Energy &Fuels 1994,8, 1417-1424
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Influence of Resinite on Huminite Properties I. Suarez-Ruiz,**tA. Jimknez,? M. J. Iglesias,t F. Laggoun-Defarge,$and J . G. Pradot Instituto Nacional del Carbbn (C.S.I.C.), Ap. Co. 73, 33080-Oviedo, Spain, and Laboratoire de aologie de la Matikre Organique, SCdimentation et DiagenLse de la MatiLre Organique, U A 724 d u CNRS, UniversitC d'orlhans, Btitiment Giosciences, Rue St. Amand, 45067-0rlhans, Cedex 2, France Received May 3, 1994@
Vitrain from Teruel (northeastern Spain) constitutes a good example of the influence of liptinitic compounds on properties of huminite. The resinization of the humotelinitic tissue of this lithotype has provoked an important suppression of its reflectance giving it a strongly perhydrogenated character. Even though it later undergoes a diagenetic evolution, neither of the conventional rank parameters reflects the real degree of maturation reached by this vitrain because of the important alteration of its properties. Only its fluorescence features and the FTIR study make it possible to detect this resinization and to approach the degree of maturation from the presence of exudates in its structure. The most important conclusion is that properties of huminitehitrinite are strongly dependent not only on the amount and type of liptinite but also on its distribution and interrelation between the two maceral groups.
Introduction Causes which can originate the suppression of the vitrinite reflectance of a particular coal or organic sediment are diverse and they have recently been reviewed by Barker.l In particular, the influence of hydrogen content on vitrinite reflectance has been discussed in many papers. One of the conclusions was that perhydrogenated vitrinites are distinguished by relatively low reflectance values2 in relation to the real degree of maturity that they could have acquired throughout their geological history. In these cases reflectance becomes invalid as a rank parameter. In addition to the more or less suppressed reflectances and high H content, perhydrous vitrinites present strong discrepancies and anomalies in their chemical and petrographic parameters related to the composition and degree of maturation when they are compared with those of vitrinites from normal series of evolution. Factors which may originate this perhydrogenated character are diverse, although not all of them have been exhaustively studied. Some of them relate the high hydrogen content in vitrinites to the special conditions of their depositional environment (anoxic or sapropelic sedimentary e n v i r ~ n m e n t ) . In ~ *other ~ cases vitrinites are enriched in H because of phenomena of impregnatiodadsorption of resinous, bituminous, or petroleum-like substance^.^*^-^ Other recognized causes
* Author to whom correspondence should be sent. +
Instituto Nacional de Carb6n.
* Universit6 d'Orl6ans.
@Abstractpublished inAdvance ACS Abstracts, September 15,1994. (1)Barker, Ch. E. Soc. Org. Pet. Newslett. 1991,8, 8. (2) Teichmuller, M. In Coal and Coal-Bearing Strata: Recent Aduances; Scott, A. C., Ed.; Geological Society, Special Pub. No. 32; Blackwell Scientific: London, 1987; p 127. (3) Newman, J; Newman. N. A. New Zealand J . of Geol. Geophys. 1982,25,233. (4) Stach, E.;Mackowsky, M. Th.; Teichmuller, M.; Taylor, B. H.; Chandra, D.; Teichmuller, R. Coal Petrology; 3th ed.; Gebruder Borntraeger: Stuttgart, 1982;535 pp. (5) Hutton, A. C.; Henstridge, D. A. Fuel, 1985,64,546.
0887-0624/94/2508-1417$04.50/0
of the suppression of vitrinite reflectance are related to the relative abundance of specific liptinitic compounds in the rock.8-12 In this context, the objective of this work has been to determine the origin of the perhydrogenated character and the consequent reflectance suppression of a vitrain in relation to the associate coal (whole coal) in the same seam as well as to determine the influence of this hydrogenated character on its composition and its later diagenetic evolution. Both the vitrain and the associate coal are from the Cretaceous (Albian) coal Basin of Teruel (northeastern Spain) which were originated in a delta-estuary depositional envi1-0nment.l~The problem of low reflectance values in certain coals from this basin has already been mentioned by Querol et al.13
Sampling and Analytical Procedures In the Teruel Coal Basin significant levels of vitrains have been found in some of their coal beds. Normally, these vitrains are wood-drifted by streams and then deposited in the coal sediments. They stand out of the dull coal bed because of their shiny appareance. They often have a lenticular morphology, reaching lengths of 60 cm and a thickness of 15 cm. In this work two representative samples of the number 4 seam were taken from the underground Concepcion Mine. One of them comes from the pure vitrain (TV sample) located at the top of the seam and the second one (TAC sample) corresponds to the whole coal (clarain lithotype) of seam (6) Teichmuller, M. Int. J . Coal Geol. 1992,20,1.
(7) Suirez-Ruiz, I.; Iglesias, M. J.; Jimbnez, A,; Laggoun-Defarge, F.; Prado, J. G. In: Reevaluation of Vitrinite Reflectance as a Maturity Parameter: Petrologic, Kinetic and Geochemical Factors; ACS Symposium Series; American Chemical Society: Washington,DC, in press. (8) Hutton, A.; Cook, A. Fuel 1980,59, 711. (9) Kalkreuth, W. Bull. Can. Pet. Geol. 1982,30,112. (10)Price, L. C.; Barker, Ch. E. J . ofpet. Geol. 1985,8, 59. (11) Wenger, LL. M.; Baker, D. R. Org. Geochem. 1987,11, 411. (12) Raymond, A. C.; Murchison, D. G. Fuel 1991,70, 155. (13) Querol, X.;Fernhdez Turiel, J. L.; L6pez Soler, A.; Hagemann, H. W.; Dehmer, J.; Juan, R.; Ruiz, C. Int. J. of Coal Geol. 1991,18, 327.
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1418 Energy & Fuels, Vol. 8, No. 6, 1994
Suarez-Ruiz et al.
Table 1. Maceral Analysis number 4 adjacent to vitrain. Both samples were taken according t o standard sampling procedures and were imcomponents (% vol., mm0 TV sample TAC sample mediately stored under argon atmosphere to avoid alteration humotelinite 94.8 14.0 phenomena. Subsequently they were prepared for petrogelinite 65.1 graphic and chemical analyses. phlobaphinite 1.8 Microscopic characterization was performed through machumodetrinite 1.4 era1 analysis, random reflectance, and fluorescence measuresporinite 1.4 ments. resinite 3.4 0.4 fusinite Maceral analysis and measurements of random reflectance 14.0 semifusinite 3.0 for both samples were carried out on a MPV-Combi Leitz inertodetrinite 0.7 apparatus (with a standard l o x eyepiece and a 1 . 2 5 ~tube factor) by means of reflected white light using oil immersion objectives (32x) in accordance with IS0-7404/3 and ISO-74046 The soluble organic fraction was obtained by treating each procedures.14J5 Moreover, for vitrain, specific measurements sample with chloroform in an ultrasound bath at room of reflectance were carried out on some of its differentiated temperature. Asphaltenes were previously eliminated from components. the extract using n-heptane and then fractionated by liquid Fluorescence characterization was performed on a n MPV chromatography. The content of saturated and aromatic I11 Leitz employing water immersion and UV and blue light. hydrocarbons as well as resins was determined by successive Spectral analysis and alteration measurements (after 30 min dilutions with n-heptane and n-heptane:toluene (2:l ratio). exposure) were made following the procedure previously The textural properties were carried out by measuring real described by Martinez et a1.16 These measurements were and apparent densities as well as porosity. The apparent performed on huminite, resinite, and exudatinite. The fluodensity was determined using mercury porosimetry while the rencence parameters used in this work were the quotients QFdetermination of the real density was carried out using a glass 535, Q650/500, the emission flux (F)and ,lmax(95%). picnometer. Helium was the picnometric fluid employed. Chemical characterization (proximate and ultimate analyPorosity was calculated on the basis of density data. ses, sulfur forms, and calorific value) was made in accordance with international standard procedures, ISO-589, ISO-1171, Results ISO-562, ISO-925, ISO-157, and IS0-1928.17-22The C, H, N, and total S content was determined using a LECO CHN 600 From the macroscopic point of view the TV sample and LECO SC 132 apparatus and the oxygen content was shows the typical features described for this lithotype.28 calculated by subtraction. Its color is bright black. It is clean by touch and fragile Pyrolysis characterization was carried out on a Rock-Eva1 because it easily breaks. The formation of fractures or pyrolyzer (performed in accordance with E ~ p i t a l i e ) . Spe~~,~~ cracks on its surface is typical. This vitrain can easily cific parameters in relation with type, composition, and be altered by short exposure to air and the formation evolution of both samples were considered. of sulfate efflorescence on its surface is then clearly The functional groups were studied in both solid samples visible. The associate coal (TAC sample) is also a humic and their oils obtained through the Gray-King assay techbanded coal in which dull and bright microlayers n i q ~ e by , ~ FTIR. ~ The preparation of solid samples was performed with the aid of the conventional p r o ~ e d u r e For . ~ ~ ~ ~ ~alternate, giving it a dirty and dull appearance (clarain oils, the preparation procedure has been described in Suarezlithotype28). Likewise, it is easily altered. Ruiz et aL7 All the absorbance spectra were recorded on a Petrographic Characterization. Results from the Perking Elmer 1750 spectrometer coadding 25 interferograms maceral analyses, reflectance measurements, and fluoobtained at a resolution of 4 cm-l. Each spectrum was rescence determinations for both samples are presented corrected for scattering and then calibrated to 1mg (daf)/cm2. (14) Methods for the petrographic analysis of bituminous coal and anthracite.Part 3: Method of determining maceral group composition. International Standard IS0 74043, 1st ed., 1984,4 pp. (15)Methods for the petrographic analysis of bituminous coal and anthracite. Part 5: Method of determining microscopically the reflectance of vitrinite. International Standard IS0 7404/5, 1st ed., 1984, 13 PP. (16) Martinez, L.; Pradier, B.; Bertrand, P. C.R. Acad. SOC.Paris,
1987,304,SBr. IIU9, 441.
(17) Hard coal. Determination of total moisture. International Standard ISO-589,2nd ed., 1981,6 pp. (18) Solid mineral fuels. Determination of ash. International Standard ISO-1171, 2th ed., 1981, 2 pp. (19)Hard coal and coke. Determination of volatile matter content. International Standard ISO-562, 2nd ed., 1981, 5 pp. (20) Solid mineral fuels. Determination of carbon dioxide content. Gravimetric method. International Standard ISO-925,2nd ed., 1980, 3 PP.
(21) Hard coal. Determination of forms of sulphur. International Standard ISO-157, 1st ed., 1975, 10 pp. (22) Solid mineral fuels. Determination of gross calorific value by the calorimetric bomb method and calculation of net calorific value. InternationalStandard ISO-1928, 1st ed., 1976, 14 pp. (23) Espitalie, J.; Madec, M.; Tissot, R.; Mening, J. J.; Leplat, P. Proc. 9th Annu. Ofshore Tech. Conf., Houston, TX 1977,439. (24) Espitalie, J.; Laporte, J. L.; Madec, M.; Marquis, F.; Leplat, P.; Paulet, J.; Boutefeu, A. Rev. de Z'lnst. Franqais P&. 1977,32,23. (25) Coal. Determination of coking power. Gray-King Assay. International Standard ISO-502, 2th Ed., 1981, 9 pp. (26) Solomon, P. R.; Hamblen, D. G.; Carangelo,R. M. In Coal and Coal Products: Analytical Characterization Techniques; Fuller Jr., E. L., Ed.; ACS Symposium Series. No. 205; American Chemical Society; Washington, DC, 1982, p 77. (27) Painter, P.; Starsinic, M.; Coleman, M. In Fourier Transform Infrared Spectroscopy; Ferraro, J. R., Basile, L., Eds.; Academic Press: Orlando, FL, 1985, Vol. 4, p 169.
in Tables 1, 2 and 3. TV Sample. The vitrain is composed of humotelinite (Table 1)which appears as a porous vegetable cellular tissue showing different degrees of gelification. With a low degree of gelification (Figure la), the cell walls of this tissue are neat and sharp, it being possible to differentiate a light section with 0.24% of reflectance (Table 2) and a dark section, thick with lower reflectance (0.20%). When the gelification is considerable, the humotelinite adopts a relatively homogeneous appearance (Figure lb). Humotelinite presents a low intensity of fluorescence, as shown by the F value with a maximum of intensity at 530 nm (Table 3). In some cases the fluorescence is only limited to the dark section of the cell wall of the tissue. The spectral alteration (Table 3) is positive during the first five minutes (slight positive fading) and then constant. The chromatic derivate QF (dQF in Table 3) is also constant. When the humotelinite has a low degree of gelification, cell cavities of different sizes can be observed (Figure 1). These cavities mainly appear t o be filled with resinite. Optically, this compound can be divided into dark and light resinite (Figure lc,d) which exhibit different reflectance values (Table 2). In most cases light resinite is difficult to separate from the dark (28) International Handbook for Coal Petrology; ICCP Glossary, 2th ed., CNRS: Paris, 1975, Vol. 1,2, and 3.
Influence of Resinite on Huminite Properties
Energy & Fuels, Vol. 8, No. 6,1994 1419
H
25 microns Figure 1. Photomicrographs with some of the compounds identifiedin the vitrain (Tvsample)using white light and oil immersion. (a) Humotelinite (HM) with low degree of gelification.D W dark cell wall, LW light cell wall. (b) Humotelinite (HM) with high degree of gelification in which are still visible the light cell walls (LW)and the dark cell walls (DW). (c) Humotelinite(HM) with cell cavities filled with dark resinite (DR). (d) Humotelinite (HM) with cell cavities filled with light resinite (LR).
section of the cell wall because of the gradual transition between them, their fluorescence and reflectance values being similar. Dark resinite has different optical properties (Tables 2 and 3). It presents a strong yellow fluorescence with high F values. The fluorescence alteration shows a negative alteration during the first five minutes (slight negative fading) for the Fb parameter while it is constant for Fr. The chromatic derivate QF (dQF in Table 3) is also constant. It must be pointed out that resinite has only been observed as a figurated compound and never in the form of impregnations on humotelinite. In a few cases cell cavities of humotelinite appear to
be filled with phlobaphinite. This component is very rare (Table l), presents the highest reflectance values (Table 2), and is nonfluorescent. The last compound to be identified was exudatinite uncounted in maceral analysis (achieved in white light). Its fluorescence characteristics are given in Table 3. The random reflectance measured in humotelinite is low, as shown in Table 2. TAC Sample. The associate coal to vitrain has a random reflectance of 0.38% (Table 2), higher than the value found for the TV sample. It is formed by the three maceral groups (Table 1)which appear in different concentrations, humocollinite being (gelinite variety) the
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Table 2. Results of Reflectance Measurementsa TV sample TAC sample random reflectance (%) 0.23(0.02) 0.38(0.04) humocollinite 0.31(0.03) phlobaphinite (% R,) humotelinite 0.24(0.02) light wall (% R,) humotelinite 0.20 (0.01) dark wall (% R,) 0.17 (0.02) light resinite (9% R,) dark resinite (% R,) 0.09 (0.02)
