OA17917A - Dry-modified acid-activated bleaching earth, process for production thereof and use thereof. - Google Patents
Dry-modified acid-activated bleaching earth, process for production thereof and use thereof. Download PDFInfo
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- OA17917A OA17917A OA1201600286 OA17917A OA 17917 A OA17917 A OA 17917A OA 1201600286 OA1201600286 OA 1201600286 OA 17917 A OA17917 A OA 17917A
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- Prior art keywords
- bleaching
- weight
- water content
- bleaching earth
- acid
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- 238000004061 bleaching Methods 0.000 title claims abstract description 145
- 238000000034 method Methods 0.000 title claims abstract description 34
- 238000004519 manufacturing process Methods 0.000 title description 16
- 239000002253 acid Substances 0.000 title description 13
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 102
- 239000004927 clay Substances 0.000 claims abstract description 47
- 229910052570 clay Inorganic materials 0.000 claims abstract description 47
- 239000007787 solid Substances 0.000 claims abstract description 20
- 150000007522 mineralic acids Chemical class 0.000 claims abstract description 15
- 238000001035 drying Methods 0.000 claims abstract description 13
- 239000000203 mixture Substances 0.000 claims abstract description 8
- 238000000227 grinding Methods 0.000 claims abstract description 5
- 238000002156 mixing Methods 0.000 claims abstract description 3
- 239000003921 oil Substances 0.000 claims description 43
- KRKNYBCHXYNGOX-UHFFFAOYSA-N citric acid Chemical compound OC(=O)CC(O)(C(O)=O)CC(O)=O KRKNYBCHXYNGOX-UHFFFAOYSA-N 0.000 claims description 30
- 239000000463 material Substances 0.000 claims description 22
- 229960004106 citric acid Drugs 0.000 claims description 10
- 235000015165 citric acid Nutrition 0.000 claims description 10
- QAOWNCQODCNURD-UHFFFAOYSA-N Sulfuric acid Chemical compound OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 claims description 9
- 239000003925 fat Substances 0.000 claims description 9
- 238000007670 refining Methods 0.000 claims description 9
- 239000000741 silica gel Substances 0.000 claims description 8
- 229910002027 silica gel Inorganic materials 0.000 claims description 8
- FEWJPZIEWOKRBE-XIXRPRMCSA-N Mesotartaric acid Chemical compound OC(=O)[C@@H](O)[C@@H](O)C(O)=O FEWJPZIEWOKRBE-XIXRPRMCSA-N 0.000 claims description 7
- NBIIXXVUZAFLBC-UHFFFAOYSA-N phosphoric acid Chemical compound OP(O)(O)=O NBIIXXVUZAFLBC-UHFFFAOYSA-N 0.000 claims description 7
- 235000002906 tartaric acid Nutrition 0.000 claims description 7
- 239000011975 tartaric acid Substances 0.000 claims description 7
- 229960001367 tartaric acid Drugs 0.000 claims description 7
- BJEPYKJPYRNKOW-UHFFFAOYSA-N Malic acid Chemical compound OC(=O)C(O)CC(O)=O BJEPYKJPYRNKOW-UHFFFAOYSA-N 0.000 claims description 6
- 239000010779 crude oil Substances 0.000 claims description 6
- 229940099690 malic acid Drugs 0.000 claims description 6
- 235000011090 malic acid Nutrition 0.000 claims description 6
- 239000001630 malic acid Substances 0.000 claims description 6
- 150000007524 organic acids Chemical class 0.000 claims description 6
- 229910000147 aluminium phosphate Inorganic materials 0.000 claims description 3
- 235000013311 vegetables Nutrition 0.000 claims description 3
- 235000015112 vegetable and seed oil Nutrition 0.000 abstract description 7
- 239000008158 vegetable oil Substances 0.000 abstract description 6
- 239000010775 animal oil Substances 0.000 abstract 1
- 235000019198 oils Nutrition 0.000 description 40
- 238000004332 deodorization Methods 0.000 description 23
- 230000000052 comparative effect Effects 0.000 description 21
- ATNHDLDRLWWWCB-AENOIHSZSA-M chlorophyll a Chemical compound C1([C@@H](C(=O)OC)C(=O)C2=C3C)=C2N2C3=CC(C(CC)=C3C)=[N+]4C3=CC3=C(C=C)C(C)=C5N3[Mg-2]42[N+]2=C1[C@@H](CCC(=O)OC\C=C(/C)CCC[C@H](C)CCC[C@H](C)CCCC(C)C)[C@H](C)C2=C5 ATNHDLDRLWWWCB-AENOIHSZSA-M 0.000 description 16
- 229930002868 chlorophyll a Natural products 0.000 description 15
- 210000002741 Palatine Tonsil Anatomy 0.000 description 14
- 235000019484 Rapeseed oil Nutrition 0.000 description 13
- 230000000694 effects Effects 0.000 description 10
- 230000004913 activation Effects 0.000 description 8
- 238000001914 filtration Methods 0.000 description 8
- 235000019197 fats Nutrition 0.000 description 7
- 239000000047 product Substances 0.000 description 6
- 238000004140 cleaning Methods 0.000 description 5
- 235000014593 oils and fats Nutrition 0.000 description 5
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 5
- 235000019482 Palm oil Nutrition 0.000 description 4
- 150000007513 acids Chemical class 0.000 description 4
- 239000002540 palm oil Substances 0.000 description 4
- 239000011148 porous material Substances 0.000 description 4
- 239000000796 flavoring agent Substances 0.000 description 3
- 235000019634 flavors Nutrition 0.000 description 3
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 description 3
- 229910052710 silicon Inorganic materials 0.000 description 3
- 239000010703 silicon Substances 0.000 description 3
- 239000000126 substance Substances 0.000 description 3
- 235000019486 Sunflower oil Nutrition 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000003463 adsorbent Substances 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 2
- 229910052681 coesite Inorganic materials 0.000 description 2
- 239000000470 constituent Substances 0.000 description 2
- 229910052906 cristobalite Inorganic materials 0.000 description 2
- 238000010192 crystallographic characterization Methods 0.000 description 2
- 230000018109 developmental process Effects 0.000 description 2
- 239000000499 gel Substances 0.000 description 2
- XEEYBQQBJWHFJM-UHFFFAOYSA-N iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 2
- 239000000944 linseed oil Substances 0.000 description 2
- 239000004006 olive oil Substances 0.000 description 2
- 235000008390 olive oil Nutrition 0.000 description 2
- 235000005985 organic acids Nutrition 0.000 description 2
- 230000003647 oxidation Effects 0.000 description 2
- 238000007254 oxidation reaction Methods 0.000 description 2
- 230000000704 physical effect Effects 0.000 description 2
- 229910052904 quartz Inorganic materials 0.000 description 2
- 239000000377 silicon dioxide Substances 0.000 description 2
- 239000003549 soybean oil Substances 0.000 description 2
- 235000012424 soybean oil Nutrition 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- 229910052682 stishovite Inorganic materials 0.000 description 2
- 239000002600 sunflower oil Substances 0.000 description 2
- 229910052905 tridymite Inorganic materials 0.000 description 2
- 239000002351 wastewater Substances 0.000 description 2
- JLPULHDHAOZNQI-ZTIMHPMXSA-N 1-hexadecanoyl-2-(9Z,12Z-octadecadienoyl)-sn-glycero-3-phosphocholine Chemical compound CCCCCCCCCCCCCCCC(=O)OC[C@H](COP([O-])(=O)OCC[N+](C)(C)C)OC(=O)CCCCCCC\C=C/C\C=C/CCCCC JLPULHDHAOZNQI-ZTIMHPMXSA-N 0.000 description 1
- 229940067606 Lecithin Drugs 0.000 description 1
- 229940067631 Phospholipids Drugs 0.000 description 1
- 150000008043 acidic salts Chemical class 0.000 description 1
- 230000002378 acidificating Effects 0.000 description 1
- 239000011149 active material Substances 0.000 description 1
- 230000000274 adsorptive Effects 0.000 description 1
- 229960000892 attapulgite Drugs 0.000 description 1
- 239000007844 bleaching agent Substances 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 235000019804 chlorophyll Nutrition 0.000 description 1
- 229930002875 chlorophylls Natural products 0.000 description 1
- 230000003247 decreasing Effects 0.000 description 1
- 235000014113 dietary fatty acids Nutrition 0.000 description 1
- KARVSHNNUWMXFO-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane;hydrate Chemical compound O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Al]O[Al]=O KARVSHNNUWMXFO-UHFFFAOYSA-N 0.000 description 1
- 238000002845 discoloration Methods 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 239000000194 fatty acid Substances 0.000 description 1
- 150000004665 fatty acids Chemical class 0.000 description 1
- 239000012065 filter cake Substances 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 229910052742 iron Inorganic materials 0.000 description 1
- 239000000787 lecithin Substances 0.000 description 1
- 235000010445 lecithin Nutrition 0.000 description 1
- 235000021388 linseed oil Nutrition 0.000 description 1
- 229910052901 montmorillonite Inorganic materials 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- MYMOFIZGZYHOMD-UHFFFAOYSA-N oxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052625 palygorskite Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 150000003904 phospholipids Chemical class 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 238000003825 pressing Methods 0.000 description 1
- 150000003839 salts Chemical class 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 239000011780 sodium chloride Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
- 238000005429 turbidity Methods 0.000 description 1
- 235000019871 vegetable fat Nutrition 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
Abstract
The invention relates to a process for
producing a bleaching earth, comprising the steps
of drying a water-rich raw clay to a reduced water
content, mixing the raw clay having a reduced
water content with a solid organic and/or
concentrated inorganic acid, and grinding the
mixture of raw clay having a reduced water
content and solid organic and/or concentrated
inorganic acid, in which case the bleaching earth
then has a water content of 20% to 40% by
weight. The invention further encompasses a
bleaching earth obtainable by this process and to
the use thereof for bleaching of raw animal or
vegetable oil.
Description
DRY-MODIFIED ACID-ACTIVATED BLEACHING EARTH, PROCESS FOR PRODUCTION THEREOF AND USE THEREOF
The invention relates to a process for producing a bleaching earth, especially a dry-modified bleaching earth, to a bleaching earth obtained by the process, and to the use thereof for bleaching of vegetable or animal crude oil.
In the industrial production of oils and fats, bleaching earths are used to remove turbidity and discoloration, or else to remove oxidation accelerators. The adsorptive cleaning can significantly improve flavor, color and storage stability of the oils and fats. Cleaning is accomplished using various classes of bleaching earths.
A first group is the class of the highly active bleaching earths that are usually based on, montmorillonite (HPBE = high-performance bleaching earth). This group especially includes acid-activated montmorillonites, wherein the acid activation is conducted in a complex process by dealumination of the raw clays with concentrated acids at high températures. This process affords a bleaching earth product with a very high spécifie surface area and large pore volume. Even the use of small amounts of this highperformance bleaching earth leads to noticeable cleaning of the crude oils. Small use amounts in the bleaching process are désirable because the spent bleaching earth firstly binds residual amounts of oil, which reduces the yield, and the spent bleaching earth secondly has to be disposed of in accordance with applicable régulations.
A disadvantage of these high-performance bleaching earths is the fact that the dealumination with acid causes large amounts of acidic salt-rich wastewater to occur during the production, and this can be processed or disposed of only in costly and inconvénient processes. The high costs for the disposai of the wastes and the complex production process are the reasons for the comparatively high costs of such high-performance bleaching earths.
A further group is the class of naturally active clays. These naturally occurring bleaching earths hâve already been used for hundreds of years for the cleaning of fats and oils. These naturally active Systems (also called fuller's earth) can be provided very inexpensively. However, they hâve only low bleaching power, and so they are usually unsuitable for the cleaning of oils and fats that are difficult to bleach. Moreover, by comparison with highperf ormance bleaching earths, significantly greater amounts of the adsorbent hâve to be used in order to achieve the desired bleaching resuit. As a resuit, however, higher losses of oil or fat hâve to be accepted, since the bleaching earths cannot be separated in pure form, and certain amounts of oil or fat remain in the bleaching earth.
The third class of bleaching earths, called surfaceactivated Systems (SMBE = surface-modified bleaching earth; surface-activated bleaching earths), represents a compromise between low production costs and acceptable activity. Here, a naturally active raw clay is contacted with small amounts of acid and hence in situ activation is achieved. For this process, raw clays comprising attapulgite and hormite hâve been found to be especially useful. These hâve quite a high spécifie surface area for natural raw clays of about 100 to 180 m2/g and a pore volume of about 0.2 to 0.35 mL/g. Since, however, salts formed in the acid activation or unreacted fractions of the acids are not washed out, these remain on the product and are at least partly also deposited in the pores. As a resuit, these acid-activated bleaching earths generally do not attain the same efficiency as that obtained by high-performance bleaching earths (HPBE) which are produced by dealumination with acid. However, the simple production process enables comparatively inexpensive production, since no acidic wastewater is obtained.
WO 96/33621 discloses the production of bleaching earths from clay material having a water content of not more than 8% by weight by grinding the clay with solid organic polycarboxylic acids.
WO 99/02256 describes the production of bleaching earths from clay material, wherein the clay is first preferably dried to a water content of 8% to 10% by weight, then activated with a concentrated solution of an inorganic or organic acid and subsequently dried to a maximum water content of 13% by weight.
A common factor among the abovementioned bleaching earth
| types | is | that, after | activation | or prior to | use, | they | are |
| dried | to | a minimum | water content (usually | 8% to | 12% | by | |
| weight | , typically 10% | by weight or | less). | ||||
| The main | field of | use of the | bleaching | earths | is | the |
refining of oils and fats, in this case the bleaching of course. After the bleaching, the refined oil is expected to meet particular demands in relation to color, flavor and shelf life. For instance, the oil must not be too dark and, according to the oil type, may hâve a yellow to green hue. In addition, the oil is to hâve a long shelf life without any détérioration in flavor, i.e. is not to hâve a rancid taste.
In the processing which is customary nowadays, the oil, after pressing, is first degassed and dried in order to remove dissolved oxygen, for example. Subsequently, gums, especially phospholipids, are removed. For this purpose, the dried and degassed oil is admixed with phosphoric acid and stirred at about 95°C and standard pressure for about 15 to 20 minutes. In order to be able to remove the guns more easily, toward the end of the degumming, further water is added, for instance in a proportion of 0.2% by weight. After stirring briefly, the lecithin phase is removed, for example by centrifuging. The subséquent bleaching of the degummed oil comprises two stages, a wet bleaching stage and a vacuum bleaching stage. For the wet bleaching, the degummed oil is admixed with 0.1% to 0.5% by weight of water and, after the oil has been heated to 95 °C, 0.3% to 2% by weight of bleaching earth is added. The mixture is then stirred at standard pressure for about 20 minutes. Subsequently, vacuum is applied (for example 100 mbar) and the oil is stirred at 95°C for a further 30 minutes. After the bleaching, the spent bleaching earth is removed, for example by filtering the mixture through a suction filter covered with a paper filter.
After the bleaching, the oil is deodorized. For this purpose, superheated steam having an exit température of, for instance, 200 to 240°C is passed through the oil in order to remove free fatty acids and unpleasant flavoring and odorous substances. The deodorization is conducted under reduced pressure at a pressure in the région of less than 5 mbar, preferably 1 to 3 mbar, and in some cases also lower.
After the refining, the oil has to meet particular demands in relation, for example, to color, taste and shelf life. For example, the oil should not hâve a brown appearance, but a yellow to green hue according to the type. One standard for this purpose is the Lovibond red color value (CV red) , which should be at a minimum. In order to increase shelf life, the oil should hâve a very low iron or phosphorus content. Moreover, the oil should be of minimum sensitivity to oxidation, in order to prevent the development of a rancid odor and taste.
As well as the high quality of the oil, the refining, however, should also be conducted in a rational and inexpensive manner. The process outlined above has become established in commercial oil processing. However, there is still a need for optimization of oil refining, such that it can be conducted more quickly and at lower cost without having to accept losses in the quality of the oil.
The raw clays known from EP 1893329 B1 or EP 2099561 B1 are a good starting material for high-quality bleaching earths. To date, these hâve been used to produce high-quality SMBEs after reaction with 3% sulfuric acid and drying to a water content of 10% by weight. A disadvantage of the production of these SMBEs is that the raw clay has a water content of about 60% by weight and is transported with this high water content. The water content is then reduced to 10% by weight in production by heating and driving out the water. This is costly and not environmentally sustainable.
It was an object of the invention to develop an efficient bleaching earth that does not hâve these disadvantages.
It was a particular object of the invention to provide a process for producing an adsorbent, especially a bleaching earth, which avoids the disadvantages of the prior art and leads to a product having high adsorption capacity, especially with regard to the bleaching effect of oils and fats.
This object is achieved by a process having the features of claim 1. Advantageous developments of the process are the subject of the dépendent daims.
The invention firstly provides a process for producing a dry-modified bleaching earth, wherein a water-rich raw clay is first dried to a reduced water content, and the raw clay having a reduced water content is mixed and ground with 1%5% by weight (based on the weight of the raw clay) of a solid organic and/or concentrated inorganic acid. It is a feature of the process of the invention that the bleaching earth thus obtained has a water content of 20% to 40% by weight. In the production of the bleaching earth of the invention, it is consequently possible to dispense with a drying step after the grinding of the raw clay with the solid organic and/or concentrated inorganic acid, which makes the production inexpensive and less labor-intensive overall than in conventional processes. The bleaching earths obtainable by the process of the invention nevertheless show excellent results in the bleaching fats or oils, as shown in the experimental examples.
Since the process of the invention includes only moderate drying of the raw clay, it is advantageously possible to resort to mild drying methods that do not entail any great technical complexity or energy consumption. More particularly, it has been found that the raw clay can be sun-dried in order to reduce the water content from originally 50% to 70% by weight down to 20% to 40% by weight. The residual water content to be attained is partly determined by the duration of the solar drying, which is typically 1 to 14 days, preferably less than 1 week and ideally 2 to 4 days (depending on the duration and intensity of sunshine). Such solar drying increases the effective proportion of solid constituents in the raw clay, such that less water is ultimately transported for the same mass and hence the transport costs (based on the solid constituent of the raw clay) are reduced.
The water-rich raw clay preferably has a water content of 50% to 70% by weight. However, the process of the invention can also be used advantageously for raw clays having other water contents, for example for water contents of more than 40% by weight.
After the drying and activation with solid organic and/or concentrated inorganic acid, the bleaching earth ideally has a water content of 30% to 40% by weight. However, water contents down to about 20% by weight are likewise possible in accordance with the invention. The advantage of the gentle drying of the raw clays achievable in accordance with the invention and the omission of a drying step after the grinding of the raw clay with the solid organic and/or concentrated inorganic acid can, however, best be realized when the raw clays are dried to the preferred water content range of 30% to 40% by weight.
The process of the invention advantageously works with solid organic acids seiected from the group comprising citric acid, malic acid and tartaric acid, and/or concentrated inorganic acids such as, in particular, concentrated sulfuric acid and/or concentrated phosphoric acid. The acids may be présent alone or in any desired mixtures with one another. Tartaric acid has surprisingly been found to be particularly effective in the bleaching of vegetable oil, especially of rapeseed oil.
The proportion of solid organic and/or concentrated inorganic acid is typically in the range of l%-5% by weight (based on the weight of the raw clay) , and a proportion of l%-3% by weight has been found to be préférable.
The water-rich raw clay which is particularly suitable for the process of the invention contains a mixed smectitesilica gel phase. Particular preference is given to raw clays as described in detail in EP 1893329 B1 and EP 2099561 B1. Explicit reference is made here to the raw clays described in these two documents and the characterization and properties thereof, and likewise to the experimental details for the détermination of the chemical and physical properties.
The invention further provides a bleaching earth, especially a dry-modified bleaching earth (DMBE for short), obtainable by the process described in detail above. By contrast with bleaching earths according to prior art, the bleaching earth of the invention has a comparatively high water content. While bleaching earths are dried in a costly and inconvénient manner to a water content of about 10% by weight in the prior art, the bleaching earths of the invention hâve water contents of 20% by weight or more, typically up to 40% by weight. Surprisingly, bleaching earths having such high water contents can be ground without any problem to typical bleaching earth particle sizes (dry sieve residue on 63 pm sieve: 20% to 40% by weight; dry sieve residue on 25 pm sieve: 40% to 65% by weight) without sticking of the grinders. This positive aspect is manifested particularly for the raw clays described in detail above that comprise a mixed smectite-silica gel phase.
The invention further provides for the use of the (especially dry-modified) bleaching earth of the invention for refining of fats and/or oils, especially of vegetable fats and/or oils. The refining preferably comprises the bleaching and optionally the subséquent deodorization, followed by the removal of the bleaching earth, especially by filtration.
The invention also finally provides a method of refining fats and/or oils. This involves providing a crude oil obtained from vegetable or animal material. The crude oil is subjected to bleaching by treating it with an (especially dry-modified) bleaching earth of the invention. The bleached oil is then separated from the bleaching earth, for example by filtration.
A suitable starting material for the process of the invention for production of a dry-modified bleaching earth in particular, i.e. in the form of a water-rich raw clay, is especially a mixed smectite-silica gel phase that features a very high spécifie surface area of more than 120 mz/g, preferably more than 150 m2/g. The mixed smectite-silica gel phase may hâve a spécifie surface area of up to 300 m2/g, preferably up to 280 m2/g. In addition, the mixed smectitesilica gel phase features a very high total pore volume of more than 0.35 mL/g. The mixed smectite-silica gel phase has an unusually high proportion of a silica gel phase and therefore has a high silicon content, calculated as SiO2, of at least 60% by weight, preferably more than 63% by weight, especially preferably more than 70% by weight. In accordance with one embodiment of the invention, the silicon content of the mixed smectite-silica gel phase is less than 85% by weight. In a further embodiment, the silicon content of the mixed smectite-silica gel phase, calculated as SiO2, is less than 75% by weight. Such water-rich raw clays that are suitable in accordance with the invention are known from Sohling et al., Clay Minerais (2009) 44, 525-537 and
Emmerich et al., Clay Minerais (2010) 45, 477-488.
Especially production are raw clays EP 2099561 Bl.
suitable for the process of dry-modified bleaching earths as described in detail in EP of the invention for in particular
1893329 B1 and
Explicit reference is made here to the raw clays described in these two documents and the characterization and properties thereof, and likewise to the experimental details for the détermination of the chemical and physical properties.
Surprisingly, it is possible to use the sun-dried raw clay to produce a bleaching earth that does not need a further drying step, i.e. is capable of effectively bleaching fats and oils at a water content of 20%-40%. This was not to be expected according to the current state of the art.
EXAMPLES
The invention is elucidated in detail hereinafter by examples.
The following analysis methods and general production and test methods were employed:
Oil analysis:
The color values in oils (Lovibond color values) were determined in accordance with AOCS Ce 13b-45. The chlorophyll A détermination was effected in accordance with AOCS Ce 13d-55.
Activation of the raw clay with sulfuric acid (state of the art, for comparative purposes):
The raw clay is mixed with water and then activated with 3% by weight of H2SO4. For this purpose, 100 g of raw clay powder dried to about 10% H2O are mixed intimately with 208 g of water and 2.83 g of H2SO4 (96%) in a beaker. The résultant mixture is dried at 110°C to a water content of about 10% and then ground to a typical bleaching earth fineness (dry sieve residue on 63 pm sieve: 20% to 40% by weight; dry sieve residue on 25 pm sieve: 40% to 65% by weight).
Inventive activation of the raw clay with solid organic or concentrated inorganic acid:
The raw clay is - unless stated otherwise in the examples first dried to a water content of about 35% by weight, then mixed intimately with 3% by weight of solid organic or concentrated inorganic acid and hence activated. Subsequently, the mixture is ground to a typical bleaching earth fineness (dry sieve residue on 63 pm sieve: 20% to 40% by weight; dry sieve residue on 25 pm sieve: 40% to 65% by weight).
Bleaching of vegetable oil
An optionally degummed and deacidified vegetable oil is according to the oil used - bleached with 0.30%-1.60% by weight of bleaching earth at 100-120°C under a pressure of 30-100 mbar for 20-30 minutes. Subsequently, the bleaching earth is filtered off and the color values of the oil (CV red) are determined with the aid of the Lovibond method in a 5Μ cuvette (unless stated otherwise). A portion of this oil is additionally deodorized by steam treatment (30 minutes, at 220-270°C, < 1 mbar) . The oil obtained here is also analyzed with the aid of the Lovibond method. The values after the deodorization are of particular relevance here, since almost ail oils in practice are deodorized after bleaching.
Example 1: Bleaching earth made from sun-dried raw clay for bleaching of rapeseed oil
A raw clay which has been sun-dried to a water content of 21.5% or 26.2% or 27.6% (in accordance with EP 1893392 Bl) was homogenized with 3% by weight of citric acid in each case, dried to about 10% by weight of water and ground, in order to obtain 3 specimens of a bleaching earth.
Rapeseed oil was bleached with 3 specimens of the abovedescribed bleaching earth and, for comparison, with a highquality SMBE (Tonsil® Suprême 112 FF, Clariant Produkte (Deutschland) GmbH). For this purpose, a degummed and deacidified rapeseed oil was bleached with 0.60% by weight of bleaching earth under a pressure of 30 mbar at 110°C for 30 minutes. Subsequently, the bleaching earth was filtered off and the color values (CV) of the oil were determined with the aid of the Lovibond method in a 5^ cuvette. A portion of this oil was additionally deodorized by steam treatment (30 minutes, 230°C, < 1 mbar) . The oil obtained here was also analyzed with the aid of the Lovibond method.
Table 1 shows the results of the bleaching operations.
| Table 1 | ||||
| Bleaching of rapeseed oil | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF | 1.4 | 0.03 | 0.6 | 0.04 |
| Specimen 1.1 (26.2% by wt. of water, dried to 10% by wt. ) | 6.0 | 0.02 | 0.3 | 0.018 |
| Specimen 1.2 (21.5% by wt. of water, dried to 10% by wt. ) | 5.8 | 0.01 | 0.3 | 0.016 |
| Specimen 1.3 (27.6% by wt. of water, dried to 10% by wt. ) | 4.6 | 0.01 | 0.3 | 0.018 |
The bleaching earths activated with solid citric acid attain moderate red values on bleaching of rapeseed oil (CV red 6.0-4.6 according to Lovibond AF 995), but excellent red values after deodorization (CV red 0.3) and very good chlorophyll removal (< 0.02 ppm). This example shows that solar drying does not damage the raw clay and good bleaching earths (specimens 1.1 to 1.3 as comparative specimen) are producible therewith.
Example 2: Filtration characteristics and bleaching of palm oil with sun-dried raw clay specimens of raw clay sun-dried to a water content of about 35% by weight (in accordance with EP 1893392 Bl) were divided and half of each was dried at 110 °C to a water content of about 9% by weight. The water-containing and dried specimens were analyzed separately with respect to their filtration times. For this purpose, 10 g in each case of the raw clay specimen are added to 100 g of crude linseed oil and stirred at 96.5°C for 10 min. The raw clay-linseed oil mixture is then filtered through a suction filter and the time taken for the entire visible surface of the filtercake (essentially raw clay) to be visually dry is recorded. Table 2 shows the results.
| Table 2 | ||
| Filtration characteristics | ||
| Sample | Water content (% by wt.) | Filtration time (s) |
| Specimen 2.1 (inventive) | 32.3 | 51 |
| Specimen 2.1 (comparative specimen) | 9.0 | 73 |
| Specimen 2.2 (inventive) | 34.8 | 50 |
| Specimen 2.2 (comparative specimen) | 8.9 | 65 |
| Specimen 2.3 (inventive) | 36.8 | 50 |
| Specimen 2.3 (comparative specimen) | 9.0 | 64 |
It was found that the materials which hâve only been sundried had better (i.e. shorter) filtration times than the materials dried conventionally to a lower water content, and consequently the séparation of the bleaching earth from the oil in the case of sun-dried materials is improved.
Table 3 shows the results for CV red after bleaching and deodorization of palm oil for bleaching earth specimen 2.2 (moist with 34.8% water, dry with 8.9% water) compared to an SMBE (Tonsil® Suprême 112 FF, Clariant Produkte (Deutschland) GmbH).
Table 3
| Bleaching of palm oil (bleaching with 1.6% by weight of bleaching earth, 0.02% H3PO4 at 120°C and 100 mbar for 20 min; deodorization at 240-270°C and < 1 mbar for 120 min) | ||
| Sample | Bleaching | Deodorization |
| CV red (M cuvette) | CV red (5M cuvette) | |
| Tonsil® Suprême 112 FF (comparative material) | 7.4 | 2.5 |
| Specimen 2.2 (34.8% water) (inventive) | 17.9 | 2.1 |
| Specimen 2.2 (8.9% water) (comparative specimen) | 15.6 | 2.1 |
In the bleaching of palm oil, raw clays which had been sundried (residual water content 34.8%) and dried to a water content of about 9% by weight showed identical results even though the sun-dried materials hâve less active material for the same dosage (i.e. are basically more dilute) . Even compared to the SMBE Tonsil® Suprême 112 FF (as a représentative of high-quality standard bleaching earths), the sun-dried clay showed excellent results after the deodorization.
Example 3: Bleaching effect for various vegetable oils
The raw clays from example 2 were additionally processed by adding 3% citric acid (H3Cit) and mixing until attainment of a homogeneous mass to give DMBEs, and the bleaching effect was tested on various vegetable oils (olive oil, soybean oil, rapeseed oil, sunflower oil). Again, the comparison of sun-dried material (water content 34.8%) was made with normally dried material (water content 8.9%) and an SMBE (Tonsil® Suprême 112 FF, Clariant Produkte (Deutschland) GmbH). The experimental details and the results are compiled in tables 4 to 7.
| Table 4 | ||||
| Bleaching of olive oil (bleaching with 1.50% by weight of bleaching earth at 100°C and 30 mbar for 30 min; deodorization at 240°C and < l*10'3 mbar for 60 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 2.6 | 0.05 | 2.3 | 0.00 |
| Specimen 2.2 (8.9% water) + 3% by weight of H3Cit (comparative specimen) | 2.1 | 0.1 | 1.6 | 0.01 |
| Specimen 2.2 (34.8% water) + 3% by weight of H3Cit (inventive) | 3.1 | 0.19 | 2.2 | 0.14 |
| Table 5 | ||||
| Bleaching of soybean oil (bleaching with 0.30% by weight of bleaching earth at 100°C and 30 mbar for 30 min; deodorization at 220°C and < 1 mbar for 30 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 5.4 | 0.11 | 0.8 | 0.10 |
| Specimen 2.2 (8.9% water) + 3% by weight of H3Cit (comparative specimen) | 16.6 | 0.07 | 0.6 | 0.07 |
| Specimen 2.2 (34.8% water) + 3% by weight of H3Cit (inventive) | 16.3 | 0.12 | 1.0 | 0.11 |
Table 6
| Bleaching of rapeseed oil (bleaching with 0.60% by weight of bleaching earth at 110°C and 30 mbar for 30 min; deodorization at 230°C and < 1 mbar for 30 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 1.4 | 0.03 | 0.6 | 0.04 |
| Specimen 2.2 (8.9% water) + 3% by weight of H3Cit (comparative specimen) | 8.2 | 0.03 | 0.4 | 0.03 |
| Specimen 2.2 (34.8% water) + 3% by weight of H3Cit (inventive) | 3.1 | 0.04 | 0.4 | 0.04 |
| Table 7 | ||||
| Bleaching of sunflower oil (bleaching with 1.00% by weight of bleaching earth at 100°C and 100 mbar for 30 min; deodorization at 240°C and < l*10“3 mbar for 60 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 1.4 | 0.01 | 1.3 | 0.002 |
| Specimen 2.2 (8.9% water) + 3% by weight of H3Cit (comparative specimen) | 1.6 | 0.01 | 1.2 | 0.004 |
| Specimen 2.2 (34.8% water) + 3% by weight of H3Cit (inventive) | 1.8 | 0.06 | 1.3 | 0.03 |
The product of the invention (i.e. the dry-modified bleaching earth DMBE having a high residual water content of 5 34.8%) surprisingly exhibited good to very good values after deodorization.
Example 4 :
Bleaching effect for various residual water contents
Here, the behavior of the product having relatively high water content with respect to rapeseed oil, which is important in central Europe, was examined. The water content was varied between 8.9% and 34.8%, and it was found that, surprisingly, the bleaching effect improved with increasing water content (decreasing red value). After the deodorization, the red values - irrespective of the water content - were ail at an excellent level.
The raw clays of example 2 were additionally processed by addition of 3% citric acid (H3Cit) as described in example 3 to give DMBE and the bleaching effect was tested for rapeseed oil. Again, the comparison of sun-dried material (water content 21% to 34.8%) was made with normally dried material (water content 8.9%) and an HPBE (Tonsil® Suprême 112 FF, Clariant Produkte (Deutschland) GmbH). The experimental details and the results are compiled in table
8.
| Table 8 | ||||
| Bleaching of rapeseed oil (bleaching with 0.60% by weight of bleaching earth at 110°C and 30 mbar for 30 min; deodorization at 230°C and < 1 mbar for 30 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 1.4 | 0.03 | 0.6 | 0.04 |
| Specimen 2.2 (8.9% water) + 3% by weight of H3Cit (comparative specimen) | 8.2 | 0.03 | 0.4 | 0.03 |
| Specimen 2.2 (21.0% water) + 3% by weight of H3Cit (inventive) | 4.0 | 0.02 | 0.4 | 0.03 |
| Specimen 2.2 (25.3% water) + 3% by weight of H3Cit (inventive) | 3.6 | 0.02 | 0.4 | 0.02 |
| Specimen 2.2 (30.5% water) + 3% by weight of H3Cit (inventive) | 3.3 | 0.02 | 0.4 | 0.03 |
| Specimen 2.2 (34.8% water) + 3% by weight of H3Cit (inventive) | 3.1 | 0.04 | 0.4 | 0.04 |
Example 5: Bleaching effect for different acid activation
Analogously to example 3, the raw clay was activated with various solid organic acids. The raw clay was processed by addition of 3% solid organic acid (citric acid, malic acid, tartaric acid) to give DMBEs and the bleaching effect was tested for rapeseed oil. Again, the comparison of sun-dried 10 material (water content 34.8%) was made with normally dried material (water content 8.9%) and an HPBE (Tonsil® Suprême 112 FF, Clariant Produkte (Deutschland) GmbH). The experimental details and the results are compiled in table
9.
| Table 9 | ||||
| Bleaching of rapeseed oil (bleaching with 0.60% by weight of bleaching earth at 110°C and 30 mbar for 30 min; deodorization at 230°C and < 1 mbar for 30 min) | ||||
| Sample | Bleaching | Deodorization | ||
| CV red | Chlorophyll A (ppm) | CV red | Chlorophyll A (ppm) | |
| Tonsil® Suprême 112 FF (comparative material) | 1.4 | 0.03 | 0.6 | 0.04 |
| Specimen 2.2 (8.9% water) + 3% by weight of citric acid (comparative specimen) | 8.2 | 0.03 | 0.4 | 0.03 |
| Specimen 2.2 (34.8% water) + 3% by weight of citric acid (inventive) | 3.1 | 0.04 | 0.4 | 0.04 |
| Specimen 2.2 (8.9% water) + 3% by weight of malic acid (comparative specimen) | 3.8 | 0.01 | 0.4 | 0.03 |
| Specimen 2.2 (34.8% water) + 3% by weight of malic acid (inventive) | 2.7 | 0.03 | 0.6 | 0.04 |
| Specimen 2.2 (8.9% water) + 3% by weight of tartaric acid (comparative specimen) | 4.7 | 0.01 | 0.4 | 0.02 |
| Specimen 2.2 (34.8% water) + 3% by weight of tartaric acid (inventive) | 1.7 | 0.02 | 0.5 | 0.03 |
It has been found that, surprisingly, it was possible to distinctly improve the bleaching effect by substituting 5 citric acid with malic acid and especially tartaric acid.
The improvement was far more marked in the case of the sundried material (34.8% water) than in the case of the product with a normal water content (8.9% water). The higher water content surprisingly promotes the bleaching action of the 10 DMBE.
i
Claims (10)
1. A process for producing a bleaching earth, comprising the steps of
- drying a water-rich raw clay to a reduced water content,
- mixing the raw clay having a reduced water content with l%-5% by weight (based on the weight of the raw clay) of a solid organic and/or concentrated inorganic acid,
- grinding the mixture of raw clay having a reduced water content and solid organic and/or concentrated inorganic acid, wherein the bleaching earth has a water content of 20% to 40% by weight.
2. The process as claimed in claim 1, wherein the waterrich raw clay has a water content of 50% to 70% by weight.
3. The process as claimed in claim 1 or 2, wherein the
comprising citric acid, malic acid and tartaric acid.
5. The process as claimed in any of daims 1 to 3, wherein the concentrated inorganic acid is selected from the group comprising sulfuric acid and phosphoric acid.
6. The process as claimed in any of daims 1 to 5, wherein the proportion of solid organic acid or concentrated inorganic acid is l%-3% by weight, based on the weight of the raw clay.
7. The process as claimed in any of daims 1 to 6, wherein the water-rich raw clay contains a mixed smectite-silica gel phase.
8. A bleaching earth obtainable by the process as claimed in any of daims 1 to 7.
9. The use of the bleaching earth as claimed in claim 8 for
10 refining of fats and/or oils.
10. A method of refining fats and/or oils, wherein
- a crude oil obtained from vegetable or animal material is provided,
15 - the crude oil is subjected to bleaching by treating it with a bleaching earth as claimed in claim 8, and
- the bleached oil is separated from the bleaching earth.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| EP14000725.3 | 2014-02-28 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| OA17917A true OA17917A (en) | 2018-02-27 |
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