JPH0639410B2 - Method for producing lower olefin containing propylene as a main component - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for catalytically converting a hydrocarbon mainly containing paraffin. More specifically, by using a crystalline aluminosilicate zeolite supporting silver or silver and phosphorus as a catalyst, hydrocarbons mainly composed of paraffin are efficiently converted, and propylene, which is valuable as a petrochemical raw material, is contained as a main component. To a method for producing a lower olefin.

(Prior Art) It is well known that various hydrocarbon raw materials are contacted with a solid acid catalyst, particularly crystalline aluminosilicate zeolite, and converted by reactions such as cracking, isomerization, disproportionation and hydrocracking. Has been.

As a typical example, the conversion of heavy oil or the like into a gasoline fraction using Y-type zeolite is widely practiced in petroleum refining. Further, in recent years, a method of converting a light petroleum fraction into lower olefins using various proton type zeolites has been proposed.

For example, there are JP-A-51-57688 and JP-A-60-178830. The Journal of Japan Petroleum Institute, Volume 28, NO.3 (1985)
In "catalytic cracking of hydrocarbons by zeolite catalyst", catalytic cracking of n-pentane has been extensively elucidated by using various zeolite catalysts as a shape-selective catalyst.

Furthermore, in JP-A-59-148728, JP-A-59-152334 and JP-A-62-285987, when converting an aliphatic hydrocarbon into an aromatic hydrocarbon using a metal-supported zeolite catalyst, describes also a by-product olefins _C 2 -C _4.

(Problems to be Solved by the Invention) In recent years, in Japan, where the demand for propylene and lower olefins containing propylene as a main component is increasing as a resin raw material, the production of these is mainly a by-product from an ethylene plant by thermal decomposition of naphtha, Alternatively, it relies on by-products from the FCC plant to obtain catalytically cracked gasoline, but since they are by-products, it is not possible to expect high yields and they are limited to low yields, so the demand for main products is high. If it does not grow, there is a problem that propylene and lower olefins containing propylene as a main component are insufficient. Therefore, a method for efficiently producing a lower olefin containing propylene as a main component is desired, but none of the known methods is satisfactory.

For example, in the catalytic conversion method using Y-type zeolite, ferrierite, and mordenite, lower olefins such as methane, ethane, and propane are mainly produced, and in the method using ZSM-5 type zeolite, methane, ethane, and propane, etc. Lower olefins and aromatic hydrocarbons are mainly produced. Furthermore, a method for producing an aromatic hydrocarbon using ion-exchange treatment with metal ions or using a metal oxide-supported zeolite (JP-A-59-148728).
JP-A-59-152334 and JP-A-62-285987)
Then, although aromatic hydrocarbons are the main product and olefins are also by-products, the conversion rate decreases when the selectivity of aromatic hydrocarbon channels is relatively low and the olefin by-product rate is relatively high. There is a tendency. Thus, the problem could not be solved by any of the methods.

The present invention solves such a problem, and produces a lower olefin containing propylene as a main component in a high yield, that is, with a high selectivity and a high conversion, by a catalytic reaction of a hydrocarbon mainly containing paraffin. The purpose is to

(Means for Solving the Problems) As a result of intensive studies for achieving the above-mentioned object, the present inventors carried a specific amount of a specific metal in a catalytic reaction of a hydrocarbon raw material mainly containing paraffin. By using the crystalline aluminosilicate zeolite as a catalyst and conducting the reaction within a specific contact time, surprisingly, the production of paraffin and aromatic hydrocarbons is suppressed, and the target lower olefin containing propylene as a main component is suppressed. It was found that a high yield, that is, a high selectivity and a high conversion rate can be obtained.

That is, according to the present invention, when a lower olefin containing propylene as a main component is produced by a catalytic reaction of a hydrocarbon containing C3 to C10 as a main component, 0.1 to 50% by weight is used.
The silver-supported crystalline aluminosilicate zeolite as a catalyst, and the contact time of the raw material paraffin and the catalyst is 1.0 seconds or less, or the silver-supported crystalline aluminosilicate zeolite further 0.1 ~ 5.0 wt% phosphorus The present invention relates to a method for producing a lower olefin containing propylene as a main component, which is supported.

More specifically, the hydrocarbon used as a raw material in the catalytic reaction of the present invention is a paraffin having 3 to 10 carbon atoms or a hydrocarbon containing the paraffin as a main component. Specifically, propane, n-butane, i-butane,
Paraffins such as n-pentane, i-pentane, n-hexane, i-hexane, heptane, octane, nonane, and decane, and naphtha mainly containing a mixture thereof and having a carbon number of 4 or more and a boiling point of 150 ° C or less. Those are preferable.

The crystalline aluminosilicate zeolite, which is one of the constituent elements of the catalyst used in the present invention, includes X-type zeolite, Y-type zeolite, mordenite, ferrierite,
Examples include offretite, erionite, zeolite having a mixture of offretite and erionite, ZSM-5 type zeolite, and hydrogen ion type thereof.

Particularly preferred are ZSM-5 type zeolite having a SiO ₂ / A ₂ O ₃ molar ratio (hereinafter molar ratio) of 25 or more, and zeolite in which offretite and erionite structure are mixed. When using ZSM-5 type zeolite, the reaction product is SiO ₂ / A ₂ O in the crystal structure.
_It depends on the ₃ ratio, and if the SiO ₂ / A ₂ O ₃ ratio is small, it is highly active, so the conversion is high, but the selectivity of lower paraffins such as methane, ethane, and propane, and aromatic hydrocarbons is high, and that of propylene and the like is high. The selectivity of lower olefins is low. On the other hand, when the SiO ₂ / A ₂ O ₃ ratio is large, the conversion is low because of low activity. Therefore, according to the present invention, ZSM-5 type zeolite (hereinafter referred to as NaZSM-5 type zeolite) in a cation state such as Na is converted to hydrogen ion type ZSM-5.
Type zeolite (hereinafter referred to as HZSM-5 type zeolite)
When used, the SiO ₂ / A ₂ O ₃ ratio is preferably 25 to 800, and more preferably 35 to 600.

The metal supported on the crystalline aluminosilicate zeolite generally has a large amount of lower paraffins such as ethane and propane when the supported amount is small, and conversely tends to produce methane and aromatic hydrocarbons when the supported amount is large. is there.
Therefore, in order to produce a large amount of lower olefin containing propylene as the main component, which is the object of the present invention, it is important to adjust the amount of metal supported.

In the method of the present invention, the metal supported on the zeolite is silver. The amount of silver supported on zeolite is 0.1 to 50.
%, Preferably 0.2 to 20% by weight. The contact time between the raw material hydrocarbon and the catalyst is usually 1.0 second or less.

Even when the reaction is carried out under a condition slightly deviated from the range of the supported amount and the contact time, the yield of the lower olefin containing propylene as a main component is not so low, but the excellent effect of the present invention, that is, , It is difficult to maintain a high yield of 50% or more.

The method of supporting silver can be carried out by a commonly used means such as an ion exchange method, an impregnation method, and a kneading method. The metal salts used include those commonly available, for example, silver nitrate, silver acetate, and silver sulfate. The crystalline aluminosilicate zeolite that has been subjected to the supporting treatment of silver can be calcined by a commonly used method. Firing temperature is 300-800 ℃,
The temperature is preferably 400 to 650 ° C., and the firing time is 0.1 to 20 hours, preferably 0.5 to 10 hours.

The above-mentioned amounts of silver supported are all values calculated as metals.

When crystalline aluminosilicate zeolite is loaded with phosphorus in combination with the above silver, coke formation can be suppressed without impairing the characteristics of the above silver, and stability against high temperature steam is improved. . The supported amount of phosphorus having such an action is within the range of 0.1 to 5.0% by weight as an element. The loading of phosphorus may be performed before loading silver on the crystalline aluminosilicate zeolite or after loading it. The supporting method is the same as in the case of silver. As the phosphorus compound to be used, phosphoric acid, diammonium hydrogen phosphate, ammonium dihydrogen phosphate and other water-soluble phosphates are preferable.

Further, the crystalline aluminosilicate zeolite may be used as a mixture with a porous material such as alumina, silica, diatomaceous earth, clay, zirconia, titania, silica-alumina, silica-magnesia, silica-zirconia, silica-titania, In this case, the mixing treatment may be carried out either before or after carrying the silver.

The reaction temperature of the method of the present invention is 350 to 700 ° C., preferably 400 to 6
The temperature is 50 ° C, more preferably 450 to 600 ° C. The reaction temperature is
If the temperature does not reach 350 ° C, the conversion rate of the raw material paraffin is low, and if it exceeds 700 ° C, a large amount of methane and aromatic hydrocarbons are generated, and the production of coke increases rapidly, which is not preferable.

The reaction method of the method of the present invention may be a fixed bed type, a fluidized bed type, an air flow type, or the like. In addition, it is preferable to use, for example, carbon dioxide gas, helium, nitrogen, steam, or flue gas that does not substantially contain oxygen as the transport air flow.

(Effect of the Invention) In the method of the present invention, crystalline aluminosilicate zeolite is used as a catalyst, and silver is supported in a specific ratio on the catalyst to suppress the production of lower paraffins and aromatic hydrocarbons and to contain propylene as a main component. The selectivity of lower olefins was significantly increased to 55-80% by weight, and the raw material C ₃
It can be increased to -C ₁₀ or more always 70% also conversion of paraffins, the yield of lower olefins composed mainly of propylene can be 50% or more.

In addition, when a catalyst supporting phosphorus with silver is used, as compared with the case of using a catalyst not supporting phosphorus, coke generation is suppressed, and stability to high temperature steam is improved. In the case of containing propylene, the catalyst life is not shortened even when the catalyst is regenerated with steam or when high temperature steam is used as a carrier air flow. The lower olefin as the main component can be economically produced.

(Examples) Hereinafter, the present invention will be described more specifically with reference to Examples and the like, but the present invention is not limited thereto.

Example 1 HZSM-5 type zeolite _{(SiO 2 / A 2 O 3} = 200)
Dipped in 15% by weight silver nitrate solution and then dried in air
A catalyst supporting 3.0% by weight of silver was prepared by firing at 550 ° C. for 5 hours.

A quartz reaction tube (inner diameter 4 mmφ) is filled with 0.3 cc (200 mg) of catalyst sized to 24-32 mesh, and the temperature is 600 ° C under air flow.
Heated for 1 hour. Next, under atmospheric pressure helium gas flow (5000 m / hr, NTP, the same below) 550
After the temperature was raised to 0 ° C, 1 µ of n-hexane was injected and the contact time was 0.
The contact reaction was performed in 07 seconds. The reaction product was analyzed using a gas chromatograph. The results are shown in Table 1 together with the results of Examples 2 and 3 and Comparative Example 1 below.

Example 2 HZSM-5 type zeolite _{(SiO 2 / A 2 O 3} = 200)
Was treated with 0.1N silver nitrate solution at a temperature of 90 ° C. for 50 hours. After washing with water and drying, the catalyst was prepared by baking in air at 550 ° C. for 5 hours. The catalyst supported 1.6% by weight of silver. Using this catalyst, a catalytic reaction was carried out under the same conditions as in Example 1.

Example 3 The catalytic reaction was carried out under the same conditions as in Example 1 except that the amount of silver supported was changed to 0.2% by weight.

Comparative Example 1 The catalytic reaction was carried out under the same conditions as in Example 1 except that the zeolite used in Example 1 was used as a catalyst without supporting silver.

Example 4 A catalytic reaction was carried out under the same conditions as in Example 1 except that 5.0% by weight of silver was supported on HZSM-5 type zeolite (SiO ₂ / A ₂ O ₃ = 50) and the reaction temperature was changed to 500 ° C. . The results are shown in Table 2 together with the results of Example 5 and Comparative Example 2.

Example 5 The catalytic reaction was carried out under the same conditions as in Example 4 except that the amount of silver supported was changed to 20.0% by weight.

Comparative Example 2 The catalytic reaction was carried out under the same conditions as in Example 4, using the zeolite used in Example 4 as a catalyst without supporting silver.

Example 6 A catalytic reaction was carried out under the same conditions as in Example 1, in which 5.0 wt% of silver was supported on a hydrogen ion type of offretite-erionite mixed zeolite (product of Tosoh Corporation, SiO ₂ / A ₂ O ₃ = 8.0). I went. The results are shown in Table 3 together with the results of Comparative Example 3.

Comparative Example 3 The catalytic reaction was carried out under the same conditions as in Example 1, using the zeolite used in Example 6 as a catalyst without supporting silver.

Example 7 HY-type zeolite _{(SiO 2 / A 2 O 3} = 4.8) and silica - alumina _{(38% A 2 O 3 ·} 62% SiO 2) were mixed in a ratio of 20:80 silver 3.0 wt% on The catalytic reaction was carried out under the same conditions as in Example 1 except that the reaction product was used as a catalyst and the reaction temperature was changed to 600 ° C. The results are shown in Table 3 together with the results of Comparative Example 4.

Comparative Example 4 The catalytic reaction was carried out under the same conditions as in Example 7, using the zeolite used in Example 7 as a catalyst without supporting silver.

Example 8 The catalytic reaction was carried out under the same conditions as in Example 1 except that the raw material hydrocarbon was changed to n-pentane and the silver supported amount of the catalyst was changed to 1% by weight. The results are shown in Table 4 together with the results of Examples 9 and 10 below.

Example 9 The catalytic reaction was carried out under the same conditions as in Example 1 except that the starting hydrocarbon was changed to n-heptane.

Example 10 The catalytic reaction was carried out under the same conditions as in Example 1 except that the raw material hydrocarbon was changed to naphtha (specific gravity 0.700, composition: 81% by weight of paraffin, 12% by weight of naphthene, 7% by weight of aromatic hydrocarbon). .

The conversion and paraffin and aromatics in the product distribution were determined as follows. In the calculation of the conversion rate, the amount of C _{3 to} C ₄ paraffins present in the raw material naphtha was small, so it was ignored, and the composition of the gas flowing out from the reactor was analyzed, and the paraffins and naphthenes (C _{5 and} higher) present were calculated. 1
6.8%) is the total unconverted, and since the aromatics (18.0%) present in the reactor effluent is larger than the amount present in the raw material, 7% present in the raw material is left as unconverted. The total unconverted rate was 23.8%. Therefore, the conversion rate is 76.2%
Becomes Then paraffins in the product distribution is therefore C ₁ -C ₄ paraffins content in the reactor effluent therein based on the system excluding unconverted fraction as described above.
As for aromatics, as described above, the amount of aromatics produced by this reaction is converted to 11.0% (the amount of aromatics in the reactor effluent minus 7.0% of unconverted aromatics) converted to the distribution in the product. Therefore, it was calculated by dividing by 0.762.

Example 11 HZSM-5 type zeolite (SiO ₂ / A ₂ O ₃ = 50) was immersed in a 5 wt% diammonium hydrogen phosphate solution, dried, and calcined in air at 550 ° C. for 5 hours to remove phosphorus. 1.0 wt% was supported. This was loaded with 5.0% by weight of silver under the same conditions as in Example 1 and then sized to 24 to 32 mesh.
In order to examine the stability against steam, after filling a stainless steel reaction tube and treating steam at a temperature of 600 ° C. for 25 hours, a contact reaction was carried out under the same conditions as in Example 1. The results are shown in Table 5.

Comparative Example 4 HZSM-5 type zeolite (SiO ₂ / A ₂ O ₃ = 50) was steamed under the same conditions as in Example 13 and then subjected to a catalytic reaction. The results are shown in Table 5.

Claims (2)

[Claims] 1. A crystalline aluminosilicate carrying 0.1 to 50% by weight of silver for producing a lower olefin containing propylene as a main component by catalytic reaction of a hydrocarbon mainly containing paraffins having 3 to 10 carbon atoms. A method for producing a lower olefin containing propylene as a main component, characterized by using zeolite as a catalyst. 2. The method for producing a lower olefin containing propylene as a main component according to claim 1, wherein the crystalline aluminosilicate zeolite catalyst further supports 0.1 to 5.0% by weight of phosphorus.