JPH1149705A - Production of lower olefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a lower olefin that is useful as a basic raw material for a variety of chemicals by catalytically decomposing a hydrocarbon raw material using a catalyst of a rare earth element oxide in the presence of oxygen as the formation of aromatic and heavy side-products is inhibited. SOLUTION: (A) A hydrocarbon raw material (of 2-30 carbon atoms, preferably of 2-20 carbon atoms, particularly ethane) is catalytically decomposed by using (B) a catalyst of a rare earth element oxide such as oxide of lanthanum or neodymium preferably containing an alkali metal and/or alkaline earth metal (lithium or magnesium) as a cocatalyst, in the presence of (C) oxygen at a mixed ratio of the component A to the component C in terms of an atomic ratio of the oxygen/the carbon atoms of 0.01-3 at 500-800 deg.C, preferably 550-780 deg.C to obtain the objective olefin.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a catalyst for catalytically cracking a hydrocarbon feedstock using a catalyst to produce a lower olefin,
It mainly relates to a method for producing ethylene and propylene.

[0002]

2. Description of the Related Art Lower olefins such as ethylene and propylene are important substances as basic raw materials for various chemical products. Conventionally, as a method for producing these lower olefins, a method in which a gaseous hydrocarbon such as ethane, propane, butane or a liquid hydrocarbon such as naphtha is used as a raw material and is thermally decomposed in a steam furnace in an externally heated tubular furnace. Is widely practiced. However, in this method, a high temperature of 800 ° C. or more is required to increase the gasification rate, there are many by-products such as heavy substances, and carbon precipitated during decomposition causes coking in the decomposition furnace. There were problems. Therefore, as a means for solving such a problem, a catalytic cracking method using various catalysts has been proposed. For example, a method in which a mixture of chromium oxide and magnesium oxide to which at least one of aluminum oxide, silicon dioxide, iron oxide, calcium oxide and potassium oxide is added as a catalyst is used to catalytically decompose a hydrocarbon raw material in the presence of steam. (JP-B-53-23806), a method of catalytically cracking in the presence of steam using a catalyst containing 20 to 100% by weight of a rare earth oxide as a rare-earth oxide (JP-B-56-299).
No. 19), using a mixed oxide catalyst obtained by mixing at least one selected from lithium oxide, sodium oxide and potassium oxide with a titanate of an alkaline earth metal oxide, and performing catalytic cracking in the presence of steam (JP-B-57-42672), using a catalyst comprising a refractory carrier such as titanium oxide, an oxide of a Group VIb metal of the periodic table and an alkali metal oxide, and catalytically cracking in the presence of steam. Process (JP-A-59-193834), using a catalyst comprising an oxide of manganese or iron and at least one oxide of magnesium, a lanthanum-based metal or niobium, and catalytically cracking in the presence of steam. A method (Japanese Patent Publication No. 7-68151) and the like are disclosed. These methods have the effect of reducing the occurrence of coking and increasing the gasification rate of the raw material, but require a reaction temperature as high as in the case of thermal decomposition for the development of catalytic activity. In addition, there is a problem in terms of energy efficiency, such as that in each method, almost the same amount of steam as the raw material is mixed with the raw material, so that a large amount of energy is consumed for heating the steam. On the other hand, a method of catalytic cracking using a crystalline aluminosilicate zeolite or a zeolite catalyst such as ZSM-5 or ZSM-11 (for example, JP-A-61-7218, JP-A-6-192134, etc.) ) Is disclosed. In these methods,
Olefins can be produced at a relatively low temperature without using steam.However, since all of them are aimed at co-production of aromatic hydrocarbons, when performing selective production of lower olefins such as ethylene and propylene, Was inappropriate.

[0003]

DISCLOSURE OF THE INVENTION The present invention relates to the production of lower olefins such as ethylene and propylene by catalytic cracking of a hydrocarbon raw material using a catalyst, and the production of lower by-products such as aromatic hydrocarbons and heavy substances. It is an object of the present invention to provide a method for producing a lower olefin in an advantageous manner in terms of energy cost while suppressing the production.

[0004]

Means for Solving the Problems The inventors of the present invention have made intensive studies to solve the above-mentioned problems, and as a result, the catalyst was decomposed in the presence of oxygen using a catalyst containing a rare earth element oxide as a main component. As a result, they have found that ethylene and propylene can be produced selectively at a low temperature that is industrially advantageous, and have completed the present invention. That is, according to the present invention, there is provided a method for producing a lower olefin, which comprises catalytically cracking a hydrocarbon raw material in the presence of oxygen using a rare earth oxide catalyst. Further, according to the present invention, a hydrocarbon material is catalytically cracked in the presence of oxygen using a catalyst comprising a rare earth element oxide containing an alkali metal and / or an alkaline earth metal. An olefin production method is provided.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION As the hydrocarbon raw material used in the present invention, gaseous or liquid hydrocarbons at normal temperature and normal pressure can be used. Generally, it has 2 to 30 carbon atoms, preferably
2 to 20 paraffins or a hydrocarbon raw material containing the same as a main component (10 wt% or more) are used. Examples of such hydrocarbon raw materials include paraffins such as ethane, propane, butane, pentane and hexane, and light hydrocarbon fractions such as naphtha and light oil. The raw material components are not limited to saturated hydrocarbons, and those containing components having unsaturated bonds can also be used.

The catalyst of the present invention contains a rare earth element oxide as a main component. As the rare earth element, any can be used, but preferably, lanthanum, neodymium, samarium, europium, gadolinium, dysprosium, holmium and the like can be mentioned. Used as an oxide of The rare earth element oxides may be used alone or in combination of two or more.
The preparation of the catalyst comprises a rare earth element oxide or various salts thereof,
For example, acetate, nitrate, halide, sulfate, carbonate, or alkoxide, acetylacetonate,
It can be easily carried out by firing at a temperature of 600 to 1,000 ° C. in the presence of oxygen.

The catalyst comprising the rare earth element oxide according to the present invention may contain an alkali metal and / or an alkaline earth metal as a promoter. Use of such a cocatalyst can further increase the selectivity of ethylene and propylene. In the cocatalyst, the alkali metal includes lithium, sodium, potassium and cesium, and the alkaline earth metal includes magnesium, calcium, strontium and barium. In the catalyst of the present invention, the co-catalyst can be present in the form of a metal compound such as a carbonate in addition to an oxide and a hydroxide. In the catalyst of the present invention, the proportion of the cocatalyst used per atom of the rare earth element is, in the case of an alkali metal,
0.01 to 10 atoms, preferably 0.1 to 5 atoms, and in the case of an alkaline earth metal, 0.01 to 100 atoms,
Preferably, the ratio is 0.1 to 50 atoms.

As a method for preparing a catalyst comprising a rare earth element oxide containing a cocatalyst, a powder mixing method, a wet mixing method, an impregnation method, a coprecipitation method, a sol-gel method and the like can be adopted. The shape of the catalyst of the present invention is not particularly limited, and may be any shape such as a powder or a molded product. These catalysts may be used by mixing a filler such as silica, alumina, magnesia or quartz sand.

The method for producing a lower olefin according to the present invention is a method of decomposing a hydrocarbon raw material in the presence of the catalyst of the present invention in the presence of oxygen. In this case, by causing oxygen to be present in the reaction system, generation of heavy substances can be suppressed, coking can be prevented, and the activity of the catalyst at low temperatures can be increased. The oxygen source is not particularly limited to high-purity oxygen, and air may be used. The mixing ratio of the hydrocarbon raw material and oxygen is 0.01 to 0.01 atomic ratio of oxygen / carbon.
3, preferably in the range of 0.1 to 2, usually outside the explosion range. When the oxygen / carbon ratio is higher than 3, the production of carbon monoxide and carbon dioxide increases, so that the selectivity of the lower olefin decreases. When the oxygen / carbon ratio is lower than 0.01, the activity of the catalyst is low and the gasification rate of the raw material is low. Decrease or
Alternatively, when the reaction temperature is high, the result is the same as that of ordinary thermal decomposition, which causes coking.

The catalytic cracking reaction of the present invention is carried out by using a fixed bed, a fluidized bed or the like type reactor and supplying a mixed fluid of a hydrocarbon raw material and oxygen to the catalyst bed filled with the catalyst. . At this time, the mixed fluid may be diluted with nitrogen, steam, helium, argon, or the like. The reaction temperature is 500-800 ° C, preferably 550-780.
° C, more preferably in the range of 600 to 700 ° C.
Although it can be carried out at a temperature exceeding 800 ° C., in this case, formation of carbon monoxide and carbon dioxide becomes remarkable, and
When the oxygen / carbon ratio of the mixed fluid is low, oxygen is almost completely consumed, and there is a possibility that coking may occur due to thermal decomposition. In the present invention, a sufficient catalytic activity can be exhibited even at a low temperature, and thus a reaction temperature in the above range is sufficient. The reaction can be carried out at normal pressure, reduced pressure or increased pressure, but normal pressure is usually employed. If the method of the present invention is carried out under the above conditions, hydrocarbon feedstock can be efficiently decomposed at a low temperature, and ethylene,
Lower olefins such as propylene can be selectively produced.

In the present invention, since oxygen is mixed with the raw material, a part of the raw material is discharged as carbon monoxide and carbon dioxide. However, in the present invention, it is possible to lower the reaction temperature by 100 ° C. or more as compared with the conventional thermal decomposition method. The amount of carbon dioxide is extremely small compared to the amount of carbon dioxide expected to be generated from the combustion of the plant. Therefore, the total amount of carbon dioxide emitted is greatly reduced in consideration of the entire plant.

[0012]

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 7 0.2 g of catalyst powder and quartz sand were placed in a quartz straight tube reactor (inner diameter 10 mm, length 30 cm) made so as to form a catalyst layer of 3 cm in the center. A mixture obtained by mechanically mixing 2 g was filled to prepare a fixed bed flow reactor. This catalyst layer was treated at 800 ° C. in an air atmosphere as a pretreatment.
For 1 hour. Thereafter, a mixed fluid of 1.4% by volume of n-butane, 1.5% by volume of oxygen, 5.7% by volume of nitrogen, and 91.4% by volume of helium (oxygen / carbon atom ratio = 0.5%) was added to the catalyst layer. ) At a reaction temperature of 600 ° C. and a flow rate of 97 cc /
min distributed. The reaction product was analyzed by gas chromatography, and the product gas yield, raw material conversion, and oxygen conversion were calculated by the following equations. Product gas yield (% by weight) = weight of each component / weight of feedstock ×
100 Conversion rate of raw material (%) = (1−weight of unreacted raw material / weight of feed material) × 100 Oxygen conversion rate (%) = (1−weight of unreacted oxygen / weight of supplied oxygen) × 100 Lanthanum oxide, neodymium oxide as catalyst Table 1 shows the results when samarium oxide, europium oxide, gadolinium oxide, dysprosium oxide, and holmium oxide were used.

Comparative Examples 1 and 2 The results obtained when the catalyst layer was filled with magnesium oxide or quartz sand alone under the same conditions as in Example 1 are also shown in Table 1.

[0015]

[Table 1]

From the results shown in Table 1, it can be seen that when the catalyst of the present invention was used, the yields of ethylene and propylene were high and the raw materials were decomposed efficiently.

Examples 8 to 10 and Comparative Example 3 The reaction was carried out in the same manner as in Example 1 except that the oxygen / carbon atom ratio of the raw material mixed fluid was changed to the ratio shown in Table 2, and the reaction temperature was 700 ° C. Was. Table 2 shows the results. Although the yields of ethylene and propylene are affected by the mixing ratio of oxygen, they can be obtained in high yields by properly defining the O / C atomic ratio. This shows that the activity of the catalyst is not sufficiently exhibited.

Comparative Example 4 A reaction was carried out in the same manner as in Example 10 except that steam was mixed instead of oxygen in the raw material mixed fluid. The results are also shown in Table 2. It can be seen that the raw material conversion and the olefin yield are low under the condition that oxygen is not present even when steam is mixed.

[0019]

[Table 2]

Examples 11 to 16 Each powder of magnesium oxide, calcium oxide and barium oxide was mixed with a powder of lanthanum oxide in a weight ratio of 1: 1.
Mix in agate mortar with a small amount of water, 120 ° C
After drying overnight at 500 ° C. for 2 hours,
C. for 2 hours, (i) lanthanum oxide / magnesium oxide, (ii) lanthanum oxide / calcium oxide and (iii)
A lanthanum oxide / barium oxide mixed catalyst was prepared. The decomposition reaction of n-butane was performed in the same manner as in Example 1 except that the pretreatment was performed at 700 ° C. for 1 hour using each catalyst, and the reaction temperature was set at 600 ° C. or 700 ° C. Table 3 shows the results at a reaction temperature of 600 ° C.
Table 4 shows the case at 00 ° C. When the alkaline earth metal oxide was mixed, the yield of ethylene and propylene was further improved as compared with the case of the rare earth oxide alone.

Examples 17 to 19, Comparative Example 5 An aqueous solution of lithium nitrate (1.1 g) was impregnated with 2.5 g of lanthanum oxide powder, and after removing water, dried at 120 ° C. overnight and dried at 500 ° C. 2 hours, followed by 2 hours at 700 ° C
The mixture was calcined for a period of time to prepare a lithium / lanthanum oxide mixed catalyst. In this case, lithium was included as lithium oxide. Using the same catalyst, a catalyst amount of 0.69 g and a pretreatment of 7
The decomposition reaction of n-butane was performed in the same manner as in Example 1 except that the reaction temperature was set at 600 ° C. or 700 ° C. at 00 ° C. for 1 hour. Table 3 shows the results at a reaction temperature of 600 ° C., and Table 4 shows the results at a reaction temperature of 700 ° C. In Example 19, the amount of the catalyst was 1.26 g, the pretreatment was at 700 ° C. for 1 hour, and the flow rate of the raw material mixed fluid having the composition shown in Table 5 was 2.3.
The reaction was carried out at a reaction temperature of 600 ° C. in the same manner as in Example 1 except that cc / min was used. Table 5 shows the results. Also,
Table 5 also shows the results when the reaction was carried out under the same conditions as in Example 19 by filling the catalyst layer only with quartz sand.

Examples 20 and 21 0.5 g of lithium nitrate and 3.4 of lanthanum nitrate hexahydrate
1 g of calcium oxide to the mixed aqueous solution of
After removing water, dry at 120 ° C. overnight,
After that, the mixture was calcined at 700 ° C. for 2 hours to prepare a lithium / lanthanum oxide / calcium oxide mixed catalyst. In this case, lithium was included as lithium oxide. Using the same catalyst, the decomposition amount of n-butane was performed in the same manner as in Example 1 except that the catalyst amount was 0.68 g, the pretreatment was 700 ° C. for 1 hour, and the reaction temperature was 600 ° C. or 700 ° C. Was. Table 3 shows the results at a reaction temperature of 600 ° C.
Table 4 shows the case at 00 ° C.

Example 22 A raw material mixed fluid having the composition shown in Table 5 was supplied at a flow rate of 2.33 cc / min.
The reaction was carried out in the same manner as in Example 20, except that the reaction was conducted. Table 5 shows the results. A mixed catalyst with an alkali metal compound suppresses the production of carbon monoxide and carbon dioxide,
It can be seen that industrially useful olefins can be produced more selectively.

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

[Table 5]

[0027]

According to the method of the present invention, gaseous or liquid hydrocarbons are used as raw materials, by-products such as heavy substances are reduced, coking is prevented, and lower olefins such as ethylene and propylene are selectively produced. Can be manufactured. Furthermore, in the case of the present invention, it is possible to lower the reaction temperature by 100 ° C. or more as compared with the conventional thermal decomposition method.

 ──────────────────────────────────────────────────続 き Continuation of the front page (71) Applicant 000183657 Idemitsu Petrochemical Co., Ltd. 5-6-1 Shiba, Minato-ku, Tokyo (71) Applicant 000221627 Tonen Chemical Co., Ltd. 1-1-39 Hiroo, Shibuya-ku, Tokyo (71) Applicant 000231682 Nippon Petrochemical Co., Ltd. 1-3-1, Uchisaiwai-cho, Chiyoda-ku, Tokyo (74) The above five agents Patent Attorney Toshiaki Ikeura (72) Inventor Yuji Yoshimura 1-1-1, Higashi, Tsukuba, Ibaraki Inside the Institute of Materials Science and Technology, Institute of Industrial Science and Technology (72) Inventor Takashi Hayakawa 1-1-1, Higashi, Tsukuba, Ibaraki Prefecture Inside the Institute of Materials Science and Technology, Institute of Industrial Science (72) Kunio Suzuki 1-1-1, Higashi, Tsukuba, Ibaraki Industry (72) Inventor Katsuomi Takehira 1-1-1 Higashi, Tsukuba City, Ibaraki Pref. (72) Inventor Goro Sawada 3-6-1 Kasumigaseki, Chiyoda-ku, Tokyo Japan Chemical Industry Association (72) Inventor Kenichi Wakui 3-6-1 Kasumigaseki, Chiyoda-ku, Tokyo Within the Japan Chemical Industry Association (72) Inventor Koji Shiozawa 3-2-6 Kasumigaseki, Chiyoda-ku, Tokyo (72) Within the Japan Chemical Industry Association (72) Koichi Sato 3-2-2, Kasumigaseki, Chiyoda-ku, Tokyo Japan Chemical Industry Association

Claims (5)

[Claims] 1. A process for producing lower olefins, comprising subjecting a hydrocarbon raw material to catalytic cracking in the presence of oxygen using a catalyst comprising a rare earth element oxide. 2. A process for producing a lower olefin comprising catalytically cracking a hydrocarbon raw material in the presence of oxygen using a catalyst comprising a rare earth element oxide containing an alkali metal and / or an alkaline earth metal. Method. 3. The method according to claim 2, wherein said alkali metal and / or alkaline earth metal is an oxide, hydroxide or carbonate. 4. The mixing ratio of the hydrocarbon material and oxygen is oxygen / oxygen.
The atomic ratio of carbon is in the range of 0.01 to 3.
The method according to any of the above. 5. The method according to claim 1, wherein the catalytic cracking reaction is carried out at a reaction temperature of 500 to 800 ° C.