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Module:3
Lecture:15 Butyl alcohol
Dr. N. K. Patel
Module: 3
Lecture: 15
BUTYL ALCOHOL
INTRODUCTION
Butyl alcohol or butanol, C4H9OH is a primary alcohol with 4 carbon
atoms. It belongs to the higher alcohols and branched-chain alcohols.
Butanol can be produced by fermentation of biomass by bacteria.
When produced biologically called as bio-butanol. It is primarily used as a
solvent, as an intermediate in chemical synthesis, and as a fuel. There are four
isomeric structures for butanol, which are n-butanol, sec-butanol, iso-butanol
and tert-butanol. Prior to the 1950s, Clostridium acetobutyricum was used in
industrial fermentation processes producing butanol.
In 1914 Weizmann established a fermentation process in USA using
'Clostridium acetobutyricum' to ferment starchy material. With the outbreak
of World War I demand for acetone increased and large scale fermentation
operation were established in Canada, USA, and India. By 1930's synthetic
production began and fermentation process using molasses instead of grain
were developed.
Commercially, butanol is produced from fossil fuels in the USA
since1950s. Propene is hydroformylated to butyraldehyde which was then
reduced with hydrogen to 1-butanol and/or 2-butanol.
The most wide spread means of producing butanol today is the oxo
process where propylene and syngas (CO and H2) are reacted. The products
were both aldehydes and ketones. Most of the aldehydes produced are
either reduced to alcohol directly or subjected to aldol condensation prior to
hydrogenation. High pressure cobalt catalysts oxo process was
commercialized since 1950. Many variations of the above process have been
developed and commercialized. The next improvement came with the
range of catalyst to phosphine-modified cobalt carbonyls with reduced
operating pressure. Two step rhodium oxo hydrogenation process uses
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Module:3
Lecture:15 Butyl alcohol
Dr. N. K. Patel
rhodium carbonyls as oxo catalyst with reactivities about 102 – 103times
higher than cobalt carbonyls. The process also required less pressure.
MANUFACUTRE
1. By fermentation of starch products
Raw materials
Molasses
Grain
Culture
Nutrients
Water
Reaction
Manufacture process
Molasses diluted with water to a concentration of approximately 5%
sugar, sterilize, cooled to 300C and pumped to fermenter. The fermentation
was carried out for 36 - 48 hrs. The beer containing 1.5 – 2.5% mixed solvents
were taken out from beer column % residue obtained from bottom of
column.
During fermentation carbon dioxide and hydrogen gas were evolved.
The beer treated in a batch column from which water can be removed and
ethyl alcohol, acetone from top of column. The butanol section containing
about 50% water taken out from middle portion of column was created in a
separator column from which butanol was obtained as a bottom product.
Block diagram of manufacturing process
Diagram with process equipment
Animation
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Module:3
Lecture:15 Butyl alcohol
Dr. N. K. Patel
Cereal
grains
Spores on
soil
Cleaned
potatoes
Milling
Potato
mash
Clostridium
acetobutylicum
8% corn
mash
Water
Water
6% corn
mash
Water
Continuous
cookers
(sterilization)
Cooler
Water
Fermenter 1
Water
H2 to
synthesis
Fermenter 2
Water
Distillation
column
Butyl
alcohol
Fractionation
column
Storage
tank
Scurbber
Acetone
CO2 for dry ice
To condenser
Hot air
Cold air
Ethanol
Dried butyl
stillage
Steam
Triple-effect evaporators
Drum drier
Figure: Manufacture of Butyl alcohol by fermentation of starch products
2. From propylene and synthesis gas
Raw materials
Basis: 1000kg butyl alcohol from propylene and synthesis gas
Propylene
540kg
Synthesis gas
405kg
Hydrogen
30kg
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Module:3
Lecture:15 Butyl alcohol
Dr. N. K. Patel
Reaction
Manufacture process
Separater
Circulation turbo
compressor
Fractionating
column
Absorber
Gases to
atmosphere
Recycle
gas
Steam
Vaporizer
Air
Synthesis
gas
Flue
gases
Flue
gases
Carbonyl
formation unit
n-butyl alcohol &
iso-butyl alcohol
Oxidation
column
Reactor
Toluene
Propylene
gas
Compressor
Cobalt
naphthanate
Figure: Manufacture of butyl alcohol from propylene and synthesis gas
Block diagram of manufacturing process
Diagram with process equipment
Animation
The process is also known as “Oxo process”. The liquid propylene and
the fresh synthesis gas at the pressure of 25 – 30MPa were preheated, in heat
exchangers by the heat of the hot reaction mass coming out from the top of
the reactor vessel. Then they were charged in to a reactor where the solution
of cobalt carbonyls in toluene was introduced from carbonyl formation unit.
In reactor aldehydes and by-products were formed at 110 – 1600C and the
heat evolved being dissipated by the boiling water condensate with the
generation of low-pressure steam.
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Module:3
Lecture:15 Butyl alcohol
Dr. N. K. Patel
The heat of the reaction mass was used in heat exchangers and in
separator the liquid was separated and the synthesis gas was recycled
together with some of the unconverted propylene by compressor to the
reaction. The liquid from the separator was throttled to 0.2 – 0.4MPa and
oxidized at 40 – 700C by a small amount of air in oxidation column. In this
column, the oxygen-depleted air passes over into the gas phase together
with CO, H2 and propylene, which were in dissolved state at a high pressure,
and also with the vapours of the aldehydes entrained by the gas. These
vapours were absorbed in absorber by the heavy ends from distillation and
the gases were discharged to the atmosphere or burnt.
The liquid from oxidizing column and absorber was then transferred to
vaporizer. The solution of the cobalt salt from the bottom of this column was
sent to carbonyl-formation unit along with toluene, where the formation of
the carbonyls takes place at 170 – 1800C and 25 – 30MPa in the presence of
a small amount of the CO:H2 mixture and a fresh solution of cobalt
naphthenate. The resultant carbonyls were then recycled to a reactor.
Where the crude aldehydes was taken as overhead from the top of
vapourizer and hydrogenated over a heterogeneous catalyst in
hydrogenator. The resultant isobutyl and n-butyl alcohols mixture were
charged into fractionating column where they were separated from the
bottoms in fractionating column.
Engineering aspects
 Catalyst
Rhodium is very expensive and the modified cobalt catalyst is less
active and causes a side hydrogenation reaction. Therefore, the
overwhelming majority of oxo plants operate in the presence of the
conventional cobalt catalyst. The most promising method with this catalyst is
the vaporization salt method for carrying out the reaction and for the
regeneration of the catalyst.
PROPERTIES
 Molecular formula
 Molecular weight
 Appearance
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: C4H10O
: 74.12gm/mole
: Colourless liquid
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Module:3
Lecture:15 Butyl alcohol





Odour
Boiling point
Melting point
Density
Solubility
Dr. N. K. Patel
: Banana like odour
: 116-1180C
: -900C
: 0.81gm/cm3
: Miscible with water
USES
 85% strength butanol is used in cars designed for petrol without any
change to the engine which have more energy than ethanol
 As a blended additive to diesel fuel to reduce soot emissions
 As a solvent in chemical as well as textile processes
 As a paint thinner and solvent in coating industry
 As the base for perfumes
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