Download 7 - University of Miami

Chemistry 101 H
Petroleum
Chapter 7 - Petroleum
This presentation was created by
Professor Carl H. Snyder
Chemistry Department
University of Miami
Coral Gables, FL 33124
[email protected]
Copyright 2004 by Carl H. Snyder,
University of Miami. All rights
reserved.
Petroleum + Distillation = Gasoline
Petroleum comes
from two Latin words:
petrus (rock) + oleum
(oil).
Petroleum consists
principally of various
hydrocarbons that can
be separated from
each other by
distillation.
A Typical Cylinder
The Four-Stroke Internal
Combustion Engine
Energy released through the combustion of
gasoline (petroleum hydrocarbons) powers the
four-stroke
internal combustion engine.
Stroke 1
Intake Stroke
Intake valve open;
exhaust valve closed
Piston moves
downward
Gasoline-air mixture
drawn into the cylinder
1
Stroke 2
Compression
Stroke
Both valves closed
Piston moves
upward
Gasoline-air mixture
compressed
Stroke 4
Exhaust Stroke
Exhaust valve is open;
intake valve is closed
Piston moves upward
Gases resulting from
combustion are moved
out of the cylinder, out
of the car, into the
atmosphere.
The Volatility of Hydrocarbons
- Chain Length -
For unbranched hydrocarbons, the shorter the
hydrocarbon chain, the lower the boiling point.
Stroke 3
Power Stroke
Both valves closed
Piston moves
downward
Combustion of
gasoline-air mixture
releases energy that
moves the piston
downward.
A Summary
Intake stroke
Compression stroke
Power stroke
Exhaust stroke
The Volatility of Hydrocarbons
- Branching -
For hydrocarbons of the same carbon-content, the
greater the degree of branching, the lower the boiling
point.
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Compression
Ratio
The compression
ratio is one of the
factors that affects
knocking.
Knocking
Knocking results from preignition or irregular
ignition of the gas-air mixture.
Octane Rating
Octane Ratings at the
Gasoline Pump
Difference in tendencies to produce knocking.
Deriving Octane Numbers
2,2,4-trimethylpentane and hetpane
Mixtures of the two are used to determine octane
ratings.
Research vs. Motor
Cruising along the highway or zooming away
from a stop light?
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A Solution To A Problem Of
The 1920s - Leaded Gasoline
Adding 1 teaspoon of tetraethyllead to a gallon of
gasoline raises the gasoline’s octane number by
about 10 points.
A Solution To A Problem Of
The 1990s - Beyond Lead
Lead is toxic to humans and inactivates
catalytic converters.
Lead can be replaced by octane enhancers.
MTBE (methyl tert-butyl ether) is a leading
oxygenate and octane enhancer.
MTBE
(Methyl tert-Butyl Ether)
Disadvantage:
Potential for polluting
undergroiund water
supplies.
"The state of
California has
determined that the
use of this chemical
presents a significant
risk to the
environment."
A Solution To A Problem Of
The 1970s - The Catalytic
Converter
Unburned hydrocarbons in exhaust gases
contribute to air pollution known as smog.
The catalyst of the catalytic converter helps
oxidize these hydrocarbons to CO2 and H2O.
MTBE
(Methyl tert-Butyl Ether)
Advantages:
Octane enhancer
Oxygenate
A Solution to the Problems
Presented by Tetraethyllead,
MTBE, and Other Additives
- Petroleum Refining Octane ratings can be increased by improved
methods of petroleum refining.
Converting crude oil to refined gasoline and
other commercial products by:
Distillation
Catalytic Cracking
Reforming - Isomerization
Reforming - Cyclization
Reforming - Aromatization
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Distillation - The Process
Distillation At The Refinery
A liquid is
heated to boiling
The vapors are
separated from
the liquid
The vapors are
cooled
The condensed,
purified, distilled
liquid is
collected.
Refinery distillation separates the crude oil into
its various hydrocarbon fractions.
Distilled Fractions
Catalytic Cracking - Definition
Catalytic Cracking - Example
Catalytic Reforming
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Reforming - Isomerization
Isomerization converts straight-chain
hydrocarbons to branched-chain hydrocarbons.
Isomerization increases the octane rating of the
hydrocarbons.
Reforming - Aromatization
Reforming - Cyclization
Cyclization converts acyclic hydrocarbons into
cyclic hydrocarbons.
Cyclization paves the way for aromatization.
Alternative Fuels
Liquified Petroleum
Gas (LPG)
Compressed Natural
Gas
Ethanol
Methanol
Electricity
Fuel Cells
Aromatization converts nonaromatic, cyclic
hydrocarbons into aromatic hydrocarbons.
Aromatization increases the octane rating of
hydrocarbons.
Advantages and
disadvantages of each.
A Fuel Cell
The
combination of
H2 and O2 in a
fuel cell can
provide energy
where fossil
fuels can’t be
used, as in
space
capsules.
End - Chapter 7
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