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Course: Chemical Technology (Organic) Module IV

Lecture 2Synthetic Detergent And

Linear Alkyl Benzene

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LECTURE 2SYNTHETIC DETERGENT AND LINEAR ALKYL

BENZENEDETERGENT

A detergent is a surfactant or a mixture of surfactants having cleaning properties in dilute solutions. Commonly, "detergent" refers to alkylbenzenesulfonates, a family of compounds that are similar to soap but are less affected by hard water.

High detergency in soft and hard water (they do not react with Ca and Mg solution.) Requirement of small quantity Detergency action at low temperature Do not hydrolyses

Table M-IV 2.1: Types of Specialty SurfactantsAnionic Amphoteric Cationic NonionicEther carboxylates Amphoteric acetates Amine Oxide Alkyl polyglucosidesAcylisethionates Betaines and siltainesPhosphate estersSarcosinatesSulfosuccinatesTaurates

Source: Chemical Weekly November 29, P-200, 2011.

During 40’s and 50’s the detergent market was primarily captured by the dodecyl benzene

(DDB), a product formed by alkylation of Benzene with propylene tetramer in a hard detergent

alkylation unit. It was found, however, that the branched structure of the alkyl group was

responsible for the poor biodegradability of the detergent, and the linear alkyl Benzene (LAB)

was introduced in the early 60’s have substantially replaced its counter parts.

Although Linear alkyl benzene is the major detergent being used due its low cost as derived from

petroleum feed, other surfactants used widely are fatty alcohol sulphates(FAS), Fatty alcohol

ether sulphates[FES), fatty alcohol ethoxylates (AE).

Fatty AlcoholsThere has been rapid growth in the use of fatty alcohols due its low toxilogical profile and safe

use, continued substitution of soap by alcohol based surfactants in the personal care industry,

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strong sales of laundary liquids that use higher levels of alcohol based surfactants, displacement

of LAS surfactants by alcohol based surfactants, the substitution of alkyl phenol eythoxylates by

alcohol based surfactants[ Brent, 2004].the global market for fatty alcohol has shown significant

growth. Oleochemical route to alcohols starting from vegetable/animal oils and fats has

dominant share(70%) of global capacity of about 3.3 million tones synthetic alcohol produced

from petrochemically derived ethylene still continues to have a about 30% share [ Chemical

weekly, November 29,2011, p.197]

CLASSIFICATION OF DETERGENT [http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Detergent.html] ANIONIC DETERGENTS:

The detergency of the anionic detergent is vested in the anion. The anion is neutralized with an

alkaline or basic material, to produce full detergency [Kiwi Web]. Typical anionic detergents are

alkylbenzenesulfonates. There are three kinds of anionic detergents: a branched sodium

dodecylbenzenesulfonate, linear sodium dodecylbenzenesulfonate, and soap. The alkylbenzene

portion of these anions is lipophilic and the sulfonate is hydrophilic. Two varieties have been

popularized, those with branched alkyl groups and those with linear alkyl groups. [Smulders et

al., 2002].

CATIONIC DETERGENTS:

The detergency is in the cation, which can be a substantially sized molecule. Strong acids are

used, such as hydrochloric acid to produce the CI anion as the neutralizing agent although in

essence, no neutralization takes place in the manufacturing process [Kiwi Web]. Cationic

detergents are similar to the anionic ones, with a hydrophobic component, but instead of the

anionic sulfonate group, the cationic surfactants have quaternary ammonium as the polar end.

The ammonium center is positively charged. [Smulders et al., 2002].

ETHOXYLATES: Ethoxylates are compounds that have long hydrocarbon chains, but

terminate with (OCH2CH2)nOH group. These groups are not charged, but they are highly

hydrophilic owing to the presence of many oxygen centres.

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NON-IONIC OR ZWITTERIONIC DETERGENTS: This detergent consists of no inonic

constituents which are ionically inert. The vast majority of all non-ionic detergents are

condensation products or ethylene oxide with a hydrophobe. This grop of detergents is

enormous, and the permutation endless. These are characterized by their (net) uncharged,

hydrophilic head groups. They are based on polyoxyethylene (i.e. Tween, Triton and Brij series),

Chaps, glycosides (i.e. octyl-thioglucoside, maltosides), bile acids such as DOC, lipids (HEGAs),

or phosphine oxides. Zwitterionic detergents possess a net zero charge arising from the presence

of equal numbers of +1 and -1 charged chemical groups.

BASIC COMPONENTS OF DETERGENT Detergent (Linear alkyl benzene sulphonate)

Builders: Phosphate (Sodium tripolyphosphate boost detergent powder), citrates,

silicates, carbonates, zeolite

Filters and Processing Aids: Sodium carbonate, sodium sulphonate

Corrosion inhibitors: Sodium silicate

Anti redeposition agent: Carboxy methyl cellulose

Fabric Brightners: Fluoroscent dyes

Bluing: Improve whiteners by counteracting natural yellowing tendency

Antimicrobiol agents: Carbinilides, salicylanilides

Enzymes: Decompose or alter the composition of soil and render the particles more easily

removable.

Some of the enzymes used in detergent are protease,amlases,liapse and celolases. The enzymes

catalyses the breakdown of chemicalds through addition of water and helps in the removal of

soils.[Saini,2001a].Polymers and enzymes play important role in improving the detergency.

Polymers help in soil removal, prevent insoluble salt incrustation work as anti-soil re-deposition,

inhibit dye transfer. Use of optical brightner enhance the brightness and whiteness. processing

aids when added to slurries of detergent powder improve stability and homogeneity of slurries

during mixing and reduce viscosity[Saini, 2001b].

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LINEAR ALKYL BENZENELAB basic raw material for detergent which was introduced in 60's as substitute for non-

biodegradable branched. Other surfactants are alcoholsulphate (AS), alcoholethoxylates (AE),

Secondary alkane sulphonate, and alpha olefin sulphonates. LAB is a clear colourless liquid with

characteristic odour. It is most widely used as the basic raw material for the manufacture of

synthetic detergent. The linear alkyl Benzene produced from the C10 – C13 or C11 – C14 linear

mono olefins are useful detergent intermediate and can be readily sulphonated to yield linear

alkyl benzene sulphonates. These compounds constitute the “active” ingredients of many house

hold detergents. They are surface active compounds (surfactants) which are combined with

various builders (often inorganic salts) to make up a detergent formula.

Linear alkyl benzene (LAB) is the basic raw material for production of most widely used

detergent. Linear alkyl benzene was introduced as substitute for non biodegradable branched

alkyl benzene. Process involved for LAB manufacturing is mention in Table M-IV 2.3.

Although LAB demand grew by 14% per annum during 1984-90, future demand in the country is

projected to increase at a healthy growth rate of 7-8% as against 2-4% worldwide. India and

China with huge population are the largest market for LAB

LAB manufactured in India started in 1985 by IPCL in 1985 followed by Reliance Industries,

Tamilnadu Petro products, Nirma, IOC. Application of LAB in India is mention in Table M-IV

2.2.

• IPCL., Vadodara : 50,000 TPA

• Reliance Industries Patal ganga : 1,00,000 TPA

• Tamil Nadu Petro Products : 1,20,000 TPA

• Nirma Limited : 75,000 TPA

• Indian Oil Corporation, vadodara : 1,20,000 TPA

Total: 4,65,000

Table M-IV 2.2: LAB Application in IndiaApplication Share (%)Consumer Cleaning Products 96.2

a. Synthetic detergents for fabric wash 90.1Popular 68.3Mid-Price 13.3Premium 18.4

b. Scouring products 8.7

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c. Liquid detergents 1.2Industrial & Institutional Cleaners 1.3Other Industrial Application 2.5Non-surfactant Applications( varnish, cablefluid oil, lubricant)

0.1

Total 100Source: Indian Oil Corporation,(Chemical Weekly November 29, P-199, 2011).

Table M-IV 2.3: Process steps in LAB manufacturePrefractionation To obtain C10-C14 range hydrocarbons from kerosene. (n-C10 to n-

C13 for light and n-C11to n-C14 for heavy LAB).The LAB unit requires a very specific feed in terms of carbon number. The prefractionation unit is designed to process a high purity C9 to C15 linear (normal) paraffin feed and to separate out a heart cut with the desired carbon number which will range from n C10 to n13 for light LAB and nc11 – nc14 for heavy LAB.

Hydrotreator To remove sulphur compounds from feed stockThe purpose of this unit is to remove sulfur and nitrogen from the feed without greatly changing its B.P. If not removed, sulfur and nitrogen would poison the sieve in the Molex Unit.

ParaffinSeparation (Parex process)

To remove n-paraffins from kerosene by selective adsorption usingmolecular sieve. The UOP MOLEX process is an effective method of continuously separating normal paraffins from a stream of co- boiling hydrocarbons by means of physically selective adsorption.The feed stock is separated into a high purity normal paraffin fraction at high recoveries and a non-normal paraffin.

Dehydrogenationof Paraffins(Pacol Process)

Dehydrogenation of n-paraffins to olefins.This process dehydrogenates the high purity linear paraffin feed

stock from the pre-fractionation unit into the corresponding non-olefins, suitable as feed stock for the down stream detergent alkylate unit.

Alkylation Alkylation of benzene with olefins to obtain LAB in presence of HF or solid zeolite catalyst

This process alkylates benzene with linear olefins produced by the Pacol unit in the presence of HF acid catalyst to yield linear alkyl benzenes, LAB. The LAB thus produced can be readily sulfonated to form a suitable ingredient for many household detergents. This unit consists of three processing section :

i. Alkylation Sectionii. Fractionation Sectioniii. Acid Regeneration Section

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Figure M-IV 2.1: Pre-fractionation Pre-Treatment and Paraffin Separation

Alkylation Unit

LAB Sulphonation

Figure M-IV 2.2: Manufacture of linear alkyl Benzene Sulponate

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LAB BY SOLID ACID CATALYSTThe conventional catalyst AlCl3, H2SO4 and HF commercially used has the disadvantage of

causing corrosion of equipment as well as waste production. There has been continuous search

for development of non corrosive solid catalyst with similar catalytic properties. Some of the

catalyst which have been developed are SiO2-Al2O3, H-,ontmorillonite, amberlyst, H-Y, H-

Beta, HM [Almeida, 1994]. World LAB capacity was around 3 million tones with nearly

85percent based on HF alkylation, 5percent on the aluminium chloride process, and 10percent on

the newly developed fixed bed alkylation. The fixed bed alkylation was first introduced on

commercial scale in 1995 in Canada by Petresa. Figure M-IV 2.3 gives details for LAB

Manufacture from Fixed Bed Technology.

Figure M-IV 2.3: LAB Manufacture from Fixed Bed Technology

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MANUFACTURING OF DETERGENTSDetergents use a synthetic surfactant in place of the metal fatty acid salts used in soaps.

They are made both in powder and liquid form. Most detergents have soap in their mixture of

ingredients, but it usually functions more as a foam depressant than as a surfactant. Various

processes in manufacturing of detergents is mention in Table M-IV 2.4.

A synthetic detergent, a sodium alkyl sulfate called sodium dodecylsulfate, will be prepared by

reacting dodecyl alcohol (dodecanol) with sulfuric acid.

The resulting dodecylsulfate is converted to the sodium salt by a reaction with sodium hydroxide.

Table M-IV 2.4: Various Processes for Making Detergent

Powder DetergentSlurry making The solid and liquid raw ingredientsare dropped into a large tank known as a

slurry mixer. As the ingredients are added the mixture heats up as a result of two exothermic reactions: the hydration of sodium tripolyphosphate and the reaction between caustic soda and linear alkylbenzenesulphonic acid. The mixture is then further heated to 85oC and stirred until it forms a homogeneous slurry.

Spray drying The slurry is deaerated in a vacuum chamber and then separated by an atomiser into finely divided droplets. These are sprayed into a column of air at 425oC, where they dry instantaneously. The resultant powder is known as ’base powder’, and its exact treatment from this point on depends on the product being made.

Post dosing Other ingredients are now added, and the air blown through the mixture in a fluidiser to mix them into a homogeneous powder. Typical ingredients are

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Soda ash (anhydrous Na2CO3), Bleach (usually sodium perborate. NaBO3), Bleach activator (e.g. tetraacetylethylenediamine), Enzymes (e.g. alkaline protease), Colour and perfume

Liquid DetergentSoap premixmanufacture

Liquid detergent contains soap as well as synthetic surfactants. This is usuallymade first as a premix, then other ingredients are blended into it. This step simply consists of neutralizing fatty acids (rather than fats themselves) with either caustic soda (NaOH) or potassium hydroxide.

Ingredientmixing

All ingredients except enzymes are added and mixed at high temperature. Theingredients used in the liquid detergent manufacture are typically sodium tripolyphosphate, caustic soda, sulphonic acid, perfume and water. The functions of these ingredients have been covered above.

Enzymeaddition

The mixture is cooled and milled, and the enzymes added in powder form.

REFERENCE1. Almeida, 1994

2. Saini,S.K. “ Synyhetic detergent powders: changing trends part I “ chemical weekly

March,20,2001a,p.149

3. Saini,S.K. “ Synthetic detergent powders: changing trends part II “ chemical weekly

March,27,2001b,p.141

4. Brackmann,B., Deutschland,C, Hager,Claus-Dierk, “ Versatility of derived surfactants will

propel demand for fatty alcohols” Chemical weekly August 24, 2004,p155.

5. Renaud,P. Brackmann,B “ Natural based fatty alcohols” Chemical weekly August 24,

2004,p155.

6. Smulders E., Rybinski W., Sung E., Rähse W., Steber J., Wiebel F., Nordskog A., "Laundry

Detergents" in Ullmann’s Encyclopedia of Industrial Chemistry 2002, Wiley-VCH,

Weinheim

7. http://www.princeton.edu/~achaney/tmve/wiki100k/docs/Detergent.html

8. http://www.chemistry.co.nz/detergent_class.htm

9. Chemical weekly, November 29,2011, p.197

10. Chemical Weekly November 29, P-200, 2011.

11. Indian Oil Corporation, Chemical Weekly November 29, P-199, 2011.