JPS6313417B2 - - Google Patents

Description

[Detailed description of the invention]

The technical field to which this invention relates is solid layer adsorption separation of fatty acids. More specifically, the present invention relates to a method for separating fatty acids using an adsorbent containing specific polymers that selectively adsorbs one fatty acid from a feed mixture containing two or more fatty acids. It is known in the separation art that certain crystalline aluminosilicates can be used to separate certain fatty acid esters from mixtures thereof. For example, US Patent Nos. 4048205, 4049688 and 4066677
No. 1, 2003, claims a method for separating fatty acid esters of varying degrees of unsaturation from a mixture of esters of saturated and unsaturated fatty acids. These methods use adsorbents containing X or Y zeolites with selected cations in an exchangeable cation seat. In contrast, the present invention relates to the separation of certain fatty acids rather than fatty acid esters. We show that nonionic, hydrophobic, insoluble cross-linked polystyrene polymers exhibit adsorption selectivity for one fatty acid with respect to another, thus enabling the separation of such fatty acids by solid layer selective adsorption. I found something to do. In one particular embodiment, our method is a method for separating stearic acid from palmitic acid. In another specific embodiment, our method is a method for separating oleic acid from linoleic acid. A substantial use of fatty acids is in the field of plasticizers and surfactants. Fatty acid derivatives are important in the formulation of lubricating oils, as lubricants for the textile and molding industries, in special lacquers, as waterproofing agents, in the cosmetic and pharmaceutical sectors, and in biodegradable detergents. Briefly summarized, the present invention, in one specific embodiment, combines a first fatty acid selected from the group consisting of stearic acid and oleic acid with a second fatty acid selected from the group consisting of palmitic acid and linoleic acid. A method for separating fatty acids from a mixture containing a fatty acid, the method comprises separating said mixture under adsorption conditions from a nonionic, hydrophobic, insoluble cross-linked polystyrene polymer having adsorption selectivity for said first fatty acid. contacting the first fatty acid with an adsorbent containing the fatty acid, and thus selectively adsorbing the first fatty acid;
In this case, when the first fatty acid is stearic acid, the second fatty acid is palmitic acid, and when the first fatty acid is oleic acid, the second fatty acid is linoleic acid. In yet another specific embodiment of the present invention, a first fatty acid selected from the group consisting of stearic acid and oleic acid is combined with a second fatty acid selected from the group consisting of palmitic acid and linoleic acid. A method of separating the first fatty acid from a mixture containing stearic acid, in which the second fatty acid is palmitic acid when the first fatty acid is stearic acid, and the second fatty acid is palmitic acid when the first fatty acid is oleic acid. The fatty acid is linoleic acid, the method uses an adsorbent containing a nonionic, hydrophobic, insoluble cross-linked polystyrene polymer, and the method includes the following steps: A process of maintaining a net fluid flow in a single direction through a column, the column having at least three zones within which the zones have separate operating functions occurring therein, and having continuous connection of the zones. (b) an adsorption zone is retained within said column, said zone being in continuous interconnection with a zone at the end of said column connected to give a (c) retaining a purification zone immediately upstream of the adsorption zone; (d) retaining a desorption zone immediately upstream of said purification zone, said desorption zone is defined by the adsorbent between the desorbent input stream at the upstream boundary of this zone and the extract output stream at the downstream boundary of this zone; selectively adsorbing the first fatty acid by an adsorbent in the adsorption zone through the removal of a raffinate output stream from the adsorption zone containing the second fatty acid; (f) removing a desorbent material from the adsorption zone; (g) removing from the desorption zone an extractive output stream containing the first fatty acid and desorbent material; (h) passing at least a portion of said extract output stream through a separation means and separating therein at least a portion of said desorbent material under separation conditions; and (i) said feed input stream, raffinate output. A stream, a desorbent input stream, and an extract output stream are periodically advanced through the adsorbent column in a downstream direction with respect to the fluid flow within the adsorption zone to move the zone through the adsorbent and extract product. The process of creating an outflow and a roughinate production stream. Other embodiments of the invention include details about charge mixtures, adsorbents, desorbents, desorbent materials, and operating conditions, all of which are specific to each aspect of the invention. As disclosed in the description below. First, it will be helpful to define various terms used throughout this specification to clarify the operation, objects, and advantages of the present invention. A "feed mixture" is a mixture containing one or more extract components and one or more roughinate components that are separated by the present method. The term "feed stream" refers to the flow of the feed mixture through the adsorbent used in the process. "Extract component" is a compound or type of compound that is more selectively adsorbed by the adsorbent, whereas "ruffinate component" is a compound or type of compound that is less selectively adsorbed. . In this method, the first fatty acid is an extract component and the second fatty acid is a ruffinate component. The term "desorbent material" shall generally mean a material capable of desorbing extract components. The term "desorbent stream" or "desorbent input stream" refers to the flow through which the desorbent material goes to the adsorbent. "Roughinate stream" or "ruffinate output stream" means a stream through which the roughinate components are removed from the adsorbent. The composition of the ruffinate stream may vary within the range of substantially 100% desorbent material to substantially 100% ruffinate component. The term "extract stream" or "extract output stream" shall mean the stream through which the extract material desorbed by the desorbent material is removed from the adsorbent. The composition of the extract stream may likewise vary within the range of substantially 100% desorbent material to substantially 100% extract components. At least a portion of the extract stream and preferably at least a portion of the raffinate stream from the separation process is passed to a separation means, typically a rectification device, where at least a portion of the desorbent material is separated to form the extract. yields a product and a ruffinate product. The terms "extract product" and "raffinate product" refer to a product produced by the present method that contains extract and raffinate components in higher concentrations than those found in the extract stream and the raffinate stream, respectively. means. Although according to the method of the invention it is possible to produce high purity first fatty acid products or second fatty acid products (or both) with high recoveries, the extract components are never completely absorbed by the adsorbent. It will be appreciated that the raffinate components are not completely unadsorbed by the adsorbent. Therefore, different amounts of the raffinate components can be present in the extract stream, and likewise different amounts of the extract components can be present in the raffinate stream. The extract and raffinate streams are then further distinguished from each other and from the charge mixture by the ratio of the concentrations of extract and raffinate components present in a particular stream.
More specifically, the ratio of the concentration of the primary fatty acid to the concentration of the less selectively adsorbed secondary fatty acid is lowest in the raffinate stream, next highest in the feed mixture, and highest in the extract stream. Dew. Similarly, the less selectively adsorbed first
The ratio of the concentration of fatty acids to the concentration of more selectively adsorbed secondary fatty acids will be highest in the raffinate stream, next highest in the feed mixture, and lowest in the extract stream. The term "selective pore volume" of the adsorbent is defined as the volume of the adsorbent that selectively adsorbs extract components from the feed mixture. The term "non-selective void volume" of the adsorbent is the volume of the adsorbent that does not selectively retain extract components from the feed mixture. This volume contains adsorbent cavities that do not have adsorbent seats but have interstitial void spaces between adsorbent particles. Selective pore volume and non-selective pore volume, as described above, are generally expressed in terms of the amount of fluid that must be passed through the operating zone for efficient operation to occur for a given amount of adsorbent. This is important in determining the appropriate flow rate. When the adsorbent "transfers" into the operating zone (to be defined and explained below) used in one embodiment of the invention,
The non-selective void volume, along with the selective pore volume, transports fluid into the zone. The non-selective void volume is used in determining the amount of fluid that must migrate countercurrently to the adsorbent into the same zone to displace fluid present in the non-selective void volume. If the flow rate of fluid migrating into a zone is less than the nonselective void volume velocity of the adsorbent material migrating into that zone, there is a net entrainment of liquid into that zone by the adsorbent. . Since this net entertainment is the fluid present within the non-selective pore volume of the adsorbent, it often consists of less selectively retained feed components. The selective pore volume of one adsorbent adsorbs a portion of the ruffinate material from the fluid surrounding the adsorbent, since in some instances the selective pore volume This is because there is competition between the extractive material and the raffinate material for the adsorbent seat. If a large amount of raffinate material surrounds the adsorbent relative to the extract material, the ruffinate material can be competitive enough to be adsorbed by the adsorbent. Before considering the feed mixture that can be charged to the process of the invention, first a brief explanation of the terminology and general production of fatty acids is provided. Fatty acids are a large group of aliphatic monocarboxylic acids, many of which are found as glycerides (esters of glycerol) in natural fats and oils. Although the term "fatty acids" has been restricted by some to saturated acids of the acetic acid series, both straight-chain and branched, today it is generally, and in this specification as well, extended to related unsaturated acids, It is also used to include certain substituted acids and aliphatic acids with alicyclic substituents. Naturally occurring fatty acids are higher straight chain unsubstituted acids with an even number of carbon atoms, with a few exceptions. Unsaturated fatty acids are divided into monoethanoids, diethanoids, triethanoids, etc. (or monoethylenic, etc.) based on the number of double bonds in the hydrocarbon chain. Thus, the term "unsaturated fatty acids" is a generic term for fatty acids with at least one double bond, and the term "polyethanoloid fatty acids" refers to fatty acids with two or more double bonds per molecule. Fatty acids typically have several “splits”
prepared from glyceride fats or oils by one of the following methods: (splitting) or hydrolysis. In all cases, the hydrolysis reaction is summarized as the reaction of fats or oils with water to produce fatty acids plus glycerol. In modern fatty acid plants, this process is carried out by continuous high-pressure, high-temperature hydrolysis of fats. The most commonly used starting materials for the production of fatty acids include coconut oil, palm oil, inedible animal fats, and the commonly used vegetable oils, soybean oil, cottonseed oil, and corn oil. The composition of the fatty acids obtained from the "splitter" depends on the fat or oil from which they are made. As detailed data on the fatty acid composition of fats accumulate across a wide range of substances, it becomes increasingly clear that natural fats tend to be organized into groups depending on their component acids, depending on their biological origin. It's getting old. Furthermore, the fats of the simplest and most primitive organisms are usually made from very complex mixtures of fatty acids, but as biological development progresses, the lipids of higher organisms It has become clear that the number of major component acids is decreasing. In the animal kingdom, this type of change is remarkably consistent and culminates in the fats of higher land animals, in which oleic, palmitic, and stearic acids are the only major constituents. All lipids of aquatic origin contain a wide range of bound fatty acids, primarily of the unsaturated series. In passing from aquatic animal fats to terrestrial animal fats, there is also a significant simplification of the composition of mixed fats; with the exception of oleic acid, most of the unsaturated acids disappear. The final result is that in most higher terrestrial animals, the major fatty acid acids are limited to oleic acid, palmitic acid, and stearic acid, and that approximately 60-65% of these acids are saturated or unsaturated.
It belongs to the C ₁₈ series. Thus, the composition of fatty acids obtained from the “splitting device” is
It can vary widely depending on the fat or oil used. The composition of the fatty acid mixture obtained from the "splitting device" is rarely ideal or even satisfactory for most applications. Therefore, fractionation is most commonly used to produce a product that is more desirable for specific end applications than the mixture obtained from a "splitting device." Fractionation based on molecular weight is usually done by
This is achieved during fractional distillation. There is some difference in the volatility of any two fatty acids of different chain lengths,
And in fact, the effectiveness of fractional distillation is due to the absence of odd-numbered acids in natural fats, so that two carbon atoms are almost always the smallest difference in chain length of the fatty acids present in the mixture. be promoted. Fractionation columns in such operations can sometimes produce fatty acids of greater than 95% purity in terms of chain length, depending on the chain length in question. However, commercial fractional distillation may be used to separate unsaturated fatty acids from each other or from saturated fatty acids, or to separate certain saturated fatty acids from each other, if all have the same chain length or a minimal difference in chain length. It is impossible to do so. The method relates to separating certain mixtures of these fatty acids; more particularly, the method relates to separating a first fatty acid from a mixture containing a first fatty acid and a second fatty acid; ,
In this case, when the first fatty acid is stearic acid, the second fatty acid is palmitic acid, and when the first fatty acid is oleic acid, the second fatty acid is linoleic acid. Examples of typical charge mixtures include approximately 1% by volume palmitic acid, 2% by volume stearic acid, 51% by volume oleic acid, 45% by volume linoleic acid, and others.
It consists of 4% by volume. In addition to the fatty acids, the feed mixture that can be charged to the process can contain diluent substances which are not adsorbed by the adsorbent and which are preferably separable from the extract and the raffinate output stream by fractional distillation. If a diluent is used, the concentration of diluent in the mixture of diluent and fatty acids can be from a few percent by volume to about 90 percent by volume. The desorbent materials used in the various prior art adsorptive separation processes vary depending on factors such as the type of operation used. In swing bed systems, where selectively adsorbed feed components are removed from the adsorbent by a purge stream, the choice of desorbent is not critical; it may be gaseous hydrocarbons such as methane, ethane, etc. or nitrogen. Alternatively, desorbent materials containing other types of gases, such as hydrogen, under elevated temperature or reduced pressure, or both, can be used to effectively purge adsorbed feed components from the adsorbent. However, in general, in adsorption separation processes that operate continuously at substantially constant pressure and temperature to ensure a liquid phase,
Desorbent materials must be carefully selected to satisfy a number of criteria. First, the desorbent material is adsorbed at a suitable mass flow rate and without itself being adsorbed so strongly as to unduly prevent extract components from displacing the desorbent material in subsequent adsorption cycles.
Extractable components should be excluded from the adsorbent. In terms of selectivity (discussed in more detail below), an adsorbent is more selective of the extractant component with respect to the raffinate component than it is with respect to the desorbent material with respect to the raffinate component. Preferably it is more selective for all.
Second, the desorbent materials must be compatible with the particular adsorbent and the particular feed mixture. More particularly, they must not reduce or destroy the critical selectivity of the adsorbent for extract components with respect to raffinate components. Additionally, the desorbent materials should be materials that can be easily separated from the feed mixture passed during the process. Both the raffinate stream and the extract stream are mixed with the desorbent material and removed from the adsorbent; therefore, unless a method is used to separate at least a portion of the desorbent material, the purity of the extractant product and the raffinate product may be affected. would not be very high or the desorbent material would not be available for reuse in this process. Therefore, any desorbent material used in the present method
Having an average boiling point that is substantially different from the average boiling point of the feed mixture allows separation of at least a portion of the desorbent material from the feed components in the extract and raffinate stream by simple fractional distillation. It is thus considered preferable to allow reuse of the desorbent material in the present method. As used herein, the term "substantially different" is intended to mean that the difference between the average boiling points of the desorbent material and the charge mixture is at least about 5°C.
The boiling range of the adsorbent material may be higher or lower than that of the feed mixture. Finally, desorbent materials should also be materials that are readily available and therefore of reasonable cost. In the preferred isothermal, isobaric, liquid operation of the process of the invention, we use acetonitrile and methanol; acetonitrile, tetrahydrofuran and water; acetone and water; dimethylacetamide and water; methanol and water; dimethylformamide and water; A particularly effective class of desorbent materials has been found containing one of the mixtures of ammonium hydroxide, water and methanol; and quaternary propylammonium hydroxide, water and methanol. The prior art has also recognized that certain properties of adsorbents are highly desirable, although not absolutely necessary, for the successful operation of selective adsorption processes.
Such properties are equally necessary for the present method. Among these properties are: adsorption capacity for a certain volume of extract components per volume of adsorbent; selective adsorption of extract components with respect to raffinate components and desorbent materials; and
Sufficiently fast rates of adsorption and desorption onto or from the adsorbent. The ability of the adsorbent to adsorb a specific volume of extract components is, of course, a necessary requirement; without such ability, the adsorbent is useless for adsorptive separations. Furthermore, the higher the capacity of the adsorbent for the extract components, the better the adsorbent. As the capacity of a particular adsorbent increases, it is possible to reduce the amount of adsorbent required to separate a known concentration of extract components contained at a particular feed rate of the feed mixture. Reducing the amount of adsorbent required for a particular adsorptive separation reduces the cost of the separation process. A good initial capacity of the adsorbent can be maintained during practical use in separation processes over a certain economically favorable lifetime.
It is important that it is retained. The second necessary adsorbent property is that the adsorbent is capable of separating the feed components; in other words, the adsorbent's adsorption selectivity for one component relative to another component [B]
It is to have. Relative selectivities can be expressed not only for one feed component compared to another, but also between any feed mixture component and the desorbent material. As used throughout this specification, selectivity [B] refers to the ratio of the two components in the adsorbed phase to the same component in the unadsorbed phase under equilibrium conditions.
Defined as the ratio of the ratios of components. The relative selectivity is expressed as the following formula: Formula Selectivity [B] = [Volume % of C / Volume % of D] _A / [Volume % of C / Volume % of D] _U , C and D are The two components of the charge are expressed in volume %, with subscripts A and U representing the adsorbed and unadsorbed phases, respectively. Equilibrium conditions were determined when the feed passing over the adsorbent layer did not change composition after contacting the adsorbent layer. In other words, there was no net mass transfer occurring between the unadsorbed and adsorbed phases. When the selectivity of two components approaches 1.0,
No preferential adsorption of one component by the adsorbent with respect to the other component occurs; they are both adsorbed (or not adsorbed) to approximately the same extent with respect to each other. As the above [B] becomes smaller or larger than 1.0, there is preferential adsorption of one component by the adsorbent with respect to other components. When comparing the selectivity of one component C versus component D by the adsorbent, a [B] greater than 1.0 indicates preferential adsorption of component C within the adsorbent. [B] smaller than 1.0 indicates that component D is preferentially adsorbed and component C
It is shown that more unadsorbed phase and more of component D remain in the adsorbed phase.
Ideally, the sorbent materials should have selectivities for all extractive components equal to or slightly less than 1, such that all of the extractive components have a selectivity of approximately 1 or slightly less than 1 for all extractive components. can be desorbed as a class with a flow rate of , and the extractant components can displace the desorbent material in the next adsorption step. Although separation of one extract component from one roughinate component is theoretically possible if the selectivity of the adsorbent for the extract component with respect to the roughinate component is greater than 1, such selectivity is is preferably close to a value of 2. As with relative volatility, the higher the selectivity, the easier it is to perform the separation. The higher the selectivity, the lower the amount of adsorbent used. A third important property is the rate of exchange of extractive components of the feed mixture material, or in other words, the relative rate of desorption of extractive components. This property is directly related to the amount of desorbent material that must be used in the method to recover the extractant components from the adsorbent; the faster the exchange rate, the more desorption Less desorbent material can be pumped into the process and less desorbent material can be pumped into the process if the exchange rate is faster, which reduces the amount of desorbent material and thus allows for a reduction in the operating costs of the process. Must be separated from the extract stream for reuse. Dynamic test equipment is used to test various adsorbents with specific feed mixtures and desorbent materials to determine adsorbent properties such as adsorption capacity, selectivity, and exchange rate. This device consists of an adsorbent chamber,
This chamber has an inlet and an outlet section at opposite ends of the chamber.
Consists of a helical column with a capacity of 70 c.c. This chamber is placed within a temperature regulating means and a pressure regulating device is further used to operate the chamber at a constant, predetermined pressure. Qualitative and quantitative analytical equipment, such as refractometers, polarimeters, and chromatographs, are used to qualitatively detect one or more components in the effluent stream leaving the adsorbent chamber, attached to the outlet line of the chamber. Or it can be determined quantitatively. Pulse tests performed using this equipment and the general procedure described below are used to determine selectivity and other data for various adsorbent systems. The adsorbent is loaded and equilibrated with the specific desorbent material by passing it through the adsorbent chamber. At a convenient time, a pulse of a charge containing a known concentration of tracer and specific extract or raffinate components or both (all diluted with desorbent) is injected for a period of several minutes. The desorbent flow is resumed and the tracer and extract or raffinate components (or both) are eluted as in a liquid-solid chromatography operation. The effluent can be analyzed on-stream, or alternatively, effluent samples can be collected periodically and later analyzed separately by means of an analyzer and the developed envelope tracing of the corresponding component peaks. . From the information obtained from the above tests, it is clear that the adsorbent capacity is
It can be graded as retention volume, selectivity for one component relative to other components, and rate of desorption of extract components by the desorbent. The retention volume of an extract component or roughinate component can be characterized by the distance between the centers of the envelope of the peak of the extract component or roughinate component and the peak envelope of the racer component or some other known reference point. . This retention volume is expressed as the volume in cubic centimeters of desorbent pumped during this time interval represented by the distance between the peak envelopes. The selectivity for the extract component with respect to the roughinate component [B] is the distance between the centers of the extract component peak envelope and the tracer peak envelope (or other reference point) versus the roughinate component peak envelope. It can be characterized by the ratio of the corresponding center distances of the tracer peak envelopes. The rate of exchange of extract components by a desorbent can generally be characterized by the width of the peak envelope at half intensity. The narrower the peak width, the faster the desorption rate. The rate of desorption can also be characterized by the distance between the envelope of the tracer peak and the center of disappearance of the extract component just desorbed. This distance is also the volume of desorbent pumped during this time interval. Furthermore, to evaluate potential adsorbent systems and translate this type of data into practical separation methods, continuous
Practical testing of the best systems in countercurrent, liquid-solid contacting devices is needed. The general principles of operation of such a device have been described above and are found in Broughton, US Pat. No. 2,985,589. Certain laboratory-sized devices utilizing these principles are available. de Rosset, US Pat. No. 3,706,812. Certain laboratory-sized devices that utilize these principles are available. No. 3,706,812 to Lotse et al. The device consists of multiple adsorbent beds that are attached to distributors within the bed and have a number of ingress and egress lines terminating in rotary distribution valves. At a given valve position, charge and desorbent are being introduced through two of the lines;
And the roughinate and extract streams are being removed through more than one. All remaining input/output lines are inactive, and when the distributor valve position is advanced by one index, all active positions will be advanced by one index. This simulates a condition in which the adsorbent physically moves in a countercurrent direction to the liquid flow. Additional details regarding the nonionic sorbent test equipment and sorbent evaluation techniques described above can be found in 1971.
AJ de Rothsse, RW Neuzil, and DN Rosback presented at the American Chemical Society, Los Angeles, California, March 28-April 2, 2016.
can be found in the paper “Separation of C ₈ Aromatics by Adsorption” by The adsorbents used in the process of the invention are non-ionic, hydrophobic, insoluble cross-linked polystyrene polymers, preferably manufactured by the Rohm and Haas Company and known as "Amberlite".
(Amberlite). Types of Amberlite polymers that have been found useful for use in accordance with the present invention are designated in the Rohm and Haas Company literature as Amberlite XAD-2 and Amberlite XAD-4. , described in the literature as "hard, insoluble spheres of high surface, porous polymers." The various types of Amberlite polymer adsorbents differ in physical properties such as porosity volume, surface area, average pore size, framework density, and nominal mesh size. Applications of Amberlite polymer adsorbents suggested in the Rohm and Haas Company literature include decolorizing pulp mill bleach effluents, decolorizing dye waste, and removing pesticides from waste effluents. Of course, there is no hint in that literature for our surprising discovery of the effectiveness of Amberlite polymer adsorbents in the separation of monoethanoid fatty acids from diethanoid fatty acids. The fundamental advantage of Amberlite polymer adsorbents over crystalline aluminosilicates is that, unlike the latter, the former can be used for the direct separation of fatty acids without first converting them to the corresponding esters. It is possible. The methods of the above-mentioned prior art patents are only applicable to fatty acid esters because the free carboxylic acid groups of the fatty acids chemically react with the crystalline aluminosilicates used by those methods. The adsorbents of the invention do not exhibit such reactivity and the process of the invention is therefore uniquely suited for the separation of fatty acids. The adsorbent can be used as a dense, compact fixed bed that is contacted alternately with the charge mixture and the desorbent materials. In the simplest embodiment of the invention, the adsorbent is used as a single fixed bed, in which case the process is only semi-continuous. In another specific embodiment, one of the two or more fixed layers
The set can be used in a fixed bed in contact with suitable valves, so that the feed mixture is passed through one or more adsorbent beds, while the desorbent substances are passed through one or more adsorbent beds within said set. It can be passed through other layers. The flow of the charge mixture and desorbent materials may be either upward or downward within the desorbent. Any of the conventional equipment used in fixed bed fluid-solid contacting can be used. However, a countercurrent moving bed or similar moving bed countercurrent flow system has a much higher separation efficiency than a fixed adsorbent bed and is therefore preferred. In a moving bed or simulated moving bed process, the adsorption and desorption operations occur continuously, which provides for both continuous production of extract and raffinate streams and continuous use of charge and desorbent streams. . One preferred embodiment of the method uses what is known in the art as a similar transfer layer. The principles and sequence of operation of such a flow system are described in US Pat. No. 2,985,589, which is hereby incorporated by reference. In such systems, it is the forward movement of the composite liquid entry/exit point below the adsorbent chamber that simulates the upward movement of the adsorbent contained within the adsorbent chamber. Only four of the input and output lines are active at any one time: the feed input stream, desorbent inlet stream, ruffinate outlet stream, and extract outlet stream lines. This mimicking, upward movement of the solid adsorbent and the movement of the liquid occupying the void volume of the packed bed of adsorbent overlap. Liquid flow below the adsorbent chamber can be provided by a pump so that countercurrent contact is maintained. As one active liquid entry/exit point moves through a cycle, ie from the top to the bottom of the chamber, the chamber circulation pump moves through different zones requiring different flow rates. Programmed flow regulators can be provided to set and regulate these flow rates. The active liquid entry and exit points effectively divide the adsorbent chamber into separate zones, each having a different function.
In this embodiment of the method, it is generally necessary that three separate operating bands exist for the method to occur, although in some instances an optional fourth band can be used. The adsorption zone, Zone 1, is defined as the adsorbent between the feed inlet stream and the roughinate outlet stream. Within this zone, the feed is contacted with an adsorbent, extract components are adsorbed, and a raffinate stream is removed. Since the general flow through zone 1 is either the feed flow entering this zone or the roughinate flow exiting this zone, the flow within this zone is considered to be in the downstream direction as it progresses from the feed inlet stream to the roughinate outlet stream. . Immediately upstream with respect to fluid flow within zone 1 is a purification zone, zone 2. This purification zone is defined as the adsorbent between the extract outlet stream and the feed inlet stream. The basic operations that take place within zone 2 are the removal of the raffinate material carried into zone 2 by the movement of the adsorbent into this zone from the non-selective void volume of the adsorbent, and the selective removal of the adsorbent from the non-selective void volume. It is the desorption of ruffinate material adsorbed within the pore volume or adsorbed onto the surface of the adsorbent particles. Purification is accomplished by passing a portion of the extract stream material leaving zone 3 into zone 2 at the upstream boundary of zone 2, the extract outlet stream, to eliminate raffinate material. The material flow in zone 2 is in the downstream direction from the extract outlet stream to the feed inlet stream. Immediately upstream of zone 2 with respect to the fluid flowing within zone 2 is a desorption zone, zone 3. This desorption zone is defined as the desorbent between the desorbent inlet stream and the extract outlet stream. The function of the desorption zone is to eliminate, by the desorbent material entering this zone, the extract components adsorbed onto the adsorbent during contact with the previous charge in zone 1 in the previous operating cycle. It is.
The fluid flow in zone 3 is substantially in the same direction as zones 1 and 2. In some examples, an arbitrary buffer band, Band 4, can be used. This zone, defined as adsorbent between the roughinate outlet stream and the desorbent inlet stream, is immediately upstream with respect to fluid flow into zone 3, if used. Zone 4 would be used to conserve the amount of desorbent used in the desorption process, by passing a portion of the raffinate stream removed from zone 1 into this zone. This is because the desorbent material present therein can be removed from this zone and transferred to the desorption zone. Zone 4 has sufficient water content to prevent roughinate material present in the roughinate stream exiting zone 1 and passing into zone 4 from entering zone 3 and contaminating the extract stream being removed from zone 3. It will contain an adsorbent. In instances where the fourth operating zone is not used, the direct flow from zone 1 to zone 3 is The raffinate stream passed from zone 1 to zone 4 must be carefully monitored to prevent contamination of the extract outlet stream by stopping the flow. Circular progression of the input and output streams through a fixed bed of adsorbent can be accomplished using a manifold system in which valves are operated sequentially to move the input and output streams, thus countercurrent,
Provides fluid flow to the solid adsorbent. Another method of operation that can achieve countercurrent flow of solid adsorbent to fluid involves the use of rotating small disc valves, where the input and output flows are the feed input, extract output, desorption The agent input and raffinate output flows are connected to passing valves and lines to advance in the same direction through the adsorbent bed. Manifold arrangements and small disk valves are known in the art. Specifically, rotating small disc valves that can be used in this operation can be found in US Pat. Nos. 3,040,777 and 3,422,848. Both of the above-mentioned patents disclose rotary coupling valves that allow the proper progression of various input and output streams from a fixed source to be achieved without difficulty. In many instances, one operating zone will contain much more adsorbent than some other operating zones. For example, in some operations, the buffer zone may contain a small amount of adsorbent compared to that required for the adsorption and purification zones.
In instances where a desorbent is used that can easily desorb the extract material from the adsorbent, a relatively small amount of adsorbent is required in the desorption zone compared to the amount of adsorbent required in the buffer zone or the adsorption zone or the purification zone or all of these. It is understandable that medication may be required.
Since the adsorbent need not be in a single column, the use of multiple chambers or a series of columns is also within the scope of the invention. It is not necessary that all of the input or output streams be used at the same time; in fact, in many instances, some of the streams can be shut off while others input or output material. Apparatus that can be used to accomplish the invention includes mounting various input or output streams,
It can also contain a series of individual layers connected by connecting conduits carrying input or output taps that can be moved alternately and periodically to achieve continuous operation. In some instances, the connecting conduit can be connected to a transfer tap that does not function as a conduit for materials to enter or exit the method during normal operation. At least a portion of the extract output stream enters a separation means in which at least a portion of the desorbent material may be separated to yield an extract product containing a reduced concentration of the desorbent material. is possible. Preferably, but not necessarily, for operation of the process, at least a portion of the raffinate output stream is also passed through a separation means in which at least a portion of the desorbent material is separated and purified. A desorbent material that can be reused in the process and a ruffinate product containing a reduced concentration of desorbent material can be produced. This separation means will typically be a fractionation column, the design and operation of which are well known to the separation art. DB Bluffton U.S. Patent No. 2985589 and
DB presented at the 34th Annual Meeting of the Society of Chemical Engineers, Tokyo, Japan, April 2, 1969.
Bluffton's “Continuous Adsorption Processing…
Reference may be made to the paper entitled "...New Separation Technology", both of which are incorporated herein by reference to further explain the analogous moving bed countercurrent flow process diagram. Although both can be used in many adsorption separation methods, liquid phase operation is preferred because of the lower temperature requirements and because the yield of extract obtained with liquid phase operation is higher than that obtained with gas phase operation. .Adsorption conditions are about 20℃ to about 200℃, preferably about 20℃ to ensure a liquid phase.
Temperature range from about 100°C to about atmospheric pressure to about
It will include a pressure range of 500 psig (3450 kPa gauge), preferably about atmospheric pressure to about 250 psig (1725 kPa gauge). Desorption conditions will include the same range of temperature and pressure used for adsorption conditions. The unit sizes for which the method of the invention can be used are pilot plant scale (e.g., as described in our assignee's U.S. Patent No.
3705812) to commercial scale, and the flow rate is several C per hour.
C. Can range from a small amount to many thousands of gallons per hour. The following examples are presented to illustrate the selectivity relationships that enable the method of the invention. The examples are not intended to unduly limit the scope or spirit of the claims. Example I This example shows the results of Amberlite XAD-2 and Amberlite for linoleic and oleic acids.
Figure 2 shows the selectivity of two Amberlite polymer adsorbents consisting of XAD-4. The charge mixture consisted of the desorbent used in the pulse test in question and tall oil fatty acids, with a ratio of desorbent to tall oil fatty acids of 90:10. Tall oil fatty acids have the following composition: Fatty acids Palmitic acid (C ₁₆ 0) 1 Stearic acid (C ₁₈ 0) 2 Oleic acid (C ₁₈ 1) 51 Linoleic acid (C ₁₈ 2) 45 Others 4 Retention volume and Selectivity was obtained using the pulse test equipment and procedure described above. Specifically, the adsorbent was tested in a 70 c.c. helical coil column using the following sequence of operations for each pulse test. The desorbent material was run continuously through the column containing the adsorbent at a nominal hourly space velocity (LHSV) of approximately 1.0. Void volume was determined by measuring the volume of desorbent required to fill a packed drying column. At a convenient time, the flow of desorbent material was stopped and a 10 c.c. sample of the charge mixture was injected into the column via the sample loop, and the flow of desorbent material was resumed. Effluent samples were automatically collected into an automatic sample collector and subsequently analyzed by chromatographic analysis. From analysis of these samples, peak envelope concentrations were developed for the charge mixture components. The retention capacity for fatty acids was calculated by measuring the distance from time zero on the reference point to the respective midpoint value of the fatty acid and subtracting the distance representing the void volume of the adsorbent. The selectivity of an adsorbent over oleic acid with respect to linoleic acid in the presence of a desorbent material is the quotient of the retention capacity for oleic acid divided by the retention capacity for linoleic acid. The results of these pulse tests are shown in Table 1.

TABLE FIG. 1 is an example of one graphical representation of a pulse test whose test data is listed in Table 1. This pulse test was performed using Amberlite XAD-2 adsorbent and 85%
Dimethylformamide-15% water desorbent was used at 90°C. As shown in Figure 1,
Linoleic acid is eluted first, followed by oleic acid. Table 1 and Figure 1 show that certain desorbent mixture combinations were used for the separation of fatty acids having 18 carbon atoms per molecule, and in particular for such combinations.
This shows that oleic acid is more strongly adsorbed than linoleic acid. Moreover, the separations achieved for many of these combinations, as illustrated in FIG. 1, are substantial and clearly commercially viable. EXAMPLE This example shows that the ratio of desorbent to acid mixture is 90:10.
Figure 2 shows the results of using Amberlite XAD-2 to separate stearic acid from an approximately 50:50 mixture of stearic acid and palmitic acid diluted in a desorbent. The desorbent used is 85% by weight dimethylformamide and/5% by weight water. Data were obtained at a temperature of 90° C. using the pulse test equipment and procedure described above. Specifically, the adsorbent
It was placed in a 70 c.c. helical coil column and the following sequence of operations was used. The desorbent material was run continuously in upward flow through the column containing the adsorbent at a flow rate of 1.2 ml/min. At a convenient time, the flow of desorbent material was stopped and a 10 c.c. sample of the charge mixture was injected into the column via the sample loop, and the flow of desorbent was restarted. A sample of the effluent was automatically collected in an automatic sample collector and later analyzed by chromatographic analysis. FIG. 2 is a graphical representation of the results of a pulse test. Second
The figure shows that stearic acid is more strongly adsorbed than palmitic acid, especially for the desorbent mixture used. Furthermore, the separation achieved for this combination is substantial and clearly commercially viable.

[Brief explanation of the drawing]

1 and 2 are both graphical representations of the results of pulse tests performed on the method of the invention.

Claims (1)

[Claims] 1. A mixture of a first fatty acid selected from the group consisting of stearic acid and oleic acid and a second fatty acid selected from the group consisting of palmitic acid and linoleic acid is heated at about 20°C to about 200°C. Temperatures within the range of °C and about atmospheric pressure to about 500 psig (3450 kPa gauge)
Under adsorption conditions including pressures in the range of
From the above mixture, the first
A method for separating acids, wherein when the first acid is stearic acid, the second acid is palmitic acid, and when the first acid is oleic acid, the second acid is How is linoleic acid. 2. The method of claim 1, wherein the first fatty acid is recovered by desorption with a desorbent under desorption conditions. 3. The method of claim 2, wherein the desorption conditions include a temperature in the range of about 20°C to about 200°C and a pressure in the range of about atmospheric pressure to about 500 psig (3450 kPa gauge). 4. A method according to claim 3, characterized in that the method is carried out in liquid phase. 5 The desorbent is a mixture of acetonitrile and methanol, a mixture of acetonitrile, tetrahydrofuran and water, a mixture of acetone and water, a mixture of dimethylacetamide and water, a mixture of methanol and water, a mixture of dimethylformamide and water, or quaternary methylammonium. 2. The method according to claim 1, wherein the method is one of a mixture of hydroxide, water and methanol, and a mixture of quaternary propylammonium hydroxide, water and methanol. 6. When separating stearic acid or oleic acid from a mixture of stearic acid and palmitic acid or a mixture of oleic acid and linoleic acid using an adsorbent made of a nonionic, hydrophobic, and insoluble crosslinked polystyrene polymer, (a) at least three, each with different operating functions;
(b) having a net fluid flow in a single direction through a column of said adsorbent having five zones with the end zones interconnected such that each zone is connected in series; (c) an adsorption zone located between the feed input stream at the upstream boundary of a zone and the roughinate output stream at the downstream boundary of the zone; (c) located immediately upstream of said adsorption zone; (d) a zone located immediately upstream of said purification zone; a zone located between the extract output stream at the upstream boundary of the zone and the feed input stream at the downstream boundary; a desorption zone located between the desorbent input stream at the upstream boundary of the zone and the extractant output stream at the downstream boundary; selectively adsorbing stearic acid or oleic acid onto the adsorbent in the zone through adsorption conditions at a temperature of about 20° C. to about 200° C. and a pressure of about atmospheric pressure to about 500 psig (3450 kPa gauge). and (f) removing a desorbent material into the desorption zone at a temperature from about 20°C to about 200°C at which the liquid phase is maintained. (g) containing stearic acid or oleic acid and a desorbent material; (h) passing at least a portion of the extract output stream through separation means under separation conditions to separate at least a portion of the desorbent material; (i) removing at least a portion of the desorbent material from the feed; An input stream, a roughinate output stream, a desorbent input stream, and an extract output stream are periodically advanced through the adsorbent column in a downstream direction with respect to the fluid flow within the adsorption zone to convert each zone in turn. A fatty acid separation method that generates an extract output stream and a roughinate output stream while 7 passing at least a portion of said roughinate output stream through separation means under separation conditions to separate at least a portion of said desorbent material to obtain a roughinate product having a reduced concentration of desorbent material; 7. A method according to claim 6, characterized in that: 8. A buffer zone containing the adsorbent is provided immediately upstream of the desorption zone, and a desorbent input flow is located at the downstream boundary of the zone, and a roughinate output flow is located at the upstream boundary. A method according to claim 6. 9 The desorbent is a mixture of acetonitrile and methanol, a mixture of acetonitrile, tetrahydrofuran and water, a mixture of acetone and water, a mixture of dimethylacetamide and water, a mixture of methanol and water, a mixture of dimethylformamide and water, or quaternary methylammonium. 7. The method according to claim 6, wherein the method is one of a mixture of hydroxide, water and methanol, and a mixture of quaternary propylammonium hydroxide, water and methanol.