JPH06199707A - Catalytic cracking of light hydrocarbon - Google Patents

Abstract

PURPOSE:To convert a light hydrocarbon composed mainly of paraffin into lower olefins and monocyclic aromatic hydrocarbons in high yield. CONSTITUTION:A light hydrocarbon raw material containing 2-12C paraffin as main component (>=70wt.%) is brought into contact with a catalyst consisting of an aluminosilicate zeolite having intermediate pore size and containing 100wt. ppm to 1wt.% of iron (preferably ZSM-5 zeolite and ZSM-11 zeolite) at 600-800 deg.C under a weight hourly space velocity of 1-200/hr. The hydrocarbon raw material can be converted to lower olefins composed mainly of ethylene and propylene and monocyclic aromatic hydrocarbons composed mainly of benzene, toluene and xylene by this process.

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. 130236/1993 discloses a method in which a catalyst having a specific intermediate pore size zeolite, 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 is disclosed. Has been done. 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 obtained, 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-1-2
In the example of Japanese Patent No. 13240, 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 object of the present invention is to overcome the problems of the prior art and efficiently use paraffin-based light hydrocarbons, particularly naphtha as a raw material to efficiently feed ethylene, propylene and aroma, and especially to increase propylene. It is to provide a catalytic cracking method which is produced in a yield.

[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,
The present invention has been completed by using an intermediate pore diameter aluminosilicate zeolite containing 100 ppm by weight to 1% by weight of iron as a catalytic cracking catalyst. That is, the present invention uses a light hydrocarbon raw material mainly composed of paraffins having 2 to 12 carbon atoms as a catalyst with an intermediate pore size aluminosilicate containing 100 wtppm to 1 wt% of iron at a temperature of 600 to 800 ° C. and a weight time of 600 to 800 ° C. Space velocity (WHSV) 1-
Efficiently contact lower olefins containing ethylene and propylene and monocyclic aromatic hydrocarbons (aroma) containing benzene, toluene and xylene as main components by contacting under the condition of 200 / hour, and especially high yield of propylene. It provides a way to get at a rate. The lower olefin referred to here is
In addition to ethylene and propylene, butene, pentene and hexene are included. Further, the monocyclic aromatic hydrocarbon is benzene,
In addition to toluene and xylene, it contains ethylbenzene and styrene.

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 of about 7.
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 medium pore size aluminosilicate zeolite used in the present invention has a medium pore size of small pore size zeolite represented by A type zeolite, and large pore size zeolite represented by X type and Y type zeolite, The effective pore size is in the range of about 5 to 6.5. As representatives of these, ZSM-5 class, ZSM-11, Z
SM-12, ZSM-21, ZSM-23, ZSM-3
5, ZSM-38 and the like, but preferred examples are ZSM-5s and ZSM-11.

As the catalyst used in the present invention, these zeolites may be used alone or as a mixture. The ZSM-5s referred to in the present invention are zeolites whose X-ray diffraction pattern includes at least the peak of the interplanar distance shown in Table 1. The peaks in Table 1 are diffraction peaks peculiar to ZSM-5's, and other peaks are included in ZSM-5's which are the object of the present invention even if they are slightly different from each other.

The ZSM-5s included in the present invention include:
For example, ZSM-5 (US Pat. No. 3,702,886), ZS
M-8 (German Patent No. 2049755), ZETA-1
(German Patent 2548697), ZETA-3 (British Patent 1553209), NU-4 (German Patent 326).
8503), NU-5 (German Patent 3169606).
No.), TZ-01 (US Pat. No. 4,581,216), Cr
ystalline aluminosilicate
(US Pat. No. 4,954,326), TRS (German Patent 2
924870), MB-28 (European Patent 21445)
No.), TSZ (JP-A-58-45111), AZ-1
(European Patent No. 113116) and the like. ZSM-
8, ZETA-1, NU-4, NU-5, TZ-01,
TSZ, etc., is the inter-plane distance d = 3.8 described in Table 1.
The main peak of 5 ± 0.07 is described as a double peak, but such a zeolite is also included in the catalyst used in the present invention.

The zeolite used in the present invention may contain various metal elements by a method such as ion exchange or impregnation, but the hydrogen type zeolite can be used as it is. As an example of preparation of the hydrogen type zeolite, the calcined zeolite can be ion-exchanged with ammonium ions, and the ammonium-exchanged zeolite can be calcined under a condition sufficient to release ammonium.

In addition, SiO ₂ / A of these zeolites
The l ₂ O ₃ ratio is in the range of 20 to 500, preferably 3
It can be selected in the range of 0 to 400. When the ratio is less than 20, stability as a catalyst is poor, and when it exceeds 500, the catalytic activity is insufficient. The zeolite used in the present invention is prepared by hydrothermal synthesis. In this case, a raw material containing an iron element may be used as the raw material. As the aluminum raw material of the zeolite raw material, aluminum sulfate, sodium aluminate, alumina, aluminum isopropoxide, etc., as the silicon raw material,
Sodium silicate, silica sol, silica and the like are used.
Since the silicon raw material is used in a larger amount than the aluminum raw material, the amount of the iron element mixed in the zeolite due to the raw material mainly depends on the iron component concentration in the silicon raw material.

It is also preferable to use an iron container during the hydrothermal synthesis of zeolite to produce the iron-containing zeolite of the present invention. In the present invention, the iron component contained in the synthesized zeolite is derived from the iron component contained in the zeolite synthesis raw material and the mixed iron component contained in the zeolite hydrothermal synthesis process, so that the iron element contained in the synthesized zeolite is catalytically decomposed of light hydrocarbons. Effective in the reaction. The amount here is 100 weight pp
It means a range of m to 1% by weight. This value can be measured by the fluorescent X-ray method.

The effect of the iron element can be confirmed by synthesizing and comparing zeolite having a low iron element content. For the zeolite with an iron element content of less than 100 ppm by weight, use a raw material in which the iron element content of the silicon raw material is suppressed to several ppm or less, and in addition, use a reactor equipped with a Teflon container in the autoclave to produce water. It can be synthesized by performing thermal synthesis.

The amount of elemental iron according to the present invention is 100 wtpp
The catalytic cracking reaction of light hydrocarbons was carried out between the case where the zeolite contained in the range of m to 1 wt% was used as the catalyst and the case where the zeolite containing less than 100 ppm by weight of the iron element for comparison was used as the catalyst. As a result, the catalyst according to the present invention exhibits the effect of increasing the total yield of ethylene, propylene, and monocyclic aroma, in particular, the yield of propylene. The iron element according to the present invention does not matter whether it is in an ionic state or incorporated in the zeolite crystal structure. The point is that the amount of iron element is 100 weight p regardless of the compound state.
Zeolite contained in the range of pm to 1% by weight can be applied as the catalyst of the present invention.

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. By this molding treatment, the mechanical strength at the time of use is increased, but the activity per unit weight of the catalyst is reduced by the amount added with the matrix and the binder.

The conditions for carrying out the present invention are 600 to 800.
℃ temperature, weight hourly space velocity of ¹ ~ 200hr ^-1 (WH
SV), a pressure of 0.1 to 30 kg / cm ² is adopted. 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 a reactor system, the contact efficiency between the hydrocarbon feedstock and the catalyst tends to increase as the reactor size increases, so increase the weight hourly space velocity to obtain the same catalytic activity. Will be possible.

Since each condition does not take proper values 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 the aroma and the total yield thereof are high. However, when the reaction temperature is lower than 600 ° C., the yield of ethylene and propylene is low, and when the temperature is higher than 800 ° C., deterioration of the catalyst progresses due to coke precipitation and the yield of propylene and aroma is low. In addition, weight space velocity 1
Even under the conditions below, the yield of ethylene, propylene, and aroma is low because the deterioration of the catalyst due to coke precipitation progresses.
Under the condition of more than 0, the conversion rate is low, and the ethylene and aroma yields are low.

In carrying out the present invention, the raw material can be diluted with an inert gas such as nitrogen or helius. However, even if the reaction is carried out only with a light hydrocarbon raw material without using a diluent, a high yield of an effective product can be obtained. It is also a characteristic of the present invention to be obtained by. The reactor system of the present invention may be either a fixed bed of catalyst or a fluidized bed. For practical use,
A fluidized bed system capable of continuous regeneration is preferred in order to prevent a decrease in catalyst activity due to 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 equipment consists of a reaction tower and a regeneration tower, these two towers being connected by two lines,
The catalyst circulates in the reaction tower and the regeneration tower through this line. 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 3.7 g of aluminum sulfate (18-hydrate) and 30 g of tetrapropylammonium bromide were added to 200 g of distilled water.
The solution dissolved in was added dropwise to 170 g of silica sol (30% SiO ₂ ) containing 30 ppm by weight of Fe with stirring to obtain a mixture. With vigorous stirring, 10.5 g of a 20% aqueous sodium hydroxide solution was added dropwise to this mixture to homogenize it.
Put in a 500 ml autoclave made of SUS304, 16
The mixture was reacted at 0 ° C. under stirring at 600 rpm for 65 hours. After the reaction, cooling, the reaction mixture was filtered, washed with water, the solid was separated, dried at 120 ° C. for 3 hours and calcined in air at 550 ° C. for 3 hours to obtain 44.0 g of crystalline aluminosilicate zeolite. Was given.

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% aqueous ammonium chloride solution to carry out ion exchange, and after drying at 120 ° C.,
Proton-type ZSM baked in air at 550 ° C for 3 hours
-5 was obtained. Fluorescent X-ray analysis of this product SiO ₂ /
The Al ₂ O ₃ ratio was 153, and the Fe content was 620 ppm by weight. Fluorescent X-RA measurement
Using a Y SPECTROMETER RIX 3000 device, the zeolite was diluted 4 times with Avicel, and then compression molding was performed for measurement.

Catalytic decomposition reaction The obtained proton type ZSM-5 was compression molded and then pulverized to obtain 9 to 20 mesh, 1.0 g of which had an inner diameter of 24 m.
It was filled in a mφ quartz glass reactor, and the naphtha conversion reaction was carried out under the conditions of naphtha 25 g / hr and temperature 680 ° C. under atmospheric pressure. The raw material naphtha has a density of 0.683 g / cm ^3.
The composition is shown in Table 2. In addition, the analysis is performed by collecting the reaction product 10 to 40 minutes after starting the supply of the raw material by separating it into a gas and a liquid, and performing gas chromatography (TCD, FID detector).
Was performed using. The results are shown in Table 3. The third
The naphtha conversion rate in the table was defined by the following formula.

[0026]

[Equation 1]

[0027]

Example 2 The same synthetic method as in Example 1 was applied at 160 ° C. and 80 ° C.
Hydrothermal synthesis was carried out under stirring at 0 rpm for 85 hours. After firing, confirmed by powder X-ray diffraction ZSM-5
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-5. Fluorescent X-ray analysis of this product SiO ₂ / Al ₂
O ₃ ratio is 155, Fe content is 1020 weight p
It was pm.

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]

Example 3 Fe 2 was used as a raw material by the same synthetic method as in Example 1.
Using silica sol containing 10 ppm, 160 ° C., 12
Hydrothermal synthesis was performed under stirring at 00 rpm for 120 hours. After firing, powder X-ray diffraction confirmed ZSM-
5 patterns were 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-5.
Got Fluorescent X-ray analysis of this product SiO ₂ / Al
_{The 2} O ₃ ratio was 151, and the Fe content was 2800 ppm by weight.

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.

[0031]

[Examples 4 and 5] Proton-type ZSM synthesized in Example 1
-5 (SiO measured by fluorescent X-ray analysis ₂/ Al₂O₃
A ratio of 153 and an Fe content of 620 ppm by weight)
Reaction temperature 620 ° C., Example 5 is weight hourly space velocity 40 /
The conversion reaction of naphtha was carried out in the same manner as in Example 1 with hr.
It was The reaction conditions and the reaction results are shown in Table 3.

[0032]

Comparative Example 1 Fe was added in an amount of 6 wt.
In an autoclave using silica sol containing pm as a raw material
Attach a Teflon container to the inside, and in it, 160 ℃, 600r
The mixture was reacted for 65 hours under stirring at pm. Powder X-ray after firing
When confirmed by diffraction, it showed a ZSM-5 pattern.
Ion exchange was carried out in the same manner as in Example 1, followed by drying and firing.
Then, a proton type ZSM-5 was obtained. Fluorescent X-ray analysis
More of this SiO ₂/ Al₂O₃The ratio is 148
Therefore, the Fe content was 10 ppm by weight.

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 4.

[0034]

Comparative Examples 2 and 3 Proton-type ZSM synthesized in Comparative Example 1
-5 (SiO measured by fluorescent X-ray analysis ₂/ Al₂O₃
The comparative example 3 shows a ratio of 148 and an Fe content of 10 wt ppm).
Response temperature 620 ° C., Comparative example 4 is weight hourly space velocity 40 / h
The conversion reaction of naphtha was carried out in the same manner as in Example 1 with r.
It was The reaction conditions and the reaction results are shown in Table 4.

Comparison of Examples 1, 2 and 3 with Comparative Example 1, Example 4 with Comparative Example 2, and Example 5 with Comparative Example 3 revealed that Fe was 10
It can be seen that the propylene yield is low when the content of 0 wt ppm or more is not included.

[0036]

[Table 1]

[0037]

[Table 2]

[0038]

[Table 3]

[0039]

[Table 4]

[0040]

[Effects of the Invention] Ethylene, propylene, monocyclic aromatic hydrocarbons (benzene, toluene, xylene), which are useful products as basic chemical raw materials made from naphtha, have high yields without diluting propylene. You can get at a rate.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C10G 35/06 6958-4H 35/095 6958-4H // C07B 61/00 300

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 raw material is contact-reacted with a catalyst, which is an intermediate pore size aluminosilicate zeolite containing iron in the range of 100 ppm by weight to 1% by weight.