RU2396254C2 - Method of obtaining highly soluble linear alkylbenzolsulphonates - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to method of obtaining highly soluble alkyl-aromatic sulphonate with regulated content of 2-phenyl isomer from 18% wt to 70% wt, by means of catalytic alkylation of aromatic compound by purified alkylating agent, which includes the following stages: 1) catalytic dehydration of linear paraffin raw material; 2) selective hydration of diolefins, obtained as by-product at stage (1), to monoolefins; 3) purification of raw material alkylating agent, obtained at stage (2), separation of non-linear products, contained in output flow of stage (2); processing of non-linear products, extracted at stage (3) for formation of hydrotropic precursor; 5) alkylation of aromatic hydrocarbon with monoolefins present in purified alkylating agent, by combination of the following alkylation methods: a) method of alkylation with catalyst, forming raw material liner alkyl aromatic compound with maximal content of 2-phenyl isomer, constituting 20% wt; b) method of alkylation with catalyst, forming raw material linear alkyl aromatic compound with minimal 2-phenyl isomer, constituting 20% wt; 6) separation into fractions of stage (5) output flow in order to separate unreacted aromatic compounds, paraffins and the heaviest by-products of linear alkyl aromatic compounds; 7) purification of fraction of linear alkyl aromatic compounds supplied from stage (6); 8) sulfonation of purified linear alkyl aromatic compounds obtained at stage (7); 9) neutralisation of linear alkyl sulphonic acid, obtained at stage (8), different in that catalyst, which forms maximally 20 % wt of 2-phenyl isomer, includes zeolite of FAU type, from 0.01% wt to 0.15% wt of at least one metal, selected from group, consisting of Li, Na, K, Mg or Ca, and from 0.1% wt, to 8% wt of at least one rare earth metal, selecxted from group, consisting of La, Ce, Pr, Nd, Pm, Sm or Eu; and catalyst, forming minimally 20% wt of 2-phenyl isomer, includes zeolite of MOR type, from 0.01% wt to 0.2% wt of at least one metal, selected from group, consisting of Li, Na, K, Mg or Ca, with maximal content of Na equal 0.01%, and from 0 to 0.5% wt of at least one metal, selected from group, consisting of Ti, Zr, Hf.

EFFECT: obtaining alkyl aromatic sulphonate with extremely low coloration after sulfonation with maximised detergent properties.

24 cl, 24 tbl, 4 dwg, 7 ex

Description

The present invention generally relates to catalytic alkylation reactions and, in particular, to zeolite type catalysts.

Alkylaromatic compounds are an important family of substances that are used as raw materials in many industries, such as plasticizers, polymers, insecticides, to prevent agglomeration of fertilizers in agriculture, in the production of textile materials and fibers, in the manufacture of leather and furs, herbicides , in industrial cleaning methods, in the photographic industry, in the production of adhesives and fire-fighting products, such as wetting agents, in electrochemicals eskih methods of removing dirt and grease from the surface of the substance and in biodegradable detergents (Surfactants in Consumers Product, Theory, Technology and Application, edited by J. Falbe, Springer Verlag, 1987).

The usual method used in the petrochemical industry for the production of alkyl aromatic compounds, especially for use in detergents, consists of dehydrogenation of linear paraffins to obtain linear monoolefins and then alkylation of benzene with said monoolefins. Linear alkylbenzenesulfonate (LAS) is obtained by sulfonation of linear alkylbenzene (LAB) and subsequent neutralization of the corresponding sulfonic acids (H-LAS). The linear olefins used in this method have nine to sixteen carbon atoms. The alkylation step is carried out in the liquid phase in the presence of Friedel-Kraft type catalysts, for example hydrofluoric acid. The method in the presence of HF is well known and used in industry, giving a high yield (> 99 wt.%) LAB with a relatively low selectivity for the 2-phenyl isomer, less than 20%. A combined method for producing LAB is described in Handbook of Petroleum Refining Process, published by Robert A. Meyers, 1986, p.1-23, incorporated herein by reference. US Pat. No. 5,276,231 describes intermediate steps of a method for producing LAB, such as the selective hydrogenation of diolefin by-products from the dehydrogenation of paraffins and the removal of non-linear by-products from the dehydrogenation stage stream. The use of HF has some drawbacks, as it requires careful handling and special equipment due to its corrosive activity, which leads to an increase in current and operating costs; as a result, an attempt was made to develop alternative catalysts based on acidic solids.

The prior art describes many solid acid catalysts for the production of phenylalkanes, such as synthetic faujasites (zeolites X and Y), zeolites L, ZSM-5, ZSM-18, ZSM-20, mordenite and offretite. Modern developments, which use several types of zeolites, amorphous aluminosilicates and other types of materials as alkylation catalysts, are described for the production of LAB containing 2-phenyl isomer in the range from 20 to 80 wt.% (JLBerna Tejero, A. Moreno Danvila, US Pat. No. 5,157,158, 1992 and JLG De Almedia, M. Dufaux, Y. Ben Taarit, C. Naccache, Journal of the American Oil Chemist's Society, Vol. 71, no. 7, 675-694, 1 1994). The solid zeolites mentioned here as catalysts are defined in the Atlas of Zeolite Framework Types, W. M. Meier, D.H. Olson and C. H. Baerlocher, 5th revised edition, 2001, Elsevier, referred to in the present invention.

One of the crystalline aluminosilicates that can be used as a catalyst in this type of reaction is a zeolite of the FAU family, designated zeolite Y, the composition of which is as follows:

Na ₅₆ [Al ₅₆ Si ₁₃₆ O ₃₈₄ ]: 250H ₂ O

Zeolite Y has a porous three-dimensional structure with pores located perpendicular to each other in the x, y, and z planes. The pore diameter is large, about 7.4 Å, while the hole is defined by a ring of 12 oxygen atoms and leads into a large cavity with a diameter of 12.5 Å. It structurally includes a three-dimensional framework of SiO ₂ and AlO ₄ tetrahedra connected to each other via common oxygen atoms. When a tetravalent silicon ion is isomorphically substituted with a trivalent aluminum atom in a silicon framework including silicon tetrahedrons, the resulting negative charge must be stabilized by an adjacent positive ion, such as a proton. The latter can be obtained by dissociation of water forming a hydroxyl group on an aluminum atom. The resulting structure is Bransted acid (C. N. Satterfield, Heterogeneous Catalysts in Practice, McGraw-Hill Inc., 1980, page 152). When the latter is heated, water is extracted from the composition and the active centers of Bransted acid are converted into the active centers of the Lewis acid. Dehydrated zeolites can have both active Bransted acid sites and active Lewis acid sites, depending on ion exchange and heat treatment conditions. As a result of their microporous structure, zeolites can produce a much larger number of available active acid sites on the surface area of a solid, in contrast to the standard amorphous aluminosilicate catalyst used in alkylation.

In practice, when an aromatic compound is alkylated using solid acid catalysts, dialkylated, as well as monoalkylated, products are formed, especially when the reaction proceeds under conditions of a high degree of conversion and the aromatic compound is benzene. In addition to acidity, zeolite Y has another important property related to catalytic activity. Due to their crystal structure, zeolite channels or pores are microscopically small, therefore, their small size and their molecular configuration have an extraordinary effect on the selectivity of the reaction, since they can prevent the formation of more bulky compounds, such as some types of heavy alkylates, also known as dialkylbenzenes . This effect is called selectivity 0, due to pore size.

It is well known that the presence of rare earth elements can strongly affect the strength and density of acidic active sites in zeolite material (L. B. Zinner, K. Zinner, M. Ishige and AS Araujo, Catalytic activity of lanthanide-doped Y Zeolite on the alkylation of benzene with 1-dodecene model reaction, Journal of Alloys and Compounds, 193, 65-67, 1993). After ion exchange with rare-earth elements, aluminum silicate is an activated crystalline catalyst in which the atomic structure is modified because it has chemisorbed or ion-bound rare-earth metal cations. Rare earth cations can be prepared from a single metal salt or, preferably, from a mixture of salts of various metals, such as light rare earth chlorides or didyme chlorides (La, Ce, Pr, Nd, CAS: 11098-090-1). In most applications, rare earth mixtures are preferred since they can be easily obtained commercially and are much more cost effective than refined rare earth metals. R. B. Venua et al. published in the Journal of Catalysts, 4, 81-98, 1966 the possible use of highly acidic solid catalysts, such as rare earth metal ion exchange exchange type faujasites X and Y, designated REY and REX, for the alkylation of benzene with olefins. In the Brazilian patent P.I. 9204326-7 shows the use of a catalyst based on zeolite faujasite, in particular zeolite Y, activated by Ca and lanthanides, in particular La, Ce, Nd or Gd. The patent claims a method in a batch solid-state reactor operating under conditions of complete mixing with a super acid catalyst operating at temperatures as low as 80 ° C.

Another alkylation catalyst that is often used in these reactions is a zeolite with a structure of the MOR type, mordenite, which is characterized by a molar ratio of SiO ₂ / Al ₂ O ₃ equal to 10. The composition of its typical unit cell is:

Na ₈ [(AlO ₂ ) ₈ (SiO ₂ ) ₄₀ ] × 24H ₂ O

The crystal structure shows a system of channels of 12-membered rings with a free diameter of 6.7 × 7 Å, and these main channels are interconnected by small channels bounded by 8-membered rings with an opening of 2.9 × 5.7 Å. These small channels impede the passage of most organic molecules; as a result, the porous mordenite skeleton basically looks like a unidirectional porous structure. A dealumination method of mordenite by hydrotreatment followed by acid treatment can modify its structure and catalytic characteristics, increasing the adsorption capacity and diffusion rate of molecules, as described in the link entitled "Alquilation du benzene par le 1-dodecene sur catalyseurs zeolithiques", JLAlmeida , PhD, abstracts presented in Universite Claude Bernard-Lyon 1, 1994. The following patents US 2003/0166481-A1, US 6521804-B1, US 6133492 and US 6562776-B1, incorporated herein by reference, describe an alkylation process in wherein the mordenite type catalyst can be mixed with various catalysts that do not produce a high content of the 2-phenyl isomer, therefore, the amounts of each catalyst must be selected to obtain the desired levels of the 2-phenyl isomer in the product.

The method for producing alkylaromatic compounds or alkylates by alkylation of benzene with long chain olefins is characterized, in terms of selectivity, by the content of heavy alkylates, the content of the 2-phenyl isomer and also the content of branched alkylates. These chemicals, which determine the effectiveness of the process and the quality of the product, mainly depend on the type of catalyst, the quality of the starting material, and the process conditions.

The group of heavy alkylates includes a combination of chemicals with a molecular weight exceeding that of the monoalkylated product. They are usually formed by diacylbenzenes, diphenylalkanes, oligomerized olefins and alkylates of these oligomerized olefins formed during the alkylation step. These products are mainly obtained by alkylation of monoalkylbenzene preformed with an olefin. Diphenylalkanes are formed by alkylation of benzene with a diolefin that has been dehydrocyclized. The formation of this type of product is undesirable, since it reduces the overall yield of the process and can degrade the quality of the resulting alkylate, thereby reducing economic feasibility. Additionally, there are other compounds that need to be considered, for example, some alkyl polyaromatic products formed by the alkylation of monoolefins of polyaromatic compounds obtained in the dehydrogenation step. These products can be extracted together with the heaviest LAB compounds, since the range of the boiling point of their fraction overlaps with the range of the boiling point of the fraction of these LAB. These products significantly reduce the quality of the sulfonated final product N-LAS, since the color after sulfonation increases very much.

2-phenyl isomers are alkyl molecules having an aromatic ring attached to an alkyl chain at position 2 of the chain. The content of the 2-phenyl isomer is defined as the mass percentage of the 2-phenyl isomer in a mixture of LAB or LAS and calculated by the following formula:

2-phenyl isomer [%] = (mass of 2-phenyl isomer) × 100 / (total mass of LAB or LAS)

LAB mixtures with the content of external isomers (2 + 3 phenyl) in excess of 60 wt.% Are characterized by the fact that they provide LAS with improved surface activity after sulfonation and neutralization. These LAS, however, have an important drawback, due to their low solubility in cold water, low stability under conditions of high viscosity. LAS mixtures, including more than 60 wt.% Of external isomers (2 + 3 phenyl), tend to form highly insoluble gels with high viscosity, making it difficult to handle and process them. For this reason, it is desirable to include a hydrotrop in order to improve the solubility of the final surfactant when the content of the 2-phenyl isomer is above 60 wt.% Although there are many patents related to the use of hydrotropes, one of them is considered as the most recommended for this method. PCT / ES 2005000169 relates to a method for producing a suitable hydrotrope based on pre-dehydrogenated paraffins, in particular based on their by-products recovered during the purification step of monoolefins.

Finally, branched alkylates can be defined as the percentage of all monoalkylates in which the alkyl chain attached to the aromatic ring is not a linear or normal alkyl group, but is branched. These abnormal alkyl groups possess radicals such as methyl, ethyl, propyl, isopropyl, butyl, isobutyl, tert-butyl and various hexyl, heptyl, octyl variants linked to the alkyl chain anywhere except at the ends of the chain. Branched alkylates are formed by alkylation from such branched paraffins that are present in fresh starting paraffins, or by alkyl rearrangement processes that occur during the dehydrogenation and alkylation steps. Branched alkylates include alkylates having one of the carbon atoms of an aliphatic alkyl group at the position of the quaternary carbon. A quaternary carbon atom in an alkyl chain is defined as carbon attached to four other carbon atoms, and one of these atoms can be bonded to the carbon atom of the phenyl group to form a quaternary alkyl phenylalkane. If the quaternary carbon is the second carbon atom in the alkyl chain, then the quaternary carbon present in the resulting 2-alkyl-2-phenylalkane can be called the “final quaternary carbon”. It is known that these substances, like simple branched alkylates, have a biodegradation rate similar to that of alkylbenzenesulfonate. However, when the quaternary carbon is any other carbon atom of an alkyl chain, for example 5-methyl-5-phenylalkane, it is called “internal quaternary carbon” and the corresponding alkylbenzenesulfonate has a much lower biodegradation rate. In the articles entitled "Iso-branching of LAS biodegradation study of two model compounds", L. Cavalli, G. Cassani, M. Lazzarin, C. Maraschin, G. Nuzzi, JLBerna, J. Bravo, J. Ferrer, A .Masno, Toxicology & Environmental Chemistry, Vol. 54, page 167-186, 1966 and Biodegradation of co-products of commercial LAS, AMNielsen, LN Britton, L. Cavalli, JL Berna, The Cler 20 Review, Vol. 1.2, N.1, p.14-27, 1996, provides scientific evidence of the biodegradable behavior of these alkylbenzene derivatives.

The alkylation reaction can be finally evaluated using the following indicators: degree of conversion, selectivity for monoalkylbenzene, distribution of isomers, and deactivation rate.

1) the degree of conversion of alkylation, or, more specifically, the relative degree of conversion: In the alkylation reaction of this invention, benzene is always used with a stoichiometric excess with respect to olefins. The relative degree of conversion can be defined as the proportion of limiting reagents, in this case olefin, which are consumed to obtain all products, thus:

The degree of conversion = [(N _A0 -Na) / N _A0 ] × 100,

where N _A0 is the number of moles of olefin at the inlet to the reactor and N _A is the number of moles of the same reagent at the outlet of the reactor.

2) Monoalkylbenzene selectivity is defined as

Se / _mab = [W _mab / (W _lay + W _mab + W _strand )] × 100,

where the W _mab is the mass of the monoalkyl _{benzene in} question obtained, the W _leg is the mass of by-products lighter than the lightest monoalkyl benzene in question, and the W _strand is the total mass of all substances whose molecular weights are higher than the molecular weights of the obtained monoalkylates, and as indicated, they are usually formed from dialkylbenzenes, diphenylalkanes, oligomerized olefins and alkylates of these oligomerized olefins. The masses or mass percentages of each product family can be used to calculate selectivity.

3) Isomer distribution. Among the obtained monoalkylbenzenes, the distribution of isomers can be defined as the mass percentage of each type of isomer obtained, such as 2-phenyl, 3-phenyl ... 6-phenyl isomers, as well as branched alkylates.

линейный 2-фенил изомер (R = линейный)

linear 2-phenyl isomer (R = linear)

линейный 3-фенил изомер (R = линейный)

linear 3-phenyl isomer (R = linear)

линейный 6-фенил изомер (R = линейный)

linear 6-phenyl isomer (R = linear)

разветвленный n-фенил изомер (разветвленный R или R′, n=2-6)

branched n-phenyl isomer (branched R or R ′, n = 2-6)

The distribution of isomers plays an important role for the general economic feasibility of the production method, for the quality of the final sulfonated product and also for its biodegradation rate.

4) The rate of catalyst deactivation: this variable is defined as the ratio of the activity of the catalyst at the considered time and the activity of the catalyst at time zero:

Catalyst deactivation rate = catalyst activity (t) / catalyst activity (t = 0)

The activity of the catalyst is considered in terms of the degree of conversion:

Catalyst deactivation rate = degree of conversion (t) / degree of conversion (t = 0).

Catalyst deactivation is caused either by poisoning of the active sites (irreversible decontamination) or contamination processes (formation due to collisions at the active sites or pores of the catalyst, usually reversible by controlled burning or pyrolysis).

Therefore, there is a need for a method for producing a highly soluble linear alkylbenzenesulfonate with maximized detergent properties, extremely low color after sulfonation, optimal environmental behavior and the most effective conditions for the use of raw materials.

The present invention relates to a very efficient method for producing a highly soluble linear alkylbenzene sulfonate with a controlled content of 2-phenyl isomer and extremely low color after sulfonation, using a catalytic system based on highly stable solid catalysts, with high selectivity for linear monoalkylated compounds, which solves the problems described in the present prior art.

Therefore, the first aspect of the invention relates to a method for producing highly soluble linear alkylbenzenesulfonate containing 2-phenyl isomer from 18 to 70 wt.% By catalytic alkylation of aromatic compounds with an alkylating agent, comprising the following stages:

1) the catalytic dehydrogenation of linear paraffin feedstock, whereby linear monoolefins, non-converted paraffins and a certain amount of by-products such as diolefins and non-linear compounds are obtained;

2) the selective hydrogenation of diolefins obtained as a by-product of step (1) into monoolefins, whereby a raw alkylating agent is obtained;

3) purification of the feed alkylating agent by separating non-linear products contained in the effluent of step (2), whereby a purified alkylating agent formed by monoolefins and paraffins is obtained;

4) processing non-linear products extracted in stage (3), with the formation of a hydrotropic precursor;

5) alkylation of an aromatic hydrocarbon with monoolefins present in a purified alkylating agent by combining two alkylation methods based on:

a) an alkylation method with a catalyst forming a linear linear alkyl aromatic compound with a maximum content of 2-phenyl isomer of 20 wt.%;

6) an alkylation process with a catalyst forming a linear linear alkyl aromatic compound with a minimum content of 2-phenyl isomer of 20 wt.%;

b) fractionation of the effluent of stage (5) to separate unreacted aromatic compounds, paraffins and the most severe by-products of the considered alkyl aromatic compounds;

7) purification of the fraction of the considered aromatic compounds coming from stage (6);

8) sulfonation of the purified linear alkyl aromatic compounds obtained in stage (7);

9) neutralization of the linear alkyl sulfonic acid obtained in stage (8).

This method is characterized in that the catalyst forming a maximum of 20% of the 2-phenyl isomer includes a zeolite of the FAU type, from 0.01 to 0.15 wt.% Of at least one metal selected from the group consisting of Li, Na, K , Mg or Ca, and from 0.1 to 8.0 wt.% At least one rare earth metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm or Eu; and the fact that the catalyst forming at least 20% of the 2-phenyl isomer comprises a MOR type zeolite from 0.01 to 0.20 wt.% of at least one metal selected from the group consisting of Li, Na, K, Mg or Ca, a maximum of 0.01% Na, and from 0 to 0.5 wt.% at least one metal selected from the group consisting of Ti, Zr, Hf.

In the present invention, zeolites of the FAU or EMT-FAU type belong to the group of zeolites with isotypic structures corresponding to a structure of the FAU type, such as zeolite Y, zeolite Na-X, siliceous zeolite Na-Y, zeolite Linde X, zeolite Linde Y, zeolite ZSM- 3 and zeolite ZSM-20, preferably zeolite Linde Y or zeolite Y.

In the present invention, MOR type zeolites belong to the group of zeolites with isotypic structures corresponding to the MOR structural type, such as mordenite, Na-D zeolite and Ca-Q zeolite, more preferably mordenite.

In a specific embodiment of the invention, the catalyst forming a maximum of 20 wt.% 2-phenyl isomer includes:

a) an isotypic zeolite of the FAU type, preferably zeolite Y;

b) from 0.01 to 0.15 wt.% of at least one metal selected from the group consisting of Li, Na, K, Mg or Ca, preferably about 0.08 wt.% Na;

c) from 0.1 to 8 wt.% at least one rare earth metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm or Eu, preferably from 3 to 4 wt.% La, from 0 5 to 1.5 wt.% Ce, 0.1 to 1 wt.% Pr and 1 to 2 wt.% Nd.

In a specific embodiment of the invention, the catalyst forming a maximum of 20 wt.% 2-phenyl isomer in its structure and texture is characterized by:

a) powder x-ray diffraction, characterized in that the most intense peak appears at an angle of 2θ corresponding to 6.2 °, and the remaining main peaks appear at diffraction angles of 2θ corresponding to 23.6 °; 27 °; 31.3 °; 15.6 °; 20.3 °; 18.6 ° and 30 ° indicated in decreasing order of intensity of the corresponding peaks;

b) a total silicon / aluminum molar ratio of from 1: 1 to 3: 1, preferably 1.6: 1.0;

C) the total specific surface area (BET from 400 to 700 m ² / g, preferably 650 m ² / g;

g) a total specific surface area of micropores from 350 to 600 m ² / g, preferably 525 m ² / g;

d) a specific micropore volume of from 0.1 to 0.3 ml / g, preferably 0.21 ml / g;

e) the distribution of macropores, in which the diameter of the macropores is in the range from 20 to 2000 angstroms, preferably from 20 to 80 angstroms.

In a specific embodiment of the invention, the catalyst forming at least 20 wt.% Of the 2-phenyl isomer includes:

a) zeolite with an isotypic structure of the MOR type,

b) from 0.01 to 0.2 wt.% at least one metal selected from the group consisting of Li, Na, K, Mg or Ca, preferably about 0.07 wt.% Mg,

c) a maximum of 0.01% Na,

g) from 0 to 0.5 wt.% at least one metal selected from the group consisting of Ti, Zr, Hf, preferably 0.25 wt.% Ti.

In a particular embodiment of the invention, a catalyst forming at least 20 wt.% Of the 2-phenyl isomer is characterized by its structure and texture:

a) powder x-ray diffraction, characterized in that the most intense peak appears at an angle of 2θ corresponding to 25.6 °, and the remaining main peaks appear at diffraction angles of 2θ corresponding to 22.3 °; 26.3 °; 19.6 °; 13.5 ° and 27.7 ° indicated in decreasing order of intensity of the corresponding peaks;

b) a total silicon / aluminum molar ratio of from 1.5: 1.0 to 3.5: 1.0, preferably 2.8: 1.0;

c) a total specific surface area (according to BET) of from 150 to 600 m ² / g, preferably 490 m ² / g;

g) a total specific surface area of micropores from 300 to 450 m ² / g, preferably 380 m ² / g;

d) a specific micropore volume of from 0.01 to 0.2 ml / g, preferably 0.15 ml / g;

e) the distribution of macropores, in which the diameter of the macropores is in the range from 20 to 800 angstroms, preferably from 20 to 300 angstroms.

In a specific embodiment of the present invention, the paraffins of step (1) include straight chain alkanes containing from 8 to 30 carbon atoms, preferably from 10 to 16 carbon atoms, more preferably from 10 to 14 carbon atoms. These paraffins can be dehydronized and refined by any method described in the prior art.

In a specific embodiment of the present invention, the aromatic hydrocarbon is an aromatic hydrocarbon selected from the group: toluene, xylene, benzene, or mixtures thereof, preferably it is benzene.

In a particular embodiment of the present invention, the aromatic compound and the olefin are mixed before the alkylation reaction of step (5) in a benzene: olefin molar ratio of 5: 1 to 70: 1, preferably 10: 1 to 30: 1, more preferably 10: 1 up to 15: 1. In a specific embodiment, the mixture further comprises from 0 to 0.3 wt.% Non-linear compounds. In a specific embodiment, the mixture further comprises from 0 to 0.1 wt.% Water.

In a specific embodiment of the present invention, the alkylation reaction of step (5) is carried out in a reactor with a catalyst selected from the group consisting of a fixed catalyst bed with one catalyst, at least one fixed catalyst bed with two completely mixed different solid catalysts, at least two separate stationary catalytic layers, each of which contains the same catalyst, at least two separate fixed catalytic layers, each each of which contains various catalysts; and a fluidized bed reactor with one or more different catalysts.

In a specific embodiment, the alkylation reactions are carried out simultaneously in a reactor configuration comprising at least one configuration selected from the group: an independent reactor, at least two reactors connected in parallel, at least two reactors connected in series, and combinations thereof.

In a specific embodiment, the purification in step (3) is carried out by purification technologies known to those skilled in the art, such as, for example, hydrogenation, fractionation and selective adsorption. In the case of selective adsorption, the adsorbent layer is formed from at least one material selected from the group consisting of zeolites, silica, silica gel, macroporous magnesium silicate, activated alumina, aluminosilicates, clays, molecular sieves, cellulose acetate, activated macroporous polystyrene gel coal and organoselective polymer membranes.

In a specific embodiment, the purification in step (4) is carried out by purification technologies known to those skilled in the art, such as, for example, hydrogenation, fractionation and selective adsorption. In the case of selective adsorption, the adsorbent layer is formed from at least one material selected from the group consisting of zeolites, silica, silica gel, macroporous magnesium silicate, activated alumina, aluminosilicates, clays, molecular sieves, cellulose acetate, activated macroporous polystyrene gel coal and organoselective polymer membranes.

In a specific embodiment, the purification in step (6) is carried out by purification technologies known to those skilled in the art, such as, for example, hydrogenation, fractionation and selective adsorption. In a preferred embodiment, the purification in the step is carried out by selective adsorption using a selective clay type adsorbent characterized by:

a) a total molar ratio of silicon dioxide: alumina from 3: 1 to 6: 1, preferably from 3.5: 1.0 to 5.5: 1.0, more preferably 4.2: 1;

b) a content of from 1 to 4 wt.% Fe, preferably 2.1 wt.%;

c) from 0.5 to 2 wt.% K, preferably 1.2 wt.%;

g) from 0.2 to 2 wt.% Mg, preferably 0.7 wt.%;

d) from 0.1 to 1.0 wt.% TiO ₂ , preferably 0.3 wt.%;

e) a total specific surface area, expressed as a BET surface, of from 150 to 500 m ² / g, preferably from 200 to 400 m ² / g, more preferably 260 m ² / g;

g) an aggregate pore volume of from 0.1 to 2.0 ml / g, preferably 0.4 ml / g;

h) the distribution of macropores, in which the diameter of the macropores is in the range from 20 to 800 angstroms, preferably from 20 to 200 angstroms, more preferably from 20 to 100 angstroms, with an average diameter in terms of pore volume centered at 34 Angstroms.

In a specific embodiment, the hydrotropic precursor of step (4) is added to the alkyl aromatic stream before purification in step (7), purification, sulfonation and / or neutralization, thereby conducting a joint purification and sulfonation.

In a specific embodiment, the hydrotropic precursor of step (4) is purified, sulfonated and / or neutralized and subsequently added to the alkyl aromatic sulfonate obtained in step (8).

In a specific embodiment, the neutralization in step (9) is carried out by means of an alkaline substance comprising one or more cations selected from the group: Na, K, NH ⁴⁺ , Mg, Ca, Ba, or by substituted ammonium alkalis.

In a specific embodiment, the reaction temperature is from 20 to 400 ° C.

In a specific embodiment, the space velocity is from 1 hour ^-1 to 15 hour ^-1 .

Another aspect of the present invention relates to a method for producing a highly soluble linear alkylbenzenesulfonate with a content of 2-phenyl isomer of at least 18 wt.%, By catalytic alkylation of an aromatic compound with an alkylating agent, as described previously, in which stages (1), (2), (3) and (4) are optional.

In a more specific embodiment, the olefins are alpha olefins and comprise from 18 to 28 carbon atoms, preferably from 20 to 24 carbon atoms, and may further include a maximum of 10 wt.%, Branched olefins.

In a more specific embodiment of the present invention, the aromatic compound and alpha olefins are mixed prior to the alkylation reaction of step (5) in a molar ratio of aromatic compound: olefin of 5: 1 to 70: 1.

In a more specific embodiment, the mixture further comprises from 0 to 0.01 wt.% Water.

Another aspect of the present invention relates to suitable cleaning compositions for dishwashing detergents, cleaners for hard coatings, liquid detergents, powder detergents, cleaning products in the form of pastes, gels, washing bars, including:

a) from 1 to 99 wt.% soluble linear alkylbenzenesulfonate obtained by the method according to any of the above;

b) from 99 to 1 wt.% of other detergent ingredients selected from the group consisting of derivatives of fatty alcohols, concomitant surfactants, structuring agents, solvents, additives and mixtures thereof, such as derivatives of fatty alcohols, fatty acids, alkyl sulfates , ethanolamine, amine oxide, alkaline carbonates, ethanol, isopropanol, water, pine oil, sodium chloride, sodium silicate, polymers, alcohol alkoxylates, perborates, zeolites, alkaline sulfates, enzymes, hydrotropes, coloring materials, fragrances, preservatives, brighteners, incorporating substances, polyacrylates, essential oils, alkalis, ether sulfonates, water-soluble branched alkyl benzene sulfonates, alkyl phenol alkoxylates, fatty acid amines, alpha olefin sulfonates, paraffins sulfonates, polyethylene sulfonates, telomeloylate , low-foaming alcohol surfactants based on ethylene oxide / propylene oxide, methyl ether sulfonates, alkyl polysaccharides, n-methi glucamides, sulfonated alkildifeniloksid and polyethylene glycol.

BRIEF DESCRIPTION OF THE DRAWINGS

Figure 1 shows the reaction scheme of the present invention in the form of a technological scheme.

Figure 2 shows the reaction scheme of the present invention in the form of a flow chart in which the steps of catalytic dehydrogenation of paraffin, hydrogenation of a diolefin, purification of an alkylating agent and purification and addition of a hydrotropic precursor are omitted.

Figure 3 simultaneously shows two chromatograms of the obtained products obtained by gas chromatography with a flame ionization detector (GC-DIP), after separation of unreacted benzene and paraffins, when the benzene is alkylated with a purified alkylating agent using two different catalysts separately: the catalyst used in the usual manner in a similar alkylation method (catalyst B), and one of the catalysts the use of which is claimed in this patent (catalyst A). The chromatogram specifically refers to the retention time of the heavy alkylate.

Figure 4 simultaneously shows two chromatograms of the obtained products obtained by GC-DIP after separation of unreacted benzene and paraffins, when the benzene is alkylated with a purified alkylating agent using one of the catalysts claimed in this patent.

Figure 1 shows a non-limiting implementation diagram of this invention.

Stream 15 is a paraffin feed to a dehydrogenation unit and includes a fresh paraffin mixture, stream 10, together with unreformed paraffins separated in a raw alkylbenzene purification unit, block 350, and recycled in a stream 170. In the dehydrogenation block 300, the feed is partially converted paraffin feedstock into a mixture of monoolefins, paraffins and various by-products such as diolefins and non-linear compounds. An olefin purification unit, block 310, is supplied with an effluent from the dehydrogenation unit through stream 20, increasing the net yield of monoolefins by converting certain by-products formed in the dehydrogenation unit, mainly diolefins, to monoolefins. The resulting stream, stream 30, is processed in block 320 containing a selective adsorbent to eliminate non-linear compounds from the dehydrogenation process. Fresh benzene is pumped into the process through stream 50 and mixed with reused benzene that has not reacted (stream 160) coming from the raw alkylbenzene purification unit, block 350. A mixture of these two streams forms a feed benzene stream (stream 55), which is mixed with the effluent a stream (stream 40) from a selective adsorption unit 320 to form a stream 60 consisting of monoolefins, benzene and paraffins and supplied to the alkylation unit.

Stream 60 is divided into two identical streams, 60a and 60b, which are fed into two different alkylation reactors, blocks 330 and 340, respectively; the alkylation reactor 330 uses a catalyst forming a linear linear alkylbenzene feed (stream 70) with a maximum content of 2-phenyl isomer of at least 20 wt.%, while the linear alkylbenzene forming a catalyst forming a raw linear alkylbenzene 340 (stream 80) with the content of the 2-phenyl isomer of at least 20 wt.%. Streams 70 and 80 are mixed in various proportions to form a stream, stream 90 containing linear alkyl benzene with a variable content of the 2-phenyl isomer, unreacted benzene, paraffins and by-products. Stream 90 is fed to a feed alkyl benzene purification unit, block 350, in which unreacted benzene, paraffins and by-products heavier than linear alkyl benzene are distilled to produce a relatively pure linear alkyl benzene (stream 100). After this, stream 100 is fed to the final stage of alkylbenzene purification, to block 360, which contains a selective adsorbent for eliminating aromatic compounds that are still present in small amounts in relatively pure alkylbenzene due to the fact that the boiling point range overlaps with the boiling point of interest alkylbenzene.

Non-linear compounds recovered in block 320 are pumped into special treatment block 380 via stream 180. This block 380 includes stages such as fractionation, hydrogenation and / or selective adsorption to convert non-linear impurities in a hydrotropic precursor (stream 190). Depending on the operating conditions of the method of the invention, stream 190 can be conducted through streams 190a and 190b, or it cannot be used if the content of the 2-phenyl linear alkylbenzene isomer is less than 60 wt.%. The relatively pure linear alkylbenzene stream, stream 100, and hydrotropic precursor stream 190a can thus be mixed to form stream 110; they are cleaned together in block 360 and then sent in streams 120 and 130 to block 370 where they are sulphonated / neutralized together to give a final stream, stream 150. Streams 190a can also be omitted, so that the relatively pure linear alkyl benzene coming from block 350, stream 100-110, separately cleaned in block 360, and after cleaning it (stream 120), then mix it with the hydrotropic precursor supplied by streams 190b and 191a, forming stream 130, thereby sulfonating and neutralizing together in block 370, thereby forming final stream, stream 150. Streams 19 0a and 191a can also be omitted, so that only one relatively pure alkylbenzene stream 100 is purified (block 360), sulfonated and neutralized (block 370), separately producing a stream of alkylbenzenesulfonate. This stream 140 is then mixed with a hydrotrope stream 192, which is separately sulfonated and neutralized in block 390 through streams 190, 190b and 191b, thereby forming a final stream 150. Stream 150 includes a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer and low color after sulfonation. The addition of hydrotropic substances (in any of these options) is performed when the content of the 2-phenyl isomer exceeds 60 wt.%.

Figure 2 shows another non-limiting implementation diagram of this invention when steps 1), 2), 3) and 4) are optional.

Stream 10 is the supply of fresh alpha olefin to the process. Stream 20 is a feed of a fresh aromatic compound, such as benzene, to the process. Stream 20 is mixed with stream 60, which is a recycled excess of the aromatic compound, after it is separated from the alkylation process in a distillation column, block 120. Stream 30, which is the aromatic compound supply, is formed by mixing streams 20 and 60. This stream 30 is mixed with a stream 10 in the mixing unit 100 in order to obtain a mixture of aromatic compounds and olefins with the desired aromatic / olefin molar ratio, stream 40. This stream is fed to an alkylation reactor, Lok 110, wherein the catalyst is placed into a fixed bed reactor, so that the alkylation of aromatic compounds with olefins is carried out. The effluent from the alkylation reactor, stream 50, consists of an unreacted aromatic compound and an alkyl aromatic compound obtained during the alkylation. Stream 50 is separated in a distillation column, block 120, with the goal of separating the unreacted aromatic compound in its upper part, stream 60, and the alkyl aromatic compound in its lower part, stream 70. Stream 60 is returned back to the method, as mentioned earlier, at that time as stream 70 is sulfonated in a film-type reactor (falling-film reactor) with gaseous SO ₃ , block 130. The sulfonated product, stream 80, consists of a highly pure linear alkyl aromatic sulfonic acid with a specific content of the 2-phenyl isomer. This product can then be neutralized in block 140 with basic salts of calcium, barium, sodium, magnesium and ammonia in the presence of a highly ionizable compound, such as phenol, in order to obtain a highly pure alkyl aromatic sulfonate, both neutral and preferably ultra-alkaline, depending on the amount of base, used in neutralization.

The invention is described further, for purposes of illustration only, by the following examples, which should not be construed as limiting the scope of the present invention.

Examples

Example 1

This example illustrates the advantage of using zeolite Y doped with 7 wt.% Rare earth metals such as La, Ce, Pr and Nd (called catalyst A) in the alkylation of benzene with an olefin / paraffin mixture over industrial amorphous fluorinated silica-alumina (called catalyst B), widely used in this reaction on an industrial scale. Both catalysts were crushed and sieved to obtain an equivalent particle size distribution. Benzene was dried using a molecular sieve to minimize the addition of water, and it was then mixed with a mixture of monoolefins and paraffins, which came from the dehydrogenation of paraffins and the selective hydrogenation of diolefins. Tests in a pilot alkylation unit were performed in a fixed-bed isothermal reactor with 24-hour reaction cycles, followed by catalyst regeneration cycles by washing with benzene for the same period of time. The standard cycle includes a 24-hour reaction cycle at 140 ° C, LHSV (fluid hourly space velocity) = 11 hour ^-1 and a benzene: olefin molar ratio of 30: 1, followed by a benzene washing cycle for the same period of time. Table 1 shows the mass of the catalyst, washing conditions, etc.

TABLE 1 Catalyst BUT AT Particle diameter, mm 0.50-1.25 0.50-1.25 The volume of catalyst, cm ³ 122 122 Reaction temperature, ° C 100-150 115-170 Regeneration temperature, ° C 260 260 Reaction pressure MPa (kgf / cm ² ) 1.96 (20) 1.96 (20) Regeneration pressure MPa (kgf / cm ² ) 3.92 (40) 3.92 (40) LOS reaction (hour ^-1 ) 4-11 2-4-11 COSG regeneration (hour ^-1 ) one one The benzene / olefin molar ratio 10-30 10-30

The composition of the feedstock related to the mixture of olefins and paraffins is summarized in Table 2.

TABLE 2 Compound Percentage (wt.% In the mixture) n-c10 14.8 n-c11 31,0 n-C12 26.1 n-C13 18.2 n-C14 <0.9 C10 olefin 1.3 C11 olefin 3.2 C12 olefin 3,1 C13 olefin 2,3 C14 olefin <0.1 Aromatic compounds <0.1

This mixture of paraffins and olefins was mixed with dry benzene until the desired benzene: olefin molar ratio was achieved. The evaluation of the catalyst was carried out in five different sequences of reaction cycles. After carrying out each reaction cycle, the resulting alkylation product was dispersed in three stages using three distillation columns (the first worked at atmospheric pressure, while the other two worked under vacuum). The first column was operated at atmospheric pressure and unreacted benzene was separated in its upper part, while the compounds present in its lower part were fed into the second column. In the second column, paraffins were separated in its upper part, while the compounds present in its lower part were fed into the third column. In the third column, alkylbenzene was separated in its upper part, and heavy alkylate in its lower part. Assays (performed by GC-DIP) relate to compounds fed to the third column. In the first sequence of reaction cycles, both catalysts were independently tested using the same operating conditions. For each catalyst, the sequence consisted of seven cycles that were performed at a LHSV of 11 h ^-1 , at a temperature of 130 and 140 ° C, followed by three cycles at 155 ° C and a LHSV of 4 h ^-1 . Next, a standard cycle was performed at 140 ° C and a LHSV of 11 h ^-1 in order to check the deactivation of the catalyst. In all these cycles, the molar ratio of benzene to olefin was maintained at a value of 30. All these conditions and results are presented in Table 3.

In the second sequence of reaction cycles, catalyst A was tested in order to analyze its activity at lower temperatures. This sequence included three reaction cycles that were carried out at a LHSV of 4 h ⁻¹ , but now at 100 ° C, followed by a standard cycle (LHSV = 11 h ⁻¹ ; T = 140 ° C). In all these cycles, the molar ratio of benzene to olefin was maintained at a value of 30. All conditions and results are presented in Table 4.

In the third sequence of reaction cycles, both catalysts were tested independently in order to analyze their deactivation rate. In order to have a stronger effect on the stability of the catalyst after a standard cycle (LSS = 11 h ^-1 ; T = 140 ° C), the normal reaction period of 24 hours was extended to 60 hours without a standard benzene wash. In all these cycles, the molar ratio of benzene to olefin was maintained at a value of 30. The catalytic activity was analyzed in terms of the degree of conversion. All results and conditions are presented in Table 5.

TABLE 5 Reaction hours Temperature ° C HOUSING, hour ^-1 Catalyst A Conversion Catalyst B Conversion 24 140 eleven 100.0 93.9 thirty 140 eleven 100.0 93.1 36 140 eleven 100.0 92.2 42 140 eleven 99.9 91.1 48 140 eleven 99.9 89.7 54 140 eleven 99.5 88.5 60 140 eleven 98.9 85.6

The fourth sequence of reaction cycles in which Catalyst B was tested included six reaction cycles that were performed at a LHSV of 2 h ⁻¹ (in order to achieve 100% conversion), at various temperatures, followed by a standard cycle (LHSV = 11 h ⁻¹ ; T = 140 ° C). In all these tests, the molar ratio of benzene to olefin was maintained at a value of 30. All these conditions and results are presented in Table 6.

The fifth sequence of reaction cycles, in which only catalyst A was tested, included six reaction cycles; they were carried out with different LHSVs, temperatures, and the molar ratio of benzene to olefin in order to analyze the effect of the latter variable on conversion and reaction selectivity. All results and conditions are presented in Table 7.

As can be seen in Table 3, the activity of catalyst A is much higher than the activity of catalyst B, since catalyst A reaches 100% conversion in almost all cycles. Even when the temperature is 100 ° C (LHSV = 4 hr ^-1 , Table 4), approximately 100% conversion is achieved with catalyst A, while 100% conversion is not achieved with catalyst B to very low spatial velocities and temperatures above 130 ° C (Table 6). In order to expose the activity of the catalyst to a load, the normal reaction period of 24 hours was extended to 60 hours in the third sequence (Table 5) and, in the case of catalyst A, even after the 50th hour of the reaction, the observed conversion was higher than 99%, while Catalyst B deactivation was observed after 24 hours. This implies that catalyst A is much more resistant to deactivation than catalyst B, so this catalyst allows longer reaction cycles, reducing the number of benzene rinses during the life of the catalyst and, in conclusion, reducing operating costs.

Another important advantage of catalyst A is associated with the production of heavy alkylate. As can be seen in Table 3, catalyst A produces significantly less heavy by-products than catalyst B (at least 80% less), reaching less than 1% heavy alkylate in all of these tests, when the molar ratio of benzene to olefin is 30 :one.

Figure 3 shows the results of GC-DIP of the products obtained in tests with a molar ratio of benzene to olefin equal to 30 (after separation of benzene and paraffin) related to products obtained with catalyst A and catalyst B. In particular, they correspond to retention times heavy alkylate.

As can be seen in FIG. 3, catalyst A forms much less intense peaks in the chromatographic region corresponding to alkylbenzene type compounds (heavy alkylates) than amorphous catalyst B. These compounds have 26 to 32 carbon atoms and they are formed by the reaction of monoalkylbenzene with an olefin forming a dialkylbenzene compound (such as didecylbenzene, didodecylbenzene, decyldodecylbenzene, etc.). The advantage of using catalyst A is that its internal microporous structure includes size and shape restrictions that minimize the formation of these by-products, since their size is larger than the pore diameter of the catalyst.

In order to analyze the effect of the molar ratio of benzene to olefin on the distribution of the product, experiments were performed, the results of which are presented in Table 7. As can be seen from Table 7, when this ratio decreases, the amount of heavy by-products increases, however, even with the tested minimum molar ratio in this sequence (the benzene to olefin molar ratio of 10, Table 7), when Table 7 is compared with Table .3, the amount of heavy by-products formed by catalyst A (about 3%) is less than or equal to the amount obtained by catalyst B at a higher molar ratio (molar ratio of benzene to olefin equal to 30). Thus, catalyst A allows operation at a lower molar ratio of benzene to olefin than catalyst B, which implies lower costs in the subsequent separation step of unreacted benzene.

Finally, as can be seen in Table 3, catalyst A produces a relatively large amount of branched alkylate compared to catalyst B. However, catalyst A is more active than catalyst B, so the reaction system does not need to be operated at temperatures as high as 130- 140 ° C (as can be seen in all results, as the temperature rises, the content of branched hydrocarbons increases) to achieve a 100% degree of conversion. This means that when the reaction system is operated at an industrially reasonable space velocity (LSS = 4 h ^-1 ) and the temperature is maintained at 100 ° C (Table 4), a 100% degree of conversion is achieved and the content of branched hydrocarbons in the alkylate is reduced to 4 wt. % of acceptable value and similar to that achieved when catalyst B is operating at 100% conversion (Table 6).

Example 2

This example shows the advantages of purifying an olefin / paraffin mixture from the dehydrogenation and selective hydrogenation steps before they react with benzene in the alkylation step. This reaction was catalyzed by zeolite Y, doped with 7 wt.% Rare earth metals such as La, Ce, Pr and Nd (referred to as catalyst A). In this example, catalyst A was placed on a fixed bed in order to accelerate the alkylation of benzene with purified and crude olefin / paraffin mixtures.

The purification step is carried out using an adsorbent layer in which a certain amount of some molecular sieve is placed. The selected molecular sieve is 13X zeolite, widely used in methods for the selective removal of aromatic components from a mixture of olefins and paraffins. A mixture of olefins and paraffins is passed through the bed to achieve selective adsorption of non-linear compounds coming from the previous dehydrogenation step (or present in a fresh supply of paraffin and / or reusable paraffin). After saturation, the layer is washed with short chain paraffins to desorb olefins and paraffins that may remain in the pores, and then transported together with benzene to recover adsorbed aromatic compounds that can be used as hydrotropic precursors. The operating conditions for the cleaning stage for the pilot plant are presented in Table 8.

TABLE 8 Size (mesh, US standard) from 10 to 20 Adsorption temperature, ° C 140 Flushing temperature, ° C 130 Desorption temperature, ° C 140 Adsorption pressure, kgf / cm ² (MPa) 25 (2.45) Flushing pressure, kgf / cm ² (MPa) 25 (2.45) Desorption pressure, kgf / cm ² (MPa) 25 (2.45) Flushing agent n-pentane Desorbing agent benzene CSJ (hour ^-1 ) 2

A mixture of olefins and paraffins from the dehydrogenation and hydrogenation steps contained approximately 2% by weight of aromatics. Its composition after the purification step is presented in Table 9.

TABLE 9 Compound Percentage (wt.% In the mixture) n-c10 14.8 n-c11 31,0 n-C12 26.1 n-C13 18.2 n-C14 <0.9 C10 olefin 1.3 C11 olefin 3.2 C12 olefin 3,1 C13 olefin 2,3 C14 olefin <0.1 Aromatic compounds <0.1

After purification, a mixture of olefins and paraffins was mixed with dry benzene to obtain the selected molar ratio. This mixture was then used as feed for the alkylation step. The operating conditions for the alkylation step are presented in Table 10. Other parameters associated with the fixed bed are the same as the parameters presented in Example 1 (catalyst A), since alkylation with purified and crude mixtures is performed in the same reactor and under the same conditions defined in this Example. The distillation process was carried out to separate benzene, paraffins, alkylbenzenes and heavy alkylate, as defined in Example 1. Gas chromatographic analyzes relate to the stream fed to the third column. Light products were analyzed by GC-DIP on the top stream of the first column.

TABLE 10 Temperature ° C 140 Pressure, MPa (kg / cm ² ) 1.96 (20) HOUSING, hour ^-1 eleven The benzene / olefin molar ratio thirty

Another test was performed to analyze the effect of the purification stage on the distribution of products, while maintaining all operating parameters at the same values as before, but using an uncleaned mixture. The distribution of products related to alkylation with purified and non-purified mixtures is presented in Table 11.

TABLE 11 Product distribution Refined mixture Crude mixture Alkylbenzene, wt.% 98.6 94.8 Heavy alkylate, wt.% 0.5 3,7 Light products, wt.% 0.9 1,6

As can be seen in Table 11, the amount of heavy alkylate formed when using purified mixtures is reduced by 86 wt.% Compared with untreated mixtures. Figure 4 shows chromatograms corresponding to the GC-DIP of the obtained products, after separation of benzene and paraffins, when using purified and crude mixtures.

The top line corresponds to the use of the crude mixture, while the bottom line corresponds to the use of the purified mixture. When comparing both chromatograms, it becomes clear that the intensity lines of the peaks corresponding to the heavy alkylate obtained using purified mixtures are much lower than when using crude mixtures. The effect of selective adsorption mainly affects the final content of the "lightest" heavy alkylates located at retention times of less than 62 minutes, as shown in Figure 4. These products are mainly compounds of 20-22 carbon atoms, such as alkylfluorenes, alkylanthracenes, alkylphenanthrenes, indanes, indenes, etc. They mainly form by alkylation of polyaromatic compounds formed in the dehydrogenation step (such as anthracene, phenanthrene, fluorenes, etc.) with C ₁₀ -C ₁₄ olefins. Purification of olefins and paraffins with an adsorbing layer includes the elimination of these products, which are directly formed in the dehydrogenation stage or are contained in fresh or reused raw materials, as well as the elimination of those polyaromatic compounds that can interact with C ₁₀ -C ₁₄ olefins in the alkylation stage.

As can be seen in Table 11, the use of purified mixtures also includes reducing the final amount of light by-products. The amount of light by-products formed is reduced by 44 wt.% When using purified mixtures.

Example 3

This example shows the stability of zeolite Y doped with rare earth metals when it is used as a catalyst in the alkylation of benzene with olefins. A long sequence of cycles in which zeolite Y doped with rare earth metals was used was performed to analyze the rate of their deactivation. Thirty standard cycles were performed, as previously determined in Example 1, with a LHSV = 8 h ^-1 and T = 140 ° C. After each 24-hour reaction cycle, a washing cycle was performed for 24 hours. The results are presented in Table 12 and they are averaged over the considered cycles.

TABLE 12 Cycles Average conversion 1st to 10th 99.6 from 11th to 20th 99.6 from 21st to 30th 99.6

As can be seen in Table 12, during this sequence of reaction / regeneration cycles, the average degree of conversion is always higher than 99.5% and no deactivation was recorded in the third ten cycles with respect to the initial cycles. This means that zeolite Y, doped with rare earth metals, is a very stable catalyst that maintains a high degree of conversion over time and does not show any signs of deactivation.

Example 4

This example shows the benefits of using two parallel fixed-bed isothermal reactors, one loaded with previously used zeolite Y, doped with 7 wt.% Rare earth metals such as La, Ce, Pr and Nd (called catalyst A) and the other loaded with industrial crystalline mordenite , called catalyst C, by controlling the distribution of the pre-purified feedstock between the two reactors and mixing the resulting effluents to obtain a controlled content 2-phenyl isomer in the resulting effluent.

A certain amount of catalyst A was placed in one of the fixed-bed reactors (called layer A), while the other fixed-bed reactor (called layer C) was loaded with a certain amount of industrial crystalline mordenite (catalyst C). The composition of the feed was the same for both reactors. A feed stream was obtained by mixing a purified mixture of olefins and paraffins (the composition of the mixture is defined in Example 2) with a suitable amount of dry benzene to obtain the desired molar ratio of benzene to olefin. The specified initial flow was always maintained at a constant flow rate. After this, the stream was divided into two substreams by means of a three-way valve, each stream was fed into the reactor (after the pre-heating stage) in order to dose an alternating stream to each reactor by regulating the valve (however, keeping the total flow rate constant). The effluents from each reactor were mixed, thereby obtaining a final effluent, which was analyzed (after separation of benzene and paraffins by distillation, as shown in Example 1) using GC-DIP. In this Example, both the composition of the feed and the reaction pressure were kept constant for both reactors, while the reaction temperature was different in each reactor and the flow rate of the feed in each reactor was varied to modify the final content of the 2-phenyl isomer. Operating conditions are presented in Table 13.

TABLE 13 Catalytic layer BUT FROM Particle diameter mm 0.50-1.25 0.50-1.25 The volume of catalyst, cm ³ 122 122 Reaction temperature, ° C one hundred 140 Reaction pressure, MPa (kg / cm ² ) 1.96 (20) 1.96 (20) COSG reaction, hour ^-1 2.7-11.0 2.7-11.0 The benzene / olefin molar ratio thirty thirty

It is necessary to take into account that the hourly volumetric flow rate of a fluid (CFSV), related to each reactor, changes when the percentage of the feed feed dosed to each reactor is changed from 2.7 h ^-1 (when 25% of the feed feed passes through such a reactor) up to 10.8 h ⁻¹ (when 100% of the feed feed passes through one reactor). The distribution of the product in the final effluent when the flow rate of the feed is changed is presented in Table 14.

TABLE 14 % of feedstock metered into each reactor (layer A / layer B) Total Conversion Rate The content of 2-phenyl isomer, wt.% Heavy alkylate, wt.% Branched alkylate, wt.% 100/0 99.9 eighteen 0.9 3.8 75/25 99,4 thirty 1,1 4.4 50/50 99.1 43 1.3 5.1 25/75 98.7 55 1.4 5.7 0/100 98.3 70 1,6 6.3

As can be seen in Table 14, a change in the flow supplied to each reactor implies a change in the final content of the 2-phenyl isomer from 18 wt.% (Obtained when all of the feed is passed through catalyst bed A) to 70 wt.% (Obtained when all of the feed is passed through a layer of mordenite). In all cases, the amount of heavy alkylate recorded in the final effluent was less than or equal to 1.6% of the mass. and the amount of branched alkylate has always been less than 6.5% of the mass. Both catalysts show obvious stability with respect to changes in LHSV (in terms of conversion and selectivity) in the range of LHSV that has been tested.

Example 5

This example shows the advantages of purification of raw alkylbenzene before the sulfonation step in order to minimize the color after sulfonation of the final sulfonic acid.

A purified mixture of olefins and paraffins mixed with dry benzene was used as raw material as described in Examples 2 and 4. A molar ratio of benzene to olefin of 20: 1 was chosen. Alkylation was carried out by means of two parallel fixed-bed isothermal reactors, as in Example 4. The catalysts and operating conditions were exactly the same as in Example 4. For each reactor, the dosage of the feedstock in the amount of 50% of the feed stream was selected. Raw alkylbenzene was obtained by fractionating the effluent from the alkylation step. However, the distillation was slightly different from the distillation used in the previous Examples. In this example, four distillation columns were used. The first column was operated at atmospheric pressure and unreacted benzene was separated in its upper part, while the compounds that were present at the bottom of the column were fed into the second column. In the second column, which operated under vacuum, paraffins were separated in its upper part, while the compounds that were present in the lower part of the column were fed into the third column. In the third column, which operated under vacuum, monoalkylbenzene was separated in its upper part, and heavy alkylate in its lower part. This raw monoalkylbenzene obtained in the upper part of the third column and containing a certain amount of heavy alkylate was fed into the adsorption layer. After cleaning, the effluent from the adsorption layer was supplied to the fourth distillation column. In this column, light by-products obtained during the purification step (mainly benzene obtained through transalkylation reactions at ppm levels) in its upper part were separated, while the compounds in its lower part were pure monoalkylbenzenes. These high purity monoalkylbenzenes were then sulfonated using dilute SO ₃ in dry air as a sulfonating agent in a multi-tube film reactor, and then they were allowed to mature and hydrolyzed to complete the reaction.

As mentioned before, the purification step was carried out by means of a fixed bed in which a certain amount of industrial acid clay was placed. In this example, the clay used was characterized by a mass ratio of silica to alumina of 4.9, it was partially neutralized by 1.4 wt.% K ₂ O and 1.2 wt.% MgO, and also contained 2.9 wt.% Fe ₂ O ₃ and 0.5 wt.% TiO ₂ . This clay was pre-activated by passing a stream of hot inert gas in order to eliminate adsorbed water. The activation and operation conditions are presented in Table 15.

TABLE 15 Adsorption temperature, ° C 110 COSG adsorption, hour ^-1 3 Activation temperature, ° C 120 COSG activation, hour ^-1 2 Activation time, hour 12 Activating gas N ₂

Average sulfonation conditions are presented in Table 16.

TABLE 16 The molar ratio of SO ₃ / LAB 1.10: 1 Reaction time 1,5 hour Reaction temperature 40-45 ° C Cleavage time 1 hour Cleavage temperature 40-45 ° C Hydrolysis time 0.5 hours Hydrolysis temperature 40-45 ° C

The final color after sulfonation was analyzed using a Clett-Summerson colorimeter. In order to eliminate the effect of the purification step on the final color after sulfonation, alkylbenzene was also sulfonated under the same conditions without a purification step. The color after sulfonation of the raw sulfonated alkylbenzene and purified alkylbenzene is presented in Table 17.

TABLE 17 Sulfonate Color after sulfonation (Clett-Summerson scale) Raw Sulphonated Alkylbenzene 23 Purified Sulfonated Alkylbenzene <5

As can be seen from Table 17, purification of raw alkylbenzene by means of a selective adsorbent layer implies a reduction of the final color after sulfonation by about 80%. When the color after sulfonation is reduced, the quality of the neutralized product increases, especially when it is used in liquid detergent compositions, since it can interfere with the visual effect of the dyes contained in the detergent composition.

Example 6

This example shows the advantages of adding a hydrotropic precursor obtained by processing non-linear compounds recovered in the purification step of the mixture after alkylation to alkylbenzene prior to the purification step of selective adsorption. Both streams were mixed, then purified with acid clay and distilled to separate light by-products and sulfonated as described in Example 4, and finally neutralized with aqueous sodium hydroxide in a stoichiometric amount.

Three samples of alkylbenzene were obtained with different contents of the 2-phenyl isomer in the alkylation step (as defined in Example 2) in order to evaluate the hydrotropic effect on the content of 2-phenyl isomer. Samples are designated S1, S2, S3, and the content of the 2-phenyl isomer in them is shown in Table 18.

TABLE 18 S1 S2 S3 2-phenyl alkanes, wt.% eighteen 68 70

The hydrotropic effect of the hydrotropic precursor was evaluated in terms of the cloud point at cooling (TPO) of the final product, diluted with water, to obtain the usual industrial concentrations. In order to evaluate the effect of the hydrotropic precursor, samples were prepared containing 90 wt.% Alkylbenzene and 10 wt.% Of this hydrotropic precursor, and then they were diluted in water. Another well-known hydrotrope, sodium xylene sulfonate, was added to samples without a hydrotropic precursor (90% pure sodium sulfonate alkylbenzene) with a variable content of 2-phenyl isomer and 10% sodium xylene sulfonate) and then diluted with water to the same concentrations as and in previous samples. The results are presented in Table 19.

TABLE 19 Active material in a cleansing composition, wt.% In water twenty% 25% thirty% Cloud Point (° C) 100% A 7 16 25 90% A + 10% KCH (sodium xylene sulfonate) 8 fourteen twenty 90% A + 10% hydrotropic predecessor one 7 fourteen 100% B fourteen 17 (*) 90% B + 10% KCH 17 twenty (*) 90% B + 10% hydrotropic predecessor 13 16 twenty 100% C 16 twenty 24 90% C + 10% KCH 12 fifteen 17 90% C + 10% hydrotropic predecessor 7 9 13 (*) cloudy at room temperature

As can be seen in Table 19, the hydrotrop considered in this patent reduces the SST of the final product in all samples, and in all cases its effect is much stronger than the hydrotropic effect of SPH, which is especially interesting when the content of the 2-phenyl isomer is higher.

Example 7

This example shows the behavior of zeolite Y doped with 7 wt.% Rare earth metals, such as La, Ce, Pr, Nd, in the alkylation of benzene with linear long-chain alpha olefins compared to the results obtained when using the HF catalyst, widely used on an industrial scale for a similar method.

Benzene was dried with a molecular sieve to minimize water addition and then mixed with a mixture of linear long chain alpha olefins. In the case of a solid catalyst, the pilot alkylation experiments were performed in a fixed-bed isothermal reactor with 24-hour reaction cycles, followed by washing cycles with benzene for the same period of time. Standard cycles include a 24-hour reaction cycle with a molar ratio of benzene to olefin equal to 50: 1, followed by a washing cycle with benzene for the same period of time. Operating conditions are presented in Table 20.

TABLE 20 Catalyst BUT Particle diameter mm 0.50-1.25 The volume of catalyst, cm ³ 122 Reaction temperature, ° C 140-150 Regeneration temperature, ° C 260 Reaction pressure, MPa (kg / cm ² ) 1.96 (20) Regeneration pressure, MPa (kg / cm ² ) 3.92 (40) COSG reaction, hour ^-1 4-8 COSG regeneration, hour ^-1 one Reaction time, hour 24 Regeneration time, hour 24 The benzene / olefin molar ratio fifty

The mixture of alpha olefins used as the raw material composition is presented below in Table 21.

TABLE 21 Compound wt.% <C ₂₀ olefin 0.1 C ₂₀ olefin 43.7 C ₂₂ -olefin 35.3 C ₂₄ olefin 19.1 > C ₄₀ olefin 0.7

Twelve cycles of the alkylation reaction were performed using zeolite Y. The first three cycles were performed at a LHSV of 8 h ⁻¹ and T = 150 ° C (cycle A). Then, three cycles were performed at a LHSV of 6 h ^-1 , and T = 150 ° C (cycle B). The last four cycles were performed at a LHSV of 4 h ^-1 , two of them at T = 150 ° C and the last two at a lower temperature, T = 140 ° C (cycle C). All these cycles were performed to analyze the effect of temperature and space velocity on the catalyst yield. Products were analyzed by gas chromatography (GC) and flame ionization detector (DIP).

Alkylation with HF was performed in a batch reactor with continuous stirring, taking into account that alkylation is an exothermic reaction and heat must be removed from the reactor in order to maintain a constant required reaction temperature, which is characteristic of the present prior art. A certain amount of the previously considered mixture of linear alpha olefins (the composition is shown in Table 20) was mixed with dry benzene until the selected molar ratio of benzene to olefin was introduced into the reactor. This mixture of benzene and olefins was preheated to the selected reaction temperature. Then, a certain volume of liquid HF was introduced into the reactor until the selected ratio of HF to olefin was reached. The reaction time was adjusted to 10 minutes in order to obtain a LHSV = 6 h ⁻¹ , which is typical of the prior art in the field of alkylation with HF. The operating conditions of the alkylation reaction using HF are presented in Table 22.

TABLE 22 Catalyst Hf The reaction temperature, ° C 60 Reaction time, min 10 Volume ratio HF / olefin one The benzene / olefin molar ratio 10

The results shown in Table 23 relate to the average product distribution for these cycles (called cycles A, B, and C) when using a solid catalyst with various LHSV conditions and temperatures. Results corresponding to HF technology are located at the bottom of Table 23 for comparing yields with HF and solid catalyst.

As can be seen in Table 23, the activity of zeolite Y doped with rare earth metals is always higher than 99.7% when considered in terms of the degree of conversion of olefin. This means that zeolite Y after ion exchange with rare earth metals is highly active. When the obtained by-products were analyzed, both catalysts (modified zeolite Y and HF) were highly selective for minimizing light by-products and heavy alkylate. The total amount of by-products obtained through zeolite Y is below 0.4 wt.% In the three cycles evaluated, and in cycles B and C even lower than when using HF, therefore, it clearly shows that zeolite Y doped with rare earth metals, It is highly selective in technology using a fixed bed reactor.

The distribution of isomers corresponding to previous experiments is presented in Table 24. As in Table 23, the line of results at the bottom corresponds to the results related to the reaction with HF under the operating conditions that were previously defined in Table 22.

In Table 24, the distribution of isomers is relatively similar when comparing products obtained using zeolite Y and products obtained using HF. The main difference is related to the content of branched alkylate. As you can see, the amount of branched alkylate obtained when using zeolite Y doped with rare earth metals is about 4 wt.% More than the amount obtained when using HF as a catalyst. This small difference is not important provided that the branched alkylate does not affect the properties of the detergent. With respect to the content of the 2-phenyl isomer, it can be seen that a slightly larger amount of the 2-phenyl isomer is obtained using the HF technology than in the case of the modified zeolite Y.

Although there is a slight difference between the distribution of the product associated with each technology, it was clearly shown that zeolite Y, doped with rare earth metals, is capable of catalyzing the alkylation of benzene with linear C _20-24 olefins with high activity in terms of the degree of olefin conversion and with high selectivity for monoalkylbenzenes.

Claims (24)

1. A method of obtaining a highly soluble alkylaromatic sulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% By catalytic alkylation of an aromatic compound with a purified alkylating agent, comprising the following stages:
1) catalytic dehydrogenation of linear paraffin feed;
2) the selective hydrogenation of diolefins, obtained as a by-product in stage (1), to monoolefins;
3) purification of the raw alkylating agent obtained in stage (2), separation of non-linear products contained in the effluent of stage (2);
4) processing non-linear products extracted in stage (3) to form a hydrotropic precursor;
5) alkylation of an aromatic hydrocarbon with monoolefins present in a purified alkylating agent by combining the following alkylation methods:
a) an alkylation method with a catalyst forming a linear linear alkyl aromatic compound with a maximum content of 2-phenyl isomer of 20 wt.%;
b) an alkylation method with a catalyst forming a linear linear alkyl aromatic compound with a minimum content of 2-phenyl isomer of 20 wt.%;
6) fractionation of the effluent of stage (5) in order to separate unreacted aromatic compounds, paraffins and the most severe by-products of linear alkyl aromatic compounds;
7) purification of the fraction of linear alkyl aromatic compounds from stage (6);
8) sulfonation of the purified linear alkyl aromatic compounds obtained in stage (7);
9) neutralization of the linear alkyl sulfonic acid obtained in stage (8),
characterized in that the catalyst forming a maximum of 20 wt.% 2-phenyl isomer includes a zeolite type FAU, from 0.01 to 0.15 wt.% at least one metal selected from the group consisting of Li, Na, K , Mg or Ca, and from 0.1 to 8 wt.% At least one rare earth metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm or Eu; and the catalyst forming at least 20 wt.% of the 2-phenyl isomer includes a MOR type zeolite from 0.01 to 0.2 wt.% of at least one metal selected from the group consisting of Li, Na, K, Mg or Ca, with a maximum Na content of 0.01%, and from 0 to 0.5 wt.% At least one metal selected from the group consisting of Ti, Zr, Hf. 2. A method of producing a highly soluble alkyl aromatic sulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the catalyst forming a maximum of 20 wt.% 2-phenyl isomer includes:
a) an isotopic zeolite of the FAU type;
b) from 0.01 to 0.15 wt.% at least one metal selected from the group consisting of Li, Na, K, Mg or Ca;
C) from 0.1 to 8 wt.% at least one rare earth metal selected from the group consisting of La, Ce, Pr, Nd, Pm, Sm or Eu. 3. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to any one of claims 1 and 2, in which the catalyst forming a maximum of 20 wt.% 2-phenyl isomer is characterized by:
a) powder x-ray diffraction, characterized in that the most intense peak appears at an angle of 2θ corresponding to 6.2 °, and the remaining main peaks appear at diffraction angles of 2θ, corresponding to 23.6; 27; 31.3; 15.6; 20.3; 18.6 and 30 ° indicated in decreasing order of intensity of the corresponding peaks;
b) a total silicon / aluminum molar ratio of from 1: 1 to 3: 1;
C) the total specific surface area (BET) from 400 to 700 m ² / g;
g) a specific surface area of micropores from 350 to 600 m ² / g;
d) specific micropore volume from 0.1 to 0.3 ml / g;
e) the distribution of macropores, in which the diameter of the macropores is in the range from 20 to 2000 Å. 4. A method of obtaining a highly soluble alkylaromatic sulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the catalyst forming a minimum of 20 wt.% 2-phenyl isomer includes:
a) an isotypic zeolite of the MOR type;
b) from 0.01 to 0.20 wt.% at least one metal selected from the group consisting of Li, Na, K, Mg or Ca;
c) a maximum of 0.01% Na;
g) from 0 to 0.5 wt.% at least one metal selected from the group consisting of Ti, Zr, Hf. 5. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the catalyst forming a minimum of 20 wt.% 2-phenyl isomer is characterized by:
a) powder x-ray diffraction, characterized in that the most intense peak appears at an angle of 2θ corresponding to 25.6 °, and the remaining main peaks appear at diffraction angles of 2θ corresponding to 22.3; 26.3; 19.6; 13.5 and 27.7 ° indicated in decreasing order of intensity of the corresponding peaks;
b) a total silicon / aluminum molar ratio of from 1.5: 1 to 3.5: 1;
C) the total specific surface area (BET) from 150 to 600 m ² / g;
g) a specific surface area of micropores from 300 to 450 m ² / g;
d) specific micropore volume from 0.1 to 0.2 ml / g;
e) the distribution of macropores, in which the diameter of the macropores is in the range from 20 to 800 Å. 6. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the paraffins used include from 8 to 30 carbon atoms. 7. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the aromatic hydrocarbon is selected from the group consisting of toluene, xylene, benzene or mixtures thereof. 8. The method of obtaining highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the aromatic hydrocarbon and purified alkylating agent are mixed before the alkylation reaction of stage (5) at a molar ratio of aromatic hydrocarbon: olefin from 5: 1 to 70: 1. 9. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 8, in which the mixture of aromatic hydrocarbon and purified alkylating agent contains a maximum of 0.3 wt.% Non-linear compounds other than aromatic hydrocarbon . 10. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 8, in which the mixture of aromatic hydrocarbon and purified alkylating agent contains from 0 to 0.1 wt.% Water. 11. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the alkylation reactions of stage (5) are carried out simultaneously. 12. The method of producing highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the catalyst used in the alkylation reaction is placed in the reactor in an arrangement selected from the group consisting of such arrangements as : fixed bed with one catalyst, fixed bed with two completely mixed different catalysts, at least two different fixed beds with the same catalyst in each of them, at least two different fixed layers with a different catalyst in each of them, a slurry reactor with one or more different catalysts. 13. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the alkylation is carried out in a reactor configuration comprising at least one of the reactor configurations selected from the group: independent reactor, at least two reactors connected in parallel; at least two reactors connected in series; and combinations thereof. 14. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the purification is carried out by selective adsorption and / or hydrogenation and / or fractionation. 15. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to 14, in which selective adsorption is carried out by means of a selective adsorbent such as clay. 16. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to clause 15, in which the clay is characterized by:
a) a total molar ratio of silicon dioxide-alumina from 3: 1 to 6: 1;
b) content from 1 to 4 wt.% Fe,
C) from 0.5 to 2.0 wt.% K, preferably about 1.2 wt.%,
g) from 0.2 to 2.0 wt.% Mg, preferably about 0.7 wt.%,
d) from 0.1 to 1.0 wt.% TiO ₂ , preferably about 0.3% by weight .;
f) specific surface area, expressed as BET specific surface area, from 150 to 500 m ² / g;
g) a total pore volume of from 0.1 to 2 ml / g;
h) the distribution of macropores, in which the diameter of the macropores is from 20 to 800 Å. 17. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the hydrotropic precursor obtained in stage (4) is added to the flow of alkylaromatic compounds when the content of 2-phenyl isomer in alkyl aromatic compounds more and equal to 60 wt.% adding it:
a) immediately before stage (6);
b) immediately after stage (6). 18. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the hydrotropic precursor obtained in stage (4) is sulfonated and neutralized separately, and subsequently added to the final alkylaromatic compound when the content of the 2-phenyl isomer in it is greater and equal to 60 wt.%. 19. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the neutralization in stage (9) is carried out by means of an alkaline compound comprising one or more cations selected from the group Na, K, NH ⁴⁺ , Mg, Ca, Ba or substituted ammonium alkalis. 20. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which stages (1), (2), (3) and (4) are optional. 21. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 20, in which the olefins of stage (5) are linear alpha-olefins. 22. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 20, in which the olefins of stage (5) contain from 9 to 30 carbon atoms. 23. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 1, in which the reaction temperature is from 20 to 400 ° C. 24. A method of obtaining a highly soluble linear alkylbenzenesulfonate with a controlled content of 2-phenyl isomer from 18 to 70 wt.% According to claim 20, in which the space velocity is from 1 to 15 h ^-1 .

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