JPH05154385A - Xylene isomerized catalyst and isomerized reaction process for xylene group - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a xylene isomerization catalyst which promotes only an isomerization reaction and a deethylation reaction with good selectivity at a low temperature of 400 ° C or lower, and a method for isomerizing xylenes. The present invention is a xylene isomerization catalyst, which is characterized in that crystalline manganese aluminosilicate is used as a carrier and platinum is supported on the carrier. Further, the present invention is a crystalline manganese aluminosilicate as a carrier, and platinum is used as the carrier. When performing an isomerization reaction of xylenes using a catalyst supporting, the temperature is in the range of 350 ° C to 400 ° C.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a catalyst for isomerizing xylenes containing ethylbenzene and a method for isomerizing xylenes.

[0002]

BACKGROUND ART As is well known, xylenes produced by catalytic reforming of heavy naphtha, thermal decomposition of naphtha, carbonization of coal, etc. are produced as a mixture of ethylbenzene, paraxylene, metaxylene and orthoxylene. Of these, the demand for paraxylene is particularly high, and it is necessary to separate paraxylene from xylenes by an adsorption method or a crystallization method and then isomerize other xylenes to paraxylene. The xylene isomerization catalyst has a history of research of more than 30 years since it was first industrialized in 1955 by ICI in the world for the first time in the world. Initially, a silica / alumina-based solid acid catalyst was used in a steam atmosphere. After that, the reaction was carried out in a hydrogen stream, and the catalyst life was remarkably improved. Although silica-alumina was mainly used as the catalyst, the conversion of ethylbenzene differs depending on the presence or absence of platinum, and when platinum is present, ethylbenzene is isomerized to xylene. Furthermore, Mobil is ZSM-
Against the background of the invention of a new zeolite called 5 as shown in Japanese Examined Patent Publication No. 53-41658, instead of the conventional method of isomerizing ethylbenzene, a new deethylation type isomerization of benzene production by deethylation reaction of ethylbenzene was conducted. Started to develop chemical catalysts.

[0003]

A problem involved in the isomerization reaction of xylenes with a deethyl isomerization catalyst is suppression of side reactions. That is, the side reaction is roughly classified into a hydrogenolysis reaction and a disproportionation reaction of xylenes.
When a solid acid catalyst is used, the hydrocracking reaction easily occurs at higher temperatures, and paraffins, olefins, and naphthenes are formed, and xylenes are lost.

On the other hand, the disproportionation reaction is a reaction in which xylenes react with each other to form toluene or benzene and C9 aromatics or C10 aromatics. Similarly, when a solid acid catalyst is used, it tends to occur at higher temperatures, This causes a problem that the amount of para-xylene produced from xylenes decreases. Therefore, a catalyst that promotes only the isomerization reaction and the deethylation reaction at low temperature with good selectivity is required.

[0005]

As a result of intensive studies to solve these problems, the present inventors have found a catalyst that promotes only the isomerization reaction and the deethylation reaction with good selectivity at a low temperature of 400 ° C. or lower. It came to be developed.

That is, the xylene isomerization catalyst according to the present invention is characterized in that crystalline manganese aluminosilicate is used as a carrier and platinum is supported on the carrier. Moreover, the isomerization reaction method of xylenes according to the present invention uses a crystalline manganese aluminosilicate as a carrier, and when carrying out an isomerization reaction of xylenes using a catalyst supporting platinum thereon, the temperature is 350 ° C to 400 ° C. The range is set to.

Crystalline manganese aluminosilicate is used as the carrier of the catalyst according to the present invention. The crystalline manganese aluminosilicate as used herein means a crystalline substance which shows the same or similar pattern as the pentasil-type zeolite represented by ZSM-5 in the powder X-ray diffraction method, and the crystalline aluminosilicate aluminum and / or silicon. Means a crystallized substance in which a part of is replaced with manganese.

In crystalline manganese aluminosilicate, the composition of the reaction product varies depending on the composition ratio of the catalyst carrier, that is, the SiO ₂ / Mn ₂ O ₃ molar ratio and the SiO ₂ / Al ₂ O ₃ molar ratio. For example, in the case of crystalline aluminosilicate,
Since the carrier acidity changes depending on the SiO ₂ / Al ₂ O ₃ molar ratio, the composition of the reaction product changes. When the SiO ₂ / Al ₂ O ₃ molar ratio is high, the acid catalysis by the carbonium ion mechanism is reduced. That is, the light paraffin produced by the decomposition reaction and the heavy aromatic content produced by the disproportionation reaction are reduced. However, on the contrary, when the acidic catalytic function is lowered, the target isomerization reaction and deethylation reaction rate are also lowered. Also, the lower the acidity, the less coke is produced and the longer the catalyst life. Therefore, in consideration of these, the SiO ₂ / Al ₂ O ₃ molar ratio is preferably 40 to 1000, and more preferably 60.
~ 600.

When a part of aluminum and / or silicon of the crystalline aluminosilicate is replaced with manganese,
As the acidity changes, as a more preferable property,
The disproportionation reaction and the hydrogenolysis reaction of side reactions are significantly suppressed. The xylene isomerization capacity is also improved, and para-xylene is produced above the thermodynamic equilibrium value. The reason why the catalytic performance is improved in this way is not clear, but the size of the aluminum ion and the manganese ion and the electrical characteristics are different depending on whether the Bronsted acid point generated in the crystal is near aluminum or manganese. It is estimated that one of the reasons is that the acid strength changes due to the difference in the degree of negativeness. It is also presumed that the difference in the size of the ions physically changes the size and shape of the pores in the crystal. The properties of manganese ion, including acidity and size of pores in crystals, are considered to be more suitable for this reaction. The content of manganese ions is 25 to 1000, and more preferably 50 to 500, in terms of SiO ₂ / Mn ₂ O ₃ molar ratio.

Even when these crystalline manganese aluminosilicates are used alone as catalysts for isomerization, the disproportionation reaction is not sufficiently suppressed as shown in Comparative Examples, and benzene and toluene are reacted by the reaction of ethylbenzene and xylene. , C9 aromatics and C10 aromatics are produced, and the loss of xylene is large. Moreover, the deethylation reaction of ethylbenzene is not sufficient and there are many disproportionation reactions.

When platinum having hydrogenation ability is supported on these crystalline manganese aluminosilicates, it becomes possible to suppress disproportionation activity and to cause isomerization reaction and deethylation reaction of ethylbenzene. Incidentally, in the case of platinum-supported crystalline aluminosilicate which is a conventional deethylation type isomerization catalyst, the deethylation activity is high, the ethylbenzene conversion rate is high, the benzene yield is also high, but since the xylene disproportionation activity is still high, High yield of toluene and C9 aromatics,
Large loss of xylene. Platinum-supported crystalline manganese aluminosilicate has much higher deethylation activity than conventional catalysts and low side reaction disproportionation activity. If the hydrogenation capacity is too high, the loss of xylene tends to increase due to the hydrogenation reaction or the hydrogenolysis reaction, so platinum is particularly suitable among the metals of Group VIII of the Periodic Table. .. The supported amount is 0.01 to 1.0 wt%, and a particularly preferable range is
It is 0.05 to 0.5 wt%.

There are various methods for synthesizing crystalline manganese aluminosilicate, for example, Catalyst magazine Vol.
No. 232 (1981), the method for synthesizing ZSM-5 can be used. In this method, the alkylammonium salt called template is tetrapropylammonium bromide, but primary to tertiary amines can also be used, and crystalline manganese aluminosilicate having the same crystal structure can be synthesized. Further, the synthesis of these crystalline manganese alumina silicates can be carried out in a shorter time by the rapid crystallization method shown in the 8th World Conference on Catalysis, Volume 3, Page 569. As the manganese raw material, various water-soluble manganese salts can be used, and examples thereof include manganese chloride, manganese sulfate, manganese nitrate, manganese acetate, and manganese phosphate.
As a method for supporting platinum, a usual ion exchange method or a dipping method is used.

The reaction conditions can be such that the yield of paraxin is high and the amount of ethylbenzene is low. In this catalyst system, isomerization of xylene does not proceed at a temperature of 350 ° C. or lower, the yield of para-xylene is low, and the conversion rate of ethylbenzene is low. When the temperature exceeds 400 ° C., the xylene isomerization reaction proceeds, but along with this, the disproportionation reaction increases, the xylene loss increases, and the final para-xylene yield decreases. The conversion rate of ethylbenzene increases with temperature, and the benzene yield increases accordingly. Therefore, the optimum temperature condition changes a little with the economic change due to the price change of the product, but since the target product is paraxylene, the range of 350 ° C to 400 ° C at which the paraxylene yield is maximum is preferable. Although pressure has little effect on this reaction,
The higher the pressure, the longer the catalyst life, so it is determined by the required catalyst life. Further, the higher the pressure, the higher the operating cost, so the range of 5 to 20 kg / cm ² G is preferable. LH
An SV of 2 to 10 hr ^-1 and a hydrogen ratio of 2 to 5 mol / mol are suitable.

EXAMPLES The present invention will be described in more detail with reference to Examples below.
The present invention is not limited to the embodiments without departing from the spirit of the present invention.

Example 1 Crystalline manganese aluminosilicate was synthesized as follows. 180 g of ion-exchanged water, 6.5 g of aluminum sulfate, 5.7 g of manganese nitrate, 18.6 g of sulfuric acid, and 22.6 g of tetrapropylammonium bromide are mixed to prepare a solution A. Ion-exchanged water 133 g and water glass (JIS No. 3) 207 g are mixed to prepare a solution B. Deionized water (313 g) and sodium chloride (78.8 g) are mixed to prepare a solution C. The solutions A and B are placed in a dropping funnel and added dropwise to the solution C with vigorous stirring for 30 minutes. This mixed solution is put into a stainless steel 1 liter autoclave and reacted at 160 ° C. for 48 hours. After the reaction, the product is separated by filtration and washed with ion-exchanged water until the pH of the filtrate reaches 8. After washing, dry at 110 ° C for 16 hours, then at 530 ° C for 3 hours
Bake for hours. After calcination, 50 g of crystalline manganese aluminosilicate is immersed in 300 ml of a 1N ammonium chloride aqueous solution to make it into a proton form and kept at 80 ° C. for 8 hours, then the solution is exchanged and this is repeated 4 times. After separating the solution 110
Dry at 16 ° C for 16 hours and bake at 530 ° C for 3 hours.

10 g of the protonated crystalline manganese aluminosilicate was immersed in 30 ml of ion-exchanged water, and 0.13 g of chloroplatinic acid was dissolved in the solution while stirring.
Add ml dropwise. The mixture was gently stirred for about 20 hours to allow the platinum salt to be sufficiently adsorbed on the crystalline manganese aluminosilicate, then evaporated to dryness and dried at 110 ° C for 5 hours, then 530
Bake at ℃ for 3 hours. This is designated as catalyst A. The powder X-ray diffraction pattern of catalyst A was the same as that of ZSM-5. Catalyst A SiO ₂
/ Mn ₂ O ₃ molar ratio is 100, SiO ₂ / Al ₂ O ₃ molar ratio is 100, and platinum loading is 0.5 wt%.

Example 2 3.2 g, 1.6 g of aluminum sulfate in the solution A of Example 1
Other operations are performed in exactly the same way, except for 1.1g. Let these be catalysts B, C, and D, respectively. Catalyst B, C, D
Is SiO ₂ / Al in crystalline manganese aluminosilicate
_{The 2} O ₃ molar ratio is 200, 400, 600.

Example 3 Other operations are exactly the same except that the amount of manganese nitrate in the solution A of Example 1 is 2.9 g and the amount of aluminum sulfate is 1.6 g. Let these be catalyst E, respectively. Catalyst E SiO ₂
/ Mn ₂ O ₃ molar ratio is 200, SiO ₂ / Al ₂ O ₃ molar ratio is 400, and platinum loading is 0.5 wt%.

Comparative Example 1 A catalyst a1 is the same as that of Example 1 except that platinum is not supported.

Comparative Example 2 The catalyst a2 was the same as in Example 1 except that manganese nitrate was not mixed.

Example 4 and Comparative Example 3 Using xylene for isomerization with less paraxylene, reaction temperature 380 ° C., pressure 8 kg / cm ² G, LHSV 2.0 hr ⁻¹ , hydrogen ratio 3
Table 1 shows the results of the reaction under the mol / mol condition.

[0022]

[Table 1]

In the catalysts A, B, C, D and E, ethylbenzene is reduced and benzene is produced, and the isomerization reaction of xylene also proceeds, but it is understood that xylene loss is small. Catalyst a
In No. 1, the isomerization reaction and the disproportionation reaction are the main reactions, and the loss of xylene is large. The catalyst a2 has a reduced disproportionation reaction, but has a low paraxylene yield.

[0024]

EFFECTS OF THE INVENTION When the catalyst according to the present invention is used, the disproportionation reaction and hydrogenolysis reaction of xylene are suppressed, and only the isomerization reaction of xylene to para-xylene proceeds selectively. As a result, para-xylene can be obtained in a high yield at a lower reaction temperature than conventional catalysts. Further, since xylene loss is small, the xylene fraction can be effectively used by circulating the raw material after the separation of para-xylene.

Claims (5)

[Claims] 1. A xylene isomerization catalyst comprising crystalline manganese aluminosilicate as a carrier and platinum supported thereon. 2. The xylene isomerization catalyst according to claim 1, wherein the amount of platinum supported is 0.01 to 1.0 wt%. 3. The ratio of silica to manganese oxide is SiO ₂ / Mn.
The xylene isomerization catalyst according to claim 1 or 2, wherein the ₂ O ₃ molar ratio is 25 to 1000. 4. The ratio of silica to alumina is SiO ₂ / Al ₂ O.
The xylene isomerization catalyst according to claim 1, 2 or 3, wherein the ₃ molar ratio is 40 to 1000. 5. When carrying out the isomerization reaction of xylenes using a catalyst having platinum supported on crystalline manganese aluminosilicate as a carrier, the temperature is 350 ° C. to 400 ° C.
Of isomerization reaction of xylenes characterized in that