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Thomas Gentzis - One of the best experts on this subject based on the ideXlab platform.
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Elemental concentration and organic petrology of unique liptinite-Rich humic Coal, canneloid shale, and cannel Coal of Devonian age from Arctic Canada
Chemical Geology, 2018Co-Authors: Fariborz Goodarzi, Thomas GentzisAbstract:Abstract Seventeen Coal and carbonaceous shale samples taken from eight stratigraphic sections of the Devonian Hecla Bay and Weatherall formations in Arctic Canada, were examined using reflected light microscopy, instrumental neutron activation analysis (INAA), and inductively coupled plasma emission spectroscopy (ICPES). Samples consist of humic Coal with 62–79 vol% vitrinite, liptinite-Rich humic Coal with 42 vol% liptinite, and cannel Coal with 52–81 vol% sporinite content. Carbonaceous shale has 46–73 vol% mineral matter and canneloid shale has 30–42 vol% mineral matter as well as 22–38 vol% sporinite content. Most were deposited in areas characterized by minor channel cut-and-abandonment and lake and bay infills peripheral to distributary complexes. A fresh water environment is indicated by Boron (18–71 ppm), low inertinite (0–7.8 wt%), and high sporinite content (30–81 vol%). The ratio of Na/K versus liptinite content shows that Coals and associated sediments from the Hecla Bay Formation experienced a more rapid rate of sedimentation than the carbonaceous shales from the Weatherall Formation. The highest total REEs and LREE (La-Gd) was in the liptinite-Rich humic Coal, followed by humic Coal and carbonaceous shale. The concentration of REEs and LREEs in the cannel Coals is half of that measured in the liptinite-Rich humic Coal. The PAAS normalized for oil shales follows two different patterns: 1) the liptinite-Rich Coal samples display a sharp increase from Nd to Ho, then maintain a similar pattern up to Lu; and 2) samples of other lithologies increase from Nd to Dy, and then maintain a flat trend up to Lu. Hierarchical cluster analysis shows that canneloid and liptinite-Rich Coal exhibit the greatest similarity with each other whereas humic Coal and liptinite-Rich Coal show the greatest dissimilarity with carbonaceous shale.
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Elemental concentration and organic petrology of unique liptinite-Rich humic Coal, canneloid shale, and cannel Coal of Devonian age from Arctic Canada
Chemical Geology, 2018Co-Authors: Fariborz Goodarzi, Thomas GentzisAbstract:Abstract Seventeen Coal and carbonaceous shale samples taken from eight stratigraphic sections of the Devonian Hecla Bay and Weatherall formations in Arctic Canada, were examined using reflected light microscopy, instrumental neutron activation analysis (INAA), and inductively coupled plasma emission spectroscopy (ICPES). Samples consist of humic Coal with 62–79 vol% vitrinite, liptinite-Rich humic Coal with 42 vol% liptinite, and cannel Coal with 52–81 vol% sporinite content. Carbonaceous shale has 46–73 vol% mineral matter and canneloid shale has 30–42 vol% mineral matter as well as 22–38 vol% sporinite content. Most were deposited in areas characterized by minor channel cut-and-abandonment and lake and bay infills peripheral to distributary complexes. A fresh water environment is indicated by Boron (18–71 ppm), low inertinite (0–7.8 wt%), and high sporinite content (30–81 vol%). The ratio of Na/K versus liptinite content shows that Coals and associated sediments from the Hecla Bay Formation experienced a more rapid rate of sedimentation than the carbonaceous shales from the Weatherall Formation. The highest total REEs and LREE (La-Gd) was in the liptinite-Rich humic Coal, followed by humic Coal and carbonaceous shale. The concentration of REEs and LREEs in the cannel Coals is half of that measured in the liptinite-Rich humic Coal. The PAAS normalized for oil shales follows two different patterns: 1) the liptinite-Rich Coal samples display a sharp increase from Nd to Ho, then maintain a similar pattern up to Lu; and 2) samples of other lithologies increase from Nd to Dy, and then maintain a flat trend up to Lu. Hierarchical cluster analysis shows that canneloid and liptinite-Rich Coal exhibit the greatest similarity with each other whereas humic Coal and liptinite-Rich Coal show the greatest dissimilarity with carbonaceous shale.
Jonathan P. Mathews - One of the best experts on this subject based on the ideXlab platform.
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The characterisation of slow-heated inertinite- and vitrinite-Rich Coals from the South African Coalfields
Fuel, 2015Co-Authors: Mokone J. Roberts, Raymond C. Everson, Hein W.j.p. Neomagus, Daniel Van Niekerk, Gregory N. Okolo, Jonathan P. MathewsAbstract:Abstract The development of Coal char structures with pyrolysis has been extensively investigated but has traditionally been focused on the carboniferous Coals in the northern Hemisphere. In this investigation, the properties of pyrolysis chars generated from inertinite- and vitrinite-Rich Coals (81% and 91% mmb by volume, respectively) collected from selected South African Coalfields were determined. Chars were generated at 450, 700 and 1000 °C. The properties of Coals and chars were examined using the chemical, physical, petrographic, solid-state 13 C NMR and X-ray diffraction analytical techniques. The objective was to generate results for further studies including molecular modelling and atomistic reaction kinetics. A good correlation was found between the total maceral scan (rank) and aromaticity as the pyrolysis temperature increased, as well as between the aromaticity measurements with XRD and NMR techniques. The chemical structure of the intertinite-Rich and vitrinite-Rich chars at 700–1000 °C was remarkably similar in terms of the proximate, ultimate, total maceral scan and aromaticity values. Greater transition occurred in the vitrinite-Rich Coal, implying a thermally more activated Coal. Differences in the physical structure of the chars at these temperatures were observed in terms of the surface area using the Dubinin–Radushkevich (D–R), the Brunauer–Emmet–Teller (BET) and Langmuir methods as well the microporosity from the CO 2 adsorption method. The macerals were not distinguishable at 700–1000 °C. However, the differences in maceral composition of the Coals resulted in substantially different char forms during thermal conversion. The intertinite-Rich Coal formed more denser chars and higher proportions of thicker-walled networks (60–65% by volume). The vitrinite- Rich Coal showed higher proportions of isotropic “coke” (91–95% by volume), which contributes to a high distribution of surface area and micropores. Therefore, on a chemical level, the high temperature chars were similar. Differences existed in the physical structure at high temperatures. The physical structures, char forms and crystallite diameter ( L a ) significantly distinguished the chars at high temperatures, where L a for inertinite-Rich chars was 37.6 A compared with 30.7 A for the vitrinite-Rich chars. The L a property, in particular, played a significant role in investigations for the molecular structural properties of the inertinite- and vitrinite-Rich chars, including their reactivity behaviour with carbon dioxide gas.
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Molecular representations of Permian-aged vitrinite-Rich and inertinite-Rich South African Coals
Fuel, 2010Co-Authors: Daniel Van Niekerk, Jonathan P. MathewsAbstract:Abstract Molecular representations for two Permian-aged South African Coals, inertinite-Rich Highveld (dominated by semifusinite) and vitrinite-Rich Waterberg were constructed based on analytical data. High-resolution transmission electron microscopy (HRTEM) was used to determine the size and distribution of aromatic fringes, thereby affording the base aromatic skeleton for each Coal model. Sulfur, nitrogen, oxygen and aliphatic side chains and crosslinks were added to the aromatic skeletons according to 13 C NMR and literature data. The individual molecules were assembled into three-dimensional structures and were in agreement with experimental data (NMR, mass spectrometry and elemental analyses data). These models were structurally diverse with a molecular weight ranging from 78 to 1900 amu. The vitrinite-Rich Coal model consists of 18,572 atoms and 191 individual molecules and the inertinite-Rich Coal model consists of 14,242 atoms and 158 individual molecules. These were the first molecular representations for South African vitrinite-Rich and inertinite-Rich Coals. The inertinite-Rich Highveld Coal model was more aromatic with a larger portion of the aromatic carbons polycondensed. The vitrinite-Rich Waterberg Coal model was more aliphatic and contained more aliphatic side chains and longer aliphatic crosslinks. Although these Coals have very similar average molecular structures according to the various analytical data, subtle differences in the experimental data lead to significant structural differences in the models.
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Solvent swelling behavior of Permian-aged South African vitrinite-Rich and inertinite-Rich Coals
Fuel, 2010Co-Authors: Daniel Van Niekerk, Phillip M. Halleck, Jonathan P. MathewsAbstract:Abstract Two South African Coals similar in rank and age, but different in maceral composition, were studied using solvent swelling. Inertinite-Rich Highveld Coal (dominated by semifusinite) and vitrinite-Rich Waterberg Coal were evaluated for swelling extent and swelling rate using N-methylpyrrolidone (NMP) and CS 2 /NMP. A stop-motion videography method was developed to study individual particle swelling behavior. This method allowed observation of overshoot and climbing-type swelling, as well as swelling kinetics. Single-particle swelling experiments showed that both Coals exhibited overshoot-type and climbing-type swelling. The inertinite-Rich Coal swelled much faster (in both solvents) than the vitrinite-Rich Coal. The swelling in CS 2 /NMP was faster for both Coals. Kinetic parameters showed that solvent swelling was governed by relaxation (super-Case II relaxation) of the Coal structure. X-ray computed tomography was conducted over a 50 h swelling period in NMP for single particles of each Coal. Anisotropic swelling was observed in all the particles (swelling greater perpendicular to the bedding plane than parallel to it). The subtle changes in molecular structure, fine structural and physical differences resulted in significant differences in solvent swelling behavior.
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Structural characterization of vitrinite-Rich and inertinite-Rich Permian-aged South African bituminous Coals
International Journal of Coal Geology, 2008Co-Authors: Daniel Van Niekerk, Ronald J. Pugmire, Mark S. Solum, Paul C. Painter, Jonathan P. MathewsAbstract:Abstract Two South African Coals of the same rank and age, but different in maceral composition were subjected to extensive structural analyses. Inertinite-Rich Highveld Coal (dominated by semifusinite) and vitrinite-Rich Waterberg Coal were studied to determine structural differences and similarities. The two Coals had similar carbon content (∼ 84%, dmmf) and vitrinite reflectance (mean-maximum 0.71% for vitrinite-Rich vs. 0.75% for inertinite-Rich), but differed in hydrogen content (6.23% for vitrinite-Rich and 4.53% for inertinite-Rich). The inertinite-Rich Coal was more aromatic (86% for inertinite-Rich and 76% for vitrinite-Rich) and more polycondensed (indicated by a higher bridgehead carbon content). The inertinite-Rich Coal was structurally more ordered, with a higher degree of crystalline stacking. Both Coals had similar average aromatic cluster sizes (16 carbons for vitrinite-Rich and 18 carbons for inertinite-Rich) and number of cluster attachments (6 attachments for vitrinite-Rich and 5 attachments for inertinite-Rich). Mass spectrometry showed that both Coals consist of similar molecular weight distributions; ranging to approximately 1700 m/z with a maximum abundance of ∼ 450 m/z for the vitrinite-Rich Coal and ∼ 550 m/z for the inertinite-Rich Coal. Compared to the Argonne Premium Coals the South African vitrinite-Rich Waterberg Coal was comparable to the Coals in the high-volatile bituminous range and inertinite-Rich Highveld was closer to the medium- to low-volatile bituminous range. Both Coals were surprisingly similar in bulk characterization, although inertinite-Rich Highveld Coal was structurally more ordered, hydrogen deficient, and more aromatic.
Fariborz Goodarzi - One of the best experts on this subject based on the ideXlab platform.
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Elemental concentration and organic petrology of unique liptinite-Rich humic Coal, canneloid shale, and cannel Coal of Devonian age from Arctic Canada
Chemical Geology, 2018Co-Authors: Fariborz Goodarzi, Thomas GentzisAbstract:Abstract Seventeen Coal and carbonaceous shale samples taken from eight stratigraphic sections of the Devonian Hecla Bay and Weatherall formations in Arctic Canada, were examined using reflected light microscopy, instrumental neutron activation analysis (INAA), and inductively coupled plasma emission spectroscopy (ICPES). Samples consist of humic Coal with 62–79 vol% vitrinite, liptinite-Rich humic Coal with 42 vol% liptinite, and cannel Coal with 52–81 vol% sporinite content. Carbonaceous shale has 46–73 vol% mineral matter and canneloid shale has 30–42 vol% mineral matter as well as 22–38 vol% sporinite content. Most were deposited in areas characterized by minor channel cut-and-abandonment and lake and bay infills peripheral to distributary complexes. A fresh water environment is indicated by Boron (18–71 ppm), low inertinite (0–7.8 wt%), and high sporinite content (30–81 vol%). The ratio of Na/K versus liptinite content shows that Coals and associated sediments from the Hecla Bay Formation experienced a more rapid rate of sedimentation than the carbonaceous shales from the Weatherall Formation. The highest total REEs and LREE (La-Gd) was in the liptinite-Rich humic Coal, followed by humic Coal and carbonaceous shale. The concentration of REEs and LREEs in the cannel Coals is half of that measured in the liptinite-Rich humic Coal. The PAAS normalized for oil shales follows two different patterns: 1) the liptinite-Rich Coal samples display a sharp increase from Nd to Ho, then maintain a similar pattern up to Lu; and 2) samples of other lithologies increase from Nd to Dy, and then maintain a flat trend up to Lu. Hierarchical cluster analysis shows that canneloid and liptinite-Rich Coal exhibit the greatest similarity with each other whereas humic Coal and liptinite-Rich Coal show the greatest dissimilarity with carbonaceous shale.
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Elemental concentration and organic petrology of unique liptinite-Rich humic Coal, canneloid shale, and cannel Coal of Devonian age from Arctic Canada
Chemical Geology, 2018Co-Authors: Fariborz Goodarzi, Thomas GentzisAbstract:Abstract Seventeen Coal and carbonaceous shale samples taken from eight stratigraphic sections of the Devonian Hecla Bay and Weatherall formations in Arctic Canada, were examined using reflected light microscopy, instrumental neutron activation analysis (INAA), and inductively coupled plasma emission spectroscopy (ICPES). Samples consist of humic Coal with 62–79 vol% vitrinite, liptinite-Rich humic Coal with 42 vol% liptinite, and cannel Coal with 52–81 vol% sporinite content. Carbonaceous shale has 46–73 vol% mineral matter and canneloid shale has 30–42 vol% mineral matter as well as 22–38 vol% sporinite content. Most were deposited in areas characterized by minor channel cut-and-abandonment and lake and bay infills peripheral to distributary complexes. A fresh water environment is indicated by Boron (18–71 ppm), low inertinite (0–7.8 wt%), and high sporinite content (30–81 vol%). The ratio of Na/K versus liptinite content shows that Coals and associated sediments from the Hecla Bay Formation experienced a more rapid rate of sedimentation than the carbonaceous shales from the Weatherall Formation. The highest total REEs and LREE (La-Gd) was in the liptinite-Rich humic Coal, followed by humic Coal and carbonaceous shale. The concentration of REEs and LREEs in the cannel Coals is half of that measured in the liptinite-Rich humic Coal. The PAAS normalized for oil shales follows two different patterns: 1) the liptinite-Rich Coal samples display a sharp increase from Nd to Ho, then maintain a similar pattern up to Lu; and 2) samples of other lithologies increase from Nd to Dy, and then maintain a flat trend up to Lu. Hierarchical cluster analysis shows that canneloid and liptinite-Rich Coal exhibit the greatest similarity with each other whereas humic Coal and liptinite-Rich Coal show the greatest dissimilarity with carbonaceous shale.
Daniel Van Niekerk - One of the best experts on this subject based on the ideXlab platform.
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The characterisation of slow-heated inertinite- and vitrinite-Rich Coals from the South African Coalfields
Fuel, 2015Co-Authors: Mokone J. Roberts, Raymond C. Everson, Hein W.j.p. Neomagus, Daniel Van Niekerk, Gregory N. Okolo, Jonathan P. MathewsAbstract:Abstract The development of Coal char structures with pyrolysis has been extensively investigated but has traditionally been focused on the carboniferous Coals in the northern Hemisphere. In this investigation, the properties of pyrolysis chars generated from inertinite- and vitrinite-Rich Coals (81% and 91% mmb by volume, respectively) collected from selected South African Coalfields were determined. Chars were generated at 450, 700 and 1000 °C. The properties of Coals and chars were examined using the chemical, physical, petrographic, solid-state 13 C NMR and X-ray diffraction analytical techniques. The objective was to generate results for further studies including molecular modelling and atomistic reaction kinetics. A good correlation was found between the total maceral scan (rank) and aromaticity as the pyrolysis temperature increased, as well as between the aromaticity measurements with XRD and NMR techniques. The chemical structure of the intertinite-Rich and vitrinite-Rich chars at 700–1000 °C was remarkably similar in terms of the proximate, ultimate, total maceral scan and aromaticity values. Greater transition occurred in the vitrinite-Rich Coal, implying a thermally more activated Coal. Differences in the physical structure of the chars at these temperatures were observed in terms of the surface area using the Dubinin–Radushkevich (D–R), the Brunauer–Emmet–Teller (BET) and Langmuir methods as well the microporosity from the CO 2 adsorption method. The macerals were not distinguishable at 700–1000 °C. However, the differences in maceral composition of the Coals resulted in substantially different char forms during thermal conversion. The intertinite-Rich Coal formed more denser chars and higher proportions of thicker-walled networks (60–65% by volume). The vitrinite- Rich Coal showed higher proportions of isotropic “coke” (91–95% by volume), which contributes to a high distribution of surface area and micropores. Therefore, on a chemical level, the high temperature chars were similar. Differences existed in the physical structure at high temperatures. The physical structures, char forms and crystallite diameter ( L a ) significantly distinguished the chars at high temperatures, where L a for inertinite-Rich chars was 37.6 A compared with 30.7 A for the vitrinite-Rich chars. The L a property, in particular, played a significant role in investigations for the molecular structural properties of the inertinite- and vitrinite-Rich chars, including their reactivity behaviour with carbon dioxide gas.
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the effect of syngas on tar quality and quantity in pyrolysis of a typical south african inertinite Rich Coal
Fuel, 2014Co-Authors: Beatriz Fidalgo, Daniel Van Niekerk, Marcos MillanAbstract:Abstract The influence of gas atmosphere on the quantity and quality of tar obtained from thermochemical processing of an inertinite-Rich South African Coal is reported in this work. The effect of syngas and steam on the produced tar is addressed. Experiments were carried out in a fixed bed reactor at 30 bar and four gas atmospheres: N2, N2 + steam, H2/CO and H2/CO + steam. Tar yield increased when H2/CO was used instead of N2. Additionally, the introduction of steam to the reaction atmosphere together with N2 or H2/CO gave rise to higher tar yields than those obtained under dry N2 or H2/CO alone. Tar quality was evaluated by size exclusion chromatography, simulated distillation, gas chromatography–mass spectrometry and infrared spectrometry. Tar evolved under H2/CO atmosphere presented lighter molecular weight distribution than that obtained under N2 atmosphere. Moreover, the presence of steam in the reaction atmosphere gave rise to tars with slightly broader molecular weight distribution, shifted towards heavier species. Although all tars exhibited wide variety of aromatic compounds, tar from H2/CO experiment showed the largest degree of aromatization. The addition of steam to H2/CO atmosphere yielded tar with lower degree of aromatization and oxygenated groups. In contrast, tar with higher degree of aromatization and oxygen functional groups were obtained when steam was added to N2 atmosphere.
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Molecular representations of Permian-aged vitrinite-Rich and inertinite-Rich South African Coals
Fuel, 2010Co-Authors: Daniel Van Niekerk, Jonathan P. MathewsAbstract:Abstract Molecular representations for two Permian-aged South African Coals, inertinite-Rich Highveld (dominated by semifusinite) and vitrinite-Rich Waterberg were constructed based on analytical data. High-resolution transmission electron microscopy (HRTEM) was used to determine the size and distribution of aromatic fringes, thereby affording the base aromatic skeleton for each Coal model. Sulfur, nitrogen, oxygen and aliphatic side chains and crosslinks were added to the aromatic skeletons according to 13 C NMR and literature data. The individual molecules were assembled into three-dimensional structures and were in agreement with experimental data (NMR, mass spectrometry and elemental analyses data). These models were structurally diverse with a molecular weight ranging from 78 to 1900 amu. The vitrinite-Rich Coal model consists of 18,572 atoms and 191 individual molecules and the inertinite-Rich Coal model consists of 14,242 atoms and 158 individual molecules. These were the first molecular representations for South African vitrinite-Rich and inertinite-Rich Coals. The inertinite-Rich Highveld Coal model was more aromatic with a larger portion of the aromatic carbons polycondensed. The vitrinite-Rich Waterberg Coal model was more aliphatic and contained more aliphatic side chains and longer aliphatic crosslinks. Although these Coals have very similar average molecular structures according to the various analytical data, subtle differences in the experimental data lead to significant structural differences in the models.
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Solvent swelling behavior of Permian-aged South African vitrinite-Rich and inertinite-Rich Coals
Fuel, 2010Co-Authors: Daniel Van Niekerk, Phillip M. Halleck, Jonathan P. MathewsAbstract:Abstract Two South African Coals similar in rank and age, but different in maceral composition, were studied using solvent swelling. Inertinite-Rich Highveld Coal (dominated by semifusinite) and vitrinite-Rich Waterberg Coal were evaluated for swelling extent and swelling rate using N-methylpyrrolidone (NMP) and CS 2 /NMP. A stop-motion videography method was developed to study individual particle swelling behavior. This method allowed observation of overshoot and climbing-type swelling, as well as swelling kinetics. Single-particle swelling experiments showed that both Coals exhibited overshoot-type and climbing-type swelling. The inertinite-Rich Coal swelled much faster (in both solvents) than the vitrinite-Rich Coal. The swelling in CS 2 /NMP was faster for both Coals. Kinetic parameters showed that solvent swelling was governed by relaxation (super-Case II relaxation) of the Coal structure. X-ray computed tomography was conducted over a 50 h swelling period in NMP for single particles of each Coal. Anisotropic swelling was observed in all the particles (swelling greater perpendicular to the bedding plane than parallel to it). The subtle changes in molecular structure, fine structural and physical differences resulted in significant differences in solvent swelling behavior.
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Structural characterization of vitrinite-Rich and inertinite-Rich Permian-aged South African bituminous Coals
International Journal of Coal Geology, 2008Co-Authors: Daniel Van Niekerk, Ronald J. Pugmire, Mark S. Solum, Paul C. Painter, Jonathan P. MathewsAbstract:Abstract Two South African Coals of the same rank and age, but different in maceral composition were subjected to extensive structural analyses. Inertinite-Rich Highveld Coal (dominated by semifusinite) and vitrinite-Rich Waterberg Coal were studied to determine structural differences and similarities. The two Coals had similar carbon content (∼ 84%, dmmf) and vitrinite reflectance (mean-maximum 0.71% for vitrinite-Rich vs. 0.75% for inertinite-Rich), but differed in hydrogen content (6.23% for vitrinite-Rich and 4.53% for inertinite-Rich). The inertinite-Rich Coal was more aromatic (86% for inertinite-Rich and 76% for vitrinite-Rich) and more polycondensed (indicated by a higher bridgehead carbon content). The inertinite-Rich Coal was structurally more ordered, with a higher degree of crystalline stacking. Both Coals had similar average aromatic cluster sizes (16 carbons for vitrinite-Rich and 18 carbons for inertinite-Rich) and number of cluster attachments (6 attachments for vitrinite-Rich and 5 attachments for inertinite-Rich). Mass spectrometry showed that both Coals consist of similar molecular weight distributions; ranging to approximately 1700 m/z with a maximum abundance of ∼ 450 m/z for the vitrinite-Rich Coal and ∼ 550 m/z for the inertinite-Rich Coal. Compared to the Argonne Premium Coals the South African vitrinite-Rich Waterberg Coal was comparable to the Coals in the high-volatile bituminous range and inertinite-Rich Highveld was closer to the medium- to low-volatile bituminous range. Both Coals were surprisingly similar in bulk characterization, although inertinite-Rich Highveld Coal was structurally more ordered, hydrogen deficient, and more aromatic.
Zongqing Bai - One of the best experts on this subject based on the ideXlab platform.
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Structural changes and sodium species redistribution of a typical sodium-Rich Coal during thermal dissolution with aromatic solvents
Fuel, 2021Co-Authors: Lu Han, Peng Wang, Wu Guoguang, Xianliang Meng, Ruizhi Chu, Yongzhou Wan, Zongqing BaiAbstract:Abstract Sodium-Rich Coals are widely distributed all over the world and they are considered as suitable materials for thermal dissolution of Coals. In this work, to better understand structural changes of sodium-Rich Coals during thermal dissolution process, TG-FTIR was used to characterize weight loss and evolution of gases released from pyrolysis of a typical sodium-Rich Coal and extraction residues. Additionally, the occurrence mode of sodium species was determined by sequential chemical extraction method in order to examine sodium species redistribution. The results show that the organic oxygen content of Coal was reduced by thermal treatment, which implied that thermal dissolution tended to remove oxygen and upgrade Coal. TG-FTIR analysis also revealed that the CO2 content released from pyrolysis of extraction residues was on a lower level than that released from pyrolysis of raw Coal. During thermal dissolution, the chemical structures of raw Coal got more compact. It suggests that Coal reactivity toward further thermal conversion would be weakened. In pyrolysis process, weight loss of samples treated by tetralin was higher compared with those treated by 1-methylnaphthalene, especially at 300 °C. This difference proves that raw Coal had been pre-hydrogenated by tetralin even as low as 200–300 °C. Furthermore, tar produced in pyrolysis of samples treated by tetralin was deoxygenated by the residual tetralin and it leaded to decrease of tar-O structures, which influenced release of CO. Besides, it was observed that most sodium species were reserved in the extraction residue, as retention ratios were significantly high. At the same temperature, more exchangeable sodium species were promoted to be transformed into water-soluble ones when tetralin was used, which demonstrated that tetralin had better promotive effects on decomposition of –COO−. Along with decomposition of –COO−, exchangeable sodium species were detached from Coal matrix and transformed into other chemical forms.
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the key for sodium Rich Coal utilization in entrained flow gasifier the role of sodium on slag viscosity temperature behavior at high temperatures
Applied Energy, 2017Co-Authors: Xiaodong Chen, Lingxue Kong, Jin Bai, Xin Dai, Zongqing BaiAbstract:Abstract Tremendous sodium-Rich Coal in China has unique ash compositions, and the entrained flow gasification is one of the best choices to use sodium-Rich Coal for Coal chemical industry. The entrained flow gasifiers require smooth slag tapping for long term and safe running, but the viscosity-temperature behavior of high-sodium slags is unknown, which limits the utilization of sodium-Rich Coal. In this study, viscosity-temperature behavior of high-sodium Coal ash slags was revealed for the first time, and the parameter of slag network structure and index of slag crystallization tendency is raised for slag viscosity evaluation. The results show that Na 2 O provides O 2− ions which break Si O Si bonds and slag network structure. However, Al 3+ ions are absorbed into silicate network, acting as a network former with the ionic charge-compensation effect of Na + . The classic structural parameter (fraction of non-bridging oxygen, NBO) is modified to evaluate the high-sodium slag viscosity accurately by taking Al 3+ into account. NBO fraction decreases as Na 2 O content increases, leading to the decrease of slag viscosity. Below T liq , slags are prone to be crystalline slag with increasing Na 2 O content or glassy slag with increase in SiO 2 /Al 2 O 3 ratio (S/A). A novel index, namely glassy slag formation ability (G), is established to quantitatively evaluate the crystallization tendency of Coal ash slags. G is the ratio of activation energy for viscous flow ( E η ) to T liq . The slag will exhibit the glassy behavior when G is higher than 0.16 kJ/(mol·K). The results enhance the knowledge of viscosity-temperature behavior of high-sodium Coal ash slags and will be helpful for Coal selection and blending to avoid slag blockage in entrained flow gasification.
