FTIR Study of Pure Vitrains and Associated Coals

Abstract

URA 724 est intégrée dans l'UMR6113 ISTO CNRS Université d'OrléansInternational audienceA semiquantitative analysis of the infrared spectra from 650 to 4000 cm-' of six vitrains and the coals associated with three of them is presented. This analysis supplies information on the concentration of several functionalities in the samples. Relationships between infrared data and several parameters (carbon content, vitrinite reflectance, pyrolysis data) are discussed. The results thus obtained contribute to a better understanding of vitrinite structure. They also help to explain the discrepancies between rank parameters obtained from chemical analyses and those determined by petrographic measurements. The comparison between the infrared data of the Cretacic-Albian vitrain from Teruel (Spain) and its associated coal reveals the unusual chemical composition of this vitrain. The infrared analysis of this vitrain and the vitrian from Asturias (Jurassic-Malm) shows unusual features in comparison with “normal” coals. The intensity of the aliphatic peaks relative to the aromatic (A factor) in these vitrains is characteristic of immature samples, closer to those of type I1 kerogens than type 111. This result agrees with the perhydrous character of these samples and helps to explain volatile matter and pyrolysis data. However, for the vitrain from Asturias, the intensity of the bands due to aromatic hydrogen and the ratio between aromatic and aliphatic hydrogen are consistent with a stage of evolution that is higher than the diagenesislcatagenesis transition in agreement with other chemical and petrographic data. In the vitrains from Asturias and Teruel an absorption band at 1500 cm-l is assigned to aromatic C=C bonds. In these vitrains, the band centered at 815 cm-l is the most prominent in the 900-700 cm-l region. These spectral features are unusual in coal spectra, but they seem to be characteristic of perhydrous coals

Control of the chemical structure of perhydrous coals; FTIR and Py-GC/MS investigation

“…Aromaticity apparently agrees with the vitrinite reflectance values ( Table 1). However, a comparison of the Har/Hal values for the perhydrous samples with the data from non-perhydrous coals [29], depicted in Fig. 4b, shows in all cases higher values of Har/Hal than those expected for the values of vitrinite reflectance.…”

“…Thus, any differences in grinding or weight between pellets are minimised. All of the absorbance spectra were recorded on a Perkin-Elmer 1750 and analysed following procedures described by Iglesias et al [29].…”

“…The results from the semiquantitative analysis are shown in Table 3. The spectra and data for the TCV and AJV samples previously reported [29] are also presented here for comparative purposes. It can be seen that the spectra from the UCV and WJVh/WJVl samples closely resemble those reported for the Utah and Whitby jets, respectively [12 and 36].…”

Fuel-oils from co-pyrolysis of scrap tyres with coal and a bituminous waste. Influence of oven configuration

“…Although various indices derived from FTIR spectra have been used to evaluate the chemical characteristics of fuels [29][30][31], only two described in Table 1 have been employed in the present research work: 1. Ar/Al which gives an indication of the degree of aromaticity and 2. the index which indicates the ratio of oxygenated functional groups in the oils.…”

Characterization of Tars from the Thermal Processing of Baganuur and Tavan Tolgoi Coals from Mongolia, Using SEC, UV-F, IR and Mass Spectrometry

“…The band at 3030 cm −1 is assigned to the aromatic CH stretching while the bands at 2920 and 2850 cm −1 are assigned to asymmetric and symmetric modes of aliphatic CH stretching respectively. Thus the integrated areas of these two spectral ranges are often used in estimating the aromaticity of a carbonaceous material [42,43]. The H ar and H al are the integrated area of the of the IR absorbance at 3100 -3000 cm −1 and 3000 -2700 cm −1 respectively.…”