Dehydrogenation

The naphthenic hydrocarbons are dehydrogenated to form aromatics (see Figure 4-1). The reaction is extremely fast, and the yields obtained

(1) Dehydrogenation of napthenes to aromatics with energy absorption

(2) Isomerization of normal paraffins to isoparaffins

C6H14 , " CH3 — CH—CH2—CH2 — CH3 2 kCal/mole

(3) Dehydrocyclization of paraffins C7H12 «

60 kCal/mole

(4) Hydrocracking reactions

CH3—CH—CH2—CH3 + CH3—CH—CH3 -10 kCal/mole

(5) Secondary reactions Demethanation

Desuifurisation R-S-R + 2H2

Denitrification R=N-H + 2H,

Figure 4-1. Reforming reactions.

are almost those predicted by thermodynamics. Also, the reaction is endothermic, AH 50kCal/mole. Dehydrogenation reactions are very important, because they increase the octane number and the reactions produce hydrogen. The only disadvantage is their endothermicity. Due to the large heat absorption, the feed has to be reheated several times, requiring a number of furnaces and reactors.

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