WO2013061336A2

WO2013061336A2 - A process for producing alkylated aromatic hydrocarbons

Info

Publication number: WO2013061336A2
Application number: PCT/IN2012/000561
Authority: WO
Inventors: Pavankumar ADURI; Parasu Veera UPPARA; Mangesh SAKHALKAR; Uday RATNAPARKHI; Paresh Nanubhai TRIVEDI; Munish BHALLA; Narayanmadhav JAGADALE
Original assignee: Reliance Industries Ltd
Current assignee: Reliance Industries Ltd
Priority date: 2011-08-23
Filing date: 2012-08-23
Publication date: 2013-05-02
Anticipated expiration: 2014-02-23
Also published as: TW201311614A; WO2013061336A3; TWI546278B; SA112330799B1

Abstract

In the present disclosure, there is provided a process for preparing alkylated aromatic hydrocarbons by contacting an aromatic hydrocarbon with an alkylating agent that comprises a mixture of at least one C₂ to C₅₀ containing olefin and at least one C₂ to C₅₀ containing paraffin, in the presence of at least one acid catalyst selected from the group consisting of (i) compounds having the molecular formula of RSO₃H, wherein R is independently selected from the group consisting of alky 1, aryl, halogen, or alkyl halide; (ii) ionic liquid composition comprising (a) at least one cationic precursor selected from the group of compounds consisting of hydrogen donor compounds, tetra alkyl ammonium halide, phosphonium halides or imidazolium bromide; and (b) at least one anionic precursor selected from the group consisting of metal halides and organic halides, at a temperature varying between 35°C and 90 °C, under atmospheric pressure to obtain a hydrocarbon layer containing an alkylated aromatic hydrocarbon.

Description

A PROCESS FOR PRODUCING ALKYLATED AROMATIC

HYDROCARBONS

FIELD OF THE DISCLOSURE

The present disclosure relates to a process for preparing alkylated aromatic hydrocarbons. BACKGROUND

Surfactants are widely used in the industry to improve contact between polar and non- polar media such as oil and water or between water and minerals. Linear alkyl benzene sulfonic acids constitute the category of the most widely used precursors for the manufacturing of household detergents such as laundry liquids, dishwashing liquids and other house hold cleaners. Apart from this, their use as a coupling agent, as an emulsifier for agricultural herbicides and as a catalyst in the emulsion polymerization is also well- known in prior-art.

Linear alkyl benzene sulfonic acid (LAS) are often produced by the sulfonation of linear alkyl benzene with oleum in batch reactors. Generally, the production of linear alkyl benzene is accomplished by contacting benzene/substituted benzene with an olefin or mixture of olefins, in the presence of a homogeneous or heterogeneous alkylation catalyst such as aluminum chloride, boron trifluoride, sulfuric acid, hydrofluoric acid, phosphoric acid and zeolite.

Hydrofluoric acid (HF) is the most commonly employed acid catalyst for such reactions. However, HF based processes are associated with plentiful operational concerns in terms of safety, toxicity, volatility, corrosiveness, waste disposal and troublesome acid recovery and its purification.

EXISTING KNOWLEDGE

United States Patent Documents 3104267 and 4219686 disclose the use of lewis acid catalysts such as the mixture containing titanium tetrachloride and alkylaluminum

l dichloride/dialkylaluminum chloride/ alkylaluminum sesquichloride, and aluminum chloride respectively during the alkylation of aromatic hydrocarbons. However, the processes as disclosed in these documents still do not completely obviate the use of corrosive and hazardous acids like HC1 and/or HBr.

Further, attempts have also been made to attenuate the problems associated with corrosive acids by employing HF based catalyst which is one of the least acidic and least corrosive hydrogen halides. United States Patent Documents such as US3249650, US3494971, US3560587, US3686354, US3715615, US 4239931, and US 3950448 disclose the use of such catalysts for the alkylation of hydrocarbons. However, the risk of releasing HF into the environment became a concern.

Further to HF based catalysts, solid catalysts have also been found to facilitate linear alkyl benzene production as disclosed in US3494971, US7737312, US 5334793, US3346657, US4358628, US4368342, U?4513156, US4973780, US5196574, US5196624, US5344997, US5574198, UK5777187, US5847254, US5894076, US6133492, US7655824, US201 101 18517 and US201 10144403. However, the use of such solid catalysts calls for major structural modifications in the existing HF catalyst based alkylation processing plants.

In addition to the aforementioned catalysts, ionic; liquid based compounds have also been employed in the alkylation reactions as described in WO1998003454, US5824832, WO 1999003163, WO2000041809, US 7285698, US7732651. Further, ionic liquid particularly chloroaluminate based ionic liquid has been indicated for the alkylation reaction by Zhu Hai-yan et. al. in Bulletin of Catalysis Society of India, 6, 2007, 83-89 and Ling H.E. et. al. in Chinese Chemical Letters, 2003, 17.3, 321-324. Apart from HF and ionic liquid based catalysts, other catalysts that have been explored for alkylation include sulfonic acid derivatives as disclosed in the Journal of Catalysts, 226, 2004, 301-307.

Despite a large number of catalysts available for alkylation of benzene/substituted benzene, a need to develop a safer catalyst for ths alkylation process is felt by the present inventors wherein the major drawbacks associated with the use of corrosive and toxic catalysts are mitigated and the reaction is accomplished in the existing HF based alkylation plants with minimum or no modifications.

OBJECTS

Some of the objects of the present disclosure are - discussed herein below.

It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.

It is an object of the present disclosure to provide a process for producing alkylated aromatic hydrocarbons by using a non-hazardou.: and recyclable catalyst.

It is another object of the present disclosure to \. ovide a process for producing alkylated aromatic hydrocarbons which is scaled up in the HF technology-based manufacturing plants with minimum or no modifications.

It is yet another object of the present disclosure to provide an environmentally safe process for producing alkylated aromatic hydro rbons.

Other objects and advantages of the present di .closure will be more apparent from the following description when read in conjunction with the accompanying figures, which are not intended to limit the scope of the present disclosure. SUMMARY

In accordance with the present disclosure there is provided a process for preparing alkylated aromatic hydrocarbons, said process comprising the following steps; alkylating an aromatic hydrocarbon with an alkylating agent that comprises a mixture of at least one C₂ to C₅₀ olefin and at least one C₂ to C₅₀ paraffin, in the presence of at least one acid catalyst selected from the group consisting of (i) compounds having the molecular formula of RS0₃H, wherein R is independently selected from the group consisting of alkyl, aryl, halogen, or alkyl halide; (ii) ionic liquid composition comprising (a) at least one cationic precursor selected fror the group of compounds consisting of hydrogen donor compounds, tetra alkyl ammor ium halide, phosphonium halides, and imidazolium bromide; and (b) at least one ar. :nic precursor selected from the group consisting of metal halides and organic halides, at a temperature varying between 35°C and 90 °C, under atmospheric pressure to obtain a hydrocarbon layer containing an alkylated aromatic hydrocarbon.

Typically, the aromatic hydrocarbon is at least one selected from the group consisting of benzene and substituted benzene;said substituted benzene includes toluene, ethylbenzene, xylene and cumene.

Preferably, the aromatic hydrocarbon is benzene.

Typically, the alkylating agent is a mixture of ct least one C₁₀ to C₎₄ olefin and at least one Cio to Ci₄ paraffin.

Typically, the molar ratio of olefin to paraffi in the alkylating agent varies between 10:90 to 20:80, preferably 15:85.

Typically, the proportion of aromatic hydrocarbon and alkylating agent expressed in term of molar ratio varies between 1 :1 to 15:1, preferably between 2: 1 to 8: 1. Typically, the compound of molecular formuia RS0₃H is selected from the group consisting of methane sulfonic acid, p-toluene sulfonic acid and combinations thereof

Typically, the cationic precursor is at least one selected from the group consisting of tetra butyl ammonium halide, 1-buty 1-3 -methyl imidazolium bromide, trihexyl tetradecyl phosphonium halide, methyl sulfonic acid, p-teluene sulfonic acid and combinations thereof

Typically, the metal halide is selected from the group consisting of aluminum chloride and ferric chloride.

Typically, the organic halide is choline chloride.

Typically, the proportion of acid catalyst to hydrocarbon varies between 0.1 and 1.5

Typically, the alkylation is carried out at temperature varying between 50-70 °C

The process in accordance with the first a: >ect of the present disclosure further comprising the following steps: i. separation of the hydrocarbon layer from the catalyst; (ii) purification of the hydrocarbon layer obtained in method step (i) either by washing with water or aqueous alkali solution or centrifugation or decantation; (iii) re-circulation of the catalyst obtained in method step (i) m the process of alkylating aromatic hydrocarbon; and (iv) subjecting the hydrocarbon layer obtained in method step (ii) to a distillation process to separate the alkylated aromatic hydrocarbon.

BREIF DESCRIPTION OF THE ACCOMPNAYING DRAWINGS:

FIGURE 1 of the accompanying drawings illustrates a process flow diagram of the process of alkylation of aromatic hydrocarbon, it accordance with the present disclosure. DETAILED DESCRIPTION

Accordingly, a process for producing alkylated aromatic hydrocarbons by using a strong acid catalyst is envisaged in the present disclosure wherein the drawbacks and disadvantages allied with related prior-arts are completely alleviated.

Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the Inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

The use of the expression "at least" or "at lea.;t one" suggests the use of one or more elements or ingredients or quantities, as the r.se may be in the embodiment of the invention to achieve one or more of the desired objects or results.

In accordance with a first aspect of the present disclosure, there is provided a process for preparing alkylated aromatic hydrocarbons, said process comprising the following steps: alkylating an aromatic hydrocarbon with an alkylating agent that comprises a mixture of at least one C₂ to C₅₀ olefin and at least one C₂ to C₅₀ paraffin, in the presence of at least one acid catalyst selected from the group consisting of (i) compounds having the molecular formula of RS0₃H, wherein R is independently selected from the group consisting of alkyl, aryl, halogen, or alkyl halide; (ii) ionic liquid composition comprising (a) at least one cationic precursor selected from the group of compounds consisting of hydrogen donor compounds, tetrs alkyl ammonium halide, phosphonium halides, and imidazolium bromide; and (b) at ¾ast one anionic precursor selected from the group consisting of metal halides and organic halides, at a temperature varying between 35°C and 90 °C, under atmospheric pressure.

The aromatic hydrocarbon as used in the process of the present disclosure is benzene. In addition to benzene their substituted derivatives may also be used in the process of the present disclosure. Typically, the substituted benzene is at least one selected from the group consisting of toluene, xylene, ethylbenze e and cumene. The preferred aromatic hydrocarbon is benzene.

The alkylating agent as used in the process of the present disclosure is a mixture of olefin and paraffin. Typically, the olefin is C₂ to C₅₀ olefin, preferably C₎₀ to C₁₅ olefin. Generally, the olefin is mixed with paraffin having the same number of carbon atoms. Paraffin having 2 to 50 carbon atoms, preferable 10-15 carbon atoms is mixed with the olefin of the present disclosure to obtain an alkylating agent. The olefin as used in the process of the present disclosure is a straight or branched chain olefin and alpha-olefin or non-alpha-olefin. The varied combinations of ol lns and paraffins as the alkylating agent are suitably employed in the process of the pres : t disclosure.

In an embodiment of the present disclosure, the alkylating agent is a mixture of a single olefin and a single paraffin. In another embodiment, the alkylating agent is a mixture of a single olefin and two or more paraffins. In still another embodiment, the alkylating agent is a mixture of two or more olefins and a single paraffin. In yet another embodiment, the alkylating agent is a mixture of two or more olefins and two or more paraffins.

In the process of the present disclosure, an aromatic hydrocarbon feed is mixed with an alkylating agent feed to obtain a pre-mix feed. The pre-mixed feed is then charged in a reactor/vessel and further mixed with a catalyst feed to obtain a resultant feed. The reactor is then heated at a temperature varying between 35 °C to 90°C under ambient pressure condition, to initiate the aikylation of .aromatic hydrocarbon, and to obtain an alkylated product

Typically, the weight proportion of hydrocarbori and alkylating agent expressed in terms of molar ratio varies between 1 :1 and 15: 1, preferably between 2: land 8: 1 , in accordance with the process of the present disclosure. The alkylation of aromatic hydrocarbon in accordance with the present disclosure is accomplished by using a strong acid catalyst.

The inventors of the present disclosure particularly employ a strong acid catalyst for the alkylation of aromatic hydrocarbon which is non-hazardous and capable of being further used in the reaction.

In accordance with one of the embodiments of the present disclosure, the catalyst is a strong acid catalyst selected from the group consisting of compounds having the molecular formula of ROS₃H, wherein R is independently selected from the group consisting of alkyl, aryl or halogen or alkyl halides.

The preferred examples of the compound of m ;. lecular formula RSO₃H include at least one selected from the group consisting of met!" me sulfonic acid and p-toluene sulfonic acid.

In accordance with another embodiment of the present disclosure, the catalyst is an ionic liquid composition comprising (a) at least one cationic precursor selected from the group of compounds consisting of hydrogen donor compounds, tetra alkyl ammonium halide, alkyl or aryl imidazolium bromide, and alkyl or aryl phosphonium halides; and (b) at least one anionic precursor selected from the group consisting of metal halides and organic halides.

The ionic liquid composition as used in the process of the present disclosure is a eutectic mixture that comprises the combination of a' - organic salt and a metal halide or an organic halide as cationic and anionic precujcprs, respectively. The anionic and the cationic precursors are mixed in a stoichiometric weight proportions to obtain eutectic ionic liquid compositions of the present disclosure. In accordance with one of the preferred embodiment of the present disclosure, the hydrogen donor compound in combination with at least one metal halide/organic halide is used as the ionic liquid catalyst.

Typically, the hydrogen donor compound is selected from the group consisting of methyl sulfonic acid, p-toluene sulfonic acid.

In accordance with another embodiment of the present disclosure, the combination of at least one cationic precursor selected from the group of compounds consisting of tetra alkyl ammonium halide, imidazolium bromide?:, and phosphonium halides, and at least one anionic precursor selected from the group consisting of metal halides and organic halide is used as the ionic liquid catalyst.

The preferred examples of cationic precursors other than the hydrogen donor compounds include at least one selected from the group consisting of tetra butyl ammonium chloride, trihexyl tetradecyl phoshonium bromide, 1- Benzyl-3-methyl imidazolium bromide and 1- Butyl-3-methyl imidazolium bromide.

The metal halide in accordance with the process of the present disclosure includes at least one selected from the group consisting of aluminum chloride or ferric chloride. The preferred organic halide is choline chloride.

The ratio of catalyst feed to hydrocarbon feed ir« accordance with the present disclosure typically varies between 0.1 and 1.5.

The ionic liquid compositions in accordance with the process of the present disclosure are either procured readymade or prepared by employing methods known in the prior-art. Preferably, the catalyst with 99.5 % purity is used. Alternatively, the feed containing the pure catalyst is mixed with recycled/regenerated catalyst. The alkylation of benzene or substituted benzete js in accordance with the process of the present disclosure produces alkylated benzene/alf lated substituted benzenes.

After completion of the reaction, a hydrocarbon layer containing an alkylated aromatic hydrocarbon (hereinafter refer as an alkylated product) is obtained. In addition to the alkylated product, the hydrocarbon layer also comprises the residual hydrocarbon and the alkylating agent. The feed containing the hydrocarbon layer along with the catalyst layer is processed further to separate the alkylated products. Accordingly, the process of the present disclosure further comprises the following steps: (i) separating the catalyst layer from the hydrocarbon layer; (ii) purification of the hydrocarbon layer to remove traces of acid catalyst residues; (iii) subjecting the purified hydrocarbon layer obtained in method step (ii) to a fractional distillation to separate alkylated product and residual aromatic hydrocarbon; (iv) recycling of the residual hydrocarbon in the alkylation process, and (v) optionally, the purification of recovered and rec¾ling.

The alkylation of aromatic hydrocarbon in accordance with the process of the present disclosure is carried out in a reactor or in a n ixer. Preferably, a mixer such as static mixer, jet mixer, pump mixer or stirrer is used. Further, a single reactor/mixer or a series of two or more mixers/reactors are used in the process of the present disclosure.

The feed, as obtained from the mixer/reactor after completion of the reaction, is introduced in a settler wherein the catalyst feed separates from the hydrocarbon layer. The hydrocarbon layer containing the alkylated product and the residual hydrocarbon is then subjected to de-acidification to remove traces of acid catalyst residues. The acidification is carried out either by water- ash or neutralization with an alkali or centrifugation or chilling. The de-acidified hydr ocarbon layer is then distilled to remove the alkylated product.

The process of alkylating aromatic hydrocarbon in accordance with the present disclosure is further described with reference to Figure-! of the accompanying drawings. The

ί

provided figure- 1 illustrates the process flow diagram representing the sequence of unit operations involved during the alkylation of aromatic hydrocarbon in accordance with the present disclosure.

The aromatic hydrocarbon feed (2) is mixed wi&the" alkylating agent feed (4) to obtain a pre-mix feed. The proportions of aromatic hydrocarbon and alkylating agent expressed in terms of molar ratio varies between 1 :1 and 15: 1, preferably between 2:1 to 8: 1. The pre- mixed feed is then fed to a mixer Ml where it is mixed with a catalyst stream (6). The volume ratio of catalyst to aromatic hydrocarbon feed varies between 0.1 and 1.5. The first mixer Ml is maintained at a temperature typically varying between 30 to 80 °C, under pressure varying from 1 to 5 atmospheres to initiate the alkylation process. After completion of the alkylation process, the feed from the first mixer Ml is then transferred to a second mixer M2, through an outlet provided in Ml . Further alkylation of the feed.is accomplished in the second mixture M2. The temperature and pressure conditions in the second mixer M2 are the same as in Ml. Alternatively, the temperature and pressure conditions are different from Ml .

Optionally, the feed discharged from Ml is introduced in a settler provided between Ml and M2. In this settler, the feed received from Ml. separates into two distinct layers: (i) an upper hydrocarbon layer containing the alkylated aromatic hydrocarbon and the residual aromatic hydrocarbon, and (ii) lower catalyst layer. The upper hydrocarbon layer is then transferred to M2 and mixed with the catalyst feed (6), whereas the lower catalyst layer is recycled to mixer M1/M3 directly or through a c italyst recovery- unit (CRU).

After completion of the alkylation reaction in the second mixer M2, the feed is transferred to settler SI. In SI, the feed separat s into two distinct layers, similar to the separation as observed in the above described settler. The heavier catalyst layer via stream 8 is recycled to mixer Ml directly or through catalyst recovery unit CRU whereas the upper hydrocarbon layer is fed to mixer M3 via line 10 which is further mixed with a catalyst feed via line 6. Similar to the alkylation as carried out in mixer Ml and M2, further alkylation of the feed is accomplished in Mixer M3 so as to achieve higher percent conversion of aromatic hydrocarbon to* alkylated aromatic hydrocarbon. After completion of the alkylation reaction in mixer M3, the feed from M3 is fed into settler S2 where separation of the hydrocarbon layer and tfie catalyst layer is accomplished, similar to the separation as carried out in settler SI.

The processing units Ml, M2, M3, and SI ami S2 as employed in the process of the present disclosure can be arranged in multiple ce, ^figurations.

In accordance with one of the embodiments of the present disclosure, the alkylation of aromatic hydrocarbons is carried out in a single mixer. In this embodiment, the feed from mixer Ml is directly fed to settler S2.

In accordance with another embodiment of t- e present disclosure, the alkylation of hydrocarbons is carried out in a series of two mixers, for example in a series of Ml and M2. In this embodiment, the feed from second n ixer i.e. M2 is fed into settler S2. In this settler, the feed separates into an upper hydrocav on layer and a lower catalyst layer. The lower catalyst layer via line 8 is recycled to mi;;er Ml through CRU whereas the upper hydrocarbon layer is fed to hydrocarbon layer purifier (PR) via line 14. In the purifier, the hydrocarbon layer is washed either with watc- or with alkali solution via line 16 to remove traces of acid catalyst. Alternatively, the hydrocarbon layer is directly centrifuged

Ί

without addition of water or alkali solution, or crystallized to remove traces of acid catalyst. Accordingly, the hydrocarbon purifier is either a stirred vessel or a centrifuge separator or a crystallizer. In an embodiment, wherein the hydrocarbon purifier is a crystallizer, the traces of acid catalyst are crystallized by a sudden decrease in the temperature of the hydrocarbon layer i.e. below \5 °C.

Typically, the volume ratio of water/alkali solu ion to hydrocarbon layer varies between 0.2: 1. In an embodiment, when purification of drocarbon layer is carried out by alkali wash, the concentration of alkali solution ranges' between 2 to 50%.

In still another embodiment of the present disclosure, the alkylation of aromatic hydrocarbons is carried out in a series of three mixers i.e Ml , M2 and M3. In this embodiment, the upper hydrocarbon layer from settler SI is fed to a mixer M3 and further mixed with the catalyst stream (6) to somplete the alkylation of the residual t

aromatic hydrocarbon. The feed from M3 is then fed into settler S2 to separate the

^'i

hydrocarbon layer and the catalyst layer, simile? to the separation as observed in settler SI . The hydrocarbon layer from settler S2 ½ then introduced into a hydrocarbon purification unit and processed further, similar to the process as described in above embodiment of the present disclosure.

The hydrocarbon layer from PR is directly fe ί to settler S3 where separation of the alkylated product and the residual aromatic hydrocarbon occurs. In an embodiment, wherein water or alkali wash is used in the hydrocarbon purification unit during the de- acidification of the hydrocarbon layer, the bottcn layer in settler S3 is an aqueous layer. The bottom aqueous layer is sent for effluent treatment via line 18. In an embodiment, wherein centrifugation or crystallization is carded out in the hydrocarbon purification unit during the de-acidification of the hydrocarbon layer, the bottom layer in S3 is the catalyst layer with traces of acid catalyst, which is further fed to CRU via line 18.

The upper hydrocarbon layer from S3 is fed to fractionating column Dl where the

1

residual aromatic hydrocarbon is distilled off nd recycled to line 2 via line 22. The residue of Dl is fed to fractionating column 02 via line 24 to remove and recover paraffin via line 26. The residue of fractionating D2 is fed to fractionating column D3 to separate lower alkylated aromatic hydrocarbon ¾y line 30 and heavy alkylated aromatic hydrocarbon by line 32. The distillation columns Dl, D2 & D3 are operated under ambient pressure or or under vacuum. Prior to fractional distillation, the upper hydrocarbon layer is analysed for bromine inc' x for olefin determination. The percent conversion of olefin in accordance with the present process is 98.89 %.

The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments ! erein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples-should not be construed as limiting the scope of the embodiments herein.

Example 1

The example is as per the process described in E ;gure 1 of the accompanying drawings.

1106 ml (810.5 gm) of olefin stream containing 10-15% C_10-C₁₄ olefins and 85-90% C,₀- C₁₄ paraffin was added into a 4000 ml jacketed glass cylindrical vessel with an overhead stirrer. The stirrer consisted of two 45° pitch blac^ turbines placed approximately 150 mm apart. The blades were arranged is a manner that ©ne blade was immersed in the lower catalyst layer and the other blade was immersed in the upper hydrocarbon layer when there was no mixing, to get maximum dispersion during the mixing. The Hot water at 60- 65 °C was circulated inside the jacket so thai the temperature inside the vessel was maintained at 60 °C. 619 ml (521.2 gm) bc izene was added to the above olefin containing stream. Both the reactants were mixed for 10-15 mins at 60 °C. 1725 ml (2519 gm) of fresh pre-heated methane sulphonic acid was added to the above mixture. The reaction mass was stirred for 1.5-2 hrs at 60 °C. After 2hrs, without stirring the reaction mixture was cooled to 30 °C. The layers were, hen separated. The lower catalyst layer was collected in a separate vessel while the u per hydrocarbon layer remained in the cylindrical vessel. 1100 ml (1100 gm) of distilled water was added to the above hydrocarbon layer. The mixture was stirred wall for 1 hr at 35-40 °C. After 1 hr the mixture was allowed to settle for 20-30 mins. The layers were then separated. The lower water layer was discarded while the upper hydrocarbon layer was collected and kept aside. The hydrocarbon layer as obtained in accordance with the process of this example was analyzed quantitatively and about 3590 gm (4600 ml) of hydrocarbon layer was prepared. The hydrocarbon layer was further subjected to distillation. The distillation column contained a 5 lit glass flask as a reboiler which was connected at its upper end with a hollow cylindrical tube of 400 mm height and 40 mm diameter. The cylindrical tube further contained a perforated plate at the bottom to withstand the packing; the tube was packed with 6-8mm glass raschig rings. Over the cylindrical tube, a reflux divider was provided to maintain the desired reflux ratio. A condenser was provided at the top of the column. A thermowell was inserted inside the reboiler. Another thermowell was kept in the reflux divider to measure the vapour temperature. A manometer was assembled to the distilallation column to measure the vacuum inside the column. In the distillation column, benzene was distilled at atmospheric conditions whereas paraffin and linear alkyl benzene was di:.tilled under vacuum.

3590 gm (4600 ml) of hydrocarbon layer containing linear alkyl benzene, un-reacted benzene and residual alkylating agent was charged into the reboiler. The reboiler was heated. Initially no vacuum was applied and benzene was distilled at atmospheric pressure and vapor temperature maintained between 79-81 °C. During benzene distillation, re-boiler temperature was maintained between 1 15 to 185 °C. When the collection of distilled benzene was stopped, the re-boiler was cooled. Followed to benzene distillation, linear alkyl benzene and residual paraffin were distilled. For this, the vacuum with a very slow rate was applied and re-boiler was heated at a temperature of 110 °C. The pressure inside the column was maintained at 9-10 mm Hg. During vacuum distillation, initially paraffin was distilled followed by distillation of linear alkyl benzene. During paraffin distillation, vapour temperature, increased from 80- 150 °C and reboiler temperature increased from 110 to 175 °C. -uririg linear alkyl benzene distillation, vapour temperature increased from 155- 205 °C and reboiler temperature increased from 175 to 325 °C. After distillation, the reboiler was cooled and residue was collected separately. Weight of distilled benzene : 721 g

Weight of distilled paraffin : 2529.5

Weight of distilled linear alkyl benzene : £46.2 g

Weight of residue 25.6 g ¹ '

Example-2:

This example describes a process for the alkylation of benzene by using an ionic liquid catalyst composition.

865 ml (634 gm) of olefin feed containing 10-15% C_]0-C₁₄ olefins and 85-90% C₁₀-C,₄ paraffins was added into a 2000 ml jacketed glass cylindrical vessel with an overhead stirrer. The stirrer consisted of two 45 ° pitch blade turbines which were approximately 150 mm apart. The blades were arranged in a manner that one blade (bottom blade) gave an upward flow and the other blade (top blace) gave a downward flow. The Hot water at 45-47 °C was circulated inside the jacket so that the temperature inside the vessel was maintained at 45 °C. 335 ml (291 gm) benzene was added to the above olefin stream. Both the reactants were mixed for 10-15 mins 45 °C. Subsequently, 12 gm of the ionic liquid composition comprising a eutectic m cture of 1 -butyl-3-methyl-imidazolium bromide and aluminum trichloride was added. The resultant feed thus obtained was stirred for 10-15 minutes at 45 °C. After 15 minutes, the resultant feed was cooled to 30 °C and introduced into a settler to separate the hydrocarbon layer from the catalyst layer. Further processing of the hydrocarbon layer and the catalyst layer was carried out in the same manner as described in the process of example- 1. The upper hydrocarbon layer was analysed for bromine index for olefin determination and the olefin conversion obtained was 98.89 %.

TECHNICAL ADVANTAGES

The present disclosure related to a process for preparing alkylated product aromatic hydrocarbons has the following technical advantages:

i (1) Replacement of toxic hydrogen fluoride by a safer and biodegradable catalyst, and

(2) The use of HF based manufacturing plants with minimum or no modifications.

The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the invention, unless there is a statement in the specification specific to the contrary

The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described ir terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.

Claims

Claims:

1. A process for preparing alkylated aromatic hydrocarbons, said process comprising the following steps; alkylating an aromatic hydrocarbon with an alkylating agent that comprises a mixture of at least one C₂ to C₅₀ containing olefin and at least one C₂ to C50 containing paraffin, in the presence of at least one acid catalyst selected from the group consisting of (i) compounds haying the molecular formula of RS0₃H, wherein R is independently selected frcm the group consisting of alkyl, aryl, halogen, or alkyl halide; (ii) ionic liquid composition comprising (a) at least one cationic precursor selected from the groi?;. of compounds consisting of hydrogen donor compounds, tetra alkyl ammo : um halide, phosphonium halides or imidazolium bromide; and (b) at least c e anionic precursor selected from the group consisting of metal halides and organic halides, at a temperature varying between 35°C and 90 °C, under atmospheric pressure to obtain a hydrocarbon layer containing an alkylated aromatic hydrocarbon.

2. The process as claimed in claim 1 , wherein the aromatic hydrocarbon is at least one selected from the group consisting o: benzene and substituted benzenes; said substituted benzenes include toluene, ethylbenzene, xylene or cumene.

3. The process as claimed in claim 2, wherein the aromatic hydrocarbon is benzene.

4. The process as claimed in claim 1, wher ^:n the alkylating agent is a mixture of at least one C)₀ to C₁₄ olefin and at least onf iG ₁₀ to C₁₄ paraffin .

5. The process as claimed in claim 1, wher- n the molar ratio of olefin to paraffin in the alkylating agent varies between 10:9Θ to 20:80, preferably 15:85.

6. The process as claimed in claim l _i wherein the proportion of aromatic hydrocarbon and alkylating agent expressed in term of molar ratio varies between 1 : 1 to 15: 1, preferably between 2: 1 to 8 : 1

7. The process as claimed in claim 1, wherein the compound of molecular formula RS0₃H is selected from the group consisting of methane sulfonic acid, p-toluene sulfonic acid and combinations thereof.

8. The process as claimed in claim 1, wherein the cationic precursor is at least one selected from the group consisting of tetra butyl ammonium chloride, l-butyl-3- methyl imidazolium bromide, trihexyl tetradecyl phosphonium bromide, methyl sulfonic acid, and p-toluene sulfonic acid.

9. The process as claimed in claim 1, wherein the metal halide is selected from the group consisting of aluminum chloride ar \ ferric chloride.

10. The process as claimed in claim 1, wherein the organic halide is choline chloride.

11. The process as claimed in claim 1 , w! "rein the proportion of acid catalyst to hydrocarbon varies between 0.1 to 1.5

12. The process as claimed in claim 1 , wherein the alkylation is carried out at a temperature varying between 50-70 °C.

13. The process as claimed in claim 1 further comprising the following steps: i. separation of the hydrocarbon layer from the catalyst; (ii) purification of the hydrocarbon layer obtained in metiiod step (i) either by washing with water or aqueous alkali solution or entrifugation or decantation; (iii) recirculation of the catalyst obtair¾<i in method step (i) in the process of alkylating aromatic hydrocarbon; nd (iv) subjecting the hydrocarbon layer obtained in method step (ii) t a distillation process to separate the alkylated aromatic hydrocarbon.