CS208740B2 - Method of gaining the pure aromatic hydrocarbons or the mixtures thereof - Google Patents

Abstract

Isolation of pure aromatic hydrocarbons from a stabilised reformate or a fraction thereof comprises passing the feed at high temp. (and at a pressure sufficient to maintain the feed in the liq. phase) through abed of macroporous sulphonated cation-exchange resin in the H+ form. The effluent is then subjected to distn. extraction or extractive distn. in known manner to isolate the individual aromatics. The cation exchanger treatment is pref. at 60-140 degrees C (esp. 100-140 degrees C). Deposits of tars and oligomers on the exchanger can be periodically removed by regeneration with mixts. of polar solvent (esp. lower alkanols) and aromatic hydrocarbons pref. contg. 10-60% polar solvent. The cation exchanger removes unsatd. cpds. from the reformate by catalysing their conversion to alkylaromatics and oligomers, this facilitates subsequent isolation of the aromatics.

Description

(54) Method for obtaining pure aromatic hydrocarbons or mixtures thereof

The invention relates to a process for obtaining pure aromatic hydrocarbons or mixtures thereof from liquid products of catalytic reforming of gasoline, called reformates. The gasoline reforming liquid products, called reformates, consist mainly of a mixture of aromatic hydrocarbons (benzene, toluene, xylene and aromatic compounds having 9 or more carbon atoms), as well as paraffinic and constituent hydrocarbons. Further, in the mix of products obtained by reforming beinzine, unsaturated compounds are present in an amount of about 0.5 to 3%. especially olefins, cyclooefins and diene hydrocarbons. The content of unsaturated compounds in the reformates is usually expressed as a bromine number which, depending on the reforming conditions, is in the range of 1 to 5 g Br / 100 ml. When separating aromatic hydrocarbons from reformed products, the presence of unsaturated compounds is highly undesirable.

Two processes are known to recover pure aromatic hydrocarbons from the reformate.

According to the first procedure, the stabilized reformate, i.e. the reformate from which the low-boiling hydrocarbons have been removed, is extracted with organic solvents and the trace amount of unsaturated compounds is removed from the aroma extract obtained. Methods of such refining have been described in which bleaching clays, clay solutions or cation exchangers are used as catalysts, for example in the process of Polish Patent No. 86,867. and react with the solvent used in the process, which, among other reasons, contributes to increasing solvent consumption and reducing its selectivity.

Another method for obtaining hydrocarbons from aromaaických 'reformate is a preliminary removal of unsaturated compounds from the reformate refining ν ^^! ^ Mank ^OR totaíyttokcu ^h ydr refinací ^about 208,740, after which the refined reformate extracted or extractive distillation, and the obtained extract is subsequently rozdeettluje in individual aromatic hydrocarbons.

The disadvantage of this method of purification of the reformate is that it requires the use of hydrogen, which is a short-circuit, the need to withstand high temperatures and pressures, as well as expensive catalysts and complex equipment.

It has now surprisingly been found that the above disadvantages and disadvantages of the prior art methods can be avoided by using the method of the invention.

The inventive method for purification of liquid products reforming naphtha or fractions thereof from compounds of the unsaturated nature lies in the fact that in the first stage ttabiliovvaný reformate or fractions thereof treated at a higher temperature, i.e. at temperatures ranging from 60 to 14 ⁰ C in ^the and ^p aln ^{e f} azide ion exchanger with sulfonic ions at JINR ^P roc ^hook ne ^p Ruto ^for verifies a rate in the range of ^{d 0,} 5 ^d of ^{4, 0,} h ^'1, whereupon the reformate extra-is or extractive eestilljs some known processes to obtain the resulting pure aromatic hydrocarbons.

^p i r ^ finace is preferably operated at a range of toplotoch ^d 1ОД to ¹⁴⁰ ° C. In order to keep the reformate in the liquid phase, a suitable overpressure in the range of 0.1 to 1.0 MPa is used.

Increasing the operating temperature extends the period of catalyst depletion between two successive regenerations. During contact of the cation exchange ion exchange resin with the catalyst grains, the unsaturated compounds are eluted and oligomerized to give a reformate free of! unsaturated compounds.

If necessary, some of the higher alkyl aromatic hydrocarbon derivatives and oligomers of the unsaturated compounds formed by the process of the invention can be readily separated by distillation.

It has been found that during processing of the reformate, the cation exchanger gradually loses its ratalytical efficacy, including due to the sorption of oligomers and tars.

Therefore, it is sometimes advantageous to regenerate them with polar solvents.

Surprisingly, it has been found that the best results are obtained when using not pure polar solvents such as mehanl, isopropanol, acetone, but mixtures thereof with an aromatic one. hydrocarbons containing 10 to 60% of a polar component. It is preferable to use regenerative mixtures in which the concentration of the polar component is lower than in the azeooropic roe formed by the aromatic hydrocarbon. The use of such regenerative mixtures facilitates their further recovery and reduces the loss of the polar component.

The catalyst may be regenerated at a rate of less than about 100%.

According to the invention umo0ňujs snnžit piri loss of solvent extraction of extractive not ^{b e} es ^tt lhci reformate. Amortized straight ^from the dream ^ ^ ^ the ^ jackets cost reduction due to the operating pressure and temperature as compared with conventional methods. The high quality of the resulting reformate treatment products, i.e., benzene, toluene and xylenes, is achieved.

The process according to the invention is illustrated by the following examples.

Example 1

Stabilized reformate having a distillation range of 65-195 DEG C and a bromine number of 1.6 and heated to 90 ° C was passed through a column filled with cationic Ш1 25 s i nto ^the ENIC ^{m H +} -CY ^LU (Aabbrtyst speed ⁵⁰ ml / ^h 'to ^b 5 to ^{1 0} hours. ^From ískáv ^plated product of bromine number in the range from 0.02 to 0.2, which is distilled to separate the fraction having a boiling point of 180 ° C. with Desstlát It is extracted at 60 DEG C. with a solvent which is a mixture of N-meethlpyrrolidone and ethylene glycol to obtain an aromatic extract from which, after distillation, aromatic fractions, i.e. benzene, toluene and xylene, are obtained. benzene in the range 79-82 ° C, toluene in the range 109-112 ° C and xylene in the range 138-146 ° C. They are distinguished by the following coloring with sulfuric acid according to ASTM D 842 + 62: benzene 1, toluene 0 + 1 , xylene 1.

For comparison, they were isolated only by extraction and final de-distillation under otherwise identical conditions of the aromatic fraction of the reformate which had not previously been refined on the cethionic ion exchanger. The resulting fractions had these ASTM coloring characteristics: benzene 5, toluene 6, xylene 3.

Example 2

The stabilized reformate having a distillation range of 62 to 205 ° C and characterized by a bromine number of 2.3 is heated to 120 ° C at an overpressure of about 0.6 MPpa, which ensures that the reformate remains in the liquid phase and passed through the column, sulphonic filled with 25 ml of ion exchanger (Wofatit OK-80) in H ^ ^p ^ o -cycle prop ⁱⁿ Tost ^and přziWiz them ^ ^0, 4 cm ³ / ^g at 100 ml / h for 100 hours. The product is characterized by a bromine number between 0.04 and 0.3.

Example 3

The reformate was treated as in Example 1 using a regenerated macroporous cation exchange resin (Amerlyst 15). The regeneration is carried out by washing the cation exchange bed with 7 parts by volume of toluene with 3 parts by volume of methanol at 50 ° C at a rate of 2 volumes / 1 volume of catalyst per hour for 6 hours, followed by passing the catalyst bed at 120 ° C with toluene 4 volumes (calculated as liquid hydrocarbon). The reformate treated on this regenerated ion exchange material has a bromine number in the range 0.05 to 0.3.

Example 4

FRA ^to CE reform мt ^Jd Stila ^ ne ^ ⁶ between 5 and ⁸⁵ ° C, c ^h ERA ^to terizovan domovým ^á · number of 4.2 is passed through a bed of cation exchange resin (Ambrlyst 15) at 15 ° C at 2 volumes ^ catalyst bed volume per hour for more than 100 hours. The reformed contact with the cation exchange resin is in the liquid phase under an appropriate overpressure (0.4 to 0.6 MPpI.) The reformate fraction obtained as the product has a bromine number in the range of 0.02 to 0.25.

This fraction is then distilled to separate fractions boiling above 100 ° C. .

The product is extractively íestilujs for pouužtí N ^ meehyllyyrolidonu as a solvent ^carrier, whereby ^z is pure získzá ^b enzen of ^{d b} o u ^t u ^h Nut: to ^5.4 ° C with zkrvením účirdcem sulfuric acids ¹ according to ASTM D 848 - 62 between 0 and +1 *

Claims (2)

SUBJECT OF THE INVENTION A process for obtaining pure aromatic hydrocarbons or mixtures thereof from a stabilized gasoline reforming product by distillation, extraction, extractive distillation, used together or separately, using a macroporous sulfonic ion ion exchanger, characterized in that the stabilized reformate or fraction thereof is first passed at a flow rate in the range of from 0.5 to 4.0 beds of sulfonic ion exchangers in the H-cycle at a temperature in the range of from 60 to 140 ° C, optionally under a pressure of from 0.1 to 1.0 MPa, maintaining the reformate still in the liquid phase, after which the reformate or fraction thereof is treated to separate the individual hydrocarbons. 2. A process according to claim 1, wherein the tar-like substances adsorbed onto the macroporous sulfonic ion exchanger are removed by washing with a polar solvent such as lower aliphatic alcohols mixed with aromatic hydrocarbons.