CA1120055A - Process for producing carboxylic acids and aromatic carboxylic acids - Google Patents

Process for producing carboxylic acids and aromatic carboxylic acids

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Publication number
CA1120055A
CA1120055A CA000322657A CA322657A CA1120055A CA 1120055 A CA1120055 A CA 1120055A CA 000322657 A CA000322657 A CA 000322657A CA 322657 A CA322657 A CA 322657A CA 1120055 A CA1120055 A CA 1120055A
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Prior art keywords
reagent
carboxylic acid
aromatic carboxylic
aromatic
isomerized
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CA000322657A
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French (fr)
Inventor
Raymond A. Schep
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Occidental Research Corp
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Occidental Research Corp
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    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/582—Recycling of unreacted starting or intermediate materials

Abstract

PROCESS FOR PRODUCING CARBOXYLIC ACIDS
AND AROMATIC CARBOXYLIC ACIDS

ABSTRACT

A process for producing carboxylic acid from carbonaceous material by treating a mixture of a carbonaceous material, water, and a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, the reagent producing an alkaline solution by hydrolysis, with oxygen, under conditions sufficient to convert the carbonaceous material to a carboxylic acid salt of said reagent; then removing water from the mixture;
then treating the mixture with an acid of the reagent to convert the carboxylic acid salt to a carboxylic acid precipitate and the reagent; and then separating the aromatic carboxylic acid from the reagent. In one embodiment ah aromatic carboxylic acid is produced from aromatic material.

In another embodiment an isomerized aromatic carboxylic acid is produced by treating a mixture of an aromatic material, water, and a water soluble reagent comprising a Group Ia or IIa metal with oxygen under conditions sufficient to convert at least a portion of the aromatic material to an aromatic carboxylic acid salt of the metal; isomerizing the aromatic carboxylic acid salt by heating without converting the aromatic carboxylic acid salt to an aromatic carboxylic acid salt of a different Group Ia or IIa metal prior to isomerizing; converting the isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and regenerating the reagent; recovering the isomerized aromatic carboxylic acid, and recycling the reagent thusly regenerated to supply a portion of the reagent required for producing the aromatic carboxylic acid salt. In one embodiment the water soluble reagent is potassium carbonate, or potassium bicarbonate or mixtures thereof.

Description

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~` ;j ,I FIELD OF INVENTION
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The field o~ the invention relates to the production ¦iof aromatic carboxylic acids from aromatic materials, such as I coal, petroleum residium, shale oil, and tar sands. The invention is particularly useful ~or the production of tereph-- thalic acid from bituminous coal.

;~ 10 1PRIOR ART
~. I
U.S. Patent 2,785,198 discloses a process for producing jpolycarboxylic acids from bituminous coal, lignites, peat and llthe like or their carbonization products such a~ coal, tar, or pitch by thermal treatment with oxidizing agents such as nitric ! ` I . .
~-~ 15 lacid, chromic acid, permanganate, or oxygen or air under super-atmospheric pressure in an alkaline medium.

¦ The crude oxidation product is subject to an extraction .,.
1~ ¦ treatment with a polar organic solvent for both the monocyclic ~ .~ ,. , ¦ aromatic and high molecular weight polycarboxylic acids, and ~ 20 treating the thusly formed solution with water to extract the ;~ ¦monocyclic aromatic polycarboxylic acids from the rèmainder of ; ¦Ithe mixture.

~ ~ I The alkaline medium disclosed by Grosskinsky et al is :,',. i~
~ ' sodium hydroxide.
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I U.S. Patent 2,193,337 discloses a process for producing organic acids by heating carbonaceous material such as sawdust, , wood chips, peat, or coal with oxygen-containing gases at elevated pressures and temperatures in the presence of at ; 5, least 10 times the weight of the carbonaceous material of water and preferably an oxide or hydroxide of an alkali or ¦ alkaline earth metal. Oxalic acid and other organic acids which are formed, such as mellitic and benzoic acid or acetic acid, may be isolated from the resulting reaction mixture as loil salts of the alkali or alkaline earth metals. The caustic - ¦i material disclosed is an oxide or hydroxide of an alkali metal `l i 'l or an alkaline earth metal and specifically lime, quick-lime, 'l and caustic soda.
.. ,~ 1 l U.S. Patent 2,786,074 discloses a process for making 15 1! organic acids by oxidizing carbonaceous materials at elevated ` Il temperatures and pressures with gaseous oxygen in the presence of an alkaline solution. Alkalis which are suitable for use in : li ¦ a high pressure reactor are specified as sodium hydroxide, ! potassium hydroxide, and mixtures thereof.
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20 1 U.S. Patent 2,461,740 discloses a process for oxidizing carbonaceous material to aromatic acids using a two-stage oxidation process.
. 1 1 ' In the first stage, the carbonaceous ma~erial is oxidized I to a state where it is soluble in aqueous alkali such, for 25 , example, as a solution of sodium hydroxide, potassium hydroxide, sodium carbonate, or potassium carbonate, especially at elevated , ll temperatures.

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ql5~i : , .i , ; Any acid or acid anhydride with suitable oxidizing pro-perties which can be regenerated by air and recycled in the process can be employed, for example sulfur trioxide~ oxides of ll nitrogen, or the acids formed by reaction of these compounds 5,l with water. Specifically disclosed are sulfur trioxide, ! N2O3~ and N2O5.

~, In the second stage, U.S. ~atent 2,461,740 discloses the use of a high pressure elevated temperature reaction of oxygen ¦I gas in aqueous alkali. The aqueous alkali employed is a 10¦ solution of sodium hydroxide, potassium hydroxide, sodium ¦l carbonate, or potassium carbonate.

i ¦1 U.S. Patent 3,023,217 discloses a process for introducing I! carboxyl groups into aromatic compounds free from carboxyl ; ll groups, such as aromatic carbocyclic hydrocarbons and aromatic l5l1heterocyclic hydrocarbons. The patent discloses a process for introducing into aromatic carbocyclic or aromatic heterocyclic jl compounds free from carboxyl groups by reacting such materials ¦ in the absence of substantial amounts of oxygen, such as a non-oxidative atmosphere and under anhydrous conditions, with ~; 20,lalkali metal salts of aliphatic carboxylic acids at elevated temperatures and pressures in the presence of catalysts.
. i! As disclosed in the process, it is necessary to exclude the presence of substantial quantities of oxygen. Examples of ! aliphatic carboxylic acids which are used in the form of their .: i1 25,,lalkali metal salts, especlally their potassium salts, are oxalic acid, malonic acid, maleic acid, and trichloroacetic acid.

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~l2~5,~-,;, , Examples o~ suitable compounds free from carboxyl grouDs ; which may be used as starting materials for the process are aromatic carbocyclic compounds free from carboxyl groups such Il as monoeyclie aromatie hydroearbons such as benzene or its s~l derivatives having saturated alkyl or cyeloalkyl substitutes attached thereto, and dicyelic aromatie hydroearbons such as naphthalenes, diphenyl, and other polyeyelie aromatie hydro-earbon eompounds. Similarly, aromatic heteroeyelie compounds ; free from earboxyl groups whieh may be used as starting mate-~; 10 I rials are heteroeyelie eompounds whieh contain one or more ~;
heteroatoms in the ring and whieh are designated as having an ll aromatie eharaeter beeause of their ehemieal behavior.

; I U.S. Patent 2,948,750 diseloses a process for earboxylating aromatie hydrocarbons by direct introduetioh of earbon dioxide 15j to produee polyearboxylie aeids.
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Suitable starting materials which are disclosed are ;j aromatie hydroearbons, especially benzene but also toluene, xylene, eumene and diisopropyl benzene and other benzenes ¦ substituted with saturated or unsaturated alkyl or eyeloalXyl 20ll radieals, naphthalene, diphenyl, diphenylmethane and other aromatic compounds which may also be substituted with hydro-I earbon radicals.

Seleetive earboxylation is aeeomplished by heating the starting materials in the presence of an aeid-binding agent, 251 and earbon dioxide under anhydrous conditions. Examples of the 1 aeid-binding agent are earbonates of alkali metals, espeeially . . .

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' ., ,f potassium carbonate, the salts of other weak acids such as bicarbonates, formates, or oxalates. Similarly, the corres-; Il ponding compounds of other metals are suitable; for example, the earbonates o the alkali earth metals.
, ,1 S l U.S. Patent 3,023,216 discloses a method of introdueinq ~ I earboxyl groups into aromatic carbocyclie compounds free from ; ~ i!
earboxyl groups by reacting these eompounds in a non-oxidative atmosphere with alkali metal salts of aromatie carboeyclie or ' I aromatie heteroeyelie earboxylie aeids.

10 I Suitable compounds which are free from carboxyl groups whieh may be used as starting compounds in this patent are ¦I similar to the starting compounds in U.S. Patent 2,948,750.

U.S. Patent 3,023,216 discloses reacting aromatic ear-llboxylic eompounds free from earboxyl groups with aromatic 15l;carboxylic aeids in the form of their alkali metal salts.

Both U.S. Patents 3,023,216 and 2,948,750 require specifie ! I
¦ehemieal eompounds as starting materials.

U.S. Patent 2,833,816 diseloses a process for oxidizing ~;~ aromatie eompounds using a eatalyst comprising a lower aliphatic 20 ~earboxylate salt of a heavy metal and bromine. Examples of a heavy metal are manganese, cobalt, nickel, chromlum, vanadium, molybdenum, tungsten, tin, and cerium.

The metals may be supplied in the form of metal salts;
for example such as manganese aeetate. The bromine may be ` ''', `, .
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supplied as ionic bromine, or other bromine compounds solu~le in the reaction medium such as potassium bromate.
.~ , ` Thus, the process requires the conjoint presence of ` bromine and a heavy metal oxidation catalyst.

The starting material required is an aromatic compound ` containing one or more aliphatic substituents to produce I corresponding aromatic carboxylic acids.
:, , ;; U~S. Patent 3,Q64,043 discloses a process for oxidizing para-toluic acid or para-formyl toluene to produce terephthalic 10,, acid.
, ,' U.S. Patent 3,064,046 discloses a process for oxidizing toluic acid or formyl toluene to produce orthophthalic acid or isophthalic acid.

I . .
l Both U.S. Patents 3,064,043 and 3,064,046 require specific 15'~ starting materials to be oxidized.

I ,i U.S. Patent 3,558,458 discloses a process for preparing ': ~ '! . !
aromatic acids by treating an alkyl aryl ketone ~ith water at an elevated temperature in the presence of a reaction promoting agent. The reaction promoting agent may comprise an alkaline ~` 20l catalyst, a transition metal salt, or actinic light. Examples ¦l of an alkaline catalyst include potassium acetate, lithium acetate, rubidium acetate, and cesium acetate. The process is - l . i ,! conducted in water at a temperature of about 200C to 400C.
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I ~l The art discloses processes for the alkaline oxidation of coal employing large amounts of chemicals relative to the . ~ I

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amount of water soluble coal acids produced, see Uni~ed States Patent 2,786,074 and a report entitled "Production of Chemicals by Oxidation of Coal", Battelle Laboratory, Columbus, Ohio of March 31, 1975. The report also suggests the use of potassium ` ; acetate and acetic acid in a cyclic process for the Henkel reaction at page 19.
Recovery of caustic soda and sodium carbonate was dis-closed by Industrial and Engineering Chemistry, Volume 44 (1952), at page 2791 in an article entitled "Water-Soluble Polycarboxylic ~ , , Acids by Oxidation of Coal" beginning at page 2784.
Japanese Patent 18,365 discloses the reclamation of alkali by recrystallization and requires the consumption of one part by weight of the alkali and 1.5 parts of sulfurlc acid for each :;
two parts of coal consumed.
Non-alkaline oxidation of coal generally yields about 10 parts by weight of water soluble coal acids based on 100 parts of coal carbon consumed. Alkaline oxidation yields have ::
been about 30 to about 42 parts per 100 parts of coal carbon consumed. Therefore, alkaline oxidation processes are favored because of the higher yield possible.
In systems like HCI/KCl, H2S04/K2S04, and HN03/KN03 the salts do not produce an alkali solution by hydrolysis because ., ~ s ~ the acids involved are too strong. These systems over oxidize ,.. ,........................................................................ ~
~ the coal and therefore result in much lower yield of coal -:
` acids.

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Another disadvantage of treatment of coals with strong acids is the production of unwanted by-products by chlorination, sulfation, or nitra-tion of the aromatic nuclei of the coal.
` Coal acids have been prepared by nitric acid oxidation, United States Patents 3,~68,9~3; 3,709,931; 2,555,~10; in the presence of nitrogen catalyst, United States Patent 3,702,340; and oxidation in a non-alkaline aqueous medium, United States Patent 3,259,650.
The caustic-oxygen treatment of coal has been described in United States Bureau of Mines Information Circular No. 8234 at pages 74 to 98.
In another process, United States Patent 3,259,650 discloses the use of a non-alkaline medium and produces lower yields of water soluble coal acids.
United States Patent 2,927,130 discloses a process for the recovery of alkalis and terephthalic acid from aqueous solutions containing alkali ~ ~ salts of terephthalic acid. Alkalis of interest are sodium, potassium and ; ammonium. The patent discloses that dialkali salts of terephthalic acid in ,..
aqueous solution can easily be divided into difficultly soluble monoalkali .. . . .
salts and alkali bicarbonate by introducing carbon dloxlde lnto the solu-" tion, and that the difficultly soluble monoalkali salts of terephthalic acid ;;:
~ 20 can be hydrolyzed with water into free terephthalic acid and dialkali salts ... ..
; ~ of terephthalic acid. The free terephthalic acid separates out as a solid, while the dialkali terephthalate remains in solution.

. Although oxidation can be carried out in reclaimable acidic media, ~ these processes are not as desirable because of lower yields and unwanted -~ by-products due to chlorination, sulfation, and nitration.

The use of the applicant's invention allows reclamation of the re-..;., ' agent, higher yields, and less production of undesirable by-products. In the applicant's invention, the material principally consumed in the process ;: ~
~:~ is the aromatic material. Almost all other reagents are almost fully re-coverable and completely reusable. In one embodiment of the applicant's invention, the applicant has found that 92 to 95 percent by weight of potas-;,~ sium could be recovered as potassium acetate.

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SUMMARY OF THE INVENTION
This invention provides an improved process for che production of carboxylic acids from carbonaceous materials.
According to the present invention; there is provided a process for producing carboxylic acid from carbonaceous material comprisiny:
a. treating a mixture of i. a carbonaceous material, ii. water, and iii. a water soluble reagent comprising a Group Ia or IIa metal formate, 10 acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, with oxygen, under conditions sufficient to convert at least a portion of said carbonaceous material to a carboxylic acid salt of said reagent;
b. removing water from said mixture from step (a);
d C. treating the mixture from step (b) with an acid of said -; reagent to convert at least a portion of said carboxylic salt to carboxylic acid and said reagent and to precipitate said carboxy-lic acid; and -d. separating said carboxylic acid formed in step (c) from said 20 reagent.
Furthermore, the invention provides a process for produc-ing isomerized aromatic carboxylic acid from aromatic materials `
comprising:
a. treating a mixture of an aromatic material, water, and a water soluble reagent comprising a Group Ia or IIa metal, said reagent producing an alkaline solution by hydrolysis, with oxygen -under conditions sufficient to convert at least a portion of said aromatic material to an aromatic carboxylic acid sal-t of said Group Ia or IIa metal of said reagent;
30 b. isomerizing said aromatic carboxylic acid salt by heating to produce an isomerized aromatic carboxylic acid salt without ,, . . ,- . : ~ :-:

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-P converting said aromatic carboxylic acid salt to an aromatic carboxylic acid salt of a different Group Ia or IIa metal prior to isomerizing said aromatic carboxylic acid salt;
c. converting said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and regenerating said reagent comprising said Group Ia or IIa metali d. recovering said isomerized aromatic carboxylic acid; and e. recycling said reagent comprising said Group Ia or IIa metal thusly regenerated to step (a) to supply a portion of said reagent required for producing said aromatic carboxylic acid salt.
- Thus mixture of carbonaceous material, water, and a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate is first formed. The Group Ia or IIa metal formate, acetate, or propionate is such that it will produce ~' an alkaline solution by hydrolysis. Thus, hydrogen is excluded ~ from the group comprising Group Ia or IIa metals.
`- Examples of such soluble reagents are potassium acetate, potassium formate, potassium propionate, sodium acetate, sodium formate, sodium propionate, lithium acetate, lithium formate, :,:
~ lithium propionate, magnesium acetate, calcium acetate, barium -~ acetate, beryllium acetate, etc.

The carbonaceous material may be coal, lignite, peat, , coke, char, and other materials containing, or capable of evolving, or producing, a hydrocarbon material, either liquid or solid.

`~ Pure water is not required and in fact process water may - be used over and over at least in part.
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~ The mixture can be formed in any manner in a mlxlng zone ;~ using mixers suitable for handling slurries containing solids if a solid or solid-like carbonaceous material is to be converted, or mixers suitable for handling liquids if liquid aromatic ~''! ' ' ~ - lOa -i~ ,.
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materials are to be converted.
The mixture is removed from the mixing zone and fed to a reaction zone wherein the mixture is reacted with oxygen, .~ .

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5~ii or an oxygen-containing gas such as air. The reaction zone and the mi~ing zone can be, if desired, in the same vessel as in some batch-type processes r or they may be separate vessels as ~ in some continuous processes.

5, More particularly, this invention provides an improved i process for the production of aromatic carboxylic acids from ,1 aromatic materials.
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A mixture of an aromatic materialr water, and a water I soluble reagent comprising a Group Ia or IIa metal formate, 10~ acetate, or propionate is first formed. As described above, the Group Ia or IIa metal formate, acetate, or propionate is such that it will produce an alkaline solution by hydrolysis.
Thus, hydrogen is excluded from the group comprising Group Ia or IIa metals.

; 151 Examples of such soluble reagents are potassium acetate, , 1 potassium formate, potassium propionate, sodium acetate, sodium I '` formate, sodium propionate, lithium acetate, lithium formate, -~ ! lithium propionate, magnesium acetate, calcium acetate, barium i ~1 acetate, beryllium acetate, etc.

201~ The aromatic material may be coal, especially bituminous coal, petroleum residium, lignite, peat, pitch, tar, coke, char, oil shale, oil from oil shale, and any other material containing or capable of evolving or producing aromatic material ; , either liquid or solid.

25', Any kind of coal, including lignite, anthracite, or coke or char can be used, but bituminous coals give the best yields.
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~z~5 . . , Yields of benzene carboxylic acid from anthracite coal are low because anthracite is too aromatized. Anthracitic coals produce a product having a high percentage of polynuclear aromatic acids.
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Sll Yields from lignites are low because lignite produces little aromatic material, thus the yield of aromatic carboxylic acids will be low.

¦ The mixture is treated with oxygen under conditions sufficient to convert the aromatic material to an aromatic lOI,carboxylic acid salt of the reagent. In general, a temperature I llof about 200C to about 350C is required. The pressure in the reaction zone should be sufficient to maintain a liquid state in the reaction zone. Generally this requires a pressure of at ¦least about 250 psig. Preferred reaction zone conditions are 15i`about 270C and about 900 psig.

¦ Reaction times in the reaction zone depend upon the ;~
' lltemperature, degree of agitation, the proportion of aromatic material, water, and water soluble reagent, the solid-to-liquid ratio, and the particle size of the solid material. Generally, 20¦~reaction times of from about ten minutes to about three hours are required.

During oxidation carboxylic acids are formed which react I!with the reagent to form carboxylic acid salts, and the volatile - ,lacid of the reagent, the latter of which can be reclaimed by ~ 25'lventing vapor from the reactor.
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i After treating the mixture with oxygen or an oxygen-containing gas such as air to convert the aromatic material into aromatic carboxylic acid, water is removed from the mixture in a dewatering zone. In the dewatering zone, an 5l amount of water is removed which is sufficient that upon the addition of "an acid of said reagent" that at least a ~ortion of the aromatic carboxylic acid salt will be converted to an aromatic carboxylic acid precipitate. The solution will ¦ contain the regenerated reagent which can be recycled for 10¦l further use.

As used herein and claimed herein, the expression "an acid of the reagent" means an acid which is formed by the ~ Il replacement of the Group Ia or IIa metal atom of the water ; ¦I soluble reagent with hydrogen. The acid, therefore, will 1S fl either be formic, acetic, or propionic acid, or mixtures ;I thereof.

¦ Thus the invention can be seen to comprise the use of Il an alkaline-acid-system. Examples of alkaline-acid-systems : l!
', which may be used in the invention are potassium acetate-acetic 20 il acid, or potassium forma~e-formic acid, or potassium propionate-.~ j, propionic acid. Any alkaline-acid buffer system can be used !
l from which a component is volatile or extractable. Since ,.; l -; ¦ potassium acetate is the most soluble, it is therefore preferred.

i As mentioned earlier, systems liXe HCl/KCl, H2S04/K2S04, 2s il and HN03/KN03 are unsuitable because the salts do not produce an alkali solution by hydrolysis since the acids involved are ~ I , .li il i~ - 13 -,;,. .. .

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, too strong. Equally important is the fact that unwanted by-products are formed by chlorination, sulfation, or nitration o aromatic nuclei.

The dewatering zone can be in the same vessel as the ,1 reaction zone as in some batch processes, or it can be in a separate vessel as in some continuous processes.

The water from the dewatering zone can be used in the ~, mixing zone to supply at least part of the water reqùirements ~i in the mixing zone.

10l The dewatered mixture, i.e., the mixture from the de-i watering zone, is then treated in an acidification zone with an 1l acid of the reagent to convert the aromatic carboxylic acid ; I salt to an aromatic carboxylic acid precipitate and the reagent~
i 1I For example, potassium phthalate treated with acetic acid is 15 11 converted to phthalic acid and potassium acetate. In the case I where no aromatic carboxylic acid precipitate is formed separa-!
,I tion can be achieved by solvent extraction or other suitable ; ~, means.

~ The acidification zone may be in the same vessel as the ; ~;
- 20~l~ dewatering zone as in some batch processes, or it can be in a i separate acidification vessel as in some continuous processes.
Sufficient acid must be added to the mixture to effect the conversion of the aromatic carboxylate to the aromatic carboxy-lic acid and to cause precipitation.
.. : i 25, The conditions in the acidification zone must be such that the s~ecies of aromatic carboxylic acid desired to preci-11 .
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pitate will in fact precipitate. These conditions, especialiy temperature, will vary depending upon the species or species of aromatic carboxylic acids which are desired to form precipitates.

j After forming the aromatic carboxylic acid precipitate, the precipitate is separated rom the mixture in a separation zone. Any apparatus capable of separating solids from liquids may be used such as a filter. The separated solid comprises the aromatic carboxylic acid precipitate.

The separated liquid from the separation zone is treated 10l, in a regeneration zone to recover the reagent from the liquid.

' The liquid stream from the acidification zone contains ~ l both the reagent and an acid of the reagent. The reagent and ,. , the acid of the reagent are separated in a separation zone.
The separated reagent can be used for additional treatment of fresh aromatic material in the mixing zone whether the process `~ ; is batch or continuous.

The separated acid of the reagent can be used to acidify , !
additional material in the acidification zone whether the ~process is batch or continuous.

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20~ In another embodiment an isomerized aromatic carboxylic acid is produced by treating a mixture of an aromatic material, water, and a water soluble reagent comprising a Group Ia or IIa metal, the reagent is such that it produces an alkaline solution ' by hydrolysis, with oxygen under conditions sufficient to convert at least a portion of the aromatic material to an , .
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~aromatic carboxylic acid salt of the Group Ia or IIa metal of the reagent. The aromatic carboxylic acid salt is isomerized ~by heating to produce an isomerized aromatic carboxylic l,acid salt without converting the aromatic carboxylic acid salt l~to an aromatic carboxylic acid salt of a different Group Ia or IIa metal prior to isomerizing the aromatic carboxylic acid salt. Thus, for example, a sodium salt of the aromatic carboxylic acid is not converted to a potassium salt of the aromatic carboxylic acid. The isomerized aromatic carboxylic acid salt llis then converted to an isomerized aromatic carboxylic acid, and ; i¦the reagent comprising said Group Ia or IIa metal is regenerated.
The isomerized aromatic carboxylic acid is recovered and the reagent comprising the Group Ia or IIa metal thusly regenerated ¦is recycled to supply a portion of the reagent required for ,producing the aromatic carboxylic acid salt.

' ,~ The process is particularly valuable where the said aromatic material is coal and/or the reagent is a potassium reagent.

i BRIEF DESCRIPTION OF THE DRAWINGS
I! _ .
. 20 ¦i Figure 1 is a schematic flow diagram for my process for the production of terephthalic acid from bituminous coal.
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; ¦ Figure 2 is a schematic flow diagram for my process for ! the production of carboxylic acid from coal.

'I DESCRIPTIGN OF PREFERRED EMBODIMENT

l, Referring to Figure 1, a finely divided bituminous coal ; l~through stream 10, water through stream 12 and potassium - 15a -'.1 .

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acetate through stream 14 are introduced into mixer 20. About five parts water by weight and about 1 to 5 parts by weight of potassium acetate are added to the mixer per part by weight of coal. Any type of mixer may be used. After mixing, the ` 5 mixture is removed from mixer 20 through stream 22 and intro-`I duced into autoclave 30. Air or oxygen is introduced into . .
autoclave 30 through line 24. About two parts by weight of oxygen per part by weight of coal is charged to autoclave 30.

` Ifi The coal is oxidized in autoclave 30 to produce aromatic lOII carboxylic acids comprising benzene carboxylic acids, poly-nuclear aromatic acids, carbon dioxide and water. The potassium ` ¦ acetate reacts with the thusly formed acids to produce potassium f~ ~I salts thereof and acetic acid.

` il The autoclave is operated at a temperature of about 200 15 ll to about 350C, preferably about 270C, and at a pressure of about 250 psig to about 2000 psig, preferably about 900 psig.
Temperatures below about 200C are not desirable because the formation of polynuclear aromatic carboxylic acids are favored ll and temperatures above about 350C are not desirable because 201l the formation of carbon dioxide is favored. Pressures outside ~ l¦ this range, however, can be used. Lower pressures are not : I! desirable because kinetic rates are lower. Higher pressures - l¦ are not desirable because of the cost of high pressure equipment i and compression costs. Preferably the contents of autoclave 30 25l are agitated to increase product yield and to lower reaction time.

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1. i t Gases comprising carbon dioxide, acetic acid and water vapor are removed from autoclave 30 through line 31 and fed ,' into condenser 350. In condenser 350 the vaporous acetic acid , and water vapor are condensed. The condensate and gases are removed from condenser 350 through line 360 and fed to separator , 370. The condensate comprising aqueous acetic acid is separated ',from the gas comprising carbon dioxide in separator 370. The , 'gas is removed from separator 370 through line 380 and the llcondensate through line 390. Both of streams 380 and 390 are lO~¦fed to subsequent steps in the process as will be described " Illater.
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, j The thusly formed aromatic acid salts are discharged from autoclave 30 through line 32 to filter 40. , -,,!!
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Filter 40 is used to separate the liquid product from 15,,residual solids. Filter 40 may be any type Oe filter, such as a precoated revolving drum filter or a vacuum filter. The , liquid product containing the dissolved thusly formed potassium ~ ~,acid salts is removed from filter 40'through line 42. The ', llsolids which contain unreacted coal and ash are removed from 20,`filter 40 through line 44 and recycled to mixer 20. The filtration step is optional and is not needed if the solids in stream 32 will not interfere with a subsequent isomerization ! step as described later.
i1 Liquid stream 42 from filter 40 is charged to evaporator , 25 50 where most of the water therein is removed. The damp solids ;,containing the thusly formed potassium acid salts are removed 1. ' ~

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~LZ~1~)55 from the evaporator 50 through line 52 and enter dryer 60.
Water from evaporator 50 is removed through line 54 and recycled to mixer 20.

In dryer 60, the remaining water which contains acetic 5 , acid is removed from the damp solids. The thusly formed dry solids are removed from dryer 60 through line 62 and charged to il isomerization reactor 80. It is important to dry the solids charged to the isomerization reactor sufficiently to prevent 1 ll excessive reaction between water and aromatic carboxylic acids .'~ 10l~ in the isomerization reactor.
,, I
In an alternate embodiment, potassium benzoate can be introduced, as through line 66, into isomerization reactor 80 to simultaneously undergo conversion to terephthalic acid.
. .1 .
~ In isomerization reactor 80, the dry acid salts are ., catalytically isomerized at a temperature of from about 400C
¦, to about 440C at a pressure of about 10 atmospheres, and for a -period of time of about 10 to about 100 minutes to cause isomerization of the dry potassium acid salts to more valuable 'I products such as terephthalate and isomerized polynuclear ~`
20~l aromatic acid salts.

,I Preferably a carbon dioxide environment is maintained - Il in the isomerization reactor. Especially preferably the carbon dioxide is produced in the oxidation step as mentioned earlier ' and is fed to the isomerization reactor 80 through line 380.
25l If free oxygen is present in the gas in line 380 then it must l be removed or converted to carbon dioxide (not shown) before ; - 18 -. . ~

the gas is fed to isomerization reactor 80. Stream 380 may be used as a source of carbon dioxide without any subsequent puri-fication or treatment, if it does not contain free oxygen, since it is not necessary to use pure carbon dioxide. In still another embodiment, any inert atmosphere, such as nitrogen, may be used.
Examples of catalysts useful for promoting the isomeriz-ation are the oxides, carbonates, or halides of zinc or cadmium. Organic salts, particularly carboxylates such as cadmium ben~oate, are particularly good catalysts. Cadmium iodide is a preferred catalyst, in concentrations varying from 1 to 15 parts by weight per 100 parts by weight of aromatic carboxylic acid salts. The preferred concentration of cadmium iodide is about 5 parts by weight per 100 parts by weight of the aromatic carboxylic acid salt mixture.
The products are removed from isomerization reactor 80 through line 82 and enter cooler 90 where the products are cooled to a temperature of about 200C to about 100C, pref-erably about 100 C. It is necessary to cool the products because decomposition occurs at higher temperatures when exposed to water or oxygen. For example, exposure to water can cause potassium tereph~halate to decompose to ben~oic acid and potassium bicarbonate; and exposure to oxygen can cause potas-sium terephthalate to decompose to carbon dioxide and potassium bicarbonate.
The cooled products rcmoved from cooler 90 through line 92, together with water from line 94, are charged to dissolver .

. - 19 -, s :
100. In dissolver 100 the potassium acid salts are completely dissolved.
The mixture is removed from dissolver 100 through line 102 and enters filter 110 where any undissolved solids are separated from the liquid portion of the mixture. The thusly separated liquid portion is removed from filter 110 through line 112 and charged to precipitator 120. Treatment of the solution with activated charcoal to remove any impurities which impart a color to the terephthalic acid solution can be performed , 10 prior to the precipitation step if desired.
The thusly separated solids, which consist essentially of char and ash, are removed from filter 110 through line 114 and a portion thereof lS recycled to mixer 20 by way of line 116, or alternately the solids are recycled to autoclave 30 (not shown), to undergo further oxidation to produce additional carboxylic acids. In order to prevent buildup of solids, principally ash, in the system, another portion of the solids is removed from the system through line 118.
In still another embodiment ~not shown), solids from filter 110 are mechanically treated or floated to separate the ash material from the carbonaceous material. The carbonaceous -material can be returned to mixer 20, or alternately to auto-clave 30, while the separated ash fractlon is removed from the system.
Returning to dryer 60, the vapor stream, removed from the dryer through line 64, is fed to condenser 70 wh~re~pon water .~
'' :

~"
. ~,, ' t5S

vapor containing acetic acid vapors is condensed to produce a~ueous acetic acid. The condensate and any gases are removed from condenser 70 through line 72 and fed to separator 75 which separates the aqueous acetic acid from the gases. The separated 5` aqueous acetic acid is removed from separator 75 through line , 76 and then charged to precipitator 120. Make-up acetic acid ' ' is fed to precipitator 120 through line 124. An excess of acetic acid is maintained in the precipitator to effect preci-~ ¦I pitation of terephthalic acid. A pH of about 3 to about 7, 10,, preferably about 4.7 to about 5.5, is maintained in preci-pitator 120 to cause conversion of the potassium terephthalate ¦ to the terephthalic acid. By controlling the pH in the preci-pitator in this range, i.e. about 3 to about 7, terephthalic Il acid will be formed from the potassium acid salt and will be 15¦ caused to precipitate. Other aromatic carboxylic acids are ¦ more soluble than terephthalic acid and will remain in solution.
' A low pH, for example below about 3, in the precipitator is ~i undesirable because this will cause impurities to co-precipitate ¦¦ with terephthalic acid,while a high pH, for example over about 20i' 7, is undesirable because insu~ricient precipitation o tereph-thalic acid will result, thereby reducing the yield.

¦I The temperature in the precipitator must be controlled below the temperature at which significant product begins to dissolve. This temperature is about 5C to about 25C when the 25l principal product is terephthalic acid. Precipitator 120 may be any type, such as a continuous stirred tank reactor.

!

i ; 1, ' .
!i S

` Gases removed ~rom separator 75 through line 77, which ; I comprise carbon dioxide, can be used to maintain at least part of carbon dioxide atmosphere in the isomerization reactor 80.
These gases are fed to reactor 80 through line 78 or vented 5` through line 79. If gases from separator 75 contain free oxygen then the free oxygen must be removed or converted Ij I ~ to carbon dioxide (not shown) before the gases are fed to ¦ isomerization reactor 80.
,, i . '.
l All of the products are removed from precipitator 120 lOI~through line 122 and enter filter 130. Filter 130 may be any jltype, such as a precoated revvlving drum filter. -The solid product, terephthalic acid, is removed from filter 130 through line 131 and stored in s~orage vessel 135, 15l, The liquids are separated from the solid terephthalic ¦acid in filter 130 and the liquid is removed from the filter -through line 132. If it is desired to remove more soluble carboxylic acids from the acid solution, then liquids in line 132 are fed to separator 140.

. ,!
20l Separator 140 may be a liquid-liquid extraction apparatus.

The separated carboxylic acids are removed from the separator 140 through line 152 and are fed to purifier 160. Purification of the carboxylic acid in purifier 160 may be by conventional Imeans. The purified carboxylic acids are removed from the : , ; 25 purifiér 160 through line 162 and sent to storage vessel 170.

~ The impurities, consisting principally of potassium salts and : I, ' i ~ - 22 , . 1'1 , 1:~2Q~55 ;
water soluble aromatic acids, are removed from purifier 160 through line 164. These impurities may be recycled to the autoclave.
. !`
In an alternate embodiment (not shown), if it is not 5 desirable to remGve the more soluble carboxylic acids from liquid stream 132, then stream 132 is fed directly to separator ~ll90 instead of stream 142 for separation of acetic acid from ¦¦potassium acetate. In this embodiment, elements 140, 142, 152, 1 160, 162, 164, and 170 are omitted.

10 ~I Returning to separator 140, stream 142, which does not ¦contain the separated aromatic carboxylic acid but which contains potassium acetate and acetic acid, is fed to separator l90 for separation of acetic acid from potassium acetate.
IlAcetic acid may be separated from potassium acetate in separator 15 lll9o by distillation or by steam distillation, or by solvent extraction or by other standard procedures.

- I The separated acetic acid is removed from separator 190 through line 194 and is recycled to precipitator 120 through 'line 126. Make-up acetic acid may be added to precipitator 120 ~ 1 20 Ithrough line 124.

Il Potassium acetate is removed rom separator 190 through ¦lline 192 and enters reactor 200 whereupon it is treated with lime which is introduced to reactor 200 through line 196. The ilpurpose of the lime treatment is to prevent buildup of sulfate 25 lin the recycle stream and thereby liberate potassium for ; lirecycle. Reactor 200 can be a con~inuous stirred tank reactor.

,~

s5 !
",`'' "
The product from reactor 200 is removed therefrom through ~j line 202 and enters filter 210 whereupon calcium sulphate is : ` separated as a solid from the liquid stream containing the , dissolved potassium acetate. Filter 210 may be any type, such as a vacuum filter. Calcium sulphate is removed from filter 210 by line 212. The calcium sulphate may be used in the ; making of portland cement, gypsum or pool acid or disposed of by landfill. The potassium acetate stream is removed from ~Ifilter 210 through line 214 and is recycled to mixer 20.
''Make-up potassium acetate may be added to mixer 20 through ¦lline 14.

Alternately, if there is no desire to produce isomerized carboxylic acids, stream 32 can be fed directly to filter 110 . ,1 . j .
~and the steps involving elements 40 through 102 are omitted.
IlThe alternate process is shown in Figure 2. This process, l although similar, still has considerable value because of the Ilregeneration and recycling of potassium acetate, line 214, to mixer 20 or, alternately, to autoclave 30 (not shown). ~owever, by eliminating the isomerization step, an aromatic carboxylic ,iacid of different constituents is produced and the yield of '~terephthalic acid will be reduced. This carboxylic acid I Ilmixture is useful in detergent manufacturing.

In another embodiment, the product from the isomerization ~Ireactor 80, preferably having been cooled in cooler 90, dissolved l in dissolver 100 and filtered in filter 110 to remove undissolved :; 1l . .

solids is sent to a precipitator for treatment with carbon dioxide. In this embodiment, the precipitator is used to .. .

~ , - 24 -" ',' - ,i . .
.
.

precipitate the monopotassium salt of terephthalic acid by treatment with carbon dioxide. Thus, the aqueous solution containing dipotassium terephthalate in stream 112 is treated in the precipitator with carbon dioxide to produce the mono~
potassium salt of terephthalic acid and potassium bicarbonate.
jIn this embodiment, which is not shown in either Figure 1 or 2, acetic acid is not charged to the precipitator. The precipitator is maintained at a temperature below about 50C, preferably llbelow 30C, and especially preferably at about 0C to enhance ,the dissolving of carbon dioxide in the solution.

The monopotassium salt of terephthalic acid, a precipitate, is separated from the aqueous solution of potassium bicarbonate in a separation zone which may be a filter. The separated I,monopotassium salt of terephthalic acid is then charged to a lS ~hydrolyzer where it is treated with water to form dipotassium terephthalate and terephthalic acid. The dipotassium tereph-,thalate remains in solution while the terephthalic acid precipi-tates. The terephthalic acid may then be separated from the 'dipotassium terephthalate solution and the dipotassium tereph-Ithalate solution recycled to the precipitator above, or treatedin another zone. In either case, the dipotassium terephthalate ~,is treated with carbon dioxide to convert the dipotassium ¦terephthalate to monopotassium salt of terephthalic acid and additional potassium bicarbonate.

~ The monopotassium salt of terephthalic acid can be neu-ltralized by other means, if desired, such as treatment with ,carbon dioxide or an acid such as acetic acid in an aqueous solution.

, 1, ,1 !! ., --- \
~z0~ss The potassium bicarbonate solution after separation from ithe monopotassium solid terephthalic acid can be recycled to ~mixer 20, or alternately to autoclave 30, as the water soluble reagent comprising a Group Ia or IIa metal. Preferably the S potassium bicarbonate is converted to potassium carbonate by heating, and the potassium carbonate is recycled to mixer 20, ~or alternately to autoclave 30, as the water soluble reagent 'comprising a Group Ia or IIa metal. In this embodiment, the liwater soluble reagent comprising a Group Ia or IIa metal does "not require the use of a formate, acetate or propionate of such metal.

Furthermore, in this embodiment the alkali metal reagent, which is potassium in the above description, is recovered and lrecycled in the process. As can be seen, nd conversion of the l~potassium aromatic carboxylic acid salt prior to isomerization is required in the process. That is to say, it is not necessary to convert the potassium acid salt to a sodium acid salt, or ~ -vice versa, prior to isomerization. -~ The process of this invention has the advantage over prior lart for producing terephthalic acid in that it is not necessary ,to prepare the salts of the aromatic carboxylic acids, then to separate the benzene carboxylic acids from the remaining polynuclear carboxylic acids; and then to convert the benzene ~Icarbox~lic acids to the potassium salt of the a,_ids prior to 25 isomerization. ~-.

, . ~ , .

~Z~1~55 Anothe~ advantage of this invention is that it is not necessary to prepare the salts in a separate zone apart from ` the o~idation zone since in this invention the salts are prepared directly in the oxidation zone.

1 Another advantage of this invention is that it is not necessary to treat the aromatic carboxylic acid salts or convert the aromatic carboxylic acid salts to their aromatic ,¦carboxylic acids and then treat, with a compound which contains 'la Group Ia or IIa metal prior to isomerization.

I Similarly, another advantage of this invention is that it is not necessary to convert the aromatic carboxylic acid salts ito their aromatic carboxylic acids and to treat the aromatic ! carboxylic acids with a Group Ia or IIa metal prior to lisomerization.

15 ll Still another advantage of this invention is that after ,the aromatic material is oxidized in the presence of a first compound comprising a Group Ia or IIa metal to form an aromatic carboxylic acid salt of the Group Ia or IIa metal, it is not necessary to convert the aromatic carboxylic acid salt of the ,IGroup Ia or IIa metal to another aromatic carboxylic acid salt of another Group Ia or IIa metal prior to isomerization.

Another advantage is that the reagent is regenerated by the process.

., . .

EXA;1PLE I

Regeneration of Reagent The following is an example of the conversion of an aromatic carboxylic acid with a metal acetate to a metal S aromatic carboxylate followed by the conversion of the metal aromatic carboxylate by treating with an excess acetic acid to convert the metal aromatic carboxylate to aromatic carboxylic ~ -acid. ~This corresponds to Step Nos. 30, 40, 50, 60, 120, 130, ` and l90 in Figure l.) 18.82 gr of dry reagent grade trimesic acid (l, 3, 5 ~benzene-tricarboxylic acid) was added to a flask together with 39.50 gr of potassium acetate and 300 gr of water. This mixture ~was boiled until all of the trimesic acid was dissolved.
~ (This corresponds to the state found in autoclave 30 of 15~~igure l.) ., .
The mixture was then evaporated to dryness. It is estimated that at least 80% of the acid was converted to its potassium salt. (This corresponds to the state found in dryer ~ 60 of Figure l.) The condensate consisted of acetic acid and water.

Three extractions of the acid salt took place using 80 cm3 ~ i ,of a mixture containing 90% glacial acetic acid and 10% by weight ,of water for each extraction. Each extraction took place at i 60C with stirring for 15 minutes. Each time the acetic acid ., . i I

~Z~I~S5 water mixture containing newly formed potassium acetate was passed through a 50-60 ASTt~ sintered glass filter, with the newly formed trimesic acid remaining behind. (This corresponds to steps 120 and 130 in Figure 1.) The extract was evaporated to dryness by heating to 200C under vacuum. 37.53 gr of extract or 95~ by weight of the original potassium acetate was recovered. The weight of the remaining dry trimesic acid was 20.22 gr. It thus con-tained the remaining potassium. (This corresponds to step 190 in Figure 1.) The fact that the reclaimed potassium acetate may contain some potassium trimesate and trimesic acid in this experiment is of no consequence to the process of this invention because it is intended that the reclaimed potassium acetate be recycledO
However, should a higher reclamation factor be desired, the extraction with the acetic acid water mixture can be repeated with the results being predicted by a fractionation curve as used in distiilation.

EXAMPLE II

Oxidation of Coal i About 28 gr of coal, 170 gr of potassium acetate, and 400 gr of water were charged to a stirred autoclave.

The mixture was treated with oxygen at a total pressure of 1700 psig at a temperature of 500F for 30 minutes with continuous stirring taking place.
.

., , :, , i '~

~ \
~L~L2~5S

The autoclave contents were analyzed and 12.8 gr of coal acids were found to be present. About 6.4 gr of this was benzene-carboxylic acids, which represents a 28~ yield on a dry ash free coal basis.

EXAMPLE III
:
Regeneration of Reagent, Specifically Potassium Acetate To demonstrate the regeneration of potassium acetate, the , following experiment was carried out.

Pyromellitic acid, a typical constituent of coal acids, I -, I ~
10 ~ was used. I --18.82 gr of pyromellitic acid were reacted with 39.5 gr of potassium acetate to give 30.4 gr of tetrapotassium pyromellate and an unmeasured amount of acetic acid. The acetic acid is ' recoverable by distillation. The salt was extracted with a ', -15 I water/acetic acid mixture, and 37O5 gr of potassium acetate , was recovered. 1-The salt was converted back to pyromellitic acid. Thus, 95~ potassium acetate was reclaimed after forming the potassium , salt of pyromellitic acid.

- 20 ~XAMPL~ IV
:

Precipitation of Aromatic Carboxylic Ac d, Specifically , Terephthalic Acid A prepared solution of potassium terephthalate consisting of 10 gr of potassium terephthalate in 100 gr of water was treated with 100 ml of 6~ acetic acid solution and immediately i produced 6.7 gr of a white precipitate of terephthalic acid.

' ', . . ~ .
, - 30 - ' , EXAMPLE V

Isomerization of Coal Acids Abo~t 9.3 gr of coal acids were converted to their corresponding potassium salts. 0.5 gr of cadmium oxide was thoroughly mixed with the salts. The mixture was then dried to remove moisture.

The mixture was charged to an autoclave which was pres- j surized to 130 psig with carbon dioxide. It was heated to ,' 400C and maintained at that temperature for four hours while at 130 psig.

After cooling, the mixture was dissolved in boiling water ~and filtered to remove char containing the cadmium~
., .
Upon acidification of the mixture with 100 ml of 6~
' acetic acid solution, a yield of 3.2 gr of terephthalic acid 15~ was obtained. This corresponds to a 36~ yield from the coal acids.

EXAMPLE ~I
, . .
` Conversion of Coal to Terephthalic Acid ~!
, 100 gr potassium acetate and 30 gr of bituminous coal are mixed with 400 gr of water. The mixture is charged to an oxidation autoclave and heated to 260C. Oxygen is slowly added to the autoclave until a total pressure of 1500 psig is achieved. A product gas consisting of carbon dioxide, steam, , . .
., i .
! I i ',' . i ,. `, ~:

;
5~

and acetic acid is periodically vented from the autoclave, and the autoclave is repressurized with oxygen to 1500 psig each time. After half an hour of treatment with oxygen, the autoclave contents are cooled to room temperature and discharged from the autoclave.

The oxidized mixture is dried by boiling until almost dry ~-l~and the vapors condensed. A total of 407.6 gr of liquid i~condensate is collected by combining the condensate from the llproduct gas and the drying operation. The total condensate Icomprises of 16.6 gr of acetic acid. The moist oxidized mixture is thoroughly dried under vacuum for three hours. -Il About 2.0 gr of cadmium iodide, as catalyst, is intimately ¦,mixed with the dried, oxidized mixture. Thq mixture is then 'Icharged to an isomerization autoclave and heated to 150F.
~Remaining moisture is purged from the autoclave using dry j'lcarbon dioxide. The autoclave is heated to 395C for 2.5 hours jj ! :
with 600 psig of carbon dioxide pressure.

The autoclave is then cooled to room temperature. The solid material is removed from the autoclave and dissolved in I I ~
i~100 gr of hot water. The solution is filtered to remove char land solids.

. 1, .
, The condensate from the oxidization and drying steps, 'which contains acetic acid, is added to the solution. A

iprecipitate of 10.2 gr of crude terephthalic acid is formed.

,The terephthalic acid precipitate is separa~ed by filtration.
., , , ~
,1 . , The filtrate, or mother liquor, is evaporated to form a condensate containing 0.9 gr of acetic acid dissolved in 450 gr of water. 102 gr of solid residue, containing 98.5 gr of potassium acetate is obtained. The solid residue is recycled to the next oxidation step.

The 450 gr of water is reduced in weight to 400 gr and 1.5 gr of makeup potassium carbonate is added, converting the remaining acetic acid in solution to potassium acetate.
The solution is recycled to the oxidation step. It can be seen 10 llthat nearly all of the origlnal potassium acetate is recovered and recycled.

The following table summarizes the mass flows in Example VI.

15 1 Weight of Coal 30.0 gr Weight of Potassium Acetate100.0 gr Weight of Recovered Potassium Acetate 38.5 gr Weight of Unused Acetic Acid0.9 gr ' Weight of Potassium Carbonate Required to Regenerate Potassium Acetate from Acetic Ac1d 1.5 gr i, , ~, .~

,i ,1 .

5~

EXAMPLE VII

Conversion of Coal Char to Terephthalic Acid 100 gr potassium acetate and 30 gr of coal char are mixed with 400 gr of water. The coal char is produced by pyrolyzing a bituminous coal at 1500F for 20 minutes in a ~fluidized bed reactor. The mixture is charged to an oxidation autoclave and heated to 260C. Oxygen is slowly added to the autoclave until a total pressure of 1500 psig is achieved.
~ A product gas consisting of carbon dioxide, steam, and acetic lacid is periodically vented from the autoclave, and the auto-`clave is repressurized with oxygen to 1500 psig each time.
After half an hour of treatment with oxygen, the autoclave contents are cooled to room temperature and discharged from the 'autoclave.

i The oxidized mixture is dried by boiling until almost dry and the vapors condensed. A total of 407.6 gr of liquid condensate is collected by combining the condensate from the product gas and the drying operation. The total condensate IcomPrises of 16.6 gr of acetic acid. The moist oxidized 20 I mixture is thoroughly dried under vacuum for three hours. -About 2.0 gr of cadmium iodide, as catalyst, is intimately jlmixed with the dried, oxidized mixture. The mixture is then ~charged to an iso~erization autoclave and heated to 150F.
~Remaining moisture is purged from the autoclave using dry l~carbon dioxide. The autoclave is heated to 395C for 2.5 hours ,with 600 psig of carbon dioxide pressure.

.j I

- `~

The autoclave is then cooled to room temperature. The solid material is removed from the autoclave and dissolved in lO0 gr of hot water. The solution is filtered to remove char and solids.

The condensate from the oxidization and drying steps, which contains acetic acid, is added to the solution. A precipitate of 6.3 gr of crude terephthalic acid is formed. The terephthalic acid ~precipitate is separated by filtration.

The filtrate, or mother li~uor, is evaporated to form a l condensate containing 0.9 gr of acet1c acid dissolved in 450 gr of l~ water. 102 gr of solid residue~ containing 98.5 gr of potassium acetate is obtained. The so1id residue is recycled to the next oxidation step.

Il The 450 gr of water is reduced in weight to 400 gr and l.5 gr ,lof makeup potassium carbonate is added, converting the remaining ~acetic acid in solution to potassium acetate. The solution is recycled to the oxidation step. It can be seen that nearly all of the original potassium acetate is recovered and recycled.

The following table summarizes the mass flows in Example VII.

20 ~ eight of Coal Char 30.0 gr 1 Weight of Potassium Acetate lO0.0 gr .
~ '~1 Weight of Recovered Potassium Acetate 9~.5 gr , .
Weight of Unused Acetic Acid 0.9 gr Weight of Potassium Carbonate Required to Regenerate Potassium Acetate from ~ Acetic Acid l.5 gr ,, .
, ';

EXA;~PLE VIII

Conversion of Coal Tar to Terephthalic Acid 100 gr potassium acetate and 30 gr of coal tar are mixed with 400 gr of water. The coal tar is produced by pyrolyzing a bituminous coal to 1500F for 20 minutes in a fluidized bed, cooling the product vapors, and recovering the condensed coal tar. The mixture is charged to an oxidation autoclave and heated to 260C. Oxygen is slowly added to the autoclave until a total pressure of 1500 psig is achieved. A product gas consisting of carbon dioxide, steam, and acetic acid is periodically vented from the autoclave, and the autoclave is repressurized with oxygen to 1500 psig each time. After half an hour of treatment with oxygen, the autoclave contents are cooled to room temperature and discharged from the autoclave.

~, l~ '' The oxidized mixture is dried by boiling until almost dry -and the vapors condensed. A total of ~07.6 gr of liquid ~ ~
condensate is collected by combining the condensate from the product gas and the drying operation. The total condensate ,comprises of 16.6 gr of acetic acid. The moist oxidized imixture is thoroughly dried under vacuum for three hours.

¦ About ~.0 gr of cadmium iodide, as catalyst, is intimately mixed with the dried, oxidized mixture. The mixture is then charged to an isomerization autoclave and heated to 150Fo IlRemaining moisture is purged from the autoclave using dry ~lcarbon dioxide. The autoclave is heated to 395C for 2.5 hours with 600 psig of carbon dioxide pressure.

Il `~

The autoclave is then cooled to room temperature. The solid material is removed from the autoclave and dissolved in 100 gr of ~hot water. The solution is filtered to remove char and solids.

The condensate from the oxidization and drying steps, which contains acetic acid, is added to the solution. A precipitate of 11.8 gr of crude terephthalic acid is formed. The terephthalic acid precipitate is separated by filtration.

i' The filtrate, or mother liquor, is evaporated to form a ,Icondensate containing 0.9 gr of acetic acid dissolved in 450 gr of liwater. 102 gr of solid residue, containing 98.5 gr of potassium acetate is obtained. The solid residue is recycled to the next oxidation step.

1. ~
,~ The 450 gr of water is reduced in weight to 400 gr and 1.5 gr of makeup potassium carbonate is added, converting the remaining lacetic acid in solution to potassium acetate. The solution is recycled to the oxidation step. It can be seen that nearly all of "the original potassium acetate is recovered and recycled~

! The following table summarizes the mass flows in Example VIII.

,, .
20 iWeight of Coal Tar 30.0 gr Weight of Potassium Acetate 100.0 gr Weight of Recovered Potassium Ace~ate 9805 gr Weight of Unused Acetic Acid 0.9 gr Weight of Potassium Carbonate Required 25 to Regenerate Potassium Acetate from Acetic Acid 1.5 gr .1 ~z~s~

EXAMPLE IX

Conversion of Heavy Residual Oil to Terephthalic Acid 100 gr potassium acetate and 30 gr of heavy residual oil from a naphthenic crude oil are mixed with 400 gr of water.
The mixture is charged to an oxidation autoclave and heated to 260C. Oxygen is slowly added to the autoclave until a total 'pressure of 1500 psig is achieved. A product gas consisting of ,Icarbon dioxide, steam, and acetic acid is periodically vented Ifrom the autoclave, and the autoclave is repressurized with loxygen to 1500 psig each time. After half an hour of treatment with oxygen, the autoclave contents are cooled to room tempera-ture and discharged from the autoclave.

The oxidized mixture is dried by boiling until almost dry land the vapors condensed. A total of 407.6 gr of liquid Icondensate is collected by combining the condensate from the product gas and the drying operation. The total condensate comprises of 16.6 gr- of acetic acid. The moist oxidized mixture is thorouyhly dried under vacuum for three hours.

~ About 2.0 gr of cadmium iodide, as catalyst, is intimately ,jmixed with the dried, oxidized mixture. The mixture is then ilcharged to an isomerization autoclave and heated to 150F.
- , Remaining moisture is purged from the autoclave using dry ~carbon dioxide. The autoclave is heated to 395C for 2.5 hours with 600 psig of carbon dioxide pressure.

.' . .

"

.

i The autoclave is then cooled to room temperature. The solid material is removed from the autoclave and dissolved in 100 gr of ~hot water. The solution is filtered to remove char and sol ds.

The condensate from the oxidization and drying steps, which contains acetic acid, is added to the solution. A precipitate of ~3.8 gr of crude terephthalic acid is formed. The terephthalic acid precipitate is separated by filtration.

¦; The filtrate, or mother liquor, is evaporated to form a I,condensate containing 0.9 gr oE acetic acid dissolved in 450 gr of ¦,water. 102 gr of solid residue, containing 98.5 gr of potassium ¦lacetate is obtained. The solid residue is recycled to the next oxidation step.

¦ The 450 gr of water is reduced in weight to 400 gr and 1.5 gr i,of makeup potassium carbonate is added, converting the remaining 'acetic acid in solution to potassium acetate. The solution is recycled to the oxidation step. It can be seen that nearly all of , the original potassium acetate is recovered and recycled.

The following table summarlzes the mass flows in Example IX.

20 1¦ Weight of Heavy Residual Oil30.0 gr ¦~ Weight of Potassium Acetate100.0 gr ¦ Weight of Recovered Potassium Acetate 9~.5 gr 'l Weight of Unused Acetic Acid0.9 gr ~ Weight of Potassium Carbonate Required to Regenerate Potassium Acetate rrom Il Acetic Acid 1.5 gr ', - 39 -l l -EXAMPLE X

Conversion of Dipotassium Terephthalate to Terephthalic Acid L ~ c~ ~ D i c ~

29 gr of dipotassium terephthalate were dissolved in 200 S ml of hot deionized water and the solution was filtered to remove any insoluble solids. Carbon dioxide was bubbled through the solution as it was cooled in an ice bath. ~hite crystals immediately began to form. After the suspension of llcrystals in the solution had cooled to a temperature of less l~than -2C (28F) and let stand for thirty minutes, it was then vacuum filtered. The white needles on the filter were washed with ice water, dried in a vacuum oven, and weighed. Approxi-Imately 16.2 gr of precipitate were recovered. A sample was lanalyzed and found to have the composition:

15 ! Element ~ by Wei~ht C 47.4 H 2.8 ',, K 18.1 O 31.7 (by difference) I Pure potassium hydrogen terephthalate has the following ~composition:

Element ~_~Y~
! . .
C 47.0 I H 2.5 ~I K 19.2 O 31.3 Thus, the precipitate is potassium hydrogen terephthalate.

-- ~O --J
,, ~Z0~15S

The potassium hydrogen terephthalate was then dissolved in 160 ml of water and boiled for 5 minutes. About 6.5 gr of terephthalic acid were recovered by filtering the solution.
The solution, which contains dipotassium terephthalate, can be concentrated and recycled to the carbon dioxide precipitation step.

EXAMPLE XI

Conversion_of Dipotassium Terephthalate to Terephthalic Acid ,,Using Carbon Dioxide ~0l 29 gr of dipotassium terephthalate were dissolved in 200 ml of hot deionized water and the solution was filtered to remove any insoluble solids. Carbon dioxide was then bubbled through the solution (cooled to 25C) in a pressure filtration apparatus at 800 psig. About 20 gr of potassium hydrogen terephthalate were recovered after filtration. This was then dissolved in 200 ml of water and boiled for five minutes.
About 8.0 gr of terephthalic acid were recovered by filtration of the solution.

.
~, ~

. :

, ! -` ~

. .

The process of the invention has been described generally ,and by example with reference of clarity and illustration only.
! It will be apparent to those skilled in the art from the foregoing that various modifications of the process and the S 'Imat,erials disclosed herein can be màde without departure from l,the spirit of the invention.

Accordingly, the invention is not to be construed or ¦limited to the specific embodiments illustrated, but only 'as defined,in the fo owing claims.

Claims (71)

I claim:
1. A process for producing carboxylic acid from carbonaceous material comprising:
a. treating a mixture of i. a carbonaceous material, ii. water, and iii. a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, with oxygen, under conditions sufficient to convert at least a portion of said carbonaceous material to a carboxylic acid salt of said reagent;
b. removing water from said mixture from step (a);
c. treating the mixture from step (b) with an acid of said reagent to convert at least a portion of said carboxylic salt to carboxylic acid and said reagent and to precipitate said carboxylic acid; and d. separating said carboxylic acid formed in step (c) from said reagent.
2. The process of claim 1 wherein said reagent is potassium acetate.
3. The process of claim 1 wherein said reagent is potassium formate.
4. The process of claim 1 wherein said reagent is potassium propionate.
5. The process of claim 1 wherein the amount of water removed in step (b) is sufficient that upon the addition of an acid of said reagent that at least a portion of said carboxylic acid salt will be converted to a carboxylic acid precipitate
6. The process of claim 1 further comprising recycling said reagent from step (d) to step (a) to provide at least part of said reagent of said mixture.
7. The process of claim 1 wherein said reagent after separ-ating from said carboxylic acid in step (d) is in a mixture which comprises said acid of said reagent and further comprising separating said acid of said reagent from said reagent; recycling said thusly separated reagent to step (a) to provide at least part of said reagent of said mixture; and recycling said thusly separated acid of said reagent to step (c) to provide at least part of said acid of said reagent required for step (c).
8. The process of claim 1 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
9. A process for producing aromatic carboxylic acid from aromatic material comprising:
a. treating a mixture of i. an aromatic material, ii. water, and iii. a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, with oxygen, under conditions sufficient to convert at least a portion of said aromatic material to an aromatic carboxylic acid salt of said reagent;
b. removing water from said mixture from step (a);
c. treating the mixture from step (b) with an acid of said reagent to convert at least a portion of said aromatic carboxylic salt to aromatic carboxylic acid and said reagent and to precipitate said aromatic carboxylic acid; and d. separating said aromatic carboxylic acid formed in step (c) from said reagent.
10. The process of claim 9 wherein said aromatic material is coal.
11. The process of claim 9 wherein said reagent is potassium acetate.
12. The process of claim 9 wherein said reagent is potassium formate.
13. The process of claim 9 wherein said reagent is potassium propionate.
14. The process of claim 9 wherein the amount of water removed in step (b) is sufficient that upon the addition of an acid of said reagent that at least a portion of said aromatic carboxylic acid salt will be converted to an aromatic carboxylic acid precipitate.
15. The process of claim 9 further comprising recycling said reagent from step (d) to step (a) to provide at least part of said reagent of said mixture.
16. The process of claim 9 wherein said reagent after separ-ating from said aromatic carboxylic acid in step (d) is in a mixture which comprises said acid of said reagent, and further comprising separating said acid of said reagent from said reagent; recycling said thusly separated reagent to step (a) to provide at least part of said reagent of said mixture; and recycling said thusly separated acid of said reagent to step (c) to provide at least part of said acid of said reagent required for step (c).
17. The process of claim 9 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
18. A process for producing aromatic carboxylic acid from coal comprising:
a. treating a mixture of i. coal, ii. water, and iii. potassium acetate with oxygen, under conditions sufficient to convert at least a portion of said coal to a potassium aromatic carboxylate;
b. removing water from said mixture from step (a);
c. treating the mixture from step (b) with acetic acid to convert at least a portion of said potassium aromatic carboxylate to aromatic carboxylic acid and potassium acetate and to precipitate said aromatic carboxylic acid;
d. separating said aromatic carboxylic acid formed in step (c) from said potassium acetate and e. recycling said potassium acetate from step (d) to step (a) to provide at least part of said potassium acetate of said mixture.
19. The process of claim 18 wherein said coal is bituminous coal.
20. The process of claim 18 wherein the amount of water removed in step (b) is sufficient that upon the addition of acetic acid that at least a portion of said potassium aromatic carboxylate will be converted to an aromatic carboxylic acid precipitate.
21. The process of claim 18 wherein said potassium acetate after separating from said aromatic carboxylic acid in step (d) is in a mixture which comprises said acetic acid, and further comprising separating said acetic acid from said potassium acetate before recycling said potassium from step (d) to step (a); and recycling said thusly separated acetic acid to step (c) to provide at least part of said acetic acid required for step (c).
22. The process of claim 18 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
23. A process for producing isomerized aromatic carboxylic acid from aromatic materials comprising:
a. treating a mixture of an aromatic material, water, and a water soluble reagent comprising a Group Ia or IIa metal, said reagent producing an alkaline solution by hydrolysis, with oxygen under conditions sufficient to convert at least a portion of said aromatic material to an aromatic carboxylic acid salt of said Group Ia or IIa metal of said reagent;
b. isomerizing said aromatic carboxylic acid salt by heating to produce an isomerized aromatic carboxylic acid salt without converting said aromatic carboxylic acid salt to an aromatic carboxylic acid salt of a different Group Ia or IIa metal prior to isomerizing said aromatic carboxylic acid salt;
c. converting said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and regenerating said reagent comprising said Group Ia or IIa metal;

d. recovering said isomerized aromatic carboxylic acid;
and e. recycling said reagent comprising said Group Ia or IIa metal thusly regenerated to step (a) to supply a portion of said reagent required for producing said aromatic carboxylic acid salt.
24. The process of claim 23 wherein said aromatic material is coal.
25. A process for producing isomerized aromatic carboxylic acid from aromatic materials comprising:

a. treating a mixture of an aromatic material, water, and a water soluble potassium reagent, said potassium reagent producing an alkaline solution by hydrolysis, with oxygen under conditions sufficient to convert at least a portion of said aromatic material to a potassium aromatic carboxylic acid salt b. isomerizing said potassium aromatic carboxylic acid salt by heating to produce an isomerized potassium aromatic carboxylic acid salt without converting said potassium aromatic carboxylic acid salt to an aromatic carboxylic acid salt of a different Group Ia or IIa metal prior to isomerizing said potassium aromatic carboxylic acid salt, c. converting said isomerized potassium aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and regenerating said potassium reagent;
d. recovering said isomerized aromatic carboxylic acid;
and e. recycling said potassium reagent thusly regenerated to step (a) to supply a portion of said potassium reagent required for producing said potassium aromatic carboxylic acid salt.
26. The process of claim 25 wherein said aromatic material is coal.
27. A process for producing isomerized aromatic carboxylic acid from aromatic materials comprising:
a. treating a mixture of i. an aromatic material, ii. water, and iii. a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, with oxygen under conditions sufficient to convert at least a portion of said aromatic material to an aromatic carboxylic acid salt of said reagent;
b. removing sufficient water from said mixture from step (a) so that said aromatic carboxylic acid salt in said mixture can be isomerized;

c. forming an isomerized aromatic carboxylic acid salt from said aromatic carboxylic acid salt by heating said mixture from step (b) to a temperature suffi-ciently high in the presence of a catalyst;
d. treating said mixture from step (c) with an acid of said reagent to convert at least a portion of said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and said reagent, and to precipitate said isomerized aromatic carboxylic acid;
and e. separating said isomerized aromatic carboxylic acid formed in step (d) from said reagent.
28. The process of claim 27 wherein said aromatic material is coal.
29. The process of claim 27 wherein said reagent is potassium acetate.
30. The process of claim 27 further comprising recycling said reagent from step (e) to step (a) to provide at least part of said reagent of said mixture.
31. The process of claim 27 wherein said reagent after separ-ating from said isomerized aromatic carboxylic acid in step (e) is in a mixture which comprises said acid of said reagent, and further comprising separating said acid of said reagent from said reagent; recycling said thusly separated reagent to step (a) to provide at least part of said reagent of said mixture; and recycling said thusly separated acid of said reagent to step (d) to provide at least part of said acid of said reagent required for step (d).
32. The process of claim 27 wherein step (d) is conducted at a pH of about 4.7 to about 5.5 and said precipitated isomerized aromatic carboxylic acid is terephthalic acid.
33. The process of claim 27 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
34. A process for producing isomerized aromatic carboxylic acid from aromatic materials comprising:
a. treating a mixture of i. an aromatic material, ii. water, and iii. a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, with oxygen under conditions sufficient to convert at least a portion of said aromatic material to an aromatic carboxylic acid salt of said reagent;
b. removing sufficient water from said mixture from step (a) so that said aromatic carboxylic acid salt in said mixture can be isomerized;

c. forming an isomerized aromatic carboxylic acid salt from said aromatic carboxylic acid salt by heating said mixture from step (b) to a temperature suffi-ciently high in the presence of a catalyst;
d. treating said mixture from step (c) with an acid of said reagent to convert at least a portion of said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and said reagent, and to precipitate said isomerized aromatic carboxylic acid;
e. separating said isomerized aromatic carboxylic acid formed in step (d) from said mixture from step (d), thereby forming a first stream containing the thusly separated isomerized aromatic carboxylic acid and a second stream comprising said reagent and said acid of said reagent;
f. separating said acid of said reagent from said reagent;
g. recycling said thusly separated reagent from step (f) to step (a) to provide at least part of said reagent of said mixture; and h. recycling said thusly separated acid of said reagent from step (f) to step (d) to provide at least part of said acid of said reagent required for step (d).
35. The process of claim 34 wherein said aromatic material is coal.
36. The process of claim 34 wherein said aromatic material is bituminous coal.
37. The process of claim 34 wherein said reagent is potassium acetate.
38. The process of claim 34 wherein said catalyst is cadmium benzoate.
39. The process of claim 34 wherein said catalyst is cadmium iodide.
40. The process of claim 34 wherein step (d) is conducted at a pH of about 4.7 to about 5.5 and said precipitated isomerized aromatic carboxylic acid is terephthalic acid.
41. The process of claim 34 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
42. A process for producing isomerized aromatic carboxylic acid from bituminous coal comprising:
a. treating a mixture of i. bituminous coal, ii. water, and iii. potassium acetate, with oxygen under conditions sufficient to convert at least a portion of said bituminous coal to a potassium aromatic carboxylate;

b. removing sufficient water from said mixture from step (a) so that said potassium aromatic carboxylate in said mixture can be isomerized;

c. forming an isomerized potassium aromatic carboxylate from said potassium aromatic carboxylate by heating said mixture from step (b) to a temperature suffi-ciently high in the presence of a catalyst;
d. treating said mixture from step (c) with acetic acid to convert at least a portion of said isomerized potassium aromatic carboxylate to isomerized aromatic carboxylic acid, and said potassium acetate, and to precipitate said isomerized aromatic carboxylic acid;
e. separating said isomerized aromatic carboxylic acid formed in step (d) from said mixture from step (d), thereby forming a first stream containing the thusly separated isomerized aromatic carboxylic acid and a second stream comprising said potassium acetate and said acetic acid;
f. separating said acetic acid from said potassium acetate;
g. recycling said thusly separated potassium acetate from step (f) to step (a) to provide at least part of said potassium acetate of said mixture; and h. recycling said thusly separated acetic acid from step (f) to step (d) to provide at least part of said acetic acid required for step (d).
43. The process of claim 42 wherein said catalyst is cadmium benzoate.
44. The process of claim 42 wherein said catalyst is cadmium iodide.
45. The process of claim 42 wherein step (d) is conducted at a pH of about 4.7 to about 5.5 and said precipitated isomer-ized aromatic carboxylic acid is terephthalic acid.
46. The process of claim 42 wherein carbon dioxide is formed in step (a) and further comprising removing a gas stream comprising carbon dioxide from said mixture in step (a).
47. In a process for producing isomerized aromatic carboxylic acid from aromatic material wherein carbonaceous material is oxidized in an aqueous-caustic environment to produce an aromatic carboxylic acid salt and the aromatic carboxylic acid salt is isomerized in the presence of a catalyst, the improvement which comprises oxidizing an aromatic material in the presence of a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, to form an aromatic carboxylic acid salt of said reagent;
and isomerizing said aromatic carboxylic acid salt produced by the oxidation of the aromatic material in the presence of said reagent without treating said aromatic carboxylic acid salt, or converting said salt to its aromatic carboxylic acid and treating, with a compound which contains a Group Ia or IIa metal prior to isomerization.
48. The process of claim 47 wherein said aromatic material is coal.
49. The process of claim 47 wherein said reagent is potassium acetate.
50. The process of claim 47 further comprising separating said isomerized aromatic carboxylic acid formed from said reagent.
51. The process of claim 50 further comprising recycling said reagent to provide at least part of said reagent used during oxidation of said aromatic material.
52. The process of claim 50 wherein said reagent after separating from said isomerized aromatic carboxylic acid is in a mixture which comprises said acid of said reagent, and further comprising treating said isomerized aromatic carboxylic acid salt with an acid of said reagent to convert at least a portion of said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and said reagent, and to precipitate said isomerized aromatic carboxylic acid; separating said acid of said reagent from said reagent; recycling said thusly separated reagent to provide at least part of said reagent used during oxidation of said aromatic material; and recycling said thusly separated acid of said reagent to provide at least part of said acid of said reagent required for precipitating said isomerized aromatic carboxylic acid.
53. The process of claim 52 wherein said treating of said isomerized aromatic carboxylic acid salt with an acid of said reagent is conducted at a pH of about 4.7 to about 5.5 and said precipitated isomerized aromatic carboxylic acid is terephthalic acid.
54. In a process for producing isomerized aromatic carboxylic acid from aromatic material wherein carbonaceous material is oxidized in an aqueous-caustic environment to produce an aromatic carboxylic acid salt and the aromatic carboxylic acid salt is isomerized in the presence of a catalyst, the improvement which comprises oxidizing an aromatic material in the presence of a water soluble reagent comprising a Group Ia or IIa metal formate, acetate, or propionate, said reagent producing an alkaline solution by hydrolysis, to form an aromatic carboxylic acid salt of said reagent;
and isomerizing said aromatic carboxylic acid salt produced by the oxidation of the aromatic material in the presence of said reagent without converting said aromatic carboxylic acid salt to aromatic carboxylic acid and treating said aromatic carboxylic acid with a compound which contains a Group Ia or IIa metal prior to isomerization.
55. The process of claim 54 wherein said aromatic material is coal.
56. The process of claim 54 wherein said reagent is potassium acetate.
57. The process of claim 54 further comprising separating said isomerized aromatic carboxylic acid formed from said reagent.
58. The process of claim 57 further comprising recycling said reagent to provide at least part of said reagent used during oxidation of said aromatic material.
59. The process of claim 57 wherein said reagent after separating from said isomerized aromatic carboxylic acid is in a mixture which comprises said acid of said reagent, and further comprising treating said isomerized aromatic carboxylic acid salt with an acid of said reagent to convert at least a portion of said isomerized aromatic carboxylic acid salt to isomerized aromatic carboxylic acid, and said reagent, and to precipitate said isomerized aromatic carboxylic acid; separating said acid of said reagent from said reagent; recycling said thusly separated reagent to provide at least part of said reagent used during oxidation of said aromatic material; and recycling said thusly separated acid of said reagent to provide at least part of said acid of said reagent required for precipitating said isomerized aromatic carboxylic acid.
60. The process of claim 59 wherein said treating of said isomerized aromatic carboxylic acid salt with an acid of said reagent is conducted at a pH of about 4.7 to about 5.5 and said precipitated isomerized aromatic carboxylic acid is terephthalic acid.
61. The process of claim 25 wherein said reagent comprises potassium carbonate.
62. The process of claim 25 wherein said reagent comprises potassium bicarbonate.
63. The process of claim 25 wherein said isomerized potassium aromatic carboxylic acid salt comprises dipotassium terephthalate and wherein said dipotassium terephthalate is treated in an aqueous solution with carbon dioxide to produce an acid potassium terephthalate and potassium bicarbonate, said acid potassium terephthalate is converted to terephthalic acid, and said potassium bicarbonate is used as said potassium reagent.
64. The process of claim 63 wherein said acid potassium terephthalate is converted to terephthalic acid by treatment with carbon dioxide.
65. The process of claim 63 wherein said acid potassium terephthalate is converted to terephthalic acid by hydrolyzing with water.
66. The process of claim 23 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid.
67. The process of claim 27 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid
68. The process of claim 34 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid.
69. The process of claim 42 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid.
70. The process of claim 47 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid.
71. The process of claim 54 wherein said isomerized aromatic carboxylic acid comprises terephthalic acid.
CA000322657A 1978-03-06 1979-03-02 Process for producing carboxylic acids and aromatic carboxylic acids Expired CA1120055A (en)

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Cited By (3)

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CN113924282A (en) * 2019-06-12 2022-01-11 诺力昂化学品国际有限公司 Process for separating carboxylic acids from aqueous sidestreams
US11976034B2 (en) 2019-06-12 2024-05-07 Nouryon Chemicals International B.V. Process for the production of diacyl peroxides
US11976035B2 (en) 2019-06-12 2024-05-07 Nouryon Chemicals International B.V. Process for the production of diacyl peroxides

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN113924282A (en) * 2019-06-12 2022-01-11 诺力昂化学品国际有限公司 Process for separating carboxylic acids from aqueous sidestreams
CN113924282B (en) * 2019-06-12 2023-09-12 诺力昂化学品国际有限公司 Process for separating carboxylic acid from aqueous side stream
US11976034B2 (en) 2019-06-12 2024-05-07 Nouryon Chemicals International B.V. Process for the production of diacyl peroxides
US11976035B2 (en) 2019-06-12 2024-05-07 Nouryon Chemicals International B.V. Process for the production of diacyl peroxides

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