|Title of Invention||
"A PROCESS FOR SIMULTANEOUS CONVERSION OF CARBOXYLIC ACIDS AND THEIR GLYCERIDES TO ALKYL ESTERS"
|Abstract||A process for simultaneous conversion of carboxylic acids and their glycerides to alkyl esters by reacting carboxylic acid / or their glycerides with an alcohol optionally in presence of a montmorillonite clay catalyst treated with calcium chloride at a temperature in the range of 130-250°C, at pressure in the range of 5-25 kg/cm2 for 2 to 8 hr. and recovering the alkyl ester by conventional method.|
|Full Text||The present invention relates to a process for the simultaneous conversion of carboxyiic acids and their glycerides to the alkyl esters.
The present invention particularly relates to a one step process for the preparation of alkyl esters by simultaneous transesterification and esterification of oils and fats containing varying amounts of free fatty acids with or without catalysts at elevated temperatures and under moderate pressure. The invention has distinct applicability to the acid rich fractions obtained during vegetable oil processing like the distillates obtained during physical refining, deodorization, acidulated soapstock, etc. which predominantly consist of a mixture of fatty acids and triglycerides with or without other constituents, whereby the fatty acids and the glycerides are converted to alkyl esters in one step. While both processes (catalytic and catalyst-free) work equally well with substrates containing fatty acids and glycerides, those which are essentially neutral, i.e. when the substrate contains only glycerides and no fatty acids, require a catalyst for conversion to alkyl esters. The presence of some amount of fatty acids or a small quantity of water is essential for the catalyst-free process. The solid clay catalyst when used is easily separated at the end of reaction by filtration.
BACKGROUND OF THE INVENTION
Fatty acids derived from triglyceride oils traditionally form the basic raw material for other oleochemicals. The soapstock obtained as a by-product from caustic refining of edible vegetable oils provides a cheap, readily available supply of fatty acids for oleochemical manufacture. The major components of soapstock are; water (-45%). neutral oil (~18%), fatty acids in the form of soap (-25%), non-
saponiftable constituents (--8%) and others (-4%). The cnide soapstock is acidulated to yield what is known as acid oil which typically has the composition; neutral oil. 20-30%; free fatty acids, 65-70%; nonfatty contaminants, -5%. Owing to the easy availability and low price, considerable attention has been paid during the past decade towards development of economical technology to upgrade soapstock utilization. One area of technology development has been the conversion of the free fatty acids and the triglycerides present to their corresponding methyl esters The trend for the increasing use of methyl esters from soapstock / acid oil appears to be a consequence of several factors. Methyl esters have been slowly replacing fatty acids as starting materials for many oleochemicals such as fatty alcohols, alkanolamides, A similar source of cheap fatty acids is the deodorizer distillate obtained during the deodorization of vegetable oils. As in the case of acid oil this also is a mixture of fatty acids, glycerides and nonglyceride components. The deodorizer distillate, especially from soybean oil has been the traditional source of valuable byproducts such as tocopherols'and sterols. Conventional processing of this material involves distilling out the fatty acid components leaving a mixture of neutral oil and nonsaponifiable material resulting in some concentration of the tocopherols and sterols. If the neutral oil also is converted to distillable materials, for example to methyl esters as proposed" in the present invention, the concentration of tocopherols
and sterols in the residue would be much higher and their purification becomes simpler-Fatty acid esters are produced commercially either by esterification of fatty acids which are obtained by high pressure splitting of oils and fats or transesterification of oils and fats. Many methods are described in prior art for conversion of fatty acids to methyl esters. Continuous esterification of C2-C24 carboxylic acids with a C1-C5 monoalcohoi in a reactor at elevated temperatures of 200 to 260°C and at a pressure of 0.5 to 1.5 mPa in the absence of any esterification catalyst by continuously feeding in the alcohol during the reaction and removing a gaseous alcohol-water mixture is reported in US The process is carried out in two steps with the first step as described above and a second step in which further reaction to a conversion of 99% is carried out in the presence of a esterification catalyst below 100°C. describes a column reactor containing an ion exchange resin having -SO3H and / or -COOH groups as esterification catalyst charged on a plurality of trays The fatty acid mixture flows down the column reactor from one tray to the next downward against an upflowing alcohol vapour stream. Relatively dry alcohol vapour is injected into the bottom of the column reactor. Water of esterification is removed from the top of the column reactor in the vapour stream while ester product is recovered from the sump of the reactor and the reaction is driven further towards 100% ester formation. US Patent 5,405,992 reports a process for concurrent esterification and separation using a simulated moving bed. The simulated moving bed is a homogeneous mixture of atleast one solid effective as an esterification catalyst and at least one solid effective as an ester or water adsorbent. The bed comprises of a strongly acidic macroreticular
polymeric resin effective both as an esterification catalyst and as an adsorbent for at least one esterification product. A long chain alkylbenzene sulfonic acid catalyst, the alkyl radical containing from 8 to 20 carbon atoms or mixtures of such catalysts for esterification are claimed The improvement in the process comprises minimizing the amount of acidic sulfate in the product ester Methods for producing polyol fatty acid polyesters using atmospheric or superatmospheric pressure is claimed The polyol is reacted with fatty acid alkyl ester in the presence of basic catalyst to produce polyol fatty acid polyester product and lower alkyl alcohol byproduct. Reaction is carried out in the temperature range of 60 to 180°C while sparging inert gas through the reactor to transfer the alcohol byproduct from the liquid mixture of reactant and product to promote full esterification of polyol without the use of vacuum / pressure. The use of thin film methodology which provides for greater yields of the polyol fatty acid polyesters and more efficient removal of by-products is reported in US Patent 5,596,085 /The reaction is carried out at 95-200°C in the presence of an esterification catalyst These polyol fatty acid polyesters, especially sucrose fatty acid polyesters are usefiil as fat substitutes or low-calorie fats in food compositions A catalyst-free process for making polyester polyols having a low acid number for use in polyurethane compositions by melt condensation of polyalcohols and polycarboxyiic acids is reported in When the reaction product has an acid number of 480 or less, then selected distillable mono- and or dialcohols are added and the condensation reaction is continued until an acid number of less than one is obtained
Many crude oils from natural sources contain varying amounts of free fatty acids. Many methods are described in prior art for the conversion of such oils to
methyl esters for use as oleochemicals and as diesel fuel substitutes. Most methods involve a two step process. The mitial step involves conversion of free fatty acids to esters followed by transesterification of glycerides to methyl esters. Generally the first step is acid catalyzed while the later is catalyzed by alkali. Direct transesterification of oils containing fatty acids is uneconomical for commercial production as the yields are low. For direct transesterification of the oil the acid value has to be interesterifying substantially refined soapstock in the second step. Initially, a three hour acid-catalyzed direct esterification with methanol at 65-67°C converts free fatty acids to methyl esters and then a two-stage base catalyzed methanolysis at time cycles of 1 h and 0.5 h respectively carried out on the oil phase from the first step, converts the triglycerides to methyl esters. The Hoechst process (German Pat., 3,421,217) consists of contacting the fat body with a stream of methanol vapor at 240°C in the presence of an alcoholysis catalyst such as sodium methoxide. The reaction products, methyl esters and glycerol are stripped from the liquid phase as soon as they are formed. After partial condensation of the vapor phase, the glycerol is separated from methyl esters. The alcohol vapour is returned to the reaction zone. A portion of the methanol is withdrawn from the loop and replaced with fresh alcohol to keep the concentration of water of reaction to low levels. A process described consist of first esterifying the free fatty acids in an oil with a special synthetic resin catalyst and then transesterifying the remaining neutral oil with sodium methoxide. Jeromin, et al (Fette Seifen Anstrichm 1981, 83, 493) have reported esterification of fatty acids using an alkaline catalyst. Haas and Scott (J Am. Oil Chem. Soc. 1996, 73, 1393) describe a combined chemical-enzymatic process for the conversion of soapstock into methyl esters in two steps In the first step the glycerides present in the soapstock were transesterified with alcohol and potassium hydroxide and in the second step the free fatty acids are esterified using a lipase An alkaline catalyst (J. Am. O'il Chem. Soc, 1984, 61, 343) that catalyzes both esterification and transesterification at a pressure of 90 bar has been reported A process for the preparation ol" Catty acid alkyl esters is claimed that comprises transesterification of glycerides in the presence of acidic catalyst at elevated pressure and temperature. Thus, coconut oil containing 3.8% by weight of bound glycerol gave
a product (AV 0.8) containing 1.0% of bound glycerol (Ger. Offen DE 4,122,530) Production of alkyl esters by catalytic esterification / transesterification of natural fats and oils containing free fatty acids is described in US Patent 4,652,406. In the preliminary step the free fatty acids present are reacted with C1-C4 alcohols in the presence of an acidic esterification catalyst, at a temperature of about 50 to 120"C, The reaction mixture is allowed to separate into two phases; an alcohol phase containing the acidic esterification catalyst and part of water of reaction and the oil phase. Then the oil phase is extracted with an immiscible extractant, comprising a mixture of glycerol and methanol, to remove the residual water of reaction. In the subsequent step the extracted oil phase is transesterified with C1-C4 alcohol in the presence of an alkali catalyst. A method is described using zinc oxide or zinc hydroxide as catalysts for esterification - transesterification of a mixture containing fats, fatty acids, tocopherols, sterols etc. wherein the free fatty acids present in the mixture are esterified and fatty glycerides are transesterified with an alcohol (US Patent 5,703,252).
Thus all known methods for conversion of crude oils containing fatty acids or acidulated soapstock or deodorizer distillate to methyl esters described above require a two-stage process. The more desirable one-stage technology, generally applicable to large volume production of methyl esters appears to be largely in the development stage. It would be economicalfy advantageous if a single catalyst can be found which catalyses both the steps simultaneously. Such processes with or without catalysts are described in the present invention
DETAILS OF THE DESCRIPTION
The catalytic process of the present invention is based on the observation that a particular class of mineral clay catalysts described as aikaline earth metal salt-modified clays used for dimerization of unsaturated fatty acids [US Patent 3,632,822] also catalyzed esterification of the dimer acids when methanol was pre^nt in the medium yielding a one-step process for the preparation of dimer acid methyl esters. These clays are activated mineral clays of the base exchanging type (i.e., montmorillonite or bentonite) that have been reacted with an aqueous solution of a water-soluble alkaline earth metal salt until substantial ion exchange has occurred and the interplanar spacing of clay has increased to a thickness equivalent to at least two monomolecular layers of water. In the present invention, similar clays were prepared from Montmorillonite K-10 clay. The use of this clay in the present process does not result in dimerization of fatty acids since the temperatures involved are lower than that required for dimerization.
In a representative procedure, Montmorillonite K-10 having a pH 3.45 (pH of the supernatent obtained by shaking 1 g of clay with 50 ml of water for 15 min.) is agitated with a 1 moiar aqueous calcium chloride solution for 10 hours or longer, after which the clay is separated from the salt solution by filtration This procedure replaces alkali metal and hydrogen ions of the clay with calcium ions. For best results the clay is then preferably subjected to a second treatment with a 1 molar calcium chloride solution, and this treatment is preferably continued until the pH of the modified clay, measured as described above, is in the range of from 5 to 7 The
filtered clay is then air dried and finally dried at 1 10°C overnight before use. The clay catalyst can be separated after the reaction by filtration.
The invention has particular applicability to the simultaneous esterification of free fatty acids in admixture with triglycerides in a single step even in the presence of small amounts of water. The invention has particular applicability to esterification cum transesterification of crude oils, acid oils and deodorizer distillates. The latter two could be important sources of value added, biologically active minor constituents of vegetable oils such as tocopherols, sterols, oiyzanols etc. and the present processes should help in their easier recovery
The process is particularly applicable to esterification of long chain carboxylic acids which occur naturally in vegetable oils. The process is also applicable to other natural fats and oils from other sources. Preferably therefore the carboxylic acid is a C10 to C24 carboxylic acid or a mixture of such acids. The carboxylic acids may be saturated or unsaturated with one or more double bonds. It is preferable to carry out the esterification reaction on a naturally occurring mixture of carboxylic acids such as those derived from vegetable or animal origin or on a fraction derived fVoin such a mixture. For example, the acids may be derived from any edible grade vegetable oil either in its caide state or after some treatment by way of refining. The present invention is of particular application when substantial quantities of glycerides as are present along with free fatty acids as are found in crude vegetable oils, in acid oils and in deodorizer distillates. The present invention has special applicability to the acid oil obtained from rice bran oil and soybean deodorizer distillate. The former is an excellent source for oryzanols while the latter provides for a source of tocopherols
and sterols. However, the present invention is not limited to these two oils alone. For example, the deodorizer distillates from ricebran oil and palm oil could be valuable sources of tocotrienols in addition to tocopherols and sterols
The catalyst-free process of the present invention has particular application in the production of synthetic ester lubricants where traces of acid and alkaline catalyst residues adversely affect the thermal and oxidative stabilities of such lubricants.
Preferably, the esterification of the acid is with C1 to C5 alcohols especially methanol. Preferably there is employed an excess of 1.5 moles and 10 moles of methanol based on fatty acids and oils respectively, more preferably an excess of 2.2 moles for fatty acids and 9.2 moles for oils
Preferably, the reaction is carried out in an autoclave and there is employed an autogenous pressure. Preferably there is employed a temperature of 130-250°C more preferably 180-210°C. Preferably there is employed a reaction time of 4-11 h, more preferably 2-8 h. While the clay-catalyzed process of thepresent invention work on pure glycerides as well as in admixture with fatty acids, the catalyst-free process requires some amount of fatty acids to be present in the substrate. Alternatively, small amount of water may be added to effect the conversion. App^ently, the esterification of the glycerides in this process proceeds via hydrolysis of the glycerides followed by esterification of the liberated fatty acids
The main object of the present invention is to provide a process for simultaneous conversion of carboxylic acid / and their glycerides to the alkyl esters.
Another objective of the present invention is to provide a one step improved process for the preparation of alkyl esters from glyceride mixtures containing free fatty- acids by simultaneous esterification of free fatty acids and transesterification of the glycerides. Yet another objective of the present invention is to use the product thus obtained for oleochemicals or as diesei fuel substitute after distillation. Yet another objective of the present invention is to provide the residue from distillation as a valuable source of byproducts. For example, such a residue obtained after siiort path distillation of the esterified soybean deodorizer distillate contains a much higher concentration of tocopherols and sterols than that obtainable by conventional direct distillation of the deodorizer distillate.
Accordingly the present invention provides a process for simultaneous conversion of carboxylic acids and their glycerides to alkyl esters which comprises reacting carboxy/ic acid / or their glycerides with an alcohol wherein the ratio of alcohol used varies from hi to 1:10 optionally in presence of a montmorillonite clay catalyst in the range of 3 to 8% by wt based on the wt of raw material at a temperature in the range of 130-250"C, at pressure in the range of 5-25 kg/cm' for 2 to 8 hr. and recovering the alkyl ester by conventional method. In an embodiment of the present invention the carboxylic acid used may contain straight chain or branched chain carboxylic acids.
In another embodiment of the present invention the glycerides used may be of long chain fatty acids with carbon chain varying from C10 to C24-
The mixture of carboxylic acids and glycerides obtained from any source such as from natural oil, or a fraction derived from such a mixture may be used for
esteritlcation. In yet another embodiment the alcohol used may contain carbon I to 8 alcohols preferably methanol
In still another embodiment of the reaction tiie clay catalyst used may be montmorillonite K-10 clay
The present invention provides a process for the simultaneous conversion of glycerides and carboxylic acids to methyl esters from fatty acids, deodorizer distillates, acid oils, high free fatty acid oils, crude oils etc which comprises esterification of fatty acids and transesterification of any neutral oil present in the acid oils simultaneously, at a temperature in the range of 130-250°C for 2 to 8 h at a pressure of 20-25 kg/cm2. The catalyst when used is removed by filtration. An added advantage of the present invention is that the byproduct glycerol is obtained in a concentrated form. A further advantage is that the clay catalyst can be reused. A still further advantage compared to conventional homogeneous acid or alkali catalyzed reaction is that a neutralization step generating aqueous effluents is avoided making the present invention more environmentally friendly
The broad applicability of the invention was examined with various raw materials like crude vegetable oils, acid oils obtained during the vegetable oil refining process, deodorizer distillate obtained during the deodorization of vegetable oils, free fatty acids and their reaction products.
The following examples are given by way of illustration of the present invention and therefore should not be construed to limit the scope of the present invention.
Example I a. Preparation of clay catalyst
Twenty grams of acid-activated Montmorillonite K-10 (Fluka) and 200 g of a 1 i molar aqueous calcium chloride solution are taken in a suitable reaction vessel and stirred using a magnetic stirrer, for 16-20 hr at room temperature The mixture is filtered and the clay is washed and dried to give a clay of pH 4 14. To obtain clays of higher pH the treated clay is further stirred for an additional four hours with 200 g of a 1 molar calcium chloride solution. Again the clay is filtered and the treatment repeated (4 to 6 times) to obtain a clay of pH 7.8 to 8.05 The clay is then air-dried followed by drying in the oven at 110°C overnight and kept in a dessicator.
Estcrificatioii of fatty acids
A 2 I stainless steel autoclave equipped with a stirrer, temperature control and sampling device was charged with 800 grams of commercial grade oleic acid (2,8 moles. Acid Value 183.8 mg KOH/g), 32 grams of modified clay catalyst (pH ~4, 4%) and 200 ml methanol (6.25 moles) and heated to 200°C. The reaction temperature was maintained for 4 h at a pressure at 20 kg/cm'. At the end of the reaction, the reaction mixture was cooled, and the clay was filtered off Acid
value of the product showed that about 70% of the esterification was complete by this reaction. The product was subjected to a second treatment as described above to complete the reaction. At the end of the reaction time, the contents were cooled and the catalyst was filtered off. From the crude ester product excess methanol was distilled out and the product was vacuum dried and analyzed for acid value. The experiments were repeated with isopropanol and 2-ethylhexanol in place of methanol. The results are given in Table i
Example 2 The same experimental set up described in F:xample 1 was used to study the transesterification of a triglyceride mixture using the conditions given in Table 2. A clay of pH~8 was used as catalyst and refined groundnut (peanut) oil was used as the substrate. For transesterification, a clay of higher pH was more active Progress of the reaction was monitored by thin layer chromatography. At the end of the reaction no spot corresponding to triglycerides was seen and the reaction was taken as complete. After the reaction the contents were cooled and the catalyst was filtered off. From the crude product excess methanol was distilled out and then the product
was dried under vacuum Pure esters were obtained by distillling the product at 180-2I0°C under 8-12 mm vacuum.
Example 3 Using the same experimental set up and conditions as described in Example 1, commercial samples of acid oil and soybean deodorizer distillate (both samples being mixtures of triglycerides and fatty acids) were converted to methyl esters using a clay of pH ~ 8 as catalyst under the conditions described in Table 3 The product was recovered as described in Example 2.
Siniukaacous Esleriricalion and Transesterification of Fatty Acids and
Example 4 800 g of crude jatropha oil of acid value 20 I and 200 ml of methanol were charged to a 2 L stainless steel autoclave equipped with a stirrer, temperature control and sampling device. The contents were heated to 200°C and the reaction was further continued at this temperature for 5 5 h at a pressure of 20 kg/cm2. Progress of the reaction was monitored by thin layer chromatography (TLC). When TLC did not show any spot corresponding to glycerides, the reaction was assumed as complete. At the end of the reaction time, the contents were cooled and the lower glycerol layer was separated. From the crude product excess methanol was distilled out and then the product was dried under vacuum. The product was analyzed for acid value and bound glycerol content. The results are shown in Table 4 Pure esters were obtained by distilling the product at 180-210°C under 8-12 mm vacuum
Example 5 The reaction was carried out in 10 L SS autoclave The experiment was conducted as in Example 4 except that the ratio of jatropha oil to methanol (wt/vol) was 1:1. The results are shown in Table 4
Example 6 The reaction was carried out as in Example 4 except that the jatropha oil used had acid value of 49. The results are shown in Table 4.
Example 7 The reaction was carried out as in example 4 except that the oil used was crude rice bran oil of acid value 20.4, The results are shown in Table 4
Example 8 The reaction was carried out in a IL SS autoclave. The reaction was carried out as in example 4 except that the raw material used was deodorized distillate of soybean oil of acid value 96. Oil to methanol ratio (wt/vol) used was 10:3, About 80% of the reaction was completed at this stage. The lower glycerol layer was scpartcd niui the producl was .subjectcd to a .second trearment as dcscribed abovc to complete the reaction. The results are shown in Table 4
Example 9 Here acidulated soapstock of acid value 130, a byproduct from rice bran oil processing was used as raw material. The reaction was carried out in a !L SS autoclave. The reaction was carried out as in example 4 except the raw material used was rice bran acid oil of acid value 130. Oil to methanol ratio (wt. / vol.) used was 10.3. About 80% of the reaction was completed at this stage. The lower glycerol layer was separated and the product was subjected to a second treatment as described above to complete the reaction The results are shown in Table 4
Example 10 In this example stearic acid of acid value 197.5 was used as the raw material The reaction was carried out in'a IL SS autoclave. 400 g of stearic acid and 120 ml of methanol were charged to the reactor The reaction was carried out at 190-200°C for 6 h. At this stage about 80% of the reaction was completed Water layer was removed and the product was subjected to a second treatment as described above to complete the reaction. The results are shown in Table 4
Example 11 The reaction was carried out as described in Example !0 with stearic acid and with alcohols from C2 to C10 range.
Example 12 Polyol esters for commercial applications are prepared by esterification of polyalcohols and short chain carboxylic acids like octanoic acid and 2-ethyl hexanoic acid or their mixtures. The polyol esterification reaction was carried out with 39 4 g of pentaerythritol and 258 g of carboxylic acid (Cg) in a 1 L SS autoclave as described in Example 10. The acid value of the product was 143. At this stage the water separated was removed and the reaction was continued for another 5 h. At this stage the product had acid value of 127.8. The excess acid was removed by distillation and the polyol ester had acid value II.
The reaction was carried out with 400 g of diinerized fatty acids from split castor oil and 200 ml of methanol. The reaction was conducted as described in Example 10. The results are shown in Table 4
Example 14 The reaction was carried out with 600 g of dimerized fatty acids from split castor oil and 338 g of 2-ethyi hexanol. The reaction was conducted as described in Example 10. The results are shown in Table 4
The main advantages of the present invention
1. The present invention uses a single heterogeneous catalyst (easily removable
by filtration) for esterification of free fatty acids and transesterifunction of the glycerides in one step
2. Glycerol is obtained in a concentrated form free (rem inorganic salts. Thus
considerable energy is saved in concentrating the dilute glycerol solutions obtained in the conventional processes.
3. There is no neutralization of the catalyst used as in the case of homogeneous
catalysis and hence no aqueous effluents are generated. The present method is thus more environmentally friendly
The heterogeneous catalyst as used in the present invention has the advantage that the solid catalyst can be easily removed by filtration The invention has particular applicability to the simultaneous esterification of free fatty acids in admixture with triglycerides in a single step even m the presence of small amounts of water. The invention has particular applicability to the transesterification of crude or refined oils and to add oils (a mixture of free fatty acids and glycerides) obtained by acidulation of soapstock and the deodorizer distillate obtained from the conventional oil refining process The latter two could be important sources of value added, important minor constituents of vegetable oils such as tocopherols, sterols, oryzanol, etc.
5. The present invention can also be carried out without the heterogeneous
catalyst for the simultaneous conversion of carboxylic acids and glycerides to methyl esters thus avoiding the filtration step.
We claim :
1. A process for simultaneous conversion of carboxylic acids and their glycerides to alkyl esters which comprises reacting carboxylic acid / or their glycerides with an alcohol wherein the ratio of alcohol varies from 1:1 to 1:10 optionally in presence of a montmorillonite clay catalyst in the range of 3 to 8% by wt based on wt of raw material at a temperature in the range of 130-250°C, at pressure in the range of 5-25 kg/cm for 2 to 8 hr. and recovering the alkyl ester by conventional method.
2. A process as claimed in claim 1, wherein the free carboyxlic acid or carboxylic acid component of the glyceride is a C10 to C24 carboxylic acid or a mixture of such acids commonly found in vegetable oils or other natural oils and fats or their reaction products.
3. A process as claimed in claims 1 to 2 wherein the source of long chain carboxylic acids used for esterification are acid oil obtained by acidulation of soapstock.
4. A process as claimed in claim 1 to 3 wherein another preferred source of long chain carboxylic acid used for esterification is deodorizer distillate obtained from a vegetable oil.
5. A process as claimed in claim 1 to 4 wherein the carboxylic acids used for esterification are selected from vegetable oils selected from the group consisting of
groundnut oil, soybean oil, ricebran oil and jatropha oil.
6. A process as claimed in claims 1-5, wherein the fatty acids are straight chain or branched chain carboxylic acids.
7. A process as claimed in claim 1 to 6 wherein the alcohols used for reacting with carboxylic acids are selected from C1 - C8 alcohols selected from the group consisting of methanol, isopropanol, 2-ethyl hexanol, polyol. selected from trimethylolypropane, pentaerythritol, di-pentaerythritol.
8. A process as claimed in claims 1-7, wherein the alcohol is monohydric or polyhydric alcohol.
9. A process as claimed in claim 1 to 8 wherein the catalyst is separated or removed by filtration at the end of the esterification reaction.
10. A process as claimed in claims 1-9, wherein the acid or acid mixture is esterified with one or more C1-C8 alcohols or their mixtures.
11. A process as claimed in claims 1 to 10 wherein modified clay catalyst used has the pH ranging between 4.0-8.0,
12. A process as claimed in claims 1 to 11 wherein the esterification reaction is carried out at the temperature ranging between 180-2]0°C preferably.
13. A process as claimed in claims 1 to 12 wherein the esterification reaction is carried out for 4 to 11 hr. and preferably for 4 hrs.
14. A process as claimed in claim 1 to 13 wherein the esterification is carried out in the presence or absence of any one or more glycerides.
15. A process as claimed in claims 1-14 wherein a clay of higher pH~8 is more preferable for transesterification of vegetable oils to esters.
16. A process as claimed in claims 1-15 wherein a clay of pHI~4 is more preferable for esterification of fatty acids.
17. A process for the simultaneous conversion of carboxylic acids and their glycerides to the alkyl esters substantially as herein described with reference to the examples accompanying the specification.
|Indian Patent Application Number||659/DEL/2000|
|PG Journal Number||35/2010|
|Date of Filing||18-Jul-2000|
|Name of Patentee||COUNCIL OF SCIENTIFIC AND INDUSTRIAL RESEARCH|
|Applicant Address||RAFI MARG, NEW DELHI-110001, INDIA|
|PCT International Classification Number||C07C 69/00|
|PCT International Application Number||N/A|
|PCT International Filing date|