JP3241424B2 - Xylene isomerization catalyst and xylene isomerization reaction method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for isomerizing xylenes containing ethylbenzene and a method for isomerizing xylenes.

[0002]

2. Description of the Related Art As is well known, xylenes produced by catalytic reforming of heavy naphtha, pyrolysis of naphtha, carbonization of coal, etc. are produced as a mixture of ethylbenzene, para-xylene, meta-xylene and ortho-xylene. Of these, para-xylene is particularly popular, and it is necessary to separate para-xylene from xylenes by an adsorption method or a crystallization method and then to isomerize other xylenes to para-xylene. The xylene isomerization catalyst has a history of research of more than 30 years since it was first industrialized in 1955 by ICI, UK. Initially, a silica-alumina solid acid catalyst was used in a steam atmosphere. Thereafter, the reaction was carried out in a hydrogen stream, and the catalyst life was remarkably improved. Silica-alumina was mainly used as a catalyst, but the conversion of ethylbenzene differs depending on the presence or absence of platinum. When platinum is present, ethylbenzene is isomerized to xylene. Mobil is also ZSM-
Against the background of the invention of a new zeolite called No. 5, as shown in JP-B-53-41658, it is not a method of isomerizing ethylbenzene, but a new deethylated isomerization method called benzene production by deethylation of ethylbenzene. Began developing catalysts.

[0003]

A problem involved in the isomerization reaction of xylenes with a deethylation-type isomerization catalyst is suppression of side reactions. That is, the side reactions are roughly classified into a hydrogenolysis reaction of xylenes and a disproportionation reaction.
In the case of using a solid acid catalyst, the hydrocracking reaction is more likely to occur at higher temperatures, producing paraffins, olefins, and naphthenes, resulting in loss of xylenes.

[0004] On the other hand, the disproportionation reaction is a reaction in which xylenes are reacted to form toluene or benzene with C9 aromatic or C10 aromatic. Similarly, when a solid acid catalyst is used, it tends to occur at higher temperatures, There is a problem that the amount of para-xylene produced from xylenes is reduced. Therefore, a catalyst that promotes only isomerization reaction and deethylation reaction at low temperature with good selectivity is required.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve these problems, and as a result, have found a catalyst which promotes only isomerization reaction and deethylation reaction at a low temperature of 400 ° C. or less with good selectivity. It has been developed.

That is, the xylene isomerization catalyst according to the present invention is characterized in that a crystalline manganese aluminosilicate is used as a carrier, and platinum and one kind of a metal of Group IIA of the periodic table are supported on the carrier. Further, the method for isomerizing xylenes according to the present invention comprises the step of carrying out the isomerization reaction of xylenes using a crystalline manganese aluminosilicate as a carrier, and using platinum and a catalyst supporting one kind of Group IIA metal of the periodic table. In carrying out the process, the temperature is set in a range of 350 ° C to 400 ° C.

[0007] A crystalline manganese aluminosilicate is used as a carrier of the catalyst according to the present invention. The crystalline manganese aluminosilicate referred to herein means a crystalline material which shows the same or similar pattern as a pentasil-type zeolite represented by ZSM-5 in a powder X-ray diffraction method, and includes aluminum and / or silicon of a crystalline aluminosilicate. Means a crystal in which a part of is replaced by manganese.

In the case of crystalline manganese aluminosilicate, the composition of the reaction product changes depending on the composition ratio of the catalyst support, that is, the molar ratio of SiO ₂ / Mn ₂ O _{3 and the} molar ratio of SiO ₂ / Al ₂ O ₃ . 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 acidic catalysis by the carbonium ion mechanism decreases. That is, the light paraffin is reduced by the decomposition reaction, and the heavy aromatic component is reduced by the disproportionation reaction. However, when the acidic catalyst function is reduced, there arises a problem that the intended isomerization reaction and deethylation reaction rates are also reduced. 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, more preferably 60 to 1000.
600.

When a part of aluminum and / or silicon of the crystalline aluminosilicate is replaced by manganese,
As the acidity changes, as more preferable properties,
Disproportionation reaction and hydrocracking reaction of side reactions are remarkably suppressed. The xylene isomerization ability is also improved, and para-xylene is formed above the thermodynamic equilibrium value. It is not clear why the catalyst performance is improved in this way, but the size and electrical properties of aluminum and manganese ions are different between when the Bronsted acid sites generated in the crystal are near aluminum and when they are near manganese. It is presumed that one of the reasons is that the acid strength changes due to the difference in negativity. It is also assumed 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 ions, including the acidity and the size of the pores in the crystal, are considered to be more suitable for this reaction. However, if the manganese ion content is excessively increased, on the contrary, the isomerization ability and the deethylation ability decrease, so that an appropriate amount exists. Moderate manganese ion content is SiO ₂
/ Mn ₂ O ₃ molar ratio of 25 to 1000, more preferably 50
~ 500.

When these crystalline manganese aluminosilicates are used alone as isomerization catalysts, the disproportionation reaction is still large, and benzene, toluene, C9 aromatics and C10 aromatics are formed by the reaction of ethylbenzene and xylene. Large loss of xylene. In addition, 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 is possible to suppress disproportionation activity to some extent and to cause isomerization reaction and deethylation reaction of ethylbenzene. However, it is necessary to further suppress the disproportionation activity in order to further increase the economic efficiency.

The crystalline manganese aluminosilicate supported on platinum and Group IIA metal of the Periodic Table has lower isomerization activity and lower disproportionation activity for side reactions than platinum-supported crystalline manganese aluminosilicate catalyst, A catalyst with improved economy. All Group VIII metals of the periodic table have the ability to activate hydrogen, but if the hydrogenation ability is too high, the loss of xylenes tends to increase due to the hydrogenation reaction or hydrogenolysis reaction, and if it is too low, The supported amount increases and the activity is suppressed or another side reaction occurs. Therefore, platinum having an appropriate hydrogenation ability is particularly preferable among the Group VIII metals of the periodic table. The supported amount is 0.01 to 1.0 wt%, and a particularly preferred range is 0.025 to 0.25 wt%.

[0013] Group IIA metals of the periodic table include beryllium, magnesium, calcium, strontium, barium,
There is radium, but magnesium, calcium, strontium and barium are suitable. Magnesium is particularly preferred. The reason why the disproportionation reaction is suppressed by carrying them is not clear, but it is presumed that the acid point causing the disproportionation reaction is appropriately modified. When the amount of Group IIA metal carried in the periodic table is 0.1 wt% or less, the effect of suppressing the disproportionation reaction is not so remarkable, and when it is 2.0 wt% or more, not only the disproportionation reaction but also the isomerization activity and deethylation activity are performed. 0.1 to 2.0 wt% is preferable, and a particularly preferable range is 0.5 to 1.
5 wt%.

There are various methods for synthesizing crystalline manganese aluminosilicate.
No. 232, page 1981 (1981). In this method, the alkylammonium salt called a template is tetrapropylammonium bromide, but primary to tertiary amines can also be used, and a crystalline manganese aluminosilicate having the same crystal structure can be synthesized. In addition, the synthesis of these crystalline manganese alumina silicates can be carried out in a short time by the rapid crystallization method shown in the proceedings of the 8th World Catalyst Conference, Vol. 3, p. 569. As a method for supporting platinum, a usual ion exchange method or immersion method is used. An ordinary immersion method is also used as a method for supporting a Group IIA metal of the periodic table.

The reaction conditions are such that the yield of paraxin is high and the amount of ethylbenzene is low. In the present catalyst system, the isomerization of xylene does not proceed at a temperature of 350 ° C. or lower, the para-xylene yield is low, and the conversion of ethylbenzene is low. At a temperature higher than 400 ° C., the xylene isomerization reaction proceeds, but the disproportionation reaction increases and the xylene loss increases, and the final para-xylene yield decreases. The conversion of ethylbenzene increases with temperature, and the benzene yield increases with it. Therefore, the optimum temperature condition slightly changes with the change in economy due to the price fluctuation of the product, but since the target product is para-xylene, the range of 350 ° C. to 400 ° C. at which the para-xylene yield is maximized is preferable. Pressure has little effect on the reaction,
The higher the pressure is, the longer the catalyst life is, so it is determined by the required catalyst life. Since the operating cost increases as the pressure increases, the range of 5 to ²⁰ kg / cm ² G is preferable.
It is appropriate that the LHSV is 2 to 10 hr ^-1 and the hydrogen ratio is 2 to 5 mol / mol.

[0016]

The present invention will be described in more detail with reference to the following Examples, which should not be construed as limiting the scope of the present invention.

[0017]

Example 1 A 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 and 22.6 g of trapropylammonium bromide are mixed to prepare a solution A. 133 g of ion-exchanged water and 207 g of water glass (JIS No. 3) are mixed to obtain a solution B. A solution C is prepared by mixing 313 g of ion-exchanged water and 78.8 g of sodium chloride. Each of the solutions A and B is placed in a dropping funnel and dropped into the solution C with vigorous stirring over 30 minutes. This mixed solution is placed in a 1-liter stainless steel autoclave and reacted at 160 ° C. for 48 hours. After the reaction, the product is filtered and washed with ion exchanged water until the pH of the filtrate is 8. After washing, it is dried at 110 ° C. for 16 hours and baked at 530 ° C. for 3 hours. 50 g of the crystalline manganese aluminosilicate after calcination is immersed in 300 ml of a 1 N aqueous solution of ammonium chloride in order to make it into a proton type, kept at 80 ° C. for 8 hours, exchanged with the same solution, and repeated four times. The solution is filtered, dried at 110 ° C. for 16 hours, and calcined at 530 ° C. for 3 hours.

10 g of the protonated crystalline manganese aluminosilicate is immersed in 30 ml of ion-exchanged water, and 10 ml of an aqueous solution in which 0.026 g of chloroplatinic acid is dissolved is added dropwise with stirring. The mixture is gently stirred for about 20 hours, and the platinum salt is sufficiently adsorbed on the crystalline manganese aluminosilicate, evaporated to dryness, dried at 110 ° C. for 5 hours, and then calcined at 530 ° C. for 3 hours. 5 g of the platinum-supported crystalline manganese aluminosilicate is added to 20 parts of ion-exchanged water.
Then, 10 ml of an aqueous solution having 0.8 g of magnesium lactate dissolved therein is added dropwise with stirring. The mixture was gently stirred for about 20 hours, and the magnesium salt was sufficiently adsorbed on the crystalline manganese aluminosilicate carrying platinum, evaporated to dryness, dried at 110 ° C. for 5 hours, and then 530
C. 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. SiO _{2 of} catalyst A
The / Mn ₂ O ₃ molar ratio was 100, the SiO ₂ / Al ₂ O ₃ molar ratio was 100, and the amount of supported platinum was 0.1 wt%. The amount of magnesium carried is 1.5 wt%.

[0019]

Example 2 0.27 g of magnesium lactate of Example 1
Other operations are performed in exactly the same manner, except that This is designated as catalyst B. Catalyst B has a magnesium loading of 0.5 wt.
%.

[0020]

Example 3 Other operations were carried out in exactly the same manner except that the amount of aluminum sulfate in solution A of Example 1 was changed to 3.2 g. This is designated as catalyst C. Catalyst C had a SiO ₂ / Al ₂ O ₃ molar ratio of 200 in crystalline manganese aluminosilicate.
It is.

[0021]

Example 4 Manganese nitrate in solution A of Example 1 was changed to 2.
Other operations are carried out in exactly the same way, except that 9 g and aluminum sulfate were changed to 1.6 g. These are referred to as catalysts D, respectively. Catalyst D in crystalline manganese aluminosilicate
The SiO ₂ / Mn ₂ O ₃ molar ratio is 200, and the SiO ₂ / Al ₂ O ₃ molar ratio is 400.

[0022]

Example 5 Other operations were carried out in exactly the same manner as in Example 1, except that instead of 0.8 g of magnesium lactate, 0.22 g of calcium acetate, 0.12 g of strontium acetate and 0.09 g of barium acetate were used. These are called catalysts E, F,
G. Catalysts E, F, and G each have a calcium, strontium, and barium loading of 1.0 wt%.

[0023]

Comparative Example 1 A catalyst obtained by performing the same operation in Example 1 except that magnesium was not supported is referred to as a catalyst a.

[0024]

Example 6 and Comparative Example 2 Using xylene for isomerization with little para-xylene, a reaction temperature of 380 ° C. and a pressure of 8 kg / cm.
Table 1 shows the results of the reaction under the conditions of ² G, LHSV of 2.0 hr ^-1 and a hydrogen ratio of 3 mol / mol.

[0025]

[Table 1]

In the catalysts A, B, C, D, E and F, the amount of ethylbenzene decreases to generate benzene, and the xylene isomerization reaction proceeds, but the loss of xylene is small. Catalyst a has higher disproportionation activity than catalyst A and a large loss of xylene.

[0027]

When the catalyst according to the present invention is used, the disproportionation reaction and the 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 higher yield at a lower reaction temperature than the conventional catalyst. Further, since the xylene loss is small, the xylene fraction can be effectively used by circulating the raw material after para-xylene separation.

Claims (7)

(57) [Claims] 1. A xylene isomerization catalyst comprising: a support made of crystalline manganese aluminosilicate; and platinum and one of metals of Group IIA of the periodic table supported thereon. 2. The amount of supported platinum is 0.01 to 1.0 wt%.
The xylene isomerization catalyst according to claim 1, wherein 3. The xylene isomerization catalyst according to claim 1, wherein the amount of Group IIA metal supported in the periodic table is 0.1 to 2.0 wt%. 4. The xylene isomerization catalyst according to claim 1, wherein the metal of Group IIA of the periodic table is magnesium. 5. The method according to claim 1, wherein the ratio of silica to manganese oxide is SiO ₂ / Mn.
₂ O ₃ molar ratio of xylene isomerization catalyst according to claim 1, characterized in that it is 25 to 1000. 6. A silica / alumina ratio of SiO ₂ / Al ₂ O
The xylene isomerization catalyst according to any one of claims 1 to 5, wherein the molar ratio is _{3 to} 40 to 1000. 7. A temperature of 350 ° C. to 400 ° C. when performing an isomerization reaction of xylenes using a crystalline manganese aluminosilicate as a carrier and a catalyst carrying platinum and one kind of a metal of Group IIA of the periodic table. Isomerization reaction method for xylenes, wherein