HU201576B - Process for isolating aromatic hydrocarbons fromhydrocarbon mixtures - Google Patents

Abstract

The separation of aromatic and nonaromatic hydrocarbons containing hydrocarbon feed is provided by use of an extraction separation process using mixed extraction solvents. The term ''mixed extraction solvent'' as used herein shall mean a solvent mixture comprising a ''solvent'' component and a ''cosolvent'' component, as hereinafter defined. The ''solvents'' component employed in the instant process are the low molecular weight polyalkylene glycols of formula: HO-[CHR1 - (CR2R3)n -O]m -H wherein n is an integer from 1 to 5 and is preferably the integer 1 or 2; m is an integer having a value of 1 or greater, preferably between about 2 to about 20 and most preferably between about 3 and about 8; and wherein R1, R2 and R3 may be hydrogen, alkyl, aryl, aralkyl or alkylaryl and are preferably hydrogen and alkyl having between 1 and about 10 carbon atoms and most preferably are hydrogen. The ''cosolvent'' component employed herein is a glycol ether of the formula :R4O -[CHR5 -(CHR6-)-xO]y-R7 wherein R4, R5, R6 and R7 may be hydrogen alkyl, aryl, aralkyl, alkylaryl and mixtures thereof with the proviso that R4 or R7 are not both hydrogen.

Description

The present invention relates to an improved process for separating aromatic and non-aromatic hydrocarbons from starting materials of a mixture of hydrocarbons, in particular, separating aromatic and non-aromatic hydrocarbons in high yield from a mixture of aromatic naphthenic and paraffinic hydrocarbons. A further feature of the process according to the invention is that it significantly reduces the energy requirement for the separation of aromatic and non-aromatic hydrocarbons. The process is particularly applicable to the separation of aromatic hydrocarbons from naphthenes and paraffinic hydrocarbons in the case of starting hydrocarbon mixtures having mineral oils, in particular lubricating oils, between their net aromatic components.

The need for separating the aromatic and non-aromatic hydrocarbons of hydrocarbon mixtures, commonly referred to as disaromatization, and the advantageousness of many different aspects have long been known. For example, the BTX aromatic fraction (benzene, toluene, xylene) can be used as a feedstock for the production of petrochemicals or as an additive to increase the octane number of gasoline. Further, the non-aromatic fractions obtained from the hydrocarbon mixtures can be used for various purposes, for example as a fuel or a solvent, and therefore their recovery is also desirable. Due to the potential applications of the aromatic and non-aromatic fractions 30, a number of desaturation processes have been developed.

It is a particularly interesting and difficult task to separate the complex components present in the lubricating oils where the removal of the aromatic hydrocarbons is viscosity! index increase, heat and oxidation stability and lubricating oil color. The quality of lubricating oils is influenced by aromatic hydrocarbons due to their low viscosity index, low heat and oxidation stability, high carbon content and poor color. The aromatic hydrocarbons present in the lubricating oils are significantly different from the BTX fraction in the light 45 hydrocarbon blends used to produce gasoline, so that the separation problems encountered are significantly different from those in the BTX fraction separation.

Several processes have been developed for separating aromatic and 50 non-aromatic hydrocarbons from mixtures of hydrocarbons having the BTX fraction as an aromatic component. These processes are characterized by the use of an extraction column to separate the BTX fraction, where a mixture of glycol solvent and aqueous solution, BTX and reflux stream is introduced into a two-stage distillation column. The BTX is then distilled to remove residual water and glycol. Similarly, a process 60 is proposed where two distillation columns are used and the BTX fraction and water are distilled on the second column. In another process, two distillation columns are also used, the second column 65 distilling the BTX fraction and other components.

However, the methods described above have not proved to be appropriate in cases where the aromatic component to be removed is not a BTX fraction, and is particularly unsuitable when the task is to disinfect the lubricating oil. Therefore, several methods have been proposed for the disaromatization of hydrocarbon mixtures containing various aromatic hydrocarbons. The essence of most of these processes is the choice of extraction solvent. THE

U.S. Patent No. 400,732, for example, discloses an extraction-distillation process using primarily water as the extraction solvent. Many water-based solvents have been proposed so far for extracting aromatic hydrocarbons from a hydrocarbon mixture, but these solvents have not proved to be suitable. Examples of such water-based extraction solvents are glycol, a urine mixture disclosed in U.S. Patent 2,400,802, wherein the glycol content may be up to 50%; the

A mixture of methanol and water as disclosed in U.S. Patent No. 985,644; water, a non-oxygenated organic solvent mixture disclosed in U.S. Patent No. 2,298,791; a mixture of water and amines disclosed in U.S. Patent 2,401,852; and a mixture of water and inorganic salts, acids or bases, or organic materials disclosed in U.S. Patent 2,403,485. Problems with the use of water-based extraction solvents are well known in the art, such as the need to use extremely high pressures.

Many different methods have been proposed to overcome these known problems with the use of water-based extraction solvents. For example, U.S. Patent No. 1,783,203 describes the use of dry C 1 -C 3 alcohols for the treatment of heavy mineral oils. The toxic nature of these alcohols and the problems associated with their flammability are well known. U.S. Patent No. 1,908,018 discloses the use of certain ethylene glycol ethers, i.e., ethylene glycol and diethylene glycol ethers and acyl derivatives thereof, in mineral oil refining processes. In the process, the paraffinic and naphthenic moieties of the feed oil are separated using ethylene glycol ether and the whole mixture is cooled and stirred to obtain a paraffin-rich top and a naphthenic-rich lower layer. As is apparent from the specification, the distinction between aromatic and non-aromatic hydrocarbons is not included in the patent. The solvent was then added

EN 201576 Β removed by vacuum distillation (see column 4 of this description, starting with line 129). The process does not use ethylene glycol ethers mixed with other solvents, nor does it use glycol ether with higher ethylene glycol ethers. In addition, this process is energy intensive due to the need for distillation steps to remove the extraction solvent.

U.S. Patent 2,337,732 discloses an extraction-distillation process using ethanolamines to remove aromatic hydrocarbons from hydrocarbon distillates, including gasoline and C 1 -C 5 hydrocarbons. U.S. Patent No. 2,295,612 discloses the use of low molecular weight polyhydroxylated alcohols for the separation of aromatic mixtures to yield resin-forming compounds. U.S. Patent 2,129,283 discloses extraction of naphthenic impurities from lubricating oils with a solvent mixture of 3β, dichloro-diethyl ether and 2 to 30% propylene glycol at a temperature of 48.9 to 93.3 ° C. . U.S. Pat. No. 3,379,788 discloses the use of alkylene oxide, phenylglycidyl ether adducts.

U.S. Patent No. 834,820 discloses the use of mixed alkylene oxide, ethylene, or propylene oxide adducts as solvents for a process of disaromatization.

In order to overcome the drawbacks of the above processes, the relatively low yields and the problems of purity and solvent recovery, disaromatization processes involving extraction and distillation are proposed. Examples of such processes are solvent extraction steam distillation processes (see, e.g.

U.S. Patent Nos. 417,033, 3,714,034, 3,779,904, 3,788,980, 3,755,154 and 3,966,589); multi-extraction zones and azeotropic distillation processes (see, for example, U.S. Patent No. 3,789,077); processes employing distillation and stripping columns (see, for example, U.S. Patent Nos. 4,048,062 and 4,177,137), and processes involving multiple distillation processes (see, for example, U.S. Pat. No. 3,461,066). herein). However, these processes all involve expensive solvent distillation. In addition, these procedures are usually investment intensive and costly. Therefore, other solutions have been sought which minimize these problems.

U.S. Patent 3,431,199 discloses the solvent separation of aromatic hydrocarbons from hydrocarbon mixtures; diethylene glycol, dipropylene glycol, sulfolane and mixtures thereof are used as solvents in the process. The process is suitable for the extraction of light aromatic hydrocarbons, the extraction is preferably carried out at a temperature of 80 to 130 ° C, and azeotropic distillation of the aromatic hydrocarbons with acetone. Preferably, the solvent used is 2-8% by weight of water.

U.S. Patent 3,551,327 discloses extraction distillation with a sulfolane type solvent.

U.S. Patent 3,985,644 discloses the separation of light gasoline into aromatic and paraffin-rich fractions using methanol / water. The solvent is separated from the aromatic hydrocarbon-rich fraction by reducing the temperature of the mixture. As mentioned above, the process utilizes methanol / water mixtures. These mixtures are highly toxic and flammable.

U.S. Patent 4,086,159 discloses the separation of aromatic hydrocarbons from hydrocarbon mixtures by extraction-distillation using an ethoxylated alkane-polyol solvent. Ethoxylated alkane-polyol solvents have a high boiling point, so that high-boiling aromatic hydrocarbons such as ethylbenzene and polysubstituted benzenes can also be recovered. This process is necessarily energy intensive due to the energy demanding distillation steps.

U.S. Patent No. 4,179,362 discloses a method for separating aromatic hydrocarbon-rich mineral oil fractions from aromatic hydrocarbon-rich fractions, wherein the methanol, water extraction solvent, at least 10% water, and the extraction solvent are water. An extraction zone of 65.56-121.11 ° C is used. The water used in the extraction step reduces the solubility of the hydrocarbon in the aromatic rich extract. After the extraction step, an additional amount of water (distilled water) is added to the aroma-rich extract, such that the water, methanol solvent mixture has a water content of at least 80% by volume. The water and methanol must then be removed by energy-intensive flash distillation or by other methods, such as using a carbon dioxide extraction solvent above a critical value. The use of methanol / water solvent mixture in distillates with higher boiling points requires higher pressure to be carried out, and the methanol / water mixture also raises safety concerns as it is highly flammable and toxic.

From the foregoing processes 5, it can be concluded that there is a great need to develop a process for the de-flavoring of which costs are lower than those which have previously been commercially used. U.S. Patent No. 3,985,644 discloses a process suitable for accomplishing this goal by omitting energy-intensive steps such as distillation steps. 15

There is a great deal of interest in the desaturation of lubricating oils in particular. Desaturated lubricating oils are generally naphthenic or paraffinic viscous materials whose viscosity changes only slightly with temperature change - that is, viscosity! they have a relatively high index, high heat and oxidation stability, low carbon formation, good color and high flash point. 25

Lubricating oils are generally obtained as vacuum distillates or bottoms from crude oils. The crude lubricating oil fraction contains a variety of chemical components such as paraffins, naphthenes, aromatic hydrocarbons and the like. Generally, aromatic and polyaromatic compounds that lower the viscosity index are removed from the lubricating oil to produce refined, relatively high quality, high viscosity lubricating oils. Removal of aromatic components has been described previously and is described in 2,079,885, 2,342,205, 3,600,302,

773,005; 3,291,728; 3,788,980; and a

883,420.

U.S. Patent 2,079,885 discloses a countercurrent extraction process for refining hydrocarbon oils containing aromatic and non-aromatic components at elevated temperatures using selective solvents such as furfural or phenol, cooling the aromatic rich fraction, and refining the raffinate oil. oil-refined 30 raffinates.

However, this process involves the loss of raffinate from the aroma-rich extract.

U.S. Patent 2,342,205 discloses a solvent recovery process wherein the aliphatic and aromatic hydrocarbons are washed with water and then distilled.

U.S. Patent 3,600,302 discloses an extraction method for improving the quality of fractions obtained by distilling petroleum oils; as at least one polar functional group in the process as an extraction agent

A 6-membered 6-membered ring aromatic organic solvent such as phenol and (lower) glycol ether such as ethylene glycol monomethyl ether or diethylene glycol monomethyl ether is used. The process involves separating the solvent from the aromatic and non-aromatic phases in a conventional distillation apparatus and using (lower) glycol ether to reduce the capacity of the phenol since the capacity of the phenol is extremely high at higher extraction temperatures (see column 3, line 25).

According to the process described in U.S. Patent No. 2,773,005, light lubricating oils are extracted with phenol and water. Phenol is recovered from the second extraction fraction - this fraction contains the aromatic hydrocarbons and phenol used as the extraction solvent. Thus, in this process, a separation step is required to regenerate the extraction solvent, since the "second extraction fraction" contains phenol, which is a highly toxic compound, and aromatic substances.

According to the process described in U.S. Patent No. 3,291,728, the raffinate and extract fraction from the extraction process is washed with 25-50 volumes of water.

U.S. Patent No. 3,778,980 discloses a process for recovering an aromatic hydrocarbon by contacting the starting material with a mixture of water and solvent. The aromatics mixture is introduced into a distillation zone whose temperature is maintained at the boiling point of the aromatic mixture by steam introduced at the bottom of the distillation zone, so that a distillation zone is necessarily used to remove the aromatic compounds.

U.S. Patent No. 3,883,420 discloses a process for removing aromatic hydrocarbons from an extraction phase comprising aromatic hydrocarbons and an extraction solvent. The process employs a mixture of steam and low molecular weight paraffinic hydrocarbons (solvent). The solvent is recovered by steam stripping or extraction distillation using a solvent recovery column.

United States Patent Application Serial No. 164,039, filed June 30, 1980, describes a solvent extraction-solvent decantation process in which solvent purification of a hydrocarbon mixture or raffinate can be used.

In the process of the invention, these solvent purification steps can be eliminated.

U.S. Patent No. 267,427, filed June 4, 1981, describes the separation of starting materials containing aromatic and non-aromatic components by a specific extraction-decantation process, in which low molecular weight polyalkylene glycols are preferably used as the extraction solvent.

The process of the present invention is an improved process using an improved extraction solvent mixture. 10

The process of the present invention is more economically advantageous than the known processes in the extraction-separation process, i.e. it is energy efficient and eliminates many of the problems of the above-described processes.

The process of the present invention separates the aromatic and non-aromatic components of hydrocarbon mixtures with selective aromatic solvents, the solvent used being two or more components. In the extraction-separation process of the present invention, the extraction solvent is selected so as to contain a primary solvent component and an auxiliary solvent component for separation of aromatic and non-aromatic hydrocarbons, thereby improving process capacity and selectivity between aromatic and non-aromatic products. the amount of heat required is reduced for a wide range of starting materials.

According to the invention, the starting material consisting of a mixture of hydrocarbons, which is composed of aromatic and non-aromatic components, hereinafter referred to as the starting material, is efficiently separated at low energy consumption by a continuous solvent extraction solvent separation process. The process steps are as follows:

i) contacting the starting material with a mixed extraction solvent comprising triethylene glycol or tetraethylene glycol or a mixture thereof containing a (C1-C4) alkoxy, triglycol or a mixture of such triglycols in an extraction zone at a temperature of at least 150 ° C; and ii) cooling the latter of the resulting raffinate phase containing the non-aromatic hydrocarbons and the solvent phase containing the aromatic hydrocarbons, iii) cooling the solvent phase and dissolving the aromatic solvents in the mixed extraction solvent. where the introduced material is separated into the extract phase containing the aromatic hydrocarbons and the solvent phase containing the mixed extraction solvent and the solubilizer, and

Iv) recovering the extract phase of step iii and the raffinate phase of step i) and, if desired, recirculating the anti-solvent and the mixed extraction solvent to the appropriate previous step of the procedure.

The solvent remaining in the extract phase or in the raffinate may be removed by washing with water.

Figure 1 is a schematic flow chart of one embodiment of the process of the invention.

Figure 2 is a schematic flowchart of the procedure used in the Examples.

As described above, as before, the industry needs an ener20 ghetto-efficient process for separating aromatic and non-aromatic hydrocarbons from mixtures of hydrocarbons. Light naphtha, fuel oil, light oil, cracked naphtha, dripolene, lubricating oil (range from easy distillate to heavy distillate), kerosene and the like may contain up to 90% by weight of aromatic hydrocarbons such as BTX, or BTX fraction. . The distinction between aromatic and non-aromatic hydrocarbons is particularly important in the process of deacarburizing crude lubricating oils. The components of the hydrocarbon mixture used as starting materials are well known to those skilled in the art and are not detailed here, except that the hydrocarbon mixture used is a conventional petroleum distillation fraction containing one or more aromatic compounds including light naphtha (crude or cracked), petroleum such as gasoline, fuel oils, lubricating oils (light distillate, heavy distillate, asphalt-free distillation residue, .residual oils, jet fuel, and recycled oils. Preferably, starting material is a lubricating oil fraction, heavy distillates, asphalt-free distillation residues, etc., boiling in the range of 204.4 to 593.3 ° C.

The aromatic hydrocarbons found in the heavy hydrocarbon starting materials, such as lubricating oils, generally include alkylbenzene, indane, tetralin, indene, naphthalene, fluorene, acenaphthalene, biphenyl, phenanthrene, anthracene, diacenaphthalene. , 55 Pyrene, cripene, diaceanthracene and benzpyrene derivatives and other aromatic substances.

The process of the present invention allows for a significantly improved processing of starting materials containing aromatic and non-aromatic components. The use of a mixed extraction solvent, as described below, has several significant advantages in the extraction separation process.

First; the mixed extraction solvent is 65 lower solvent: starting material ratio

HU 201576 Β

- ie lower solvent recirculation rate - thus reducing the size of equipment required for the process, thus reducing the capital required for the investment.

Second; the use of a mixed extraction solvent reduces the amount of water used to remove the solvent and, as a result, reduces the amount of water used to wash the solvent which is captured by the raffinate and extract. (The operations will be described below with reference to the drawings.) Reducing the amount of water used for solvent separation reduces the overall energy requirement of the process.

Third; with the use of a mixed extraction solvent and a smaller amount of water, the total energy consumption of the process depends on the total amount of feedstock fed, not on the solvent: feedstock ratio used. This advantage makes it possible to treat a variety of starting materials, such as fractions from light paraffinic distillates to asphalt-free distillation residues, without significantly increasing the process energy requirements. The energy savings thus obtained in carrying out the process are equal to or greater than 50% of the energy requirements of furfural or other known processes.

Fourth; using a mixed extraction solvent, the process uses a larger proportion of solvent components depending on the raw material. degree of operability.

fifth; the use of a mixed extraction solvent can generally result in a relatively low extraction temperature, thereby improving the snow stability of the solvent.

A further advantage is that the solvent mixture used in the process of the present invention (solvent and auxiliary solvent, referred to herein as a mixed extraction solvent) provides a special balance of desired properties with the solvents used to date such as furfural, phenol, methanol and the like. solvents could not be achieved.

These are:

(a) high selectivity at the extraction temperature for the aromatic components of the starting material;

b) high solvent capacity at the extraction temperature for the aromatic components of the starting material;

(c) low capacity of the aromatic components of the starting material at temperatures below the extraction temperature;

d, chemical and snow stability under process conditions;

e) applicable to a wider range of starting materials;

f, the solvent and the cosolvent are sufficiently miscible to be recycled as a single recycled component.

As a result of these advantages, a very high quality product is obtained and lubricating oils which are otherwise difficult to process can be used as starting materials with good results.

As will be apparent to one of ordinary skill in the art, the relationship between the above characteristics is critical to the applicability of an extraction solvent.

These characteristics are in equilibrium with the mixed extraction solvent used in the extraction separation process of the present invention. The process according to the invention differs from the processes in which the extraction solvent is distilled from the aromatic extract or raffinate. The extraction solvents used in the processes used to date are not compatible with each other to reduce the energy required for the process.

As mentioned above, the solvents and auxiliary solvents used in the process of the invention are water-miscible organic liquids, boiling point and decomposition temperature higher than the extraction temperature. By water miscible is meant solvents and auxiliary solvents which are miscible with water over a wide range of temperatures or those which are miscible with water at room temperature, which are usually miscible with water at the temperature employed in the process.

The term "mixed extraction solvent" refers to a mixture comprising a solvent component and an auxiliary solvent component. These are: Solvent · triethylene glycol or tetraethylene glycol or a mixture thereof; the co-solvent is C 1-4 alkoxy triglycol, such as methoxy-triglycol, ethoxy-triglycol, propoxy-triglycol or butoxy-triglycol, or a mixture thereof.

The solvent / auxiliary solvent mixture is formulated so that the mixed extraction solvent comprises at least one solvent and at least one auxiliary solvent. The auxiliary solvent comprises 10 to 50% by weight of the total weight of the mixed extraction solvent.

In the solvent separation step of the process of the invention, an antisolvent is used. Such a substance can be, for the most part, any compound which reduces the solubility of aromatic hydrocarbons in a mixed extraction solvent. Water is the preferred anti-insoluble agent since the energy requirement of the process can be significantly reduced if steam produced by distillation of water is utilized in other processes. In addition, the water is used in the extraction step as a solubilizer

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In addition, it has been observed that the addition of the selected starting material, the mixed extraction solvent and the presence of an appropriate amount of an anti-solvent in the extraction zone further enhances the process flexibility. Other suitable dissolution inhibitors include ethylene glycol, glycerol, low molecular weight alcohols, and the like. The use of low molecular weight alcohols as an antisolvent is not always advantageous, even at low concentrations used for this purpose. This observation coincides with problems in the field of alcohol use in the art. The effective concentration of an antisolvent, as determined in the separation zone, is the amount that effectively reduces the solubility of the aromatic hydrocarbons in the mixed extraction solvent; the amount of aromatic hydrocarbons in the mixed extraction solvent is measured after leaving the separation zone. The amount of aromatic hydrocarbons in the extraction solvent leaving the separation zone is preferably less than 5% by weight, more preferably less than 3% by weight, of the extraction solvent. The anti-insoluble material used in the process of the present invention is more conducive to the formation of two phases than when the material obtained by extraction is separated by simple cooling into an aroma-rich extract and a solvent-rich phase. The concentration of the antisolvent present in the separation zone is generally 0.5 to 25.0 wt.% Or more, preferably 0.5 to 15.0 wt.%, More preferably 3.0 to 10.0 wt.%, Based on the solvent phase rich in aromatic substances. Part of the antisolvent present in the separation zone may be derived from the antisolvent present in the solvent-rich solvent phase. This solvent-rich solvent phase is obtained from the extraction zone as a substance present in the recycle of the mixed extraction solvent and the solvent inhibitor. As mentioned above, the presence of a solubility inhibitor up to 10% by weight relative to the total weight of the recycled mixed solvent is advantageous in terms of adjusting the mixed extraction solvent to changes in the starting material. The actual concentration of the antisolvent in the decantation zone may be more than 25% by weight, depending on the choice of starting hydrocarbon, the aromatic compounds contained therein, the mixed extraction solvent used, and so on. Depending on. The above-mentioned concentration of an antisolvent, such as water, is the total amount of antisolvent present in the separation zone, regardless of the origin of the substance. Preferably, the antisolvent is added to the solvent-rich solvent phase before it enters the separation zone, thereby providing better separation.

The extraction in the extraction zone is generally carried out at a volume of 2 to 20 volumes of solvent / volume starting material, preferably (2: 1) to (15: 1), more preferably 4: 1 to 10: 1, solvent: volume starting material. The wide range of solvent to hydrocarbon ratios can be expanded depending on the solvent, co-solvent, amount of co-solvent (wtX), amount of solubility inhibitor (wtX, etc.) in the mixed extraction solvent mixture, and the solvent and feedstock ratio can be optimized. whether high yield or high purity is desired, although the process of the present invention generally provides high yield and high purity at the same time.

It has been found that using the solvent / auxiliary solvent mixture according to the invention as the extraction solvent has a high selectivity and high capacity for the aromatic hydrocarbons, and the process demand (energy consumption, proportional to the feed rate of the starting material does not depend strictly on Thus, the energy requirement of the process is similar when using a wide variety of starting materials, which is not an important characteristic of processes using furfural, N-methyl-2-pyrrolidone and phenol as extraction solvents.

A further feature of the process according to the invention is that the pressure at the top of the extraction zone is typically lower than 1135 kPa, and often even lower than 790 kPa. This is very advantageous because of the simplicity of operation of the device and the capital investment required for the implementation of the separation device. The actual pressure in the extraction zone will be higher or lower, depending on the particular starting hydrocarbon, the mixed extraction solvent used, the nature and concentration of the anti-solvent, and the temperature used during the extraction. The pressure applied in the separation zone is usually simply the pressure required to pass the solvent-rich solvent phase through the separation zone, but higher pressures may be used if desired. A small pressure drop (pressure gradient) is usually observed along the separation zone.

The temperature of the extraction zone is at least 150 ° C, generally 150-275 ° C, preferably 170-250 ° C, more preferably 200-240 ° C. The temperature along the extraction zone is not constant and the temperature gradient is generally 30 ° C or greater, i.e. the temperature of the mixed extraction solvent introduced into the extraction zone and the phase leaving the extraction zone.

-Ί13

The difference between EN 201576 Β is usually 30 ° C or more. The temperature of the separation zone is generally maintained at 50-200 ° C below the temperature of the extraction zone, so that the temperature of the separation zone is preferably 25-150 ° C, more preferably 25-100 ° C, most preferably 25-70 ° C. The temperature of the separation zone is selected in part based on the solubility of the aromatic hydrocarbon in the mixed extraction solvent, the amount of antisolvent present in the separation zone, and the viscosity of the mixed extraction solvent at the temperature of the separation zone.

The apparatus used in the extraction zone, the separation zone and the like in the process of the present invention are conventionally used for this purpose.

For example, a multistep reciprocal extraction column may be used, which then contains a perforated plate centrally mounted on a vertical axis and held in oscillating motion by a motor; a pump-driven column containing a settling zone or a sifting tray can be used with up and down stream of material. (The countercurrent system is commonly used in extraction columns.) The separation operation in the separation zone may be carried out in a container without internal elements, but to facilitate separation, a container having elements (.coalescing elements *) or ribs is preferably used. Preferably, the separation zone has a depth of porous material. judge (.depth-type *, built-in element {fiber cannon built-in element). The separation of the phases in the separation zone is facilitated by the presence of an anti-solvent. As described above, the anti-solvent is preferably added to the solvent phase after leaving the extraction zone and cooled before it enters the separation zone.

Optional heat exchangers, tanks, solvent regenerators, as well as various extractors and settling vessels used in the various embodiments of the present invention are also design devices commonly used in the industry. The extractors used are generally multi-stage countercurrent extractors, but. any other type as mentioned above may be used.

The total yield of aromatic hydrocarbons according to the invention is generally 70-95% by weight or more based on the aromatic hydrocarbon content of the starting material, and the yield of non-aromatic hydrocarbons is similar.

To carry out the following examples, a Karr extraction column made of 5.08 cm internal diameter glass tubes with 5 l internal spacings with 5.08 cm spacing was used. All the metal parts inside the machine no. made of stainless steel with the exception of reciprocating plates which are non-stick. The separation zone is a tank with or without a burgundy or a glass separator filler (LS-60 P type, Selas Corporation of America) with a built-in depth element. Preferably, a fiber cannon integral member is used. The pipeline used is generally anywhere in the 316s. tube made of stainless steel, 0,95 cm outside diameter, 0,89 mm wall thickness. The water stripping column is 0.61 cm. A glass distillation column of 10.16 cm internal diameter with a 0.61 cm stainless steel coated metal packing was used.

The oil content of the various phases is determined by gas chromatography. Hewlett-Packard 5750 Chromosorb W wetted with 3% OV-101, 2 mm. A gas chromatograph with a 1.83 m column equipped with a ion ionization detector is used.

The water content of each phase was determined by Karl-Fischer automatic titration (type 392) using an automatic burette (395 Fisher Model).

The viscosity index (VI) of the starting material and the products was first determined by the ASTM D2270-75 method. The viscosity index is a measure of the purity of an oil product, the higher the viscosity index, the clearer the oil (i.e., the lower the aromatic content). After correlating the viscosity index, as determined by ASTM D2270-75, with the refractive index at 70 ° C, the viscosity index of the starting material and products was determined from the value of the refractive index at 70 ° C. The values given in the examples as the viscosity index are those obtained from measuring the refractive index at 70 ° C. Yields were calculated from the refractive index of the starting material, raffinate, and extract products at 70 ° C (% by volume of total feed material), and the yields so calculated are given in the examples.

Temperature and pressure were measured by standard detection methods.

The following is an explanation of the figures.

In the flow chart of Figure 1, the mixed hydrocarbon feedstock is fed to feed 10. The feedstock is preheated by heat exchange with the aromatic-rich extract and the raffinate. The starting material is then introduced into the heat exchanger 22, where the vapor from line 54, which is used as the antisolvent material, flows out of the solvent phase.

It is heated to and distilled into an extraction column (zone). The mixed extraction solvent (hereinafter referred to as "extraction solvent"), preferably 150-275 ° C, more preferably 200-240 ° C, is introduced through line 57 near the top of the extraction column. The extraction solvent flows downwardly through the extraction column 24 while removing aromatic materials from the feed hydrocarbon feedstock to form raffinate and aromatic phase rich solvent phase. The raffinate, which contains mainly non-aromatic substances, leaves the extraction column 24 through conduit 26 and, through the heat exchanger 20, preheats the feed hydrocarbon feed while cooling itself. The raffinate then proceeds through line 26 to a. It reaches 39 extractors, where it is contacted with water to remove any extraction solvent remaining therein to obtain an aqueous phase and a raffinate final product. (When water is used as the anti-insoluble agent, water removed from the extraction solvent is preferably added to the extractor 39.) When using some starting materials (for example, asphalt-free distillation residues and heavy distillates), the raffinate may carry a solvent. Preferably, most of this solvent is removed prior to the aforementioned 30 steps. A second aqueous extraction is carried out in the extractor 38, whereby an aqueous phase containing the mixed extraction solvent and an aromatic end product are obtained from the aromatic extract from the separation zone 34, as described below.

The aqueous phase from extractors 38 and 39 is predominantly water and contains little extraction solvent which is present in the extract rich in aromatic substances and in the raffinate as dissolved or in the form of drops. The combined aqueous phases are recycled to the separation tank 34 (zone) via line 44.

It is noted that the 'phases' and 'products' are named according to their principal components, which are present in the phase in an amount of at least 50% by weight, usually 80% by weight 50 or more.

A solvent-rich solvent comprising mainly an extraction solvent and aromatic hydrocarbons from the bottom of the extraction column 24 passes through conduit 28 to heat exchanger 30, where the extraction solvent arriving through conduit 48 cools into the heat exchanger. If desired, the solvent-rich solvent phase is further cooled in the 32 60 cooler to facilitate separation of the two phases. The recycled extraction solvent and the antisolvent, when water is used as the antisolvent, are introduced through line 44 into the separation tank 34 (zone) to recover the solvent.

B 16 is involved in the procedure. Preferably, the antisolvent is added to the solvent-rich solvent phase before it enters the separation zone 34, thereby further promoting phase formation. For example, the antifouling agent may be added at the position 46 in FIG. 1, i.e., at the connection of line 44 to line 28. However, if desired, the dissolution inhibitor may be added directly to the separation vessel 34. The latter component of the solvent extraction solvent, arriving at line 44, reduces the solubility of the aromatic hydrocarbons in the extraction solvent to an extent that cannot be achieved simply by cooling the solvent-rich solvent phase. The dissolution inhibitor is present in the separation zone 34 in an amount of 0.5 to 25.0% by weight, preferably 0.5 to 15.0% by weight, more preferably 3.0 to 10.0% by weight, of aromatic substances and solvent. The presence of the antisolvent in the separation zone reduces the solubility of the aromatic substances in the extraction solvent to such an extent that the aromatic content of the material exiting the sedimentation vessel 34 on the conduit 48 is preferably less than 3%, often less than 2%. From the separation zone 34, the extraction phase rich in aromatic substances passes through the conduit 36 and enters the aqueous extraction column 38 where it is contacted with water, preferably water removed from the extraction solvent / antisolvent mixture. This aqueous extraction removes the solvent or the entrapped solvent from the aromatic extraction phase.

From the separation zone 34, the solvent phase passes through conduit 48 and pump 50 to heat exchanger 30, where it is heated from condenser 28 to a warm, aromatic solvent-rich solvent, and then to a distillation column 52. If the solvent phase exiting the heat exchanger 30 through the conduit 48 is to be further heated, it may be further heated with the material passing through the conduit 57 in an additional heat exchanger (not shown). This additional heat exchanger is also suitable, if desired, to cool the solvent traveling through line 57. The use of the distillation zone in the process of the present invention is not limiting, since any solution can be used to reduce the concentration of the solubilizer in the extraction solvent. The use of a distillation zone is advantageous when water is used as an anti-solvent, since the steam thus formed can be advantageously and economically used in the process of the invention and / or other processes (not shown).

When water is used as a solubility inhibitor, it is the solvent which arrives via line 48

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The phase is introduced into the distillation zone 52, where the water is preferably distilled under pressure and the steam produced is removed through the conduit 54. Steam discharged from line 54 is fed to heat exchanger 22, where it is used to heat the feed hydrocarbon feedstock and then condensed in condenser 62. The water obtained by condensation can be used in the extractors 38 and 39. Alternatively, steam from the heat exchanger 22 may be advantageously used in the process of the invention or otherwise (not shown). In the heat exchanger 22, small amounts of solvent may condense. This solvent is removed from the heat exchanger (dotted line in the figure) and recycled to the extraction column 24 with the solvent from distillation zone 52 (not shown). If such steam is used in the process, the heat needed to carry out the process may be partially covered by the heat exchanger 22 associated with the distillation zone 52.

As mentioned above, instead of the solution described above, alternative methods of removing the antisolvent may be selected depending on its nature. The above solution is advantageous in reducing the energy requirement of the process according to the invention as a whole. For example, as a result of the above-described extraction-separation process, the energy requirement for the disaromatization is reduced by 50-80% compared to conventional disaromatization processes, depending on the quality of the starting material fed.

The total amount of antisolvent material, such as water, used in the system can be easily determined, since the amount of water introduced into the separation zone 34 through the conduit 46 can be measured. Also, taking into account the water loss due to leaks and malfunctions, it is necessary to ensure the presence of an antisolvent in the separation zone of 0.5 to 25.0% by weight, preferably 5.0 to 10.0% by weight.

Figure 2 illustrates another embodiment of the process of the invention. In this embodiment, some of the process features mentioned in Figure 1 are not used. The starting hydrocarbon mixture is fed via line 70 from an external starting material reservoir (not shown) and heated in a heat exchanger 72. The heated starting material is then introduced through line 74 into the extraction column 76 (zone). The selective aromatic solvent is introduced into the extraction column 76 at a location close to the top of the extraction column 76 through a conduit 104 passing through the heater 105. The extraction solvent down the column 76 removes the aromatic substances from the feed hydrocarbon mixture, thereby separating the mixture into a raffinate containing mainly non-aromatic substances and a solvent-rich solvent phase. At the top of column 76, the raffinate product, mainly composed of non-aromatic materials, which passes through line 78, is collected, cooled, and the extraction solvent is decanted. The raffinate product is then washed with water (not shown). The viscosity index of the Laffinatun product is indirectly determined by measuring the refractive index of the raffinate at 70 ° C as described above.

The solvent-rich solvent phase leaves the extraction column 76 through line 80. This phase, comprising mainly the extraction solvent and the aromatic hydrocarbons, is cooled in the heat exchanger 82 (generally consisting of one or more units of cold water cooled in series) and fed to the mixer 86. In the mixer 86, the solvent-rich solvent phase from line 84 and the antisolvent material from line 102, such as water, are mixed with each other, and the mixture is passed through line 88 to the separation zone 90. The mixer 86 includes a mechanical magnetic stirrer. In this embodiment of the process, a tank or fibrous bed coalescer, such as Sealas Corporation (Model No. LS-60P), may be used as a separation zone. In addition, a filter such as a cotton filter (not shown) in line 88 is preferably used to remove any solids present in the material entering the line. The use of a filter is particularly advantageous when a fiber-based unit with a built-in element is used as the separation zone. If desired, the anti-dissolution agent may also be added directly to the separation zone 90, i.e. the conduit 102 may be directly connected to the separation zone 90, but this is not preferred. As mentioned above, cooling on the heat exchanger 82 and addition of the anti-insoluble agent reduces the solubility of the aromatic hydrocarbons in the extraction solvent, such as an extraction phase rich in aromatic substances and one. The solvent phase consists mainly of an extraction solvent and an antisolvent (hereinafter referred to as a wet PO - solvent - only phase).

The aromatic-rich phase formed in the separation zone 90 leaves the settling zone 90 on line 92.

The wet PO phase leaves the separation zone 90 through conduit 94 and enters the water stripping column 96, where part of the wet PO phase selected as an anti-insoluble agent in the example is discharged into condenser 98 and into the catchment vessel 100. As shown in FIG. The water to be used as the anti-insoluble agent is passed through line 102 to the desired concentrate

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EN 201576 mennyiség to the 90 separation zones. The solvent from the 96 water stripping columns (hereinafter referred to as the dry PO phase)

104 wires mentioned above

It passes through a heating device 105 to the extraction zone 76. The dry PO phase also contains some water; the water content may reach or exceed 10 massX. Generally, however, the water content of the dry PO phase is below 10X. As mentioned above, the water content of the dry PO phase is preferably adjusted to ensure good efficiency of the mixed extraction solvent even when using different quality starting materials. The content of the PO phase solubilizer can be adjusted by controlling the temperature and pressure of the solubilizer removal zone. Accordingly, the capacity and selectivity of the mixed extraction solvent can be matched to the particular feedstock to be treated by bringing the mixed extraction solvent and the amount of water in the reconstituted mixed extraction solvent (dry PO fraction) into the feed. As mentioned above, there may be little oil in the dry PO phase.

The following examples illustrate the invention. The examples are not limiting.

1-8. example

1-8 in Table I. The results of Examples 1 to 5 illustrate the advantages of the process of the invention and the use of the mixed extraction solvent described. 1-8. Examples 1 to 4 were carried out according to the procedure shown in Figure 2. 1-2. Examples are comparative examples using only triethylene glycol or tetraethylene glycol as solvent. The temperature of the PO phase introduced into the extraction zone is 235 ± 5 ° C and the temperature of the separation zone is 65 ± 5 ° C.

3-8. Examples 1 to 8 use a mixed extraction solvent prepared using a tetraethylene glycol solvent and a glycol ether auxiliary as previously known. As shown in Table I, the process of the present invention achieves the same or better product quality even with lower solvent: oil ratio and lower water: oil ratio. The feed material at 70 ° C is a refractive index residue of 1.4820 (viscosity index 91) free of asphalt.

3-8. Examples 1 to 4 show that using a mixed extraction solvent reduces the solvent to oil ratio and the raffinate viscosity index remains unchanged or improved; the amount of water required for washing raffinate and extract products is reduced, i.e. the water to feed ratio is reduced.

Table I

Example Solvent ¹ O / B ^z HzO / Feed ³ PO ⁴ temperature Paraffin-containing raffinate (Yield X) (VI) ⁵ (R1) ⁵ First TEG 13.5 1.19 232 81 99 1.4780 14.3 0.93 235 82 98 1.4786 Second TETRA 13.4 0.861 236 72 101 1.4754 16.9 1,050 235 70 101 1.4755 14.2 0.518 235 74 100 1.4763 Third 20 massX 10.0 0.541 232 75 100 1.4763 ETG / TETRA 9.4 0.57 230 77 100 1.4767 7.8 0.56 230 79 99 1.4770 4th 30 massX 9.4 0.283 221 66 101 1.4753 ETG / TETRA 7.9 0.248 220 71 100 1.4768 5th 25 massX 7.9 0.239 221 71 100 1.4760 MTG / TETRA 6.1 0.248 221 77 99 1.4775 6th 30 massX 9.7 0.608 231 53 103 1.4730 MTG / TETRA 7.8 .595 231 68 101 1.4755 8.2 0,600 231 72 100 1.4759

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HU 201576 Β

Example Table I Solvent ¹ 0 / B ² H2O / Feed ³ PO ¹ temperature Paraffin-containing raffinate (Yield X) (VI, ³ (RLP 7th 44.5 wtX MTG / TETRA 7.9 0.203 221 54 103 1.4731 8th 11.5 wt 9.7 0.861 231 70 101 1.4750 BTG / TETRA 8.1 0,686 235 73 100 1.4758 8.3 0.736 235 75 100 1.4764

TEG = triethylene glycol; TETRA = tetraethylene glycol; MTG = methoxyglycol; ETG = ethoxyglycol; BTG = butoxitriglycol;

0 / B = solvent: volume ratio of feed oil

The volume ratio of water to feed is the ratio of the amount of water to the feedstock fed to extraction zone 2 that is added to the cooled solvent before it enters the separation zone. This water can be used to wash the raffinate and / or extract to better remove the solvent.

PO temperature of the solvent phase consisting mainly of extraction solvent and anti-solvent (° C)

VI = viscosity! index, R1 = refractive index (at 70 ° C)

Claims (7)

PATENT CLAIMS A process for the preparation of aromatic hydrocarbons from a mixture of hydrocarbon starting materials during the process i) contacting the starting material with an extraction solvent mixed in an extraction zone at a temperature of at least 150 ° C, ii) cooling the latter of the raffinate phase containing the non-aromatic hydrocarbons and the solvent phase containing the aromatic hydrocarbons, iii) cooling the solvent phase and introducing an inhibitor of solubility of the solvents in the mixed extraction solvent into a separation zone, wherein the introduced material is separated into the extract phase containing the aromatic hydrocarbons and the solvent phase containing the mixed extraction solvent and the solubilizing agent, followed by step iv) i) recovering the raffinate phase of step i) and, if desired, recirculating the anti-solvent and the mixed extraction solvent to a suitable earlier step of the process, characterized in that triethylene glycol or tetraethylene glycol or a mixture thereof and additionally 10 to 50% by weight of a mixed extraction solvent (C 1-4 alkoxy) triglycol or a mixture of such triglycols and water as the anti-insoluble agent. 2. A process according to claim 1 wherein the tetraethylene glycol is a methoxy triglycol solvent mixture. 3. A process according to claim 1, wherein in step iii, 0.5 to 25.0 wt. A process according to claim 1, wherein the temperature of the separation zone is maintained at 150-275 ° C. 5. The process of claim 1, wherein the temperature of the separation zone is maintained at 25-150 ° C. The method of claim 1, wherein. ³ θ characterized in that in step i) 4 to 12 volumes of solvent are added to the extraction zone based on 1 volume of feedstock. The process of claim 1 for removing hydrocarbon mixtures containing a crude oil fraction i) maintaining the temperature of the extraction zone at 150-275 ° C; ii) cooling the latter of the resulting raffinate phase and solvent ⁴⁰ ; iii) maintaining the temperature of the separation zone at 10 ° C to 70 ° C; a cooled solvent phase and 0.5-25.0 wt. removing the solubilizing agent from the containing phase; v) recovering the mixed extraction solvent recovered in step iv) to step i); vi) converting the raffinate from step i) and the extract from step iii) with water into two separate aqueous phases, vii) returning at least a portion of the two aqueous phases of step vi) to step iii) and -1 223 EN 201576 (ix) recovering the extract and raffinate obtained in step (vi), characterized in that triethylene glycol or tetraethylene glycol or a mixture thereof is used as a mixed extraction solvent, and additionally 10 to 50% by weight of (1-4C) alkoxy based on the mixed extraction solvent. triglycol or a mixture of such triglycols and water as the anti-insoluble substance. Published by the National Office for Inventions, Budapest Responsible: dr. Gabriella Swaboda Head of Department R 4968 - KJK 91.3521.66-13-2 Alföldi Nyomda Debrecen - Chief Executive Officer: Viktor Szabó Chief Executive Officer