Alkylbenzenes linear, manufacture

Typical properties of detergent alkylate are shown in Table 10-2. Detergent manufacturers buy linear alkylbenzene, sulfonate it with SO3, and then neutralize it with NaOH to produce linear alkylbenzene sulfonate (LABS), the active ingredient in detergents ... 

The higher molecular weight unbranched C10-C18 n-olefins—not only a-olefins but also n-olefins with internal double bonds, so-called n-vj/-olefins—are important initial products for the manufacture of anionic surfactants, e.g., linear alkylbenzenes or olefinsulfonates. These linear C10-C18 olefins are manufactured technically by the following procedures ... 

Not only the linear Cl0-Cl8 a-olefins but also the linear C10-Cl8 olefins with internal double bonds, the so-called -v /-olefins, are of great importance in surfactant chemistry, n-a-Olefins and n-y-olefins have the same suitability for the manufacture of linear alkylbenzenes, the most important synthetic anionic surfactants, by alkylation of benzene. Nowadays medium molecular weight n- /-olefins are industrially produced by two processes the catalytic dehydrogenation of the corresponding n-alkanes [4,28] and the cometathesis of low and high molecular weight n-v /-olefins, obtained by double-bond isomerization of the isomeric n-a-olefins [29]. 

The major uses of linear alkylbenzenes are in the manufacture of linear alkyl sulfonates, LAS, for laundry (70%), light duty dishwashing liquids (15%), industrial cleaners (12%), and household cleaners (3%). 

The production of LAB involves the liquid-phase alkylation of benzene with linear monoolefins or alkyl chlorides. Liquid HF is used as catalyst for linear monoolefins. And the A1C13 is used as the catalyst for alkyl chlorides. Nowadays, acidic zeolite catalyst is used for olefin alkylation which generates less waste and reduces manufacture cost. The alkylate is then sulfonated to produce linear alkylbenzene sulfonate for biodegradable detergents. The manufacture of detergents is described in detail in Chapter 27. 

Reference Greer, D., et al., "Advances in the Manufacture of Linear Alkylbenzene," 6th World Surfactants Conference (CESIO), Berlin, Germany, June 2004. 

Friedel-Crafts technology and zeolite- or other solid catalyst-based processes are currently used for other aromatic alkylations, in particular for the manufacture of linear alkylbenzenes (LABs) made from C10-C14 olefins (Equation 8), or from the corresponding chloroparaffins and benzene, and also to make m- and p-cymene (isopropyltoluene Equation 9). LABs are used for the production of sulfonate detergents, while cymenes lead to m- and p-cresols through a procedure analogous to that used for the cumene-to-phenol process. 

The subject of this entry relates to the manufacture of linear alkylbenzene (LAB), commercially known as detergent alkylate. It is one of the primary surfactant raw materials for the production of household, laundry, dishwashing, and other surfactants. 

Linear alkylbenzene enjoys worldwide acceptance as a cost-effective and environmentally friendly intermediate used in the production of household and industrial cleaning formulations. Both HF acid and solid-bed alkylation processes are cost-competitive routes for the manufacture of LAB. Solid-bed alkylation process produces fewer environmentally hazardous by-products and employs a less complex facility when compared to HF route. With the breakthrough development of commercially demonstrated and expected future refinement, the solid-bed alkylation technology is expected to meet the continued growth in LAB. 

Besides the production of cumene and ethylbenzene, there are a number of recent reports on the production of linear alkylbenzene, precursors to detergents, via the alkylation of benzene with C6-C18 olefins. One process uses suspension CD and essentially 100% conversion of olefin at low temperatures of 90-100°C was obtained. An HF-treated mordenite used in the alkylation of benzene and C10-C14 olefins was foimd to give a 74-84% selectivity to linear alkylbenzene containing 80% 2-phenyl isomer. A new patent on the alkylation of aromatic hydrocarbons such as benzene and cumene with straight-chain C6-C20 olefins on acidic catalyst such as zeolites or fluorine-treated zeolite catalyst packed in a Katamax-type packing was granted. A patent application on the manufacture of xylenes from reformate by RD also appeared and higher than equilibrium amounts of para-xylene were claimed. 

The i-oleftns obtained have a purity of more than 95 molar per cent of terminal olefins and are devoid of branched structures or diolefinic or cyclic impurities. These z-olefms, which all have an even number of carbon atoms, are produced with yields that vary according to a statistical distribution, with a maximum of C, 0-C, 2-Cj, for example, if the final product is intended for the manufacture of linear alkylbenzene. Due to the low yield of a given cut, it is understandable that the upgrading of all the other fractions is economically necessary. Since the upgrading of the light and heavy fractions is often a problem. Shell in the United States has developed the SHOP (Shell Higher Olefin Process), in which these effluents are converted to a cut for detergents by isomerization and metathesis. 

Other alkylaromatics synthesis processes are also of interest. The H-ZSM-5 zeohte is used industrially to selectively alkylate ethylene on toluene into paraethyl-toluene, which is an intermediate for production of the monomer paramethylstyrene. The selective synthesis of paracymene was considered by selective alkylation of propylene on toluene with the H-ZSM-5 zeolite. Open zeolites (e.g., Y) are catalysts of potential interest for the alkylation of benzene by C10-C15 linear olefins, which produce linear alkylbenzenes (LABs) used in manufacturing detergents. Good selectivities for 2.6-dialkylnaph-thalene (alkyl=methyl or isopropyl) can be obtained by alkylation of naphthalene by methanol, propylene, or isopropanol on H-mordenite. 

Of all the various surfactants used in detergent formulations, alkylbenzene sulfonates are by far the most widely used. As a result, alkylbenzenes are the most widely used surfactant raw materials. There are two basic types of alkylbenzenes used in surfactant manufacturing linear alkylbenzenes (LAB) and branched alkylbenzenes (BAB). Both types of alkylbenzenes are homolog mixtures. Typical homolog representatives of LAB and BAB are depicted in Figures 2.1 and 2.2, respectively. 

Higher n-olefins of Cs-Ci4 are used as intermediates in the manufacture of several types of surfactant materials. Linear internal olefins are used in the production of linear alkylbenzene alkylphenol detergent alcohols, which in turn is used to produce alcohol sulfates, alcohol ethoxylates, and alcohol ether sulfates and synthetic lubricants. a-Olefins are used in the production of detergent alcohols, linear alkylbenzene, synthetic lubricants, and a-olefin sulfonates (another ionic surfactant). 

Greer, D. et al. Advances in the manufacture of linear alkylbenzene. CESIO—6th World Surfactants Conference, Berlin, June 20-23, 2004. 

Linear alkylbenzene sulfonate is also used as a foaming agent in the manufacture of plaster boards, as an emulsifier in phytosanitary liquids and emulsion polymerization and as a dispersing agent for dyes in paper and textile industries. 

Specialty surfactants are mostly secondary surfactants, not the primary ingredient in a formulation, and gamer somewhat higher prices in the marketplace. Normally, over time a surfactant once considered a specialty slowly becomes a commodity. However, some surfactant classes can have both coimnodity and specialty uses. In fact, it is sometimes possible to convert a coimnodity into a specialty. For instance, linear alkylbenzene sulfonate (LAS) is considered a commodity. As such, it is sold either in the acid form at 96% active or as the sodium salt at 40% to 60% active. There are many producers of and applications for LAS. As a specialty, the sodium salt is sold as flakes at 90% active. Few producers and few applications need this material, but it commands a higher price. One main use is for dry blending in powdered detergents for smaller manufacturers, where it makes it possible to avoid purchase of expensive spray-drying equipment. Here the special property is its physical form. 

Three basic processes have been practiced for linear alkylbenzene manufacture. The most prevalent route of alkylbenzene manufacture is by partial dehydrogenation of paraffins, followed by alkylation of benzene with a mixed olefin/paraffin feedstock, using liquid hydrogen fluoride catalyst. A second route is via partial chlorination of paraffins, followed by alkylation of the chloroparaffin/paraffin feedstock in the presence of an aluminium chloride catalyst. The third process uses partial chlorination, but includes a dehydrochlorination to olefin step prior to alkylation with aluminium chloride or hydrogen fluoride. 

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