LAS is produced by sulphonation of linear alkylbenzene (LAB) followed by neutralization of the corresponding sulphonic acid with caustic soda. Here the average technology, representing a mix of 50% aluminium chloride (AlCl3) process and 50% hydrofluoric acid (HF) process is applied - this is typical for European production conditions in the mid 1990s. In the AlCl3 process, the benzene is alkalyted with chloro-paraffins and/or n-olefins with the help of an AlCl3 catalyst. In this process, part of the n-paraffins is chlorinated, the remainder is used to produce n-olefins. In the HF process, benzene is alkalyted directly with n-olefins, using HF as a catalyst. The n-olefins themselves are produced by catalytic dehydrogenation of n-paraffins. In both processes the n-paraffins are responsible for the line-arity of the alkyl chain. Sulphonation of LAB is then usually carried out by adding an SO3 group to the aromatic ring of the LAB molecule. The reaction is exothermic and requires careful control of the temperature. Finally, sodium hydroxide is used to neutralize the acid that has been produced (Berna et al. (1995)).
Reference:
Berna J. L., Cavalli L. and Renta C. (1995) A Life-Cycle Inventory for the Pro-duction of Linear Alkylbenzene Sulphonates in Europe. In: Tenside, Surfactants, Detergents, 32(2), pp. 122-127.