Van Krevelen Diagrams

General scheme of kerogen evolution from diagenesis to metagenesis in the van Krevelen diagram. 

Wu, Z. Rodgers, R. R Marshall, A. G. Two- and three-dimensional van Krevelen diagrams A graphical analysis complementary to the Kendrick mass plot for sorting elemental compositions of complex organic mixtures based on ultrahigh-resolution broadband Fourier transform ion cyclotron resonance mass measurements. Anal. Chem. 2004, 76, 2511-2516. 

Figure 7.3. Van Krevelen diagram. Black squares plot the changes of the elemental composition during heating of peat material at 350°C at oxic conditions as reported in Ahnendros et al. (2003).

Kim, S., Kramer, R. W., and Hatcher, P. G. (2003). Graphical method for analysis of ultrahigh-resolution broadband mass spectra of natural organic matter, the Van Krevelen diagram. Anal. Chem. 75, 5336-5344. 

Figure 13.13. Van Krevelen diagram (left) of 11 molecular compositions of CnHmOq for marine NOM (UDOM) materials. Represented are three series of CH4/0 isobaric molecules with an IUPAC nominal mass of 178Da and numbers of feasible isomers given (unit count = 10,000 isomers). Certain restrictions have been applied to exclude mathematically possible, but chemically unlikely, structures. The dotted line relates isobaric molecules, in which 4C atoms were exchanged against 30 atoms. Right Numbers of calculated isomers according to series 1-3 and IUPAC mass. [From Hertkorn (2006), with permission.]...

Figure 3.5 General scheme of kerogen evolution from diagenesis to metagenesis in the Van Krevelen diagram (from Tissot and Welte, 1984. Reprinted by permission of Springer-Verlag).

Figure 5. Van Krevelen diagram of some Queensland Tertiary kerogens.

Figure 6 indicates the position of the Ontario shales on the van Krevelen diagram. Atomic 0/C ratios are considered to be overstated because of the presence of minor amounts of silicate mineral matter in the kerogen isolates. Therefore, the kerogens may have lower atomic 0/C ratios than shown and so could be type I or type II. 

Fig. 4.13 Confirmation of the van Krevelen diagram in a stirred cell with a plane surface. Material system CO2/NaOH from [212].

Figure 35. General scheme ofkerogen evolution in a van Krevelen diagram (from Engel and Macko, 1993).

What chemical alterations have occurred during kerogen transformation Give an example of a van Krevelen diagram. 

Van Krevelen diagrams, of atomic O/C versus H/C ratios, are frequently used to compare the compositions of coals and their components. Typical initial (immature) positions of some of the major macerals and plant tissues in such a plot are shown in Fig. 4.3.As can be seen... 

Fig. 4.3 Chemical composition of major coal macerals and plant tissues plotted on a van Krevelen diagram (after Tissot Welte 1984 Hedges et al. 1985). Lignin incorporates differences between angiosperms (ang) and gymnosperms (gym) (after Hatcher 1990).

Fig. 4.5 Van Krevelen diagram showing the main evolutionary trends of sapropelic (cannel and boghead) and humic coals (after Durand et al. 1983). Rank increases towards the origin brown coal = lignite + sub-bituminous coal).

Fig. 4.14 Distribution of oxygen-containing functional groups in the three main types of kerogen with increasing maturity (after Behar Vandenbroucke 1987). See Fig. 4.15 for positions of samples on a van Krevelen diagram and Table 4.8 for additional compositional data.

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