1.INTRODUCTION

Isopropanol (IPA) is one of the most widely used solvents in the world; also used as a

chemical intermediate. IPA is a colorless, flammable liquid with a characteristic alcohol /

acetone-like odor. It mixes completely with most solvents, including water. One well-

known yet relatively small use for IPA is ―rubbing alcohol,‖ which is a mixture of IPA

and water and can be purchased in many pharmacies and grocery stores.

Global Production

Global IPA production capacity reached 2,153 thousand metric tons (4,747 million

pounds) in 2003, although global capacity use was roughly 80%. Approximately, 74% of

the global IPA capacity is concentrated in the United States, Western Europe and Japan.

Dow produced approximately 12% of the IPA in 2003 at its site in Texas City, Texas,

where it has 411 thousand metric tons (906 million pounds) capacity. The biggest

international companies that produce isopropyl alcohol are as follows:

PRODUCER CAPACITY [*]

Dow, Texas City, Tex. 550

Equistar, Channelview, Tex. 65

ExxonMobil, Baton Rouge, La. 660

Shell, Deer Park, Tex. 600

Total 1,875

* Millions of pounds per year of crude isopropyl alcohol (IPA). All of the above companies,

except Equistar, produce IPA by sulfuric acid oxidation of propylene and all have captive

propylene

The global market for isopropanol remains oversupplied, with flat demand growth in

Europe and the US but stronger growth in Asia. Hence global demand is expected to

grow at only 2-2.5%/year.

Manufacturing Processes

Two processes are mainly used to produce IPA. i.A two-step (indirect) hydrogenation

and then hydrolysis of a petroleum product, propylene, using acid and water. ii. A one-

step (direct) hydrogenation of a petroleum product, propylene, with an acid catalyst.

Chinese Technology

A new technology developed by Dalian Institute of Chemistry and Physics for the production of

isopropanol through solid acid catalysis has been approved by the Chinese Academy of Sciences.

The process allows energy consumption to be reduced by 20-30% and raw material usage to be

lowered by 10-20%. A 30,000 tonne/y isopropanol unit is planned by Shandong Dongqing Haike

Chemical (Group) Co Ltd. China consumes over 200,000 tonne/y isopropanol, mostly for use in

coatings, paint, inks, pesticides and drugs. The country has a capacity to produce 100,000 tonne/y

and imports are rising by 10%/y. China expects demand to rise by 5-8%/y over the next few years

and total 235,000 tonnes in 2010.

Indian Scenario

Deepak Fertilisers & Chemicals

Deepak Fertilisers and Petrochemicals Corporation Limited has set up India's largest

plant for producing Isopropyl Alcohol with an installed capacity of 70,000 MT per year

at Taloja near Mumbai.

International Quality Isopropyl Alcohol is manufactured using the direct hydration

process, which is an extremely efficient and environmental-friendly process. It produces

a sparkling colourless product of high purity with no undesirable odour or by-product

formation. The product meets International Standards for use in pharmaceuticals,

agrochemicals, speciality chemicals and other critical applications.

Total Production in India: Reliance Industries Limited also manufactures isopropyl

alcohol with a plant capacity of 30,000 Tons/Annum. The total production in India is

100,000 Tones per annum.

Isopropyl Alcohol is used in the following Products / Industries in India:

Pharmaceuticals Speciality Chemicals

Anti-freeze Rubber Chemicals

Lubes Inks

Agrochemicals Paints

Metal Treatment Fuel Additives

Isopropyl Amines Disinfectants

Indicative Specifications

Properties Specifications Test Method

Purity 99.7% to 99.9%

W/w GC

Residue 12 PPM W/W Max IS 517 1986

Water Content 650 PPM W/W Max ASTM D

1364

Miscibility with Water Complete ASTM D

1722

Acidity as Acetic Acid 10 PPM W/W Max ASTM D

1613

Color Hazen Units 10 Max ASTM D

1209

Distillation Range 81.5 to 83 ASTM D

1078

Specific Gravity @

25oC

0.782 - 0.784 ASTM D 891

Synonyms

Isopropyl Alcohol, Isopropanol, 2-Propanol, IPA, Propyl Alcohol, 2-Propyl alcohol,

Propan-2-ol, Dimethyl carbinol, 1-Methulethanol, 2-Hydroxy propan, 2-Hydroxy

propane. In this report, the synonyms of isopropy alcohol, IPA and propanol are used.

2. PROPERTIES & USES OF ISOPROPANOL

Isopropyl alcohol is a colorless, volatile, flammable liquid. Its odor is slight resembling a

mixture of ethyl alcohol and acetone. Unlike ethyl alcohol, it has a bitter, unpotable taste.

The physical and chemical properties of isopropyl alcohol reflect its secondary hydroxyl

functionality. For example, it’s boiling and flash points are lower than n-propyl alcohol,

whereas its vapor pressure and freezing point are significantly higher. Thus, isopropyl

alcohol boils only 4 0C higher than ethyl alcohol and posses similar solubility properties,

which accounts for the competition between these two products in many solvent

applications. Table 2.1 gives the physical propertiesfor anhydrous and 91% grades.

Table 2.1 Physical Properties of Isopropanol

Anhydrous 91%

Molecular weight 60.10 60.10

Boiling point ( at 101.3 kPa), 0C 82.3 80.4

Freezing point, 0C -88.5 -50

Specific gravity, 20/200C 0.7861 0.8179

Density at 200C, g/cm

3 0.7849

Surface tension (at 200C) ,mN/m 0.0213 0.0214

Specific heat ( liquid at 200C), J/(kg.K) 2510.4

Refractive index 1.3772

Heat of combustion ( at 25 0C), kJ/mol 2005.8

Latent heat of vaporization

( at 101.3 kPa) kJ/mol 39.8

Vapor pressure at 20 0C, kPa 4.4 4.5

Critical temperature, 0C 235.2

Critical pressure aty 20 0C, kPa 2760

Viscosity, mPa

At 0 0C 4.6

At 20 0C 2.4

At 40 0C 1.4 2.1

Solubility ( at 20 0C)

In water complete complete

Flammability limit in air, Vol%

Lower 2.02

Upper 7.99

Flash point, 0C

Tag open cup 17.2 21.7

Closed cup 11.7 18.3

Chemical Properties

Most of the isopropyl alcohol chemistry involves the introduction of the isopropyl or

isopropxy group into other organic molecules. The use of isopropyl alcohol for this

purpose accounts for 60% of its production. Much of the production is for the

manufacture of agricultural chemicals, pharmaceuticals, process catalysts, and solvents.

Isopropyl alcohol undergoes reactions typical of an active secondary alcohol. It can be

dehydrogenated, oxidized, esterified, eherified, aminated, halogenated, or otherwise

modified at this site more readily than primary alcohols, eg, n-propyl alcohol or ethyl

alcohol. Manufacture of the commercially important aluminum isopropoxide and

isopropyl halides illustrates this reactivity. The former reaction in volves replacement of

the hydrogen atom of the group with concomitant hydrogen evolution and, in the latter,

the hydroxyl group is displaced. Thus, aluminum isopropoxide is produced in

quantitative yield by refluxing isopropyl alcohol with aluminum turnings.

6CH3-CHOH-CH3+ 2 Al [(CH3)2CHO]3Al +3 H2

Catalytic amounts of mercuric chloride are usually employed in this preparation.

Aluminum isopropoxide is a useful Meerwein-Ponndorf-Verley reducing agent in certain

ester exchange reactions and is a precursor for aluminum glycinate, a buffering agent.

Displacement of the hydroxyl group is exemplified by the production of isopropyl

halides, eg, isopropyl bromide, by, refluxing isopropyl alcohol with a halogen acid, eg,

hydrobromic acid.

CH3-CHOH-CH3 + HBr (CH3)2CHBr + H2O

The order of reactivity with acid is HI > HBr >HCl. Reaction with hydrochloric acid to

form isopropyl chloride is facilitated by a zinc chloride catalyst.

Esterification

Isopropyl alcohol is esterified readily by treatment with carboxylic acids in the presence

of an acidic catalyst, eg, p-toluenesulfonic acid. An equilibrium is established in the

reaction.

RCO2H + CH3-CHOH-CH3 RCO2 CH(CH3 )2 + H2O

The equilibrium reaction is typically carried out at 100-1600C, 101.3kPa and with an

excess of alcohol. Energy is supplied to remove the water as an azeotrope, thus forcing

the reaction I the desired direction. Excess alcohol is distilled and recycled, and yields of

ester are nearly quantitative. For, example isopropyl acetate can be prepared by the

reaction of isopropyl alcohol with acetic acid in the presence of sulfuric acid catalyst and

toluene as the azeotroping agent. Esterification of isopropyl alcohol with myristric acid

forms isopropyl myristate, which is an emollient and lubricant in various cosmetic

products and topical medicinals. A jellied product is marketed as Estergel.

Xanthate esters are prepared by reaction of isopropyl alcohol with carbon disulfide.

Isopropyl xanthates have wide use in mineral flotation process, and sodium isopropyl

xanthate, is a useful herbicide for bean and pea fields.

Etherification

Glycol ethers can be prepared from isopropyl alcohol by reaction with olefin oxides, eg,

ethylene or propylene oxide. Reaction is generally catalyzed by an alkali hydroxide.

O

CH3-CHOH-CH3 + CH2 CH2 KOH

(CH3)2CHOCH2 CH2OH

Dehydrogenation

Isopropyl alcohol can be catalytically dehydrogenated by a wide variety of catalysts in

high conversions(75-90 mol%) in endothermic vapor phase process. Operation at 300-

500 0C and moderate pressures (2.04 atm) provides acetone in yields up to 90 mol%. The

most useful catalyst contain Cu, Zn and Ni either alone, as oxides, or in combinations on

inert supports.

CH3-CHOH-CH3 Zno catakyst CH3-CO-CH3 + H2

Oxidation

Isopropyl alcohol can be catalytically oxidized with air or oxygen at high temperatures to

give acetone and water.

CH3-CHOH-CH3 + ½ O2 CH3-CO-CH3 + H2O

The catalysts are of the same general type as those used for dehydrogenation processes.

In contrast to dehydrogenation, oxidation is highly exothermic at 295 0C

Isoprolpyl alcohol can be partially oxidized by a noncatalytic, liquid phase process at low

temperatures and pressure to produce hydrogen peroxide and acetone.

CH3-CHOH-CH3 + O2 CH3-CO-CH3 + H2O2

Amination

Isopropyl alcohol can be aminated by either ammonlysis in the presence of dehydration

catalysts or reductive ammonolysis with hydrogenation catalysts. Both methods produce

two amines: isopropylamine and diisopropylamine. Virtually no tridistributed amine, ie,

triisopropylamine is produced. The ratio of mono to diisopropylamine produced depends

in the molar ratio of isopropyl alcohol and ammonia employed; molar ratios of ammonia

and hydrogen to alcohol are 2:1 -5:1

CH3-CHOH-CH3 + NH3 (CH3)2 CH NH2 + H2O

(CH3)2 CH NH2 + CH3-CHOH-CH3 catalyst

[(CH3)2 CH ]2 NH2 + H2O

Halogenation

Normally halopropane derivatives are prepared from isopropyl alcohol most

economically by reaction with the corresponding acid halides. However, under the

appropriate conditions, other reagents, eg. Phosphorous halides and elemental halogen

also react with replacement of the hydroxyl group to give the halide.

3 CH3-CHOH-CH3 + PBr3 3 (CH3)2 CHBr + H3 PO4

Halogenations of isopropyl alcohol in aqueous solution results in concomitant oxidation.

Miscellaneous reactions

Several reactions of potential commercial significance include acylation by ketone.

CH3-CHOH-CH3 + CH2-CO CH3-CO2 CH-(CH3)2

And the ritter reaction to prepare N-isopropylacrylamide from acrylonitrile and

isopropylalcohol.

CH2-CH-CN+(CH3)2CHOH CH2=CHCONHCHCH3

Table 2.2:Thermodynamic properties

Phase behavior

Triple point 184.9 K (–88.2 °C), ? Pa

Critical point

508.7 K (235.6 °C),

5370 kPa

Std enthalpy change

of fusion, ΔfusHo

5.28 kJ/mol

Std entropy change

of fusion, ΔfusSo

28.6 J/(mol·K)

Std enthalpy change

of vaporization, ΔvapHo

44.0 kJ/mol

Std entropy change

of vaporization, ΔvapSo

124 J/(mol·K)

Solid properties

Heat capacity, cp 0.212 J/(mol K) at –200°C

Liquid properties

Std enthalpy change

of formation, ΔfHo

liquid –318.2 kJ/mol

Standard molar entropy,

Soliquid

180 J/(mol K)

Heat capacity, cp 154 J/(mol K) at 20°C-

25°C

Gas properties

Std enthalpy change

of formation, ΔfHo

gas –261.1 kJ/mol

Standard molar entropy,

Sogas

333 J/(mol K)

Heat capacity, cp 89.32 J/(mol K) at

25°C

Structure and properties

Index of refraction, nD 1.3776 at 20°C

Dielectric constant, εr 18.23 ε0 at 25 °C

Surface tension 21.7 dyn/cm at 20°C

Viscosity[1]

4.5646 mPa·s at

0°C

2.3703 mPa·s at

20°C 1.3311 mPa·s at

40°C

Vapor-liquid Equilibrium

for Isopropanol/Water[2]

P = 760 mm Hg

BP

Temp.

°C

% by mole isopropanol

liquid vapor

82.2 100.00 100.00

81.48 95.35 93.25

80.70 87.25 83.40

80.37 80.90 77.45

80.23 76.50 73.70

80.11 69.55 69.15

80.16 66.05 67.15

80.15 64.60 66.45

80.31 55.90 62.55

80.38 51.45 60.75

80.67 44.60 59.20

80.90 38.35 57.00

81.28 29.80 55.10

81.29 29.75 55.40

81.23 28.35 55.30

81.62 24.50 53.90

81.75 19.35 53.20

81.58 18.95 53.75

81.99 16.65 52.15

82.32 12.15 51.20

82.70 10.00 50.15

84.57 5.70 45.65

88.05 3.65 36.55

93.40 1.60 21.15

95.17 1.15 16.30

100.0 0.00 0.00

13

Table 2.3: Vapor pressure of liquid (CRC Handbook of Chemistry and Physics)

P in mm Hg 1 10 40 100 400 760 1520 3800 7600 15200 30400 45600

T in °C –26.1 2.4 23.8 39.5 67.8 82.5 101.3 130.2 155.7 186.0 220.2 —

Figure 2.1 Vapor pressure curve

Table 2.4: Azeotropes of isopropanol, BP=82.5°C

2nd Component BP of

comp.

BP of

mixture

% by

weight

spef.

grav

with various esters

ethyl acetate 77.1°C 75.3°C 75 0.869

14

isopropyl acetate 91.0°C 81.3°C 40 0.822

with various hydrocarbons

benzene 80.2°C 71.9°C 66.7 0.838

toluene ‡[6]

110.8°C 80.6°C 42

cyclohexane 81.0°C 68.6°C 67.0 0.777

n-pentane 36.2°C 35.5°C 94

n-hexane 68.9°C 62.7°C 77

n-heptane 98.5°C 76.3°C 46

with various alkyl halides

carbon tetrachloride 76.8°C 69.0°C 82 1.344

chloroform 61.1°C 60.8°C 95.8

ethylene chloride 83.7°C 74.7°C 56.5

ethyl iodide 83.7°C 67.1°C 85

n-propyl chloride 46.7°C 46.4°C 97.2

15

n-propyl bromide 71.0°C 66.8°C 79.5

isopropyl bromide 59.8°C 57.8°C 88

n-propyl iodide 102.4°C 79.8°C 58

isopropyl iodide 89.4°C 76.0°C 68

tetrachloroethylene[6]

121.1°C 81.7°C 19.0

with various other solvents

methyl ethyl ketone 79.0°C 77.5°C 68 0.800

diisopropyl ether 69°C 66.2°C 85.9

nitromethane 101.0°C 79.3°C 70

USES

The uses of isopropyl alcohol are chemical, solvent, and medical.

Chemical:Growth of the use of isopropyl alcohol as a feedstock for the production of

acetone will be influenced by alternative routes to and markets for, the production of

acetone. In addition, isopropyl alcohol is consumed in the production of other chemicals.

Solvent Because of the balance between alcohol, water, and hydrocarbon like

characteristics, isopropyl alcohol is an excellent low cost solvent which is free from the

government regulations and taxes that apply to ethyl alcohol. The lower toxicity of

isopropyl alcohol favors its use over methyl alcohol, even though the former is somewhat

16

higher in cost. Consequently, isopropyl alcohol is used in many consumer products as

well as industrial products and procedures, eg, gasification and extractions. It is a good

solvent for a variety of oils, gums, waxes, resins and alkaloids and consequently, it is

used for preparing cements, primers, varnishes, paints, printing inks, etc.

Isopropyl alcohol is also employed widely as a solvent for cosmetics, eg, lotions,

perfumes, shampoos, skin cleansers, nail polishes, make up removers, deodorants, body

oils, and skin lotions. In cosmetic applications, the acetone like odor of isopropyl alcohol

is masked by the addition of fragrance.

Over 68 aerosol products containing isopropyl alcohol solvent have been reported.

Aerosol formulations include hair sprays, floor detergents, shoe and polishes,

insecticides, burn ointments, window cleaners, waxes and polishes, paints, automotive

products, eg, windshield decier, insect repellents, flea and tick spray, foot fungicide, and

fabric wrinkle remover.

Medical

Isopropyl alcohol also is used as an antiseptic and disinfectant for home, hospital, and

industry. It is about twice as effective as ethyl alcohol in these applications. Rubbing

alcohol, a popular 70 vol% isopropyl alcohol in water mixtures, exemplifies its medical

use. Other examples include 30 vol% isopropyl alcohol solutions for medical liniments,

tinctures of green soap, scalp tonics, and tincture of mercurophen. It is contained in

pharmaceuticals, eg, local anesthetics, tincture of iodine, and bathing solutions for

surgical sutures and dressings. Over 200 uses of isopropyl alcohol have been tabulated.

Propylene Properties

Gas Properties

Molecular weight : 42.08 g/mol

Solid phase

17

Melting point : -185.3 °C

Latent heat of fusion (1,013 bar, at triple point) : 71.34 kJ/kg

Liquid phase

Liquid density (1.013 bar at boiling point) : 613.9 kg/m3

Liquid/gas equivalent (1.013 bar and 15 °C (59 °F)) : 388 vol/vol

Boiling point (1.013 bar) : -47.8 °C

Latent heat of vaporization (1.013 bar at boiling point) : 437.94 kJ/kg

Vapor pressure (at 20 °C or 68 °F) : 10.3 bar

Critical point

Critical temperature : 91 °C

Critical pressure : 46.1 bar

Gaseous phase

Gas density (1.013 bar at boiling point) : 2.365 kg/m3

Gas density (1.013 bar and 15 °C (59 °F)) : 1.81 kg/m3

Compressibility Factor (Z) (1.013 bar and 15 °C (59 °F)) : 0.984

Specific gravity (air = 1) (1.013 bar and 21 °C (70 °F)) : 1.476

Specific volume (1.013 bar and 21 °C (70 °F)) : 0.587 m3/kg

Heat capacity at constant pressure (Cp) (1.013 bar and 15 °C (59 °F)) : 0.062

kJ/(mol.K)

Heat capacity at constant volume (Cv) (1.013 bar and 15 °C (59 °F)) : 0.054

kJ/(mol.K)

Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 15 °C (59 °F)) : 1.156832

Viscosity (1.013 bar and 0 °C (32 °F)) : 0.0000784 Poise

Thermal conductivity (1.013 bar and 0 °C (32 °F)) : 13.984 mW/(m.K)

Miscellaneous

Solubility in water (1.013 bar and 0 °C (32 °F)) : 0.434 vol/vol

Solubility in water (1.013 bar and 20 °C (68 °F)) : 0.23 vol/vol

18

Autoignition temperature : 460 °C

Major Hazards

Major hazard : Fire

Toxicity (Am. Conf. Of Gov. Ind. Hygienists ACGIH 2000 Edition) : Simple

Asphyxiant

Flammability limits in air (STP conditions) : 2.0-11.0 vol%

Odour : Faintly Sweet

Material compatibility

Air Liquide has assembled data on the compatibility of gases with materials to assist you

in evaluating which products to use for a gas system. Although the information has been

compiled from what Air Liquide believes are reliable sources (International Standards:

Compatibility of cylinder and valve materials with gas content; Part 1: ISO 11114-1 (Jul

1998), Part 2: ISO 11114-2 (Mar 2001)), it must be used with extreme caution. No raw

data such as this can cover all conditions of concentration, temperature, humidity,

impurities and aeration. It is therefore recommended that this table is used to choose

possible materials and then more extensive investigation and testing is carried out under

the specific conditions of use. The collected data mainly concern high pressure

applications at ambiant temperature and the safety aspect of material compatibity rather

than the quality aspect.

19

2. DIFFERENT PROCESS FOR PRODUCTION OF ISOPROPANOL

Indirect hydration for manufacture of isopropanol

In the process, crude liquid propylene reacts with sulfuric acid (>60wt%) agitated

reactors at moderate pressure(300-400psig). The isopropyl sulfate esters form and are

maintained in the liquid state at 20-70 0

C. Low propylene concentrations, ie, 50 wt% can

be tolerated, but concentrations of 65 wt% or higher are preferred to achieve high alcohol

yields; since the reaction is exothermic, cooling helps minimize corrosion.

There are two general operational modes practiced for conducting the reaction. In the two

step strong acid process, separate reactors are used for the propylene absorption and

sulfate ester hydrolysis stages. The reaction occurs at high sulfuric acid concentration (80

wt %) and at 1-1.2 MPa and low temperature and at higher pressure and temperature, ie,

2.5 MPa and 60-65 0

C, respectively. Isopropyl alcohol selectivities in excess of 90 wt%

are obtained from both acid processes.

The sulfate ester hydrolysate is separated in a stripper to gibe a mixture of isopropyl

alcohol, isopropyl ether, and water overhead and dilute sulfuric acid bottoms. The

overhead is neutralized in a scrubbing tower containing sodium hydroxide and is refined

in a two column distillation system. Diisopropyl ether is taken overhead in the first, ie,

ether column. This stream is generally recycled to the reactors to produce additional

isopropyl alcohol by the following equilibrium reaction:

[(CH3)2–CH]2O + H2SO4 (CH3)2–CHOSO3H +(CH3)2–COH

Wet isopropyl alcohol (87.1 wt%; 91 vol%) is taken overhead in the second still. More

than of the charged propylene is converted to isopropyl alcohol in this system.

The bottoms of the stripper (40-60 wt %) are sent to the acid reconcentration unit for

upgrading to the proper acid strength for recycle to the reactor. Because of the associated

high energy requirements, reconcentration of the diluted sulfuric acid is a costly

operation. However, a propylene gas stripping process, which utilizes only a small

20

amount of added water for hydrolysis, has been recently described. In this modification,

the equilibrium quantity of isopropyl alcohol is stripped so that acid is recycled without

reconcentration. Equilibrium is attained rapidly at 50 0

C as isopropyl alcohol is removed

from the hydrolysis mixture. Similarly, the weak sulfuric acid process minimizes

reconcentrating the acid and its associated corrosion and pollution problems.

The 91 vol% alcohol is sold as such or is dehydrated by extractive distillation with

diisopropyl ether or cyclohexane to produce an anhydrous product. The wet isopropyl

alcohol is fed at about the center of a dehydrating column and the azeotroping agent is

fed neat the top. As the ternary azeotrope forms, it is taken overhead, condensed, and the

layers are separated. The upper layer, which is mainly azeotroping agent and alcohol, is

returned to the top of the column as reflux. The lower layer is mostly water. Anhydrous

isopropyl alcohol is removed from the base of the column.

Acid corrosion presents a problem in isopropyl alcohol factoris.steel is sadtisfactory

material of construction for tanks, lines and columns where concentrated acid (>65 wt %)

and moderate temperatures (< 60 0

C) are employed. For the dilute acids and higher

temperatures, however, stainless steel, tantalum, hastelloy and the like are required for

corrosion resistance and to ensure product purity.

The extent of the purification depends on the use requirements which can be from 91 vol

% azeotrope to essence grade. Generally, either intense aqueous extractive distillation or

post treatment by fixed bed absorption with the use of activated carbon, molecular seives

and certain metals on carriers are employed to improve odor and to remove minor

impurities. Essence grade is produced by final distillation in nonferrous (copper)

equipment.

BP CHEMICALS U.K . LTD.

Application: A process for manufacturing isopropanol from 65% purity liquid

propylene. Normal product is 87 wt. % isopropanol. This product can be concentrated to

99 wt. % alcohol by add8ing one more fractionating step.

21

Description: The liquid propylene feedstock, combined with recycled hydrocarbons, is

first absorbed in 75 % sulfuric acid in a series of agitated reactors to form a solution of

diisopropyl sulfate and isopropyl acid sulfate. The sulfated hydrocarbon solution is

converted to an acid solution of isoprpopanol, ether and polymer by hydrolysis reactions

which take place in the hydrolyzer-stripper in the presence of dilution water. These

reaction products are steam stripped from the acid in the same column and leave as

overhead vapors. The vapors are neutralized by contact with caustic solution and then

condensed.

The crude isopropanol is charged to the ether column. The bulk of overhead vapors from

this column is condensed and refluxed to the column. A portion of the liquid is diverted

from the main reflux stream and sent to a decanter for separation. In the decanter the two

liquid layers are separated; the upper layer is very rich in ether, and the lower layer

contains mainly water and small amounts of ether and alcohol. The lower water-rich layer

is refluxed back to the tower continuously along with the main reflux stream going with

to the column. The ether rich layer is pumped back into the reaction system.

The ether column bottoms are pumped to the isopropanol column for recovery of the

main product. The condensed overhead form this column is 87 % solution of isopropanol

in water. Polymer is withdrawn as a side stream from the column and pumped to storage.

From the based of the isopropnol column, water is withdrawn containing only traces of

alcohol.

Operating conditions: the propylene sulphation occurs in the reaction at 300-400 psig.

All other equipment, except for the propylene feed tank, operates at near atmospheric

pressure. No mechanical refrigeration is required.

Yields : 93 to 95% of propylene charged is converted to isopropanol, depending in

propylene content of charge stock.

22

Commercial installations : this process is based in development work carried out by the

Distillers Co Ltd., with recent improvements by Stone & Webster. Commercial plants

using this process are operating in United Kingdom and Japan.

Direct hydration Processes

The acid catalyzed direct hydration of propylene is exothermic and resembles the

preparation of ethanol from ethylene.

CH3–CH=CH2+H2O CH3-CHOH-CH3+12.3 kcal/ mol

The equilibrium can be controlled to favor product alcohol if high pressures and low

temperatures are applied. However, the advantage of low temperature cannot be utilized,

because all known catalysts require moderate temperatures to be effective.

There are three basic processes in commercial operation:

Vapor-phase hydration over a fixed bed catalyst of supported phosphoric acid or

silica supported tungsten oxide with zinc oxide promoter.

Mixed vapor-liquid phase hydration at low temperature(150 0C) and high

pressure(10.13MPa) with a strongly acidic cation-exchange resin catalyst.

Liquid phase hydration at high temperature and high pressure(2700C,20.3MPa) in

the presence of a soluble tungsten catalyst.

.The manufacture of isopropyl alcohol by the direct catalytic hydration of propylene was

begun in 1951 by ICI. The plant used a WO-ZnO3 catalyst supported in SiO2, high

temperature and high pressure.

DEUTSCHE TEXACO AG

Application: Process for the manufacture of isopropanol from 75-92% liquid

propylene and demineralized water.

23

Process description: The direct hydration of propylene to isoproipanol is carried out

using a trickle process with an ion exchange catalyst. Liquid propylene at elevated

pressures is mixed with preheated water, the heat capacity of the water being used for

evaporation of the propylene. The mixture of water and gaseous propylene in

supercritical state is charged to the top of a fixed bed reactor and allowed to trickle

downward concurrently over a bed of ion exchange resin an intensive exchange between

the liquid and gas phases occurs at a temperature between 1300

and 1550 and a pressure

in the range of 60-100 atmospheres. Conversion of the propylene takes place according

to the equation:

CH3–CH=CH2+H2O CH3-CHOH-CH3+12.3 kcal

Aqueous alcohol and non converted propylene are drawn off from the bottom of the

reactor and passed to a high pressure separator where the alcohol containing aqueous

phase is separated from propylene containing gas phase. The liquid phase is then passed

to a low pressure separator. The gas phase is cooled to condense any water and

isopropanol which are returned to the low pressure separator. The crude alcohol solution

bottoms from the low pressure separator are neutralized by treatment with caustic soda

and charged to a prerunning column where diethyl ether is removed overhead. The

bottoms from the distillation are charged to second distillation column where isopropanol

is taken overhead as an aqueous azeotropic mixture. Water from the bottom of this

column is desalted by ion exchange and recycled to the reactor. Dehydration of the

azeotropic mixture of isopropanol and water is carried out in the usual manner using

benzene as an entrainer followed by treatment with activated carbon.

Yield: 1.24 tons isopropanol per ton of propylene charge based on a feed gas with 92%

wt. propylene content. Conversion: 94%wt of propylene to isopropanol ; 3.5% wt. of

isopropylene to diisopropyl ether; 2.5% wt. of propylene not reacted, including losses. In

the reactor pass there is a 75% conversion of the propylene feedstock based on the

propylene content of the feedstock.

24

Economics: A 100,000 metric ton/year plant requires battery limits investment of $7.6

million and uses 1 supervisor and 4 operators.

Commercial installations: A large scale plant has been in operation in Germany for

1 ½ years.

VEBA-CHEMIE WEST GMBH

Application: process for production of isopropanol through direct hydration of 99%

propylene and demineralized water. Isopropanol of by 87.5%weight and absolute

isopropanol are produced.

Description : liquid propylene and water are preheated with the recycle gas from the

rotating gas compressor in heat exchangers by gases from the catalyst furnace, and then

heated in the superheater with high pressure steam to 180-2600C, and passed over the

catalyst under pressure of about 25-26 atm. Here the propylene and water are converted

after the following equation:

CH3–CH=CH2+H2O CH3-CHOH-CH3+12.3 kcal

The gas charged with isopropanol leaving the furnace is cooled in heat exchangers, then

fed to the scrubber where the remaining isopropanol is removed. The unconverted

propylene is then returned to the system through the recycle compressor. The pressure of

the dilute isopropyl alcohol that is collected in the sump of the scrubber is reduced in the

storage tank and then the dilute alcohol is fed to the scrub column where it is freed of the

impurities through extractive distillation with water, and then drawn off as azotrope in the

rectifying column. The azeotrope can be dehydrated in two further columns with benzene

as the dehydrating agent.

25

P-3 P-3

P-5

P-8

P-20

P-41

P-65

P-86

propylene

water

High

pressure

steam

Recycle gas

scrubber

vent

Waste water

Reaction section Purification section

100wt% isopropyl alcohol

Waste

water

87.5wt% iso propyl alcohol

Figure 3.1: Veba-Chemie direct hydration process for the manufacture of isopropyl

alcohol

Utilities:

Power …………………………………………………… 40 kwh/ton IPA

Cooling water……………………………………………..160 m3/ton IPA

Steam (17 atm 3000C)…………………………………….2.2 t/t IPA

Yield (based in converted propylene)……………………...97%

Another advantage of the process is that ethanol can be produced in the same installation

with only slight additional investment and without change of the catalyst which requires

only a special treatment in the plant.

Commercial installations: three large scale installations for the production of

isopropanol and three for production of ethanol are in operation or in planning and

construction stages respectively with an annual capacity of 500,000 tons.

Tokuyama Soda process

A liquid phase variation of the direct hydration was developed by tokuyama soda. The

disadvantages of the gas phase processes are largely avoided by employing a weakly

acidic aqueous catalyst solution of silicotungstate. Preheated propylene, water and

recycled aqueous catalyst solution are pressurized and fed into a reaction chamber. They

react in the liquid state at 270 0C and 20.3 MPa and form aqueous isopropyl alcohol.

Propylene conversions of 60-70% per pass are obtained and selectivity to isopropyl

26

alcohol is 98-99 mol% of converted propylene. The catalyst is recycled and requires very

little replenishment compared to other processes. Corrosion and environmental problems

are also minimized because the catalyst is weak acid and because the system is

completely closed. Because of the low gas recycle ratio, regular commercial propylene of

95% purity can be used as feedstock.

Propylene

water

Recycle catalyst solution

Reaction section

Recycle propylene

Preheater

Heat exchanger

Light ends columnHeavy ends column

Recovery column

Benzene azeotropic

column

Purification column

Fuel Fuel

IPA

seperator

Figure 3.2: Tokuyama Soda’s direct hydration process for the manufacture of

isopropyl alcohol.

Other process

Isopropyl alcohol can be prepared by the liquid phase oxidation of propane with the use

of soluble vanadium catalysts. It is produced incidentally by the reductive condensation

of acetone, and partly it is recovered from fermentation.

Large scale commercial biological production of isopropyl alcohol from carbohydrate

raw materials is being studied. Approximately 50 wt% of C3 chemicals probably will be

supplied by fermentation when carbohydrates become competitive with petroleum

feedstocks.

27

Processes Being Developed for Direct Hydration of propane

The direct functionalisation of propane (instead of propylene) to oxygen and nitrogen

containing intermediates (like propylene oxide, acetone, acrylonitrile, etc.) by reaction

with oxygen is a research challenge with signi®cant potential in the petrochemical

industry. An additional impetus for the direct oxyfunctionalisation of propane is the

present emphasis on the reduction of ole®ns and aromatics in fuels like gasoline. The

latter requires the increasing use of oxygenates like MTBE, TAME, etc. Isopropanol and

diisopropyl ether have been proposed as oxygenate additives for gasoline and diesel but

present methods of their manufacture have limited their usefulness from a cost

standpoint. Isopropanol is currently manufactured by either hydration of propylene or

hydrogenation of acetone. In view of the large worldwide resources of propane, an

economic process for its direct oxidation to isopropanol is desirable.

Two major routes have been reported in the literature for the oxyfunctionalisation of

propane. In an indirect process, propane is oxydehydrogenated to propylene at high

temperatures over metal oxide catalysts and the reactor effluent is passed to the second

propylene oxidation or ammoxidation stages without separation of the intermediate

propylene. Alternatively, paraffin activating catalysts may be combined with compatible

olefin conversion catalysts to produce the corresponding oxygen or nitrogen containing

unsaturated products directly. In contrast to these high temperature operations, the second

route involves the low-temperature functionalisation of propane with O2 using catalysts

which mimic enzymes, like methane monoxygenase or cytochrome P450, in

hydroxylating light alkanes.

New Processes for Dehydration of Isopropanol

Extractive Distillation with DMSO: The usual practice for the separation of Isopropyl

alcohol (IPA) and water mixture in industry is to add cyclohexane (CyH) as an entrainer

via heterogeneous azeotropic distillation. However, it is well-known that heterogeneous

azeotropic distillation can exhibit high parametric sensitivity, multiple steady-state, and

long transient, and nonlinear dynamics, which can limit the operating range of this IPA

dehydration system under feed disturbances. An alternative way for the separation of this

28

mixture with minimum-boiling azeotrope is to use homogeneous azeotropic distillation

by adding an extractive agent. a suitable extractive agent for this system with high

separation factor is dimethyl sulfoxide (DMSO). A process scheme is conceptualized and

is shown in Figure 3.3.

Figure 3.3 : Dehydration of IPA with Dimethyl Sulfoxide

29

Membrane Separation of Isopropanol from Water: Isopropanol has been widely used

in semiconductor and liquid crystal display industries as a waterremoving agent. Used

isopropanol can be recycled by several methods, including pervaporation processes.

Water and isopropanol form an azeotrope at 85.3 wt % isopropanol concentration. We

have investigated pervaporation performances of water–isopropanol mixtures using

modified chitosan composite membranes and the possibility of the hybrid system

consisting of pervaporation and distillation. It was confirmed that a hybrid process

consisting of pervaporation and distillation was superior to the conventional azeotropic

distillation column and the benzene recovery column, whereas the former process was

regarded as an energy-saving processes It is reported that a chitosan/ PAN composite

membrane with specific interfacial bonding between substrate and active layer exhibited

a high separation factor of more than 8000 and flux of around 981 g/m2 h using 80 wt %

isopropanol concentration at 60°C. A few researchers also reported a study on

pervaporation of water/isopropanol mixtures through asymmetric polyetherimide and

chitosan membranes. They showed effects of membrane- casting parameters on the

pervaporation. Their membranes had a separation factor of about 200 and flux of 60 g/m2

h using 0.32 mol fraction (87.6 wt %) isopropanol aqueous solution at 25°C. Chitosan

membrane crosslinked with 1,6-hexamethylene diisocyanate showed an improved

separation factor via crosslinking, and the advantage of a composite membrane over

homogeneous membranes at above 70 wt % feed isopropanol concentrations.