Page 65 - Fluid Catalytic Cracking Handbook

FCC Feed Characterization 43

CH 3

H 2C CH
H 2C
/ \ / \
H 2C H 2C H 2C H 2C
/ \
H 2C H 2C
1 1 1 i i 1
H 2C H 2C H 2<- "Ut if" 1
C*
Jtl 2C
\ /
H 2C— H 2C \ / \ /
H 2C H 2C
Cyclopentane Cyclohexane Methy-Cyclohexane
(C 5H !0) (C 6H 12) (C 7H 14)
Figure 2-3. Examples of naphthenes.

Naphthenes are desirable FCC feedstocks because they produce
high-octane gasoline. The gasoline derived from the cracking of
naphthenes has more aromatics and is heavier than the gasoline
produced from the cracking of paraffins.

Aromatics

Aromatics (C nH 2n_ 6) are similar to naphthenes, but they contain a
resonance stabilized unsaturated ring core. Aromatics (Figure 2-4) are
compounds that contain at least one benzene ring. The benzene ring
is very stable and does not crack to smaller components. Aromatics

H CH,

H— C)"" (:— H H r \_ C-H H-C

H-^< C i_i P-i H-C H
H e v»^ CD— H
V ^c^ "C I
o
y
H H H

BENZENE (C 6H 6) TOLUENE (C 7 H 8 ) ANILINE (C 6 H 5 NH 2 }
Figure 2-4. Examples of aromatics.