The use of hydroxyalkyl sulphonates in detergent compositions is well-known. For example, US-A-3896057 discloses the use of water-soluble salts and acids of alkene sulphonates and hydroxyalkyl sulphonates in laundry detergents. US-A-3883583 discloses high molecular weight, oil-soluble, anionic surface active agents consisting of sulphonates of an aliphatic monoolefin having a carbon number in the range of 32-40.

The surface active agents are said to be good reagents for dry-cleaning detergents.

EP-A-0537840 discloses a lubricating oil composition comprising a major proportion of a lubricating oil and a minor proportion of an alkaline earth metal salt selected from calcium and magnesium salts of a hydroxyalkyl sulphonic acid. The compounds are formed by the sulphonation of internal olefins which are disclosed as C1o-C32 olefins, with C1s-C19 olefins with an average molecular weight of 230 being preferred.

EP-A-0351928 discloses a process for the preparation of internal olefin sulphonates which comprises reacting in a film reactor an internal olefin having from 8 to 26 carbon atoms with a sulphonating agent, in a molar ratio of sulphonating agent to internal olefin of 1: 1 to 1.25: 1, while cooling the reactor with a cooling means having a temperature not

exceeding 35°C, and neutralising and hydrolysing the reaction product of the sulphonating step.

The successful preparation of hydroxyalkane sulphonates depends very much on the efficiency of the neutralisation/hydrolysis reactions. If these reactions are not carried out efficiently, immediately following sulphonation, the reverse reaction to olefins and sulphur trioxide can occur, resulting in poor yields or poor quality products.

However, in each of the above publications the olefins are relatively pure, without contaminating materials present which may interfere with the various two-phase reactions and/or with the reaction products.

For example, high levels of paraffins would be detrimental to the effectiveness of sulphonation, neutralisation and hydrolysis, as the paraffins have the effect of slowing down the reactions. It is expected that high levels of paraffins negatively affect direct neutralisation (ring opening) of the beta-sultones produced in the sulphonation reaction. This may give rise to unacceptably low conversions to hydroxyalkane sulphonates, due to the reverse-reaction to sulphur trioxide and internal olefin.

This is expected to be even greater if bases of limited solubility in water, such as calcium hydroxide, are used in the neutralisation step.

US-A-5488148 discloses a process for sulphonating internal olefins in the presence of a hydrocarbon solvent but wherein the intermediate sulphonated compounds are neutralised with an aqueous solution of an alkali metal hydroxide, such as sodium hydroxide. The reverse-reaction to olefins and sulphur trioxide is counteracted by the use of an excess of the alkali metal hydroxide.

The present invention is based on the realisation that mixtures of olefins and paraffins which emerge from a dehydrogenation plant, such as a PACOL- (OLEX) unit or a wax cracker unit fed with paraffins, or from a Fischer-Tropsch unit fed with natural gas, other hydrocarbons, or coal, may be utilised directly as a feedstock in the production of calcium hydroxyalkane sulphonates.

Therefore in accordance with the present invention there is provided a process for the preparation of calcium hydroxyalkane sulphonates from a mixture comprising at least 20% by weight paraffins and at least 10% by weight olefins, comprising reacting the mixture with a sulphonating agent in a reactor, and neutralising and hydrolysing the reaction product in the presence of a calcium-containing base.

Preferably the olefins in said mixture are Cob-30 olefins, more preferably C14-30 olefins, particularly C14-20 olefins. Said base is preferably selected from calcium hydroxide, calcium carbonate, calcium acetate and calcium oxide. Particularly preferred is calcium hydroxide. The mixture may also comprise 1 to 25% by weight of oxygenated products, as for example found in the Fischer-Tropsch olefin/paraffin products.

The reaction product is suitable as a detergent in fuel and lubricant compositions.

In the process of the present invention, said mixture is typically reacted with a sulphonating agent in a reaction vessel with a subsequent reaction in a stirred neutralisation vessel. A final heating step may be carried out to hydrolyse any residual sultones produced by the reaction.

The feedstock that is typically used in the process mimics those produced from a PACOL- (OLEX)

dehydrogenation plant, from a wax cracker after double bond isomerisation, both fed with paraffins and, more particularly, those from a Fischer-Tropsch unit, e. g. from the Shell Middle Distillate Synthesis (SMDS) unit prior to hydrocracking, fed with methane, naphtha, residual fuel, or coal using a suitable Fischer-Tropsch catalyst, if required after double-bond isomerisation.

Said mixture preferably comprises 10% to 80% by weight olefins.

In a preferred embodiment of the present invention, the olefins present in the mixture are internal olefins.

The molar ratio of sulphonating agent to olefin is preferably in the range of 1: 1 to 1.25: 1.

The sulphonation of the olefins is preferably carried out with sulphur trioxide, preferably in a film reactor. The reactor is preferably cooled to a temperature not exceeding 35°C, more preferably in the range 10-30°C.

The neutralisation/hydrolysis is preferably carried out with the calcium-containing base in aqueous medium.

The neutralisation of the reaction product is preferably carried out with a molar excess of calcium-containing base, preferably at a base: olefin molar ratio of at least 1.2: 1, more preferably a molar ratio of at least 1.5: 1. Preferably, neutralisation is carried out at a temperature in the range 0°C to 80°C, more preferably 30 to 40°C.

The hydrolysing step is preferably carried out at a temperature in the range of 100°C to 250°C, more preferably 130°C to 200°C.

The process may be carried out batch wise, semi- continuously or continuously. The reaction is generally performed in a falling-film reactor (ffr) which is cooled by flowing water on the outside walls of the

reactor. At the inner walls of the reactor, the mixture flows in a downward direction. The sulphur trioxide is diluted with a stream of nitrogen, air or any other inert gas into the reactor. The concentration of sulphur trioxide is generally 1-4 % by volume with respect to the carrier gas. The neutralisation reaction should be carried out immediately after the sulphonation reaction under high shear mixing conditions.

The following Examples illustrate the present invention.

Example 1 A mixture comprising 76.8% by weight paraffins, 3% by weight oxygenates and 20.2% by weight internal olefins (having a chain length distribution of: C14 5%; C15 22.3%; C16 31.8%; C17 23.8%; C18 11.7%; C19 4.3%; and Czo 1% w/w), was sulphonated in a continuous falling- film reactor having a diameter of 0.5 cm and a length of lm.

Sulphur trioxide was prepared by reacting sulphur dioxide with oxygen (dry air) over a vanadium pentoxide catalyst at about 450°C.

The mixture flowed along the inner part of the reactor walls as a flowing film in a downward direction and reacted with the sulphur trioxide (molar ratio sulphur trioxide: olefins was 1.2: 1). The temperature of the reaction mixture was approximately 15°C. After the sulphonation process had been carried out, the reaction products were fed to a stirred slurry of calcium hydroxide in water (about 1.5 equivalents calcium hydroxide with respect to the amount of olefin feed).

The mixture was stirred vigorously (using an Ultraturrax high-shear mixer) at about 40°C for at least 2 hours and subsequently transferred into a hydrolysis reactor and heated at 160°C for 1 hour.

Examples 2 and 3 Example 1 was repeated but using a pure olefin mixture instead of an olefin/paraffin mixture. In Example 3, a larger falling-film reactor was used.

A comparison of the sulphonation conditions in Examples 1-3 is shown in Table 1 and an analysis of the reaction products is shown in Table 2.

Table 1 EX 1 EX2 EX 3 Sulphonationreactor ffr ffr ffr length (m) 1.0 1. 0 6 diameter (cm) 0.5 0. 5 2.54 temperature (°C) 15 15 23-24 conc. S03 (% vol) 132. 5 olefin C14-C20 C15-C19 C15-C19 mw olefin 224 230 230 mw sulphonate 674 686 686 throughput (mol/hour) 0.42 1. 5 71.3 S03: olefin molar ratio 1. 2 1. 2 1.06 Neutralisation/Hydrolysis OH: olefin molar ratio 1. 5 1. 4 1.5

Taking account of the fact that the sulphur trioxide concentration in Example 1 was lowered to accommodate the longer residence time of the dilute olefin in the falling film reactor, Table 1 shows that the sulphonation and neutralisation conditions in all three Examples are similar, the sulphur trioxide: olefin molar ratio being within the desired range.

Table 2 EX 1 EX 2 EX 3 Mass product (g) 2058 307 450,000 Mass AM (g) 203.4 54. 3 109,000 Yield (% mol/mol) 71 81 85

Table 2 shows that the yield of the calcium hydroxyalkane sulphonate, using olefin/paraffin mixtures (Ex 1) was comparable to those obtained using a pure C15-Cl9 internal olefin mixture (Ex 2 and 3). This shows that mixtures comprising high levels of paraffins are suitable feedstocks for the preparation of calcium hydroxyalkane sulphonates, which are suitable detergents for use in fuel and lubricant compositions.