Carbon limit diagram

Figure 5.15 Carbon limit diagram. Principle of equilibrated gas. Carbon is formed for conditions to the left of the curves. Curves 1 and 2 represent graphite data and whisker carbon (Appendix 2), respectively. The dotted hnes show feed gas compositions leading to product gas with indicated H2/CO ratios [152]. Reproduced with the permission of...

Figure 10. Carbon Limit Diagram, 6 bar abs. H2/CO ratios in exit gas indicated by dotted lines. (Rostrup-Nielsen, 1988c).

The predominance limits shown in figure 8.22 are analytically summarized in table 8.17. Compare figures 8.22 and 8.21 to better visualize the redox state of the anionic ligands at the various Eh-pH conditions of interest (particularly the sulfide-sulfate transition and carbonate limits). We remand to Garrels and Christ (1965) for a more detailed account on the development of complex Eh-pH diagrams. 

A system particularly studied from a thermodynamic point of view is the monocarbide (AnCi x) system. A range of stability for carbon deficient compositions in the monocarbides is present in many metal-carbon phase diagrams. Table 6 shows the composition range at room temperature for actinide monocarbides. The non-stoichiometry range is very limited for uranium monocarbide for neptunium and plutonium monocarbides, the stoichiometric AmCj oo composition is not stable. 

Figure 4.5 shows a phase diagram between silicon and carbon. The diagram shows how SiC particle precipitation forms in Si-melt in the C-rich domain [20], in which the solubility limit of carbon in Si-melt CL(T) is approximated by a polynomial function,... 

The thermodynamic carbon limit B is a function of the composition of the feed gas (atomic ratio 0/C and H/C) and total pressure. An example of thermodynamic limits (16) is given in the diagram in Fig. 6. This calculation should apply the thermodynamics of whisker carbon pushing the carbon limits to more critical conditions. It means that in principle the carbon limits depend on the nickel particle size of the crystal (17,18) as illustrated in Fig. 7. 

The classification of amorphous carbon films according to carbon bond type and hydrogen content can be represented in a triangular diagram, Fig. 6 [e.g., 70]. The comers at the base of the triangle correspond to graphite (100% sp carbon) and diamond (100% sp carbon). The apex represents 100% H, but the upper limit for formation of solid films is defined by the tie line between the compositions of polyethene, -(CH2) -, and polyethyne, -(CH) -. 

Sulfur (figure 8.21D) is present in aqueous solutions in three oxidation states (2—, 0, and 6+). The field of native S, at a solute total molality of 10, is very limited and is comparable to that of carbon (for both extension and Eh-pH range). Sulfide complexes occupy the lower part of the diagram. The sulfide-sulfate transition involves a significant amount of energy and defines the limit of predominance above which sulfates occur. 

In the diagram of propane, the most important feature is the chain of 3 carbons. Such carbon-carbon bonding is what generates the incredible variety of organic compounds. This linkage of carbon atoms can continue without limit. Just as propane has 3 bonded carbons, you can imagine organic compounds with 4 or 5 or 500 carbons in an extensive chain or network. 

Mozenski and Kucharski [2] examined the pressure-drop, overload limit, and flooding limit of a column (0.5 m diameter) packed with Pall rings (35 mm diameter) and Bialecki rings (35 mm and 50 mm diameter) sprayed with propylene carbonate up to 15 bar. Some specific correlations have been proposed and compared with literature data for atmospheric pressure, particularly with the use of the Sherwood diagram for loading-and flooding capacities. 

Revised proposals for the phase diagrams of the Group 5 transition metal-carbon systems are given in Figure 4.3(a-c). In our opinion they are preferable with respect to the composition and decomposition temperature of the t, phases (within the limits given in Table 4.1) as well as the homogeneity ranges of the fi and 6 phases. 

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