VERSATILE METHOD FOR PURIFYING GLYCERIDIC MATERIALS

Abstract

The invention provides a method for the purifying of low-quality glyceridic material usually unfit for use as feed or food. The method includes a thermal treatment of the low-quality glyceridic material and chemical treatments. The purified oils and fat are suitable feed-stock or suitable components thereof for a hydrogenation processes yielding to high quality renewable diesel. The process thus permits the recycling of waste material that is usually discarded, into a valuable high-quality fuel.

Claims

1. A method for the purification of low-quality glyceridic material to yield a purified glyceridic material, said low-quality glyceridic material containing triglycerides, partial glycerides, FFA and P, Na, K, Mg, Ca and Fe, said purification process including: (a) a thermal treatment of the low-quality glyceridic material at a temperature of at least 160° C., to yield a thermally treated low-quality glyceridic material, (b) allowing to cool the thermally treated low-quality glyceridic material of step a) at a temperature of 120° C. or lower to yield a cooled thermally treated low-quality glyceridic material, and (c) applying one or more standard refining technique(s) to said cooled thermally treated low-quality glyceridic material of step b), wherein said thermal treatment does not lower the concentration of FFA contained in said low-quality glyceridic material.

2. The method according to claim 1, wherein said standard refining technique(s) belong(s) to the field of the refining of edible vegetable oil or to the field of the refining edible animal oil.

3. The method according to claim 1, wherein said standard purification techniques are able to remove at least 90% of the phosphorus and at least 95% of the sum of elements Na, K, Mg, Ca and Fe.

4. The method according to claim 1, wherein the purified glyceridic material is a suitable material for the production of renewable diesel.

5. The method according to claim 1, wherein said thermal treatment of the low-quality glyceridic material is occurring in absence of any solvent and further in absence of any reactant.

6. The method according to claim 1, wherein said thermal treatment includes heating the low-quality glyceridic material at a temperature ranging from 160° C. to 300° C., preferably at a temperature ranging from 180° C. to 280° C., even more preferably at temperature ranging from 200° C. to 260° C.

7. The method according to claim 1, wherein said thermal treatment of the low-quality glyceridic material is realized during a period of time ranging from 5 minutes to 120 minutes, preferably ranging from 10 to 60 minutes, even more preferably ranging from 15 to 30 minutes.

8. The method according to claim 1, wherein said thermal treatment of the low-quality glyceridic material is realized in a hermitical vessel under adiabatic pressure.

9. The method according to claim 1, wherein said thermal treatment of the low-quality glyceridic material is realized in a hermitical vessel under a pressure ranging from 100 mbar to 10 bar, preferably ranging from 200 mbar to 8 bar and even more preferably ranging from 400 mbar to 6 bar.

10. The method according to claim 1, wherein said thermal treatment of the low-quality glyceridic material is realized under a rotating mechanical agitation having a frequency ranging from 0.01 to 100 hertz, preferably ranging from 0.1 to 80 hertz, even more preferably ranging from 1 to 60 hertz.

11. The method according to claim 1, wherein the low-quality glyceridic material is at least partially water washed prior said thermal treatment.

12. The method according to claim 1, wherein the low-quality glyceridic material is at least partially washed with an aqueous acidic solution prior said thermal treatment.

13. The method according to claim 1, wherein the low-quality glyceridic material is at least partially degummed prior to said thermal treatment.

14. The method according to claim 1, wherein said one or more standard refining technique(s) include water washing, acidulated water washing, water degumming, acid degumming, bleaching realized with bleaching agent(s) such as bleaching earth and/or silica and/or activated carbon.

15. The method according to claim 1, wherein said low-quality glyceridic material contain at least 5% of FFA, preferably at least 10% of FFA, even more preferably at least 20% of FFA.

16. The method according to claim 1, wherein said low-quality glyceridic material contain at least 500 ppm of alkalinity, preferably at least 200 ppm of alkalinity, said alkalinity being defined at the sum of Na, K, Mg, Ca and Fe.

17. The method according to claim 1, wherein said purification includes a filtration step, said filtration step removing solid particles such as, but not limited to HDPE particles.

18. The method according to claim 17, wherein said filtration includes a filter aid.

19. The method according to claim 1, wherein said low-quality glyceridic materials include waste oils or fats of vegetable or animal origins, recycled oils or fats of vegetable or animal origins, rendered animal fats, acid oils.

Description

EXAMPLES

[0064] The present technology will be further described in the following examples, which should be viewed as being illustrative and should not be construed to narrow the scope of the disclosed technology or limit the scope to any particular embodiments.

Samples of Low-Quality Glyceridic Material

[0065] Table 1 summarizes the concentration of some major contaminants in typical animal fats that are improper for usage in food and feed applications. To put the level of contamination into perspective, table 1 also list the typical contamination found in crude soybean oil from North American origin. However, such contamination is very detrimental for the hydrodeoxygenation catalyst and thus it is paramount to reduce those contaminants to very low level. The goal is to purify low-quality glyceridic material in an economical way without consuming large quantity of chemical and/or solvent and without generating large volume of waste stream. It is also important to not further degrade the feedstock during the purification step(s), in particular the concentration of FFA should not increase at all or at least not increase markedly. Indeed, even if FFA are converted in renewable diesel during the HVO process, it is not advantageous to increase further the concentration of FFA since at high concentration and high temperature FFA can be corrosive.

TABLE-US-00001 TABLE 1 Crude soybean oil (typical values Contaminants Sample 1 Sample 2 Sample 3 for refence) FFA [%] .sup.(1) 19.4 28 29.7 1-2 P [ppm] 346 260 181  900-1200 Fe [ppm] 121 24 84 2 Ca [ppm] 273 90 72 30 Mg [ppm] 55 15 12 45 K [ppm] 224 797 1200 80 Na [ppm] 172 550 1023 80 Total [ppm] 1191 1736 2572 1138-1439 (except FFA) .sup.(1) FFA is only a contaminant in the case of edible vegetable oils. It must be removed from edible oil to meet organoleptic target.

Example 1

[0066] In Example 1, Sample 1 is directly degummed at 90° C. with an aqueous solution of citric acid (3.5 kg/ton of oil) and washed with aqueous solution of sodium hydroxide (0.55 kg/ton of oil). This standard degumming, known in the art as ‘acid degumming’ only removes 67.3% of the P presents in Sample 1. By comparison only about 5 to 10 ppm of P would remain in degummed soybean oil under same conditions which corresponds to a removal efficiency of in excess of 99%. However, 95.6% of the metals Fe, Ca, Mg, K and Na are removed from the Sample 1 during this degumming step.

[0067] Then two standard bleaching operations have been conducted at 100° C. during 30 min and at 100 mbar with 1.5 kg of citric acid and 20 kg of bleaching earth per ton of Sample 1 for the first and second bleaching. Thus, even if a relatively large amount of bleaching earth is used, still a large quantity of P remains in the sample 1:64 ppm after the first bleaching, and 37 ppm after the second bleaching corresponding to a removal efficiency of 81.5% and 89.3%, respectively. This removal efficiency is not satisfactory. For economical reason, it is not desired to conduct a third or fourth bleaching hoping to remove more phosphorus. Indeed, the cost of the bleaching earth and the glyceridic material loss would be prohibitive. Furthermore, it is not likely that a third and fourth bleaching operation would lead to a satisfactory removal of phosphorus. In sharp contrast, a bleaching operation conducted on degummed soybean oil would have led to the removal of nearly all phosphorus. Usually, only 2 to 3 ppm of phosphorus remains in degummed and bleached soybean oil corresponding to a cumulative removal rate of about 99.8%. The two consecutive bleaching operations further removed more metals (Fe, Ca, Mg, Na, K) of the sample 1 and after the second bleaching operation, 14 ppm of said metals remain which correspond to a cumulative removal rate of 98.3% which even if encouraging still fails to deliver the required metal removal efficiency.

[0068] Table 2 summarizes the cumulative removal of phosphorus and metals (sum of Fe, Ca, Mg, K, Na) as well as the concentration of those remaining elements after each purification operation. In Table 2, as well as in all tables, “P” means phosphorus, and “Metal” means the sums of the Fe, Ca, Mg, Na, and K.

TABLE-US-00002 TABLE 2 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) Water washing 18.5% (282 ppm)  23.8% (643 ppm) Degumming 67.3% (113 ppm) 95.6% (37 ppm) (including washing) First Bleaching 81.5% (64 ppm)   96.6% (28.8 ppm)  Second Bleaching 89.3% (37 ppm)  98.3% (14 ppm)

Example 2

[0069] In Example 2, Sample 3 is degummed and bleached two times successively. However, the degumming conditions have been slightly modified. The degumming has been realized at 90° C. with 19 kg of citric acid per ton of fat, which correspond to the molar ratio of the sum of the element K and Na to the amount of citric acid, and the washing after the degumming has been realized with water (without sodium hydroxide). Both bleaching operations are similar to the ones of Example 1.

[0070] Table 3 presents the cumulative removal rate of phosphorus and metals (sum of Fe, Ca, Mg, K, Na) as well as the concentration of those remaining elements. It can be seen that the removal of the phosphorus is not satisfactory since only 55.6% of this element is removed even after the second bleaching. The removal of the metals ions (sum of Fe, Ca, Mg, K, Na) was very promising after the acid degumming (99.5% of removal rate with about 15 ppm left). However, it has been observed that the metal concentration increases with the bleaching operation. This is due to leaching of some metals from the bleaching earth. This phenomenon is known but cannot be fully explained. It is possible that the presence of high concentration of FFA (about 30%) plays a role in this phenomenon. In conclusion, for this sample containing a large fraction of FFA, the removal of phosphorus, and to a lower extend the removal of metals ions (Fe, Ca, Mg, K, Na) remains problematic.

TABLE-US-00003 TABLE 3 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) Degumming 22.5% (62 ppm) 99.5% (14.8 ppm) (including washing) First Bleaching 41.3% (47 ppm) 99.3% (21.5 ppm) Second Bleaching   55.6% (35.5 ppm)   99.2% (22 ppm) 

Example 3

[0071] In Example 3, a blend of the three samples were degummed with aqueous solution of hydrochloric acid. The first trial has been realized with a molar ratio of 1:1 between the hydrochloric acid and the metals ions (Fe, Ca, Mg, K, Na) and a second trial has been done with a molar ratio in excess of 30%. Both trials have been done with 5% of water. Results are shown in Table 4.

TABLE-US-00004 TABLE 4 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) HCl washing (1:1) 17.8% (143 ppm) 76.9% (537.8 ppm) HCl (1:1.3) 39.7% (105 ppm) 98.2% (43 ppm)  

[0072] This example shows that even a very strong acid such as hydrochloric acid is unable to remove the impurities contained in a blend of various samples of low-quality glyceridic material. Since Examples 1 and 2 showed that standard purification techniques as used during the refining of edible vegetable and animal oils and fats failed to satisfactory purify technical fat, and even degumming with stronger acid failed as well, it is obvious that this strategy should be abandoned and that logically dedicated procedures should be developed. However, it has most surprisingly been observed that heating the technical fat at a high temperature (160° C. to 260° C.) in various conditions, but in all case is absence of any chemicals and/or solvent lead to a much more efficient removal of all the contaminants even when subsequently standards purification techniques are applied. This thermal treatment can be applied before any standard treatment(s) is/are applied on the technical fat or after one or more preliminary standard treatments such as a washing or degumming for example. By standard treatments, reference is made to the purification and refining treatment applied during the refining of edible vegetable/animal oils and fats. Those standard treatments are well known by the skilled artisan. Examples 4 to 14 will describe several variations of those standard treatments.

Example 4

[0073] In Example 4, Sample 1 is first heated at 160° C. during 90 minutes under 300 mbar is absence of any chemical or solvent. Moderate mechanical agitation is applied. After the heating the Sample 1 has been cooled to 85° C., washed with 3% water and centrifuged at 2000 G for 10 minutes. After water washing, the Sample 1 has been further degummed with an aqueous solution of citric acid and bleached with 2% of bleaching earth. Results are shown in Table 5.

TABLE-US-00005 TABLE 5 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) Water washing after  67.9% (109 ppm)  55.8% (373 ppm) heat treatment Degumming 81.8% (63 ppm) 96.2% (32 ppm) Bleaching 91.9% (28 ppm) 97.9% (18 ppm)

[0074] The comparison of Table 1 and Table 5 shows clearly that a thermal treatment improves greatly, and most surprisingly, the efficiency of standard treatment such as water washing, degumming and bleaching for what P and metal removal concerns. After the thermal treatment of the Sample 1, the removal of phosphorus by the degumming operation increased from 67% to 81.8% and the removal of the metal increases from 95.6% to 96.2%. Improvement of the removal of the same magnitude is also observed for the bleaching operation. The improvement of the removal rate of phosphorus is much more marked than the improvement of the removal efficiency of the metals. The reason of this improvement is unknown. It is possible that the thermal treatment modifies the phosphorus-containing impurities and make them more water soluble or accessible to the reactants used in the various subsequent purification steps. The metals sensitivity to the standard purification steps seem less modified by the thermal treatments.

Example 5

[0075] In Example 5, 600 g of Sample 1 was heated in a Rotary Vapor Unit at 180° C. for 120 minutes at 300 mbar in absence of any chemical reactant and/or solvent. Rotation of the vessel containing the crude technical fat was 60 RPM. After the heat treatment, the Sample 1 was cooled to 85° C. and acid degummed with 3.5 kg/ton citric acid, 0.43 kg /ton NaOH (both HSM with Ultraturax) and 2% total water, maturated for 20 min and then centrifuged at 2000×G for 10 min. Degummed Sample 1 was double bleached with the bleaching earth Clariant 9192 (ABE) in the same condition than in Example 4 (but realized two times). Thus, Example 5 is similar to Example 4, but the later is realized with a more intense thermal treatment and without water washing.

[0076] Results shown in Table 6 indicates that a more intense thermal treatment of the glyceridic material induces an even better removal of the impurities by the post standard purifications steps. Removal rates are higher after the degumming and after the first bleaching even if no water washing has been realized.

TABLE-US-00006 TABLE 6 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) Degumming 94.4% (19 ppm)   98.1% (16 ppm) (including washing) after heat treatment First Bleaching 98.0% (6.8 ppm) 99.2% (7 ppm) Second Bleaching 99.0% (3.3 ppm) 99.3% (6 ppm)

Example 6

[0077] Example 6 is similar to Example 5 but the Sample 1 has been thermally treated under 50 mbar instead of under 300 mbar as in Example 5. Temperature and duration and agitation were the same. Purifications steps were the same but only one bleaching has been realized. Results shown in Table 7 indicate that lower pressure during the thermal treatment of the technical fat brings no benefit for the removal of the impurities. Nevertheless, the thermal treatment per se is still improving the removal of the impurities compared to a similar purification procedure including no thermal treatment.

TABLE-US-00007 TABLE 7 Cumulative P Cumulative Metal Purification Removal [%] Removal [%] operations (remaining P [ppm]) (remaining Metal [ppm]) Degumming 89.1% (38 ppm) 95.9% (14 ppm) Bleaching 95.9% (14 ppm) 98.8% (10 ppm)

Example 7

[0078] Example 7 aims at the comparison of two degumming acids combined to initial thermal treatment. Sample 1 has been preheated at 180° C. during 120 minutes under 700 mbar and then degummed with citric acid or with phosphoric acid. Except the nature of the acid used in during the degumming, the other conditions were similar. Results are shown in Table 8. From Table 8, it can be observed that the removal of phosphorus is identical for the two acids, but metal ions are much more efficiently removed with citric acid. It is supposed that the chelating effect of citric acid is conductive to higher removal efficiency. It is unknown why this chelating effect does not operate on phosphorus. However, Example 7 clearly shows that citric acid is preferably used in all degumming operation and water washing in acidic conditions.

TABLE-US-00008 TABLE 8 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Degumming with 94.9% 98.3% Citric Acid Degumming with 94.9% 69.3% Phosphoric Acid

Example 8

[0079] In Example 8, Sample 1 has been treated and purified in the same condition that in Example 5 but 3% of water was added to the glyceridic material during the thermal treatment and the heating has been realised in a closed reactor (PARR) under mechanical agitation (60 RPM) and in adiabatic conditions corresponding to a pressure of 4.6 bar. Results show that addition of water brings no benefit to the purification of the glyceridic material. However, the FFA concentration of the glyceridic material increased from 28% to 34% during the thermal treatment in presence of added water. Since it is preferred not to increase the FFA content during any purification treatment water is preferably not mixed with the glyceridic material during the thermal treatment. As a matter of fact, best purification performances of standard purification methods have been observed when no chemicals and/or no solvent and/or no water are mixed with the low-quality glyceridic material during its thermal treatment prior to said standard purification methods. It must be mentioned that in all the other experiments, the thermal treatment has been realized in absence of water (and in absence of any solvent or added chemical). In those conditions, the amount of FFA initially present in the low-quality glyceridic material did not increased much. A moderate increase of the FFA concentration of 1 to 2% has been observed when the thermal treatment is realised at higher temperature (260° C.). At such high temperature even trace of water will induce hydrolysis of glyceridic material. As a matter of fact, no thermal treatment has induced a decrease of the FFA concentration in the thermally treated low-quality glyceridic feedstock.

Example 9

[0080] In Example 9, the influence of a washing with acidified water before the thermal treatment of the glyceridic material has been investigated. After this initial washing and subsequent centrifugation realized on Sample 2, thermal treatment was done at 180° C. during 120 minutes under 700 mbar, again without added chemicals, solvent or water. Subsequently, the obtained thermally treated sample has been split in two batches. The first batch was degummed under standard conditions and then bleached with bleaching earths. The second batch was treated according to the same procedure, but with a slightly modified degumming. Table 9 and Table 10 show the obtained results for the standard degumming and for the slightly modified degumming procedure respectively. In the standard degumming procedure, the oil is washed with an alkalinized water solution after the degumming operation per se. In the slightly modified degumming procedure, the oil is washed with pure water. This slightly modified procedure is thus simpler and more economical since no base is needed. It is understood that such modification of the degumming procedure is totally usual in the refining of edible oil. Indeed, this type of water washing is realised for oil requiring only a water degumming or when the following bleaching is realized with acid activated bleaching earth. Indeed, in that case some remaining acidy in the oil after the degumming step is not problematic at all.

[0081] Table 9 and Table 10 indicate that the concept of the pre-washing of the low-quality glyceridic material prior to the thermal treatment is beneficial for the removal of the impurities. Indeed, removal efficiency is quite close to 100% after the second bleaching. Skipping the caustic neutralisation after the acid degumming seems also beneficial for both the removal of phosphorus and the ions metals.

TABLE-US-00009 TABLE 9 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Initial washing 43.3 61.9 Heat treatment — — Degumming (standard) 93.2 96.9 First Bleaching 95.8 99.3 Second Bleaching 97.7 99.5

TABLE-US-00010 TABLE 10 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Initial washing 43.3 61.9 Heat treatment — — Degumming (including 93.2 99.1 water wash instead of alkalinized water wash as in standard degumming) First Bleaching 96.7 99.3 Second Bleaching 98.3 99.7

Example 10

[0082] In Example 10, the influence of citric acid wash (1% in water, 90° C.) before the heat treatment realized on Sample 3. Metals are particularly efficiently removed. However, such citric acid wash does not induce a marked improvement of the phosphorus removal. Table 11 shows the obtained results.

TABLE-US-00011 TABLE 11 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Initial acid  3.7% 11.7% washing Heat treatment — — Degumming 88.6% 99.5% (water washing) First Beaching 92.7% 99.3% Second Bleaching 95.1% 99.5%

Example 11

[0083] In Example 11, the effects of thermal treatment realised at higher temperature (260° C.) is investigated. After the thermal treatment, the heated low-quality glyceridic material is split in two fractions. The first fraction has been washed with water acidified with 2% of citric acid (“CA washing) and the second fraction has been washed with a water acidified with 2% of sulfuric acid It is observed a significant improvement of the removal rate given by simple CA washing after a thermal pre-treatment at 260° C. during 20 minutes at adiabatic pressure in a closed PARR reactor. Washing with sulfuric acid give slightly different results but still very good after the washing step per se and very good after the bleaching with ABE and a second bleaching with Trisyl. As a matter of fact, removal efficiency is close to 100%. Sulfuric acid is probably more advantageous for the purification of low-quality glyceridic material as this one is considerably less expensive than citric acid. Table 12 and Table 13 show the obtained results.

TABLE-US-00012 TABLE 12 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Thermal treatment — — (260° C.) Washing (water with 97.7% 99.2% 2% CA) Bleaching ABE 2% 99.3% 99.2% Silica Trisil 0.5%  99.35% 99.6%

TABLE-US-00013 TABLE 13 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Thermal treatment — — (260° C.) Washing (water with — 99.1% 2% sulfuric acid) Bleaching ABE 2% 99.1% 99.5% Silica Trisyl 0.5% 99.2% 99.7%

Example 12

[0084] In Example 12, the influence of an acid washing (2% acid water solution) done before heat treatment has been investigated. It seems the that acid washing realized before a thermal treatment is less efficient as compared to results of Example 11. Removal efficiency of the metal is approaching 100% but the satisfactory removal of the phosphorus cannot be obtained with this purification procedure. Table 14 shows the obtained results.

TABLE-US-00014 TABLE 14 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Washing with 45.3% 73.6% CA solution Thermal treatment — — 260° C. Water washing 92.3% 72.5% Or washing with 97.2% 95.7% CA solution Or washing with sulfuric 92.3% 99.3% acid (SA) solution

Example 13

[0085] In Example 13, the influence of a washing with aqueous solution of sulfuric acid prior the thermal treatment is investigated. The conclusions are similar to the ones of Example 12. Table 15 shows the obtained results.

TABLE-US-00015 TABLE 15 Purification Cumulative P Cumulative Metal operations Removal [%] Removal [%] Washing with 51.6% 86.8% SA solution Thermal treatment — — 260° C. Water washing 92.2% 89.9% Or washing with 87.8% 99.4% SA solution

[0086] While embodiments of the disclosed technology have been described, it should be understood that the present disclosure is not so limited and modifications may be made without departing from the disclosed technology. The scope of the disclosed technology is defined by the appended claims, and all devices, processes, and methods that come within the meaning of the claims, either literally or by equivalence, are intended to be embraced therein.