WO2007079981A2

WO2007079981A2 - Natural method for bleaching oils

Info

Publication number: WO2007079981A2
Application number: PCT/EP2006/012630
Authority: WO
Inventors: Friedrich Ruf; Genovefa Wendirch; José Antonio ORTIZ NIEMBRO
Original assignee: Süd-Chemie AG
Priority date: 2005-12-29
Filing date: 2006-12-29
Publication date: 2007-07-19
Also published as: DE102005062955A1; WO2007079981A3

Abstract

The invention relates to a method for refining of fats and/or oils by preparation of a crude oil, obtained from plant or animal material, subjecting the crude oil to a bleaching step by treatment with a fuller's earth product containing a raw clay with a specific surface area of more than 200 m2/g, an ion exchange capacity of more than 40 meq/l00g, and a total pore volume of more than 0.4 ml/g, where at least 40% of the total pore volume of the pores available has a pore diameter of at least 14 nm and at most 25 % of the pore volume of the pores available has a pore diameter of less than 7.5 nm and the bleached oil is then separated from the fuller's earth product.

Description

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NATURAL METHOD OF BLEACHING OILS

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

In the industrial production of oils and fats, bleaching earths are used to remove turbidity, discoloration or even to remove oxidation accelerators. Adsorptive cleaning can significantly improve the taste, color and storage stability of oils and fats. For purification, different classes of bleaching earths are used. A first group is the class of highly active, mostly montmorillonite-based bleaching earths (HPBE = high performance bleaching earth). In particular, this group comprises acid-activated montmorillonites wherein the acid activation is carried out in a complex process by dealuminating the crude clays with concentrated acids at high temperatures. In this process, a bleaching earth product with a very high specific surface area and a large pore volume is obtained. Even the use of small amounts of this highly active bleaching earth leads to significant purification of the crude oils. Small amounts in the bleaching process are desirable because the spent bleach _ _

On the one hand earth binds to residual amounts of oil, whereby the yield is reduced, and on the other hand, the used bleaching earth, according to current regulations, must be disposed of.

A disadvantage of these highly active bleaching earths is the fact that dealuminating with acid during production results in large amounts of acidic, high-salinity wastewater, which can only be treated or disposed of in complex processes. The high costs for waste disposal and the complex production process justify the comparatively high prices of such highly active bleaching earths.

Another group is the natural active clay class (NABE = naturally active whitening earth). These naturally occurring bleaching earths have been used for hundreds of years for the purification of fats and oils. These naturally active systems (also called filler's earth or fuller's earth) can be provided very cheaply. However, they have only a low bleaching power, so they are usually not suitable for the cleaning of hard to bleach oils and fats. Furthermore, much larger amounts of the adsorbent must be used in comparison to highly active bleaching earths in order to achieve the desired bleaching result. As a result, however, higher losses of oil or fat must be accepted, since the bleaching earths can not 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 is a natural active raw clay with small amounts of acid 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 * / g. Particular preference is given to using a naturally occurring mixture of attapulgite and benzonite. 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 ⁰ 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 grinding. - -

In US-A-3, 029, 783 a method for the treatment of 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.

The US-A-5 869.415 describes a process for activation of layered silicates having an ion exchange capacity of at least 25 meq / lOOg by activation with 1 to 10 wt .-% acid and subsequent calcination at temperatures of 200 ⁰ C to 400 ⁰ C. Phyllosilicates 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 / 100 g.

WO 99/02256 describes a process for producing a bleaching earth having an increased acid content. The activation takes place here in an environmentally friendly, because non-aqueous process. Preferably, 2.5 to 5% by weight of acid in aqueous solution are applied to predried and ground raw clay. Examples of suitable acids are hydrochloric and phosphoric acid and citric acid, which are applied to a crude clay of the palygorskite smectite class.

EP 0 398 636 A1 describes that weakly acidic naturally occurring palygorskite clays, as well as mixtures of polygorskite 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 added to a clay extracted with acid - -

applied, which is made up of water glass and polyvalent ions that were previously 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. 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%. 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.

A similar model as in WO 2004/105936 is pursued in DE 103 56 894 A1. Here, a natural clay material is selected, which has a high proportion of silicon dioxide, as well as 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. Through the _ _

similarly wide-meshed gel-like network of SiO ₂ , the oil to be bleached quickly diffuse to the finely divided clay particles. Due to the large number and the fine distribution of the embedded clay particles then takes place 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. The raw clay preferably has an Al ₂ O ₃ content of less than 11% by weight. The material used in the examples has an Al ₂ O ₃ content of 9.8.

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 / cj _» 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 / 100 g. 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 explained above, surface-activated bleaching earths (SMBE) have the advantage of cost-effective production. However, they do not achieve the bleaching effect achieved by highly active bleaching earths (HPBE). Therefore, in comparison with the highly active bleaching earths, larger amounts of surface-activated bleaching earth are necessary in order to achieve a desired bleaching result. This in turn has the effect that in the bleaching by adsorption of oils and fats in the bleaching earth higher oil losses must be accepted, and on the other hand, larger quantities of used bleaching earth must be treated or disposed of. - σ -

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

This object is achieved by a method having the features of patent claim 1. Advantageous developments of the method are the subject of the 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 which 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 _ _

so relatively high. The percentages refer in each case to the dry clay material (atro).

The pore volume is relatively high in comparison to the surface active bleaching earths used hitherto. Surprisingly, it has been found that even with a high proportion of small to medium pores, a good bleaching effect can be achieved with relatively short bleaching times. At least 20% of the pore volume must be provided by pores having a pore diameter of at most 7.5 nm and at least 40% of the pore volume must be provided by pores having 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. Similarly, the combination of ion exchange capacity, which is fully maintained, unlike highly activated adsorbents, and the high percentage of micropores in the total pore volume should eliminate elimination of charged impurities (eg, Fe ³⁺ ). - -

improve. 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 the bleaching earth product used in the process according to the invention, a significant reduction in the Lovibond color number and the content of chlorophyll A and at the same time a significant reduction in the content of phosphorus and iron can be achieved. The method according to the invention therefore enables rapid and simple refining of oils and fats. As a further advantage, the clay used for the refining is already available from natural sources, so that it can be provided at low cost. After degradation, the clay may optionally be dried and ground and then immediately available for use in the bleaching of oils and fats. The provision of bleaching earth product is therefore technically relatively easy to carry out, whereby the costs incurred can be kept relatively low.

Usually, in the refining of oils, the crude oils are first degummed to remove mucilage from the oil. For this purpose, the oil is treated at temperatures in the range of 70 to 80 ⁰ C with water, being stirred for about 10 to 20 minutes at atmospheric pressure. After separating the gums, for example by means of a centrifuge, followed by acid degumming, wherein the vorentschleimte oil with acid, in particular phosphoric acid or citric acid, is treated at temperatures ranging from 70 to 100 ⁰ C at atmospheric pressure. The separation of the mucilage occurs together with the aqueous _ _

Phase, for example by centrifugation. In the case of acid degumming, water, usually in amounts of from 1 to 2% by weight, based on the crude oil, can still be added at the end of the treatment time in order to improve the efficiency of degumming.

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

providing a crude oil derived from a vegetable or animal material;

bleaching the crude oil 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; has 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 40% 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% by weight; and

the bleached oil is separated from the bleaching earth product. _

For the purposes of the invention, a crude oil is understood to mean an oil or fat which is obtained by conventional processes, e.g. Presses obtained from an animal or vegetable source. It can be used both directly and have already undergone a pre-cleaning, for example, have been degummed.

In the method according to the invention thus a raw clay is used, which is selected according to the criteria defined above. Suitable analytical methods for determining the specific surface area, the pore volume and the ion exchange capacity are given below in the examples. Such a raw clay can be equated with a clay material obtained from the raw clay by chemical or physical modification and having the above-mentioned properties.

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 / 100 g. 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. _ _

The raw clay or the clay material has a characteristic distribution of the pore radii. At least 20% of the pore volume is provided by pores with a diameter of at most 7.5 nm. Preferably, at least 22% of the pore volume, more preferably 20 to 30% of the pore volume of pores having a diameter of at most 7.5 nm are provided. The pore size or the pore size distribution can be determined by nitrogen porosimetry according to DIN 66131 and evaluation by means of the BJH method. The total pore volume refers to pores with a diameter of 2 to 130 nm.

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

The proportion of pores with a diameter of more than 25 nm in the total pore volume is preferably less than 40%, particularly preferably less than 35%. The clay material used in the method according to the invention thus has a relatively small proportion of large pores. It is therefore surprising that nevertheless an efficient bleaching can be achieved within bleaching times, which is practical for a technical implementation.

Table 1 shows the preferred proportions of pores for different pore diameters. - -

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

Particular preference is given to using raw clays whose ion exchange capacity is above 50 meq / 100 g, preferably in the range from 55 to 75 meq / 100 g. As already explained above, the bleaching earth product used in the process according to the invention differs, due to its high ion exchange capacity, from highly active bleaching earths prepared by extraction with acid. Such highly active bleaching earths have virtually no longer the ability to ion exchange due to the extraction performed with their production with strong acids.

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 interchangeable _ _

Mg ²⁺ ions are preferably 20 to 70 meq / 100 g, more 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 raw 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.

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

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 bleaching earth product used in the process according to the invention may comprise, in addition to the raw clay or the clay material, further customary constituents, for example for improving the flowability. Preferably, the bleaching earth product consists of at least 98%, particularly preferably 100%, of the raw clay or the clay material.

Particular preference is given to using raw clays which only have a low crystallinity, that is to say they are not assigned to the class of layered silicates per se. The low crystallinity can be determined for example by X-ray diffractometry. The particularly preferred raw clays are substantially or completely X-ray amorphous, i. they show reflexes whose intensity almost or completely disappears in the noise. These preferred minerals can therefore not be assigned to the class of Attaculgite or Smektite.

The raw clays preferably have a large amount of exchangeable divalent and trivalent cations on the surface or on the interstitial sites, for which reason the raw clay used in the process according to the invention preferably has a very low swelling capacity in water.

In the process according to the invention, preference is therefore given to using crude clays whose sediment volume in water is less than 10 ml / 2 g. To determine the sediment volume, the crude clay is first added to water according to the instructions given in the examples. After an exposure time of 1 hour, the sedi- _ _

read volume. When stored in water for a prolonged period of, for example, 3 days, preferably only a very small increase in the sediment volume of less than 20%, more preferably less than 10%, more preferably less than 5% is observed, and particularly preferred is no increase in To observe sediment volume. This distinguishes the bleaching earth products preferably used in the process of the invention from the commonly used calcium or sodium bentonites, which exhibit a significant increase in sediment volume in water, i. the strong swelling. The bleaching earth product used in the process according to the invention can therefore be quite easily distinguished from the SMBE hitherto used for the bleaching of oils and fats, since it swells considerably less in water or does not swell at all.

The clay material used in the process according to the invention preferably has a high content of calcium ions. The proportion of calcium ions, based on the weight of the dry raw clay and calculated as CaO, is preferably 3 to 8% by weight, particularly preferably 3.5 to 6% by weight. These calcium ions can also be proportionally replaced by sodium ions, for example, by kneading the clay material in a conventional manner with a suitable sodium compound, for example soda, in a moist state. The clay material transferred to the sodium form can then be dried and ground.

The sediment volume of the crude clay in water is preferably less than 8 ml / 2 g, ie the crude clay does not practically swell in the presence of water. As a result, the bleaching earth product can be distributed very evenly in the crude oil and, after the bleaching process by filtration, also very well separated again. , _

- Xo -

Since the processed oils and fats are preferably intended for human consumption, preference is given to using raw clays which have low heavy metal leaching.

The crude clay used in the process according to the invention preferably has a tartaric acid-leachable content of heavy metals As, Pb, Cd, Hg of less than 25 ppm, preferably less than 15 ppm, particularly preferably less than 10 ppm. The proportion of arsenic 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. The proportion of cadmium leachable by tartaric acid is preferably less than 0.5 ppm, preferably less than 0.3 ppm, and the proportion of mercury leachable by tartaric acid is preferably less than 0.2 ppm, preferably less than 0.1 ppm.

A method for determining the proportion of heavy metals leachable by tartaric acid is given in the examples.

In the method according to the invention, the crude oil is treated with a bleaching earth product which contains a raw clay or a clay material which is characterized by the features indicated above. In the context of the present invention, a raw clay is understood to mean a non-naturally active or in particular a naturally active clay. In particular, naturally occurring raw or non-naturally active clays are understood to mean naturally occurring or non-naturally active clays which have not yet been subjected to any chemical modification, for example, have not yet been treated with strong acids or dealuminated by extraction with strong acids. _ _lg _

Clay materials are to be understood as meaning raw clays which have been processed further by conventional mechanical or chemical work-up steps but, unlike the highly active bleaching earths, have not been activated in a (separate) activation step, in particular have not been extracted with acid. :

The bleaching action of the raw clay can, according to a preferred embodiment, be further increased by surface-activating the raw clay. By "surface activation" is meant an activation achieved by treatment of the surface by physical or chemical means, but the activation should not involve extraction with strong acids, as is done in the production of HPBE. Activation of the raw clay is generally to be understood as meaning a treatment of the raw clay which leads to an improvement in the bleaching action, in particular in the bleaching of oils and fats, as measured 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 is determined.

A surface activation can be of the raw clay can be performed in the simplest case by means of a thermal treatment by being dried to 120 ⁰ C, for example at mild temperatures in the range of about 100 or even at higher temperatures, preferably in the range of 300 to 350 ⁰ C calcium is defined.

According to a preferred embodiment, the surface activation is carried out by the raw clay is brought into contact with an acid, in particular is coated with an acid. The activation of the raw clay can be carried out in a way - -

as known from the manufacture of SMBE. When activating the raw clay, the mineral structure of the raw clay preferably remains substantially unchanged. When treated with acid, the specific surface area and pore volume of the raw clay may have been found to decrease by up to about 20% depending on the method used for acid activation.

If necessary, the raw clays can be dried and ground before activation. Most of the water content of the resulting bleaching earth product is adjusted to a proportion of less than 20 wt .-%, preferably less than 10 wt .-%.

It has been found that crude clays with the properties described above can even be converted by activation with small amounts of acid into clay materials which have surprisingly good bleaching properties as bleaching earth products. The bleaching effect of these bleaching earth products reaches or even surpasses the results of highly active bleaching earths.

For activation with an aqueous solution of an acid or a concentrated acid, the acid itself can be chosen as desired. Both mineral acids and organic acids or mixtures of the above acids can be used. Usual mineral acids may be used, such as hydrochloric acid, phosphoric acid or sulfuric acid, with sulfuric acid being preferred. Concentrated or diluted acids or acid solutions can be used. As organic acids, solutions of e.g. Citric acid or oxalic acid can be used. Preferred is citric acid.

In principle, any method known to those skilled in the art may be used for activation with acid, including those described in WO 99/02256, US 5,008,226 and US 5,869,415 - -

Methods which are expressly incorporated herein by reference.

When the activation of the raw clays is carried out by a treatment with acid, the raw clays are brought into contact with an inorganic or organic acid. For example, the raw clay may be mixed with a solid acid such as a solid organic acid such as citric acid. Preferably, the raw clay is ground together with the solid acid, so that an intimate contact between raw clay and acid is achieved. The amount of acid added is preferably less than 20% by weight, more preferably less than 10% by weight, and most preferably less than 5% by weight, based on the weight of the anhydrous raw clay. Preferably, the proportion of added acid is at least 1 wt .-%.

In one embodiment of the method according to the invention, the activation of the crude clay is carried out in the aqueous phase. For this purpose, the acid is brought into contact with the crude clay as an aqueous solution. In this case, it is possible to proceed by initially slurrying the crude clay, which is preferably provided in the form of a powder, in water. Subsequently, the acid is added in preferably concentrated form. However, the raw clay can also be slurried directly in an aqueous solution of the acid, or the aqueous solution of the acid can be applied to the raw clay. According to an advantageous embodiment, the aqueous acid solution can be sprayed, for example, onto a preferably crushed or powdery raw clay, the amount of water being preferably chosen to be as low as possible and, for example, using a concentrated acid or acid solution. The amount of acid may preferably be between 1 and 10% by weight, more preferably between 2 and 6% by weight, preferably strong, acid, in particular a mineral acid, such as sulfuric acid, based on the anhydrous raw clay (atro) can be selected. If necessary, excess water can be evaporated and the activated raw clay then ground to the desired fineness. After the aqueous solution of the acid has been dispensed, it is only possible to dry, if necessary, until the desired moisture content has been reached.

According to a preferred embodiment of the invention it is not necessary that the excess acid and the salts formed during the activation are washed out. Rather, after the task of acid, as usual in the acid activation, no washing step is carried out, but the treated raw clay dried and then ground to the desired grain size. When grinding usually a typical bleaching earth fineness is set.

According to a further embodiment of the method according to the invention, the raw clay is activated with an iron salt. For this purpose, the raw clay can be sprayed, for example, with an aqueous solution of the iron salt. Suitable iron salts are, for example, the iron salts of halides or of organic acids, such as acetates or citrates. A preferred iron salt is iron sulfate. The amount of iron salt applied to the raw clay is preferably selected in the range of 1 to 6% by weight, based on raw raw clay.

The grain size or the mean grain size of the bleaching earth product used in the process according to the invention should preferably be selected such that when the optionally activated raw clay or the bleaching earth product is used, a complete - -

a simple and simple separation of the clay from the refined product is made possible. Preferably, the mean grain size of the powdered raw clay is selected in a range of 10 to 63 μm. Typically, the fineness is chosen so that on a sieve with a mesh size of 63 microns about 20 to 40% by weight of the mixture remain (sieve residue) and on a sieve with a mesh size of 25 microns about 50 to 65 wt .-% of Stay behind. This can be referred to as typical bleaching earth fineness.

In the process according to the invention, the acid degumming and a wet bleaching can be dispensed with under certain conditions, and the vacuum bleaching can be started immediately after the bleaching earth product has been added.

This rationalized refining is particularly suitable for oils which have a phosphorus content, in particular phospholipid content, of less than 100 ppm, preferably less than 50 ppm. The phosphorus content can be determined, for example, by elemental analysis.

In particular, the process according to the invention is suitable for the refining of palm oil.

The invention will be explained in more detail by means of examples and with reference to an attached figure. Showing:

1 shows a schematic process diagram for the physical refining of oils, in particular palm oil.

Crude edible oil, for example palm oil, is usually refined according to the principle of physical refining by a process as shown schematically in FIG. The - -

Crude oil which has been obtained, for example, by pressing corresponding plant seeds in an oil mill is first subjected to drying and degassing in order to remove, for example, dissolved oxygen from the oil. The crude oil is fed to a degumming stage, in which the gums, in particular phospholipids, are separated. The degumming may include pre-degumming and acid degumming. In the pre-degumming water is added to the crude oil and the mixture is stirred at about 70 to 80 ⁰ 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 ⁰ 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 ⁰ 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-phosphor crude oils, such as palm oil - -

oil, can be dispensed if necessary, the acid degumming and directly the bleaching be carried out.

Degumming is followed by bleaching of the oil, initially with wet bleaching and then with vacuum bleaching. In wet bleaching, the oil is mixed with water and bleaching earth, with amounts ranging from about 0.1 to 0.5% by weight for water and 0.3 to 2.0% by weight for bleaching earth being chosen. The oil is heated at atmospheric pressure to about 80 to 100 ⁰ C and stirred for about 20 minutes. Subsequently, a vacuum is applied (for example 100 mbar) and the oil is stirred for a further 30 minutes at about 90 to 120 ^° C. The oil is then filtered, for example via a filter with a paper filter. The filtration is carried out at a temperature of about 80 ⁰ C.

After bleaching, the oil is deodorized. For this purpose, superheated steam, which has an outlet temperature of about 240 to 260 ⁰ C, passed through the oil to remove free fatty acids and 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.

After refining, the oil has a phosphorus content of less than 3 ppm and an iron content of less than 0.1 ppm.

In the method according to the invention, the refining of the crude oil is carried out in the manner described above, but a special bleaching earth product is used as adsorbent or bleach, in particular in the bleaching. For oils which have a phosphorus content of less than about 80 ppm, preferably less than 50 ppm, the degumming - ZO -

step be omitted and, if necessary, after drying and degassing of the crude oil, be made directly a bleaching of the oil.

Examples:

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

The following analysis methods were used:

Surface area / pore volume:

The specific surface area is carried out on a fully automatic nitrogen porosimeter from Micromeritics, type ASAP 2010, according to DIN 66131. The pore volume is determined using the BJH method (E.P. Barrett, L.G. Joyner, P.P. 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 isotherms 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 determined according to AOCS Cc 13b-45. Chlorophyll A determination was according to AOCS Cc 13d-55.

Water content:

The water content of the products at 105 ⁰ C is determined using the method DIN / ISO-787/2. _2?

Silicate analysis:

This analysis is based on the total amount of raw clay or the corresponding product. After dissolution of the solids, the individual components are treated with conventional specific analytical methods, e.g. ICP, analyzed and quantified.

Ion exchange capacity:

For the determination of ion exchange capacity (IEC), the dried raw clay to be examined over a period of two hours at 105 ⁰ C. 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 diffractometry:

The X-ray images are taken on a high-resolution powder diffractometer made by Phillips (X ¹ -Pert-MPD (PW 3040)), which is equipped with a Cu anode.

Determination of sediment volume

A graduated 100 ml measuring cylinder is filled with 100 ml of distilled water or an aqueous solution of 1% soda and 2% trisodium polyphosphate. 2 g of the substance to be measured are added slowly and in portions, each about 0.1 to 0.2 g, with a spatula on the surface of the water. After this _O

Decreasing an added portion, the next portion is added. After the 2 g of substance have been added and dropped to the bottom of the measuring cylinder, the cylinder is allowed to stand for one hour at room temperature. Then the height of the sediment volume in ml / 2g is read off the graduation of the measuring cylinder.

Determination of volume increase of sediment volume (swelling capacity)

The sample batch used for determining the sediment volume as described above is closed with Parafilm and allowed to stand vibration-free for three days at room temperature. 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 dry 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 strainer is covered with a plastic lid and the vacuum cleaner is switched on. 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 a tempered weighed porcelain crucible with lid approx. 1 g dried sample is weighed to 0, 1 mg and 2 h - -

annealed at 1000 ^° C. in a muffle furnace. Thereafter, the crucible is cooled in a desiccator and weighed.

Determination of bulk density

A glass measuring cylinder cut off at the 1000 ml graduation is weighed empty and then the bulk material to be measured is filled with the aid of a powder funnel in a train so that a bulk cone is obtained at the upper end of the measuring cylinder. The bulk material is scraped off with the aid of a ruler and material attached to the outside of the measuring cylinder is removed. The filled measuring cylinder is weighed again. The difference of the measured weights corresponds to the bulk density in g / 1000 ml.

Determination of mean particle size

The particle size is determined on the "Malvern Mastersizer S" by laser diffraction in the particle air flow, indicating the d50 value, i.e. 50% of all particles <x μm.

example 1

Characterization of the raw clay A

A raw clay A (Süd-Chemie AG, Moosburg, Germany, Rohtonlager Ref. No.: 05407) suitable for the process according to the invention was investigated with regard to its physicochemical properties. The results obtained are shown in Tables 2 and 3. Table 2

Physical-chemical analysis of raw clay A

Specific surface area (BET) (mVg) 358

Pore volume (ml / g) 0.580

Cation exchange capacity (meq / 100g) 55

Sediment volume in water (ml / 2g) 6.0

Silicate:

57.0 SiO ₂ (wt.%)

Fe ₂ O ₃ (wt%) 4.3

Al ₂ O ₃ (wt%) 12.4

CaO (wt%) 4.6

MgO (wt%) 8.5

Na ₂ O (wt.%) 0.5

K ₂ O (wt.%) 1.4

TiO ₂ (wt.%) 0.4

Loss on ignition (2h 1000 ⁰ C) 8.9

Sum (% by weight) 99.0

Furthermore, the raw clay A characterized in Table 2 was examined for the proportion of pore volume formed by pores of radii. The corresponding data are summarized in Table 3 a-c.

Table 3a

Relative proportions of the pores in the pore volume

Range 0 - 75 A 0 - 140 A 0 - 250 A 0 - 800 A> 800 A

Share (%) 26 55 69 80 20 - -

Table 3b

Relative proportions of the pores in the pore volume

Range 0 - 75 Ä 75 - 140 Ä; 140 - 250 A 250 - 800 A> 800 A

Share (%) 26 29 14 11 20

Table 3c

Relative proportions of the pores in the pore volume

Example 2 (Comparative Examples)

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

Table 4

NABE: naturally active bleaching earth SMBE: surface modified bleaching earth HPBE: high performance bleaching earth a) Süd Chemie AG, Munich, DE b) Oil-Dri Corp., USA

- - Example 3

Bleaching of palm oil

To carry out the refining experiments, two different palm oils were used whose properties are summarized in Table 5. :

Table 5

Properties of raw palm oils

The crude palm oils were refined in the following ways:

a) Refining palm oil C

For the refining of palm oil C, the dried and degassed crude palm oil was first treated with 0.075% by weight of citric acid (20%) 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 given in Table 12. The mixture was first stirred at atmospheric pressure for 20 minutes at 95 ⁰ C, then the pressure was lowered to 30 mbar and the mixture for a further 30 minutes at 110 ⁰ C stirred. After bleaching, that became - -

Oil at 80 ⁰ C on a Filterutsehe, which was covered with a filter paper, filtered.

The deodorization of the bleached oil was carried out by at a pressure of <1 mbar for 120 minutes superheated steam (exit temperature: 260 ⁰ C) was passed through the oil. The oil was characterized after the individual purification steps. The values are given in Table 6.

Table 6 a

Table 6b

- -

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) was added and the mixture stirred at 80 ⁰ C for an additional 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 ⁰ C, then the pressure was lowered to 30 mbar and the mixture for a further 30 minutes at 120 ⁰ C stirred. After the bleaching the oil at 80 ⁰ C over a Filternutsehe which was lined with a filter paper, was filtered.

The deodorization of the bleached oil was carried out by at a pressure of <1 mbar for 120 minutes superheated steam (exit temperature: 255 ⁰ C) was passed through the oil. The oil was characterized after each refining step. The values are given in Table 7.

Table 7 b

- 4 -

c) refining palm oil D

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

Table 8 a

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 crude 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 ⁰ C and then ground to a typical Bleicherdefeinheit. The properties found for the activated raw clays are summarized in Table 9.

Table 9 a

Table 9 b

- -

Example 5

Bleach of rapeseed and soybean oil

A degummed and deacidified rapeseed oil or soybean oil with 1.2 wt .-% (rapeseed oil) or 0.4 wt .-% (soybean oil) of the bleaching earths given in Tables 10 and 11 at 110 ⁰ C and 105 ⁰ C 30 Bleached under a pressure of 30 mbar for a few minutes. The bleaching earth is then filtered off and the color number of the oil is determined by means of the Lovibond method in a 5 ¹ A "cuvette The values determined for Lovibond red and chlorophyll" A "are reproduced in Tables 10 and 11.

Table 10

Bleaching of rapeseed oil

- - Table 11

Bleaching of soybean oil

Claims

1. A process for refining fats and / or oils, wherein

providing a crude oil derived from a vegetable or animal material;

a specific surface area of more than 200 m ² / g; an ion exchange capacity of more than 40 meq / 100g; has 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% by weight; and

the bleached oil is separated from the bleaching earth product.

2. The method of claim 1, wherein the total pore volume of the raw clay is greater than 0.5 ml / g.

The method of claim 1 or 2, wherein the ion exchange capacity of the raw clay is greater than 50 meq / 100g. - -

4. The method according to any one of the preceding claims, wherein the raw clay, based on the raw anhydrous clay, has a MgO content of more than 5 wt .-%.

5. The method according to any one of the preceding claims, wherein the raw clay has a Fe ₂ O ₃ content, based on the anhydrous raw clay of less than 5 wt .-%.

6. The method according to any one of the preceding claims, wherein the sediment volume of the crude clay in water is less than 10 ml / 2g.

7. The 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.

8. The method of claim 7, wherein the proportion of the pores having a diameter of more than 25 nm in the total pore volume is less than 40%.

9. The method according to any one of the preceding claims, wherein the raw clay is surface-activated.

The process of claim 9, wherein the surface activation raw clay is contacted with an acid.

The process of claim 10, wherein the acid is contacted with the crude clay as an aqueous solution.

12. The method according to claim 10 or 11, wherein the acid is a mineral acid.

13. The method of claim 12, wherein the mineral acid is sulfuric acid or phosphoric acid.

14. The method according to any one of the preceding claims, wherein the raw clay is activated with an iron salt.

15. The method of claim 14, wherein the iron salt is Fe ₂ (SO ₄ ) ₃ .

16. The method according to any one of the preceding claims, wherein the crude oil has a phosphorus content, calculated as P, of less than 100 ppm.

17. Procedure ^! according to one of the preceding claims, wherein the crude oil is not subjected to degumming.