Coke types

Eor the Gray-King coke-type assay test (91,92) coal is heated in a retort tube to 600°C and the product coke is compared to a series of standard cokes. Eor a strongly swelling coal, enough anthracite or electrode carbon is added to the coal to suppress the swelling. This method is primarily used in Europe. 

The necessity of forcing activation conditions has been attributed to the production of various carbonaceous species during activation. Under oxidizing atmospheres, the appearance of stretching frequencies consistent with the formation of surface carboxy-lates has been reported. Similarly, several persistent surface bands consistent with coke-type species were identified when activating supported Ru DENs under H2. °... 

A volume increase is possible only when the whole sample briquet has already been deformed (the deformation of the sample being in fact measured as an expansion). When the expansion begins (see Figure 10, 385°C.), pore formation in the vitrinite sets in. The size of the pores formed in the dilatometer experiment is on the average smaller than in a loose bulk owing to the fact that deformation of single particles into void volumes is impossible in the dilatometer. Figure 13 compares the dependence of pore formation on bulk density for three coke types. 

Coals classified by class and by group are further subdivided into subgroups, defined by reference to coking properties. The coking properties are determined by either the Gray-King coke type of assay or the Audibert-Amu dilatometer test (ISO methods). These tests express the behavior of a coal when heated slowly, as in carbonization. 

Since the high-temperature assay is used mainly for the examination of gasmaking coals, the range of coke types normally encountered is considerably smaller than that met with in low-temperature assays, and as a consequence, no standard classification of coke types has been drawn up, nor is such a classification so necessary in this case. Nevertheless, a full description of the coke should always be made. 

Properties of Calcined Coke. Table II shows the properties of calcined cokes A, B, C, D and F by the new and traditional methods. Regardless of the green coke type, the thermal expansion coefficient of calcined coke by the new method was lower than that of traditional calcination method. Porosity values for calcined cokes by the new method have a higher value, regardless of the coke type, than... 

The only small-scale methods that have stood the test of time and have been accepted as standard plasticity tests are the crucible swelling number, Gray-King coke type, dilatation characteristics, Gieseler plasticity, and, in some countries, the Rogas index. All of these are essentially empirical in nature and many are subjective, at least to some degree. 

Group Class (% dmmO Coke Type Description... 

Figure 4 Gray-King coke types and profiles.

Table 5 Comparison between free-swelling index, Gray-King coke type, and Roga index...

Free-swelling index Gray-King coke type... 

Thus, Butt s k measxireraents of a very non-uniform coke profile, indicate that ultimate penetration of a coke type foulant into a catalyst particle is very quickly attained, and sybsequent deposition occurs entirely within an outer shell. 

The specific energy or capacify of fhe lifhium-ion system depends largely on the type of carbon materials used, the lithium intercalation efficiency, and the irreversible capacity loss associated with the first charge process. Table 34.3 lists the properties of some of these carbon materials. Coke-type carbon, having physical properties such as ash content <0.1%, surface area <10 m /g, true density <2.15 g/cm, and interlayer spacing >3.45 A, were used in first-generation lithium-ion system. These types of carbon materials can provide about... 

The types of carbon may alternatively be organized based on the type of precursor material, as illustrated in Fig. 35.17 as the precursor material, and the processing parameters determine the nature of carbon produced. Materials that can be graphitized by treatment at high temperature (2000°C to 3000°C) are termed soft carbons. Upon graphitization, the turbostratic disorder is removed and strain in the material relieved. Hard carbons, such as those prepared from phenolic resin, cannot be readily graphitized, even when treated at 3000°C. Coke type materials are prepared at 1000°C, typically from aromatic petroleum precursors. 

Table 3.10 Gray-King assay coke types [11],...

Figure 6.34 shows the TG/DTA results for the spent catalysts after reforming at 663 K (a) and 963 K (b). It is not possible to differentiate the type of coke deposited on the catalyst. The mass loss of the catalyst tested at 663 K was 45 %, while that at 963 K about 28 %. DTA profiles show that the catalyst tested at 663 exhibited one peak at 820 K and a shoulder around 860 K, which suggest the presence of two different types of coke formations. On the other hand, the catalyst tested at 963 K exhibited only one peak at around 950 K and indicates the presence of only one coke type formation. 

Table 2.6 Parameters for kinetic modeis of coke combustion Coke type (mol/g-cat.-min)...

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