JPH037648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION 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 the alkyl aromatic hydrocarbon is catalytically alkylated in the presence of an alkylating agent such as methanol, formaldehyde, or a methylal agent to form a side chain alkyl group having a larger number of carbon atoms than the raw material alkyl aromatic hydrocarbon. The present invention relates to a method for obtaining an alkyl aromatic hydrocarbon having a group.

By using the method of the present invention, it is possible to synthesize, for example, ethylbenzene and styrene from toluene, ethyltoluene and methylstyrene from xylene, and kyumene from ethylbenzene, etc., with high yield and with little deterioration over time of the catalyst activity used. .

Conventionally, as a method for obtaining alkyl aromatic hydrocarbons, a method of catalytic nuclear alkylation of benzene with an olefin (ethylene, propylene, dodecene) in the presence of a Friedel-Crafts catalyst has already been industrialized.

For example, in order to industrially produce ethylbenzene, the benzene obtained by dealkylating alkyl aromatic hydrocarbons such as toluene and xylene in catalytic reforming oil of naphtha or pyrolysis oil of naphtha is treated with ethylene to produce ethylbenzene such as aluminum chloride. A method of nuclear alkylation in the presence of an acid catalyst has been adopted.
However, since these methods use aluminum chloride, etc., there are many economic disadvantages such as corrosion of equipment, recovery of products, and treatment of waste catalysts, and benzene as a raw material is more expensive than toluene, so they are not suitable for industrial use. This is even more disadvantageous. On the other hand, the catalytic side chain alkylation method can produce ethylbenzene by directly alkylating toluene, which is contained in a large amount in catalytic reformed oil or naphtha pyrolysis oil, using methanol as an alkylating agent. This is an interesting process because it can greatly shorten the process of the conventional method and eliminate the disadvantages of the conventional method, such as equipment corrosion.

PRIOR ART In general, many research examples are known regarding methods for alkylating alkyl aromatic hydrocarbons using methanol as an alkylating agent, but most of them use solid acids; Only nuclear alkylation occurs (for example, synthesis of xylene from toluene), and side chain alkylation, which is the main focus of the present invention, does not occur at all. What is known in the literature regarding the alkylation reaction of the side chain alkyl group of an alkyl aromatic hydrocarbon with methanol is that after zeolite is exchanged with potassium, rubidium or cesium ions, boric acid or phosphoric acid and their sodium salts are added. A method using a catalyst has been proposed. (See U.S. Pat. No. 4,140,726). However, in this method, although the initial activity is high, the activity deteriorates significantly over time due to carbon precipitation, which poses an industrial problem.

On the other hand, the present applicant has discovered that a catalyst in which an oxide of one or more metals selected from the group consisting of potassium, rubidium, cesium, and francium is supported on activated carbon as a side chain alkylation catalyst for alkyl aromatic hydrocarbons has a high He discovered that it was active and stable with little change over time (Japanese Unexamined Patent Application Publication No. 1983-1999).
(See Publication No. 133932).

Summary of the Invention In order to further improve the method of the invention of JP-A No. 52-133932, the present inventors have conducted intensive studies to efficiently alkylate the alkyl side chains of alkyl aromatic hydrocarbons using various catalyst systems. The present invention was completed by carrying out the following steps.

That is, the present invention provides a method for catalytically alkylating the alkyl side chain of toluene in the presence of an alkylating agent, in which the catalyst used is activated carbon as a carrier and the catalyst components include (a) potassium, rubidium, and cesium; The present invention provides a method for catalytic side chain alkylation characterized by containing one or more alkali metal compounds and (b) cesium borate.

Detailed Description of the Invention (Catalyst) The catalyst used in the method of the present invention has activated carbon as a carrier, and the catalyst components include (a) one or more alkali metal compounds consisting of potassium, rubidium, and cesium, and (b) ) Contains cesium borate.

Examples of the activated carbon used as the carrier include coconut shell activated carbon, coal-based activated carbon, petroleum pitch activated carbon, and the like.

Sources of potassium, rubidium and cesium include inorganic salts of these alkali metals, such as carbonates,
In addition to bicarbonates, nitrates, etc., oxides, hydroxides,
Organic acid salts such as formic acid, acetic acid, and oxalic acid can be used.

The catalyst used in the method of the present invention includes the above potassium,
One or more alkali metal compounds consisting of rubidium and cesium and cesium borate are contained as catalyst components on an activated carbon carrier. in this case,
These alkali metal compounds are carried in an amount of 1 to 50% by weight, preferably 5 to 25% by weight, based on the activated carbon. In addition, cesium borate is 0.5
~25% by weight, preferably 1-20% by weight.

(Catalyst Preparation) Although the catalyst can be prepared by any conventionally known method, a simple method is to introduce an aqueous solution of an alkali metal soluble compound onto a carrier by evaporation to dryness. For example, activated carbon is immersed in an aqueous solution containing cesium nitrate and cesium borate.
Evaporate to dryness at 100℃, and then evaporate to 1-24℃ at 100-120℃.
Re-dry in air for an hour.

In addition to the method of simultaneously supporting an alkali metal compound such as cesium nitrate and cesium borate as described above, there is also a method of supporting an alkali metal compound first, drying it, and then adding cesium borate. A method can be adopted in which the alkali metal compound is added after the addition of the alkali metal compound.

Firing is performed at 400 to 600° C. for 1 to 10 hours in an inert gas (N ₂ , He, Ar, etc.) or reducing gas (H ₂ , CH ₄ , ethane, CO, etc.).

(Alkyl Aromatic Hydrocarbon) The raw material alkyl aromatic hydrocarbon used in the present invention refers to monoalkyl monocyclic aromatic hydrocarbons (for example, toluene, ethylbenzene, etc.) or polyalkyl monocyclic aromatic hydrocarbons (for example, xylene, etc.). each isomer). In addition to methanol, formalin or its lower condensates (trioxane, 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.

The reaction conditions for carrying out the alkylation reaction are as follows:
The reaction temperature is preferably in the range of 350 to 600°C, more preferably in the range of 380 to 550°C.
The reaction pressure is preferably in the range of 0.1 to 20 Kg/cm ² , more preferably in the range of 0.1 to 15 Kg/cm ² . The raw material feed rate is preferably 0.1 to 10.0 cc/cc-cat-hr expressed in liquid hourly space velocity (LHSV).
and is preferably in the range of 0.2 to 5 c.c./cc-cat-hr. The molar ratio of alkylating agent such as methanol and alkyl aromatic hydrocarbon is 0.05 to 30 mol/
mol is used, preferably 0.1 to 20 mol/mol.

Experimental Examples Example 1 To 50 ml of an aqueous solution in which 1.95 g of cesium nitrate and 0.5 g of cesium borate were dissolved, 8 g of petroleum pitch-based activated carbon (trade name "Kuraray Coal" manufactured by Kuraray Chemical Co., Ltd.) was added while stirring occasionally. Evaporate to dryness at 50-100°C. Next, it was dried at 100-120°C for 24 hours.
Furthermore, 2 g of this was placed in a quartz reaction tube and fired at 450° C. for 3 hours in a nitrogen stream at a gas flow rate of 12/hr. 15% by weight prepared in this way
The activity of Cs ₂ O - 5% by weight cesium borate/activated carbon catalyst (cesium other than cesium borate is shown in terms of Cs ₂ O. The same applies hereinafter) was measured at a reaction temperature of 410°C, normal pressure, LHSV 2.5cc/ cc-cat-hr,
The evaluation was performed under reaction conditions of a methanol/toluene ratio of 1/5.25 (mol/mol).

As a result of gas chromatograph analysis of the product for 1 hour from the 1st hour to the 2nd hour after the start of the reaction, the ethylbenzene yield (based on methanol) was
It was 21.0 mol%. When the reaction was continued, the yield gradually increased, and when the product was analyzed by gas chromatography for 1 hour from 8th to 9th hour after the start of the reaction, the yield of ethylbenzene (based on methanol) was 26.2 mol. It was %. After this, the reaction was continued, but there was almost no deterioration in activity over time.

Example 2 A 15% by weight Cs ₂ O-2.5% by weight cesium borate/activated carbon catalyst was prepared in the same manner as in Example 1 except that the amount of cesium borate was changed.

The reaction was carried out in the same manner as in Example 1 except that this catalyst was used, and the product was analyzed from 8 hours to 9 hours after the start of the reaction. As a result, the ethylbenzene yield (based on methanol) was 22.0 mol%. Ta.

Example 3 A 15% by weight Cs ₂ O-10% by weight cesium borate/activated carbon catalyst was prepared in the same manner as in Example 1 except that the amount of cesium borate was changed.

The reaction was carried out in the same manner as in Example 1 except that this catalyst was used, and the product was analyzed from 8 hours to 9 hours after the start of the reaction. As a result, the ethylbenzene yield (based on methanol) was 23.0 mol%. .

Example 4 The catalyst used in Example 1 was prepared, and the catalytic activity was evaluated under different reaction conditions as follows.

Reaction temperature 440℃, normal pressure, LHSV2.6cc/cc-
cat-hr, methanol/toluene ratio 10/1 (mol/
The evaluation was made under the reaction conditions of (mol). As a result of gas chromatograph analysis of the product for 1 hour from 8th hour to 9th hour after the start of the reaction, the yield of ethylbenzene (based on toluene) was 23.8 mol%.

Example 5 15% by weight Cs ₂ O - 5% by weight boric acid in the same manner as in Example 1 except that the activated carbon as a carrier was changed to carbon molecular sieve (trade name "Adsorb C" manufactured by Nishio Kogyo Co., Ltd.) A cesium/activated carbon catalyst was prepared and used in the reaction in the same manner as in Example 1 to examine the catalytic activity.

As a result, the yield of ethylbenzene in the product from 7 hours to 9 hours after the start of the reaction (based on methanol) was 22.0 mol%.

Example 6 Using the same catalyst as that used in Example 5, the reaction conditions were a reaction temperature of 410°C, normal pressure, LHSV 2.5cc/
Catalytic activity was investigated using cc-cat-hr, methanol/toluene/N ₂ (diluent) = 1/5.25/32 (molar ratio).

As a result, when the products were analyzed from 9 hours to 10 hours after the start of the reaction, the yield of ethylbenzene (based on methanol) was 18.5 mol %, and the yield of styrene (based on methanol) was 2.5 mol %.

Comparative Example 1 Using a cesium hydroxide aqueous solution containing boric acid, 60% of the sodium in sodium-exchanged type A type X zeolite catalyst was prepared.

The reaction was carried out in the same manner as in Example 1 except that this catalyst was used.
Analysis of the products after that time revealed that the yield of ethylbenzene (based on methanol) was 13.0 mol% and the yield of styrene (based on methanol) was 13.5 mol%. However, when the reaction was continued and the product was analyzed for 1 hour from 8th hour to 9th hour after the start of the reaction, the yield of ethylbenzene (based on methanol) was 4.0 mol%, and the yield of styrene (based on methanol) was 3.8 mol%.
It was hot. Although this catalyst has high initial activity, the activity deteriorates significantly over time.

Comparative Example 2 Same as Example 1 except that sodium borate was used instead of cesium borate, 15% by weight
A Cs ₂ O-5% by weight sodium borate/activated carbon catalyst was prepared and the reaction was carried out in the same manner as in Example 1. Analysis of the product revealed that the yield of ethylbenzene (based on methanol) was 14.2 mol%.

Comparative Example 3 A 15 wt% Cs ₂ O-5 wt% boric acid/activated carbon catalyst was prepared in the same manner as in Example 1 except that boric acid was added instead of cesium borate, and the reaction was carried out in the same manner as in Example 1. When the product was analyzed, the yield of ethylbenzene (based on methanol) was 10.5 mol%.

Comparative Example 4 A 15% by weight Cs ₂ O/activated carbon catalyst was prepared in the same manner as in Example 1 except that cesium borate was not added.

Reaction conditions: reaction temperature 480℃, normal pressure, LHS
V.1.5cc/cc-cat-hr, methanol/toluene=
This catalyst was evaluated using a 10/1 (molar ratio).
Ethylbenzene yield (based on methanol) as a result of analyzing the product from 8 hours to 9 hours after the start of the reaction
was 16.7 mol%.

Comparative Example 5 In the experiment of Comparative Example 4, only the reaction temperature was set to 440°C.
When the reaction was carried out by changing the formula, the yield of ethylbenzene (based on methanol) was 14.0 mol%.

Comparative Example 6 When the reaction was carried out in the same manner as in Example 1 except that the catalyst prepared in Comparative Example 4 was used and the catalyst was evaluated, the ethylbenzene yield (based on methanol) was 16.7 mol%.
It was hot.

Comparative Example 7 A 17.7% by weight Cs ₂ O/activated carbon catalyst was prepared by the same catalyst preparation method as in Example 1, except that cesium borate was not added.

The alkylation reaction was carried out under the same reaction conditions as in Example 1, and the product was analyzed from 8 hours to 9 hours after the start of the reaction. As a result, the ethylbenzene yield (based on methanol) was 15.7 mol%.

Comparative Example 8 A 25.0% by weight Cs ₂ O/activated carbon catalyst was prepared by the same catalyst preparation method as in Example 1, except that cesium borate was not added.

An alkylation reaction was carried out under the same reaction conditions as in Example 1, and the product was analyzed from 8 hours to 9 hours after the start of the reaction. As a result, the ethylbenzene yield (based on methanol) was 15.3 mol%.

From the above Examples and Comparative Examples, it is clear that by using the method of the present invention, alkylation of the alkyl side chain of an alkyl aromatic hydrocarbon can be carried out with good yield.

Claims (1)

[Claims] 1. A method for catalytically alkylating the alkyl side chain of toluene in the presence of an alkylating agent, in which the catalyst used is activated carbon as a carrier and contains (a) potassium, rubidium, and cesium as catalyst components; and (b) cesium borate.