DR. R.K. KHANDALDIRECTOR

WORKSHOP ON HYDROCARBONS

SHRIRAM INSTITUTE FOR INDUSTRIAL RESEARCH19, UNIVERSITY ROAD, DELHI - 110007

Email : sridlhi@vsnl.com Website : www.shriraminstitute.org

OUTLINE

What are they ?

How are they formed ?

Types of Hydrocarbons ?

Characterization of Hydrocarbons ?

Environmental issues

Degradation and Biodegradation ?

Bioremediation ?Everything about Hydrocarbons

Hydrocarbons: What are they ?

Compounds consisting of Carbon & Hydrogen

Covalent bonding

Varying Molecular Weights

Exist in all three states: Gas; Liquid; Solid

Used as fuel, solvent, coating, base material

Non-Renewable

Non-Polar

Petroleum as the source

Non-degradable

Hydrocarbons: What are they

Li

Na

K

Rb

H is first element C is first of IV group; middle of first row of Periodic table

A Range of Chemicals based on C & H

Cs

Be

Mg

Ca

Sr

Ba

B

Al

Ga

In

Tl

C

Si

Ge

Sn

Pb

N

P

As

Sb

Bi

O

S

Se

Te

Po

F

Cl

Br

I

At

He

Ne

Ar

Kr

Xe

Fr Ra

H

Rn

Hydrocarbons: What are they ?

Nonionic in nature

Carbon as a base

Hydrogen as an acid

A big chain length - - - - C- C - C- C - - - -

Completely non-polar; Insoluble in water

Hydrocarbons are naturally occurring

substances; but not renewable !

Hydrocarbons:How are they formed ?

2 Electrons in p orbital

Should loose 2 electrons

like other elements in its

group

Instead bonds covalently

sp3 hybridized

C H

1s2 2s2 2p2 1s1

I group I element; 1 e-

Can exist as Hydride or

Hydrogen derivative

Only one electron to take

part in bonding

Shares to form covalent

bond

Hydrocarbons : How are they formed?

C

1s2 2s2 2p2

H

1s1

Hybridization

p3s

sp3 orbitals s orbital

One carbon has 4 sp3 hybridized orbitals

All four can share one electron each

4 H 1s orbitals combine to form CH4

Hydrocarbons : How are they formed?

No polarization ; no polarity

CH

1s

H

1s

H

1s

H

1s

C C

H

H H HCH4 CH4

Carbon can bond with carbon besides bonding with hydrogen

Since all bonds are formed by sharing of an electron

each from two different orbitals; bond is formed

Saturated alkane molecule CnH2n+2

C C C C

Hydrocarbons : How are they formed?

H H H H

HHHH

Carbon can combine with carbon with more than one bond, when hydrogen atoms are less than those present in alkanes

Unsaturated alkenes (2 bonds) and alkynes ( 3 bonds)

C C H- CC-H

C C C=C

HH

HH

Hydrocarbons : How are they formed?

CnH2n

CnH2n-2

In the nature, compounds of carbon and hydrogen

exist in hydrated form; carbohydrates

All hydrocarbons are formed in the nature through

evolutionary process, but they are non- renewable !

Carbohydrates form by photosynthesis process in plants In addition to C & H, they also contain OCarbohydrates are sources of energy for all living systems

Hydrocarbons : How are they formed ?

Carbohydrates

Hydrocarbons : How are they formed ?

Biomass of plants & living species

• Pressure• Temperature• Microbes• Enzymes

Dehydroxylation

Hydrocarbons

Burried under the earth

Lignite Coal Crude oil Natural gas

< 500 m < 1000 m > 600 m > 600 m

• pH• Catalysts

Petroleum

Micro-organisms or sea animals origin

Occur under earth’s crust 600-6000 m depth

Crude oil/ Petroleum Useful fractions

Remains of dead Micro-organisms

Covered by sand/ clay

Sank at bottom of sea

Petroleum

High temperature, Pressure, Absence of air, Bacterial action

Also called crude oilMixture of 150 different organic compounds

Refining

Petroleum : Occurrence

To oil refinery To supply

line

Rocks

Natural gas

Petroleum

Sea water

Soil

Crude oil well

101 Production of Petrochemicals

GasolinePetroleum Refinery

Petroleum gas (Ethane, propane, butane)

Naphtha

Ref

orm

ing

Methane Ethane Ethene Propane Butane

Hydrogen

Benzene

Toluene

Xylene

Hydrogen

Cyclohexane

Cracking

Thermal

Liquid phase

High boiling lubricating oil

Vapor phase

Low boiling fraction

Low boiling fraction

SteamCatalytic

High hydrocarbons

(Catalyst SiO2 : Al2O3: MnO2)

4 : 1 : 1

Low hydrocarbons

eg. Gasoline production

477 oC

327-377 oC2 atm , catalyst

High hydrocarbonsin vapor phase

Heat, 900oC

Low unsaturated hydrocarbons

Cooled rapidly

17

Cracking/

breaking down/pyrolysis

C10H22 C8H18 + C2H4

497 oC

C-C bonds are broken in random manner

Yield of low boiling fractions (low molecular mass) eg. Gasoline is increased by the cracking of less useful high boiling fraction

Higher hydrocarbons Lower hydrocarbons

Cracking of Hydrocarbons

Cracking

Cracking always leads to low boiling alkenes as by-productsProducts obtained from cracking depends on:

Structure of alkane Pressure Catalysts

C16H34 C8H18 + C8H16

Low boiling volatileHigh boiling

18

n- Hexane- H2

397 oC, Pt

Production of aromatic hydrocarbons like benzene & Toluene

Increase aromaticity hydrocarbons Increase octane number of gasoline

Reforming/ Aromatization

- 3H2cyclohexane benzene

CH3

H2CCH2

CH2

CH2

CH3

19

Liquified Petroleum Gas (LPG) : Low boiling fractions of petroleum

LPG & CNG

Used as domestic & industrial fuel As a source of low molecular mass petrochemicals

Liquified under pressure

Compressed Natural gas (CNG) - Mixture of

Methane 60-90%(main constituent)

Ethane 5-9%

Propane 3-18%

Butane 2-14%

CO2, N2, H2S <1% each

Ethane, Propane , Butane Liquified petroleum gas (main constituents)

Coal : Classification

Element

Carbon

Peat

54

Lignite

84

Bituminous Anthracite

Hydrogen

Oxygen

Nitrogen

Sulphur

5.5

35

2

3.5

64

5

26

1.3

3.3

8

4.5

1.3

1.5

93

3.3

2.0

1.3

0.5

Anthracite is the richest in carbon content

21

Fischer Tropsch process Bergius process

Synthetic Petrol

n C + (n+1)H2(g) CnH2n+2

(coal) (mixture of hydrocarbons)

Iron oxide

200-250 atm 475 oC

Bergius process

C (red hot) + H2O(g) CO + H2 (coke)

n CO + (2n+1) H2 CnH2n+2 + nH2O 5-10 atm,

177-202 oC

Co catalyst

Fractional distillation

Fischer Tropsch process

Coal

Petrol

Water gas

101 Destructive Distillation of Coal

Volatile

Coal

Solid residue

Undissolved gases

Soluble gases

Upper aqueous

layer

Lower layer

Coke ~ 70% by mass

Passed through water

Allowed to standCoal gas ~ 17%; mainly alkanes & alkenes

Ammonical liquor ~ 8-10 % Coal Tar ~ 4-5 %

101 Fractional Distillation of Coal Tar

Light Oil ~ 2.25 %

Coal Tar

Upto 170 °C

Benzene, Toluene, Xylene

170 - 230 °C

Middle Oil ~ 7.5 %

Phenol, Cresol, Naphthalene

Heavy Oil ~ 16.5 %

230 - 270 °C

Anthracene Oil ~ 12 %

270 - 360 °C

Cresol, Naphthalene, Naphthol

Carbon still remains as a residue with ~ 56 % content

Anthracene

Hydrocarbons : TypesCharacteristicsParameter Type

C-C Bond

Single C-C bondDouble C=C bondsTriple CC bonds

AlkanesAlkenesAlkynes

Shape

Straight chainRing structureRing structure with

delocalized e-

Chain length

No. of C-atoms involved <C5C6-C17 >C18

All of them are non-polar

AcyclicCyclicAromatics

GasLiquidSolid

Behaviour

Increases with unsaturation

Decreases with increase in chain length

Increases with increase in chain length

Decreases with branching

Decreases with unsaturation

Parameter

Boiling Point

Reactivity

Hydrocarbons : Behaviour & Properties

26

Why Cyclopropane is very reactive when compared to Cyclohexane ?

C - C - C bond angle = 60o in cyclopropane

C - C - C bond angle = 90o in cyclobutane

C - C - C bond angle = 120o in cyclohexane

Angle strain in cyclopropane = 1/2(109.3 - x) = 1/2(109.3 - 60o) = 24o 40’

Angle strain in cyclobutane = 1/2(109.3 - x) = 1/2(109.3 - 90o) = 9o 6’

Angle strain in cyclohexane = 1/2(109.3 - x) = 1/2(109.3 - 120o) = - 5o16’

Deviation is more in case of cyclopropane making it highly

strained and hence, more reactive than cyclohexane

Hydrocarbons: Characterization

Characterize as per chemistry and with reference to the requirements of the application

Characterization

Compositional Physical properties Chemical properties

IR/UV

GC

GC/MS

LC

LC/MS/MS

Melting point

Boiling point

Vapour pressure

Calorific value

Solubility

Viscosity

Unsaturation

Reactivity

Chain length

Structure

Conformation

Hydrocarbons: Environmental Issues

Certain hydrocarbons are carcinogenic in nature

Aromatics Poly-aromatics

Water should be treated well before being put into

river or water bodies

Degradation & remediation are the key tasks

Carcinogenic hydrocarbons getting into food

chain is a major cause of concern

Water Food Feed

101Hydrocarbons : Environment Issues

Crude oil Spillage getting into water bodies

Process step Pollution

Water Oil

Desalting

Water with salts Oil

Petrochemicals

Water must be treated well before reuse etc.

Contamination of HCs in water

Water contaminated with HCs

Demulsification

Various processes

Effluent Water

101Hydrocarbons: Treatment of Water

Contaminated water

Step

Various types of surfactants play a key role

Check

Deoiling

Reuse

Oil Water

Level of contamination

Right type of surfactants

Compliance as per guidelines

101Hydrocarbons: Water Oil Systems

Selection of suitable surfactant is the key

Oil Water

Oil Hydrophobe

Water Hydrophile

Separation is spontaneous unless solubilized / emulsified

Water in oil Oil in water

Oil Water

Surfactant Surfactant

Hydrocarbons: Degradation

Degradation of hydrocarbons is not easy because of strong bonding of C-C and C-H bonds; no polarization

Hydrocarbons

Degradation

E

Breaking of bonds

Formation of short chain molecules from long chain ones

Ultimately to elements C as CO2 and H as H2O

E Bio or chemical process

Hydrocarbons: Degradation & Biodegradation

Hydrocarbons

Chemical Process

pH Solar Radiations

Biological Process

Adsorption on soils

Solubility in water

Creation of activity

Smaller molecules

Adsorption on soils

Solubility in water

Taken up by microbes

Enzymatic reactions

Smaller molecules

Em

uls

ion

S

olu

bil

isat

ion

Hydrocarbons: Bioremediation

Hydrocarbons

Bio-remediation Phyto-remediation

Isolation of microbes

Picked up by plantsCulturing microbes

eating hydrocarbons

Biodegradation

Emulsion Solution

Plant metabolism

Phyto-remediation

Hydrocarbons: Degradation

The factors can be maneuvered to facilitate degradation of hydrocarbons

Degradation Factors

Solubility in water

Emulsion in water

O/WW/O

Energy absorption from solar radiations

ChemicalsEnvironmentpHCatalysts

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