JP2002348579A - Method for hydrocarbon mixture separation using zeolite-based separation membrane and method for obtaining separated hydrocarbon by separation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for a hydrocarbon mixture separation, by which a zeolite-based separation membrane is used, the hydrocarbon mixture is stably and efficiently separated into a component rich in a straight-chain hydrocarbon and a component rich in a branched hydrocarbon without causing a decomposition and a chemical reaction and the hydrocarbons are obtained. SOLUTION: This method for hydrocarbon mixture separation using a zeolite- based separation membrane is characterized in that the zeolite-based separation membrane is provided with a zeolite thin film layer on the surface part of a porous substrate, the zeolite thin film layer has pores characteristic of zeolite crystal and pores with <=10 nm pore diameter in a grain boundary.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for separating a hydrocarbon mixture and a method for obtaining a hydrocarbon by separation using a zeolite-based separation membrane.
From the residue obtained after separating olefins and / or diolefins from the distillate containing hydrocarbons having 4 or 5 carbon atoms obtained by cracking naphtha, a linear hydrocarbon-rich component and a branched-chain hydrocarbon Or can be suitably used to obtain a hydrocarbon-rich component in a straight chain and a hydrocarbon-rich component in a branched chain, respectively.

[0002]

2. Description of the Related Art C4-5 olefins and diolefins, which are important basic raw materials in the petrochemical industry, are hydrocarbon fractions having 4C by-produced when ethylene is produced by cracking naphtha. (C4 fraction) or a hydrocarbon fraction having 5 carbon atoms (C5 fraction) by an extractive distillation method. However, the quantity and quality of the C4 fraction and C5 fraction as raw materials are significantly affected by the situation of ethylene supply and demand, and stable production means are required.

[0003] On the other hand, the residue after extractive distillation of the target olefin or diolefin from the C4 or C5 fraction contains paraffin or olefin useful as a raw material for the olefin or diolefin. Nevertheless, it is not used industrially and is consumed as fuel.

[0004] For example, isoprene is one of diolefins useful as a raw material for isoprene rubber and the like, and is currently produced by a method of extracting and distilling a C5 fraction contained at a concentration of 12 to 15%. . However, the residue after the extraction and distillation of isoprene from the C5 fraction contains, as an ingredient that can be converted to isoprene by dehydrogenation, a branched chain compound such as isopentane or methylbutene at an average concentration of 30 to 40% by mass. However, these are currently consumed as fuel without being used. Since the equilibrium constant of the dehydrogenation reaction of isopentane or methylbutene to isoprene is extremely small, if the residue is directly dehydrogenated, the yield of isoprene is low, It is thought to be due to inefficiency.

[0005] Therefore, a method for efficiently separating and concentrating branched hydrocarbons such as isopentane and methylbutene contained in these residues has been desired.

[0006]

SUMMARY OF THE INVENTION The zeolite-based compound is formed by a crystal-specific pore derived from its crystal structure.
For example, it is well known to discriminate between branched and straight-chain hydrocarbons (shape selectivity, molecular sieve action). In recent years, technology development for separating a hydrocarbon mixture using a separation membrane in which such a zeolite-based compound is thinned has been advanced, but the following performance is required.

First, the transmittance of the linear chain is large, and the ratio of the transmittance of the linear chain to the branched chain (permeability coefficient ratio) is large. Here, the transmittance, the transmission coefficient ratio, and the transmission ratio are defined as follows. Transmittance = N / (A × ΔP) (N: permeation amount per unit time, A: transmission area, ΔP: pressure difference between high pressure side and low pressure side) Transmission coefficient ratio = transmittance of substance A / transmission of substance B Rate Permeability ratio = 100 × [weight of component permeated through separation membrane / weight of charged material (permeate + non-permeate)] Second, the zeolite-based separation membrane does not cause chemical change of hydrocarbons. Since zeolite often acts as a solid acid catalyst for hydrocarbons, it is easy for tar to be generated due to chemical changes such as decomposition and polymerization of hydrocarbons, which also leads to deterioration of the performance of the separation membrane. Because.

The present invention has been made in view of the above circumstances, and utilizes a zeolite-based separation membrane to convert a hydrocarbon mixture containing a linear chain and a branched chain from a hydrocarbon mixture containing a linear chain and a branched chain. It is an object of the present invention to provide a method for efficiently separating a component and a hydrocarbon-rich component of a branched chain from each other efficiently.

[0009]

Means for Solving the Problems The present invention, which has solved the above-mentioned problems, relates to a hydrocarbon mixture containing a linear hydrocarbon and a branched hydrocarbon using a zeolite separation membrane. Is separated into a hydrocarbon-rich component of a linear chain and a hydrocarbon-rich component of a branched chain, and, as a membrane permeate, a hydrocarbon-rich component of a linear chain,
A method for obtaining a hydrocarbon-rich component of a branched chain as a membrane non-permeate, wherein the zeolite-based separation membrane has a zeolite thin film layer formed on a surface layer portion of a porous support, and the zeolite thin film layer has It is characterized by having pores specific to zeolite crystals and pores having a pore diameter of 10 nm or less at crystal grain boundaries. The zeolite thin film layer has a molar ratio of alumina to silica (alumina / silica) of 0.1.
It is desirably 0025 (1/400) or less. The hydrocarbon mixture is preferably a residue obtained by separating an olefin and / or a diolefin from a mixture containing a hydrocarbon having 4 or 5 carbon atoms obtained by cracking naphtha, and more preferably a carbon number. Is the residue after separating isoprene from the fraction containing 5 hydrocarbons,
It preferably contains isopentane, methylbutene and linear hydrocarbons.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventors have studied the preparation method, structure, characteristics, etc. of a zeolite-based separation membrane. The zeolite thin film layer has pores specific to zeolite crystals, and a zeolite-based separation membrane having pores having a pore diameter of 10 nm or less at a crystal grain boundary is formed of a linear hydrocarbon and a branched chain. The present inventors have found that they exhibit an excellent separation effect on hydrocarbons, and have completed the present invention.

First, the zeolite-based separation membrane used in the present invention will be described. The zeolite-based separation membrane used in the present invention means that a zeolite thin film layer is formed on a surface layer of a porous support, and the zeolite thin film layer has fine pores having a pore diameter of 10 nm or less at crystal grain boundaries together with pores specific to zeolite crystals. It is characterized by having holes.

Although the pore diameter inherent in the zeolite crystal is not particularly limited, it is desirably 0.3 nm or more, preferably 0.5 nm or more, 1.5 nm or less, and preferably 1 nm or less. The pore diameter of the pores at the crystal grain boundaries in the zeolite thin film layer is 10 nm or less, preferably 8 nm or less, more preferably 5 nm or less. If the average pore diameter at the crystal grain boundary is more than 10 nm, the performance of separating hydrocarbon straight chain and branched chain is reduced. The lower limit of the pores at the crystal grain boundaries is not particularly limited,
It is preferable that the pore diameter is larger than the zeolite crystal-specific pore diameter. In particular, when the pore diameter inherent to the zeolite crystal is less than 1 nm, the pore diameter at the crystal grain boundary is preferably 1 nm or more, more preferably 2 nm or more.

[0013] The pore diameter and pore distribution in the zeolite thin film layer can be determined by a nitrogen adsorption method and / or an argon adsorption method in a micropore region (crystal portion) and a mesopore region (crystal grain boundary portion). The distribution can be measured.

It is not clear why the zeolite-based separation membrane used in the present invention exerts an excellent separation action on hydrocarbon linear and branched chains, but the zeolite thin film formed on the surface layer of the porous support is not clear. The layer has both relatively small pores (less than 1 nm) inherent in zeolite crystals and relatively large pores (1 nm to 10 nm) at grain boundaries,
This is considered to be because high transmittance and high selectivity of linear hydrocarbons can be simultaneously realized. The pores unique to zeolite crystals are fine and have a uniform pore size, so that very high selectivity can be expected, but the transmittance is low. On the other hand, the crystal grain boundaries have poor selectivity due to a large pore diameter, but have high transmittance. In the case of separating small molecules such as an inorganic gas, the presence of a crystal grain boundary significantly lowers the selectivity, so that it does not function as a separation membrane. Is considered to function as a high-performance separation membrane because the transmittance is improved without lowering the selectivity even if there is a grain boundary up to about 10 nm.

In the zeolite thin film layer, 10n
In order to form a separation membrane having relatively large pores of not more than m, it is preferable that the zeolite thin film layer is formed on the surface layer of the porous support and not on the inner layer. When the zeolite thin film layer is formed up to the inner layer portion of the porous support, relatively large pores of 10 nm or less are not formed at the crystal grain boundaries, and the selectivity of the chain structure is equal to or greater than that of the zeolite thin film layer. This is because the transmittance of the chain is reduced.

The thickness of the zeolite thin film layer is 5 μm or more, preferably 10 μm or more and 100 μm or less, preferably 50 μm or less. When the thickness is less than 5 μm, the zeolite thin film layer is easily broken, the effect of providing the zeolite thin film layer is substantially small, and the ability to separate linear and branched is reduced. On the other hand, if it exceeds 100 μm, the film thickness becomes too large, the transmission resistance is large, and conversely, the separation ability tends to be reduced.

The zeolite thin film layer is preferably formed only on the surface layer of the porous support, but a part of the thin film layer is formed on the support in order to prevent separation of the zeolite thin layer from the porous support. It may be formed in the body layer. The thickness of the thin film layer formed on the inner layer portion of the support is preferably 4 μm or less, more preferably 2 μm or less (including 0 μm) from the support surface toward the inside. As described above, when the zeolite thin film layer is formed up to the inner layer portion of the porous support, relatively large pores cannot be obtained at the crystal grain boundaries, and the separation performance is reduced. Also, the formation of the zeolite thin film layer on the inner layer portion should be minimized so as to prevent separation of the zeolite thin film layer from the porous support. When the zeolite thin film layer has excellent adhesion to the porous support and there is no fear of peeling, it is not necessary to particularly form the zeolite thin film layer on the inner layer of the support.

The molar ratio of alumina to silica constituting the zeolite thin film layer is not particularly limited either, but the molar ratio of alumina to silica (alumina / silica)
However, it is desirably 0.0025 (1/400) or less, more preferably 0.00125 (1/800) or less (including the case where alumina is not included at all).

The present inventors have found that the content of the alumina component contained in the zeolite thin film layer affects the transmission coefficient ratio between the branched chain and the straight chain, and when the alumina component increases,
It has been found that the ratio of the permeability coefficient of the straight chain to the branched chain (= the transmittance of the straight chain / the transmittance of the branched chain) is reduced.
In particular, if the molar ratio of alumina to silica (alumina / silica) exceeds 0.0025 (1/400), the ratio of the transmission coefficient of the linear substance to the branched one becomes small, and the separation performance decreases.

The raw materials for forming the zeolite thin film layer are as follows:
There is no particular limitation, and for example, the following raw materials can be used. Examples of the silica source include sodium silicate, sodium metasilicate, potassium metasilicate, sodium orthosilicate, water glass, silica sol, and silicon alkoxide.Examples of the alumina source include aluminum sulfate, aluminum nitrate, aluminum chloride, and sodium aluminate. Sources include sodium hydroxide, potassium hydroxide, cesium hydroxide and the like. Further, as the crystallization accelerator for zeolite, for example, tetrapropylammonium bromide (TPABr), tetrapropylammonium hydroxide, or the like can be used.

Next, the porous support on which the zeolite thin film layer is formed on the surface layer will be described. The porous support is not particularly limited as long as it has a continuous vent, and for example, a porous support having a needle-like pore may be used. Further, it is necessary that the material has high mechanical strength and can be stably present in the hydrothermal treatment and the subsequent heat treatment. For example, ceramics such as alumina, titania, and mullite, metals such as stainless steel and titanium, An alloy, glass or the like can be used, and a porous support such as titania or alumina is preferable. The shape of the porous support may be any shape suitable for separating hydrocarbons, and examples thereof include a film shape, a plate shape, a tubular shape, a cylindrical shape (FIG. 2), and a honeycomb shape.

The method for producing the zeolite-based separation membrane used in the present invention is not particularly limited as long as the zeolite thin film layer is formed on the surface of the porous support. For example, a method of applying a zeolite thin film forming sol, a zeolite precursor or a seed crystal to the surface of a porous support, a method of dipping the porous support in a zeolite thin film forming sol, or the like can be used. When the porous support is immersed in the sol for forming a zeolite thin film, the immersion time is preferably within 30 minutes, preferably within 20 minutes, more preferably within 10 minutes. If the immersion time exceeds 30 minutes, the sol for forming a zeolite thin film permeates into the inside of the porous support, and a zeolite thin film layer is formed inside the support. The immersion time refers to the time from when the porous support is immersed in the zeolite thin film forming sol to when the hydrothermal treatment is started.

Then, a zeolite thin film layer is formed on the surface of the porous support by hydrothermal treatment. The hydrothermal treatment can be performed by immersing the porous support treated with the zeolite thin film layer forming sol in hot water or hot water in an autoclave, or by leaving it in heated steam. The hydrothermal treatment may be performed while the porous support is immersed in the sol for forming a zeolite thin film layer.In this case, the autoclave containing the porous support and the sol for forming a thin film is directly placed in an oven. What is necessary is just to heat. The hydrothermal treatment is performed at 80 ° C.
Above, more preferably 150 ° C. or more and 300 ° C. or less, more preferably 200 ° C. or less, 3 hours or more, more preferably 12 hours or more, 180 hours or less, more preferably 7 hours or less.
It is desirable to carry out for 2 hours or less.

After the above-mentioned hydrothermal treatment, the porous support is taken out, dried, and further subjected to a heat treatment, thereby firing the zeolite thin film layer. The calcination may be performed, if necessary, for 4 hours.
What is necessary is just to heat-process at the temperature of 00 degreeC-800 degreeC for 1 to 10 hours.

In the present invention, a hydrocarbon mixture containing a linear hydrocarbon and a branched hydrocarbon is separated by a chain structure using the zeolite-based separation membrane obtained as described above. To obtain a straight-chain hydrocarbon-rich component and a branched-chain hydrocarbon-rich component.

The hydrocarbon mixture is not particularly limited as long as it contains a straight-chain hydrocarbon and a branched-chain hydrocarbon, and is preferably a hydrocarbon having 4 to 10 carbon atoms.
More preferably, it is a hydrocarbon mixture containing a straight-chain and branched-chain hydrocarbon having 4 to 5 carbon atoms. As the hydrocarbon mixture, for example, a residue obtained by separating olefins and / or diolefins from a fraction containing a hydrocarbon having 4 or 5 carbon atoms obtained by cracking naphtha, more preferably obtained by cracking naphtha It is particularly desirable to use a residue obtained by separating isoprene from a hydrocarbon fraction having 5 carbon atoms. This is because one object of the present invention is to separate and obtain industrially useful straight-chain hydrocarbons and branched-chain hydrocarbons contained in these residues. The method for separating olefins and / or diolefins from a fraction containing a hydrocarbon having 4 or 5 carbon atoms obtained by cracking naphtha is not particularly limited, and examples thereof include extraction, distillation, and extraction distillation. No.

Examples of the linear hydrocarbon having 4 or 5 carbon atoms include linear paraffins such as n-butane and n-pentane; n-butene, n-pentene, n-butadiene and n-pentadiene. Linear olefins and diolefins; branched paraffins such as isobutane and isopentane; and branched olefins and diolefins such as isobutene, methylbutene and isoprene.

In the present invention, for example, a residue obtained by separating an olefin and / or a diolefin from a fraction containing a hydrocarbon having 4 or 5 carbon atoms mainly contains paraffin and / or olefin. Can be separated into a linear paraffin and / or olefin-rich component and a branched paraffin and / or olefin-rich component. In particular,
The residue obtained by separating isoprene from the hydrocarbon fraction having 5 carbon atoms obtained by the decomposition of naphtha contains isopentane, which is an industrially useful raw material for producing isoprene, and methylbutene (mainly 2-methyl-2-butene, 2-methyl-2-butene, -Methyl-1-
Butene and traces of 3-methyl-1-butene) from about 30 to
40% by mass, and it is extremely useful to obtain them separately.

In the present invention, the hydrocarbon mixture can be separated into a straight-chain hydrocarbon-rich component and a branched-chain hydrocarbon-rich component by permeating the above-mentioned zeolite-based separation membrane. it can. At the time of the separation, regardless of whether the linear substance is a paraffin or an olefin, the linear substance permeates the zeolite-based separation membrane in preference to the branched chain substance. ) Is a linear hydrocarbon-rich component, and those that do not permeate through the separation membrane (hereinafter referred to as “non-permeate”) are branched-chain hydrocarbon-rich components. In the present invention, in this way, a hydrocarbon-rich component in a linear chain can be obtained as a membrane-permeable component, and a hydrocarbon-rich component in a branched chain can be obtained as a non-membrane component. it can.

In this separation, the permeated portion (around the zeolite-based separation membrane) is kept at 300 ° C. or less, preferably 50 to 200 ° C.
It is preferable that the non-permeate side be pressurized or the permeate side be depressurized in a temperature range where the hydrocarbon mixture can be separated in a gaseous state. For example, hydrocarbons having 5 carbon atoms, such as isopentane, methylbutene, and isoprene, are liquid at room temperature, but are separated in a gaseous state in a temperature range of 50 ° C. or higher.

In the present invention, it is necessary to separate the hydrocarbon component containing a straight chain and the hydrocarbon component containing a branched chain, and at the same time, inevitably concentrate the straight chain or the branched chain contained in each component. Thus, a straight-chain hydrocarbon-rich component and a branched-chain hydrocarbon-rich component are obtained. In the present invention, the term "enriched in a linear or branched chain" means that a hydrocarbon of interest is concentrated by being separated, and the molar fraction of the linear or branched chain in each component after the separation treatment is increased. Means that the fraction is higher than the molar fraction in the hydrocarbon mixture used. In the present invention, the content of the linear or branched chain in each component after separation is not particularly limited, but the molar fraction of the linear or branched chain in each component after the separation treatment is not limited. The ratio is preferably 0.4 or more, more preferably 0.6 or more, and still more preferably 0.9 or more.

For example, when a hydrocarbon mixture containing a branched chain hydrocarbon and a straight chain hydrocarbon and having a mole fraction of 0.3 of the branched chain is separated by the zeolite-based separation membrane, the branched chain is separated. And a permeate enriched to a linear fraction having a molar fraction of 0.9 or more can be obtained at the same time. When a hydrocarbon mixture containing isopentane, methylbutene and a linear hydrocarbon is used as the hydrocarbon mixture to be separated, a hydrocarbon component rich in isopentane and methylbutene and a hydrocarbon component rich in linear hydrocarbon And can be obtained.

The method of the present invention can be effectively utilized for producing olefins and / or diolefins as described below. That is, using the above-mentioned zeolite-based separation membrane, from the residue obtained after separating the olefin and / or diolefin component from the distillate containing hydrocarbons having 4 or 5 carbon atoms obtained by the decomposition of naphtha, the linear carbonization is performed. After obtaining a hydrogen-rich component and a branched hydrocarbon-rich component, one of the hydrocarbon components can be dehydrogenated to produce an olefin and / or a diolefin. When the purpose is to produce a branched olefin and / or diolefin and a linear olefin and / or diolefin, each of the non-permeate containing the branched chain and the permeate containing the straight chain is used. What is necessary is just to dehydrogenate.

For example, if a component containing paraffin and / or olefin is dehydrogenated, olefin and / or diolefin can be obtained.

The olefins and / or diolefins which can be produced by using the present invention include, for example, linear olefins having 4 to 10 carbon atoms such as butene, pentene and hexene; and 4 olefins such as isobutene, isopentene and neopentene. Branched chain olefins such as butadiene, pentadiene, and hexadiene; and branched chain diolefins such as isoprene;
Preferably it is an olefin and / or diolefin having 4 to 5 carbon atoms, more preferably isoprene.
The resulting olefin or diolefin having 4 to 5 carbon atoms,
In particular, isoprene is an industrially useful raw material for which a stable production means is required. Hydrocarbons having 5 carbon atoms to be separated are liquid at room temperature and thus have excellent handleability. On the other hand, they are vaporized at the separation temperature (50 ° C. to 250 ° C.) and are therefore suitable for separation.

The dehydrogenation reaction may be carried out in a temperature range of 500 ° C. to 600 ° C. using a general catalyst used for hydrocarbon dehydrogenation, for example, an iron-based or platinum-based catalyst. good.

[0037]

EXAMPLES Hereinafter, the present invention will be described in detail with reference to examples. However, the present invention is not limited to the following examples. Are also included in the scope of the present invention.

[Production of zeolite-based separation membrane] Zeolite-based separation membrane 1 (without alumina) In an aqueous solution containing sodium hydroxide and tetrapropylammonium bromide (TPABr), colloidal silica (Cataloid SI-, manufactured by Catalyst Chemicals, Inc.) was used. 30) was added and stirred to prepare a uniform sol for forming a zeolite thin film. Each raw material is such that the composition of the sol is TPABr: Na ₂
O: Si ₂ O: H ₂ O was added so as to have a molar ratio of 0.1: 0.05: 1: 80. A cylindrical alumina porous support (average pore diameter 0.7 μm, porosity 35%) was sealed on the outer surface so that the outer surface did not come into contact with the thin film forming sol. After immersing the alumina porous support in the sol for forming a thin film for 20 minutes, the alumina porous support is transferred to an autoclave together with the sol for forming a thin film, and subjected to a hydrothermal treatment at 170 ° C. for 72 hours to perform the alumina porous support. A zeolite thin film layer was formed on the inner surface of the porous support. Next, the alumina porous support having the zeolite thin film layer formed thereon was washed with water, dried, and calcined at 600 ° C. for 2 hours to obtain a zeolite-based separation membrane.

The zeolite-based separation membrane has a permeation area of 1
It was 3 cm ² , and the formed zeolite thin film layer was confirmed to be silicalite by X-ray diffraction. The thickness of the zeolite thin film layer was 50 μm by scanning electron microscopy, and the portion formed inside the support was 2 μm.

FIG. 1 shows the measurement of the pore distribution of the zeolite thin film layer of the zeolite separation membrane 1 by using both the nitrogen adsorption method (pore area of 1 μm or more) and the argon adsorption method (pore area of 1 μm or less). This shows the result of the measurement. It can be seen that the zeolite thin film layer has pores having a sharp distribution around 0.5 nm and pores having a broad distribution around 2 to 4 nm at the crystal grain boundaries.

The zeolite-based separation membrane 2 was produced in the same manner as the zeolite-based separation membrane 1, except that the permeation area was 22 cm ² .

Zeolite-based separation membrane 3 Alumina porous support was added to sol for forming zeolite thin film.
A zeolite-based separation membrane was formed in the same manner as the zeolite-based separation membrane 1, except that the membrane was immersed under a reduced pressure of 333.2 Pa for 6 hours to form a zeolite thin-film layer up to the inner layer of the support. The zeolite-based separation membrane has a permeation area of 16 cm ² , and the formed zeolite thin film layer has X
Line diffraction confirmed that it was silicalite. The zeolite thin film layer has a thickness of 50 μm, and the portion formed in the support inner layer has a thickness of 10 to 30 μm.
m (15 μm on average).

Zeolite-based separation membrane 4 (silica: alumina = 800: 1) The composition of the sol for forming the zeolite thin film was TPABr: Na
₂ O: Si ₂ O: H ₂ O: Al ₂ O ₃ = 0.1: 0.05:
A zeolite-based separation membrane was prepared in the same manner as for the zeolite-based separation membrane 3, except that the molar ratio was 1: 80: 0.00125.

Zeolite-based separation membrane 5 (silica: alumina = 400: 1) The composition of the sol for forming a zeolite thin film is represented by TPABr: Na
₂ O: Si ₂ O: H ₂ O: Al ₂ O ₃ = 0.1: 0.05:
A zeolite-based separation membrane was prepared in the same manner as for the zeolite-based separation membrane 3, except that the molar ratio was 1: 80: 0.0025.

Zeolite-based separation membrane 6 (silica: alumina = 100: 1) The composition of the zeolite thin film forming sol was TPABr: Na
₂ O: Si ₂ O: H ₂ O: Al ₂ O ₃ = 0.1: 0.05:
A zeolite-based separation membrane was prepared in the same manner as the zeolite-based separation membrane 3, except that the molar ratio was 1: 80: 0.01. Table 1 shows the properties of the zeolite-based separation membranes 1 to 6.

[0046]

[Table 1]

[Measurement of Permeability] Using the zeolite-based separation membrane 1, the non-permeate side was pressurized at 200 ° C. to give n-butane,
A permeation test of isobutane, n-pentane and isopentane was performed. Table 2 shows the measurement results of the transmittance.

[0048]

[Table 2]

From Table 2, it is found that n-butane which is linear and
The transmittance of n-pentane was 2.74 × 10, respectively.
^-8(Mol · s^-1・ M^-2・ Pa^-1), 2.53 × 10^-8(Mol
・ S^-1・ M ^-2・ Pa^-1) And high, branched isobutane,
The transmittance of isopentane was 0.28 × 10
^-8(Mol · s^-1・ M^-2・ Pa^-1), 0.24 × 10^-8(Mol
・ S^-1・ M ^-2・ Pa^-1), Which is much more
It became very low. From these results, the zeolite used in the present invention was
Olyte-based separation membranes are more straightforward than branched hydrocarbons.
Selectively permeates chain hydrocarbons and has excellent separation performance
It became clear that.

[Separation Performance of Hydrocarbon Mixture] Using a zeolite-based separation membrane 1, a hydrocarbon mixture containing a linear chain and a branched chain is converted into a hydrocarbon component rich in a linear chain and a hydrocarbon component rich in a branched chain. Separated into each of the hydrogen components. Table 3 shows the hydrocarbon mixture used and the molar fraction of the branched chain in each component before and after the separation treatment.

[0051]

[Table 3]

Examples 1 to 5 relate to the case where the hydrocarbon mixture to be separated contains isopentane in a molar fraction of 0.11 to 0.49. Since the mole fraction of the branched chain in the non-permeate after the separation treatment is high, and the mole fraction of the branched chain in the permeate is reduced, the hydrocarbon component rich in the branched chain is It was clarified that it was efficiently separated into a hydrocarbon component rich in linear chain. In addition, it is clear that the zeolite-based separation membrane 1 has excellent separation performance between a linear chain and a branched chain in a wide concentration range regardless of the mole fraction of the branched chain in the hydrocarbon mixture to be separated. It became.

Examples 6 and 7 show that the hydrocarbon mixture to be separated is the olefin 2-methyl-2-butene,
This is the case where isoprene, which is a diolefin, is contained.
It has been found that the zeolite-based separation membrane 1 is effective for separating straight-chain and branched-chain hydrocarbons irrespective of the structure of the hydrocarbon to be separated, whether it is paraffin, olefin, or diolefin.

Similarly, using the zeolite-based separation membrane 2, n
A hydrocarbon mixture in which a branched chain prepared by mixing pentane, isopentane and 2-methyl-2-butene has a mole fraction of about 0.4; The composition of each component in the permeate and the non-permeate when the permeate side was decompressed and reduced at 100 ° C. until the pressure reached about 0.7 was analyzed. The analysis results are shown in Table 4.

[0055]

[Table 4]

The mole fraction of the branched chain in the non-permeate is 0.1%.
76, while the molar fraction of linears in the permeate is:
Since it is 0.94, it can be seen that the branched chain (mol fraction 0.41) and the straight chain (mol fraction 0.59) of the hydrocarbon mixture before the separation treatment are respectively separated and concentrated. From these results, according to the present invention, it is possible to separate and concentrate a hydrocarbon mixture containing a linear chain and a branched chain, and to obtain a hydrocarbon-rich component of a linear chain and a hydrocarbon of a branched chain. It has been clarified that each of the components rich in water can be obtained efficiently.

[Influence of Structure of Zeolite Separation Membrane 1] A zeolite separation membrane in which a zeolite thin film layer is formed on the surface layer of a porous support using zeolite separation membranes 1 to 3, and an inner layer of the support The separation performance was compared with the case where the zeolite thin film layer was formed up to the part. As the hydrocarbon mixture, a mixture obtained by mixing n-pentane and isopentane and having a mole fraction of 0.32 was used, and separation was performed at 200 ° C. at a reduced pressure on the permeate side. . Table 5 shows the results of the separation.

[0058]

[Table 5]

In Examples 8 and 9, the table of the porous support was used.
Zeolite separation with zeolite thin film layer formed on the layer
Membrane 1 (permeation area: 13 cm^Two) And separation membrane 2 (transmission surface)
Product: 22cm^Two), And in Comparative Example 1,
Zeolite thin film layer was formed on the inner layer of the porous support
Zeolite-based separation membrane 3 (permeation area: 16 cm^Two)
Was. Transmission ratio and transmission ratio per unit transmission area of Example 8
Has a transmission area of 13 cm ^TwoDespite the comparison
Example 1 has a transmission area of 16 cm^TwoUsing zeolite-based separation membrane
Mole fraction of branched form in non-permeate
Is also expensive. From these results, it is clear that hydrocarbons rich in linear hydrocarbons
To hydrocarbon and hydrocarbon-rich hydrocarbon components
For separation efficiency, a zeolite thin film layer is formed on the surface
When using a zeolite-based separation membrane,
Zeolite-based separation membranes with a zeolite thin film layer
It became clear that it became higher than the case where it was used.

[Influence 3 of Structure of Zeolite Separation Membrane] The effect of the molar ratio of alumina to silica in the zeolite thin film layer on the separation performance was examined using zeolite separation membranes 4 to 6. Using a hydrocarbon mixture having a mole fraction of about 0.3 of a branched chain product prepared by mixing n-pentane and isopentane, at 200 ° C. and reducing the pressure on the permeation side, the permeation ratio is almost constant (38). %) And the separation performance was compared. The results of the separation are shown in Table 6.

[0061]

[Table 6]

As shown in Table 6, the molar ratio of Al ₂ O ₃ / SiO ₂ (the molar ratio of alumina to silica) was 0.01 (1/1).
In the case of (00)), the mole fraction of the branched body in the permeate is 0.1.
31 is relatively high, but as the ratio decreases from 0.0025 (1/400) to 0.00125 (1/800), the mole fraction of the branched chain in the permeate decreases to 0.15 to 0.06. It was found that the separation performance was significantly improved. From these results, in the present invention, preferably, Al
It became clear that the separation performance of the zeolite-based separation membrane was improved by setting the molar ratio of ₂ O ₃ / SiO ₂ to 0.0025 or less, more preferably 0.00125 or less.

[Effect of Separation Temperature 1] Zeolite-based separation membrane 2
Was used to study the effect of temperature on separating hydrocarbon mixtures. n-pentane, isopentane and 2
The hydrocarbon mixture in which the mole fraction of the branched chain obtained by mixing -methyl-2-butene was 0.40 was separated and concentrated in a temperature range of 50 to 250 ° C while reducing the pressure on the permeate side. The results are shown in Table 7.

[0064]

[Table 7]

From Table 7, it can be seen that the higher the separation temperature, the higher the mole fraction of the branched body which moves to the permeate side.
It has been found that a separation performance without any problem can be obtained at a temperature of not more than ° C.

[Influence of Separation Temperature 2] In the present invention, a branched chain obtained by mixing n-pentane and isopentane in order to examine whether or not the zeolite-based separation membrane causes a chemical change such as hydrocarbon decomposition or polymerization. When the molar fraction of the body is about 0.
Each of the hydrocarbon mixture having a mole fraction of about 0.40 and the hydrocarbon mixture having a branched chain structure obtained by mixing n-pentane, isopentane and 2-methyl-2-butene with each other at a temperature of 100 ° C. to 400 ° C. Separation and concentration were performed in a temperature range, and the composition of components in the permeate was analyzed by gas chromatography.

As a result, butene was detected in a separated product obtained by separating and concentrating a hydrocarbon mixture containing 2-methyl-2-butene in a reaction temperature range exceeding 300 ° C., and the olefin, 2-methyl-2-butene, was detected. -When butene is contained, it is presumed that the decomposition reaction is caused, albeit very slightly.

When a hydrocarbon mixture containing only n-pentane and isopentane was separated and concentrated in a temperature range of 400 ° C. or lower, no peak derived from a new component was observed in the separated product. The zeolite-based separation membrane used in the present invention can stably separate hydrocarbon components at a temperature of 400 ° C. or lower, and particularly at a temperature of 300 ° C. or lower even for a hydrocarbon component containing an olefin. It was found that stable separation was possible in the temperature range.

REFERENCE EXAMPLE [Dehydrogenation reaction] The equilibrium composition of the product when the non-permeate obtained by separating and concentrating the hydrocarbon mixture shown in Table 4 was decomposed into n-pentane and isopentane , 2
-Pentene (trans), 2-methyl-2-butene,
The results calculated using the dehydrogenation equilibrium constants for the six-component system of 1,3-pentadiene and isoprene were separated and analyzed.
The results are shown in Table 8 in comparison with those obtained when directly dehydrogenating without concentration. The equilibrium composition was determined by dividing the hydrocarbon-rich component of the branched-chain body after separation / concentration and the hydrocarbon mixture before separation / concentration by 9 mol times the amount of a diluent gas added, at a temperature of 5 mol.
The calculation was performed under the reaction conditions of 50 ° C. and a total pressure of 0.1 MPa.

[0070]

[Table 8]

As shown in Table 8, the molar fractions of isoprene and 2-methyl-2-butene when dehydrogenating the hydrocarbon-rich component of the branched-chain product after separation and concentration were 0.22 and 0.22, respectively.
0.45, which is higher than the molar fractions of isoprene and 2-methyl-2-butene of 0.10 and 0.24 when the hydrocarbon mixture before the separation treatment is directly dehydrogenated. From these results, it has been clarified that isoprene can be produced more efficiently by using the present invention than by directly dehydrogenating a hydrocarbon mixture before the separation treatment.

[0072]

According to the present invention, the zeolite thin film layer comprises:
By using a zeolite-based separation membrane provided with a zeolite crystal layer and a zeolite thin film layer having pores having a pore diameter of 10 nm or less at a crystal grain boundary at a surface layer portion of a porous support,
From hydrocarbon mixtures containing straight-chain and branched-chain hydrocarbons, straight-chain hydrocarbon-rich and branched-chain hydrocarbon-rich components without decomposition or chemical reaction Were efficiently separated from each other.

When the present invention is used as a pretreatment step for the dehydrogenation reaction of a hydrocarbon mixture, the branched and linear components of each component are separated and concentrated, respectively. The above restrictions can be remarkably relaxed and the reaction rate can be increased. Therefore, olefins and diolefins can be produced more efficiently than in the case where hydrocarbon mixtures before separation and concentration are directly dehydrogenated to produce olefins and diolefins.

[Brief description of the drawings]

FIG. 1 is a pore distribution diagram of a crystal grain boundary in a zeolite thin film layer.

FIG. 2 is an explanatory view (example) of a zeolite-based separation membrane (cylindrical).
It is.

[Explanation of symbols]

 1: Outside surface 2: Inside surface

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C07C 11/10 C07C 11/10 11/18 11/18 C10G 55/04 C10G 55/04 (72) Inventor Satoshi Abe 2-6-1 Nishinagasu-cho, Amagasaki-shi, Hyogo Pref. In Nard Research Institute, Inc. (72) Inventor Yasunori Ando 3-136 Noritake Shinmachi, Nishi-ku, Nagoya-shi, Aichi Pref. Inventor Hisatomi Taguchi 3-136 Noritakeshinmachi, Nishi-ku, Nagoya-shi, Aichi F-term (reference) in Noritake Company Limited 4D006 GA41 MA02 MA09 MA22 MB04 MC03X NA05 NA62 NA64 PB20 PB68 PC80 4H006 AA02 AD19 BC51 4H029 DA02 DA14

Claims (7)

[Claims] 1. A hydrocarbon mixture containing a straight-chain hydrocarbon and a branched-chain hydrocarbon is converted to a hydrocarbon-rich component of a straight-chain and a branched-chain hydrocarbon by using a zeolite-based separation membrane. A method for separating into a hydrogen-rich component, wherein the zeolite-based separation membrane, a zeolite thin film layer is formed on the surface layer portion of a porous support, the zeolite thin film layer has zeolite crystal-specific pores The pore size is 1 at the crystal grain boundary.
A method for separating a hydrocarbon mixture, which has pores of 0 nm or less. 2. Using a zeolite-based separation membrane, a hydrocarbon-rich component containing straight-chain hydrocarbons and branched-chain hydrocarbons is used as a membrane permeant to remove a component rich in straight-chain hydrocarbons. The method for obtaining a zeolite-based separation membrane, wherein a zeolite thin film layer is formed on a surface layer portion of a porous support, and the zeolite thin film layer has pores specific to zeolite crystals and a pore diameter at a crystal grain boundary. Has a pore size of 10 nm or less. 3. A hydrocarbon-rich component as a membrane-impermeable component from a hydrocarbon mixture containing a straight-chain hydrocarbon and a branched-chain hydrocarbon using a zeolite-based separation membrane. Wherein the zeolite-based separation membrane has a zeolite thin film layer formed on a surface layer portion of a porous support, and the zeolite thin film layer has pores unique to zeolite crystals and fine particles at crystal grain boundaries. A method for obtaining a hydrocarbon-rich component of a branched-chain body having pores having a pore diameter of 10 nm or less. 4. The hydrocarbon mixture is a residue obtained by separating olefins and / or diolefins from a fraction containing hydrocarbons having 4 or 5 carbon atoms obtained by cracking naphtha. The method described in. 5. The method according to claim 4, wherein the hydrocarbon mixture is a residue obtained after separating isoprene from a fraction containing a hydrocarbon having 5 carbon atoms. 6. The hydrocarbon mixture according to claim 3, wherein the hydrocarbon mixture contains isopentane, methylbutene and a linear hydrocarbon, and a hydrocarbon component rich in isopentane and methylbutene is obtained from the mixture. the method of. 7. The zeolite thin film layer has a molar ratio of alumina to silica (alumina / silica) of 0.00.
25 (1/400) or less (including 0).
7. The method according to 6.