chemistry of fuels

Presented by
• Ali Zia
• Bilal Ali
• Hafiz M Kashif

CONTENTS
Introduction of fuels.
Chemical composition of fuels.
Nuclear fuels.
Fossil fuels.
Industrial processing of fuel.
Energy from fuels.

Introduction
• The word “Fuel” is came from Old French feuaile, from
feu fire, ultimately from Latin focus fireplace, hearth.
• A fuel is any compound that has stored energy.
• This energy is captured in chemical bonds through
processes such as photosynthesis and respiration.

 Energy is released during oxidation.
 Most common form of oxidation is the direct
reaction of a fuel with oxygen through
combustion.
 It is simply the reaction of substances with
oxygen and converts chemical energy into heat
and light.

 Wood, gasoline, coal, and other fuels have
energy-rich chemical bonds created during
using the energy from the sun.
 This energy is released when the fuel is
burned (i.e. the release of chemical
energy).
• Are useful reserve of energy and therefore
used extensively to satisfy the demands of
an energy-dependent civilization.

History
• The ﬁrst known use of fuel was the combustion of wood or sticks
by Homo erectus nearly two million years ago.
• Throughout most of human history fuels derived from plants or
animal fat were only used by humans.
• Charcoal, a wood derivative, has been used since at least 6,000 BCE
for melting metals.

• Charcoal briquettes are now commonly used as a fuel for
barbecue cooking.
• Coal was ﬁrst used as a fuel around 1000 BCE in China.
• With the concept development of the steam engine, coal
came into more common use as a power source.
• Coal was later used to drive ships and locomotives.
• In 20th and 21st centuries, the primary use of coal is to
generate electricity.

Heat produced by fuels
• Fuels are any materials that store potential energy in forms that
can be practicably released and used for work or as heat energy.
• The heat energy released by many fuels is harnessed into
mechanical energy via an engine.
• Or is valued for warmth, cooking, or industrial processes, as well
as the illumination that comes with combustion.

 Fuels are also used in the cells of organisms in a process known as
cellular respiration, where organic molecules are oxidized to release
usable energy.
 Fuels contain one or several of the combustible elements: carbon,
hydrogen, Sulphur, etc.
 During combustion C and H combine with O2 with liberation of
heat.
C+O2 CO2+ 94 Kcals
2H2+O2 2H2O +68.5 Kcal

Characteristics of a good Fuel
1. It should ignite easily.
• Ignition temperature: The temperature of the
fuel at which ignition starts and continues to burn
without further addition of heat is called ignition
temperature.
 It should be moderate for a good fuel.

2. It should give out a lot of heat, that is, its
specific heat should be high.
3. Low smoke and combustible matter such as
ash.
4. Inexpensive and readily available.
5. easy to store and transport.
6. low ash content.

Types of Fuel
Classifications of Fuels
Based on Physical State
Based on occurrence
 Solid fuel (e.g., wood, coal)
 Liquid fuel (e.g., crude
petroleum, natural gasoline)
Gaseous fuel (e.g., natural gas)
 Secondary or Synthetic fuels (e.g.,
Water Gas, charcoal, petroleum
coke).
 Primary or natural fuels (e.g.,
wood, coal)

Composition of fuel
In terms of their chemical composition their principle constituents are carbon(C)and
hydrogen (H).
The other important constituents are nitrogen (N) Oxygen(O) and Sulphur (S).
These elements combine to form organic compound in fossil fuels, in contrast to other
earths constituents which are inorganic(such as sand and other rocks and minerals).
Different types of fuels have different constitutional elements that give them some unique
features.
The elements present in the fuels determine their ignition and combustion properties.

• All coal contains various combustible materials, left
from the alteration of the vegetal matter, moisture,
and varying amounts of mineral matter which on
burning appear as ash.
• The usual means of determining the composition of
a coal are:
(1) by an ultimate analysis and
(2) by a proximate analysis.
Composition of coal

• The combined water is presented by the oxygen content
of the coal plus the equivalent amount of hydrogen
necessary to unite with it to form water.
• Free or available hydrogen is the hydrogen remaining
after combined hydrogen and on burning can produce
heat by union with oxygen of the air.
Moisture

Coal ash
• The ash in coal is composed of two classes:
(1) free ash and (2) fixed ash.
• The ash-forming constituents of coal are:
(a) impurities present as an intimate mixture in the coal substance,
derived from the ash in the original vegetal matter or from
sedimentation etc., during coal formation.
(b) bits of clay, shale, "slate" pyrites etc. that occur in the form of
veins and partings and
(c) fragments from the roof and floor, etc. that are mixed with the
coal in the process of mining.

• The "free ash" is mostly that formed by processes (b) and (c),
and, consisting of dirt, slate, pyrites, etc., can be washed out
of the coal by suitable coal-washing machinery. The amount
of such ash in the coal varies considerably in different parts of
the mine.
• The "fixed ash," formed mostly by process (a), is
disseminated throughout the coal fairly uniformly, and usually
amounts to from 2 to 3 percent.

• The presence of sulfur in coal is always harmful, since it
affects the quality of coke for metallurgical uses, increases
the corrosion of boilers, and usually affects the fusibility of
the ash.
• It occurs in three forms:
(1) pyritic sulfur,
(2) organic sulfur,
and (3) sulfate sulfur.
Sulphur

• The nitrogen content of coals is of great economic
importance, because of the value of the nitrogen obtained
as ammonia in the manufacture of by-product coke.
• The nitrogen, present as a constituent of the organic
compounds which go to make up the coal substance, is
mainly derived from the original vegetal matter (the N2
content of trees varying from 1 to 3 per cent), although a
small proportion may originally have come from animal
matter or from the air.
Nitrogen

• Consists in determining the percentages of the "ultimate"
constituents; namely, carbon, hydrogen, oxygen, sulfur,
nitrogen, and ash in the dry coal.
• The amounts of carbon, hydrogen, and nitrogen are
determined by the ordinary methods of organic quantitative
analysis.
• The sulfur may be determined by analysis of washings from
the bomb calorimeter used in determining the heating value
of the coal.
Ultimate analysis

Ultimate analysis
• The amount of oxygen is always determined by difference,
the sum of the percentages of carbon, hydrogen nitrogen and
sulfur, plus the percentage of ash, being subtracted from 100
to give this constituent.
• pyrites to be converted to ferric oxide in the ash, that the
oxygen be determined by subtracting from 100 the sum of
carbon, hydrogen, nitrogen, ash, and five-eighths the sulfur.

Proximate analysis
The proximate analysis of coal, which includes the
determination of moisture, volatile matter, fixed carbon, ash,
and sulfur, is:
• Much easier
• Quicker than the ultimate analysis
• And is the one more commonly made, since it furnishes
most of the data necessary to determine the commercially
important properties of the coal.

Proximate analysis
• The amount of moisture is determined by the loss in
weight of a small sample on heating for 1 to 1.5 hr. at
220°F (104°C) to 230°F(110°C).
• The volatile matter is determined by heating a 1-gm
sample of the coal as purchased in a closed crucible at
1740°F (950°C) for 7 min. The percentage of volatile
matter is the percentage loss as thus determined minus
the percent moisture.
Proximate analysis

• Ash is determined on the dried sample from the moisture
determination by completely burning off all combustible
matter until the ignited material reaches a constant weight.
• The percentage of fixed carbon is equal to 100 minus the sum
of moisture, volatile matter, and ash.
Proximate analysis

• Fuel produced by the natural
resources like anaerobic
decomposition of dead
organisms.
• It is a general term for buried
combustable geological deposit
of organic material, formed from
decayed plants and animals
buried under earth crust millions
of year ago
• Fossil fuels are hydrocarbons.
• Its main components are Carbon
and Hydrogen.
• Sulphur ,Nitrogen ,Oxygen and
other metals are also present in
small amount.
Fossil fuel

• Coal is a solid usually brown or
black.
• Carbon rich material.
• It is one of the most important
fossil fuel.
• Natural resource that can be use
as source of energy.
• Coal is made up of carbon,
hydrogen, oxygen , nitrogen and
Sulphur.

It is believed that coal was formed from remains of
trees buried inside earth crust some 500 millions
years ago.
Due to bacterial and chemical reaction on wood
it got converted into peat. Then in result of high
temperature and high pressure inside earth crust,
peat got transformed into coal.
Formation of coal

Wood
bacterial chemical reaction
Peat
High pressure high temperature
Lignite
pressure
Bituminous coal
pressure
Anthracite
Formationofcoal

There are three main types of
coal.
1. peat coal
2. Lignite coal
3. Bituminous coal
4. Anthracite coal
Types of coal

Peat coal
• It is brown in colour.
• It is also called tuft.
• It has very low energy..
• It consist of partially decomposed organic
matter.
• It is harvest as important source of fuel.
• It is also use to produce electricity.

It
Lignite coal
• It is yellow or brown in colour.
• It is soft.
• It is formed from peat when heated at 100C
• It has low energy content.
• Carbon content is between 25-30%.
• It has higher moisture content.
• It has tendency to crumble.
• It is use as fuel in electric power.

bituminous coal
• It is also called black coal.
• It is black or brown in colour.
• It is medium hard.
• Carbon content is between 34-86%.
• It has little moisture content.
• It also contain S and H.
• Generally used for power generation and in
steel and iron industry.

Anthracite coal
• It is black or steel grey in colour.
• It has metallic lusture.
• It is hard.
• Highest carbon content in between 86-96%.
• It burns slowly.
• It is use to heat homes.
• It is also use for decorative purpose.

oil
• Oil is any non polar chemical substance that is
viscous at ambient temperature and is
hydrophobic.
• Very complicated liquid mixture of hydro carbons.
• Almost always contain dissolved natural gas as well.

How oils are formed
• As diatoms died they fell into the sea floor.
• They were buried under sediments and rocks . The rock squeezed
diatoms and the energy in their bodies could not escape. Carbon
eventually turned into oil under pressure and heat.

Types of oil
there are two types of oils.
1. Organic oil
2. Mineral oil

Organic oil
• Organic oil are produce in remarkable diversity by plants, animals and
other organisms through natural metabolic process

Mineral oil
Mineral oil is organic but it is called mineral instead of organic because
it is obtained in the vicinity of rocks, underground traps and sands.it
also refers to several specific distillates of crude oil.
Mineral oil iscalled petroleum when it is in refined form.
When extracted from rocks it appears as blackish colour called crude
oil.

Applications of oil
1. Cooking and food preparation.
2. Flavoring and modifying texture of food.
3. Cosmetics.
4. Painting
5. Heat transfer
6. Lubrication

Natural gas
• It is lighter than air.
• Mixture of low boiling hydrocarbons.
• Mixture primarily consisting of methane with other hydrocarbons.
Carbon dioxide , nitrogen and hydrogen supplied.
• Formed by decomposition of organic matter.
• It is highly flammable.

Natural gas is found deep underground natural rock
formation or associated with other hydrocarbon
reservoirs in coal beds. Petroleum is another resource
found in approximately to and with natural gas.
Natural gas

Uses of natural gas
Natural gas have many uses
• Power generation
• Domestic use
• Manufacturing chemical Fertilizer
• Aviation
• Production of synthetic Material

Advantages of fossil fuel
There are manys advantages of fossil fuel
• Large amount of electricity can be be generated fairly cheaply.
• Transporting of oil and Gas to power station is easy.
• Fossil fuels are very easy to find.
• Powerstations that use fossil fuel can be constructed at Almost any
direction.

Drawbacks
• The main drawback or fossil fuel is pollution.
• The burning of Fossil fuel produce carbon dioxide
Which contribute green house effect.
• It also produce sulphur dioxide That contribute to acid
rain.
• Mining coal can be difficultand dangerous.
• Strip mining damage large area of land.
• Coal fixed Power station need large amount of coal.
• Oil may contain cancer causing compound
eg.benzene.

NUCLEAR FUEL
• Material that can be used in a nuclear reactor to generate energy or
electricity.
OR
• Used in nuclear reactor to sustain a nuclear chain reaction.
• These fuels are fissile, most common are URANIUM-235 and
PLUTONIUM-239.
• Nuclear fuel cycle
• Nuclear fuel is said to be efficient if it produces a lot of energy and a
very little bit of pollutants.
obtaining Refining Using

Nuclear energy is produced
Naturally
For example, sun and
other stars make heat and
light by nuclear reactions.
Man-made
 Machines called nuclear
reactors(part of nuclear
power plants) provide
electricity.
 Explosions of atomic and
hydrogen bomb.

Nuclear energy is produced in two
different ways
 Heavy elements or large nuclei
are split into fragments to
release energy.
 Fragments of comparable
mass.
 Light elements or small
nuclei are combined to
make a larger one nuclei/ to
release energy.
 Mass of larger nuclei is
smaller than sum of the
mass of smaller nuclei.
Nuclear Fission
Nuclear Fusion

A process in which neutrons released in
fission, produce an additional fission in at
least one further nucleus. This nucleus in
turn produces neutrons, and the process
repeats.
Nuclear Chain
Reaction

Alpha
Particles
Positively charged particles and heavy as compared
to other particles.
Nuclear Radiations

Beta
Particles
Negatively charged particles and more penetrating as
compare to alpha.
Gamma
Rays
No charge highly penetrating radiations.

The
known
fissile
materials
are
Uranium-233
Uranium-235
Plutonium-238
Plutonium-239
Plutonium-241
Fission Nuclear Fuels

 The most often used fuels are U-235
and Pu-239.
 The only Fissionable Nuclear Fuel occurring
in nature is URANIUM, of which is 99.3% is
U-238 and 0.7% is U-235.
 Pu-239 and U-233 can be produced
artificially from U-238 and Th-232.
 Th-232 needs fast moving neutrons to
start the chain reaction.

c
Fusion Nuclear Fuels
Fusion reactions are induced by a mixture
of the hydrogen isotopes DEUTRIUM (H-2)
and TRITIUM (H-3), forming heavier
HELIUM nucleus.
Need extremely high temperature and
pressure.
Reaction yields 1.76MeV energy.

Advantage and
disadvantages
of nuclear
energy

Advantages of nuclear energy
1. Lower green house gas
emission
 It has been calculated, the
emissions of the Greenhouse
gases have reduced for nearly
half due to use of Nuclear
Power.

2. Powerful and efficient:
Advancement in technologies has
made it more viable option than
others. This is one of the reasons that
many countries are putting huge
investment in Nuclear Power.

3. Reliable
Nuclear energy can be produced from
nuclear power plants even in the cases
of rough weather conditions.

4. Cheap Electricity
The cost of URANIUM which is
used as a fuel, is quite low. Set
up cost of nuclear power plant is
relatively high while running cost
is low. Average life of nuclear
reactor is range from 4-60 years
depending upon its usage

5. Supply
Nuclear energy is widely
available, has huge reserves
and expected to last for
another 100 years while
coal, oil and natural gas are
limited and are expected to
vanish soon.

6. Easy to Transport
Production of nuclear energy
needs very less amount of raw
material. Only about 28 g of
Uranium releases as much energy
as produced from 100 metric tons
of coal. Since, it requires in small
quantities, transportation fuel is
much easier than fossil fuels.

1. Radioactive waste
When the Uranium has finished splitting, the
resulting radioactive byproducts need to be
removed.
Disadvantages of nuclear energy

2. Raw materials
Uranium is naturally unstable element. That's
why, special precautions must be taken during
the mining, transporting and storing of the
Uranium.

3. Fuel Availability
Unlike fossil fuels which are available to most of
the countries, Uranium is very rare resource and
exist in only few of the countries

4. Non-renewable Energy
Nuclear energy is an alternative energy but not a
renewable energy, as Uranium is non-renewable

5. Hot Target for Militants
Nuclear energy has immense power. Today,
nuclear energy is used to make weapons. If
these weapons go into the wrong hands, that
could be the end of this world.

 A nuclear reactor produces and
controls the release of energy
from splitting the atoms of
certain elements.
 The energy released is used as
heat to make steam to generate
electricity.
NUCLEAR REACTOR

Types of Nuclear Reactor
Neutrons , generated during nuclear fission
reactions to produce radioisotopes, that are going to
be used in other applications of nuclear energy or
materials.
NUCLEAR REASERCH REACTOR

 These are based on the use of thermal energy generated in fission reactions.
 This reactor is used to generate the electricity in power plant.
TYPES OF NUCLEAR REACTOR
NUCLEAR POWER PLANT

Pressurized water Reactor (PWR)
 PWR is the most used in the world.
 This nuclear reactor uses enriched Uranium as oxide form as nuclear
fuel.
 Water under high pressure can evaporate without reaching the
boiling point. i.e. at temperature greater than 100c.
TYPES OF NUCLEAR REACTOR

Boiling Water Reactor (BWR)
•BWR is also used frequently.
•Water is used as coolant and moderator.
•Nuclear fuel is enriched Uranium in oxide form.
•Thermal energy generated by the chain reaction is
used to boil water.
TYPES OF
NUCLEAR
REACTOR

Requirement of a good fuel
Moderate ignition temperature.
Low moisture content.
Combustion should be controllable.
Easy to transport and readily available at
low cost.

Principle of Combustion
 Combustion refers to the rapid oxidation of fuel
accompanied by the production of heat, or heat and light.
Complete combustion of a fuel is possible only in the
presence of an adequate supply of oxygen.
COM BUST ION

3T’S of combustion
The objective of good combustion is to release all of
the heat in the fuel. This is accomplished by
controlling the "three T's" of combustion which are
(1)Temperature high enough to ignite and maintain
ignition of the fuel
(2) Turbulence or intimate mixing of the fuel and
oxygen, and
(3) Time sufficient for complete combustion

No smoke or ash after
combustion
High thermal efficiency
High calorific value
Advantages of gaseous fuel

Disadvantages of gaseous fuel
Highly inflammable so
higher chances for fire
hazards are high
Since gas occupy large
Volume , they require
Large storages tanks

No ash after burning
Require less storage space
High calorific value
Combustion is uniform
Advantages
of liquid fuel

Comparatively costlier
Evaporate during storage
Unpleasant odour during
incomplete combustion
Special type of burners are required
for effective combustion
Dis
Advantage
s of liquid
fuel

 Crude petroleum is defined
as a naturally occurring
mixture, consisting of
hydrocarbons and derivatives
of hydrocarbons which is
removed from the earth in
liquid state.
 Petroleum (Petra=rock,
oleum=oil ) also known as
rock oil or mineral oil.

 Petroleum is formed from the fossilized remains of
ancient plants and animals by exposure to high heat
 And pressure in the absence of oxygen in the earth’s
crust over hundreds of millions of years.
 Petroleum is extract from underground deposits at a
depth of 500-1500 feet at various places.

Composition of typical crude oil
z zz z83-87%
HYDROGEN
11-14%
NITROGEN 0-05%
CARBON

The crude petroleum falls into three main classes:
1. The first yields on distillation a residue consisting
mainly of paraffin wax and is known as a paraffin
base crude.
2. The second leaves a black, lustrous residue of
asphalt, and is known as an asphalt-base crude.
3. The third, leaving both asphalt and paraffin as a
residue, is known as a mixed-base crude.
CLASSIFICATION

• Nearly all crude petroleum contain nitrogen and
sulfur.
 The nitrogen may vary from only a trace up to 1
percent and over and is practically always present in
the form of complex organic bases.
 Sulfur, though rarely absent, is usually present in
only small amounts.
 Crystalline sulfur also has been separated from a
number of crude petroleum.
COMPOSITION

Compounds found in petroleum
• CnH2n+2.
• CnH2n
• CnH2n-2
• CnH2n-1
• CnH2n-6
• CnH2n-8
• CnH2n-10
• CnH2n-12
• CnH2n-14

Uses
• Transportation
• Lubricants
Of
• Heating & lighting
• Industrial power
petroleum
• Petro-chemical industry
• Use of by-products

1. The manufacturing process of gasoline
2. Fractional distillation
3. Refining petroleum
4. Reforming of petrol
5. knocking

2. After a possible reservoir is found the
area must e test drill.
Core sample are taken to confirm rock
formation.
Sample are chemically analyze.
Exploration
1. The first step is to find
petroleum(Parent ingredient).
Crude oil is trapped in areas of porous
rock or reservoir rock

2
0
1
8
3. Crude oil recovered through well into the rock.
Holes are made rotary drillers which bore a hole as water is added.
Water and soil create a thick mud that hold back the oil and prevent it from
“gushing’’.
4. To recover the oil complicated system of pipes is installed into the well.
Natural pressure of reservoir rock brings oil out of well into pipes.
These are connected to a recovery system.

Fractional Distillation
»Long chains of
molecules in crude oil
must be separated
into smaller chains of
refine fuels including
gasoline, in a
petroleum refinery.
This process is called
fractional distillation.

Refining petroleum
• ‘’It is the process of separation of crude oil into different useful
fractions on the basis of their B.P’’.
It is done by two processes.
1.Cracking 2.polymerization

• It is the process of decomposition of higher molecules(higher
boiling) into lower molecular weight hydrocarbons.
• Cracking process involves breaking of C-C and C-H bond
• It produces low alkanes and alkenes.
• A small amount of hydrogen and hydrogen are also produced.

2.Catalytic cracking:
Carried out in the presence of a
catalyst(Al2O3+SiO2) at much
lower temperature and
pressure.
1. Thermal cracking:
Carried out at high
temperature and pressure
in the absence of
catalyst.

• The increase in octane number of straight run gasoline occurs
through structural modifications such as conversion of
straight hydrocarbon into branched, cyclic, and aromatic
hydrocarbons.
Reforming process:
• The straight run gasoline is preheated to remove S and N
content to avoid Pt catalyst being poisoned.
• Mixed with hydrogen and preheated to 5000 C.

Reforming reactions
•Isomerization:
The conversion of straight chain hydrocarbon into
branched chain.
•Dehydrogenation:
dehydrogenation of cycloalkanes to produce
aromatic compounds.

• In an internal combustion engine
sharp sound caused by premature
combustion of parts of compressed
air-fuel mixture in the cylinder.
Cause of knocking:
• In properly functioning engine charge
burns with flame front progressing
smoothly from point of ignition across
combustion chamber.

• By a suitable change in engine
design.
• Using anti-knocking agent.
• Using high rating gasoline.

chemistry of fuels

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