsible for the association of coal-derived materials such as coal extracts and liquefaction products are considered to be hydrogen bonds, T-?T interactions between aromatic rings, and electrostatic interactions. No clear evidence for the contribution of charge transfer interactions has been obtained.
00/01666 Observations of heterogeneity coal particles
in large
pulverized
Gibbins, J. R. 0c~g.r Fw/.r. 1999. 13. (3). 592-601. Density separation and optical and scanning electron microscopes were used to examine the heterogeneity of the 125-212 I’m size cuts from four pulverized coal samples from the United Kingdom, United States, and South Africa. While average properties of the overall size cut samples are similar to those of the parent coals, a high degree of heterogeneity exists between average compositions for the different density cuts within each sample, between different particles within the same density cuts, and in many cases, within the particles themselves. Conventional analyses are unsuited for describing this heterogeneity and an alternative descriptive method based on maceral associations has been used, together with illustrative micrographs.
00/01669
Organosulfur compounds in sulfur-rich Rasa coal
Damste, J. S. S. Errc’rgj Fw/.Y. 1999. 13. (3). 728-738. Gas chromatography-high-resolution mass spectrometry has heen used to identify the organosulfur compounds in the extract and pyrolysate of the unusually organic sulfur-rich (I I .4 wt%) Upper Palaeocene Rasa coal. The major organosulfur compounds (OSC) present in the extract are alkylated benzo-[b]and dihenzothiophenes and in the pyrolysates alkylated thiophenes and benzo[b]thiophenes. Furthermore, a large suite of sulfurcontaining polyaromatics was identified, which occasionally contain more than one sulfur atom per molecule. The degree of alkylation of many homologous series was found to maximize at either three, four, or five alkyl
Marzec. A. Ko,ho-E,te~~ocli[,~~f.~~~f)/., I9YX. 43. (17). 379 3X1, (In Polrsh) Coal research trends are hriefly reviewed in this article. The main arcas focused on include: optimization of combustion and gasrfication NO, and SO, emission control, coal-derived sorbents. coal minerals. waste and biomass fuels for COZ emission ahatcment. coking. coal liquetaction and fundamental research.
The use of coals as catalysts for the oxidative dehydrogenation of n-butane
00/01671
Maldonado-Hodar, F. J. Appl. Carcll., A. 1999, 178. (I ). 49960. The study focused on in this paper is the oxidative dehydrogenation (ODH) of n-butane using coals as catalysts. The influence of oxygen and butane partial pressures, temperature. contact time and coal rank were investigated. The used coals were characterized texturally. which includes surface area and mercury porosimetry and chemically (ash content and elemental analysis). The coals proved to have an excellent catalytrc hehaviour, hut only in the presence of gaseous O1. which lead\ to the occurrence of two simultaneous processes: butane conversion. which includes both ODH and deep oxidation and coal combustion. Butane conversion favours an increase in oxygen partial pressure and temperature. However, at >SOO , cracking and isomerization reactions occurred. leading to decreased selectivity to (C,) dehydrogenation products. A strong increase in (‘4 selectivity wa\ encouraged by an increase in contact time. Increasing coal rank (from lignite to high-volatile bituminous coals) also favoured butane conversion: however, higher-rank coals led to smaller conversions. The highest dehydrogenation yields were obtained with high-volatile hituminous coal. Under any experimental conditions, when the reaction starts, hutadiene i\ the main product formed.
Thermogravimetric and rock-eval studies of coal properties and coal rank
00/01672
Huang, H. Errerg), Frrcls. 1999. 13. (2). 396 ~400 Thermo-gravimetric analysis (TGA) has been used to inve\tigatc a wide range of coal ranks from lignite to anthracite. There is a strong correlation (r’ = 0.998) between the derived peak maximum for volatrle matter evolution vitrinite reflectance. Thus. providing a convenient measure of degree of coalification (coal rank). 7’,,,,\, by the Rock-Eva1 method also shows a positive although somewhat poorer correlation (r’ = 0.856) with vitrinite reflectance.
Preparation 00101673 A new coal tailings washing plant M. Iwowriw.\ Mirwr. CoralPm L’\j., PIWC~. Inr. MI~JI. Proc(‘5<. 1998, 351-356. Edited by Atak S.. Onal G.. Celrk M. S. Older coal dumps very often contain schistose rejects, which, when ‘washed’, produce leftover coal in a quantity that varies between 6%12% of retrieved coal. As a result of this, EXTERBEL. a Belgian company, has created and established a novel technology, washing in two stages in a dense suspension, created with a pulp made up of sludge and water. A scrolled barrel is used to gravimetrically separate the material from the first stage. it then undergoes centrifugation in a cyclone system. The coal then is drained and dried. the schist reintegrated to match the local terrain on the site. The system is very flexible and economic. easy to handle. environmentally excellent and more or less applicable for most raw material processing purposes. Rumberger,
Swap..71/r.
:0//:\;4,
Bacterial desulphurization of coal from Lupeni in
Fecko,
Prm Iflt Miwr. P,ow\\ P. 1m1o~rior1.r Mirw Cm/ Prows\ 7rh. 1998. 361-366. Edited by Atak S.. Onal G.. Celik M. S. This paper describes the bacterial desulfurization of coal from Lupeni. The results indicate that clean cultures of Thiobacillus ferrooxidans almost completely removed pyrite after one month of leaching. Total desulfurization of coal was approximately 63%. Su77p..
00101675 Calcination of calcium acetate and calcium magnesium acetate: effect of the reacting atmosphere Adanez, J. Fuel. 1999, 78. (5). 583~ 592 As a previous step for coal gas desulfurization during sorhent injection at high temperatures, the calcination process of the calcium acetate and calcium magnesium acetate was investigated. The reason behind this study was the excellent results demonstrated by these sorbents as sulfur removal agents both in combustion and gasification processes. As the development of pore structure during calcination is one of the most significant characteristics of the sorbent related with the later reaction with the
Fuel and Energy Abstracts
July 2000
193