JPH02152934A - Production of alkyl aromatic hydrocarbon from lower isoolefin - Google Patents

Abstract

PURPOSE:To catalytically make lower olefin into a middle fraction containing a large amount of alkyl aromatic hydrocarbon almost without changing the aromatic hydrocarbon by bringing the lower isoolefin into contact with silica alumina catalyst in the presence of an aromatic hydrocarbon. CONSTITUTION:<=7C isoolefin is brought into contact with silica alumina catalyst in the presence of 6-8C aromatic hydrocarbon (A) (e.g. benzene or toluene) at 90-220 deg.C under 0-50kg/cm<2>G to give >=10C alkyl aromatic hydrocarbon (B) by polymerization and ring formation of the isoolefin and alkylation. The amount of the reaction product B is at least four times as much as the amount of the consumption of the component A and at least 90% of the component A added at the initial stage is recovered. The component A and the lower isoolefin are fed in the weight ratio of 0.2-2.5/1 and a catalyst heat-treated under contact of steam and oxygen is used as the catalyst.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention relates to a method for catalytically refining lower isoolefins, and more specifically, the present invention relates to a method for catalytically refining lower isoolefins, and more specifically, converts hydrocarbons containing lower isoolefins or lower inolefins into alkyl aromatic The present invention relates to a method of catalytically heavyening a middle distillate containing a large amount of hydrocarbons.

[Prior Art] In petroleum refining, a method of cracking and lightening heavy oils such as petroleum fractions and residual oils is widely used in order to obtain gasoline fractions and the like. In this process, lower hydrocarbons containing large amounts of olefins are produced as by-products. Of these, propane and butane are recovered as liquefied petroleum fuels, and propylene and butene are recovered as petrochemical raw materials, but light hydrocarbons with 5 to 6 carbon atoms, so-called light naphtha, are recovered as gasoline blending base materials and petrochemical raw materials. Although it is used as a raw material, demand is unstable and there is often a surplus. In addition, the light hydrocarbons have drawbacks such as a lack of storage stability.

On the other hand, middle distillates such as kerosene and light oil can be obtained by cracking heavy oils in addition to straight-run distillates, and steady demand is expected for them for consumer use, transportation, etc.

Alkyl aromatic hydrocarbons are also useful as petrochemical raw materials.

Therefore, light hydrocarbons are oligomerized (
Various methods have been proposed for producing higher-grade hydrocarbons.

For example, a method in which an olefin having 2 to 12 carbon atoms is oligomerized with ZSM-13 zeolite and converted into a dimer to tetramer (Japanese Patent Application Laid-Open No. 56-92222) or ZSM-5
, ZSM-11, ZSM-12, 25M35 and ZSM
A method has been proposed in which olefins having 2 to 5 carbon atoms are oligomerized using 38 zeolite to produce gasoline fractions and middle distillates (Japanese Unexamined Patent Publication No. 33391/1983).

[Problems to be Solved by the Invention] However, when silica-alumina catalysts are used as oligomerization catalysts, they have the disadvantage that the degree of polymerization of the oligomers produced is low. What was the problem was that the production efficiency of relatively high middle distillates was very low. In addition, with this catalyst, especially an amorphous silica/alumina catalyst, linear or branched paraffinic hydrocarbon oligomers (low polymers) are produced from lower olefins, but aromatic hydrocarbons are produced by cyclization of olefin chains. , and the production of aromatic hydrocarbons such as alkylbenzene by alkylation of the produced aromatic hydrocarbons was hardly observed.

A method for obtaining aromatic hydrocarbons by cyclizing olefins is disclosed, for example, in JP-A-52-155692, but this method uses an expensive catalyst containing a gallium compound, and also In order to obtain group hydrocarbons in high yield, the treatment is carried out at a high temperature of 550°C.

Therefore, an object of the present invention is to provide a method for producing kerosene and gas oil fractions by making lower olefins with low added value heavier, and also producing alkyl aromatic hydrocarbons useful as petrochemical raw materials. be.

[Means and effects for solving the problem] As a result of intensive research in order to solve the problem, the present inventors found that aromatic hydrocarbons having 6 to 8 carbon atoms such as benzene, toluene, and xylenes Using a silica-alumina catalyst in the presence of
When the low polymerization reaction of light hydrocarbons containing isoolefins proceeds, the aromatic hydrocarbons hardly change (
Products containing aromatic hydrocarbons such as alkylbenzene (
A middle distillate is produced containing a high conversion, substantially by the cyclization of lower isoolefins to produce aromatic hydrocarbons and the alkylation of the aromatic hydrocarbons thus produced.
We have discovered the surprising fact that alkyl aromatic hydrocarbons are produced with high selectivity, and that most of the aromatic hydrocarbons added at the beginning of the reaction can be recovered and reused.The present invention was completed based on this knowledge. This is what I did.

That is, in the present invention, in the presence of an aromatic hydrocarbon having 6 to 8 carbon atoms, a lower isolefin having 7 or less carbon atoms or a hydrocarbon containing the above-mentioned lower isolefin is brought into contact with a silica/alumina catalyst to form a lower inolefin. By polymerization, cyclization and alkylation of olefins, alkyl aromatic hydrocarbons having 10 or more carbon atoms (including the number of carbon atoms in the aromatic ring) are produced at least 4 times the consumption amount of aromatic hydrocarbons having 6 to 8 carbon atoms. A method for producing alkyl aromatic hydrocarbons from lower isoolefins having 7 or less carbon atoms, characterized in that at least 90% of the initial addition amount of aromatic hydrocarbons having 6 to 8 carbon atoms is recovered. . According to the method of the present invention, alkyl aromatic hydrocarbons can be produced substantially from lower isoolefins with high selectivity and efficiency, and a middle distillate rich in aromatic hydrocarbons such as alkylbenzene can be obtained. In the present invention, the lower isoolefin used as a raw material has 4 carbon atoms.
-6 isolefins are preferred, particularly isopentene having 5 carbon atoms, which has the highest conversion rate compared to other isoolefins. This raw material isolefin may be used alone, but it can also be used as a hydrocarbon mixture containing it. Such hydrocarbon mixtures include so-called light naphtha fractions, which are produced as by-products when petroleum fractions and residual oils are hydrodesulfurized, catalytically cracked, or thermally cracked; It will be done.

When a light hydrocarbon mixture containing lower isoolefins is used as a raw material, there is no particular restriction on the content of lower isoolefins in the mixture, but if the amount of components that do not participate in the reaction, such as paraffinic hydrocarbons, increases, the reaction will increase. Since the properties (conversion rate) decrease, it is desirable that the content be at least 20% by weight or more. In addition, when normal olefin is used alone, it reacts with aromatic hydrocarbons to produce alkyl aromatic hydrocarbons in the presence of the catalyst of the present invention, but an olefin mixture composition containing isoolefins as a main component exhibits the same behavior as isoolefins. Mixed olefins containing less than 30% normal olefins can be used as feedstock hydrocarbons in the present invention, since alkyl aromatic hydrocarbons are produced without substantially consuming aromatic hydrocarbons. This is also one of the excellent features of the present invention.

In the present invention, the aromatic hydrocarbon itself hardly reacts and is recovered as an unreacted substance, but its presence promotes the cyclization reaction of isoolefins, acting as if it were a catalyst. That is, in the present invention, an alkyl aromatic hydrocarbon production reaction is carried out using substantially only isoolefins as raw materials.

Depending on the type and amount added, the added aromatic hydrocarbons may be consumed by the alkylation reaction, but even in such cases, the amount of aromatic hydrocarbons added should be at least 4 times, usually 10 times, the amount of aromatic hydrocarbons consumed. The above alkyl aromatic hydrocarbons are produced. In the normal alkylation reaction of aromatic hydrocarbons using aromatic hydrocarbons as a raw material, the amount of alkyl aromatic hydrocarbons produced is as follows: In this case, the consumption amount of raw material aromatic hydrocarbons is approximately twice the maximum (theoretical value), but in the present invention, a much larger amount of alkyl aromatic hydrocarbons can be obtained. As a result, the consumption amount of the added aromatic hydrocarbon is an extremely small amount of less than 174 of the generated alkyl aromatic hydrocarbon,
More than 90% of the initial charge is recovered, which can be recycled and reused after separation.

As the aromatic hydrocarbon, benzene, toluene, and xylenes having 6 to 8 carbon atoms are used. Among them, toluene is partially consumed in the alkylation reaction as shown in the examples, but in the presence of toluene, It is most preferred because it has a high conversion rate of isoolefins and a high yield of aromatic hydrocarbons.

These can be used either in the form of a single compound or in the form of a mixture.

Further, the amount of the aromatic hydrocarbon added is in the range of 0.2 to 2.5, particularly 1.0 to 2.5 per liter of isoolefin in terms of weight ratio.
．． It is preferable to add in a range of 0. If it is less than 0.2, the effect of adding the aromatic hydrocarbon will not appear, and if it is more than 2.5, the amount of the aromatic hydrocarbon consumed by the alkylation reaction with the olefin will increase, which is not preferable.

The above-mentioned aromatic hydrocarbon may be mixed and added to the raw material lower isoolefin in advance and supplied to the reactor, or may be supplied to the reactor separately from the raw material.

In particular, the catalyst applicable to the present invention is a silica-alumina catalyst, which is generally used as a solid acid catalyst in reactions such as catalytic cracking, isomerization, polymerization, and alkylation of petroleum fractions. Both crystalline and amorphous silica/alumina catalysts can be used, but in the present invention, in the presence of aromatic hydrocarbons, lower isoolefins can be converted using inexpensive amorphous silica/alumina catalysts. It is economically advantageous because alkyl aromatic hydrocarbons can be produced.

The silica-alumina catalyst that has been heat-treated in contact with steam and oxygen is preferably used. The ratio of silica/alumina is 60,740 to 9,515 by weight, especially 70/3.
0 to 90/10 is preferred. In addition, heat treatment under contact with steam and oxygen is carried out at a steam/oxygen molar ratio of 50/1 to 1/1, preferably 30/1.
Heat treatment may be performed at a temperature of 600 to 900° C. for about 2 hours in an atmosphere of 5/1. As oxygen, a pure gas may be used, but a mixture diluted with air or another gas may also be used.

In carrying out the present invention, as other reaction conditions, the reaction temperature is preferably 90 to 220°C, particularly preferably 140 to 200°C, and the reaction pressure is 0 to 50 kg/
crt? G, weight-based liquid hourly space velocity (WHSV) is 0.1
A range of ~20 hr-' is preferred. Furthermore, this reaction can be carried out in either a fixed bed or suspended bed system.

[Examples] Hereinafter, the present invention will be described in more detail based on Examples, but the present invention is not limited thereto.

A silica-alumina catalyst [N631 (L) manufactured by JGC Chemical Co., Ltd.] containing 13% by weight of alumina is crushed to give a 32 to 34
The prepared catalyst was heat-treated in an air and steam atmosphere (700'CX for 2 hours), and 3.1 g of the obtained catalyst was packed into an autoclave with an internal volume of 50 cc, and this was filled with 12.6 g of various raw material olefins, 12. Add 6g of the mixed solution (no benzene was added in Comparative Example 1), seal the autoclave, and raise the temperature to 155°C while stirring.
A time reaction was performed.

The composition of the reaction product obtained by the above reaction was measured by gas chromatography. The results are shown in Table 1.

As is clear from these examples, when isoolefins are brought into contact with the catalyst of the present invention in the presence of benzene, carbon atoms with a carbon number of 10
It can be seen that the above alkyl aromatic hydrocarbons are obtained as main products. Even if benzene is consumed in small quantities,
A much larger amount of alkyl aromatic hydrocarbons is produced compared to the benzene conversion rate.

On the other hand, without the addition of benzene, no alkyl aromatic hydrocarbons are produced at all. Furthermore, when normal olefins are used as raw material hydrocarbons, alkyl aromatic hydrocarbons are produced, but a large amount of benzene is consumed, and only a normal alkylation reaction between benzene and olefins occurs.

Comparative Medical Day A silica/alumina catalyst treated in the same manner as in Examples 1 to 3 was packed into a reaction tube with a diameter of 20 mm, and diluted with 2-methyl-2-butene impenkun to give a 30% weight % of raw material hydrocarbons and various aromatic hydrocarbons at a ratio of 7=3 (weight ratio) (comparative example 3, no aromatic hydrocarbons were added) at 120 cc/hr (WHSV=8 hr-'). Supply, temperature 160℃, pressure 30kg/crr? 6 in G
A time reaction was performed. The reaction product was collected every hour, and its composition was analyzed by gas chromatography, and the olefin conversion rate, the added aromatic hydrocarbon conversion rate, the product yield, etc. were calculated. Table 2 shows the results for 1 hour from 5 to 6 hours after the start of the reaction.

The continuous reaction results in Table 2 show almost the same tendency as the results in Table 1, but the results in Table 2 show that among the aromatic hydrocarbons with 6 to 8 carbon atoms used in the present invention, toluene exhibits a unique behavior. It can be seen that this shows that

Although toluene itself partially reacts, the amount of aromatic hydrocarbons produced is more than five times the amount of toluene consumed, and a much larger amount of alkyl aromatic hydrocarbons is derived from the alkylation of toluene itself. is being generated. That is, in the present invention, toluene has a stronger effect of promoting polymerization, cyclization, and alkylation of isoolefins than benzene or xylene.

10g of the silica/alumina catalyst treated in the same manner as Comparative Example 1 was packed into the reaction tube used in Examples 4 to 6, and C,
, C, as a main component (containing 21% by weight of isoolefins and 7% by weight of normal olefins) and aromatic hydrocarbons in a ratio of 7:3 (weight ratio) (Comparative Example 4 is an aromatic group hydrocarbons added) at 120cc/hr (
WH3V=8hr-1), temperature of 160℃, 3
The reaction was carried out for 50 hours under a pressure of 0 kg/cm2G.

Reaction products were collected at predetermined oil passage times and analyzed by gas chromatography. The results are shown in Table 3.

In Example 7, a mixture with an isoolefin/normal olefin weight ratio of 3 was used as the raw material olefin, but benzene was hardly consumed and alkyl aromatic hydrocarbons were produced, which was different from when only inolefin was used as the raw material. The same behavior was exhibited, and the alkylation reaction of aromatic hydrocarbons with normal olefins as shown in Comparative Example 2 hardly occurred. Also in Example 8 in which toluene was used as the aromatic hydrocarbon, toluene was partially consumed, but alkyl aromatic hydrocarbons were produced in high yield in the presence of toluene.

Reaction conditions: suspended bed 5 reaction temperature 155°C, reaction time 1 hour (Note) Product yield is based on raw material olefin, same Table 1 below
(continued) Raw material: Hydrocarbon mixture of 30% by weight of 2-methyl-2butene and 70f1% of isopentane = 773 (fixed bed, reaction temperature 160°C, WHSV 8hr",
Oil passing time 5th to 6th hour) Table (raw material 0 cracked light naphtha, containing 21% by weight of isoolefin and 7% by weight of n-olefin) cracked light naphtha/
Mixing ratio of aromatic hydrocarbons = 7/3 (fixed bed, reaction temperature 1
60°C, WHSV 8hr”) [Effects of the Invention] The present invention is characterized in that lower isoolefins are treated with silica in the presence of aromatic hydrocarbons such as benzene, toluene, or xylenes.
By contacting with an alumina catalyst, lower inolefins are highly efficiently converted into alkyl aromatic hydrocarbons through polymerization, cyclization, and alkylation without substantially changing the aromatic hydrocarbons, resulting in a gas oil that is a middle distillate. It is characterized in that a particularly large amount of fraction can be obtained, and most of the aromatic hydrocarbons added initially can be recovered and reused.

The alkyl aromatic hydrocarbon thus obtained can be used as a petrochemical raw material, and by dealkylation or the like, it can also be used to obtain benzene, etc., which has higher added value and utility value.

3 (continued)

Claims (1)

[Claims] 1. In the presence of an aromatic hydrocarbon having 6 to 8 carbon atoms, a lower isolefin having 7 or less carbon atoms or a hydrocarbon containing the lower isolefin described above is brought into contact with a silica/alumina catalyst. By polymerization, cyclization and alkylation of lower isoolefins, alkyl aromatic hydrocarbons having 10 or more carbon atoms are obtained in an amount at least 4 times the consumption amount of aromatic hydrocarbons having 6 to 8 carbon atoms, and A method for producing an alkyl aromatic hydrocarbon from a lower isoolefin having 7 or less carbon atoms, characterized in that at least 90% of the initially added amount of the aromatic hydrocarbon having .about.8 carbon atoms is recovered. 2. Temperature 90~220℃, pressure 0~50kg/cm^2
A method according to claim 1, characterized in that the contacting is carried out under conditions of G. 3. Aromatic hydrocarbon and lower isoolefin at 0.2/
3. A method according to claim 1, characterized in that the contacting is carried out in a weight ratio of 1 to 2.5/1. 4. The method according to any one of claims 1 to 3, wherein the silica-alumina catalyst is heat-treated in contact with steam and oxygen.