Proses Sulfonasi

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Proses Sulfonasi

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  • 1. Introduction Sulfonation and sulfation, chemical methods for introducing the SO3 group into organic

    molecules, are related and usually treated jointly. These methods are utilized widely

    throughout the world and are important chemical processes for manufacture of a

    number of product classes, including surfactants, polymers, dyes, concrete additives,

    pesticides, and medicinals. In the anionic surfactant industry alone, it is estimated that

    _139 plants across the globe had an sulfonation capacity (in terms of linear alkylbenzene sulfonates) of 4.9 million metric tons as of 2003 . Of this capacity, 1.5

    million metric tons resided in North America (United States, Canada, Mexico).

    In sulfonation, an SO3 group is introduced into an organic molecule to give a product

    having a sulfonate, CSO3, moiety. This product may be a sulfonic acid, a salt, or a

    sulfonyl halide requiring subsequent alkaline hydrolysis. Aromatic hydrocarbons are

    generally directly sulfonated using sulfur trioxide, oleum, or sulfuric acid. Sulfonation

    of unsaturated hydrocarbons may utilize sulfur trioxide, metal sulfites, or bisulfites.

    The latter two reagents produce the corresponding hydrocarbon metal sulfonate salts in

    processes referred to as sulfitation and bisulfitation, respectively. Organic halides react

    with aqueous sodium sulfite to produce the corresponding organic sodium sulfonate.

    This is the Strecker reaction, also referred to as sulfonato-de-halogenation. In instances

    where the sulphur atom at a lower valance is attached to a carbon atom, the sulfonation

    process entails oxidation. Thus the reaction of a paraffin hydrocarbon with sulfur

    dioxide and oxygen is referred to as sulfoxidation; the reaction of sulfur dioxide and

    chlorine is called chlorosulfonation. The sulfonate group may also be introduced into an

    organic molecule by indirect methods through a primary reaction, eg, esterification,

    with another organic molecule already having an attached sulfonate group. Sulfation is

    defined as any process of introducing an SO3 group into an organic compound to

    produce the characteristic C-oSO3 configuration. .

    2. Uses for Derived Products and Sulfonation Technology Sulfonation processes are utilized in the production of water-soluble anionic

    surfactants, which are principal ingredients in formulated light-duty and heavy-duty

    detergents, liquid hand cleansers, combo bar soaps, general household and personal

    care products, and dental care products . Generally, household and personal care

    products must have light color, little

    unreacted material (free oil), low inorganic salt, and negligible odor. Bleach activators

    represent an additional commercial sulfonate technology. Sulfonated and sulfated

    products for industrial applications include emulsifiers for emulsion polymerizations,

    pesticideherbicide emulsifiers, concrete additives, demulsifiers, textile wetting agents, dry-cleaning detergents, leather tanning agents, metal cleaners, corrosion inhibitors,

    and oil-production chemicals. Other commercially significant product sectors include

    lube additives, pesticide chemicals, medicinals, sweeteners, cyclic intermediates, dye and

    pigment products, and ionexchange resins. This latter class of materials finds uses as

    strong acid catalysts and as ion-transport membranes in the exanding field of fuel cell

    technology. Application chemists are most interested in physical and functional

    properties contributed by the sulfonate moiety, eg, solubility, emulsification, wetting,

    foaming, detersive properties, and chemical acidity. Products can be designed to meet

    various criteria including water solubility, water ispersibility, and oil solubility. The

    polar SO3 moiety contributes detersive properties to lube oil sulfonates and dry-

    cleaning sulfonates.

  • 2.1. Process Selection and Options. Because of the diversity of feedstocks, no single process fits all needs. An acceptable

    sulfonation process requires (1) the proper reagent for the chemistry involved and the

    ability to obtain high product yields; (2) consistency with environmental regulations

    such that minimal and disposable by-products are formed; (3) an adequate cooling

    system to control the reaction and to remove significant heat of reaction; (4) intimate

    mixing or agitation of often highly viscous reactants to provide adequate contact time;

    (5) products of satisfactory yields and marketable quality; and (6) acceptable

    economics. Sulfonation and sulfation processes have been recently reviewed .

    Elevated viscosity can play a significant role in dictating agitation/mixin requirements

    and can also seriously affect heat-exchange efficiency. For example in the case of SO3

    sulfonation of various surfactant feedstocks, viscosity generally undergoes a 15 to 350

    fold increase on reaction, significantly reducing heat-transfer coefficients. Conventional

    continuous sulfonation equipment, eg, falling film reactors, are generally suitable for

    producing sulfonic acid products with viscosities up to 1500 cps, whereas some

    industrially important products may have viscosities as high as 40,000 cps . In some

    instances, where the feedstock has a high melt point or where either the feedstock or its

    sulfonic acid exhibits high viscosity under nominal sulfonation reaction temperatures,

    the use of higher temperature cooling media, eg, hot water or steam cooling has been

    utilized . In addition, the application of a pressure drop to accellerate gaseous SO3

    across the length of a falling film tube reactor as been reported to be effective in

    overcoming viscosity limitations .

    SULFONATION REACTANTS Sulfonation reactants and reaction products may be miscible or immiscible. For

    example, the reagents in sulfuric acid sulfonation of simple aromatic hydrocarbons, eg,

    xylenes, are immiscible and therefore mixing has important effects on reaction kinetics.

    In some instances, inert solvents may be required to overcome high viscosity, poor heat transfer, or reagent incompatability; examples of useful solvents include pentane,

    methylene chloride, and liquid sulphur dioxide.

    2.2. Industrial Changes Affecting Sulfonation Operations(PAST & PRESENT) Ongoing changes dating to the 1980s that impact sulfonationsulfation operations on a worldwide basis include maturation of the sulfonation industry and its technology,

    development of a highly competitive and reactive market environment, and

    environmental and safety regulations affecting the types of manufacturing operations,

    plant locations, by-product generation and disposal, plant emissions, and other

    discharge streams. Sulfur trioxide has become the dominant sulfonation reagent for

    anionic surfactant manufacture, largely though not completely supplanting oleum

    sulfonation processes. For example, a Huish SO3air sulfonation plant with 79,000

    metric ton annual capacity came on stream in Texas in 2003, concurrent with a shut-

    down of the companys 8000 metric ton oleum sulfonation plant in Wyoming . The preference for SO3 based sulfonation is particulary strong amongst merchant

    manufacturers of surfactants, where manufacturing flexibility is critical to plant

    rationalization and adaptable product mixes. Continuous falling film SO3 sulfonation

    continues to be the method of choice for sulfonating liquid flowable feedstocks, and

    improvements in raw material quality and reactor design have enabled further

    optimization of product quality . Shifting consumer preference for liquid laundry

    detergents over powders in the United States, significant cost pressures on detegent

  • manufacturers from discount retailers, and advances in detergent formulation

    technologies, eg, advanced enzymes and bleaching systems have all had a significant

    impact on the anionic surfactant industry. A dramatic shift away from linear

    alkylbenzene sulfonates (LAS) to alcohol ethoxylate sulphates (AES) in North American

    laundry detergents occurred during the 1990s and has held firm through the first half

    of the 2000s. As of 2005, volatility in the petroleum market has intensified interest in

    anionic surfactant technologies that utilize nonpetroleum based feedstocks, eg, methyl

    ester sulfonates (MES) derived from palm oils. Developments and potential future

    developments in anionic surfactant feedstocks has been reviewed. Production of dyes

    and dye intermediates, including the sulfonation operations associated with this

    production, has declined signficantly over the past decade in North America and

    Europe as production has largely been relocated to Asian countries, eg, China and

    India. Severe price pressures have resulted from oversupply of dyestuffs, and

    competition from small producers has forced large dyestuff manufactures to restructure

    . Sulfonated products for use in lubricants and metalworking likewise suffered from a

    decline in value in the early 2000s due n part to competition from producers in China

    and India

    .

    3. Economic Aspects It was estimated from U.S. International Trade Commision reports that in the United

    States during 1991,1.92 million tons of sulfonated, sulfated, and sulfamated products

    were manufactured. This represented a market value of $3.4 million constituted 4.5% of the annual value of all synthetic organic chemical production. Anionic surfactants