JPS606336B2 - Catalytic side chain alkylation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 1. Background of the Invention {11. Technical Field The present invention relates to a method for alkylating a side chain alkyl group of an alkyl aromatic hydrocarbon.

More specifically, the side chain alkyl group of an alkyl aromatic hydrocarbon is alkylated with an oxygen-containing compound such as methanol or formaldehyde in the presence of a novel catalyst with high performance, and the alkyl aromatic group of the raw material is The present invention relates to a method for obtaining an alkyl aromatic hydrocarbon whose side chain alkyl group has one more carbon atoms than a group hydrocarbon. For example, it can be used to synthesize ethylbenzene from toluene, kyumene from ethylbenzene, ethyltoluene from xylene, etc.

Conventionally, the method for obtaining alkyl aromatic hydrocarbons has been to convert benzene into olefins (ethylene, propylene, dodecene).
A method of catalytic nuclear alkylation in the presence of a Friedel-Crafts catalyst has already been commercialized. For example, in order to industrially produce ethylbenzene, the benzene obtained by dealkylating alkyl aromatic hydrocarbons such as toluene and xylene in naphtha catalytic oil or naphtha pyrolysis oil is treated with aluminum chloride etc. using ethylene. A method of nuclear alkylation in the presence of an acid catalyst has been adopted.

However, since this method uses aluminum chloride, etc., there are many economic disadvantages such as corrosion of the catalyst, recovery of products, and treatment of waste catalysts.Furthermore, the raw material benzene is more expensive than toluene, so it is not suitable for industrial use. This is even more disadvantageous.
In contrast, the catalytic side chain alkylation method uses catalytic reformed oil,
It is possible to produce ethylbenzene by directly alkylating toluene, which is contained in large amounts in naphtha pyrolysis oil, using methanol as an alkylating agent, and it is possible to produce ethylbenzene by directly alkylating the toluene contained in large amounts in naphtha pyrolysis oil. This is an interesting process because it can overcome the disadvantages of (2- Prior Art In general, many research examples are known on methods of alkylating alkyl aromatic hydrocarbons using methanol as an alkylating agent, but most of them use solid acids; In some cases, only nuclear alkylation occurs (
For example, synthesis of xylene from toluene), side chain alkylation, which is the main focus of the present invention, does not occur at all.

A known document regarding the alkylation reaction of alkyl aromatic hydrocarbons using methanol as a side chain alkyl group is Soviet Patent No.
There is No. 8958. According to the Soviet patent specification, toluene was alkylated at 425oo, MeOH/toluene = 0.33 (mol/mol) using a catalyst in which molecular sieve 13x (Na type) was ion-exchanged with K, Rb, and Cs salts. The reaction was carried out, and the toluene conversion rate was 3.2 to 4.1 mol.
%, side chain alkylation selectivity based on toluene is 42-92
It is stated that it is hol%.

However, as is clear from these results, both the toluene single flow conversion rate and the side chain alkylation selectivity are 4.0%, and there is a large change in catalyst activity over time, which is thought to be due to carbon precipitation. There are problems. Furthermore, an industrial problem has been pointed out in that since the side reaction products are mainly nuclear alkylation products, it is difficult to separate the desired product. (For example, in the alkylation of toluene, it is necessary to separate ethylbenzene and om/p-xylene.) From the above points of view, in order to efficiently carry out this reaction process, it is necessary to have stable activity, high emotionality, and The development of new catalysts with high selectivity is desired. B. Summary of the Invention The present invention is directed to catalytic side chain alkylation of alkyl aromatic hydrocarbons in higher yields than conventional ones using a catalyst system newly discovered from the above-mentioned viewpoints.

More specifically, ``when alkylating the alkyl side chain of an alkyl aromatic hydrocarbon using methanol as an alkylating agent, an oxide of one or more metals selected from the group consisting of potassium, rubidium, cesium, and francium is used. The feature of the present invention is that the metal oxides of potassium, rubidium, cesium, and francium are brought into contact with a catalyst supported on activated carbon. The purpose is to use a catalyst supported on

For example, when these alkali metal oxides are supported on other inert carriers such as silica or diatom, the alkylation reaction does not occur at all, and when these alkali metal oxides are supported on other inert carriers such as silica or diatom, no alkylation reaction occurs, and also when these alkali metal oxides are supported on other inert carriers such as silica or diatom, no alkylation reaction occurs. When supported on a generally known carrier, the main reaction is the nuclear alkylation reaction, and side chain alkylation hardly progresses. After intensive research into development, we discovered that by using a catalyst system that combines activated carbon, which does not show any activity on its own, and the alkali metal oxide mentioned above, we were able to improve the activity selectivity of Okinawa compared to an alkali-exchanged zeolite catalyst. It is currently unknown why side chain alkylation activity is expressed by the combination of potassium, rubidium, cesium, and francium metal oxides and activated carbon, but these alkali metal oxides 1 to 5 cloud cover% to activated carbon
, preferably 5 to 25% by weight, allows the side chain alkylation reaction to proceed efficiently. As the activated carbon, commonly used activated carbon such as coconut shell-based activated carbon, coal-based activated carbon, petroleum pitch-based activated carbon, etc. can be used. (preparation)
Although the catalyst can be prepared by any conventionally known method, it is convenient to introduce an aqueous solution of an alkali metal soluble compound onto a carrier by evaporation to dryness.

For example, if activated carbon is introduced into an aqueous solution of cesium nitrate,
Evaporate to dryness at 100qo ~ further 100~11000
Let dry again in the air for 1 to 1 hour. Firing is performed using an inert gas (N2, He, Ar, etc.) or a reducing gas (Z, C
H4, ethane, CO, etc.) 400-600 pm 0, 1
Do this for 1 to 1 feeding period. Carbonates as alkali metal salts,
Bicarbonates, nitrates, oxides, hydroxides, as well as formic acid,
Organic acid salts such as acetic acid and oxalic acid can also be used. ■ Catalytic side chain alkylation (alkyl aromatic hydrocarbons) The raw material alkyl aromatic hydrocarbons used in the present invention are monoalkyl monocyclic aromatic hydrocarbons (e.g. toluene, ethylbenzene, etc.) or polyalkyl monocyclic hydrocarbons. Aromatic hydrocarbons (eg xylene isomers, etc.).

In addition to methanol, formalin or its lower condensates (trioxaso, paraformaldehyde, etc.) can also be used as the alkylating agent. (Catalytic side chain alkylation reaction) The alkylation reaction is generally carried out by thoroughly mixing the raw material alkyl aromatic hydrocarbon and methanol, which have been vaporized in a preheating section, and then introducing the mixture into the catalyst layer. be.

Factors to be controlled as reaction conditions are reaction temperature, reaction pressure, raw material supply rate, and molar ratio of methanol to alkyl aromatic hydrocarbon. ~50k9/en, 0.1~10.0cc'cc-cat-hr and 0
．． 1-3 hol/mol preferably 380-5500
0, normal pressure to 35k9' flow, 0.2 to 5cc/cc catalyst
time and o. 2 to 2 dishes ol/mol.

Hereinafter, the present invention will be explained in more detail with reference to Examples. Example 1 50% of an aqueous solution containing 3.90% of cesium nitrate
16,000 g of coal-based activated carbon (trade name: Llumicol) was added thereto, and the mixture was evaporated to dryness at 80 to 100°C.

Next, it was dried at a temperature of 100 to 11,000 for 1 hour. Furthermore, 20 times the dried catalyst was put into a quartz reaction tube, and the gas flow rate was 20 times.
Firing was performed at 450° C. for 3 hours in a N2 stream of 1/hr.
The activity of the 15 wt% Cs20/activated carbon catalyst thus prepared was determined at a reaction temperature of 430 pm, normal pressure, and LHSV 3.
The reaction conditions were cc'cc-cat-hr and a methanol/toluene molar ratio of 10/lmol/mol. Gas chromatography analysis of the product for 1 hour from 3G minutes to 1 hour and 30 minutes after the start of the reaction revealed that the toluene conversion rate was 15.9 mol% and the ethylbenzene selectivity was approximately 100 mol%.

Example 2 15% by weight CS2 was prepared by the same catalyst preparation method as in Example.
0/The type of activated carbon in the activated carbon catalyst is petroleum pitch-based activated carbon (
It was prepared by changing the brand name to Kuraray-LQ).

Reaction temperature 440oo, normal pressure, LHSV 2.6 cc/c
c-cat-hr methanol/toluene molar ratio 10/
Activity was evaluated in lmol'mol. As a result of analyzing the product up to 30 minutes after the start of the reaction, the toluene conversion rate was 23.2.
The ethylbenzene selectivity was 95.9 mol%. Some styrene, ortho, meta, para-xylene, and cumene were detected as reaction products other than ethylbenzene. Example 3 A 15% by weight RQO/activated carbon catalyst (coal-based activated carbon trade name Agen was used) was produced using the same catalyst preparation method as in Example 1.

As a result of carrying out the alkylation reaction of toluene with methanol under the same reaction conditions as in Example 2, the toluene conversion rate was 6.
．． At 5 mol%, the selectivities for ethylbenzene and styrene were 93.8 and 4.6 mol%, respectively. Example 4 15 wt% K20/
An activated carbon catalyst (using coal-based active product name Agen) was manufactured.

As a result of carrying out the alkylation reaction of toluene with methanol under the same reaction conditions as in Example 1, the toluene conversion rate was 1.
．． At 9 mol%, the selectivity for ethylbenzene was approximately 100 mol%. Example 5 Using the same catalyst as in Example 1 and using methanol and ethylbenzene as raw materials, 430q0, normal pressure, LHSV 3cc/c
The side chain alkylation reaction was carried out under the reaction conditions of c-cat-hr and a methanol/ethylbenzene molar ratio of 1 mol/mol.

As a result of analyzing the product for 1 hour from 30 minutes to 1 hour and 30 minutes after the start of the reaction, the conversion rate of ethylbenzene was 4.4 mol%.
, cumene selectivity was 53.4 mol%, n-propylbenzene selectivity was 11.8 mol%, and other ortho-, meta-, and para-ethyltoluene were slightly produced. Example 6 Using the same catalyst as in Example 1 and using methanol and para-xylene as raw materials, 430°C, normal pressure, LHSV 3cc'cc
The side chain alkylation reaction was carried out under the reaction conditions of -cat-hr and methanol/para-xylene molar ratio dish hol/mol.

As a result of analyzing the product for 1 hour from 30 minutes to 1 hour and 3 minutes after the start of the reaction, the conversion rate of para-xylene was 12.5 mol%.
, para-ethyltoluene selectivity was 91.6 mol%, and some other substances such as diethylbenzene were produced. Comparative Example 1 A 15% by weight CS20/Si02 catalyst and a 15% by weight Rb2q catalyst were produced by the same method as in Example 1 except that silica was used as the carrier.

An alkylation reaction of toluene with methanol was carried out under the same reaction conditions as in Example 2, but regardless of which catalyst was used, the toluene conversion rate was 0.1 mol % or less and almost no ethylbenzene was produced. Comparative Example 2 Molecular sieve 13x (Na type) was ion-exchanged with a CsCI aqueous solution by the usual method to replace 70% of Na with Cs.
A replacement catalyst was produced.

Claims (1)

[Claims] 1. When alkylating the alkyl side chain of an alkyl aromatic hydrocarbon using methanol as an alkylating agent, at least one oxide selected from the group consisting of potassium, rubidium, cesium and francium is supported on activated carbon as a catalyst. A method for catalytic side chain alkylation of alkyl aromatic hydrocarbons, characterized by contacting them.