JPS58180207A - Adsorptive separation - Google Patents

Abstract

PURPOSE:To remove a target component from an adsorbent layer which does not adsorb the target component selectively by supplying a fluid mixture to an adsorption system consisting of the adsorbent layer which does not adsorb the target component selectively and an adsorbent layer which adsorbs said component selectively and moving the supplied mixture between both adsorbent layers with a fluid desorbing agent. CONSTITUTION:A mixture 3 of components A, B is supplied together with a mixture 5 flowing out from an adsorbent layer 2 from the right of an adsorbent layer 1 consisting of an adsorbent which does not adsorb the component A selectively and a raffinate 4 rich in the component A is drawn from the left. In this stage, an adsorbent 6 is supplied from the right of the adsorbent layer 2 consisting of the adsorbent which adsorbs the component A selectively and the flow 5 is expelled from the left. An adsorbent 7 is supplied from the left of layer 1 and the mixture 8 is supplied together with the supplied mixture 3 to the left of the adsorbent 2. A raffinate 9 rich in the component B is drawn from the right. The A and B are separated from the mixture by operating the above-mentioned operation repeatedly and connectively.

Description

[Detailed description of the invention] The present invention relates to a method for separating components by adsorption,
In particular, we propose an adsorption separation method using adsorbents with contradictory adsorption abilities.

Conventionally, as a component separation method applying adsorption separation technology, the chromatographic preparative method, in which a mixture is intermittently supplied onto an adsorbent and developed and fractionated with a developing agent, has been made continuous, and the liquid flow and adsorbent There is an adsorption separation method using a simulated moving bed that brings the flow into apparent upward flow contact.

Comparing the two on a commercial production scale, chromatographic preparative separation is relatively simple in terms of operation and system, and equipment costs are low;
A large amount of developing agent is used, and therefore the concentration of the fractionated components is diluted, and the cost of separating the developing agent is very high. Furthermore, the recovery rate of separated components by chromatographic separation is lower than that of a simulated moving bed. On the other hand, adsorption separation using a simulated moving bed improves the above-mentioned drawbacks of chromatographic separation, but
On the other hand, both the operation and system become complicated and the equipment cost increases.

In view of this, the present inventors have conducted intensive research into an adsorption separation method that combines the advantages of both methods, and have found that effective adsorption separation can be achieved by using adsorbents with contradictory selective adsorption performance. I found out what I can achieve.

That is, in order to separate and recover a component of interest from a fluid mixture, the present invention applies the fluid mixture to an adsorption system consisting of an adsorbent layer that does not selectively adsorb the component and an adsorbent layer that selectively adsorbs the component. The adsorption separation method is characterized in that the feed mixture is transferred between defined adhesion layers by means of a fluid desorbent, and the component of interest is removed from an adsorption layer that does not selectively adsorb the component.

The present invention is characterized by an adsorbent layer (hereinafter referred to as the second adsorption layer) that selectively adsorbs the component of interest (hereinafter referred to as A) and an adsorbent layer that does not selectively adsorb A (hereinafter referred to as the first adsorption layer). A is removed from the first adsorption layer as a so-called raffinate stream by using an adsorption layer (referred to as an adsorption layer). That is, by supplying a fluid mixture (hereinafter referred to as the mixture) to the adsorption system consisting of both of the above-mentioned adsorption layers, and alternately supplying a fluid desorbent (hereinafter referred to as the desorbent) from one end of both layers, the mixture is removed. The component A is moved back and forth across both adsorption beds and brought into contact with both adsorption beds to extract A from the first adsorption bed and the remaining component from the second adsorption bed as a raffinate stream.

An advantage of the method of the present invention is that it does not require any apparent movement of adsorbent in a simulated moving bed, thereby simplifying the complex operations and systems required for supplying or withdrawing fluids and reducing equipment costs. Furthermore, since the adsorbent layer is not used cyclically like a pseudo-moving bed, component A may be mixed into the desorbent supplied to the first adsorption layer, and the desorbent supplied to the second adsorption layer There is no problem even if the remaining ingredients are mixed into the agent.

The advantage of this is that, for example, of the raffinate flow containing component A extracted from the first adsorption layer (hereinafter referred to as the first raffinate), only the portion with a high concentration of component A is recovered, and the rest is used as a desorbent. Therefore, the amount of desorbing agent (or developing agent) used can be greatly reduced compared to, for example, chromatographic separation.

Furthermore, in the chromatographic separation method, when component A cannot be completely developed and separated on the adsorbent, that is, the portion where the peaks of component A and other components overlap becomes an unrecovered portion, reducing the recovery rate of component A. Since the method retains that portion together with the feed mixture in the adsorption system, the recovery rate of component A is improved compared to preparative chromatography.

Next, the method of the present invention will be specifically explained with reference to a schematic diagram for a system in which the mixture consists of the component A of interest and the other component B, but it goes without saying that the present invention is not limited thereto.

In FIG. 1(a), a feed mixture 3 consisting of components A and B is fed from the right end of a first adsorption layer 1 filled with an adsorbent that does not selectively adsorb component A to a second adsorption layer 2, which will be described later. (referred to as the second extract stream)
The first raffinate 4 containing highly purified component A is extracted from the left end of the adsorbent layer. At this time, a desorbent 6 is supplied from the right end of the second adsorption layer 2 filled with an adsorbent that selectively adsorbs component A, and a second extract flow 5 is expelled from the left end.

The above operation is stopped just before the B component substantially breaks through into the first raffinate stream 4, and the operation then proceeds to that of FIG. 1(b). A desorbent 7 is supplied from the left end of the first adsorption layer 1 and a mixture (referred to as the first extract flow) 8 flowing out from the right end is supplied together with the feed mixture 3 to the left end of the second adsorption layer 2. A second raffinate stream 9 containing the B component is extracted from.

Just before the A component substantially breaks through into the second raffinate flow, the operation of FIG. 1(b) is stopped and the operation of FIG. 1(a) is started. By repeating the operations shown in Fig. 1 (a) and (b) above, A and B are extracted from the mixture.
Each component can be separated and recovered.

FIG. 2 shows one example of a method for extracting raffinate from the middle-open position of the adsorbent bed.

Reference numeral 10.11 shows the first adsorption layer 1 in FIG. 1 divided into two adsorption chambers, and a first raffinate extraction line 4 is provided at the divided location. Similarly, 12.1
3 is the second adsorption layer 2 divided into two adsorption chambers, and 9 is the second raffinate extraction line. A
The feed mixture 3 consisting of the and B components is fed through the pump 24 to the first adsorption bed 11 with a second extract stream exiting the adsorption chamber 12 of the second adsorption bed. At this time, a liquid flow occurs from the adsorption chamber 11 to the first adsorption chamber 10.
A part of the desorbent held in the adsorption layer is collected into the first desorbent tank 14 through the valve 16. At this time, valve 17 is closed and valve 18 is open. The above operation is completed just before the B component substantially breaks through to the liquid outflow side of No. 11. Therefore, the adsorption chamber 10 contains the A component and the desorbent.

Next, while supplying the desorbent from the first desorbent tank 14 to the adsorption chamber 10 of the first adsorption layer through the pump 22, the first raffinate stream 4 containing the A component is extracted through the valve 17. If desired, a portion of the first raffinate stream may be fed through valve 18 to adsorption chamber 11 of the first adsorption bed. The valve 17 is then closed and the first extract stream leaves the adsorption chamber 11 and is fed with the feed mixture 3 to the adsorption chamber 12 of the second adsorption bed. At this time, the valve 20 is closed, a liquid flow occurs from the adsorption layer 12 to the adsorption layer 13, and a part of the desorbent held in the second adsorption layer passes through the valve 21 and is collected into the second desorbent tank 15. be done.

The above operation is completed just before the A component substantially breaks through to the liquid outflow side of No. 12. Therefore, the adsorption chamber 13 contains the B component and the desorbent. However, this does not apply when it is not necessary to recover component B with high purity or when it is desired to increase the yield of component A.

Next, while supplying the desorbent from the second desorbent tank 15 to the adsorption chamber 15 of the second adsorption layer through the pump 25, the second raffinate stream 9 containing the B component is extracted through the valve 20. If desired, a portion of the second raffinate stream may be supplied to adsorption chamber 12 through valve 19.

The valve 20 is then closed and the second extract stream leaves the adsorption chamber 12 and is supplied with the feed mixture 3 to the adsorption chamber 11 of the first adsorption bed. By repeating the operations explained in FIG. 2 above, components A and B can be separated and recovered from the mixture.

In the above operation, extraction of the raffinate may be carried out at the time of supplying the mixture. Furthermore, the supply of the mixture and the supply of the extract stream flowing out from the other adsorption layer may be carried out separately, or the raw material may be supplied only to one adsorption layer.

It is also possible to take part of the extract flow out of the system. Furthermore, it goes without saying that the state of the fluid may be either a gas phase or a liquid phase.

Each of the first and second adsorption layers may be divided into six or more adsorption chambers, and a plurality of fluid supply or extraction ports may be provided.

Figure 6 shows an example in which the first adsorption layer, which is an adsorbent layer that does not selectively adsorb component A, is divided into two adsorption chambers 10 and 11, and these are used in combination according to the pulp sequence example in Table 1. This is what is shown.

Table 1 In step 1 of Table 1, the feed mixture and/or the second adsorption layer (not shown) are added from the rightmost line in FIG.
A second extract stream exiting is supplied to the adsorption chamber 11 through valve 36 . At the same time, fluid flows from adsorption chamber 11 to 10 through valve 35, and the desorbent held in adsorption chamber 1o is collected into desorbent tank 14 through valve 32.31.3o. A at the left end exit of the adsorption chamber 10
Just before the components begin to substantially break through, step 2 is entered, where valve '51 is closed and 33 is opened to recover the first raffinate stream 4 containing the highly purified A component. Adsorption chamber 1
Just before the B component substantially passes through the left end exit of 0, the process moves to step B. In step 3, the desorbent is supplied from the desorbent tank 14 to the adsorption chamber 11 through the pump 22, valves 61, and '54.

At 11, the mixture held within the adsorption chamber is expelled by the desorbent and a first extract stream exits through valve 56. At least a portion of this is fed to a second adsorption layer (not shown). The adsorption chamber 10 remains in the same state at the end of step 2. In step 4'c, the feed mixture and/or the second extract stream are supplied to the adsorption chamber 10 through the valve 37.

At the same time, the fluid flows from the adsorption chamber 10 to the adsorption chamber 11 through the valve 38, and the desorbent valve 34 held in the adsorption chamber 11
, K1', 50 and is collected in the desorbent tank 14.

Just before the A component begins to substantially break through to the left end outlet of the adsorption chamber 11, the process moves to step 5, where the valve 51 is closed and the valve 33 is opened to produce the first raffinate stream 4 containing the highly purified A component.
Collect. Just before the B component substantially passes through the left end exit of No. 11, the process moves to step B.

In step 6, the desorbent is pumped from the desorbent tank 14 to the pump 2.
2. It is supplied to the adsorption chamber 10 through valves 31 and 32. At 1o, the mixture held within the adsorption chamber is expelled by the desorbent and the first Fname tract stream exits through valve 37. At least a portion of this is fed to a second adsorption layer (not shown). At this time, the adsorption chamber 11 remains in the same state as at the end of step 5. Next, return to step 1 and repeat the above operations.

In the method illustrated in FIG. 3, the recovery rate of component A is improved because the adsorption chamber 11) is formed within the adsorption chamber.

The desorbent used in the present invention may be of any type as long as it can easily separate the components to be separated and recovered, for example by distillation, and can also selectively expel the adsorbed substances from the adsorbent. Moreover, the desorbent supplied to the first adsorption layer and the desorption agent supplied to the second adsorption layer may be different, but it is preferable that they be the same.

Any material may be used for the adsorbent used in the present invention, and what is required is to find an adsorbent that does not selectively adsorb the component of interest to be recovered and an adsorbent that selectively adsorbs the component of interest. In the case of a two-component system where the component of interest is A and the other component is B, the order of adsorption power for each component of the adsorbent is A (B) on one side, and B (A on the other side). , C, it is essential that one adsorbent adsorbs A the weakest, and the other adsorbent preferably adsorbs A the strongest, but for example, if B (A<C Although this does not limit materials with contradictory adsorption abilities,
For example, zeolite adsorbents, clay adsorbents, activated carbon,
It can be selected from silica gel, ion exchange resin, gel filtration agent, sinterable adsorbent, etc. Of course, the first and second
It goes without saying that the adsorbents used in the adsorption layer may be of the same material or different materials.

Further, the substances separated by the method of the present invention are not limited, but include, for example, separation of aromatics, separation of isomers, separation of paraffins, separation of aromatics and paraffins, separation of sugars, and various other substances. It can be used for separation of fluid mixtures.

In order to separate a certain target substance using the method of the present invention, two types of adsorbents having contradictory adsorption capacities as described above are required. The adsorption capacity of these adsorbents is expressed by the adsorption selectivity a shown below.

Here, S represents an adsorption layer, and L represents a liquid phase in equilibrium with the adsorbed gold. A if αA/B is greater than 1.0
If the component is more selectively adsorbed than the B component and is smaller than 1.0, it means that the A component is not adsorbed more selectively than the B component (that is, the B component is selectively adsorbed). Therefore, one of the two types of adsorbents used in the present invention should be as α as possible.
It is preferable to select one in which A/B is greater than 1, and the other to be smaller than 1 and close to 0 as possible.

The adsorbent having the above-mentioned contradictory adsorption abilities that can be used in the present invention will be specifically explained using a zeolite-based adsorbent. Zeolite adsorbents are so-called crystalline aluminosilicate and are usually classified into type A, mordenite, clinoptilolite, L type, 28M type, faujasite type, etc., and are particularly effective for adsorption and separation of aromatic isomers. The faujasite type is preferred for use. The faujasite type is a crystalline aluminosilicate represented by the following formula: Q, 9±cL2J/rlO: Al2O3: xS 40
2:yH2゜(M indicates a cation, n indicates its valence) and X type (US P-2,882,244)
and type Y (USP-3,130,007),
The type is X = 2.5 ± 0.5, and the Y type is x = 3
~6. Moreover, y varies depending on the degree of hydration.

If the above-mentioned faujasite is subjected to a dealuminization reaction, X can become 6 or more.

Exchangeable cations in zeolites can be replaced with other cations by ion exchange methods. Ion exchange methods for these cations are widely known to those skilled in the art who have knowledge of crystalline aluminone licades, and are usually
This can be carried out by contacting the zeolite with an aqueous solution of a soluble salt of one or more cations to be added to the zeolite. To use these zeolites as adsorbents, they are usually granulated to a size of 5ILI+1φ or less,
Calcination removes some or almost all of the hydrates and activates them.

Specific examples of the zeolite-based adsorbent having the above-mentioned contradictory adsorption abilities that can be used in the present invention include cations of Y-type zeolite, -Y, and Na ions.
This is the separation of p-xylene and m-xylene using -Y. The adsorption selectivity α in this system is shown in Table 2.

Table 2 (PX: p-xylene, MX: m-xylene) Furthermore, four compounds with contradictory adsorption abilities shown in Table 3 for p-chlorotoluene and m-chlorotoluene, which are halogenated aromatic hydrocarbon isomers, were used. There is Jasite type zeolite.

(Margins below) Table 6 (PCT: ρ-chlorotoluene, MCT: m-chlorotoluene) Similarly, Table 4 shows p-chlorotoluene and o-chlorotoluene.

Table 4 (PCT: p-chlorotoluene, OCT: 0-chlorotoluene) Table 5 shows p-dichlorobenzene and m-dichlorobenzene.

Table 5 (DCB Nidichlorobenzene) Using the adsorbent shown in Table 5, p-xylene and m-
A specific example of separating and recovering m-xylene with high purity from a mixture consisting of xylene is as follows.

In Figure 2, 11.12 has a length of 2.2m and a diameter of 51u.
The adsorption chamber of Iφ, 10.13, has a length of 1 m.

Using an adsorption chamber with a diameter of 5Uφ, the particle size was approximately [11
A diameter of 111φ was filled with a -Y type adsorbent, and a diameter of 12.13 was filled with an Na-Y type adsorbent having the same particle size.

Table 6 shows a typical mass balance during operation with the adsorbent layer maintained at 150°C.

The remainder of the material balance in Table 6 is the portion of the first and second extract flows taken out of the system.

[Brief explanation of the drawing]

1 to 3 are flow sheets showing embodiments of the present invention. 1... Adsorbent layer that does not selectively adsorb the component of interest 2... Adsorbent layer that selectively adsorbs the component of interest 3... Supply mixture 4...・°・ Raffinate flow containing the component of interest 5.8
6.7 Mixture flowing out from the adsorbent layer for...
... Desorbent 9 ... Raffinate flows 10 to 13 containing components other than the components of interest ... Adsorption chamber

Claims (1)

[Claims] (1) In separating and recovering a component of interest from a fluid mixture,
The entire fluid mixture is fed to an adsorption system consisting of an adsorbent layer that does not selectively adsorb the component and an adsorbent layer that selectively adsorbs the component, and a fluid desorber moves the feed mixture between the defined adhesion layers. An adsorption/separation method characterized in that the component of interest is extracted from an adsorbent layer that does not selectively adsorb the component.