PROCESSES OF PRODUCING BIODIESEL AND BIODIESEL PRODUCED THEREFROM

Abstract

The present disclosure discloses processes for treating, producing, or producing and treating biodiesel. Products produced with the various processes of the present invention are also disclosed.

Claims

1. A process for treating biodiesel comprising: placing biodiesel in contact with an organic solvent nanofiltration membrane capable of removing steryl glycosides from the biodiesel, wherein the biodiesel passes through the membrane.

2. The process of claim 1, wherein the biodiesel contains a smaller amount of steryl glycosides after being placed in contact with the membrane than before being placed in contact with the membrane.

3. The process of claim 1 or claim 2, wherein before contacting the membrane, the biodiesel has not been subjected to a processing step selected from the group consisting of allowing the temperature to decrease below 40 degrees C., chilling to below ambient temperature, contacting the biodiesel with filter aid, holding the chilled biodiesel and filtering the biodiesel through a leaf filter.

4. The process of claim 1, wherein after contact with the membrane, the biodiesel passes at least one of the ASTM D7501 cold soak filterability or the Canadian standard method CGSB-3.0 No. 142.0 cold soak filter blocking tendency test.

5. The process of claim 1, wherein after contact with the OSN membrane, the biodiesel has an ASTM D7501 cold soak filterability test time of less than 90 seconds.

6. The process of any one of claims 1-5, wherein the temperature of the biodiesel while being placed in contact with the organic solvent nanofiltration membrane is in the range of from 40 to 120 degrees C.

7. The process of claim 1, wherein, after being placed in contact with the membrane the biodiesel contains a smaller amount of one or more impurity selected from the group consisting of water, phosphorus, sulfur, free fatty acids, chlorophyll, monoglycerides, diglycerides, and triglycerides, than before being placed in contact with the membrane.

8. The process of claim 7, wherein the amount of any one of phosphorus, sulfur, diglycerides or monoglycerides in the biodiesel after being placed in contact with the membrane is less than half the amount of the impurity in the biodiesel before being placed in contact with the membrane.

9. The process of claim 1, wherein at least one of the Lovibond red value or the Lovibond yellow value of the biodiesel is lower after being placed in contact with the membrane.

10. The process of claim 9, wherein after being placed in contact with the membrane the Lovibond red value of the biodiesel is not greater than 2.0 or the Lovibond yellow value of the biodiesel is not greater than 35, as determined in a one inch Lovibond cell.

11. The process of claim 1, wherein biodiesel comprises fatty acids derived from the group consisting of vegetable oil, canola oil, safflower oil, sunflower oil, nasturtium seed oil, mustard seed oil, olive oil, sesame oil, soybean oil, corn oil, peanut oil, cottonseed oil, rice bran oil, babassu nut oil, castor oil, palm oil, palm kernel oil, rapeseed oil, low erucic acid rapeseed oil, palm kernel oil, lupin oil, jatropha oil, coconut oil, flaxseed oil, evening primrose oil, jojoba oil, tallow, beef tallow, butter, chicken fat, lard, dairy butterfat, shea butter, biodiesel, used frying oil, oil miscella, used cooking oil, yellow trap grease, hydrogenated oils, gums, soapstock, acid oil, derivatives of the oils, fractions of the oils, conjugated derivatives of the oils, and mixtures of any thereof.

12. A composition produced by the process of claim 1, wherein the composition has a detectable spectrophotometric transmittance.

13. The composition of claim 11, wherein the spectrophotometric transmittance of the biodiesel after being placed in contact with the membrane is greater than 20%.

14. A product produced by the process of any one of claims 1-11.

15. A process for producing biodiesel, comprising: mixing a fatty acid containing material with an alcohol, thus producing a biodiesel precursor mixture; subjecting the biodiesel precursor mixture to a condition selected from the group consisting of time, an increased temperature, an increased pressure, the presence of a catalyst, and any combination thereof, thus producing a mixture of biodiesel and methanol; removing methanol and glycerol to obtain the biodiesel; and passing the biodiesel through an organic solvent nanofiltration membrane at a temperature of less than 125 C.; wherein steryl glycosides are removed from the biodiesel.

Description

DETAILED DESCRIPTION OF EMBODIMENTS

[0037] One method for predicting the behavior of biodiesel under cold conditions is to determine the Cold Soak Filterability, as indicated by the ASTM D7501 method, as summarized above.

[0038] An alternative method of testing biodiesel is the Canadian Standard Method C**/CGSB-3.0 No. 142.0, Cold Soak Filter Blocking Tendency of Biodiesel (B100), also as summarized above. As previously noted. minor components of some biodiesel esters, including saturated monoglycerides and steryl glycosides, can separate above the cloud point of a biodiesel fuel blend. The CSFBT test assesses the propensity of these materials to separate from a blend of biodiesel and isoparaffinic solvent after a cold soak cycle, yielding a dimensionless value indicative of the relative tendency of a given biodiesel fuel to plug or block a filter, based on the relative pressure increase across a filter observed in filtering different biodiesels or on the volumes filtered of various biodiesels once a limiting pressure drop has been reached.

[0039] What is meant by chilling is the process of reducing the temperature of biodiesel to below ambient. What is meant by unchilled is that the biodiesel has not been subjected to the usual industrial practice of chilling to 10 degrees C. and holding to allow precipitates to form.

[0040] We have developed methods using a so-called organic solvent nanofiltration membrane to remove steryl glycosides from unchilled, unfiltered biodiesel, that is, directly after the vacuum stripper. This enables the avoidance of the chilling, holding, addition of filter aid, the use of leaf filters, the loss of biodiesel trapped in the spent filter aid, and the expense of disposal of the filter aid. In addition, we developed methods to remove water, phosphorus, sulfur, free fatty acids, monoglycerides, diglycerides, and triglycerides as well as substantially clarify the biodiesel using an OSN membrane, as well as improve the Cold Soak Filter Blocking Tendency and lower the Filter Blocking Tendency of the biodiesel. The improved biodiesel has a decreased amount of steryl glycosides and may be of greater clarity (higher in transmittance) and may be lower in one or more of water, phosphorus, sulfur, free fatty acids, chlorophyll and other color-imparting impurities, monoglycerides, diglycerides, and/or triglycerides than untreated biodiesel.

[0041] Petroleum diesel fuel often must undergo a desulfurization process to reduce the content of sulfur. This is carried out by hydrogenation or hydrodeoxygenation, requiring expensive equipment and high temperatures. We have developed a method using an organic solvent nanofiltration membrane for the desulfurization of diesel fuel; the method obviates the expensive equipment and high temperatures normally needed for petroleum diesel fuel desulfurization.

[0042] The invention is further explained by use of the following illustrative examples.

Example 1

[0043] A flat sheet non-polar organic solvent nanofiltration (OSN) membrane (PMS-600 PuraMem membrane, Evonik Industries, Chicago, Ill., USA, molecular weight cut off nominally 600, membrane area 0.0062 m.sup.2) was secured into a flat sheet membrane holder. Toluene was passed through the membrane to remove the preservative, then the toluene was flushed out with biodiesel.

[0044] Unfiltered canola biodiesel (fatty acid methyl esters, Archer Daniels Midland Co., Velva, N. Dak., USA) was obtained. The biodiesel had been subjected to vacuum stripping at 120 degrees C., but had not been treated by the usual chilling to 10 degrees C. and filtering with filter aid in a leaf filter as carried out in commercial biodiesel production to reduce the content of steryl glycosides in the biodiesel. A closed system was pressurized with nitrogen (20 bar) on the upper side of the membrane to provide cross-membrane driving force. Unchilled, unfiltered biodiesel at 22 degrees C. containing 55.80 mg/kg steryl glycosides (measured by gas chromatography after derivatization) was purified by passing the biodiesel through the membrane. In 1.5 hours, 50 mL of purified biodiesel permeate containing 5.25 mg/kg steryl glycosides was obtained. Thus, a 91% reduction of steryl glycosides was obtained without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

Example 2

[0045] Unchilled, unfiltered canola biodiesel (438.50 grams, ADM, Velva, N. Dak., USA) containing 32.15 mg/kg steryl glycosides was hydrated by adding water (1.05 grams) and stirred for 30 minutes, yielding biodiesel containing 0.3% water. This was passed through the organic solvent nanofiltration membrane substantially according to Example 1 except the pressure was raised to 27 bar to yield 100 grams of purified diesel. After the addition of water, the level of steryl glycosides in the OSN filtered biodiesel was below detection limits (<2 mg/kg), without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid. Thus instead of chilling and filtering, steryl glycoside removal was carried out by simply adding a trace of water and passing the unfiltered biodiesel through an OSN filtration membrane.

Example 3

[0046] Unchilled, unfiltered canola biodiesel (ADM, Velva, N. Dak., USA) containing 19.64 mg/kg sterol glycosides, 0.34% monoacylglycerols and 0.09% diacylglycerols was passed through a flat sheet organic solvent nanofiltration membrane (PMF flux, Evonik Industries) having a nominal molecular weight cutoff of 500 in substantially the same arrangement as in Example 1 except the pressure applied was 26 bar. Permeate (35 ml) was collected in 1.5 hours and tested (Table 1).

TABLE-US-00001 TABLE 1 Rejection by Feed Permeate membrane (%) Sterol glycosides 19.64 mg/kg 0 mg/kg 100 Monoacylglycerols 0.34% 0.27% 21 Diacylglycerols 0.09% 0.04% 56

[0047] The Evonik PMF flux membrane was able to produce biodiesel with undetectable sterol glycoside levels while substantially reducing the content of monoacylglycerols and diacylglycerols without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

Example 4

[0048] Unchilled, unfiltered canola biodiesel (ADM, Velva, N. Dak., USA) containing 5.78 mg/kg sterol glycosides, 0.34% monoacylglycerols and 0.11% diacylglycerols was hydrated by adding 2.05 grams of water to 345.92 grams of biodiesel to produce biodiesel containing 0.59% water. This was passed through the flat sheet PMF flux membrane substantially as described in Example 3. Permeate (35 ml) was collected in 1.5 hours and tested (Table 2).

TABLE-US-00002 TABLE 2 Rejection by Feed Permeate membrane (%) Sterol glycosides 5.78 mg/kg 0 mg/kg 100 Monoacylglycerols 0.34% 0.28% 18 Diacylglycerols 0.11% 0.03% 73

[0049] The flat sheet organic solvent nanofiltration membrane was very effective at removing steryl glycosides and diacylglycerols from hydrated biodiesel, and was able to reduce the content of monoglycerides without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

Example 5

[0050] Unchilled, unfiltered biodiesel was placed into an agitated feed vessel, circulated through a heater set at 45 degrees C. and passed through a spiral wound OSN membrane (Evonik PuraMem Flux membrane, surface area: 0.12 square meters, one inch diameter) at 20.7 bar (300 psi) pressure. The flux was 15.8-17.4 liters/meter.sup.2/hour. Biodiesel passed through the membrane as permeate and steryl glycosides were retained. The retentate, containing biodiesel enriched in steryl glycosides, was recirculated to the feed vessel so that the concentration of steryl glycosides in the biodiesel feed increased. The level of steryl glycosides in the feed and the purified permeate was determined at three times as the concentration of steryl glycosides increased (Table 3).

TABLE-US-00003 TABLE 3 Steryl glycosides in unchilled, unfiltered canola biodiesel as recirculation of feed was carried out. Rejection by Lot Feed (mg/kg) Permeate (mg/kg) membrane (%) 1 47.39 3.54 93.53% 2 53.95 4.61 91.46% 3 64.30 5.01 92.21%

[0051] Even as the concentration of steryl glycosides increased in the feed, the rejection of steryl glycosides by the membrane remained high. The content of steryl glycosides in the unchilled, unfiltered biodiesel was decreased by greater than 90% after permeating through the spiral wound membrane.

Example 6

[0052] The removal of additional impurities from unchilled, unfiltered biodiesel was tested. Biodiesel was passed through the spiral wound membrane substantially as in Example 5 and the permeate, treated biodiesel tested for impurities. The results are shown in Table 4.

TABLE-US-00004 TABLE 4 Removal of impurities from biodiesel after permeating through the membrane. Concentration Concentration in in treated Rejection by Component raw biodiesel biodiesel OSN (%) Phosphorus (mg/kg) 1.05 0.44 57.9 Sulfur (mg/kg) 1.71 0.87 49.2 Free fatty acids (%) 0.18 0.13 26.5 Monoglycerides (%) 0.48 0.32 34.1 Diglycerides (%) 0.28 0.06 78.7 Triglycerides (%) 1.40 0.15 89.2 Chlorophyll (ppm) 3.407 0.008 99.8

[0053] Significant removal of all measured impurities was achieved, with about half or more of the phosphorus, sulfur, diglycerides, and triglycerides being removed from the unchilled, unfiltered biodiesel.

Example 7

[0054] The progress in the concentration of biodiesel after permeating through the membrane was determined. The unchilled, unfiltered biodiesel from Example 6 was heated to 45 degrees C. and passed through the spiral wound Evonik PuraMem Flux OSN membrane at 20.68 bar pressure substantially as outlined in Example 5. The biodiesel was purified as it passed through the membrane and the rate of permeate flux was measured. The retentate was recirculated back to the feed vessel. The permeate flux was measured and a factor known as the Volume Concentration Factor was calculated. In this equation, V.sub.o is a constant that represents the starting volume of unchilled, unfiltered biodiesel, and V.sub.c is an ever-decreasing number representing the volume of retentate remaining as the biodiesel passes into the permeate. The volume Concentration Factor was obtained by dividing V.sub.o by V.sub.c. The Biodiesel recovery represents the percentage of the starting volume (V.sub.o) that was obtained as permeate through the spiral wound membrane (Table 5).

TABLE-US-00005 TABLE 5 Flux rate, Volume Concentration Factor, and Biodiesel recovery obtained when recirculating biodiesel through the spiral wound membrane. Biodiesel temperature: 45 degrees C.; pressure: 20.68 bar. Permeate Volume Biodiesel flux rate concentration recovery Sample (liter/m.sup.2-hour) factor (%) 1 17.4 1.10 8.7 2 16.6 1.35 26.1 3 16.8 1.77 43.5 4 16.3 3.29 69.6 5 16.0 7.67 87.0 6 15.8 23.0 95.7

[0055] The permeate flux rate decreased only slightly during the 5-hour test. The Volume Concentration Factor of the recycling biodiesel retentate was 23.0, and 95.7% of the initial volume of biodiesel was recovered as membrane-purified biodiesel without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

Example 8

[0056] Two important operational characteristics of biodiesel, the Cold Soak Filterability and the Cold Soak Filter Blocking Tendency, were determined after permeating unchilled unfiltered canola biodiesel through the spiral wound OSN membrane substantially as described in Example 6. The cold soak filterability was determined according to ASTM D7501 (Table 6). The Cold Soak Filter Blocking Tendency was tested according to Canadian Standard Method CGSB-3.0 No. 142.0, Cold Soak Filter Blocking Tendency of Biodiesel (B100). The biodiesel was heated to 60 degrees C. for three hours prior to the Cold Soak Filter Blocking Tendency (CSFBT) test.

TABLE-US-00006 TABLE 6 Quality test Required OSN treated biodiesel Cold soak No more than 360 seconds 89 seconds Filterability Cold Soak Filter No greater than 1.41 1.05 Blocking Tendency

[0057] The biodiesel obtained by passing unchilled, unfiltered biodiesel through the OSN membrane passed both the Cold Soak Filterability test and the Cold Soak Filter Blocking Tendency test, without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

Example 9

[0058] Color removal from biodiesel from Example 6 was tested. Unchilled, unfiltered canola biodiesel (ADM, Velva, N. Dak., USA) was dark and hazy, and when tested in a spectrophotometer no detectable transmittance could be measured. After the unchilled, unfiltered canola biodiesel passed through the spiral wound membrane, a significant improvement in clarity was noted. The appearance of the biodiesel was bright and clear, similar to edible quality vegetable oil. The spectrophotometer test was repeated on the filtered biodiesel. The transmittance was 38.5%, exhibiting a substantial improvement in clarity of the oil.

[0059] The Lovibond Red and Lovibond Yellow values of the unchilled, unfiltered biodiesel were determined in a Lovibond colorimeter using a one inch Lovibond cell according to method AOCS Method Cc 13b-45. Before passing through the OSN membrane, the Lovibond Red value was 3.1 and the Lovibond Yellow value was 70. After passing through the OSN membrane, the Lovibond Red value was 0.5 and the Lovibond Yellow value was 13, illustrating the significant decrease in the color of the biodiesel without chilling the biodiesel to below ambient temperature and without contacting the biodiesel with filter aid.

[0060] The exemplary embodiments described herein are not intended to limit the invention or the scope of the appended claims. Various combinations and modifications of the embodiments described herein may be made without departing from the scope of the present disclosure and all modifications are meant to be included within the scope of the present disclosure. For instance, the various embodiments of the biodiesel treatments described herein may be used in conjunction with other embodiments of the biodiesel processing activities described herein. Further, the biodiesel treatment activities described herein may be implemented by modifying existing biodiesel processing systems and used in conjunction with existing biodiesel processing equipment.