FSC 432
Petroleum Processing

Desirable Chemical Reactions

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Desirable Chemical Reactions

Figure 8.2 illustrates more specifically the desirable chemical reactions of catalytic reforming including:

  • dehydrogenation of naphthenes to aromatics,
  • dehydroisomerization of alkyl-C5-naphthenes,
  • dehydrocyclization of n-paraffins to aromatics, and
  • isomerization of n-alkanes to i-alkanes.

All of these reactions significantly increase the octane number (research octane number [RON] from 75 to 110 in Reaction 1, from 91 through 83 [cyclohexane] to 100 in Reaction 2, from 0 to 110 in Reaction 3, and from –19 to 90 in Reaction 4).

Specific chemical structures of the chemical reactions listed above. Also noted: promote reactions with high T, low P, low SV, low H2/HC¬¬¬
Figure 8.2: Desirable chemical reactions in of catalytic reforming reactions.
Source: Dr. Semih Eser

Reaction conditions that promote the desirable reactions are also listed in Figure 8.2. As can be seen in Figure 8.2, aromatic compounds and large quantities of by-product H2 are produced in the highly endothermic Reactions 1–3. High temperatures, low hydrogen pressures, low space velocity (SV), and low H2/HC ratio strongly promote the conversion in Reaction 1-3. Although maintaining a low hydrogen pressure is needed for promoting equilibrium conversion in Reactions 1-3, it is, however, necessary to maintain a sufficiently high hydrogen pressure in the reactors to inhibit coke deposition on the catalyst surfaces.