Polymerization Of gasoline&In the petroleum industry

1. PolymerizationPolymerization
Of gasolineOf gasoline
Mohamed Salah Abu-Hamad
Refining and Petrochemical
Engineering

2. Overview
A Brief History
Description
ID card
Explanation of the process
Catalyst
Principal Reactions
Health and Safety Considerations
Comparison of polymerization and alkylation

3. A Brief History
It was widely used in the 1930's and 1940's,
but was replaced by the alkylation process
after WWII. It did make a comeback due to
the mandated phase out of leaded gasoline
and the demand for high octane fuel.

4. THE REFINERY

5. Description
Polymerization in the petroleum industry is the process of
converting light olefin gases including ethylene,propylene, and
butylene into hydrocarbons of higher molecular weight and
higher octane number that can be used as gasoline blending
stocks.
Polymerization combines two or more identical olefin
molecules to form a single molecule with the same elements in
the same proportions as the original molecules.
Polymerization may be accomplished thermally or in the
presence of a catalyst at lower temperatures.

6. ID card
Feedstock From Typical
products
To
Olefins Cracking
processes
High octane
naphtha
Gasoline
blending
Petrochem.
feedstock
Petrochemi
cal
Liquefied
petro. gas
Storage

7. Drawing

8. Explanation of the process
The olefin feedstock is pretreated to remove sulfur and
other undesirable compounds.
In the catalytic process the feedstock is either passed
over a solid phosphoric acid catalyst or comes in contact
with liquid phosphoric acid, where an exothermic
polymeric reaction occurs.
This reaction requires cooling water and the injection of
cold feedstock into the reactor to control
temperatures between 300° and 450° F .
pressures from 200 psi to 1,200 psi.

9. Cont…
The reaction products leaving the reactor are sent to
stabilization and/or fractionator systems to separate
saturated and unreacted gases from the polymer gasoline
product.

10. Catalyst
The above reactions are caalyzed by phosphoric acid on
an inert support. Sulfur in the feed poisons the catalyst and
basic compounds neutralize the acid and increase its
consumption. Also, oxygen dissolved in the feed strongly
affects the reactions and must be removed..

11. Principal Reactions
olefin + olefin --> olefin
C=C-C + C=C-C --> C-C-C=C-C
C=C-C-C + C=C-C --> C-C-C-C-C=C-C

12. NOTE
In the petroleum industry, polymerization is used to indicate the
production of gasoline components, hence the term "polymer"
gasoline. Furthermore, it is not essential that only one type of
monomer be involved.
If unlike olefin molecules are combined, the process is referred
to as "copolymerization." Polymerization in the true sense of the
word is normally prevented, and all attempts are made to
terminate the reaction at the dimer or trimer (three monomers
joined together) stage.
However, in the petrochemical section of a refinery,
polymerization, which results in the production of, for instance,
polyethylene, is allowed to proceed until materials of the required
high molecular weight have been produced.

13. Health and Safety Considerations
a. Fire Prevention and Protection.
Polymerization is a closed process where the potential
for a fire exists due to leaks or releases reaching a source
of ignition.
b. Safety.
The potential for an uncontrolled exothermic reaction
exists should loss of cooling water occur.
Severe corrosion leading to equipment failure will
occur should water make contact with the phosphoric acid,
such as during water washing at shutdowns.
Corrosion may also occur in piping manifolds,
reboilers, exchangers, and other locations where acid may
settle out.

14. Cont…
c. Health.
Because this is a closed system, exposures are expected
to be minimal under normal operating conditions.
There is a potential for exposure to caustic wash (sodium
hydroxide), to phosphoric acid used in the process or
washed out during turnarounds, and to catalyst dust.
Safe work practices and/or appropriate personal
protective equipment may be needed for exposures to
chemicals and other hazards such as noise and heat, and
during process sampling, inspection, maintenance, and
turnaround activities.

15. Comparison of alkylation and
polymerization
Process POLYMERIZATION ALKYLATION
Purpose polymerize propene and
butenes to form a high octane
gasoline.
produce a high octane
gasoline by reactine light
olefins with light iso-
paraffins.
Feed Propene and butene primarily a mixture of
(propylene and butylene)
with isobutane
Operating
Conditions
Pressure 200-1200 psi
Space Velocity 0.3 gal/lb
Temperature 300-450 F
Lower temperatures
(yield a higher quality)
Strong acid strength

16. Catalyst phosphoric acid
(H2SO4 and HF)
The concentrations must
be greater than 88%
Products 1. Liquefied petro. gas
2. High octane
naphtha
3. Petrochem.
Feedstock
1. LPG grade propane
liquid
2. Normal butane
liquid
3. C5 + alkylate
(want to maximize its production)
Gasoline
Specification
MON = 83
RON = 97
MON = 88-94
RON = 94-99

17. Major Refinery Products
LPG (Propane/Butane)
GASOLINE (hundreds of blends)
JET FUELS
DIESEL FUELS
HEATING OILS
GREASES
ASPHALTS
COKE (not the kind you drink )

18. Gasoline Specifications
Gasoline must meet many criteria which change with the time
of year and geographic location. Some critical
specifications are:
Vapor Pressure
Octane
Aromatics / Benzene Content
Sulfur Content
Gasolines are always a blend of a number of streams in the
refinery

19. Specifications
Product gasoline (olefin)
MON = 83
RON = 97

20. Summary
Comparison of alkylation/polymerization
with catalytic cracking:
Alkylation/polymerization combines
shorter chains (C3, C4) to get C7 and C8.
Catalytic Cracking breaks long chain n-
alkanes to make branched alknaes.
The final product for each process is
branch chain alkanes.

21. References
Web
http://www.hghouston.com
http://www.eoearth.org
http://nptel.iitm.ac.in
Books
Petroleum refining technology and
economics_James H. Gary