JP2017071579A - Method for refining olefin for removing impurities included in olefin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To develop a method of removing and refining carbon dioxide in an olefin raw material capable of economically, simply and efficiently conducting removal of carbon dioxide which is an impurity from the olefin raw material and supplying a sufficiently refined monomer raw material to an olefin polymerization.SOLUTION: Olefin containing carbon dioxide and an acethylene-based compound as impurities is contacted with a hybrid absorbent consisting of a mixture of active alumina and zeolite to remove carbon dioxide and the acethylene-based compound.SELECTED DRAWING: None

Description

  The present invention relates to a method for purifying an olefin raw material, and particularly relates to a method for purifying an olefin in which impurities carbon dioxide and acetylene contained in the olefin are removed by a special adsorbent.

In recent years, the demand for olefins used as basic raw materials for the petrochemical industry is rapidly increasing, particularly as raw materials for polyolefin production.
In general, propylene and ethylene as industrial raw materials are produced by thermal decomposition of hydrocarbons, separation of C3 fraction obtained from catalytic cracking products of heavy oil, and the like.
However, the industrial olefin thus obtained usually contains various impurities such as carbon monoxide, carbon dioxide, and acetylene. These impurities have the effect of poisoning the active sites of polymerization catalysts such as transition metal catalysts typified by metallocene catalysts, and cause problems such as a reduction in catalyst efficiency. Therefore, studies for removing these impurities have been made for some time.

  Low molecular weight impurities such as carbon monoxide in olefins are separated and removed in the light boiling removal tower in the raw material purification process, but carbon dioxide has a molecular weight close to that of propylene and is difficult to separate in the light boiling removal tower. Therefore, it was necessary to remove it using a purified catalyst (adsorbent).

Generally, methods for selectively removing a trace amount of harmful components contained as impurities in a mixed gas can be broadly divided into a physical adsorption method (referred to as “physical removal method”) and a chemical reaction. It is divided into a method (called “chemical removal method”).
Specifically, as a method for removing carbon dioxide as an impurity in industrial olefins, the following removal methods have been proposed.

Active alumina is known as the most common purification catalyst (adsorbent) for removing carbon dioxide (see Patent Document 1), and is currently being applied to olefin purification.
In addition, studies are being made on improving the performance of activated alumina. For example, an adsorbent comprising activated alumina carrying an alkali metal oxide, hydroxide, nitrate, acetate, etc. is being developed (patent) Reference 2).

  However, since adsorption by activated alumina is a chemical removal method that mainly involves chemical reaction, the active sites in the adsorbent change in a relatively short period of time with use, and the performance does not recover even after regeneration. The short life was a difficult point.

  Moreover, as a method for removing carbon dioxide by a physical removal method, for example, a removal method using a catalyst (for example, containing zeolite, alumina, or a metal precursor) containing zeolite (molecular sieve) as a main component can be cited ( However, the removal efficiency was not always sufficient.

  Therefore, although removal of carbon dioxide in olefins by these known purification catalysts shows a certain effect, there is still room for improvement in the adsorption performance.

JP-A 63-240915 US Pat. No. 4,493,715 JP 2002-253959 A Special table 2010-505033 gazette

Conventionally, industrial olefin raw materials produced by various methods usually contain carbon dioxide, acetylene, sulfur impurities, and the like. In order to use this industrial olefin as a raw material monomer for polymer production, the contained carbon dioxide is removed to a concentration level below 5 volppm, sometimes to a level below 1 volppm, and a transition metal catalyst is obtained. It is necessary to prevent poisoning of the polymerization catalyst such as.
As described above in the background art, the conventional carbon dioxide removal method uses activated alumina or molecular sieve as a purification catalyst, but it is sufficient for transition metal catalysts that are easily affected by impurities such as carbon dioxide. Purification could not be said.

  Accordingly, the present invention provides a method for removing and purifying carbon dioxide in an olefin raw material, which is economical, simple and efficient when supplying carbon dioxide from an olefin raw material and can supply a monomer raw material sufficiently purified for olefin polymerization. It is a problem to be solved by the invention.

  In order to solve the above-described problems of the present invention, the present inventors tried to consider a method for removing and purifying carbon dioxide from an olefin raw material by using various purification catalysts (adsorbents), and adopted a specific adsorbent. Thus, the inventors have found that the problems of the present invention can be solved, and have created the present invention.

  That is, the present invention has been made in view of the above-described conventional technology and its problems. In order to use olefins such as propylene and ethylene as raw material monomers for polymer production, in these raw material monomers, transition metals are used. This is a simple and efficient method that can reduce carbon dioxide that poisons a polymerization catalyst such as a catalyst to a content that does not adversely affect the polymerization catalyst.

In the present invention, specifically, as a main requirement of the invention, a hybrid adsorbent composed of a mixture of activated alumina and zeolite is used, and impurities in olefins, particularly propylene and ethylene, which cause catalyst poisoning. It is possible to remove carbon dioxide as more efficiently and reliably than in the past.
Therefore, according to the first invention of the present invention (basic invention; claim 1), an olefin containing carbon dioxide as an impurity is mixed with a hybrid adsorbent comprising a mixture of activated alumina and zeolite (hereinafter simply referred to as “hybrid adsorbent”). And a method for purifying olefin, which is characterized by removing carbon dioxide as an impurity.
In the present invention, in addition to the feature of adsorption and removal of carbon dioxide by a hybrid adsorbent, acetylene compounds such as acetylene as impurities, particularly acetylene compounds of 5 volppm or less can be removed simultaneously. This is the second feature of the invention.

Here, the hybrid adsorbent composed of a mixture of activated alumina and zeolite is a conventionally known adsorbent, but for purification of hydrocarbons, ethers and alcohols from butene hydrocarbons in the C4 fraction are used. It is only used in a method for removing oxygen-containing compounds such as JP-A-2010-095494 and JP-A-2010-095495. The above-mentioned requirement (specific matter of the invention) for carrying out carbon dioxide removal purification cannot be found.
In JP 2002-253959 A mentioned above as the prior art, it seems that the hybrid adsorbent has the ability to remove carbon dioxide. However, the present invention is not limited to the carbon dioxide which is an impurity, but acetylene such as acetylene as an impurity. It can be said that this compound is a novel invention which can be removed at the same time from the conventional technology.
In the present invention, as demonstrated by the examples described later, in the removal of carbon dioxide and acetylenic compounds as impurities, the present invention shows extremely excellent performance with respect to conventional known purification catalysts (adsorbents). .

  As embodiment inventions (each invention of the dependent claims) accompanying the basic invention of the present invention described in paragraph 0014, as a second invention, the hybrid adsorbent is pretreated at a temperature of 100 to 650 ° C. in advance. In the olefin purification method according to the first aspect of the invention, the third aspect of the invention is that the activated alumina has a pore diameter of 1 to 100 nm and the zeolite has an average pore diameter of 0.2 to 1 nm. The method for purifying olefins in the first or second invention, characterized in that, as the fourth invention, the contact temperature with the hybrid adsorbent is 0 to 100 ° C. The olefin purification method according to the third invention is characterized in that, as a fifth invention, the contact treatment with the hybrid adsorbent is performed in two or more stages, and the oleophore in the first to fourth inventions. This is a method for purifying fins.

  Furthermore, as a sixth invention, the olefin is propylene and / or ethylene, the olefin purification method according to the first to fifth inventions, the seventh invention as a purification method (ii) A method for purifying olefins according to the first to sixth inventions, characterized by using a contact treatment with any one or more of molecular sieve, (b) metal oxide, and (c) activated alumina. The invention is characterized in that the olefin purification method according to the first to seventh inventions is characterized in that the concentration of carbon dioxide is reduced to 10 volppm or less in advance by other means. In the first to eighth inventions, the propylene and / or ethylene is purified by the olefin purification method, and the propylene and / or ethylene is further polymerized. To a polymerization process of propylene and / or ethylene.

The present invention eliminates the use of a conventional purification catalyst when removing carbon dioxide from an olefin raw material, can be carried out economically, simply and efficiently, and at the same time, can also remove acetylenic compounds, and is a sufficiently purified monomer for olefin polymerization. This is a method for removing and purifying carbon dioxide from an olefin raw material that can supply the raw material.
Specifically, according to the present invention, olefins purified by removing carbon dioxide and acetylenic compounds, particularly propylene and ethylene, can be used as monomers for polymerization catalysts that are weak against impurities, such as metallocene catalysts, polyethylene, Polypropylene homopolymers, propylene / α-olefin copolymers, propylene block copolymers, and the like can be produced with stable catalyst efficiency without catalyst poisoning.

  Hereinafter, the present invention will be described in detail and specifically with respect to raw material olefins, hybrid adsorbents, purification treatment methods, and the like according to the claims of the present invention.

[I] Raw Olefin As the olefin used as a raw material in the present invention, an industrial olefin containing carbon dioxide produced by various methods can be used. It is suitably applied when using industrial ethylene produced by separation of C2,3 fractions obtained from catalytic cracking products and FCC propylene (FCC; Fluid Catalytic Cracking Process).

Carbon dioxide contained in these raw material olefins is preferably applied in the case of 100 vol ppm or less, and more preferably 10 vol ppm or less. If carbon dioxide is contained in the raw material olefin at a concentration exceeding 100 volppm, the carbon dioxide concentration is reduced to 100 volppm or less in advance by other means such as distillation or PSA (Pressure Swing Adsorption) method. It is desirable to keep it.
Further, other impurities contained in the raw material olefin, such as acetylene, is preferably 5 volppm or less, and if it exceeds 5 volppm, it is desirable to reduce the concentration beforehand with another purifying catalyst.

[II] Hybrid Adsorbent (1) Composition of Adsorbent The hybrid adsorbent used in the present invention is a mixture of activated alumina and zeolite, and is usually activated alumina 20 in a total of 100% by weight of activated alumina and zeolite. -80 wt% and zeolite 80-20 wt%, preferably a mixture of activated alumina 30-70 wt% and zeolite 70-30 wt%.
As described above in paragraph 0015, such a hybrid adsorbent is a conventionally known adsorbent, and a commercially available hybrid adsorbent may be used.
Usually, since the raw material olefin contains impurities other than carbon dioxide (for example, H ₂ O, CO, COS, acetylene compounds, etc.), it is preferable to perform pretreatment and post-treatment prior to the hybrid adsorbent treatment. For example, an adsorption column filled with molecular sieves, metal oxide, activated alumina, or the like is separately used before and after the adsorption column filled with the hybrid adsorbent, and these impurities can be removed.

  The activated alumina that constitutes the hybrid adsorbent is the one obtained by transferring alumina hydroxide to porous aluminum oxide with low crystallinity to give adsorption ability, and has a high specific surface area and high pore volume and is excellent. Has adsorption capacity. The activated alumina may be a commercially available product, or may be produced by a known method.

The average pore diameter of the activated alumina is usually 1 to 100 nm, preferably 1 to 80 nm. The average particle diameter of the activated alumina is not particularly limited, and it is preferable that the average pore diameter is in the above range because highly polar impurities such as water and alcohol can be adsorbed efficiently.
Although it does not restrict | limit especially as a preferable activated alumina, (gamma) -alumina etc. are mentioned.

The zeolite constituting the hybrid adsorbent can be synthesized and produced by a known method.
The average pore diameter of the zeolite is usually 0.2 to 1 nm, preferably 0.5 to 1 nm. The average particle diameter of the zeolite is not particularly limited, and it is preferable that the average pore diameter is in the above range because various impurities including carbon dioxide can be adsorbed efficiently.

Although it does not restrict | limit especially as a preferable zeolite, Zeolite X, Y, A, etc. are mentioned, Especially preferably, zeolite X is mentioned. (In addition, these various zeolites are common names as types of zeolite and are well known.)
If the olefin contains many polar impurities such as water and alcohol, these impurities are adsorbed on the hybrid adsorbent in preference to carbon dioxide, so zeolite (Molecular Sieves) etc. It is preferable to use the adsorbent in front of the hybrid adsorbent.
The average particle size of the single zeolite used in combination with the hybrid adsorbent is not particularly limited, but the average pore size is preferably within the above-mentioned range.

(2) Shape of adsorbent The shape of the adsorbent used in the present invention is not particularly limited, and may be formed into pellets, powders, granules, drops, disks, or the like. What is necessary is just to select the shape of an adsorbent suitably according to a use aspect, and the magnitude | size can also be suitably selected according to use conditions.

[III] Treatment conditions (1) Pretreatment of hybrid adsorbent (activation treatment)
The hybrid adsorbent of the present invention is preferably heat activated as a pretreatment.
The pretreatment (activation treatment) of the hybrid adsorbent in the present invention is a heat treatment, and the temperature thereof is 100 to 650 ° C., preferably 200 to 600 ° C., more preferably 300 to 600, under an inert gas flow. ° C, most preferably 400-600 ° C. When the pretreatment temperature is within this range, the zeolite crystals are not severely collapsed and the removal efficiency is appropriate. Nitrogen, argon, helium, etc. can be used as the inert gas.

(2) Contact temperature between olefin and hybrid adsorbent The contact temperature of the present invention is 0 to 100 ° C, preferably 10 to 60 ° C, more preferably 20 to 50 ° C. When the treatment temperature is within this range, in the case of a liquefied olefin, the treatment operation is efficient without vaporization. In the case of gaseous olefins, there is no concern that side reactions will occur.

(3) Contact time between olefin and hybrid adsorbent The contact time of the present invention is appropriately selected according to the carbon dioxide concentration in the olefin, the amount of the hybrid adsorbent, the contact temperature, the contact pressure, and the like. Usually, it is 1 minute to 100 hours, preferably 5 minutes to 80 hours.

(4) Contact pressure between olefin and hybrid adsorbent The contact pressure of the present invention can be carried out at normal pressure, but it is also carried out under a pressure of 0.2 to 5 MPa, preferably 0.5 to 4 MPa. Can do.

(5) Contacting method of olefin and hybrid adsorbent As the contacting method of the present invention, olefin is usually contacted in a gaseous state, but is not limited to this, and in the case of propylene, it is contacted in liquid form. May be. The filling mode of the hybrid adsorbent may be appropriately selected according to the shape of the contact tower, and a fixed bed is generally used, but it can also be packed as a moving bed, a fluidized bed or the like.

(6) Supplementary treatment with other adsorbents In the polymerization of olefins by a catalyst that is easily affected by impurities such as metallocene catalysts, in order to lower the carbon dioxide concentration, the olefin is a hybrid comprising the mixture of activated alumina and zeolite of the present invention. It is very useful to carry out the contact treatment with a system adsorbent, but it can also be said to be contact with various conventional additional catalyst parts that can be added, (b) molecular sieve contact, (b) metal oxide contact, and (c) ) It is beneficial to perform contact in combination with activated alumina contact so that various impurities other than carbon dioxide can be removed. One or more of these combined contacts may be combined arbitrarily.

An example of such an embodiment using so-called combined contact is as follows.
(1) Combined contact with hybrid adsorbent after molecular sieve contact (2) Combined contact with hybrid adsorbent after metal oxide contact (3) Composite metal oxide or metal oxide after hybrid adsorbent contact Combined contact with oxide (4) Contact with hybrid adsorbent after contact with metal oxide or composite oxide of metal oxide, then multistage combined contact with metal oxide or composite oxide of metal oxide (5) Activated alumina After contact, combined contact with hybrid adsorbent

The above-mentioned contact treatment with the hybrid adsorbent and the purification catalyst that can be added can be changed in various combinations in consideration of the properties and quality of the olefin, and the number of times can be arbitrarily set in multiple stages. This is because contact with a hybrid adsorbent composed of a mixture of activated alumina and zeolite exclusively reduces the content of carbon dioxide and acetylenic compounds, whereas this additional purifying catalyst is otherwise It is also beneficial to sequentially reduce the content of impurities that can become catalyst poisons.
Specifically, for example, when ethylene or propylene is used for polymerization, it is remarkably useful in that the activity of the metallocene catalyst is maintained as a whole by detoxifying any catalyst poison.
In this way, olefins typified by ethylene and propylene are preliminarily contacted with various types of refining catalyst parts that can be added such as molecular sieve contact, metal oxide or metal oxide composite oxide contact, and then adsorbed in a hybrid system. Combined contact with the agent is also beneficial. The hybrid adsorbent treatment can be performed in two or three stages, and an optional purification catalyst portion can be provided in multiple stages, and any mode in which the contact before and after the contact is arbitrarily changed can be applied to the technology of the present invention. Included in the range.

[IV] Concentration measurement of carbon dioxide and acetylene compound This is performed by GC / MS analysis (gas chromatography / mass analysis) using a molecular carbon column.

  Hereinafter, the present invention will be described more specifically based on examples, but in contrast to the examples of the present invention and comparative examples, the rationality and significance of the constituent elements of the present invention and the usefulness and superiority of the present invention. It demonstrates the sex.

[Example 1]
As a hybrid adsorbent, 0.5 g of AZ-300 (manufactured by Union Showa) was charged in a U-shaped tube in advance, and pretreatment was performed at 220 ° C. under He gas flow. The adsorptivity of carbon dioxide and acetylene was evaluated by the concentration before and after passing propylene through the adsorbent. As a test gas, propylene gas containing 200 volppm carbon dioxide and 4 volppm acetylene was used.
Propylene gas was allowed to flow for 10 minutes at 30 ° C. at a rate of 60 cc / min through the pre-treated hybrid adsorbent. The passing gas at the time when 10 minutes had elapsed was collected in a sampling bottle and introduced into the GC / MS on-line under a He stream. A packed column (shincarbonST) was used as the GC column. Table 1 shows the carbon dioxide concentration after passing through the adsorbent.

[Example 2]
The test was performed under the same conditions as in Example 1 except that the test gas was propylene gas containing 4 volppm of carbon dioxide and 4 volppm of acetylene. Table 1 shows the carbon dioxide concentration after passing through the adsorbent.

[Comparative Example 1]
The test was performed under the same conditions as in Example 1 except that the evaluation catalyst was changed to 0.5 g of Selexsorb-COS (manufactured by BASF), which is an alumina-based adsorbent. Table 1 shows the carbon dioxide concentration after passing through the adsorbent.

From the results in Table 1, Example 1 evaluates the adsorption performance using propylene gas containing 200 volppm of carbon dioxide, the carbon dioxide concentration after passing through the adsorbent is reduced to 1 volppm, and the acetylene concentration falls below the detection limit. doing. On the other hand, when Comparative Example 1 using a known activated alumina was evaluated under the same conditions, a carbon dioxide concentration of 75 volppm was detected, and the hybrid adsorbent was excellent in removing carbon dioxide and acetylene. I can hear that you have.
Further, Example 2 evaluates the adsorption performance using propylene gas containing 4 volppm of carbon dioxide, the carbon dioxide concentration after passing through the adsorbent is reduced to below the detection limit (0.1 volppm or less), and the acetylene concentration is also detected. Reduced to:
Therefore, the rationality and significance of the constituent elements of the present invention and the usefulness and superiority of the present invention are demonstrated.

The olefin purification method of the present invention can adsorb and remove olefins, particularly ethylene, carbon dioxide and acetylene compounds in propylene, economically simply and extremely efficiently. Therefore, when the purified olefin is used as a monomer, the polymerization catalyst, particularly the metallocene catalyst, is extremely less poisoned, so that production with dramatically stable catalyst efficiency becomes possible.
For these reasons, the production of polypropylene homopolymers, polyethylene homopolymers, propylene / α-olefin copolymers, propylene-based block copolymers, etc., and organic compounds using olefins as contact reaction raw materials (for example, phenol and acrylic acid) Etc.) can be significantly reduced, and its use as a monomer material for polymerization and a raw material for contact reaction is greatly expanded.

Claims (9)

Purification of an olefin characterized by contacting an olefin containing carbon dioxide and an acetylene compound of 5 volppm or less as an impurity with a hybrid adsorbent composed of a mixture of activated alumina and zeolite to remove the carbon dioxide and the acetylene compound. Method. The method for purifying an olefin according to claim 1, wherein the hybrid adsorbent is pretreated at a temperature of 100 to 650 ° C in advance. The method for purifying an olefin according to claim 1 or 2, wherein the activated alumina has an average pore diameter of 1 to 100 nm, and the zeolite has an average pore diameter of 0.2 to 1 nm. The method for purifying an olefin according to any one of claims 1 to 3, wherein the contact temperature with the hybrid adsorbent is 0 to 100 ° C. The method for purifying an olefin according to any one of claims 1 to 4, wherein the contact treatment with the hybrid adsorbent is performed in two or more stages. The olefin purification method according to any one of claims 1 to 5, wherein the olefin is propylene and / or ethylene. Either of (1) molecular sieve, (b) metal oxide, and (c) contact treatment with one or more of activated alumina is used in combination as a purification method. The method for purifying olefins described in 1. The method for purifying an olefin according to any one of claims 1 to 7, wherein the concentration of carbon dioxide is previously reduced to 10 volppm or less by other means. Propylene and / or ethylene is purified by the method for purifying olefin according to any one of claims 1 to 8, and the propylene and / or ethylene is further polymerized. Polymerization method.