JPS63146834A - Separation of 2,6-dimethylnaphthalene - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a method for separating 2,6-dimethylnaphthalene from a feedstock containing a mixture of dimethylnaphthalene isomers. More specifically, the present invention utilizes a specific solid adsorbent and a specific desorption agent for selective adsorption and desorption of co,≦-dimethylnaphthalene and at least seven other species. Dimethylnaphthalene isomers and/or derivatives of 2,6-dimethylnaphthalene are separated from feed streams containing hydrocarbons and/or derivatives thereof in the boiling range 220-270°C. This relates to a separation method.

[Conventional technology]

It has been recognized in the prior art that type X or type Y zeolites containing sufficient cations to constitute exchangeable cation sites can separate specific dimethylnaphthalenes from mixtures containing t-dimethylnaphthalene isomers. For example, a US patent! , /JJ, /26 and US Patent! , //41. ';#2 points out that type X zeolites containing sodium or calcium at exchangeable cation sites are useful as selective adsorbents between dimethylnaphthalene isomers.

In the Japanese Patent Publication No. 5 Co. 94'j, Y-type zeolite was used, and benzene, toluene, and ortho-xylene were used as desorbing agents to selectively remove 2,2 from the co-, d/2,7-dimethylnaphthalene eutectic mixture. -It is stated that dimethylnaphthalene can be separated.

Tokusho≠9-27571 uses Y-type zeolite.
2. It is stated that ≦-dimethylnaphthalene can be separated. Further, Dutch Patent No. 3022, U.S. Patent J, 71,2. JP? , U.S. Patent JfuO, t10, U.S. Patent Jf9j, 07θ, U.S. Patent Hiro, 0/Hiro, Rihiro, etc. all disclose that Y-type zeolite is useful as an adsorbent in the separation of cyclic hydrocarbons. Are listed.

[Problem that the invention seeks to solve]

However, U.S. Patent J,/j J,/2 and U.S. Pat. / /≠, 2r2, when observing the adsorption selectivity between dimethylnaphthalene isomers, a static batch method was used for a dilute solution of a dimethylnaphthalene isomer mixture in the presence of paraffin, which does not actually strongly participate in adsorption. It merely discusses adsorption selectivity; in fact, 1
There is no mention of the involvement of a desorbing agent, which is indispensable in aggressive operation, for example, when continuous separation is performed using a simulated moving bed or the like.

There is no mention of the industrially essential desorbing agent in the aforementioned Japanese Patent Publication Sho≠2-2252♂, U.S. Patent J, 77J.
, J Tata, US Patent Jf9! , 070° U.S. patent reference, θ
The same applies to 9μ9, Dutch Patent No. 3022. In general, in adsorption separation operations, an excellent adsorption separation system requires that the adsorbent has a large separation coefficient and adsorption capacity when an equilibrium state is reached, that the substance to be separated shows no alteration, and that: The rate of adsorption and desorption of the substance to be separated is required to be high, and the desorbing agent must be somewhere between the weakest adsorption force and the strongest adsorption force among the separation substances. It has the highest adsorption power, and requires 1% of the substance to be separated to contain a substance that promotes adsorption and desorption of the target substance. If these requirements are not met, problems such as increased tailing of the substance to be separated occur, making it impossible to efficiently separate the target substance.

[Means for solving problems]

We obtained 2,
As a result of intensive studies regarding adsorption separation of 6-dimethylnaphthalene, we found that if X-type zeolite is used as an adsorbent and an aromatic hydrocarbon having 7 to 10 carbon atoms is used as a desorbing agent, 2
, 6-dimethylnaphthalene can be separated by absorption, and the present invention has been achieved.

That is, the present invention uses type X zeolite as an adsorbent to adsorb and separate co,6-dimethylnaphthalene from a feedstock oil containing a mixture of dimethylnaphthalene isomers,
This is a method for separating 2 μm dimethylnaphthalene using an aromatic hydrocarbon having 2 to 10 carbon atoms as a desorption agent.

The present invention will be explained in more detail below.

Many types of zeolites are known, including naturally occurring ones and artificially synthesized ones. However, not all of these zeolites are effective as adsorbents for the separation of co,t-dimethylnatalene according to the method of the present invention, and in the present invention, type X zeolite is used. X-type zeolite has θβ±0.2 Na! as its oxide representation. O: At203: j, j θ
, j 8101: YH20 (Where is Y? Below 0
It can be expressed as a molar ratio of oxides with respect to sodium bodies, as expressed by an arbitrary value including . In the sodium body of X-type zeolite, part or all of the sodium at its cation site can be ion-exchanged into other cations according to known methods, and X-type zeolite that has been ion-exchanged in this way can also be ion-exchanged. Can be used as an adsorbent.

/species'' or 2I!1 or more cations are selected.

Specifically, lithium, sodium, potassium, cesium, rubidium, magnesium, calcium, strontium, cobalt, butyl, iron, lead, ammonium,
Cations such as hydrogen are preferred. Particularly preferred are the lithium, sodium, potassium, cesium, magnesium, cobalt and zinc cations.

By the method of the present invention 2. In separating cordimethylnaphthalene, a feed stream of feedstock containing a mixture of dimethylnaphthalene isomers has seven or more of the above cations at the cation sites! 5. Elution-type chromatography method, Enoki moving bed method, etc. in which zeolite is brought into contact with a single bed packed in a chromatography column, and then a desorbing agent substance is passed on this bed to selectively desorb 2,6-dimethylnaphthalene. continuous separation techniques can be used. Zeolite as an adsorbent is not limited to powder form, but may also be formed into pellets, extrusions, granules, etc. In that case, silica, alumina,
Although clay and the like are used, any binder material can be used. Next, when filling the column,
The shape of the zeolite can be either spherical or crushed, but when the average particle size of the zeolite is d and the inner diameter of the column to be packed is D, the ratio D/d is 7.
More than j.

It is preferable to have a size of 20 or more I.

In order to efficiently adsorb and separate 6-dimethylnaphthalene, the selection of a desorbing agent is important.

That is, the desorbing agent can selectively and easily desorb 2,6-dimethylnaphthalene from the X-type zeolite separately from other raw oil components, and then further remove the copolymer by distillation or other methods. , and must be easily removable from dimethylnaphthalene. For this purpose, a desorbing agent whose adsorption power to the zeolite is between that of the component with the strongest adsorption power and 6-dimethylnaphthalene present in the feedstock containing a mixture of dimethylnaphthalene isomers is preferred. In the present invention, 2. The desorbing agent used for desorption of t-dimethylnaphthalene is an aromatic hydrocarbon having 2 to 10 carbon atoms. Specifically, toluene, 0-
xylene, m-xylene, p-xylene, ethylbenzene, n-7'ropylbenzene, isopropylbenzene,
Derethyltoluene, J-ethyltoluene, -monoethyltoluene, 1,2. μ-trimethylbenzene, 1,J
, z-)limethylbenzene, 1,2.3-) IJ methylbenzene, 0-cymene, m-cymene, p-cymene, 0
-diethylbenzene, m-diethylbenzene, p-diethylbenzene, 0-propyltoluene, m-propyltoluene, p-propyltoluene, n-butylbenzene, BeC-7'thylbenzene, tθrt-methylbenzene, 1,2. J, Hiro-tetramethylbenzene, 1,2
,3. j-tetramethylbenzene, 1,2. II,!
-Tetramethylbenzene and tetralin are mentioned,
Two or more of these can also be used in combination. Among the above compounds, toluene, 0-xylene, m-
Preferred are xylene, p-xylene, ethylbenzene, n-propylbenzene, isopropylbenzene, ethyltoluene, 1,1-trimethylbenzene, p-diethylbenzene, p-cymene, and tetralin, and most preferred are toluene and 0-xylene. , p-xylene, ethylbenzene, isopropylbenzene, Hiro-ethyltoluene, and tetralin. Furthermore, the above-mentioned desorbing agents can also be used in admixture with inert diluents, in which case saturated chain hydrocarbons that are liquid at the operating temperature or carbon atoms that may have alkyl substituents can be used. Naphthenes, which are saturated cyclic hydrocarbons having numbers 6 to -0, can be used.

The raw material oil containing a mixture of dimethylnaphthalene isomers, which is a raw material in the method of the present invention, includes co, 6-dimethylnaphthalene, -17-dimethylnaphthalene, J, 7-dimethylnaphthalene, muco-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4
1-dimethylnaphthalene, 1,! -dimethylnaphthalene, 1,! -dimethylnaphthalene, /I-methylnaphthalene, 1,j-dimethylnaphthalene, co, 6-
Dimethylnaphthalene 7-1 and other dimethylnaphthalene 7-1
hydrocarbon compounds containing one or more dimethylnaphthalene isomers and having a boiling point range of -10 to -70°C, such as α-methylnaphthalene, β-methylnaphthalene, α-ethylnaphthalene, β-ethylnaphthalene. ,
It may contain biphenyls, alkanes, cycloalkanes, alkenes, cycloalkenes, and the like.

The method of the present invention can be carried out in either gas phase or liquid phase, but liquid phase is preferred.

The agent must be selected appropriately considering its physical properties such as melting point, boiling point, viscosity, etc., but in order to maintain the liquid phase,
Temperatures in the range of 0 to 300° C. and pressures in the range of about 100 sq. to Jθ atmospheres are preferred.

More preferably, the pressure is selected from the fM degree range of ≦0-200°C, and the pressure in the range of about atmospheric pressure to about θ atmosphere.

Generally, as an indicator of the separation ability of an adsorbent, separation is defined as the ratio of the same two components in the adsorbed phase to the ratio of the unadsorbed λ component in an adsorption equilibrium state between the special λ components in the feedstock. A coefficient K is used. That is, components A, B
Assuming that the unadsorbed volume is xA s xB s and the volume % of the adsorption phase is YA s YB, the separation coefficient J of components A and B defined by is used. The component with strong adsorption power is B1 The component with weak adsorption power is A
In this case, the larger the value of xB, the better the separation ability of the adsorbent. In other words, if the KA values of two components A and B are close to 1 and 0, the adsorbent is
is not preferentially adsorbed, and both are adsorbed to approximately the same extent as each other. The fact that the value of - is larger than 7.0 means that component B is preferentially adsorbed compared to component Al/C. K used a dynamic test apparatus to determine the adsorbent properties of adsorption capacity, selectivity, and desorption rate using various adsorbents and desorbers for feedstocks containing mixtures of dimethylnaphthalene isomers. do. This device is a stainless steel column with an inner diameter rttrs and a length/m, and has a heat insulation jacket on the outside.

A distributor for liquid dispersion is provided at the inlet of the column to prevent uneven flow.

A pulse test is conducted using the apparatus described below in accordance with the general procedure described below, and data such as selectivity is measured for various adsorbent/desorbent systems. The column is packed with adsorbent and conditioned by passing through the desorbing agent. Next, a raw material containing a mixture of dimethylnaphthalene isomers is injected in pulses for several minutes, and after a predetermined amount is injected into the column inlet, the flow is switched to the desorbing agent again, and desorption is carried out within a flow rate range in which plug flow is maintained and back mixing diffusion does not occur. A release agent is flowed to develop the feedstock into the column. A sampling port is provided at the column outlet, through which a certain amount of effluent is periodically sampled and analyzed using a gas chromatograph to quantify each component in the fraction. By plotting each component concentration against the corresponding outflow time, the envelope of the peak corresponding to each component can be determined.

The suitability of the selected sub-adsorption agent and desorption agent is generally determined by the capacity of the target substance to be desorbed, the separation coefficient between the target substance and each other component contained in the raw material, and its purpose. It is determined based on the desorption rate of the substance, etc. The capacity index is the amount of desorption pumped in the time between the center of the peak envelope of any adsorbed component and the center of the peak envelope of the tracer component not participating in adsorption (a known reference point). It is expressed as the volume of release agent.

By the way, the volume through which tracer components not related to adsorption flow is synonymous with the volume of voids between adsorbent particles in the column, and this value is determined by the physical properties of the adsorbent such as the true density of the adsorbent, the bore volume, etc., and the packing in the column. It is determined by measuring the packing density when

Therefore, in other words, the above-mentioned known reference point.

The time is determined by dividing this void volume by the desorbing agent flow rate.

On the other hand, the separation of component A and component B in the raw materials can also be expressed as 9, which is the ratio KA/of the capacity indexes KA and KB of the two. From the above, in the present invention, the separation coefficient of the other dimethylnaphthalene isomer component J for 2,6-dimetelnaphthalene is set to 6, and the distance between the center of the peak envelope of the component and the known reference point is set to 6. Calculated from the ratio of the interval between the center of the peak envelope line of J,4-dimethylnaphthalene and a known reference point. According to the method of the present invention, it is clear that ``1.6'' is all/larger and that 9-dimethylnaphthalene can be selectively released.

〔Example〕

Next, the present invention will be explained in more detail with reference to examples, but the present invention is not limited to the following examples as long as the gist of the present invention is not exceeded.

Example 1 Granules of X-type zeolite (particle size distribution: Kobadako Opm), which is a cation site or sodium, were packed into a stainless steel column with an inner diameter of ♂m and a length of 7m with a heat-retaining jacket. A distributor was installed to prevent drifting. The column temperature was maintained at 100°C, and from one end of the column, as a desorbing agent,
Toluene every minute! The column was fed at a rate of -, and the column was filled with a desorbing agent for 7' (0).Then, the entire raw material containing the dimethylnaphthalene isomer mixture was fed as a 3-pulse to the top of the column, and then again. Switching to the desorbing agent flow, the desorbing agent was introduced at a rate of O0 per minute, and the raw material feed was developed in the column. The outlet stream is sampled, the components contained in each fraction are quantified using a gas chromatograph, and the concentration changes of the raw material components in the outlet stream are measured over time.Next, each fraction of the effluent is analyzed. By dotting the values, the peak envelope line of each component is obtained.Table 1 shows the separation coefficients of other raw material components for 2,t-dimethylnaphthalene obtained based on this.

Example 2 ~// As in Example//, a granular product of type X zeolite (particle size distribution 2!θ to Hiroko θ7J exclusive) whose cation site is sodium was used as an adsorbent. p-xylene and m-xylene as desorbing agents, respectively.
Xylene, 0-xylene, ethylbenzene, φ-ethyltoluene, isopropylbenzene, n-7′-pyrubenzene, 1,co, φ-trimethylbenzene, p-7men,
The same method as in Example 1 was carried out except that tetralin was used. The obtained results are similarly shown in Table 1 as separation coefficients of other raw material components for 2,1-dimethylnaphthalene. It can be seen that each example shows good selectivity for 2,6-dimethylnaphthalene.

Example 2 - 4L-θμm) was carried out in the same manner as in Example 2 using p-xylene as an adsorbent and p-xylene as a desorbing agent. Table 2 shows the separation coefficients of other raw material components for the resulting product, 6-dimethylnaphthalene.

Example 73-2/ Exchangeable cation sites were replaced with potassium, cesium, and
Example 2 below uses a granule of type X zeolite (particle size distribution: 0 to 2 oam) substituted with magnesium, copal), zinc, iron, lead, ammonium, and hydrogen as an eyebrow absorbent.
I did it in the same way. 2,6- for each adsorbent
Table 2 shows the separation coefficients of other raw material components for dimethylnaphthalene.

Comparative Example/Example/X-type zeolite granules in which the cation site is sodium (particle size distribution 2!O~1k20μrI)
The same procedure as in Example 1 was carried out except that L) was used as an adsorbent and benzene was used as a desorbing agent. Because benzene was strongly adsorbed on the adsorbent, all dimethylnaphthalene isomers were not adsorbed and flowed out at the same time. From this result, it is clear that benzene has no ability to separate dimethylnaphthalene isomers at all.

Comparative Example λ Same as Example/, except that granules of X-type zeolite (particle size distribution 2jO≠20μWL) in which the cation sites are sodium were used as the adsorbent, and n-dodecane was used as the desorbing agent. I did the same. As a result, the raw material feed containing the dimethylnaphthalene isomer mixture is strongly adsorbed by the adsorbent and does not flow out to the column outlet. From this, it is clear that n-dodecane is not suitable as a desorption agent.

Comparative Example 3 Granular product of type X zeolite in which exchangeable cation sites were replaced with barium (particle size distribution 250-4c, 2θμr
The same procedure as in Example 1 was carried out except that rL) was used as the adsorbent and baraxylene was used as the desorbing agent. As a result, all the dimethylnaphthalene isomers leaked out at the same time, making it impossible to separate them. From this it is clear that barium-substituted zeolites of type X are unsuitable as adsorbents for the fractionation of dimethyl isomer mixtures.

Sender: Mitsubishi Chemical Industries, Ltd. Representative Patent Attorney Hase - Others/Names

Claims (3)

[Claims] (1) In adsorbing and separating 2,6-dimethylnaphthalene from a feedstock containing a mixture of dimethylnaphthalene isomers, X-type zeolite is used as an adsorbent, and aromatic hydrocarbons having 7 to 10 carbon atoms are used as a desorbing agent. A method for separating 2,6-dimethylnaphthalene, characterized in that it is used. (2) The cation site of the X-type zeolite is one or more cations selected from lithium, sodium, potassium, cesium, rubidium, magnesium, calcium, strontium, cobalt, nickel, iron, zinc, lead, ammonium, or hydrogen. 2. The method according to claim 1, wherein the ion exchange is performed with (3) The dimethylnaphthalene isomer mixture includes 2,6-dimethylnaphthalene, 2,7-dimethylnaphthalene, 2
, 3-dimethylnaphthalene, 1,2-dimethylnaphthalene, 1,3-dimethylnaphthalene, 1,4-dimethylnaphthalene, 1,5-dimethylnaphthalene, 1,6-dimethylnaphthalene, 1,7-dimethylnaphthalene and 1
, 8-dimethylnaphthalene. 8-dimethylnaphthalene.