DE102005062955A1 - Natural process for bleaching oils - Google Patents

Abstract

The invention relates to a process for refining fats and / or oils, DOLLAR A being provided - a crude oil which is obtained from a vegetable or animal material; DOLLAR A - the crude oil is bleached by treating it with a bleaching earth product containing a raw clay which DOLLAR A È has a specific surface area of more than 200 m · 2 · / g; DOLLAR A È has an ion exchange capacity of more than 40 meq / 100 g and DOLLAR A È has a total pore volume of more than 0.4 ml / g, at least 40% of the total pore volume being provided by pores which have a pore diameter of at least 14 nm, and at most 25% of the pore volume is provided by pores that are less than 7.5 nm in diameter and DOLLAR A - the bleached oil is separated from the bleaching earth product.

Description

The The invention relates to a process for the refining of fats and / or oils.

at industrial production of oils and fats become bleaching earths to remove turbidities, discoloration or also used for the removal of oxidation accelerators. By adsorptive cleaning can Taste, color and storage stability of oils and fats significantly improved become. For purification, various classes of bleaching earths are used used. A first group is the class of highly active, mostly on montmorillonite based bleaching earths (HPBE = high performance whitening earth). This group includes in particular acid-activated Montmorillonite, wherein the acid activation in an elaborate Process by dealuminating the crude clays with concentrated acids high temperatures becomes. In this process, a bleaching earth product with very high specific Surface and great Obtained pore volume. Already the use of small amounts of this highly active bleaching earth leads to noticeable cleaning of the crude oils. Low amounts used in the bleaching process are therefore desirable, because the used bleaching earth binds to a residual amount of oil, whereby the yield is reduced, and secondly the used Bleaching earth, according to current regulations, must be disposed of.

adversely At these highly active bleaching earths is the fact that through the Dealuminate with acid while the production big Amounts of acidic, high-salinity wastewater incurred only in complex processes can be recycled or disposed of. The high cost of disposal the waste as well as the elaborate Justify production processes the comparatively high prices of such highly active bleaching earths.

A Another group is the class of naturally active clays (NABE = naturally active whitening earth). These naturally occurring bleaching earths have been around for hundreds of years for the purification of fats and oils used. These nature-active systems (also Fuller's Earth or Fuller earths called) very inexpensive to disposal be put. However, they have only a low bleaching power, so they for the cleaning of hard-to-bleach oils and fats usually not are suitable. Furthermore, must in comparison to highly active bleaching earths much larger quantities of the adsorbent used to achieve the desired bleaching result. Thereby have to but higher Loss of oil or fat are accepted, since the bleaching earths are not can be separated in pure form and certain amounts of oil or fat remain in the bleaching earth.

A compromise between low production costs and acceptable activity is represented by the third bleaching earth class, the so-called surface-activated bleaching systems (SMBE = surface-modified bleaching earths). Here, a naturally active raw clay with small amounts of acid is applied and thus achieved an "in situ activation". Attapulgite and hormone-containing raw clays have proven particularly suitable for this process. These have a very high specific surface area of natural raw materials of about 100 to 180 m ² / g and a pore volume of about 0.2 to 0.35 ml / g. However, since salts formed in the acid activation or unreacted portions of the acids are not washed out, they remain on the product and are at least partially deposited in the pores. As a result, these acid-activated bleaching earths generally do not achieve the same efficiency as achieved by highly active bleaching earths (HPBE) produced by dealuminating with acid. However, the simple manufacturing process allows a comparatively low-cost production, with no acid effluents being a particular advantage.

From US-A-5,008,226 a method for the production of acid-activated bleaching earth using a naturally occurring acid Attapulgit clay according to the above-described acid activation is known. This clay has a pore volume in the range of 0.25 to 0.50 ml / g and a specific surface area in the range of 100 to 150 m ² / g. Particular preference is given to using a naturally occurring mixture of attapulgite and bentonite. The main components of this mineral consist of 71 to 75 wt .-% SiO ₂ and from 11 to 16 wt .-% Al ₂ O ₃ . The attapulgite / bentonite mineral is acid at a temperature of about 25 to 100 ° C, corresponding to an acid amount of 1 to 10 wt .-%, applied. The acid-activated intermediate is not washed but used directly as bleaching earth after drying and milling.

In US-A-3,029,783 a method of treating an attapulgite clay with acid is described. The attapulgite contains about 15 wt .-% Al ₂ O ₃ . The acid activated clay is suitable for use as cat litter.

US-A-5,869,415 describes a method for activating layered silicates having an ion exchange capacity of at least 25 meq / 100g by activation with 1 to 10% by weight of acid followed by calcination at temperatures of 200 ° C to 400 ° C. The layered silicates have specific surface areas in the range of 132 to 167 m ² / g and a pore volume in the range of 0.27 to 0.35 ml / g and an ion exchange capacity of 38 to 68 meq / 100g.

In WO 99/02256 discloses a process for producing a bleaching earth with an elevated acidity described. Activation takes place in an environmentally friendly, because not watery Process instead. Preference is given to 2.5 to 5 wt .-% acid in aqueous solution abandoned on pre-dried and ground raw clay. As examples for suitable acids be hydrochloric and phosphoric acid as well as citric acid described on a raw clay from the Palygorskit smectite class be applied.

In the EP 0 398 636 A1 It is described that weakly acid naturally occurring Palygorskit clays, as well as mixtures of Palygorskit clays and bentonite clays, which were not calcined in each case, can be so strongly activated even with small amounts of acid that they can achieve a high bleaching effect. The acid can be sprayed onto the clay, whereby it is not necessary to wash the clay after activation. The activated materials can be used directly for bleaching oils. The raw clays used as starting material typically have a specific surface area in the range of 100 to 150 m ² / g, a pore volume in the range of 0.20 to 0.31 ml / g, and an SiO ₂ content of 71 to 75 wt. %, an Al ₂ O ₃ content of 11 to 16 wt .-%, and a Fe ₂ O ₃ content of 3.8 to 6.7 wt .-% to. When minerals are used which comprise mixtures of palygorskite clays and bentonite clays, these have a content of attapulgite in the range from about 10 to 90% by weight, preferably from 20 to 60% by weight. If palygorskite clays are used, they have a content of attapulgite of at least 90% by weight. The proportion of attapulgite can be determined by X-ray diffractometry, since these minerals have a high crystallinity. By activation with very high acid amounts of 60% by weight, specific surface areas in the range of about 220 m ² / g and pore volumes in the range of about 0.38 ml / g are achieved.

In addition to extraction of a raw clay with strong acid, attempts have also been made to synthetically produce "tailor-made" materials. Thus WO 2004/105936 describes an adsorbent which according to a preferred embodiment can be obtained by first extracting, as in the production of highly active bleaching earths, a crude clay with a strong mineral acid under boiling heat. To the resulting acidic suspension is added a water glass solution, the amount of water glass being chosen so that the resulting mixture has a pH of more than 4. The mixture can then be heated first, to be then adjusted by the addition of acid to a pH of less than 4. The solid is separated from the suspension and then washed, dried and optionally ground. In this bleaching earth product, therefore, a layer of a silicate-rich precipitate is applied to a clay extracted with acid, which is composed of water glass and polyvalent ions which had previously been extracted from the clay. Figuratively, therefore, a relatively wide-meshed network of silicon dioxide is produced, in which the particles of the extracted clay material are embedded. The particles are relatively large, so that the image of a clay particle can be used, which is covered with a layer of silicon dioxide, which comprises relatively large pores. The adsorbent is particularly suitable for bleaching oils. It is not necessary to achieve a high activity to calcine the adsorbent. The adsorbent described in the examples has a cation exchange capability of 41.2 meq / 100 g, a specific surface area of 370 m ² / g and a pore volume of 0.685 ml / g. The proportion of SiO ₂ based on the weight of the adsorbent is 79.5%, the Fe ₂ O ₃ content 2.4% and the Al ₂ O ₃ content is 6.1%.

A similar model as in WO 2004/105936 is in the DE 103 56 894 A1 tracked. Here, a natural clay material is selected, which has a high proportion of silicon dioxide, and a high pore volume and a high proportion of large pores. Here, too, the model is assumed that fine clay particles are embedded in a large-pored matrix of SiO ₂ , which are ultimately responsible for the bleaching effect of the clay material. The clay material described therein has a specific surface area of more than 200 m ² / g, a pore volume of more than 200 m ² / g and an ion exchange capacity of more than 40 meq / 100 g. The SiO ₂ content is preferably more than 65% by weight, the material used in the examples having an SiO ₂ content of 70.6% by weight. Due to the comparatively wide-meshed gel-like network of SiO ₂ , the oil to be bleached quickly diffused to the finely divided clay particles ren. Due to the large number and the fine distribution of the embedded clay particles is then a rapid and intense bleaching of the oil. The aluminum content of the clay material is relatively low, as in the materials obtained by acid extraction. Preferably, the raw clay has an Al ₂ O ₃ content of less than 11 Wt .-% on. The material used in the examples has an Al ₂ O ₃ content of 9.8. However, since the clay material has been extracted with strong acid, the clay material described in WO 2004/105936 no longer has the capability of ion exchange.

In the production of acid-activated bleaching earths described above, phyllosilicates, in particular smectites and palygorskites, or mixtures of these silicates are therefore usually used. The raw clays used as starting materials have specific surface areas in the range of 100 to 180 m ² / g, a pore volume in the range of 0.25 to 0.50 ml / g and an ion exchange capacity in the range of 38 to 68 meq / 100g. These layer silicates have an Al ₂ O ₃ content of> 11 wt .-%. By extraction with acid, portions of the aluminum can be dissolved out, so that these highly active bleaching earths have a high SiO ₂ content and a low Al ₂ O ₃ content.

As already stated above, have surface-activated Bleaching earth (SMBE) has the advantage of cost-effective production. you reach however, not the bleaching effect as seen with highly active bleaching earths (HPBE) can be achieved. It is therefore in comparison to the highly active Bleaching earth larger quantities surface-activated Bleaching earth necessary to a desired To achieve bleaching result. This in turn causes that in the Bleaching by adsorption of oils and fats in the bleaching earth higher oil losses have to be tolerated and on the other hand, larger quantities must be recycled or disposed of on used bleaching earth.

Of the The invention is therefore based on the object of a process for refining of oils and / or fats available to provide, which avoids the disadvantages of the prior art and which in particular cost carried out can be, with a strong lightening in the bleaching of oils and fats already be achieved with small amounts of added bleaching earth should.

These The object is achieved by a method having the features of the patent claim 1 solved. Advantageous developments of the method are the subject of dependent Dependent claims.

It has surprisingly been found that by selecting the clays, a high whitening effect on the bleaching of oils and fats can be achieved without necessarily requiring prior activation of the clays. Through a targeted selection of natural clays, it is possible to provide bleaching earth products which have a strong bleaching effect even without prior activation. In order to obtain a strong bleaching effect, the selected clays must have a specific surface area (BET area) of more than 200 m ² / g. Furthermore, the clays must already have a relatively high ion exchange capacity of more than 40 meq / 100 g. It is believed that the high ion exchange capacity promotes binding of those contaminants that have charged groups. Furthermore, the clay must have a pore volume of more than 0.4 ml / g, preferably more than 0.5 ml / g. The SiO ₂ content of the clay material is chosen to be relatively low. The clay material has a SiO ₂ content of less than 65 wt .-%, which is relatively low for a natural bleaching earth. For the Al ₂ O ₃ content is relatively high. The Al ₂ O ₃ content is more than 10 wt .-% and is therefore relatively high. The percentages refer in each case to the dry clay material (atro).

The Pore volume is compared to the previously used surface active Bleaching earths relatively high. Surprised has been found that even with a high proportion of smaller to medium pores a good bleaching effect with relatively short bleaching times can be achieved. At least 20% of the pore volume needs pores be provided having a pore diameter of at most 7.5 nm and at least 40% of the pore volume must of Pores are provided that have a diameter of less than 14 nm.

The high bleaching effect came as a surprise since the clay material used has a relatively low SiO ₂ content and a relatively high proportion of Al ₂ O ₃ . Heretofore, it has been thought that a high SiO ₂ content is required for natural materials having a high universal bleaching effect, the total pore volume being primarily formed by large pores which allow rapid diffusion of the oil to be bleached into the clay particles. The clay material used in the process according to the invention has a very high proportion of small to medium pores. Nevertheless, a significant bleaching effect is achieved universally for oils and fats. The structure of the clay material is not yet fully understood. However, the inventors believe that especially the microporous structure described causes effective, specific absorption and separation of the relevant dyes such as chlorophylls and carotenoids from the oil. Likewise, the combination of ion exchange capacity, which is fully maintained unlike highly activated adsorbents, and the high proportion of micropores in the total pore volume should invite the elimination of charge improve impurities (eg Fe ³⁺ ). The advantage of the method according to the invention is primarily to be seen in the fact that, due to the pore structure of the bleaching earth product used, the impurities and only to a limited extent the oil to be cleaned are absorbed, which reduces the oil loss during the bleaching process.

With in the method according to the invention used bleaching earth product can significantly reduce the Lovibond color number and the content of chlorophyll A and simultaneously achieved a significant reduction in the content of phosphorus and iron become. The inventive method therefore allows a quick and easy refining of oils and fats. As another Advantage stands for The refining used clay in itself from natural Sources available, making this cost-effective can be provided. After the degradation, the clay may be dried and ground and then stands directly for one Use For the bleaching of oils and fats available. The provision of the bleaching earth product is therefore technically relative easy to perform, which also kept the costs incurred comparatively low can be.

Usually will in the refining of oils the crude oils first degummed to remove mucilage from the oil. This is the oil treated with water at temperatures ranging from 70 to 80 ° C, wherein it for is stirred for about 10 to 20 minutes at atmospheric pressure. After disconnecting the mucilage, for example by means of a centrifuge follows an acid degumming, being the pre-degummed oil with acid, in particular phosphoric acid or citric acid, treated at temperatures ranging from 70 to 100 ° C at atmospheric pressure becomes. The separation of the mucilage takes place together with the aqueous Phase, for example by centrifugation. In the acid degumming At the end of the treatment time you can still use water, usually in amounts of 1 to 2 wt .-% based on the crude oil, to be added to the Improve the efficiency of degumming.

• – ein Rohöl bereitgestellt wird, welches aus einem pflanzlichen oder tierischen Material gewonnen ist;
• – das Rohöl einer Bleichung unterworfen wird, indem es mit einem Bleicherdeprodukt behandelt wird, welches einen Rohton enthält, der die folgenden Parameter aufweist:
• – eine spezifische Oberfläche von mehr als 200 m²/g;
• – eine Ionenaustauschkapazität von mehr als 40 meq/100g;
• – ein Gesamtporenvolumen von mehr als 0,4 ml/g aufweist, wobei mindestens 20% des Gesamtporenvolumens von Poren bereitgestellt werden, die einen Porendurchmesser von höchstens 7,5 nm aufweisen und mindestens 40% des Porenvolumens von Poren bereitgestellt werden, die einen Durchmesser von weniger als 14 nm aufweisen,
• – einen SiO₂-Gehalt von weniger als 65 Gew.-%;
• – einen Al₂O₃-Gehalt von mehr als 10 Gew.-%; und
• – das gebleichte Öl von dem Bleicherdeprodukt abgetrennt wird.

The refining of fats and / or oils according to the invention is now carried out in such a way that

• - a crude oil is provided which is derived from a vegetable or animal material;
• - the crude oil is bleached by treating it with a bleaching earth product containing a crude clay having the following parameters:
• A specific surface area of more than 200 m ² / g;
• - an ion exchange capacity of more than 40 meq / 100g;
• Having a total pore volume of greater than 0.4 ml / g, providing at least 20% of the total pore volume of pores having a pore diameter of at most 7.5 nm and providing at least 40% of the pore volume of pores having a diameter of have less than 14 nm,
• An SiO ₂ content of less than 65% by weight;
• An Al ₂ O ₃ content of more than 10% by weight; and
• - The bleached oil is separated from the bleaching earth product.

Under a crude oil becomes an oil in the sense of the invention or fat understood with usual Method, e.g. Pressing, from an animal or vegetable Source has been won. It can be used both directly be, as well as have already undergone a pre-cleaning, for example have been degummed.

at the method according to the invention So a raw clay is used, which according to the above defined Criteria selected becomes. Suitable analytical methods for the determination of the specific Surface, pore volume and ion exchange capacity are below Examples given. Such a raw tone can be a sound material be equated that of the raw clay by chemical or physical Modification was obtained, and that the above properties having.

The specific surface area (BET area) and the specific pore volume are determined by means of nitrogen porosimetry according to DIN 66131. The specific surface area is preferably more than 250 m ² / g, particularly preferably more than 300 m ² / g, and is preferably in the range from 320 to 400 m ² / g. The specific pore volume is preferably more than 0.5 ml / g, preferably 0.5 to 1.0 ml / g, particularly preferably 0.5 to 0.7 ml / g. The ion exchange capacity is determined by the method described below in the Examples. It is preferably more than 50 meq / 100 g and is more preferably in the range of 55 to 75 meq / 100g. A slurry of 10% by weight of the raw clay in water preferably has a pH in the range of 5.5 to 8.5, preferably 5.9 to 8.2. The pH is determined using a pH electrode according to DIN ISO 7879.

Of the Raw clay or the clay material has a characteristic distribution the pore radii on. At least 20% of the pore volume is through Pores with a diameter of at most 7.5 nm provided. Preferably be at least 22% of the pore volume, particularly preferably 20 to 30% of the pore volume of pores with a diameter of at most 7.5 nm provided. The pore size or the pore size distribution let yourself by nitrogen porosimetry according to DIN 66131 and evaluation using the BJH method. The total pore volume refers to pores with a diameter of 2 to 130 nm.

Prefers be at least 45%, in particular at least 50% of the total pore volume of the raw clay provided by pores having a pore diameter from at most 14 nm.

Prefers is the proportion of pores with a diameter of more than 25 nm on Total pore volume less than 40%, more preferably less than 35%. The used in the process according to the invention Clay material therefore has a relatively small proportion of large pores on. Surprised is therefore that nevertheless an efficient bleaching within Bleaching times can be achieved, which is practical for a technical implementation is.

In Table 1 shows the preferred proportions of pores for different ones Pore diameter indicated.

Table 1: Preferred proportions of pores with a defined pore diameter on the total pore volume

Especially preference is given to using crude clays whose ion exchange capacity is above 50 meq / 100 g, preferably in the range of 55 to 75 meq / 100 g. As already explained above, differs the bleaching earth product used in the process according to the invention by its high ion exchange capacity of by extraction with Acid produced highly active bleaching earths. Such highly active bleaching earths point because the extraction carried out during their production with strong acids the ability virtually no longer available for ion exchange.

The raw clay contained in the bleaching earth product in the process according to the invention has a high proportion of exchangeable divalent and trivalent cations. The proportion of exchangeable Ca ²⁺ ions is preferably 30 to 70 meq / 100 g, particularly preferably 40 to 65 meq / 100 g. The proportion of exchangeable Mg ²⁺ ions is preferably 20 to 70 meq / 100 g, particularly preferably 30 to 60 meq / 100 g. The proportion of exchangeable Al ³⁺ ions is preferably 0.5 to 2 meq / 100 g, more preferably 1 to 1.5 meq / 100 g.

The raw clay preferably has a specific surface area (BET) of more than 250 m ² / g, particularly preferably more than 300 m ² / g, and is preferably in the range from 320 to 400 m ² / g. The total pore volume (specific pore volume) of the crude clay used is preferably greater than 0.5 ml / g and is preferably in the range of 0.5 to 1.0 ml / 100 g, in particular in the range of 0.5 to 0.8 ml / 100 g.

For the bleaching earth product used in the process according to the invention, particular preference is given to using clay materials or raw clays whose aluminum content, based on the anhydrous raw clay and calculated as Al ₂ O ₃ , is more than 11% by weight, particularly preferably more than 12% by weight and preferably in a range of 11 to 20% by weight.

The bleaching earth products used in the process according to the invention preferably comprise a crude clay which has a low content of SiO ₂ . Preferably, the raw clay has an SiO ₂ content, based on the raw water-free clay, of less than 65% by weight, and is more preferably in a range of from 45 to 63% by weight.

Prefers has the raw clay, based on the raw anhydrous clay, a MgO content of more than 5% by weight, especially preferably more than 7% by weight and is preferably in a range of 5 to 10 wt .-%

Preferably, the raw clay has an Fe ₂ O ₃ content, based on the anhydrous raw clay of less than 8 wt .-%, preferably less than 6 wt .-% and is preferably in the range of 3 to 5 wt .-%.

The in the process according to the invention used bleaching earth product can in addition to the raw clay or the clay material even more usual Components include, for example, to improve the flowability. Preferably, the bleaching earth product is at least 98%, in particular preferably 100% of the raw clay or the clay material.

Especially Preferably, raw clays are used which have only a low crystallinity, ie is not assigned to the class of layer silicates per se. The low crystallinity let yourself for example, by X-ray diffractometry determine. The most preferred raw clays are largely X-ray amorphous, i.e. they show reflexes whose intensity is almost lost in noise. These preferred minerals can therefore not assigned to the class of Attapulgite or Smektite become.

The Raw clays preferably have a large amount of interchangeable divalent and trivalent cations on the surface or on the interstitial sites, which is why in the inventive method used raw clay prefers a very low swelling capacity in water.

Prefers be in the process of the invention therefore Rohtone used their sediment volume smaller in water than 10 ml / 2 g. To determine the sediment volume of the Rohton according to the given the examples initially in water. To After an exposure time of 1 hour, the sediment volume is read off. When stored in water for a longer one Period of for example 3 days is preferably only a very slight increase in sediment volume of less than 20%, in particular preferably less than 10%, especially preferably less than 5% and especially preferred is no increase in sediment volume to observe. This distinguishes the method according to the invention preferably used bleaching earth products of the customary used calcium or sodium bentonites, which in water a show significant increase in sediment volume, i. the strong swelling. The process according to the invention bleaching earth product used Therefore, quite easy from the previously for the bleaching of oils and Fats used SMBE differ as it is essential in water less or at all does not swell.

The in the process according to the invention used clay material preferably has a high content of calcium ions on. The proportion of calcium ions, based on the weight of the dry Raw clay is preferably 3 to 8 wt .-%, particularly preferably 3.5 to 6 wt .-%. These calcium ions can also be proportionately replaced by sodium ions, for example the sound material in usual With a suitable sodium compound, for example soda, is kneaded in a wet state. The clay material transferred to the sodium form can subsequently dried and ground.

Prefers is the sediment volume of crude clay in water is less than 8 ml / 2 g, i.e. Raw clay does not practically swell in the presence of water. By doing so leaves the bleaching earth product is distributed very evenly in the crude oil and after the bleaching process by filtration also very good again.

There the processed oils and fats preferably for enjoyment by humans are preferred Rohtone used, which have a low heavy metal leaching.

Prefers has the in the process according to the invention Raw clay used a leachable by tartaric acid content Heavy metals As, Pb, Cd, Hg less than 25 ppm, preferably less than 15 ppm, more preferably less than 10 ppm. The proportion of tartaric acid leachable arsenic is preferably less than 1.5 ppm, preferably less than 1 ppm. The proportion of leachable by tartaric lead is preferably none than 5 ppm, preferably less than 4 ppm. Of the Share of by tartaric acid leachable cadmium is preferably less than 0.5 ppm, preferably less than 0.3 ppm and the proportion of leachable by tartaric acid Mercury is preferably less than 0.2 ppm, preferably smaller as 0.1 ppm.

One Method for determining the proportion of leachable by tartaric acid Heavy metals are given in the examples.

At the inventive method becomes the crude oil treated with a bleaching earth product, which is a raw clay or contains a sound material, which is characterized by the features indicated above. Under A raw clay in the context of the present invention is a non-natural active or in particular a naturally active clay understood. Especially become natural under raw tones understood occurring natural or non-natural sound clays, which have not undergone any chemical modification, e.g. not yet with strong acids occupied or dealuminated by extraction with strong acids.

Under Clay materials are understood to be raw clays which are obtained by conventional mechanical or chemical processing steps further processed but not in contrast to the highly active bleaching earths have been activated in a (separate) activation step, in particular not with acid were extracted.

The Bleaching effect of the raw clay can according to a preferred embodiment be further increased by the surface clay is surface activated. Under one surface activation In this case, an activation is understood, which by treatment the surface is achieved by physical or chemical means, the Activation, however, does not involve extraction with strong acids as it is done in the manufacture of HPBE. Activation of the raw clay is generally a treatment to understand the raw clay to improve the bleaching effect leads, especially in the bleaching of oils and fats, as shown by the color numbers in oils (Lovibond color numbers) according to AOCS Cc 13b-45 and / or the chlorophyll A determination according to AOCS Cc 13b-55 determined becomes.

A surface activation can in the simplest case by way of a thermal treatment of the raw clay carried out By, for example, this at mild temperatures in the range from about 100 to 120 ° C is dried or at higher Temperatures, preferably in the range of 300 to 350 ° C calcined becomes.

According to one preferred embodiment the surface activation takes place, by giving the raw clay with an acid is brought into contact, especially occupied with an acid becomes. The activation of the raw clay can be carried out in a way who the, as it is known from the manufacture of SMBE. When activated Of the raw clay, the mineral structure of the raw clay remains preferable essentially unchanged. at a treatment with acid can the specific surface and the pore volume of the crude clay as a function of that for acid activation According to experience, the method used decreases by up to about 20%.

In front the activation can optionally dry and ground the raw clays. Most of time the water content of the resulting bleaching earth product is reduced to one Proportion of less than 20% by weight, preferably less than 10% by weight set.

It Rohtone was found to have the properties described above even by activation with small amounts of acid in clay materials can be converted which are surprising as bleaching earth products have good bleaching properties. The bleaching effect of these bleaching earth products achieves the results of highly active bleaching earths or exceeds them these even.

For activation with an aqueous solution an acid or a concentrated acid can the acid chosen arbitrarily become. It can both mineral acids, as well as organic acids or mixtures of the above acids be used. It can be used conventional mineral acids be like hydrochloric acid, phosphoric acid or sulfuric acid, being sulfuric acid is preferred. It can concentrated or diluted acids or acid solutions used become. As organic acids can solutions from e.g. citric acid or oxalic acid be used. Preferred is citric acid.

In principle, any method known to those skilled in the art, including those described in WO 99/02256, may be used for acid activation US 5,008,226 and the US 5,869,415 described methods which are expressly incorporated by reference in the description.

Becomes the activation of the raw clays are performed by a treatment with acid the raw clays are in contact with an inorganic or organic acid brought. For example, the raw clay with a solid acid, for example a solid organic acid, like citric acid, be mixed. Preference is given to the raw clay together with the solid acid ground so that intimate contact between raw clay and acid is achieved becomes. The amount of added acid is preferably less than 20 wt .-%, particularly preferably less chosen as 10 wt .-% and particularly preferably less than 5 wt .-%, based on the weight of the anhydrous raw clay. Preferably, the proportion the added acid at least 1% by weight.

at an embodiment the method according to the invention the activation of the crude clay is carried out in the aqueous phase. To becomes the acid as watery solution brought into contact with the raw clay. It can be done this way be that first the raw clay, which is preferably provided in the form of a powder is slurried in water becomes. Subsequently becomes the acid added in preferably concentrated form. The raw tone, however, can also directly in an aqueous solution the acid slurried be, or the watery solution the acid be abandoned on the raw clay. According to an advantageous embodiment can the watery Acid solution, for example be sprayed onto a preferably cracked or powdered raw clay, wherein the amount of water is preferably chosen as low as possible and e.g. a concentrated acid or acid solution used becomes. The amount of acid may preferably be between 1 and 10% by weight, more preferably between 2 and 6% by weight of a, preferably strong, acid, in particular a mineral acid, like sulfuric acid, based on the anhydrous raw clay (atro) can be selected. If necessary, can excess water be evaporated and the activated raw clay then to the desired Fineness to be ground. After abandonment of the aqueous solution of the acid can only so far necessary until reaching the desired moisture content be dried.

To a preferred embodiment of the invention It is not necessary that the excess acid and the activation be washed out resulting salts. Rather, it is up to task the acid, as usual with the acid activation, no Washing step performed, but the treated raw clay dried and then ground to the desired grain size. When grinding, a typical bleaching earth fineness is usually set.

According to one another embodiment the method according to the invention the raw clay is activated with an iron salt. This can be the raw tone for example, with an aqueous solution the iron salt sprayed become. Suitable iron salts are, for example, the iron salts halides or organic acids such as acetates or citrates. A preferred iron salt is iron sulfate. The amount of raw clay applied iron salt is preferably in the range of 1 to 6 wt .-%, based on raw raw clay, selected.

The Grain size or the mean grain size of the inventive method bleaching earth product used should preferably be chosen that when using the, possibly activated, raw clay or the Bleicherdeprodukts a completeness ended and simple separation clay from the refined product. Preferably the mean grain size of the powdery raw clay in a range of 10 to 63 μm selected. Typically, the fineness is chosen so that on a sieve with a mesh size of 63 microns about 20 to 40% by weight to remain behind the mixture (Sieve residue) and on a screen with a mesh size of 25 microns approximately 50 to 65 wt .-% of the mixture remain. This can be as typical Bleicherdefeinheit be designated.

At the inventive method may under certain conditions on acid degumming as well as a Wet bleaching can be omitted and after addition of the bleaching earth product Begin immediately with the vacuum equalization.

These rationalized refining is particularly suitable for oils containing a phosphorus content, especially phospholipid content, of less than 100 ppm less than 50 ppm. The phosphorus content can be for example, determine by elemental analysis.

Especially the method according to the invention is suitable for the Refining of palm oil.

The The invention will be described by way of example and with reference to an attached Figure explained in more detail. there shows:

1 : A schematic process diagram for the physical refining of oils, especially palm oil.

Crude cooking oil, for example palm oil, is usually refined according to the principle of physical refining by a process as shown schematically in FIG 1 is reproduced. The crude oil, which was obtained for example by pressing appropriate plant seeds in an oil mill, is first subjected to drying and degassing, for example, to remove dissolved oxygen from the oil. The crude oil is fed to a degumming stage, in which the gums, in particular phospholipids, are separated. Degumming may include pre-degumming as well as acid degumming. In the pre-degumming water is added to the crude oil and the mixture is stirred at about 70 to 80 ° C at atmospheric pressure. The aqueous lecithin phase is then separated off. The crude oil after pre-degumming has a phosphorus content in the range of about 100-200 ppm. In the acid degumming, the pre-degummed oil is mixed with an acid and stirred at about 70 to 100 ° C at atmospheric pressure. Suitable acids are, for example, phosphoric acid and citric acid. Exemplary conditions are an acid amount of 0.06 wt% of a 50% phosphoric acid, a treatment temperature of about 95 ° C, and a treatment time of about 15 minutes. At the end of acid degumming, water may still be added with the amount of water chosen at about 0.2% by weight to facilitate the separation of the gums. The aqueous phase is then separated, for example by centrifugation. After acid degumming, the oil has a phosphorus content in the range of about 10 to 20 ppm. Degumming is necessary in combination with subsequent bleaching to reduce the proportion of phospholipids (phosphors) in the oil as well as the metals. If the degumming is dispensed with, the contents of phosphorus and iron are often too high even in the case of sufficiently low Lovibond color numbers red / yellow in the refined oil. After degumming, the oil may be dried and degassed if necessary. For low-phosphorus crude oils, such as palm oil, acid degumming may possibly be dispensed with and bleaching carried out directly.

At the degumming closes a bleaching of the oil at first a wet bleaching and then performed a vacuum equalization becomes. In wet bleaching, the oil becomes water and bleaching earth amounts ranging from about 0.1 to 0.5 wt .-% for water and 0.3 to 2.0% by weight for Bleaching earth selected become. The oil is heated at normal pressure to about 80 to 100 ° C and about 20 minutes touched. Subsequently vacuum (for example, 100 mbar) is applied and the oil for further 30 minutes at about 90 to 120 ° C touched. The oil will follow filtered, for example, over a filter with a paper filter. The filtration is carried out at a temperature of about 80 ° C.

To the bleaching becomes the oil still deodorized. This is overheated Water vapor having an exit temperature of about 240 to 260 ° C, through the oil passed to free fatty acids as well as unpleasant flavors and odors. The Deodorization is carried out in vacuo at a pressure in the range of less than 5 mbar, preferably 1 to 3 mbar.

To Refining has the oil a phosphorus content of less than 3 ppm and an iron content of less than 0.1 ppm.

At the inventive method becomes the refining of crude oil performed in the manner described above, but with a special Bleaching earth product as adsorbent or bleaching agent, in particular used in the bleaching. For oils containing a phosphorus content less than about 80 ppm, preferably less than 50 ppm, can be dispensed with the degumming step and, if necessary after Drying and degassing of crude oil, directly a bleaching of the oil be made.

Examples:

The The invention will be further explained below with reference to examples.

It the following analytical methods were used:

Surface area / pore volume:

The specific surface area is measured on a fully automatic nitrogen porosimeter made by Microme ritics, type ASAP 2010, carried out according to DIN 66131. The pore volume is determined using the BJH method (EP Barrett, LG Joyner, PP Haienda, J. Am. Chem. Soc. 73 (1951) 373). Pore volumes of certain pore size ranges are determined by summing up incremental pore volumes, which are obtained from the evaluation of the adsorption isotherm according to BJH. The total pore volume according to the BJH method refers to pores with a diameter of 2 to 130 nm.

Oil Analysis:

The Color numbers in oils (Lovibond color numbers) are calculated according to AOCS Cc 13b-45 determined. The chlorophyll A determination was carried out according to AOCS Cc 13d-55.

Water content:

Of the Water content of the products at 105 ° C is determined using the method DIN / ISO-787/2.

Silicate:

These Analysis is based on the total digestion of the raw clay or the corresponding Product. After dissolving The solids are the individual components with conventional specific analytical methods, e.g. ICP, analyzed and quantified.

Ion exchange capacity:

To determine the ion exchange capacity (IUF), the raw clay to be investigated is dried at 105 ° C. over a period of two hours. Thereafter, the dried material is reacted with an excess of aqueous 2N NH ₄ Cl solution for one hour under reflux. After a service life of 16 hours at room temperature is filtered, whereupon the filter cake is washed, dried and ground and the NH ₄ -Ge content in raw clay by nitrogen determination (CHN analyzer from. Leco) is determined according to the manufacturer. The proportion and type of exchanged metal ions is determined in the filtrate by ICP spectroscopy.

X-ray:

The radiographs be at a high resolution Phillips powder diffractometer (X'-Pert-MPD (PW 3040)) created with equipped with a Cu anode is.

determination of sediment volume

One graduated 100 ml graduated cylinder is filled with 100 ml of distilled water or an aqueous Solution 1% soda and 2% trisodium polyphosphate filled. 2 g of the to be measured Substance become slow and in portions, each about 0.1 to 0.2 g, with a spatula placed on the surface of the water. To the drop of one added portion becomes the next serving added. After the 2 g of substance added and to the bottom of the measuring cylinder, the cylinder is for one hour allowed to stand at room temperature. Subsequently, at the graduation the measuring cylinder the height sediment volume in ml / 2g.

Determination of volume increase of the sediment volume (swelling capacity)

The sample approach used as described above to determine the sediment volume is sealed with Parafilm ^® and vibration-free for three days at room temperature, allowed to stand. Then the sediment volume is read off the graduation of the measuring cylinder. The increase in sediment volume results from the difference in sediment volume at the beginning of the measurement and after a service life of three days.

determination of the dry sieve residue

About 50 g of the air-dry mineral to be examined are weighed out on a sieve of mesh size 45 μm. The sieve is connected to a vacuum cleaner, which sucks all parts, which are finer than the sieve through the sieve through a suction slot circulating under the sieve bottom. The sieve becomes covered with a plastic lid and turned on the vacuum cleaner. After 5 minutes, the vacuum cleaner is switched off and the amount of remaining on the screen coarser fractions determined by differential weighing.

Loss on ignition:

In an annealed one weighed porcelain crucible with lid is about 1 g of dried sample weighed to the nearest 0.1 mg and kept at 1000 ° C in a muffle furnace for 2 h annealed. Thereafter, the crucible is cooled in a desiccator and weighed.

determination the bulk density

One at the 1000 ml graduation cut glass measuring cylinder is weighed empty and then the bulk material to be measured with the help of a powder funnel filled in one go, the at the top of the measuring cylinder a cone is obtained. The pour cone is stripped off with the aid of a ruler and attached externally to the measuring cylinder Material removed. The stuffed Measuring cylinder is weighed again. The difference of the measured weights corresponds to the bulk density in g / 1000 ml.

determination the mean particle size

The Grain size is at the "Malvern Mastersizer S "through Laser diffraction determined in the particle air flow. Given is the d50 value, i. 50% of all particles <x μm.

example 1

Characterization of the Rohtons A

One for the inventive method suitable crude clay A (Süd-Chemie AG, Moosburg, DE, raw clay bearing Ref. No .: 05407) was in terms of its physicochemical Properties examined. The results achieved here are in Tables 2 and 3.

Table 2 Physical-chemical analysis of raw clay A

Further the raw clay A characterized in Table 2 became the fraction examined at the pore volume, which formed by pores radii becomes. The corresponding data are summarized in Table 3 a-c.

Table 3a Relative proportions of the pores in the pore volume

Table 3b Relative proportions of the pores in the pore volume

Table 3c Relative proportions of the pores in the pore volume

Example 2 (Comparative Examples)

Of the Raw clay A was compared with various commercially available bleaching earths. The properties of the bleaching earths are together with the raw clay A summarized in Table 4.

Example 3

Bleaching of palm oil

For the implementation of Refining trials, two different palm oils were used their properties are summarized in Table 5.

Table 5 Properties of crude palm oils

The raw palm oil were refined in the following ways:

a) Refining palm oil C

For the refining of palm oil C, 0.075% by weight of citric acid (20%) was first added to the dried and degassed crude palm oil, and the mixture was stirred at 70 ° C. for 30 minutes under atmospheric pressure. Subsequently, 0.2% H ₂ O was added and stirred for a further 10 minutes under atmospheric pressure. After degumming, the oil was admixed with in each case 0.8 or 1.0% by weight of the bleaching earths indicated in Table 12. The mixture was first stirred at atmospheric pressure for 20 minutes at 95 ° C, then the pressure was lowered to 30 mbar and the mixture stirred for a further 30 minutes at 110 ° C. After bleaching, the oil was filtered at 80 ° C over a suction filter covered with a filter paper.

The deodorization of the bleached oil was carried out by passing at a pressure of <1 mbar for 120 minutes superheated steam (outlet temperature: 260 ° C) through the oil. The oil was characterized after the individual purification steps. The values are given in Table 6.

b) refining palm oil D

For the refining of palm oil D, the dried and degassed crude palm oil was first admixed with 0.05% by weight of citric acid (30%) and the mixture was stirred at 80 ° C. for 5 minutes under atmospheric pressure. Then, 0.050 wt .-% colloidal silica (Trisyl ^®, Grace Corp., US) were added and the mixture stirred at 80 ° C for another 5 minutes at atmospheric pressure. After degumming, the oil was treated with in each case 0.4 or 0.5% by weight of the bleaching earths given in Table XIII. The mixture was first stirred at atmospheric pressure for 20 minutes at 95 ° C, then the pressure was lowered to 30 mbar and the mixture stirred for a further 30 minutes at 120 ° C. After bleaching, the oil was filtered at 80 ° C over a suction filter covered with a filter paper.

The Deodorization of bleached oil carried out by overheating at a pressure of <1 mbar for 120 minutes Water vapor (exit temperature: 255 ° C) passed through the oil has been. The oil was characterized after each refining step. The values are given in Table 7.

c) refining palm oil D

In in another series, palm oil D was described as in b) above refined, but added no colloidal silica has been. The measured values are summarized in Table 8.

Example 4

Activation of the raw clay A with sulfuric acid and / or iron sulfate

The crude clay A characterized in Example 1 is mixed with water and then activated by adding the amounts of H ₂ SO ₄ or Fe ₂ (SO ₄ ) ₃ indicated in Table 9. For this purpose, in each case 100 g of the raw clay A dried to 11.5 H ₂ O are intimately mixed with the amounts of H ₂ SO ₄ or Fe ₂ (SO ₄ ) ₃ indicated in Table 9 in a beaker. The resulting mixture is dried at 110 ° C and then ground to a typical bleaching earth density. The properties found for the activated raw clays are summarized in Table 9.

Example 5

Bleaching of rapeseed and soybean oil

One degummed and deacidified rape oil or soybean oil is used with 1.2% by weight (rapeseed oil) or 0.4% by weight (soybean oil) the bleaching earths indicated in Tables 10 and 11 at 110 ° C and 105 ° C for 30 minutes bleached under a pressure of 30 mbar. Subsequently, will The bleaching earth is filtered off and the color number of the oil is filtered using the Lovibond method in a 5 ¼ "cuvette. The for Lovibond red and chlorophyll "A" values are shown in Tables 10 and 11.

Table 10 Bleaching of rapeseed oil

Table 11 Bleaching of soybean oil

Claims (17)

A process for refining fats and / or oils, wherein - a crude oil is provided which is derived from a vegetable or animal material; - the crude oil is bleached by treating it with a bleaching earth product containing a crude clay having the following parameters: A specific surface area of more than 200 m ² / g; - an ion exchange capacity of more than 40 meq / 100g; Having a total pore volume greater than 0.4 ml / g, providing at least 20% of the total pore volume of pores having a pore diameter of at most 7.5 nm and providing at least 50% of the pore volume of pores having a diameter of less than 14 nm, an SiO ₂ content of less than 65% by weight; - an Al ₂ O ₃ content of more than 10 wt .-%; and - the bleached oil is separated from the bleaching earth product. The method of claim 1, wherein the total pore volume of raw clay larger than 0.5 ml / g. A method according to claim 1 or 2, wherein the ion exchange capacity of the raw clay greater than 50 meq / 100g is. Method according to one of the preceding claims, wherein the raw clay, based on the anhydrous raw clay, has a MgO content of more than 5 wt .-% has. A process according to any one of the preceding claims, wherein the raw clay has an Fe ₂ O ₃ content, based on the raw water-free clay, of less than 5% by weight. Method according to one of the preceding claims, wherein the sediment volume of crude clay in water is less than 10 ml / 2g. A method according to any one of the preceding claims, wherein the raw clay has a specific surface area of more than 300 m ² / g. The method of claim 7, wherein the proportion of the pores with a diameter of more than 25 nm on the total pore volume smaller than 40%. Method according to one of the preceding claims, wherein the raw clay surface activated is. The method of claim 9, wherein the raw clay for surface activation with an acid is brought into contact. The method of claim 10, wherein the acid is as aqueous solution is brought into contact with the raw clay. A method according to claim 10 or 11, wherein the acid is a mineral acid is. Process according to claim 12, wherein the mineral acid is sulfuric acid or phosphoric acid is. Method according to one of the preceding claims, wherein the raw clay is activated with an iron salt. The method of claim 14, wherein the iron salt is Fe ₂ (SO ₄ ) ₃ . Method according to one of the preceding claims, wherein the crude oil has a phosphorus content, calculated as P, of less than 100 ppm. Method according to one of the preceding claims, wherein the crude oil is not subject to degumming.