US2345005A - Nitrogen bases - Google Patents

Description

March 28, 1944. L. REA -r A 2,345,005

NITROGEN BASES Filed 001',- 4, 1939 l 4cm "v1.5

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Patented Mar. 28, 1944 UNITED STATES PATENT OFFICE NITROGEN BASES Chester L. Read, Westfield, and Amiot P. Hewlett;

Summit, N. J., assignors to Standard Oil Developrnent Company, a corporation of Delaware Application October 4, 1939, Serial No. 297,884

4 Claims. (Cl. 260-269) The present invention relates to the production of nitrogen bases. The invention is particularly concerned with recovery of nitrogen bases from mineral oils, particularly from petroleum oils boiling in the motor fuel, kerosene, heating oil, and Diesel oil boiling range. In accordance with the present invention these materials are recovered from spent mineral acids used in the treatment of mineral oils by a process comprising a particular sequence of stages.

It is well known in the art that mineral oils, particularly petroleum oils contain various complex nitrogen bases. Although these bases are valuable intermediate products for the produc tion of dyes, insecticides, and the like, it has not been possible heretofore to economicall recover the same from petroleum oils since their concentration is relatively small and their recovery expensive. We have now discovered a process by which it is possible to recover nitrogen bases from petroleum oils in an eflicient and economical manner. Our process comprises treating a nitrogen base containing mineral oil with a mineral acid under conditions in which the nitrogen bases are removed as nitrogen base salts with the acid. The acid liquid is hydrolyzed to remove tarry and other undesirable materials. The hydrolyzed mixture is solvent treated with a selective solvent having preferential selectivity for the nitrogen base salts under conditions to form a solvent extract phase. This phase is handled in a manner to remove the solvent from the extract. The extract comprising oil and nitrogen base salts is treated in a manner to separate the oil from the nitrogen base salts which are then treated to segregate the respective complex compounds or further refined in any desirable manner.

The process of our invention may be readily understood by the attached drawing illustrating one modification of the same. A nitrogen base containing feed oil is introduced into acid treating plant I by means of feed line 2, in which it is contacted with acid which is introduced by means of acid feed line 3. For purpose of illustration, it is assumed that the reed oil is a cracked petroleum oil boiling in the motor fuel boiling range and the acid is sulfuric acid. Temperature and pressure conditions are maintained in treating plant I to secure the complete removal of the nitrogen bases. Treating plant I may comprise any desired number of treating units arranged in any suitable manner.

The acid treated oil free of nitrogen bases and substantially free of acidic materials'is removed from treating plant I by means of line 4. This oil may be treated in any desirable manner in order to remove any remaining traces of acidic materials. The acid liquor containing the nitrogen bases as nitrogen base salts is withdrawn from treating plant I by means of line 5, and introduced into hydrolyzing plant 6. Water or an equivalent 'hydrolyzing agent is introduced into hydrolyzing plant 6 by means of line 1. Tem-' perature and pressure conditions are maintained in the hydrolyzing plant adapted to secure the precipitation of tarry and similar materials which are withdrawn by means of line 8. The mixture comprising spent acid, nitrogen base salts and added water is withdrawn from hydrolyzin plant 6 by means of line 9 and introduced into solvent treating plant II) which for the purposes of de-' scription is assumed to be a countercurrent treat-1 ing tower. In solvent treating plant In the spent. acid liquor is countercurrently extracted with aselective solvent having a preferential selectivity for the nitrogen base salts. Temperature'and' pressure conditions are maintained inorder to secure the formation of a solvent extractphase which is removed by means of line 'I 2 and a spent acid phase which is removed bymeans' of line l3. Solvent treating plant It] is provided with suit-' able distributing and contacting means; Solvent treating plant I!) may also'be provided with' means adapted to modify the selectivity or solvent power of the particular selective solvent used. The acid liquor phasewithdrawn by means of line [3 may be handled in any manner desirable and is usually passed to a regeneration plant" and then recycled through the system. The sol vent extract phase removed by means of line" i2; is introduced into a solvent recovery unit 54 which, for the purposes of description, is taken to be a distillation unit. Temperature and pres-' sure conditions are maintained indistillation unitadapted to remove overhead the selective solvent which is removed by means of line I5. The solvent free extract is removed from distillation unit M by means of line l6 and mixed with water or an equivalent substance which is introduced comprise an oil phase and a water phasecontaining soluble salts of the nitrogen bases. The

oil phase is withdrawn from separator l8 by' means of line [9 while the aqueous solution of salts of the nitrogen bases is withdrawn by meansof line 20 and passed into neutralizing plant 2| in which it is contacted with a suitable neutraliz-- ing agent which is introduced by means of line 22. The neutralized mixture is then passed into settler 24 by means of line 23 in which a further phase separation occurs. The nitrogen bases insoluble in the spent alkaline phase are withdrawn by means of line 26 while the spent alkaline phase is withdrawn by means of line 25. If desired, the nitrogen bases may be segregated or further refined in any desirable manner.

The process of the present invention may be widely varied. The process may be applied for the recovery of any nitrogen basespresent in spent acids used in alkylation or similar processes or from acids used in the manufacture of alcohols, ethers and esters from olefin-containing petroleum oils. The invention, however, is particularly adapted for the processing of spent acids secured in the refining of motor fuels and other light distillates in which petroleum oils are contacted with sulfuric or an equivalent acid under conditions adapted .for the removal of gum forming constituents and color forming bodies and for the reductionof sulfur. The spent acid secured in these operations may be readily regenerated and nitrogen bases recovered as by-products. The tarry materials are removed from the acid in the .hydrolyzing plant while the other undesirable substances are removed in the solvent treating plant. The aqueous solution of spent acid removed from the solvent treating plant is relatively clean and is particularly adapted for efllcient and economical regeneration.

Although the nitrogen base containing feed oil may be contacted with any suitable mineral acid in order to remove the nitrogen bases therefrom, it has been found that sulfuric acid is particularly desirable. The sulfuric acid used should preferably have a concentration of from 90 to 100%. In general, it is preferred to contact the petroleum oil boiling in .the motor fuel and gas oil boiling ranges with from 2 to 15 pounds of acid per barrel of feed oil, although in certain instances the oil may be contacted with as high as 40 to 50 pounds of acid per barrel of feed oil. The pressure should be sufiicient to maintain the constituents in the liquid phase. The treating operation is carried out under conditions so that the temperature does not exceed about 110 F. It is desirable to keep the temperature in the range below 75 F., preferably in the range below about 40 F.

The acid liquor separated from the acid contacting step is then hydrolyzed with a sufficient quantity of a hydrolyzing agent. Although water is preferred, other hydrolyzing agents, as for example, alcohols and the like, may be used. We have found that from one-half to one volume of hydrolyzing agent per one volume of acid liquor is sufiicient .to substantially completely remove the tarry and similar materials from the acid phase.

The acid phase free of tarry and similar materials may be contacted with any solvent having a preferential selectivity for the nitrogen base salts as compared to the spent aqueous acid phase. Solvents of this character are phenols, cresols, nitro-benzene. and the like. We have found that phenols are particularly desirable solvents. When using a phenol as the selective solvent it is desirable that the sulfuric acid be diluted to about 30 to 40 Baum concentration as the phenolic type solvents are less soluble in acids of this concentration. Particularly desirable phenolic type solvents are monohydroxy phenol and cres'ylic acid. Temperature and acid liquor.

pressure conditions of the solvent treating stages are adapted to secure efficient removal of the nitrogen base salts from the spent clean acid. In general, atmospheric pressure and a temperature above the melting point of the solvent, preferably in the range of 70 F. to F., are employed. The quantity of selective solvent used per volume of acid liquor being extracted may vary widely, depending upon the character of the acid being extracted, the character and concentration of the nitrogen base salts and upon the particular selective solvent employed. In general, when using phenol it is preferred to use from 0.1 to 1 volume of phenol per volume of The solvent extract after removal from the clean spent acid phase is handled in any manner to remove the selective solvent from the extract. This is preferably accomplished by distilling the solvent extract and removing the solvent overhead.

The solvent free extract removed from the solvent recovery unit comprising oil, various complex reaction products and nitrogen base salts is mixed with a suitable substance which will'dissolve the nitrogen base salts. The mixture is then passed into a separator in which a phase separation occurs between the oily constituents and the nitrogen base salt layer. Although substances such as alcohols may be used for the separation of the nitrogen base salts from the oily constituents, we prefer to use water. We have found that the temperature maintained in the oil-salt separator should preferably be in the range from about F. to 200 F. In order to facilitate phase separation, the oil-nitrogen base salts mixture may be diluted with naphtha, chloroform, benzene, etc. The salt solution free of oily constituents is then neutralized with any suitable neutralizing agent in order to convert the salts to the corresponding nitrogen bases. The preferred neutralization agent is an aqueous solution of sodium hydroxide. The nitrogen bases are immiscible in the aqueous solution of spent sodium hydroxide and in general are readily separated from it. Under certain conditions difficulty may be experienced in effecting this separation, in-which case solvents such as naphtha, chloroform, benzene, etc. may be added to the mixture to facilitate separation of the sodium hydroxide from the nitrogen bases. The aqueous solution may be passed to an evaporator where water is removed, leaving behind the sodium soaps of the sulfonic acids and other complex reaction products. The nitrogen bases are withdrawn by means of line 26, and may be subjected to purification which may involve simple removal of any added solvent by distillation, or may involve extraction of this layer with an acid solution followed by neutralization to purify the nitrogen bases. As an alternate procedure, the crude nitrogen base layer separated from neutralizing unit 2| may be extracted with an alcoholic solution of hydrogen chloride to dissolve the nitrogen bases. The nitrogen bases may then be purified and separated from this solution by means known to the art. The amine hydrochlorides may be crystallized from the alcohol or may be recovered by evaporation of the alcohol.

In order to further illustrate the invention, the following example is given which should not be construed as limiting the same in any manner whatsoever.

Example 1 A cracked heating oil distillate was treated with 3 pounds of 98% sulfuric acid per barrel. The

acid sludge was hydrolyzed by mixing with 0.7 volume of water to obtain a separated acid of 32 Baum concentration. After separation of the precipitated tarry material, the weak acid phase was extracted with 0.25 volume of monohydroxy phenol. The phenolic extract was separated from the resulting clean acid which was passed through a restoring plant. The phenolic extract was subjected to distillation to separate the solvent from the extract oil. The extract was mixed with 4 volumes of water and the mixture allowed to stratify. The oily top phase was withdrawn and an excess of NaOH added to the aqueous phase. This mixture was allowed to stratify and the nitrogen bases (constituting the bottom oily phase) were withdrawn. The aqueous phase was then evaporated to recover sodium sulfonates. Approximately .02% nitrogen bases were recovered based upon the original petroleum fraction. The nitrogen bases obtained consisted of aryl and alkyl amines and complex derivatives of pyridine, pyrrole and pyrazole.

The nitrogen bases secured in accordance with the present invention are very desirable as intermediates for the production of dyes, insecticides, and the like. They are also desirable as wetting agents to improve the adhesivity of asphalts to mineral aggregate and thus are valuable aids in road construction.

The process of the present invention is not to be limited by any theory or mode of operation but only by the following claims in which it is desired to claim all novelty in so far as the prior art permits.

We claim:

1. Process for the production of nitrogen bases from a mineral oil of the motor fuel to ga oil boiling range containing the same, which comprises treating said mineral oil with a mineral.

acid, separating the resulting acid liquor containing dissolved nitrogen base salts, hydrolyzing said acid liquor to precipitate therefrom tarry and similar substances, solvent treating the acid liquor free from tarry materials with a solvent selected from the class consisting of phenols, cresols, and nitrobenzene, under conditions to form a solvent extract phase and a spent acid phase, separating the solvent extract phase and removing the solvent therefrom, mixing the residual extract with a solvent for the nitrogen base salts selected from the class consisting of alcohols and water under conditions to form an oil phase and a solvent phase containing said nitrogen salts, separating said solution of nitrogen salts and neutralizing the same with an excess of an alkaline agent to liberate the nitrogen bases as an oily phase, and separating the latter from the spent alkaline phase containing salts.

2. Process for recovering nitrogen bases from a mineral oil of the heating oil boiling range containing the same, which comprises treating said mineral oil with sulfuric acid, separating the resulting acid liquor containing dissolved nitrogen base salts, hydrolyzing said acid liquor with water to precipitate therefrom tarry and similar substances, separating said tarry precipitate, treating the acid liquor free from tarry material with phenol under conditions to form a phenol extract phase and a clean acid phase, separating said phenol extract phase and removing the phenol therefrom, mixing the phenol-free extract with water under conditions to form an oil phase and an aqueous solution of nitrogen base salts and removing said oil phase therefrom, treating the residual aqueous solution of nitrogen base salts with an excess of caustic soda to liberate the nitrogen bases as an oily phase, and separating the latter from the aqueous phase containing sodium sulfonates and excess caustic soda.

3. Process for recovering nitrogen bases from a petroleum oil of the heating oil boiling range containing the same, which comprises contact ing said oil with about 2-50 lbs. of 98-100% sulfuric acid per barrel of oil at a temperature below about 110 F., separating the resulting acid liquor containing dissolved nitrogen base salts, hydrolyzing and diluting said acid liquor with about /2-1 volume of water to precipitate tarry and similar substances, separating the diluted acid liquor from said tarry material, treating the resultant tar-free acid liquor with about 0.1-1.0 volume of phenol at about -120 F. to extract oil constituents, sulfonic compounds and nitrogen base salts in the phenol extract phase, separating the latter from the residual clean acid, separating the phenol from said phenol extract phase by distillation, mixing the resulting phenol-free extract with a sufi'lcient amount of water to cause stratification into two layers, removing the upper oil layer, and neutralizing the residual aqueous solution of nitrogen base salts with an excess of caustic soda to liberate the nitrogen bases as an oily phase, and separating the latter from the aqueous phase containing sodium sulfonates and excess caustic soda.

4. Process according to claim 3 in which 3 lbs. of 98% sulfuric acid are used per barrel of oil treated, about 0.7 volume of water is used for hydrolyzing and diluting the acid liquor to precipitate tarry material, and about 0.25 volume ofiphenol is used to extract the tar-free dilute ac d.

CHESTER L. READ. AMIOT P. HEWLETT.

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