WO2013122599A1 - Enzymatic production of monoglycerides - Google Patents

Abstract

Systems and methods related to the enzymatic production of high purity monoglycerides are described. In certain embodiments, a monoglyceride can be produced by reacting a fatty acid alkyl ester or a carboxylic acid with glycerol, in the presence of a lipase. In some embodiments, one can tailor the operating conditions of the system such that large amounts of monoglycerides are produced, relative to the trace amount of diglycerides and triglycerides that are produced. For example, in certain embodiments, the system can be operated such that the reaction solution does not undergo phase separation throughout the reaction. In some embodiments, the concentration of the monoglyceride within the reactor is substantially fixed at each position in the reactor as a function of time throughout a substantial portion of the reaction. In certain embodiments, one or more recycle streams can be used to transport a monoglyceride and/or unreacted reactant upstream to a reactor, which can lead to a reduction in reaction number.

Description

ENZYMATIC PRODUCTION OF MONOGLYCERIDES

TECHNICAL FIELD

Systems and methods related to enzymatic production of monoglycerides are generally described.

BACKGROUND

Monoglycerides, whether in the form of mixtures or as a high purity composition, have been widely used in food, cosmetic and pharmaceutical industries. Highly pure monoglycerides are potentially attractive starting materials for different applications. They can be used in drug delivery, textile and fiber processing and biobased plastics. For example, to produce resin, they can react with maleate half esters or maleic anhydride to form monomers. They are also attractive intermediates for the synthesis of more complex lipids like selectively functionalized triglycerides, glycolipids or phospholipids.

Unfortunately, high purity monoglyceride has not been accessible industrially in high yield. The high prices of high purity monoglycerides limit their large-scale applications. Accordingly, a cost-effective mass production process for high purity monoglycerides manufacturing is very desirable.

Monoglycerides can be produced through the following types of reactions:

Esterification of glycerol with fatty acid

FFA + Glycerol MG + H₂0 [1]

Transesterification of triglyceride (i.e., oil) with glycerol

Triglyceride + Glycerol MG + DG [2-1] DG + Glycerol = 2MG [2-2]

Transesterification of fatty acid alkyl ester with glycerol

Fatty Acid Alkyl Ester (i.e., RCOOR') + Glycerol = MG + R'OH [3] In the above-mentioned reactions, "FFA" corresponds to a free fatty acid, "MG" corresponds to monoglycerides, "DG" corresponds to diglycerides, and R'OH

corresponds to alcohols (e.g., primary or secondary alcohols).

Currently, most manufacturing processes for the preparation of monoglycerides involve glycerolysis esterification with the use of acid catalysts, such as sulfuric acid, phosphoric acid or organo- sulfonic acids. The main drawbacks of these processes include (i) having a product that is a mixture of mono-, di- and triglyceride, which requires further downstream separations to result in high purity monoglycerides, and (ii) the generation of waste chemicals with regard to the removal of catalyst.

Chemical transesterification of triglyceride and glycerol is normally operated from 210°C to 240°C. This method, however, cannot be applied to the synthesis of monoglyceride with unstable fatty acids. The product is likewise a mixture of mono- and diglyceride. Though it is possible to separate both products via use of a short-path evaporator (i.e., molecular distillation), the process needs to be operated under extremely low pressure, e.g., 0.001 torr. Even then, the product purity is still insufficiently high. For example, a typical product might consist of 94.2% monoglycerides, 3.6%

diglycerides, and others. If separation is done at higher pressures, undesirable products are formed. Similar problems have been documented for the chemical transesterification of fatty acid alkyl ester with glycerol.

The enzymatic approach is more desirable since it can be carried out in an environmentally friendly manner using mild operating conditions, e.g., <60°C or 80°C generally, and results in a specific product distribution. Though enzymatic production of highly pure monoglycerides has been done, the process still suffers from low overall yield and the use of high-priced raw materials. A drawback similar to the one addressed above (i) is encountered in the chemical approach (i.e. limited to non-enzymatic chemical reactions) when triglyceride undergoes glycerolysis transesterification.

Therefore, a cost-effective process for obtaining highly pure monoglycerides with high selectivity and high overall yield, especially based on value- optimized raw materials, is still unavailable.

Similar to the chemical approach, most enzymatic methods for producing monoglycerides in the prior art focus on the first two types of reactions. Relatively few mention the use of glycerolysis transesterification for fatty acid alkyl ester. Since pure fatty acid and pure glycerol are both high-priced raw materials, monoglycerides produced through glycerolysis esterification are expensive, aggravated further by the fact that overall yield is low.

To improve product selectivity, employment of inert solvent in reactions has been proposed. Though it has been mentioned in French Patent Publication FR 2617501 that monoglycerides can be produced with high selectivity via a glycerolysis esterification reaction in a i-amyl alcohol solvent, this publication is silent regarding whether glycerolysis transesterification of fatty acid alkyl ester in tertiary alcohol can produce similar products. Furthermore, this publication does not describe how to obtain a high purity monoglyceride product. In fact, monoglyceride concentrations in the final product greater than 44.7 mol are not described.

European Patent Application Publication EP 0407959A2 includes examples related to the production of monoglycerides via glycerolysis esterification of fatty acid and via glycerolysis transesterification of fatty acid alkyl ester in tertiary alcohol.

Although high reaction conversions were shown in this publication, there was no indication that high selectivity could be achieved.

SUMMARY

Contrary to the above described conventional approaches, fatty acid alkyl ester and pure glycerol can now be produced economically through an enzymatic approach that was invented by Chou (see commonly owned US patent no. 7473539B2, which is incorporated herein by reference). This is especially true when the oil feedstock employed comes from a low-priced oil source, such as oils with high free fatty acids (FFA) (e.g. 10 wt - 15 wt FFA) and non-edible oils from Jatropha, or other similar oil sources. This can allow fatty acid alkyl ester and glycerol products to become more competitive feedstocks for monoglyceride production. Furthermore, separation of fatty acid alkyl esters by fractional distillation is often relatively easy compared to separation of fatty acids. This means that using each specialty (or neat) fatty acid ester as the starting material to tailor-make the monoglyceride end-product to the exact end-use requirement becomes relatively easy and economical. Examples of high purity specialty products include glycerol monostearate, an emulsifier in food, oil and wax industries; glycerol monooleate, a surfactant used in food, pharmaceuticals and cosmetics; glycerol monolaurate, an emulsifying and dispersing agent in food, oils, waxes and solvents; glycerol monocaprate, a product useful for medical purposes or as an anti-bacterial additive in food; and glycerol monoricinoleate, a non-drying emulsifying agent, plasticizer and solvent used in cosmetics, textiles and paper and leather processing.

Enzymatic production of monoglycerides, and associated systems and methods, are described. In particular, in one aspect of the invention, a process based on glycerolysis transesterification of fatty acid alkyl ester or glycerolysis esterification of carboxylic acid (e.g., fatty acid) that can produce monoglycerides with relatively high purity and relatively high selectivity are described. That is to say, in certain aspects of the invention, methods for producing monoglycerides at high overall yields are described.

The subject matter of the present invention involves, in some cases, interrelated products, alternative solutions to a particular problem, and/or a plurality of different uses of one or more systems and/or articles.

In one aspect, a method for producing a high purity monoglyceride product is provided. In certain embodiments, the method comprises mixing a fatty acid alkyl ester and glycerol in an organic solvent to form a solution, wherein each molecule of the organic solvent contains 4-8 carbon atoms and a heteroatom. The method comprises, in certain embodiments, reacting the fatty acid alkyl ester with glycerol in the presence of a lipase within a plug flow reactor to produce a reaction mixture comprising the monoglyceride product. In some embodiments, the solution does not undergo phase separation throughout the reaction, an alcohol is produced as a byproduct of the reaction, and the product selectivity of monoglyceride is at least 95%, by weight.

In some embodiments, the method comprises mixing a carboxylic acid and glycerol in an organic solvent to form a solution, wherein each molecule of the organic solvent contains 4-8 carbon atoms and a heteroatom. The method comprises, in certain embodiments, reacting the carboxylic acid with glycerol in the presence of a lipase within a plug flow reactor to produce a reaction mixture comprising the monoglyceride product. In certain embodiments, the solution does not undergo phase separation throughout the reaction, and water is produced as a byproduct of the reaction. In some embodiments, the method comprises removing at least a portion of the water from the reaction mixture during the reaction and/or before any subsequent reaction, and separating the monoglyceride product from the reaction mixture.

In some embodiments, a method for producing a monoglyceride product is described. The method comprises, in some embodiments, introducing a mixture comprising a fatty acid alkyl ester and/or a carboxylic acid, glycerol and an organic solvent into a plug flow reactor; reacting the fatty acid alkyl ester and/or the carboxylic acid with glycerol in the presence of a lipase within the plug flow reactor to produce a reaction mixture comprising the monoglyceride product; and recycling at least a portion of the reaction mixture back into the plug flow reactor after removal of at least a portion of the alcohol and/or water. In another aspect, systems for producing a monoglyceride product are described. The systems can be used to produce a monoglyceride product according to any of the methods described herein, including those outlined above.

In certain systems and methods, including those described above, the product selectivity of monoglyceride can be high (e.g., at least about 95%, by weight). In addition, in some embodiments, the systems and methods described herein, including those described above, can be used to produce a high-purity monoglyceride product, for example, without the need for separation of the monoglyceride from non-alcohol and/or non-water components (e.g., diglycerides, triglycerides, and/or reactants).

Other advantages and novel features of the present invention will become apparent from the following detailed description of various non-limiting embodiments of the invention when considered in conjunction with the accompanying figures. In cases where the present specification and a document incorporated by reference include conflicting and/or inconsistent disclosure, the present specification shall control.

BRIEF DESCRIPTION OF THE DRAWING

Non-limiting embodiments of the present invention will be described by way of example with reference to the accompanying figures, which are schematic and are not intended to be drawn to scale. In the figures, each identical or nearly identical component illustrated is typically represented by a single numeral. For purposes of clarity, not every component is labeled in every figure, nor is every component of each embodiment of the invention shown where illustration is not necessary to allow those of ordinary skill in the art to understand the invention. In the figures:

FIG. 1 is a schematic diagram of a monoglyceride production process, according to one set of embodiments;

FIG. 2 is, according to certain embodiments, a schematic diagram of a monoglyceride production process; and

FIG. 3 is an exemplary schematic diagram of a separator, used in association with one set of embodiments.

DETAILED DESCRIPTION

Systems and methods related to the enzymatic production of monoglycerides are described. In certain embodiments, a monoglyceride can be produced by reacting a fatty acid alkyl ester or a carboxyilic acid with glycerol. The reactants can be mixed in a solvent (e.g., an organic solvent containing molecules with 4-8 carbon atoms and a heteroatom), in some embodiments, to form a solution. The solution can then be transported to a suitable reactor, such as one or more plug flow reactors. A lipase can be included in the reactor to catalyze the reaction between the fatty acid alkyl ester or carboxylic acid and glycerol. For example, a lipase can be immobilized on a carrier and added to the reactor to catalyze monoglyceride production.

In some embodiments, one can tailor the operating conditions of the system such that large amounts of monoglycerides are produced, relative to the trace amount of diglycerides and triglycerides that are produced. For example, in certain embodiments, the system can be operated such that the solution does not undergo phase separation throughout the reaction. In some embodiments, the concentration of the monoglyceride within the reactor is substantially fixed at each position within the reactor as a function of time throughout a substantial portion of the reaction (e.g., throughout at least about 75%, at least about 90%, at least about 95%, or at least about 99% of the time during which the reaction occurs). In certain embodiments, one or more recycle streams can be used to transport a monoglyceride and/or unreacted reactant to an upstream reactor or an upstream portion of a single reactor, which can lead to reduction in reactor number.

In certain embodiments, the systems and methods described herein can produce a high purity monoglyceride product having, for example, a monoglyceride component present in an amount of at least about 90 wt%, at least about 95 wt%, at least about 99 wt%, at least about 99.8 wt%, or at least about 99.9 wt%. In certain embodiments, the high purity monoglyceride product can be produced using a single reactor and/or a single separator, sometimes without the need for subsequent separation of monoglyceride from diclyceride(s) and/or triglyceride(s).

FIG. 1 is a schematic illustration of an exemplary, non-limiting monoglyceride production system 100, which can be used to carry out various processes described herein. In FIG. 1, a fatty acid alkyl ester or carboxylic acid (e.g., fatty acid) reactant is provided in stream 110. In addition, a glycerol reactant can be provided via stream 112. An inert solvent (e.g., an anhydrous organic solvent) can be provided in stream 114. The contents of input streams 110, 112, and 114 can be combined to form a solution within stream 116. In certain embodiments, the contents of stream 116 are mixed to form a one-phase solution. In some embodiments, the contents of stream 116 are such that the reaction solution does not undergo phase separation throughout the reaction (i.e., the solution remains substantially homogeneous throughout all reactors). This can be achieved, for example, by selecting one or more suitable solvents and adding those solvents in an amount sufficient to achieve substantially complete miscibility of the reactant components.

Typically, the amount of glycerol reactant in stream 116 is about 10-50 mol in excess of the stoichiometric amount required for the complete conversion of the fatty acid alkyl ester or carboxylic acid (e.g., fatty acid) reactant.

The organic solvent within stream 116 can be mixed with other suitable solvents, in certain embodiments. In certain embodiments, the organic solvent can be mixed with monoglyceride, which can originate from elsewhere in the process (e.g., from an optional recycle stream(s), e.g. 149, 151 as described in more detail below) or from other sources (e.g., purchased from a commercial source). In preferred embodiments, when organic solvent is used together with another solvent, it is added in an amount sufficient to maintain the homogeneity of the solution during the reaction, thereby minimizing inactivation of catalysts (e.g., lipases) in the reactors. In certain embodiments, the type(s) and/or amount(s) of solvent(s) added to the reactant composition can be selected and adjusted such that the resulting reactant composition does not phase separate during essentially the entirety of the reaction. In certain embodiments, avoiding phase separation during the reaction step can ensure that the lipase or lipases are not deactivated (e.g., by glycerol) during the reaction. One of ordinary skill in the art, given the present disclosure, would be capable of selecting an appropriate amount and type of solvent(s) for use in a particular reaction system, for example, by adding a solvent to the components to be reacted and ensuring that phase separation does not occur.

In the set of embodiments illustrated in FIG. 1, the solution in stream 116 is mixed well before it is sent to downstream unit operations. Mixing of the components in stream 116 can be achieved using any method known to those of ordinary skill in the art. For example, the components can be transported to a mixing tank (not illustrated in FIG. 1), where they can be mixed prior to being transported to downstream unit operations. In some embodiments, a standalone mixing unit operation is not used. For example, baffles, stirrers, or other in-line mixing apparatus can be integrated directly into the conduit through which the components are transported. The reaction components in stream 116, after the optional mixing step, are transported to reactor 118. In certain embodiments, reactor 118 is a plug flow reactor. For example, reactor 118 can comprise a packed bed reactor. In certain embodiments, the plug flow reactor is operated such that the concentration of monoglyceride within the reactor is fixed uniformly (i.e., it does not significantly vary with time) throughout a substantial portion of the reaction.

In certain embodiments, a lipase can be used as a catalyst in the

transesterification of fatty acid alkyl ester and/or in the esterification of carboxylic acid (e.g., fatty acid) with glycerol. The term "lipase" refers to any enzyme capable of catalyzing a transesterification or esterification reaction. Examples include Candida antarctica lipase, thermomyces lanuginosa lipase, pseudomonas fluorescens lipase, Burkholderias cepacia lipase, chromobacterium viscosum lipase, pseudomonas sp.

lipase, aspergillus oryzae lipase, aspergillus niger lipase or rhizopus niveus lipase.

Additional examples of suitable lipases include phospholipases such as phospholipase Al (PLA1), phospholipase A2 (PLA2), phospholipase C (PLC), and/or phospholipase D (PLD). The lipase can include a single lipase or a combination of two or more lipases. In some embodiments, the lipase is immobilized on a carrier in the reactor. In certain embodiments, two or more different immobilized lipases can be employed in the reactor. To obtain immobilized lipase, one or more types of lipase can be attached to a suitable carrier by adsorption or other methods well-known in the art. Examples of such methods are described, for example, in Applied Biocatalysis, edited by A.J.J. Straathof and P. Adlercreutz, Harwood Academic Publishers, pp.217-219, 2^nd ed. (2000). Generally, a suitable carrier is one that does not substantially inhibit the activity of the enzyme immobilized on it. The carrier, with the lipase attached, can be placed in reactor 118 (and/or other reactors used in system 100, such as fixed bed reactors).

After the reaction is carried out in reactor 118, a monoglyceride-containing reaction mixture is produced, which can be transported out of reactor 118 via stream 120. Unexpectedly, the systems operated as described herein are capable of producing monoglyceride-containing compositions with high selectivity toward the monoglyceride. For example, the product can comprise large amounts of the monoglyceride (e.g., at least about 50 wt , at least about 60 wt , at least about 70 wt , at least about 80 wt , or at least about 90 wt%), a trace amount of diglyceride (e.g., less than about 1 wt , less than about 0.1 wt%, or less), and an insignificant amount of triglyceride (e.g., less than about 1 wt%, less than about 0.1 wt%, less than about 0.01 wt%, or less).

In some embodiments, the amount of monoglyceride in the reaction product can be relatively high relative to the amount of diglyceride and/or triglyceride in the reaction product. For example, in certain embodiments, the weight ratio of monoglyceride to diglyceride in the reaction product from the first reactor (or any subsequent reactor) within the system can be at least about 25: 1, at least about 50: 1, at least about 75: 1, at least about 90: 1, at least about 95: 1, at least about 99: 1, or at least about 99.9: 1. In some embodiments, the weight ratio of monoglyceride to triglyceride in the reaction product from the first reactor (or any subsequent reactor) within the system can be at least about 25: 1, at least about 50: 1, at least about 75: 1, at least about 90: 1, at least about 95: 1, at least about 99: 1, at least about 99.9: 1, or at least about 99.99: 1.

The systems and methods described herein can be used to achieve relatively high product selectivities of monoglyceride. As used herein, the "product selectivity of monoglyceride" is expressed as a percentage and is calculated by dividing the mass of monoglyceride in the reaction product by the sum of the masses of monoglyceride, diglyceride, and triclygeride in the reaction product, and multiplying by 100%. The product selectivity of monoglyceride (SMG) ^can be expressed as a mathematical formula as follows:

^{¾C =} (m_{MG + moG + mrc)} ^{X l00%}

wherein m_MG is the mass of monoglyceride in the reaction product, m_DGis the mass of diglyceride in the reaction product, and m_TG is the mass of triglyceride in the reaction product. The product selectivity of monoglyceride is calculated before any post-reaction separation of the monoglyceride, diglyceride, and triglycerides is performed, and therefore represents the amount of monoglyceride produced during the reaction relative to the amounts of di- and triglycerides produced during the reaction.

In certain embodiments, the systems and methods described herein can achieve a product selectivity of monoglyceride of at least 95%, at least 98%, at least 99%, or at least 99.9%, by weight.

In certain embodiments, reaction product mixture also includes an alcohol co- product (e.g., when glycerol is reacted with a fatty acid alkyl ester), or water (e.g., when glycerol is reacted with a carboxylic acid). When alcohol co-products are produced, the type of alcohol produced varies with the kind of fatty acid alkyl ester used as a reactant. In certain embodiments, the alcohol co-product can comprise a primary or a secondary alcohol with 1-8 carbon atoms, such as methanol, ethanol, w-propanol, isopropanol, n- butanol, isobutanol, w-pentanol, isopentanol, neopentanol, 3-methyl-l-butanol, n- hexanol, 1-octanol, 2-octanol and so on.

In certain embodiments, during and/or after the reaction step has been performed, the alcohol and/or water can be separated from other components of the reaction mixture. In FIG. 1, reaction mixture 120 is transported to separator 122. In certain embodiments, at least a portion of the alcohol and/or water can be removed from the reaction product while the reaction step is being performed (e.g., directly from reactor 118), for example, by using a membrane separator integrated with the reactor, as described below. In separator 122, alcohol and/or water can be separated from the monoglyceride, unreacted reactant (e.g., glycerol and carboxylic acid or fatty acid alkyl ester), and/or solvent in reaction output 120. The alcohol and/or water can be transported away from separator 122 via stream 124. The monoglyceride, unreacted reactant, and/or solvent can be transported from separator 122 via stream 126. Separator 122 can comprise any suitable unit operation known to those of ordinary skill in the art. For example, separator 122 can comprise an evaporator, a distillation column, a stripping column, a membrane unit, a regenerative adsorber (e.g., using resins or molecular sieves), or any other suitable type of separator.

In certain embodiments, removal of alcohol (R'OH) or water can be carried out in an evaporator, where it can be optionally stripped with nitrogen or deaerated superheated steam. The reaction output may be heated first before it is sent to the evaporator. In certain embodiments, the evaporator can be operated in ambient or vacuum pressure, depending on the alcohol or water byproduct and organic solvent used in the reaction. The evaporator can be a thin film evaporator, a falling film evaporator, a column evaporator, a short-path evaporator or any other suitable evaporator known in the art. Typically, the temperature in the evaporator is lower than 120°C. Water, either contained in the fatty acid alkyl ester, carboxylic acid (e.g., fatty acid) or organic solvent, or co-produced during the reaction, is generally removed along with alcohol. The water and alcohol can be collected and separated in a recovery unit, which can consist of liquid separation or removal units. Water can be discharged, for example, after being treated in a water treatment facility. Alcohol can be purified and sold as a co-product, in some embodiments.

Alternatively, when the alcohol byproduct is of low carbon number (e.g., methanol), the alcohol (as well as water, if present) can be removed using a suitable, selective membrane apparatus. For example, a selective membrane apparatus employing pervaporation or vapor permeation can be employed. In some such cases, it is possible to remove the alcohol and/or water by-product during the reaction rather than at the reaction outlet. For example, rather than employing a standalone separator, a portion or all of a reaction wall can be formed of a suitable, selective membrane material that would allow the alcohol (e.g., methanol) and/or water to permeate the membrane wall while retaining the other reaction products (and solvent, when present).

In some embodiments in which only a water co-product is produced (e.g., when carboxylic acids, rather than fatty acid alkyl esters, are used as the starting reactant), the water co-product can be removed via adsorption (e.g., using resins or molecular sieves) or by any other methods known to those of ordinary skill in the art.

In some embodiments, the portion of the reaction product in stream 126 can be subjected to further reaction steps to produce monoglyceride in even higher

concentrations. In FIG. 1, for example, after alcohol or water is removed, the solution in stream 126 is sent to second reactor 128, where higher purity monoglyceride is produced. The monoglyceride can be produced by reacting the unreacted glycerol and fatty acid alkyl ester and/or carboxylic acid contained in stream 126. It has been unexpectedly discovered that, by using multiple reactors, a product distribution with high selectivity toward monoglyceride is achieved. For example, in FIG. 1, reactor 128 can be used to produce a second reaction product stream 130, which contains a relatively higher amount of monoglyceride than that of inlet stream 126.

Normally, no further glycerol and organic solvent are added to the output from the first reactor 118 before it is transported to the second reactor. To accelerate the reaction in the second reactor, however, glycerol and/or organic solvent can be optionally added, provided that the reaction solution remains homogeneous throughout the reaction.

Reactor 128 can be operated in a similar manner as reactor 118, in certain embodiments. For example, reactor 128 can comprise a plug flow reactor (e.g., a packed bed reactor). A lipase enzyme (e.g., immobilized on a support) can be used as a catalyst in reactor 128. When a lipase is employed in reactor 128, the lipase can be the same as or different from the lipase that is employed in reactor 118. In certain embodiments, reactor 128 can also be operated such that the concentration of the monoglyceride within reactor 128 does not significantly vary as a function of time during the a substantial portion of the reaction.

During and/or after the reaction step in reactor 128 has been performed, the alcohol and/or water can be separated from other components of the reaction mixture, for example, similar to the separation performed during and/or after reaction in reactor 118 (e.g., using separator 122). For example, in FIG. 1, reaction output 130 can be transported to separator 132. In separator 132, alcohol and/or water can be separated from the monoglyceride, unreacted reactant (e.g., glycerol and carboxylic acid or fatty acid alkyl ester), and/or solvent in reaction output 130. The alcohol and/or water can be transported away from separator 132 via stream 134. The monoglyceride, unreacted reactant, and/or solvent can be transported from separator 132 via stream 136. Like separator 122, separator 132 can comprise any suitable unit operation known to those of ordinary skill in the art.

After removal of alcohol and/or water in separator 132, additional reactions can be performed using additional reactors operated, for example, in a manner similar to the operation of reactors 118 and/or 128. Any number of reactors can be used to produce a final product including the desired amount and/or proportion/purity of monoglyceride. For example, in certain embodiments, 2 or more, 3 or more, 4 or more, 5 or more, 6 or more, or 10 or more reactors are employed. When lipases are employed, each reaction bed can make use of the same lipase or a different lipase. In certain embodiments, one or more reactors can include a single type of lipase or a combination of different lipases.

When a monoglyceride-containing product with a desired monoglyceride concentration is obtained, the reaction outlet is transported to one or more separators to separate the monoglyceride portion of the reaction product from the rest of the reaction product. For example, in FIG. 1, stream 138 (which can include the contents of stream 136 or another stream originating from another reactor) is transported to separator 140. Separator 140 can comprise, for example, a vacuum evaporator, where alcohol, inert solvent and/or water, if any, are evaporated. Of course, the invention is not limited to the use of vacuum separators, and in other embodiments, other types of separators suitable for removing water, alcohol(s), and or solvent from the reaction mixture can be employed. Alcohol, water, and/or solvent can be removed from separator 140 via stream 142. The residue, which comprises monoglyceride and glycerol can be transported out of separator 140 via stream 144. The mixture of monoglyceride and glycerol in stream 144 can be further separated in separator 146. Separator 146 can comprise any suitable type known to those of ordinary skill in the art. In certain embodiments, separator 146 comprises an evaporator. In some embodiments, separator 146 comprises an

evaporator/stripper that combines evaporation and stripping into a single operation wherein the evaporator is similar to those described above). Separator 146 can also comprise a column operated under high vacuum or any other suitable design known to those of ordinary skill in the art.

High purity monoglyceride, transported from separator 146 via stream 148, can be obtained as a product without the need for further treatment. Such monoglycerides can be useful, for example, in emulsifier and/or lubricant applications. Alternatively, stream 148 can be sent further downstream for further purification in one or more additional separators, if desired. In particular, the monoglyceride product might contain a certain quantity of unreacted fatty acid ester, FFAs, and/or organic solvent, at levels which may be undesirable for certain applications. Purification of the final

monoglyceride-containing product can be achieved by conventional techniques known to those of ordinary skill in the art, such as alkali treatment, evaporation, recrystallization for higher purity, solvent fractionation, adsorption, chromatography, and the like.

Glycerol, which can be transported from separator 146 via stream 150 in FIG. 1, can be recycled to the feedstock for further use.

In certain embodiments, at least a portion of the reaction product, after the removal of alcohol or water, can be recycled back to one of the reactor inlets. In certain cases, by recycling the reaction product stream(s), the number of reactors within the system can be reduced while still producing relatively high concentrations of

monoglyceride and maintaining the high selectivity of the system. The recycling stream can be withdrawn from the outlet of the separator (i.e., after alcohol or water removal) immediately downstream of the first reactor (i.e., recycle stream 149 from separator 122 in FIG. 1) or immediately downstream of the second reactor (i.e., recycle stream 151 from separator 132 in FIG. 1).

It should be noted that recycled components can originate from any reactor outlet and be forwarded to any of the upstream inlets. For example, in certain embodiments, the recycling stream can originate from the first outlet (i.e., stream 149) and be transported to the first inlet (i.e., stream 116). In some embodiments, the recycling stream can originate from the second outlet (i.e., stream 151) and can be transported to the second inlet (i.e., stream 126). In still other embodiments, the recycling stream can originate from the second outlet (i.e., stream 151) and can be transported to the first inlet (i.e., stream 116). In certain embodiments, each reactor is configured to receive a maximum of only one recycle stream, and mixing of multiple recycle streams is avoided. The system design is generally flexible and may be adjusted according to the preferred reaction characteristics and process design requirements. For example, if the last reactor in a series of reactors includes the slowest reaction step, then the reaction stream output from the last reactor (after the removal of alcohol or water) can be recycled back to the inlet of the last reactor to increase the concentration of monoglyceride at the inlet of the last reactor, thereby allow the final purity to be achieved in a single step.

The flexibility of the system also allows one to design the system such that a side product can be withdrawn from any reactor outlet after alcohol or water removal.

Various side products drawn from various intermediate reactors can include different grades of monoglycerides. For example, in one set of embodiments, side-drawn products can include grades 40 wt , 60 wt and 90 wt monoglyceride. In other applications, different concentrations can be obtained, depending on the application. Examples include 37 wt - 42 wt glycerol monooleate, which can be used as anti-fogging agent in the low-density polyethylene (LDPE), polypropylene (PP), and/or polyvinyl chloride (PVC) industries; 60 wt monoglyceride, which can be used as a food additive in margarines and ice cream; 90 wt monoglyceride, which can be used as a food additive in dough; and 90 wt glycerol monostearate, which can be used as an anti-static agent in the production of LDPE, PP, PVC, acrylonitrile butadiene styrene (ABS), and the like, or as an internal lubricant for rigid PVC.

In many cases, when the monoglyceride is recycled, the associated inert solvent and glycerol are recycled as well. In certain embodiments, inert solvent (which can be lost due to alcohol or water removal) is replenished before adding the recycled reaction product stream to a reactor. In some such embodiments, the composition of the feedstock of each reactor is adjusted and/or controlled such that the reaction solution is in a homogeneous state at all times, even in the presence of the recycling stream. In some embodiments, supplemental glycerol can be added (along with the addition of inert solvent) at one or more reactor inlets (e.g., at each reactor inlet in the system). In some such embodiments, glycerol is added along with a sufficient amount of solvent, thereby providing the subsequent reaction solution that is in a homogeneous state. In certain cases, adding glycerol at the inlets of the second and subsequent reactors can accelerate the reaction process.

When a recycling design is employed, it can be challenging to ensure that the concentration of monoglyceride within the reactor does not significantly vary at a given position as a function of time throughout a substantial portion of the reaction. For example, in some cases in which a recycling design is employed (e.g., cases that employ traditional recycling designs such as those used to produce chemicals other than monoglycerides), during start-up, the inlet composition to the reactor (e.g., stream 116 in FIG. 1) will vary over time until it reaches a steady state. If such a design were employed in the current system, however, the recycled monoglyceride would be able to react with the reactant fatty acid alkyl ester and/or carboxylic acid to produce

diglyceride(s) and/or triglyceride(s). The reactor outlet (e.g., stream 120 in FIG. 1), could then be contaminated with diglyceride(s) and/or triglyceride(s), and monoglyceride could be located almost exclusively at the reactor outlet during the first run. This process could worsen as recycling continues. In addition, the process described above can result in the monoglyceride concentration varying as a function of time until the system reaches a steady state, which is generally undesirable.

In certain embodiments, to reduce or prevent this problem, the monoglyceride concentration at the reactor inlet can be substantially fixed during startup, for example, by transporting a supplemental feed to a reactor inlet. For example, in FIG. 1, supplemental feed stream 101 and/or 102 can be transported to reactor 118 and/or reactor 128, respectively. The supplemental feed can include monoglyceride at the same or slightly higher (e.g., about 2% higher or less) concentration than that which would be observed in a recycle stream at steady state. This can be accomplished by preparing a separate product mixture (e.g., off-line from system 100) that has the same or slightly higher concentration of monoglyceride and other reaction components that would be observed at the reactor outlet, except with the alcohol or water removed (to mimic the removal of alcohol or water by the downstream separator). This separate product can then be used as the start-up recycling stream. After the system has been started, the separate product stream can be turned off, and the regular recycling stream can be turned on. One of ordinary skill in the art would be capable of estimating the steady state reactor output composition (e.g., in stream 120 in FIG. 1 at steady state), for a given feed rate of reactants and a given recycle ratio, via empirical calculations and lab testing.

In other embodiments, a single reactor (e.g., reactor 118) and a single separator for the removal of alcohol and/or water (e.g., separator 122) can be employed, achieving any of the favorable product compositions described elsewhere herein. In certain embodiments, two reactor and/or alcohol/water separators (as illustrated in FIG. 1) or more than two reactors and/or alcohol/water separators (e.g., three, four, or more) can be employed. In some embodiments, a combination of two different organic solvents can be applied, for example, to improve product selectivity. This can save the amount of high cost organic solvent used.

As noted above, in certain embodiments, a fatty acid alkyl ester can be reacted with glycerol to form a monoglyceride-containing reaction product. The fatty acid alkyl ester used in the system can be prepared by reacting a triglyceride or a carboxylic acid with a primary alcohol or a secondary alcohol, wherein the primary alcohol or the secondary alcohol contains 1 to 8 carbon atoms. It can also be the specialty (or neat) fatty acid alkyl ester that is obtained, for example, directly by the esterification reaction outlined above or through fractional distillation of a mixture of fatty acid alkyl esters, for example, derived from any oil source.

The fatty acid alkyl ester used in the systems described herein can contain a Cl- C8 primary or secondary alkoxy moiety or a C6-C24 fatty acid moiety. The term

"alkoxy," as used herein, refers to a straight or branched, saturated or unsaturated, non- aromatic hydrocarbon moiety containing an oxygen radical, such as -OCH₃ or - OCH=C₂H₄. The term "fatty acid," as used herein refers to a straight or branched, saturated or unsaturated monobasic organic acid. Exemplary fatty acids include, but are not limited to, caproic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, palmitoleic acid, stearic acid, oleic acid, ricinoleic acid, linoleic acid, linolenic acid, arachidic acid, ds-l l-eicosenoic acid, behenic acid, erucic acid and lignoceric acid. Exemplary fatty acid alkyl esters include, but are not limited to, fatty acid methyl esters, fatty acid ethyl esters, fatty acid w-propyl esters, fatty acid isopropyl esters, fatty acid n- butyl esters, fatty acid isobutyl esters, fatty acid w-pentyl esters, fatty acid w-hexyl esters, fatty acid 1-octyl esters and fatty acid 2-octyl esters. The fatty acid alkyl ester can have a boiling point of 150-500°C.

Examples of suitable oil sources (e.g., for making fatty acid alkyl esters for use in the present invention) include plant oil (e.g., microalgae oil, vegetable oil), animal fat (e.g., fish oil, lard, rendered fats or tallow), waste grease (e.g., waste restaurant grease), or a hydrolytic fraction thereof (e.g., carboxylic acids).

The glycerol used in the systems and methods described herein can be from any suitable source. In certain embodiments, the glycerol feed comprises a pure, anhydrous glycerol with a water level of less than about 2 wt , less than about 10,000 ppm by weight, or less than about 3,000 ppm by weight.

A variety of suitable solvents can be used in association with the systems and methods described herein. In certain embodiments, the solvent comprises an organic solvent. Examples of suitable organic solvents include C4-C8 tertiary alcohols (e.g., t- butanol, 2-methyl-2 butanol, 2,3-dimethyl-2-butanol, 2-methyl-2-pentanol, 3-methyl-3- pentanol, 3-ethyl-3-pentanol, 2,3-dimethyl-2-pentanol, 2,3-dimethyl-3-pentanol, 2,2,3- trimethyl-3-pentanol, 2-methyl-2-hexanol, or 3-methyl-3-hexanol) and pyridine.

The transesterification reaction (e.g., carried out in reactors 118 and 128 in FIG. 1, or in additional reactors in other systems) can be carried out at the range of -15°C to 95°C (e.g., 0-95°C). In certain embodiments, each reaction is carried out for 1-240 minutes per bed (e.g., 1-180 minutes or 1-120 minutes) to obtain the monoglyceride.

In certain embodiments, organic solvent and/or glycerol is partially removed during the alcohol or water removal processes (e.g., separator 122, separator 132, or in any other separator in the system). In some such cases, the removed solvent and/or glycerol is compensated for in the subsequent reaction step by adding solvent and/or glycerol to the separator effluent stream. By adding supplemental solvent and/or glycerol to the separator effluent stream, one can ensure that the reaction solution remains substantially homogeneous throughout the monoglyceride production process.

The specific examples below are to be construed as merely illustrative, and not limitative of the remainder of the disclosure in any way whatsoever. While these examples are intended to illustrate certain embodiments of the present invention, they do not exemplify the full scope of the invention. Without further elaboration, it is believed that one skilled in the art can, based on the description herein, utilize the present invention to its fullest extent. All publications cited herein are hereby incorporated by reference in their entirety.

EXAMPLE 1

This example describes the effect of varying the type of organic solvent used in the reaction of fatty acid methyl esters (FAME) with glycerol to produce monoglyceride. Reactions were carried out in a homogeneous solution. The feedstock comprised crude fatty acid methyl esters and glycerol. Crude FAME and high purity glycerol were obtained through the enzymatic transesterification of soybean oil and methanol, as described in U.S. Patent No. US 7,473,539 and European Patent Number 1637610, each of which is incorporated herein by reference in its entirety for all purposes. Crude

FAME comprised 90.50 wt% FAME, 9.44 wt% monoglyceride, 0.04 wt% diglyceride and 0.02 wt triglyceride. Glycerol purity was over 99.5 wt and the water content less than 3,000 ppm by weight. In this example, and all other examples herein, crude FAME, rather than pure FAME, was used.

For each reaction, a different anhydrous organic solvent was added. The reaction components were added to a flask and reacted. The contents of the flasks for each reaction, before the reaction, are given in Table 1.1.

Table 1.1. Feed compositions for reactions in Example 1.

0.3 g of the lipase LIPOZYME TL IM (a thermomyces lanuginosa lipase,

Novozymes A/S, Bagsvaerd, Denmark) was added to each flask prior to reaction. The reactions were carried out at 25 °C for 18 hours. During the reaction, the flasks were agitated at a speed of 250 rpm. The reaction time was chosen such that the reaction would reach its final equilibrium state.

The product compositions were determined using high-pressure liquid

chromatography (HPLC) (column: Luna Su CI 8(2) 250 x 4.6mm, phenomenex; mobile phases: methanol, hexane and isopropanol; UV detector: UV-2075, JASCO, Japan). The product compositions for each of the reactions are outlined in Table 1.2.

Table 1.2. Reaction product compositions with TL IM.

A similar set of reactions were carried out using the lipase thermomyces lanuginosa (CLEA Technologies, Delft, Netherlands) immobilized on a mesoporous polymer through physical adsorption. The compositions of the product streams for these reactions are outlined in Table 1.3.

Table 1.3. Reaction product compositions with lipase from CLEA.

Except for ί-butanol, the product distribution for each solvent unexpectedly exhibited high selectivity for monoglyceride. Higher selectivity was observed to be favored with a higher tertiary alcohol.

EXAMPLE 2

In this example, reactions were carried out in a homogeneous solution with anhydrous pyridine as the organic solvent, similar to the reactions carried out in Example 1. The reaction solution included 0.528 g crude FAME, 0.190 g glycerol, and 1.155 g pyridine with 0.15 g LIPOZYME TL IM lipase. The reaction was carried out at 25°C and 250 rpm for 18 hours. The following product composition was obtained, unexpectedly exhibiting a high degree of selectivity to monoglyceride. Table 2.1. Reaction product compositions for reactions in Example 2.

EXAMPLE 3

In this example, the amount of glycerol in the feed was investigated. A first reaction was carried out when crude FAME was in excess; that is, the amount of glycerol in the reactor feed was too small to completely convert the FAME. In this case, the solution added to the reactor comprised 0.704 g crude FAME, 0.150 g glycerol and 1.920 g i-amyl alcohol. For 0.704 g of crude FAME, the stoichiometric minimum amount of glycerol is 0.22 g. Accordingly, this first reactant composition was stoichiometrically short of glycerol. The reaction was carried out at 25°C and 250 rpm for 18 hours with 2.0 g LIPOZYME TL IM.

In addition, a second reaction was carried out in which glycerol was present in excess. In the second reaction, a homogeneous solution was made with 0.704 g crude FAME, 0.252 g glycerol and 1.920 g i-amyl alcohol. Unexpectedly, the reaction product compositions included relatively large amounts of monoglyceride, as shown in Table 3.1 Table 3.1. Reaction product compositions for reactions in Example 3.

The results in Table 3.1 indicated that product selectivity was not significantly affected by the amount of glycerol used. Accordingly, whether FAME or glycerol was in excess was not a deciding factor with regard to product selectivity.

EXAMPLE 4

In this example, the effect of temperature is discussed. Reactions similar to those outlined in Example 1 were carried out at different temperatures. The solutions included 0.704 g crude FAME, 0.252 g glycerol, and 1.92 g i-amyl alcohol. The reactions were carried out at 25°C and 45°C at 250 rpm for 18 hours with 2.0 g each of LIPOZYME TL IM and Novo 435 (a Candida antarctica lipase, Novozymes A/S, Bagsvaerd, Denmark) lipases in separate runs. Unexpectedly, each reaction produced monoglyceride in relatively large amounts, as outlined in Table 4.1.

Table 4.1. Reaction product compositions for reactions in Example 4.

The results indicated that, at temperatures of 0°C and 25°C, the product yield and selectivity were both improved, relative to 45 °C.

EXAMPLE 5

This example describes the effect of miscibility on the final product composition. An experiment was conducted similar to Example 1, except that it was made in a partially miscible solution. That is to say, the amount of organic solvent added to the reactant solution was insufficient to produce a completely dissolved solution, such that crude FAME and glycerol were present in two phases. The reaction solution included 0.704 g crude FAME, 0.252 g glycerol and 0.4 g i-amyl alcohol with 2.0 g LIPOZYME TL IM lipase. The reaction was carried out at 25°C and 250 rpm for 18 hours.

The following product compositions (wt%) were unexpectedly obtained: FAME

44.88, monoglyceride 52.86, diglyceride 2.26 and triglyceride 0.006. Compared to the result obtained in Example 4, the immiscibility of the reaction solution affected the lipase activity (perhaps due to deactivation, as evidenced by the reaction yield) as well as the product selectivity.

EXAMPLE 6

In this example, reactions were carried out using conditions similar to Example 1 while employing different amounts of lipase in the reactant composition. The reactant composition solutions included 0.528 g crude FAME, 0.189 g glycerol and 0.665 g t- butanol. In one reactant composition, 0.3 g of Novo 435 lipase were included. In the second reactant composition, 1.5 g of Novo 435 lipase were included. Reactions were carried out at 25°C and 250 rpm for 18 hours using each reactant composition in separate runs.

Unexpectedly, product compositions with different product selectivities were obtained, as outlined in Table 6.1.

Table 6.1. Reaction product compositions for reactions in Example 6.

The result indicates that product selectivity is improved when a higher amount of lipase is used in the reaction. The results imply that a design employing a packed bed reactor can provide better product selectivity toward monoglycerides than a continuously stirred tank reactor-based (CSTR-based) design.

EXAMPLE 7

In this example (and in Examples 8 and 9, which follow), the residence time for each reactor was selected to be the time at which equilibrium was achieved. Further improvement in conversion was not observed at times beyond the indicated residence time. A schematic illustration of reaction system 200 employed in this example is shown in FIG. 2. In Example 7 (as in Examples 8 and 9, which follow), product selectivity of monoglyceride is determined as the ratio of monoglyceride mass in the reaction mixture over the total mass of monoglyceride, diglyceride and triglyceride in the reaction mixture.

The starting reactant composition feedstock, transported in stream 210, included the following components: 24.5 wt crude FAME, 8.8 wt glycerol, and 66.7 wt t- amyl alcohol, in which water content was 2,152 ppm. The first reaction was carried out in a packed bed reactor 218. The bed was filled with thermomyces lanuginosa immobilized on a mesoporous polymer through physical adsorption. The reaction was carried out at 25°C for 60 minutes. The methanol byproduct 224 in the reaction outlet solution 220 was removed through a simple distillation apparatus 222, illustrated in FIG. 3. Distillation apparatus 222 included receiving flask 302 and condenser 304. Methanol in the byproduct can be boiled out of container 306 using heater 308, leaving behind the remainder of the reaction product in container 306. The mixture in container 306 was maintained at a temperature higher than the boiling point of methanol. The temperature of the mixture in container 306 was monitored using thermometer 310. The amount of t-amyl alcohol that was removed with the methanol was measured, and an equivalent amount of t-amyl alcohol was added to the reaction mixture in container 306 after separation to compensate for the loss, in preparation for the subsequent reaction.

After removal of methanol, the remaining reaction product in container 306 was transported via stream 226 to a second plug flow reactor 228 filled with thermomyces lanuginosa immobilized on a mesoporous polymer through physical adsorption, where a subsequent reaction was commenced. After the reaction within reactor 228 was complete, a second separator 232 (similar to separator 222) was used to remove methanol and water (via stream 234) from reaction product stream 230 to produce final product stream 236.

After four repetitions of reaction and methanol removal, the following composition was obtained (wt%): FAME 6.37, monoglyceride 90.75 and diglyceride 2.90. After five repetitions, the reaction product composition was (wt%): FAME 1.11, monoglyceride 97.28 and diglyceride 1.61. After the 6^th reaction, the following composition was unexpectedly obtained (wt%): FAME 0.51, monoglyceride 98.83, diglyceride 0.65, and triglyceride 0.01, with an acid value of 3.56 mg KOH/g and 2,594 ppm water.

EXAMPLE 8

This example describes the production of specialty products from methyl laurate and methyl myristate. The following two starting reactant compositions were employed:

Composition 1

Methyl laurate 26.7 wt%

Glycerol 13.2 wt%

t-amyl alcohol 60.1 wt%

Composition 2

Methyl myristate 28.1 wt%

Glycerol 12.3 wt%

t-amyl alcohol 59.6 wt%

A packed bed reactor, similar to reactor 218 described in Example 7 and illustrated in FIG. 2, was employed. The beds were filled with LIPOZYME TL IM lipase. The reactions were carried out at 25°C for 20.0 minutes and 40.0 minutes, respectively. Compositions 3 and 4 were unexpectedly obtained from Compositions 1 and 2, respectively:

Composition 3

Methyl laurate 4.95 wt%

Monoglyceride 95.03 wt%

Diglyceride 0.02 wt%

Triglyceride undetectable

Composition 4

Methyl myristate 7.97 wt%

Monoglyceride 92.00 wt%

Diglyceride 0.03 wt%

Triglyceride undetectable

Methanol was removed from the reaction products, as described above in Example 7 and illustrated in FIG. 3. A second reaction was carried out in a packed bed reactor in each case. In the second reactions, each bed was filled with LIPOZYME TL IM lipase, and the reactions were carried out at 25°C for 20 minutes. Compositions 5 and 6 were unexpectedly obtained from Compositions 3 and 4, respectively:

Composition 5

Methyl laurate 0.07 wt%

Monoglyceride 99.93 wt%

Diglyceride undetectable

Triglyceride undetectable

Composition 6

Methyl myristate 0.20 wt%

Monoglyceride 99.27 wt%

Diglyceride 0.53 wt%

Triglyceride undetectable

EXAMPLE 9

This example describes the production of glycerol monolaurate from lauric acid and glycerol. Starting with a neat feedstock of lauric acid, the reaction was carried out similar to previous Examples 7 and 8.

Initially, the feedstock included the following components: Lauric acid 22.4 wt

Glycerol 11.8 wt%

i-amyl alcohol 65.8 wt

Again, in this example, a packed bed reactor, similar to reactor 218 described in Example 7 and illustrated in FIG. 2, was employed. The bed was filled with

LIPOZYME TL IM lipase. The reaction was carried out at 25°C for 20 minutes.

Unexpectedly, a reaction composition including a relatively large amount of monoglyceride was obtained:

Lauric acid 24.89 wt%

Glycerol monolaurate (monoglyceride) 75.10 wt

Glycerol dilaurate (diglyceride) 0.003 wt

Glycerol trilaurate (triglyceride) 0.003 wt

Water was removed from the reaction product using a separator similar to the separator illustrated in FIG. 3. Subsequently, second, third, and fourth reactions were carried out at 25 °C, again, using packed bed reactors. Each of the reactor beds for these reactions were filled with LIPOZYME TL IM lipase. The residence time for each reaction was 20 minutes. Unexpectedly, lauric acid was converted to a high degree, and monoglyceride was produced highly selectively, as shown below:

2ⁿ reaction output

Lauric acid 9.55 wt%

MG 90.45 wt%

DG undetectable

TG undetectable

3^rd reaction output

Lauric acid 5.63 wt%

MG 94.36 wt%

DG undetectable

TG 0.001 wt%

4^th reaction output

Lauric acid 1.79 wt%

MG 98.21 wt%

DG 0.002 wt%

TG 0.001 wt% All of the features disclosed in this specification may be combined in any combination. Each feature disclosed in this specification may be replaced by an alternative feature serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each feature disclosed is only an example of a generic series of equivalent or similar features.

From the above description, one skilled in the art can easily ascertain the essential characteristics of the present invention and without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions. Thus, other embodiments are also within the scope of the following claim.

While several embodiments of the present invention have been described and illustrated herein, those of ordinary skill in the art will readily envision a variety of other means and/or structures for performing the functions and/or obtaining the results and/or one or more of the advantages described herein, and each of such variations and/or modifications is deemed to be within the scope of the present invention. More generally, those skilled in the art will readily appreciate that all parameters, dimensions, materials, and configurations described herein are meant to be exemplary and that the actual parameters, dimensions, materials, and/or configurations will depend upon the specific application or applications for which the teachings of the present invention is/are used. Those skilled in the art will recognize, or be able to ascertain using no more than routine experimentation, many equivalents to the specific embodiments of the invention described herein. It is, therefore, to be understood that the foregoing embodiments are presented by way of example only and that, within the scope of the appended claims and equivalents thereto, the invention may be practiced otherwise than as specifically described and claimed. The present invention is directed to each individual feature, system, article, material, kit, and/or method described herein. In addition, any combination of two or more such features, systems, articles, materials, kits, and/or methods, if such features, systems, articles, materials, kits, and/or methods are not mutually inconsistent, is included within the scope of the present invention.

The indefinite articles "a" and "an," as used herein in the specification and in the claims, unless clearly indicated to the contrary, should be understood to mean "at least one." The phrase "and/or," as used herein in the specification and in the claims, should be understood to mean "either or both" of the elements so conjoined, i.e., elements that are conjunctively present in some cases and disjunctively present in other cases. Other elements may optionally be present other than the elements specifically identified by the "and/or" clause, whether related or unrelated to those elements specifically identified unless clearly indicated to the contrary. Thus, as a non-limiting example, a reference to "A and/or B," when used in conjunction with open-ended language such as "comprising" can refer, in one embodiment, to A without B (optionally including elements other than B); in another embodiment, to B without A (optionally including elements other than A); in yet another embodiment, to both A and B (optionally including other elements); etc.

As used herein in the specification and in the claims, "or" should be understood to have the same meaning as "and/or" as defined above. For example, when separating items in a list, "or" or "and/or" shall be interpreted as being inclusive, i.e., the inclusion of at least one, but also including more than one, of a number or list of elements, and, optionally, additional unlisted items. Only terms clearly indicated to the contrary, such as "only one of or "exactly one of," or, when used in the claims, "consisting of," will refer to the inclusion of exactly one element of a number or list of elements. In general, the term "or" as used herein shall only be interpreted as indicating exclusive alternatives (i.e. "one or the other but not both") when preceded by terms of exclusivity, such as "either," "one of," "only one of," or "exactly one of." "Consisting essentially of," when used in the claims, shall have its ordinary meaning as used in the field of patent law.

As used herein in the specification and in the claims, the phrase "at least one," in reference to a list of one or more elements, should be understood to mean at least one element selected from any one or more of the elements in the list of elements, but not necessarily including at least one of each and every element specifically listed within the list of elements and not excluding any combinations of elements in the list of elements. This definition also allows that elements may optionally be present other than the elements specifically identified within the list of elements to which the phrase "at least one" refers, whether related or unrelated to those elements specifically identified. Thus, as a non-limiting example, "at least one of A and B" (or, equivalently, "at least one of A or B," or, equivalently "at least one of A and/or B") can refer, in one embodiment, to at least one, optionally including more than one, A, with no B present (and optionally including elements other than B); in another embodiment, to at least one, optionally including more than one, B, with no A present (and optionally including elements other than A); in yet another embodiment, to at least one, optionally including more than one, A, and at least one, optionally including more than one, B (and optionally including other elements); etc.

In the claims, as well as in the specification above, all transitional phrases such as

"comprising," "including," "carrying," "having," "containing," "involving," "holding," and the like are to be understood to be open-ended, i.e., to mean including but not limited to. Only the transitional phrases "consisting of and "consisting essentially of shall be closed or semi-closed transitional phrases, respectively, as set forth in the United States Patent Office Manual of Patent Examining Procedures, Section 2111.03.

What is claimed is:

Claims

1. A method for producing a high purity monoglyceride product, comprising: mixing a fatty acid alkyl ester and glycerol in an organic solvent to form a solution, wherein each molecule of the organic solvent contains 4-8 carbon atoms and a heteroatom;

reacting the fatty acid alkyl ester with the glycerol in the presence of a lipase within a plug flow reactor to produce a reaction mixture comprising the monoglyceride product, wherein:

the solution does not undergo phase separation throughout the reaction, an alcohol is produced as a byproduct of the reaction, and the product selectivity of monoglyceride is at least 95%, by weight.

2. The method of claim 1, further comprising removing at least a portion of the alcohol from the reaction mixture during the reaction and/or before any subsequent reaction.

3. The method of any one of claims 1-2, further comprising separating the monoglyceride product from the reaction mixture.

4. A method for producing a high purity monoglyceride product, comprising: mixing a carboxylic acid and glycerol in an organic solvent to form a solution, wherein each molecule of the organic solvent contains 4-8 carbon atoms and a heteroatom;

reacting the carboxylic acid with the glycerol in the presence of a lipase within a plug flow reactor to produce a reaction mixture comprising the monoglyceride product, wherein:

the solution does not undergo phase separation throughout the reaction, and

water is produced as a byproduct of the reaction;

removing at least a portion of the water from the reaction mixture during the reaction and/or before any subsequent reaction; and

separating the monoglyceride product from the reaction mixture.

5. The method of claim 4, wherein the product selectivity of monoglyceride is at least 95%, by weight.

6. The method of any one of claims 1-5, wherein the product selectivity of monoglyceride is at least 98%, by weight.

7. The method of any one of claims 1-6, wherein the organic solvent comprises at least one C4-C8 tertiary alcohol.

8. The method of any one of claims 1-7, wherein the organic solvent comprises t- butanol, 2-methyl-2-butanol, 2,3,-dimethyl-2-butanol, 2-methyl-2-pentaol, 3-methyl-3- pentanol, 3-ethyl-3-pentanol, 2,3-dimethyl-2-pentanol, 2,3-dimethyl-3-pentanol, 2,2,3- trimethyl-3-pentanol, 2-methyl-2-hexanol, and/or 3-methyl-3-hexanol.

9. The method of any one of claims 1-8, wherein the organic solvent comprises pyridine.

10. The method of any one of claims 1-9, wherein the lipase is immobilized on a carrier.

11. The method of any one of claims 1-10, wherein the lipase comprises Candida antarctica lipase, thermomyces lanuginosa lipase, pseudomonas fluorescens lipase, Burkholderias cepacia lipase, chromobacterium viscosum lipase, pseudomonas sp.

lipase, aspergiUus oryzae lipase, aspergiUus niger lipase, rhizopus niveus lipase, and/or a phospholipase.

12. The method of claim 11, wherein the phospholipase comprises phospholipase Al, phospholipase A2, phospholipase C, and/or phospholipase D.

13. The method of any one of claims 1-12, wherein a temperature within the reactor during at least a portion of the reacting step is about -15°C to about 95°C.

14. The method of any one of claims 1-13, wherein the reacting step is carried out for about 1 to about 240 minutes.

15. The method of any one of claims 1-14, further comprising adding a

monoglyceride to the solution before the reacting step.

16. The method of any one of claims 1-3 and 6-15, wherein the fatty acid alkyl ester comprises a compound including a C6-C24 fatty acid moiety.

17. The method of any one of claims 1-3 and 6-15, wherein the fatty acid alkyl ester comprises a compound including a C1-C8 primary or secondary alkoxy moiety.

18. The method of any one of claims 1-3 and 6-15, wherein the fatty acid alkyl ester comprises a fatty acid methyl ester, a fatty acid ethyl ester, a fatty acid n-propyl ester, a fatty acid isopropyl ester, a fatty acid n-butyl ester, a fatty acid isobutyl ester, a fatty acid n-pentyl ester, a fatty acid isopentyl ester, a fatty acid neopentyl ester, or a fatty acid n- hexyl ester, a fatty acid 1-octyl ester and/or a fatty acid 2-octyl ester.

19. The method of any one of claims 1-3 and 6-15, wherein the fatty acid alkyl ester has a boiling point of about 150 to about 500°C.

20. The method of any one of claims 1-3 and 6-15, wherein the fatty acid alkyl ester is a mixture or a single specialty compound.

21. The method of any one of claims 4-15, wherein the carboxylic acid comprises a hydrolytic fraction of plant oil, animal fat, or waste grease.

22. The method of any one of claims 4-15 and 21, wherein the carboxylic acid comprises a caproic acid, a caprylic acid, a capric acid, a lauric acid, a myristic acid, a palmitic acid, a palmitoleic acid, a stearic acid, an oleic acid, a ricinoleic acid, a linoleic acid, a linolenic acid, an arachidic acid, a cis-l l-eicosenoic acid, a behenic acid, an erucic acid or a lignoceric acid, or any combination thereof.

23. A method for producing a monoglyceride product, comprising:

introducing a mixture comprising a fatty acid alkyl ester and/or a carboxylic acid, glycerol and an organic solvent into a plug flow reactor;

reacting the fatty acid alkyl ester and/or the carboxylic acid with the glycerol in the presence of a lipase within the plug flow reactor to produce a reaction mixture comprising the monoglyceride product; and

recycling at least a portion of the reaction mixture back into the plug flow reactor after removal of at least a portion of the alcohol and/or water.

24. The method of claim 23, wherein the concentration of the monoglyceride in the plug flow reactor is substantially fixed at each position within the reactor as a function of time throughout a substantial portion of the reaction.

25. The method of any one of claims 23-24, wherein the organic solvent comprises a component containing 4-8 carbon atoms and a heteroatom.

26. The method of any one of claims 23-25, wherein the organic solvent comprises at least one C4-C8 tertiary alcohol.

27. The method of any one of claims 23-26, wherein the organic solvent comprises t- butanol, 2-methyl-2-butanol, 2,3,-dimethyl-2-butanol, 2-methyl-2-pentaol, 3-methyl-3- pentanol, 3-ethyl-3-pentanol, 2,3-dimethyl-2-pentanol, 2,3-dimethyl-3-pentanol, 2,2,3- trimethyl-3-pentanol, 2-methyl-2-hexanol, and/or 3-methyl-3-hexanol.

28. The method of any one of claims 23-27, wherein the organic solvent comprises pyridine.

29. The method of any one of claims 23-28, wherein the lipase is immobilized on a carrier.

30. The method of any one of claims 23-29, wherein the lipase comprises Candida antarctica lipase, thermomyces lanuginosa lipase, pseudomonas fluorescens lipase, Burkholderias cepacia lipase, chromobacterium viscosum lipase, pseudomonas sp. lipase, aspergiUus oryzae lipase, aspergiUus niger lipase, rhizopus niveus lipase, and/or a phospholipase.

31. The method of claim 30, wherein the phospholipase comprises phospholipase Al, phospholipase A2, phospholipase C, and/or phospholipase D.

32. The method of any one of claims 23-31, wherein a temperature within the reactor during at least a portion of the reacting step is about -15°C to about 95°C.

33. The method of any one of claims 23-32, wherein the fatty acid alkyl ester comprises a compound including a C6-C24 fatty acid moiety.

34. The method of any one of claims 23-33, wherein the fatty acid alkyl ester comprises a compound including a C1-C8 primary or secondary alkoxy moiety.

35. The method of any one of claims 23-34, wherein the fatty acid alkyl ester comprises a fatty acid methyl ester, a fatty acid ethyl ester, a fatty acid n-propyl ester, a fatty acid isopropyl ester, a fatty acid n-butyl ester, a fatty acid isobutyl ester, a fatty acid n-pentyl ester, a fatty acid isopentyl ester, a fatty acid neopentyl ester, or a fatty acid n- hexyl ester, a fatty acid 1-octyl ester and/or a fatty acid 2-octyl ester.

36. The method of any one of claims 23-34, wherein the fatty acid alkyl ester has a boiling point of about 150 to about 500°C.

37. The method of any one of claims 23-36, wherein the fatty acid alkyl ester is a mixture or a single specialty compound.

38. The method of any one of claims 23-34, wherein the carboxylic acid comprises a hydrolytic fraction of plant oil, animal fat, or waste grease.

39. The method of any one of claims 23-34, wherein the carboxylic acid comprises a caproic acid, a caprylic acid, a capric acid, a lauric acid, a myristic acid, a palmitic acid, a palmitoleic acid, a stearic acid, an oleic acid, a ricinoleic acid, a linoleic acid, a linolenic acid, an arachidic acid, a cis-l l-eicosenoic acid, a behenic acid, an erucic acid or a lignoceric acid, or any combination thereof.

40. The method of any one of claims 23-39, wherein the product selectivity of monoglyceride is at least 95%, by weight.

41. The method of any one of claims 23-40, wherein the product selectivity of monoglyceride is at least 98%, by weight.