JP3492396B2 - Olefin purification method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to carbon monoxide, oxygen and carbon dioxide gas (hereinafter CO, O ₂ and C, respectively) present in trace amounts in olefins such as ethylene and propylene.
Abbreviated as O ₂ . ) By contact adsorption removal. More specifically, CO present in trace amounts in olefins,
A method for catalytically removing O ₂ and CO ₂ is provided, and since the adsorbent used is low-temperature active, a trace amount of C
It is an industrially effective method for purifying olefins, which is characterized in that O, O ₂ and CO ₂ can be removed in a gas phase at low temperature.

[0002]

BACKGROUND OF THE INVENTION Trace amounts of CO, O ₂ and C in olefins
As a method of removing O ₂ , a method of contacting olefins with a composition such as copper oxide is known. For example,
In the method described in Japanese Examined Patent Publication (Kokoku) No. 50-25443, a supported catalyst composed of copper oxide or a copper oxide-barium compound-chromium compound system is partially reduced before use, but the reaction activity of the catalyst is sufficient. However, the catalyst must be frequently regenerated, and the degree of partial reduction must be adjusted, which is not practical.

Further, in the method described in Japanese Patent Publication No. 486441/1988, it is described that cupric oxide and zinc oxide are used in combination, but the catalyst has activity at 100 ° C. or higher and is high temperature. It is a type-active catalyst and is disadvantageous in terms of efficiency.

Japanese Unexamined Patent Publication (Kokai) No. 49-90694 discloses a supported catalyst composed of elements belonging to Group IB of the Periodic Table (copper, silver, gold) alone or in combination.

Further, in Japanese Patent Publication No. 48644/1980, it is considered unsuitable to use manganese oxide, chromium oxide or the like in combination with copper oxide since it may oxidize ethylene and explode at high temperature. It was

Further, Japanese Patent Laid-Open No. 53-2405 and Japanese Patent Laid-Open No. 55-154921 disclose supported catalysts composed of a combination of copper oxide-titanium oxide and copper oxide-chromium oxide, respectively. These catalysts were not satisfactory in terms of catalytic activity, resistance to poisoning, side reactions, etc.

As described above, an improved method which does not have various drawbacks associated with the conventionally known methods for removing CO, O ₂ and CO ₂ from olefins, that is, high catalytic activity,
And an improved purification method of olefins using a novel catalyst capable of removing the CO, O ₂ and CO ₂ contained in the olefins while maintaining its activity for a long period of time and without accompanying adverse side reactions Development is required.

[0008]

In the above-mentioned conventional technique, trace amounts of CO and O _{2 in} olefins used for polymerization are used.
And of CO _2, particularly trace CO gas phase, 80 ° C. or higher high-temperature copper oxide - but for oxidized and removed as by using a catalyst of the zinc oxide-based carbon dioxide is typically carbon dioxide produced is adsorbed and removed Therefore, it is not always efficient because some olefins may be polymerized on the catalyst due to the high temperature because it cannot be removed by another method.
_In order to remove ₂ , a partially reduced copper oxide-zinc oxide catalyst is required, and trace amounts of CO and O in olefins are required.
_It has the drawback that it is difficult to adsorb ₂ and CO ₂ at the same time. In addition, there is an economical problem that the energy cost is high because the temperature is kept high during operation. Therefore, the present invention does not have such a problem, and provides a method for purifying olefins by efficiently catalytically adsorbing and removing CO, O ₂ and CO ₂ which are present in trace amounts in olefins under gas phase conditions at low temperatures. The purpose is to do.

[0009]

[Means for Solving the Problems] The above-mentioned problem is achieved by "contacting an olefin containing at least a trace amount of carbon monoxide, oxygen or carbon dioxide gas with Raney copper at a low temperature under a gas phase condition. , A method for purifying olefins characterized by catalytically removing a trace amount of carbon monoxide, oxygen and carbon dioxide.

The present invention will be described in detail below. Coordination anionic polymerization catalysts for producing polyolefins are composed of transition metal compounds such as titanium tetrachloride, titanium trichloride, vanadium oxychloride and the like and organometallic compounds such as alkylaluminum compounds such as triethylaluminum, triisobutylaluminum and diethylaluminum. Although it was a binary catalyst, recently, a complicated catalyst system to which various third components are added and a supported catalyst supporting the above-mentioned transition metal compound have been developed. In particular, as a catalyst for polypropylene, a combination of titanium trichloride obtained by reducing titanium tetrachloride with aluminum and diethylaluminum chloride has been mainly used, but after that, a third component catalyst containing a stereoregularity improving agent was added. Highly stereoregular catalysts such as titanium trichloride obtained by reduction of titanium tetrachloride with alkylaluminum together with complexing agents, and ultrahighness by the combination of titanium trichloride supported on magnesium chloride with triethylaluminum and electron donors. Active catalyst systems are being used.

Olefin such as ethylene and propylene produced by pyrolyzing petroleum contains impurities such as hydrogen and unsaturated hydrocarbons such as acetylene, CO, O ₂ and CO _2. CO, O ₂ and CO ₂
When the olefins are polymerized, the above-mentioned polymerization catalyst is poisoned, so that CO, O ₂
And that CO ₂ remains is not desirable. For example, CO or O ₂ in olefins is several mol ppm (hereinafter
(ppm means mol ppm) When present, the activity of the polymerization catalyst is significantly impaired and, in some cases, the catalytic activity may be lost. In particular, the influence of CO or O ₂ is very large in the ultra-high activity polymerization catalyst which has recently come into common use. C
Effect of O ₂ is not a higher CO or O _2. Therefore, when polymerizing olefins using such a catalyst, it is necessary to make the olefins as raw materials highly pure, and usually CO or O ₂ is 0.1 ppm or less, that is, the detection limit or less. It is necessary. It is also preferable that CO ₂ is also removed. At present, trace amounts of CO, O ₂ and CO ₂ in olefins are usually removed separately. That is, a small amount of CO is usually adsorbed and removed, or is oxidized and converted into a substance having a relatively small influence such as carbon dioxide to be removed, and a small amount of O ₂ is usually adsorbed and removed. Further, CO ₂ is removed by an adsorption method or an absorption method if necessary.

The olefins used in the refining method of the present invention are olefins for polymerization produced by thermal decomposition of petroleum, and include butenes, pentenes, methylpentenes and the like in addition to ethylene and propylene. can give.
These olefins produced by the thermal decomposition of petroleum usually contain trace amounts of CO, O ₂ , CO of several ppm to several tens of ppm.
Contains ₂ . Among these olefins,
It is preferable to apply the method of the present invention to ethylene or propylene.

The concentrations of trace amounts of CO, O ₂ and CO _{2 in} the raw material olefins used in the present invention are preferably 30 ppm or less, more preferably 10 ppm or less. If the raw olefins contain more than 30ppm CO,
When O ₂ and CO ₂ are contained, it is desirable to previously reduce the concentration to 30 ppm or less by another method.

The catalytic adsorbent Raney copper (hereinafter abbreviated as R-Cu) used in the method of the present invention is based on known literature.
It is defined as follows. That is, aluminum (Al),
It is defined as a metal adsorbent obtained by producing an alloy of a metal soluble in an alkali or an acid such as silicon (Si) and zinc (Zn) and a metal hardly soluble in an alkali or an acid and then developing the alloy. Of the R-Cu, Al is usually used as a metal soluble in an alkali or an acid. R-Cu
For example, when the alkali- or acid-soluble metal is Al, a Cu alloy containing 30 to 70% by weight of Al (which may contain a small amount of a metal other than Cu) is used as an appropriate particle size. After crushing into, using a method of expanding with an alkali or an acid, or a method of expanding after melted Raney copper alloy is produced by rapid solidification using water atomization, rotary water atomization, gas atomization, etc. to produce alloy particles Has been done. At this time, the deployment method used is alkali,
A method of developing with acid or steam is used. Sodium hydroxide is frequently used as an alkali because of its efficiency and economy.

Usually when R-Cu is used as a catalyst,
The particle size is 10 to 20 μm, and the Al concentration in the metal Cu is about 0.5 to 5% by weight. The contact adsorbent used in the method of the present invention is such fine particles and low Al. A concentration of R-Cu may be used, but a grain size of 0.5 mm or more and a high Al concentration of 8 to 30% by weight are preferable. The reason is that it is considered preferable to use the contact adsorbent as a fixed bed as the usage form of the adsorbent in the method of the present invention.

Practical R-having such a particle size and composition
For example, Cu is manufactured through the following steps. Raney copper alloy production process An alloy in which Al and Cu are mixed in a weight ratio of 50/50 is produced, and the molten alloy is rapidly solidified by a rotating disc method or an underwater dropping method in an inert gas atmosphere, and a solid Raney alloy is produced. Cu
Manufacture alloys. By selecting the manufacturing conditions, a massive Raney Cu alloy with a yield of 0.5 to 6 mm can be obtained. Development Step A predetermined block Raney Cu alloy is put into a development tank containing an aqueous sodium hydroxide solution of 5 to 15% by weight, and development is carried out within a development temperature range of 30 to 60 ° C. It is important to control the temperature because the development is accompanied by the generation of hydrogen and is an exothermic reaction. After the completion of the washing step, washing is performed using deoxygenated pure water. The washing is performed until the pH of the washing liquid becomes 9-11. Through the steps from to, R-Cu in a state of being immersed in water is obtained. Since the surface of R-Cu is likely to be oxidized when it comes into contact with oxygen or an oxygen-containing gas, it is preferable to carry out each step in an inert gas atmosphere and to cut off contact with air as much as possible.

As a Raney Cu alloy used as a raw material, a crystalline phase CuAl ₂ (Cu / Al) identified by powder X-ray diffraction is used.
An atomic ratio of 0.5 is shown. ) Is preferably used, and this crystal phase is developed with an aqueous alkali solution to form Al.
It is said that the porous and active metal Cu is generated by elution of Cu. That is, in order to form the crystal phase CuAl ₂ , it is preferable to produce an alloy on the Al excess side in terms of atomic ratio (Cu / Al atomic ratio is 0.5 or less).
A composition with an Al weight ratio of 50/50 is advantageous.

As R-Cu used in the method of the present invention, metallic Cu is used under mild development conditions in the expansion step.
The Al concentration in the medium is 8 to 30% by weight, more preferably 10
Those in the range of up to 20% by weight can be preferably used. The mechanical strength of R-Cu is highly dependent on the Al concentration, and the lower the Al concentration, the lower the strength. When the Al concentration is 8% or less, it becomes difficult to use the adsorbent as a fixed bed, and when the Al concentration is 30% or more, the strength is sufficient, but effective metal Cu decreases, so that performance is deteriorated. It loses practicality.

As a method for producing Raney Cu alloy, Cu / A
There is also a method in which an alloy ingot with a weight ratio of 50/50 is manufactured, and then mechanically crushed and sieved to collect a lump of 0.5 to 6 mm, but the yield of crushing is poor and the generated fine particles are discarded. As a method for producing the massive Raney Cu alloy, there is no problem in terms of performance, but there is an economical disadvantage. As a method for producing the massive Raney Cu alloy, it is preferable to use a rotating disk centrifugal atomizing method or an underwater dropping method.

As a route for removing a trace amount of CO in olefins by the method of the present invention, adsorption by Al on the surface of a porous metal Cu having a large effective surface area generated by expansion, and R-Cu. It is presumed that CO ₂ is generated by the oxidation of adsorbed CO due to active oxygen existing on the surface. It is known that CO ₂ is adsorbed on the active Cu surface in the pathway in which adsorbed CO is oxidized and CO ₂ is produced, and it is considered that CO ₂ is adsorbed as it is. Of course, it is expected that the trace amount of CO ₂ originally present in the olefins will also be adsorbed and removed by this route.

Further, R-Cu itself is usually produced from the manufacturing stage.
Cut off contact with oxygen as much as possible, and handle afterwards as much as possible
It is handled in a force-inert gas atmosphere, but the effect of adsorbed oxygen is
Not negligible, some are amorphous Cu oxides (usually Cu₂ 
Exists as O). However, this Cu₂ The oxygen in O is active
It seems that it is effective for the oxidation of adsorbed CO. Also olefin
Trace O in class₂ For the adsorption on the active Cu surface and
Amorphous Cu₂ Thought to be removed by adsorption route on O surface
To be That is, the contact adsorption remover used in the method of the present invention
R-Cu is mainly porous metal Cu, amorphous oxide
Cu (mainly Cu₂ O) and Al (Al₂ O₃ ・ XH
₂ O form and presumed), and the combination
Therefore, trace amounts of CO and O in olefins₂ And CO₂ But
Estimated to be efficiently and simultaneously removed by contact adsorption
It

In the method of the present invention, catalytic adsorption of olefins containing trace amounts of CO, O ₂ and CO ₂ and R-Cu is usually carried out by a gas phase method. Contact temperature is usually 0-80
C., preferably 10 to 50.degree. Generally, in the case of a copper oxide type catalyst, a trace amount of CO is produced in a low temperature range of 50 ° C or lower.
It is said that the removal rate is slow and not practical. In the case of R-Cu of the present invention, sufficient CO even in a low temperature range near room temperature,
It has a catalytic removal rate of O ₂ and CO ₂ . Further, when the temperature of the copper oxide-based catalyst exceeds 100 ° C., although it is a small amount, oxidation or polymerization of olefins is likely to occur, which is disadvantageous. In this respect as well, R-Cu active at low temperature is advantageous. In the case of contacting by a gas phase method, the space velocity of olefins is preferably in the range of 1,000 to 10,000 hr ^-1 , and the pressure at the time of contact is not particularly limited, but it is from normal pressure to 6
It can be appropriately selected within the range of 0 atm.

When the method of the present invention is carried out industrially, a system in which R-Cu as an adsorbent is used as a fixed bed and olefins are caused to flow through the packed bed in an upflow or a downflow is advantageous. or,
It is preferable that the contact adsorption tower is a double tower type and a continuous type by a switching type.

CO by contact in the method of the invention,
R-Cu whose catalytic adsorption ability for O ₂ and CO _{2 has} decreased is
It can be easily regenerated by calcining at a temperature of 80 to 200 ° C. in the presence of molecular oxygen-containing gas such as air or oxygen, and then reducing with a reducing gas such as hydrogen at a temperature of 50 to 150 ° C. .

By the method of the present invention, trace amounts of CO, O ₂ and CO ₂ contained in olefins can be efficiently catalytically adsorbed and removed. The olefins from which CO, O ₂ and CO ₂ have been removed by the method of the present invention can be directly used as a polymerization raw material.

[0026]

EXAMPLES The present invention will now be described in more detail with reference to Examples. Example 1 A trial R-Cu was used as a contact adsorbent. This R-Cu
Is an alloy having a Cu / Al weight ratio of 50/50 manufactured by a conventional method, then crushed to recover an alloy having a particle size of 0.5 to 1.2 mm, and developed and prepared using an aqueous sodium hydroxide solution. . The composition after development is Cu83-Al17% by weight, and is stored in a state of being immersed in water to avoid contact with air. When R-Cu was used, it was drained and then sufficiently dried under reduced pressure at 40 ° C. before use. 12.5 ml of this dried R-Cu was added to a reaction tube (SU
S), and a catalytic removal test of CO, O ₂ and CO ₂ in ethylene (C ₂ H ₄ ) was conducted under the following reaction conditions and a catalyst fixed bed flow method.

Reaction conditions Reaction temperature; 30 ° C. Reaction pressure; 5 kg / cm ² G space velocity (SV); 3000 hr ⁻¹ CO concentration in C ₂ H ₄ ; 26 ppm O ₂ concentration; 2 ppm CO ₂ concentration; 2 ppm C ₂ H _For CO and carbon dioxide (CO ₂ ) in ₄ , the CO and CO ₂ were separated by gas chromatography, and after CO and CO ₂ were completely converted to methane (CH ₄ ) through a methanator, the CH ₄ was usually converted into Was detected by a hydrogen flame ionization detector (FID), and quantified. CO by this method
The detection limits for CO ₂ and CO ₂ were 0.03 ppm. Also, C
O _{2 in 2} H ₄ is trace O ₂ analyzer (O ₂ detection limit 0.0
1 ppm) for analysis. As a result of carrying out the reaction for 2 hours,
The CO, O ₂ and CO ₂ concentrations in the reactor outlet C ₂ H ₄ were all below the detection limit, and formation of C ₂ H ₄ oligomers was not observed.

Example 2 Spherical R-Cu was used as a contact adsorbent. This RC
u is a spherical alloy with a Cu / Al weight ratio of 50/50 (particle size 1.
5 to 2.0 mmφ) was produced by a rotating disk centrifugal atomization method, and then developed and prepared using an aqueous sodium hydroxide solution. The composition after development is Cu83-Al17% by weight and is stored in a state of being immersed in water. This spherical R-
A contact removal test of CO, O ₂ and CO ₂ in C ₂ H ₄ was conducted in the same manner as in Example 1 using 12.5 ml of a dried Cu product. As a result of carrying out the reaction for 2 hours, the concentrations of CO, O ₂ and CO _{2 in the} reactor outlet C ₂ H ₄ were all below the detection limit, and formation of C ₂ H ₄ oligomers was not observed.

Example 3 The same R-Cu as in Example 1 was used as a contact adsorbent, and C ₂
CO, O ₂ and CO ₂ concentrations in H ₄ are all 2 ppm,
The reaction conditions were the same as in Example 1 except that the SV was 6,000 hr ^-1.
A contact removal test for CO, O ₂ and CO ₂ in C ₂ H ₄ was conducted in the same manner as in. As a result of carrying out the reaction for 2 hours, the concentrations of CO, O ₂ and CO _{2 in the} reactor outlet C ₂ H ₄ were all below the detection limit.

Example 4 The same spherical RC as used in Example 2 as a catalytic adsorbent
u is used, but the expansion rate is changed and the composition is Cu72 after expansion.
-Al 28% by weight was used. Dried spherical R-
Using Cu12.5ml, C ₂ H ₄ in CO, O ₂ and CO ₂ all concentrations in the same reaction conditions as in Example 1 except that the 2ppm in C ₂ H ₄ CO, O ₂ and CO ₂ The contact removal test was conducted. As a result of carrying out the reaction for 2 hours, the CO concentration in the reactor outlet C ₂ H ₄ was 1.62 ppm,
The O removal rate was 19%. The O ₂ and CO ₂ concentrations were below the detection limit.

Comparative Example 1 As the catalytic adsorbent, a CuO-ZnO type catalyst (G-66D manufactured by Nissan Gardler Catalyst Co., Ltd.) which is industrially used as a high temperature active type catalyst was used. Crushed and particle size 0.5
The reaction conditions were the same as in Example 3 using 25 ml of a catalyst of ~ 1.2 mm, and CO, O ₂ and CO _{2 in} C ₂ H ₄ were used.
The contact removal test was conducted. As a result of the reaction, the concentrations of CO, O ₂ and CO _{2 in the} reactor outlet C ₂ H ₄ were around 2 ppm, and the removal ability was low.

Example 5 The same adsorbent used in Example 1 was used as the catalytic adsorbent, the reaction conditions were exactly the same as in Example 1, and C ₂ H _{4 was used.}
A continuous reaction of CO catalytic removal in was carried out. 300 in succession
The reaction was carried out for a time, but the C in the reactor outlet C ₂ H _{4 was}
O, O ₂ , and CO ₂ concentrations were below the detection limit during this period. In addition, formation of C ₂ H ₄ oligomers was not detected.

[0033]

Industrial Applicability According to the method of the present invention, catalytic removal of a trace amount of CO, O ₂ and CO ₂ in olefins can be efficiently carried out in a gas phase and at a low temperature by using R-Cu.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Tadakuni Kitamura 573 Ushijima, Kasukabe City, Saitama Prefecture Nissan Guarder Catalyst Co., Ltd. Kasukabe Laboratory (56) References Japanese Patent Publication No. 25-25443 (JP, B2) Areas (Int.Cl. ⁷ , DB name) C07C 7/12 C07C 11/02-11/113

Claims (3)

(57) [Claims] 1. A trace amount of carbon monoxide, oxygen and oxygen is obtained by contacting an olefin containing at least a trace amount of carbon monoxide, oxygen or carbon dioxide gas with Raney copper under a gas phase condition at a low temperature. A method for purifying olefins, which comprises removing carbon dioxide by contact adsorption. 2. The olefin according to claim 1, wherein the Raney copper having a composition after expansion of the Raney copper alloy is in the range of 8 to 30% by weight of aluminum and 92 to 70% by weight of copper is used. Purification method. 3. A trace amount of carbon monoxide as an olefin,
The method for purifying olefins according to claim 1 or 2, characterized in that ethylene or propylene containing either oxygen or carbon dioxide is used.