Oil purification process

Abstract

The invention relates to a process for purification of oil by heat treatment in order to degrade phospholipids present in the non-purified oil.

Claims

1. A method for purification of lipid material, the method comprising: a) providing a feed of lipid material; b) heat treating the lipid material without added water or other solvent wherein heat treatment takes place at any temperature in a range of 240° C. to 280° C., and wherein a residence time in step b) is maintained during a period of 1 minute to 30 minutes and wherein the lipid material has not undergone any pre-treatment prior to heating and wherein the heat treatment is performed in a pressure chamber; and c) post treating the lipid material by a water treatment step which is performed in a presence of water in an amount of 1 wt % to 3 wt % to a volume of the lipid material; wherein water treatment step c) is performed at a temperature of 130° C. to 220° C., to thereby reduce an amount of phosphorous and/or metal compounds in the lipid material.

2. The method according to claim 1, wherein the lipid material is a plant based, microbial based or animal based lipid or any combination thereof.

3. The method according to claim 1, comprising: selecting a water content of the lipid material in the feed to be lower than 10000 ppm, lower than 5000 ppm, lower than 2000 ppm, lower than 1500 ppm, lower than 1000 ppm, lower than 500 ppm, lower than 250 ppm, lower than 100 ppm, lower than 50 ppm, lower than 25 ppm, lower than 10 ppm, lower than 5 ppm, lower than 1 ppm or such that the lipid feed is substantially water free.

4. The method according to claim 1, comprising: performing the water treatment step c) during a period of 1 minute to 30 minutes.

5. The method according to claim 1, comprising: removing water in the lipid material by evaporation.

6. The method according to claim 1, comprising: removing any impurities in the water treatment step c) by one or more of filtration, centrifugation or bleaching or any combinations thereof.

7. The method according to claim 1, wherein post-treatment step c) comprises: water washing/degumming or acid treatment/degumming or bleaching.

8. The method according to claim 1, wherein post-treatment step c) comprises: centrifugation and/or filtration to remove impurities formed during the process.

9. The method according to claim 1, wherein post-treatment step c) comprises: a bleaching treatment to remove impurities.

10. The method according to claim 1, wherein phosphorous compounds are phospholipids, selected from one or more of phosphatidyl ethanolamines, phosphadityl cholines, phosphatidyl inositols or phosphatidic acids.

11. A method for purification of lipid material according to claim 1, wherein a residence time in step b) is maintained during a period of 5 minutes to 30 minutes.

12. The method according to 1, comprising: performing the water treatment step c) during a period of 5 minutes to 30 minutes.

Description

FIGURES

(1) FIG. 1 illustrates the impurities in samples centrifuged in heat treatment of lecithin at 240° C. and how the amounts of the impurities vary over time.

(2) FIG. 2 illustrates the impurities in samples centrifuged in heat treatment of lecithin at 210° C. and how the amounts of the impurities vary over time.

(3) FIG. 3 illustrates impurities in RSO samples with no wash and with water wash.

(4) FIG. 4 illustrates the typical heating curve of batch heat treatment of animal fat at 240° C. for 30 min.

(5) FIG. 5 illustrates the filtration fluxes for different feeds.

(6) FIG. 6 illustrates the amount of impurities in oil after water wash with 5% water added at 240° C. (treatment temperature ca. 220° C.), samples withdrawn from the reactor at certain time and centrifuged and filtered.

(7) FIG. 7 illustrates the amount of impurities in oil after water wash with 5% water added at 160° C., samples withdrawn from the reactor at certain time and centrifuged.

(8) FIG. 8 illustrates the amount of impurities in oil after water wash with 5% water added at 80° C., samples withdrawn from the reactor at certain time and centrifuged.

(9) FIG. 9 illustrates the impurities in AF samples with no wash and with water wash and how the amounts of the impurities vary over time.

(10) In specific embodiments the invention also relates to the following items:

(11) 1. A method for purification of lipid material, the method comprising

(12) a) Providing a feed of lipid material,

(13) b) optionally pre-treating the lipid material,

(14) c) heat treating the lipid material,

(15) d) optionally subjecting the heat treated lipid material to a water treatment step,

(16) e) post treating the lipid material

(17) to thereby purify the lipid material from phospholipids

(18) 2. The method according to item 2, wherein the lipid material is a plant based or animal based fat or oil or wax or any combination thereof.

(19) 3. The method according to according any of the preceding items, wherein the pre-treatment may comprise water degumming, acid degumming, filtration and bleaching or any combinations thereof and in any order.

(20) 4. The method according to any of the preceding items, wherein the method does not comprise steps b) and/or d)

(21) 5. The method according to any of the preceding items, wherein the heating in step c) is performed at a temperature of e.g. about 200° C. to about 300° C.

(22) 6. The method according to any of the preceding items, wherein the heating in step c) is performed in the absence of any added water.

(23) 7. The method according to any of the preceding items, wherein the heating in step c) is maintained during a period of about 1 minute to about 30 minutes, such as about 5 minutes to about 30 minutes.

(24) 8. The method according to any of the preceding items, wherein water washing step d) is performed in the presence of water in an amount of e.g. about 1 wt % to about 5 wt % to the volume of the lipid material.

(25) 9. The method according to any of the preceding items, wherein water washing step d) is performed at a temperature of about e.g. 130° C. to about 220° C.

(26) 10. The method according to any of the preceding items, wherein water washing step d) is performed during a period of about 1 minute to about 30 minutes, such as about 5 minutes to about 30 minutes.

(27) 11. The method according to any of the preceding items, wherein water in the washing step d) is removed by flash evaporation.

(28) 12. The method according to any of the preceding items, wherein any solids in the water washing step d) are removed by one or more of filtration, degumming or bleaching or any combinations thereof.

(29) 13. The method according to any of the preceding items, wherein post-treatment step e) comprises water washing/degumming or acid degumming.

(30) 14. The method according to any of the preceding items, wherein step e) comprises an amount of water of about 1 wt % to about 5 wt % to the volume of the lipid material.

(31) 15. The method according to any of the preceding items, wherein the water washing/degumming in step e) is performed at a temperature of about 60° C. to about 80° C.

(32) 16. The method according to any of the preceding items, wherein post-treatment step e) comprises a centrifugation step to remove impurities formed during the process.

(33) 17. The method according to any of the preceding items, wherein post-treatment step e) further comprises a bleaching treatment to remove trace impurities.

(34) 18. The method according to any of the preceding items, wherein the phospholipids are one or more of phosphatidyl ethanolamines, phosphadityl cholines, phosphatidyl inositols, phosphatidic acids, and phosphatidyl ethanolamines.

(35) In another aspect, the invention further relates to the following articles:

(36) 1. A method for purification of lipid material, the method comprising

(37) a) Providing a feed of lipid material,

(38) b) heat treating the lipid material without added water or other solvent,

(39) c) post treating the lipid material

(40) to thereby reduce the amount of phosphorous and/or metal compounds in the lipid material.

(41) 2. The method according to article 1, wherein the lipid material is a plant based, microbial based or animal based lipid or any combination thereof.

(42) 3. The method according to article 1, wherein the lipid material is of fossil based origin, such as e.g. various products and by-products produced by the oil industry, such as e.g. various petroleum products such as e.g. fuel oils and gasoline (petrol) or spent lubrication oils.

(43) 4. The method according to any of the preceding articles, wherein the water content of the lipid material in the feed is lower than about 10000 ppm, such as e.g. lower than about 5000 ppm, such as e.g. lower than about 2000 ppm, such as e.g. lower than about 1500 ppm, such as e.g. lower than about 1000 ppm, such as e.g. lower than about 500 ppm, such as e.g. lower than about 250 ppm, such as e.g. lower than about 100 ppm, such as e.g. lower than about 50 ppm, such as e.g. lower than about 25 ppm, such as e.g. lower than about 10 ppm, such as e.g. lower than about 5 ppm, such as e.g. lower than about 1 ppm or such that the lipid feed/oil is substantially water free.

(44) 5. The method according to any of the preceding articles, wherein the method does not comprise step c).

(45) 6. The method according to any of the preceding articles, wherein the temperature in step b) is performed at any temperature in the range of e.g. about 200° C. to about 300° C.

(46) 7. The method according to any of the preceding articles, wherein residence time in step b) is maintained during a period of about 1 minute to about 30 minutes, such as about 5 minutes to about 30 minutes.

(47) 8. The method according to any of the preceding articles, wherein step c) comprises a water treatment step which is performed in the presence of water in an amount of e.g. about 1 wt % to about 5 wt % to the volume of the lipid material.

(48) 9. The method according to any of the preceding articles, wherein water treatment step c) is performed at a temperature of about e.g. 130° C. to about 220° C.

(49) 10. The method according to any of the preceding articles, wherein water treatment step c) is performed during a period of about 1 minute to about 30 minutes, such as about 5 minutes to about 30 minutes.

(50) 11. The method according to any of the preceding articles, wherein water in the lipid material is removed by evaporation.

(51) 12. The method according to any of the preceding articles, wherein any impurities in the water treatment step c) are removed by one or more of filtration, centrifugation or bleaching or any combinations thereof.

(52) 13. The method according to any of the preceding articles, wherein post-treatment step c) comprises water washing/degumming or acid treatment/degumming or bleaching.

(53) 14. The method according to any of the preceding articles, wherein step c) comprises an amount of water of about 1 wt % to about 5 wt % to the volume of the lipid material.

(54) 15. The method according to any of the preceding articles, wherein post-treatment step c) comprises a centrifugation and/or filtration step to remove impurities formed during the process.

(55) 16. The method according to any of the preceding articles, wherein post-treatment step c) further comprises a bleaching treatment to remove impurities.

(56) 17. The method according to any of the preceding articles, wherein phosphorous compounds are phospholipids, such as e.g. one or more of phosphatidyl ethanolamines, phosphadityl cholines, phosphatidyl inositols and phosphatidic acids.

(57) 18. A lipid material, obtainable by the method according to any of articles 1-17.

(58) 19. Use of a lipid material, obtainable by the method according to any of articles 1-17 in any catalytic process such as e.g. catalytic cracking, thermo-catalytic cracking, catalytic hydrotreatment, fluid catalytic cracking, catalytic ketonization, catalytic esterification, or catalytic dehydration.

(59) 20. Use of an unpurified lipid material in a method according to any of articles 1-17, for preparation of fuels or chemicals.

Definitions

(60) The following abbreviations have been used in the examples.

(61) TABLE-US-00001 MAG Monoacylglycerides DAG Diacylglycerides TAG Triacylglycerides FFA Free fatty acids Olig Lipid oligomers AF Animal fat RSO Rapeseed oil UCO Used cooking oil CPO Crude Palm oil

EXAMPLES

(62) The invention is now further illustrated in the following non-limiting examples. In the examples below the concentration of impurities is given in mg/kg in all examples. The lipid class composition (MAG, DAG, TAG, Olig, FFA) is in all examples given in area %.

Example 1. Heat Treatment of High Impurity Feed

(63) Lecithin, a mixture of water degummed phospholipids of soybean oil and thus high in metals and phosphorus, was heat treated at T 240° C. and 210° C. A stirred pressure reactor with high boiling hydrocarbon solvent was heated to a temperature ca. 20° C. above the intended reaction temperature. Lecithin-solvent solution was fed to the heated reactor so that the final lecithin concentration in the reactor was 3.7 wt %. Samples were withdrawn from the reactor at certain retention time. Part of the samples were water treated with 5 wt % water at 80° C. (1 min vortex mixing). All samples were centrifuged for 10 min at 60° C. to remove formed solids.

(64) Almost all impurities (metals and phosphorus) were removable by centrifugation after treatment at 240° C. for 5 min (FIG. 1, Table 1). At treatment temperature 210° C. the degradation of phospholipids is much slower and the level of impurities stayed high (FIG. 2, Table 2). Water treatment had small effect on the removal of impurities when treatment time had been long enough.

(65) TABLE-US-00002 TABLE 1 Analysis results for centrifuged samples withdrawn from the reactor in heat treatment of lecithin at 240° C. t (min) 0 (feed) 1 2 5 10 20 30 Fe 0.9 1.7 1.7 0.3 <0.1 <0.1 <0.1 Na 3.4 5.5 5.9 1.3 <1 1.2 <1 Ca 67 60 61 7.7 0.8 0.6 0.6 Mg 112 110 110 12 0.3 <0.3 <0.3 P 1082 990 990 140 23 16 14

(66) TABLE-US-00003 TABLE 2 Analysis results for centrifuged samples withdrawn from the reactor in heat treatment of lecithin at 210° C. t (min) 0 (feed) 1 2 5 10 20 30 Fe 0.9065 1 1.1 1.1 1.1 1.1 0.5 Na 3.404 5.1 4.9 5.8 5.6 5.9 2.9 Ca 66.6 64 68 65 66 64 28 Mg 111.925 110 120 120 120 113 49 P 1082.25 1100 1100 1100 1100 1000 420 After water treatment t (min) feed 1 2 5 10 20 30 Fe 0.9065 1.1 1.1 1.2 1 0.6 0.5 Na 3.404 4.7 4.7 5.4 4.2 3.4 2.7 Ca 66.6 70 71 72 59 37 27 Mg 111.925 120 120 120 98 61 45 P 1082.25 1100 1100 1100 840 530 380

Example 2. Heat Treatment of Rapeseed Oil in a Tube Reactor with and without Water Wash

(67) Water degummed rapeseed oil (RSO) was heat treated in a tube reactor for certain time and at certain temperature. Samples were centrifuged for 10 min at 60° C. after heat treatment. A sample was in addition water treated with 5 wt % water at 80° C. (1 min vortex mixing) and centrifuged for 10 min at 60° C.

(68) From these results it can be seen that a heat treatment at 240° C. for 20 min or 260-280° C. for 10 min is enough to degrade phosphorous and metal containing compounds in rapeseed oil so that the impurities can be removed in a water treated. The samples that were only centrifuged had considerably more impurities than the water washed samples.

(69) TABLE-US-00004 TABLE 3 Analysis results for RSO samples without and with water treatment. 200° C./ 200° C./ 240° C./ 240° C./ 260-280° feed 10 min 20 min 10 min 20 min C./10 min No water treatment Fe 1 0.6 0.5 0.5 0.5 0.5 Na <1.0 <1 2 2.3 <1 <1.0 Ca 179 142 124 119 95.8 90.8 Mg 42.1 35.7 31.5 30.5 24.2 23.5 P 217 163 148 142 107 119 Water treatment Fe 0.5 0.4 0.3 0.3 <0.1 <0.1 Na <1.0 2.2 1.7 2.1 1.8 1.9 Ca 155 99.4 86.7 83.6 3.2 8.1 Mg 38.8 25.5 22.5 19.7 0.7 1.8 P 174 117 103 98.5 4.5 10.3

Example 3. Heat Treatment of Animal Fat in a Tube Reactor with and without Water Treatment

(70) Animal fat was heat treated in a tube reactor for certain time and at certain temperature. Samples were centrifuged for 10 min at 60° C. after heat treatment. A sample was in addition water treated with 5 wt % water at 80° C. (1 min vortex mixing) and centrifuged for 10 min at 60° C.

(71) From these results it can be seen that a heat treatment at the tested temperature/time combinations were sufficient to make phosphorous and metals containing impurities in the oil removable in a simple water treatment. The samples that were only centrifuged had considerably more impurities than the water treated samples. Already water treatment of the untreated feed oil, results in considerable decrease in the level of impurities (P 124.fwdarw.46 ppm). Heat treatment followed by water wash decreased the P level to 6 ppm.

(72) TABLE-US-00005 TABLE 4 Analysis results for AF samples without and with water treatment. No water treatment 236° C./ 240 ° C./ 253° C./ 263 ° C./ Feed 25 min 20 min 20 min 40 min Fe 57.3 39 34.3 25.2 15.4 Na 22.5 19.8 18.3 15.2 10.1 Ca 97.4 73.3 68.3 52.7 34.9 Mg 24.5 18 16.9 12.6 7.5 P 124 94.7 87.6 64.9 41.4 Water treatment 236 ° C./ 240 ° C./ 253 ° C./ 263 ° C./ Feed 25 min 20 min 20 min 40 min Fe 28.5 2.9 2.6 2.7 1.5 Na 6.9 2.4 3.1 2.6 1.8 Ca 29.1 5.8 5.5 5.7 3.5 Mg 8.2 1.3 1.2 1.2 0.8 P 46.4 6.7 6.5 6.7 4.2

Example 4. Water Wash at Different Temperature for Heat Treated Animal Fat

(73) Animal fat was heat treated in a stirred pressure reactor at 500 rpm mixing. The oil was heated to 240° C. and kept there for a certain time, where after the reactor was cooled. A typical heating curve is presented in FIG. 4.

(74) Heat treated animal fat (30 min at 240° C.) was water treated by adding 5 wt % water to the fat at specific temperature. Treatment temperatures were ca. 220° C., 150° C. and 80° C. At 220° C. and 150° C., water was fed to the fat in a pressure reactor from a feed vessel and mixed at 500 rpm. At 80° C., water was dispersed to the oil with a 2 min high sheer mixing, followed by mixing at 500 rpm. Samples were withdrawn at certain retention time and centrifuged (10 min/60° C.).

(75) At 220° C. the impurities were removed in centrifugation after only 2 min of contact time with water (Table, FIG. 6). At 5 min treatment time, the hydrolysis was minimal; at 30 min the product contained already 28 wt % FFA.

(76) At 150° C. the same trend is seen. A very short contact time is needed to remove impurities in centrifugation (Table 6, FIG. 7). Prolonged water treatment time can result in higher levels of impurities. Very little hydrolysis of the oil happens in 30 min.

(77) At 80° C. water treatment was also effective (Table, FIG. 8).

(78) Water treatment at higher temperature (above 130° C.) enable evaporation of the water by flashing, where after solids can be removed by filtration or bleaching.

(79) TABLE-US-00006 TABLE 5 5% water was added to animal fat at 240° C. after 30 min heat treatment, samples withdrawn from the reactor at certain time. Samples were centrifuged and filtered after treatment. water T t wt % (° C.) (min) Fe Na Ca Mg P MAG DAG TAG Olig FFA 0 (before 240 30 41.4 18.2 77.4 17.7 99 1.5 22 58.8 0.8 17 water addition 5 220 1 2.1 4.6 4.5 1.1 4.8 5 220 2 1.2 5 2.2 0.7 2.1 5 220 5 0.9 7.2 2.1 0.5 1.5 1.9 23.2 56 0.9 18 5 220 10 0.9 7.2 1.7 0.4 1.5 5 220 20 1.1 7.6 1.9 0.6 2.9 5 220 30 1.1 10.4 1.5 0.6 1.9 5.4 28.5 37.4 0.8 28

(80) TABLE-US-00007 TABLE 6 5% water added to animal fat at 160° C. after heat treatment (240° C./30 min), samples withdrawn from the reactor at certain time. Samples were centrifuged after treatment. water T t wt % (° C.) (min) Fe Na Ca Mg P MAG DAG TAG Olig FFA 0 (before 160 0 31.2 15.4 53.6 13.5 70 1.6 22.1 58.1 1.1 17 water addition) 5 150 1 2.1 4.3 3.5 1 3.6 5 150 2 2.4 3.1 3.7 1 3.7 5 150 5 3.6 7.5 6 1.7 5.9 5 150 10 4.2 3.7 7 1.7 7.3 5 150 20 4.9 5.1 8.3 2 8 5 150 30 6 5.2 9.9 2.7 9.9 2.1 23.9 55.2 1 18

(81) TABLE-US-00008 TABLE 7 5% water added to animal fat at 80° C. after heat treatment (240° C./30 min), samples withdrawn from the reactor at certain time. Samples were centrifuged after the treatment. water T t wt % (° C.) (min) Fe Na Ca Mg P MAG DAG TAG Olig FFA 0 (before 80 0 31.2 15.4 53.6 13.5 70 1.6 22.1 58.1 1.1 17 water addition) 5 80 2 1.8 3 3.6 0.9 6.2 5 80 3 2.3 3.7 4.5 1.1 7.3 5 80 5 3.1 3.5 5.7 1.5 9.8 5 80 30 4 4.3 8 1.7 7.4 1.8 23.1 56.7 1.4 17

Example 5. Heat Treatment of Used Cooking Oil (UCO)

(82) Heat treatment of used cooking oil was performed in a stirred pressure reactor as a batch experiment. The oil was heated to 240° C., kept there for 30 min and cooled. The heated UCO was treated such that a sample was centrifuged to remove solids, the rest of the oil was water treated (5% water, 2 min ultraturrax high shear mixing, 5 min 500 rpm mixing) and centrifuged. The water treated oil was additionally bleached (700 ppm citric acid, 0.2 wt % water, 0.5 wt % bleaching earth, mixing for 20 min at 80 C, drying and filtration).

(83) Results for UCO are presented in Table. The result for bleaching of untreated UCO (700 ppm citric acid+0.2 wt-% water, 0.7 wt-% bleaching earth) is given as a reference.

(84) Heat treatment of UCO followed by centrifugation did not result in any purification. However, heat treatment (240° C./30 min) followed by a water treatment with 5% water and bleaching treatment resulted in pure product.

(85) Hence, the proposed process is suitable also for difficult feeds such as used cooking oil.

(86) TABLE-US-00009 TABLE 8 Analysis results for used cooking oil. HT + HT + water water feed treat- treat- water Feed HT + ment + ment + feed treated bleach. centrif. centrif. bleach. MAG area % 5.1 3.9 3.3 DAG area % 15.2 21.8 21.8 TAG area % 63.2 56.7 57.9 Olig. area % 2.5 3.8 3.3 FFA area % 14 13.9 13.7 Fe mg/kg 3.1 1.5 0.4 5.6 1.7 <0.1 Cu mg/kg 1.6 0.2 0.4 0.3 0.3 <1 Si mg/kg 1.4 1.5 1.2 16.9 1 <1 Na mg/kg 14.3 3.6 2.7 2.2 1.8 0.7 Ca mg/kg 57.6 31.7 2 69.6 20.2 <0.3 Mg mg/kg 2.7 0.9 0.3 3.4 1 <0.3 P mg/kg 42.7 20.5 5.8 44.2 13.5 0.9

Example 6. Heat Treatment of Crude Palm Oil (CPO)

(87) Heat treatment of crude palm oil was performed in a stirred pressure reactor as batch experiment. The oil was heated to 240° C., kept there for 30 min and cooled.

(88) After opening the reactor the oil and impurities were separated in two different ways. A sample was centrifuged at 60° C./10 min to remove the solids. Another sample was water treated with 5 wt % water at 80° C. (1 min vortex mixing) and centrifuged for 10 min at 60° C.

(89) Results are given in Table 9. Results show that this process is also effective for “easy” feedstocks such as palm oil. Impurities are lowered considerably and only slight changes in lipid profile is seen.

(90) TABLE-US-00010 TABLE 9 Analysis results for CPO samples. HT + water treatment + Feed HT + centrif. centrif. MAG 1.1 1.8 1.8 DAG 13 18.9 19.7 TAG 78.3 67.5 66.9 Olig. <0.1 0.4 0.2 FFA 7.7 11.4 11.4 Fe 4.5 1.6 0.6 Na <1.0 <1.0 <1.0 Ca 13.5 4.5 1.9 Mg 1.6 0.8 <0.3 P 13.7 4.6 1.6

Example 7 Heat Treatment Followed by Bleaching

(91) Animal fat, which is very difficult to purity, was bleached (2000 ppm citric acid, 0.2 wt % water, 1 wt % bleaching earth, mixing for 20 min at 80 C, drying and filtration). Samples used were both untreated ones and ones after heat treatment at different conditions (temperature and time). Bleaching products after heat treatment were considerably purer than bleaching product of untreated feed. The more severe conditions (higher temperature and longer time) resulted in the better removal of metals and phosphorus.

(92) The result for bleached products are presented in Table 10.

(93) TABLE-US-00011 TABLE 2 Impurities in bleached feed and after heat treatment (HT). HT HT HT HT 280° C./ 230° C./ 280° C./ 230° C./ Feed 5 min + 5 min + 30 min + 30 min + Feed bleached bleach. bleach. bleach. bleach. Fe 0.39 <0.1 <0.1 <0.1 0.12 0.14 Na 180 6.1 2 2.4 <1.0 <1.0 Ca 7.1 0.4 <0.3 <0.3 <0.3 0.34 Mg 0.39 0.45 <0.3 <0.3 <0.3 <0.3 P 27 8.6 0.97 3.4 <0.6 1.1

Example 8 Heat Treatment of Tall Oil Pitch (TOP) Followed by Acid Treatment

(94) Untreated and heat treated (280° C./30 min in stirred pressure reactor) tall oil pitch samples (three different feeds) were acid treated at 90 C with phosphoric acid (PA) by mixing 1000-2000 ppm PA (added as 30-50% aqueous solution) to the feed with a high shear mixer for 1 min and continuing mixing with a magnetic stirrer for 60 min. At the end, temperature was raised to 100 C and the acid treated TOP was filtered through a precoat of cellulose fibre.

(95) The purification (Table 11) and filterability of heat treated TOP after acid treatment was considerably better than that of untreated TOP.

(96) TABLE-US-00012 TABLE 3 Acid treatment (AT) of untreated (comparative example) and heat treated (280° C./30 min) TOP after precoat filtration. Fe Na Ca Mg P TOP 1: feed 39 470 26 3.4 120 TOP 1: AT 3.6 32 1.2 <0.3 45 (1000 ppm PA (30%)) + F TOP 1: HT + AT <0.1 4.6 0.33 <0.3 13 (1000 ppm PA (30%)) + F TOP 2: feed 230 730 15 5.1 93 TOP 2: AT 190 430 5.5 3.6 540 (2000 ppm PA (50%)) + F TOP 2: HT + 0.2 1.7 0.64 <0.3 17 AT (2000 ppm PA (50%)) + F TOP 3: feed 33 630 8.9 3.4 68 TOP 3: AT 18 270 3.8 1.4 340 (2000 ppm PA (50%)) + F TOP 3: HT + AT 0.18 5.7 0.41 <0.3 61 (2000 ppm PA (50%)) + F

Comparative Example 1. Heat Treatment of Animal Fat with Different Amount of Water in Stirred Reactor

(97) Heat treatment of animal fat has been performed in a stirred pressure reactor as batch experiments with different amount of water (water added in the beginning and present during heating and cooling). The reactor with the oil and water was heated to 240° C. and kept there for 30 min before cooling the reactor.

(98) After opening the reactor the oil and water was separated by centrifugation and the oil analysed for glyceride distribution.

(99) Results are given in Table 12. Purest oil is gained with water contents 1-3 wt %. Hydrolysis of oil is low at up to 1 wt % water content, resulting in an increase of FFA from 18 wt % to 21 wt %. At higher water content undesirable hydrolysis of lipids is seen.

(100) Hence, it is desirable to perform heat treatment with preferably lower than 1 wt % water and perform a water wash in a subsequent shorter step at lower temperature (Example 4).

(101) TABLE-US-00013 TABLE 12 Glyceride distribution of heat treated animal fat with different amount of water. MAG, DAG, TAG, Olig. and FFA presented as area %. water T t (wt %) (° C.) (min) MAG DAG TAG Olig FFA 1.6 18.1 62.2 0.3 18 0.5 240 30 2.1 25.5 53.1 0.4 19 1 240 30 3.2 28.1 46.9 1 21 3 240 30 5.8 31.6 32.2 0.6 30 10 240 30 15.1 21.2 5.5 0.1 58 20 240 30 11.4 13.7 2.9 0.5 72