CA1070711A

CA1070711A - Process for preparing butanediol-(1.4)

Info

Publication number: CA1070711A
Application number: CA251,589A
Authority: CA
Inventors: Hans Fernholz; Dieter Freudenberger; Friedrich Wunder
Original assignee: Hoechst AG
Current assignee: Hoechst AG
Priority date: 1975-05-03
Filing date: 1976-04-30
Publication date: 1980-01-29
Also published as: NL7604539A; FR2310331A1; DE2519817A1; JPS51133212A; BE841409A; FR2310331B1; GB1551741A

Abstract

ABSTRACT OF THE DISCLOSURE

PROCESS FOR PREPARING BUTANEDIOL-(1.4) Butanediol-(1.4) is prepared by hydrogenating maleic anhydride, maleic acid or mixtures thereof in one step in the presence of catalysts comprising simultaneously elements of subgroup VII or compounds thereof and elements of sub-group VIII or compounds thereof or mixtures of these elements and compounds.

Description

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The present invention relates to a single-stage, catalytic process Eor preparing butanediol-(1.4) from maleic anhydride, maleic acid or mixtures of both compounds.
Butanediol-(1.4) is used, for example, as initial pro-duct for preparing polyester fibers; in this process butanediol-(1.4) is reacted, for example, with terephthalic acid at elevated temperature in the presence of catalysts to yield polybutylene terephthalate.
Processes for preparing butanediol-(1.4) are already known. Besides a number of formerprocesses with syntheses based, for example, on acetyleneformaldehyde or 1.4-dihalogenobutane processes for preparing butanediol-(l.~) by using as starting material ~-butyrolactone haverecently been described.
Economic and technically utilizable processes for directly preparing butanediol-(1.4) from maleic anhydride r or maleic acid have not been known, hitherto. It is true that maleic anhydride may be converted into butanediol-(1.43 in a -yield of at most 64 %, but ~aney cobalt used as catalyst in said process is not ~uitable for technical continuous operation, as it is dissolve`d and deactivated in an irreversible manner by maleic anhydride and maleic acid partly formed intermediary already after a short period. The reaction moreover requires -extremely high pressures of about 800 bars and temperatures of about 275C, at which the diol formed is again dehydrated with considerable formation of tetrahydrofurane.
When using nickel molybdate or nickel chromate catalysts described in former processes butanediol-(1.4) is obtained from maleic anhydride only in a yield of about 50 % besides . ~ ~

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conside~able qua~tlties of tetrahydrofllrarle. T~ s process also requlres very high pressure of about 800 bars which may only be obtained with difficulty technicallyO Sa~d catalysts are also unstable when used in long-time operatio~
and are dissolved and deactivated by acidsSlike ~ecopper chromi~tm oxides known for ester hydrogenations. The same applies to pure nickel catalysts.
When using catalysts which are clascrlbed as being stabler towards acids and contàin for example rhenium, rhenium-molybdenu~cobalt or nickel~molybdenum-rheniu~l or nickel-rhenium~ maleic anhydride or maleic acid can only b~ co~1~erted into butanediol-(1.4) up to at most 9 to 14 ~oO In this proce~s there are formed asMain products in a yield of partly more than 90 % succinic acid, tetrahydrofurane and ~ butyrolactone.
In this case as well a dissolution, especially of the nick~l or cobalt portiorls of the catalysts~ takes place. In other disclosed cases butanediol-(1.4)is not at ~lformed from malelc acid anhydride or maleic acid when using rhenium catalysts, but only succinic acid. The same applies to platinum and 20- rhodium catalysts. Whon ~1sing palladium catalysts, for example palladium/carbon catalysts, maleic anhydride may only be hydrogenated to the stage of ~-butyrolactone or the reaction i~ Qtopped at the stage of succinic acid.
A catalytic process for preparing butanediol-(1.4) has now been found9 in which maleic anhydride or maleic acid or mixtures thereof may be directly converted into butanedi~l-(1.4) in a one-step reaction with excellent yields and con~
versions and a very high ser~ice life of -che catalysts.
29 This i~ very surprising as acceptable yields snay only .~ ~J
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be obtained accordi~g to the state of the ar~ wi~h unstable catalyst~ ab~olu~ely unsuit~le for technlcal long-tirne operation.
When using stabler catalyst~ ~ery low yields of butan0diol-(l.4!. if any~ are obtained or only succinic acid.
The present invention proYides a process for preparing butanediol-(1.4) from maleic anhydri~le; maleic acid or mixtures thereof, which comprises hydrogenating maleic anhy-dride, maleic acid or mixture~ th0reDf in one step in thepresence of catalysts comprising simultaneously eleme~ts of subgroup VII or compound~ thereof and elements of subgroup VIII or compounds thereof or mixtures of these clements and - compound 5 .
The novel pr~cess is espocially distinguishcd by the fact that by~products ~uch as tetrah~Ydrofurane, ~-butyrolactone and succlnic aci`~ are not obtained practically and that the formation of n-butanol disclo~ed in literature concernlng hydrogenations of maleic anhydride and maleic acid to yield tetra~ydrofurane and ~-butyrolactone i.5 lnSignifiCaIlt.
The noYel proce~s for preparing butanediol-~1.4) is con~equently a tochnically simple and very economical method, in which pro,blems involved with waste products~which may be observed in the former processes for preparing butanediol- :
(1.4) from dihalogenobutanes do not occur.
The catalysts used in the noYel process contain elements or compounds of elements of subgroup YII as well a~ of sub-group VIII of the Periodical Table, with the inc~usi.on of 29 mixtures of el.ements o~ one group with cornp~lds of eleme.ts : J

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of the other group~ ~speoially sultable elements are manganesc~
rhenium~ rutheniutn, rhorlium, palladium, osmium, iridium, and platinium. Rhenium~ palladlum and platinum are used preferably~
An especially surprising advantage in the novel proces~
resides in the ~act that a selectivity of butanediol-(1.4 may be obtalned by a simple combination of elements of sub-group VII or compounds thereof with elements of subgroup VIII
or compounds thereof, which cannot be obtained when using alone elements o~ one group or compound~ thereof, especially with rhenium or palladium, ~.
Moreover, it was not to be expected that practically quantitative conversions o~ maleic anhydride and/or maloic acld co~ld thus be ~tained without a notable less of activit~
of th~ catalysts accord~ng to the invention. The combination according to the invention of the elcmeItts of subgroup ~II
with elements o~ subgroup VIII, especially rhenium and palladlum9 and/or their compounds has therefore ~urprlslngly a considerable ~tabilizing effert and lncreases significantly ~:
the service life o~ the catal~sts as compared to those described in the former literature. This ~s of decisive importance for technical lo~g~tlme operation and as a result th~ no~el process is superior to the prior art proces~es~
In the process according to the invention the catalysts are generally used in a pulverulent form. They may also be used, however, in a tabletted ~orm or mixed wi~h inert ma~
terials optionally s~rv~ng as a support.
Suitable carr~r~ are, for example. silicon dioxide, 29 titanlum dioxlde, ~ilicon dioxide aluminium oxide~ carbon .
: . ' '' , :

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thorium~oxide, zlrconium oxide, silicon carbide~ spinels and aluminiu~ oxid2.
I~ supported catalysts or those mixsd with inert materials are use~, the quantity of the catalytically actiYe ~ub~tances i5 generally in the ranFe from 0~1 to 50 ~ by wei~ht of the total quanti-ty of the catalyst~ The quantity of the inert materials (carrier) is consequently in th~ range from 99.9 to 50 ~ of the total mass o~ the catalyst J
The ratio of the elements of subgroup VII and those o~
subgroup VIII is in the range from 99:1 to 1:99, pre~erably from 10:1 to 1:10.
The catalysts may be present ~n the form of elemants as well as compounds or as mixture~ o~ both, optiona:Lly together with carriers, Consequently they may be prepared by uqln~
direc~y sui.table compolmds being optinally supported or by reducing these compounds to a more or less consid0rable extent, optinally up to the stage o~ the ele~ents.
Suitable compounds to be used are, for example: oxide~
hydrated oxides, carbonates, nitrates, borides, carboxylates 20- (such as acetates, propionates, butyrates), chelates of 1.3-diketo compounds (for examp~e enolates such as acetyl acctonates, benzoyl acetollates, acetoacetic acid ester com-pounds). Especially suitable are carbo~ylates, acetylaceto-nates, oxides and hydrous oxides. For technical and econom~cal reasons the use of rhenium9 ~or example, in the ~orm of potassium perrhenate or rhenium heptoxide and of palladium in the form of palladium(II) acetate or acetyl-acetonate is especially ad~antageou~, a~ these compo~nds are 29 commercially availabe.

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For preparing, for example, palladium-rhenium catalysts a solution of a palladium carboxylate or of a compound reacting with carboxylic acids to yield palladium carboxylate such as hydrous palladium oxide, palladium nitrate, palladium hydroxy-carbonate or a salt of a 1.3-diketo-compound such as acetoacetic acid ester or acetylacetone in an anhydrous or water containing carboxylic acid together with perrhenic acid or its salts is applied on the carrier, by impregnating, immersing or suspending the carrier material or by spraying. Instead of palladium carboxylate there may also be chosen a compound reacting with carboxylic acid to yield a palladium carboxylate, for example the hydrous oxide, the nitrate or the hydroxycarbonate of palladium. The carboxylic acid is then eliminated by drying at higher temperatures in vacuo or under atmospheric pressure.
The catalyst may now be directly used, but is treated preferably in the gaseous or liquid phase at a temperature from 15 to 200C
with reducing agents.
Suitable carboxylic acids are all liquid aliphatic carboxylic acids having from 2 to 10 carbon atoms which may be vaporized in vacuo without being decomposed. Acetic acid, propionic acid or butyric acid, are preferably used, especially preferred is acetic acid.
The solutions of both compounds used for preparing the catalysts, for example of a palladium salt and a rhenium compound may be applied separately on the carrier material, but the palladium and rhenium compounds are preferably dissolved in one carboxylic acid. It is also possible to apply firstly one of the aforesaid palladium compounds on the 7~L
carrier m~ter:;a.]. antI to apply th~r~a~ter th~ 501ution of a rhenllml compound in a carboxylic acld. The carriers may be pulveruleIlt or ~hape(I 9 for example as granules 9 p~llets, tablets, compressed extruded materials, saddles, rings or tubes having a honeycomb structurn.
The reductio~ o~ the catalysts tnay be performed in the liquid phase, for example with hydrazine hydrate, but i9 carried out advantageously at ele~ated te~nperatures, ~or example in the range from 100 to 200C in the gaseous phase with reducing vapors or gases such as hydrogen, methanol~
formaldeh~de, ethylene, propylene, butene ~in a diluted or undiluted form. Stronglr diluting at the beglnni.ng with inert gases such as ni.trogen, carbon dioxlde or noble gase~ and ~ncreasin~ the coneentration of the reducing agent in ~he measure as the reduction progresses has pro~ed especially advantageous so tha-t the reduction may be terminated for example in pure hydrogen, The reduction may be per~ormed in ~ separate devlce as well as in the apparatus used for converting malelc anhydride and/or ~aleic acid into butane-

2~ diol-t 1.4).
The catalysts may be pyrophoric~ In this case they must be tre~$ed adequatly. Reducing the catalyst and reacting maleic acid and/or the anhydride in one apparatus is especially advantageous in thl.s case.
An important factor for performing the single-~ctep direct pl'OCeSS of the invention on an industrial scale is that succinic acid is not formed practically, an acid which would readily precipitate owing to its extremely low solubility 29 and cause obstructlon of the apparatus or requIre a further ~, :

step 3 T~`or carrying out the process o~ the in~ention in an optimum mann~r the hydrogenolysis of maleic anhydride and/or maleic acid is generally per~ormed und~r an elevated pressure and at elevated temperature.
The reaction temperatures are therefore generally in tha range ~rom 50 to 300C~ preferably from 150 to 250C.
The reactio~ pressure is generally in the range from 50 to 500 bars~ preferably from lO0 to 350 bars.
Hydrogen used for th~ hydrogenolysis of maleic anhydr.i.de or maleic acid is generally in a considerable stoichiometrical exce~s. Unreacted hydrogen may be recycled to the reaction as circulating gas. The reaction may be carried out con-tinuously or discontinuously. Hydrogen is generally us~d in 1~ a technically pure form. Admixtures of inert gases such as nitrogen7 however, do not disturbe the course of the reaction.
The re~ction time in the process of the inv~ntion i3 general~y in the range from 5 minutes to 8 hours 9 f`or exampls about 3 to 6 hours, when working discontinuously in an autoclave.
Pulverulent catalysts may be ~iltered off at the end Or the reaction or by separated by centrifugation and be reusecl without a notable loss of activity.
When working continuously, for example in the trickling phase, tabletted catalysts or those applied on carriers are generally usedr When performing the reactivn in practice, the solvents known for hydrogenations may be used 9 for example dioxane, 29 tetrahydropyrane ~ oth~cyclic or strai.ght chain ethers, for , . ~ :

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ex;llnpl~ tetra}lydrol`-tra~le or diethyl ether, Polyalkylene gly~ol dialkyl ether~,~ f`or exalnple tetramethyl~neglycol dibtltyl eth~r, tctra~D~tllylene~lycol dipenty:L ether~ tetra~thylen.e-glycol dimothyl etherl tetraethylaneglycol diethyl ether and diethyleneglycol dibuty:L ethar or m.i~tures of these or other solvents may also ba used. Solvcnt3 ha~ing a boiling point nbove 245~ have pro~ed especially advantageous. The content of maleic acid and/or anhydrlde in the initial soluti.on in this case is generally in the range ~rom 5 to 1060 %~ Using maleic anhydride as a 20 to 40 ~0 solution in 1,4-dioxane has proved advantageous~ Water ls also suitable as solvent for maleic acid. The quanti$y o~ catalyst used for hydrogenating is generally in the range ~ro~ 0.5 to 2g Or the quantlty of maleic anhydride or maleic acid.
15Malelc ~nhydride as well as maleic aicd and any mixture~
of both substancos may be used a5 charge products.
The reaction m.ixtures arc gen~rally worked up by fractio_ nated distillation.
The following method has pro~ed e~peclally advantageous ~or preparing butanedlol-(1.4) discontinuously: A solution o~
maleic anhydride in 1.4 dioxane is gi.ven into a high pressure aukoclave together with the catalyst, hydrogen i5 introduced under pressure and the reaction mixture i5 heated. At the erld o~ ~he r~action the reaction mixture is cooled~ the catalyst is separated and the mixture is distilled.by fractio-nation.
The rollowing examples illustrate the invantion:
E X A M P 1, E 1~
2~ 27 g of palladium acetate and 4 g o~ rhenium heptoxlde , .. . .

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w0r~ clis80].~red ir~ 120C) ml o~ acetic acid at 80C~ 100 g of ~ :
kiese~guhr ~r~a~ded~ khe mlxture was evaporated to drynes~
in VAOUO while stlrring and roduced in a hydrogen atmosphere at 200C, 0,5 mol of` maleic anhydride (49g) were dissolv~d in 1Q0 ml of dioxaneO The solution was poured into a 1 liter autocla~e pro~ided with a shaking dlvics together with 5 g o~ the pulverulent kleselguhr catalyst containing 10.6 ~ o~ palladium and 2.3 /0 o-~ rhenium~ Hydrogen was introduced until a pressurs of 215 ba~s was r~ached and the mixture obtained was rapidly heated to 225 to 230C. After about 6 hours tho reaction was interrupted and the reaction mixture was rapidly clried. After separation o~ the catalyst 151.5 g o~ a water-clear9 colorless reactio~ solution was obtained cont~ning 27~9 /~ of 1.4~bu~ne~
1$ diol (42,2 g) correspondin~ to 93,8 ~o o~ the theory. Besides butanediol~ and the solvent dioxane 9 water could be de-tected as well as rather small quantities of ~-butyrolactone~
tetrahydrofurane~ n-butanol by gaschromatography and traces of succinic acid by titrimetry.
E X A M P L E 2:
49 g of maleic anhydride were dissolved in 100 ml o~
dioxane. The solution was reacted together with 5.9 g of the slightly wet catalyst, which had already been used ln Example 1 and bee~ filtered off, in the manner descrlbed in Example 1.
There wcre obtained 149,8 g of a wate. clear colorless solution containing 28.2 % of ~ .4-butanediol (42.3 g~. Tllis corresponded to 93.9 ~ of the theory, The reaction mixture contained still small quantities o~ a polyestsr bsides the 29 substances cited ::Ln Example ~, . .

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E X A ~I Y L ~ ~:
The calculated quantity o~ platin~lm acetate and rhaniu~
heptoxide in acetic acid solution was ad~nixed wlth kie~elguh:r~
dricd and reduced as describ~d in Example 1.
A ~olution of 58 g of maleic acid (0p5 mol) in 200 ml o~ water was given lnto a 1 liter steel autoclave together wit;h 6 g of the kieselguhr catalyst containing 10 ~0 Or platinum and 2.8 ~0 o~ rheniump Hydrogen was introduced unti.l a pressure of 195 bars wa~ obtained and the reaction mixture was rapidly heated to 230C.
A~ter a reaction time of about 3 arld a half hours another Z5 bars o~ hydrogen were introduced. After a total r~action time of 5 hours the reaction wa~ stopped, as no further hydro~en absorption could be observ0d. The catalyst was separated by a centrifuge and 2~5 g o~ a reaction solution were obtained.
The water-clear, colorless solution contained 16 ~o or 40.8 g of butanediol ~ ) corresponding to 90.0 % of the theory.
20. The reaction mixture contair.~ed b~sid0s butanediol-(1.4) and watar 0.53 % o~ ~-butyrolactorle~ 0. 6 % of n-butanol as well as small portions o~ tetrahydrofurane, succinic acid and butyric acid.
~ L r 4:
For preparing the dèsired qua~tity of the catalyst) palladium acetate, rhodium acetate and rhenium heptoxide were dissolved in the calculated quantities ln ac.etic ac-ld 9 alumosilicate powder~as added and dried a~d reduced as des-29 cribed in E~ample 1p Then 0.5 ~.ol of maleic arlhydride (ll~ g) _ 12 ~

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were dis~olved in 100 g Or tetrahydropyrane (about 114 ml)~
5.2 g o~ the kieselguhr~aluminium oxide catalyst were added contalning 8.3 ~ of palladium, 4 2 '~o of rhodium and 2.7 %
o~` rhenium and the m~xture was placed into a 0.5 liter autoOElave provided wltll a magnetic type lifting stirrer.
After having introduced hydrogen until a pressure of 189 bars ?
was obtained the mixture was rapidly heated to 220C and allowed to react for a total of 4 and a half hours. There-after it was rapidly cooted, the catcllyst was separated and the reaction mixture was analyzed by gaschromatography.
i47 g Of a solution were obtained containing 26 9 /v of butanediol-(1.4) (39.6 g), which corresponded to about 88 % of the theory.
E X A M P T E 5:
For preparing the catalyst 100 g of` active carboll (810 m /g according to ~ET, pore volume of 0.9 mllg) wer~ impreg-nated with a solution of 20 g of Na2PdC14 in 86 ml of water, dried while stirring, impregnated with a solution o~ 4 g of NaOH in 88 ml of H20 and ~llowed to stand for 2 hours~ There~
after the mixture was washed until it was free from chloride~
dried to a w0ight of 150 g, impregnated with a solutlon of 6 g of Re207 in 50 ml of water, dried while stirring and reducsd in hydrogen at 200C.
0.25 mol of maleic anhydride (24 g) and 0.25 mol o~
maleic acid ~29 g) were dissolved in 100 ml of slightly heated dioxane. 5 g of the catalyst based on act~ve carbon powder were added which contained 4.1 ~ of rhenium and 8.2 ~ of palladium oxide and the mixture was given into a 29 0~5 liter high pressura autoclave pro~ided with a shalc~ng ~j .

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After having tntroduced hydrogen until a pressure of 170 bars was obtained~ -the mixture was heated to 232C and allowed to react for 3 hours~ Anothar 40 bar~ of hydroge~a wero inkroduced and the reaction mixture was rapidly cooled after 1.5 hours. The catalyst was sep~rated.
149.3 g of reaction solution were olbtain~d containing 39.8 g of butanedlol-(1.43 E X A M P L E 6:
The kieselguhr catalyst used in Exampla 1 was compressed to tablets having a diameter of 6 !~m and a thickness of 2 mm on a pelleting machine. 1 liter of this catalyst was gi~en into a stainless steel high pressure reactor havin2 a length of about 2 ~n~;l`he apparatu~ was ~lushed w$th nltrogen and 15 ~aydrogen was Lowly added until a pressure o~ 260 bars was attained. While add~ng hydrogen at the lower end o~ the reactor a 32 ~ solution o~ maleic anhydride in dioxane was added at the upper end and allo~red to trid~e o~er the catalyst. As soon as a liquid left the reactor at thc lower end, the reaction mixture ~as slowly ~leated to tho working te~perature of 225 C while continuing the a~dition of hydrogen at a rate of about 8 to 10 Nm3/h (N meaning that the ~ol~ame is calculated under normal conditlons of tempera~
ture and pressure i.e. of 0C and 760 mm~Ig) and dioxane-maleic anhydride at a rate o~ about 1520 g/h. Two hours afterhaving attaine~a the working temp~rature of 225C the leavialg reaction mixture was araalyzed at ho~arly intervals. Per hour there were obtained about 1560 g o~ reaction mixture con-29 taining on th~ a~erage from 25 to 26 % of butan~diol~ 4), ~, :

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which corresponded to abou-t 85 to 90 % of the theoretical yield of butanediol~ ). A decrease of the output could not be observed even after 300 working hours.
E X A M P L E 7:
20 g of palladium acetate, 10 g of iridium acetate~
4 g of rhenium heptoxide were dissolved in 600 ml of glacial acetic acid, 100 g of kieselguhr were introduced by stirring; the mixture was dried in the rotation evaporator at 60C in a water jet vacuum. The dried catalyst was reduced in an aqueous solution of sodium boron hydride having a temperature of ~0C, washed and dried. It contained 8.2 % of palladium, 4 % of iridium and 2.3 %
of rhenium as borides, the percentages being calculated on the elements.
5 g of this catalyst were given into an autoclave with 0.5 mol of maleic anhydride and 100 ml of dioxane and treated as indicated in Example 1.
148.1 g of a water-clear colorless reaction solution were obtained containing 39.~ g of butanediol-(1.4).
E X A M P L E 8:
19.5 g of palladium acetate, 7.7 g of ruthenium acetate and 3.3 g of rhenium heptoxide were dissovled in 900 ml of acetic acid, 1~0 g of zirconium oxide were introduced by stirring, the mixture was dried in the rotation evaporator in vacuo and and reduced in hydrogen at 200C.
0.5 mol of maleic acid (58 g) were dissolved in 100 ml of warm dioxane. 7.5 g of a zirconium oxide catalyst containing 8.1 % of palladium, 205 ~ of ruthenium and 2.2 % of rhenium were added and the mixture was placed into a 0.5 liter autoclave provided with a magnetic type lifting stirrer.

, , : ' ' ' Hydrogen was introduced until a pressure of 178 bars was obtained, the mixture was rapidly heated to 215C and allowed to react or 3 and a half hours. It was cooled, expanded and the reaction solution was analyzed. After having filtered o~f the catalyst 138 g of a solution containing2g.8 ~ or 34.S g of butanediol-~1.4) was obtained, which corresponded to about 78 %
of the theory.
C O M P A R A T I V E E X A M P L E 1:
27 g of palladium acetate were dissolved in 1200 g of glacial acetic acid at 80C, 100 g of kieselguhr were added and dried and reduced as described in Example 1.
0.5 mol of maleic acid (149 g) were dissolved in 100 ml of dioxane. The solution was reacted with 5 g of the kieselguhr catalyst containing 10% of palladium as indicated in Example 1.
148.3 g of a slightly yellow solution were obtained, containing only 3.5 % (5.2 g) of butanediol-(1.4). The main product of the reaction was ~ butyrolactone being present in the reaction solution in an amount of 23.1 ~.
C O M P A R A T I V E E X A M P L E 2:

3.2 g of rhenium heptoxide were dissolved in 400 ml of glacial acetic acid, 100 g of kieselguhr were introduced by stirring, dried and reduced as in Example 1.
The example was carried out in the same way as in Comparative Example 1, but by using instead of the catalyst used therein 5 g of a SiO2 catalyst containing 2~3 % of rhenium.
147.2 y of a reaction solution were obtained containing only traces (<0.2 %) of butanediol-(1.4), 10.2~ of ~-butyrolactone but more considerable quantities of succinic acid, p;artly precipitat-ing .

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the preparation of butanediol-(1.4) in which maleic anyhydride, maleic acid or a mixture thereof is hydrogenated in one step in the presence of a catalyst comprising manganese or rhenium or compounds thereof as well as ruthenium, rhodium, palladium, osmium, iridium or platinum or compounds thereof.

2. A process as claimed in claim 1 in which the catalyst comprises rhenium or compounds thereof as well as palladium and platinum or compounds thereof.

3. A process as claimed in claim 1 in which the catalyst comprises rhenium or compounds thereof as well as palladium or compounds thereof.

4. A process as claimed in claim 1 in which the compounds of the elements are selected from the group of oxides, hydrated oxides, carboxylates, chelates of 1.3-diketo compounds, nitrates, carbonates or borides.

5. A process as claimed in claim 1, in which the catalyst is supported on a carrier material.

6. A process as claimed in claim 5 in which the catalyst is present in an amount of from 0.1 to 50% by weight of the total quantity of catalyst and carrier material.

7. A process as claimed in claim 6 in which the carrier material is selected from the group of silicon dioxide, silicon dioxide/aluminium oxide, carbon, titanium dioxide, thorium oxide, zirconium oxide, silicon carbide, spanels and aluminium oxides.

8. A process as claimed in claim 1, claim 2 or claim 3 in which the ratio in active elements of subgroup VII and elements of subgroup VIII is from 99:1 to 1:99.

9. A process as claimed in claim 1, claim 2 or claim 3 in which the reaction temperature is in the range of from 50 to 300°C.

10. A process as claimed in claim 1, claim 2 or claim 3 in which the reaction pressure is in the range of from 50 to 500 bars.