US2999794A

US2999794A - Recovery of quinoline

Info

Publication number: US2999794A
Application number: US762915A
Authority: US
Inventors: Donald J Foster; Denvil E Reed
Original assignee: Union Carbide Corp
Current assignee: Union Carbide Corp
Priority date: 1958-09-24
Filing date: 1958-09-24
Publication date: 1961-09-12
Anticipated expiration: 1978-09-12

Description

United States Patent 9 2,999,794 RECOVERY OF QUINOLINE Donald J. Foster, South Charleston, and Denvil E. Reed,

Charleston, W. Va., assignors to Union Carbide Corporation, a corporation of New York No Drawing. Filed Sept. 24, 1958, Ser. No. 762,915 18 Claims. (Cl. 202-42) The present invention relates to the separation of organic compounds, and more particularly, to an improved process for recovering quinoline from a mixture with aromatic nitrogen-containing compounds.

The quinoline-containing mixtures with which this invention is concerned are those of the type produced, for example, by the liquid-phase hydrogenation of coal. In such a process, quinoline can be obtained in admixture with other aromatic nitrogen-containing compounds, and particularly with aromatic primary and tertiary amines, by distillation of the crude hydrogenation product. It is in association with this process, viz. the production of quinoline by the liquid-phase hydrogenation of coal, that especial advantage has been found to accrue in accordance with the practice of the invention. However, the invention is not limited in this respect, and can be employed to recover quinoline from any similar mixture of arcmatic nitrogen-containing compounds, notwithstanding the manner in which the mixture was initially obtained. For example, the process of the invention can be employed to recover quinoline from a mixture with other aromatic nitrogen-containing coal tars, such as that obtained as a by-prodnct during the coking of coal. The invention also finds suitable use in the recovery of quinoline from the crude reaction product formed by conventional processes for the production of quinoline from alkyl-substituted anilines.

Illustrative of the broad range of compounds found in the quinoline-containing mixtures contemplated by the invention there can be mentioned isoquinolines, alkylsubstituted quinolines, aniline, alkyl-substituted anilines, pyridine, alkyl-substituted pyridines and the like. Generally, aromatic nitrogen compounds of this nature evidence basic characteristics in that they are reactive with acids, particularly dilute mineral acids. Consequently, such compounds are commonly known as aromatic nitrogen bases, and will hereinafter so be defined.

In the past, various processes for recovering quinoline from a mixture with other aromatic nitrogen bases have been proposed by the art. Illustrative of these are processes involving either (a) fractional distillation of the mixture, or (b) the formation of aromatic nitrogen base salts by the addition of mineral acids, such as phosphoric or sulfuric acids, to the mixture, followed by the selective extraction of the quinoline salt from the resulting mixture by means of a suitable solvent, such as water or alcohol. Unfortunately, however, the use of these recovery techniques has not met with complete satisfaction, particularly when they are utilized to separate quinoline from aromatic nitrogen base mixtures in which compounds possessing physical properties close to or in common with the desired product are also present, and in which the initial concentration of quinoline is low.

For instance, it is at least difficult to distill a quinoline product of high concentration from an aromatic nitrogen base mixture such as that obtained by coal hydrogenation, containing in addition to quinoline substantial quantitles of alkyl-substituted derivatives of ailine and pyridine, such as 3-methyl-5-ethylaniline, 2,4,5-trimethylaniline, 2,6-diethylaniline, 2-tert.-butylaniline, 3,4-diethylpyridine, 2-ethyl5-propylpyridine, 2,4-diethy-l-3-methylpyridine, Z-butyl-S-methylpyridine, 2,6-dipropylpyridine and the like. Many of these compounds boil in a temperature range close to or overlapping that of the desired product. As a result, the distillate recovered from such a mixture by ordinary fractionation has often been found to consist of no more than about 35 percent by weight of quinoline, an amount which may be considered insufiicient for the commercial production of quinoline.

On the other hand, salts of many aromatic nitrogen bases, such as the phosphate or sulfate salts of alkylsubstituted derivatives of aniline and pyridine, evidence solubility characteristics in solvents such as water and alcohols comparable to those possessed by like salts of quinoline. Consequently, the separation of quinoline from an aromatic nitrogen base mixture by solvent ex traction techniques which are dependent upon the relative solubility of aromatic nitrogen base salts in the solvents described is rendered less effective in terms of product yield and concentration as the initial concentration of these other aromatic nitrogen bases in the mixture increases, and as the concentration of quinoline therein decreases. k I

Advantageously, these difficulties can now be overcome through the practice of the present invention, an object of which is to provide an improved process for the substantial recovery of quinoline from a mixture with other aromatic nitrogen bases as a product of high concentration. Another object of the invention is to provide an improved process for recovering quinoline from aromatic nitrogen base mixtures which process is not closely dependent upon the initial concentration of the various components of the mixture. Still other objects and advantages of the invention will become apparent in light of the following description.

In its broadest aspect, the invention contemplates subjecting a quinoline-containing aromatic nitrogen base mixture to azeotropic distillation in the presence of kerosene so as to obtain a distillate comprised essentially of a minimum-boiling quinoline-kerosene azeotrope. The quinoline component can then be recovered from the azeotropic distillate with facility in several different ways, as hereinafter described, and subsequently purified if desired. In this manner, it is possible to obtain a substantially pure product containing a quinoline concentration of up toabout 99 percent or more by weight, and representing a quinoline yield of up to about 93 percent or more by weight, even when the initial quinoline-containing mixture also contains appreciable quantities of closely related aromatic primary and tertiary amines.

In the practice of the invention, it is preferred, although not critical thereto, that the initial boiling point of the aromatic nitrogen base mixture subjected to azeotropic distillation be between about 230 C. and the boiling point of quinoline, i.e., about 238 C., and more preferably between about 234 C. and about 238 C. Greater efliciency and economy of operation can thereby be realized for the reasons stated below.

The invention is based in important part upon the finding that kerosene will azeotrope with quinoline, thus forming a mixture having a boiling point substantially below that of quinoline and many other aromatic nitrogen bases. In accordance with the invention, this azeotrope is taken advantage of to separate quinoline from the remaining components of the aromatic nitrogen base mixture.

In addition to quinoline, however, certain other compounds commonly present in aromatic nitrogen base mixtures have also been found to form minimum-boiling azeotropes with kerosene. Fortunately, the depression in boiling point as a result of kerosene azeotrope formation is generally not as great with the other aromatic nitrogen bases as with quinoline, particularly at subatmospheric pressures. Hence, the low-boiling quinoline-keroseneazeotropes can be separated from many of these compounds during azeotropic distillation, preferably by carrying out the distillation in a partial vacuum.

Nevertheless, the difiiculty and inconvenience encountered in engendering a substantially complete recovery of quinoline in high concentration, due to the presence of other kerosene azeotropes, becomes increasingly great as the initial boiling point of the aromatic nitrogen bases from which quinoline is to be recovered decreases below about 234 C., and especially below about 230 C. Compounds boiling at such low temperatures, particularly low-boiling alkyl-substituted an-ilines, are more likely to form azeotropes with kerosene which boil in approximately the same temperature range as the quinoline as contaminants in the azeotropic distillate. It is therefore expedient and preferable to eifect a preliminary separation or distillation of the quinoline-conta-ining aromatic nitrogen base mixture so that the azeotropic distillation can be directed specifically to a mixture having an initial boiling point of at least about 230 C. and more preferably at least about 234 C. In this manner, the need or desirability for subsequent purification of the quinoline product diminishes as the initial boiling point of the aromatic nitrogen base mixture is increased. In addition, lesser quantities of kerosene are required for the azeotropic distillation.

The preliminary separation or distillation of the ammatic nitrogen base mixture can be accomplished by any convenient means, either during production of the mixture or subsequent thereto. In connection with the liquid-phase hydrogenation of coal, for example, the quinoline-containing mixture can be obtained as a fraction having the desired initial boiling point by the exercise of control over the conventional distillation of the crude hydrogenation product.

In an embodiment of the invention, kerosene is suitably admixed with the quinoline-containing aromatic nitrogen base mixture and the resulting mixture introduced into a distillation zone. While quinoline has been found to azeotrope with a wide variety of hydrocarbons, particularly good results can be obtained in the invention when the kerosene employed as azeotroping agent has an initial boiling point of at least about 190 C., and preferably a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture. Higher or lower boiling kerosene fractions can also be employed. However, as the boiling point of the kerosene fraction decreases, the proportion of quinoline in the quinoline-kerosene azeotrope also decreases, often to an appreciable extent as the boiling point range of the kerosene fraction falls below 190 C. The yield of quinoline obtained upon subsequent separation of the azeotropic distillate is thereby diminished, although the purity of the product, i.e., the concentration of quinoline therein, remains unaffected. On the other hand, an increase in the boiling point of the kerosene fraction engenders an increase in the boiling point of the quinoline-kerosene azeotrope thus rendering more difficult the separation of the azeotrope from the remaining components of the aromatic nitrogen base mixture.

The initial concentration of quinoline in the aromatic nitrogen base mixture together with other factors such as the boiling point range of the mixture, particularly the initial boiling point thereof, and the ratio of quinoline to kerosene in the resulting azeotrope is generally determinative of the amount of kerosene required to permit the substantially complete recovery of quinoline. This amount can readily be determined by one skilled in the art. In this connection, a convenient expression for the amount of kerosene to be employed, and one which inherently takes into account any loss of kerosene, as for example, by azeotrope formation with other aromatic. nitrogen bases, is based upon the total weight of the. mixture. Thus, high yields and concentration of quinoline have been obtained when kerosene is admixed with an alkyl-substituted anilines.

aromatic nitrogen base mixture produced by the liquidphase hydrogenation of coal in a proportion of from about 1 to about 2 parts by weight of kerosene to each part by weights of the aromatic nitrogen base mixture. The amount of kerosene required is not narrowly critical, however, hence higher and lower proportions of kerosene can be utilized in the invention with satisfaction.

The azeotropic distillation can be carried out at any pressure up to about 4 atmospheres, pressures above this level frequently engendering the breakdown of the azeotrope into its component parts. As mentioned above, the azeot'ropic distillation is preferably conducted under reduced pressure in order to facilitate the separation of the quinoline-kerosene azeot-rope from other azeotrope-forming aromatic nitrogen bases, particularly Accordingly, reduced pressures of from about 10 to about 20 millimeters of mercury are most desirably employed.

The temperature at which the quinoline-kerosene azeotrope distills over is dependent in direct relationship to both the boiling range of the kerosene fraction and the pressure at which distillation is conducted, and can readily be determined by one skilled in the art. By way of illustration, the quinoline-kerosene azeotrope boils at a temperature of about 110 C. when a kerosene fraction boiling in the temperature range of from about 225 C. to about 230 C., and a pressure of about 20 millimeters of mercury are employed.

In a typical azeotropic distillation, heat is increasingly applied to the mixture of kerosene and aromatic nitrogen bases in the distillation zone at the desired pressure until a temperature is reached at which the quinoline-kerosene azeotrope distills over. The distillation is continued at this temperature level until further quantities of the quinoline-kerosene azeotrope can no longer be recovered or until the temperature of the reflux rises substantially above the boiling point of the azeotrope. The quinoline component can then be separated and recovered from the azeotropic distillate in any suitable manner.

By way of illustration, a convenient and economical procedure involves cooling the azeotropic condensate to a temperature below about 20 C. and preferably to a temperature between about 0 C. and 5 0, whereby a phase separation of the azeotrope is eifected. Thus, a quinoline-rich bottom layer and a kerosene-rich upper layer are obtained and can be mutually separated by decanation. The particular manner in which the separation of the azeotrope into its component parts is accomplished is not, however, critical to the invention.

For example, another suitable procedure lies in the extraction of the quinoline component by the addition of an aqueous mineral acid solution such as an aqueous solution of hydrochloric acid to the az'eotropic condensate. The quinoline-containing aqueous acidic layer thereby formed is readily separated from the kerosene component by decantation, and upon neutralization with caustic yields the desired product. In a similar manner, the qu-inoline component can be separated and recovered by extraction from the azeotropic condensate with water or an alcohol such as methanol.

If desired, the kerosene component of the azeotrope can be recycled to the distillation zone where it is admixed with further quantities of aromatic nitrogen base mixture. The recycling of kerosene in such a manner provides a continuous method for the recovery of quinoline from a mixture with other aromatic nitrogen bases wherein a considerable savings in the amount of azeotrope-forming agent is possible. However, the method of the invention can also be carried out efiiciently in batchwise operation.

The quinoline product obtained by cooling or otherwise treating the azeotropic condensate as described above can thereafter be employed in procedures involving the use of quinolines without further processing, or subjected to Conventional fractional distillation in order to provide a quinoline product of higher concentration or purity. It is generally found desirable to upgrade the product in this manner when the initial boiling point of the aromatic nitrogen base mixture from which the condensate was obtained was below about 234 C. and especially below about 230 C. Under these circumstances, varying amounts of other aromatic nitrogen bases such as lowboiling alkyl-substituted anilines may also be distilled over as azeotropes with kerosene and appear as contaminants in the quinoline product. However, their separation from quinoline as forecuts during the fractional distillation of the quinoline product can readily be accomplished even at atmospheric pressure due to their significant difference in boiling points from that of quinoline.

The improved process of the invention can also be illustrated by description in connection with the following specific examples of its practice.

EXAMPLE 1 A crude product obtained by the conventional liquidphase hydrogenation of coal was distilled so as to obtain as a fractional condensate a mixture of aromatic nitrogen bases having a boiling point range of between about 235 C. and about 241 C. The condensate contained an initial quinoline concentration of about 27 percent by weight. Five hundred grams of the aromatic nitrogen base mixture thus obtained was then introduced to a 2-liter still pot equipped with 2-foot packed column, and 500 grams of a kerosene fraction having a boiling point range of between about 223 C. and 230 C. added thereto with stirring. Heat was applied to the still and the resulting mixture of aromatic nitrogen bases and kerosene subjected to azeotropic distillation under a reduced pressure of about 20 millimeters of mercury. At a temperature of about 110 C. the formation of a distillate was observed. Heating was continued until the temperature of the reflux reached 115 C. The distillate was condensed and found by chemical analysis to be an azeotropic mix ture composed of about 32 percent by weight of aromatic nitrogen bases and about 68 percent by weight of kerosene. The azeotropic condensate was then cooled to a temperature of about 5 C. Upon cooling, the azeotropic mixture separated into two layers, the upper layer of which was removed by decantation. Chemical and spectroscopic analysis indicated the presence of quinoline in the 132 gram bottom layer in a concentration of about 91.0 percent by weight representing a quinoline yield of about 97 percent, while the upper layer was found to be composed essentially of kerosene. The quinoline-rich bottom layer was then introduced to a small still and subjected to fractional distillation at atmospheric pressure. At a temperature of about 237 C. a 117 gram fraction was recovered and found by chemical and spectroscopic analysis to contain quinoline in a concen-- tration of about 99.0 percent by weight, representing an overall quinoline yield of about 86 percent.

The experiment was repeated employing a kerosene fraction having a boiling point range of between about 220 C. and 225 C. as the azeotroping agent. The azeotropic distillate was condensed and found by chemical analysis to be a mixture composed of about 26 percent by weight of aromatic nitrogen bases and about 74 percent by weight of kerosene. The ultimate yield and concentration of the quinoline product was the same as that described above.

EXAMPLE 2 In a manner essentially the same as that described in Example 1, 250 grams of an aromatic nitrogen base mixture obtained by the liquid-phase hydrogenation of coal, having a boiling point range of between about 236 C. and about 238 C., and containing an initial quinoline concentration of about 88 percent by weight, was admixed with 500 grams of a kerosene fraction having a boiling point range of between about 225 C.

and about 230 C. and subjected to azeotropic distillation. -The azeotropic mixture distilling over at a temperature of about 110 C. under a reduced pressure of EXAMPLE 3 In a manner similar to that described in Example 1, 350 grams of an aromatic nitrogen base mixture obtained by the liquid-phase hydrogenation of coal, having a boiling point in the range of between about 235 C. and about 240 C. and containing an initial quinoline concentration of about 68 percent by weight, was admixed with 700 grams of a kerosene fraction having a boiling point range of between about 223 C. and 228 C., and subjected to azeotropic distillation. During distillation at a temperature of about 110 C. and under a reduced pressure of about 20 millimeters of mercury, several azeotropic fractions were taken and condensed. Each fraction was then treated with from about to 200 grams of a 6 normal aqueoushydrochloric acid solution, whereupon an aqueous acidic bottom layer and. a kerosene upper layer were formed. The kerosene layer was removed by decantation and the bottom layer neutralized by the addition of from about 100 to 200 grams of a 6 normal aqueous sodium hydroxide solution. Upon neutralization, an aromatic nitrogen base layer was separated and recovered by decantation. The aromatic nitrogen base product obtained from each fraction was then analyzed for the presence of aromatic primary, secondary and tertiary amines by selective titration, and specifically for the presence of quinoline by infra-red analysis. The results obtained are set forth below in Table A. In the table, the percent by weight of the aromatic nitrogen base mixture which had been distilled over as an azeotrope with kerosene upon the taking of each fraction is indicated in the column headed Amount Distilled; the concentration of aromatic amines in the product is indicated as moles of amine per 100 grams of product; the concentration of quinoline in the product is indicated as percent by weight of the product.

Table A Concentration of Aromatic Amines Concen- Fraction No. Amount tration Distilled of Quinc- Primary Secon- Tertiary line dary From the above table it can be seen that in accordance with the process of the invention, quinoline can be recovered from a mixture with other aromatic nitrogen.

prised essentially of a quinoline-kerosene azeotrope and separating the quinoline component from said distillate. 2. A process for the recovery of quinolinefrom a mixture with other aromatic nitrogen bases, said mixture having an initial boiling point of between about 230 C. and about 238 C., which comprises subjecting said mixture to azeotropic distillation in the presence of a kerosene fraction having an initial boiling point of at least about 190 C. so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate and separating the quinoline component from the condensate.

3. A process for the recovery of quinoline from a mixture with other aromatic nitrogen bases, said mixture having an initial boiling point of between about 230 C. and about 238 C. which comprises subjecting said mixture to azeotropic distillation under reduced pressure in the presence of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby efiecting a phase separation of the condensate into a quinolinerich layer and a kerosene-rich layer and separating the quinoline-rich layer from the condensate and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

4. A process for the recovery of quinoline from a mixture with other aromatic nitrogen bases, said mixture having an initial boiling point of between about 230 C. and about 238 C. which comprises subjecting said mixture to azeotropic distillation under reduced pressure in the presence of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby effecting a phase separation of the condensate into a quinolinerich layer and a kerosene-rich layer separating the quinoline-rich layer from the condensate.

5. A process for the recovery of quinoline from a mixture with other aromatic nitrogen bases, said mixture having an initial boiling point of between about 230 C. and about 238 C., which comprises subjecting said mixture to azeotropic distillation under reduced pressure in the presence of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature of between about C. and about C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer, separating the quinoline-rich layer from the condensate, recycling the kerosene-rich layer to the azeotropic distillation and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

6. A process for the recovery of quinoline from a mixture with other aromatic nitrogen base compounds, said mixture having an initial boiling point of between about 234 C., and about 238 C. which comprises subjecting said mixture to azeotropic distillation in the presence of a kerosene fraction having an initial boiling point of at least about 190 C. so as to obtain a distillate comprised essentially of a quinoline-kcrosene azeo'trope, condensing the distillate and separating the quinoline component from the condensate.

7. A process for the recovery of qu'inoline from a mixture with other aromatic nitrogen base compounds, said mixture having an initial boiling point of between about 234 C., and about 238 C. which comprises subjecting said mixture to azeotropic distillation under reduced pressure in the presence of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base 8 mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby eifecting a phase separation ofthe condensate into a quinolinerich layer and a kerosene-rich layer and separating the quinoline-rich layer from the condensate and subjecting the quinolinerrich layer to fur: ther distillation so as to obtain a distillate consisting of substantially pure quinoline.

8. A process for the recovery of quinoline from a mixture with other aromatic nitrogen base compounds, said mixture having an initial boiling point of between about 234 C., and about 238 C. which comprises subjecting said mixture to azeotropic, distillation under reduced pressure in the presence of a kerosene fraction having a boiling point range of between about C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentialiy of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene- :rich layer separating the quinoline-rich layer from the condensate.

9. A process for the recovery of quinoline from a mixture with other aromatic nitrogen base compounds, said mixture having an initial boiling point of between about 234 C., and about 238 C. which comprises subjecting said mixture to azeotropic distillation under re duced pressure in the presence of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinolinekerosene azeotrope, condensing the distillate, cooling the condensate to a temperature of between about 0 C. and about 5 C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer, separating the quinoline-rich layer from the condensate, recycling the kerosene-rich layer to the azeotropic distillation and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

10. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product to azeotropic distillation in the presence of kerosene so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope and separating the quinoline component from said distillate.

11. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 230 C. and about 238 C., to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having an initial boiling point of at least about 190 C. so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate and separating the quinoline component from the con densate.

12. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the nitrogen base fraction of the crude hydrogenation prodnot having an initial boiling point of between about 230 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosenerich layer and separating the quinoline-rich layer from the condensate and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

13. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an arcmatic nitrogen base-containing crude hydrogenation prod not is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 230 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 0., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer separating the quinoline-rich layer from the condensate.

14. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an arcmatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 230 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of be tween about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature of between about C. and about 5 C., thereby efiecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer, separating the quinoline-rich layer from the condensate, recycling the kerosene-rich layer to the azeotropic distillation and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

15. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 234 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fi'action having an initial boiling point of at least about 190 C. so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate and separating the quinoline component from the condensate.

16. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation prodnot is obtained, from which quinoline is subsequently rccovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 234 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of between about C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer and separating the quinoline-rich layer from the condensate and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

17. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation product is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 234 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature below about 20 0., thereby efiiecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer separating the quinoline-rich layer from the condensate.

18. In a process for the production of quinoline by the liquid-phase hydrogenation of coal wherein an aromatic nitrogen base-containing crude hydrogenation prodnot is obtained, from which quinoline is subsequently recovered, that improvement which comprises subjecting the aromatic nitrogen base fraction of the crude hydrogenation product having an initial boiling point of between about 234 C. and about 238 C. to azeotropic distillation in the presence of from about 1 to about 2 parts by weight of the aromatic nitrogen base fraction of a kerosene fraction having a boiling point range of between about 190 C. and the initial boiling point of the aromatic nitrogen base mixture so as to obtain a distillate comprised essentially of a quinoline-kerosene azeotrope, condensing the distillate, cooling the condensate to a temperature of between about 0 C. and about 5 C., thereby effecting a phase separation of the condensate into a quinoline-rich layer and a kerosene-rich layer, separating the quinoline-rich layer from the condensate, recycling the kerosene-rich layer to the azeotropic distillation and subjecting the quinoline-rich layer to further distillation so as to obtain a distillate consisting of substantially pure quinoline.

References Cited in the file of this patent UNITED STATES PATENTS 2,035,583 Bailey Mar. 31, 1936 2,085,287 Bailey June 29, 1937 2,231,241 Bailey Feb. 11, 1941 2,237,542 Bailey Apr. 8, 1941 2,363,159 Engel Nov. 21, 1944 OTHER REFERENCES Distillation (Weissberger), published by Interscience Publishers Inc. (N.Y.), 1951, pages 356-368 relied upon.

Claims

1. A PROCESS FOR THE RECOVERY OF QUINOLINE FROM A MIXTURE WITH OTHER AROMATIC NITROGEN BASES WHICH COMPRISES SUBJECTING SAID MIXTURE TO AZEOTROPIC IN THE PRESENCE OF KEROSENE SO AS TO OBTAIN A DISTILLATE COMPRISED ESSENTIALLY OF A QUINOLINE-KEROSENE AZEOTROPE AND SEPARTING THE QUINOLINE COMPONENT FROM SAID DISTILLATE.