Engineering Chemistry S Datta

FUELS AND COMBUSTION 409
• Polymerisation
C
CC=C + CC=C
or cat.
C
CCCC = C
C
C
• Alkylation
82%
C
C = CCC + CCC
CCCCC
C
C
C
• Isomerisation
1-Butene
Isobutane
Isooctane
CCCC
Straight chain
C
300°C
CCC
Anh. AlCl 3
Branched chain
• Hydroforming or Aromatisation
() i
CH 3
CH 3
+3H 2
( ii)
CH 3 (CH)CH 2 5 3
n-heptane
cat
CH 3
+4H 2
Q. 14. What is Benzol?
Ans. Benzol is a coal tar distillation fraction (b.p. 70-150°C) containing 70% benzene,
18% toluene and 6% xylenes. It is blended with petrol. It has octane rating 87-90. The blended
petrol is a good motor fuel.
Q. 15. What is power alcohol?
Ans. Ethyl alcohol when blended with petrol to be used as a fuel for internal combustion
engine, is known as power alcohol.
Q. 16. What is gasohol?
Ans. It is a mixture of gasoline and alcohol.
gasoline + alcohol = gasohol.
The use of grain alcohol as a blending agent with petrol is a controversial issue in the
world. Though blending will reduce 10% petrol consumption but alochol production by
fermentation will make use of food grains which is not desirable. Moreover, rectified spirit
(95% alcohol) is not suitable for blending, 99.5% alcohol is to be produced which will make the
cost higher. That is why now-a-days butanol is tried for the purpose.