US2487611A - Purification of glycerin - Google Patents

Description

Patented Nov. 8, 1949 UNITED STATES PATENT OFFICE PURIFICATION OF GLYCERIN tion of New Jersey No Drawing. Application August 15, 1947, Serial No. 768,926

16 Claims.

This invention relates in general to the purification of essentially anhydrous glycerine, and more particularly to a process for refining essentially anhydrous glycerine obtained by the trans-asterification of fatty materials.

From time immemorial, glycerine has been obtained chiefly as a by-product of the soap making industry. Conventional soap making processes involve the saponification of suitable fatty materials with an alkali such as sodium or potassium hydroxide. The reaction produces the alkali metal soaps of the fatty acids and glycerine. In the process of separating the soap from the reac-- tion mass and purifying it, considerable quantities of water and common salt are utilized in the form of brine. Thus the glycerine resulting from the saponification process ends up in a very dilute aqueous solution, which solution contains not only the glycerine but also considerable salt as well as various impurities originally associated with the fatty material or resulting from side reactions during the saponification. In order to obtain a relatively pure, high quality glycerine from this impure, dilute aqueous solution, or spent soap-lye as it is commonly known, numerous involved processes have been proposed. Such processes not only add to the cost of the final product, but also it is relatively difficult to obtain good yields of anhydrous glycerine thereby. A part of this poor recovery of the glycerine is inherent in the saponification process itself; however, a considerable amount of the loss is directly attributable to the inefficiency of the recovery processes.

In recent years it has been proposed to prepare esters of the fatty acids by reacting fatty materials with low molecular weight, monohydric alcohols such as methanol or ethanol in the presence of alkaline or acidic transesterification catalysts. These esters, after separation from the reaction mass and purification, may be used per se or saponified to produce high quality soaps. The glycerine which results from such transesterification of glycerides is in an essentially anhydrous condition; however, the glycerine does have associated with it various impurities which were originally associated with the fatty materal, were produced by side reactions during the transesterification process, or were added to or produced in the reaction mixture incident to the separation and purification of the end products. Difiiculties have been encountered in removing these impurities from the crude essentially anhydrous glycerine and obtaining purified, high quality glycerine. In one transesterification process it is recommended that the glycerine obtained be diluted with water before an attempt is made to purify it. Not only does this discard the advantage of having obtained the glycerine in an anhydrous state, but also the addition of the water increases the solubility of certain of the impurities in the resulting glycerine solution thus increasing the difiiculty of refining the glycerine as regards these impurities.

In the copending application of Sprules and Price, Serial No. 761,160, filed July 15, 1947, there is disclosed an improved process for preparing alkyl esters of the fatty acids involving first transesterifying fatty glyceride materials having acid values of at least one with low molecular weight alcohols employing an alkaline material in sufficient quantity to neutralize the free fatty material, and provide suflicient alkaline material to serve as an alkaline catalyst, and then adding sulfuric or phosphoric acid to the reaction mixture in sufficient amount to split what soaps were previously formed, neutralize the alkaline catalyst, and provide suficient acidic material to serve as an acid catalyst, and thereafter esteriiying the free fatty acids in the mass with the alcohol therein.

It is the object of this invention to provide an improved process for refining the crude, essentially anhydrous glycerine obtained'by the Sprules and Price process disclosed in the above-identified application.

Other objects of the invention will in part be obvious and will in part appear hereinafter.

It has now been discovered that the foregoing and other objects of the invention may be realized by reacting the acid catalyst after the esterification of the free fatty acids is completed, either with or without separating the acidic, crude anhydrous glycerine from the reaction mass, with an alkaline earth carbonate, i. e. calcium carbonate, barium carbonate, or strontium carbonate, subsequently treating the crude anhydrous glycerine with a small amount of a compound selected from the group consisting of the halides of calcium,

barium and strontium by admixing such a comfined product has not been definitely determined, but one possible explanation is as follows: Assuming that sodium hydroxide and sulfuric acid have been employed as the alkali and acid catalysts respectively and designating the carbonate as MCO3 where M is barium, strontium or calcium, the sulfate ion in the crude glycerine is converted into an insoluble alkaline earth sulfate. An equimolar amount of sodium bicarbonate is also formed according to the following equation:

Any very small excess of sulfuric acid is converted into the alkaline earth sulfate according to the following equation:

In the second step of the refining process, the alkaline earth halide (MXz) reacts with the sodium bicarbonate formed during the first step of the process to produce an alkaline earth bicarbonate and sodium halide according to the following equation:

In this manner the residual acidic salts in the crude 'glycerine are all converted to neutral salts which are insoluble in the glycerine and can be removed by filtration.

The explanation of the manner in which the process may work applies equally as well if the acid catalyst is phophoric acid instead of sulfuric acid or if an alkali metal compound other than a sodium compound is employed as the alkaline catalyst. The suggested mechanism for the proccess is well borne out in practice, but we do not limit ourselves to such an explanation. Regardless of whether the above explanation is the proper one, we do know that the refining process as set out above, i. 6. reaction of the acid catalyst with one of the basic compounds listed, followed by treatment of the crude essentially anhydrous glycerine with a halide salt as set forth'and subsequent removal of insoluble materials from the glycerine-salt mixture, will produce an excellent grade of refined essentially anhydrous glycerine much more simply and with greater yields than previous refining processes. In view of the dificulties which have been encountered in the prior art in attemptin to refine the glycerine obtained by transesterification procvarious impurities in the glycerine into a form in which they may readily be separated from the glycerine. Thus it is quite apparent that the mechanism of our precess is considerably more involved than the simplified explanation given above might indicate.

In the Sprules and Price process of producing the alkyl esters from the fatty materials through transesterification followed by esterification, some water is unavoidably produced whenever the alkaline catalyst which is employed is one of the alkali metal hydroxides. The water is formed when the hydroxide is neutralized with either sulfuric or phosphoric acid preparatory to carrying out the esterification step of that process; however, since the amount of alkaline catalyst which is employed is quite small only a very small amount of water is produced by such neutralization. A small amount of water is also produced by the chemical reactions involved in our refining process, but the amount produced in that manner is also quite small. In fact the total amount of water produced by both the neutralization of the alkaline catalyst when such catalyst is an alkali metal hydroxide and by the re actions which occur in our refining process is so small that, comparatively speaking as regards such sources of water, the glycerine produced will be relatively water-free.

If the fatty material being employed in the Sprules and Price process has a relatively low acid value, c. g. 10 or below, the amount of water produced by neutralization of the free fatty acids prior to carrying out the transesterification step of that process will be quite small. However, when the fatty material has a relatively high acid value, the amount of water produced by the neutralization of the free fatty acids will be appreciable. Therefora'in order to obtain relatively anhydrous glycerine in such a case, it is preferred to carryout the Sprules and Price process under conditions such that the water of reaction will be continuously-removed, e. g. by carrying out the processunder reflux conditions and continuously separating the water from the alcohol being employed "either by drying the alcohol-Water azeotrope over caustic alkali, or by mechanically separating the water from the alcohol in a Dean trap When the alcohol employed is one relatively immiscible with water, or by any other suitable means. However, if desired, the Sprules and Price process may in all cases be carried out under conditions such that the water of reaction will be continuously removed.

Any water left in the glycerine after the main steps of our refining process will be removed for the most part when the glycerine is freed of any of the alcohol used in producing the alkyl esters which is still associated with the glycerine. Also if the refined glycerine is itself distilled under reduced pressures so as to obtain a completely pure product, it may be completely freed during such distillation 'of. any water still associated therewith, and thus refined, completely anhydrous glycerine may be obtained.

In carrying out theprocess of the invention, the crude essentially anhydrous acidic glycerine is first neutralized with a basic compound selected from the group consisting of calcium carbonate, barium carbonate, and strontium carbonate. This neutralizationmay be carried out on the entire reaction mass prior to the removal of the anhydrous glycerine therefrom, or the essentially anhydrous glycerine may first be removed and'then neutralized. After the essentially anhydrous glycerine has been'so treated, either as a part of the esterification reaction mixture or after separation from the reaction mixture, it may be filtered, if desired, to remove any insoluble material therein. If desired, the treated glycerine may be heated for a short time prior to such filtration since such heating will often aid in converting the insoluble impurities therein into a form more readily removable by filtration. Such heating may conveniently be carried out by heating the treated glyceri'ne at about 60 C. or above by any convenient means, e. g. by a steam bath, for a short time,e. g. about half an hour.

The glycerine is then further treated by admixing therewith a small amount of one of the halide compounds suitable for use in the second step of the refining process. If the first treatment with the alkali metal carbonates is carried out without separating the essentially anhydrous glycerine from the esterification reaction mass, such a separation is made before adding the halide compound to the glycerine. In order to have a relatively fluid material to work with, it is usually preferred to allow a small amount of the alcohol employed in the esterification to remain with the glycerine during the refining. Not only does it give a material which is easier to handle, but it also helps to prevent loss of glycerine due to adherence to filters during filtration. If, for some reason or other, all of the alcohol has been separated from the essentially anhydrous glycerine during the removal thereof from the esterification mixture, a suitable amount of the esterification alcohol or a similar alcohol may, if desired, be added to the glycerine so that it will be less viscous. However, this is not necessary and, if it is preferred, the process may be carried out on essentially anhydrous glycerine completely free of alcohol. After admixture of the anhydrous glycerine and the halide compound, the mass may be heated for a short time, if desired, in order to bring about a more efficient interaction between the halide compound and the impurities in the glycerine. The heating may be carried out at any desired temperature below that which would deleteriously affect the glycerine. A suitable temperature is from about 60 C. to about 120 C. When the glycerine being treated still has alcohol associated therewith, the heating may suitably be carried out in general at the reflux temperature of the alcohol. The length of time of heating may vary considerably; however, heating for about half an hour to an hour will in most cases bring about the desired degree of refining although the mass may be heated for a longer period, if desired. The amount of heating is not critical since even a small amount of heating will aid in the refining of the glycerine. After the treatment with the halide compound the glycerine is filtered to remove any insoluble salts and any other insoluble matter. The product obtained is a light colored, essentially anhydrous glycerine of good quality. If any alcohol is still admixed with the glycerine, it may readily be removed by a simple distillation.

The essentially anhydrous glycerine obtained by the process as described hereinabove is of good quality, and for many purposes for which it may be used, e. g. as a plasticizer, in adhesives, etc., no further treatment whatsoever is necessary; however, for some purposes it may be desirable to refine the glycerine further. Occasionally the glycerine will have a rather opaque or cloudy appearance or in some cases it may even be viscous or pasty. This is caused by the presence in the glycerine of small amounts of salts and other impurities which in some cases may be of such small particle size that it will sometimes be difficult, if not impossible, to remove them by ordinary filtration. If it is desired to further refine the essentially anhydrous glycerine by distillation thereof under reduced pressure, it is rather important to remove relatively large percentages of such impurities present prior to the distillation since we have found that their presence during the distillation may tend to decompose the glycerine thus reducing the final yield and deleteriously affecting the quality of the product as some of the decomposition products distill over with the glycerine giving it undesirable odors and colors as well as reducing the purity thereof.

If any difficulty is encountered in removing such impurities from the glycerine by filtration means, the impurities may be removed for the most part by contacting the anhydrous glycerine containing the impurities with a solvent selected from the group consisting of methanol, ethanol, propanol, butanol, and acetone. The extraction process should preferably be carried out at about room temperature or a temperature below room temperature, and in each extraction the ratio of the solvent to the essentially anhydrous glycerine containing the impurities should preferably be from about 1 to 3 to about 1 to '7 in order to obtain the best results. Under such conditions these solvents, which are immiscible with the impurities in the glycerine, will be found to be somewhat immiscible with the essentially anhydrous glycerine containing the impurities but relatively miscible with glycerine which is more or less free of such impurities. Thus when such a process is carried out, the solvent will extract relatively pure, essentially anhydrous glycerine from the mixture of essentially anhydrous glycerine and impurities. By carrying out successive extractions, the essentially anhydrous glycerine may easily be separated from the greater part of the impurities contained therein. When using acetone as the extracting solvent, it will usually be necessary to carry out a greater number of extractions than when employing the other solvents since acetone is not too miscible with glycerine. The essentially anhydrous glycerine containing the impurities may be contacted with the solvent in any desired manner. A liquid-liquid extraction apparatus may be em-- ployed, or if desired a batch extraction process may be used with successive portions of the solvent being contacted with the glycerine. By simply filtering the combined solvent extracts and removing the solvent therefrom, e. g. by distillation under reduced pressure, a fairly pure grade of glycerine will be recovered. This essentially anhydrous glycerine may then, if desired, be readily distilled without any decomposition to give in most cases a colorless, odorless, neutral, anhydrous glycerine of substantially C. P. quality.

If any diflioulty is experienced in separating the essentially anhydrous glycerine from the more or less colloidally sized impurities by means of the solvent extraction process as set forth in the previous paragraph, an alternate procedure may be employed. The essentially anhydrous glycerine mass may be completely dissolved in either methanol, ethanol, propanol, or butanol by employing an excess of the solvent. Acetone is then added to the solvent solution until a precipitate of the impurities just begins to form. Preferably an amount of the solvent just sufficient to cause the precipitate to redissolve is then added. The mass is then digested by heating for a short time, c. g. by heating on a steam bath for about half an hour at a temperature of about 50 to 60 C. or above. This treatment will cause practically all of the impurities which are still associated with the essentially anhydrous glycerine to precipitate out, and they may then be readily removed from the glycerine by filtration. After removal of the solvent from the solvent solution of the glycerine, the glycerine may be further purified by distilling it under reduced pressure if desired.

In carrying out the distillation of the essentially anhydrous glycerine under reduced pressure, the glycerine may be co-distilled with mineral oil if desired. Such a procedure will help prevent slight decomposition of the glycerine,

woman and in some cases will help obtain a more'nearly complete recovery of the refined glycerine. Any good grade of mineral oil having a boiling point temperature about the same or slightly higher than that of glycerine may be utilized in such a co-distillation process.

Halide salts which are suitable for use in the process of our invention are the chlorides, fluorides and bromides of calcium, barium, and strontium. Suitable mixtures of these salts may also be used if desired. Of these many salts we prefer to employ the barium halides, and in particular we prefer to employ barium chloride in view of the somewhat better results obtained with this compound. Also, the use of certain of the strontium and calcium halides involves disadvantages which are not encountered in the use of the barium halides. For example, strontium chloride is usually sold in the form of a hydrate containing six molecules of water. If such a compound were used in the refining of the glycerine, a certain amount of the water of hydration would become associated with the glycerine, and thus the advantage of having had the glycerine originally in an essentially anhydrous condition would be discarded. Of course, the anhydrous strontium chloride could suitably be used, but its use would increase the cost of the process. Calcium chloride may be acidic and care must be taken that the amounts thereof employed are no greater than required to accomplish the refining of the glycerine. Otherwise, the glycerine may be rendered fairly acidic and as a result tend to decompose if and when it is later distilled as a further step in the refining process.

The amount of alkaline earth halide which is employed in the halide salt treatment step of the invention is preferably determined by calculating the amount thereof which would be required to react with the sodium hydroxide, or other similar alkali metal compound employed as the alkaline catalyst during the esterification of the original fatty material, which is present in the glycerine layer. We have found that such an amount of the alkaline earth halide gives very effective results in refining the essentially anhydrous glycerine. Slightly smaller proportions of the alkaline earth halide may be employed, however, if desired.

After the neutralization of the acid catalyst with an alkaline earth carbonate, and after the halide treatment step of our process, insoluble materials may be separated from the glycerine by means other than filtration, for example by centrifugation, etc., if desired, as well as by the solvent extraction processes described hereinabove.

Eor a fuller understanding of the nature and objects of the invention, reference may be had to the following examples which are given merely to further illustrate the invention and are not to be construed in a limiting sense.

Example I 1800 parts of peanut oil having an acid value of one were reacted with 960 parts of methanol (a ratio of five moles of methanol per fatty acid equivalent) first transesterifyin the glycerides in the peanut oil by refluxing the reaction mixture for one hour in the presence of 18 parts of sodium hydroxide; then adding 90 parts of sulfuric acid to the transesterification mass thus splitting what soaps were formed from the free fatty acids in the peanut oil, neutralizing the sodium hydroxide, and providing sufficient acidic material to serveas an acid catalyst; and then esterifying the liberated fatty acids with the methanol in the reaction mass by refluxing the mass for approximately four hours.

The mass was then cooled and 200 parts of barium carbonate added thereto. This was the amount theoretically required to neutralize the acid mass plus about a ten percent excess. The neutralized mass was agitated on a steam bath for about two hours and then filtered to remove insoluble material therein. Excess methanol was removed by distillation and the esters and glycerine allowed to separate. The glycerine layer was drawn oif and 58.2 parts of BaClzZl-IzO added thereto. This was an amount of barium chloride sufficient to convert the sodium ions in the glycerine into sodium chloride. A quantity of methanol equal to about three times the weight of the glycerine was then added and the mass heated at the reflux temperature of the methanol for about two hours. The methanol by rendering the mass more fluid allowed a more efficient interaction to take place between the barium chloride and the impurities in the glycerine. After this treatment, the methanol was removed, and the glycerine filtered to remove precipitated material. The glycerine still appeared to contain some impurities as evidenced by its opaque and cloudy appearance. These impurities were either actually in solution in the glycerine or were more or less of a colloidal size otherwise they would have been removed when the glycerine was filtered. However, we found, as pointed out hereinabove in the specification, that by solvent extraction of the glycerine these impurities could be removed.

The glycerine was repeatedly extracted with small portions of methanol at room temperature. On each extraction the methanol removed a small quantity of relatively pure glycerine from the glycerine containing the impurities. Thus it was possible to almost completely separate the glycerine from the impurities. The combined methanol extracts were filtered and the methanol removed therefrom. The glycerine obtained was then distilled under reduced pressure giving a yield of anhydrous glycerine of 86% based upon the amount of peanut oil employed. This anhydrous glyceri-ne was colorless, odorless and had a pH of '7. No decomposition at all was evident during the distillation.

Example II 1650 parts of coconut oil having an acid value of approximately five were reacted with methanol in the same manner as in Example I except that only 2.3 moles of methanol per fatty acid equivalent were employed as compared to 5 moles in Example I.

Upon completion of the reaction, the acid mass was neutralized with 185 parts of barium carbonate, and further treated as in Example I. The glycerine layer was then admixed with 47.3 parts of anhydrous barium chloride and treated as in Example I.

first few extractions had been made with methanol the remaining extractions were made With butanol. The glycerine was recovered from the alcoholic extracts, and it was then distilled under reduced pressure giving very high quality, anhydrous glycerine in a yield of 72% based upon the amount of coconut oil employed. During the distillation no decomposition at all was evident.

Example III 1800 parts of peanut oil having an acid value of one were treated with 960 parts of methanol by the same process as that of Example I except that only 46.2 parts of sulfuric acid were employed as compared to 90 parts in Example I. Also, in the neutralization of the acidic mass, 50 parts of calcium carbonate were employed instead of the barium carbonate. After 61 parts of BaCl2.2HzO were added to the glycerine which was obtained, the glycerine was heated on a steam bath in the presence of methanol for a short time as in Example I. No precipitation of salts occurred at this point, but instead the insoluble salts appeared to remain in more or less of a colloidal state. Upon removal of the methanol from the mixture, a paste-like mass which was too thick to filter was obtained. It was found that the insoluble salts could readily be separated from the glycerine by redissolving the paste-like mass in methanol, adding acetone to the methanol solution until a precipitate just began to form, and then heating the mass on a steam bath for about half an hour. This treatment caused the salts and other insoluble matter present to separate out as a flocculent precipitate which was readily removed from the solution by filtration. The solvent was removed from the anhydrous glycerine by distillation, and the anhydrous glycerine was distilled under reduced pressure. A yield of anhydrous glycerine of excellent quality which was 82% of the theoretical yield was obtained. It was entirely odorless and had a pH of 7.

Example IV Another sample of anhydrous glycerine obtained from peanut oil employing the same amounts of materials as in Example III was treated by a process the same as that of Example III with the exception that '73 parts of strontium carbonate were employed in place of calcium carbonate. Also, only 48 parts of BaC1z.2H2O were employed. As in Example III, excellent quality anhydrous glycerine in very good yield was obtained.

Example V 110 parts of hydrogenated fish oil having an acid value of approximately 20 were reacted with 52.5 parts of methyl alcohol (which involved refiuxing for one hour in the presence of 1.1 part of sodium as an alkaline catalyst followed by a four hour refiux after addition of 5.5 parts of sulfuric acid to serve as an acid catalyst). When the reaction was completed, the mass was neutralized with 7.0 parts of calcium carbonate, filtered, the most of the excess methanol removed by distillation, and the glycerine layer separated from the ester layer. The glycerine was admixed with 1.8 parts of CaFz and the mixture, which also contained a small amount of the excess methanol from the esterification reaction, was heated at about 65 C. for about an hour, filtered, freed of the methanol, and the residue vacuum distilled at 1 mm. Excellent quality, anhydrous glycerine in a yield of 67% was obtained.

Our process is particularly applicable for the refining of essentially anhydrous glycerine, but it is obvious, of course, that it is also applicable to the refining of glycerine which is not essentially anhydrous. Consequently, if it were desired, the process could be employed for refining crude glycerine obtained by the transesterification of fatty materials employing a combined alkali and acid transesterification process even though such glycerine contained an appreciable amount of water. However, as has been pointed out above, the presence of large amounts of water in the glycerine considerably complicates the refining process.

Having described our invention what we claim as new and desire to secure by Letters Patent is:

1. In a process for refining glycerine obtained by transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic glycerine with an alkaline earth carbonate, treating the glycerine with an alkaline earth halide, and then separating the glycerine from insoluble material formed therein.

2. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, removing insoluble material formed therein from the esterification mass, separating the glycerine from the esters, treating the glycerine with an alkaline earth halide, and separating the treated glycerine from insoluble material formed therein.

3. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising separating the glycerine from the acidic esterification mass, neutralizing the acidic glycerine with an alkaline earth carbonate, treating the glycerine with an alkaline earth halide, and separating the treated glycerine from insoluble material formed therein.

4. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, removing insoluble material from the esterification mass, removing any excess unreacted alcohol from the esterification mass, separating the glycerine from the esters, treating the glycerine with an alkaline earth halide, and separating the treated glycerine from insoluble material formed therein.

5. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, heating the mass for a short time to aid in converting insoluble material in the mass into a more easily removable form, removing insoluble material formed therein from the esterification mass, removing any excess unreacted alcohol from the esterification mass, separating the glycerine from the esters, mixing the glycerine with an alkaline earth halide, heating the mass for a short time, ex-

11* tracting' the halide treated glycerine at a temperature not above about room temperature with a solvent selected from the group consisting of methanol, ethanol, propanol, butanol, and acetone, and recovering refined glycerine by removing thesolvent from the solvent extracts.

6. In a processfor refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterificati'on with an acid catalyst,.the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, heating the mass for a short time to aid in converting insoluble material in the mass into a more easily removable form, removing insoluble material formed therein from the esterification mass, removing any excess unreacted' alcohol from the esterification mass, separating the glycerine from the esters, mixing the glycerine with an alkaline earth halide, heating the mass for a short time, dissolving the halide treated glycerine in at least an equal weight of an aliphatic mon'ohydric alcohol containing not more than 4 carbon atoms, adding acetone to the alcoholic solution until a precipitate just begins to form, heating the solution for a short time, removing insoluble material formed therein from the solution, and recovering refined glycerine by removin the solvent from the solvent solution.

'7. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transest'erification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, removing insoluble material formed therein from the esterification mass, separating the glycerine from the esters, treating the glycerine with barium chloride, and separating the treated glycerine from insoluble material formed therein. I

8. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising separating the glycerine from the acidic esterification mass, neutralizing the acidic glycerine with an alkaline earth carbonate, mixing the glycerine with barium chloride, and separating the treated glycerine from insoluble material formed therein.

9. In a process for refining glycerine obtained by the transesteri'ficationof a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with an alkaline earth carbonate, removing insoluble material formed therein from the esterification mass", removing any excess unreacted alcohol from the esterification m'ass, separating the glycerine from the esters, treating the glycerine with barium chloride,- separating the treated glycerine from insoluble material formed therein, and distilling the glycerine under reduced pressure.

10. In a process for refining glycerine obtained by the transes'te'rification of a fatty material wherein the transesterification process is catalyzed byan alkaline" catalyst followed by esterification' with an acid catalyst, the steps comprising neutralizing the acidic esterification the mass for a shorttimeto aid in converting insoluble material in the massv into a: more easily" removable form, removing insoluble material formed therein from the esterification mass, re moving any excess unreacted alcohol from the esterification mass, separating'the glycerine from the esters, mixingmthe glycerine with barium chloride, heating the mass for a short time, ex-

.tr'acting the barium'chloride' treated glycerine at a temperature not above about room temperature' with a solvent selected from the group con-- sisting of methanol, ethanol, propanol, butanol. and acetone, recovering refined glycerine by re:-

moving the solvent from the solvent solution,

and distilling the glycerine under reduced pressure.

11. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterificat'ion process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps com prising mass with an alkaline earth carbonate, heating the mass for a short time to aid in convertinginsoluble material in the mass into a more: easily removable form, removing insoluble material formed therein from the esterification mass, r'emoving any excess unre'acted alcohol from the esterification mass, separating the glycerine from the esters, mixing the glycerine with barium chloride, heating the mass for a short time, dissolving the barium chloride treated glycerine in. at least an equal weight of methanol, adding acetone to the alcoholic solution until a precipitate just begins to form, heating the solution for a short time, removing insoluble material formed therein from the solution, recovering refined glycerine by removing the solvent from the solvent solution, and distilling the glycerine under reduced pressure.

12. In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising neutralizing the acidic esterification mass with barium carbonate, removing insoluble material formed therein from the esterification mass, separating the glycerine from the esters, mixing the glycerine with barium chloride, heating the mass for a short time, removing the treated glycerine from insoluble material formed therein, and distilling the glycerine under pressure.

13 In a process for refining glycerine obtained by the transesterification of a fatty material wherein the transesterification process is catalyzed by an alkaline catalyst followed by esterification with an acid catalyst, the steps comprising separating the glycerine from the acidic esterification mass, neutralizing the acidic glycerine with barium carbonate, separating the neutralized glycerine from insoluble material formed therein, mixing the glycerine with barium chloride, heating the mass for a short time, separating the treated glycerine from insoluble material formed therein, and distilling the glycerine under reduced pressure.

14. A process in accordance with claim 9 wherein the alkaline earth carbonate which is employed is barium carbonate.

15. A process in accordance with claim 10 wherein the alkaline earth carbonate which is employed is barium carbonate.

neutralizing the acidic esterification.

13 16. A process in accordance with claim 11 wherein the alkaline earth carbonate which is employed is barium carbonate.

FRANCIS J. SPRULES. RAYMOND LIEBLING.

REFERENCES CITED The following references are of record in the file of this patent:

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