feedstock - raw materials lect 3

PES Lecture 3

Raw Materials 1

Catalysts, Solvents, Oils

Contents of Lecture• Introduction

• Catalysts• Diluents and solvents: - Petroleum based

hydrocarbon solvents, Acetone, Methanol, Ethanol, Isopropanol, Benzene, Toluene, Xylene, n- Butanol, Cyclohexanol, Cyclohexanone, MEK, MIBK, Di-acetone alcohol, Isophorone, Ethyl acetate, Isopropyl acetate

• Oils

Introduction

Polymer Engineering and Science

• This subject consists of two major divisions: -

• Polymer Manufacturing

• Polymer processing or making the final product from raw polymer.

Polymer Manufacturing

• This involves catalysts, solvents or diluents and monomers.

• Reactor design involves kinetics and other engineering operations such as mixing, fluid mechanics, heat transfer, material of construction, process control etc.

Polymer Processing

• This involves selection of material for a given application, compounding of additives and other ingredients and a proper processing technique such as extrusion, molding, calendaring etc.

• Polymer properties and product design influence the selection of process.

• Decorative processes also play a role.

Catalysts

Catalysts

• Two types of catalysts are used: - Homogeneous and heterogeneous.

• Acid catalyst in ester formation can be considered as an example of homogeneous catalyst.

• In most cases the catalyst is heterogeneous.

• Heterogeneous catalyst is prepared in a very careful way. The shape, size and size distribution play an important role. The porous catalyst have different characteristics as compared to non porous catalysts.

• The surface area offered by catalyst is one of the most important criterion of catalyst.

• Catalysts are many times deposited on suitable inert support with desired size, shape and functional groups.

• In polymerization process, Ziegler-Natta catalysts have played a major role.

• These catalysts made it possible to make Linear polyethylenes namely HDPE (High Density Poly Ethylene) and LLDPE (Linear Low Density Poly Ethylene) at lower temperatures and pressures as compared to those employed for the manufacture of LDPE (Low Density Poly Ethylene) which is branched.

• Ziegler Natta Catalysts

• These are made from salts of multivalent metal elements such as Titanium, Vanadium or Chromium.

• The catalysts are not porous and hence the smaller size catalyst particles are used.

• New generation catalysts are made by depositing the titanium on active support like Magnesium hydroxide.

• Ziegler Natta catalysts made the manufacture of isotactic polypropylene possible.

• Another type of catalysts are Metallocene type.

• These two type of catalysts help to control the stereo regularity and the molecular weight distribution of PP and PE.

• The action of these two catalysts would be discussed later in the manufacture of PP and PE.

Solvents and Diluents

Solvents and Diluents

• Solvents or diluents are used during manufacturing of polymers.

• They may also be part of final formulations of paints, inks or adhesives.

• The solubility of monomer, polymer, the reaction conditions and health issues influence the choice of solvents.

• Recovery of solvent during the manufacture of polymer is very important factor in selecting the solvent.

• Solvents dissolve the polymer / monomer while diluents may only suspend the polymer and reduce the viscosity of medium.

• Viscosity of solution increases as the polymer concentration increases or at a given concentration it increases if molecular weight is higher.

• In good solvents, the solubility of polymers is better and the viscosity is also slightly less.

• When ‘good’ solvents are used, viscosity rise is minimal. However, the removal of solvent by evaporation or by drying at room temperature becomes difficult.

• It is a common practice to use mixture of solvents to suit the needs.

• The vapor pressure of solvent and its boiling point decide the use in a given formulation.

• Some of the materials like benzene, toluene or xylene are solvents as well as starting materials for other monomers or chemicals.

• Most hydrocarbon solvents are separated during crude refining and are a mixture of materials over a boiling point range.

• Some polymers precipitate if the molecular weight increases beyond certain limit. The solution polymerization can yield a control over the molecular weight of a polymer during the manufacturing.

• Low boiling white petroleum distillate These are mixture of hydrocarbons obtained as low boiling distillates. The aromatic content of different grades can change. The difference in the boiling points of extreme constituents may not differ by more than 20 – 25 0C.

• White Spirit is a traditionally used term. The aromatic contents differ from 1 to 20 %. It is fast evaporating solvent used in screen printing inks as well as a cleaning solvent.

• CAS registry numbers for white spirit:

• [8052-41-3] (standard solvent) [64742-82-1] (white spirit type 1) [64741-92-0] (white spirit type 2) [64742-48-9] (white spirit type 3) [64742-88-7] (white spirit type 0)

• Paraffin Oil (Kerosene)

• This is also a mixture obtained during distillation of crude. Its boiling point range is higher than that for white spirit. It dissolves cyclic rubber and ester gum. It is also used in letter press inks.

• The CAS registry number for kerosene is [8008 – 20 – 6]

• High boiling petroleum distillate: - For this solvent category, boiling point is in the range of 250 0C. The aromatic contents are in the range of 25 %. It dissolves ester gums, rosins, phenolics etc.

• Naphthenic solvents: - The solvent action of petroleum distillates is governed by its aromatic contents which can impart some toxicity.

• Controlled hydrogenation of such distillates yields more powerful solvents labeled as naphthenic solvents which are low on the toxicity of sulfur and olefinic contents.

• The solvents of this type are used in inks used for printing on food wrappers due to lower toxicity.

• CAS Registry Number is [64741 – 97 – 5]

• White spirit or kerosene etc are mixture of many compounds. Many solvents are pure chemicals. Some of these are discussed now.

• Acetone: - O=CCH3CH3

• This is a powerful solvent. Its properties are given below.

• CAS registry No [67 – 64 – 1]

• Chemical formula CH3COCH3

• Formula weight 58• Boiling point 56.1 C• Freezing point - 94.6 C• Solubility soluble in water,

ether, alcohols and esters

• Manufacturing process for Acetone:

• Most of acetone is produced as a co product in the manufacturing of phenol from cumene.

• Benzene, C6H6, is alkylated to cumene, C6H5CH (CH3)2, which is oxidized to cumene hydro peroxide, C6H5COOH(CH3)2 which is then cleaved into phenol, C6H5OH, and acetone, CH3COCH3. Details of this process are given under phenol as a monomer.

ReactorCleavage of cumene

hydroperoxideConcentration

α Methyl Styrene

Cumene

H2

Distillation

Tar

Hydrogenation

Block diagram of cumene process for phenol (and acetone) production

Air

Cumene for RecycleAcid

Wash Phenol

Acetone

• Acetone … continued

• It can also be manufactured by catalytic dehydrogenation of isopropyl alcohol.

• This reaction is endothermic and heat is supplied by heating the reactants around 350 C.

• Catalyst is copper, silver, platinum or sulfides of transition metals.

• The hydrogen is used as source of energy or in other reactions.

• Acetone … continued

• The reaction products are cooled to separate non condensable gasses and acetone is purified by distillation.

• CH3CHOHCH3 → CH3COCH3 + H2

• Methanol, (Methyl Alcohol)

• The properties of methanol are given below.

• CAS Registry NO [67 – 56 – 1]

• Chemical Formula CH3OH

• Formula weight 32

• Boiling Point 64.70 C

• Freezing point - 97.10 C

• Solubility Soluble in water, alcohols and esters

• Methanol … continued

• Methyl alcohol or methanol is a one of the largest volume produced chemicals.

• It is used to be called as wood alcohol in earlier days since it was produced by destructive distillation or wood.

• Methanol is a colorless liquid with boiling point of 64.7oc. It has a density of 0.787 gm/cm3 and viscosity of 0.54 centipoises, at 25oc.

• Methanol … continued

• Methanol is one of the important solvents.• It is also a chemical used in the manufacture of

many useful solvents / petrochemicals such as Methyl tertiary butyl ether, MTBE – a fuel additive, Formaldehyde, Methyl esters (Methyl acrylates etc), Methyl amines etc.

• It also acts as antifreeze in natural gas pipelines.

32

Sr. No. Company Catalyst System Typical Atomic Ratios

1 Lurgi Cu-Zn-V

Cu-Mn-V

61 : 30 : 9

48 : 30 : 22

2 ICI Cu-Zn-Al

Cu-Zn-Al

61 : 30 : 9

64 : 23 : 13

3 Haldor Topsoe Cu-Zn-Cr 37 : 15 : 48

4 DuPont Cu-Zn-Al 50 : 19 :31

5 BASF Cu-Zn-Al

Cu-Zn-Al-Cr-Mn

32 : 42 : 26

38 : 38 : 0.4 : 12 : 12

6 Mitsubishi Gas Chemical Cu-Zn-Mp*

Cu-Zn-Cr

Cu-Zn-B

55 : 43 : 2

55 : 43 : 2

61 : 38 : 1

7 Shell Cu-Zn-Ag

Cu-Zn-RE*

61 : 24 : 15

71 : 24 : 5

8 United Catalysts Cu-Zn-Al 62 : 21 : 17

9 Ammonia Casale Cu-Zn-Al-Cr 29 : 47 : 6 : 18

Patent Survey of Representative Types of Copper-Based Methanol Synthesis Catalysts

*Mp = Metal Phosphates, M = Li, Cu, Mg, Co, Zn, Mn, Fe

*RE = Rare earth oxides

• Manufacturing Process for Methanol:• Catalytic reforming of methane (natural gas) or

similar feedstock produces methanol. The feedstock is converted into syn gas (mixture of carbon monoxide and hydrogen) and then reformed into methane.

• CO + 2H2 → CH3OH

• CO2 + 3H2 → CH3OH + H2O

• The catalyst is specially designed copper – zinc – aluminum system. Reaction pressure is ~ 50 to 100 atmospheres and temperature is 220 – 250 C.

feed

oxygenPartial oxidation

Process boiler

steam

Carbon recovery

Sulfur recoveryCO Shift reactionRemoval of Carbon dioxide

Heat recovery Steam

Compressor and methanol synthesis

Block diagram for the manufacture of Methanol

• Ethanol, (Ethyl alcohol)• This has been a well known solvent for more

than 100 years. It is normally mixed with 4 to 5 % of methanol and is known as denatured spirit. Its properties are given below. It is used in paints, inks and cosmetics.

• CAS registry No [64 – 17 – 5]• Chemical formula CH3CH2OH, • Formula weight 46• Boiling point 78.320 C• Freezing point - 114.10 C• Solubility soluble in water, other

alcohols, esters & organic solvents

• Manufacturing process for Ethanol:• Industrially it can be produced from direct

or indirect hydration of ethylene. Indirect hydration uses sulfuric acid. The reaction is shown here.

• C2H4 + H2SO4 → CH3CH2OSO3H• 2C2H4 + H2SO4 → (CH3CH2O)2SO4

• CH3CH2OSO3H + H2O → CH3CH2OH + H2SO4

• (CH3CH2O)2SO4 + 2H2O → 2CH3CH2OH + H2SO4

Ethylene

Sulfuric acid

Reactor

Waste gases for recovery / disposal

Hydrolyser

water

Crude ethanol and dilute acid for recovery

Block diagram for the manufacture of ethyl alcohol

• Ethanol … continued

• In direct hydration process, acidic catalyst is used. Ether and acetaldehyde are produced as by-products. The reaction is given below:

• C2H4 + H2O → CH3CH2OH• (This reaction is reversible. In countries where

ethanol from fermentation route is abundantly available, ethylene is produced from ethanol for making polyethylene.)

• Fermentation of sugar molasses or starch can produce ethanol. This route is known for a very long time. The synthetic route is developed due to economic considerations

• Isopropyl Alcohol: CHOHCH3CH3

• This is used extensively in inks and cosmetics. Its properties are given below.

• CAS registry No [67 – 63 – 0]

• Chemical formula CH3CHOHCH3

• Formula weight 60• Boiling point 82.30 C• Freezing point - 88.50 C• Solubility soluble in water, alcohols

and other organic solvents

• Manufacturing processes for Isopropanol:• Hydration of propylene is the industrial process.

This is similar to the one described for ethanol from ethylene.

• Indirect hydration:• 2CH2=CHCH3 + H2SO4 → {(CH3)2CHO}2SO4

• {(CH3)2CHO}2SO4 + H2O → (CH3)=CHOH + H2SO4

• Direct hydration:• CH2=CHCH3 + H2O →(CH3)2CHOH• In another process, acetone is hydrogenated to

isopropyl alcohol.• (CH3)2CO + H2 → (CH3)2CHOH

Propylene

Sulfuric acid

Reactor

Waste gases for recovery / disposal

Hydrolyser

water

Crude isopropanol and dilute acid for recovery

Block diagram for the manufacture of isopropyl alcohol

• Benzene, Toluene and Xylene:• These are clubbed together because their

manufacturing process is similar and all these are aromatic solvents.

• Benzene, Toluene and Xylene (BTX) are manufactured in refining of crude. No flow sheet is, therefore, provided.

• Benzene forms azeotropes with many compounds and hence it is not practical to distil it directly from the crude.

• It is one of the building blocks for number of organic chemicals.

• Benzene, Toluene, Xylene … continued

• Until 1940, destructive distillation of coal was the main source of benzene, toluene and xylene. Now the main source is crude petroleum. Catalytic reforming of naphtha or similar feedstock is the main process where benzene, toluene and xylenes are formed in different proportions. The output of these three can be altered depending upon the demand for a particular chemical by changing operating conditions of the reformer accordingly

• Benzene:

• CAS Registry No [71 – 43 – 2]

• Chemical formula C6H6


• Boiling point 80.10 C

• Freezing point 5.50 C

• Solubility Soluble in organic solvents

• Toluene:


• Chemical Formula C6H5CH3

• Formula weight 92• Boiling point 110.60 C• Freezing point - 86.70 C• Solubility Soluble in organic

solvents

• Xylene• There are three isomers of xylene, namely ortho

xylene, meta xylene and para xylene depending upon the positions of CH3 groups.

• In ortho two CH3 groups are at 1,2 position, in meta xylene, two CH3 groups are at 1,3 positions, while that for para it is 1,4.

• The para xylene is also a raw material for the manufacturing of para terephthalic acid. The properties of xylene are given here.

• Properties of three isomers are given below.

• Xylene o-xylene m-xylene p-xylene• CAS No [95 – 47 -6] [108 – 38 – 7] [106 – 42 – 3]• Boiling point, 144 139 138• Freezing point, - 25 - 48 13

• (Boiling and freezing points in 0C)

• The Chemical formula for all isomers is C6H4(CH3)2

• The formula weight is 106• They are soluble in organic solvents.

• Butyl alcohol, n- butanol• CAS Registry Number [71 – 36 – 3]

• Chemical formula CH3(CH2)3OH




• Solubility soluble in alcohol, organic solvents and

limited quantity in water

• Manufacturing process for n-butanol:

• From propylene, n- butyraldehyde is obtained in Oxo process. The iso-butyraldehyde is also produced as a co product and it is separated from the n – butyraldehyde.

• Vapor phase hydrogenation of n – butyraldehyde over a catalyst system, of CuO – ZnO – NiO at temperature around 1950 C and pressure of 7 atmosphere produces n butanol.

• It can also be produced by fermentation of molasses using specific microbes.

Vapor phase reactorn-butarldehyde

Hydrogen

Butanol for purification

Block diagram for the manufacture of butanol

• HEXANE

• This is a very useful solvent/ diluent used in plastic industry.

• It is inert. It is also used in extraction processes to recover chemicals, oils etc.

• It is separated from petroleum fractions and purified by distillation.

• Properties of Hexane are: -


• Chemical Formula C6H14


• Boiling Point 69.10 C

• Melting Point - 95.10 C


• HEPTANE

• This is a solvent used in polymer industry.

• It is also used in extraction of chemicals, and oils from seeds.

• It is an inert solvent.

• This is also separated from petroleum fractions and purified by distillation.

• Properties of Heptane are given below.


• Chemical Formula C7H16





• Cyclohexanol and Cyclohexanone

• These are considered together due to similarity in manufacturing process. Properties of these two materials are given here.

• Cyclohexanol• CAS registry number [108 – 93 0]• Chemical formula C6H11OH, (CH2)5CHOH

• Formula weight 100• Boiling point 161.10 C• Freezing point 25.10 C• Solubility Limited solubility in

water: soluble in organic solvents.

• colorless liquid with odor similar to that of camphor.

• Cyclohexanone:• CAS registry number [108 – 94 – 1]

• Chemical formula C6H10O, (CH2)5C=O

• Formula weight 98• Boiling point 156.70 C• Freezing point - 47.10 C• Solubility Similar to cyclohexanol• liquid having odor similar to that of pepper mint

and acetone.• Used for manufacture of caprolactam.

• Manufacturing process for cyclohexanol and cyclohexanone:

• Catalytic air oxidation of cyclohexane produces a mixture of cyclohexanone (ketone) and cyclohexanol (alcohol), known as KA mixture. The two are separated and purified to obtain cyclohexanone and cyclohexanol.

• Cyclohexanol can also be produced by hydrogenation of phenol.

Oxidation reactor

Cyclohaxane

AirCyclohexanol and

cyclohexanone(KA mixture)

For separation

Block diagram for the manufacture of cyclohaxnol and cyclohexanone

Methyl Ethyl Ketone, MEK• CAS registry number [78 – 93 – 3]

• Chemical formula CH3 C=OCH3CH2





• Manufacturing process for Methyl Ethyl Ketone, MEK:

• Catalytic dehydrogenation of isobutanol (sec- butanol) yields MEK.

• CH3CHOHCH2CH3 → CH3C=OCH2CH3 + H2

2 Butanol Reactor

Hydrogen to Scrubber

DistillationMEK

Heavy Fractions

Block Diagram for the manufacturing of Methyl Ethyl Ketone, MEK

• Methyl Isobutyl Ketone: (MIBK)• CAS Registry Number [108 – 10 – 1]

• Chemical Formula CH2CH(CH3)2C=OCH3





• MIBK … continued

• MIBK is another powerful ketonic solvent used in coating industry.

• It is obtained from vapor phase catalytic hydrogenation of mesityl oxide which is obtained from acetone.

Acetone Reactor

Alkali Phosphoric acid

Dehydrating column

Mesityl oxide column

Hydrogen

Hydrogenation column

Distillation Column

MIBK

Block diagram for the manufacture of MIBK

Diacetone alcohol • CAS Registry No. [123 – 42 – 2]• Chemical Formula (CH3)3COHC=OCH3

• Formula weight 117• Boiling point 164 C• Freezing point - 47 C• Solubility Soluble in organic

solvents and water• This is a powerful solvent used in coating

industry. It is obtained by alkaline condensation of acetone (Aldol change).

ReactorAcetone

Dilute alkali

Neutralization and separation of

diacetone alcohol

Block diagram for the manufacture of diacetone alcohol

Isophorone• The properties of this material are

• CAS Registry No. [79 – 59 – 1]

• Chemical Formula C9H14O





• Isophorone … continued

• The isophorone is a ketonic solvent.

• It is obtained by alkaline condensation of acetone.

• This material is a powerful solvent used in coating industry.

CH2

C

CH3

CHC====

CH3

CH2

CO

CH3

Acetone High Pressure Reactor

Alkali

cool

Separation column

Isophorone

By-products

Block diagram for the manufacture of isophorone

Ethyl Acetate

• CAS Registry No [141 – 78 – 6]• Chemical formula C4H8O2• Formula weight 88• Boiling point 77.1 C• Freezing point - 83.6 C• Solubility Soluble in organic solvents

• It is obtained by the esterification of acetic acid by ethanol.

• Powerful ester type of solvent used in ink and paint industry.

Isopropyl Acetate• CAS Registry No. [108 – 21 – 4]

• Chemical Formula C5H10O2

• Formula weight 102• Boiling point 89 C• Freezing point - 73 C• Solubility Soluble in organic

solvents

• It is obtained by esterification of isopropyl acetate. This ester type solvent is used in the ink industry.

OILS

• Oils are used in ink and paint industry more often. In plastics industry, it may find use as plasticizers and lubricants. Oils are triglycerides

• CH2COOR1

|• CHCOOR2

|• CH2COOR3

where R1, R2 and R3 are long chains consisting of chain length (C5-C15).

• The hydrocarbon chains may have unsaturation which provides the active sites for polymerization. The unsaturation in oil is expressed in terms of its iodine value. The higher unsaturation imparts higher iodine value.

• Generally the drying oils have iodine value of 140 and above, semi drying oils between 125 to 140 and that for non drying it is less than 125.

• Manufacturing of vegetable oils• Generally oil is produced from seeds or flax by

mechanical expellers and / or by solvent extraction.

• Oil seeds are dried, crushed and ‘cooked’ at about 70 to 80 C. Then they are subjected to hydraulic pressure to separate oil from the seed (kernel as the case may be). Oil is drained (filtered) and the cake which is left behind may be further subjected to solvent extraction.

• The crushed oil seeds may be processed by screw expeller where the oil seeds are forced through a conical grating so that oil exudes and oilcake is extruded from the other end.

• The oil cake can be used as cattle feed or as a fuel.

• The oil cake can be treated with some suitable solvent (hexane, heptane, butanol etc.), to extract remaining oil. In this case, however, the oil cake is not suitable as cattle feed.

• The oil may be further modified to monitor the unsaturation or refined to remove gums or free fatty acids.

• The oils used in polymer industry (mainly paints and inks) include linseed oil, tung oil, oiticia oil, castor oil (dehydrated, hydrogenated), tall oil, coconut oil, tobacco seed oil, cottonseed oil, rice bran oil and many more.

• Soya oil is also used in polymer industry.• If oil is edible, the economic and social issues

compete with each other.• Some fish oils also are used in polymer industry.

The bad odor is the main issue for their limited use.

• Cashew Nut Shell Liquid (CNSL)• CNSL is a monomer obtained as a by product of

cashew industry. It is a naturally occurring substituted phenolic compound.

• It is a greenish yellow viscous liquid found in the soft honeycomb of the shell of cashew nut. It is not oil but it has water repellent properties.

• It can replace phenol in some reactions. CNSL is used in brake liners as well as in some paints and polishes. It is also used as insecticide, fungicide and as an additive in some plastics.

• The cashew nut is attached to the cashew apple. The cashew apple is used in making beverage or as a fruit.

• CNSL is abundantly available in many parts of the world, such as, India, Brazil, Bangladesh, Tanzania, Kenya, tropical regions of Africa and South-East and Far-East Asia.

• The main constituents of CNSL are:

• CNSL is extracted from the nuts by roasting them and filtering the CNSL. The shell can be subjected to hot oil bath also to extract CNSL.

• The roasted shells can be further subjected to solvent extraction to remove the remaining CNSL.

• The shell, after removing the CNSL, is used as fuel.

• The method adapted to extract CNSL depends mainly on tradition.

• Raw CNSL is heated to decrboxylate it and therefore anacardic acid is not present in the commercial CNSL which is used as a monomer in phenolic resins.

• During heating iodine value is reduced due to small degree of polymerization. This enhances the viscosity.

• CNSL is characterized by its viscosity and iodine value.

• Use of inhibitors such as hydroquonone controls the loss of iodine value.

feedstock - raw materials lect 3

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