DE4426132A1 - Dehydration of acetic acid in adipic acid mfr. without cobalt salt pptn. - Google Patents

Dehydration of acetic acid in adipic acid mfr. without cobalt salt pptn.

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Publication number
DE4426132A1
DE4426132A1 DE19944426132 DE4426132A DE4426132A1 DE 4426132 A1 DE4426132 A1 DE 4426132A1 DE 19944426132 DE19944426132 DE 19944426132 DE 4426132 A DE4426132 A DE 4426132A DE 4426132 A1 DE4426132 A1 DE 4426132A1
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Germany
Prior art keywords
phase
acetic acid
cyclohexane
column
water
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
DE19944426132
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German (de)
Inventor
Ernst Dr Kysela
Bettina Burkhardt
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Bayer AG
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Bayer AG
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Publication date
Application filed by Bayer AG filed Critical Bayer AG
Priority to DE19944426132 priority Critical patent/DE4426132A1/en
Publication of DE4426132A1 publication Critical patent/DE4426132A1/en
Withdrawn legal-status Critical Current

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    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
    • C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
    • C07C51/42—Separation; Purification; Stabilisation; Use of additives
    • C07C51/43—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation
    • C07C51/44—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation
    • C07C51/46—Separation; Purification; Stabilisation; Use of additives by change of the physical state, e.g. crystallisation by distillation by azeotropic distillation

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Oil, Petroleum & Natural Gas (AREA)
  • Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)

Abstract

Dehydration of process acetic acid from liq. phase oxidn. of cyclohexane with air in the presence of Co salts as catalyst is carried out in a dehydration colum, without pptn. of Co salts, after sepn. of the adipic acid by filtration and of the cyclohexane phase by phase sepn.. Dehydration is carried out by azeotropic distn. of the acetic acid phase to be recycled, with addn. of cyclohexane, until the residual water content is less than 0.3 up to 0.7 wt.%.

Description

Gegenstand der Erfindung ist ein Verfahren zur Entwässerung von Prozeß­ essigsäure aus der Flüssigphasenoxidation von Cyclohexan mit Luft in Gegenwart von Cobaltsalzen als Katalysator nach Abtrennung der Adipinsäure durch Filtra­ tion und der Cyclohexanphase durch Phasentrennung unter gleichzeitiger Vermei­ dung von Cobaltsalzfallungen in der Entwässerungskolonne, dadurch gekennzeich­ net, daß man die an den Prozeßanfang zurückzuführende Essigsäurephase unter Verwendung von zugesetztem Cyclohexan einer Azeotropdestillation unter destilla­ tiver Entfernung des Wassers bis auf einen Restgehalt von 0,3 bis 0,7 Gew.-% unterzieht.The invention relates to a process for dewatering process acetic acid from the liquid phase oxidation of cyclohexane with air in the presence of cobalt salts as a catalyst after separation of the adipic acid by Filtra tion and the cyclohexane phase by phase separation with simultaneous avoidance formation of cobalt salt precipitates in the dewatering column, characterized net that under the acetic acid phase to be returned to the beginning of the process Use of added cyclohexane an azeotropic distillation under distilla tive removal of water down to a residual content of 0.3 to 0.7% by weight undergoes.

Beim Verfahren der mit der Veröffentlichungs-Nr. WO 94/07834 veröffentlichten internationalen Patentanmeldung wird Cyclohexan mit Sauerstoff oder einem Sauerstoff enthaltenden Gasgemisch (z. B. Luft) in Gegenwart von 0,15 bis 15 Molen Essigsäure als Lösungsmittel bei einem Druck von 1 bis 100, vorzugsweise 1 bis 70 und besonders bevorzugt 5 bis 40 atm einer Oxidationsreaktion unterzogen. Das den Oxidationsreaktor verlassende Reaktionsgemisch wird abgekühlt, die hierbei ausfallende Adipinsäure durch Filtration abgetrennt und das verbleibende zweiphasige flüssige Gemisch in eine unpolare, Cyclohexan-reiche und eine polare, Essigsäure-reiche, die Hauptmenge des Katalysators enthaltende polare Phase aufgetrennt. Die unpolare Phase wird vollständig, die polare Phase zu 10 bis 98, vorzugsweise 50 bis 95 und insbesondere 60 bis 90% an den Prozeßanfang zurückgeführt. In the process of using the publication no. WO 94/07834 published international patent application is cyclohexane with oxygen or a Gas mixture containing oxygen (e.g. air) in the presence of 0.15 to 15 Moles of acetic acid as solvent at a pressure of 1 to 100, preferably 1 to 70 and particularly preferably 5 to 40 atm of an oxidation reaction subjected. The reaction mixture leaving the oxidation reactor becomes cooled, the resulting adipic acid separated by filtration and the remaining two-phase liquid mixture in a non-polar, cyclohexane-rich and a polar, acetic acid-rich one containing the bulk of the catalyst polar phase separated. The non-polar phase becomes complete, the polar phase too 10 to 98, preferably 50 to 95 and in particular 60 to 90% of the Process start traced.  

Die vorliegende Erfindung betrifft nun eine Verbesserung dieses vorbekannten Verfahrens, welche darin besteht, den an den Prozeßanfang zurückzuführenden Teil der polaren Phase durch Azeotropdestillation unter Verwendung von Cyclo­ hexan als Schleppmittel von einem Teil des vorliegenden Wassers zu befreien. Hierbei ist wesentlich, daß nicht die Gesamtmenge des vorliegenden Wassers ent­ fernt wird, um Cobaltsalzfallungen in der zu Azeotropdestillation eingesetzen Ent­ wässerungskolonne zu vermeiden.The present invention now relates to an improvement of this prior art Process, which consists in returning the process to the beginning of the process Part of the polar phase by azeotropic distillation using cyclo to remove hexane as an entrainer from part of the water present. It is essential that the total amount of water present is not ent is removed to remove cobalt salts in the ent used for azeotropic distillation to avoid the water column.

Die genannte, erfindungsgemäß zu behandelnde polare Phase enthält neben unter­ schiedlichen sonstigen Nebenprodukten (z. B. Cyclohexanol, Cyclohexanon, Cyclo­ hexanolester u. dgl.) ca. 1 bis 6, vorzugsweise 3 bis 4 Gew.-% Wasser, ca. 6 bis 15, vorzugsweise 8 bis 9 Gew.-% Cyclohexan, ca. 60 bis 75, vorzugsweise 66 bis 68 Gew.-% Essigsäure, ca. 3 bis 6, vorzugsweise 3 bis 4 Gew.-% Adipinsäure und ca. 2500 bis 6000, vorzugsweise 3000 bis 4000 ppm (Gewicht) Cobalt in Form von Cobaltsalzen.The polar phase mentioned to be treated according to the invention contains in addition to under various other by-products (e.g. cyclohexanol, cyclohexanone, cyclo hexanol esters Like.) about 1 to 6, preferably 3 to 4 wt .-% water, about 6 to 15, preferably 8 to 9 wt .-% cyclohexane, about 60 to 75, preferably 66 to 68% by weight of acetic acid, approx. 3 to 6, preferably 3 to 4% by weight of adipic acid and approx. 2500 to 6000, preferably 3000 to 4000 ppm (weight) cobalt in the form of cobalt salts.

Durch die erfindungsgemäße Azeotropdestillation wird erreicht, daß der Wasser­ gehalt des an den Prozeßanfang zurückzuführenden Teils der polaren Phase nicht unter ca. 0,3, vorzugsweise bei 0,4 bis 0,7 Gew.-% liegt, um so unerwünschten Ausfällungen und Ablagerungen von Cobaltsalzen vorzubeugen.The azeotropic distillation according to the invention ensures that the water does not contain the part of the polar phase that can be traced back to the beginning of the process is less than about 0.3, preferably 0.4 to 0.7% by weight, so all the more undesirable To prevent precipitation and deposits of cobalt salts.

Das erfindungsgemäße Verfahren wird vorzugsweise dergestalt durchgeführt, daß man die Azeotropdestillation kontinuierlich in einer Destillationskolonne durch­ führt, in welche die zu entwässernde polare Phase als Seitenstrom eingespeist wird, in den siedenden Sumpf abwärts fließt und mit einem Wassergehalt von 0,3 bis 0,7, vorzugsweise ca. 0,4 bis 0,7 Gew.-% aus dem siedenden Sumpf ent­ nommen wird, während gleichzeitig Essigsäure enthaltendes Cyclohexan in die Kolonne eingepumpt wird, sich dort mit der eingespeisten polaren Phase mischt, einen Teil des in ihr enthaltenden Wassers aufnimmt und als wäßriges Azeotrop über Kopf abgenommen und in einem Scheidegefaß in eine untere Wasserphase und eine mit Essigsäure gesättigte obere, im Kreislauf in die Kolonne zurückzu­ führende Cyclohexan/Essigsäure-Phase getrennt wird. Die obere Cyclohexan/Essig­ säure-Phase stellt das im Kreislauf geführte Schleppmittel dar. The process according to the invention is preferably carried out in such a way that the azeotropic distillation is carried out continuously in a distillation column leads into which the polar phase to be dewatered is fed as a side stream flows down into the boiling swamp and has a water content of 0.3 to 0.7, preferably about 0.4 to 0.7 wt .-% ent from the boiling sump is taken, while at the same time acetic acid containing cyclohexane in the Column is pumped in, mixes with the polar phase fed in, absorbs part of the water it contains and as an aqueous azeotrope Removed overhead and in a septic tank into a lower water phase and an upper one saturated with acetic acid, recirculated back to the column leading cyclohexane / acetic acid phase is separated. The top cyclohexane / vinegar The acid phase is the entrainer that is circulated.  

Das zuletztgenannte Schleppmittel besteht im allgemeinen aus einem Gemisch aus Cyclohexan und Essigsäure. Das Gewichtsverhältnis von in Kreislauf geführtem Schleppmittel zu zu entwässernder polarer Phase liegt im allgemeinen bei 1 : 1 bis 2 : 1.The latter entrainer generally consists of a mixture Cyclohexane and acetic acid. The weight ratio of circulated The entrainer for the polar phase to be dewatered is generally 1: 1 to 2: 1.

Die Destillation kann bei Normaldruck und im Vakuum durchgeführt werden. Zur Vermeidung unerwünschter Reaktionen im Sumpf der Kolonne, wie etwa Vereste­ rungsreaktionen, wird vorzugsweise im Vakuum gearbeitet. Die genauen Daten der Kolonne hängen von ihrer Auslegung ab. Typische Daten einer 4 m-Kolonne (2 m Packungshöhe) mit Wilson-Spiralen als Füllkörper bei Normaldruckbetrieb: 90°C Sumpftemperatur, 70°C Kopftemperatur; bei 600 mbar: 75°C Sumpftemperatur und 55°C Kopftemperatur.The distillation can be carried out at normal pressure and in vacuo. For Avoidance of undesirable reactions in the bottom of the column, such as esterification tion reactions, is preferably carried out in a vacuum. The exact dates of the Columns depend on their design. Typical data of a 4 m column (2 m Packing height) with Wilson spirals as packing in normal pressure operation: 90 ° C Bottom temperature, 70 ° C head temperature; at 600 mbar: 75 ° C bottom temperature and 55 ° C head temperature.

Im nachfolgenden Beispiel beziehen sich alle Mengenangaben in "Prozent" und "ppm" auf das Gewicht.In the following example, all quantities refer to "percent" and "ppm" by weight.

Beispielexample

Die aus der Phasentrennung einer Cyclohexan-Oxidation anfallende, an den Prozeßanfang zurückzuführende polare Phase (Rohessigsäure) mit einem Gehalt an Wasser von 3 bis 4%, an Cyclohexan von 8 bis 9%, an Essigsäure von 66 bis 68%, an Adipinsäure von 3 bis 4% und an Cobaltacetat in einer Menge ent­ sprechend 3000 bis 4000 ppm Co wird in einer Menge von 1000 ml/h als Seiten­ strom in eine mit Wilson-Spiralen gefüllte Glaskolonne der Höhe 2 m eingespeist und fließt abwärts in den bei einer Temperatur von 95°C siedenden Sumpf und von diesem über einen Überlauf in die Vorlagen. Zur Entfernung des Reaktions­ wassers wird zusätzlich über einen weiteren Seitenstrom Essigsäure-gesättigtes Cyclohexan in einer Menge von 1000 ml/h in die Kolonne eingepumpt. Das Schleppmittel vermischt sich mit der eingespeisten Rohessigsäure, nimmt einen Teil des Wassers und etwas Essigsäure auf und wird als wäßriges Azeotrop über Kopf abgenommen. In einem Scheidegefäß trennt sich das Destillat in eine 15% Essigsäure enthaltende untere Wasserphase und eine mit Essigsäure gesättigte Cyclohexanphase. Diese obere Cyclohexan/Essigsäure-Phase wird wieder in die Kolonne zurückgepumpt und stellt das im Kreislauf geführte Schleppmittel dar.The resulting from the phase separation of a cyclohexane oxidation to the Beginning of the process polar phase (crude acetic acid) containing Water from 3 to 4%, from cyclohexane from 8 to 9%, from acetic acid from 66 to 68%, of adipic acid of 3 to 4% and of cobalt acetate in an amount speaking 3000 to 4000 ppm Co is in an amount of 1000 ml / h as sides current was fed into a glass column of height 2 m filled with Wilson spirals and flows down into the swamp and boiling at a temperature of 95 ° C from this via an overflow into the templates. To remove the reaction water is additionally saturated with acetic acid via a further side stream Cyclohexane in an amount of 1000 ml / h pumped into the column. The The entrainer mixes with the raw acetic acid fed in, takes one Part of the water and some acetic acid and is over as an aqueous azeotrope Head removed. In a separating vessel, the distillate separates into a 15% Lower water phase containing acetic acid and one saturated with acetic acid Cyclohexane phase. This upper cyclohexane / acetic acid phase is again in the Pumped back and represents the entrainer circulated.

Die in den Vorlagen gesammelte Rohessigsäure weist einen Wassergehalt von ca. 0,6% auf.The crude acetic acid collected in the templates has a water content of approx. 0.6%.

Claims (2)

1. Verfahren zur Entwässerung von Prozeßessigsäure aus der Flüssigphasen­ oxidation von Cyclohexan mit Luft in Gegenwart von Cobaltsalzen als Katalysator nach Abtrennung der Adipinsäure durch Filtration und der Cyclohexanphase durch Phasentrennung unter gleichzeitiger Vermeidung von Cobaltsalzfallungen in der Entwässerungskolonne, dadurch gekenn­ zeichnet, daß man die an den Prozeßanfang zurückzuführende Essigsäure­ phase unter Verwendung von zugesetztem Cyclohexan einer Azeotrop­ destillation unter destillativer Entfernung des Wassers bis auf einen Restge­ halt von weniger als 0,3 bis 0,7 Gew.-% unterzieht.1. Process for dehydrating process acetic acid from the liquid phase oxidation of cyclohexane with air in the presence of cobalt salts as a catalyst after separation of the adipic acid by filtration and the cyclohexane phase by phase separation while avoiding cobalt salt drops in the dewatering column, characterized in that the Process acetic acid phase to be returned using an added cyclohexane is subjected to an azeotropic distillation with removal of the water by distillation to a residual content of less than 0.3 to 0.7% by weight. 2. Verfahren gemäß Anspruch 1, dadurch gekennzeichnet, daß man die Azeo­ tropdestillation kontinuierlich in einer Destillationskolonne durchführt, in welche die zu entwässernde polare Phase als Seitenstrom eingespeist wird, in den siedenden Sumpf abwärts fließt und mit einem Wassergehalt von als 0,4 bis 0,7 Gew.-% aus dem siedenden Sumpf entnommen wird, während gleichzeitig Essigsäure enthaltendes Cyclohexan in die Kolonne einge­ pumpt wird, sich dort mit der eingespeisten polaren Phase mischt, einen Teil des in ihr enthaltenden Wassers aufnimmt und als wäßriges Azeotrop über Kopf abgenommen und in einem Scheidegefäß in eine untere Wasser­ phase und eine mit Essigsäure gesättigte obere, im Kreislauf in die Kolonne zurückzuführende Cyclohexan/Essigsäure-Phase getrennt wird.2. The method according to claim 1, characterized in that the azeo carried out tropdistillation continuously in a distillation column, in which the polar phase to be dewatered is fed as a side stream, flows down into the boiling swamp and with a water content of than 0.4 to 0.7 wt .-% is removed from the boiling sump while cyclohexane containing acetic acid is simultaneously introduced into the column is pumped, mixes with the polar phase fed in, one Part of the water it contains and as an aqueous azeotrope Removed overhead and in a septic tank into a lower water phase and a top saturated with acetic acid, circulating in the Column to be recycled cyclohexane / acetic acid phase is separated.
DE19944426132 1994-07-22 1994-07-22 Dehydration of acetic acid in adipic acid mfr. without cobalt salt pptn. Withdrawn DE4426132A1 (en)

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Cited By (24)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5801273A (en) * 1996-08-21 1998-09-01 Twenty-First Century Research Corporation Methods and devices for controlling the reaction rate of a hydrocarbon to an intermediate oxidation product by pressure drop adjustments
US5817868A (en) * 1996-11-12 1998-10-06 Twenty-First Century Research Corporation Method and devices for controlling the oxidation of a hydrocarbon to an acid by regulating temperature/conversion relationship in multi-stage arrangements
US5824819A (en) * 1996-12-18 1998-10-20 Twenty-First Century Research Corporation Methods of preparing an intermediate oxidation product from a hydrocarbon by utilizing an activated initiator
WO1999014179A1 (en) * 1997-09-16 1999-03-25 Rpc Inc. Methods and reactor devices for removing catalyst after oxidation of hydrocarbons
WO1999014178A1 (en) * 1997-09-16 1999-03-25 Rpc Inc. Methods of recycling catalyst in oxidations of hydrocarbons
US5908589A (en) * 1997-12-08 1999-06-01 Twenty-First Century Research Corporation Methods for separating catalyst from oxidation mixtures containing dibasic acids
US5922908A (en) * 1996-06-24 1999-07-13 Twenty-First Century Research Corporation Methods for preparing dibasic acids
US5929277A (en) * 1997-09-19 1999-07-27 Twenty-First Century Research Corporation Methods of removing acetic acid from cyclohexane in the production of adipic acid
WO1999040058A1 (en) * 1998-02-09 1999-08-12 Rpc, Inc. Process for treating cobalt catalyst in oxidation mixtures of hydrocarbons to dibasic acids
US5939582A (en) * 1996-01-17 1999-08-17 Twenty-First Century Research Corporation Reaction control by regulating internal condensation inside a reactor
WO2000001656A1 (en) * 1998-07-02 2000-01-13 Rpc Inc. Methods of extracting catalyst from a reaction mixture in the oxidation of cyclohexane to adipic acid
US6037491A (en) * 1997-07-25 2000-03-14 Rpc Inc. Methods and devices for controlling hydrocarbon oxidations to respective acids by adjusting the solvent to hydrocarbon ratio
US6103933A (en) * 1996-11-07 2000-08-15 Rpc Inc. Methods for controlling the oxidation rate of a hydrocarbon by adjusting the ratio of the hydrocarbon to a rate-modulator
WO2000048981A1 (en) * 1999-02-22 2000-08-24 Rpc Inc. Methods of extracting catalyst in solution in the manufacture of adipic acid
US6129875A (en) * 1998-02-19 2000-10-10 Rpc Inc. Process of separating catalyst from oxidation mixtures
WO2000063147A1 (en) * 1999-04-20 2000-10-26 Rpc Inc. Methods of replacing water and cyclohexanone with acetic acid in aqueous solutions of catalyst
US6143927A (en) * 1996-06-24 2000-11-07 Rpc Inc. Methods for removing catalyst after oxidation of hydrocarbons
US6288270B1 (en) 1996-06-24 2001-09-11 Rpc Inc. Methods for controlling the reaction rate of a hydrocarbon to an acid by making phase-related adjustments
US6288274B1 (en) 1996-08-21 2001-09-11 Rpc Inc. Methods and devices for controlling the reaction rate and/or reactivity of hydrocarbon to an intermediate oxidation product by adjusting the oxidant consumption rate
US6337051B1 (en) 1996-06-24 2002-01-08 Rpc Inc. Device for detecting formation of a second liquid phase
US6340420B1 (en) 1998-07-06 2002-01-22 Rpc Inc. Methods of treating the oxidation mixture of hydrocarbons to respective dibasic acids
EP1370335A1 (en) * 2001-03-15 2003-12-17 A.E. Staley Manufacturing Company Azeotropic distillation process for producing organic acids or organic acid amides
US6695952B1 (en) 1999-07-22 2004-02-24 Consortium Fur Elektrochemische Industrie Gmbh Method for the separation of and purification of an aqueous mixture consisting of the main components acetic acid and formic acid
US6793777B1 (en) 1999-07-22 2004-09-21 Consortium für elektrochemische Industrie GmbH Method for separating and purifying an aqueous mixture that mainly consists of acetic acid and formic acid

Cited By (41)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5939582A (en) * 1996-01-17 1999-08-17 Twenty-First Century Research Corporation Reaction control by regulating internal condensation inside a reactor
US6359173B1 (en) 1996-06-24 2002-03-19 Rpc Inc. Methods and devices for oxidizing a hydrocarbon to form an acid
US6143927A (en) * 1996-06-24 2000-11-07 Rpc Inc. Methods for removing catalyst after oxidation of hydrocarbons
US6288270B1 (en) 1996-06-24 2001-09-11 Rpc Inc. Methods for controlling the reaction rate of a hydrocarbon to an acid by making phase-related adjustments
US6294689B1 (en) 1996-06-24 2001-09-25 Rpc Inc. Methods for removing catalyst after oxidation of hydrocarbons
US5922908A (en) * 1996-06-24 1999-07-13 Twenty-First Century Research Corporation Methods for preparing dibasic acids
US6156868A (en) * 1996-06-24 2000-12-05 Rpc Inc. Methods for preparing polymers from dibasic acids
US6039902A (en) * 1996-06-24 2000-03-21 Rpc Inc. Methods of recycling catalyst in oxidations of hydrocarbons
US6337051B1 (en) 1996-06-24 2002-01-08 Rpc Inc. Device for detecting formation of a second liquid phase
US5877341A (en) * 1996-08-21 1999-03-02 Twenty-First Century Research Corporation Methods and devices for controlling the reaction rate of a hydrocarbon to an intermediate oxidation product by pressure drop adjustments
US6288274B1 (en) 1996-08-21 2001-09-11 Rpc Inc. Methods and devices for controlling the reaction rate and/or reactivity of hydrocarbon to an intermediate oxidation product by adjusting the oxidant consumption rate
US5801273A (en) * 1996-08-21 1998-09-01 Twenty-First Century Research Corporation Methods and devices for controlling the reaction rate of a hydrocarbon to an intermediate oxidation product by pressure drop adjustments
US6183698B1 (en) 1996-08-21 2001-02-06 Rpc Inc. Devices for controlling the reaction rate of a hydrocarbon to an intermediate oxidation product by pressure drop adjustments
US6103933A (en) * 1996-11-07 2000-08-15 Rpc Inc. Methods for controlling the oxidation rate of a hydrocarbon by adjusting the ratio of the hydrocarbon to a rate-modulator
US5998572A (en) * 1996-11-12 1999-12-07 Rpc Inc. Methods and devices for controlling the oxidation of a hydrocarbon to an acid by regulating temperature/conversion relationship in multi-stage arrangements
US5817868A (en) * 1996-11-12 1998-10-06 Twenty-First Century Research Corporation Method and devices for controlling the oxidation of a hydrocarbon to an acid by regulating temperature/conversion relationship in multi-stage arrangements
US5980801A (en) * 1996-12-18 1999-11-09 Twenty-First Century Research Corporation Methods of preparing an intermediate oxidation product from a hydrocarbon by utilizing an activated initiator
US5824819A (en) * 1996-12-18 1998-10-20 Twenty-First Century Research Corporation Methods of preparing an intermediate oxidation product from a hydrocarbon by utilizing an activated initiator
US6037491A (en) * 1997-07-25 2000-03-14 Rpc Inc. Methods and devices for controlling hydrocarbon oxidations to respective acids by adjusting the solvent to hydrocarbon ratio
WO1999014178A1 (en) * 1997-09-16 1999-03-25 Rpc Inc. Methods of recycling catalyst in oxidations of hydrocarbons
WO1999014179A1 (en) * 1997-09-16 1999-03-25 Rpc Inc. Methods and reactor devices for removing catalyst after oxidation of hydrocarbons
US5929277A (en) * 1997-09-19 1999-07-27 Twenty-First Century Research Corporation Methods of removing acetic acid from cyclohexane in the production of adipic acid
US6177053B1 (en) 1997-09-19 2001-01-23 Rpc Inc. Devices for removing acetic acid from cyclohexane in the production of adipic acid
US5908589A (en) * 1997-12-08 1999-06-01 Twenty-First Century Research Corporation Methods for separating catalyst from oxidation mixtures containing dibasic acids
US6326455B2 (en) 1998-02-09 2001-12-04 Rpc Inc. Methods for treating cobalt catalyst in oxidation mixtures resulting from oxidation of hydrocarbons to dibasic acids
US6232495B1 (en) 1998-02-09 2001-05-15 Rpc Inc. Methods for treating cobalt catalyst in oxidation mixtures resulting from oxidation of hydrocarbons to dibasic acids
WO1999040058A1 (en) * 1998-02-09 1999-08-12 Rpc, Inc. Process for treating cobalt catalyst in oxidation mixtures of hydrocarbons to dibasic acids
US6129875A (en) * 1998-02-19 2000-10-10 Rpc Inc. Process of separating catalyst from oxidation mixtures
US6433220B1 (en) 1998-07-02 2002-08-13 Rpc Inc. Methods of extracting catalyst from a reaction mixture in the oxidation of cyclohexane to adipic acid
US6433221B1 (en) 1998-07-02 2002-08-13 Rpc Inc. Methods of separating catalyst in solution from a reaction mixture produced by oxidation of cyclohexane to adipic acid
US6218573B1 (en) 1998-07-02 2001-04-17 Rpc Inc. Methods of recovering catalyst in solution in the oxidation of cyclohexane to adipic acid
WO2000001655A1 (en) * 1998-07-02 2000-01-13 Rpc Inc. Methods of separating catalyst in solution from a reaction mixture produced by oxidation of cyclohexane to adipic acid
WO2000001656A1 (en) * 1998-07-02 2000-01-13 Rpc Inc. Methods of extracting catalyst from a reaction mixture in the oxidation of cyclohexane to adipic acid
US6340420B1 (en) 1998-07-06 2002-01-22 Rpc Inc. Methods of treating the oxidation mixture of hydrocarbons to respective dibasic acids
WO2000048981A1 (en) * 1999-02-22 2000-08-24 Rpc Inc. Methods of extracting catalyst in solution in the manufacture of adipic acid
US6417128B1 (en) 1999-04-20 2002-07-09 Rpc, Inc. Methods and replacing water and cyclohexanone with acetic acid in aqueous solutions of catalyst
WO2000063147A1 (en) * 1999-04-20 2000-10-26 Rpc Inc. Methods of replacing water and cyclohexanone with acetic acid in aqueous solutions of catalyst
US6695952B1 (en) 1999-07-22 2004-02-24 Consortium Fur Elektrochemische Industrie Gmbh Method for the separation of and purification of an aqueous mixture consisting of the main components acetic acid and formic acid
US6793777B1 (en) 1999-07-22 2004-09-21 Consortium für elektrochemische Industrie GmbH Method for separating and purifying an aqueous mixture that mainly consists of acetic acid and formic acid
EP1370335A1 (en) * 2001-03-15 2003-12-17 A.E. Staley Manufacturing Company Azeotropic distillation process for producing organic acids or organic acid amides
EP1370335A4 (en) * 2001-03-15 2004-08-11 Staley Mfg Co A E Azeotropic distillation process for producing organic acids or organic acid amides

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