FI74488C - FOERFARANDE OCH MOLEKYLSIL FOER SEPARERING AV OLEINSYRA FRAON LINOLSYRA. - Google Patents

Description

Λ 1 74488

Method and molecular sieve for separating oleic acid from linoleic acid

The invention relates to the separation of fatty acids in a solid layer by means of molecular sieves. More specifically, the invention relates to a process for separating oleic acid from linoleic acid using a Mole alkyl screen formed by silicalite.

It is known from the separation technique that certain crystalline aluminosilicates can be used to separate certain esters of fatty acids from their mixtures. For example, U.S. Patents 4,048,205, 4,049,688 and 4,066,677 disclose methods for separating fatty acid esters of various degrees of unsaturation from mixtures of saturated and unsaturated fatty acids. These methods use adsorbents which form an X or Y zeolite containing · '. at the cationic binding sites of the selected cation.

The present invention, on the other hand, experiences the separation of certain fatty acids rather than fatty acid esters. It has been found that a particular molecular sieve having selectivity for one unsaturated fatty acid over another unsaturated fatty acid thus allows such fatty acids to be separated by selective retention into a solid layer. It has further been found that there is an increased effectiveness of specific displacement fluids under certain displacement conditions. According to an embodiment of the invention, a method for separating oleic acid from linolenic acid is provided. Fatty acids are widely used as plasticizers and surfactants. Fatty acid derivatives are valuable in the formation of lubricating oils, such as in the lubrication of textiles and molds, in certain varnishes, as water-resistant substances, in cosmetics and pharmaceuticals, and as naturally degradable detergents.

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It has been found that bridging lite, which is a non-zeolite, hydrophobic, crystalline silica molecular sieve, is very well suited for the separation treatment according to the invention because it first has an affinity for fatty acid compared to resin acid , and secondly, it has an affinity for oleic acid compared to linolenic acid.

In the accompanying drawings, Figure 1 schematically shows an embodiment of the invention, which is a simulated moving bed with an adsorption column 1, a piping system 3 and various connecting lines described below, Figures 2, 3 and 4 show graphically the values obtained in the examples below.

Briefly, one embodiment of the invention comprises a method of separating oleic acid from linoleic acid contained in a raw material mixture comprising these acids, said method comprising contacting the raw material mixture under separation conditions with a molecular sieve of silicalite to selectively retain oleic acid then from the molecular sieve by displacement with a displacement fluid under displacement conditions.

Another embodiment of the invention comprises a method of separating oleic acid from linoleic acid in a feed mixture containing these acids using a molecular sieve formed by silicalite, the method comprising the steps of: (a) maintaining a net flow of liquid through the molecular sieve column in one direction, including at least three zones; processing operations and which are connected in series with the end zones of the statue and combined so as to provide a continuous connection of the 3 74488 zones? (b) maintaining a retention zone in the column, wherein the zone is formed by a molecular sieve located between the feed stream of the upstream boundary of the zone and the raffinate effluent of the downstream of the zones; (c) maintaining the purification zone immediately upstream of the retention zone, the purification zone being formed by a molecular sieve located at the upstream flow point of the extract at the upstream boundary of the purification zone and the feed stream at the downstream boundary of the purification zone; (d) maintaining a displacement zone immediately upstream of the purification zone, wherein the displacement zone is bounded by a molecular sieve located between the displacement fluid feed stream at the upstream boundary of the zone and the extract effluent at the downstream boundary of the zone; (e) raw material flow. . introducing into the retention zone under separation conditions such as to provide for selective retention of oleic acid by a molecular sieve in the retention zone and removal of the raffinate effluent from the retention zone; (f) introducing a displacement liquid into the displacement zone under displacement conditions to effect displacement of oleic acid from the adsorbent in the displacement zone; (g) extracting an extract stream comprising oleic acid and displacing fluid from the displacement zone; (h) periodically passing the feed stream, the raffinate effluent, the displacement liquid inlet stream, and the extract effluent stream and the raffinate effluent stream downstream of the molecular sieve column with respect to the liquid flow in the retention zone.

Other embodiments of the invention comprise details relating to raw material mixtures, molecular sieves, displacement; liquids and handling conditions, all of which are discussed in more detail below in the detailed description of the invention.

The various terms used in this specification to explain the operation, objects, and advantages of the method of the invention are defined below.

A "feedstock mixture" is a mixture containing one or more extract components and one or more raffinate components that are separated in the process of the invention. The term "feed stream" means the stream of the raw material mixture that is passed through the molecular sieve used in the process.

An "extract component" is a compound or species of compound that is retained by a molecular sieve, while a "raffinate component" is a compound or species of compound that is not retained. In this process, oleic acid is the extract component and linoleic acid is the raffinate component. "Displacement fluid" generally means a fluid capable of displacing an extract component. "Displacement fluid flow" or "displacement fluid input flow" means the flow through which the displacement fluid passes. . molecular sieve. "Diluent" or "diluent stream": means the stream through which the diluent enters the molecular sieve. "Raffinate stream" or "raffinate removal stream" means a stream by which a raffinate component is removed from a molecular sieve. The composition of the raffinate stream can range from substantially 100% displacement fluid to substantially 100% raffinate component and. "Extract stream" or "extract effluent" means a stream by which an extract material displaced by a displacement liquid is removed from a molecular sieve. The composition of the extract stream can also range from substantially 100% displacement fluid to substantially 100% extract components. At least a portion of the extract stream from the separation treatment, and preferably a portion of the raffinate stream, is passed to separation equipment, usually fractionation equipment, in which at least a portion of the displacement liquid and diluent are separated to obtain an extract product and a raffinate product. The terms "extract product" and "raffinate product" refer to products prepared in this process and containing the extract component and the raffinate component at a higher concentration than in the extract stream and the raffinate stream, respectively. Although the process of the invention makes it possible to prepare a high purity fatty acid product and a rosin acid product (or both) in high yield, it should be noted that the molecular sieve never completely retains the extract component nor the raffinate component. As a result, the raffinate component may be present in varying amounts in the extract stream and similarly the extract component may be present in varying amounts in the raffinate stream. The extract and raffinate streams are then further separated from each other and from the feedstock based on the concentration ratio present in the particular stream between the extract component and the raffinate component. More specifically, the ratio of fatty acid concentration to non-retained resin acid is lowest in the raffinate stream, followed by the highest in the feedstock mixture and highest in the extract stream. Similarly, the ratio of rosin acid concentration to retained fatty acid is highest in the raffinate stream, next highest in the feedstock mixture and lowest in the extract stream.

By "selective pore volume" of a molecular sieve is meant the volume of the molecular sieve that selectively retains the extract component from the raw material mixture. The "non-selective pore volume" of a molecular sieve is the volume of the molecular sieve that does not selectively retain the extract component from the raw material mixture. This volume includes those pores of the molecular sieve that receive the raffinate components and the spaces between the particles of the molecular sieve. Selective pore volume and non-selective pore volume are generally expressed in units of volume and are important in determining the correct fluid flow rates to be introduced into the treatment zone to perform efficient treatment using a given amount of molecular sieves. When a molecular sieve "enters" a treatment zone (described in more detail below) in accordance with one embodiment of the invention, its non-selective pore volume, together with its selective pore volume, transports fluid to that zone. The non-selective pore volume is used to determine the amount of liquid that must be introduced into the same zone upstream of the molecular sieve to displace the liquid in the non-selective pore volume. If the flow rate of the liquid passing into a given zone is less than the non-selective pore volume of the molecular sieve entering that zone, the molecular sieve will cause additional fluid retention in that zone. Because this additional retention consists of a liquid present in the non-selective pore volume of the molecular sieve, in most cases it contains unrestrained components of the raw material.

Before considering the raw material mixtures that can be derived from the treatment according to the invention, the terminology and the preparation of fatty acids in general will be briefly discussed first. Fatty acids are a large group of aliphatic monocarboxylic acids, many of which are present as glycerides (glycerol esters) in natural fats and oils. Although the term "fatty acids" is limited to a few saturated acids of the acetic acid series, both straight and branched chain, it is commonly used herein to include similar unsaturated acids, certain substituted acids, and even aliphatic acids containing alicyclic acids. Naturally occurring fatty acids are, with a few exceptions, higher straight chain, unsubstituted acids with an even number of carbon atoms. Unsaturated fatty acids can be divided into monoethanides, dietanoids, trietanoides, etc. (or monoethylene, etc.) based on the number of double bonds in the hydrocarbon chain. Thus, the term "unsaturated fatty acids" generally refers to fatty acids having at least one double bond, and the term "polyethanoid fatty acids" refers to fatty acids having more than one double bond in a molecule. Fatty acids are usually prepared from glyceride fats or oils using any of a number of "cleavage" or hydrolytic methods. In all cases, the hydrolysis reaction can be considered as a reaction of a fat or oil with water, 7 74488 to give fatty acids plus glycerol. In modern fatty acid production plants, this method is carried out by continuously carrying out the hydrolysis of fat at high pressure and high temperature. Examples of starting materials commonly used in the preparation of fatty acids include coconut oil, palm oil, inedible animal fats and commonly used vegetable oils, soybean oil, cottonseed oil and corn oil.

The source of fatty acids which is the main subject of the present invention is tall oil, a by-product of the pulp industry which is usually recovered from black liquor in the production of pine pulp by the sulphate or power pulp process. Tall oil contains about 50-60% fatty acids and about 34-40% resin acids. Fatty acids include oleic, linoleic, palmitic and stearic acids. Linoleic and oleic acids make up 90% of the fatty acids in tall oil. Resin acids, such as abietic acid, are monocarboxylic acids having a molecular structure containing carbon, hydrogen and oxygen, and in which: there are three fused 6-membered carbon rings which give a much larger molecular diameter of the resin acids than the fatty acids.

The raw material mixtures fed to the process according to the invention may contain, in addition to the tall oil components, a diluent which is not adsorbed by the adsorbent and which can advantageously be separated from the extract and raffinate by fractional distillation. When a diluent is used, its concentration in the mixture of diluent and acids is preferably from a few volume percent to about 75 volume percent, with the remainder being fatty and rosin acids. Although it has been found in the past, e.g. in U.S. Patent No. 4,329,280, that silicalite is effective in separating fatty and rosin acid esters, the separation of free acids using silicalite has not previously been accomplished.

The displacement fluids previously used in various adsorbent and molecular sieve 8 74488 separation treatments vary depending on such factors as the quality of the treatment. In various separation treatments that operate continuously at substantially constant pressures and temperatures to ensure a liquid phase and that use a molecular sieve, the displacement material must be carefully selected to meet a number of requirements. First, the displacing agent should displace the extract component from the molecular sieve using reasonable mass flow rates, but still allow the extract component to enter the molecular sieve without adversely preventing the extract component from displacing the displacement material in the subsequent separation cycle. In addition, the displacement fluids must be substances that are easily separable from the raw material mixture fed to the treatment. Both the raffinate stream and the extract stream are removed from the molecular sieve in admixture with the displacement liquid and unless a method is used to separate at least a portion of the displacement liquid, the purity of the extract product and the raffinate product is not very high and the displacement liquid cannot be used for reprocessing. Consequently, it has been found that the displacement liquid used in the treatment should be such that it preferably has a significantly different average boiling point compared to the feedstock mixture, so that at least some of the displacement fluid components in the extract and raffinate streams can be separated. by fractional distillation, which allows reuse of the displacement liquid in the treatment. As used herein, the term "substantially different" means that the difference in average boiling point between the displacement fluid and the raw material mixture should be at least about 5 ° C. The boiling range of the displacement liquid may be higher or lower compared to the raw material mixture. Finally, Syr antifreezes should be those that are; readily available and therefore reasonably priced. In the most preferred isothermal, isobaric, and liquid phase treatments of the present invention, it has been found, as discussed in more detail below, that the most preferred are displacement fluids that comprise a diluent soluble in the feedstock having a polarity index of at least 3.5.

The most effective displacement fluid is an organic acid.

However, it has been found that silicalite can also be ineffective in separating fatty and resin acids or fatty acids from each other when using a molecular sieve layer in redistribution after a displacement step. When the displacement fluid is present in the bed, selective retention of the fatty acid no longer occurs. It is believed that the displacement fluid, especially the organic acid, participates in or even catalyzes hydrogen-bound dimerization reactions, in which reaction there is a similarity between the fatty and resin acid molecules and possibly the displacement fluid molecules. These dimerization reactions can be represented by the formulas: fa + fa s (fafa) RA + RA "O (RARA) FA + RA (FARA) in which FA and RA are fatty or resinic acids, respectively. The organic acid displacement liquid molecules must be The dimers prevent the separation of fatty and rosin acids from each other by preventing the former from entering the pores of the molecular sieve The inhibition of separation due to the presence of dimers does not appear to be: an essential problem in the above process.

It has been found that the above-mentioned dimerization reactions can be reduced at least to the extent necessary to enable the separation of resin and / or fatty acids by first rinsing the molecular sieve with a suitable diluent. This diluent removes the displacement fluid from at least the non-selective pore volume of the molecular sieve. Adequate separation requires, firstly, the dissolution of the components of the feedstock stream in the diluent, as well as the easy separation of the diluent 10 74488 in a conventional manner, such as by means of a displacement liquid.

It has also been found that the above-mentioned pre-rinsing can also be avoided if the polarity index of the displacement liquid is at least 3.5. A preferred displacement fluid having a polarity index of at least 3.5 is a short chain organic acid having a chain length of 2 to 5 carbon atoms in solution with a diluent capable of reducing dimerization. The measure of this property is the polarity index of the liquid.

The polarity index is described in the article "Classification of the Solvent Properties of Common Liquids"; Snyder L.J., Chromatography, £ 2, 223 (1974), which is incorporated herein by reference. The diluent should contain about 50-95% by volume of displacement fluid. The polarity indices of certain selected diluents are as follows:

Solvent Polarity Index

Isooctane -0.4 n-hexane 0.0 toluene 2,3 p-xylene 2.4 benzene 3.0 methyl ethyl ketone 4.5 acetone 5.4

Acetone, methyl ethyl ketone and diethyl ketone are the most preferred diluents.

It should be noted that diluents having a polarity index of at least 3.5 are particularly preferred displacement liquids, especially when the temperature at which the displacement is carried out is about 120-150 ° C. Also in this case, acetone, methyl ethyl ketone and diethyl ketone are most preferred. This is an improvement over the practice of using a solution of such a diluent and an organic acid as a displacement liquid at a relatively low temperature. The main disadvantage of using such a solution is that the recovery of organic 11 74488 acid from the product stream is relatively energy intensive and also requires a high temperature to carry out the distillation, which causes thermal decomposition of the fatty acids. Another advantage is that the corrosion caused by short-chain organic acids is eliminated.

The molecular sieve used in the process of the invention is silicalite. As mentioned above, silica potassium is a hydrophobic, crystalline silica molecular sieve. Silicalite is described in U.S. Patents 4,061,724 and 4,104,294, which are incorporated herein by reference. Due to its aluminum-free structure, silicalite has no ion exchange properties and is hydrophobic and organophilic. Silicalite thus forms a molecular sieve, but is not a zeolite. Silicalite is uniquely suitable for use in the separation treatment according to the invention due to the fact that its pore size and shape are such that this allows the silicalite to function as a molecular sieve, i. it receives fatty acid molecules in its pores, i.e. its internal structure, but does not receive resin acid molecules. Silicalite is described in detail in the article "Silicalite, A New Hydrophobic Crystalline Silica Molecular Sieve"; Nature, Vol. 271, February 9, 1978, to which reference is made in this connection.

Silicalite, in the same way as previously known adsorbents or molecular sieves, is most preferably used in combination with a suitable binder. The binder promotes the formation or agglomeration of the crystalline parts of the silicalite, otherwise it is formed by a fine powder. Not all binders previously used are suitable for freezing in the separation of tall oil components due to the reactivity of the binder or the effect on the separation treatment.

A binder has now been invented which, in combination with silicalite, provides a new molecular sieve which is uniquely suitable for separating tall oil constituents.

Silicalite is bound by silica, i. silicalite 12 74488 is combined with a silica matrix. The silicalite is combined with silica by dispersing the silicalite powder in colloidal, amorphous silica to give a precursor, this precursor is gelled, and this gel is then treated to provide substantially complete removal of hydroxyl groups from the silica and silica matrix. Colloidal amorphous silica comprises an aqueous colloidal dispersion of amorphous silica particles, and gelation is preferably accomplished by removing water from this dispersion, although other gelation methods may be used, such as changing the pH or adding salt or a water-miscible organic solvent. Silicalite should be present in the silica material in amounts of about 75-98% by weight of silicalite based on the mixture of non-volatile materials. Prior to treatment of the gel, it is extruded to remove hydroxyl groups, preferably still in a plastic state, and then broken up into separate particles. The plastic condition occurs for at least part of the time. during which the water is removed to effect gelation. After treatment, the particles can be further ground to be more physically suitable for use in a particular separation treatment, usually a fineness of 16-60 (Standard U.S. Mesch).

The colloidal amorphous silica most preferred for use in accordance with the invention is that described by Du Pont Co. markets under the trademark "Ludox". Colloidal Silica "Ludox" is silica formed by discrete, homogeneous spheres having no internal surface area or detectable crystallinity, dispersed in an alkaline medium that reacts with the surface of the silica to form a negative charge. The pH of the alkaline medium is maintained in the range of about 8.5-11.0. The stabilizing cations in this alkaline medium may be sodium or ammonium ions. The concentration of silica in the colloidal dispersion can be about 30-50% by weight, calculated as SiO 2.

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The literature of Du Pont Co describing the colloidal silica "Ludox" shows that during drying, the hydroxyl groups on the surfaces of the silica particles condense to cleave water to form siloxane bonds (Si - 0 - Si), which causes fusion, bonding of the particles to each other. and particles that are chemically inert and heat resistant. However, it has been found that further drying of silica-bonded silica under the conditions used in this art to effect drying, i. heating in an air furnace at a temperature slightly above 100 ° C provides a molecular sieve that is not suitable for separating the constituents of tall oil. Such a molecular sieve reacts with fatty and rosin acids, and the separation obtained is very poor, since the fatty acid components leave considerably waste of rosin acid components. The reason which is presumed to cause such behavior is that what is stated in Du Pont Co's literature on the formation of siloxane bonds during normal drying is essentially true, but a very small amount of hydroxyl groups (or ammonium groups remain if the stabilizing cations are ammonium ions). ), which are irrelevant for most practical purposes, but which make the adsorbent completely unsuitable for use in the process according to the invention. In this context, it should be noted that other silicalite binders have also been tried, but with equally poor results. Organic binders, such as polyvinyl alcohol, are unsuitable, probably due to the presence of hydroxyl groups. Binders formed from natural clay have selectivity for certain constituents of tall oil and thus affect the effectiveness of silicalite.

As a result, it is necessary to treat the gelled silica-bonded silicalite in the above-mentioned manner to remove hydroxyl groups and replace them with siloxane bonds. The obtained silicalite in the obtained silica matrix molecular sieve is very suitable for separating pine oil components, since it provides an excellent separating effect of pure silicalite and at the same time a physically strong and stable molecular sieve suitable for factory scale.

There are several ways to treat gelled silica-bound silicate to achieve substantially complete removal of hydroxyl groups. One method is heat treatment in the temperature range of about 450-1000 ° C, with a minimum treatment time of about 3-48 h, which can occur in the presence of oxygen, nitrogen and / or hydrogen. Another way is to first contact the molecular sieve with an alcohol such as ethanol and then heat treat the molecular sieve at an elevated temperature (above about 350 ° C) in the presence of oxygen. A third way to eliminate hyoxyl groups is to chlorinate the molecular sieve at an elevated temperature, as disclosed in, e.g., U.S. Patent 4,308,172, wherein the molecular sieve is contacted at an elevated temperature with a chlorinating agent (e.g., CCl 4, CO 2 Cl 2 The molecular sieve is dechlorinated at elevated temperature and the dechlorinated molecular sieve is oxidized at elevated temperature.

Another way to effect the removal of hydroxyl groups by chlorination is to contact the molecular sieve at an elevated temperature with a mixture of oxygen and silicon tetrachloride.

The molecular sieve can be used in the form of a dense, uniform, solid layer which is contacted alternately with the raw material mixture and the displacement liquid. According to the simplest embodiment of the invention, a molecular sieve is used in the form of a single static layer, in which case the treatment is only semi-continuous. In another embodiment, a series of two or more static layers may be used in a solid layer having a suitable valve arrangement such that the raw material mixture is passed through one or more molecular sieve layers, while the displacement fluid may be passed through one or more other layers in the series. . The flow of the raw material mixture and the displacement liquid through the molecular sieve can take place either upwards or downwards. Any conventional equipment used in the static layer to bring the liquid and solid into contact can be used.

However, a countercurrent moving bed system or a simulated countercurrent moving bed system has a much higher separation efficiency than fixed bed based systems and is therefore the most preferred. In systems based on a moving bed or a simulated moving bed, retention and displacement treatments take place continuously, which enables both the continuous production of extract and raffinate streams and the continuous use of feed and displacement fluid streams and possibly the necessary rinsing stream. In a preferred embodiment of this method, the so-called simulated moving bed countercurrent system. The principles and steps of handling such a flow system are set forth in U.S. Patent 2,985,589, which is incorporated herein by reference. In such a system, the successive downward movement of multiple fluid inlets in the molecular sieve chamber simulates the upward movement of the molecular sieve in the chamber. Only five inlet lines operate at any one time, namely, feedstock feed flow, displacement fluid feed flow, rinse fluid feed flow, raffinate discharge flow, and extract discharge flow. Simultaneously with the simulated upward flow of this solid molecular sieve, the movement of the liquid that fills the pore volume of the dense layer of the molecular sieve takes place. In order to maintain countercurrent contact, the downward flow of liquid in the molecular sieve chamber can be provided by a pump.

When the active fluid inlet moves through the cycle, i.e. from the top of the chamber to its bottom, the circulation pump of the chamber moves through different zones where different flow rates are required. A programmed flow control device can be used to achieve and control these flow rates.

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The active fluid inlets efficiently divide the molecular sieve chamber into separate zones, each with a different function. In this embodiment of the treatment, it is generally necessary for three separate treatment zones to be present in order for the treatment to take place, although in a few cases four zones may be used.

The positive net flow of fluid occurs through all parts of the column in the same direction, although the composition and velocity of the fluid flow will naturally vary from point to point. Figure 1 shows zones I, II, lii and IV, as well as piping system 3, pump 2, which provides a positive net flow of liquid, and line 4, which is connected to pump 2. Figure also shows treatment supply and discharge lines, which provide flow through piping system 3.

The retention zone, zone I, is the part of the molecular sieve located between the feedstock input stream 5 and the raffinate effluent stream 7. In this zone, the raw material comes into contact with the molecular sieve, the extract component is retained and the raffinate stream is removed. Since the general flow through zone I takes place from the feedstock stream, which in this zone becomes the raffinate stream leaving the zone, it is considered that the flow in this zone occurs downstream from the feedstock feed point to the raffinate outlet. The liquid rinsing stream (diluent) can be directed to zone I at a point somewhat downstream of the raw material inlet. If a diluent is used, it is added at a rate sufficient to displace the displacement fluid in the simulated motion of at least the non-selective pore volume of the molecular sieve layer in zone I, which promotes fatty acid retention.

17 74488 Immediately downstream of the liquid flow, zone I is purification zone II. The purification zone is formed by a molecular sieve between the extract effluent and the feed stream 5. The basic treatments that take place in Zone II are displacement from the non-selective pore volume of the molecular sieve by the circulating stream of raffinate material that enters this zone II when the molecular sieve is changed to this zone. Purification is accomplished by directing a portion of the extract stream exiting Zone III to Zone II at the upstream boundary of Zone II, i.e., a portion of the extract effluent stream, so as to effect displacement of the raffinate material. The material flow in zone II takes place upstream of the extract effluent to the feedstock feed stream.

Immediately upstream in zone II, with respect to the flow of liquid in this zone, is a displacement zone, i.e. zone III. This displacement zone is formed by the molecular sieve located between the displacement liquid inlet 13 and the extract outlet 11. The purpose of the displacement zone is to allow the displacement liquid that enters this zone to displace the extract component that has remained on the molecular sieve during previous contact with the raw material in zone I during the previous cycle of treatment. The fluid flow in zones III takes place substantially in parallel with zones I and II.

In a few cases, an optional buffer zone, zone IV, can be used. This zone, delimited by the molecular sieve between the raffinate effluent stream 7 and the displacement liquid feed stream 13, is located, if used, immediately upstream of the liquid stream to zone III. Zone IV can be used to retain the displacement fluid used in the displacement step, since a portion of the raffinate stream removed from Zone I can be directed to Zone IV to displace the molecular sieve in that zone from the displacement zone.

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Zone IV contains sufficient molecular sieves so that the raffinate material in the raffinate stream passing from zone I to zone IV can be prevented from entering zone III and thus contaminating the product stream leaving zone III. In cases where the fourth treatment zone is not used, the raffinate stream that would have flowed from zone I to zone IV must be carefully treated with the intention that the flow directly from zone I to zone III can be stopped when there is sufficient raffate from zone I to zone III. that the extract effluent does not become dirty.

In a preferred embodiment of the invention, zone IV is used and the rinse-diluent stream, if used, can be led not only to zone I but also to zone IV at the upstream boundary of zone IV. In this way, the displacement fluid that would otherwise enter zone IV from zone III as part of the simulated moving bed is kept in zone III, assuming that an appropriate amount of rinsing fluid is used. This also reduces the need for displacement fluid. Thus, when the molecular sieve enters zone I, it has a suitable minimum displacement liquid content.

Cyclic conduction of supply and discharge streams through the solid bed of the molecular sieve can be accomplished by using a piping system in which the valves in the piping operate sequentially to provide variation in the supply and discharge flows, allowing fluid flow countercurrent to the solid molecular sieve. Another treatment method that provides a solid molecular sieve countercurrent to the liquid involves the use of a rotary poppet valve in which the supply and discharge flow is connected to this valve, and the lines through which the feed, extract, feed and raffinate take place move in the same direction. through.

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Both said piping arrangement and the poppet valve are already known. Rotary poppet valves that can be utilized in this discussion are disclosed in U.S. Patents 3,040,777 and 3,422,848. Both said patents disclose a rotary connecting valve in which proper conduction of various feed and discharge flows from solid feedstocks can be achieved without difficulty.

In many cases, one functional zone contains a much larger number of molecular sieves than another functional zone. For example, in a few treatments, the buffer zone may contain a smaller amount of molecular sieve compared to the amount of molecular sieve required in the retention and purification zones. It can also be seen that in cases where a displacement fluid that can easily displace the extract material from the molecular sieve is used, a relatively small amount of molecular sieve is required in the displacement zone compared to the number of molecular sieves required in the buffer zone or retention zone or purification zone. Since it is not necessary for the molecular sieve to be located in a single statue, several chambers or sets of statues can be used according to the invention.

It is not necessary that all feed and discharge streams be used simultaneously, and in reality, in many cases, multiple streams may be shut off simultaneously while others provide material feed and discharge. The equipment which can be used to carry out the method according to the invention may also comprise a series of separate layers connected to each other by interconnectors fitted with pipe connections for supply and discharge, to which different supply and discharge flows can be attached and alternated to provide continuous processing. . In a few cases, the connecting lines can be connected to these pipe connections, which during normal processing do not act as a line through which the material passes into and out of the processing.

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It should be noted that at least a portion of the extract effluent can be passed to separation devices in which at least a portion of the displacement liquid, including the diluent, can be separated to obtain an extract product containing the displacement liquid at a lower concentration. Preferably, but not necessarily, for process operation, at least a portion of the raffinate effluent is also passed to separation devices in which at least a portion of the diluent can be separated to provide a diluent stream that can be used for reprocessing and to produce a raffinate product containing less diluent. Separation devices usually consist of a fractionation column, the structure and operation of which are well known in the art.

Reference may be made in this connection to U.S. Patent 2,985,589 and D.B. Broughton's article "Continuous Adsorptive Processing - A New Separation Technique" presented at the 34th Annual Meeting of the Society of Chemical Engineers in Tokyo, Japan on April 2, 1969, both of which present a more simulated layer-based control.

Although both liquid and gas phase treatment can be used in several adsorbent separation treatments, liquid phase treatment is most preferred in this treatment due to the lower temperature requirements and higher yield of extract product that can be achieved in liquid phase treatment compared to steam phase treatment. Separation conditions include a temperature range of about 20-200 ° C, with a range of 20-100 ° C being most preferred, and sufficient pressure to provide a liquid phase, provided, however, that when a diluent is used as the displacement liquid, the temperature is at least 120 ° C. The displacement conditions comprise the same temperatures and pressures used in the separation treatment.

The size of the units that can be used in the process of the invention can range from an experimental scale of 2i 744 8 8 (see, e.g., U.S. Patent 3,706,812) to a factory scale, and flow rates can range from a few ml per hour to several thousand liters per hour.

When the processing feedstock contains rosin acids, as in the case of tall oil, an additional step is required to separate the rosin acids from the feedstock first. This can be accomplished by first contacting the rosin acid-containing feedstock mixture with a molecular sieve formed by silicalite, thereby selectively retaining fatty acids other than rosin acid. The resin acid is then removed from the fatty acids in the first molecular sieve, the mixture of fatty acids can be recovered by displacement from the first molecular sieve, and the fatty acid mixture can then be contacted with a second molecular sieve formed by a sieve that separates fatty acids .

A dynamic test apparatus is used to test different molecular sieves using some specific raw material mixture and displacement fluid to determine the molecular sieve retention capacity and exchange rate. The apparatus comprises a helical molecular sieve chamber having a volume of approximately 70 ml and with inlet and outlet points at opposite ends. The chamber has temperature control devices, and in addition, a pressure control device is used to control the operation of the chamber at a predetermined constant speed. Apparatus for performing quantitative and qualitative analysis, such as reflectometers, polarimeters, and chromatographic devices, can be fitted to the outlet line of the chamber and used to quantitatively or qualitatively determine one or more components of the substance exiting the Molecular sieve chamber. The pulse test performed using this apparatus and the following general method is used to determine the values of various molecular sieve systems. The molecular sieve is filled to equilibrium with a given displacement fluid by passing this displacement fluid through a molecular sieve chamber. At a suitable time, a dose of feedstock containing a known concentration of "residual" and a specified extract component or raffinate component, or both, all diluted with displacement fluid, is injected over several minutes. The displacement fluid flow is stopped and the tracer and extract component or raffinate component (or both) are eluted in a liquid-solid chromatographic treatment. The effluent may be analyzed from the flow or, alternatively, samples of the effluent may be taken periodically and analyzed separately at a later date with analytical equipment to develop peak envelopes or similar component peaks.

Based on the data obtained from the experiments, the performance of the molecular sieve can be evaluated in terms of pore volume, amount of retention of the extract or raffinate component, and the rate of displacement of the extract component from the molecular sieve. The amount of retention of the extract or raffinate component can be determined by the distance between the peak of the tracer component, the center of the sheath, and some other known reference point. It is expressed as a volume in cm of displacement fluid pumped during this period, represented by the distance between the peaks of the jacket. Exchange rate of an extract component with the displacement fluid can generally be characterized by the width of the peak of the shells of half-intensity means. The narrower the top jacket, the higher the displacement rate. The displacement rate can also be characterized by the distance between the peak of the tracer shell and the point of disappearance of the extract component, the latter being just displaced. This distance is also the volume of the displacement fluid pumped during said time.

The following non-limiting examples illustrate the method of the invention but do not limit the scope of the invention.

23 74488

Example I

The pulse test apparatus described above was used to determine the values of this example. The liquid temperature was 60 ° C and the liquid flow rate in the column upwards was 1.2 ml / min. The raw material stream comprised 10% by weight of the fatty acid mixture and 90% by weight of the displacement liquid. The fatty acid mixture consisted of 50-50 linoleic-oleic acid. The column was filled with 23% by weight of "Ludox" -bound silicalite (77% by weight of silicalite) prepared according to a preferred embodiment of the invention, which involved gel formation by removing water (drying) followed by treatment to remove hydroxyl groups, which in this case was heating in air at 1000 ° C for 48 h. The resulting molecular sieve was ground and screened to a particle size of 20-50 (mesh). The displacement liquid used consisted of 80% by volume of methyl ethyl ketone and 20% by volume of propionic acid.

The results of this example are shown in the accompanying Figure 2. As can be seen from this drawing, the separation of oleic acid from linoleic acid is clear and unambiguous, but the desorption event is somewhat slow, as evidenced by the large average retention volume of displacement liquid required for displacement.

The curves also show that there is no above-mentioned reactivity between the adsorption and raw material components which has previously been observed when using silicalite with an organic binder, or a silicalite with a silica binder which has not been heat treated according to the present invention.

Example II

The experimental equipment described above was also used to determine the values of this example. The temperature of the liquid was 80 ° C and the flow was downwards in the column at a rate of 1.2 ml / min. The raw material mixture comprised 10% by weight of tall oil and 90% by weight of 24 7 4 4 8 8 displacement liquid. The column was filled with 23% by weight of bound "Ludox" silicalite (77% by weight of silicalite) in the same manner as in Example I. The displacement liquid used was 100% acetone.

The results of this example are shown in the accompanying Figure 3. It can be seen from this figure that the separation of rosin acid, oleic acid and linoleic acid is good, but the desorption rate is still quite low.

Example III

The experiment of Example II was repeated except that, in accordance with the present invention, in addition to using a displacement fluid having a polarity index greater than 3.5, the temperature of the fluid in the column was 120 ° C.

The results of this example are shown in Figure 4. Figure 4 shows a significant improvement (increase) in the desorption rate, i. the transverse retention volume is significantly reduced. Increased desorption kinetics are, of course, desirable in a factory scale embodiment of the invention, especially in an embodiment using a simulated moving bed because it has a direct effect (reducing effect) on the amount of displacement fluid required and thus saves energy because less displacement fluid has to be distilled off.

Claims (13)

25 7 4 4 8 8 A process for separating oleic acid from ininoic acid from a raw material mixture containing these acids, characterized in that the process comprises contacting the raw material mixture under separation conditions with a molecular sieve containing silicalite in a silicon oxide matrix, wherein the precursor of this molecular sieve contains s ΐ1i dispersed in colloidal, amorphous silica, the precursor being gelled and then treated to provide substantially complete removal of hydroxyl groups from the molecular sieve, thereby selectively retaining oleic acid, removing the linoleic acid from the molecular sieve, and removing the oleic acid from the molecular sieve. A method according to claim 1, characterized in that the displacement liquid is formed by a diluent which is soluble in said raw material mixture and has a polarity index of at least 3.5. Process according to Claim 2, characterized in that the displacement liquid is formed by a solution of an organic acid and a diluent, wherein the organic acid is formed by a compound having 2 to 5 carbon atoms in the molecule and the diluent is selected from the group consisting of acetone, methyl ethyl ketone and diethyl ketone. A method according to claim 3, characterized in that the separation and displacement conditions include a temperature range of about 20 to 100 ° C and a pressure sufficient to maintain the liquid phase. A process according to claim 1, characterized in that the diluent is selected from the group consisting of acetone, methyl ethyl ketone and diethyl ketone, and that the separation and displacement conditions 74488 26 include a temperature of about 120-150 ° C and a pressure sufficient to maintain the liquid phase. Process according to Claim 1, characterized in that the displacement liquid is formed by an organic acid and that the treatment is intermittent, and that the molecular sieve is rinsed with a diluent in suitable rinsing proportions before the raw material mixture comes into contact with the molecular sieve, and that the separation, rinsing and displacement conditions include a temperature range of about 20-200 C and a pressure sufficient to maintain the liquid phase. A method according to claim 1, characterized in that said raw material mixture contains resin acid, and that this method comprises first contacting said raw material mixture with a first molecular sieve containing siiclite, thereby selectively retaining fatty acids other than resin acids, resin acids removing from the first molecular sieve containing fatty acids, defecting the fatty acid mixture by displacing it from said first molecular sieve, and then contacting the fatty acid mixture with a second molecular sieve formed by a molecular sieve that causes the fatty acids to separate from each other. A process for separating oleic acid from linoleic acid from a raw material mixture containing these acids, characterized in that the process uses a molecular sieve containing silica in a silicon oxide matrix, wherein the precursor of this molecular sieve contains silicalite powder dispersed in colloidal, amorphous silicon gelled and then treated to provide substantially complete removal of hydroxyl groups from the molecular sieve, and the method comprises the steps of: 74488 27 (a) maintaining a net flow of fluid through the molecular sieve column in one direction, the column containing at least three zones of different treatment operations; in series with the end zones of the statue and connected so as to provide a continuous connection of the zones; (b) maintaining a retention zone in the column, the zone being formed by a molecular sieve located between the feed stream of the upstream boundary of the zone and the raffinate effluent of the downstream zone; (c) maintaining the purification zone immediately upstream of the retention zone, the purification zone being formed by a molecular sieve located at the upstream flow point of the extract at the upstream boundary of the purification zone and the feed stream at the downstream boundary of the purification zone; ::: (d) displacement of the zone immediately upstream of the treatment zone, wherein the displacement zone is bounded by a molecular sieve located at the upstream boundary of the zone at the boundary between the feed stream and the downstream extraction of the zone; (e) directing the feedstock stream to the retention zone under separation conditions to provide for selective retention of oleic acid by a molecular sieve in the retention zone and removal of the raffinate effluent from the retention zone; (f) aside from the management of liquefied sludge in the ascending zone. freeze in a ratio to cause displacement of oleic acid in the adsorbent zone; (g) an extract stream comprising removing oleic acid and displacement liquid from the displaced zone; and (h) periodically conducting the feed stream, the raffinate effluent, the displacement liquid inlet stream, and the extract effluent stream and the raffinate 28 744 8 8 effluent stream downstream of the molecular sieve column with respect to the liquid flow in the retention zone. A method according to claim 8, characterized in that the diluent feed stream is directed to the retention zone downstream of the raw material feed stream to cause the molecular sieve to be flushed in the retention zone, wherein this diluent feed stream is passed with other treatment streams as a lie (h). A method according to claim 8, characterized in that it comprises the step of maintaining a buffer zone immediately upstream of said displacement zone, said buffer zone being formed by a molecular sieve located at the downstream boundary of the displacement fluid feed stream and the buffer flow stream. between the raffinate effluent at the boundary point. A method according to claim 8, characterized in that the raw material mixture contains rosin acid and that the method comprises first contacting the raw material mixture with a first molecular sieve formed by silicic acid, wherein the fatty acids but not the rosin acids are retained. selectively, removing the resin from the molecular sieve containing fatty acids, artfully removing the fatty acid mixture from the first molecular sieve, and using this fatty acid mixture as a raw material in step (e). 12. Molecular sieve for separating oleic acid from 11-nitric acid, * * characterized in that it contains si-calcite in a silica matrix, the precursor of this molecular sieve containing si-cate powder dispersed in colloidal, amorphous silica, wherein this precursor is gelled and treated to provide substantially complete removal of hydroxyl groups from the molecular sieve. Molecular sieve according to Claim 12, characterized in that the precursor comprises an aqueous colloidal dispersion of amorphous silica particles and silicalite powder and that gelation is effected by removing water from this dispersion.