JPH06145672A - Production of fraction containing highly aromatic hydrocarbon - Google Patents

Abstract

(57) [Summary] [Structure] A naphtha fraction is contacted with a reforming catalyst and a zeolite-containing aromatization catalyst under reforming conditions. The aromatization catalyst is brought into contact with the aromatization catalyst under reforming conditions, or the reforming catalyst and the zeolite-containing aromatization catalyst are in a weight ratio of 95: 5.
A process for producing a highly aromatic hydrocarbon-containing fraction, which comprises contacting a catalyst bed filled with 60:40 under reforming conditions. [Effect] A fraction having a high content of aromatic hydrocarbons, particularly benzene and toluene, can be produced from the naphtha fraction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a highly aromatic hydrocarbon-containing fraction by catalytically reforming a naphtha fraction.

[0002]

2. Description of the Related Art In petroleum refining, a naphtha fraction is catalytically reformed to produce a high-aromatic hydrocarbon-containing fraction, which is widely used as a raw material for producing high octane number catholine or BTX. The catalytic reforming of the naphtha fraction is generally carried out by adding a heavy naphtha fraction having a boiling point in the range of 60 to 210 ° C. to platinum using alumina as a carrier, or rhenium by adding platinum.
Using a catalyst supporting germanium, tin, iridium, ruthenium, etc., at a temperature of 400 to 550 ° C., 1 to 50 kg
/ Cm ² pressure, liquid hourly space velocity (LHSV) of 0.1 to 3 h ^-1 , and hydrogen / oil molar ratio of 0.5 to 20. In this catalytic reforming, in order to increase the content of aromatic hydrocarbons in the produced oil, the reaction conditions have to be severe under the use of the same feed oil type and the same catalyst. However, harsh reaction conditions shorten the catalyst life, and this method naturally has limitations.

On the other hand, the applicant of the present invention has reported that a crystalline aluminozine cosilicate catalyst, which is one of zeolite-containing aromatization catalysts, has 2 to 7 carbon atoms in the absence of hydrogen and is an aliphatic hydrocarbon or alicyclic hydrocarbon. Has been proposed to convert them into aromatic hydrocarbons by contacting them (JP-A-3-99025 and JP-A-3-1725).
8934, JP-A-4-95034, etc.). This method
If anything, it is characterized by synthesizing an aromatic hydrocarbon from an aliphatic hydrocarbon having less than 6 carbon atoms. For example, in this method, about 50% of n-pentane is converted to an aromatic hydrocarbon. Can be converted.

[0004]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention The inventor of the present invention is concerned with cyclization of hydrocarbons using a zeolite-containing aromatization catalyst
As a result of diligent research, when a reforming catalyst and a zeolite-containing aromatization catalyst were used in combination, and the naphtha fraction was contacted under reforming conditions, surprisingly, the functions of both catalysts complemented each other. It was found that the yield of aromatic hydrocarbons can be improved.

The present invention has been made based on such findings, and an object of the present invention is to provide a method for producing a fraction having a high content of aromatic hydrocarbons, particularly benzene and toluene, from a naphtha fraction. .

[0006]

The present invention comprises contacting a naphtha fraction with a reforming catalyst and a zeolite-containing aromatization catalyst under reforming conditions. In particular, the naphtha fraction is used as a reforming catalyst. Subsequently, the zeolite-containing aromatization catalyst is brought into contact with the catalyst under reforming conditions, or the catalyst bed and the reforming conditions are filled with the reforming catalyst and the zeolite-containing aromatization catalyst in a weight ratio of 95: 5 to 60:40. It is a process for producing a fraction containing a high aromatic hydrocarbon, which comprises contacting underneath.

The naphtha fraction referred to in the present invention is a petroleum fraction having an overhead condensation fraction to 210 ° C. obtained by an atmospheric distillation separation operation, and in particular, a heavy oil having a boiling point in the range of 60 to 210 ° C. A high quality naphtha fraction is preferred. This naphtha fraction is obtained by a direct distillation naphtha fraction obtained by distilling crude oil under atmospheric pressure, as well as by purification treatment such as thermal cracking, catalytic cracking, hydrocracking, etc. of petroleum fractions and residues. The obtained fraction in the boiling point range or the like can also be used. This naphtha fraction preferably has a sulfur content and a nitrogen content of 50 ppm, particularly 1 ppm or less. This is a commonly used hydrodesulfurization treatment method under ordinary desulfurization conditions, for example, , A carrier such as alumina or silica-alumina carrying one or more kinds of cobalt, nickel, molybdenum, tungsten, etc., at a temperature of 250 to 430 ° C., a pressure of 10 to 200 kg / cm ² , a liquid space velocity ( It is preferable to use desulfurized naphtha desulfurized under the conditions of LHSV) 0.1 to 15 h ⁻¹ and hydrogen circulation amount of 50 to 1400 Nm ³ / kl.

The reforming catalyst used in the present invention includes alumina as a carrier, platinum, or rhenium in addition to platinum.
As long as it is a catalyst supporting germanium, tin, iridium, ruthenium, etc. and used in a method for producing a high octane gasoline from a normal naphtha fraction, it can be adopted without any particular problem.

On the other hand, the zeolite-containing aromatization catalyst of the present invention comprises a skeleton structure of MFI-type, L-type or β-type crystalline aluminosilicate, or comprises all or part of the alumina of the skeleton component. Periodic table IIb of zinc, zinc, etc.
It is substituted with a group IIIa element such as gallium and gallium, and a group VIII element such as platinum, and has an aromatizing activity of producing an aromatic hydrocarbon from a lower hydrocarbon having 3 to 5 carbon atoms.
As this type of zeolite, crystalline gallosilicate,
Crystalline aluminogallosilicate, crystalline zincogallosilicate, crystalline aluminozincosilicate, or by introducing a group IIb, IIIa or VIII element of the periodic table into the ion exchange site by the usual ion exchange method, The thing which carried these elements on the said zeolite surface can be illustrated.

Among these, a crystalline aluminozine cosilicate obtained by partially replacing the aluminum of the crystalline aluminosilicate with a zinc cation is preferable. This is because the silicon, aluminum and zinc atoms are crosslinked by sharing oxygen to form a crystalline aluminosilicate. It has the same skeletal structure as aluminosilicate. This crystalline aluminozine cosilicate has a high Si / Al atomic ratio of 14 to 35, and has aluminum substituted with zinc until the Si / Zn atomic ratio of 30 to 350 has a high activity and selection of aromatic hydrocarbons. It is particularly preferable because of high rate and long catalyst life.

The zeolite aromatization catalyst of this type is preferably one in which an alkali metal such as sodium or potassium is replaced with hydrogen ion so that the alkali metal content is 0.4% by weight or less. Further, this catalyst can be used as the above zeolite itself, but it is also possible to use one having the zeolite as a carrier and supporting a transition metal such as platinum or chromium thereon.

This zeolite-containing aromatization catalyst is generally a silicon compound, an aluminum compound, or if necessary, an element of Group IIb, IIIa or VIII of the Periodic Table, an alkali metal compound, water and, if desired, an organic compound as a template. Nitrogen compound, and then acid is mixed to obtain 100
It can be synthesized by maintaining the temperature at 220 ° C for 3 to 200 hours.

In the present invention, the reforming catalyst and the zeolite-containing aromatization catalyst are used in combination. One of the embodiments in this case is a method in which heavy naphtha is first modified with a reforming catalyst and then contacted with a zeolite-containing aromatization catalyst. In this method, a catalyst bed in which an aromatization catalyst is mixed is brought into contact with the mixed catalyst and a naphtha fraction.

According to the former method, the lower part of one reaction tower is filled with a zeolite-containing aromatization catalyst, the upper part thereof is filled with a reforming catalyst, and a naphtha fraction is introduced and flowed down from the upper part to bring them into contact with each other. good. Of course, a reaction vessel filled with the reforming catalyst and a reaction vessel filled with the zeolite-containing aromatization catalyst may be separately prepared and used by connecting them in series with a pipe. In this case, the filling amount of the catalyst is 95: 5 by weight ratio of the reforming catalyst and the zeolite-containing aromatization catalyst.
It is preferably set to 60:40. When the loading of the zeolite-containing aromatization catalyst is 5% by weight or less,
An improvement in the yield of aromatic hydrocarbons cannot be expected so much, and even if the filling amount is 40% by weight or more, the improvement in the yield of aromatic hydrocarbons is small compared to the increase in the filling amount, which is not preferable.
Further, if the packing amount of the zeolite-containing aromatization catalyst is increased, the packing amount of the reforming catalyst is reduced and the yield of aromatic hydrocarbons is reduced unless the volume of the reaction column is changed. 40% by weight of the total catalyst
The following is preferable.

On the other hand, the latter method is, for example, a so-called C, which comprises a moving bed obtained by adding a catalyst continuous regeneration method to a reaction vessel.
It is suitable for the CR (continious catalyst regeneration) method. In this case, the reforming catalyst and the zeolite-containing aromatization catalyst are mixed in a weight ratio of 95: 5 to 60:40, and are used for reaction and regeneration.

The contact with the above catalyst is carried out under normal reforming conditions. That is, a temperature of 400 to 550 ° C., 1 to 5
Liquid space velocity (LHSV) of 0.1-under hydrogen pressure of 0 kg / cm ^2.
It is appropriately selected within a range of 3 h ⁻¹ and a hydrogen / oil molar ratio of 0.5 to 20.

The product oil obtained as described above contains a high content of aromatic hydrocarbons, and is used as a base material for high-octane gasoline, or from this, aromatic hydrocarbon components such as benzene, toluene and xylene. It can be separated and recovered and used as a raw material for various petrochemical products.

[0018]

【Example】

(Example) Preparation of Zeolite-Containing Aromatization Catalyst Crystalline aluminosine cosilicate was prepared as a zeolite-containing aromatization catalyst by the following method.

Sodium chloride 3.3 in distilled water 13.1 kg
1 kg and tetrapropylammonium bromide 59.3 g
Solution C in which is dissolved in distilled water 7.50 kg zinc sulfate 301
g, 397 g of aluminum nitrate, 178.5 g of tetrapropylammonium bromide and 504 g of concentrated sulfuric acid were added simultaneously and continuously with stirring. At that time, sodium hydroxide or sulfuric acid was added so that the pH of the mixed solution was maintained at 10. The temperature of this mixed solution was raised to 160 ° C. in 3 hours, and subsequently stirred at 160 ° C. for 2 hours.
The mixture was allowed to cool, the solid substance was taken out, 1N ammonium nitrate was added until the solid substance concentration became 4%, the mixture was stirred at 80 ° C. for 2 hours to remove the supernatant liquid, washed with water and dried. To 2.4 kg of the crystalline aluminozin cosilicate thus obtained, 240 g of silica-magnesia synthetic clay was added as a granulating agent, and the mixture was molded into a spherical shape having a diameter of 4 mm by a rolling granulator and dried. It was baked at 540 ° C. Next, this was immersed in 1N ammonium nitrate at a temperature of 80 ° C. for 2 hours, dried, and then baked at 540 ° C. This catalyst has a Si / Al atomic ratio of 29, a Si / Zn atomic ratio of 48, and a Si / Na
Had an atomic ratio of 834.

This catalyst also has a temperature of 500 ° C. and an LH
Conversion of n-pentane to 4 under conditions of SV 0.8h ^-1 and atmospheric pressure
It had an initial activity of converting to aromatic hydrocarbons at 9%.

Reaction under reforming conditions Crystalline aluminodine cosilicate catalyst 2 prepared above
0 g and a commercially available reforming catalyst (U-6, R-6
2) A desulfurized heavy naphtha fraction having the properties shown in Table 1 and hydrogen gas, which had been hydrodesulfurized, were supplied from the top of a reaction vessel filled with 100 g, and the temperature was 500 ° C. and the pressure was 10 kg / cm ² G, L.
The reforming reaction was carried out under the conditions of HSV 1.0 h ^-1 and hydrogen / oil molar ratio of 3.2. The composition of the reaction product after 48 hours is shown in Table 2.

[Table 1]

[Table 2]

Comparative Example 100 g of the same catalyst as the reforming catalyst used in the above example was charged in a reaction vessel, and the reforming reaction was carried out under the same conditions as in the example. The composition of the reaction product after 48 hours is shown in Table 2.

As is clear from these results, the yield of aromatic hydrocarbons, especially benzene and toluene, can be increased by using the reforming catalyst and the zeolite-containing aromatization catalyst in parallel.

[0024]

INDUSTRIAL APPLICABILITY The present invention has the effect of producing a fraction having a high content of aromatic hydrocarbons, particularly benzene and toluene, from a naphtha fraction.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Mitsunobu Nakata 25 Kitahamacho, Chita City, Aichi Prefecture Japan Mining Co., Ltd. Chita Refinery

Claims (3)

[Claims] 1. A method for producing a highly aromatic hydrocarbon-containing fraction, which comprises bringing a naphtha fraction into contact with a reforming catalyst and a zeolite-containing aromatization catalyst under reforming conditions. 2. A method for producing a highly aromatic hydrocarbon-containing fraction, which comprises contacting a naphtha fraction with a reforming catalyst and subsequently with a zeolite-containing aromatization catalyst under reforming conditions. 3. A naphtha fraction is contacted under a reforming condition with a catalyst bed filled with a reforming catalyst and a zeolite-containing aromatization catalyst in a weight ratio of 95: 5 to 60:40. A method for producing a fraction containing a high aromatic hydrocarbon.