CA1093049A - Residue treatment process - Google Patents
Residue treatment processInfo
- Publication number
- CA1093049A CA1093049A CA276,005A CA276005A CA1093049A CA 1093049 A CA1093049 A CA 1093049A CA 276005 A CA276005 A CA 276005A CA 1093049 A CA1093049 A CA 1093049A
- Authority
- CA
- Canada
- Prior art keywords
- residue
- alcohol
- esterification
- organic
- acid
- 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.)
- Expired
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/16—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation
- C07C51/31—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting
- C07C51/313—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation of cyclic compounds with ring-splitting with molecular oxygen
-
- 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
-
- 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
- C07C51/487—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification
- C07C51/493—Separation; Purification; Stabilisation; Use of additives by treatment giving rise to chemical modification whereby carboxylic acid esters are formed
-
- 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Oil, Petroleum & Natural Gas (AREA)
- General Chemical & Material Sciences (AREA)
- Materials Engineering (AREA)
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
- Low-Molecular Organic Synthesis Reactions Using Catalysts (AREA)
- Catalysts (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In the manufacture of adipic acid by the nitric acid oxidation of a cylcohexanol/cyclohexanone mixture, the spent nitric acid is fortified and recycled for use.
Continuous recycling causes a built-up of impurities such as succinic and glutaric acid and catalyst metals. These residues are treated by the process of the invention which comprises mixing the residue in molten form with a C6-C13 alcohol at elevated temperature to effect partial esterifica-tion and to produce an aqueous phase and an organic phase.
The phases may then be separated.
In the manufacture of adipic acid by the nitric acid oxidation of a cylcohexanol/cyclohexanone mixture, the spent nitric acid is fortified and recycled for use.
Continuous recycling causes a built-up of impurities such as succinic and glutaric acid and catalyst metals. These residues are treated by the process of the invention which comprises mixing the residue in molten form with a C6-C13 alcohol at elevated temperature to effect partial esterifica-tion and to produce an aqueous phase and an organic phase.
The phases may then be separated.
Description
H.28700 10~304~
THIS INVENTION relates to the treatment of residues obtained in the manufacture of adipic acid by the nitric acid oxidation of cyclohexanol or cyclo-hexanone or mixtures thereof, and to methods of obtaining acids and esters from the said residues.
Adipic acid is commonly made by the oxidation of cyclohexanol or cyclohexanone with nitric acid.
More particularly it may be made by nitric acid oxid-ation of the mixture of products resulting from the 10 air oxidation of cyclohexane. Such a mixture consists of cyclohexanol and cyclohexanone in varying proportions, depending on the conditions of the air oxidation, together with other constituents, and is commonly referred to as 'KA'. Oxidation with nitric acid is 15 preferably effected in the presence of a metallic catalyst, a vanadium-copper catalyst being particularly suitable. Oxidation is effected at moderately elevated temperatures, for example at temperatures in the range 30 to 85C.
When oxidation is complete the reaction mixture is cooled and the crystallised adipic acid is separated.
The mother liquor, containing nitric acid, catalyst, adipic acid and impurities, is recycled for re-use in the process after bringing the nitric acid up to its ; 25 original strength. However, c~ntinual recycle of the mother liquor leads to the build-up of impurities in the~reaction m1xture to an unacceptable level, and it is therefore nec`eRsary to t ke a purge of the mother :
:
H.28700 10~3049 liquor ~rom time to time in order to control the impurity level.
This invention is concerned with the treatment of that part of the mother liquor which is taken as a purge. Apart from nitric acid, catalyst and residual adipic acid, the principal constituents of the purge are succinic acid and glutaric acid. There have been various proposals for tre&ting the purge in order to isolate use~ul components from it in a relatively pure state whether for recycle to the oxidation process or not.
Nitric acid is commonly removed by evaporation, advant-ageously under reduced pressure, as the first step. In order to assist in the removal of the nitric acid and the decomposition of metal nitrates (from the catalyst metals) it is often preferred to add a non-volatile mineral acid such as sulphuric acid or phosphoric acid prior to the evaporation step so converting the catalyst metals on heating to their sulphates or other non-nitrate salts.
~ After the removal of nitric acid by evaporation adipic acid may be allowed to crystallise in the residue and be separated. The adipic acid so obtained may be recycled to the oxidation or otherwise made use of with ' or without further preliminary refining treatment. The residue remaining after separating this adipic acid is known as purge waste acid and, though it rnay be disposed of to waste it is commonly treated to recover at least some of the constituents, which still include adipic acid, as well as succinic acid, glutaric acid and catalyst metals.
.
H.28700 10~30~9 There have been many proposals to make use o~
the adipic, glutaric and succinic acids in the residue, for example by separating all or some of the constituents from the mixture, by using the mixed acids as such, or by converting the mixed acids to derivatives, especially to esters, and either using the mixed derivatives or separating the individual constituents. In most cases it is necessary at some stage to separate the catalyst metals since otherwise they may impair the properties of the organic products, particularly the colour.
Separation of the catalyst metals is not always straight-forward, however, and separation difficulties may lead to losses of valuable organic products.
We have now found a method for treating the residue comprising salts of catalyst metals and adipic, glutaric and succinic acids whereby the said metal salts can be separated easily and cleanly.
According to our invention we provide a process for the separation of catalyst metals from the residue remaining after the separation of solid adipic acid and nitric acid from the product of the nitric acid - ~ ~
oxidation of cyclohexanol, cyclohexanone, mixtures thereof or mixtures containing them, in the presence of a metallic catalyst, the said residue comprising salts of catalyst metals and adipic, glutaric and succinic acids and being substantially free of water, which process comprises mixing the said residue in molten form with an alcohol having from 6 to 13 carbon atoms, main-.
1093049 H.28700 taining the mixture at a temperature within the range50 to 120C to effect partial esterification of the organic acids and until the mixture consists of two liquid phases, namely an aqueous phase comprising the catalyst metal salts dissolved in the water formed in the partial esterification and an organic phase comprising the organic acids, the alcohol and the esters formed in the partial esterification, and separating the aqueous phase from the organic phase.
The mixture of aqueous and organic phases may be separated hot, at or near the temperature of partial esterification or it may be cooled prior to their separation, conveniently to around ambient temperature, for example from 10 to 30C. In our separation process esterification is continued until sufficient water of esterification has been produced to form a separate aqueous phase and to dissolve the catalyst metal salts. For this purpose it is usually nece~sary to esterify a minimum of about 30% of the carboxylic acid equivalents present in the residue to be treated.
In many cases our separation process will be used in conjunction with a process for the manufacture of di-esters of mixed adipic, glutaric and succinic acids with alcohols, especially alcohols having from 6 to 13 carbon atoms, and more especially the same alcohol ; as is used in our separation process. However, although .. . .
10~3~49 H.28700 a minor proportion of the desired di-ester may be formed in our separation process, we prefer not to esterify more than a limited proportion of the mixed organic acids prior to the separation of the catalyst metals, and in general not more than 70% o~ the carboxylic acid equivalents should be esterified prior to separation.
- After separation, where it is desired to - esterify the remaining proportion of organic acids in the organic phase, the said organic phase, then consisting of the acids dissolved in the alcohol together with a proportion of ester, can be treated so as to form substantially all di-ester by standard esterification procedures, for example by heating the liquid, if necessary after adding more alcohol and optionally after addition of an ésterification catalyst,and removing the water formed, for example : by azeotropic distillation wlth the alcohol, and optionally returning the alcohol to the esterification liquid after separation of the water.
: ~ Thus a further feature of our invention is a ~ process for the manufacture of di-esters of alcohols .
~ ~ having from 6 to 13 carbon atoms with mixed adipic, `: : : glutaric and succinic acids which comprises mixing a ; 25 residue, comprising salts of catalyst metals and adipic, glutaric and succinic acids and being subst-~ ~ antially free of water~in molten form with the said : ~ alcohol, maintaining the mixture at a temperature ; within the range 50 to 120C to effect partial ~ - 6 -' ::
10~3~49 H.28700 esterification of the organic acids and until the mixture consists of two liquid phases, namely an aqueous phase comprising the catalyst metal salts dissolved in the water formed in the partial ester-ification and an organic phase comprising the organicacids, the alcohol and the esters formed in the partial esterification, separating the aqueous phase from the organic phase and substantially completing the esterification of the organic acids in the organic phase, the said residue being that remaining a~ter the separation of solid adipic acid and nitric acid from the product of the nitric acid oxidation of cyclohexanol, cyclohexanone, mixtures thereof or mixtures containing them in the presnece of a metallic catalyst.
The alcohol having from 6 to 13 carbon atoms used in the separation process of our invention is preferably an aliphatic alcohol and more preferably an alkanol. Primary alcohols are also preferred. Thus --very suitable alcohols are hexanols, heptanols, octanols, nonanols, decanols, undecanols, dodecanols and tridecanols.
Pàrticularly suitable are the usually branched chain :,:
alcohols or mixtures of such alcohols obtained by reacting olefins or mixtures of olefins of appropriate chain length with carbon monoxide and hydrogen in presence of a h~droformylation catalyst ~nd converting the product to the alcohol. As examples of such alcohols there may be mentioned iso-octanol, nonanol, , , . ~ :
.
IV~30~9 H.28700 isodecanol, and tridecanol.
With regard to the amount of alcohol which maybe used in the separation process of our invention we prefer to use at least l mole per mole of organic acid present in the residue but larger quantities, for example up to 5 moles or more, may conveniently be used. Where the separation is to precede complete esterification of the organic acids with the alcohol the proportion of alcohol in the final esterification is preferably within the range 2 to 2.5 moles per mole or organic acid, more preferably 2.15 to 2.25 moles.
Where necessary these levels may be achieved by adding additional aloohol after the separation stage.
The residue is in molten form when it is mixed with the alcohol. It is an advantage of our process that the residue is most conveniently handled in molten form, slnce handling in solid form can lead to the formation of dust and other difficulties. The dust, containlng the catalystrmetals, is toxic. More-20~ over, the residue, arising from the preliminary treat-~ment~of the purge already detailed, is normally already in;mol~en form and our process avoids the difficulty and expense of ha~ing to solidify and crush or flake ;the residue. The molten residue is typically at a 25~ temperature withln the range 120 to 160C.
After mlxlng the molten resldue with the alcohol ~; ~ the mixture is maintained within the temperature range speoified in our prooess until the mixture consists of 10~30~9 an organic and aqueous phase containing the catalyst metal salts in solution. The temperature and time required to achieve this condition will depend on various factors, in particular on the organic and inorganic acid content of the residue and on the particular alcohol or mixture of alcohols used. Typical treatment conditions are at 80 to 100C per from 1 to 5 hours, for example at 90C for 2 hours. In order to achieve the desired temperature on mixing it may be necessary to pre-heat the alcohol to an appropriate temperature. Agitation is preferably used to ensure rapid mixing.
After the desired degree of reaction is achieved the catalyst metal salts in aqueous solution are separated from the organic liquid phase. Separation may be effected at or about the temperature at which the mixture is held or after cooling. The separated catalyst metal salts may be discarded or may be recovered for re-use in the nitric acid oxidation of cyclohexanol and/or cyclohexanone, or for other purposes. The single liquid phase remaining may be used for the recovery of the organic acids contai n~d therein. We prefer, however, to convert the organic acids into their di-esters with the alcohol by methods such as have already been indicated.
Prior to such esterification, however, the single liquid phase may be stored or transported, for example in tankers, since it is relatively stable and non-corrosive to stain-` less steel.
The esters of mixed adipic, glutaric andsuccinic acids wlth alcohols of from 6 to 13 car~on ' , , _ g _ :
`::
- `
H.28700 atoms are useful as plasticisers. They are partic-ularly suitable for use in this application in admixture with phthalate esters of similar alcohols.
The method of making esters of alcohols having from 6 to l~ carbon atoms with mixed adipic, glutaric and succinic acids according to our invention has a number of advantages over prior processes for making such esters from residue as defined, especially the process whereby the residue is allowed to solidify and is then esterified. In the first place the esters prepared by the process of our invention have a better colour, that is are less discoloured, than esters produced from the solidified residue. Typically esters produced by the process of our invention have a colour of about 50 Hazen units whereas esters produced by esterification of solidlfied residue have a colour of from lO0 to 250 Hazen units and are brown to dark brown in colour.
Next, the residue used in the esterification Z0~ normally contains about 1% of non-volatile mineral acid, usually sulphuric acid, added to assist in removing the nltric acld at an earlier stage. During the esterification process of our invention such sulphuric acid is largeIy removed du~ing the separation ; 25 step along with the water and the~catalyst metals.
(Typically the sulphuric acid content of the remainirlK
esterification mixture is 0.04% by weight). In the final esterification step of our invention in which ~: :
~093049 H.28700 the esterification of the mixed acid~ is completed it will normally be necessary to add an esterification catalyst, but this can be, unlike sulphuric acid, a relatively non-corrosive catalyst such as p-toluene sulphonic acid. When the solid residue is used in the esterification, however, the residual sulphuric acid is not removed, and although this sulphuric acid wiIl function as an esterification catalyst, it can under certain circumstances, e.g. when air gains access to the esterification vessel, lead to darkening of the ester.
A further advantage of our process is that an effluent problem can be avoided. Since the separation process of our invention is carried out on the residue in molten form it is most conveniently carried out at the place where the molten residue is produced. The catalyst metals separated with the water of partial esterification can then be recycled for use as catalyst in the nitric acid ZO oxldation of cyclohexanol and/or cyclohexanone from which the residue arises. In the case of the esterification of the solidified re~idue, however, this may well be effected at a different place and then the disposal of the catalyst metals, which are ~;~ 25 ~enerally toxic, may present a problem.
Another advantage of our process is the ` avoidance of difficulties which arise when the ~inal :
~ esterification takes place in presence of the catalyst .
.. . . . . . .
1093049 H.28700 metals as it does when the solidified residue is u.sed for esterification. In esterifications gener-ally it is useful to effect the esterification in a vessel capable of withstanding vacuum, and to effect the subsequent neutralisation and washing in a I
separate vessel, which is larger to accommodate the washing and neutralisation liquors, and operates at atmospheric pressure. When esterifying the solidified residue, however, the catalyst metals, which have not been removed, coat the walls of the esterification vessel with a gelatinous layer which can cause blockages and lead to progressively darker batches of ester. This problem can only be overcome by carrying out the washing and neutralisation stages in the same vessel, but this is inconvenient and necessitates the use of an esterlfication vessel larger than would otherwise be necessary. In contrast, in our process there are virtually no catalyst metals present in the final esterification, and these problems do not arise. Only trace amounts of these metals (less than l p.p.m. of each of copper and vanadium) are present in the final esterification ,: : . .
Finally, as already mentioned, the handling of ` solidified residue is hazardous due to the toxic metals present in the dust which is inevitably produced.
Handling the residue in molten form according to our process avoids these hazards.
The invention is illustrated but not limited by " -",, ' -3049~ ~. 28700 the following Examples.
Exam~le 1 A molten residue at 150C containing 1 mole of mixed adipic, glutaric and succinic acid (in the approximate molar ratio of o.66 : 2 : 1) and mixed vanadium and copper sulphates was run into 2.2 moles of agitated iso-octanol previously heated to 60C
The temperature of the mixture was 90C and after agitating for two hours an aqueous phase containing dissolved vanadium and copper sulphates was allowed to separate and run off. The organic phase was used for the preparation of the mixed is~ octyl esters of adipic, glutaric and succinic acids by standard procedures.
Example 2 .
The separation process of Example 1 was repeated.
To the separated organic phase 0.3% by weight of p-toluene sulphonic acid and O.Z5% by weight of activated carbon were added and the mixture was heated with agitation to 115C in a stainless steel ~essel under a nitrogen atmosphere. The mixture was maintained under reflux by gradually reducing the pressure in the vessel to 133 millibars, When esterification was complete the pressure was allowed to rise to that of : :
Z5 the atmos~phere and heating was discontinued. The ester was transferred via a filter to a separate vessel, neutralised with sodium hydroxide, washed with .
`
1093049 H.28700 water, and unchanged alcohol removed by vacuum steam distillation. The ester was finally treated with 0.25% by weight of activated carbon at 70C and filtered. The colour of the finished ester was 50 Hazen units.
When the same esterification procedure of this Example was applied to the residue used in Example l after it had been allowed to solidify an ester having a colour of 200 Hazen units was obtained.
Example 3 The process of Example 2 was repeated, except that the alcohol listed in the following Table was used in place of iso-octanol.
The esters had the colours, in Hazen units, indicated.
Alcohol Colour of Ester (Hazen units?
A commercial mixture of C7, C8 and Cg alcohols in 50 the-weight ratio 45:40:15 Nonanol 40 ::
~ ` Iso-decanol 60 :
~ .
.
THIS INVENTION relates to the treatment of residues obtained in the manufacture of adipic acid by the nitric acid oxidation of cyclohexanol or cyclo-hexanone or mixtures thereof, and to methods of obtaining acids and esters from the said residues.
Adipic acid is commonly made by the oxidation of cyclohexanol or cyclohexanone with nitric acid.
More particularly it may be made by nitric acid oxid-ation of the mixture of products resulting from the 10 air oxidation of cyclohexane. Such a mixture consists of cyclohexanol and cyclohexanone in varying proportions, depending on the conditions of the air oxidation, together with other constituents, and is commonly referred to as 'KA'. Oxidation with nitric acid is 15 preferably effected in the presence of a metallic catalyst, a vanadium-copper catalyst being particularly suitable. Oxidation is effected at moderately elevated temperatures, for example at temperatures in the range 30 to 85C.
When oxidation is complete the reaction mixture is cooled and the crystallised adipic acid is separated.
The mother liquor, containing nitric acid, catalyst, adipic acid and impurities, is recycled for re-use in the process after bringing the nitric acid up to its ; 25 original strength. However, c~ntinual recycle of the mother liquor leads to the build-up of impurities in the~reaction m1xture to an unacceptable level, and it is therefore nec`eRsary to t ke a purge of the mother :
:
H.28700 10~3049 liquor ~rom time to time in order to control the impurity level.
This invention is concerned with the treatment of that part of the mother liquor which is taken as a purge. Apart from nitric acid, catalyst and residual adipic acid, the principal constituents of the purge are succinic acid and glutaric acid. There have been various proposals for tre&ting the purge in order to isolate use~ul components from it in a relatively pure state whether for recycle to the oxidation process or not.
Nitric acid is commonly removed by evaporation, advant-ageously under reduced pressure, as the first step. In order to assist in the removal of the nitric acid and the decomposition of metal nitrates (from the catalyst metals) it is often preferred to add a non-volatile mineral acid such as sulphuric acid or phosphoric acid prior to the evaporation step so converting the catalyst metals on heating to their sulphates or other non-nitrate salts.
~ After the removal of nitric acid by evaporation adipic acid may be allowed to crystallise in the residue and be separated. The adipic acid so obtained may be recycled to the oxidation or otherwise made use of with ' or without further preliminary refining treatment. The residue remaining after separating this adipic acid is known as purge waste acid and, though it rnay be disposed of to waste it is commonly treated to recover at least some of the constituents, which still include adipic acid, as well as succinic acid, glutaric acid and catalyst metals.
.
H.28700 10~30~9 There have been many proposals to make use o~
the adipic, glutaric and succinic acids in the residue, for example by separating all or some of the constituents from the mixture, by using the mixed acids as such, or by converting the mixed acids to derivatives, especially to esters, and either using the mixed derivatives or separating the individual constituents. In most cases it is necessary at some stage to separate the catalyst metals since otherwise they may impair the properties of the organic products, particularly the colour.
Separation of the catalyst metals is not always straight-forward, however, and separation difficulties may lead to losses of valuable organic products.
We have now found a method for treating the residue comprising salts of catalyst metals and adipic, glutaric and succinic acids whereby the said metal salts can be separated easily and cleanly.
According to our invention we provide a process for the separation of catalyst metals from the residue remaining after the separation of solid adipic acid and nitric acid from the product of the nitric acid - ~ ~
oxidation of cyclohexanol, cyclohexanone, mixtures thereof or mixtures containing them, in the presence of a metallic catalyst, the said residue comprising salts of catalyst metals and adipic, glutaric and succinic acids and being substantially free of water, which process comprises mixing the said residue in molten form with an alcohol having from 6 to 13 carbon atoms, main-.
1093049 H.28700 taining the mixture at a temperature within the range50 to 120C to effect partial esterification of the organic acids and until the mixture consists of two liquid phases, namely an aqueous phase comprising the catalyst metal salts dissolved in the water formed in the partial esterification and an organic phase comprising the organic acids, the alcohol and the esters formed in the partial esterification, and separating the aqueous phase from the organic phase.
The mixture of aqueous and organic phases may be separated hot, at or near the temperature of partial esterification or it may be cooled prior to their separation, conveniently to around ambient temperature, for example from 10 to 30C. In our separation process esterification is continued until sufficient water of esterification has been produced to form a separate aqueous phase and to dissolve the catalyst metal salts. For this purpose it is usually nece~sary to esterify a minimum of about 30% of the carboxylic acid equivalents present in the residue to be treated.
In many cases our separation process will be used in conjunction with a process for the manufacture of di-esters of mixed adipic, glutaric and succinic acids with alcohols, especially alcohols having from 6 to 13 carbon atoms, and more especially the same alcohol ; as is used in our separation process. However, although .. . .
10~3~49 H.28700 a minor proportion of the desired di-ester may be formed in our separation process, we prefer not to esterify more than a limited proportion of the mixed organic acids prior to the separation of the catalyst metals, and in general not more than 70% o~ the carboxylic acid equivalents should be esterified prior to separation.
- After separation, where it is desired to - esterify the remaining proportion of organic acids in the organic phase, the said organic phase, then consisting of the acids dissolved in the alcohol together with a proportion of ester, can be treated so as to form substantially all di-ester by standard esterification procedures, for example by heating the liquid, if necessary after adding more alcohol and optionally after addition of an ésterification catalyst,and removing the water formed, for example : by azeotropic distillation wlth the alcohol, and optionally returning the alcohol to the esterification liquid after separation of the water.
: ~ Thus a further feature of our invention is a ~ process for the manufacture of di-esters of alcohols .
~ ~ having from 6 to 13 carbon atoms with mixed adipic, `: : : glutaric and succinic acids which comprises mixing a ; 25 residue, comprising salts of catalyst metals and adipic, glutaric and succinic acids and being subst-~ ~ antially free of water~in molten form with the said : ~ alcohol, maintaining the mixture at a temperature ; within the range 50 to 120C to effect partial ~ - 6 -' ::
10~3~49 H.28700 esterification of the organic acids and until the mixture consists of two liquid phases, namely an aqueous phase comprising the catalyst metal salts dissolved in the water formed in the partial ester-ification and an organic phase comprising the organicacids, the alcohol and the esters formed in the partial esterification, separating the aqueous phase from the organic phase and substantially completing the esterification of the organic acids in the organic phase, the said residue being that remaining a~ter the separation of solid adipic acid and nitric acid from the product of the nitric acid oxidation of cyclohexanol, cyclohexanone, mixtures thereof or mixtures containing them in the presnece of a metallic catalyst.
The alcohol having from 6 to 13 carbon atoms used in the separation process of our invention is preferably an aliphatic alcohol and more preferably an alkanol. Primary alcohols are also preferred. Thus --very suitable alcohols are hexanols, heptanols, octanols, nonanols, decanols, undecanols, dodecanols and tridecanols.
Pàrticularly suitable are the usually branched chain :,:
alcohols or mixtures of such alcohols obtained by reacting olefins or mixtures of olefins of appropriate chain length with carbon monoxide and hydrogen in presence of a h~droformylation catalyst ~nd converting the product to the alcohol. As examples of such alcohols there may be mentioned iso-octanol, nonanol, , , . ~ :
.
IV~30~9 H.28700 isodecanol, and tridecanol.
With regard to the amount of alcohol which maybe used in the separation process of our invention we prefer to use at least l mole per mole of organic acid present in the residue but larger quantities, for example up to 5 moles or more, may conveniently be used. Where the separation is to precede complete esterification of the organic acids with the alcohol the proportion of alcohol in the final esterification is preferably within the range 2 to 2.5 moles per mole or organic acid, more preferably 2.15 to 2.25 moles.
Where necessary these levels may be achieved by adding additional aloohol after the separation stage.
The residue is in molten form when it is mixed with the alcohol. It is an advantage of our process that the residue is most conveniently handled in molten form, slnce handling in solid form can lead to the formation of dust and other difficulties. The dust, containlng the catalystrmetals, is toxic. More-20~ over, the residue, arising from the preliminary treat-~ment~of the purge already detailed, is normally already in;mol~en form and our process avoids the difficulty and expense of ha~ing to solidify and crush or flake ;the residue. The molten residue is typically at a 25~ temperature withln the range 120 to 160C.
After mlxlng the molten resldue with the alcohol ~; ~ the mixture is maintained within the temperature range speoified in our prooess until the mixture consists of 10~30~9 an organic and aqueous phase containing the catalyst metal salts in solution. The temperature and time required to achieve this condition will depend on various factors, in particular on the organic and inorganic acid content of the residue and on the particular alcohol or mixture of alcohols used. Typical treatment conditions are at 80 to 100C per from 1 to 5 hours, for example at 90C for 2 hours. In order to achieve the desired temperature on mixing it may be necessary to pre-heat the alcohol to an appropriate temperature. Agitation is preferably used to ensure rapid mixing.
After the desired degree of reaction is achieved the catalyst metal salts in aqueous solution are separated from the organic liquid phase. Separation may be effected at or about the temperature at which the mixture is held or after cooling. The separated catalyst metal salts may be discarded or may be recovered for re-use in the nitric acid oxidation of cyclohexanol and/or cyclohexanone, or for other purposes. The single liquid phase remaining may be used for the recovery of the organic acids contai n~d therein. We prefer, however, to convert the organic acids into their di-esters with the alcohol by methods such as have already been indicated.
Prior to such esterification, however, the single liquid phase may be stored or transported, for example in tankers, since it is relatively stable and non-corrosive to stain-` less steel.
The esters of mixed adipic, glutaric andsuccinic acids wlth alcohols of from 6 to 13 car~on ' , , _ g _ :
`::
- `
H.28700 atoms are useful as plasticisers. They are partic-ularly suitable for use in this application in admixture with phthalate esters of similar alcohols.
The method of making esters of alcohols having from 6 to l~ carbon atoms with mixed adipic, glutaric and succinic acids according to our invention has a number of advantages over prior processes for making such esters from residue as defined, especially the process whereby the residue is allowed to solidify and is then esterified. In the first place the esters prepared by the process of our invention have a better colour, that is are less discoloured, than esters produced from the solidified residue. Typically esters produced by the process of our invention have a colour of about 50 Hazen units whereas esters produced by esterification of solidlfied residue have a colour of from lO0 to 250 Hazen units and are brown to dark brown in colour.
Next, the residue used in the esterification Z0~ normally contains about 1% of non-volatile mineral acid, usually sulphuric acid, added to assist in removing the nltric acld at an earlier stage. During the esterification process of our invention such sulphuric acid is largeIy removed du~ing the separation ; 25 step along with the water and the~catalyst metals.
(Typically the sulphuric acid content of the remainirlK
esterification mixture is 0.04% by weight). In the final esterification step of our invention in which ~: :
~093049 H.28700 the esterification of the mixed acid~ is completed it will normally be necessary to add an esterification catalyst, but this can be, unlike sulphuric acid, a relatively non-corrosive catalyst such as p-toluene sulphonic acid. When the solid residue is used in the esterification, however, the residual sulphuric acid is not removed, and although this sulphuric acid wiIl function as an esterification catalyst, it can under certain circumstances, e.g. when air gains access to the esterification vessel, lead to darkening of the ester.
A further advantage of our process is that an effluent problem can be avoided. Since the separation process of our invention is carried out on the residue in molten form it is most conveniently carried out at the place where the molten residue is produced. The catalyst metals separated with the water of partial esterification can then be recycled for use as catalyst in the nitric acid ZO oxldation of cyclohexanol and/or cyclohexanone from which the residue arises. In the case of the esterification of the solidified re~idue, however, this may well be effected at a different place and then the disposal of the catalyst metals, which are ~;~ 25 ~enerally toxic, may present a problem.
Another advantage of our process is the ` avoidance of difficulties which arise when the ~inal :
~ esterification takes place in presence of the catalyst .
.. . . . . . .
1093049 H.28700 metals as it does when the solidified residue is u.sed for esterification. In esterifications gener-ally it is useful to effect the esterification in a vessel capable of withstanding vacuum, and to effect the subsequent neutralisation and washing in a I
separate vessel, which is larger to accommodate the washing and neutralisation liquors, and operates at atmospheric pressure. When esterifying the solidified residue, however, the catalyst metals, which have not been removed, coat the walls of the esterification vessel with a gelatinous layer which can cause blockages and lead to progressively darker batches of ester. This problem can only be overcome by carrying out the washing and neutralisation stages in the same vessel, but this is inconvenient and necessitates the use of an esterlfication vessel larger than would otherwise be necessary. In contrast, in our process there are virtually no catalyst metals present in the final esterification, and these problems do not arise. Only trace amounts of these metals (less than l p.p.m. of each of copper and vanadium) are present in the final esterification ,: : . .
Finally, as already mentioned, the handling of ` solidified residue is hazardous due to the toxic metals present in the dust which is inevitably produced.
Handling the residue in molten form according to our process avoids these hazards.
The invention is illustrated but not limited by " -",, ' -3049~ ~. 28700 the following Examples.
Exam~le 1 A molten residue at 150C containing 1 mole of mixed adipic, glutaric and succinic acid (in the approximate molar ratio of o.66 : 2 : 1) and mixed vanadium and copper sulphates was run into 2.2 moles of agitated iso-octanol previously heated to 60C
The temperature of the mixture was 90C and after agitating for two hours an aqueous phase containing dissolved vanadium and copper sulphates was allowed to separate and run off. The organic phase was used for the preparation of the mixed is~ octyl esters of adipic, glutaric and succinic acids by standard procedures.
Example 2 .
The separation process of Example 1 was repeated.
To the separated organic phase 0.3% by weight of p-toluene sulphonic acid and O.Z5% by weight of activated carbon were added and the mixture was heated with agitation to 115C in a stainless steel ~essel under a nitrogen atmosphere. The mixture was maintained under reflux by gradually reducing the pressure in the vessel to 133 millibars, When esterification was complete the pressure was allowed to rise to that of : :
Z5 the atmos~phere and heating was discontinued. The ester was transferred via a filter to a separate vessel, neutralised with sodium hydroxide, washed with .
`
1093049 H.28700 water, and unchanged alcohol removed by vacuum steam distillation. The ester was finally treated with 0.25% by weight of activated carbon at 70C and filtered. The colour of the finished ester was 50 Hazen units.
When the same esterification procedure of this Example was applied to the residue used in Example l after it had been allowed to solidify an ester having a colour of 200 Hazen units was obtained.
Example 3 The process of Example 2 was repeated, except that the alcohol listed in the following Table was used in place of iso-octanol.
The esters had the colours, in Hazen units, indicated.
Alcohol Colour of Ester (Hazen units?
A commercial mixture of C7, C8 and Cg alcohols in 50 the-weight ratio 45:40:15 Nonanol 40 ::
~ ` Iso-decanol 60 :
~ .
.
Claims (10)
1. A process for the separation of catalyst metals from the residue remaining after the separation of solid adipic acid and nitric acid from the product of the nitric acid oxidation of cyclohexanol, cyclohexanone, mixtures thereof or mixtures containing them, in the presence of a metallic catalyst, the said residue comprising salts of catalyst metals and adipic, glutaric and succinic acids and being substantially free of water, which process comprises mixing the said residue in molten form with an alcohol having from 6 to 13 carbon atoms, maintaining the mixture at a temperature within the range 50° to 120°C to effect partial esterification of the organic acids and until the mixture Consists of two liquid phases, namely an aqueous phase comprising the catalyst metal salts dissolved in the water formed in the partial esterification and an organic phase comprising the organic acids, the alcohol and the esters formed in the partial esterification, and separating the aqueous phase from the organic phase.
2. The process of Claim 1 in which, after separating the aqueous phase, the esterification of the organic acids in the organic phase is substantially completed to give diesters of alcohols having from 6 to 13 carbon atoms with mixed adipic, glutaric and succinic acids.
3. The process of Claim 1 in which, in the partial esterification, at least 30% of the carboxylic acid equiv-alents present in the said residue is esterified.
4. The process of Claim 1 in which, in the partial esterification, not more than 70% of the carboxylic acid equivalents present in the said residue is esterified.
5. The process of Claim 1 in which the mixture of molten residue and alcohol is maintained at a temperature of 80° to 100°C for from 1 to 5 hours prior to separation of the liquid phases.
6. The process of Claim 1 in which from 1 to 5 moles of alcohol are used per mole of organic acid present in the said residue.
7. The process of Claim 2 in which from 2 to 2,5 moles of alcohol are used during completion of the ester-ification per mole or organic acid present in the said residue.
8. The process of Claim 7 in which from 2.15 to 2.25 moles of alcohol are used during completion of the esterification per mole of organic acid present in the said residue.
9. The process of Claim 1 in which the alcohol is iso-octanol, nonanol or isodecanol.
10. The process of Claim 2 in which the organic phase separated after the partial esterification is stored or transported prior to completing the esterification.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB14759/76A GB1511438A (en) | 1976-04-12 | 1976-04-12 | Treatment of residues from the oxidation process for the preparation of adipic acid |
| GB14759/76 | 1976-04-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1093049A true CA1093049A (en) | 1981-01-06 |
Family
ID=10046986
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA276,005A Expired CA1093049A (en) | 1976-04-12 | 1977-04-12 | Residue treatment process |
Country Status (8)
| Country | Link |
|---|---|
| JP (1) | JPS52125111A (en) |
| BE (1) | BE853274A (en) |
| CA (1) | CA1093049A (en) |
| DE (1) | DE2715293A1 (en) |
| FR (1) | FR2347977A1 (en) |
| GB (1) | GB1511438A (en) |
| IT (1) | IT1125770B (en) |
| NL (1) | NL7703376A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE3047250A1 (en) * | 1979-12-18 | 1981-09-24 | Agustín Vitoria Arana Eraña | MOLDING SANDING MACHINE |
| US5420336A (en) * | 1994-11-02 | 1995-05-30 | E. I. Du Pont De Nemours And Company | Catalyst recovery and dialkyl ester synthesis |
| TWI238157B (en) * | 2001-01-25 | 2005-08-21 | Asahi Kasei Corp | Process for producing alkanedicarboxylic acid |
-
1976
- 1976-04-12 GB GB14759/76A patent/GB1511438A/en not_active Expired
-
1977
- 1977-03-29 NL NL7703376A patent/NL7703376A/en unknown
- 1977-04-05 BE BE176449A patent/BE853274A/en not_active IP Right Cessation
- 1977-04-05 DE DE19772715293 patent/DE2715293A1/en active Granted
- 1977-04-08 FR FR7710831A patent/FR2347977A1/en active Granted
- 1977-04-08 IT IT22342/77A patent/IT1125770B/en active
- 1977-04-11 JP JP4126977A patent/JPS52125111A/en active Granted
- 1977-04-12 CA CA276,005A patent/CA1093049A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| GB1511438A (en) | 1978-05-17 |
| DE2715293A1 (en) | 1977-10-27 |
| DE2715293C2 (en) | 1988-06-16 |
| FR2347977A1 (en) | 1977-11-10 |
| IT1125770B (en) | 1986-05-14 |
| JPS52125111A (en) | 1977-10-20 |
| NL7703376A (en) | 1977-10-14 |
| BE853274A (en) | 1977-10-05 |
| JPS6220178B2 (en) | 1987-05-06 |
| FR2347977B1 (en) | 1981-12-11 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US4076948A (en) | Process for treatment of adipic acid mother liquor | |
| US4164506A (en) | Process for producing lower alcohol esters of fatty acids | |
| US3120561A (en) | Production of terephthalic acid | |
| EP0181127B1 (en) | Recovery of metal catalyst residues and other useful products from therephthalic acid production | |
| RO120539B1 (en) | Process for preparing ester plasticizers | |
| US3818071A (en) | Reduction of acidity in the production of esters | |
| EP0463434B1 (en) | Method for the production of monoethylenically unsaturated carboxylic acid esters | |
| EP0707563B1 (en) | Production of dicarboxylic acids or esters thereof | |
| CA1093049A (en) | Residue treatment process | |
| US4883904A (en) | Process for the preparation of ethyltrifluoroacetoacetate | |
| CA1140584A (en) | Treatment of waste stream from adipic acid manufacture | |
| US4659682A (en) | Recovery of noble metal values from carbonylation residues | |
| US4105856A (en) | Recovery process for aqueous waste streams in adipic acid systems | |
| US5756413A (en) | Process for recovering cobalt carbonyl catalysts used in the preparation of N-acyl-α-amino acid derivates by amidocarbonylation | |
| US4442303A (en) | Recovery of water miscible organic acids from aqueous solution as alkyl esters | |
| US3000918A (en) | Vinyl ester synthesis | |
| MXPA96006201A (en) | Procedure to recover the decobalite carbonils employed as catalysts in the preparation of n-acil-alpha-amino acids poramidocarbonilac | |
| US2918487A (en) | Process for producing dibasic acids | |
| EP0686622A1 (en) | Removal of carbonyl impurities from alpha, beta-unsaturated carboxylic acid esters | |
| US3117145A (en) | Method of purifying vinyl esters of organic carboxylic acids | |
| US3337641A (en) | Process for the purification of impure 2, 6-dimethylphenol containing cresols as impurities | |
| US4760166A (en) | Purification of diphenyl phthalates | |
| EP0789682B1 (en) | Catalyst recovery and dialkyl ester synthesis from an adipic acid synthesis waste stream | |
| CN1232878A (en) | Process for recovering rhodium catalyst | |
| EP0343042A1 (en) | Process for the preparation of alkyl malonates |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |