JPH0639421B2 - Toluene alkylation catalyst and process for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a toluene alkylation catalyst and a process for producing the same.

[Prior Art and Problems] Alkali metal catalysts are suitable for alkylating side chains of alkylaromatics with olefin, and sodium metal or potassium is dispersed on an inorganic carrier or graphite carrier as is well known. The catalyzed catalyst is used. For example, in the Finnish patent application No. 865362 by the inventor,
A catalyst containing metallic sodium on a K ₂ CO ₃ carrier is disclosed. British Patent 1,269,280 discloses a catalyst prepared by dispersing sodium and / or lithium on a non-aqueous potassium compound. Also from Finland Patent Application No. 865363 according to the present invention is a solid
Reference is made to a catalyst in which sodium is thermally dispersed from a sodium-containing compound on the surface of K ₂ CO ₃ .

One of the drawbacks of these catalysts is that they are cumbersome to prepare and handle, their activity is relatively low at high temperatures, and their activity decreases rapidly due to tar and coking.

[Means for Solving the Problems] Compared to the above catalysts, the catalyst of the present invention is easier to treat the starting material, and moreover has the same activity as that of the alkali metal catalyst.

The catalyst of the present invention contains sodium oxide (Na ₂ O) on a potassium carbonate (K ₂ CO ₃ ) support.

The method for producing the catalyst of the present invention is characterized in that sodium oxide (Na ₂ O) and potassium carbonate (K ₂ CO ₃ ) are mixed.

The catalyst of the present invention used for the alkylation of toluene is characterized by a system containing sodium oxide (Na ₂ O) on a potassium carbonate (K ₂ CO ₃ ) support.

The catalyst of the present invention may be prepared by simply mixing sodium oxide and potassium carbonate and then heating the mixture. The heating temperature is 100 to 400 ° C, preferably 260 to 280 ° C, and the heating time is 0.5 to 1 hour. This heating is advantageously performed under reduced pressure, but it is not an absolute condition.

It is surprising that in the catalyst of the present invention, either sodium oxide or potassium carbonate alone does not show any catalytic activity. Further, according to the X-ray diffraction analysis of the final catalyst, both phases of sodium oxide and potassium carbonate are recognized, so that no chemical reaction occurs between sodium oxide and potassium carbonate.

The catalyst of the present invention was tested by the side chain alkylation reaction of toluene with propylene.

This alkylation reaction can be explained by the following reaction formula.

The main product obtained in this reaction is isobutylbenzene. 4-Methyl-1-pentene, which is n-butylbenzene and propylene dimer, is by-produced as a result of the side reaction.

The test was carried out in a 1 dm ³ continuous microreactor.

After the reaction, the gas and liquid phases were analyzed by gas chromatography.

[Examples] Next, the production method of the catalyst of the present invention and the alkylation reaction using the catalyst will be described by way of examples, but the present invention is not limited thereto.

Example Catalyst Preparation The catalyst was prepared in a 1 dm ³ Paar steel reactor at 270 ° C. under reduced pressure. A desired amount of sodium oxide and potassium carbonate was weighed and charged, and the mixture was sealed and the pressure was reduced. The mixture was heated to 260 ° C-280 ° C and held at that temperature for 0.5-1.0 hours.

Six catalysts were prepared, but their sodium content was 0-
The range was 100% by weight.

Analysis of Catalyst The finished catalyst is dark gray or brown. 14-90% by weight
A metal phase can be observed on the walls of the reactor during the production of the catalyst having a sodium oxide content of Among the finished catalysts, the catalyst containing 40% by weight of sodium oxide was analyzed by X-ray diffraction (MRD). The phases observed in the catalyst in this diffraction analysis are sodium oxide, sodium carbonate and possibly sodium metal. Sodium oxide has large crystals,
Its concentration is high. It can be seen from these low and broad peaks that potassium carbonate is either small crystals or coated with sodium oxide.

Catalyst Test The catalyst was tested in a reaction in which the side chain of toluene was alkylated with propylene. This test was carried out in a 1 dm ³ Parr autoclave and a continuous microreactor.

Test conditions in batch reactor The reaction conditions were selected as follows: reaction time t = 19 hours,
Reaction temperature T = 175 ° C., toluene / propylene molar ratio n
(T) n (P) = 0.7, catalyst mass m = 23.0 g The catalyst was charged into this reactor under a nitrogen atmosphere. The reactor was closed and a vacuum was applied. Toluene was charged using vacuum through a valve on the reactor lid. Propylene in liquid form was fed into the reactor.

After the reaction (175 ° C, 19 hours), the gas phase and the liquid phase were analyzed by gas chromatography.

Batch Test Results The main product obtained in this reaction was isobutylbenzene (IBB). In the reaction mixture obtained as a result of the side reaction was also n-butylbenzene (NBB), propylene dimer 4-methyl-1-pentene (4M1P), and 4-methyl-
It contained isomers of 1-pentene and various hexene isomers.

The test results are shown in Table 1. From the product composition, the conversion of starting materials, the selectivity of various product components, and the activity of the catalyst for IBB were calculated. FIG. 1 is a diagram in which the conversion rates of toluene and propylene to the product are plotted with respect to sodium oxide in the catalyst. Figure 2 shows the catalytic activity in g · IBB /
(g · Cat) shows the activity of the catalyst.

As can be seen from Table 1 and FIGS. 1-2, the conversion and activity in the reaction are highest when the sodium concentration is 60% by weight. But 20 or 40% by weight of sodium oxide
However, it turns out that the result is not so bad.

A comparison of the Na ₂ O / K ₂ CO ₃ catalyst with the 6% Na / K ₂ CO ₃ catalyst showed that the catalyst activity and conversion were significantly better with the 20, 40 and 60 wt% oxide catalysts. It was With the Na / K ₂ CO ₃ catalyst tested under the same conditions, the conversion of toluene was 30%, the conversion of propylene was 42%, and the catalytic activity was 4-5.
IBB / (g ・ Cat), whereas sodium oxide 20-60
The conversion of the catalyst containing wt% was 46-65% and 64-74%, and the catalyst activity was 5-7 · IBB / (g · Cat).

In addition, the oxide catalyst was easily activated and no induction period was observed. In other words, the reaction pressure began to drop immediately after the reaction temperature rose to 175 ° C. The alkali metal catalyst required about 1 hour to start the reaction.

A significant difference between the alkali metal catalyst and the oxide catalyst is the isomerization efficiency for 4-methyl-1-pentene in the latter case. The selectivity of 4-methyl-1-pentene isomerate formation is about twice that of alkali metal catalysts in the case of oxide catalysts. However, this isomerization reaction can be reduced by lowering the temperature and shortening the reaction time.

Continuous reaction test 40% Na ₂ O / for testing in continuous microreactor
K ₂ CO ₃ catalyst was chosen. The parameters of the test were as follows: Toluene feed rate about 9g / hr, Propylene feed rate about 20g / hr, reaction temperature 170 ° C, reaction pressure 90 bar, catalyst amount 26.
g.

Na ₂ O / K ₂ CO ₃ catalysts are considered particularly suitable for producing isobutylbenzene in a continuous reactor. The reason is NBB
This is because the generation of a heavier tar component is particularly small. In either case, the tar content does not increase with increasing temperature or the catalyst aging. Despite the fact that the Na ₂ O / K ₂ CO ₃ catalyst is close to a fine powder, there is no tar contamination of the catalyst, so no pressure loss is observed in the reactor. Therefore, the temperature in the reactor can be increased to 200 ° C. A disadvantage of Na ₂ O / K ₂ CO ₃ catalysts is their tendency to form 4-methyl-2-pentene as a dimerization product. This tendency of isomerization depends significantly on the reaction temperature. 150
When the temperature is lowered to ℃, the isomerization ratio becomes Na / K ₂
Reduces to close to that of CO ₃ catalysts.

[Brief description of drawings]

FIG. 1 is a graph showing the conversion rates of toluene and propylene with respect to the concentration of sodium oxide in the catalyst, and FIG. 2 is a graph showing the catalytic activity of isobutylbenzene with respect to various concentrations of sodium oxide in the catalyst.

Claims (9)

[Claims] 1. A toluene alkylation catalyst comprising sodium oxide (Na ₂ O) on a potassium carbonate (K ₂ CO ₃ ) support. 2. The catalyst according to claim 1, wherein the concentration of sodium oxide in the catalyst is 10 to 70%. 3. The catalyst according to claim 1, which has a sodium oxide concentration of 40 to 60%. 4. A process for producing a toluene alkylation catalyst containing sodium oxide (Na ₂ O) on a potassium carbonate (K ₂ CO ₃ ) carrier, the process comprising sodium oxide (Na ₂ O) and potassium carbonate (Na ₂ O). K
₂ CO ₃ ). 5. The method according to claim 4, wherein the concentration of sodium oxide in the catalyst is 10 to 70% by weight. 6. The method according to claim 4, wherein the concentration of sodium oxide in the catalyst is 40 to 60% by weight. 7. A catalyst according to claim 1 for use in the alkylation of toluene with propylene. 8. The catalyst according to claim 7, wherein the concentration of sodium oxide in the catalyst is 10 to 70%. 9. The catalyst according to claim 7, wherein the sodium oxide concentration in the catalyst is 40 to 60%.