GB751839A - Improvements in or relating to the alkylation of aromatic hydrocarbons and production of sulphonate detergents - Google Patents

Abstract

Alkylated aromatic hydrocarbons are prepared by alkylating an aromatic hydrocarbon with C11 to C13 (inclusive) polymers which have been obtained by the polymerization of propene and butene in a feed on which the butene component contains at least one mole. of n-butene per 10 moles. of propene and less than 1/2 mole. of isobutene per mole. of n-butene. The term "n-butene" is used to denote butene-1 and/or butene-2. The preferred polymer materials for the alkylation are polymer fractions obtained by the polymerization of feeds containing, on a molar basis, more propene than n-butene and preferably 3 to 10 moles. of propene per mole. of n-butene such as a fraction boiling in the range from 360 DEG to 425 DEG F. and having bromine numbers in the range from 88 to 104 which may be prepared as described in the parent Specification. Alkylation may be effected using sulphuric acid, BF3, anhydrous HF or AlCl3. CHCl3 complex as catalysts; preferably, however, an AlCl3 complex is used containing about 38-42 per cent by weight of AlCl3 combined with olefin polymers and aromatic hydrocarbons and only about 1 per cent free AlCl3 when active. Sulphonation may be carried out with sulphuric acid, oleum or liquid SO3. The preferred process, described with reference to a flow diagram, comprises mixing the olefenic reactant with at least a molar excess of the aromatic reactant, e.g. benzene, toluene or naphthalene, and fractionating to dry the mixture which is then introduced into the bottom of an alkylation reactor through a catalyst layer and alkylation effected at 35 DEG to 115 DEG F. Alkylation product is withdrawn at the top, part thereof being recycled and the remainder being passed through a settler to remove suspended catalyst and thereafter purified, e.g. by bleaching with hypochlorite, washing with sulphuric acid and treating with activated clay to remove unsaturated compounds or washing with caustic soda and then with water. The purified alkylate is next fractionated to remove the excess aromatic reactant, low boiling alkylate and a side-stream of desired alkylate, typically of B.R. 518-680 DEG F. when benzene is alkylated, and so leaving a heavy residual alkylate as bottoms. The alkylate fraction is then sulphonated and the product is quenched in water, neutralized with caustic soda, sufficient sodium sulphate added to bring the concentration of the active ingredient to 40 per cent and the resulting detergent composition is finally dried, after de-oiling when necessary. Experiments are described by way of comparison wherein three propylene feeds containing about 2, 10 and 20 per cent respectively of n-butene on a total olefine basis, traces of isobutene, and paraffins are polymerized using a phosphoric acid catalyst; precise C12 polymer fractions are recovered and used to alkylate benzene and precise C12 alkylates are recovered from the alkylation product and sulphonated; the first mentioned substantially pure propene feed gives the highest yield of detergent. The propene feeds containing the higher amounts of n-butene are polymerized in further experiments and C11-C13 polymer fractions are recovered and used to form detergents whose detergent properties are at least comparable to those of the detergent from the C12 alkylate in soft water and are substantially better in hard water and the yield of detergent is similar to that obtained using, initially, substantially pure propene.