JPS6087234A - Bulk separation of polyhydric alcohol by selective adsorption to zeolite molecular sieve - 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 The invention relates to/or liquid phase separation of mannitol and galactitol. More particularly, the present invention relates to such separations by selective adsorption onto certain types of zeolite molecular sieves.

Mannitol, sorbitol, and galactitol are polyhydric alcohols made by reducing sugars. Very often the reduction reaction product is a mixture of these polyhydric alcohols. Mannitol and sorbitol are polyhydric alcohols of particular industrial importance in their pure form.

Mannitol can be made from invert sugar, fructose or from mannose. In the first case, sucrose is hydrolyzed to invert sugar, which is a mixture of glucose and fructose.

This mixture is reduced to a mixture of sorbitol and mannitol in a ratio of approximately 6:1. In order to obtain a pure product it is necessary to separate mannitol and sorbitol in the mixture. Park Ridge, New Jersey, Noyes Data Corporation, G.A. B.
Johnson [Specialty Sugars for the Food Industry (Spec, i)]
Alized Sugars for the Foo
According to d:[industry)j (1976), this is usually done by continuous recrystallization, an expensive and time-consuming process.

Another method for separating mannitol and sorbitol in a mixture is described in U.S. Pat.
elaja) et al.). teach the use of a calcium exchanger of sulfonated polystyrene cation exchange resin cross-linked with divinylbenzene.

Mannitol can also be produced by hydrogenating mannose sources such as mata, mannose or valving liquors and other hemicellulose deglaciation products. Pure mannose is produced by hydrogenating mannose. However, these lignocellulose sources also contain wood spirit, and some of the real sugars are difficult to separate from the mannose. As a result, the hydrogenation products of these sugars, especially galactose, have to be separated from mannitol to obtain the pure product.

Crystallization type separation of mannitol and galactitol is US%
Last issue No. 4944, 625 (G. Koichi.

Neil) was disclosed. According to this method, a mannitol-galactitol mixture is dissolved in a mixed solvent of alkanol and water, and a small amount of a soluble salt of iron, nickel or cobalt is added.

It has been found that the use of resins for the separation of sugar alcohols has several disadvantages compared to the use of zeolite molecular sieves. First, the resin must be used as small beads, which may carry fines of resin through the valve and clog the valve. Also, resins tend to swell when exposed to aqueous solutions. This reduces the accuracy of the separation because the volume of resin changes from the beginning to the end of each process run. The zeolite molecular sheep used in the present invention does not swell upon encountering water, so the flow rate and volume can remain uniform throughout the process. Another potential disadvantage of using polystyrene resins is that they are organic. Therefore, it is an object of the present invention to provide an effective method for separating sugar alcohols.

It is also an object of the present invention to provide an accurate method for separating mannitol from galactitol and/or sorbitol.

A further object of the present invention is to provide a method for separating sugar alcohols by selective adsorption onto inorganic zeolite molecular sieves.

It has been found that certain zeolites are highly suitable for separating mannitol and sorbitol and mannitol and galactitol.

DESCRIPTION OF THE INVENTION The present invention is a method for separating a mixture of polyhydric alcohols consisting of one or more members consisting of sorbitol and galactitol and mannitol by selective adsorption, the mixture consisting of said compounds being heated at 30° to 110°C. selectively adsorbing the polyhydric alcohol onto an adsorbent composition comprising at least one crystalline aluminosilicate zeolite at a temperature and pressure sufficient to maintain the system in the liquid phase; The non-adsorbed portion of the mixture is removed from contact with a zeolite adsorbent, the adsorbent is desorbed by contacting said adsorbent with a desorbent, the desorbed polyhydric alcohol is recovered, and the crystalline aluminosilicate zeolite is transferred to Zeolite X. The zeolite type (zeolite type) is selected from the group consisting of zeolite type and zeolite type Y, and zeolite type
olitic) The separation method consists of the above separation method in which the cation is selected from the group consisting of barium and calcium.

Zeolite Y and its method of preparation are described in detail in U.S. Pat. No. 3,130,007, issued April 21, 1964 to D. Zeolite
It is described in detail in No. 244.

The adsorption affinity of various zeolites to sugar was determined by a pulse test. The test consisted of filling a column with the appropriate zeolite, keeping it at a constant temperature in a block heater, and eluting the solution through the column with water to determine the solute retention capacity. The solute retention capacity is defined as the solute elution volume minus the void volume. Void volume is the volume of solvent required to elute non-sorbing solutes through the column. Inulin, a soluble polymer of fructose, was chosen as the solute to fill the void volume because it is too large to be sorbed into the zeolite pores. The elution volume of inulin was determined first.

Next, the elution volume of sugar was determined under similar experimental conditions. Calculate the holding capacity and record it in the table ■ below.

The separation coefficient (S, F,) was calculated from the retention capacity data using the following formula.

3, F' = α (ゞ7-?-) -/l//galactitol)・M (retention volume t of galactitol peak) S, F −α(7jL′eto/′/Man=Toll)・
A retention capacity of the mannitol peak S,F1M/q greater than 1 indicates that the particular adsorbent was selective for mannitol over galactitol. A S,F greater than 1 indicates that the particular adsorbent was selective for sorbitol over mannitol.

Separation factor values calculated by the above method are found in Table ■.

In order to more clearly show the separation ability of sugar alcohols, Table 2 includes a column showing the value obtained by multiplying the difference between the α value and 100 by 100. This clearly shows the ability of each zeolite to perform the desired separation.

Table I Sugar alcohol retention capacity (in ml) Column size = 40 steel x 077 cIIL Internal diameter zeolite shape: Powder flow rate except where indicated: 11111
/ minute Temperature = 160°F (719C)
3.0 2.8 KY Ot4 1.3 t2 NaX 0 2.5 2.5 NaY Q t5 'b7 t8 "LiY 0 2.5 2.5 BaX Lo 8.7 15,6 21.7"BaY 0
1i0 15.0 12. ! 1”SrX O-7,2
7,28,0 ”SrY 0 1t5 12.0 1t5CaX O-
76,76,8 CaY 0 10.1 11613.1 Mesh-shaped zeolite table■ 15 15 0.82 -18SrX 0
0 111 11 SrY toa 4 0.94 -6 CaX in O1011 (CaYt15151゜1313 When mannitol and galactitol or sorbitol are separated in this method, preferably a solid zeolite adsorbent bed is packed with the adsorbate and After removing the adsorbent or raffinate mixture from the adsorbent bed, the adsorbed sugar alcohols are desorbed from the zeolite adsorbent by means of a desorbent.
It can be placed in a bed, a multiple bed using conventional swing-bed handling techniques, or a simulated moving bed countercurrent type device. A preferred mode of operation is a simulated moving bed technique, as described, for example, by Dee on May 23, 1961.

U.S. Patent No. 2,985 issued to Bee, Bruton et al.
．． It is described in No. 589. In this mode of operation, the selection of a suitable displacement or desorbent or fluid (solvent) allows the nucleating agent or fluid to displace the adsorbed alcohol from the adsorbent bed, and also allows the alcohol from the feed mixture to be adsorbed. The requirement that the desorbent removed can be replaced from a previous desorption step must be taken into account. Furthermore, the desorbent used should be easily separable from the admixture with the sugar alcohol component of the feedstock. Therefore, a desorbent should be used that has the property of easily fractionating the sugar alcohol. For example, volatile desorbents such as alcohols, ketones, mixtures of alcohol and water, especially methanol or ethanol should be used. The most preferred desorbent is water.

The active adsorbent zeolite crystals are combined into non-aggregated
It is generally more suitable to agglomerate the crystals into larger particles to reduce the pressure drop of the system, and is particularly suitable when the process involves the use of fixed adsorption beds.

The particular flocculant or flocculation method employed is not a critical factor; it is important that the binder is as inert as possible towards sugar alcohols and desorbents. The ratio of zeolite to binder is 4 to 2 parts of zeolite to 1 part binder on a dry weight basis.
A range of 0 parts is advantageous.

The temperature at which the adsorption step of the process should be carried out should be from about 0°C to the boiling point of the sugar alcohol solution (about 110°C). It has been found that at temperatures below about 30° C., the rate of interdiffusion between the sugar alcohols is too slow, ie the zeolite does not exhibit sufficient selectivity for sorbitol or mannitol. As the temperature increases, the boiling temperature of the desorbent is reached. Preferably, the adsorption step is carried out between about 0<0>C and about 90<0>C, most preferably between 60<0>C and 80<0>C.

Pressure conditions must be maintained to maintain the system in the liquid phase. Increasing the process temperature higher than necessary requires high pressure equipment, increasing the cost of the process.

A preferred method of carrying out the method of the invention is separation by chromatography columns. In this method, a sugar alcohol solution containing the mixture of sugar alcohols to be separated is briefly injected at the top of the column and the water is eluted through the column. As the mixture passes through the column, the chromatographic separation reaches a region increasingly rich in adsorbed sugar alcohols.

As the mixture passes further through the column, the resolution increases to achieve the desired resolution. At this point, the effluent from the column is initially directed to one receiver to collect the pure product.

The effluent is then directed into a mixed product receiver during which time the sugar alcohol mixture exits the column. Then, as the zone of adsorbed alcohol emerges from the end of the column, the effluent is directed into a receiver for that product.

As soon as the chromatography band has completely passed through the column, a new slug is introduced at the inlet of the column and the entire process cycle is repeated.

The mixture coming out of the end of the column during the time when a pure fraction appears is returned to the feedstock and passed through the column again to eliminate it.

The resolution of the two peaks as they pass through this chromatography column will increase as the length of the column increases. Therefore, a column of sufficient length can be designed to provide any desired degree of resolution between the two components, even when the degree of overlap between the two peaks is the greatest.

It is therefore also possible to operate the process in a manner that essentially does not return unseparated mixtures to the feedstock. However, if high purity is required, such high resolution would require unusually long columns. Additionally, as the components are eluted through the column, the average concentration of the components gradually decreases. If the sugar alcohol is eluted with water,
This means that the product stream is gradually diluted with water. Therefore, (to achieve high purity of the two components)
The optimal process uses the column for a shorter time (than required for complete separation of the peaks) and also separates the portion of the effluent containing a mixture of both peaks and separates it, as described above. It is very suitable to recycle it to the raw material.

Another way of carrying out the method of the invention is illustrated by the drawing of FIG. In this method, a number of fixed beds are connected to each other by conduits, which are also connected to a special pulp. The valves in turn move the liquid feed and product withdrawal points to different locations around the annular arrangement of individual fixed beds in a manner that simulates countercurrent movement of the adsorbent. This process is well suited for two component separations.

FIG. 5 of the drawings represents a hypothetical moving bed countercurrent process flow diagram involved in carrying out a representative process embodiment of the present invention.

Referring to the drawings, the liquid inlet and outlet are depicted as being stationary and the adsorbent mass is depicted as moving relative to the countercurrent flow of the feedstock and desorbent; It will be appreciated that the representation is primarily intended to facilitate the explanation of the functioning of the system. In reality, the adsorbent mass is usually in a fixed bed, with the liquid inlet and outlet moving relative to it. Thus, a feedstock consisting of a mixture of mannitol and sorbitol and/or galactitol is fed into the system through line 10 to adsorbent bed 12. The adsorbent bed 12 contains regenerated zeolite (BaX)
or particles of BaY adsorbent through which the feedstock passes downwardly. The temperature is 70° C. throughout the system and the pressure is substantially atmospheric. The ingredients of the feedstock are placed in bed 1
2, the raffinate is entrained in the liquid stream of water desorbent exiting the bed 12 via line 14, the majority of which is extracted via line 16 and fed to an evaporator 18; Thereupon, the mixture is fractionated and the concentrated raffinate is discharged from the pipe 20. The water desorbent exits the evaporator 18 through a line 22 and is supplied to a line 24;
It is mixed with additional desorbent that exits the adsorbent bed 26 through line 24 and circulated to the bottom of the adsorbent bed 50. Zeolite supporting adsorbed sugar alcohol) 13aX or Ba
Y passes downwardly through the conduit to bed 30 where it is contacted countercurrently with the circulated desorbent to effectively desorb the sugar alcohol, after which the adsorbent passes downwardly through the bed 30 and enters conduit 32. . The adsorbent is circulated through line 32 to the top of adsorbent bed 26. The desorption agent and the desorbed sugar alcohol are transferred to pipe 3.
Get 30 from 4. A portion of this liquid'mixture is transferred to pipe 36.
where it passes through evaporator 68 and the remaining portion passes upwardly through adsorbent bed 12 for further processing as previously described.

In the evaporator 38, the desorbent and sugar alcohol are fractionated. The sugar alcohol product is recovered via line 40 and the desorbent is either disposed of or recycled through line 42 and through line 24 as described above.

The undiverted portion of the desorbent/raffinate mixture enters bed 26 from bed 12 through line 14 and flows countercurrently upwardly against the desorbent-entrained zeolite adsorbent passing downwardly through circulation line 52. Moving.

The desorbent, in relatively pure form, passes from bed 26 through circulation line 24 to bed 50 as described above.

The following examples are illustrative of the practice of the invention and are not intended to limit the invention to the embodiments set forth in the examples.

The following abbreviations and symbols used in the examples that appear below have the following meanings.

Correction Potassium exchanged zeolite Y BaX Barium exchanged zeolite
The temperature was maintained at 〒 (71°C). Next, water was pumped into the column and α55 gprrvft2 (90””/m2)
The flow rate was maintained at A solution containing 2% by weight galactitol and 2% by weight mannitol ("feed pulse") was used for 1 minute instead of a water stream. After 1 minute feed pulse,
A water feed free of dissolved sugar alcohols was reestablished. The composition of the effluent stream was detected by a refractive index detector. The elution curve is shown in FIG. Figure 1 shows that galactitol and mannitol are not separated using KY.

Example 2 The same column and experimental procedure used in Example 1 was used.

However, this composition of the feed pulse solution was changed to 3% mannitol and 7X sorbitol. The second elution curve
As shown in the figure. This is because mannitol and sorbitol are KY
to show that they are not separated.

Example 3 The same experimental procedure used in Example 1 was used. However, I changed the zeolite to BaX. The feed pulses were galactitol 2X and mannitol 2X. The elution curve is shown in FIG. Figure 3 shows that galactitol and mannitol are separated using 13aX, with galactitol being eluted first.

Example 4 The same empty experiment procedure used in Example 3 was used. However, the feed pulse solution was changed to a solution containing mannitol 6X and sorbitol 7X. Figure 4, which shows the elution curve, shows that BaX separates mannitol and sorbitol.

Figure 1.2 shows the elution curve of polyhydric alcohol when the separation medium is potassium-substituted zeolite type Y.

Figure 3.4 shows the elution curve of polyhydric alcohol when the separation medium is barium-substituted zeolite type X.

FIG. 5 shows one way in which the method of the present application can be used.

FIG.1 FIG.2 Kaifu no blow C, yd ri

Claims (1)

[Claims] t 1 of the members consisting of sorbitol and galactitol
A method for the separation by selective adsorption of a mixture of polyhydric alcohols consisting of one or more species and mannitol, comprising: separating the mixture of said compounds at a temperature of from 60° to 110°C and at a pressure sufficient to maintain the system in the liquid phase; contacting an adsorbent composition comprising one type of crystalline aluminosilicate zeolite to selectively adsorb the polyhydric alcohol onto the composition, removing the non-adsorbed portion of the mixture from contact with the zeolite adsorbent;
The adsorbent is desorbed by contacting the adsorbent with a desorbent, the desorbed polyhydric alcohol is recovered, and the crystalline aluminosilicate zeolite is selected from the group consisting of zeolite type X and zeolite type Y, The above separation method, wherein zeolite type cations occupying 55% or more of the cation sites are selected from the group consisting of barium and calcium. 2. The method according to claim 1, wherein the temperature is about 0°C to about 90°C. 5. The method according to claim 1, wherein the temperature is about 0°C to about 80°C. 4. The method according to claim 1, wherein the desorbent is selected from the group consisting of alcohol, ketone, and water. 5. The method according to claim 1, wherein the desorbent is water. 6 A method for separating mannitol and galactitol by selective adsorption, the method comprising:
Mannitol is selected into the composition by contacting it with an adsorbent composition comprising at least one crystalline aluminosilicate zeolite of type The non-adsorbed portion of the mixture is removed from contact with the zeolite adsorbent, and the adsorbent is brought into contact with a desorbent to desorb and recover the desorbed mannitol. The above method, wherein the zeolite type cation occupying 55% or more of the ionic sites is barium. Z A method for separating mannitol and galactitol by selective adsorption, in which a mixture of the above compounds is separated by about 30%
Mannitol is selectively transferred to an adsorbent composition comprising at least one Y-type crystalline aluminosilicate zeolite by contacting the composition with a sorbent composition comprising at least one Y-type crystalline aluminosilicate zeolite at a temperature between 110 °C and 110 °C and at a pressure sufficient to maintain the system in the fluid phase. The non-adsorbed portion of the mixture is removed from contact with the zeolite adsorbent, and the adsorbent is brought into contact with a desorbent to desorb the mannitol and recover the desorbed mannitol, and the effective cations in the zeolite are removed. The above method, wherein the zeolite type cation occupying 55% or more of the sites is barium. 8. A method for separating sorbitol and mannitol by selective adsorption, the method comprising:
Sorbitol is selectively adsorbed onto an adsorbent composition comprising at least one crystalline aluminosilicate zeolite of type X by contacting the adsorbent composition with at least one type The non-adsorbed portion of the mixture is removed from contact with the zeolite adsorbent, and the adsorbent is brought into contact with a desorbent to desorb and recover the desorbed sorbitol. The method described above, wherein the zeolite type cation accounting for 55% or more is barium.