JPH06228017A - Conversion of light hydrocarbon - Google Patents

Abstract

PURPOSE:To convert light hydrocarbons composed mainly of paraffin into lower olefins and monocyclic aromatic hydrocarbons in high yield. CONSTITUTION:A light hydrocarbon is subjected to catalytic cracking using a catalyst consisting of a zeolite selected from ZSM-5 zeolites and ZSM-11 zeolite and having an SiO2/Al2O3 ratio of 50-150.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a light hydrocarbon mainly composed of paraffin, typically naphtha as a raw material, and a product useful as a chemical basic raw material, that is, lower olefins, particularly ethylene, propylene, and , A monocyclic aromatic hydrocarbon (aroma), particularly benzene, toluene, and xylene in high yield.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 60-222428 discloses a method of using a proton type ZSM-5 as a catalyst in Japanese Unexamined Patent Publication No. 61-7.
Japanese Patent No. 218 discloses a method in which zeolite (AZ-1) showing a unique X-ray diffraction pattern is used as a catalyst. In the former method, when naphtha is used as a raw material, the yield of monocyclic aromatic hydrocarbons is high, but the olefin yield is low.
The latter method, when the naphtha starting material, ethylene, propylene, C ₆ -C ₈ product yield total low consisting aroma.

Japanese Unexamined Patent Publication (Kokai) No. 3-130236 discloses a method in which a catalyst having a specific medium pore size zeolite is used, which has a desorption amount of pyridine at 500 to 900 ° C. of 40 to 180 μmol / g-zeolite by the temperature programmed desorption method. It is disclosed. This method is carried out in the presence of nitrogen or water vapor, and when naphtha is used as the raw material, the C _{6 to} C ₈ aroma yield is low.

Japanese Patent Laid-Open No. 1-213240 discloses an α value of 5 to 5.
Methods of using 25 ZSM-5 or ZSM-11 zeolites are disclosed. The α value is defined as a relative rate constant based on the conversion rate of normal hexane per unit catalyst in a unit time, and the test method for obtaining the α value is the Journal of Catalysis.
s 61 (390-396) 1980. From FIG. 2 of this document, α value and SiO ₂ / Al
The relationship with the ₂ O ₃ ratio can be determined, and based on this,
The α value of 5 to 25 corresponds to a SiO ₂ / Al ₂ O ₃ ratio of approximately 1960 to 390. In addition, JP-A 1-213
In the embodiment of the 240 publication, a value obtained by dividing 1 as the weight hourly space velocity (WHSV) is adopted.

Japanese Unexamined Patent Publication Nos. 2-1413 and 2-18
Japanese Patent No. 4638 discloses a method of using a catalyst in which copper, cobalt, silver or phosphorus is supported on a zeolite such as ZSM-5, offretite-erionite or Y. In an embodiment of the method, helium is used as the diluent gas to carry out the pulse reaction.

[0006]

[Problems to be Solved by the Invention] A light hydrocarbon mainly composed of paraffins having 2 to 12 carbon atoms, particularly naphtha is used as a raw material, and a product useful as a chemical basic raw material, that is, ethylene, propylene, aroma (benzene , Toluene, xylene) has not been established yet.

The term "high yield" as used herein means a value such that each yield of ethylene, propylene and aroma is 20 wt% or more and the total yield thereof is 60 wt% or more based on the raw material. The object of the present invention is to overcome the problems of the prior art,
It is an object of the present invention to provide a catalytic cracking method for efficiently producing ethylene, propylene, and aroma in a high yield by using paraffin-based light hydrocarbons, particularly naphtha as a raw material.

[0008]

Means for Solving the Problems The inventors of the present invention have earnestly studied a method for achieving the above object. as a result,
Z having an SiO ₂ / Al ₂ O ₃ ratio in the range of 50 to 150
The present invention has been completed by using a specific zeolite such as SM-5 or ZSM-11 as a catalytic cracking catalyst.

That is, according to the present invention, a light hydrocarbon raw material mainly composed of paraffin having 2 to 12 carbon atoms is converted into SiO ₂ /
ZSM-5s having an Al ₂ O ₃ ratio of 50 to 150 or Z
A catalyst containing SM-11 is brought into contact with the catalyst at a temperature of 600 to 750 ° C. under a weight hourly space velocity (WHSV) of 1 to 200 / hour to obtain a lower olefin containing ethylene and propylene as a main component and benzene, toluene and xylene. The present invention provides a method for obtaining a monocyclic aromatic hydrocarbon (aroma) containing as a main component in a high yield. The lower olefin mentioned here includes butene, pentene and hexene in addition to ethylene and propylene. The monocyclic aromatic hydrocarbons include ethylbenzene and styrene in addition to benzene, toluene and xylene.

The light hydrocarbon feedstock which can be used in the method of the present invention is generally composed of paraffins having 2 to 12 carbon atoms.
There is no particular limitation as long as it contains 0% by weight or more. Examples of this include light naphtha, heavy naphtha, straight run naphtha, FCC gasoline, coker gasoline, and pyrolysis gasoline. The catalyst used in the present invention is ZSM-5 or ZS-5.
Although it is M-11, ZSM-5s and ZSM-11 may be mixed and used.

The ZSM-5s referred to in the present invention are zeolites whose X-ray diffraction pattern contains at least the peaks of the interplanar distances shown in Table 1. The peak in Table 1 is ZSM-5.
ZSM-5, which is a diffraction peak peculiar to the class, and which is the object of the present invention even if the other peaks are slightly different from each other.
Included in the category. Examples of ZSM-5s included in the present invention include ZSM-5 (US Pat. No. 3,702,886),
ZSM-8 (German Patent 2049755), ZETA
-1 (German Patent No. 2548697), ZETA-3
(British Patent No. 1553209), NU-4 (German Patent No. 3268503), NU-5 (German Patent No. 31696).
06), TZ-01 (US Pat. No. 4,581,216),
Crystalline aluminosilica
te (US Pat. No. 4,954,326), TRS (German Patent 2924870), MB-28 (European Patent 2144).
5), TSZ (JP-A-58-45111), and the like. ZSM-8, ZETA-1, NU-4, NU
For -5, TZ-01, TSZ, etc., the main peak of the interplanar distance d = 3.85 ± 0.07 shown in Table 1 is described as a double peak, but such a zeolite also has the present invention. Included in the catalyst used in.

The ZSM-11 referred to in the present invention is the zeolite described in JP-B-53-23280. The zeolite used in the present invention may contain various elements by ion exchange, impregnation, or other methods, but it is preferred to use hydrogen type zeolite. As an example of preparation of the hydrogen type zeolite, the calcined zeolite is ion-exchanged with ammonium ions, and the ammonium-exchanged zeolite is calcined under conditions sufficient to release ammonium.

Zeolite SiO ₂ applicable to the present invention
The / Al ₂ O ₃ ratio is 50 to 150. This ratio is 50
If it is less than 100, the olefin yield is low, and
If it exceeds the range, the catalytic activity is insufficient. SiO ₂ /
ZSM-5 or ZSM- having an Al ₂ O ₃ ratio of 50 to 150
11 is a method of direct synthesis and a SiO ₂ / Al ₂ O ₃ ratio of 5
There is a method of dealumination of zero or less zeolite. As a method for dealumination, a method of hydrothermal treatment, a method of immersing in a mineral acid such as hydrochloric acid or nitric acid and applying heat,
There is a method of treating with a silicon compound.

Regarding the hydrothermal treatment, the ammonium ion type zeolite or the proton type zeolite obtained by calcining the same is calcined at 500 ° C. or higher in the presence of steam, or
Alternatively, even by simply firing in air or nitrogen, the hydrothermal treatment is performed by the adsorbed moisture. Aluminum is released from the skeleton of the zeolite crystal by the hydrothermal treatment, and a part of this is present in the ion exchange site as a cation, but can be removed from the zeolite by ion exchange with ammonium ion. Further, the place where aluminum is desorbed is filled with four silanol groups (Si-OH), and when these hydroxyl groups react with silica, Al and Si are replaced with each other and become stable. The high-silica zeolite having a low aluminum concentration prepared in this manner has excellent hydrothermal stability.

For the treatment with mineral acid, ZSM-5
Since ZSM-11 has excellent acid resistance, hydrochloric acid,
Even if it is boiled with a mineral acid such as nitric acid, the crystal structure does not break,
Aluminum in the crystal lattice is eluted and dealumination occurs. After elimination of aluminum, it is filled with four silanol groups, and further hydroxyl groups react with silica to stabilize. The dealumination concentration can be adjusted by the type and concentration of the mineral acid, the treatment temperature and the time.

Further, aluminum in the zeolite skeleton can be replaced with silicon by treating with a silicon compound. In the above-mentioned two methods, lattice defects are likely to occur after dealumination, but this method is different in that the crystal structure is completely maintained. When the zeolite according to the present invention is used as a catalyst, it may be used as a spherical, columnar or granular shaped body. Zeolite crystals have no binding property by themselves, so it is necessary to add a binder for molding. Usually, a porous matrix of a refractory inorganic oxide, for example, alumina, silica, silica-alumina, zirconia, titania, diatomaceous earth, clay or the like is mixed and molded as a matrix or a binder. This molding process improves the mechanical strength when used,
The activity per unit weight of the catalyst is lowered by the amount of the added matrix and binder.

The conditions for carrying out the present invention are 600 to 750.
℃ temperature, weight hourly space velocity of ¹ ~ 200hr ^-1 (WH
SV), a pressure of 0.1~30kg / cm ^2, preferably, the temperature of six hundred and fifty to seven hundred and twenty ° C., a weight hourly space velocity of 5~150hr ^{over 1} (WHSV), atmospheric pressure is employed. The weight hourly space velocity can be obtained by the feed rate of the raw material per catalyst weight, but the catalyst unit weight here means only the zeolite unit weight, and when a porous matrix is used as the matrix or binder, these Ignore the weight of.

The appropriate value of the weight hourly space velocity varies depending on the reactor shape and reactor size even if the catalyst is the same. When a fluidized bed is adopted as the reactor system, in general,
As the reactor size increases, the contact efficiency between the hydrocarbon raw material and the catalyst tends to increase, so that the weight hourly space velocity can be increased to obtain the same catalyst activity.

Since each condition does not take an appropriate value individually but is related to each other, the preferable range may change, but the point is that ethylene, propylene, The processing conditions can be selected such that each yield of aroma is 20% by weight or more and the total yield thereof is 60% by weight or more. Under the reaction temperature of less than 600 ° C, the yields of ethylene and propylene are low and 750 ° C.
Under the condition of exceeding, deterioration of the catalyst progresses due to coke precipitation and the yield of propylene and aroma becomes low. Further, even under the condition of the weight hourly space velocity less than 1, the yield of ethylene, propylene and aroma is low because the deterioration of the catalyst due to the coke precipitation progresses, and the conversion rate becomes lower under the condition of more than 200.

In practice, the raw material may be diluted with an inert gas such as nitrogen or helius, but it is possible to separate and remove these inert gases from the product obtained.
It becomes impractical with energy loss. Rather, it is also a feature of the present invention that an effective product can be obtained in a high yield even if the reaction is performed only with a light hydrocarbon raw material without using a diluent.

The reactor system of the present invention may be either a fixed bed of catalyst or a fluidized bed. In practical use, a fluidized bed system capable of continuous regeneration is preferable in order to prevent the catalyst activity from being lowered by coking. As an example of practical use of this system, there is an FCC device generally used for gasoline production in the field of petroleum refining, and it can be applied as a device type. In such a fluidized bed system, the apparatus comprises a reaction tower and a regeneration tower, these two towers are connected by two lines, and the catalyst circulates through the reaction tower and the regeneration tower. In the reaction tower, the catalyst and vaporized raw material oil contact each other in a fluid state and the decomposition reaction proceeds, and the catalyst with coke adhered is sent to the regeneration tower after the oil is removed by the stripper and regenerated by burning the coke with air. . The circulation of the catalyst is controlled by the pressure difference, density and level between the reaction column and the regeneration column.

[0022]

[Examples] Specific examples of the lab-scale fixed-bed reaction equipment according to the present invention will be shown below, but the present invention is not limited thereto.

[0023]

Example 1 Preparation of Catalyst 11.3 g of aluminum sulfate (18-hydrate) and tetra
Propyl ammonium bromide 30g distilled water 200
The solution dissolved in g is silica sol (30% SiO 2 ₂) 17
The mixture was added dropwise to 0 g with stirring to obtain a mixture. This mixture
Under strong stirring, add 30 g of 20% sodium hydroxide aqueous solution dropwise.
After lowering and homogenizing, put in a 500 ml autoclave
And reacted at 160 ° C under stirring at 600 rpm for 65 hours.
Let After the reaction, cooling, filtering the reaction mixture, washing with water,
After separating the product, it was dried at 120 ° C for 3 hours and dried at 550 ° C for 3 hours.
When calcined in air for 4 hours, 44.8 g of crystalline
A minosilicate zeolite was obtained. Powder this one
When confirmed by X-ray diffraction, it shows a ZSM-5 pattern.
did. The ZSM-5 zeolite obtained by the above method was mixed with 10
% Ion exchange by contacting with an aqueous ammonium chloride solution.
Apply, dry at 120 ° C, and bake in air at 550 ° C for 3 hours.
Then, a proton type ZSM-5 was obtained. Fluorescent X-ray analysis
Riko's thing SiO₂/ Al₂O₃The ratio was 53.

Catalytic decomposition reaction The obtained proton-type ZSM-5 (SiO ₂ / Al ₂ O ₃ ratio 53 measured by fluorescent X-ray analysis) was compression molded and then crushed to obtain 9 to 20 mesh. 0.0g for inner diameter 2
It was filled in a 4 mmφ quartz glass reactor, and the conversion reaction of naphtha was carried out under the conditions of naphtha 25 g / hr and temperature 680 ° C. under atmospheric pressure. Raw material naphtha has a density of 0.683 g / c
The composition in m ³ is shown in Table 2. In addition, the analysis was carried out using gas chromatography (TCD, FID detector) by collecting a reaction product 10 to 40 minutes after starting the supply of the raw material, which was collected as a gas and a liquid. The results are shown in Table 3. In addition,
The naphtha conversion rate in Table 3 was defined by the following formula.

[0025]

[Equation 1]

[0026]

Examples 2 and ₃ Proton type ZSM-5 having different SiO ₂ / Al ₂ O ₃ ratios was prepared by the same synthetic method as in Example 1 except that the raw material charging ratio was changed. According to fluorescent X-ray analysis, the SiO ₂ / Al ₂ O ₃ ratio of Example 2 is 72, and the SiO ₂ / A of Example 3 is _2.
The l ₂ O ₃ ratio was 120. After compression molding, the product was crushed and the conversion reaction of naphtha was carried out in the same manner as in Example 1. SiO ₂ / Al ₂ O ₃ ratio of the prepared catalyst, reaction conditions, and
The reaction results are shown in Table 3.

[0027]

Example 4 Synthesis was carried out in the same manner as in Example 1 except that tetrabutylphosphonium bromide was replaced with tetrabutylphosphonium chloride. After firing, when confirmed by powder X-ray diffraction, a ZSM-11 pattern was shown.
Ion exchange was carried out in the same manner as in Example 1, followed by drying and firing to obtain a proton type ZSM-11. According to the fluorescent X-ray analysis, the SiO ₂ / Al ₂ O ₃ ratio of this product was 55.

After compression molding, the product was crushed and the conversion reaction of naphtha was carried out in the same manner as in Example 1. The results are shown in Table 3.

[0029]

[Examples 5 and 6] Proton type ZSM synthesized in Example 2
-5 (SiO measured by fluorescent X-ray analysis ₂/ Al₂O₃
The compression ratio of 72) was crushed and then crushed to obtain a reaction temperature of 6 in Example 5.
50 ° C., Example 6 is the same as Example 1 at a reaction temperature of 720 ° C.
The conversion reaction of naphtha was carried out by the method described above. The results are shown in Table 4.
Indicated.

[0030]

Example 7 Proton type ZSM-5 synthesized in Example 3
(SiO measured by fluorescent X-ray analysis ₂/ Al₂O₃Ratio 1
20) is mixed with alumina sol and extrusion-molded, 0.6 mm
φ zeolite containing 70 wt% Al₂O₃30% by weight
Molded pellets were obtained. Using this as a catalyst, Example 1
The conversion reaction of naphtha was carried out in the same manner as in. Result first
The results are shown in Table 4.

[0031]

[Embodiment 8] The catalyst reacted in 40 minutes in Example 2 was directly packed in a reactor at a temperature of 800 ° C. for 1 hour, air was flowed at 100 cc / min to burn the coke deposited on the catalyst to regenerate the catalyst. Was done. After the regeneration, the conversion reaction of naphtha was performed again in the same manner as in Example 1. The fourth result
Shown in the table.

[0032]

Comparative Example 1 Solution (A) prepared by dissolving 5.2 g of aluminum sulfate (18-hydrate) and 7.5 g of tetrapropylammonium bromide in 90 g of distilled water, 60 g of sodium silicate (water glass No. 3), 120 g of distilled water. A solution (B) consisting of Then, the solutions (A) and (B) were simultaneously added dropwise under stirring to obtain a mixture. Under strong stirring, 18 g of 20% sulfuric acid was added dropwise to this mixture to homogenize it, and then the mixture was put into a 500 ml autoclave and heated at 160 ° C. for 6 hours.
The reaction was carried out for 40 hours under stirring at 00 rpm. After the reaction, cooling, the reaction mixture is filtered, washed with water, to separate the solid,
When dried at 120 ° C. for 3 hours and calcined at 550 ° C. for 3 hours in air, 16.0 g of crystalline aluminosilicate zeolite was obtained. When this product was confirmed by powder X-ray diffraction, it showed a ZSM-5 pattern. The ZSM-5 zeolite obtained by the above method was brought into contact with a 10% ammonium chloride aqueous solution to carry out ion exchange, dried at 120 ° C. and then calcined in air at 550 ° C. for 3 hours to obtain a proton type ZSM-5. It was In addition, from the X-ray fluorescence analysis, SiO ₂
The / Al ₂ O ₃ ratio was 30. After compression molding, it was pulverized and the conversion reaction of naphtha was carried out in the same manner as in Example 1.
The reaction results are shown in Table 5. When the SiO ₂ / Al ₂ O ₃ ratio is less than 50, the aroma yield is high, but the ethylene and propylene yields are low.

[0033]

[Comparative Example 2] In the same synthetic method as in Example 1, the raw material charging ratio was set.
Change SiO₂/ Al₂O₃Proton type ZS with different ratio
M-5 was prepared. Fluorescence X-ray analysis shows SiO₂/ Al
₂O ₃The ratio was 462. Example after crushing and crushing
The conversion reaction of naphtha was carried out in the same manner as in 1. Reaction
The results are shown in Table 4.

When the SiO ₂ / Al ₂ O ₃ ratio exceeds 150, sufficient catalytic decomposition activity cannot be obtained and ethylene,
Both propylene and aroma yields are low.

[0035]

[Comparative Examples 3 to 5] Proton type ZSM synthesized in Example 2
-5 (SiO measured by fluorescent X-ray analysis ₂/ Al₂O₃
Comparative Example 3 was crushed after compression molding and the reaction temperature was 5
80 ° C., Comparative Example 4 has a reaction temperature of 780 ° C., Comparative Example 5 has a weight
The same method as in Example 1 was applied at a spatiotemporal velocity of 0.5 / hr.
The conversion reaction of fussa was performed. The results are shown in Table 5.

When the reaction temperature is lower than 600 ° C., the yield of ethylene and propylene is low, and when it exceeds 750 ° C., the deterioration of the catalyst progresses due to coke precipitation and the yield of propylene and aroma is low. Even if the weight hourly space velocity is less than 1, the yield of ethylene, propylene, and aroma is low because the catalyst is deteriorated due to coke deposition.

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

[Table 4]

[0041]

[Table 5]

[0042]

[Effects of the Invention] High yields of ethylene, propylene, and monocyclic aromatic hydrocarbons (benzene, toluene, xylene), which are useful as basic chemical raw materials, using naphtha as a raw material without using a diluent. Can be obtained at

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Claims (1)

[Claims] 1. A light hydrocarbon raw material mainly composed of paraffins having 2 to 12 carbon atoms is converted to a lower olefin mainly composed of ethylene and propylene and a monocyclic aromatic hydrocarbon mainly composed of benzene, toluene and xylene. In the method, the temperature is 600 to 750 ° C., and the weight hourly space velocity is
Under the condition of 200 / hour, the SiO ₂ / Al ₂ O ₃ ratio is 5
A method comprising contacting with a zeolite catalyst selected from ZSM-5s and ZSM-11 in the range of 0 to 150.