GB1579815A - Aralkylation of alkylbenzenes - Google Patents

Description

(54) ARALKYLATION OF ALKYLBENZENES (71) We, NIPPON PETROCHEMICALS COMPANY, LIMITED, a Japanese company of 3-12, l-chome, Nishi-Shimbashi, Minato-ku, Tokyo, Japan do hereby declare the invention for which we pray that a patent may be granted to us and the method by which it is to be performed, to be particularly described in and by the following statement:- This invention relates to a process for aralkylating alkylbenzenes with styrene.

It is more particularly concerned with a process for catalytically aralkylating alkylbenzenes by continuously feeding an alkylbenzene and a styrene to a catalyst layer containing synthetic silica-alumina that has been subjected to calcination at a temperature between 450"C and 600"C.

Alkylation reactions between an alkylbenzene and an olefin, which are most important reactions in chemical industry, find many uses. In cases where aromatic olefins such as styrene (termed styrenes hereinbelow) are employed as the olefin the reaction is called an "aralkylation" reaction. Non-condensed polycyclic aromatic hydrocarbon compounds from the aralkylation between an alkylbenzene and a styrene which have excellent properties in terms of compatibility, heat resistance, lubricity and electric properties are synthetic oils suitable for a wide range of uses such as plasticisers, high-boiling solvents, heat media, electric insulating oils, working oils and lubricants. However, the desired aralkylated alkylbenzenes for these uses cannot be produced in a high yield due to the tendency of styrenes to be polymerized when the conventional alkylation catalysts are used.

As the heretofore disclosed aralkylation catalysts are mentioned concentrated sulfuric acid proposed in British Patent No. 977,322 and acidic solid acids proposed in U.S. Patent No. 3,069,478. The process with sulfuric acid, when operated on an industrial scale, requires not only high cost for the after-treatment such as the water washing required for the neutralization to remove the catalyst after completion of the reaction but also means for preventing corrosion of the equipment as well as environmental pollution from the discharged water. On the other hand, the prior art reactions which employ clay mineral catalysts such as acid clays are batch processes. It has been found that the synthetic silica-alumina containing from 7( to 15 /" alumina disclosed in U.S. Patent No. 3,069,478 is unfitted in practice for use in the continuous process, owing to its short life, although, as described in detail in the patent specification, it is effective in the batch reaction.

The present invention is based on the discovery of catalysts which may be used in the fixed-bed catalytic continuous reaction which is the most preferable from the industrial point of view.

According to the present invention there is provided a process for the aralkylation of at least one alkylbenzene in which each substituent alkyl group has from 1 to 4 carbon atoms with at least one styrene selected from styrene, vinyltoluenes and a-methylstyrene, by continuously feeding said at least one alkylbenzene and said at least one styrene in liquid phase and at a temperature of from 100"C to 200"C to a catalyst layer comprising synthetic silica-alumina which contains from 20% by weight to 50% by weight alumina and which has been calcined at a temperature in the range of from 450"C to 6000 C.

The attached drawing represents a graph indicating relationship between the calcination conditions and the life of the catalyst for the catalyst employed in the aralkylation of alkylbenzenes according to the present invention with various alumina contents. In Fig. 1 the axis of abscissas represents reaction days and the axis of ordinates reaction percentage. Al203-l5, A12O3-28 and A12O3-40 are silicaaluminas which alumina contents of 15% by weight, 28% by weight and 40% by weight respectively. 600x8 hr. means the calcination was conducted at 6000C for 8 hours. The curves without the calcination conditions indicated represent uncalcined silica-alumina.

The synthetic silica-alumina that is used in the process according to the invention is high-alumina synthetic silica-alumina represented by the formula A12O3 . (SiO2). mH2O wherein l.70 < n < 6.79 which has an alumina content from 20% by weight to 50% by weight.

In general, silica-alumina active as a solid acid catalyst has a structure with a number of pores and is therefore of a very large specific surface area usually in the order from 150 to 700 m2/g. When the silica-alumina is calcined, it is subjected to sintering which causes degradation of the porous structure with the result that the surface area is reduced. The catalytic activity will then be reduced. This reduction is especially marked if moisture is present. The smaller the pore size of silicaalumina the more intense will be the sintering. The pore size of silica-alumina is related to the alumina content of silica-alumina. For example, the average radius of pores is 16A for low-alumina silica-alumina with an alumina content from 8% by weight to 17% by weight and 28A for high-alumina silica-alumina with an alumina content from 20% by weight to 40% by weight.

When a low-alumina silica-alumina is calcined, reduction of the activity will be so great that it can no longer be used as the aralkylation catalyst in the process of the invention. On the contrary, when a high-alumina synthetic silica-alumina is calcined at a temperature from 4500 C. to 6000 C., the activity for the aralkylation reaction undergoes no reduction but the catalytic life is remarkably prolonged.

Although the mechanism is not completely elucidated, it is believed that the larger pore sizes of the high-alumina silica-alumina allow the silica-alumina to be influenced by the sintering in such a way that the active sites for the aralkylation reaction are not decreased but those for the side reactions are decreased with the result that reduction in the catalytic life due to the products of the side reactions is prevented.

The process of the invention is characterized by the use of silica-alumina with a high alumina content that has been calcined at a temperature within the specified range. Accordingly, the calcination of the catalyst is a critical factor.

The calcination treatment is satisfactory when conducted at a temperature from 450"C. to 6000 C. for a period of time longer than 4 hours, and preferably up to 24 hours. The calcination may well be carried out in air and use of an inert gas is not needed.

A calcination temperature below 450"C. will give rise to no improvement of the life of catalytic activity, and calcination conducted at a temperature above 600"C. will be disadvantageous because of reduction in the activity due to sintering.

It is desirable to avoid the calcination temperature exceeding 600 C., even locally, in order to prevent sintering of the catalyst from taking place. The presence of steam is not desirable during the calcination under the above-cited conditions.

Steam will remarkably promote the sintering to cause reduction in the catalytic activity, though the effect is variable depending upon the conditions used. It is therefore preferable to dry the silica-alumina thoroughly at a temperature from 1500C. to 200 C. prior to the calcination treatment.

The synthetic silica-alumina utilizable in the process of the invention may be prepared by any of the conventional deposition, coprecipitation and blending methods. For example, the method disclosed in U.S. Patent Nos. 2,384,946 and 2,900,349 which involves obtaining silica-alumina gel by adding an aqueous solution of aluminium sulfate to a slurry of silica hydrogel from a slightly acidified aqueous solution of sodium silicate is preferably employed. The alumina content can easily be controlled by adjusting the added amount of the aluminium salt.

The alkylbenzenes with one or more substituent alkyl groups containing I to 4 carbon atoms used in the process of the invention include C9 and C10 aromatics such as toluene, ethylbenzene, o-, m- and p-xylenes, cumene, o-r m- and pmethylethylbenzenes, and 1,2,3-, 1,2,4 and 1,3,5-trimethylbenzenes. They may be used either in mixture or individually. The presence of more than 4 carbon atoms in an alkyl group is not recommended because dealkylation will then occur more readily, resulting in lower yield of the desired product. Benzene is not usable from the industrial point of view because of the low reaction yield. An alkylbenzene source containing o- or m-dialkylbenzenes or 1,2,4-trialkylbenzenes gives a favorable result in the process according to the invention, because it reacts with styrenes in a better reaction yield. The other reactant, namely the styrene component is selected from styrene, a-methylstyrene and vinyltoluenes. These may be used alone or in mixture.

Other starting materials preferably utilized in the process of the invention are aromatic by-product oils formed in the thermal cracking of petroleum hydrocarbons at a temperature of 700"C or higher with the object of mainly obtaining ethylene. These aromatic by-product oils are mixed oils having 5 to 10 carbon atoms and generally contain saturated aliphatic hydrocarbons in the range from 5 to 15% by weight, aromatic hydrocarbons (other than aromatic olefins) comprising alkylbenzenes in the range from 35 to 85% by weight, unsaturated hydrocarbons in the range from 2 to 10% by weight and aromatic olefins in the range from 2 to 15% by weight, although they are variable in composition depending upon the nature of the starting oil fed to the cracking equipment and the cracking temperature. Preferred among said by-product oils for use in the present invention is a distillate containing components with a boiling range from 135"C. to 198"C. That is to say, the distillate that is substantially a mixture of C8-C10 aromatic hydrocarbons is preferably employed. An analysis of the distillate as mentioned above is illustrated in the Table below.

Aromatic n-Paraffins iso-Paraffins Naphthene hydrocarbons Olefins Total C8 0.3 0.3 1.8 43.0 22.9 68.3 C9 0.3 0.3 0.3 18.0 10.1 29.0 C10 0.0 0.0 0.3 1.2 1.2 2.7 Total 0.6 0.6 2.4 62.2 34.2 100.0 (% by weight) Olefins in the above-cited C9-C10 distillate are, for the most part, aromatic olefins which are styrenes, and they are starting materials preferably utilized for the present invention. The C9-C10 distillate as mentioned above may be in the form of a mixture or an isolated component with a given carbon number.

Conditions under which the process of the invention is carried out will be described below.

The reaction temperature is usually in the range from 1000C. to 2009C., although it is variable depending upon the nature of the styrenes and alkylbenzenes employed. Temperatures outside the above-cited range are not recommended because at temperatures below 1000C. the desired aralkylation will be associated with polymerization of the styrene, and use of temperatures over 2000 C. will cause decomposition of the aralkylated alkylbenzenes formed. More preferred temperatures are in the range from 1400C. to 1600C.

The reaction pressure may be a pressure sufficiently high to maintain the reaction zone in liquid phase. The pressure is not an essential condition provided that the above-mentioned requirement to maintain liquid phase is met. It is usually preferred to carry out the reaction at a pressure of from 3 kg./cm2 to 10 kg/cm2, although the reaction pressure may of course be varied depending upon the nature of the starting materials and the reaction temperature employed.

If the reaction zone contains gas phase, polymerization of the styrene will be accelerated over the catalyst in the gaseous area so that not only the styrene yield will be decreased but also the life of the catalyst will be shortened due to the surface of the catalyst becoming covered with the polymer.

The contact time in the reaction zone is in the range from 0.5 I.styrene/l.catalyst/hr. to 0.02 I.styrene/l.catalyst/hr. and preferably from 0.3 I.styrene/l.catalyst/hr. to 0.05 I.styrene/l.catalyst/hr.

It is preferred that the amount of styrenes continuously fed to the catalyst layer is 15% by weight or smaller. In such a case, the temperature rise due to heat of the aralkylation reaction is 55"C. or smaller. A temperature rise more than the above will unfavorably cause undesired side reactions such as polymerization of the styrenes and decomposition of the aralkylation products. Adjustment of the amount of styrenes employed may be achieved by controlling the concentration of the styrenes at the inlet to the catalyst layer by means, for example, of dilution with an excess amount of the alkylbenzenes, or by recycle of the reaction products at the outlet from the catalyst layer. However, it is not recommendable to achieve the object by adjusting the styrene concentration with a solvent inert to the reaction such as, for example, an aliphatic hydrocarbon or a halogenated hydrocarbon.

Presence of such an inert component in the reaction system will promote dimerization of the styrene or cyclic dimerization of the styrene unfavourably with the result that the styrene dimer or the cyclic dimer such as indane derivatives is incorporated into the desired aralkylated alkylbenzene products.

Preferred products of the process according to the invention are the monostyrenated and distyrenated products. For example, in the case where xylenes and styrene are employed, there are produced a mixture of l-xylyl-l-phenylethanes as the monostyrenated product and a mixture of various isomers which are adducts of one mole of the xylene and two moles of styrene as the distyrenated product.

Heavier oils other than these which are polymers of styrene are not desirable.

The monostyrenated products, distyrenated products and styrene polymers can be identified by measuring the ratio of aliphatic protons (abbreviated as PaH) to aromatic protons (abbreviated as ArH) by means of NMR.

PaH ArH PaH/ArH Monostyrenated product C16H,8 10 8 1.25 Distyrenated product C24H26 14 12 1.17 Polymer [C8H8]n 3xn 5xn 0.6 The invention is illustrated by the following examples. In the examples, styrene yield means the value in terms of percentage for moles of the styrene converted to monostyrenated and distyrenated products against moles of the styrene fed as the starting material. The larger the value the more favorable will be the results of the process.

Procedures in the examples were the same as in the following Reference Examples 1-4 unless otherwise indicated.

Reference Example 1 Preparation of the Catalyst 2 kg. of an aqueous solution of sodium silicate is prepared by dissolving 168.8 g of sodium silicate with silica:sodium oxide ratio by weight of 2.9 in water. While maintaining the solution at a temperature of 3511 0C. with vigorous stirring, 70 g. of 40 /n sulfuric acid is added to it over a period of about 60 minutes. Cooling is required in order to keep the temperature not exceeding 35floC. during the addition of sulfuric acid. After completion of the addition, stirring is continued for an additional 2 hours for ageing. Then, a 20% by weight aqueous solution of aluminium sulfate is added with stirring over a period of 90 min. Amounts of the aqueous aluminum sulfate solution to be added correspond to the alumina content of the desired silica-alumina, the amounts being 222.5 gr., 490.4 gr. and 840.6 gr.

respectively for the alumina contents of 15% by weight, 28 /n by weight and 40% by weight.

After completion of the addition of aluminium sulfate solution the resulting solution is weakly alkalized to pH 8.0--8.5 by the addition of 15% aqueous ammonia. The slurry after the addition of the aqueous ammonia is stirred for about 30 min. for ageing.

The slurry is then filtered, and the filtrate is washed with a 2% aqueous solution of NH4CI. The filtration and the washing are repeated until the filtrate becomes neutral. The slurry filtrate is dried at a temperature of 200"C. for 8 hours and pulverized to particle sizes equivalent to 5-10 mesh screen.

In the examples and the reference examples were used three catalysts having alumina contents of 15% by weight, 28% by weight and 40% by weight. They are abbreviated as Al203-15, Al203-28 and Al2O3-40, respectively.

Reference Example 2 Calcination of the Catalyst For calcination of the catalyst, an electric oven controlled at a set temperature within +5 C was used. The catalyst is placed and dried in the electric oven set at a temperature of 150"C. After drying, the temperature is raised at a rate of 100 C./hour to a predetermined calcination temperature. After the temperature is raised, calcination is effected at that temperature for 8 hours. After cooled, the resulting catalyst is used for the reaction.

Reference Example 3 Reaction Experiments The catalyst is packed in a cylindrical pressure vessel to form a cylindrical catalyst layer 40 mm. in diameter, 200 mm. in length and 250 ml. in volume. The vessel is covered with a lagging material of a thickness of 1.5 cm. and placed in the constant temperature bath of which the heating system is thermostatically controlled to within + 1 C of the set temperature. An alkylbenzenestyrene mixture is continuously fed to the catalyst layer by means of a constant-flow pump, and reactor effluent is collected in a pressure receiver after cooled pressured to a pressure of 7 kgicm2 of nitrogen. The reactor effluent (distillation feedstuff) is discharged at a predetermined interval, and the products are separated by distillation. Results of the distillation for each component are shown in terms of the composition on average in 10 days from initiation of the reaction unless otherwise indicated.

Reference Example 4 Estimation of the Life of the Catalyst-Measurement of Bromine Number (BrNo) Experiments for the life of the catalyst were carried out using an apparatus similar to the above-mentioned one but with a smaller catalyst layer 16 mm. in diameter, 20 cm. in length and 40 ml. in volume. The catalyst was used in 10--18 meshes. The feedstuff which was a mixture in a ratio of the alkylbenzenes 10 moles:the styrenes 1 mole is fed at a reaction temperature of 1500C.

The styrene has a BrNo of 154, and the feedstuff is fed to the reaction in a dilution to a BrNo of 13.8. During the period of time when the catalytic activity is high, the BrNo of the distillate is 0.05 or lower. When the catalytic activity has been lost, BrNo of the effluent is rapidly increased so that the life of the catalyst can be estimated. The reaction ratio is expressed in terms of the BrNo: BrNo of the effluent BrNo reaction ratio BrNo of the feedstuff Examples 19 and Comparative Examples 1 and 2.

Experiments Reaction between o-xylene and Styrene-effect of Calcination Results of experiments as to reaction of o-xylene with styrene catalyst using the procedures as set forth in Reference Examples 1-3 are shown in Table 1. The results indicate that calcination-improves the styrene yield.

The reaction products were separated by distillation under reduced pressure after unreacted xylene had been removed by distillation under normal pressure.

The monostyrenated product is a fraction distilling at temperatures in the range from 135"C. to 1500C. at 3 mm.Hg which is identified by NMR analysis and has a proton ratio PaH/ArH of 1.27-1.22. The distyrenated product is a fraction distilling at temperatures in the range from 1800C. to 2200C. at 3 mm.Hg which has a PaH/ArH of 1.19-1.14 according to NMR. The heavier residue is styrene polymers with a PaH/ArH of 0.62--0.59 according to NMR.

TABLE 1 Example Example Example Example Comparative Comparative 1 2 3 4 Example 1 Example 2 Catalyst A1203-40 A1203-28 Al203-28 Awl203 28 A120340 A120,-29 Calcination 550"C. 550"C. 600"C 450"C. None None Reaction temperature 1450C. I50 C. 1500C 150"C. 145"C. 1500C.

Xylene:styrene molar ratio 10:1 10:1 10:1 10:1 10:1 10:1 Amount fed ml./hr. 250 250 250 250 250 250 Starting material for distillation 2340g. 2340g. 2340 g. 2340g. 2340g. 2340g.

Monostyrenated product (g.) 279 287 292 251 216 246 Distyrenated product (g.) 52 52 61 73 69 76 Residue (g.) 30 14 18 30 50 40 Styrene yield ( /,) 85 93 91 85 75 80 Examples 5-9 and Comparative Examples 3-8.

Estimation of the Life of the Catalyst Reactions were carried out in accordance with Reference Examples 1-3 using o-xylene and styrene as the reactants. Life of the catalyst was measured by the method described in Reference Example 4. As clearly seen in the attached drawing and Table 2 below, the effect of the calcination is clear with high-alumina containing 20%50% alumina.

The life of the catalyst was indicated with reference to the point at which the reaction in terms of BrNo was 85 /n or below.

TABLE 2 Calcination conditions and Life of the Catalyst Example Catalyst Calcination Conditions Life in Days 5 Awl203 28 600"C.x8 hours 34 6 Awl203 40 600"C.x8 hours 30 Comparative Example 3 Al2O3-28 Non-calcinated 15 4 Al203-4 Non-calcinated 13 5 Al203-'5 Non-calcinated 6 6 Al203-28 7000cox8 hours 10 7 Awl203 28 350 Cx8 hours 16 8 Al2O3-15 600 C.x8hours 12 Example 7 Al2O3-28 6000Cx8 hours 30 8 Al2O3-28 550 Cx8 hours 34 9 Al203-28 4500Cx8 hours 26 Example 10--14 Reactions were carried out between various alkylbenzenes and styrene in accordance with Reference Examples 1-3 using Al203-28 as the catalyst. The calcination was done at 5500C. for 8 hours. The reaction temperature was 1500C., the alkylbenzene:styrene molar ratio was 10:1, and sv. was 1.0. Products after distillation were identified by means of NMR. The results are shown in Table 3.

TABLE 3 Example 10 11 12 13 14 Alkylbenzene m-xylene Mixed Pseudocumene C9-aromatics C10-aromatics xylenes Starting material for distillation (g.) 2340 2340 2350 2350 2380 Monostyrenated product (g.) 299 279 316 295 298 Distyrenated product (g.) 56 52 57 54 53 Heavier residue (g.) 18 30 20 32 40 Styrene yield (%) 91 85 89 84 80 Examples 15 and 16 Reactions were carried out between o-xylene and a-methylstyrene, or m-, p vinyltoluenes in accordance with Reference Examples 1-3 using Al203-25 as the catalyst. Calcination of the silica-alumina was done at 5500C. for 8 hours, the reaction temperature was 1500C., the molar ratio was 10:1, and sv. was 1.0. The results are shown in Table 4.

TABLE 4 Example 15 16 Styrene a-Methylstyrene m-, p-vinyltoluene Starting material for distillation (g.) 2350 2350 Monostyrenated product (g.) 314 292 Distyrenated product (g.) 50 63 Heavier residue (g.) 30 32 Styrene yield (%) 87 86 Example 17 The following procedures were carried out in accordance with Reference Examples 1--3: A fraction distilling at temperatures of 135"C--198"C. was separated from the by-product oil from the thermal cracking of a naphthene source. Composition of the distillate was: saturated aliphatics 3.6 by weight, aromatics (excluding styrenes) 62.2% by weight and unsaturated hydrocarbons 34.2 by weight (including styrenes 32.2% by weight).

The reactant was prepared by mixing 3 parts by weight of xylenes with I part by weight of said distillate. The feeding rate was 250 ml./hr., the reaction temperature 1500C., the catalyst Al203-4 and the calcination conditions 550"cox8 hours. The results are shown in Table 5.

Example 18 The following procedures were carried out in accordance with Reference Examples 1--3.

A styrene-containing xylene fraction distilling out at temperatures of 135"C.-- 145"C. was separated by distillation from the by-product oil from the thermal cracking of a naphthene source. Composition of said xylene distillate was: Non-Aromatics 3.7% by weight Toluene 0.1 Ethylbenzene 9.6 p-xylene 19.2 m-xylene 27.8 o-xylene 10.6 Styrene 28.8 Cumene 0.2 The reactant was prepared by mixing 3 parts by weight of xylenes with 1 part by weight of said xylene distillate. The other conditions were the same as in Example 17. The results are shown in Table 5.

TABLE 5 Example 17 18 Starting material for distillation (g.) 3000 3000 Monostyrenated product (g.) 330.0 314.1 Distyrenated product (g.) 79.4 78.3 Residue (g.) 38.5 8.6 WHAT WE CLAIM IS: 1. A process for the aralkylation of at least one alkylbenzene in which each substituent alkyl group has from 1 to 4 carbon atoms with at least one styrene selected from styrene, vinyltoluene and a-methylstyrene, by continuously feeding said at least one alkylbenzene and said at least one styrene in liquid phase and at a temperature of from 100"C to 2000C to a catalyst layer comprising synthetic silicaalumina which contains from 20% by weight to 50% by weight alumina and which has been calcined at a temperature in the range of from 450"C to 6000 C.

2. A process according to Claim 1 wherein said at least one alkylbenzene and said at least one styrene are provided together in a distillate obtained from a byproduct oil formed in the thermal cracking of petroleum hydrocarbons at a temperature of 700"C or higher, the distillate boiling in the range 1350C to 1980C.

3. A process according to Claim 1 or Claim 2 wherein the styrene content of the feed to the catalyst layer is 15% by weight or lower.

4. A process as claimed in Claim 1, substantially as hereinbefore described with particular reference to the Examples.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (6)

**WARNING** start of CLMS field may overlap end of DESC **. Example 17 The following procedures were carried out in accordance with Reference Examples 1--3: A fraction distilling at temperatures of 135"C--198"C. was separated from the by-product oil from the thermal cracking of a naphthene source. Composition of the distillate was: saturated aliphatics 3.6 by weight, aromatics (excluding styrenes) 62.2% by weight and unsaturated hydrocarbons 34.2 by weight (including styrenes 32.2% by weight). The reactant was prepared by mixing 3 parts by weight of xylenes with I part by weight of said distillate. The feeding rate was 250 ml./hr., the reaction temperature 1500C., the catalyst Al203-4 and the calcination conditions 550"cox8 hours. The results are shown in Table 5. Example 18 The following procedures were carried out in accordance with Reference Examples 1--3. A styrene-containing xylene fraction distilling out at temperatures of 135"C.-- 145"C. was separated by distillation from the by-product oil from the thermal cracking of a naphthene source. Composition of said xylene distillate was: Non-Aromatics 3.7% by weight Toluene 0.1 Ethylbenzene 9.6 p-xylene 19.2 m-xylene 27.8 o-xylene 10.6 Styrene 28.8 Cumene 0.2 The reactant was prepared by mixing 3 parts by weight of xylenes with 1 part by weight of said xylene distillate. The other conditions were the same as in Example 17. The results are shown in Table 5. TABLE 5 Example 17 18 Starting material for distillation (g.) 3000 3000 Monostyrenated product (g.) 330.0 314.1 Distyrenated product (g.) 79.4 78.3 Residue (g.) 38.5 8.6 WHAT WE CLAIM IS:

1. A process for the aralkylation of at least one alkylbenzene in which each substituent alkyl group has from 1 to 4 carbon atoms with at least one styrene selected from styrene, vinyltoluene and a-methylstyrene, by continuously feeding said at least one alkylbenzene and said at least one styrene in liquid phase and at a temperature of from 100"C to 2000C to a catalyst layer comprising synthetic silicaalumina which contains from 20% by weight to 50% by weight alumina and which has been calcined at a temperature in the range of from 450"C to 6000 C.

2. A process according to Claim 1 wherein said at least one alkylbenzene and said at least one styrene are provided together in a distillate obtained from a byproduct oil formed in the thermal cracking of petroleum hydrocarbons at a temperature of 700"C or higher, the distillate boiling in the range 1350C to 1980C.

3. A process according to Claim 1 or Claim 2 wherein the styrene content of the feed to the catalyst layer is 15% by weight or lower.

4. A process as claimed in Claim 1, substantially as hereinbefore described with particular reference to the Examples.

5. A process as claimed in Claim 1, substantially as illustrated in any one of the

Examples.

6. Aralkylated alkylbenzenes when prepared by the process claimed in any one of Claims 1 to 5.