US2385518A - Production of succinic and maleic acids from butyrolactone - Google Patents

Description

Sept. 25, 1945. R. M. ISHAM PRODUCTION OF SUCCINIC AND MALEIC ACIDS FROM BUTYROLACTONE Filed June 12, 1941 q 05, 92.00am A v 31110144 041 Rcljeri' M ZS/ZCUIZ/ Patented Sept. 25, 1945 PRODUCTION OF SUCCINIC AND MALEIO ACIDS FROM BUTYROLACTONE Robert M. Isham, Ohmulgee, Okla, assignor to Danclger Oil & Refineries, Inc., Fort Worth, Tex., a corporation of Texas Application June 12, 1941, Serial No. 397,810

12 Claims. (01. zoo-311) This invention relates to the production of succinic and maleic acids from butyrolactone.

In recent years, in the synthetic resin industry, the development of the alkyd type resins has been outstanding. These resins, which are the reaction products of polyhydric alcohols and dibasic acids, have found wide use and acceptance. In this type or material the anhydrides of the aliphatic dibasic acids such as succinic and maleic anhydrides are of distinct importance being valuable not only for the production of the alkyd type resins but also serving very effectively as modifiers for the phenolic and urea resins. The demand for such acids has thus greatly increased.

As has been explained in prior applications Serial Nos. 326,112 and 326,113, filed March 26, 1941, and No. 330,198, filed April 17, 1940, it is now possible to obtain butyrolactone in substantial quantities from cheap source materials, namely pyroligneous acid residues.

The present invention deals with the production of succinic and maleic acids from such readily available source material by an efllcient and economical method, namely by the catalytic vapor phase exidation of butyrolactone.

It is known in the art that butyrolactone can be oxidized to succinic acid. The methods pro posed heretofore contemplated the oxidation of the lactone by chemical oxidizing agents, such as nitric acid, chromic acid, permanganates and the like. Such methods were attended with certain disadvantages important among which was the difilculty of recoveringsuccinic acid from the reaction mixtures.

As a result of extensive experimentation in this field it has been found that the described conversion may be simply and eifectively accomplished by direct oxidation methods. As described in copending application Serial No. 397,809, filed June 12, 1941, this conversion may be effected by anodically oxidizing butyrolactone to succinic acid in a simple electrolytic cell. The

'present method deals with another method of conversion, similarly direct and effective, namely, the vapor phase oxidation of butyrolactone to produce succinic and maleic acids.

The present invention, briefly considered, comprehends the catalytic vapor phase oxidation of butyrolactone. The conversions involved proceed generally according to the following equations:

tively simple there are certain difliculties in volved. The oxidation reactions are accompanied by certain undesirable side reactions in which the four membered carbon chain is ruptured and products, such as carbon dioxide, acetaldehyde and acetic acid are formed. These decrease the yield of the desired products and complicate their recovery. It has been determined that these side reactions may be minimized and a concomitant increase in yield of the dibasic acids insured by carefully'controlling the relative proportion of oxygen employed in the reaction and controlling the temperature in definite correlation with the catalyst employed to within definite optimum ranges.

It has been ascertained equal, and with a particular catalyst the undesirable side reactions may be reduced by op erating at relatively low temperatures, that is to say, it has been learned that the primary reaction (lactone to dibasic acid) proceeds preferentially or more or less selectively at lower temperatures.

The particular temperature or temperature range which is most effective will in turn vary somewhat depending upon the particular catalyst which is utilized. For example, it. has been determinedthat when utilizing vanadium pentoxide and air as the oxygen supplying medium in the proper ratio of the reactants the'reaction proceeds best at between about 220 C. and 250 C.

that, other things being It is clearly to be understood that this is an op timum and not the limited operable range of temperature; below 220 C. reaction does take place but the rate is considerably lowered; conversely above 250 0. reaction proceeds but with an inordinate formation of the undesired side reaction products. It has been further found that with this particular catalyst oxidation of butyrolactone to the dibasic acids proceeds at temperatures up to 370 C. but at this elevated range the yield of the dibasic acids is quite low.

As noted above, the temperature range which is chosen for a particular operation should be correlated carefully with the particular catalyst employed. Thus if copper oxide is Used in lieu of vanadium pentoxide, for the best results the operating temperatures should be about 50 C. above those employed when using vanadium pentoxide.

It has also been ascertained that an important determinant in establishing an effective operation and securing a satisfactory yield is the proportioning of the oxygen to the butyrolactone in the reaction system. It has been established that a large excess of oxygen favors the undesired side reactions. Although reasonably good results have been obtained with a molecular ratio of oxygen to butyrolactone of 6 to 1 it is found in practice that best results are secured by establishing and maintaining this ratio at about 2 to 1.

The catalyst employed in the process may be utilized in any desired form but it is preferred to employ it supported on granular, inert material,

such as pumice or granular aluminum. The aluminum is especially preferred because, by reason tenuated form so as to insure optimum contact with the reacting vapors. Very satisfactory results have been obtained by using as the catalytic mass 10% by weight of vanadium pentoxide supported on granular aluminum.

The operation of the process will be more readily appreciated and its efiicacy evaluated by a consideration of a preferred mode of operation. In order more fully to describe the invention a typical, illustrative apparatus, in which it is carrled out, is shown diagrammatically in the single figure of the accompanying drawing.

As shown in the drawingoxygen or an oxygencontaining gas, such as air, is fed through the coil I, positioned in furnace 2. in order to preheat such air to the desired temperature. The air thus preincreased heated is fed continuously to the lower portion of the bubble column 3. Simultaneously a charge of butyrolactone is fed to the column throu h the line 4. 'In these circumstances the preheated air countercurrently contacts the downwardly flowing butyrolactone and the butyrolactone is vaporized and homogeneously mixed with the air. As noted previously. it is highly desirable to maintain a proper ratio or proportion of oxygen to butyrolactone. This may effectively be done by controlling the temperature of the preheated air admitted to column 3. In a typical operation, when air is utilized as the oxygen-supply medium, a vaporair mixture containing approximately 2 mols of oxygen to which 1 mol of butyrolactone may be produced by heating the air in coil l to a temperature of about 130 C.

The column 3, as will be appreciated, consti-- tutes a simple means for establishing a properly proportioned, potentially reactive vapor phase mixture of butyrolactone and oxygen and the heating coil not only subserves the function of preheating one of the reactants, i. e. oxygen, but also, by reason of the temperature control it serves, so to speak, as a metering device establishing the optimum proportions of the reactants. The vapor-gas mixture is withdrawn from the top of the column 3 and unvaporized butyrolactone collecting in the base of the tower may be returned by line 5 and pump 5' back to the charging line 4.

The proper proportionsof the reactants having been established as described, the mixture is then heated to reaction temperatures and then contacted with the desired catalyst to insure oxidation. As shown, this is done by passing the gasvapor mixture from the top of the tower throimh the coil 6 which is located in the furnace I. It has been found that salutary results are insured by constructing the coil 6 of aluminum since this has no catalytic effect on the reactants and thus tends to prevent or inhibit premature oxidation. In the coil 6 the mixture is raised to that temperature which is most suitable for reaction in view of the particular catalyst which is employed.

The properly proportioned heated mixture is then contacted with a catalyst. As shown, this is done by passing the mixture downwardly through the tubes 9 which are mounted within the chamber or container 8. The tubes are packed with the particular catalyst which is to be used,

i. e. vanadium pentoxide, copper oxide and the like, preferably supported on granular material as previously described. The catalyst may be retained in the tubes by a suitable means, such as the foraminous members or screens 9' attached to the lower ends of the tubes. The catalytic chamber 8 may be maintained at the desired temperature by any suitable means, as for example by heating the tubes by indirect contact with a liquid heating medium. This medium which, for example, may be a hydrocarbon oil, is admitted through line H and discharged through line H). While it is notshown, lines II and I2 may be connected in a closed circuit which includes a pump, together with heating and cooling means whereby the proper temperature may be maintained in unit 8 and the excessive heat of reaction removed.

In the passage through the catalytic chamber reaction proceeds according to Equations 1 and 2 given above to produce succinic and maleic anhydrides. The reaction mixture passes outwardly of the chamber through the line I 2 and contacts the scrubbing medium, such as water. introduced into column I 3 through line H and scrubs the upwardly flowing reaction mixture. The water flowing through line I! and downwardly over the plates of the column dissolves any unaltered butyrolactone and converts the succinic and maleic anhydrides to the respective acids and dissolves these acids. The upper portion of the column is pro- Vided with the condenser 15, which may be of the "tubular type which-is cooled by a suitable medium, such as water,.entering through line l6 and discharging through line l1. In this condenser section any, water evaporated by the hot gases is butyrolactone as well as side reaction products,

collects in'the base of the tower and is withdrawn through line I8. This solution may be treated tween about 220 C. and 250 by suitable methods to separate the individual components, as for example by distillation and/or crystallization and the like.

An operation conducted according to the foregoing description is particularly effective. In a typical operation employing an apparatus of the type described, butyrolactone was evaporated into air in the column 3 at a temperature of 130 C. The catalytic unit was maintained at a temperature of 235 C. and the reaction mixture was passed through the apparatus so that the contact time in the catalytic unit 8 was approximately seconds. On analysis of the recovered products it was found that 95% of the butyrolactone was oxidized and that 77% of the butyrolactone was converted to succinic and maleic acids in the ratio of 6 to 4. In this operation the catalyst employed consisted of vanadium pentoxide supported on granular aluminum in the proportion of 1 part by weight of the catalyst to 9 parts of aluminum.

It will be appreciated that the present method is as effective as it is simple. It will be observed, too, that the yields achieved with this process are very high and compare most favorably with comparable operations in the art. For example, in the past maleic acid has been produced by the oxidation of benzene at temperatures of the order of 400 C. In such operations a recovery of 60% is considered very good. In the present process, as indicated, a yield of over 75% of the desired products is easy to achieve.

The products produced by the present process, after separation or fractionation, may be used directly in the arts, as for example in the production of plastics. If desired these products may be further treated as by esterification to produce valuable solvents. Again, if desired the fractlonated maleic acid may be hydrogenated to succinic acid or hydrated to malic acid for use in food products. The invention thus comprehends the concept of producing succinic or maleic acid or any desired derivatives thereof from cheap source materials by the simple, direct oxidation method outlined.

I claim:

1. That method of producing succinic acid which comprises oxidizing butyrolactone, in vapor phase and at a temperature of between about 220 C. and 250 C., and in contact with a catalytic material chosen from the group consisting of vanadium pentoxide and copper oxide which promotes the oxidation.

2. That method of producing maleic acid which comprises subjecting butyrolactone to vapor phase oxidation at elevated temperatures bewith a catalyst chosen from the group consisting of vanadium pentoxide and copper oxide.

3. A method of treating butyrolactone to produce valuable products therefrom which comprises, mixing butyrolactone, in vapor phase, with an oxygen-containing gas and in the proportions of about 2 mols of oxygen to 1 mol of butyrolactone, contacting the mixture, at reaction temperatures between about 220 C. and 250 C., with a catalyst which promotes the oxidation of butyrolactone and recovering a reaction product containing appreciable percentages of succinic and maleic acids.

4. A method of treating butyrolactone to produce valuable products therefrom which comprises, mixing butyrolactone, in vapor phase, with an oxygen-containing gas and in the proto 1 mol of portions of about 2 mols of oxygen C. and in contactbutyrolactone, contacting the mixture, at reaction temperatures between about 220 C. and 250 C., with a catalyst chosen from the, group con sisting of vanadium pentoxide and copper oxide which promotes the oxidation of butyrolactone, contacting the products of oxidation with water and recovering a reaction product containing appreciable percentages of succinic and maleic acids.

5. A method of treating butyrolactone to recover valuable products therefrom which comprises, preheating an oxygen-containing gas, utilizing such preheated gas to contact and vaporize butyrolactone to produce a vapor phase mixture containing about 2 mols of oxygen to about 1 mol of butyrolactone, contacting the resulting gas-vapor mixture at elevated temperatures between about 220 C. and 250 C. with a catalyst chosen from the group consisting of vanadium pentoxide and copper oxide which promotes the formation of succinic and maleic anlrvdrides.

6. A method of treating butyrolactone to recover valuable products therefrom which comprises, preheating an oxygen-containing gas. utilizing such preheated gas to contact and vaporize butyrolactone to produce a vapor phase mixture containing about 2 mols of oxygen to about 1 mol of butyrolactone, contacting the resulting gas-vapor mixture at elevated temperatures between about 220 C. and 250 C. with a catalyst chosen from the group consisting of vanadium pentoxide and copper oxide which promotes the formation of succinic and maleic anhydrides, contacting the reaction products with water to recover succinic and maleic acids.

7. A method of treating butyrolactone to recover valuable products therefrom which comprises, preheating an oxygen-containing gas, utilizing such preheated gas to contact and vaporize butyrolactone to produce a vapor phase mixture containing about 2 mols of oxygen to about 1 mol of butyrolactone. contacting the resulting gas-vapor mixture at elevated temperatures between about 220 C. and 250 C. with a catalyst which promotes the formation of succinic and maleic anhydrides, contacting the reaction products with water to recover succinic and maleic acids and separating and recovering such succinic and maleic acids.

8. In the vapor-phase oxidation of butyrolactone to succinic and maleic anhydrides, that improvement which comprises, vaporizing'butyrolactone by contact with a heated oxygen-containing gas to produce a vapor phase mixture containing approximately 2 mols of oxygen to 1 mol of butyrolactone and oxidizing such mixture at a temperature of between about 220 and 350 C. in the presence of a catalyst chosen from the group consisting of vanadium pentoxide and copper oxide.

9. In the vapor phase oxidation of butyrolactone to produce succinic and maleic anhydrides that improvement which comprises, preheating air, passing the air countercurrently to a stream of butyrolactone to thereby vaporize the butyrolactone and intimately mix such vapors with the air to produce a vapor phase mixture containing approximately 2 mols of oxygen to 1 mol of butyrolactone, heating the vapor-gas mixture to temperatures of between about 220 C. and 250 C. which favor the oxidation of butyrolactone to succinic and maleic anhydrides and contacting the heated mixture with a catalyst chosen from the group consisting of vanadium pentoxide and copper oxide to produce succinic and maleic anhydrides. V

10. In the vapor phase oxidation of butyroiactone that improvement which comprises preheating a mixture of butyrolactone vapors and air to a temperature between about 220 C. and 250' C. in a container composed of aluminum and then contacting the heated mixture with a catalyst which promotes the oxidation of the butyrolactone to succinic and maleic anhydrides.

11. A method of producing succinic and maleic anhydrides which comprises preheating air to a. temperature of the order of 130 0., contacting such preheated air with a solution of butyrolactone to vaporize the butyrolactone to establish 15 a vapor phase mixture in the approximate ratio of 2 mols of oxygen to 1 moi of butyrolactone, heating the mixture in a separate heating zone to a temperature between approximately 200 C. and 375 C., passing the heated mixture in contact with a catalytic material which promotes the oxidation 01' butyrolactone and withdrawing the r reaction products containing succinic and maleic anhydrides.

12. A process in accordance with claim 11 in which the reaction products are scrubbed with water to recover an aqueous solution containing succinic and maleic acids.

ROBERT M. ISI-IAM.

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