Coke formers aromatic hydrocarbons

The coke-former aromatic hydrocarbons listed in Table 4.1 and shown in Fig. 4.2, i.e., naphthalene, einthracene, and acenaphtalene, are linear with a coplanar structure that has no preferred growth direction. This structural feature and the formation of a mesophase mentioned in Sec. 2.3 are the major factors in the easy conversion of theturbostratic structure into well-ordered graphite planes.1 1... 

Graphitization of Aromatics. As mentioned above, not ail aromatic hydrocarbons form coke. Some, such as phenanthrene and biphenyl, do not graphitize and are considered char formers. These compounds are branched aromatics (as opposed to the linear structure of the coke-former aromatics) with a preferred axisof growth asshown in Fig. 4.3. Thischaracteristic prevents the formation of extensive graphitic planes and of a liquid mesophase.l l... 

According to the literature, the platinum state does not seem to be a key factor for the catalytic oxidation of chlorobenzene. Certain studies have used platinum in a reduced state and others have used platinum in its oxidised state. However, studies carried out on the oxidation of VOCs showed that reduced Pt (Pt ) deposited on zeoUtes was the most active species for the oxidation of aromatic hydrocarbons and ketones. " In this context, the l.l%PtHFAU(5) catalyst formerly reduced in situ under hydrogen for six hours at 450°C was tested in the oxidation of chlorobenzene at 300°C. The particular effect of this treatment was to slightly increase the total conversion of chlorobenzene but with a much higher number of polychlorinated compounds (from 6.3 to 33.8 ppm) and amount of coke deposited on the catalyst after reaction (from 0.4 to 1.17%) (Table 5.2). 

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