TY  - JOUR
AU  - Kojić, Ivan
AU  - Bechtel, Achim
AU  - Aleksić, Nikoleta M.
AU  - Životić, Dragana
AU  - Trifunović, S.
AU  - Gajica, Gordana
AU  - Stojanović, Ksenija
PY  - 2021
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/4530
AB  - The mutual impact of low-quality lignite and high-density polyethylene (HDPE) during open system pyrolysis was investigated, aiming to improve utilization of lignite with simultaneous treatment of HDPE waste. Pyrolysis of lignite, HDPE, and their mixture (mass ratio, 1:1) was performed at temperatures 400, 450, 500, 550, and 600 °C. Initial substrates and pyrolysis products were characterized by thermogravimetric analysis (TGA), gas chromatography–mass spectrometry (GC– MS), specific carbon isotope analysis of individual hydrocarbons (δ13C), Rock-Eval pyrolysis, and ele-mental analysis. The positive synergetic effect during co-pyrolysis of lignite/HDPE mixture was observed at temperatures ≥450 °C, with the greatest being at 500 °C. The highest yield of liquid co-pyrol-ysis products with a similar composition to that of crude oils is also noticed at 500 °C. The yields of liquid and gaseous products and quality of pyrolytic products obtained by co-pyrolysis of lig-nite/HDPE mixture are notably improved compared with pyrolysis of lignite alone. On the other hand, data obtained from pyrolysis of HDPE alone indicate that it cannot be concurrent to well-developed catalytic thermal processes for polymer recycling. However, concerning the huge amount of produced HDPE, at least part of this plastic material can be reused for advanced thermal treatment of lignite, particularly in countries where this low-rank coal represents the main source of energy.
PB  - MDPI
T2  - Polymers
T1  - Study of the synergetic effect of co-pyrolysis of lignite and high-density polyethylene aiming to improve utilization of low-rank coal
VL  - 13
IS  - 5
SP  - 759
DO  - 10.3390/polym13050759
ER  - 

@article{
author = "Kojić, Ivan and Bechtel, Achim and Aleksić, Nikoleta M. and Životić, Dragana and Trifunović, S. and Gajica, Gordana and Stojanović, Ksenija",
year = "2021",
abstract = "The mutual impact of low-quality lignite and high-density polyethylene (HDPE) during open system pyrolysis was investigated, aiming to improve utilization of lignite with simultaneous treatment of HDPE waste. Pyrolysis of lignite, HDPE, and their mixture (mass ratio, 1:1) was performed at temperatures 400, 450, 500, 550, and 600 °C. Initial substrates and pyrolysis products were characterized by thermogravimetric analysis (TGA), gas chromatography–mass spectrometry (GC– MS), specific carbon isotope analysis of individual hydrocarbons (δ13C), Rock-Eval pyrolysis, and ele-mental analysis. The positive synergetic effect during co-pyrolysis of lignite/HDPE mixture was observed at temperatures ≥450 °C, with the greatest being at 500 °C. The highest yield of liquid co-pyrol-ysis products with a similar composition to that of crude oils is also noticed at 500 °C. The yields of liquid and gaseous products and quality of pyrolytic products obtained by co-pyrolysis of lig-nite/HDPE mixture are notably improved compared with pyrolysis of lignite alone. On the other hand, data obtained from pyrolysis of HDPE alone indicate that it cannot be concurrent to well-developed catalytic thermal processes for polymer recycling. However, concerning the huge amount of produced HDPE, at least part of this plastic material can be reused for advanced thermal treatment of lignite, particularly in countries where this low-rank coal represents the main source of energy.",
publisher = "MDPI",
journal = "Polymers",
title = "Study of the synergetic effect of co-pyrolysis of lignite and high-density polyethylene aiming to improve utilization of low-rank coal",
volume = "13",
number = "5",
pages = "759",
doi = "10.3390/polym13050759"
}

Kojić, I., Bechtel, A., Aleksić, N. M., Životić, D., Trifunović, S., Gajica, G.,& Stojanović, K.. (2021). Study of the synergetic effect of co-pyrolysis of lignite and high-density polyethylene aiming to improve utilization of low-rank coal. in Polymers
MDPI., 13(5), 759.
https://doi.org/10.3390/polym13050759

Kojić I, Bechtel A, Aleksić NM, Životić D, Trifunović S, Gajica G, Stojanović K. Study of the synergetic effect of co-pyrolysis of lignite and high-density polyethylene aiming to improve utilization of low-rank coal. in Polymers. 2021;13(5):759.
doi:10.3390/polym13050759 .

Kojić, Ivan, Bechtel, Achim, Aleksić, Nikoleta M., Životić, Dragana, Trifunović, S., Gajica, Gordana, Stojanović, Ksenija, "Study of the synergetic effect of co-pyrolysis of lignite and high-density polyethylene aiming to improve utilization of low-rank coal" in Polymers, 13, no. 5 (2021):759,
https://doi.org/10.3390/polym13050759 . .

TY  - JOUR
AU  - Mitrovic, Danica
AU  - Dokovic, Natasa
AU  - Životić, Dragana
AU  - Bechtel, Achim
AU  - Cvetković, Olga
AU  - Stojanović, Ksenija
PY  - 2017
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/2175
AB  - Four lignite lithotypes (matrix coal, xylite-rich coal, mixture of matrix and mineral-rich coal and mixture of matrix and xylite-rich coal), originating from the Kovin deposit, were investigated in detail. The paper was aimed to determine the main maceral, biomarker and isotopic (delta C-13) characteristics of investigated lithotypes. Based on these results the sources and depositional environment of organic matter in 4 lithotypes were established. These samples were also used as substrates for investigation of the influence of diagenetic alteration on delta C-13 signatures of biomarkers, as well as for assessment of the most convenient utilization for each lithotype. The investigated lithotypes differ in accordance with the composition of huminite macerals. Xylite-rich coal notably distinguishes from other lithotypes beacuse of the highest content of conifer resins vs. epicuticular waxes. The mixture of matrix and mineral-rich coal is characterised by the greatest contribution of algae and fungi and the most intense methanotrophic activity at the time of deposition. In all coal lithotypes diagenetic aromatisation influenced isotopic composition of individual biomarkers. Xylite-rich coal has the poorest grindability properties. However, this coal lithotype is the most suitable for fluidized bed gasification, whereas the mixture of matrix and mineral-rich coal has the lowest applicability for this process. The calorific value decreases in order: xylite-rich coal > matrix coal > mixture of matrix and xylite-rich coal > mixture of matrix and mineral-rich coal. The increase of organic carbon content and calorific value is controlled by the increase of contribution of wood vegetation vs. herbaceous peat-forming plants, as well as by stability of water table during peatification.
PB  - Serbian Chemical Soc, Belgrade
T2  - Journal of the Serbian Chemical Society
T1  - Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis
VL  - 82
IS  - 6
SP  - 739
EP  - 754
DO  - 10.2298/JSC161122030M
ER  - 

@article{
author = "Mitrovic, Danica and Dokovic, Natasa and Životić, Dragana and Bechtel, Achim and Cvetković, Olga and Stojanović, Ksenija",
year = "2017",
abstract = "Four lignite lithotypes (matrix coal, xylite-rich coal, mixture of matrix and mineral-rich coal and mixture of matrix and xylite-rich coal), originating from the Kovin deposit, were investigated in detail. The paper was aimed to determine the main maceral, biomarker and isotopic (delta C-13) characteristics of investigated lithotypes. Based on these results the sources and depositional environment of organic matter in 4 lithotypes were established. These samples were also used as substrates for investigation of the influence of diagenetic alteration on delta C-13 signatures of biomarkers, as well as for assessment of the most convenient utilization for each lithotype. The investigated lithotypes differ in accordance with the composition of huminite macerals. Xylite-rich coal notably distinguishes from other lithotypes beacuse of the highest content of conifer resins vs. epicuticular waxes. The mixture of matrix and mineral-rich coal is characterised by the greatest contribution of algae and fungi and the most intense methanotrophic activity at the time of deposition. In all coal lithotypes diagenetic aromatisation influenced isotopic composition of individual biomarkers. Xylite-rich coal has the poorest grindability properties. However, this coal lithotype is the most suitable for fluidized bed gasification, whereas the mixture of matrix and mineral-rich coal has the lowest applicability for this process. The calorific value decreases in order: xylite-rich coal > matrix coal > mixture of matrix and xylite-rich coal > mixture of matrix and mineral-rich coal. The increase of organic carbon content and calorific value is controlled by the increase of contribution of wood vegetation vs. herbaceous peat-forming plants, as well as by stability of water table during peatification.",
publisher = "Serbian Chemical Soc, Belgrade",
journal = "Journal of the Serbian Chemical Society",
title = "Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis",
volume = "82",
number = "6",
pages = "739-754",
doi = "10.2298/JSC161122030M"
}

Mitrovic, D., Dokovic, N., Životić, D., Bechtel, A., Cvetković, O.,& Stojanović, K.. (2017). Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis. in Journal of the Serbian Chemical Society
Serbian Chemical Soc, Belgrade., 82(6), 739-754.
https://doi.org/10.2298/JSC161122030M

Mitrovic D, Dokovic N, Životić D, Bechtel A, Cvetković O, Stojanović K. Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis. in Journal of the Serbian Chemical Society. 2017;82(6):739-754.
doi:10.2298/JSC161122030M .

Mitrovic, Danica, Dokovic, Natasa, Životić, Dragana, Bechtel, Achim, Cvetković, Olga, Stojanović, Ksenija, "Characterisation of lignite lithotypes from the "Kovin" deposit (Serbia) - Implications from petrographic, biomarker and isotopic analysis" in Journal of the Serbian Chemical Society, 82, no. 6 (2017):739-754,
https://doi.org/10.2298/JSC161122030M . .

TY  - JOUR
AU  - Mitrovic, Danica
AU  - Dokovic, Natasa
AU  - Životić, Dragana
AU  - Bechtel, Achim
AU  - Šajnović, Aleksandra
AU  - Stojanović, Ksenija
PY  - 2016
UR  - https://cer.ihtm.bg.ac.rs/handle/123456789/1905
AB  - The origin of the organic matter (OM) and the characteristics of the depositional environment of lignites from the Upper Miocene Kovin deposit (hosting three coal seams) of Serbia were evaluated based on petrographic data, bulk organic geochemical parameters, biomarker analysis and stable isotope geochemistry (delta C-13 of individual biomarkers). Samples were collected from four boreholes, GD-601 and GD-603 (the "A" field), and KB-79 and KB-91 (the "B" field), representing different parts of coal seams I, II, and III. Investigated lignites are typical humic coals. The OM of lignites is derived from woody vegetation and herbaceous peat-forming plants, with prevalence of the former in most samples. Peat-forming vegetation is characterized by abundant decay resistant gymnosperm (coniferous) plants, followed by a low amount of angiosperms. Lignite forming plants mostly belonged to the gymnosperm families Cupressaceae, Taxodiaceae, Phyllocladaceae and Pinaceae. Slight input of ferns, fungi and aquatic macrophyta to lignite OM is also evident. Distributions of hopanoids and isotopic compositions of these biomarkers reflect the activity of various microbial populations represented by methanotrophic-, chemoautotrophic- and heterotrophic bacteria during diagenesis. Prominent C-28 28,30-bisnorneohop-13(18)-ene was observed for the first time in the lignite extracts. According to the delta C-13 value it was probably derived from chemoautotrophic bacteria. C28 28,30-bisnorneohop-13(18)-ene could be one of the possible precursors of a series of orphan aromatic hopanoids bearing an ethyl group at C-21, via progressive aromatization. Peatification proceeded in a fresh water environment under variable redox conditions, from anoxic to slightly oxic. All three coal seams are heterogeneous. The lower parts of the coal seams represent a topogenous fresh water peat mire with open water areas, which was subjected to inundations. The upper parts of coal seams represent a wet forest swamp with relatively stable conditions. Despite the observed variations in all three coal seams, the mean values of petrographic and organic geochemical parameters suggest general increasing of wetness and establishment of more stable conditions from seam III to seam I. Maceral and biomarker data indicate that rapid flooding of the bogs stopped peat growth in all three coal seams. Relatively frequent variations in all three coal seams, followed by repetition of lignite characteristics depict well the pronounced seasonality e.g. short term cycles of the climate during Late Miocene in investigated area.
PB  - Elsevier
T2  - International Journal of Coal Geology
T1  - Petrographical and organic geochemical study of the Kovin lignite deposit, Serbia
VL  - 168
SP  - 80
EP  - 107
DO  - 10.1016/j.coal.2016.07.008
ER  - 

@article{
author = "Mitrovic, Danica and Dokovic, Natasa and Životić, Dragana and Bechtel, Achim and Šajnović, Aleksandra and Stojanović, Ksenija",
year = "2016",
abstract = "The origin of the organic matter (OM) and the characteristics of the depositional environment of lignites from the Upper Miocene Kovin deposit (hosting three coal seams) of Serbia were evaluated based on petrographic data, bulk organic geochemical parameters, biomarker analysis and stable isotope geochemistry (delta C-13 of individual biomarkers). Samples were collected from four boreholes, GD-601 and GD-603 (the "A" field), and KB-79 and KB-91 (the "B" field), representing different parts of coal seams I, II, and III. Investigated lignites are typical humic coals. The OM of lignites is derived from woody vegetation and herbaceous peat-forming plants, with prevalence of the former in most samples. Peat-forming vegetation is characterized by abundant decay resistant gymnosperm (coniferous) plants, followed by a low amount of angiosperms. Lignite forming plants mostly belonged to the gymnosperm families Cupressaceae, Taxodiaceae, Phyllocladaceae and Pinaceae. Slight input of ferns, fungi and aquatic macrophyta to lignite OM is also evident. Distributions of hopanoids and isotopic compositions of these biomarkers reflect the activity of various microbial populations represented by methanotrophic-, chemoautotrophic- and heterotrophic bacteria during diagenesis. Prominent C-28 28,30-bisnorneohop-13(18)-ene was observed for the first time in the lignite extracts. According to the delta C-13 value it was probably derived from chemoautotrophic bacteria. C28 28,30-bisnorneohop-13(18)-ene could be one of the possible precursors of a series of orphan aromatic hopanoids bearing an ethyl group at C-21, via progressive aromatization. Peatification proceeded in a fresh water environment under variable redox conditions, from anoxic to slightly oxic. All three coal seams are heterogeneous. The lower parts of the coal seams represent a topogenous fresh water peat mire with open water areas, which was subjected to inundations. The upper parts of coal seams represent a wet forest swamp with relatively stable conditions. Despite the observed variations in all three coal seams, the mean values of petrographic and organic geochemical parameters suggest general increasing of wetness and establishment of more stable conditions from seam III to seam I. Maceral and biomarker data indicate that rapid flooding of the bogs stopped peat growth in all three coal seams. Relatively frequent variations in all three coal seams, followed by repetition of lignite characteristics depict well the pronounced seasonality e.g. short term cycles of the climate during Late Miocene in investigated area.",
publisher = "Elsevier",
journal = "International Journal of Coal Geology",
title = "Petrographical and organic geochemical study of the Kovin lignite deposit, Serbia",
volume = "168",
pages = "80-107",
doi = "10.1016/j.coal.2016.07.008"
}

Mitrovic, D., Dokovic, N., Životić, D., Bechtel, A., Šajnović, A.,& Stojanović, K.. (2016). Petrographical and organic geochemical study of the Kovin lignite deposit, Serbia. in International Journal of Coal Geology
Elsevier., 168, 80-107.
https://doi.org/10.1016/j.coal.2016.07.008

Mitrovic D, Dokovic N, Životić D, Bechtel A, Šajnović A, Stojanović K. Petrographical and organic geochemical study of the Kovin lignite deposit, Serbia. in International Journal of Coal Geology. 2016;168:80-107.
doi:10.1016/j.coal.2016.07.008 .

Mitrovic, Danica, Dokovic, Natasa, Životić, Dragana, Bechtel, Achim, Šajnović, Aleksandra, Stojanović, Ksenija, "Petrographical and organic geochemical study of the Kovin lignite deposit, Serbia" in International Journal of Coal Geology, 168 (2016):80-107,
https://doi.org/10.1016/j.coal.2016.07.008 . .