Processes of Producing Biodiesel and Biodiesel Produced Therefrom
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.
This application claims the benefit of U.S. Provisional Application No. 60/754,979, filed Dec. 29, 2005, and provisional U.S. patent application 60/831,575, filed Jul. 17, 2006, each of the contents of the entirety of which are incorporated by this reference.
TECHNICAL FIELDThe present disclosure relates generally to biodiesel and processes for producing biodiesel.
BACKGROUNDBiodiesel is manufactured from animal or vegetable oils. The preferred feedstock for producing biodiesel in Europe is rapeseed (i.e., canola) oil. In North America, some canola oil is used to produce biodiesel, but soybean oil is also used as a feedstock in producing biodiesel. Biodiesel is used as an additive to petroleum-derived diesel fuel or as a substitute for petroleum-derived diesel fuel in diesel (compression-ignition) engines. Biodiesel usually comprises fatty acid methyl esters (FAME) or fatty acid ethyl esters.
The use of biodiesel in cold climates may require special considerations due to the tendency of precipitates to form in the biodiesel at temperatures of 0° C. and below. These precipitates impair the flow characteristics of biodiesel.
SUMMARY OF THE INVENTIONThe present invention discloses processes for producing biodiesel as well as biodiesel produced therefrom.
In one embodiment, a process for treating biodiesel comprises placing biodiesel in contact with a compound capable of removing steryl glycosides from the biodiesel.
In another embodiment, a process for treating biodiesel comprises placing biodiesel in contact with a compound capable of removing monoacylglycerols from the biodiesel.
In another embodiment, a process for treating biodiesel comprises reducing the filter blocking tendency of the biodiesel.
In another embodiment, a process for removing steryl glycosides from a fatty acid methyl ester containing material comprises placing a compound selected from the group consisting of adsorbents, filter aids, boric acid, soap, sucrose, sugar, glucose, carbon, activated carbon, cellulose, sodium chloride, citric acid, magnesium silicate, clay, diatomaceous earth, lecithin, granular clay, granular glucose, granular sugar, protein, textured vegetable protein, solutions of boric acid, silica hydrogel, and combinations of any thereof in contact with a fatty acid containing material, and separating the compound from the fatty acid containing material.
In another embodiment, a process for removing monoacylglycerols from a fatty acid methyl ester containing material or biodiesel comprises placing a compound selected from the group consisting of magnesium silicate, steryl glycosides, and a combination thereof in contact with the fatty acid methyl ester containing material or the biodiesel.
In another embodiment, the biodiesel is separated from the compounds capable of removing monoacylglycerols from the biodiesel. In an embodiment, the compound is separated from the fatty acid containing material by a process selected from the group consisting of filtration, centrifugation, and combinations of any thereof.
In another embodiment, the biodiesel separated from the compounds capable of removing monoacylglycerols from the biodiesel is mixed with a petroleum based diesel fuel, a biodiesel not placed in contact with the compound capable of removing the monoacylglycerols, ethanol, or any combinations thereof.
In an additional embodiment, a process for reducing the filter blocking tendency of biodiesel includes placing the biodiesel in contact with a solid or liquid, wherein the solid or liquid comprises a compound capable of reducing the filter blocking tendency of biodiesel.
In yet a further embodiment, a process for producing biodiesel includes mixing a fatty acid containing material and an alcohol, thus producing a biodiesel precursor mixture. The biodiesel precursor mixture is subjected to a condition that allows biodiesel to form, wherein the condition is selected from the group consisting of time, an increased temperature, an increased pressure, the presence of a catalyst and any combination thereof. The process further includes isolating the biodiesel and removing steryl glycosides from the biodiesel, wherein the steryl glycosides are removed from the biodiesel at a temperature of less than 125° C.
In yet a further embodiment, a process for producing biodiesel includes mixing a fatty acid containing material and an alcohol, thus producing a biodiesel precursor mixture. The biodiesel precursor mixture is subjected to a condition that allows biodiesel to form, wherein the condition is selected from the group consisting of time, an increased temperature, an increased pressure, the presence of a catalyst and any combination thereof. The process further includes isolating the biodiesel and removing monoacylglycerols from the biodiesel, wherein the monoacylglycerols are removed from the biodiesel at a temperature of less than 125° C. In an embodiment, the biodiesel is of soy origin.
In yet another embodiment, a biodiesel production plant comprises a compound capable of removing steryl glycosides from the biodiesel, and a conduit operably configured to place biodiesel in contact with the compound capable of removing steryl glycosides from the biodiesel.
In yet another embodiment, a biodiesel production plant comprises a compound capable of removing monoacylglycerols from the biodiesel, and a conduit operably configured to place biodiesel in contact with the compound capable of removing steryl monoacylglycerols from the biodiesel.
In another embodiment, an apparatus configured to treat biodiesel includes a reservoir for containing a biodiesel having an initial filter blocking tendency value, a compound capable of removing steryl glycosides from the biodiesel, and a conduit operatively configured to place the biodiesel in contact with the compound capable of removing steryl glycosides from the biodiesel.
In another embodiment, an apparatus configured to treat biodiesel includes a reservoir for containing a biodiesel having an initial filter blocking tendency value, a compound capable of removing monoacylglycerols from the biodiesel, and a conduit operatively configured to place the biodiesel in contact with the compound capable of removing monoacylglycerols from the biodiesel.
In a further embodiment, a process for preparing a composition enriched in steryl glycosides includes filtering a steryl glycoside containing composition through a bed of water-soluble solid bed material, and dissolving the water-soluble solid bed material in water to remove the water-soluble solid bed material, wherein a composition enriched in steryl glycosides is obtained.
In one embodiment, a steryl glycoside composition comprising steryl glycosides or a biodiesel origin is disclosed.
In a further embodiment, a biodiesel includes a detectable level of steryl glycosides, wherein a level of steryl glycosides in the biodiesel is less than 70 ppm.
In still a further embodiment, a biodiesel comprises a detectable level of steryl glycosides, monoacylglycerols, diacylglycerols, triacylglycerols, or any combinations thereof, wherein the biodiesel passes a filter blocking test. The filter blocking test includes determining whether a pre-selected volume of the product passes through a filter before a pre-selected pressure is placed on the filter from the product. When the pre-selected volume of the product passes through the filter before the pre-selected pressure is reached, the biodiesel passes the filter blocking test. When the pre-selected pressure is reached before the pre-selected volume of the product passes through the filter, the biodiesel fails the filter blocking test.
In another embodiment, a biodiesel comprises a detectable level of steryl glycosides, monoacylglycerols, diacylglycerols, triacylglycerols, or any combination thereof, and passes a filter blocking test. The filter blocking test comprises: adjusting a temperature of a sample of the biodiesel to 15 to 25 degrees Celsius; shaking the sample for 120 seconds; allowing the sample to stand on a vibration-free surface for 300 seconds; placing 320 milliliters of the sample into a fuel reservoir beaker of a Normalab Analis NBF 240 instrument; ensuring that the temperature of the sample is maintained at the 15 to 25 degrees Celsius; placing a pump suction pipe of the Normalab Analis NBF 240 instrument into the fuel reservoir beaker; operating a pump of the Normalab Analis NBF 240 instrument until biodiesel flows into a collection beaker; pouring any fuel from the collection beaker into the fuel reservoir beaker; placing a fresh filter on a filter unit of the Normalab Analis NBF 240 instrument; attaching the assembled filter unit to the Normalab Analis NBF 240 instrument with a Luer fitting; starting the pump of the Normalab Analis NBF 240 instrument; reading a pressure gauge after 20 seconds; and pumping the sample at a flow rate of 20 ml/minute until 300 milliliters have passed through the filter or until the pressure gauge reaches 105 kPa. The biodiesel passes the filter blocking test when 300 milliliters of the sample passes through the filter before 105 kPa is reached, and fails the filter blocking test when 105 kPa is reached before 300 milliliters of the sample passes through the sample.
In another embodiment, a biodiesel comprises a detectable level of steryl glycosides, monoacylglycerols, diacylglycerols, triacylglycerols, or combinations of any thereof, and passes a filter blocking test. The filter blocking test comprises: filtering 30 milliliters of biodiesel through a 1.6 um GF/A filter having 47 mm diameter under a 21-25 inch Hg vacuum. The biodiesel passes the filter blocking test when the entire sample of 300 ml passes through the filter in 6 minutes or less.
In a further exemplary embodiment, a process for treating biodiesel comprises placing biodiesel in contact with a compound selected from the group consisting of adsorbents, filter aids, boric acid, soap, sucrose, sugar, glucose, carbon, activated carbon, cellulose, sodium chloride, citric acid, magnesium silicate, clay, diatomaceous earth, lecithin, granular clay, granular glucose, granular sugar, protein, textured vegetable protein, steryl glycosides, and combinations of any thereof, and separating the biodiesel from the compound.
In another embodiment, the fatty acid containing material from which steryl glycosides, monoacylglycerols, or combinations thereof are separated is selected 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, lupin oil, jatropha oil, coconut oil, flaxseed oil, evening primrose oil, jojoba oil, camelina 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, derivatives of the oils, fractions of the oils, conjugated derivatives of the oils, and mixtures of any thereof.
In an embodiment, biodiesel is mixed with a solid or liquid capable of improving the cold test results of a biodiesel. In an embodiment, the solid or liquid is mixed with the biodiesel at a first temperature and the solid or liquid is separated from the biodiesel; the biodiesel is adjusted to have a second temperature, and the biodiesel is subjected to a cold test.
In a further embodiment, biodiesel is incubated at a first temperature, filtered through a compound, incubated at a second temperature, and subjected to a filter blocking test. In a further embodiment, the biodiesel is incubated at 40° F., filtered through a compound selected from the group consisting of diatomaceous earth and cellulose, incubated at a second temperature, and subjected to a filter blocking test.
DETAILED DESCRIPTION OF THE INVENTIONBiodiesel comprises ethyl or methyl esters of fatty acids of biological origin. Starting materials for the production of biodiesel include, but are not limited to, materials containing fatty acids. These materials include, without limitation, triacylglycerols, diacylglycerols, monoacylglycerols, phospholipids, esters, free fatty acids or any combinations thereof. The biodiesel is produced by incubating the material including the fatty acids with a short chain alcohol in the presence of heat, pressure, a catalyst or combinations of any thereof to produce fatty acid esters of the short chain alcohols. In industrial practice, biodiesel may undergo a final simple filtration step, such as through a polishing “sock” filter, to remove any remaining fine particulate matter. Such a filter step may comprise a first screen having 10 micron pore size and a second screen of 1 micron pore size. These fatty acid esters of the short chain alcohols may be used as supplements to or replacements for diesel fuel in compression ignition engines.
The fatty acids used to produce the biodiesel may originate from a wide variety of natural sources including, but not limited to, 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 oil, rapeseed oil, low erucic acid rapeseed oil, palm kernel oil, lupin oil, jatropha oil, coconut oil, flaxseed oil, evening primrose oil, jojoba oil, camelina 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, derivatives of the oils, fractions of the oils, conjugated derivatives of the oils, and mixtures of any thereof.
Some components of biodiesel such as, for example, esters of saturated fatty acids may cause the development of crystals when the biodiesel is subjected to cold conditions. For instance, the presence of methyl ester containing saturated fatty acids, monoacylglycerol (monoglyceride) containing saturated fatty acids, diacylglycerol (diglyceride) containing saturated fatty acids (as low as 0.1 wt %), and unsaponifiable matter (at levels of 3%) may cause cold-flow problems in biodiesel. As one example, monoacylglycerols containing saturated fatty acids may form crystals in the biodiesel and may cause flow problems or fuel blockages in biodiesel fuel systems. In another example, a fuel blockage in a biodiesel fuel system may be caused by the cooling of esters of saturated fatty acids in the biodiesel. These fuel blockages may occur when vehicles powered by biodiesel or a blend of diesel and biodiesel are exposed to cold conditions. These problems caused by the crystals or cooled esters of saturated fatty acids may be rectified by heating and, thus, melting the crystallized materials or heating the cooled esters of saturated fatty acids. The heat may be applied by towing the affected vehicle to a warm garage, or applying a heat source such as a heat blower to the fuel lines and systems of the vehicle. Under these conditions, fuel flow is restored when the crystallized material melts, and esters of saturated fatty acids pass into the combustion chamber for burning.
The formation of precipitates at temperatures of 0° C. and below resulted in the development of tests to measure the impact of cold temperatures on biodiesel. For instance, in the USA, the cloud point of the biodiesel is determined with the ASTM method D 2500. In Europe, the cold filter plugging point of biodiesel of heating oil is determined with a test designated EN 116. These tests are used to ensure that the biodiesel falls within the required standards. However, these tests do not account for the presence of precipitates which may form in soy biodiesel without exposure to cold temperatures. These precipitates can cause fuel blockage such as restriction or blockage of fuel filters, which is distinct from the problem of the precipitation of esters of saturated fatty acids caused by exposure to cold.
In one embodiment, the fatty acid containing materials or products used to produce the biodiesel may also be subjected to processes to separate solid material, such as esters of saturated fatty acids, from liquid material, such as esters of unsaturated fatty acids and polyunsaturated fatty acids to remove the solid material and prevent any potential blocking issues.
Biodiesel has been scrutinized because an amorphous cloud-like substance may develop in the biodiesel when stored at room temperature in addition to the flow problems that occur at cold temperatures. This amorphous cloud-like substance may cause clogging of fuel filters. The resulting constriction or stoppage of fuel flow is not related to cold temperatures and requires the frequent changing of filters, which is costly and inconvenient. The amorphous cloud-like substance that is observed at room temperature is not crystallized esters of fatty acids, such as saturated methyl esters or mono-, di-, or triacylglycerols of saturated fatty acids.
In another embodiment, it was surprisingly discovered that the amorphous cloud-like substance included steryl glycosides. These steryl glycosides in biodiesel increase the filter blocking tendency of biodiesel without exposure of the biodiesel to cold temperatures.
In a further embodiment, crystals formed in biodiesel at room temperature were observed under the microscope. The crystals appeared as particles of about 10-15 microns in size. The crystals were associated together in loose, amorphous, gel-like agglomerates of various sizes. After incubating biodiesel containing the crystals with water for a few hours, the morphology of the individual particles and the agglomerates changed, indicating the presence of surface-active material. These crystals were recovered and identified as steryl glycosides. The steryl glycosides include sterol glucosides, steryl glucosides, or sterol glycosides.
The steryl glycoside crystals may also contain fatty acid methyl esters (FAME), which may be entrapped or bound. The presence of steryl glycosides in biodiesel can be detected by the development or presence of a visible opacity or “haze” in the biodiesel at room temperature without a microscope. In another embodiment, it was determined that the amount of haze visible in room-temperature biodiesel (˜25° C.) is related to the tendency of biodiesel to fail a filter blocking test designed to test the flow of fuel at 15-25° C.
The steryl glycosides present in biodiesel comprise a sterol group linked to a carbohydrate at the hydroxyl moiety of the sterol. The steryl glycosides may also contain a fatty acid esterified to a hydroxyl group of the carbohydrate moiety; these compounds may be described as acylated steryl glycosides. It was also found that the ability of the steryl glycosides to increase the filter blocking occurred regardless of the presence of meltable crystals of glycerol esters of saturated fatty acids or the presence of a fatty acid moiety.
Acylated steryl glycosides are naturally occurring compounds found in plants. The acylated steryl glycosides comprise a sterol group bound to a carbohydrate having a fatty acid acylated to the primary hydroxyl group of the carbohydrate moiety of a steryl glycoside. One of the acylated steryl glycosides present in soybean extracts is the 6′-linoleoyl-beta-D-glucoside of beta sitosterol present at about 47%. In plants, other fatty acids or monobasic carboxylic acids, such as palmitic acid, oleic acid, stearic acid, linoleic acid, and linolenic acid may also be acylated to the carbohydrate moiety through an ester bond. The acylated steryl glycosides are two to ten times more abundant in plants than the (non-acylated) steryl glycosides. Steryl glycosides, also known as sterolins, are present as monoglycosides in the oil from which biodiesel is synthesized, although a few diglycosides also exist. A common sugar in steryl glycosides is D-glucose, which is joined to the sterol via the 3-beta-hydroxy group by means of an equatorial or beta-glucoside bond. Other monosaccharides that may be found in steryl glycosides include mannose, galactose, arabinose and xylose.
The amount of steryl glycosides in crude soybean oil is higher than in corn oil or sunflower oil. Crude soy oil may contain about 2300 ppm steryl glycosides, while crude oils from corn and sunflower contain about 500 ppm and 300 ppm, respectively. Steryl glycosides are enriched in gums produced by degumming soy, corn and sunflower oils, and present in concentrations of about 19300 ppm, 5400 ppm, and 16800 ppm, respectively, and can be expected to be similarly enriched in soapstock and acid oils from vegetable oils.
In oil refining, gums resulting from degumming crude oil and soapstock resulting from alkali refining of crude oil or degummed oil are often further processed to recover entrained oil and fatty acids. This process may be carried out by hydrolysis of the gums or soapstock to increase the content of free fatty acids. Hydrolysis may be carried out by the application of steam and alkali or acid. Acid is sometimes used because the acid facilitates separation of a free fatty acid phase from a water-rich phase. The free fatty acid phase is a product called “acid oil”. Acid oil may be used as a feedstock for biodiesel synthesis. The glycosides in gums and soapstock can also be present in the acid oil, so biodiesel made from acid oil can have high levels of steryl glycosides and result in the flow problems described herein.
The steryl glycosides in the biodiesel cause problems for flow of the biodiesel. Even low levels of the steryl glycosides (i.e., 10-90 ppm) in the biodiesel can form aggregates with fatty acid methyl esters that may appear as a visible cloud. These aggregates can accelerate filter plugging at any temperature, not just cold temperatures, due to the high melting point of steryl glycosides (i.e., 240° C.). At room temperatures, the steryl glycosides can aggregate and plug filters used for biodiesel fuel. At cold temperatures, the cold-flow problems caused by alkyl esters of saturated fatty acids such as monoacylglycerols may be compounded by the presence of the steryl glycosides.
The steryl glycosides not only cause problems for flow of the biodiesel, but can also hamper the production of biodiesel. For instance, since biodiesel is often centrifuged as a final polishing step in the manufacture of biodiesel, the centrifuges used for the final purification step can become filled with steryl glycoside-rich solids, resulting in costly process interruptions and shut-downs to clean the centrifuges. In addition, since biodiesel is often subjected to a final polishing filtration step, such as by passage through a sock filter, the sock filters can become filled or blinded (occluded) with steryl glycoside-rich solids, also resulting in costly process interruptions and shut-downs to clean and/or replace the filter material.
The formation of steryl glycoside crystals in the biodiesel may be exacerbated in the presence of trace amounts of water. This is because the steryl glycosides, visible as haze in biodiesel, may grow in volume when the steryl glycosides are placed in contact with water. The grown or expanded steryl glycoside crystals make the crystals even more prone to causing fuel restriction or blockage.
Unlike esters of saturated fatty acids, steryl glycosides cannot be practically removed by melting or exposure to heat since the melting point of steryl glycosides is 240° C. This means that the steryl glycosides cannot be practically heated and melted to allow the steryl glycosides to pass through a filter into a combustion chamber for burning. Further, in the event the steryl glycosides were to reach the fuel injectors of a diesel engine, the steryl glycosides may accumulate and form a refractory gum-like material that would require disassembly and cleaning of the injectors, thus increasing the operating expense of the diesel engine.
Further, since the steryl glycosides are insoluble in most solvents, with the exception of pyridine, dioxane and dimethylformamide, the cleaning of components having accumulated steryl glycosides is problematic. This is because pyridine, dioxane and dimethylformamide are not found in the usual diesel repair facility, and their health hazards make these solvents unsafe for use outside of a fume hood. Consequently, the build-up of the steryl glycosides on diesel engine components would require labor-intense abrasive cleaning or expensive replacement of fuel injectors and other fouled components.
In another embodiment, processes for removing steryl glycosides from biodiesel or oils are disclosed. The steryl glycosides are removed by placing the biodiesel or oil in contact with a compound capable of removing the steryl glycosides from the biodiesel or oil. By removing the steryl glycosides from the biodiesel, the biodiesel has a reduced tendency to have a retarded flow or block filters.
In another embodiment, a biodiesel placed in contact with a compound capable of removing steryl glycosides (i.e., treated biodiesel) has a reduced amount of steryl glycosides as compared to a biodiesel not placed in contact with a compound capable of removing steryl glycosides (i.e., untreated biodiesel). The treated biodiesel also has a reduced filter blocking tendency as compared to the untreated biodiesel. The treated biodiesel may have a FBT value of less than 1.414 as determined by ATSM method D 2068. In an embodiment, the treated biodiesel may pass a modified ASTM D6217 method.
In another embodiment, biodiesel incubated or stored at temperatures below ambient temperature, has a reduced Filter Blocking Tendency, as determined by ASTM method D 2068.
In another embodiment, processes for removing monoacylglycerols from biodiesel or oils are disclosed. The monoacylglycerols are removed by placing the biodiesel or oil in contact with a compound capable of removing the monoacylglycerols from the biodiesel or oil. By removing the monoacylglycerols from the biodiesel, the biodiesel has a reduced tendency to have a retarded flow or block filters when the biodiesel or oil is used in combination with an engine.
In another embodiment, a biodiesel placed in contact with a compound capable of removing monoacylglycerols (i.e., treated biodiesel) has a reduced amount of monoacylglycerols as compared to a biodiesel not placed in contact with a compound capable of removing monoacylglycerols (i.e., untreated biodiesel). The treated biodiesel also has a reduced filter blocking tendency as compared to the untreated biodiesel. The treated biodiesel may have a FBT value of less than 1.414 as determined by ATSM method D 2068. In an embodiment, the treated biodiesel may pass a modified ASTM D6217 method.
Since conventional tests for ascertaining the consequences of cooling biodiesel, such as pour point or cold filter plugging point, are not useful in detecting the presence of steryl glycosides, it was surprisingly found that IP 387 and the ATSM method (D 2068, “Standard Test Method for Filter Blocking Tendency of Distillate Fuel Oils”) provide measurements of filter blocking capabilities in biodiesel that has not been cooled.
The tests for measuring filter blocking capabilities herein described are carried out with a Normalab Analis (Lintot, France) NBF 240 instrument. A sample (that is substantially free of undissolved water) is passed through a specified glass-fiber filter medium at 20 ml/minute. The pressure difference across the filter is monitored, and the volume of fuel passing through the filter medium within a prescribed pressure drop is measured. According to the test, the filter blocking tendency is defined on a linear scale through a discontinuity point of 105 kPa/300 ml. This provides a dimensionless unit which is independent of the point of test cessation. The test ceases when the pressure difference across a specified filter reaches 105 kPa or when 300 ml of biodiesel passes through the filter, whichever is reached first. The results are reported as a volume or pressure at the point of cessation. A sample passes the test if a 300 ml volume can pass through a filter having a 1.6 micron particle retention and 13 mm diameter (such as Millipore Cat. No. XX30 012 00 from Millipore Corp. or Grade GF/A (FBT) from Whatman (Cat. No. 1820 8013)) without developing a pressure equal to or greater than 105 kPa. A sample fails the test if the pressure reaches 105 kPa before 300 ml of biodiesel is passes through the filter.
In this embodiment, filter blocking tendency (FBT) can be described in one of the following ways: the pressure drop across a 1.6 μm pore size glass fiber filter when 300 mL of fuel is passed at a rate of 20 mL/min, or the volume of fuel passed when a pressure of 105 kPa (15 psi) is reached. The latter method is used when less than 300 mL passes at a rate of 20 mL/min before the pressure exceeds 105 kPa. A sample of the fuel to be tested is passed at a constant rate of flow (20 mL/min) through a glass fiber filter medium. The pressure drop across the filter is monitored during the passage of a fixed volume of test fuel. If a prescribed maximum pressure drop is reached before the total volume of fuel is filtered, the actual volume of fuel filtered at the time of maximum pressure drop is recorded.
Before the test, the temperature of biodiesel being sampled is adjusted to about 15 to 25° C. The biodiesel is shaken vigorously for about 120 seconds (plus or minus 5 seconds), and allowed to stand on a vibration-free surface for about 300 seconds. A sample of about 320 mL, plus or minus 5 mL, is placed into the fuel reservoir beaker of the Normalab Analis NBF 240 instrument and the temperature is checked to ensure that it is within the range of about 15 to 25° C. (the actual temperature is recorded). The pump suction pipe of the instrument is placed into the fuel reservoir beaker. The pump is run until biodiesel flows from the fitting to which the filter unit is attached into the collection beaker. The pump is stopped, and any fuel from the collection container is poured back into the fuel reservoir beaker. The filter unit is assembled with a fresh filter, and the assembled filter unit is attached to the instrument through a Luer fitting. The pump and stopwatch are started, and after about 20 seconds, the pressure gauge reading is recorded. If the pressure gauge reading falls in the range of about 7 to 21 kPa, pumping is continued at 20 ml/minute and the pressure gauge is monitored continuously. If the pressure rises to 105 kPa, the pump is stopped immediately and the volume of liquid that passed through the filter at that point is reported as v. If the pressure does not rise to 105 kPa after 300 mL has passed through the filter, the highest pressure reached in the test is reported as P.
Filter blocking tendency (FBT) is calculated using one of the following equations, depending on whether a value was obtained for v or P.
FBT=√1+(P/105)2=(Square root of (1+(P/105)2), or (1+(P/105)2)1/2
FBT=√1+(300/v)2=(Square root of (1+(300/v)2), or (1+(300/v)2)/1/2
P is the maximum pressure reading obtained for 300 mL of biodiesel to pass through the filter, in kilopascals; and V is the volume of fuel passed at a pressure reading of 105 kPa, in milliliters.
FBT is expressed as a dimensionless number to the nearest 0.01. A FBT value close to 1 indicates good flow characteristics, and an FBT value of 1.414 or greater indicates poor flow and indicates that the fuel failed the FBT test. As the minimum test volume is 20 ml, liquids which exceed 105 kPa pressure in 20 ml or less are assigned the greatest FBT value that can be determined (i.e., 15.03).
An alternative method of testing biodiesel is a modified ASTM 6217 test. The modified ASTM 6217 test is carried out as follows: biodiesel (300 ml) is filtered through a 1.6 um GF/A filter having 47 mm diameter under a 21-25 inch Hg vacuum. The entire volume of 300 ml of the biodiesel must pass through the filter in an predetermined amount of time, such as 30 minutes, 15 minutes, 12 minutes, 10 minutes, 9 minutes, 8 minutes, 7 minutes, 6 minutes, 5, minutes, 4 minutes, 3 minutes, 2 minutes, 1 minute, or fractions thereof.
In order to produce biodiesel having an acceptable FBT value or pass a modified ASTM 6217 test, the biodiesel may be treated to obtain an acceptable FBT value or pass a modified ASTM 6217 test using methods of the present invention. Some conventional treatments to the biodiesel do not produce an acceptable FBT value or biodiesel that passes a modified ASTM 6217 test. For instance, biodiesel that is water washed to remove water-soluble impurities does not remove the steryl glycosides since the steryl glycosides are poorly soluble or insoluble in water. Thus, biodiesel treated by water washing contained 34 ppm steryl glycosides and failed the FBT test by exceeding 105 kPa pressure in less than 20 mL of the biodiesel.
Another conventional treatment of biodiesel is distillation. Although the distillation of the biodiesel may produce a biodiesel having an acceptable FBT value or that may pass a modified ASTM 6217 test, the distillation procedure is not economically acceptable. Thus, even though a commercial sample of biodiesel subjected to a distillation procedure contained no detectable steryl glycosides and had an FBT value of 1.01, the distillation procedure is costly. For instance, purification by distillation is expensive and inefficient. Further, the entire finished biodiesel product must be distilled by conventional means such as over a column or on a wiped film evaporator, necessitating costly inputs of energy to heat and cool the biodiesel. In addition, as biodiesel contains large amounts of heat-sensitive compounds, such as esters of olefinic fatty acids, the elevated temperatures required for distillation will accelerate the breakdown of the biodiesel, such as by lipid oxidation, leading to reduced storage stability of the distilled biodiesel. Alternatively, costly measures to store the biodiesel, such as the addition of antioxidants or blanketing with an inert gas, may be required.
In various embodiments described herein, an improved biodiesel having a reduced filter blocking tendency, as defined by test IP 387 (and ASTM Method D 2068, “Standard Test Method for Filter Blocking Tendency of Distillate Fuel Oils”) is prepared using the processes herein. By treating biodiesel with solid compounds, a treated biodiesel having a reduced filter blocking tendency than the starting biodiesel is produced. The improved biodiesel has a decreased amount of steryl glycosides. In some embodiments, the improved biodiesel has a decreased amount of monoacylglycerols. Further, it is desired that the improved biodiesel is able to flow at temperatures of 0° C. and below. Suitable solid compounds that may be used include, but are not limited to, adsorbents, filter aids, water-soluble solids, water-soluble bed materials, and any combinations thereof.
In one embodiment, a bed of solid bed material is associated with a filter and used to treat biodiesel by passing the biodiesel through the bed, thus, removing steryl glycosides from the biodiesel.
In an embodiment, a bed of solid bed material is associated with a filter and used to treat biodiesel by passing the biodiesel through the bed, thus, removing monoacylglycerols. In an embodiment, the compound can be applied to a filter as a precoat, wherein a layer of the compound is deposited on a filter and biodiesel is filtered by passing through the filter and the layer of the precoat. To apply a precoat, the desired quantity of compound is slurried in a small amount of biodiesel and the slurry is passed over or through the filter, such as a filter screen. The biodiesel passes thought the filter, leaving a thin layer of the compound on the screen for subsequent use in filtering biodiesel. In an embodiment, the compound can be applied to biodiesel as a body feed, wherein the compound is mixed with biodiesel and the mixture of the compound and the biodiesel is passed through a filter. In another embodiment, the compound mixed with biodiesel as a body feed may be passed through a filter and a layer of precoat.
In another embodiment, solid compounds may be added to biodiesel and slurried before removal of the solid compounds by passing the biodiesel/solid compound slurry through a filter. Solid bed materials that may be used include, but are not limited to, water-soluble solid bed materials. When water-soluble solid bed materials are used to treat the biodiesel, the solid bed material can be washed with solvent to remove any residual biodiesel. The water soluble solid bed material may also be dissolved in water to obtain a material enriched in steryl glycosides. Thus, in another embodiment, a process for purifying or obtaining steryl glycosides is disclosed.
In an additional embodiment, indicia are associated with biodiesel treated by the methods or processes of the present disclosure to inform the purchaser, distributor, blender or consumer of treated biodiesel that the treated biodiesel passes a filter blocking test or a modified ASTM 6217 test. In another embodiment, the indicia may disclose the results of a filter blocking tendency test result or a modified ASTM 6217 test. In another embodiment, the indicia may inform the purchaser, blender, distributor or consumer that the biodiesel has been treated to reduce the content of steryl glycosides and/or monoacylglycerols in the biodiesel. In yet another embodiment, indicia are associated with the treated biodiesel to provide or disclose the content of steryl glycosides.
In an embodiment, a period of incubation of biodiesel prior to filtration may be employed. In an embodiment, the temperature of incubation or storage may be below the manufacturing temperature. The duration of incubation prior to filtration may be 15 minutes, 30 minutes, 1 hour, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 18 hours, 24 hours, 2 days, 3, days, 4 days, 5 days, 6 days, 1 week, 2 weeks, 3 weeks, 4 weeks, 1 month, 2 months, 3 months, 4 months, 5 months, 6 months, or fractions of any thereof. In an embodiment, the temperature may be zero degrees Fahrenheit, 10 degrees Fahrenheit , 20 degrees Fahrenheit, 30 degrees Fahrenheit, 40 degrees Fahrenheit, 50 degrees Fahrenheit, 60 degrees Fahrenheit, 70 degrees Fahrenheit, 80 degrees Fahrenheit, 90 degrees Fahrenheit, 100 degrees Fahrenheit, 110 degrees Fahrenheit, 120 degrees Fahrenheit, or fractions of any thereof. Following the incubation, the biodiesel may be filtered such as through a polishing filter, a bag filter, a sock filter, a dewaxing filter or any combination thereof. In an embodiment, filtration may employ the use of a compound in the form of a body feed, a precoat, or combinations thereof. In another embodiment, biodiesel my be incubated or stored for a second period prior to being subjected to a test to determine filterability, such as ASTM Method D 2068 or a modified ASTM D6217 test.
The invention is further explained by use of the following illustrative examples.
EXAMPLE 1In one embodiment, biodiesel was tested to see if the biodiesel has an acceptable FBT value. Commercially manufactured rapeseed biodiesel that was subjected to a final polishing filtration step through a final sock filter having 1 micron pore size at 14250 kg/hour was obtained. Filter blocking tests were performed on the rapeseed biodiesel using a Normalab Analis (Lintot, France) NBF 240 instrument according to IP 387 (and ASTM Method D 2068, Standard Test Method for Filter Blocking Tendency of Distillate Fuel Oils, ASTM International. The ASTM standards may be obtained from the ASTM website at www.astm.org. The biodiesel flow through the polishing sock filters was unimpeded and the FBT value of the finished biodiesel was 1.02 (maximum pressure reached in filtration of 300 ml biodiesel was 21 kPa).
In another embodiment, fatty acids recovered from a glycerol-rich heavy phase of biodiesel manufactured by the process of U.S. Pat. No. 5,354,878 (which is hereby incorporated in its entirety by reference) were used as feedstock to synthesize biodiesel using hydrochloric acid as a catalyst. These fatty acids are referred to as “acid oil”. The following amounts of reactants were used to synthesize the biodiesel: 100 parts fatty acid, 100 parts methanol, 3 parts hydrochloric acid, and 180 minutes of incubation with heat and stirring in a 1000 liter vessel. The resulting biodiesel (780 kg) was blended into the 14250/kg/hour flow of rapeseed biodiesel going to the filters over the course of 2 hours (390 kg/hour). The FBT of the blended biodiesel increased steadily until it reached a peak of 1.69 and failed the FBT test by reaching 105 kPa pressure after filtering only 220 ml. Solid material on the final bag filter having 1 micron pore size was tested by thin-layer chromatography and a spot having a retention factor equal to a steryl glycoside reference was observed. Both Nuclear Magnetic Resonance and gas chromatography with mass spectroscopy determined that the solid material on the final bag filter having 1 micron pore size contained sterol and sugar structures.
EXAMPLE 2Commercially manufactured soy biodiesel which had not been subjected to simple final filtration through a polishing filter was obtained. This unfiltered soy biodiesel was subjected to filtration treatments through compounds, wherein the biodiesel was placed in contact with a compound for removing steryl glycosides from the biodiesel. The compounds in this example included granular glucose, granular sugar, diatomaceous earth, and granular clay. A Buchner funnel was fitted with #1 filter paper (3.8 cm diameter, 11.3 cm2 filter area, >11 micron particle retention) and beds of the various solid bed materials (i.e., compounds for removing the steryl glycosides) were prepared. The amount of time required to pass 50, 100, 150 and 200 ml of room temperature biodiesel through the filter was determined (Table 1). Studies were carried out in duplicate.
Filtration volumes and times for biodiesel passed through compounds. Diatomaceous earth (DE) was FW20 from Eagle Picher, Phoenix, AZ. Granular clay was Agsorb 30/60 LVM-GA from OilDri, Chicago, Ill.
The content of steryl glycosides in the unfiltered biodiesel was estimated to be 70-90 ppm obtained by ascertaining the increase in weight that occurred with the granular sugar used as a solid bed material. The filter paper with no additional solid bed material was blinded or coated quickly with a gummy deposit, resulting in slow filtration (long filtration time). After filtering biodiesel through filter paper with no additional solid bed material at room temperature, the steryl glycosides content of the filtered (i.e., treated) biodiesel was 50 ppm. Granular glucose, granular sugar and diatomaceous earth (DE) provided shorter filtration times. The filtration time obtained with granular clay was longer than the other solid bed materials. The shortest filtration time, and thus the fastest flow, was obtained with granulated sugar, while a constant filtration rate was obtained with diatomaceous earth DE.
EXAMPLE 3 Magnesium silicate (Magnesol R30, Dallas Group, Whitehouse, N.J.) was tested as a “body feed” for treating biodiesel having a steryl glycoside content of 174 ppm and visible haze. Unfiltered biodiesel (180 g) was slurried at room temperature or at 60° C. with Magnesol R30 (added as “body feed” to the biodiesel) for 10 minutes. The slurry was filtered through Whatman #1 filter paper at room temperature. The steryl glycoside content in biodiesel before and after Magnesol treatment and filtration was measured. The filtered biodiesel was also subjected to a Cold test (AOCS Official Method Cc 11-53) to evaluate the reduction of haziness. A procedure of the cold test is found in “Official Methods and Recommended Practices of the AOCS”, Fifth Edition, Second Printing (2004) American Oil Chemists' Society, Champaign, Ill., which is incorporated herein in its entirety by this reference. For the cold test, 4 oz. clear sample bottles were filled with biodiesel before immersion in an ice water bath maintained at 0° C. The sample bottles were removed from the ice water bath every hour to examine the appearance of the biodiesel for haziness. To pass the test, the biodiesel samples should be completely clear and brilliant.
All levels of Magnesol R30 treatment were effective at reducing the appearance of haze at room temperature and 60° C. The appearance of haze or lack of appearance of haze at room temperature in biodiesel treated at room temperature and treated at 60° C. was used as a qualitative assessment of possible steryl glycoside content. Room-temperature magnesium silicate treatment was more effective at reducing the quantity of steryl glycosides in biodiesel than treatment at 60° C., and also produced a biodiesel which passed a cold test at 4 hours (Tables 2 and 3). However, the ability of the biodiesel to pass the cold test after filtration at room temperature was unrelated to the steryl glycosides content of the biodiesel, indicating that the cold test was not actually measuring steryl glycoside content, but rather measuring some other component (i.e., possibly the crystals rich in saturated fatty acid ester which develop under cold conditions).
Samples of biodiesel filtered with 1.2% Magnesol at room temperature and 60° C. were analyzed to determine the effectiveness of Magnesol treatment at reducing the content of monoacylglycerols and the results are presented in Table 4.
Cooling the biodiesel was not required to reduce the content of monoacylglycerols. A reduction of 15% was effected at room temperature and a reduction of 17% was effected at 60° C.
EXAMPLE 4 Water-soluble compounds (i.e., sugar, sodium chloride, and citric acid) were compared with DE for their ability to remove steryl glycoside from biodiesel and produce improved biodiesel. Commercial biodiesel (600 g) having a steryl glycoside content of 174 ppm was filtered through the water-soluble solid bed materials (14 grams of granular sugar, sodium chloride (NaCl) or citric acid) or diatomaceous earth (DE, 5 grams) on a Whatman #1 filter paper (3.4 cm diameter) under vacuum. Residual biodiesel was removed from the sugar, sodium chloride, and citric acid filter cakes by washing with ˜100 ml hexane and hot water (˜70° C., 200 ml), which was used to dissolve the solid bed materials and recover the steryl glycosides. The recovered steryl glycosides remaining on the filter paper were dried in a 70° C. oven overnight.
Excellent Filter Blocking Tendency (FBT) values and reduction of steryl glycosides of from 77.6% to 87.3% were obtained with the solid bed materials tested (Table 5).
EXAMPLE 5A sample of unfiltered commercial soy biodiesel having 117 ppm steryl glycosides and filtered commercial soy biodiesel (having 68 ppm steryl glycosides) produced at the same facility were subjected to the Filter Blocking Test. The unfiltered and the filtered soybean biodiesel failed the FBT test by exceeding 105 kPa pressure after 20 ml, to yield FBT values of 15.03. The filtered soy biodiesel (1000 g) was passed through a bed of 5 grams of diatomaceous earth at room temperature to yield a treated biodiesel having a steryl glycoside content of 20 ppm which passed the FBT test with an FBT value of 1.01.
EXAMPLE 6The commercial unfiltered soy biodiesel from Example 5 (1000 g) was filtered through a 5 gram bed of diatomaceous earth (DE) at room temperature and at 60° C. using the procedure of Example 4. The biodiesel filtered through the diatomaceous earth at room temperature had an FBT value of 1.01 and contained 34 ppm steryl glycosides. The biodiesel filtered through diatomaceous earth at 60° C. had an FBT value of 1.20 and contained 39 ppm steryl glycosides.
EXAMPLE 7 Diatomaceous earth was tested as a “body feed” for treating biodiesel. Commercial soy biodiesel (555 g) was treated by slurrying the soy biodiesel with 5 g DE (Altofina Clarcel DIT/2R SA 25K, AltoFina, King of Prussia, Pa.), stirring the slurry for 10 minutes at 500 rpm, and filtering the slurry through a 0.95 cm deep bed of DE on a 4 cm diameter Schleicher & Schuell “White Ribbon Filter” filter paper (Grade 598/2: 4-12 micron retention, ashless standard filter paper for medium fine precipitates (class 2b according to DIN 53 135, from VWR/Sargent Welch Scientific Co., Buffalo Grove, Ill.). The filtration was carried out at room temperature and the filtrate was cooled to 1° C. After cooling, the filtrate was analyzed to measure the FBT and contents of glycerol esters in the untreated and treated biodiesels. The results are shown in Table 6.
Although the content of glycerol esters was virtually unchanged by the filtration treatment at both temperatures, the FBT values were greatly affected. The unfiltered biodiesel failed the FBT test after only 20 ml had passed through the FBT filter, but the treated biodiesel showed excellent FBT values, showing that improvement of FBT by filtering through DE under these conditions was not dependent on removal of the glycerol esters that can cause filter blockage.
EXAMPLE 8A purified steryl glycoside composition was prepared by filtration through granulated sugar. After treating 1000 mL of soy biodiesel with a bed of granular sugar (15 g, 1.2 cm deep) as described in Example 4, the bed of granular sugar was washed with hexane to remove the biodiesel from the bed of granular sugar. The composition of soy biodiesel is given in Table 7. Warm wash water was applied to the carbohydrate solid bed material (granular sugar). The solid bed material that dissolved in the wash step left behind a steryl glycoside composition comprising 92% steryl glycoside.
The entire lot of treated biodiesel was refrigerated for 3 days at 2.2° C. (36° F.). A visible cloud formed. The treated, refrigerated biodiesel was filtered through a second bed of granular sugar (approximately 2 cm. in depth). The filter bed was washed with cold (−6° C.) hexane. Water was applied to the second bed of granular sugar to dissolve the sugar, and material remaining on the filter was recovered. This material was washed with water and dried at 70° C. The material partially melted and formed a waxy solid when cooled. The waxy solid was predominantly monoacylglycerols (>90%, Table 7) and contained 0.67% steryl glycosides.
The monoacylglycerol-rich waxy solid was enriched in (greater than 92%) of saturated monoacylglycerols (Palmitic C16:0 and Stearic C18:0, Table 8).
EXAMPLE 9
Biodiesel containing 22 ppm steryl glycosides was obtained by combining the biodiesel filtered through sodium chloride (22 ppm steryl glycosides) obtained in Example 4 with the biodiesel filtered through citric acid (22 ppm steryl glycosides) obtained in Example 4. Purified steryl glycosides obtained using the treatment of Example 8 were added at known levels (10, 30, and 50 ppm) to the biodiesel to produce biodiesel of various steryl glycosides contents, which were subjected to the Filter Blocking Tendency test (Table 9).
All of the biodiesel samples containing additional steryl glycosides failed the FBT (FBT values greater than 1.414).
EXAMPLE 10Soy biodiesel (400 g) having an FBT value of 15.03 was blended with 12 grams of deoiled soy lecithin and subjected to a degumming procedure. The mixture was heated and mixed vigorously to disperse the lecithin in the biodiesel. Deionized water (12 grams) was added to the mixture and the mixture was agitated gently for about 20 minutes. The mixture was subjected to centrifugation, cooled to 40° F. and held at that temperature for 16 hours. The mixture was allowed to warm to room temperature and subjected to the filter blocking tendency test. The FBT value of biodiesel treated in this manner was 1.02 (passed). The heavy phase is expected to be enriched in steryl glycosides.
EXAMPLE 11Commercial unfiltered biodiesel (1000 g, labeled “Feed BD”) at room temperature (i.e., ˜72° F.) was divided into two lots, and each lot was passed through a separate bed of diatomaceous earth (DE) (5 g). The DE filter cake was labeled “DE filter cake” and the biodiesel that had passed through the filter was labeled “DE filtered BD”. Each filter cake was washed with 200 ml room temperature hexane. One lot of filtrate (DE filtered BD) was evaluated by the Filter Blocking Test and an FBT value of 1.01 was obtained. The other lot of filtrate (DE filtered BD) was cooled for 72 hours in a cold bath at 37° F. and divided into two sublots of 250 g.
Each sublot of DE filtered BD was filtered through separate beds of 15 g granular sugar and the filtrates were combined, labeled “37° F. DE filtered, cooled BD final” and analyzed. The sugar filter beds were washed with 200 ml cold (−5° C.) hexane and the hexane wash filtrates were combined, evaporated to remove hexane, labeled “37° F. DE filtered, hexane filtrate,” and analyzed. The combined sugar filter beds (DE filtered, hexane residue) were washed with 200 ml room temperature water to remove sugar. The filter paper from the sugar beds was dried at room temperature and the solid residue on the filter paper was labeled “37° F. twice filtered solid bed” and analyzed. The results of the analysis are shown in Table 11.
*not measurable
When biodiesel having a MAG content of 0.71% was filtered through DE, cooled and filtered through sugar, the biodiesel passed easily and quickly through the bed of sugar, and the content of monoacylglycerol (MAG) was virtually unchanged. The small amount of “37° F. twice filtered solid bed” (0.2907 g) obtained by treating biodiesel with DE at room temperature, cooling the biodiesel, filtering through sugar, washing the sugar filter bed (filter cake) with cold hexane, and washing the sugar filter bed with room temperature water was almost exclusively monoacylglycerols (greater than 95%) and was enriched in steryl glycosides (SG, 654 ppm).
EXAMPLE 12 Commercial unfiltered biodiesel used in Example 11 (500 g, labeled “Feed BD”) was cooled for 72 hours in a cold bath at 37° F. and divided into two sublots of 250 g. Each sublot was filtered through separate beds of 15 g granular sugar and the filtrates were combined, labeled “Filtered BD final,” and analyzed. The sugar filter beds were washed with 200 ml cold (−5° C.) hexane and the washed filter beds were combined, labeled “All cooled hexane residue,” and analyzed. The sugar filter bed was washed with 200 ml room temperature water. The filter paper was dried at room temperature and the solid residue on the filter was labeled “All cooled solid residue” and analyzed. The results of the analysis are shown in Table 12.
*not measurable on this material
The flow of cooled biodiesel through sugar beds was not rapid as it was in Example 11. This filter treatment reduced the content of MAG in biodiesel, the content of SG decreased from 65 to 27, and the resulting biodiesel had excellent properties in the Filter Blocking Test.
EXAMPLE 13 Commercial soy methyl esters containing 56 ppm steryl glycoside failed the filter blocking test (FBT) with a filter plugging tendency value of 30.0. Two solvents were tested as co-solvents for the methyl esters; dimethyl acetamide (DMA, boiling point 164° C.) and methyl-s-pyrrolidinone (methyl pyrrolidone, boiling point 202° C.). Solvents (33 ml, 10 v/v %) were mixed with 297 ml commercial soy methyl esters and stirred with a magnetic stirrer overnight at room temperature, and filter plugging tendencies were measured by FBT. The filter plugging tendencies were improved as shown in table 13. In another test, the methyl esters/solvents mixtures were stirred with a magnetic stirrer for 6 days at room temperature, then FBT were measured. The FBT passed the test (Table 13).
Semisolid material (final filter cake) retained in a production scale sock filter in a final polishing filtration step of biodiesel manufacture (30 g) was mixed with 1000 ml diethyl ether on a magnetic stirrer for 10 min. After mixing, the mixture was centrifuged at 3000 rpm for 30 sec, and the solvent phase was decanted. Hexane (1000 ml) was mixed with the pellet for 30 minutes, and the mixture was centrifuged and decanted the same way for a total of three hexane washes. The pellet was recovered and filtered through #1 filter paper to provide a residue cake. The residue cake was oven-dried at 70° C. overnight. About 3.4 g of material was recovered and analyzed. The material was steryl glycoside of 99.8% purity.
EXAMPLE 15Steryl glycosides were measured in biodiesel made from once-refined (OR) soybean oil (ADM, Decatur, Ill.) and refined, bleached (RB) soybean oil (ADM Quincy IL). OR Soybean oil contained 189 ppm steryl glycosides, and RB soy contained 224 ppm steryl glycosides. Samples of each oil were subjected to biodiesel synthesis. About 500 ml oil was taken up in a round bottom flask and heated to 90° C. under house vacuum for 15 minutes to remove traces of water. Dried oil (436 grams) was mixed with anhydrous methanol (90.0 g) to provide a molar ratio of triacylglycerols/methanol of 1/6 in a one-liter Erlenmeyer flask. A magnetic stir bar was placed in the flask and stirring was started. To the oil/methanol mixture was added 30% sodium methoxide catalyst solution (7.6 ml; 0.5 wt % sodium methoxide based on oil weight). This mixture was refluxed for 30 minutes, when the vessel was removed from heat and cooled under reflux until boiling ceased. The reaction mixture was transferred to a one-liter separatory funnel and held for 10 minutes to separate. A phase separation took place, and the lower phase (glycerol phase) was drained from the separatory funnel. The reaction mixture (biodiesel) was transferred to a one-liter round bottom flask and washed by mixing with 44 ml warm (˜70° C.) water with agitation. After ten minutes, the bottom phase was removed with a pipette and the wash procedure was repeated twice for a total of three washes. The washed biodiesel was transferred to a separatory funnel, remaining visible wash water was removed, and the biodiesel was dried by heating to 90° C. under house vacuum and holding for 20 minutes. The wash waters were combined and concentrated by evaporation on a rotary evaporator. After biodiesel synthesis, steryl glycosides were concentrated in the wash water (Table 14).
Steryl glycoside content (ppm) in biodiesel process streams made from once-refined (OR) and refined, bleached (RB) soybean oil. ND=not detected.
ND = not detected
ND: Not detected
Commercial soy biodiesel (B100, comprising 100% soy biodiesel) containing 58 ppm steryl glycosides was mixed with petroleum diesel fuel obtained from a local filling station to obtain blends (Table 15) which were subjected to the Filter Blocking Test. The petroleum diesel fuel had a cloud point of −19.6° C., which is in the range of Number 2 diesel fuel. B100 and B10 failed the filter blocking test, but blends incorporating 2% and 5% biodiesel in conventional diesel (B2 and B5, respectively) passed the filter blocking test (Table 15).
Commercial soy biodiesel (B100, comprising 100% soy biodiesel) containing 58 ppm steryl glycosides was subjected to filtration through diatomaceous earth substantially as described in Example 5 to produce a B100 with reduced content of steryl glycosides (37 ppm). The B100 with a reduced content of steryl glycosides and blends with petroleum diesel (B10 and B20) passed the filter blocking test (Table 16).
Commercial soy biodiesel having a steryl glycoside content of 69 ppm failed when subjected to the filter blocking test. The effects of incubation of biodiesel at certain temperatures before and after filtration through diatomaceous earth on steryl glycoside content and FBT tendency were tested. A sample of biodiesel (1 liter) was held overnight at 70° C., and incubated in a water bath at a first temperature of 70° F. (Table 17A), 50° F. (Table 17B), or 40° F. (Table 17C) for a first incubation time. The incubated biodiesel (500 ml) was filtered through a 5 gram precoat of diatomaceous earth, incubated at a second temperature for a second period as indicated in Table 17A, 17B, and 17C, and subjected to the filter blocking test, and the content of SG was determined.
*nd, not determined due to failure on FBT test
*nd, not determined due to failure on FBT test
*nd, not determined due to failure on FBT test
Heating biodiesel to 70° C. overnight followed by incubating biodiesel at room temperature, or cooling biodiesel to 40° F., or 50° F. for as little as six hours before filtering through a filter aid, proved to be an effective means of reducing steryl glycosides and improving filter blocking test results after a second incubation at 40° F. or room temperature (Tables 17A, 17B and 17C).
EXAMPLE 18 Commercial soy biodiesel having a steryl glycoside content of 69 ppm failed when subjected to the filter blocking test. The effects of treatment of biodiesel with activated carbon were tested by stirring the carbon with soy biodiesel. A sample of biodiesel (1 liter) was heated overnight at 70° C. This heated biodiesel (500 ml) was stirred with carbon (SA4 carbon, Norit Americas, Inc. Marshall, Tex.) in a water bath at a first temperature of 70° C. for one hour. The incubated biodiesel (500 ml) was filtered at 70° C. through filter paper to remove the carbon, incubated at a second temperature (RT) for a second period (three days), and tested to determine the filter blocking tendency and the content of SG.
Carbon treatment was effective in reducing the FBT and steryl glycoside content of biodiesel (Table 18A).
Commercial soy biodiesel having a steryl glycoside content of 69 ppm failed when subjected to the filter blocking test. The effects of treatment of biodiesel with SA4 carbon or PWA carbon (Calgon Carbon Corp, Pittsburg, Pa.) were tested by stirring with soy biodiesel. A sample of biodiesel (1 liter) was heated overnight at 70° C. This heated biodiesel (500 ml) was stirred with carbon in a water bath at a first temperature of 70° C. for one hour. The incubated biodiesel (500 ml) was filtered at 70° C. through a precoat of diatomaceous earth, incubated at a second temperature for a second period, and tested to determine the filter blocking tendency and the content of SG.
Carbon treatment and incubation was effective in reducing the FBT and steryl glycoside content of biodiesel (Table 18B).
Commercial soy biodiesel having a steryl glycoside content of 69 ppm failed when subjected to the filter blocking test. A sample of biodiesel (1 liter) was heated overnight at 70° C. The effects of treatment of biodiesel with CPG LF granular activated carbon (Calgon Carbon Corp. Pittsburg, Pa.) were tested by passing this heated soy biodiesel (500 ml) at 0.72 grams/minute through a bed of CPG LF granular activated carbon (11.5 grams) in a jacketed column (12 mm×40 mm) held at 70° C. The carbon-treated biodiesel was filtered at 70° C. through filter paper, incubated at a second temperature (room temperature) for three days, and tested to determine the filter blocking tendency and the content of SG. The FBT value was 1.02 and the content of steryl glycosides was 31 ppm.
EXAMPLE 19Commercial soy biodiesel having a steryl glycoside content of 65 ppm and monoacylglycerol content of 0.71% which failed the FBT test was filtered through DE at room temperature to obtain filtered soy biodiesel having a steryl glycoside content of 33 ppm, a monoacylglycerol content of 0.72%, and an FBT value of 1.01. The filtered soy biodiesel and an unfiltered control of commercial soy biodiesel were cooled to 33° F. and stored at 33° F. The filtered soy biodiesel remained clear for several days of incubation at 33° F. The unfiltered control biodiesel became visibly hazy after 1 day of incubation at 33° F. and this control was filtered through filter paper. The monoacylglycerol content of the filtered control biodiesel thus obtained was reduced to 0.65% and the steryl glycoside content was reduced to 27 ppm; the solid residue (filter cake) obtained contained 63.97% monoacylglycerols. Thus, the steryl glycosides enabled removal of monoacylglycerols from the soy biodiesel by filtration, possibly by providing nucleation sites for development of haze or crystals enriched in monoacylglycerols.
EXAMPLE 20Soy methyl esters containing 142 ppm steryl glycosides were washed at 150° F. by mixing with 10% of a solution containing 2% boric acid for 15 minutes. The mixture was centrifuged and the methyl ester phase dried. The resulting methyl esters contained 41 ppm steryl glycosides and passed the filter blocking test (FBT=1.04).
EXAMPLE 21Soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were treated by adding 1.2% powdered carbon (Calgon PWA) at 15° F. and stirring for 1 hour. The treated methyl esters plus carbon were filtered at 158° F. with 47 mm diameter #1 filter paper and 5 g of diatomaceous earth. The treated and filtered soy methyl esters contained 26 ppm steryl glycosides and passed the filter blocking test (FBT=1.01).
EXAMPLE 22 Soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were treated by passing through a packed bed of granular carbon (11.5 g Calgon CPG LF 12×40 in a 13.5 cm high×1.5 cm diameter column) at 158° F. and a flow rate of 2 BV/hour. The FBT of the effluent methyl esters was tested (Table 19).
Soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were treated as described in Example 22 except that the flow rate was 4 BV/hour. The effluent methyl esters collected for 24 hours failed the filter blocking test (FBT=2.36).
EXAMPLE 24 Soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were treated by mixing with Norit SA4-PAH-HF carbon for 1 hour at 158° F. as a “body feed” and then filtered at 158° F. through 47 mm diameter #1 filter paper without additional filter aid precoat. The filtered methyl esters were allowed to incubate for 3 days at room temperature prior to testing for filter blocking tendency (Table 20).
Soy methyl esters containing 54 ppm steryl glycosides and FBT=15.03 were incubated for 6 or 12 hours at 40° F. or 50° F. prior to filtering with 5 g diatomaceous earth and the filtered soy methyl esters were tested for filter blocking tendency (Table 21). All 4 samples passed the filter blocking test (FBT=1.01-1.02). For comparison, fresh soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were incubated for 1, 2, and 3 days at room temperature prior to filtering with 5 g diatomaceous earth (Table 21). All 3 of these samples also passed the filter blocking test (FBT=1.01-1.02) after storage.
Soy methyl esters containing 69 ppm steryl glycosides and FBT=15.03 were treated with 0.5% carbon (Norit SA4-PAH-HF) as a body feed by mixing for 1 hour at 158° F. and then filtered at 158° F. with 47 mm diameter #1 paper and 1 g diatomaceous earth bed. The treated and filtered methyl esters were chilled for 20 hours at 40° F. prior to testing for filter blocking tendency; the FBT of the carbon-treated, filtered, biodiesel after incubation at 40° F. was 1.16.
EXAMPLE 27Cellulose (EFC 450 from J. Rettenmaier, Rosenberg, Germany) was added to unfiltered soy methyl esters (having an FBT value of 15.03, fail) at 25 kg cellulose to 12 metric tons methyl esters and stirred for 1 hour. This mixture was used to precoat an industrial dewaxing filter to a depth of 3 mm. Soy methyl esters (180 metric tons) were chilled and incubated (stored) for one week at 52 -70° F., and filtered at a rate of 20 metric tons/hr through the cellulose precoat. The total back-pressure remained stable at 7.25 psig during the entire filtration process. Three samples of biodiesel filtered through cellulose taken at different times during the filter process all passed the filter blocking test (FBT=1.02 to 1.04).
EXAMPLE 28Three different batches of fresh commercial soy methyl esters (one each from Mainz, Leer, or Hamburg, all of Germany) were filtered as described in Example 27. Samples of the treated methyl esters were incubated in a water bath at 40° F. for 16 hours prior to running the filter blocking test. All three samples passed the Filter Blocking Test (FBT=1.01-1.03).
EXAMPLE 29 Distilled soy methyl esters were spiked with a steryl glycoside solution in pyridine such that the steryl glycoside concentration in the distilled soy methyl esters would be 25 ppm after the pyridine was removed. The mixture was treated with heat and vacuum to remove the pyridine and the methyl esters containing 25 ppm steryl glycosides were then chilled for 2, 4, and 6 hours at 40° F. prior to filtering at 40° F. with through a precoat of 5 g diatomaceous earth on 47 mm diameter #1 paper. The filtered samples were stored for 16 hours at 40° F. Samples were allowed to warm to room temperature without external heat source and then tested by the filter blocking tendency test.
*DE: Diatomaceous Earth
Samples were prepared as described in Example 29 except that steryl glycoside concentration was 100 ppm. Samples were incubated and filtered as shown below. Samples were filtered at the incubation temperature, the filter used was 47 mm diameter #1, and 5 g of diatomaceous earth was used when applicable. All filtered samples were then incubated for 16 hours at 40° F. The samples were allowed to warm to room temperature without external heat source and then tested for filter blocking tendency.
*DE: Diatomaceous Earth
Fresh soy methyl esters containing 55 ppm steryl glycosides were incubated for 6 hours at 40° F. immediately after synthesis substantially as described in Example 15 and divided into four lots. Each lot was filtered at 40° F. through 5 gram precoats of one of the following filter aids on using 47 mm diameter #1 filter paper: diatomaceous earth, Filtracel 250C cellulose, J. Rettenmaier Filtracel 250C+ cellulose, and Filtracel 450 cellulose. All filtered samples were then stored at 40° F. for 16 hours, allowed to warm to room temperature, and tested for filter blocking tendency.
Soy methyl esters, FBT=15.03, were treated with beta-glucosidase (Sigma). A solution of 0.2 g beta-glucosidase in 40 g water was added to 400 g soy methyl esters. The mixture was heated to 104° F. at ambient pressure and allowed to stir for 24 hours. The mixture was transferred to a separatory funnel and the water phase drained. The methyl ester phase was dried for 20 minutes at 194° F. under vacuum. The dried methyl esters were stored at 40° F. for 16 hours prior to testing for filter blocking tendency (FBT=3.88).
EXAMPLE 33 Soy methyl esters were synthesized by incubating soybean oil with methanol and catalyst substantially as outlined in Example 15. The FBT value of freshly synthesized soy methyl esters, after water washing three times with 10 vol % water, was 10.05 (Table 23). In some embodiments, the water washing step was eliminated and fresh soy methyl esters were treated with silica hydrogel (PQ Corporation 29-4) before or after a drying step. When methyl esters were dried as indicated in Table 23, where applicable, the reaction product was dried by incubation for 20 minutes at 90° C. under vacuum 10 and allowed to cool to room temperature. Hydrogel treatment was carried out on dried or undried methyl ester by heating methyl esters to 65° C., adding Silica Hydrogel 29-4 (PQ Corporation, Valley Forge, PA) as indicated in Table 23, and stirring for 10 minutes at 65° C. Vacuum was applied and the methyl esters and hydrogel were heated to 90° C. and held at 90° C. for 20 minutes. The mixture 15 was cooled to 70° C., the vacuum was released, and the mixture was filtered through #50 (medium) filter paper in a Buchner funnel. Immediately after filtering, all samples were placed in 40° F. bath for 16 hours. The samples were allowed to warm to room temperature and tested for filter blocking tendency.
The silica hydrogel treatment produced methyl esters which passed the filter blocking test while eliminating the water washing step.
EXAMPLE 34 The filter blocking tendency test (FBT, ASTM D2068) was compared to a modified ASTM D6217 test which may be used as a biodiesel specification. The FBT test was carried out as described above. The modified 6217 test was carried out as follows: biodiesel (300 ml) was filtered through a 1.6 um GF/A filter having 47 mm diameter under a 21-25 inch Hg vacuum. To pass the test, the entire sample of 300 ml must pass through the filter in 6 minutes. In every case, biodiesel that passed the FBT test also passed the modified D6217 test. Table 26 reports the time required for 300 ml to pass through the filter for passing samples, and the volume passed through the filter in 6 minutes for failing samples.
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. Thus, while certain exemplary embodiments and details have been described for purposes of exemplifying the invention, it will be apparent to those of ordinary skill in the art that various changes to the invention described herein may be made in any combination without departing from the scope of the present disclosure, which is defined in the appended claims.
Claims
1-118. (canceled)
119. A process for reducing the filter blocking tendency of biodiesel, comprising:
- placing the biodiesel in contact with a solid or liquid, the solid or liquid comprising a compound capable of reducing the filter blocking tendency of biodiesel.
120. The process of claim 119, wherein placing the biodiesel in contact with the solid or liquid comprises mixing the solid or liquid with the biodiesel, and further comprising separating the solid or liquid from the biodiesel.
121. The process of claim 119, wherein placing the biodiesel in contact with the solid or liquid comprises passing the biodiesel through a bed of the solid or the liquid.
122. The process of claim 119, wherein steryl glycosides are removed from the biodiesel.
123. The process of claim 119, wherein the solid or liquid is selected from the group consisting of adsorbents, filter aids, boric acid, soap, sucrose, sugar, glucose, sodium chloride, citric acid, magnesium silicate, clay, diatomaceous earth, lecithin, granular clay, granular glucose, granular sugar, protein, textured vegetable protein, carbon, cellulose, solutions comprising boric acid, silica hydrogel, beta-glucosidases, and combinations of any thereof.
124. The process of claim 119, further comprising subjecting the biodiesel to a filter blocking test comprising:
- determining whether a pre-selected volume of the biodiesel passes through a filter within a pre-selected time;
- wherein the pre-selected volume of the biodiesel passes through the filter before the pre-selected time is reached, giving the biodiesel a passing test result;
- wherein the pre-selected time is reached before the pre-selected volume of the biodiesel passes through the filter, giving the biodiesel a failing test result.
125. The process of claim 119, further comprising subjecting the biodiesel to a degumming step.
126. The process of claim 119, further comprising filtering the biodiesel through a filter aid selected from the group consisting of diatomaceous earth, sugar, and a combination thereof.
127. The process of claim 119, further comprising: incubating the biodiesel at between 40° F. and 70° F.; and filtering the incubated biodiesel.
128. The process of claim 127, wherein filtering the incubated biodiesel comprises placing the biodiesel in contact with a compound selected from the group consisting of diatomaceous earth, carbon, cellulose, and combinations of any thereof.
129. The process of claim 119, wherein the solid of the liquid is contacted with the biodiesel as a body feed.
130. The process of claim 119, further comprising forming a precoat of the solid or the liquid on a filter.
131. The process of claim 127, further comprising subjecting the filtered biodiesel to a test selected from the group consisting of ASTM D2068, a modified ASTM D6217 and a combination thereof.
132. The process of claim 131, further comprising incubating the filtered biodiesel for a second incubation period prior to subjecting the filtered biodiesel to the test, thus decreasing the content of steryl glycosides in the filtered biodiesel.
133. The process of claim 119, further comprising,
- wherein placing the biodiesel in contact with the solid or the liquid comprises filtering the biodiesel through the solid comprising a bed of water-soluble solid bed material; and
- dissolving the water-soluble solid bed material in water to remove the water- soluble solid bed material, thus producing a composition enriched in steryl glycosides.
134. The process of claim 133, further comprising washing the bed with a solvent.
135. The process of claim 119, further comprising subjecting the biodiesel to a filter blocking test comprising:
- determining whether a pre-selected volume of the biodiesel passes through a filter before a pre-selected pressure is placed on the filter from the biodiesel;
- wherein the pre-selected volume of the biodiesel passes through the filter before the pre-selected pressure is reached, giving the biodiesel a passing test result;
- wherein the pre-selected pressure is reached before the pre-selected volume of the biodiesel passes through the filter, giving the biodiesel a failing test result.
136. The process of claim 119, wherein the biodiesel comprises a detectable level of steryl glycosides that is less than 70 ppm.
137. The process of claim 119, further comprising:
- incubating the biodiesel, a filter cake obtained from the biodiesel production, a final filter cake of the biodiesel production, and combinations of any thereof with a first solvent to obtain a solid component and a liquid component;
- separating the solid component from the liquid component;
- washing the solid component with a second solvent; and
- removing the second solvent from the first solvent, thus obtaining a purified steryl glycoside.
138. A process for treating biodiesel comprising:
- placing biodiesel in contact with a compound capable of removing steryl glycosides from the biodiesel.
139. The process of claim 138, further comprising:
- separating the biodiesel from the compound capable of removing the steryl glycosides; and
- mixing the biodiesel separated from the compound capable of removing steryl glycosides with a fuel selected from the group consisting of a petroleum based diesel fuel, a biodiesel not placed in contact the compound capable of removing steryl glycosides, ethanol, and any combinations thereof.
140. The process of claim 138, further comprising:
- wherein the compound is selected from the group consisting of adsorbents, filter aids, boric acid, soap, sucrose, sugar, glucose, sodium chloride, citric acid, magnesium silicate, clay, diatomaceous earth, lecithin, granular clay, granular glucose, granular sugar, protein, textured vegetable protein, carbon, cellulose, solutions comprising boric acid, and combinations of any thereof; and
- separating the compound from the biodiesel.
141. The process of claim 140, wherein the compound is separated from the biodiesel by a process selected from the group consisting of filtration, centrifugation, and combinations of any thereof.
142. The process of claim 140, wherein the biodiesel is derived from an oil that is selected 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, derivatives of the oils, fractions of the oils, conjugated derivatives of the oils, and mixtures of any thereof.
143. A process for removing monoacylglycerols from a fatty acid methyl ester containing material, comprising:
- placing a compound selected from the group consisting of magnesium silicate, granular sugar, steryl glycosides, and any combination thereof in contact with a fatty acid containing material; and
- separating the compound from the fatty acid containing material.
144. The process of claim 143, wherein the compound is separated from the fatty acid containing material by a process selected from the group consisting of filtration, centrifugation, and combinations of any thereof.
145. The process of claim 143, wherein the fatty acid containing material is selected 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, camelina 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, derivatives of the oils, fractions of the oils, conjugated derivatives of the oils, and mixtures of any thereof.
146. The process of claim 143, further comprising:
- adjusting a temperature of the fatty acid containing material;
- mixing a solid capable of reducing the content of monoacylglycerols with the fatty acid containing material; and
- separating the solid from the fatty acid containing material.
147. A process for treating biodiesel, comprising:
- placing the biodiesel in contact with a solid or liquid capable of improving the result of a cold test of biodiesel.
148. 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 that allows biodiesel to form, the condition being selected from the group consisting of time, an increased temperature, an increased pressure, the presence of a catalyst and any combination thereof;
- isolating the biodiesel; and
- treating the biodiesel with silica hydrogel.
Type: Application
Filed: Dec 21, 2006
Publication Date: Jul 5, 2007
Inventors: Inmok Lee (Decatur, IL), Jerry Mayfield (Decatur, IL), Lisa Pfalzgraf (Decatur, IL), Leif Solheim (Decatur, IL), Scott Bloomer (Decatur, IL)
Application Number: 11/614,618
International Classification: C10L 5/00 (20060101);
