JPH03130236A - Catalytic conversion of hydrocarbon - Google Patents

Abstract

PURPOSE:To obtain a lower olefin and monocyclic aromatic hydrocarbon by contacting a hydrocarbon raw material composed mainly of paraffins, under a specific contact condition, with an aluminosilicate zeolite having medium pore size fulfilling a specific condition. CONSTITUTION:A lower olefin and a monocyclic aromatic hydrocarbon can be produced by contacting a hydrocarbon raw material (e.g. propane, butane, butene, pentane, pentene or petroleum naphtha fraction) with an aluminosilicate zeolite having medium pore size in the presence of steam at 550-700 deg.C and a weight time space velocity of 0.5-20/hr. It is necessary to use a zeolite having a pyridine desorption of 40-180mumol per 1g of the zeolite measured at 500-900 deg.C using pyridine at a heating rate of 15 deg.C/min and the zeolite satisfying the condition is e. g. a ZSM-5 zeolite containing alkali metal or alkaline earth metal. The deterioration of catalyst can be suppressed by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for catalytic conversion of hydrocarbons mainly composed of paraffins. This invention relates to a method for producing lower olefins and monocyclic aromatics useful as chemical raw materials from hydrocarbon raw materials mainly consisting of paraffins.

[Conventional technology]

It is well known that various hydrocarbon raw materials are brought into contact with a solid acid catalyst, particularly a crystalline aluminosilicate zeolite, and converted by reactions such as cracking, isomerization, disproportionation, and hydrocracking.

Typical examples include Y-type zeolite, light oil,
It is a method of converting heavy oil etc. into gasoline fraction, and is widely practiced in petroleum refining.A method of converting light hydrocarbons into aromatic compounds using ZSM-5 type zeolite has also been proposed. ing.

For example, JP-A-49-41322, JP-A-50-
This method is disclosed in Japanese Patent Application Laid-open No. 49233, Japanese Unexamined Patent Publication No. 50-4029, and the like.

Furthermore, in Japanese Patent Application Laid-open No. 60-222428, ZSM-
A method is disclosed for converting light hydrocarbons into lower olefins and aromatic compounds under conditions of high temperature and high WH8V using type 5 zeolite.

[Problem to be solved by the invention]

The above-mentioned methods all apply to lower olefins (olefins having 2 to 4 carbon atoms, such as ethylene, propylene, butene, etc.) and monocyclic aromatic hydrocarbons (aromatic olefins having 6 to 9 carbon atoms), which are useful as chemical raw materials. However, there is no satisfactory method for obtaining lower olefins (benzene and alkylbenzene) efficiently and in a higher yield than monocyclic aromatic hydrocarbons.

For example, in the catalytic conversion method using Y-type zeolite, a large amount of low-value light paraffin gas is produced, and the production of aromatic hydrocarbons is extremely small. Further, in the method using ZSM-5 type zeolite, the yield of aromatic hydrocarbons is generally relatively high, but the cracked gas composition is mainly light paraffins such as ethane and propane, and the selectivity for lower olefins is poor. Furthermore, in order to increase the selectivity of lower olefins, there are problems such as the need to make the reaction conditions harsher.

On the other hand, the thermal decomposition method is widely used as a method for obtaining lower olefins in good yield, but since it is a thermal decomposition method, it requires harsh reaction conditions, so methane is difficult to use as a chemical raw material. There are many side products.

Furthermore, the product yield of olefins such as ethylene and propylene, and monocyclic aromatic hydrocarbons such as benzene and toluene in the decomposition products has a very limited ratio, and flexibility in the yield structure is limited. They have problems such as poor sexuality.

[Means to solve the problem]

The present inventors have conducted intensive studies on a method for efficiently producing lower olefins and monocyclic aromatic hydrocarbons from hydrocarbon raw materials having at least 2 or more carbon atoms, and at a higher yield than monocyclic aromatic hydrocarbons. Layered. As a result, when a specific intermediate pore diameter aluminosilicate zeolite is used as a catalyst, lower olefins and monocyclic aromatic hydrocarbons can be obtained efficiently, and lower olefins can be obtained in higher yield than monocyclic aromatic hydrocarbons. The present invention was completed by discovering that this catalyst system is stable and exhibits little deterioration over time.

That is, the present invention provides a method for converting a hydrocarbon raw material having at least 2 carbon atoms into a lower olefin and a monocyclic aromatic hydrocarbon, in which the raw material is an aluminosilicate zeolite with an intermediate pore diameter that satisfies the following (i), and a 550-700
The present invention provides a method for the catalytic conversion of the feedstock hydrocarbons, characterized in that the contact is carried out at a temperature of 0.5°C and a weight hourly space velocity of 0.5 to 20 hr'.

(1) The amount of pyridine desorbed per 1 g of the intermediate pore size aluminosilicate zeolite is 40 to 180 μmop at 500 to 900 °C by the temperature-programmed desorption method when pyridine is used and the heating rate is 15 °C/min. The hydrocarbon having at least 2 or more carbon atoms in the present invention is
It mainly contains normal paraffins having 2 to about 25 carbon atoms, isoparaffins, olefins, cycloparaffins, cycloparaffins having side chain alkyl groups, etc., such as gases such as ethane, propane, butane, butene, etc. Hydrogenation treatment consisting of light naphtha, heavy naphtha, straight-run naphtha, mainly composed of pentane, pentene, hexane, heptane, octane alone or a mixture thereof, kerosene fraction mainly containing C10"C20, C19 to C2, In particular, propane, butane, butene, pentane, pentene, and naphtha fractions are preferred.

The intermediate pore size aluminosilicate zeolite in the present invention has a pore size intermediate between small pore size zeolite represented by A-type zeolite, and large pore size zeolite represented by X-type and Y-type zeolites, and has an effective pore size. It is in the range of about 5λ to 6.5 people. Representative examples of these include ZSM-5, ZSM-11, ZSM-12, Z
SM-21, ZSM-23, ZSM-35, ZSM-3
8 etc., but preferred ones are ZSM-
5°ZSM-11, ZSM-38, and ZSM-5 is particularly preferred.

Moreover, the silicon/aluminum atomic ratio of these zeolites is 10-75, preferably 12-60.

If this ratio is less than 10, the stability as a catalyst is poor, and if this ratio is more than 75, the catalytic activity is insufficient.

The intermediate pore size aluminosilicate zeolite catalyst used in the present invention uses pyridine to desorb pyridine per gram of the zeolite at 500 to 900°C by a temperature-programmed desorption method at a heating rate of 15°C/min. The amount is 40~
It is 180μmofi. Regarding the temperature-programmed desorption method, see "Chemistry and Industry" by Yasumori.

Volume 19, No. 10, pp. 1208-1214 (196
6), and the temperature-programmed desorption method for ZSM-5 type zeolite is described in "Catalyst J, pp. 25.97-99 (198
3) etc.

The temperature programmed desorption method using pyridine as used in the present invention is, firstly,
Pyridine is saturated adsorbed onto the catalyst to be measured at 180°C, and the temperature is raised at a constant rate of 15°C per minute. Pyridine, which is desorbed as the temperature rises, is absorbed into hydrogen only between 500 and 900°C. This refers to detecting with a flame ionization detector and determining the amount of desorption as the equivalent amount of pyridine using a pyridine calibration curve.

FIG. 1 shows a measuring device for the temperature-programmed desorption method used in the present invention.

The sample, that is, the catalyst 4 to be measured, was crushed into 20 to 30 meshes, with an inner diameter of 6fllfllφ, an outer diameter of 8mm, and a size of 1501 mm.
Place it in a long stainless steel sample tube 3. Cylinder nitrogen was used as a carrier gas, adjusted by mass flow meter 1, and
Flow at a flow rate of m1/min. Pyridine is injected in 2 μg portions through the injection port 5 made of silicone rubber using a microsyringe. If almost the entire amount has been adsorbed, perform the next injection after 10 minutes, or if unadsorbed components are observed, perform the next injection when the completion of outflow is confirmed by the detector, and repeat the injection until saturated adsorption is reached. When the saturated adsorption of pyridine onto the catalyst is completed, the temperature is raised at a rate of 15° C./min in a tubular electric furnace 2 having a core tube inner diameter of 25 mmφ and a length of 100 mm. Here, the flow path from around the pyridine injection port 5 to the flame ionization detector (FID detector) 6 is heated with a ribbon heater 8 or the like, except for the part inside the electric furnace, and the outside is covered with a heat insulating material 9. Cover and heat to 300℃
Keep warm. Temperature detection is performed at the temperature detection end 7 which is installed in close contact with the outside of the sample tube. Pyridine desorbed from the sample 4 is detected by the FID detector 6 from the time when the detected temperature at the temperature detection end 7 reaches 500°C until it reaches 900°C due to further temperature rise, and the calibration curve of pyridine is detected. to determine the amount of desorption.

When the amount of pyridine eliminated by the above method is less than 40μmoρ per zeolite ig, the catalyst activity is insufficient, and when the amount of pyridine eliminated is more than 180μIIIo1, the olefin yield decreases and the catalyst becomes unstable over time. Sex also gets worse.

The catalyst used in the present invention can be produced, for example, by incorporating an alkali metal and/or alkaline earth metal into a proton-type zeolite by a method such as an ion exchange method or an impregnation method, or by heat-treating a proton-type zeolite. Preferably, it is prepared by heat treatment in the coexistence of steam.

When containing an alkali metal and/or an alkaline earth metal, the content is such that the additive metal/aluminum (atomic ratio) is 0.2 to 1.5, preferably 0.3 to 1.2. When this ratio is less than 0.2, the selectivity for olefin production deteriorates, and when it exceeds 1.5, the catalyst activity decreases.

Suitable conditions for heat treatment in the coexistence of water vapor are 60%
Temperature from 0 to 800°C, water pressure from 0.1 to 1 atm, 0.2
~20 hours processing time. Water vapor may be used after being diluted with air or an inert gas such as nitrogen. .

In addition, in order to impart an appropriate catalyst particle shape during use, a commonly used porous inorganic binder such as alumina or silica may be blended, or a hydrogenation/dehydrogenation metal component may be further added.

The reaction conditions in the present invention vary depending on the raw material hydrocarbon, but include a temperature of 550 to 700°C, a weight hourly space velocity (WH3V) of 0.5 to 20 hr, a pressure of 0.5 to 10 atm,
Preferably at a temperature of 550-680°C for 0.5-10h
A weight hourly space velocity (WHS V) of r' and a pressure of 0.8 to 8 atmospheres are employed.

Although the reaction can be carried out using the raw material hydrocarbon alone, it is preferably carried out in the presence of nitrogen, steam, etc., and particularly preferably in the presence of water vapor. In this case, the preferred amount of steam is 0 in terms of the steam/raw material hydrocarbon weight ratio.
．． 1 to 1.0.

〔Effect of the invention〕

According to the present invention, lower olefins and monocyclic aromatic hydrocarbons useful as chemical raw materials can be obtained more efficiently than a wide range of raw materials mainly containing paraffins, and lower olefins can be obtained in higher yield than monocyclic aromatic hydrocarbons. Obtainable. Furthermore, the catalyst does not deteriorate much and can be used stably. Furthermore, compared to the pyrolysis method that has traditionally been widely used to produce lower olefins, there is significantly less methane by-product, which is difficult to use as chemical raw materials. Hydrocarbons can be obtained.

〔Example〕

The present invention will be specifically illustrated below with reference to Examples, but the present invention is not limited thereto.

Example 1 Proton type 25M-5 crystalline aluminosilicate (SiO3/Ag2O3 molar ratio determined by fluorescent X-ray analysis 38,
BET surface! 360m'/g-cat) was compression molded, crushed and arranged into 9 to 20 meshes, and 20g of the material was packed into a quartz glass reactor with an inner diameter of 24mmφ in a water vapor-nitrogen mixed gas containing 80% by volume of water vapor. So, under atmospheric pressure 6
Heat treatment was performed at 50°C for 2.2 hours. The catalyst after heat treatment,
When the amount of pyridine desorbed was measured by temperature-programmed desorption method,
The amount desorbed at 500-900°C was 145 μmoρ/g-catalyst. The measurement sample was sized to 20 to 30 meshes and dried at 400°C for 1 hour. Measuring method,
The conditions were as described above in the text. The tubular electric furnace and temperature control device are thermal analysis devices (DT-30) made by Kinsei Seisakusho.
The FID detector used was a gas chromatograph (GC-183) manufactured by Hitachi. Unless otherwise specified, the amount of pyridine desorbed in the following examples is the temperature-programmed desorption of pyridine at 500 to 900°C, measured under the method and conditions described above.

Next, a conversion experiment was conducted on the catalyst after this heat treatment.

That is, 3 g of catalyst was packed into a quartz glass reactor with an inner diameter of 24+nmφ, and the nitrogen flow rate was 9.5 NN/h under atmospheric pressure.
The conversion reaction of n-hexane was carried out under the conditions of r,n-hexane flow rate of 20 cc/hr and temperature of 650°C. Table 1 shows the reaction results 1 to 1.5 hours after the start of the reaction. Note that the n-hexane conversion rate, selectivity, and 02-C olefin/C6-C8 aromatic group in Table 1 were calculated using the following formulas.

n-hexane conversion rate = (100 - weight % of C6 fraction excluding benzene in the product) weight % of each component in the product n-hexane conversion rate C6-C8 aromatic C2-C4 olefin selectivity Japanese Example 2 50 g of the proton type 25M-5 crystalline aluminosilicate used in Example 1 was ion-exchanged for 3 days at 60°C for 3 hours using 250 g of a 1N aqueous sodium chloride solution.
After further ion exchange at room temperature for 8 hours, filtration, washing,
It was dried (120°C, 2 hours) and fired in air at 500°C for 3 hours. The amount of pyridine desorbed from this Na-containing 28M-5 was 98 μmol/g.

Next, this catalyst was compression molded and then crushed, and 6 g of the catalyst was packed into 9 to 20 meshes into a quartz reaction tube, and the conversion reaction of n-hexane was carried out in the same manner as in Example 1. The results are shown in Table 1.

Example 3 L1-containing ZSM-
5 catalysts were prepared. The amount of pyridine eliminated from this catalyst is 147
It was μwon/g.

Next, n-hexane was reacted in the same manner as in Example 1 using 2.8 g of this catalyst. The results are shown in Table 1.

Example 4 50 g of the proton type 23M-5 crystalline aluminosilicate used in Example 1 was impregnated with 100 g of a 6% by weight strontium nitrate aqueous solution and dried (120°C).

2 hours), fired (5006C in air, 3 hours), and Sr
A catalyst containing 28M-5 was obtained. The amount of pyridine desorbed from this catalyst was 145 μmofl/g.

Next, n-hexane was reacted in the same manner as in Example 1 using 1.7 g of this catalyst. The results are shown in Table 1.

Comparative Example 1 Using 1 g of the proton type 28M-5 crystalline aluminosilicate used in Examples 1 to 4, n
-Hexane reaction was carried out. The results are shown in Table 1. The amount of pyridine eliminated by this catalyst was 437 μmo (J/
It was g.

Example 5 10 g of L1-containing ZSM-5 catalyst prepared in Example 3 (
9 to 20 mesh) was packed into a quartz glass reactor with an inner diameter of 24 mm, and the n-hexane flow rate was 20 at atmospheric pressure.
The n-hexane reaction was carried out under conditions of cc/hr, H20 flow rate of 7, 4 cc/hr, and reaction temperature of about 650°C.

The reaction results and reaction conditions for 1 to 1.5 hours after the start of the reaction were
Shown in the table.

Example 6 Using 510 g of Na-containing 25M prepared in Example 2, n-hexane was converted under the same conditions as in Example 5. The results are shown in Table 2.

Example 7 By performing the same ion exchange operation as in Example 2 using a 1N potassium chloride aqueous solution, K-containing ZSM-5
A catalyst was prepared. The amount of pyridine eliminated from this catalyst is 91gw.
on/g.

Next, using 10 g of this catalyst, n-hexane was reacted in the same manner as in Example 5. The results are shown in Table 2.

Example 8 Sr-containing 28M-5 catalyst l prepared in Example 4.

Conversion of n-hexane was carried out continuously for 24 hours under the same conditions as in Example 5. The reaction results after 1 to 1.5 hours of reaction are shown in Table 2, and the changes over time in the hexane conversion rate are shown in Table 4. After the reaction is complete, the catalyst is taken out and the coke on the catalyst is burned at 800°C in an oxygen stream to remove the generated CO2.
The amount of coke was measured by detecting and quantifying with an infrared spectrometer. The results are shown in Table 3.

Example 9 Using 10 g of the steam-treated 23M-5 catalyst prepared in Example 1, n-hexane was converted under the same conditions as in Example 5. The results are shown in Table 2.

Example 10 A naphtha conversion reaction was carried out in the same manner as in Example 9 except that the raw material was changed to naphtha and the WHSV was changed to 3.2 hr-'. The results are shown in Table 2.

Example 11 20 g of the Sr-containing 28M-5 catalyst prepared in Example 4 was
Fill a SUS 316 reactor with an inner diameter of 3/4B,
54g/hr of n-hexane added with 0.04% by weight of dimethyl disulfide (DMDS) and 2027g of H
/hr, and n-hexane was converted under the reaction conditions of 600°C and 1 kg/cJ-G. The results are shown in Table 2.

Comparative Example 2 Same as Example 5, except that quartz sand was filled instead of the catalyst, and the thermal decomposition was carried out at 650. The test was carried out at 752°C. The results are shown in Table 3. This table shows that in thermal decomposition, when the yield of C2-C4 olefins and C-08 aromatics, which are useful as chemical raw materials, are made to the same level as in the method of the present invention, methane by-products are significant, and 02-C4, which can be further used as raw materials, is produced. It can be seen that the yields of ~C4 paraffin, C fraction, and C6-C8 non-aromatic fraction are low, that is, the selectivity of decomposition is low.

Comparative Example 3 Using 3 g of the same proton type 28M-5 catalyst as in Comparative Example 1, the reaction of n-hexane was carried out continuously for 24 hours in the same manner as in Example 8. Table 4 shows the change in hexane conversion rate over time and the amount of coke.

As described above, the method of the present invention can efficiently obtain lower olefins and monocyclic aromatics from a hydrocarbon raw material having 2 or more carbon atoms, and in a higher yield than lower olefins and monocyclic aromatics. Furthermore, it can be seen that it has advantages such as less methane and heavy hydrocarbon by-products and less deterioration of the catalyst over time.

(Margin below) No. 4 table 4,

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of an apparatus for measuring the amount of temperature-programmed desorption of a catalyst using pyridine.

Claims (4)

[Claims] (1) In a method of converting a hydrocarbon raw material having at least 2 carbon atoms into a lower olefin and a monocyclic aromatic hydrocarbon, the raw material is mixed with an intermediate pore size aluminosilicate zeolite that satisfies the following (1) and at a temperature of 550 to 700°C. ,0.
Contact at a weight time space velocity of 5 to 20 hr^-^1,
A method for the catalytic conversion of hydrocarbons, characterized by producing lower olefins and monocyclic aromatic hydrocarbons. (i) The amount of pyridine desorbed per 1 g of the intermediate pore size aluminosilicate zeolite at 500 to 900°C by the temperature-programmed desorption method using pyridine and a heating rate of 15°C/min is 40 to 180 μmol. (2) The method for catalytic conversion of hydrocarbons according to claim 1, wherein the conversion reaction is carried out in the presence of water vapor. (3) The method for catalytic conversion of hydrocarbons according to claim 1 or 2, wherein the hydrocarbon feedstock is propane, butane, butene, pentane, pentene, petroleum naphtha fraction, and mixtures thereof. (4) ZSM-5 in which the aluminosilicate zeolite contains an alkali metal and/or an alkaline earth metal
The method for catalytic conversion of hydrocarbons according to claim 1, 2 or 3, wherein the method is a zeolite type zeolite.