CA1145738A - Recovery of heavy-metal oxidation catalyst from the written dmt process for reuse thereof - Google Patents
Recovery of heavy-metal oxidation catalyst from the written dmt process for reuse thereofInfo
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- CA1145738A CA1145738A CA000366654A CA366654A CA1145738A CA 1145738 A CA1145738 A CA 1145738A CA 000366654 A CA000366654 A CA 000366654A CA 366654 A CA366654 A CA 366654A CA 1145738 A CA1145738 A CA 1145738A
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- heavy
- cobalt
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/40—Regeneration or reactivation
- B01J31/4015—Regeneration or reactivation of catalysts containing metals
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J23/00—Catalysts comprising metals or metal oxides or hydroxides, not provided for in group B01J21/00
- B01J23/90—Regeneration or reactivation
- B01J23/92—Regeneration or reactivation of catalysts comprising metals, oxides or hydroxides provided for in groups B01J23/02 - B01J23/36
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/02—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides
- B01J31/04—Catalysts comprising hydrides, coordination complexes or organic compounds containing organic compounds or metal hydrides containing carboxylic acids or their salts
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J31/00—Catalysts comprising hydrides, coordination complexes or organic compounds
- B01J31/40—Regeneration or reactivation
- B01J31/4015—Regeneration or reactivation of catalysts containing metals
- B01J31/4023—Regeneration or reactivation of catalysts containing metals containing iron group metals, noble metals or copper
- B01J31/403—Regeneration or reactivation of catalysts containing metals containing iron group metals, noble metals or copper containing iron group metals or copper
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/39—Preparation of carboxylic acid esters by oxidation of groups which are precursors for the acid moiety of the ester
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- B01J2231/00—Catalytic reactions performed with catalysts classified in B01J31/00
- B01J2231/70—Oxidation reactions, e.g. epoxidation, (di)hydroxylation, dehydrogenation and analogues
-
- 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
- Y02P20/584—Recycling of catalysts
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Catalysts (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Treatment Of Water By Ion Exchange (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE:
According to the present invention there is in general provided a process for the recovery of an oxidation catalyst heavy-metal component from a high-boiling distillation residue obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component, the heavy-metal component being a member of the group consisting of cobalt, manganese, nickel and mixtures thereof, which comprises providing an aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said extract containing as acid, one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms and (a) treating the aqueous acidic extract with a strongly acidic cation exchange resin in the alkali metal ion form, optionally at an elevated temperature, until the exchange capacity has been reached and (b) subsequently washing the cation exchange resin with a suitable washing liquid, optionally at an elevated temperature , and (c) regenerating the cation exchange resin, e.g. at room temperature, for example, with an aqueous solution containing a member of the group consisting of mono-carboxylic acids having 1 to 4 carbon atoms (e.g. acetic acid, formic acid etc.), alkali metal salts of said carboxylic acids (e.g. Na+ or K+ acetate) and mixtures thereof, to displace said heavy-metal component and recover as product an aqueous solution containing said heavy-metal component.
According to the present invention there is in general provided a process for the recovery of an oxidation catalyst heavy-metal component from a high-boiling distillation residue obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component, the heavy-metal component being a member of the group consisting of cobalt, manganese, nickel and mixtures thereof, which comprises providing an aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said extract containing as acid, one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms and (a) treating the aqueous acidic extract with a strongly acidic cation exchange resin in the alkali metal ion form, optionally at an elevated temperature, until the exchange capacity has been reached and (b) subsequently washing the cation exchange resin with a suitable washing liquid, optionally at an elevated temperature , and (c) regenerating the cation exchange resin, e.g. at room temperature, for example, with an aqueous solution containing a member of the group consisting of mono-carboxylic acids having 1 to 4 carbon atoms (e.g. acetic acid, formic acid etc.), alkali metal salts of said carboxylic acids (e.g. Na+ or K+ acetate) and mixtures thereof, to displace said heavy-metal component and recover as product an aqueous solution containing said heavy-metal component.
Description
11~5738 The present invention ~elates to a process for the recovery of an oxidation catalyst heavy-metal component from a high-boiling distillation residue obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component, the heavy-metal component being a member of the group consisting of cobalt, manganese, nickel and mixtures thereof wherein an aqueous acidic extract containing said heavy-metal component is obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said aqueous extract containing as acid, for example, a member of the group consisting of mineral acids and aliphatic mono-carboxylic acids, the latter containing for example 1 to 4 carbon atoms.
In particular, the invention concerns a process for the recovery and reuse of heavy-metal oxidation catalyst from the Witten DMT process, starting with high-boiling distillation residues having a cobalt content of 1 to 10 g/kg residue and in some cases a manganese content of 0.1 to 5 g/kg residue and/or a nickel content of 0.1 to 5 g/kg residue, obtained in the.
oxidation of mixtures containing p-xylene (PX) and/or methyl p-toluate (PTE) in the liquid phase with (preferably 4 to 8 bar) an oxygen-containing gas under elevated pressure for example a pressure of 4 to 10 bar preferably 4 to 8 bar and at an elevated temperature, for example 140 to 200C, preferably a temperature of 140 to 170C in the ~resence of dlssolved heavy-metal oxidation catalyst, subsequent esterificatlon of the : oxidation product with methanol under elevated pressure, for example a pressure of 20 to 30 bar and at elevated temperature, for example a temperature of 230 to 280C, and separation of ~45~31!3 the esterification product by distillation into a fraction rich in methyl p-toluate (PTE), a fraction rich in dimethyl terephthalate (DMT), and a high-boiling distillation residue, by extraction of the heavy-metal oxidation catalyst with water, dilute aqueous mineral acids, aqueous, low-molecular weight aliphatic monocarboxylic acids, or alcohols, under heating, optionally after combustion of the high-boiling distillation residues and dissolving the heavy-metal oxidation catalyst in the combustion residue (ash) with mineral acids.
DMT is required as raw material for the production of polyester by reaction with ethylene glycol or tetramethyl-ene glycol for fibers, filaments, films, or molded components.
DMT is manufactured in numerous large-scale technical plants in accordance with the method which has become known as the Witten process or also the Witten-Hercules process.
Technically, the process is conducted by reacting the PX- and PTE-containing mixture, in the absence of solvents and halogen compounds, in the presence of cobalt compounds and manganese compounds dissolved in the reaction mixture, to an oxidized product consisting predominantly of p-toluic acid (PTA), monomethyl terephthalate (MMT), and terephthalic acid (TPA), and esterifying the oxidized product at 230 to 280C
and 20 to 30 bar with methanol. The heavy-metal oxidation catalyst system is preferably employed in amounts, based on the quantity of oxidized product and converted to the metal content, of about 70 to 200 ppm cobalt and 2 to 100 (for example 7 to 100) ppm manganese. The esterification product is separated in a so-called raw ester distillation into a fraction rich in PTE, a fraction rich in DMT, as well as into a high-boiling distillation residue, by means of a distillation step. The fraction rich in PTE is introduced into the oxidation stage, the fraction rich in DMT is passed on to subsequent purification and working-up stages. The high-boiling residue contains, in addition to the organic components, compounds of the heavy-metal oxidation catalyst system, e.g. cobalt and manganese.
It is technical feasible to feed high-boiling distillation residues of the oxidation of alkyl aromatics, from which no further useful products can be recovered any longer, be it by means of isolation or by means of conversion, to a combustion stage, optionally while utilizing the heat of combustion, and to separate the heavy-metal-containing ashes present in the flue gases of the combustion process by means of cyclones or electrostatic filters (see United States Patent 3,341,470).
The heavy metal content of ashes of the aforementioned type is composed of the catalyst components still existing in the high-boiling distillation residues insofar as they have not been removed previously, for example by an extraction, furthermore of the materials of the production plant, due to corrosion, as well as of the components of the added fuels of the residue combustion. e.g. mazut or heavy fuel oil.
Ashes of the above-mentioned type can be treated with mineral acids, and the heavy metals can be precipitated as carbonates or hydroxides from the solutions (see DOS ~German Unexamined Laid-Open Application~ 2,260,498). In ~-OS
22 60 498 (German Unexamined Laid-Open Application) a process is disclosed for the recovery of cobalt and manganese compounds out of residues of the production of aromatic carbonic acids, which residues are still containing iron and copper compounds, by, among other measures, extraction with dilute sulfuric acid and precipitating and separating, after stepwise raising the pH, iron hydroxide and the carbonates of cobalt and manganese.
However, technical difficulties are encountered in the separation of such precipitates by filtration or centrifuging, as well as in the removal of the adhering, corresponding mineral acid by washing out of the filter cake. The complete removal of the inorganic mineral acid residues is one of the prerequisites for reusing the heavy metals stemming from the high-boiling distillation residues as oxidation catalysts in the oxidation of alkyl aromatics in the liquid phase with atmospheric oxy-gen.
The invention furthermore presupposes that heavy-metal components, such as, for example, iron, chromium, vanadium, molybdenum, copper, and titanium are enriched in such ashes from the combustion of high-boiling distillation residues of the manufacturing process for alkyl aromatics by oxidation in the liquid phase in the presence of heavy-metal oxidation catalysts, which components for example stem from the materials of the manufacturing plant and from the fuels for the residue combustion, and which considerably reduce and/or inhibit the activity of the cobalt, manganese, or nickel catalyst and/or mixtures thereof when recycled into the oxi-dation reaction (of the Witten Process).
It would be extraordinarily advantageous to be able to recover oxidation catalyst components e.g., a mixture of cobalt and manganese and/or nickel components from the high-boiling residue, optionally after combustion of the residue, and reuse these catalyst components for the oxidation of, for example, PX and PTE.
It would be advantageous to be able to recover from the distillation residues of the raw ester distillation, catalyst components and to make available directly aqueous solutions suitable for use in the oxidation or for some other utilization of the valuable catalyst components from the extract, without evaporation or any additional measures necessary due to the presence for example of TMA and TMME.
The present invention thus relates to a p~ocess to obtaining, from the acidic extracts or fxom.the mineral acidic solutions a catalyst regenerate extensively free of interfering organic components, especially TMA and TMME, furthermore extensi-vely free of metal compounds from the materials of the manufactu-ring plant e.g. ensuing from corrosion.
According to the present invention there is in general provided a process for the recovery of a heavy-metal oxidati.on catalyst component from a high-boiling distillation residue , said heavy-metal component being selected from the group consis-ting of cobalt, cobalt and manganese, cobalt and nickel, and cobalt, manganese and nickel, said residue being obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component as defined above,which comprises providing a suitable aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation. residue or - from the ash obtained on combustion of said high-boiling distil-lation residue, said extract containing as acid one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms and ~ A) trcati.ng thc aqucous acidi.c cxtract with a strongly acidic cation exchange resin in the alkali metal ion form, optionally at an elevated temperature, until the exchange capacity has been reached and (b) subsequently washing the cation exchange resin ~, .
~l~S738 with a suitable washing liquid, optiona~lly a-t an elevated t.emperature , and regenerati~g the cation exchange resin, e.y.
at room.temperature, with an aqueous solution containing at least one salt selected from the group consisting of alkali metal salts of low-molecular aliphatic monocarboxylic acids having 1 to 4 carbon atoms (e.g. Na+ or K acetate and mixtures thereof) to displace said heavy-metal component and recover as product an aqueous solution containing said heavy-metal compo-nent. If desired, the aqueous regenerating solution may also contain one or more acids selected from the group consisting of low-molecular aliphatic monocarboxylic acids having 1 to 4 carbon ~toms (e.g. acetic or formic acid).
In accordance with the present invention, the acidic extract treated in step (a) may be obtained by extraction of the heavy-metal component from said high-boiling distillation residue with an aqueous acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, under heating.
~ lso, in accordance with the present invention, the acidic extract treated in step (a) may be obtained by extracting the ashes obtained after combustion of said high-boiling distil-lation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids, with the addition of an oxidizing agent under heating, subsequently diluting with water, increasing the pH of the diluted extract by adding a suitable alkali metal hydroxide to precipitate any iron and chromium as the hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate with an acid, said acid being a low-molecular aliphatic mono-carboxylic acid of 1 to 4 carbon atoms or a mixture thereof, and removal of the alkali metal ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2 , Mn2 and/or Ni2 io~s.
In accordance with a particular embodiment of the present invention, the aqueous acidic extract treated in step (a) is obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with aqueous hydro-chloric acid with the addition of aqueous H2O2 at about 95C
for a duration of 0.1 to 4 hours, subsequently diluting with water, increasing the pH of the diluted extract to a value of at least 6 by adding NaOH and heating at about 95C for 0.1 to
In particular, the invention concerns a process for the recovery and reuse of heavy-metal oxidation catalyst from the Witten DMT process, starting with high-boiling distillation residues having a cobalt content of 1 to 10 g/kg residue and in some cases a manganese content of 0.1 to 5 g/kg residue and/or a nickel content of 0.1 to 5 g/kg residue, obtained in the.
oxidation of mixtures containing p-xylene (PX) and/or methyl p-toluate (PTE) in the liquid phase with (preferably 4 to 8 bar) an oxygen-containing gas under elevated pressure for example a pressure of 4 to 10 bar preferably 4 to 8 bar and at an elevated temperature, for example 140 to 200C, preferably a temperature of 140 to 170C in the ~resence of dlssolved heavy-metal oxidation catalyst, subsequent esterificatlon of the : oxidation product with methanol under elevated pressure, for example a pressure of 20 to 30 bar and at elevated temperature, for example a temperature of 230 to 280C, and separation of ~45~31!3 the esterification product by distillation into a fraction rich in methyl p-toluate (PTE), a fraction rich in dimethyl terephthalate (DMT), and a high-boiling distillation residue, by extraction of the heavy-metal oxidation catalyst with water, dilute aqueous mineral acids, aqueous, low-molecular weight aliphatic monocarboxylic acids, or alcohols, under heating, optionally after combustion of the high-boiling distillation residues and dissolving the heavy-metal oxidation catalyst in the combustion residue (ash) with mineral acids.
DMT is required as raw material for the production of polyester by reaction with ethylene glycol or tetramethyl-ene glycol for fibers, filaments, films, or molded components.
DMT is manufactured in numerous large-scale technical plants in accordance with the method which has become known as the Witten process or also the Witten-Hercules process.
Technically, the process is conducted by reacting the PX- and PTE-containing mixture, in the absence of solvents and halogen compounds, in the presence of cobalt compounds and manganese compounds dissolved in the reaction mixture, to an oxidized product consisting predominantly of p-toluic acid (PTA), monomethyl terephthalate (MMT), and terephthalic acid (TPA), and esterifying the oxidized product at 230 to 280C
and 20 to 30 bar with methanol. The heavy-metal oxidation catalyst system is preferably employed in amounts, based on the quantity of oxidized product and converted to the metal content, of about 70 to 200 ppm cobalt and 2 to 100 (for example 7 to 100) ppm manganese. The esterification product is separated in a so-called raw ester distillation into a fraction rich in PTE, a fraction rich in DMT, as well as into a high-boiling distillation residue, by means of a distillation step. The fraction rich in PTE is introduced into the oxidation stage, the fraction rich in DMT is passed on to subsequent purification and working-up stages. The high-boiling residue contains, in addition to the organic components, compounds of the heavy-metal oxidation catalyst system, e.g. cobalt and manganese.
It is technical feasible to feed high-boiling distillation residues of the oxidation of alkyl aromatics, from which no further useful products can be recovered any longer, be it by means of isolation or by means of conversion, to a combustion stage, optionally while utilizing the heat of combustion, and to separate the heavy-metal-containing ashes present in the flue gases of the combustion process by means of cyclones or electrostatic filters (see United States Patent 3,341,470).
The heavy metal content of ashes of the aforementioned type is composed of the catalyst components still existing in the high-boiling distillation residues insofar as they have not been removed previously, for example by an extraction, furthermore of the materials of the production plant, due to corrosion, as well as of the components of the added fuels of the residue combustion. e.g. mazut or heavy fuel oil.
Ashes of the above-mentioned type can be treated with mineral acids, and the heavy metals can be precipitated as carbonates or hydroxides from the solutions (see DOS ~German Unexamined Laid-Open Application~ 2,260,498). In ~-OS
22 60 498 (German Unexamined Laid-Open Application) a process is disclosed for the recovery of cobalt and manganese compounds out of residues of the production of aromatic carbonic acids, which residues are still containing iron and copper compounds, by, among other measures, extraction with dilute sulfuric acid and precipitating and separating, after stepwise raising the pH, iron hydroxide and the carbonates of cobalt and manganese.
However, technical difficulties are encountered in the separation of such precipitates by filtration or centrifuging, as well as in the removal of the adhering, corresponding mineral acid by washing out of the filter cake. The complete removal of the inorganic mineral acid residues is one of the prerequisites for reusing the heavy metals stemming from the high-boiling distillation residues as oxidation catalysts in the oxidation of alkyl aromatics in the liquid phase with atmospheric oxy-gen.
The invention furthermore presupposes that heavy-metal components, such as, for example, iron, chromium, vanadium, molybdenum, copper, and titanium are enriched in such ashes from the combustion of high-boiling distillation residues of the manufacturing process for alkyl aromatics by oxidation in the liquid phase in the presence of heavy-metal oxidation catalysts, which components for example stem from the materials of the manufacturing plant and from the fuels for the residue combustion, and which considerably reduce and/or inhibit the activity of the cobalt, manganese, or nickel catalyst and/or mixtures thereof when recycled into the oxi-dation reaction (of the Witten Process).
It would be extraordinarily advantageous to be able to recover oxidation catalyst components e.g., a mixture of cobalt and manganese and/or nickel components from the high-boiling residue, optionally after combustion of the residue, and reuse these catalyst components for the oxidation of, for example, PX and PTE.
It would be advantageous to be able to recover from the distillation residues of the raw ester distillation, catalyst components and to make available directly aqueous solutions suitable for use in the oxidation or for some other utilization of the valuable catalyst components from the extract, without evaporation or any additional measures necessary due to the presence for example of TMA and TMME.
The present invention thus relates to a p~ocess to obtaining, from the acidic extracts or fxom.the mineral acidic solutions a catalyst regenerate extensively free of interfering organic components, especially TMA and TMME, furthermore extensi-vely free of metal compounds from the materials of the manufactu-ring plant e.g. ensuing from corrosion.
According to the present invention there is in general provided a process for the recovery of a heavy-metal oxidati.on catalyst component from a high-boiling distillation residue , said heavy-metal component being selected from the group consis-ting of cobalt, cobalt and manganese, cobalt and nickel, and cobalt, manganese and nickel, said residue being obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component as defined above,which comprises providing a suitable aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation. residue or - from the ash obtained on combustion of said high-boiling distil-lation residue, said extract containing as acid one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms and ~ A) trcati.ng thc aqucous acidi.c cxtract with a strongly acidic cation exchange resin in the alkali metal ion form, optionally at an elevated temperature, until the exchange capacity has been reached and (b) subsequently washing the cation exchange resin ~, .
~l~S738 with a suitable washing liquid, optiona~lly a-t an elevated t.emperature , and regenerati~g the cation exchange resin, e.y.
at room.temperature, with an aqueous solution containing at least one salt selected from the group consisting of alkali metal salts of low-molecular aliphatic monocarboxylic acids having 1 to 4 carbon atoms (e.g. Na+ or K acetate and mixtures thereof) to displace said heavy-metal component and recover as product an aqueous solution containing said heavy-metal compo-nent. If desired, the aqueous regenerating solution may also contain one or more acids selected from the group consisting of low-molecular aliphatic monocarboxylic acids having 1 to 4 carbon ~toms (e.g. acetic or formic acid).
In accordance with the present invention, the acidic extract treated in step (a) may be obtained by extraction of the heavy-metal component from said high-boiling distillation residue with an aqueous acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, under heating.
~ lso, in accordance with the present invention, the acidic extract treated in step (a) may be obtained by extracting the ashes obtained after combustion of said high-boiling distil-lation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids, with the addition of an oxidizing agent under heating, subsequently diluting with water, increasing the pH of the diluted extract by adding a suitable alkali metal hydroxide to precipitate any iron and chromium as the hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate with an acid, said acid being a low-molecular aliphatic mono-carboxylic acid of 1 to 4 carbon atoms or a mixture thereof, and removal of the alkali metal ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2 , Mn2 and/or Ni2 io~s.
In accordance with a particular embodiment of the present invention, the aqueous acidic extract treated in step (a) is obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with aqueous hydro-chloric acid with the addition of aqueous H2O2 at about 95C
for a duration of 0.1 to 4 hours, subsequently diluting with water, increasing the pH of the diluted extract to a value of at least 6 by adding NaOH and heating at about 95C for 0.1 to
2 hours to precipitate any iron and chromium as hydroxides, filte-ring to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate to pH 5 or below with acetic acid, and removal of the Na ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2 , Mn2 and/or Ni2 ions. F
German Patent Application P 29 23 681 suggests a process for the recovery of oxidation catalyst from the catalyst-containing distillation residue obtained in DMT production, and for the reuse of the thus-recovered catalyst in the oxidation, with the objective of maintaining the selectivity of the oxida-tion at the same high level as in case of using fresh catalyst.
It has been demonstrated therein that, in the extraction of the catalyst-containing distillation residue from the raw ester distillation, trimellitic acid (TMA) and the monomethyl ester of r trimellitic acid (TMME) are dissolved together with the catalyst, and that TMA and TMME can considerably impair the course of the oxidation reaction when recycled into the oxidation with the catalyst. For this reason, in the aforementioned process, the r quantitative ratio of TMA + TMME to the heavy-metal oxidation catalyst in the extract is set at a value of at most 1.8: 1.
According to the in~entio~, the content of T~A and TMME in the extract frcm the distillation residue can be higher by a multiple, for example fivefold, than the content of cobalt-manganese, and thus can amount to almost three times the ratio of TMA + TMME to the heavy-metal oxidation catalyst admitted in Patent Application P 29 23 681.
The content of TMA and TMME in the extract is dependent on the type of raw ester processing and thus on the chemical composition of the high-boiling distillation residue.
With an increasing concentration of TMA and TMME in the extract, a raised consumption of heavy-metal oxidation catalyst is required to ensure a flawless progression of the oxidation reaction upon a recycling of the extracted catalyst.
Furthermore, the invention permits the recovery and reuse of cobaIt compounds or cobalt and manganese compounds in conjunction with nickel compounds.
According to the present invention a process of the above-indicated type, can be characterized in more particular ~ -embodiments by i, (a) treating an aqueous,acidic extract, which contains the heavy-metal component and has a cobalt content of 0.2 to 20 g/l, also in some cases a manganese content of 0.05 to lO g/l, and/or also in some cases a nickel content of 0.05 to lO g/l, with a strongly acidic cation exchange resin in the alkali metal form, e.g. Na or K form, optionally at an elevated temperature until the exchange capacity has been reached, and subsequently (b) washing thc cation cxchanc3c rcsin, for cx~mpl~
with water, optionally, at an elevated temperature and regenere-ting the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na or K acetate, thus displacing the heavy metal component and obtaining an aqueous ~D
acetic acid solution containing said heav~-~etal component.
Thus, the present inventio~ provides a process for the recovery of a heavy-metal oxidation catalyst solution containing a heavy-metal component as defined above, from a high-boiling distillation residue having a cobalt content of 1 to 10 g/kg and in some cases a mangenese content of 0.1 to 5g/kg of residue and/or a nickel content of 0.1 to 5 g/kg of residue, which is obtained in the production of dimethyl terephthalate by the oxidation of mixtures containing p-xylene and/or methyl p-toluate in the liquid phase with oxygen or an oxygen-containing gas under a pressure of 4 to 10 bar and at a temperature of 140 to 200C in the presence of dissolved heavy-metal oxidation catalyst having a heavy-metal component as defined above, subsequent esterification of the oxidation product with methanol under a pressure of 20 to 30 bar and at a temperature of 230 to 280C, and distillatory separation of the esterification product into a fraction rich in methyl p-toluate, a fraction rich in dimethyl terephthalate, and the high-boiling distillation residue; which comprises providing a suitable aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said extract containing as acid, one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms, and is characterized by (a) treating the aqueous, acidic extract, which contains the heavy-metal component and which can have a cobalt content of 0.2 to 20 g/l, in some cases a manganese content of ~
0.05 to 10 g/l, and/or in some cases a nickel content of 0.05 to r 10 g/l, with a strongly acidic cation exchange resin in the alkali metal form, e.g. Na or K form, optionally at an elevated ~ ) -- g _ ~.~
- ~145738 temperature until the exchange capacity has been reached, and subsequently (b) washing the cation exchange resin, for example with water, optionally at an elevated temperature and regenera-ting *he cation exchange resin at room temperature with an aqueous acetic acid solution containing Na or K acetate, thus displacing the heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
In accordance with the present invention, the aqueous acidic extract can be provided as lndicated above by extracting the heavy-metal component from the residue with a suitable monocarboxylic acid. Alternatively, the aqueous acidic extract can be obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids, with the addition of an oxidizing agent under heating, subsequently ~ -diluting with water , increasing the pH of the diluted extract by adding NaOH to precipitate any iron and chromium as the t hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble components, effecting dilution with water, then effecting acidification of the filtrate with acetic acid, removal of the Na ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2 , Mn2 and/or Ni2+ ions. F
The type of ion-exchanger used for the invention r can be based on polystyrene copolymerized with divinylbenzene and crosslinked. Thc activc groups arc bound sulfonic acid-(HSO3-) groups. Suitable acidic cation exchange resins for use in the in~ention are Lewatit* S 100, Amberlite* IR 120, r Dowex * 50.
* Trade marks - 9a -~ . - .
..
1~5738 The temperatures used during the eXchange tre~tment and the washing step preferably are between 10C and 90C.
By means of the working up of the combustion products stemming from the high-boiling distillation residues, in accordance with this invention, it is possible in a simple way to obtain an aqueous organic catalyst solution which is free of mineral acid residues and free of impurities e.g.
TMA and TMME, inhibiting the activity of the catalyst components.
The thus obtained aqueous catalyst solutions can contain cobalt acetate and manganese acetate with a content of about 5 to 70 g/l of cobalt, 1 to 35 g/l of manganese, and in some cases nickel acetate with a content of about 1 to 35 g/l of nickel. These aqueous solutions, containing the catalyst components for example as the acetates, are advantegeously recycled directly into the oxidation of the mixtures containing p-xylene and/or methyl p-toluate.
The ion exchanger for absorbing the heavy-metal component is in the alkali metal form and preferably in the sodium or potassium form.
Preferably, the exchanger, loaded with catalyst metal ions, is regenerated with dilute aqueous sodium acetate solu-tions, because with the strongly acidic ion exchangers used according to the invention the egeneration equilibrium i R-(Co ) + 2 Na < ~ R-(Na )2 + Co as compared to the regeneration equilibrium R-(Co ) + 2 H ~ _ > R-(H )2 + Co wherein R means the stationary ion exchange matrix,is oriented more into the direction of the right-hand side of the reaction equation.
By means of the treatment o~ the obtained extracts on solutions according to this invention with strongly acidic cation exchangers - 9b -ll~S~38 especially resins an upward concentration of the catalyst metal content in the extract to values up to about 20 times the initial concentration i5 made possible in a surprisingly simple way, and in the case of extracting the distillation residue high contents of TMA
and TMME are not interfering, by complex formation, in the exchange of the catalyst metal ions by the counter ion, e.g.
the sodium ion on the cation exchanger (e.g. exchange resin).
. According to the invention, there is no need for concentrating the extract by evaporation which, with increased TMA and TMME concentrations, would lead to losses of catalyst metal by precipitations and sedimentations. Rather, a quan-titative separation of TMA and TMME, as well as other ac-companying organic compounds, is attained in a simple manner.
In view of the disturbances caused by considerable contents of TMA and TMME in the oxidation of mixtures containing PX
and/or PTE, this result is of special value.
The process of this invention can be conducted technically either by extraction of the distillation residue or by combustion of the distillation residue and subsequent processing with aqueous mineral acids and subjecting the solutions so obtained to the further processing as described herein.
In the case of extracting the distillation residue relative amounts by weight of the extracting agent can be in the range of 0.3 : 1 to 5 : 1.
The percentage recovery of the cobalt, manganese and/or nickel present in the high boiling distillation residue depends on the percentage recovery of the extraction step, optionally after combustion of the high-boiling distillation residues.
The percentage recovery of the cobalt, manganese and/or nickel in the combined steps a) and b) according to the inven-~ .
tion is almost 100 %, typically 98 ~ and is ranging betweeen about 95 and 99.9 %.
The total percentage recovery of the cobalt r manganese and/or nickel in the overall process covered by the invention is about 85 to 99 ~.
The process of this invention is conducted technical-ly in a preferred embodiment by cooling the acidic, aqueous extracts from a temperature of about 95C to approximately room temperature, and separating the thus-precipitated organic components. This is followed by reheating to about 70C
to avoid subsequent precipitations. During the following loading of the strongly acidic cation exchanger in the Na form at about 70C, any amounts of organic components, es-pecially TMA, TMME, TPA, MMT, and the like, still present in the extract, are not absorbed on the exchanger but rather remain in the aqueous phase and pass unhindered through the exchanger. In case this wastewater, loaded primarily with alkali metal ions and organic compounds, cannot be passed on to biological processing but rather must be treated thermally, the alkali metal ions can be exchanged by treatment with a strongly acidic cation exchanger in the H+ ion form, and removed by elution with a strong acid, preferably hydrochloric acid, in the form of a neutral salt, e.g. NaCl, in an aqueous solution. Upon reaching the exchange capacity with Co2+
and Mn2+, the loaded exchanger is treated with fully deminer-alized water, likewise heated to about 70C, as the washing liquid. This treatment serves for removing the organic com-ponents absorbed on the exchange resin, which settle as a smeary film on the exchange resin matrix and would considerably reduce the exchange capacity if they were not removed with each cycle. The thus-produced washing water is suitably recycled into the extraction stage.
`-- 1145738 During the subsequent regeneration, conducted at room temperature, about two bed volumes of an aqueous sodium acetate solution collected during the preceding regeneration cycle as the last runnings and having been combined with the forerunnings of the preceding regenerating cycle are introduced to the exchanger, loaded with Co2+ and Mn2+, the bed volume of which is initially filled with fully demineralized washing water. About 50~ of the bed volume is withdrawn as a solution free of Co2+/mn2+. Subsequently, about 15% of the bed volume is collected as forerunnings with a low Co2+/Mn2 content.
The next fractions withdrawn is about 135% of the bed volume as a Co2 /Mn2 acetate solution (called concentrate herein-below). For a complete displacement of the catalyst metal components from the exchanger, about 80% of the bed volume of /
.. /
:, /
/
, - ' ~S738 an approximately 15~ aqueous sodium acetate solution containing about 10 to 15 g/l of free acetic acid is introduced onto the exchanger, and thereafter about 80% of the bed volume of fully demineralized water is fed onto the exchanger, in order to remove the sodium acetate solution which contains Co and ~n ions. The thus-obtained solutions, amounting in total to about 160% of the bed volume, are withdrawn, until a pronounced reduction in the Co2+/Mn2+ concentration, in an amount of about 5-10% of the bed volume, and combined with the concentrate, and the subsequent fractions in an amount of about 150 to 155%
of the bed volume are discharged as the last runnings, combined with the previously obtained forerunnings, and reserved for use in the following regenerating cycle.
In the case of processing the residues from the combustion of the high-boiling distillation residues, which contain heavy metal components including the metals of the oxidation catalyts they are dissolved in mineral acids, e.g.
hydrochloric acid or sulfuric acid with the addition of oxidizing agents, for example a hydrogen peroxide solution or nitric acid to oxidize, inter alia, Fe2 ions . The impurities which have accumulated in the solution and stem from the materials of the plant and the fuels, such as, for instance, iron, chromium, vanadium, molybdenum, copper, and titanium, are then precipitated, by adjusting the solution to a pH of about 6 or thereabove, with a suitable base for example, an alkali metal base (i.e. an aqueous sodium hydroxide solution), in the form of the hydroxides and the precipitates are filtered off together with the insoluble proportions of the residue (ash). The thus-purified solution is adjusted to a pH of 5 or therebelow by adding at least one linear, low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms, for example acetic acid. The ions such as Na contained in ~:~4~738 the solution are removed by treatment wi~h a strongly acidic cation exchange resin loaded with Co , Mn2 and/or Ni2 ions~
The resulting (acetic)-acid- containing heavy metal solution is then treated with a strongly acidic cation exchange resin, e.g. in the Na or K form,until the exchange capacity has been reached, and the cation exchange resin is subsequently washed optionally at an elevated temperature e.g. 50 to 90C and regenerated at room temperature with alkali metal (e.g. Na or K ) acetate-containing solutions, thus displacing the metal ions of the catalyst components and obtaining an aqueous, (e.g. acetic) acid solution which contains the metal ions of the catalyst components.
The following examples serve for a further explana-tion of the invention.
The combustion residue utilized in Examples 3 and 4 was obtained by burning a high-boiling distillation residue from the Witten DMT process at 800-1200C and separation from the flue gases in an electrostatic filter. In this con-nection, 95% by weight of such a residue was combusted with the addition of 5% by weight of heavy fuel oil. The high-boiling distillation residue fed to the combustion contained about 0.1 - 1.0 ~ by weight of ash-forming heavy-metal components.
Example 1 100 kg of distillation residue from the raw ester distillation was extracted with 60 1 of reaction water of the DMT production with an acid content of about 3~, calculated as acetic acid, at about 95C, to a residual Co2 content of 20 ppm; this di~tillation residue was obtained in an industrial plant for DMT production by the combined continuous oxidation of PX- and PTE-containing mixtures in the liquid phase with atmospheric oxygen under 8 bar pressure and at temperatures of 1145~3~3 150 to 170 C with the use of a solution of cobalt acetate and manganese acetate in aqueous acetic acid, a stationary concen-tration of about 90 ppm cobalt and lO ppm manganese being set in the oxidation product; subsequent continuous esterifica-tion of the oxidation product at temperatures of about 250 C
and under 25 bar pressure with methanol; and continuous separa-tion of the esterification product by vacuum distillation, wherein, in a first distillation colunm, a fraction rich in PTE is withdrawn overhead and recycled into the oxidation, and the sump product of this column is separated in a second, subse-quent column into a fraction in DMT, withdrawn overhead, and into a high-boiling distillation residue having a cobalt content of 2.3 g/kg and a manganese content of 0.2 g/kg of residue.
After decanting, 56 l of a Co /Mn -containing extract was obtained having a Co2 content of 3O8 g/l and a Mn2 content of 0.3 g/l. The hot extract was cooled to 20 C
and thus-precipitated organic compounds were separated by filtration.
The filtered solution was heated to 70 C to prevent subsequent precipitation and passed from below through a tube charged with a strongly acidic cation exchanger loaded with Na ions commercially available under the name of "Lewatit S
100." The resin volume was 1.1 1. The loading was continued until theincipient exhaustion of the ion exchange capacity.
From the produced 56 l Co-Mn extract, l9 l,corre-sponding to a total content of 78.4 g Co + Mn + or 2.66 eq.
Co2 , was conducted at 70 C over the cation exchanger.
Subsequently, the cation exchanger was washed with fully demi-neralized water introduced from the top at 70 C. Thereupon, the cation exchanger was eluted from the top with 2.2 l of a 10~ aqueous acetic-acid sodium acetate solution, corresponding 5~3~3 to 1.3 eq. Na ~1, and then a subsequent washing step was conducted with 1 1 of fully demineralized water at room tempera-ture, thus obtaining 0.4 1 of forerunnin~s, 2.0 1 of con-centrate, and 0.8 1 of last runnings.
The forerunnings contained 4.8 g/l Co2 , 0.4 g/l Mn2 and 0.8 g/l CH3COOH.
The last runnings contained 11.2 g/l Co2+, 0.9 g/l Mn2+, 9.5 g/l Na and 6.3 g/l CH3COOH.
The aqueous concentrate contained the following 10 components :
Co2+ = 30~1 g/l Mn2+ = 2.6 g/l Na = 1.0 g/l CH3COOH = 12.0 g/l Organic cannot be detected Impurities (polarographically) ; The thus-obtained Co , Mn containing and the Na containing forerunnings and last runnings, respectively, were combined and utilized again as the eluting solution to avoid Co + and Mn losses.
Example 2 In a continuously operating extraction plant, 300 kg/h of the high-boiling distillation residue of the raw ester distillation obtained as in Example 1 was extracted under agitation at about 95C with 150 kg/h of acidic reac-tion water from the DMT production, the origin and acid content of which were in correspondence with Example 1.
The aqueous solution obtained after separation of the organic phase contained 4.6 g/l of Co2+ and 0.4 g/l of Mn2 . This solution was cooled to about 20C and separated by filtration from the precipitated organic products, which were recycled into the process, and was then collected in a i73~3 container. After heating to about 70 C to avoid subsequent precipitation of organic compounds, 650 l/hOf this solution was conducted at a temperature of 70 C over a column charged with 180 l of a resin loaded with Na+ ions under the commercial name of "Lewatit S 100". The loading of the exchanger was completed after about 3 hours.
Thereafter a flushing step was conducted with 400 1 of hot, demineralized water in order to remove organic compounds. Subsequently, the catalyst ions were eluted at ap-proximately room temperature with a solution containing sodium acetate and with a content of 10 ta 15 g/l of free acetic acid consisting, in part, of the forerunnings and last runnings of the preceding elution as well as a 15% sodium acetate solution.
In total, 515 l of solution was used for eluting pruposes.
After elution, the exchanger was washed with 170 1 of fully demineralized water.
Four fractions were collected: 90 l Co - and Mn -free solution, 35 1 of forerunnings, 240 1 of concentrate, and 320 l of last runnings.
The forerunnings contained 5.8 g/l Co , 0.4 g/l Mn and 1.0 g/l CH3COOH.
The last runnings contained 16.6 g/l Co2 , 1.3 g/l Mn2 , 19.4 g/l Na and 10.8 g/l CH3COOH.
The concentrate contained 37.0 g/l Co and
German Patent Application P 29 23 681 suggests a process for the recovery of oxidation catalyst from the catalyst-containing distillation residue obtained in DMT production, and for the reuse of the thus-recovered catalyst in the oxidation, with the objective of maintaining the selectivity of the oxida-tion at the same high level as in case of using fresh catalyst.
It has been demonstrated therein that, in the extraction of the catalyst-containing distillation residue from the raw ester distillation, trimellitic acid (TMA) and the monomethyl ester of r trimellitic acid (TMME) are dissolved together with the catalyst, and that TMA and TMME can considerably impair the course of the oxidation reaction when recycled into the oxidation with the catalyst. For this reason, in the aforementioned process, the r quantitative ratio of TMA + TMME to the heavy-metal oxidation catalyst in the extract is set at a value of at most 1.8: 1.
According to the in~entio~, the content of T~A and TMME in the extract frcm the distillation residue can be higher by a multiple, for example fivefold, than the content of cobalt-manganese, and thus can amount to almost three times the ratio of TMA + TMME to the heavy-metal oxidation catalyst admitted in Patent Application P 29 23 681.
The content of TMA and TMME in the extract is dependent on the type of raw ester processing and thus on the chemical composition of the high-boiling distillation residue.
With an increasing concentration of TMA and TMME in the extract, a raised consumption of heavy-metal oxidation catalyst is required to ensure a flawless progression of the oxidation reaction upon a recycling of the extracted catalyst.
Furthermore, the invention permits the recovery and reuse of cobaIt compounds or cobalt and manganese compounds in conjunction with nickel compounds.
According to the present invention a process of the above-indicated type, can be characterized in more particular ~ -embodiments by i, (a) treating an aqueous,acidic extract, which contains the heavy-metal component and has a cobalt content of 0.2 to 20 g/l, also in some cases a manganese content of 0.05 to lO g/l, and/or also in some cases a nickel content of 0.05 to lO g/l, with a strongly acidic cation exchange resin in the alkali metal form, e.g. Na or K form, optionally at an elevated temperature until the exchange capacity has been reached, and subsequently (b) washing thc cation cxchanc3c rcsin, for cx~mpl~
with water, optionally, at an elevated temperature and regenere-ting the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na or K acetate, thus displacing the heavy metal component and obtaining an aqueous ~D
acetic acid solution containing said heav~-~etal component.
Thus, the present inventio~ provides a process for the recovery of a heavy-metal oxidation catalyst solution containing a heavy-metal component as defined above, from a high-boiling distillation residue having a cobalt content of 1 to 10 g/kg and in some cases a mangenese content of 0.1 to 5g/kg of residue and/or a nickel content of 0.1 to 5 g/kg of residue, which is obtained in the production of dimethyl terephthalate by the oxidation of mixtures containing p-xylene and/or methyl p-toluate in the liquid phase with oxygen or an oxygen-containing gas under a pressure of 4 to 10 bar and at a temperature of 140 to 200C in the presence of dissolved heavy-metal oxidation catalyst having a heavy-metal component as defined above, subsequent esterification of the oxidation product with methanol under a pressure of 20 to 30 bar and at a temperature of 230 to 280C, and distillatory separation of the esterification product into a fraction rich in methyl p-toluate, a fraction rich in dimethyl terephthalate, and the high-boiling distillation residue; which comprises providing a suitable aqueous acidic extract containing said heavy-metal component, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said extract containing as acid, one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms, and is characterized by (a) treating the aqueous, acidic extract, which contains the heavy-metal component and which can have a cobalt content of 0.2 to 20 g/l, in some cases a manganese content of ~
0.05 to 10 g/l, and/or in some cases a nickel content of 0.05 to r 10 g/l, with a strongly acidic cation exchange resin in the alkali metal form, e.g. Na or K form, optionally at an elevated ~ ) -- g _ ~.~
- ~145738 temperature until the exchange capacity has been reached, and subsequently (b) washing the cation exchange resin, for example with water, optionally at an elevated temperature and regenera-ting *he cation exchange resin at room temperature with an aqueous acetic acid solution containing Na or K acetate, thus displacing the heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
In accordance with the present invention, the aqueous acidic extract can be provided as lndicated above by extracting the heavy-metal component from the residue with a suitable monocarboxylic acid. Alternatively, the aqueous acidic extract can be obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids, with the addition of an oxidizing agent under heating, subsequently ~ -diluting with water , increasing the pH of the diluted extract by adding NaOH to precipitate any iron and chromium as the t hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble components, effecting dilution with water, then effecting acidification of the filtrate with acetic acid, removal of the Na ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2 , Mn2 and/or Ni2+ ions. F
The type of ion-exchanger used for the invention r can be based on polystyrene copolymerized with divinylbenzene and crosslinked. Thc activc groups arc bound sulfonic acid-(HSO3-) groups. Suitable acidic cation exchange resins for use in the in~ention are Lewatit* S 100, Amberlite* IR 120, r Dowex * 50.
* Trade marks - 9a -~ . - .
..
1~5738 The temperatures used during the eXchange tre~tment and the washing step preferably are between 10C and 90C.
By means of the working up of the combustion products stemming from the high-boiling distillation residues, in accordance with this invention, it is possible in a simple way to obtain an aqueous organic catalyst solution which is free of mineral acid residues and free of impurities e.g.
TMA and TMME, inhibiting the activity of the catalyst components.
The thus obtained aqueous catalyst solutions can contain cobalt acetate and manganese acetate with a content of about 5 to 70 g/l of cobalt, 1 to 35 g/l of manganese, and in some cases nickel acetate with a content of about 1 to 35 g/l of nickel. These aqueous solutions, containing the catalyst components for example as the acetates, are advantegeously recycled directly into the oxidation of the mixtures containing p-xylene and/or methyl p-toluate.
The ion exchanger for absorbing the heavy-metal component is in the alkali metal form and preferably in the sodium or potassium form.
Preferably, the exchanger, loaded with catalyst metal ions, is regenerated with dilute aqueous sodium acetate solu-tions, because with the strongly acidic ion exchangers used according to the invention the egeneration equilibrium i R-(Co ) + 2 Na < ~ R-(Na )2 + Co as compared to the regeneration equilibrium R-(Co ) + 2 H ~ _ > R-(H )2 + Co wherein R means the stationary ion exchange matrix,is oriented more into the direction of the right-hand side of the reaction equation.
By means of the treatment o~ the obtained extracts on solutions according to this invention with strongly acidic cation exchangers - 9b -ll~S~38 especially resins an upward concentration of the catalyst metal content in the extract to values up to about 20 times the initial concentration i5 made possible in a surprisingly simple way, and in the case of extracting the distillation residue high contents of TMA
and TMME are not interfering, by complex formation, in the exchange of the catalyst metal ions by the counter ion, e.g.
the sodium ion on the cation exchanger (e.g. exchange resin).
. According to the invention, there is no need for concentrating the extract by evaporation which, with increased TMA and TMME concentrations, would lead to losses of catalyst metal by precipitations and sedimentations. Rather, a quan-titative separation of TMA and TMME, as well as other ac-companying organic compounds, is attained in a simple manner.
In view of the disturbances caused by considerable contents of TMA and TMME in the oxidation of mixtures containing PX
and/or PTE, this result is of special value.
The process of this invention can be conducted technically either by extraction of the distillation residue or by combustion of the distillation residue and subsequent processing with aqueous mineral acids and subjecting the solutions so obtained to the further processing as described herein.
In the case of extracting the distillation residue relative amounts by weight of the extracting agent can be in the range of 0.3 : 1 to 5 : 1.
The percentage recovery of the cobalt, manganese and/or nickel present in the high boiling distillation residue depends on the percentage recovery of the extraction step, optionally after combustion of the high-boiling distillation residues.
The percentage recovery of the cobalt, manganese and/or nickel in the combined steps a) and b) according to the inven-~ .
tion is almost 100 %, typically 98 ~ and is ranging betweeen about 95 and 99.9 %.
The total percentage recovery of the cobalt r manganese and/or nickel in the overall process covered by the invention is about 85 to 99 ~.
The process of this invention is conducted technical-ly in a preferred embodiment by cooling the acidic, aqueous extracts from a temperature of about 95C to approximately room temperature, and separating the thus-precipitated organic components. This is followed by reheating to about 70C
to avoid subsequent precipitations. During the following loading of the strongly acidic cation exchanger in the Na form at about 70C, any amounts of organic components, es-pecially TMA, TMME, TPA, MMT, and the like, still present in the extract, are not absorbed on the exchanger but rather remain in the aqueous phase and pass unhindered through the exchanger. In case this wastewater, loaded primarily with alkali metal ions and organic compounds, cannot be passed on to biological processing but rather must be treated thermally, the alkali metal ions can be exchanged by treatment with a strongly acidic cation exchanger in the H+ ion form, and removed by elution with a strong acid, preferably hydrochloric acid, in the form of a neutral salt, e.g. NaCl, in an aqueous solution. Upon reaching the exchange capacity with Co2+
and Mn2+, the loaded exchanger is treated with fully deminer-alized water, likewise heated to about 70C, as the washing liquid. This treatment serves for removing the organic com-ponents absorbed on the exchange resin, which settle as a smeary film on the exchange resin matrix and would considerably reduce the exchange capacity if they were not removed with each cycle. The thus-produced washing water is suitably recycled into the extraction stage.
`-- 1145738 During the subsequent regeneration, conducted at room temperature, about two bed volumes of an aqueous sodium acetate solution collected during the preceding regeneration cycle as the last runnings and having been combined with the forerunnings of the preceding regenerating cycle are introduced to the exchanger, loaded with Co2+ and Mn2+, the bed volume of which is initially filled with fully demineralized washing water. About 50~ of the bed volume is withdrawn as a solution free of Co2+/mn2+. Subsequently, about 15% of the bed volume is collected as forerunnings with a low Co2+/Mn2 content.
The next fractions withdrawn is about 135% of the bed volume as a Co2 /Mn2 acetate solution (called concentrate herein-below). For a complete displacement of the catalyst metal components from the exchanger, about 80% of the bed volume of /
.. /
:, /
/
, - ' ~S738 an approximately 15~ aqueous sodium acetate solution containing about 10 to 15 g/l of free acetic acid is introduced onto the exchanger, and thereafter about 80% of the bed volume of fully demineralized water is fed onto the exchanger, in order to remove the sodium acetate solution which contains Co and ~n ions. The thus-obtained solutions, amounting in total to about 160% of the bed volume, are withdrawn, until a pronounced reduction in the Co2+/Mn2+ concentration, in an amount of about 5-10% of the bed volume, and combined with the concentrate, and the subsequent fractions in an amount of about 150 to 155%
of the bed volume are discharged as the last runnings, combined with the previously obtained forerunnings, and reserved for use in the following regenerating cycle.
In the case of processing the residues from the combustion of the high-boiling distillation residues, which contain heavy metal components including the metals of the oxidation catalyts they are dissolved in mineral acids, e.g.
hydrochloric acid or sulfuric acid with the addition of oxidizing agents, for example a hydrogen peroxide solution or nitric acid to oxidize, inter alia, Fe2 ions . The impurities which have accumulated in the solution and stem from the materials of the plant and the fuels, such as, for instance, iron, chromium, vanadium, molybdenum, copper, and titanium, are then precipitated, by adjusting the solution to a pH of about 6 or thereabove, with a suitable base for example, an alkali metal base (i.e. an aqueous sodium hydroxide solution), in the form of the hydroxides and the precipitates are filtered off together with the insoluble proportions of the residue (ash). The thus-purified solution is adjusted to a pH of 5 or therebelow by adding at least one linear, low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms, for example acetic acid. The ions such as Na contained in ~:~4~738 the solution are removed by treatment wi~h a strongly acidic cation exchange resin loaded with Co , Mn2 and/or Ni2 ions~
The resulting (acetic)-acid- containing heavy metal solution is then treated with a strongly acidic cation exchange resin, e.g. in the Na or K form,until the exchange capacity has been reached, and the cation exchange resin is subsequently washed optionally at an elevated temperature e.g. 50 to 90C and regenerated at room temperature with alkali metal (e.g. Na or K ) acetate-containing solutions, thus displacing the metal ions of the catalyst components and obtaining an aqueous, (e.g. acetic) acid solution which contains the metal ions of the catalyst components.
The following examples serve for a further explana-tion of the invention.
The combustion residue utilized in Examples 3 and 4 was obtained by burning a high-boiling distillation residue from the Witten DMT process at 800-1200C and separation from the flue gases in an electrostatic filter. In this con-nection, 95% by weight of such a residue was combusted with the addition of 5% by weight of heavy fuel oil. The high-boiling distillation residue fed to the combustion contained about 0.1 - 1.0 ~ by weight of ash-forming heavy-metal components.
Example 1 100 kg of distillation residue from the raw ester distillation was extracted with 60 1 of reaction water of the DMT production with an acid content of about 3~, calculated as acetic acid, at about 95C, to a residual Co2 content of 20 ppm; this di~tillation residue was obtained in an industrial plant for DMT production by the combined continuous oxidation of PX- and PTE-containing mixtures in the liquid phase with atmospheric oxygen under 8 bar pressure and at temperatures of 1145~3~3 150 to 170 C with the use of a solution of cobalt acetate and manganese acetate in aqueous acetic acid, a stationary concen-tration of about 90 ppm cobalt and lO ppm manganese being set in the oxidation product; subsequent continuous esterifica-tion of the oxidation product at temperatures of about 250 C
and under 25 bar pressure with methanol; and continuous separa-tion of the esterification product by vacuum distillation, wherein, in a first distillation colunm, a fraction rich in PTE is withdrawn overhead and recycled into the oxidation, and the sump product of this column is separated in a second, subse-quent column into a fraction in DMT, withdrawn overhead, and into a high-boiling distillation residue having a cobalt content of 2.3 g/kg and a manganese content of 0.2 g/kg of residue.
After decanting, 56 l of a Co /Mn -containing extract was obtained having a Co2 content of 3O8 g/l and a Mn2 content of 0.3 g/l. The hot extract was cooled to 20 C
and thus-precipitated organic compounds were separated by filtration.
The filtered solution was heated to 70 C to prevent subsequent precipitation and passed from below through a tube charged with a strongly acidic cation exchanger loaded with Na ions commercially available under the name of "Lewatit S
100." The resin volume was 1.1 1. The loading was continued until theincipient exhaustion of the ion exchange capacity.
From the produced 56 l Co-Mn extract, l9 l,corre-sponding to a total content of 78.4 g Co + Mn + or 2.66 eq.
Co2 , was conducted at 70 C over the cation exchanger.
Subsequently, the cation exchanger was washed with fully demi-neralized water introduced from the top at 70 C. Thereupon, the cation exchanger was eluted from the top with 2.2 l of a 10~ aqueous acetic-acid sodium acetate solution, corresponding 5~3~3 to 1.3 eq. Na ~1, and then a subsequent washing step was conducted with 1 1 of fully demineralized water at room tempera-ture, thus obtaining 0.4 1 of forerunnin~s, 2.0 1 of con-centrate, and 0.8 1 of last runnings.
The forerunnings contained 4.8 g/l Co2 , 0.4 g/l Mn2 and 0.8 g/l CH3COOH.
The last runnings contained 11.2 g/l Co2+, 0.9 g/l Mn2+, 9.5 g/l Na and 6.3 g/l CH3COOH.
The aqueous concentrate contained the following 10 components :
Co2+ = 30~1 g/l Mn2+ = 2.6 g/l Na = 1.0 g/l CH3COOH = 12.0 g/l Organic cannot be detected Impurities (polarographically) ; The thus-obtained Co , Mn containing and the Na containing forerunnings and last runnings, respectively, were combined and utilized again as the eluting solution to avoid Co + and Mn losses.
Example 2 In a continuously operating extraction plant, 300 kg/h of the high-boiling distillation residue of the raw ester distillation obtained as in Example 1 was extracted under agitation at about 95C with 150 kg/h of acidic reac-tion water from the DMT production, the origin and acid content of which were in correspondence with Example 1.
The aqueous solution obtained after separation of the organic phase contained 4.6 g/l of Co2+ and 0.4 g/l of Mn2 . This solution was cooled to about 20C and separated by filtration from the precipitated organic products, which were recycled into the process, and was then collected in a i73~3 container. After heating to about 70 C to avoid subsequent precipitation of organic compounds, 650 l/hOf this solution was conducted at a temperature of 70 C over a column charged with 180 l of a resin loaded with Na+ ions under the commercial name of "Lewatit S 100". The loading of the exchanger was completed after about 3 hours.
Thereafter a flushing step was conducted with 400 1 of hot, demineralized water in order to remove organic compounds. Subsequently, the catalyst ions were eluted at ap-proximately room temperature with a solution containing sodium acetate and with a content of 10 ta 15 g/l of free acetic acid consisting, in part, of the forerunnings and last runnings of the preceding elution as well as a 15% sodium acetate solution.
In total, 515 l of solution was used for eluting pruposes.
After elution, the exchanger was washed with 170 1 of fully demineralized water.
Four fractions were collected: 90 l Co - and Mn -free solution, 35 1 of forerunnings, 240 1 of concentrate, and 320 l of last runnings.
The forerunnings contained 5.8 g/l Co , 0.4 g/l Mn and 1.0 g/l CH3COOH.
The last runnings contained 16.6 g/l Co2 , 1.3 g/l Mn2 , 19.4 g/l Na and 10.8 g/l CH3COOH.
The concentrate contained 37.0 g/l Co and
3.1 g/l Mn No organic components except for acetic acid could be detected by polarography. The forerunnings and last runnings were combined and reused for the subsequent cycle. The con-centrate was recycled directly into the oxidation described in Example l. ~he activity of this concentrate was identical to that of a fresh catalyst solution having the same cobalt and :
manganese acetate concentration. _ _ Example 3 By combustion of 25 kg of a distillation residue, obtained analogously as in Example 1, having a cobalt content of 0.23 weight %, a manganese content of 0.025 weight % and traces of iron, nickel, chromium, molybdenum, copper and tita-nium, with heavy fuel oil, 113.3 g of a combustion residue were obatined.
50.5 g of a combustion residue from the DMT process was processed under agitation with 300 ml of dilute HCl solu-tion (- 12% HCl) and 2 ml of 30% H2O2 solution for two hours at 95 C.
The specimen employed contained :
50. 7 % cobalt 5.4 % manganese 0.37 ~ iron 0.13 ~ nickel 100 ppm chromium 1,000 ppm molybdenum 100 ppm vanadium 100 ppm copper 100 ppm titanium The solution was then diluted with 1 liter of fully demineralized water and combined with about 40 % strength sodium hydroxide solution to pH 7. The amount of sodium hydroxide solution consumed was 9 ml. The solution was then heated for one hour to 95 C and filtered through a folded filter.
The filtrate, after dilution with fully demineralized water, was adjusted to a volume of 8 liters and to pH 4 with 5 ml of concentrated acetic acid.
The solution contained :
2.9 g cobalt/l
manganese acetate concentration. _ _ Example 3 By combustion of 25 kg of a distillation residue, obtained analogously as in Example 1, having a cobalt content of 0.23 weight %, a manganese content of 0.025 weight % and traces of iron, nickel, chromium, molybdenum, copper and tita-nium, with heavy fuel oil, 113.3 g of a combustion residue were obatined.
50.5 g of a combustion residue from the DMT process was processed under agitation with 300 ml of dilute HCl solu-tion (- 12% HCl) and 2 ml of 30% H2O2 solution for two hours at 95 C.
The specimen employed contained :
50. 7 % cobalt 5.4 % manganese 0.37 ~ iron 0.13 ~ nickel 100 ppm chromium 1,000 ppm molybdenum 100 ppm vanadium 100 ppm copper 100 ppm titanium The solution was then diluted with 1 liter of fully demineralized water and combined with about 40 % strength sodium hydroxide solution to pH 7. The amount of sodium hydroxide solution consumed was 9 ml. The solution was then heated for one hour to 95 C and filtered through a folded filter.
The filtrate, after dilution with fully demineralized water, was adjusted to a volume of 8 liters and to pH 4 with 5 ml of concentrated acetic acid.
The solution contained :
2.9 g cobalt/l
4~38 0.2 g manganese/l 6 ppm nickel <5 ppm iron ~5 ppm chromium, molybdenum, vanadium, copper, titanium.
The thus-obtained solution was conducted, to extensive-ly remove the Na ions, through a column with 25 ml of a strongly acidic cation exchange resin located with Co2+ and Mn2+ ions.
. A column with 250 ml of strongly acidic cation ex-change resin "Lewatit S 100" in the Na+ form was charged with the solution.
The wastewater obtained at the discharge end contained :
30 ppm cobalt 2 ppm manganese.
The exchanger was loaded with 3.5 1 of the above solution until incipient exhaustion (limit value = 30C ppm cobalt in the effluent).
The exchanger was then washed with 250 ml of fully demineralized water.
The cobalt and manganese ions were eluted with the following solution :
400 ml of combined forerunnings and last runnings fraction from the preceding experiment 200 ml of an 18% strength sodium acetate solution with 15 g of free acetic acid per liter 200 ml of fully demineralized water.
The forerunnings contained 4.2 g/l Co2 , 0.3 g/l Mn2 and 0.6 g/l CH3COOH (free acid).
The last runnings contained 20.5 g/l Co2 , 1.4 g/l Mn 18.7 g/l Na and 8.7 g/l CH3COOH (free acid).
The elution yielded :
il4S738 60 ml of a forerunnings fraction 400 ml of a main fraction depleted of Na 340 ml of a last runnings fraction rich in Na+.
The forerunnings and last runnings were combined and utilized for elution purposes during the subsequent ex-periment.
The main fraction contained :
30.9 g cobalt/l . 2.1 g manganese/l 75 ppm nickel < 5 ppm chromiumi molybdenum, vanadium, copper, titanium 175 ppm sodium.
The thus-obtained main fraction can be utilized as the catalyst solution in the DMT process.
ExamPle 4 By combustion of 25 kg of a distillation residue, obtained analogously as in Example 1, having a cobalt content of 0.20 weight ~, a manganese content of 0.020 weight %, a ;
nickel content of 0.10 weight % and traces of iron, chromium, molybdenum, copper and titanium, with heavy fuel oil, 120.2 g of a combustion residue were obtained.
50.1 g of a combustion residue was made into a solution with 350 ml of 12% hydrochloric acid and 2 ml of 30%
H O solution for 2 hours at 95 C.
The ash residue utilized contained :
40.6 % Co 4.3 % Mn 19.8 % Ni - 30 2,970 ppm Fe < 100 ppm Cr 800 ppm Mo , , lo o ppm v ppm Cu < 100 ppm Ti 1,280 ppm Na.
The thus-processed extract was adjusted to pH 6.2 with 7 ml of an approximately 40% strength sodium hydroxide solution. After one hour, the solution, heated to 95 C, was filtered through a folded filter. The filtrate was diluted to 10 1 with fully demineralized water and adjusted to pH 3.9 with 10 ml of concentrated acetic acid.
The solution contained :
1.84 g Co/l 0.16 g Mn/l 0.87 9 Ni/l < 5 ppm Fe < 5 ppm Cr < 5 ppm Mo < 5 ppm V
< 5 ppm Cu < 5 ppm Ti.
The thus-obtained solution was treated, to extensively remove the Na ions, with 250 ml of a strongly acidic cation exchange resin loaded with Co2+, Mn2+, and Ni2 ions.
` A column with 250 ml of a strongly acidic cation exchange resin "Lewatit S 100" in the Na form was charged with the solution.
The wastewater obtained at the discharge end con-tained:
25 ppm Co 2 ppm Mn 10 ppm Ni.
To load the exchanger until incipient exhaustion, 73t3 4.7 1 of the solution was consumed.
The exchanger was then washed with 250 ml of fully deminaralized water.
For eluting the Co , Mn , and Ni ions, the following solutions were employed :
390 ml of combined forerunnings and last runnings fraction of the preceding experiment 200 ml of 18% sodium acetate solution containing 15 g of free acetic acid per liter 210 ml of fully demineralized water.
The forerunnings contained 3.6 g/l Co , 0.3 g/l Mn 1.8 g/l Ni and 0.5 g/l CH3COOH (free acid).
The last runnings con~ained 13.4 g/l Co2 , 1.3 g/l Mn2 , 7.2 g/l Ni 8.9 g/l CH3COOH (free acid) and 15.8 g/l Na .
The following solutions were obtained during elution :
80 ml of a forerunnings fraction 400 ml of a main fraction depleted of Na ions 320 ml of a last runnings fraction rich in Na .
The main fraction contained :
21.5 g Co/1 1.9 g Mn/1 10.2 g Ni/l < 5 ppm Fe < 5 ppm Cr < 5 ppm Mo < 5 ppm V
< 5 ppm Cu < 5 ppm Ti 240 ppm Na.
The thus-obtained solution was conducted, to extensive-ly remove the Na ions, through a column with 25 ml of a strongly acidic cation exchange resin located with Co2+ and Mn2+ ions.
. A column with 250 ml of strongly acidic cation ex-change resin "Lewatit S 100" in the Na+ form was charged with the solution.
The wastewater obtained at the discharge end contained :
30 ppm cobalt 2 ppm manganese.
The exchanger was loaded with 3.5 1 of the above solution until incipient exhaustion (limit value = 30C ppm cobalt in the effluent).
The exchanger was then washed with 250 ml of fully demineralized water.
The cobalt and manganese ions were eluted with the following solution :
400 ml of combined forerunnings and last runnings fraction from the preceding experiment 200 ml of an 18% strength sodium acetate solution with 15 g of free acetic acid per liter 200 ml of fully demineralized water.
The forerunnings contained 4.2 g/l Co2 , 0.3 g/l Mn2 and 0.6 g/l CH3COOH (free acid).
The last runnings contained 20.5 g/l Co2 , 1.4 g/l Mn 18.7 g/l Na and 8.7 g/l CH3COOH (free acid).
The elution yielded :
il4S738 60 ml of a forerunnings fraction 400 ml of a main fraction depleted of Na 340 ml of a last runnings fraction rich in Na+.
The forerunnings and last runnings were combined and utilized for elution purposes during the subsequent ex-periment.
The main fraction contained :
30.9 g cobalt/l . 2.1 g manganese/l 75 ppm nickel < 5 ppm chromiumi molybdenum, vanadium, copper, titanium 175 ppm sodium.
The thus-obtained main fraction can be utilized as the catalyst solution in the DMT process.
ExamPle 4 By combustion of 25 kg of a distillation residue, obtained analogously as in Example 1, having a cobalt content of 0.20 weight ~, a manganese content of 0.020 weight %, a ;
nickel content of 0.10 weight % and traces of iron, chromium, molybdenum, copper and titanium, with heavy fuel oil, 120.2 g of a combustion residue were obtained.
50.1 g of a combustion residue was made into a solution with 350 ml of 12% hydrochloric acid and 2 ml of 30%
H O solution for 2 hours at 95 C.
The ash residue utilized contained :
40.6 % Co 4.3 % Mn 19.8 % Ni - 30 2,970 ppm Fe < 100 ppm Cr 800 ppm Mo , , lo o ppm v ppm Cu < 100 ppm Ti 1,280 ppm Na.
The thus-processed extract was adjusted to pH 6.2 with 7 ml of an approximately 40% strength sodium hydroxide solution. After one hour, the solution, heated to 95 C, was filtered through a folded filter. The filtrate was diluted to 10 1 with fully demineralized water and adjusted to pH 3.9 with 10 ml of concentrated acetic acid.
The solution contained :
1.84 g Co/l 0.16 g Mn/l 0.87 9 Ni/l < 5 ppm Fe < 5 ppm Cr < 5 ppm Mo < 5 ppm V
< 5 ppm Cu < 5 ppm Ti.
The thus-obtained solution was treated, to extensively remove the Na ions, with 250 ml of a strongly acidic cation exchange resin loaded with Co2+, Mn2+, and Ni2 ions.
` A column with 250 ml of a strongly acidic cation exchange resin "Lewatit S 100" in the Na form was charged with the solution.
The wastewater obtained at the discharge end con-tained:
25 ppm Co 2 ppm Mn 10 ppm Ni.
To load the exchanger until incipient exhaustion, 73t3 4.7 1 of the solution was consumed.
The exchanger was then washed with 250 ml of fully deminaralized water.
For eluting the Co , Mn , and Ni ions, the following solutions were employed :
390 ml of combined forerunnings and last runnings fraction of the preceding experiment 200 ml of 18% sodium acetate solution containing 15 g of free acetic acid per liter 210 ml of fully demineralized water.
The forerunnings contained 3.6 g/l Co , 0.3 g/l Mn 1.8 g/l Ni and 0.5 g/l CH3COOH (free acid).
The last runnings con~ained 13.4 g/l Co2 , 1.3 g/l Mn2 , 7.2 g/l Ni 8.9 g/l CH3COOH (free acid) and 15.8 g/l Na .
The following solutions were obtained during elution :
80 ml of a forerunnings fraction 400 ml of a main fraction depleted of Na ions 320 ml of a last runnings fraction rich in Na .
The main fraction contained :
21.5 g Co/1 1.9 g Mn/1 10.2 g Ni/l < 5 ppm Fe < 5 ppm Cr < 5 ppm Mo < 5 ppm V
< 5 ppm Cu < 5 ppm Ti 240 ppm Na.
Claims (10)
1. A process for the recovery of a heavy-metal oxidation catalyst solution containing a heavy-metal oxidation catalyst component, from a high-boiling distillation residue, said heavy-metal component being selected from the group consisting of cobalt, cobalt and manganese, cobalt and nickel, and cobalt, manganese and nickel, said residue having (I) a cobalt content of 1 to 10 g/kg of residue (II) a cobalt content of 1 to 10 g/kg of residue and a manganese content of 0.1 to 5 g/kg of residue (III) a cobalt content of 1 to 10 g/kg of residue and a nickel content of 0.1 to 5 g/kg of residue or (IV) a cobalt content of 1 to 10 g/kg of residue, a manganese content of 0.1 to 5g/kg of residue and a nickel content of 0.1 to 5 g/kg of residue, said residue being obtained in the production of dimethyl terephthalate by the oxidation of mixtures containing p-xylene and/or methyl p-toluate in the liquid phase with oxygen or an oxygen-containing gas under a pressure of 4 to 10 bar and at a temperature of 140 to 200°C in the presence of dissolved heavy-metal oxidation catalyst having a heavy-metal component as defined above, subsequent esterification of the oxidation product with methanol under a pressure of 20 to 30 bar and at a tempe-rature of 230 to 280°C, and a distillatory separation of the esterification product into a fraction rich in methyl p-toluate, a fraction rich in dimethyl terephthalate, and the high-boiling distillation residue;which comprises providing a suitable aqueous acidic extract containing said heavy-metal component and having:
(V) a cobalt content of 0.2 to 20 g/l (VI) a cobalt content of 0.2 to 20 g/l and a manganese content of 0.05 to 10 g/1 (VII) a cobalt content of 0.2 to 20g/1 and a nickel content of 0.05 to 10 g/1 or (VIII) a cobalt content of 0.2 to 20 g/1, a manganese content of 0.05 to 10g/1 and a nickel content of 0.05 to 10 g/l, by extraction of said heavy-metal component from the high-boiling distillation residue, with an aqueous acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, under heating, and (a) treating said aqueous, acidic extract with a strongly acidic cation exchange resin in the Na+ or K+
form at an elevated temperature until the exchange capacity has been reached , and subsequently (b) washing the cation exchange resin at an elevated temperature with water and regenerating the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na+ or K+ acetate, thus displacing said heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
(V) a cobalt content of 0.2 to 20 g/l (VI) a cobalt content of 0.2 to 20 g/l and a manganese content of 0.05 to 10 g/1 (VII) a cobalt content of 0.2 to 20g/1 and a nickel content of 0.05 to 10 g/1 or (VIII) a cobalt content of 0.2 to 20 g/1, a manganese content of 0.05 to 10g/1 and a nickel content of 0.05 to 10 g/l, by extraction of said heavy-metal component from the high-boiling distillation residue, with an aqueous acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, under heating, and (a) treating said aqueous, acidic extract with a strongly acidic cation exchange resin in the Na+ or K+
form at an elevated temperature until the exchange capacity has been reached , and subsequently (b) washing the cation exchange resin at an elevated temperature with water and regenerating the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na+ or K+ acetate, thus displacing said heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
2. A process for the recovery of a heavy-metal oxi-dation catalyst solution containing a heavy-metal oxidation catalyst component, from a high-boiling distillation residue, said heavy-metal component being selected from the group consisting of cobalt, cobalt and manganese, cobalt and nickel, and cobalt, manganese and nickel, said residue having (I) a cobalt content of 1 to 10 g/kg of residue (II) a cobalt content of 1 to 10 g/kg of residue and a manganese content of 0.1 to 5g/kg of residue (III) a cobalt content of 1 to 10 g/kg of residue and a nickel content of 0.1 to 5 g/kg of residue or (IV) a cobalt content of 1 to 10 g/kg of residue, a manganese content of 0.1 to 5 g/kg of residue and a nickel content of 0.1 to 5g/kg of residue, said residue being obtained in the production of dimethyl terephthalate by the oxidation of mixtures containing p-xylene and/or methyl p-toluate in the liquid phase with oxygen or an oxygen-containing gas under a pressure of 4 to 10 bar and at a temperature of 140 to 200°C in the presence of dissolved heavy-metal oxidation catalyst having a heavy-metal component as defined above,subsequent esterification of the oxidation pro-duct with methanol under a pressure of 20 to 30 bar and at a temperature of 230 to 280°C, and a distillatory separation of the esterification product into a fraction rich in methyl p-toluate, a fraction rich in dimethyl terephthalate, and the high-boiling distillation residue; which comprises providing a sui-table aqueous acidic extract containing said heavy-metal component and having:
(V) a cobalt content of 0.2 to 20 g/l (VI) a cobalt content of 0.2 to 20 g/l and a manganese content of 0.05 to 10g/l (VII) a cobalt content of 0.2 to 20g/1 and a nickel content of 0.05 to 10g/1 or (VIII) a cobalt content of 0.2 to 20g/1, a manganese content of 0.05 to 10g/1 and a nickel content of 0.05 to 10g/1, by extracting the ashes obtained after combustion of said high-boiling distillation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids,with the addition of an oxidizing agent under heating, subsequently diluting with water, increasing the pH of the diluted extract by adding NaOH to precipitate any iron and chromium as the hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate with acetic acid, removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2+ , Mn2+ and/or Ni2+ ions, said process being further characterized by then (a) treating said aqueous, acidic extract with a strongly acidic cation exchange resin in the Na+ or K+
form at an elevated temperature until the exchange capacity has been reached, and subsequently (b) washing the cation exchange resin at an elevated temperature with water and regenerating the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na+ or K+ acetate, thus displacing said heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
(V) a cobalt content of 0.2 to 20 g/l (VI) a cobalt content of 0.2 to 20 g/l and a manganese content of 0.05 to 10g/l (VII) a cobalt content of 0.2 to 20g/1 and a nickel content of 0.05 to 10g/1 or (VIII) a cobalt content of 0.2 to 20g/1, a manganese content of 0.05 to 10g/1 and a nickel content of 0.05 to 10g/1, by extracting the ashes obtained after combustion of said high-boiling distillation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids,with the addition of an oxidizing agent under heating, subsequently diluting with water, increasing the pH of the diluted extract by adding NaOH to precipitate any iron and chromium as the hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate with acetic acid, removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2+ , Mn2+ and/or Ni2+ ions, said process being further characterized by then (a) treating said aqueous, acidic extract with a strongly acidic cation exchange resin in the Na+ or K+
form at an elevated temperature until the exchange capacity has been reached, and subsequently (b) washing the cation exchange resin at an elevated temperature with water and regenerating the cation exchange resin at room temperature with an aqueous acetic acid solution containing Na+ or K+ acetate, thus displacing said heavy-metal component and obtaining an aqueous acetic acid catalyst solution containing said heavy-metal component.
3. Process according to claim 2 wherein the aqueous acidic extract treated in step (a) is obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with aqueous hydrochloric acid with the addition of aqueous H2O2 at about 95°C for a duration of 0.1 to 4 hours, subsequently diluting with water, increasing the pH
of the diluted extract to a value of at least 6 by adding NaOH
and heating at about 95°C for 0.1 to 2 hours to precipitate any iron and chromium as hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate to pH 5 or below with acetic acid, and removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with CO2+ , Mn2+ and/or Ni2+ ions.
of the diluted extract to a value of at least 6 by adding NaOH
and heating at about 95°C for 0.1 to 2 hours to precipitate any iron and chromium as hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate to pH 5 or below with acetic acid, and removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with CO2+ , Mn2+ and/or Ni2+ ions.
4. Process according to any one of claims 1, 2 and 3, characterized in that the catalyst solution obtained according to step (b) contains cobalt acetate and has a content of 10 to 70g/1 of cobalt, as well as less than respectively 5 mg of iron/1,5 mg of chromium/l, 5 mg of molybdenum/l, 5 mg of vanadium/l, 5 mg of copper/l, and 5 mg of titanium/l.
5. Process according to any one of claims 1, 2 and 3, characterized in that the catalyst solution obtained according to step (b) contains cobalt acetate and manganese acetate, and has a content of 10 to 70 g/l of cobalt, 1 to 35 g/l of manga-nese, as well as less than respectively 5 mg of iron/l, 5 mg of chromium/l, 5 mg of molybdenum/l, 5 mg of vanadium/l, 5 mg of copper/l, and 5 mg of titanium/l.
6. Process according to any one of claims 1, 2 and 3, characterized in that the catalyst solution obtained according to step (b) contains cobalt acetate, manganese acetate, and nickel acetate and has a content of 10 to 70 g/l of cobalt, 1 to 35 g/l of manganese, 1 to 35 g/l of nickel, as well as less than respectively 5 mg of iron/l, 5 mg of chromium/l, 5 mg of molybdenum/l, 5 mg of vanadium/l, 5 mg of copper/l, and 5 mg of titanium/l.
7. A process for the recovery of a heavy-metal oxidation catalyst component from a high-boiling distillation residue, said heavy-metal component being selected form the group consisting of cobalt, cobalt and manganese, cobalt and nickel, and cobalt, manganese and nickel, said residue being obtained from the esterified oxidation product resulting from the oxidation of an alkyl aromatic compound in the liquid phase with oxygen or an oxygen containing gas in the presence of a dissolved oxidation catalyst having a heavy-metal component as defined above, which comprises providing a suitable aqueous acidic extract containing said heavy-metal com-ponent, said extract being obtained as a result of extracting said heavy-metal component from said high-boiling distillation residue or from the ash obtained on combustion of said high-boiling distillation residue, said extract containing as acid, one or more aliphatic monocarboxylic acids containing 1 to 4 carbon atoms and (a) treating the aqueous acidic extract with a strongly acidic cation exchange resin in the alkali metal ion form until the exchange capacity has been reached and (b) subsequently washing the cation exchange resin with a suitable washing liquid, and regenerating the cation exchange resin with an aqueous solution containing at least one salt selected from the group consisting of alkali metal salts of low-moleculaxr aliphatic monocarboxylic acids having 1 to 4 carbon atoms to displace said heavy-metal component and recover as product an aqueous solution containing said heavy-metal component.
8. A process according to claim 7 wherein the acidic extract treated in step (a) is obtained by extraction of the heavy-metal component from said high-boiling distillation residue with an aqueous acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, under heating.
9. Process according to claim 7 wherein the aqueous acidic extract treated in step (a) is obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with an aqueous acid, said acid being a mineral acid or a mixture of mineral acids, with the addition of an oxidizing agent under heating, subsequently diluting with water, increasing the pH of the diluted extract by adding a suitable alkali metal hydroxide to precipitate any iron and chromium as the hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate with an acid, said acid being a low-molecular aliphatic monocarboxylic acid of 1 to 4 carbon atoms or a mixture thereof, and removal of the alkali metal ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2+ , Mn2+ and/or Ni2+ ions.
10. Process according to claim 7, wherein the aqueous acidic extract treated in step (a) is obtained by extracting the ashes obtained after combustion of said high-boiling distillation residue with aqueous hydrochloric acid with the addition of aqueous H2O2 at about 95°C for a duration of 0.1 to 4 hours, subsequently diluting with water, increasing the pH
of the diluted extract to a value of at least 6 by adding NaOH
and heating at about 95°C for 0.1 to 2 hours to precipitate any iron and chromium as hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate to pH 5 or below with acetic acid, and removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2+ , Mn2+ and/or Ni2+ ions.
of the diluted extract to a value of at least 6 by adding NaOH
and heating at about 95°C for 0.1 to 2 hours to precipitate any iron and chromium as hydroxides, filtering to effect the combined removal of the hydroxides as well as any insoluble ash components, effecting dilution with water, then effecting acidification of the filtrate to pH 5 or below with acetic acid, and removal of the Na+ ions contained in the filtrate with the aid of a strongly acidic cation exchange resin loaded with Co2+ , Mn2+ and/or Ni2+ ions.
Applications Claiming Priority (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE2950318A DE2950318C2 (en) | 1979-12-14 | 1979-12-14 | Recovery and reuse of cobalt or cobalt and manganese compounds from the Witten DMT process |
| DEP2950318.2 | 1979-12-14 | ||
| DE3037054A DE3037054C2 (en) | 1979-12-14 | 1980-10-01 | Process for the recovery and reuse of cobalt or cobalt and manganese compounds from the Witten DMT process |
| DEP3037054.8 | 1980-10-01 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1145738A true CA1145738A (en) | 1983-05-03 |
Family
ID=25782427
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000366654A Expired CA1145738A (en) | 1979-12-14 | 1980-12-12 | Recovery of heavy-metal oxidation catalyst from the written dmt process for reuse thereof |
Country Status (14)
| Country | Link |
|---|---|
| EP (1) | EP0031437B1 (en) |
| AR (1) | AR226711A1 (en) |
| BR (1) | BR8008131A (en) |
| CA (1) | CA1145738A (en) |
| CS (1) | CS227320B2 (en) |
| DD (1) | DD155142A5 (en) |
| DE (2) | DE3037054C2 (en) |
| ES (1) | ES8200641A1 (en) |
| IN (1) | IN155166B (en) |
| MX (1) | MX155223A (en) |
| PL (1) | PL133454B1 (en) |
| RO (2) | RO81386A (en) |
| TR (1) | TR21413A (en) |
| YU (1) | YU41370B (en) |
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| CN107849227A (en) * | 2015-08-07 | 2018-03-27 | 杰富意化学株式会社 | The manufacture method of bicyclopentadiene class phenol-formaldehyde resin modified |
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| CN1062852C (en) * | 1998-02-16 | 2001-03-07 | 中国石化辽阳石油化纤公司 | Process for recovering cobalt and manganese catalysts from production of terephthalic acid |
| CN101255107A (en) * | 2008-04-03 | 2008-09-03 | 沈福昌 | Resourceful treatment method of purified terephthalic acid waste residue |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE792520A (en) * | 1971-12-10 | 1973-06-08 | Standard Oil Co | RECOVERY OF COLBALT AND / OR MANGANESE FREE OF IRON AND COPPER |
| DE2531106B2 (en) * | 1975-07-11 | 1979-02-01 | Instytut Ciezkiej Syntezy Organicznej Blachownia, Kedzierzyn (Polen) | Process for the recovery and recycling of the catalyst from the manufacturing process of dimethyl terephthalate |
| GB1595974A (en) * | 1977-04-07 | 1981-08-19 | Ici Ltd | Recovering catalyst values |
| DE2923681C2 (en) * | 1979-06-12 | 1981-11-05 | Dynamit Nobel Ag, 5210 Troisdorf | Process for the recovery and reuse of heavy metal oxidation catalyst from the Wittem DMT process |
-
1980
- 1980-10-01 DE DE3037054A patent/DE3037054C2/en not_active Expired
- 1980-11-15 DE DE8080107094T patent/DE3062553D1/en not_active Expired
- 1980-11-15 EP EP80107094A patent/EP0031437B1/en not_active Expired
- 1980-12-04 AR AR283489A patent/AR226711A1/en active
- 1980-12-08 RO RO80102799A patent/RO81386A/en unknown
- 1980-12-08 RO RO110806A patent/RO86655B/en unknown
- 1980-12-09 TR TR21413A patent/TR21413A/en unknown
- 1980-12-09 DD DD80225898A patent/DD155142A5/en not_active IP Right Cessation
- 1980-12-11 MX MX185156A patent/MX155223A/en unknown
- 1980-12-12 CA CA000366654A patent/CA1145738A/en not_active Expired
- 1980-12-12 BR BR8008131A patent/BR8008131A/en not_active IP Right Cessation
- 1980-12-12 ES ES497660A patent/ES8200641A1/en not_active Expired
- 1980-12-12 YU YU3136/80A patent/YU41370B/en unknown
- 1980-12-12 CS CS808784A patent/CS227320B2/en unknown
- 1980-12-13 PL PL1980228447A patent/PL133454B1/en unknown
-
1981
- 1981-03-25 IN IN322/CAL/81A patent/IN155166B/en unknown
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107849227A (en) * | 2015-08-07 | 2018-03-27 | 杰富意化学株式会社 | The manufacture method of bicyclopentadiene class phenol-formaldehyde resin modified |
| CN107849227B (en) * | 2015-08-07 | 2021-07-23 | 杰富意化学株式会社 | Method for producing dicyclopentadiene-modified phenol resin |
Also Published As
| Publication number | Publication date |
|---|---|
| MX155223A (en) | 1988-02-08 |
| ES497660A0 (en) | 1981-11-01 |
| DE3037054A1 (en) | 1982-04-22 |
| IN155166B (en) | 1985-01-12 |
| YU313680A (en) | 1983-04-30 |
| YU41370B (en) | 1987-02-28 |
| BR8008131A (en) | 1981-06-30 |
| DE3037054C2 (en) | 1983-09-08 |
| RO86655A (en) | 1985-04-17 |
| RO86655B (en) | 1985-05-01 |
| RO81386A (en) | 1983-06-01 |
| RO81386B (en) | 1983-05-30 |
| TR21413A (en) | 1984-05-29 |
| PL133454B1 (en) | 1985-06-29 |
| DD155142A5 (en) | 1982-05-19 |
| EP0031437A1 (en) | 1981-07-08 |
| CS227320B2 (en) | 1984-04-16 |
| AR226711A1 (en) | 1982-08-13 |
| ES8200641A1 (en) | 1981-11-01 |
| PL228447A1 (en) | 1981-10-16 |
| DE3062553D1 (en) | 1983-05-05 |
| EP0031437B1 (en) | 1983-03-30 |
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