CA1230611A - Process for the preparation of mixtures of acetic acid, propionic acid and butyric acid - Google Patents
Process for the preparation of mixtures of acetic acid, propionic acid and butyric acidInfo
- Publication number
- CA1230611A CA1230611A CA000454541A CA454541A CA1230611A CA 1230611 A CA1230611 A CA 1230611A CA 000454541 A CA000454541 A CA 000454541A CA 454541 A CA454541 A CA 454541A CA 1230611 A CA1230611 A CA 1230611A
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- Prior art keywords
- acid
- oxidation
- oxygen
- mixtures
- gas
- Prior art date
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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
- C07C51/21—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen
- C07C51/23—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups
- C07C51/235—Preparation of carboxylic acids or their salts, halides or anhydrides by oxidation with molecular oxygen of oxygen-containing groups to carboxyl groups of —CHO groups or primary alcohol groups
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C51/00—Preparation of carboxylic acids or their salts, halides or anhydrides
- C07C51/10—Preparation of carboxylic acids or their salts, halides or anhydrides by reaction with carbon monoxide
Abstract
Abstract of the Disclosure The invention relates to a process for the preparation of mixtures of acetic acid, propionic acid and butyric acid from synthesis gas. In this process, the syntilesis gas is first passed over a rhodium cata-lyst containing, as a promoter, at least one compound of Mg, Mn, La, a rare-earth metal, Sc, Y, W, Fe, Zr, Cr, Hf, Pt and U, and also, as an activator, at least one compound of an alkali metal. The reaction product is condensed, and the aqueous phase of the condensate is oxidized with oxygen or an, oxygen-containing gas in the presence of a platinum catalyst at a pH ? 7.
Description
2 - HOE 83/F 085 he present invention relaxes to a process for the preparation of mixtures of acetic acid, prop;onic acid and butyric acid.
Mixtures of oxygen containing compounds are ox-twined, in the form of an aqueous phase, in the hydra-genation of CO over heterogeneous rhodium catalysts in accordance with German Offenlegungsschriften ~,~14,365r 2,712,732, 2,846,148, 2,924~62 and 3,038,44~.
Furthermore, it has already been described in German Patent Application P 3,203,060.6 that oxygen-containing compounds can be obtained with an extremely high degree of selectivity by using rhodium catalysts containing compounds of the rare-earth metals and of the alkali metals. For example, redrill catalysts doped with ytterbium and lithium compounds are distinguished by a high selectivity and a virtually unlimited lye A
condensate having a high content (up to more than 70% by weight) ox oxygen-containing compounds is prosody This contains a surprisingly high proportion of acetic avid and, in addition, mainly acetaldehyde, ethanol end ethyl acetate. In addition, further oxygen-contain;ng corn-pounds continuing three or more carbon atoms, such as propionaldehyde, butyraldehyde, n propanol, n-butanol, propel acetate and bottle acetate, are obtained in a total order of magnitude of up to 5% by islet>
It us hardly possible to carry out ct)rlplete separation of the mixture by distillation oh;r,g o the . , , I
.
I
large number of azeotrope~ formed Also on the other hand, not all of the products mentioned are of great industrial interest. In addition, difficulties are en-countered, as us known, in using efficiently a large number of linked products.
It was therefore required to simplify the pro-duct spectrum on such a Jay that only durable products of industrial interest remain.
It has no been found that the product spectrum can be substantially simplified by oxidation in the liquid phase over a heterogeneous platinum catalyst so that only the intermediate products acetic acid, pro-phonic acid and butyric acid, which are very important for the chemical industry, are obtained.
The invention relates, therefore, to a process for the preparation of mixtures of acetic acid, prop no acid and butyr;c acid, which comprises reacting synthesis gas in the presence of a rhodium catalyst con-twinning, as a promoter, at least one compound of My, My La, a rare-earth metal, So, I w, Fez Or, Or, Hi, Pi and U and also, as an activator at least one compound of an Alec; metal, and subsequently condensing the reaction product and oxidizing the aqueous phase of the condemn-sate, if appropriate after removing the acetaldehyde, Thea oxygen or an oxygen-conta;n;ng gas in the presence of a platinum catalyst at a pi 7 and at an absolute pressure of 1 to 100 bar.
. In the first stage of the process according to the invention, carbon monoxide and hydrogen are reacted in a high degree of selectivity to give acetic acid, I
acetaldehyde and ethanol. In addition, small quintets are also formed of products which result from a second-cry reaction, for example esterifica~ion~ ace~alizat-ion or condensation These include, above all ethyl are-S late and the deathly acutely of acetaldehyde~ The prop-oration of other oxygen-contain;rlg compounds having three or more carbon atoms on the molecule us very small and is normally less than S mole X, relative to carbon monoxide which has reacted. The total selectivity of conversion to oxygen-containing C2 compounds, including products converted into ethyl acetate and acetaldehyde Doyle acutely, us up to I relative to carbon monoxide Shea has reacted The remainder of the carbon monoxide which has reacted us converted essentially into methane and other gaseous hydrocarbons and to a small extent, unto carbon dioxide.
Salts or complex compounds ox rhodium can be used 'as starting materials for making up the catalyst for the synthesis gas react;onO Rhodium can be present on the support in the form of metal or in a valence state below three that is to say as a complex compound of Covalent rhodium or as a salt or complex compound of univalent or d;valent rhodium. Suitable examples are chlorides, bromides and iodizes of rhodium or double salts of rhodium with alkali metal holidays such as for example, d;potass;urn trichlororhodate. Other suitable complex compounds are those which, in addition to rho-drum arid halogen also contain complex-form;nc~ ligands, such as tr;alkylphosph;l1es, triarylphosphines~ carbon ~.~3~6~
s monoxide olefins or plater, that is to say, for example tris-triphenylphosphine-rhodium-I chloride, bromide or iodide, iris triphenylphosphine-rhodium III chlorite, bus tri~o~tolylphosphine-rhodiurn~II chloride carbcnyl-b;s~tr;pher1ylphosph;ne-rhod;um-I Broadway or d;cesiumcar-bony pentachlororhodate~III. In addition, suitable compounds of rhodium are also those in high it is attached to a support in the form of an ion or complex.
Examples of these are zealots and ion exchangers in which replacement by rhodium halides has been carried out .
In addition to rhodium, the catalysts also con-lain promoters and activators. Compounds of the follow-no elements are employed as promoters: magnesium, man-Gaines, lanthanum, rare-earth metals (atomic number I
71), scandium, yttrium, tungsten, iron, zirconium, cry-mum, hafnium, platinum and uranium Examples of suit-able compounds are the chlorides, bromides, fluorides, nitrates, acetates, oxalates, acetylaeetonates or tar-trades. It us preferable to use the chlor;desr Brigham odes, acetates an acetylacetonates of these elemcn~s, above all the chlorides or bromides. Ytterbium, in the form of the compounds mentioned, is a particularly suit-able promoter.
The activators used are the oxides salts or COlDpl~X compounds of lithium, sodium, potassium, rub-drum or eczema or mixtures thereof, that is to say, for example, the oxides, hydroxides, carbonates, chlorides bromides, oxides n;tratesr awaits silicates Andre acuminates of the alkali metals Sodium compounds and lithium compounds, above all the latter, are preferred.
The catalyst supports used are customary support murals of varying specific surface area Supports having a specific surface area of So to 1000 mug are preferred, however. Suitable examples are silica, Nat fat or synthetic silicates of elements of the In to V~IIth group of the periodic system (that is to say, for exalnple, the silicates of masnes~um, calcium, aluminum or manganese), and also aluminum oxide thorium dioxide, zealots and spinets. It is preferable to use silica or silicates.
The catalysts are prepared by applying the rho-drum compound, the promoter and the activator to the support simultaneously or in successive stages in any desired sequence; this us generally effected by impreg-noting the support with solutions of the active components in suitable solvents, such as for example, water Alcoa hot, acetone, acutely acetone or acetic acid, and subset Z0 quaintly drying it.
It is also possible, however to ;ncorporatethe alkali metal and the promoters in a framework, for example a support substance containing celerity or aluminum oxide, such as slick, aluminum oxide or alum-nut silicate A further advantageous possible meanscons;sts on attaching the alkali metal or the promoters by means of ion exchange to cation exchangers which are also suitable as supports for the rhodium and are stable under the experimental conditions, for example tile natural or synthetic-alum;num silicates which are known as molecular sieves Preferably, the catalyst is also reduced before the start o-f the synthesis gas reaction. Examples of S suitable reducing agents are hydrogen, carbon monoxide, methanol or acetone. This reduction can be carried out in a separate apparatus or on the reactor itself. Rev diction is preferably carried out at temperatures below 300C, in particular between 100 and 275C. In many cases it is advantageous to carry out the reduction, not with the undiluted gases having a reducing action, but with an additional proportion of narrate gases, such as for example, nitrogen, carbon dockside or noble gases.
The concentration of rhodium, promoters and act t;vators on the catalysts can by varied thin wide limits; in general, relative to the metals the values are between 0.1 and 15% by weight for rhodium, between 0.1 and 20% by weight for the promoters and between 0.01 and 5% by weight or the alkali metals Catalysts continuing 1~0 to 10% by weight of rhodium and 0.1 to 10X by weight of promoters are preferred.
The synthesis gas reaction is carried out by passing over the catalyst gas mixtures worry are carp-sod entirely or predominantly of carbon monoxide and hydrogen and which can in add ton also contain, if appropriate, other components such as nitrogen argon, carbon Dodd or methane. The molar ratio of carbon monoxide to hydrogen on thus reaction can be varied within wide lots Molar ratio between So and 1:5 I
and especially button 3:1 and 1:3 are proofread In general, the reaction temperatures are bet-wren 175 and ~00C, preferably between 200 and 380C, and the reaction pressures are between 1 and 300 bar, preferably between 10 and 200 barn - It is advantageous to match the temperature and the pressure to one another in such a way as to ensure a high selectivity of conversion to the desired compounds and to keep at a Lowe level the exothermic formation of lo methane, Lucia is favored at elevated temperatures.
isle pressures and temperatures as logy as possible will, therefore, be preferred The gas phase us preferable for the synthesis gas reaction. The conventional fixed bed reactors can be used for thus purpose and it is a~ivantageQus to keep the layer thickness of the catalyst at a lo level in order to achieve better removal of heat Furthermore, reactors having a mobile catalyst bed or fluidized bed reactors are also suitable.
A particularly preferred embodiment of the sync thesis gas reaction consists in carrying it out in the gas phase on a gas circulation apparatus in itch, after the condensable reaction products have been removed the unreactcd gas mixture us recycles to the reactor This proceciure is particularly economical and naves it possible to achieve higher reaction tempera-lures and thus higher space/time yields at an unchanged selectivity level as a result of diluting the kneecap gas with the recycled residual gas, which contains less .
hydrogen Gas circulation apparatus suitable for this purpose can have an internal or external circulation of gas After the synthesis gas react;onf the reaction product is condensed, an the aqueous phase of the con dentate if appropriate after removing the acetaldehyde, is oxidized Wyeth oxygen or an oxygen-conta;ning gas in the presence of a platinum catalyst at a pi 7.
The result found, that the aldehydes, alcohols and esters present on the aqueous phase of the condemn-sate from the Rh-cataly2ed hydrogenation of C0~ can be converted in a single stage at a high degree of convert Snow unto a mixture of acetic ac;dr prop;on;c acid and butyric acid, was surprising Admittedly the homogene-ous-catalyzed oxidation of an alluded and the hotter geneous-catalyz~d oxidation of an alcohol are known and established on an industrial scale The single-stage oxidation of a mixture continuing several aldehydes, several alcohols and several esters on the presence of carboxyl;c acids has, however, not yet been described hitherto. Since the reaction is carried out at pi 7, tile addition of molar amounts of bases us unnecessary Hence a neutralization stage, itch results in the form Aetna of undesirable salts is just as superfluous as extracting the product with an extraction agent so that the process according to the invention is very economic eel. Turing the oxidation, the pi falls continuously from 7 to a lower value itch depends-on the concentra lion ox c~rboxyl;c acids finally achieved.
The preferred oxidizing agent is pure oxygen;
however, it is also possible to use mixtures of oxygen with inert gases such as air Suitable platinum catalysts are commercially available supported catalysts in particular active charcoal containing 5 to 1Q% by White of platinum The use of pressure is not absolutely necessary, but the reaction rate increases markedly with the par-teal pressure of oxygen A pressure range from 1 to 10 bar (absolute? is therefore preferable; the oxidation also takes place in a satisfactory manner at a higher pressure for example 100 bar However the advantage of the higher reaction rate can then be offset by higher investment Costs In enrolled the aqueous phase used of the con dentate from the hydrogenation of Cur contains 20-50%
by weight of water and 50-80% by weight of oxygen-containing organic compounds It is preferable to dilute tile condensate to a MU water content of 70-90% by weight before the oxidation.
A lower water content is possible in principle but the reaction rate decreases as the content of organic coy pounds rises A higher water content us also possible;
however thus increases the expenditure required for issue 5 feting the carboxylic acids formed rho oxidation temperature can vary within Dow limits, but a range iron 30 to 75C, on particular from 50 to 70C~ us preferable, since a p~rt1cula,ly high selectivity and reactivity are then achieved.
I
Tile process so flyable in so far as if desired both ace~aldehyde was the lowest~bo;li-ng come pennant and acetic acid, tether with traces of prop-nix acid and butyric acid already formed in the C0 Hyde rogenation was the hit3hes~boiling fraction) can be removed completely or partly by distillation before the oxidation The removal of the acetaldehyde~ for example is of interest of the latter can be employed as an in terrnedia-te, for example for condensation reactions The removal of the acetic acid reduces the volume of the oxidation reactor; on the other hand a certain proper lion is, however, always necessary to maintain a homage-nexus solution, so that not more than a partial removal of the acetic acid is possible.
the o~ida~;cln according to the invention can be carried out on any apparatus suitable -For carrying out reactions in the liquid phase, with or without the use of an excess pressure, for example in a stirred settle or in a bubble column using a suspended catalyst; how-ever, it is also possible lo, emplcly fixed bed Rogers using a granular catalyst as l;qu;d~phase downfall react ions. The reaction mixture can be worked up by known methods Fractional d;st;i.lation is advantageous tune water being removed first (it can still continue small amounts of unrequited aldehydes, alcohols and esters A catalyst prepared by impret~n2t;ng a slick support with the chlorides of rhodium, magnesium and of sodium contains after drying and reductiol1 with hydra gun at 275C~ 3nQ% by weight of Rho OWE by weight of No and 0.2 by weight of My Synthesis gas (40% by volt use of C0~ 59% by volume of Ho and 1% by volume of C02) is passed continuously over thus catalyst in a flow tube at Z0 bet- and a temperature of 275C and a space vowel city o, 700 his 1. The reaction product is condensed.
The aqueous phase o-f the condensate contains MY% by weight of water; its water content is raised to 75% by weight by dilution Its composition is then US indict-ted on the table 300 g of the diluted aqueous phase are poured, together with 15 g of a commercially available catalyst I of platinum on active charcoal into an externally Hyde vertical glass tube (diameter 20 mm, length 500 mm). 10 stupor of oxygen are passed in from bulge through a glass fret for 1û hours at a temperature of 50C. The filtered reaction solution contains the amounts of acetic acid prop;onic acid and butyric acid 20 indicated in the table.
Table ____ Composition (% by weight) before oxidation after oxidation acetaldehyde 2r8 < 0~1 25 propionaldehyde 0~8 C 0~1 butyraldehyde 0.3 C 0.1 ethyl acetate 1~9 0.1 ethanol 2~1 0~1 propel acetate 0~9 0.1 1~3~
propanol 0~5 < 0.1 bottle acetate OWE < ODE
n-butanol 0~2 < 001 acetic acid 13~5 21.5 5 propion;c acid 0~4 I
butyric acid C 0.1 1.0 Atari remainder Rena nuder example 2 A synthesis gas catalyst prepared analogously to Example 1 contains 2 9% by White of oh 0~3% by weight of ytterbium and 0~05 by sleight of L;. ho catalyst us employed as in Example I but at 300QC. The aqueous phase of the condensate us subjected to continue-out distillation under normal pressure on the course of which the bulk ox the acetaldehyde passes over at 20C.
The water content of the bottom product from the distill lotion is adjusted to 75% by sleight ho dilution for co~npos;tion see table).
300 9 of the butter product are subjected to catalytic oxidation as in example 1. 5 STY Pry. of oxygen are passed in at 65C for 6 hours The Sistered solution contains the amounts of carboxyl;c acids India acted in the table.
Table Z5 Composition I by weight) before oxidation after oxidation acetaldehyde 0.3 Al I
propiona~deilyde Or < Owl butyraldehyde 0.2 0.1 ethyl acetate 3.1 < 0.1 ethanol 1,7 0~1 5 propel ascot 0~3 < 0~1 propanol 0.1 0~1 bottle acetate 0.4 C 0.1 n-butanol < 0~1 < 0.1 acetic acid 16.5 Zoo 10 prop;onic acid 0.1 0~6 butyr;c acid < 0.1 0.5 water remainder remainder
Mixtures of oxygen containing compounds are ox-twined, in the form of an aqueous phase, in the hydra-genation of CO over heterogeneous rhodium catalysts in accordance with German Offenlegungsschriften ~,~14,365r 2,712,732, 2,846,148, 2,924~62 and 3,038,44~.
Furthermore, it has already been described in German Patent Application P 3,203,060.6 that oxygen-containing compounds can be obtained with an extremely high degree of selectivity by using rhodium catalysts containing compounds of the rare-earth metals and of the alkali metals. For example, redrill catalysts doped with ytterbium and lithium compounds are distinguished by a high selectivity and a virtually unlimited lye A
condensate having a high content (up to more than 70% by weight) ox oxygen-containing compounds is prosody This contains a surprisingly high proportion of acetic avid and, in addition, mainly acetaldehyde, ethanol end ethyl acetate. In addition, further oxygen-contain;ng corn-pounds continuing three or more carbon atoms, such as propionaldehyde, butyraldehyde, n propanol, n-butanol, propel acetate and bottle acetate, are obtained in a total order of magnitude of up to 5% by islet>
It us hardly possible to carry out ct)rlplete separation of the mixture by distillation oh;r,g o the . , , I
.
I
large number of azeotrope~ formed Also on the other hand, not all of the products mentioned are of great industrial interest. In addition, difficulties are en-countered, as us known, in using efficiently a large number of linked products.
It was therefore required to simplify the pro-duct spectrum on such a Jay that only durable products of industrial interest remain.
It has no been found that the product spectrum can be substantially simplified by oxidation in the liquid phase over a heterogeneous platinum catalyst so that only the intermediate products acetic acid, pro-phonic acid and butyric acid, which are very important for the chemical industry, are obtained.
The invention relates, therefore, to a process for the preparation of mixtures of acetic acid, prop no acid and butyr;c acid, which comprises reacting synthesis gas in the presence of a rhodium catalyst con-twinning, as a promoter, at least one compound of My, My La, a rare-earth metal, So, I w, Fez Or, Or, Hi, Pi and U and also, as an activator at least one compound of an Alec; metal, and subsequently condensing the reaction product and oxidizing the aqueous phase of the condemn-sate, if appropriate after removing the acetaldehyde, Thea oxygen or an oxygen-conta;n;ng gas in the presence of a platinum catalyst at a pi 7 and at an absolute pressure of 1 to 100 bar.
. In the first stage of the process according to the invention, carbon monoxide and hydrogen are reacted in a high degree of selectivity to give acetic acid, I
acetaldehyde and ethanol. In addition, small quintets are also formed of products which result from a second-cry reaction, for example esterifica~ion~ ace~alizat-ion or condensation These include, above all ethyl are-S late and the deathly acutely of acetaldehyde~ The prop-oration of other oxygen-contain;rlg compounds having three or more carbon atoms on the molecule us very small and is normally less than S mole X, relative to carbon monoxide which has reacted. The total selectivity of conversion to oxygen-containing C2 compounds, including products converted into ethyl acetate and acetaldehyde Doyle acutely, us up to I relative to carbon monoxide Shea has reacted The remainder of the carbon monoxide which has reacted us converted essentially into methane and other gaseous hydrocarbons and to a small extent, unto carbon dioxide.
Salts or complex compounds ox rhodium can be used 'as starting materials for making up the catalyst for the synthesis gas react;onO Rhodium can be present on the support in the form of metal or in a valence state below three that is to say as a complex compound of Covalent rhodium or as a salt or complex compound of univalent or d;valent rhodium. Suitable examples are chlorides, bromides and iodizes of rhodium or double salts of rhodium with alkali metal holidays such as for example, d;potass;urn trichlororhodate. Other suitable complex compounds are those which, in addition to rho-drum arid halogen also contain complex-form;nc~ ligands, such as tr;alkylphosph;l1es, triarylphosphines~ carbon ~.~3~6~
s monoxide olefins or plater, that is to say, for example tris-triphenylphosphine-rhodium-I chloride, bromide or iodide, iris triphenylphosphine-rhodium III chlorite, bus tri~o~tolylphosphine-rhodiurn~II chloride carbcnyl-b;s~tr;pher1ylphosph;ne-rhod;um-I Broadway or d;cesiumcar-bony pentachlororhodate~III. In addition, suitable compounds of rhodium are also those in high it is attached to a support in the form of an ion or complex.
Examples of these are zealots and ion exchangers in which replacement by rhodium halides has been carried out .
In addition to rhodium, the catalysts also con-lain promoters and activators. Compounds of the follow-no elements are employed as promoters: magnesium, man-Gaines, lanthanum, rare-earth metals (atomic number I
71), scandium, yttrium, tungsten, iron, zirconium, cry-mum, hafnium, platinum and uranium Examples of suit-able compounds are the chlorides, bromides, fluorides, nitrates, acetates, oxalates, acetylaeetonates or tar-trades. It us preferable to use the chlor;desr Brigham odes, acetates an acetylacetonates of these elemcn~s, above all the chlorides or bromides. Ytterbium, in the form of the compounds mentioned, is a particularly suit-able promoter.
The activators used are the oxides salts or COlDpl~X compounds of lithium, sodium, potassium, rub-drum or eczema or mixtures thereof, that is to say, for example, the oxides, hydroxides, carbonates, chlorides bromides, oxides n;tratesr awaits silicates Andre acuminates of the alkali metals Sodium compounds and lithium compounds, above all the latter, are preferred.
The catalyst supports used are customary support murals of varying specific surface area Supports having a specific surface area of So to 1000 mug are preferred, however. Suitable examples are silica, Nat fat or synthetic silicates of elements of the In to V~IIth group of the periodic system (that is to say, for exalnple, the silicates of masnes~um, calcium, aluminum or manganese), and also aluminum oxide thorium dioxide, zealots and spinets. It is preferable to use silica or silicates.
The catalysts are prepared by applying the rho-drum compound, the promoter and the activator to the support simultaneously or in successive stages in any desired sequence; this us generally effected by impreg-noting the support with solutions of the active components in suitable solvents, such as for example, water Alcoa hot, acetone, acutely acetone or acetic acid, and subset Z0 quaintly drying it.
It is also possible, however to ;ncorporatethe alkali metal and the promoters in a framework, for example a support substance containing celerity or aluminum oxide, such as slick, aluminum oxide or alum-nut silicate A further advantageous possible meanscons;sts on attaching the alkali metal or the promoters by means of ion exchange to cation exchangers which are also suitable as supports for the rhodium and are stable under the experimental conditions, for example tile natural or synthetic-alum;num silicates which are known as molecular sieves Preferably, the catalyst is also reduced before the start o-f the synthesis gas reaction. Examples of S suitable reducing agents are hydrogen, carbon monoxide, methanol or acetone. This reduction can be carried out in a separate apparatus or on the reactor itself. Rev diction is preferably carried out at temperatures below 300C, in particular between 100 and 275C. In many cases it is advantageous to carry out the reduction, not with the undiluted gases having a reducing action, but with an additional proportion of narrate gases, such as for example, nitrogen, carbon dockside or noble gases.
The concentration of rhodium, promoters and act t;vators on the catalysts can by varied thin wide limits; in general, relative to the metals the values are between 0.1 and 15% by weight for rhodium, between 0.1 and 20% by weight for the promoters and between 0.01 and 5% by weight or the alkali metals Catalysts continuing 1~0 to 10% by weight of rhodium and 0.1 to 10X by weight of promoters are preferred.
The synthesis gas reaction is carried out by passing over the catalyst gas mixtures worry are carp-sod entirely or predominantly of carbon monoxide and hydrogen and which can in add ton also contain, if appropriate, other components such as nitrogen argon, carbon Dodd or methane. The molar ratio of carbon monoxide to hydrogen on thus reaction can be varied within wide lots Molar ratio between So and 1:5 I
and especially button 3:1 and 1:3 are proofread In general, the reaction temperatures are bet-wren 175 and ~00C, preferably between 200 and 380C, and the reaction pressures are between 1 and 300 bar, preferably between 10 and 200 barn - It is advantageous to match the temperature and the pressure to one another in such a way as to ensure a high selectivity of conversion to the desired compounds and to keep at a Lowe level the exothermic formation of lo methane, Lucia is favored at elevated temperatures.
isle pressures and temperatures as logy as possible will, therefore, be preferred The gas phase us preferable for the synthesis gas reaction. The conventional fixed bed reactors can be used for thus purpose and it is a~ivantageQus to keep the layer thickness of the catalyst at a lo level in order to achieve better removal of heat Furthermore, reactors having a mobile catalyst bed or fluidized bed reactors are also suitable.
A particularly preferred embodiment of the sync thesis gas reaction consists in carrying it out in the gas phase on a gas circulation apparatus in itch, after the condensable reaction products have been removed the unreactcd gas mixture us recycles to the reactor This proceciure is particularly economical and naves it possible to achieve higher reaction tempera-lures and thus higher space/time yields at an unchanged selectivity level as a result of diluting the kneecap gas with the recycled residual gas, which contains less .
hydrogen Gas circulation apparatus suitable for this purpose can have an internal or external circulation of gas After the synthesis gas react;onf the reaction product is condensed, an the aqueous phase of the con dentate if appropriate after removing the acetaldehyde, is oxidized Wyeth oxygen or an oxygen-conta;ning gas in the presence of a platinum catalyst at a pi 7.
The result found, that the aldehydes, alcohols and esters present on the aqueous phase of the condemn-sate from the Rh-cataly2ed hydrogenation of C0~ can be converted in a single stage at a high degree of convert Snow unto a mixture of acetic ac;dr prop;on;c acid and butyric acid, was surprising Admittedly the homogene-ous-catalyzed oxidation of an alluded and the hotter geneous-catalyz~d oxidation of an alcohol are known and established on an industrial scale The single-stage oxidation of a mixture continuing several aldehydes, several alcohols and several esters on the presence of carboxyl;c acids has, however, not yet been described hitherto. Since the reaction is carried out at pi 7, tile addition of molar amounts of bases us unnecessary Hence a neutralization stage, itch results in the form Aetna of undesirable salts is just as superfluous as extracting the product with an extraction agent so that the process according to the invention is very economic eel. Turing the oxidation, the pi falls continuously from 7 to a lower value itch depends-on the concentra lion ox c~rboxyl;c acids finally achieved.
The preferred oxidizing agent is pure oxygen;
however, it is also possible to use mixtures of oxygen with inert gases such as air Suitable platinum catalysts are commercially available supported catalysts in particular active charcoal containing 5 to 1Q% by White of platinum The use of pressure is not absolutely necessary, but the reaction rate increases markedly with the par-teal pressure of oxygen A pressure range from 1 to 10 bar (absolute? is therefore preferable; the oxidation also takes place in a satisfactory manner at a higher pressure for example 100 bar However the advantage of the higher reaction rate can then be offset by higher investment Costs In enrolled the aqueous phase used of the con dentate from the hydrogenation of Cur contains 20-50%
by weight of water and 50-80% by weight of oxygen-containing organic compounds It is preferable to dilute tile condensate to a MU water content of 70-90% by weight before the oxidation.
A lower water content is possible in principle but the reaction rate decreases as the content of organic coy pounds rises A higher water content us also possible;
however thus increases the expenditure required for issue 5 feting the carboxylic acids formed rho oxidation temperature can vary within Dow limits, but a range iron 30 to 75C, on particular from 50 to 70C~ us preferable, since a p~rt1cula,ly high selectivity and reactivity are then achieved.
I
Tile process so flyable in so far as if desired both ace~aldehyde was the lowest~bo;li-ng come pennant and acetic acid, tether with traces of prop-nix acid and butyric acid already formed in the C0 Hyde rogenation was the hit3hes~boiling fraction) can be removed completely or partly by distillation before the oxidation The removal of the acetaldehyde~ for example is of interest of the latter can be employed as an in terrnedia-te, for example for condensation reactions The removal of the acetic acid reduces the volume of the oxidation reactor; on the other hand a certain proper lion is, however, always necessary to maintain a homage-nexus solution, so that not more than a partial removal of the acetic acid is possible.
the o~ida~;cln according to the invention can be carried out on any apparatus suitable -For carrying out reactions in the liquid phase, with or without the use of an excess pressure, for example in a stirred settle or in a bubble column using a suspended catalyst; how-ever, it is also possible lo, emplcly fixed bed Rogers using a granular catalyst as l;qu;d~phase downfall react ions. The reaction mixture can be worked up by known methods Fractional d;st;i.lation is advantageous tune water being removed first (it can still continue small amounts of unrequited aldehydes, alcohols and esters A catalyst prepared by impret~n2t;ng a slick support with the chlorides of rhodium, magnesium and of sodium contains after drying and reductiol1 with hydra gun at 275C~ 3nQ% by weight of Rho OWE by weight of No and 0.2 by weight of My Synthesis gas (40% by volt use of C0~ 59% by volume of Ho and 1% by volume of C02) is passed continuously over thus catalyst in a flow tube at Z0 bet- and a temperature of 275C and a space vowel city o, 700 his 1. The reaction product is condensed.
The aqueous phase o-f the condensate contains MY% by weight of water; its water content is raised to 75% by weight by dilution Its composition is then US indict-ted on the table 300 g of the diluted aqueous phase are poured, together with 15 g of a commercially available catalyst I of platinum on active charcoal into an externally Hyde vertical glass tube (diameter 20 mm, length 500 mm). 10 stupor of oxygen are passed in from bulge through a glass fret for 1û hours at a temperature of 50C. The filtered reaction solution contains the amounts of acetic acid prop;onic acid and butyric acid 20 indicated in the table.
Table ____ Composition (% by weight) before oxidation after oxidation acetaldehyde 2r8 < 0~1 25 propionaldehyde 0~8 C 0~1 butyraldehyde 0.3 C 0.1 ethyl acetate 1~9 0.1 ethanol 2~1 0~1 propel acetate 0~9 0.1 1~3~
propanol 0~5 < 0.1 bottle acetate OWE < ODE
n-butanol 0~2 < 001 acetic acid 13~5 21.5 5 propion;c acid 0~4 I
butyric acid C 0.1 1.0 Atari remainder Rena nuder example 2 A synthesis gas catalyst prepared analogously to Example 1 contains 2 9% by White of oh 0~3% by weight of ytterbium and 0~05 by sleight of L;. ho catalyst us employed as in Example I but at 300QC. The aqueous phase of the condensate us subjected to continue-out distillation under normal pressure on the course of which the bulk ox the acetaldehyde passes over at 20C.
The water content of the bottom product from the distill lotion is adjusted to 75% by sleight ho dilution for co~npos;tion see table).
300 9 of the butter product are subjected to catalytic oxidation as in example 1. 5 STY Pry. of oxygen are passed in at 65C for 6 hours The Sistered solution contains the amounts of carboxyl;c acids India acted in the table.
Table Z5 Composition I by weight) before oxidation after oxidation acetaldehyde 0.3 Al I
propiona~deilyde Or < Owl butyraldehyde 0.2 0.1 ethyl acetate 3.1 < 0.1 ethanol 1,7 0~1 5 propel ascot 0~3 < 0~1 propanol 0.1 0~1 bottle acetate 0.4 C 0.1 n-butanol < 0~1 < 0.1 acetic acid 16.5 Zoo 10 prop;onic acid 0.1 0~6 butyr;c acid < 0.1 0.5 water remainder remainder
Claims (6)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A process for the preparation of mixtures of acetic acid, propionic acid and butyric acid, which comprises reacting synthesis gas in the presence of a rhodium catalyst containing, as a promoter, at least one compound of Mg, Mn, La, a rare-earth metal, Sc, Y, W, Fe, Zr, Cr, Hf, Pt and U and also, as an activator, at least one compound of an alkali metal, and subsequently condensing the reaction product and oxidizing the aqueous phase of the condensate, if appropriate after removing the acetaldehyde, with oxygen or an oxygen-containing gas in the presence of a platinum catalyst at a pH ? 7 and at an absolute pressure of 1 to 100 bar.
2. A process as claimed in claim 1, wherein the water content of the aqueous phase employed in the oxidation reaction is adjusted to 70 to 90% by weight.
3. A process as claimed in claim 1, wherein the oxidation is carried out under an absolute pressure of 1 to 20 bar.
4. A process as claimed in claim 1 wherein the oxidation is carried out at 30 to 75°C.
5. A process as claimed in claim 2 wherein the oxidation is carried out at 30 to 75°C.
6. A process as claimed in claim 3 wherein the oxidation is carried out at 30 to 75°C.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP3318210.8 | 1983-05-19 | ||
| DE19833318210 DE3318210A1 (en) | 1983-05-19 | 1983-05-19 | METHOD FOR PRODUCING MIXTURES FROM ACETIC ACID, PROPIONIC ACID AND BUTTERIC ACID |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1230611A true CA1230611A (en) | 1987-12-22 |
Family
ID=6199374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000454541A Expired CA1230611A (en) | 1983-05-19 | 1984-05-17 | Process for the preparation of mixtures of acetic acid, propionic acid and butyric acid |
Country Status (6)
| Country | Link |
|---|---|
| EP (1) | EP0129058B1 (en) |
| JP (1) | JPS606633A (en) |
| AU (1) | AU2839684A (en) |
| CA (1) | CA1230611A (en) |
| DE (2) | DE3318210A1 (en) |
| ZA (1) | ZA843766B (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4681845A (en) * | 1985-08-16 | 1987-07-21 | Uop Inc. | Increased glucose levels in starch saccharification using immobilized amyloglucosidase |
Family Cites Families (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3407220A (en) * | 1966-09-14 | 1968-10-22 | Shell Oil Co | Production of aliphatic carboxylic acids |
| DE2924962A1 (en) * | 1979-06-21 | 1981-01-29 | Hoechst Ag | METHOD FOR PRODUCING OXYGEN-CARBON COMPOUNDS AND OLEFINS FROM SYNTHESIS GAS |
| NZ195461A (en) * | 1979-11-27 | 1983-06-14 | British Petroleum Co | Producing oxygenated hydrocarbon product containing ethanol |
| DE3203060A1 (en) * | 1982-01-30 | 1983-08-04 | Hoechst Ag, 6230 Frankfurt | METHOD FOR PRODUCING ACETIC ACID, ACETALDEHYDE AND ETHANOL |
-
1983
- 1983-05-19 DE DE19833318210 patent/DE3318210A1/en not_active Withdrawn
-
1984
- 1984-05-15 DE DE8484105507T patent/DE3460339D1/en not_active Expired
- 1984-05-15 EP EP84105507A patent/EP0129058B1/en not_active Expired
- 1984-05-17 CA CA000454541A patent/CA1230611A/en not_active Expired
- 1984-05-18 ZA ZA843766A patent/ZA843766B/en unknown
- 1984-05-18 AU AU28396/84A patent/AU2839684A/en not_active Abandoned
- 1984-05-18 JP JP59098882A patent/JPS606633A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| AU2839684A (en) | 1984-11-22 |
| EP0129058A1 (en) | 1984-12-27 |
| EP0129058B1 (en) | 1986-07-23 |
| JPS606633A (en) | 1985-01-14 |
| DE3460339D1 (en) | 1986-08-28 |
| DE3318210A1 (en) | 1984-11-29 |
| ZA843766B (en) | 1984-12-24 |
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