Van Krevelen plots

Figure 2. A van Krevelen plot showing approximate bands for the three main maceral groups.

Another view of the elemental compositions of FAs, HAs, and NOM and the major constituents of biomass is provided in Figure 5, which is known as a van Krevelen plot. The elemental compositions of FAs, HAs, and NOM overlap considerably in Figure 5. This overlap is consistent with the median elemental compositions in... 

The median elemental compositions of FAs, HAs, and NOM are rather similar, and so consequently are properties such as the average oxidation state of organic carbon and the total unsaturation of these materials. Most of the elemental compositions that were included in this review lie outside the biomass triangle on a van Krevelen plot, indicating that DOM is not simply a residue of biomass. It has clearly gained oxygen and lost hydrogen, as would be expected for partial oxidation of biomass to CO2 and H2O. 

Figure 7 An H/C versus 0/C (van Krevelen plot) plot of peat and coals of different rank. The plot illustrates that loss of oxygen (change in 0/C) is most important during peatification and early stage coalification, with H loss (change in H/C) becoming more important during coalification to higher rank.

Figure 2. The Van Krevelen plot of atomic /// C vs. atomic O/ C ratios for kerogen and coal samples. The two kerogen samples are from cores OH-3 and OH-4. The development line is that of vitrain in coal (18). Key , kerogen , coalijied wood fragments and O, callixylon from Chattanooga shale.

Fig. 4.15 A van Krevelen plot showing the evolutionary trends of the main kerogen types (shaded bands after Behar Vandenbroucke 1987) and most coals (between solid lines after Killops etal. 1998). With increasing maturity kerogens follow a path towards the origin, as shown for the low/high-H coals boundary.The main hydrocarbon-generation zones are shown, with their approximate rank boundaries (as vitrinite reflectance values, %Ro), together with the effect of loss of various volatiles from different kerogen compositions (CH2 = oil). Points represent the composition of kerogens in Fig.4.14.

Figure 7. A van Krevelen plot of the elemental compositions of buried woods and their modern counterparts. (Reprinted with permission from ref 30.

Modification of van Krevelen Plots to Verify the Selection of Bio-Derived Chemicals... 

Fig. 7 van Krevelen plot for carbohydrate-derived chemicals, colored by carbon number. VGA vinyl glycolic acid, HBL hydroxybut5Tolactone, GVL y-valerolactone, C5 pentoses, C6 = hexoses, LA levulinic acid, Suer. sucrose, Hemi. hemicellulose... 

Fig. 10 Modified van Krevelen plot for carbohydrates and their derived products, colored by...

Modifying the Original Van Krevelen Plot Functionality vs //-Index... 

In Fig. 12, a modified van Krevelen plot is shown, which contains cellulose and common sugars as well as reaction arrows. The latter are drawn to emphasize the impact of dehydration (in blue). As can be seen, a typical dehydration reaction preserves the level of functionality in our assessment while decreasing the H index of the compound. In general, dehydration involves a horizontal move to the left-hand-side of the plot. 

Fig. 12 Modified van Krevelen plot for cellulose, sugars, and the dehydration products thereof.

Fig. 14 Modified van Krevelen plot for the dehydration of sorbitol (after hydrogenation of glucose), lactic acid, 1,4-butanediol, and n-butanol. DH = dehydration, HG = hydrogenation. The effect of hydration of an aldose (hemi-acetal formation with water) is also shown...

In conclusion, dehydration, hydration, and hydrolysis (e.g., of cellulose to glucose or hemicellulose to xylose [137]) reactions fuUy preserve the degree of functionality of the starting biomass or chemicals derived therefrom. In the modified van Krevelen plot, the dehydrated products are located horizontally to the left... 

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