US2789144A - Separation of tar acids and tar bases - Google Patents

Description

United States Patent SEPAR" ATION'OF' TAR ACIDS TAR. EASES Everett Gorin,- Pittsburgh, Benjamin W. Jones? Bridgeville and- Martin I Nan-worth; Pittsburgh, Pal, assignors" to Pittsburgh Qonsolidsificmfioal: Company; Pittsburgh, Pa.,-. a corporation of Pennsylvania No Drawing. A'pplicatious eptember'2 8; 1'953, Serial No. 382;866*

7 Claims. (CL260-627);

'lhisinvention relates to the ion=exehange treatment of mixtures oftar acid'si; e. phenols,.an'd tar bases i. e. organicnitrogen containing. bases, to street separation and-permitrecovery'of the tar acid'sin substantially'tar base free condition;

This application'is a continuationdn-part of our" co pending application; Serial Number 215376, filedMatch 13; 1951, now abandoned, and assigned to? the a's'signee of-the present invention;

Tar acidsand tarbases -are' foundtogetherinthe liquid products of distillation of" oil shale and low temperature carbonization" of coal and also in" the s'o-called petroleum cres'ylics produced by' the cracking of petroleum. The tar acids are' particularly. valuable commercially in. the production of'resins, plastici'zers'and the like: In such uses their utility'is" seriously impaired if they arecon taminatedby tar bases? Unfortunately, thebo'ilingpoints of thetar acidsand'thetar bases derivedfromth'e abovementioned' source's are such as'not to'permit their'efie'c'tive separation by distillation: Treatment of the mixtures with strong'acid s is'only partially successful in removing the tar-bases and isparticularly-ineffective for removing thosebases which boil' above 230" C In accordancewiththis-invention, we have'found that treatment of a mixture of taracids and tar baseswith a cation exchangeresinisextremely efiective'in'rernovin'g not only the low 'boiling' tar bases butalso' the high boiling tar bases, therebyleaving the tar acids in a'substantially ta'rbase free condition.

Furthermore, we' have discovered'- that the capacity of the r'esinto adsorb. the'tar' bases is commercially satis-' factory and also that the" resin can be-r'eadily-a'nd completely regenerated by acid dissolved in apolar solvent in which the" tarba'ses aresolhble.

In the aforementioned application, the treatment of the; mixture-of tar acids and tarbases w'ith' a cation ex"- c-hange resinw'asdescrib'eda's b'eing carried outin a polar solvent; We have sincefo'und that-the use of a polar solvent is'desirable'in'some cases but not necessary; No solvent at all ora': non-polarsolvent may-'beemployed. However, the preferred embodiment of theproeessstill includes the use of a polar solvent. One reason for this is the fact that the tar acids and bases are recovered in a solution of a polar solvent e. g.- methanol in the separation oftar acids from neutraLoiLby thecountercurrent eittractive treatment of'tar acid oil with. aqueous methanol'andhex'aneas described'in the copending application of Gorin and Neuworth, Serial Number 184,474, now US. Patent 2,666,796,-file'd- March 13, 1951, and assigned to the assignee of the presentinvention. There is, therefore, no need to' remove the polar solvent before proceeding with: the ion exchange treatment. Furthermore, it is som'etimes desirable to have 1 a solvent toreduce the viscosity of the feedstock, particularlywhen'hig'h boiling tar acids are present.

Specifically, the preferred method of treatment is as follows. The mixture of tar acids and tar bases is first dissolved in a polar solvent. Examples of such solvents 2. are methanol, ethanol, propane], acetone, and methyl ethyl ketone. Preferably the solvent is in an aqueous condition, the amount of water being insufficient to render the tar acids and the tar bases insoluble in the polar solventr Theprecise amount ofwaterthat may be tolerated varies,- of course, with the composition of the tar acids, as well as their concentration, but may: easily be determined by simple solubility tests on the mixture. We have found aqueous methanol to be particularly effective. Since the latter solvent is' also useful in separating tar acids and tar-bases from the neutral' oil with which" they generally occur in: the distillate fractions derived from distillation of coal, oil shale and the like',-theresulting extract may be used directly: in the present invention.

The solution of tar acids and bases is passed" through abed-of. granular cation exchange resin; Useful ag'e'nts of this type are thecationic exchange: resins containing. acidic groups, for example, the sulfonated phenolic typev cation exchanger, the sulfonated coal type cation ex changen'the sulfonated styrene-type cation'exchanger, as wellas: the correspondingcarboxylic cation exchangers. We: prefer to use those 1 cation' exchange resins which derive their capacity. to adsorb-essentially from sulfonic acid groups. As a result ofcontacting. the solution of tar acids and bases with the resin, the bases are adsorbed upon the resin andasolutionoi tar acids substantially free oftar bases is discharged from the bed of resin. The solvent may thenbe-removed by distillationandthe tar acids. recovered.

After the cation exchangeresinhas adsorbed asnfiicient quantity of the tar bases, so thatit-approachesthe point at which it will not'adsorb any. more, or the point at which an appreciable amount of tar bases appears in the efiluent, the resin is eluted, preferably by a strong acid such as hydrochloric or sulfuric in a' polar solvent in which the tar bases are likewise soluble. While the solvent may advantageously contain some water, the amount of water must not be suflicienttoprevent the bases from being completely dissolved; or the capacity of the resin to adsorb in subsequent cycles of treatment will be seriously impaired. The polar solvent may be the same polar solvent selected for the base adsorption treatmentand isa'gain preferably aqueous methanol. As a result of the=elution ofthe resin, an extract containing thetar'bases in the fiorm of their mineral acid salts together with free acid is' obtained' The tar bases may readily be'recove'red from this extract by decomposing the salts with strong'alkali followed by distillation; In contrast to the optional use of a polar solvent in the treatment of the feedstock with the resin, the use of a polar solvent in the regeneration of the resin. is critically essential; Attempts-to remove the adsorbed bases with outthe polarsolvent were unsuccessful.

The relative concentrations of tar acids: and ta'r'bases in the original solution do not appean to be critical in thesuccessful practice of our invention. In general; however, the-tarbases-are present in=a very. small a'mount as: compared with-thetar acids, i. e. upto ab'o'ut 2l'0%' of thertotal t'ar acids.

In-the followingztable are 'tabulatedthe data obtained by-treatinga niix-ture of tar acids and tar bases derived frcm the di's'tillationofbituminous' coalat about 850 F? with sutfonated cation exchangers; Runs 1' and" 2 em: played a altwater phenolic type resin sold under the trademark Amberlite IR- by Resinous Productsan'd ChemicalCompany; Rim fem'plbYed a sulfonatedcoal resin sold under the trademark ZemKarb by the Permutit Company. In all three runs, the mixture of tar acids and tar bases were dissolved in 70% aqueous methanol (i. e. 70 parts by volume of CI-IsOH and 30 parts by volume of water). Likewise, in all three runs the resin was regenerated by a solution of 4% H01 in 70% aqueous methanol.

Resin capacity calculations have'been made on eflluents at break through point.

The following example illustrates the application of our process to amixture of tar acids and bases without the use of a solvent. A mixture consisting of 99.78% by weight of tar acids and 0.22% by weight of tar bases was passed over a sulfonated phenolic type resin sold under the trademark Amberlite IR-l20 by Resinous Products and Chemical Company. The effiuent tar acids contained 0.07% by weight of tar bases. The regeneration of the resin is accomplished in the same manner as described above.

According to the provisions of the patent statutes, we have explained the principle, preferred construction, and mode of operation of our invention and have illustrated and described what we now consider to represent its best embodiment. However, we desire to have it understood that, within the scope of the appended claims, the invention may be practiced otherwise than as specifically illustrated and described.

We claim:

1. The method of removing contaminating quantities of tar bases from a mixture consisting essentially of tar acids and tar bases derived from low temperature carbonization tar which comprises continuously passing said mixture in intimate contact with a cation exchange resin whereby said tar bases are adsorbed on said resin and said tar acids are passed thercthrough, continuously collecting the effiuent liquid which has passed through said cation exchange resin, said eflluent liquid containing tar acids substantially free of tar bases, until said resin becomes substantially saturated with tar bases, thereafter regenerating said resin by passing therethrough a solution of strong acid in an aqueous polar solvent selected from the class consisting of methanol, ethanol, propanol, acetone and methyl ethyl ketone to desorb said tar bases from said cation exchange resin, recovering said solution of strong acid in an aqueous polar solvent containing desorbed tar bases, and repeating the entire process in cyclic fashion.

2. The method of removing contaminating quantities of tar bases from a mixture consisting essentially of tar acids and tar bases derived from low temperature carbonization tar which comprises preparing a solution of said mixture in a polar solvent selected from the class consisting of methanol, ethanol, propanol, acetone and methyl ethyl ketone, continuously passing said solution in intimate contact with a cation exchange resin whereby said tar bases are adsorbed on said resin and whereby said tar acids and polar solvent are passed therethrough, and continuously collecting the efiluent liquid which has passed through said cation exchange resin, said efiiuent liquid containing tar acids substantially free of tar bases dissolved in said polar solvent, until said resin becomes substantially saturated with tar bases, thereafter regenerating said resin by passing therethrough a solution of strong acid in an aqueous polar solvent selected from the class consisting of methanol, ethanol, propanol, acetone and methyl ethyl ketone to desorb said tar bases I from said cation exchange resin, recovering said solution of strong acid in an aqueous polar solvent containing desorbed tar bases, and repeating the entire process in cyclic fashion.

3. The method according to claim 2 in which the tar bases comprise tar bases boiling above 200 C;

4. The method according to claim 2 in which the cation exchange resin is one which derives its exchange capacity essentially from acid groups.

5. The method according to claim 2 in which the cation exchange resin is one which derives its exchange capacity essentially from sulfonic groups.

6. The method of removing contaminating quantities of tar bases from a mixture consisting essentially'oftar acids and tar bases derived from low temperature carbonization tar which comprises preparing a solution of said mixture in a polar solvent selected from the class consisting of methanol, ethanol, propanol, acetone and methyl ethyl ketone, continuously passing said solution in intimate contact with a cation exchange resin whereby said tar bases are adsorbed on said resin and whereby said tar acids and said polar solvent are passed therethrough, continuously collecting the efiluent liquid which has passed through said cation exchange resin, said efliuent liquid containing tar acids substantially free of tar bases, dissolved in said polar solvent until said resin becomes substantially saturated with tar bases, thereafter regenerating said resin by passing therethrough a solution of strong acid in aqueous methanol to desorb said tar bases from said cation exchange resin, recovering said solution of strong acid in aqueous methanol containingdesorbed tar bases, and repeating the entire process in cyclic fashion. 7. The method of removing contaminating quantities of tar bases from a mixture consisting essentially of tar acids and tar bases derived from low temperature carbonization tar which comprises preparing a solution of; said mixture in a polar solvent selected from the class consisting of methanol, ethanol, propanol, acetone and methyl ethyl ketone, continuously passing said solution in intimate contact with a cation exchange resin whereby said tar bases are adsorbed on said resin and whereby said tar acids and said polar solvent are passed therethrough, continuously collecting the eflluent liquid which has passed through said cation exchange resin, said efiluent liquid containing tar acids substantially free of tar bases dissolved in said polar solvent, until said resinbecomes substantially saturated with tar bases, thereafter regenerating said resin by passing therethrough a solution of strong acid selected from the class consisting of sulfuric acid and hydrochloric acid, in aqueous methanol to desorb said tar bases from said cation exchange resin, recovering said solution of strong acid in aqueous methanol containing desorbed tar bases, and repeating the entire process in cyclic fashion.

References Cited in the file of this patent 260-B. E. Digest.

Claims (1)

1. 2. THE METHOD OF REMOVING CONTAMINATING QUANTITIES OF TAR BASES FROM A MIXTURE CONSISTING ESSENTIALLY OF TAR ACIDS AND TAR BASES DERIVED FROM LOW TEMPERATURE CARBONIZATION TAR WHICH COMPRISES PREPARING A SOLUTION OF SAID MIXTURE IN A POLAR SOLVENT SELECTED FROM THE CLASS CONSISTING OF METHANOL, ETHANOL, PROPANOL, ACETONE AND METHYL ETHYL KETONE, CONTINUOUSLY PASSING SAID SOLUTION IN INTIMATE CONTACT WITH A CATION EXCHANGE RESIN WHEREBY SAID TAR BASES ARE ADSORBED ON SAID RESIN AND WHEREBY SAID TAR ACIDS AND POLAR SOLVENT ARE PASSED THERETHROUGH, AND CONTINUOUSLY COLLECTING THE EFFLUENT LIQUID WHICH HAS PASSED THROUGH SAID CATION EXCHANGERESIN, SAID EFFLUENT LIQUID CONTAINING TAR ACIDS SUBSTANTIALLY FREE OF TAR BASES DISSOLVED IN SAID POLAR SOLVENT, UNTIL SAID RESIN BECOMES SUBSTANTIALLY SATURATED WITH TAR BASES, THEREAFTER REGENERATING SAID RESIN BY PASSING THERETHROUGH A SOLUTION OF STRONG ACID IN AN AQUEOUS POLAR SOLVENT SELECTED FROM THE CLASS CONSISTING OF METHANOL, ETHANOL, PROPANOL, ACETONE AND METHYL ETHYL KETON TO DESORB SAID TAR BASES FROM THE CATION EXCHANGE RESIN, RECOVERING SAID SOLUTION OF STRONG ACID IN AN AQUEOUS POLAR SOLVENT CONTAINING DESORBED TAR BASES, AND REPRATING THE ENTIRE PROCESS IN CYCLIC FASHION.