JPH0816072B2 - Method of manufacturing olefin - Google Patents

Description

The present invention relates to a process for producing olefins by catalytic cracking of hydrocarbons. More specifically, the light naphtha is brought into contact with a specific zeolite catalyst to obtain a high selectivity and a carbon number of 2 to 2
4 (hereinafter, abbreviated as _C2-4 ).

The naphtha produced by petroleum refining is a basic raw material in the petrochemical industry. In recent years, naphtha, which is a generic term for light naphtha, is a paraffin with a relatively low boiling point due to a great change in the environment surrounding petroleum and petrochemistry. , Hydrocarbons containing naphthene as the main component, aromatic hydrocarbons, olefins,
There is a strong demand for technology that can be converted to high-value-added products such as high-octane gasoline.

On the other hand, a technique of catalytically decomposing various hydrocarbon fractions using a solid acid catalyst such as an acid catalyst, particularly a zeolite which is a crystalline aluminosilicate, has been known for a long time,
C with higher selectivity than light naphtha, which is the object of the present invention,
_A satisfactory technique for catalytic cracking to _2-4 olefins has not yet been established.

For example, Japanese Examined Patent Publication No. 56-42639 is intended for the production of aromatic compounds from light naphtha, and decomposition using ZSM-5 zeolite as a catalyst is exemplified. According to this result, the decomposition into olefins was obtained only in a remarkably unsatisfactory yield.

In view of these circumstances, as a result of diligent studies by the present inventors, when catalytically cracking a hydrocarbon of a light fraction with a zeolite catalyst, a side reaction such as polymerization of the produced olefin is usually generated, and the obtained production distribution is , It was clarified that it remarkably depends on the crystal and pore structure of zeolite used as a catalyst. Therefore, as a result of conducting a detailed study on the decomposition activity, the behavior of products, and the like of various zeolites, when ferrierite is used as a catalyst, Y-type zeolite usually used as a catalyst in the catalytic decomposition of hydrocarbons. In comparison with, the secondary polymerization of the produced olefin was significantly suppressed, and a new fact that C _2-4 olefin containing propylene as a main component can be obtained with a high selectivity was found, and the present invention was completed. It was

As described above, the present invention provides an industrial olefin production method characterized by using ferrierite as a catalyst when converting light naphtha into olefin by catalytic cracking.

 Hereinafter, the present invention will be described in more detail.

The process of the present invention is carried out by contacting the raw light naphtha with a catalytic zeolite. The zeolite used in the present invention is ferrierite. The ferrierite of the present invention is approximated by a crystalline aluminosilicate of the following formula by the molar ratio of oxides.

M ₂ / nO · Al ₂ O ₃ · (5-100) SiO ₂ However, M represents a cation having a valence of n, and usually has water of crystallization.

The crystal structure of ferrierite is described in Journal of Catalysis, Vol. 35, pp. 267-2.
It is shown on page 72 (issued in 1974). That is, ferrierite is a zeolite having a main cavity composed of a 10-membered oxygen atom ring with an effective pore size of about 5Å. Generally, the crystal structure of such a zeolite is determined by an X-ray diffraction method, and the powder X-ray diffraction pattern distinguishes it from other zeolites. Table 1 shows the measurement results described in the above-mentioned reference as a typical powder X-ray diffraction pattern of ferrierite.

Ferrierite may be either a natural product or a synthetic product, but is preferably a synthetic product because of its uniform composition. The synthesis can be easily performed by known techniques. For example, ferrierite may be synthesized according to Japanese Patent Application No. 57-176077.

When using ferrierite as a catalyst in the process of the invention, it is necessary to convert the cations contained in the zeolite structure to the hydrogen ion form. To this end, for example, for a zeolite containing a metal ion such as sodium or potassium as a cation, a conventionally well-known ion exchange treatment, that is, an aqueous solution of ammonium chloride or the like is used to remove the metal ion. It can be easily converted to the hydrogen ion type by calcination after exchange with ammonium ion or treatment in a mineral acid aqueous solution such as hydrochloric acid. Depending on the synthesis method, there are some that contain organic ammonium ions and the like at the time of synthesis acquisition. For example, ferrierite and the like synthesized in the presence of N-methylpyridine contain these contained organic cations at 400 to 700 ° C. In the range, it is converted into hydrogen ion type by air calcination and, if necessary, the ion exchange treatment. The amount converted into hydrogen ions, that is, the hydrogen ion exchange rate is 50% or more, preferably 70
% Or more is required.

On the other hand, its form is not particularly limited, and it may be either powdery or shaped. In addition, when shaping it,
As the molding method, a known method such as a compression molding method, an extrusion molding method, or a spray drying granulation method is adopted. Further, in the case of molding, a binder or a molding aid is usually used for the purpose of increasing its mechanical strength, but the catalyst of the present invention is also inert to the reaction of the present invention. Any substance can be used for this purpose. For example, silica, viscosities, graphite, stearic acid, starch, polyvinyl alcohol and the like can be added in the range of 0 to 80%, preferably 2 to 30%.

Thus, the obtained catalyst of the present invention is preferably subjected to a calcination treatment in air at a temperature of 400 to 800 ° C. for 1 to 10 hours and then used for the reaction.

The feedstock used in the novel process of the present invention has a carbon number of 5 (hereinafter abbreviated as C ₅ ) to at least 50% by volume of 150 ° C.
A liquid hydrocarbon having a boiling point range up to the fraction having the following boiling points, which is composed of liquid paraffin, olefin, naphthene, etc., preferably a liquid hydrocarbon having a boiling point of C ₅ to about 100 ° C, that is, in the art. It is collectively called light naphtha.

The reaction of the present invention is carried out by introducing a raw material hydrocarbon onto the catalyst, and the hydrocarbon is supplied as it is or as a mixture with a diluent gas. At this time, the diluent gas used is not particularly limited as long as it is inert to the reaction, and an inert gas such as nitrogen or helium is usually used. The concentration of the raw material hydrocarbon is not particularly limited, but is preferably 5 to 100.
It is selected from the range of volume%.

The supply of the raw material gas depends on the reaction temperature, but it is usually 10 times as a catalyst time: W / F (g-cat · hr /, where: catalyst weight g, F: gas flow rate of raw hydrocarbons / hr) ~ 50,000g-ca
t · hr / preferably selected from the range of 20 to 10,000 g-cat · hr /.

The reaction temperature is in the range of 300 to 800 ° C. Usually, in catalytic cracking with a zeolite catalyst, the lower the reaction temperature, the more likely the olefin selectivity tends to decrease due to polymerization of the olefin produced. . On the other hand, when the temperature rises, the production of methane increases due to the sequential decomposition of the produced olefin. Therefore, the preferred temperature range for the process of the present invention is 400-700 ° C.

The reaction can be carried out under pressure, but is usually carried out at atmospheric pressure.

The type of apparatus used in the practice of the present invention is not particularly limited and may be appropriately selected from fixed bed, fluidized bed, moving bed and the like.

Hereinafter, the present invention will be described in more detail with reference to Examples.
The invention is not limited to these examples only.

Reference Example 1. Synthesis of Ferrierite Ferrierite was synthesized according to the method described in Japanese Patent Application No. 57-176077. That is, in an overflow type reaction vessel equipped with a stirrer, an aqueous solution of sulfuric acid-acidified aluminum sulfate (Al ₂ O ₃ = 4.44 w / v%, H ₂ SO ₄ = 25.69 w / v%) and an aqueous sodium silicate solution (Na ₂ O = 6.56w / v%, SiO ₂ = 20.00w / v%, A
l ₂ O ₃ = 0.22w / v%), respectively 0.25 / hr and 0.75 / h
They were fed simultaneously and continuously at a feed rate of r and reacted under stirring. The residence time of the reaction slurry was 30 minutes, and the pH of the slurry was 6.2 and the reaction temperature was 32 ° C.

The slurry product overflowing from the reaction tank,
After solid-liquid separation and sufficient washing with water, a uniform compound having the following composition was obtained.

Na ₂ O: 5.20 wt% (dry base) Al ₂ O ₃ : 7.13 wt% (dry base) SiO ₂ : 87.7 wt% (dry base) H ₂ O: 59.7 wt% (wet base) Next, 0.89 wt% concentration 505g of sodium hydroxide aqueous solution
To the above, 355.6 g of the above-mentioned homogeneous compound was added and stirred, and this slurry was charged into an autoclave. Crystallization was carried out at a temperature of 180 ° C. and its autogenous pressure for 72 hours. Then, the mixture was cooled to room temperature, the resulting solid crystals were washed with water, dried and then dried. As a result of powder X-ray diffraction measurement of the obtained powder by CuKα double ray, the X-ray diffraction pattern of ferrierite shown in Table 3 was obtained. Also, as a result of elemental analysis,
It had the following composition:

1.03Na ₂ O ・ Al ₂ O ₃・ 19.3SiO ₂ 2. Preparation of catalyst The zeolite used as a catalyst was made into a hydrogen ion type by an ion exchange treatment. That is, ion exchange treatment was performed 6 times at 80 ° C. for 8 hours in a NH ₄ Cl solution. This was filtered, washed with water, dried, and then air-baked at 540 ° C. for 2 hours to obtain a hydrogen ion type.

The ion exchange rate was determined by measuring the amount of Na ⁺ or K ^{+ in} the liquid after ion exchange by flame photometry or by elemental analysis.

The hydrogen ion-type zeolite thus obtained was sized to 32 to 80 mesh and used as a catalyst.

Examples -1 to 3 The decomposition reaction of normal pentane (hereinafter abbreviated as n-pentane) was performed using the ferrierite obtained in Reference Example as a catalyst. That is, a normal fixed-bed atmospheric pressure reactor (quartz glass inner diameter
120 × 350 mm length) was loaded with catalyst in the range of 0.1-2 g. First, after firing for 1 hour at a predetermined temperature under air flow, the temperature was changed to air and the reaction temperature was adjusted to a predetermined reaction temperature under nitrogen gas flow. Then
As a raw material hydrocarbon, n-pentane was introduced into the reactor to carry out the reaction. At that time, n-pentane was nitrogen gas at -25 ° C.
It was passed through an n-pentane saturator maintained at 20 ° C. and set to a gas concentration of 20%. The reaction product gas was directly introduced into the gas chromatograph to analyze the product. Table 5 shows the reaction conditions and the results.

Comparative Example 1 Commercially available Y-type zeolite _{(SiO 2 / Al 2 O 3} = 5.2) according to the method of Reference Example was converted to a hydrogen ion form. Using this as a catalyst, the reaction was carried out in the same manner as in Example-1. The results are shown in Table 5.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References Japanese Patent Publication No. 45-15372 (JP, B1) Japanese Patent Publication No. 44-26365 (JP, B1) US Patent 3039953 (US, A) US Patent 3354078 (US, A) U.S. Patent 4021332 (US, A) U.S. Patent 4116813 (US, A) U.S. Patent 3894940 (US, A) "Chemical Review No. 34 Catalyst Design" August 1, 1982 Published by Academic Publishing Center, Inc. p. 105 ~ 106

Claims (2)

[Claims] 1. From 5 carbon atoms to at least 50% by volume of 150 ° C.
A method for producing an olefin characterized by using ferrierite as a catalyst when converting a hydrocarbon having a boiling point range up to a fraction having a boiling point below, which comprises a paraffin, an olefin and / or naphthene, into an olefin by catalytic cracking. . 2. The method according to claim 1, wherein at least 50% or more of the exchangeable cations of ferrierite are hydrogen ions.