Paramagnetic Resonance, a New Property of Coal-like Materials

Uebersfeld, J.; Étienne, A.; Combrisson, J.

doi:10.1038/174614a0

Cited by 148 publications

(46 citation statements)

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“…Electron spin resonance spectroscopy (ESR) has been used in many investigations since the discovery of free radicals in coal by Uebersfeld et al [10]. The electron spin resonance spectroscopy has been used to describe the concentration and chemical structure of free radicals in different coals as reported in the previous studies [10e13].…”

Section: Introductionmentioning

confidence: 99%

Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

Trubetskaya

Jensen

et al. 2016

Biomass and Bioenergy

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a b s t r a c tThe concentration and type of free radicals from the decay (termination stage) of pyrolysis at slow and fast heating rates and at high temperatures (above 1000 C) in biomass char have been studied. A roomtemperature electron spin resonance spectroscopy study was conducted on original wood, herbaceous biomass, holocelluloses, lignin and their chars, prepared at high temperatures in a wire mesh reactor, an entrained flow reactor, and a tubular reactor. The radical concentrations in the chars from the decay stage range up between 7$10 16 and 1.5$10 18 spins g À1. The results indicated that the biomass major constituents (cellulose, hemicellulose, lignin) had a minor effect on remaining radical concentrations compared to potassium and silica contents. The higher radical concentrations in the wheat straw chars from the decay stage of pyrolysis in the entrained flow reactor compared to the wood chars were related to the decreased mobility of potassium in the char matrix, leading to the less efficient catalytic effects of potassium on the bond-breaking and radical re-attachments. The high Si levels in the rice husk caused an increase in the char radical concentration compared to the wheat straw because the free radicals were trapped in a char consisting of a molten amorphous silica at heating rates of 10 3 e10 4 K s À1. The experimental electron spin resonance spectroscopy spectra were analyzed by fitting to simulated data in order to identify radical types, based on g-values and line widths. The results show that at high temperatures, mostly aliphatic radicals (g ¼ 2.0026e2.0028) and PAH radicals (g ¼ 2.0027e2.0031) were formed.

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Section: Introductionmentioning

confidence: 99%

Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

Trubetskaya

Jensen

et al. 2016

Biomass and Bioenergy

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“…The consequences of such a radical hydrogen transfer would be essentially the same as those of the description of pyrolysis given here). The free radicals formed by reaction 2 have been observed (8). Some radicals recombine to yield extended structures which eventually form coke or char together with gas.…”

Section: Vitrinite---- Intermediates ----Coke+ Gasmentioning

confidence: 96%

Fundamentals of Coal Pyrolysis and Liquefaction

Gaines

1992

Clean Utilization of Coal

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“…Early studies on free radical detection in coal [3] and smoky quartz [4] indicated that ESR could be applied to geological materials. An additive artificial irradiation was made to obtain the accumulated dose.…”

Section: Introductionmentioning

confidence: 99%

“…ESR dating has been extended to shells in sediments, corals in marine terraces [11][12][13] and to planktonic foraminifera in deep-sea sediment cores [14,15]. Secondary deposits of NaHC0 3 and NaCI in arid lake sediments [16] and of marine gypsum [17] have also been studied.…”

Section: Introductionmentioning

confidence: 99%

ESR and ESR microscopy in geosciences and radiation dosimetry

Ikeya

1994

Appl. Magn. Reson.

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ESR and its microscopic imaging (microscopy) have found new applications in interdisciplinary fields related with geosciences and with radiation dosimetry. Geological, archaeological and forensic dating has been made through paleo-dosimetry of natural radiation and chemical reactions of both radical formation and valency changes. ESR microscopy, especially the simple scanning method has a potentiality to be used in various fields. New applications of ESR are briefly reviewed with some examples.

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Paramagnetic Resonance, a New Property of Coal-like Materials

Cited by 148 publications

References 1 publication

Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

Characterization of free radicals by electron spin resonance spectroscopy in biochars from pyrolysis at high heating rates and at high temperatures

Fundamentals of Coal Pyrolysis and Liquefaction

ESR and ESR microscopy in geosciences and radiation dosimetry

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