WO2006084048A1

WO2006084048A1 - Bio-diesel fuel and manufacture of same

Info

Publication number: WO2006084048A1
Application number: PCT/US2006/003703
Authority: WO
Inventors: Thomas J. Jalinski, Sr.
Original assignee: Jalin Technologies, Llc
Priority date: 2005-02-02
Filing date: 2006-02-02
Publication date: 2006-08-10

Abstract

A bio-diesel fuel including a fatty acid ester, and an acetal ester or ketal ester derived from glycerol is disclosed. A method for manufacturing a bio-diesel fuel is also disclosed, including the steps of transesterifying a glyceride such as vegetable oil to produce a mixture including fatty acid esters and glycerol, separating the glycerol from the mixture, converting the glycerol to either a ketal ester or an acetal ester, and combining the ketal ester or acetal ester with the fatty acid esters to produce a bio-diesel fuel.

Description

BIO-DIESEL FUEL AND MANUFACTURE OF SAME

CROSS-REFERENCE TO RELATED APPLICATION This international application claims the benefit of U.S. Provisional

Application No. 60/649,151, filed February 2, 2005, incorporated herein by reference.

FIELD OF THE INVENTION

The present invention relates generally to bio-diesel fuels, and more

particularly to a process for converting the waste glycerol generated by traditional transesterification processes into a miscible and combustible component of a bio-

diesel fuel.

BACKGROUND OF THE INVENTION

Bio-diesel fuels are becoming increasingly attractive because of their

environmental benefits, including the use of renewable and recyclable resources, such as either spent or unspent vegetable oils, to produce them. Thus far, however, the cost

of manufacturing bio-diesel fuels has proven to be a significant obstacle to their successful commercialization. One way to reduce the cost of manufacturing bio-

diesel fuels is to increase the efficiency of the process by converting the otherwise

wasted by-products into useable components of the bio-diesel fuel. Less starting

material is therefore required and the steps of handling and disposing of waste by¬

products are substantially eliminated.

The production of bio-diesel fuel from vegetable oil using a transesterification

process is a well known and common method for producing bio-diesel fuel. The

transesterification process, however, generates a significant amount of glycerol, also

known as glycerin, which constitutes a substantial percentage of the total product produced by the transesterification process and is the principal waste by-product that

cannot be used as fuel. Several attempts have been made to put the glycerol by¬

product to alternate use, thereby reducing the waste associated with the bio-diesel

manufacturing process. For example, it is well known that glycerol can be used in the

production of soaps, and new uses, like as a component in pig feed, have also been

contemplated and tested. Using the glycerol to produce other products like soap and

pig feed, though, requires the bio-diesel manufacturer to sell the glycerol or engage in

the manufacture of glycerol-containing products. Thus, the alternative processing of

glycerol is financially and technically burdensome and, for the most part, unattractive to the maj ority of manufacturers..

U.S. Patent Application Publication No. 2003/0167681 Al discloses a method

for converting the glycerol by-product into glycerol acetals, glycerol ketals, or glycerol acetates which can then be mixed with methyl or ethyl esters of fatty acids to produce

a bio-diesel fuel. This method allows at least a portion of the converted glycerol

products to be used as a component of the bio-diesel fuel. However, the acetals, glycerol ketals and glycerol acetates are characteristically volatile and, in addition, not wholly soluble in the fatty acid portion of the methyl or ethyl esters.

Given the limitations and problems with existing bio-diesel products and their

related manufacturing processes, there exists a need for a bio-diesel product that can

be produced using a method that eliminates or significantly reduces the amount of

glycerol by-product generated in the manufacturing process. SUMMARY OF THE INVENTION

The present invention provides a bio-diesel fuel and a method for

manufacturing a bio-diesel fuel in which the glycerol by-product is converted to a

useable fuel component and made part of the bio-diesel fuel. In one embodiment, the present invention provides a bio-diesel fuel including a fatty acid ester, and an acetal

ester or ketal ester of glycerol.

Accordingly, the invention provides in a first embodiment a bio-diesel fuel

that includes a fatty acid ester; and a glycerol derived acetal ester or ketal ester miscible in the fatty acid ester. The acetal ester or ketal ester is a combustible

component of the bio-diesel fuel. In certain diesel fuel compositions, the fatty acid ester has the structure:

wherein R¹ is a methyl or ethyl group and R² is a substituted or un-substituted Cn-Ci₉

alkyl or alkenyl group; and the acetal ester or ketal ester derived from glycerol has the structure:

wherein R and R are independently H or a substituted or un-substituted Ci-C]₃

aliphatic, unsaturated, or aromatic group, the combined number of carbon atoms between R³ and R⁴ not exceeding thirteen, and wherein R⁵ is a substituted or un-

substituted Ci-Cj₉ alkyl or alkenyl group.

In certain bio-diesel fuel compositions according to the invention, the ketal

ester has the structure:

Alternatively, a bio-diesel fuel composition according to the invention may include an acetal ester having the structure:

In yet another alternative formulation, a bio-diesel fuel composition according to the

invention includes a ketal ester having the structure:

In a second embodiment, the invention provides methods to manufacture the

bio-diesel fuel composition described and claimed herein. Such methods generally

include steps of transesterifying a glyceride, preferably vegetable oil, to produce a mixture including fatty acid esters and glycerol, separating the glycerol from the

mixture, converting the glycerol to either a ketal ester or an acetal ester, and

combining the ketal ester or acetal ester with the fatty acid esters to produce a bio- diesel fuel. All or substantially all of the glycerol is thereby converted into a fuel

component miscible in and combustible with the fatty acid esters.

Accordingly, a method for manufacturing a bio-diesel fuel according to the invention includes steps of: (a) transesterifying a glyceride to produce a mixture

including fatty acid esters and glycerol; (b) separating the glycerol from the mixture;

(c) converting the glycerol to an acetal ester or a ketal ester; and (d) combining the

acetal ester or ketal ester formed in step (c) with the fatty acid esters to provide the bio-diesel fuel.

In preferred methods, the glycerol in step (c) is converted to the acetal ester or the ketal ester by: (i) contacting the glycerol in step (c) with an acidic catalyst and an

aldehyde or ketone to form a corresponding acetal or ketal; and (ii) contacting the

glycerol in step (c) said corresponding acetal or ketal with a carboxylic acid to convert

the acetal or ketal to the corresponding acetal ester or ketal ester.

In certain methods for manufacturing diesel fuel compositions of the present invention, the fatty acid ester generated in the methods has the structure:

wherein R is a methyl or ethyl group and R is a substituted or un-substituted CH-C_I9

alkyl or alkenyl group; and the acetal ester or ketal ester derived from glycerol has the

structure:

wherein R³ and R⁴ are independently H or a substituted or un-substituted Cj-Ci₃ aliphatic, unsaturated, or aromatic group, the combined number of carbon atoms

between R³ and R not exceeding thirteen, and wherein R⁵ is a substituted or un-

substituted Ci -C ₁₉ alkyl or alkenyl group.

In certain preferred methods according to the invention, the ketal ester

generated in the method has the structure:

Alternatively, the acetal ester generated in the method has the structure:

In yet another alternative method, the method forms a ketal ester having the structure:

In certain methods, the manufacturing steps consist essentially of or consist only of the steps (a)-(d) described herein and recited in the appended claims.

The glyceride utilized in methods according to the invention is preferably a vegetable oil. Suitable vegetable oils include, but are not limited to, almond oil,

babassu oil, canola oil, corn oil, cottonseed oil, coconut oil, flaxseed oil, grape seed

oil, linseed oil, olive oil, palm oil, peanut oil, perilla oil, oiticica oil, safflower oil, sesame oil, soybean oil, sunflower oil, tung oil, walnut oil, and mixtures thereof.

The present invention provides significant advantages over previously described products and methods. Most significantly, the glycerol by-product becomes

a miscible and combustible component of the bio-diesel fuel, and thus does not need

to be sold or otherwise used to make other products. The conversion of the glycerol to acetal esters or ketal esters therefore provides a soluble additive to the fuel, which can

beneficially act as a water scavenger and/or source of oxygen.

Various other features, objects, and advantages of the invention will be made

apparent to those skilled in the art from the accompanying drawing and detailed

description thereof.

BRIEF DESCRIPTION OF THE DRAWING

FIG. 1 is a flow chart illustrating one embodiment of the steps involved in the

bio-diesel manufacturing process of the present invention. DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a bio-diesel fuel manufacturing process that

substantially eliminates the glycerol by-product produced in the traditional production

of bio-diesel fuel using the transesterification process. Once the glycerol is separated

from the bio-diesel, the glycerol can be further reacted to produce products that are

soluble in the bio-diesel and can thus be mixed in with the bio-diesel and combusted

together as fuel, In particular, the separated glycerol can be converted to an acetal

ester or a ketal ester, which are both soluble in the fatty acid portion of the bio-diesel fuel.

In general, the process of the present invention includes the transesterification

of glycerides, preferably triglycerides, and most preferably vegetable oil, to produce fatty acid esters and crude glycerol, also termed by-product or waste glycerol or glycerin. The terms glycerol and glycerin are used interchangeably herein.

Transesterification of triglycerides in the form of vegetable oil produces

approximately 80-90% fatty acid esters, typically ethyl esters or methyl esters, and

approximately 10-20% crude glycerol. The glycerol is then separated from the fatty

acid esters and further reacted to produce either a ketal ester or an acetal ester that is

mixed with the fatty acid esters to produce the resulting bio-diesel fuel product.

Accordingly, a method for manufacturing a bio-diesel fuel according to the

invention includes steps of: (a) transesterifying a glyceride to produce a mixture

acetal ester or ketal ester formed in step (c) with the fatty acid esters to provide the

bio-diesel fuel. In preferred methods, the glycerol in step (c) is converted to the acetal ester or

the ketal ester by: (i) contacting the glycerol in step (c) with an acidic catalyst and an aldehyde or ketone to form a corresponding acetal or ketal; and (ii) contacting the

the acetal or ketal to the corresponding acetal ester or ketal ester.

wherein R is a methyl or ethyl group and R² is a substituted or un- substituted Cn -C ₁₉ alkyl or alkenyl group; and the acetal ester or ketal ester derived from glycerol has the structure:

wherein R³ and R⁴ are independently H or a substituted or un-substituted Cj-Ci₃

aliphatic, unsaturated, or aromatic group, the combined number of carbon atoms

between R³ and R⁴ not exceeding thirteen, and wherein R⁵ is a substituted or un- substituted Ci -C ₁₉ alkyl or alkenyl group.

In certain preferred methods according to the invention, the ketal ester

generated in the method has the structure:

Alternatively, the acetal ester generated in the method has the structure:

In certain methods, the manufacturing steps consist essentially of or consist

only of the steps (a)-(d) described herein and recited in the appended claims.

A preferred method of producing bio-diesel fuel according to the present

invention is carried out substantially as described below and shown in FIG. 1. A

glyceride, preferably a vegetable oil 12, is mixed with an anhydrous aliphatic alcohol,

such as anhydrous methanol 10. As used herein, the term "vegetable oil" shall refer to

an oil extracted from the seeds, fruit, or nuts of plants. Many types of vegetable oils are suitable for use in the present invention, including but not limited to almond oil,

oil, linseed oil, olive oil, palm oil, peanut oil, perilla oil, oiticica oil, safflower oil, sesame oil, soybean oil, sunflower oil, rung oil, walnut oil, and mixtures thereof.

Glycerides of non- vegetable origin can also be used, including those present in animal

fats and lards. As well, suitable glycerides may be of either natural or synthetic origin.

Fatty acid components of suitable glycerides are in the Ci₂-C₂₀ range, more preferably

in the Ci₄-Cig range. While triglycerides are the preferred starting material, the present method is certainly applicable to di- or mono-glyceride starting materials

although one of skill will realize lesser stoichiometric yields of fatty acid esters relative to glycerol by-product upon use of such alternative glycerides. Even though

the production of methyl esters of fatty acids is described in the presently-described method, the production of other fatty acid ester derivatives, such as ethyl esters of

fatty acids, is certainly encompassed by the present invention as those alternative methods are substantially analogous to that described herein.

Referring again to FIG. 1, sodium metal in mineral oil 14 is slowly added to anhydrous methanol 16, resulting in a sodium methoxide, methanol, and mineral oil

mixture 18. The mineral oil 20 is separated from mixture 18, and the sodium

methoxide in methanol mixture 22 is added to reaction mixture 24. The reaction is

refluxed, forming a glycerol, methyl esters, excess methanol, and sodium methoxide

mixture 26. Next, mixture 26 is neutralized with concentrated sulfuric acid 28

dissolved in a small amount of anhydrous methanol, forming a glycerol, methyl esters,

methanol, and sodium sulfate mixture 30. The methanol 32 is then removed from

mixture 30 by distillation. The remaining methyl esters, glycerol and sodium sulfate products 34 are cooled and collected in a trap by suction and decanted to separate the

methyl esters 36 from the glycerol and sodium sulfate 38. The glycerol and sodium sulfate 38 are then vacuum filtered to separate the glycerol 40 from the sodium sulfate

42. Suitable reagents are known for carrying out transesterification reactions and

include, but not limited to, hydroxides of Li, Rb, Cs, Na and K, and alkoxides (e.g., methoxide or ethoxide).

The glycerol 40 is then mixed with sulfuric acid 44 and a ketone 46 such as

acetone or methyl ethyl ketone. Other acids and mixtures thereof (e.g., hydrochloric

acid and nitric acid), and other C₃-Ci₄ ketones or C_J-C_I4 aldehydes or mixtures thereof

may be used including substituted or un-substituted aliphatic, unsaturated or aromatic

carbonyl-containing molecules. As used herein, the term "substituted" in the context of a chemical moiety refers to the presence in that moiety of at least one heteroatom selected from halogen, nitrogen, sulfur and oxygen. Mixture 48 is refluxed until the

glycerol is dissolved in the ketone, forming a glycerol ketal, ketone, sulfuric acid, and

water mixture 50. Acetic acid 52 is then added to mixture 50 to produce a glycerol ketal, ketone, sulfuric acid, acetic acid, and water mixture 54. Other carboxylic acids

may be used including C₂-C₂₀ carboxylic acids which are branched or unbranched,

saturated or unsaturated, or substituted or un-substituted. Mixture 54 is refluxed to

form a glycerol ketal acetate (ester), excess ketone, sulfuric acid and water mixture 56.

Mixture 56 is neutralized with sodium hydroxide 58, resulting in a glycerol ketal

acetate (ester), ketone, water, and sodium sulfate mixture 60. Other neutralizing

agents can be used, including but not limited to calcium hydroxide and calcium

carbonate. Mixture 60 is vacuum filtered to separate the sodium sulfate 62 from the

glycerol ketal acetate (ester), ketone, and water mixture 64, and distilled to remove the water 66 and the ketone 46, which can be recycled and used at the beginning of the glycerol conversion process as shown. The remaining glycerol ketone acetate (ester)

68 is mixed with the methyl esters 36 to produce the bio-diesel fuel 70. Production of

bio-diesel with this protocol results in less settling out of solids and the glycerol

acetal/ketal ester products are more soluble in fossil fuels than are glycerine

acetal/ketal products that are produced by previous transesterification-based processes.

As can be appreciated, bio-diesel fuels provided by the methods described and claimed herein include a fatty acid ester, and a glycerol derived acetal ester or ketal

ester miscible in the fatty acid ester. The acetal ester or ketal ester forms a combustible component of the bio-diesel fuel. In certain diesel fuel compositions, the fatty acid ester has the structure:

wherein R is a methyl or ethyl group and R² is a substituted or un-substituted Cn -Cj g

wherein R³ and R⁴ are independently H or a substituted or un-substituted Ci-Ci₃

substituted Ci -C ₁₉ alkyl or alkenyl group.

In certain bio-diesel fuel compositions according to the invention, the ketal ester has the structure:

Alternatively, a bio-diesel fuel composition according to the invention may include an

acetal ester having the structure:

invention includes a ketal ester having the structure:

In addition, it should also be noted that prior bio-diesel processes which

convert glycerol to glycerol acetals, ketals or acetates which are returned to the bio-

diesel, result in a product in which the glycerol cetals, while being returned to the bio- diesel are not combustible and do not contribute to the energy production of the bio-

diesel. In contrast, the keto esters produced by the process disclosed herein are

soluble in fossil fuels including heating oil and kerosene. Consequently the glycerol

esters produced by the formula disclosed are, essentially, combustible in the bio-diesel

fuel adding to the energy production of the fuel. In addition, the bio-diesel produced

by the disclosed methods has a considerably lower gel point than do bio-diesels produced by other methods. This is particularly true for bio-diesel containing non-

esterified glycerol-cetals.

As can be appreciated, the present invention allows improved management of

waste and by-product problems associated with the manufacture of bio-diesel fuels. It is envisioned that such technological advantages may reduce the capitol necessary to

startup and maintain bio-diesel manufacturing plants by, for example, reducing the need to handle and dispose of large glycerin and waste water volumes. As a result,

bio-diesel manufacturing plants operating according to the present invention may provide the market with a quality bio-diesel product at lower cost while utilizing

environmentally friendly manufacturing processes.

The following examples illustrate the nature of the invention, but are not intended to limit the scope of the invention.

EXAMPLES

EXAMPLE 1 : Production of Bio-Diesel Fuel Containing Ketal Derived from

Glycerol

One gallon (3.8 liters) of generic brand vegetable oil was saturated with tap

water. Twenty-five grams of anhydrous sodium sulfate were added to the oil water

mixture contained in a 5-liter flask and the content vigorously shaken. The oil was then vacuum filtered through a course sintered glass filter and placed into a 10-liter

round bottom reaction flask. The flask was placed into a heating mantle and fitted with a top plus refluxing condenser. 2640 milliliters of dry methanol were added to

the oil. Five grams of sodium metal in 50% mineral oil were slowly added to 50

milliliters of methanol (Caution: exothermic reaction with release of hydrogen). The

sodium methoxide/methanol mixture was added to the oil/methanol. The temperature

was raised slowly to avoid bumping and the reaction mixture refluxed for three hours.

The reaction mixture was then cooled and 5.33 grams of sulfuric acid were added.

Excess methanol was removed by distillation.

One liter of acetone and 5 grams of toluenesulfonic acid were added to the

reaction mixture and it was refluxed for one hour. The acid catalyst was neutralized with sodium carbonate and the excess acetone plus water removed by distillation. The

reaction mixture was cooled and the bio-diesel decanted from the unreacted glycerol. The bio-diesel was vacuum filtered using a course sintered glass funnel. A red

colored product was formed containing methyl esters of fatty acids plus glycerol ketal.

EXAMPLE 2: Production of Bio-Diesel Fuel Containing Ketal Derived from Glycerol

One gallon (3.8 liters) of canola oil, along with 2640 milliliters of methanol

was placed into a 10-liter round bottom reaction flask. The flask was placed into a

heating mantle and fitted with a top plus refluxing condenser. Two and one-half

grams of sodium metal in 50% mineral oil were slowly added to 50 milliliters of

methanol (Caution: exothermic reaction with release of hydrogen). The sodium

methoxide/methanol mixture was added to the oil/methanol. The temperature was

raised slowly to avoid bumping and the reaction mixture refluxed for three hours. The reaction mixture was then cooled to ambient temperature and 2.67 grams of sulfuric acid were added. Excess methanol was removed by distillation.

The glycerol was separated from the bio-diesel by decanting. One liter of acetone and 5 grams of toluenesulfonic acid were added to the glycerol and the

mixture refluxed for one hour. The acid catalyst was neutralized with sodium

carbonate and excess acetone plus water removed by distillation. The reaction

mixture was cooled and the unreacted glycerol removed by decanting. The glycerol ketal product was added to the bio-diesel. An amber colored product is formed

containing methyl esters of fatty acids plus glycerol ketal.

EXAMPLE 3 : Production of Ketal Ester from Glycerol By-Product

To ten grams of glycerol in a 100 milliliter round-bottom flask, 35 milliliters of methyl ethyl ketone and 0.1 milliliters of concentrated sulfuric acid were added.

The mixture was refluxed until the glycerol was completely dissolved in the ketone

(30 to 45 minutes). The ketal product formed at this stage of the process was predicted to be:

An excess of glacial acetic acid was then added and the reaction refluxed for

30 minutes. The reaction mixture was neutralized with sodium bicarbonate, vacuum

filtered and distilled to remove excess ketone. The product was vacuum filtered. Gas chromatograph / mass spectrometry (GC/MS) analysis indicated that the major

product (-89%) formed using the process of this example is:

This ketal ester product is more soluble in the methyl fatty acid portion of the

bio-diesel than the corresponding ketal of glycerol (see Example 6) and is conveniently prepared using a one-pot synthesis.

EXAMPLE 4: Production of Acetal Ester from Glycerol By-Product Two hundred grams of glycerol, 72.5 grams of 90% paraformaldehyde and 0.5 grams of p-toluene sulfonic acid were mixed into a 500 milliliter round bottom flask.

The flask was fitted with a Dean-Stark trap and a refiuxing condenser and the reaction

mixture heated on a heating mantle until 39 milliliters of water was collected in the

trap. The formyl acetal derivative of glycerol product formed at this stage of the process was predicted to be:

To prepare the acetate ester, the Dean-Stark trap was removed and 130 grams

of glacial acetic acid was added to the formyl acetal derivative of glycerol. The

reaction mixture was then refluxed for 15 minutes. The catalyst was neutralized with sodium bicarbonate. The product was dried over anhydrous sodium sulfate and

vacuum filtered through a fritted glass filter. The resulting formyl acetal acetate

(ester) derivative of glycerol product was predicted to be:

This acetal ester product is more soluble in the methyl fatty acid portion of the

bio-diesel than the corresponding acetal of glycerol (see Example 6) and is conveniently prepared using a one-pot synthesis.

EXAMPLE 5: Production of Bio-Diesel Containing Ketal Ester Derived from

Glycerol By-Product

One gallon (3.8 liters) of vegetable oil was mixed with 2.84 liters of anhydrous

methanol into a 10-liter wide-mouth round-bottom flask fitted with a two-hole reactor cover and a refiuxing condenser. Five grams of 50% sodium metal in mineral oil

were slowly added to 60 milliliters of anhydrous methanol in a 250 milliliter beaker. The sodium methoxide formed by this reaction was added to the reaction mixture.

The beaker was rinsed with about 60 milliliters of anhydrous methanol and the alcohol

was added to the reaction mixture. The reaction was refluxed for three hours. The

reaction mixture was neutralized with concentrated sulfuric acid dissolved in a small

amount of anhydrous methanol. The methanol was then removed from the diesel fuel/glycerol mixture by

distillation. The reaction products were cooled and collected in a trap by suction.

Glycerol settled to the bottom and was separated from the diesel fuel.

The glycerol was mixed with one liter of acetone in a 2-liter flask. Two grams

of p-toluene sulfonic acid were added and the reaction was refluxed until the glycerol

was no longer separated from the acetone. The main product of this reaction was predicted to be:

The reaction mixture was neutralized with sodium bicarbonate and the acetone was removed by distillation. The ketal was then reacted with a carboxylic acid, acetic acid, (using p-toluene sulfonic acid) to make a ketal ester with the predicted formula:

This ketal ester product is predicted to be more soluble in the bio-diesel fuel

than the corresponding ketal product based on the analogous results of Example 6

below. By performing the process set forth in this example, substantially all the vegetable oil was converted to bio-diesel fuel. EXAMPLE 6: Comparative Solubility of Ketal/Acetal and Ketal/Acetal Esters

in Fatty Acid Ester

It is an objective of the present invention to convert glycerol by-product to an acetal ester or ketal ester instead of an acetal or ketal, as in certain previous

methodologies. The acetal and ketal ester derivatives are less volatile than the

corresponding acetals and ketals, and the acetal ester and ketal ester derivatives of

glycerol are more soluble in the fatty acid portion of the fatty acid esters than the corresponding acetals or ketals of glycerol. The solubility advantage is clearly borne

out in the following test results which were determined by the inventor. The tables

below show data indicating that exemplary acetal ester and ketal ester derivatives are multiple times more soluble in fatty acid esters than the corresponding acetals and

ketals at 17° Centigrade:

As a result, the present invention provides methodology by which substantially

all of the triglyceride mass is stoichiometrically-converted to combustible components

useable in a bio-diesel fuel. EXAMPLE 7: Production of Bio-Diesel from Soybean Oil.

Small scale production of bio-diesel from soybeans was accomplished as follows: One liter of virgin soybean oil was placed into a 2-liter round-bottom flask.

Enough saturated sodium hydroxide methanol solution was added to adjust the pH to 8.0 and the soybean saturated sodium hydroxide mixture was refluxed for five hours.

The mixture was cooled to ambient temperature and the bottom glycerin layer was

separated from the bio-diesel by drawing off the bio-diesel layer. The excess

methanol was removed from the bio-diesel by distillation. The bio-diesel was then

cooled and vacuum filtered through a sintered glass filter.

Large-scale production of Bio-Diesel from soybean oil may be carried out as

follows: 750 gallons of virgin soybean oil was added to a reactor. 18 oz of sodium hydroxide was dissolved into 112 gallons of methanol. Sodium hydroxide/methanol

solution was then added to the oil while agitating. The reaction mixture was refluxed for five hours. After reflux, the mixture was transferred to a settling tank and the

glycerin allowed to separate to the bottom. The bio-diesel product was then drawn off from the top of the settling tank. 18 oz of sodium hydroxide was dissolved into 75

gallons of methanol and added to the oil mixture while agitating. This solution was

refluxed for a further five hours. The reflux reaction mixture was then transferred to a

settling tank and the glycerin allowed to separate to the bottom. Resulting bio-diesel

was drawn off from the top of the settling tank. 18 oz of sodium hydroxide was

dissolved into 37 gallons of methanol and added to the oil mixture while agitating.

This solution was refluxed for a further five hours. The reflux reaction mixture was

then transferred to a settling tank and the glycerin allowed to separate to the bottom.

Resulting bio-diesel was again drawn off from a top layer. After the final separation of glycerin, the bio-diesel in total was returned to the reactor and the excess methanol was removed by distillation. The reaction mixture was cooled to ambient temperature

and filtered through an in-line filter. The by-product glycerin is now suitable to serve

as a starting material for the procedure of Example 8.

EXAMPLE 8: Manufacture of Soluble Ketal Acetate

The pH of 100 liters (26.42 gal) of glycerin/methanol mixture is adjusted, with

stirring, to between 7.0 and 6.0 with concentrated sulfuric acid with caution paid to

avoid splattering of the mixture. 200 liters (52.84 gal) of acetone is added to the

mixture followed by 400 ml of concentrated sulfuric acid. The mixture is heated slowly with stirring followed by one hour of refluxing. The catalyst is then

neutralized with sodium bicarbonate (baking soda) with caution paid to avoid foaming. The sodium bicarbonate is added until foaming ceases, requiring about 1.26

kg of baking soda. The sodium sulfate that is formed is allowed to settle to the bottom of the tank and the reaction mixture distilled to remove the excess acetone and

methanol. The soluble ketal acetate top liquid layer is removed from the bottom

sodium sulfate layer. The reactor is cleaned and dried and the soluble ketal acetate andlO9 liters (28.80 gal) of ethyl acetate is added to the clean dry reactor. The

reaction mixture is titrated with 25% sodium methoxide (in methanol) or a saturated

methanol solution of sodium hydroxide to a pH from between 8.0 to 9.0. The pH can

be checked with pH paper by adding a couple of drops of the reaction mixture to a

small amount of water. The reaction mixture should be maintained dry. The mixture

is then refluxed for two hours and the pH is re-checked to assure it is maintained at

8.0 or above. The mixture is then filtered and distilled to remove excess ethyl acetate, ethanol and methanol. The product may then be checked to confirm its solubility in a

fossil fuel, preferably kerosene.

A 50:50 mixture (volume/volume) of soluble ketal acetate and bio-diesel did

not cloud or gel at 8 degrees Fahrenheit. In comparison, the bio-diesel itself clouded

at 32 degrees Fahrenheit. The soluble ketal acetate, by itself, did not gel or freeze at

negative 18 degrees Fahrenheit. Finally, the cetane rating of bio-diesel containing

17% soluble ketal acetate (volume/volume) was determined by standard assay to be

83. In comparison, the cetane rating of the bio-diesel itself was determined by the same assay procedure to be only 60.

While the invention has been described with reference to preferred

embodiments, those skilled in the art will appreciate that certain substitutions, alterations and omissions may be made to the embodiments without departing from the spirit of the invention. Accordingly, the foregoing description and embodiments

discussed are meant to be exemplary only, and should not limit the scope of the

invention.

Claims

CLAIMSWhat is claimed is:

1. A bio-diesel fuel comprising:

(a) a fatty acid ester; and

(b) a glycerol derived acetal ester or ketal ester miscible in

^• the fatty acid ester wherein said acetal or ketal ester is a combustible

component of the bio-diesel fuel.

2. The bio-diesel fuel of claim 1, wherein:

(a) the fatty acid ester has the structure:

wherein R¹ is a methyl or ethyl group and R² is a substituted or

un-substituted C_{1 l}-C^ alkyl or alkenyl group; and

(b) the acetal ester or ketal ester derived from glycerol has

the structure:

wherein R³ and R⁴ are independently H or a substituted or un-

substituted Ci-Ci₃ aliphatic, unsaturated, or aromatic group, the

combined number of carbon atoms between R and R not exceeding

thirteen, and wherein R⁵ is a substituted or un-substituted Ci-Ci₉ alkyl or alkenyl group.

3. The bio-diesel fuel of claim 2, wherein the ketal ester has the structure:

4. The bio-diesel fuel of claim 2, wherein the acetal ester has the structure:

5. The bio-diesel fuel of claim 2, wherein the ketal ester has the structure:

6. A method for manufacturing a bio-diesel fuel comprising the

steps of: (a) transesterifying a glyceride to produce a mixture including fatty acid esters and glycerol;

(b) separating the glycerol from the mixture;

(c) converting the glycerol to an acetal ester or a ketal ester;

and

(d) combining the acetal ester or ketal ester formed in step

(c) with the fatty acid esters to provide the bio-diesel fuel.

7. The method according to claim 6, wherein said glycerol in step

(c) is converted to the acetal ester or the ketal ester by:

(i) contacting the glycerol in step (c) with an acidic catalyst

and an aldehyde or ketone to form a corresponding acetal or ketal; and (ii) contacting the glycerol in step (c) said corresponding

acetal or ketal with a carboxylic acid to convert the acetal or ketal to the corresponding acetal ester or ketal ester.

8. The method according to claim 6, wherein the fatty acid ester has the structure:

wherein R¹ is a methyl or ethyl group and R² is a substituted or

un-substituted Cn -C ₁₉ alkyl or alkenyl group; and said glycerol in step (c) is converted to the acetal ester or the

ketal ester having the structure:

wherein R³ and R⁴ are independently H or a substituted or un-

substituted Cj-Cj₃ aliphatic, unsaturated, or aromatic group, the

combined number of carbon atoms between R³ and R⁴ not

exceeding thirteen, and wherein R⁵ is a substituted or un-substituted C₁-C)₉ alkyl or alkenyl group.

9. The method of claim 8, wherein the ketal ester has the structure:

10. The method of claim 8, wherein the acetal ester has the

structure:

11. The method according to claim 8, wherein the ketal ester has

the structure:

12. The method of according to claim 6, wherein the method consists essentially of the steps (a)-(d).

13. The method according to claim 6, wherein the glyceride is a vegetable oil.

14. The method according to claim 13, wherein the vegetable oil is

selected from the group consisting of almond oil, babassu oil, canola

oil, corn oil, cottonseed oil, coconut oil, flaxseed oil, grape seed oil,

linseed oil, olive oil, palm oil, peanut oil, perilla oil, oiticica oil, safflower oil, sesame oil, soybean oil, sunflower oil, tung oil, walnut

oil, and mixtures thereof.

15. A bio-diesel fuel manufactured in accordance with the process

of claim 6.

16. A bio-diesel fuel manufactured in accordance with the process

of claim 8.