Effects of oxidative weathering on the composition of organic matter in coal and sedimentary rock

Tamamura, Shuji; Ueno, Akira; Aramaki, Noritaka; Matsumoto, Hiroyuki; Uchida, Kagemi; Igarashi, Toshifumi; Kaneko, Katsuhiko

doi:10.1016/j.orggeochem.2015.01.006

Cited by 31 publications

(15 citation statements)

References 84 publications

(122 reference statements)

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“…Most of the previous work reported the structural changes C-C and C-H bond, changes in caking properties, petrographic compositions, coke properties (Banerjee et al 2000;Xia and Yang 2014;Cimadevilla et al 2005;Smędowski and Piechaczek 2016;Tamamura et al 2015;Kříbek et al 2017) etc. in weathered coal.…”

Section: Introductionmentioning

confidence: 99%

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

Aich

Nandi

Bhattacharya

2018

Int J Coal Sci Technol

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An open air stockpile of conical shape was formed with 3.5 m base diameter and 5 m height using 500 tons of-200 mm size ROM thermal coal on a concrete floor. Coal sample from the stockpile were collected at 30 days interval for analysis of various chemical properties like; proximate analysis, ultimate analysis, gross calorific value (GCV) and various combustion related properties such as ignition temperature, peak temperature, burnout temperature, maximum combustion rate, ignition index, burnout index, combustion performance index and combustion rate intensity index. Experimental results show that, due to weathering of coal fixed carbon decreased from 35.6% to 19.9%, elemental carbon (C) decreased from 46.6% to 28.6%, hydrogen (H) decreased from 3.3% to 2.9% and GCV decreased by up to 55% of original value during 330 days of storage of coal in an open atmosphere. Ash content of coal increased form 29.2% to 46.6% due to loss of combustibles. Sulfur (S) of coal was found to get increased from 0.33% to 1.08% during storage. The activation energy of coal combustion increased from 22 kJ/mol to 54 kJ/mol. Variation in combustion parameters signifies that weathering has significant negative impact on coal combustion properties as coal become difficult to ignite.

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Section: Introductionmentioning

confidence: 99%

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

Aich

Nandi

Bhattacharya

2018

Int J Coal Sci Technol

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“…Indeed, the calculated CEC contribution by oxidised kerogen corresponds to CEC values measured in naturally oxidised lignite and coal (3.3 meq/g; Skodras et al, 2014), soil OM (1.4-10.0 meq/g Kaiser et al, 2008 and references therein), and humic acids present in marine sediments (~3 meq/g; Rashid, 1969). The latter compound was also found as a product of oxidisation in bituminous coals and shales (Kurková et al, 2004;Tamamura et al, 2015), and might have as well be generated by kerogen in the studied black shales. Natural and artificial OM oxidation produce a common trend of decreased HI with simultaneous OI increase (Fig.…”

Section: Apparent Cecmentioning

confidence: 64%

“…To track OM changes during weathering, it was assumed at this point that if oxidative weathering caused an increase in the number of COOH and OH functional groups in kerogen, free fatty acids and concentration of alcohols/phenols should be also elevated (cf. Tamamura et al, 2015). Since the Permian weathering, the studied shales were buried at least 2.5 km deep, therefore, the weathered kerogen underwent secondary thermal maturation (Belka, 1990;cf.…”

Section: Apparent Cecmentioning

confidence: 99%

“…It is quite possible that OM compounds containing such oxygen groups originating from sedimentary and diagenetic processes undergo decomposition during weathering with a rate proportional to other OM compounds. In contrast to specific recalcitrant OM species that become oxidised (Tamamura et al, 2015), their content likely decreases with TOC during weathering, following the pattern of pyrolysable hydrocarbons (S2) and TOC (cf. Georgiev et al, 2012;Skodras et al, 2014).…”

Section: Apparent Cecmentioning

confidence: 99%

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Binding of heavy metals by oxidised kerogen in (palaeo)weathered black shales

Derkowski

Marynowski

2018

Chemical Geology

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Citation style: Derkowski Arkadiusz, Marynowski Leszek. (2018). Binding of heavy metals by oxidised kerogen in (palaeo)weathered black shales. A B S T R A C TSub-aerial weathering of black shales drives the gradual leaching of sulphur-and organic-bound heavy metal elements, which are usually abundant in these rocks due to depositional conditions. The formation of oxygen functional groups in kerogen, however, can lead to an opposing mechanism -metal adsorption and binding, similar to a process common in soils. An increase in cation exchange capacity (CEC) measured previously using metal complexes on black shales oxidised under laboratory conditions implies that the same phenomenon may occur in a naturally oxidised black shale. This idea was tested on a unique, well-developed and -preserved Permian palaeoweathering profile containing two neighbouring but diverse black shales from the Devonian/ Carboniferous boundary in the Holy Cross Mountains (Poland).In the studied black shale beds, the oxygen groups formed in kerogen in the partially-weathered zone were found to be responsible for significant changes in adsorption properties measured using hexamminecobalt(III) and Cu(II)-triethylenetetramine cations, which are common probes for CEC. Compared to a pristine part of black shales, the partially weathered zone was depleted of total organic carbon (TOC), sulphur, and sulphur-and organic-bound metals, and highly enriched in Cu, which is generally present in low levels in the nascent shales.In the partially weathered zone, where TOC content is reduced, apparent CEC values surpass the CECs predicted from the contents and structures of clay minerals, and correlate linearly with the content of oxygen groups developed during weathering. The adsorption properties of carboxyl groups in the oxidised kerogen are suggested as being responsible for the syn-or post-weathering enrichment in Cu caused by the remobilisation of older Cu-sulphide ores present in the area. As opposed to natural weathering, aggressive oxidation, e.g. under laboratory conditions produces a high proportion of cross-linked oxygen groups that do not participate in metal cation adsorption. The CEC values of artificially oxidised samples reached a limit corresponding to those of naturally oxidised shales.Editor: Michael E. Böttcher exchange capacity (CEC) of soils (Parfitt et al., 1995;Kaiser et al., 2008;Rengasamy and Churchman, 1999) and oxidised low-rank coals (Skodras et al., 2014). In extreme cases, it is the oxidised black carbon formed via incomplete combustion of vegetation or fossil fuels that is responsible for high CEC levels in soils (Liang et al., 2006;Cheng et al., https://doi.

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“…Since hydraulic fracturing technology represents a potential hazard to the ecological system and it is not suitable for the shale gas reservoirs with limited water resources, oxidation has been proposed as an alternative way to replace hydraulic fracturing technology. Organic-rich shale has high chemical reactivity and it is sensitive to oxidation reactions [14,15]. Chen et al have used a high-temperature combustion method to remove organic matter in order to improve the shale matrix diffusivity [16,17].In addition to high-temperature oxidation, low-temperature oxidation has also been applied to improve shale effective porosity in experiments.…”

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confidence: 99%

H2O2-Enhanced Shale Gas Recovery under Different Thermal Conditions

Lei

Wang

et al. 2019

Energies

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The permeability of tight shale formations varies from micro-Darcy to nano-Darcy. Recently, hydrogen peroxide (H2O2) was tested as an oxidizer to remove the organic matter in the rock in order to increase shale permeability. In this study, shale particles were reacted with hydrogen peroxide solutions under different temperature and pressure conditions in order to “mimic” underground geology conditions. Then, low-temperature nitrogen adsorption and desorption experiments were conducted to measure the pore diameters and porosity of raw and treated shale samples. Moreover, scanning electron microscopy (SEM) images of the samples were analyzed to observe pore structure changes on the surface of shale samples. From the experiments, it was found that the organic matter, including extractable and solid organic matter, could react with H2O2 under high temperature and pressure conditions. The original blocked pores and pore throats were reopened after removing organic matter. With the increase of reaction temperature and pressure, the mean pore diameters of the shale samples decreased first and then increased afterwards. However, the volume and Brunauer–Emmett–Teller (BET) surface areas of the shale particles kept increasing with increasing reaction temperature and pressure. In addition to the effect of reaction temperature and pressure, the pore diameter increased significantly with the increasing reaction duration. As a result, H2O2 could be used to improve the shale permeability.

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Effects of oxidative weathering on the composition of organic matter in coal and sedimentary rock

Cited by 31 publications

References 84 publications

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

Effect of weathering on physico-chemical properties and combustion behavior of an Indian thermal coal

Binding of heavy metals by oxidised kerogen in (palaeo)weathered black shales

H2O2-Enhanced Shale Gas Recovery under Different Thermal Conditions

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