FR2505819A1 - PROCESS FOR PRODUCING ALCOHOLS BY CATALYTIC HYDROGENATION OF ORGANIC ACID ESTERS - Google Patents

Abstract

The present invention relates to a catalytic process for the direct hydrogenation of the esters of carboxylic acids to give alcohols. The reaction is carried out in liquid or gaseous phase in the presence of a carrier catalyst which contains rhenium and at least one noble metal from the group VIII. The process can be carried out at a moderate reaction pressure and reaction temperature, the temperature being 150 to 300 DEG C and the pressure 10 to 100 atmospheres. In particular, the invention relates to the preparation of alcohols having 2 to 20 carbon atoms.

Description

 The production of higher or fatty alcohols is currently ensured mainly synthetically from olefins, in particular by the OXO and Ziegler processes. Given the tensions that exist over hydrocarbon supplies, it is desirable to turn to other sources of raw materials, renewable if possible. The fatty alcohols, whose fields of application are very varied, fit into this new production scheme by the conversion of fatty acid esters, extracted from vegetable or animal oils, into corresponding fatty alcohols.

The preparation of fatty alcohols from fatty acid esters can be carried out by reduction by means of chemical agents such as lithium aluminum hydride, as described above.
Finholt et al. In J of Am Chem Soc., Vol. 69, p 1199, (1947), diborane (B2H6) or sodium (French Patent No. 388,895 and US Pat. No. 863,352). Another type of reduction method uses catalytically activated hydrogen.

 The catalysts known for this reaction consist essentially of mixed copper and chromium oxides deposited or not on a support: East German Patent Nos. 122,067, West German Nos. 2,613,226 and 2,800,384, US Pat. No. 4,072. 726, Belgian Nos. 864,567 and French Nos. 1,420,720 and 1,572,167. The doping with oxides of alkaline (Na 2 O, K 2 O) or alkaline earth metal (MgO, Ca 0, Ba 0) metals makes it possible to improve the selectivity and catalyst stability: East German Patent No. 71,544, West German Nos. 2,511,377 and 2,613,226, United States Patent Nos. 1,512,414 and 2,285,448, British Patent No. 1,151,939 and French No. 1,426,720. and 1,572,167. Catalysts based on transition metals are also the subject of claims: German Patent Nos. 2,800,384 and French Patent No. 2,021,633.

The number of patents filed for the direct hydrogenation of the esters in the presence of supported metal catalysts is relatively limited. On the other hand, the hydrogenation of the corresponding carboxylic acids has been the subject of a greater number of works which have resulted in patents: West German patents No. 2,133,768, US Pat. Nos. 2,607,805 and 2,607,807. and 4,104,478, French Nos. 1,293,723 and 2,340,922. This is explained by the greater reactivity of organic acids with respect to the corresponding methyl or ethyl esters, as shown by HS Broadbent et al.
Annals of the New York Academy of Science 172, 194 (1970) .However, the direct hydrogenation of acids requires the use of special materials capable of withstanding the corrosive action of these acids during the various stages of transfer, reaction and recycling. eventual during the operation of the unit, which significantly increases the cost of the investment. In contrast, the methyl or ethyl esters of fatty acids are very little aggressive compounds.

In addition, disadvantages related to the nature of the catalysts are to be considered
- for catalysts based on mixed copper and chromium oxides, doped or not, the need to work under high pressure, in almost all cases greater than 200 atmospheres, and at a temperature between 250 and 3500C is imposed by the very low activity of these catalysts under less severe conditions of temperature and pressure.

 for catalysts based on transition metals deposited on a support, the obligation to work at a lower temperature, below 2500C and preferably at 2000C, to limit the degradation of the alcohol formed in hydrocarbon; which imposes operating pressures greater than 100 bar to obtain good selectivities at an acceptable conversion level.

 Nevertheless, the thermodynamic analysis of the conversion of the esters to alcohols shows that the reaction is possible at low pressure provided that a sufficiently active and selective catalyst is used.

dans un réacteur continu ou discontinu sous une pression totale comprise entre 10 et 100 bars et de préférence entre 30 et 80 bars, bien que lton puisse opérer sans inconvénient, par exemple, jusqu'à 300 bars, à une température comprise entre 150 et 300 C et de préférence entre 180 et 2500C et avec un rapport molaire hydrogène sur ester compris entre-2 et 10 et plus avantageusement entre 2 et 5.Cette réaction est réalisable dans les conditions préalablement précisées si l'on utilise un catalyseur supporté renfermant les éléments suivants : le rhénium dont le pourcentage pondéral est choisi entre 0,5 et 5 % et de préférence entre 0,5 et 3 %, et au moins un métal du groupe VIII, de préférence un métal noble du groupe VIII et plus particulièrement choisi dans le groupe constitué par l'iridium, le palladium, le platine, le rhodium et le ruthénium et dont le pourcentage pondéral est choisi entre 0,01 et 3 % et plus particulièrement entre 0,1 et 1 % ; le support peut être choisi dans le groupe constitué par la silice, les différents types d'alumine, les silices alumines, le charbon, et de préférence dans le groupe constitué par les différents types d'alumine.Thus, it has surprisingly been found that it is possible to carry out the hydrogenation of an ester to alcohol according to the following scheme

in a continuous or batch reactor under a total pressure of between 10 and 100 bar and preferably between 30 and 80 bar, although it can operate without inconvenience, for example, up to 300 bar, at a temperature between 150 and 300 C and preferably between 180 and 2500C and with a hydrogen to ester molar ratio of between -2 and 10 and more advantageously between 2 and 5.This reaction is feasible under the conditions previously specified if a supported catalyst containing the elements is used. following: the rhenium whose weight percentage is chosen between 0.5 and 5% and preferably between 0.5 and 3%, and at least one metal of group VIII, preferably a noble metal of group VIII and more particularly chosen in the group consisting of iridium, palladium, platinum, rhodium and ruthenium and whose weight percentage is chosen between 0.01 and 3% and more particularly between 0.1 and 1%; the support may be chosen from the group consisting of silica, the various types of alumina, silica aluminas, and coal, and preferably from the group consisting of the different types of alumina.

 The catalyst can be prepared by different impregnation procedures of the support and the invention is not limited to a specific procedure. The impregnation operation consists, for example, in bringing the preformed support into contact with an aqueous solution of a compound of the noble metal chosen, the volume of solution being in excess of or equal to the retention volume of the support. volume. After allowing contact between the support and the solution for several hours, the impregnated support is filtered, washed with distilled water and then dried. The soluble rhenium compound is then impregnated on the preimpregnated support with the noble metal compound and dried. Another procedure is to impregnate the preformed support with a common aqueous solution of a noble metal compound and a composed of rhenium, the volume of the solution being equal to or greater than the retention volume of the support.

 Another method is to mix the wet support powder with the precursors of the catalyst and then to form and dry.

Examples of metal precursors that can be used in the preparation of the catalyst are the following:
For the noble metal, it is possible to use compounds such as chlorides, nitrates or soluble organic acid salts in the impregnating solvent, for example palladium chloride, rhodium or ruthenium, hexachloroplatinic or hexachlororidic acids, nitrates of palladium or rhodium, soluble salts of organic acids such as palladium acetate, but also the chlorides or nitrates of palladium tetrammine, platinum tetrammine, rhodium hexammine, ruthenium hexammine.On can also be used organometallic compounds of noble metals in solution in a hydrocarbon, for example in a saturated paraffinic hydrocarbon whose hydrocarbon chain contains from 6 to 12 carbon atoms (hexane, heptane, octane, nonane, decane, undecane, dodecane), in a naphthenic hydrocarbon which contains from 6 to 12 carbon atoms (cyclohexane, methylcyclohexane, ethylcyclohexane, decahydronaphthalene for example) or in a hydrocarbon romatic containing from 6 to 11 carbon atoms (benzene, toluene, ethylbenzene, ortho meta and para-Xylene, i-, 2,3,4 tetramethylbenzene and pentyl-benzene, for example): palladium acetates, rhodium acetylacetonates are preferably used , ruthenium, platinum and / or iridium. In this case, after impregnation with the organic solution, the catalyst is advantageously heated in air between 110 and 5000C and preferably between 110 and 4000C. The impregnation of rhenium is then carried out as in the case of impregnation in aqueous solution.

 The rhenium compound must be soluble in the impregnation solvent: for example, rhenium heptoxide and ammonium perrhenate, among others, are compounds which can be used to bind rhenium to the catalyst from aqueous solution of impregnation.

 The support can be of varied nature, as already mentioned above. A particularly suitable support has specific characteristics such as a specific surface area, determined by the BET method, of between 10 and 500 square meters per gram and preferably between 50 and 500 square meters per gram and a total pore volume of between 50 and 500 square meters. and 130 cubic centimeters per 100 grams of carrier and preferably between 80 and 110 cubic centimeters per 10 grams of carrier. It should be noted that the use of a support having a specific surface area of less than 50 square meters per gram, in order to prepare said catalyst, leads to a catalyst that is simply less active but whose transformation selectivity remains at least equivalent. On the other hand, if a support whose pore volume is less than 50 cubic centimeters per 100 grams is used, the final catalyst exhibits an equivalent activity with identical specific surface area, but a considerably lower selectivity.

Once the two metals are fixed on the support, the catalyst advantageously undergoes an activation treatment under hydrogen at high temperature, for example 300-5500C, in order to obtain an active metal phase. The procedure of this treatment in hydrogen consists, for example, in a slow rise in the temperature under a stream of hydrogen
Up to the maximum reduction temperature, between 300 and 550 ° C. and preferably between 350 and 4500 ° C., followed by holding for 1 to 6 hours at this temperature, if the reduction is carried out above 55 ° C. and below 3000C the catalyst is less active.

 In some cases, it is useful to calcine in air at 350-550 ° C before hydrogen activation.

The following nonlimiting examples illustrate the invention.

Example 1
It is proposed to manufacture ethyl alcohol from ethyl acetate in a dynamic fixed bed reactor in the presence of a catalyst containing 0.1% by weight of palladium and 1.8% by weight of rhenium. deposited on a silica support having a specific surface area equal to 300 square meters per gram and an equal total pore volume
3 to 90 cm per 100 grams.

 The catalyst is prepared by the so-called dry impregnation method, in which the volume of the impregnation solution is equal to the retention volume of the support, an aqueous solution of palladium chloride followed by drying. in an oven at 1100C.

The impregnation of the rhenium is then carried out by the same method of dry impregnation on the support, already impregnated with palladium chloride and dried, using an aqueous solution of ammonium perrhenate. The silica support, then impregnated with the two metal precursors, is then dried in an oven at 110 ° C. for 24 hours.

 A quantity of catalyst, known precisely, is then introduced into the central zone of the tubular reactor, in which the hydrogenation of the ethyl acetate will be carried out, and undergoes a reduction in hydrogen by progressive temperature rise up to 4500C before the catalytic test.

 The catalytic test unit is equipped with all the necessary devices for the regulation and control of temperature, pressure, charge flows (in this case, ethyl acetate) and hydrogen.

 The liquid and gaseous products obtained are measured and analyzed by gas chromatography.

 The measurements are carried out after 4 hours of injection of the charge, in order to overcome the phenomena related to possible activation of the catalyst.

The operating conditions chosen are as follows
hydrogen ratio on hydrocarbon substrate = 5 (mole / mole)
volume space velocity = 0.75 l / l / h
temperature = 230 to 2900C
total pressure = 50 bar
The results are summarized in Table I: The conversions and yields are expressed as weight percent based on the amount of ethyl acetate injected and the selectivities as weight percent relative to the converted acetate fraction. ethyl.

The rise in temperature leads to an increase in activity and a decrease in selectivity, resulting in increased formation of acetaldehyde
If we compare the first and last lines of Table 1, all the experiments having been carried out with the same sample of catalyst, we can realize that the performances of said catalyst are stable: 30 hours of operation have elapsed between the first and last line of Table 1. TABLE I
HYDROGENATION OF ETHYL-CATALYST ACETATE CONTAINING 0.1% PALLADIUM AND 1.8% RHENIUM.

Tempe <SEP> Pressure <SEP> Conversion <SEP> Selectivity <SEP> Efficiency <SEP> Selectivity <SEP> in <SEP> Efficiency <SEP> in <SEP> Selectivity <SEP> in
<tb> total <SEP> total <SEP> Threshold <SEP> in <SEP> ethanol <SEP> ethanol <SEP> acetaldehyde <SEP> acetaldehyde <SEP> hydrocarbons
<tb> (C) <SEP> (bars) <SEP>% <SEP>% <SEP>% <SEP>% <SEP>% <SEP>%
<tb> 250 <SEP> 50 <SEP> 65.0 <SEP> 85.0 <SEP> 55.2 <SEP> 8.5 <SEP> 5.5 <SEP> 6.5
<tb> 230 <SEP> 50 <SEP> 48.0 <SEP> 92.0 <SEP> 44.2 <SEP> 5.0 <SEP> 2.4 <SEP> 3.0
<tb> 270 <SEP> 50 <SEP> 74.0 <SEP> 77.0 <SEP> 57.0 <SEP> 12.0 <SEP> 8.9 <SEP> 11.0
<tb> 250 <SEP> 50 <SEP> 66.0 <SEP> 86.0 <SEP> 56.8 <SEP> 9.0 <SEP> 6.0 <SEP> 5.0
<Tb>
Example 2
It is proposed to manufacture ethyl alcohol from ethyl acetate in the presence of a catalyst containing 2% by weight of palladium and 1.8% by weight of rhenium. The preparation and operation of the catalyst are identical to those of Example 1.

 In this case, operation is carried out with a temperature range of between 230 and 2900 ° C. and a pressure range of 10 to 50 bars.

The results are summarized in Table II. We observe that
The rise in temperature increases the activity but decreases the selectivity, in the same way as in Example 1.

The pressure increase has a beneficial effect on activity and selectivity
Increasing the palladium content decreases the selectivity.

Example 3
In order to specify the absolute necessity of using a catalyst containing both a noble metal and rhenium, the following three catalysts prepared according to the technique described in Example 1 were compared with the same silica support.

TABLE II
HYDROGENATION OF ETHYL ACETATE
CATALYST CONTAINING 2% PALLADTUM AND 1.8% RHENIUM.

Tempe <SEP> Pressure <SEP> Conversion <SEP> Selectivity <SEP> Efficiency <SEP> Selectivity <SEP> in <SEP> Efficiency <SEP> in <SEP> Selectivity <SEP> in
<tb> rature <SEP> Total <SEP> Weight <SEP> in <SEP> ethanol <SEP> in <SEP> ethanol <SEP> acetaldehyde <SEP> acetaldehyde <SEP> hydrocarbons
<tb> (C) <SEP>% <SEP>% <SEP>% <SEP>% <SEP>% <SEP>%
<tb> 290 <SEP> 50 <SEP> 85.0 <SEP> 45.9 <SEP> 39.0 <SEP> 20.0 <SEP> 17.0 <SEP> 34.1
<tb> 270 <SEP> 50 <SEP> 77.0 <SEP> 66.0 <SEP> 50.8 <SEP> 14.5 <SEP> 11.2 <SEP> 19.5
<tb> 250 <SEP> 50 <SEP> 58.0 <SEP> 70.0 <SEP> 40.6 <SEP> 8.5 <SEP> 4.9 <SEP> 21.5
<tb> 230 <SEP> 50 <SEP> 45.0 <SEP> 80.0 <SEP> 36.0 <SEP> 7.3 <SEP> 3.3 <SEP> 12.7
<tb> 270 <SEP> 30 <SEP> 55.2 <SEP> 56.2 <SEP> 31.0 <SEP> 3.5 <SEP> 1.9 <SEP> 40.3
<tb> 270 <SEP> 10 <SEP> 30.0 <SEP> 50.0 <SEP> 15.0 <SEP> 5.0 <SEP> 1.5 <SEP> 45.0
<Tb>
Catalyst A: weight contents in palladium and in
rhenium equal to 0.1% and 1.8% respec
deeply
Catalyst B: rhenium content equal to 2.0%
Catalyst C: palladium content equal to 1% so that the total number of metal atoms on the catalyst is constant.

The three catalysts were tested under the following conditions: 2300C - Pressure = 50 bar - space velocity volume
equal to 0.75 liter of ethyl acetate per liter of catalyst
and per hour.

The results are collated in Table III
It is clear that both palladium alone and rhenium alone do not make it possible to obtain high yields of alcohol, it is indeed the combination of rhenium and a noble metal, in this case palladium, which makes it possible to get good returns.

Example 4
It is proposed to manufacture ethyl alcohol from ethyl acetate according to the procedure developed in Example 1 but where the palladium is replaced by iridium, platinum, rhodium and ruthenium. The rhenium-associated second metal content is 0.1% for rhodium and ruthenium and 0.27 for platinum and iridium so as to obtain the same number of noble metal atoms on the support. The impregnation of platinum is carried out by a solution of hexachloroplatinic acid, that of iridium by a solution of hexachlororic acid, that of rhodium by a solution of rhodium trichloride and that of ruthenium by. a solution of ruthenium trichloride. The results obtained in the hydrogenation of ethyl acetate are grouped together in Table IV. The operating conditions adopted are identical to those of Example 3: temperature 230 ° C-pressure: 50 bar and space velocity volume, VVH , equal to TABLE III
HYDROGENATION OF ETHYL ACETATE IN THE PRESENCE OF CATALYSTS:
A: 0.1% Pd and 1.8% Re deposited on silica
B: 1.8% Re deposited on silica
C: 1% Pd deposited on silica

Catalyst <SEP> Conversion <SEP> Selectivity <SEP> Efficiency <SEP> in <SEP> Selectivity <SEP> in <SEP> Efficiency <SEP> in <SEP> Selectivity <SEP> in
<tb> Ponderal <SEP>% <SEP> in <SEP> ethanol <SEP>% <SEP> ethanol <SEP>% <SEP> acetaldehyde <SEP>% <SEP> acetaldehyde <SEP>% <SEP> hydrocarbons <SEP >%
<tb> A <SEP> 48 <SEP> 92 <SEP> 44.2 <SEP> 5 <SEP> 2.4 <SEP> 3
<tb> B <SEP> 5 <SEP> 80 <SEP> 4 <SEP> - <SEP> - <SEP> 20
<tb> C <SEP> 15 <SEP> 70 <SEP> 10.5 <SEP> 8 <SEP> 1.2 <SEP> 22
<tb> 0.75 liter of ethyl acetate per liter of catalyst per hour.

 All catalysts resulting from a combination of rhenium with a transition metal selected from the group consisting of platinum, iridium, rhodium and ruthenium, exhibit an activity equivalent to that of the palladium - rhenium combination. It should be noted that the associations which make it possible to obtain the best selectivities are in the order of palladium - rhenium, platinum - rhenium and rhodium - rhenium.

TABLE IV
HYDROGENATION OF ETHYL ACETATE IN PRESENCE
OF CATALYSTS OR RHENIUM IS ASSOCIATED WITH Ru Ru or Pt

<tb><SEP> Metal <SEP> Conversion <SEP> Yield <SEP> Yield <SEP> $ Selectivity <SEP> in
<tb> (% <SEP> weight) <SEP> by weight <SEP> ethanol <SEP> acetaldehyde <SEP> hydrocarbons
<tb><SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight) <SEP> (% <SEP> weight)
<tb><SEP> Rh <SEP> 45 <SEP> 40.5 <SEP> 1.3 <SEP> 7
<tb><SEP> (0,1)
<tb><SEP> Ru <SEP> 42 <SEP> 36 <SEP> 0.6 <SEP> 13
<tb><SEP> (0,1) <SEP>
<tb><SEP> Ir <SEP> 46 <SEP> 40 <SEP> 1.0 <SEP> 11
<tb><SEP> (0,2)
<tb><SEP> Pt <SEP> 47 <SEP> 42 <SEP> 1.8 <SEP> 6.8
<tb><SEP> (0,2)
<Tb>
Example 5
It is proposed to manufacture ethyl alcohol by hydrogenation of ethyl acetate under the operating conditions of Example 3 in the presence of a catalyst according to the invention which contains 0.1% of palladium and 5% of rhenium.

 54 percent of the ethyl acetate is converted; however, hydrocarbon production accounts for 22 percent of the reaction products formed. The increase in conversion due to a higher metal content therefore results in a decrease in the hydrocarbon degradation selectivity of the product alcohol.

Example 6
It is proposed to manufacture ethyl alcohol from ethyl acetate under the same conditions as those adopted for Example 3. The catalyst has palladium and rhenium contents respectively equal to 0.1% and 1%. , 8% by weight. Silicas of different characteristics are used as support. The results are given in Table V.

 Increasing the surface of the support does not cause any gain in activity but causes a decrease in the selectivity.

 The use of a lower surface support does not impair the selectivity but leads to a lower activity.

TABLE V
ACTIVITY AND SELECTIVITY OF CATALYSTS CONTAINING 0.1% PALLADIUM
AND 1.8% RHENIUM ON DIFFERENT SILICA SUPPORTS.

Support
<tb> Conversion <SEP> Selectivity <SEP> Efficiency <SEP> Selectivity <SEP> Efficiency <SEP> in <SEP> Selectivity <SEP> in
<tb> weight <SEP> in <SEP> ethancl <SEP> in <SEP> ethenol <SEP> in <SEP> acetalde- <SEP> acetaldehyde <SEP> hydrocarbons
<tb> Surface <SEP> Volume
<tb>% <SEP>% <SEP>% <SEP> hyde <SEP>% <SEP>% <SEP>%
<tb> specific <SEP> Porous
<tb> (m2 / g) <SEP> (cm3 / g)
<tb> 450 <SEP> 0.45 <SEP> 45 <SEP> 80 <SEP> 36 <SEP> 7 <SEP> 3.15 <SEP> 13
<tb> 40 <SEP> 0.80 <SEP> 25 <SEP> 92 <SEP> 23 <SEP> 8 <SEP> 2 <SEP><SEP> 0.1
<tb> 300 <SEP> 0.90 <SEP> 48 <SEP> 92 <SEP> 44.2 <SEP> 5 <SEP> 2.4 <SEP> 3
<Tb>
Example 7
It is proposed to manufacture ethanol from ethyl acetate in the presence of a catalyst based on palladium and rhenium deposited on an alumina whose characteristics are as follows
2 specific surface area equal to 150 m per gram and pore volume equal to 3 90 cm per 100 grams of support. Before the reduction prior to the catalytic test at 4500C in the reactor, half of the catalyst was calcined in air at 50 ° C.

The operating conditions adopted are as follows
- Temperature: 2300C
- Pressure: 50 bars
- VVH: 0.75 1/1 catalyst / hour
TABLE VI

<tb> Echantil- <SEP> Convert <SEP> Select <SEP> Efficiency <SEP> Select <SEP> Efficiency <SEP> Selectivity
<tb><SEP> lon <SEP> Weight <SEP> time <SEP> ethanol <SEP> time <SEP> acetal- <SEP> hydrocarbu
<tb><SEP> 7. <SEP> ethanol <SEP> Z <SEP> acetal- <SEP> hyde <SEP> Z <SEP> res <SEP> Z
<tb><SEP>%<SEP> Dehyde <SEP>%
<tb> Calcined <SEP> 52 <SEP> 91 <SEP> 47.3 <SEP> 7 <SEP> 3.6 <SEP> 2
<tb> then <SEP>
<tb> duit
<tb> Reduced <SEP> 12 <SEP> 74 <SEP> 8.9 <SEP> 12 <SEP> 1.4 <SEP> 14
<tb> without <SEP> cal
<tb> cination
<Tb>
The use of alumina makes it possible to obtain slightly better performances than those obtained when the silica is used as a support. Nevertheless it is necessary to calcine the catalyst so that it has a satisfactory activity.

Example 8
It is proposed to manufacture decanol-1 from decanoate or ethyl caprate in the presence of a catalyst identical to that of Example 2 and under the operating conditions of Example 3.

The weight distribution between the different products obtained after reaction is as follows
- Ethyl decanoate: 40%
- Decanol 1: 38.5%
- Decanal: 6 7
- Ethanol: 11.5%
- Hydrocarbons: 4%
Example 9
The same reaction as that described in Example 8 can be carried out in a typical grignard reactor, or autoclave at 2300C under a hydrogen pressure of 50 bar.

 After loading a 250 ml autoclave with 5 grams of 0.1% palladium and 1.8% rhenium catalyst, the reactor is then purged with hydrogen.

 After having admitted a hydrogen pressure of 5 atmospheres into the reactor, the mixture is heated to 250 ° C: the temperature is maintained for 2 hours.

After cooling and lowering the pressure of the reactor to atmospheric pressure, the ethyl caprate is injected by means of a syringe into the reactor. In the reaction chamber, a hydrogen pressure of 5 bar is then allowed. The reactor temperature is then raised to 2300C and the reactor pressure adjusted to 50 bar
After 6 hours of experimentation, the conversion is equal to 80% and the selectivity to alcohol (decanol plus ethanol) is equal to 94%. The yield of decanol 1 is 76%.

Claims (10)

1 - Process for the manufacture of alcohol, in which an orga acid ester  is treated with hydrogen in the presence of a catalyst,  characterized in that the catalyst contains a support, rhenium  and at least one noble metal of group VIII. 2 - Process according to claim 1, wherein the rhenium content  is 0.5 to 5% by weight and the noble metal content of the group  VIII from 0.01 to 3% by weight. 3 - Process according to claim 1, wherein the rhenium content  is from 0.5 to 3% by weight and the noble metal content of the group  VIII from 0.1 to 1% by weight. 4 - Process according to one of claims 1 to 3, wherein the metal  Group VIII noble is palladium. 5 - Process according to one of claims 1 to 4, wherein the support  has a surface area of 10 to 500 m2 / g and a pore volume of 0.5 to  1.3 cm3 / g. 6 - Process according to one of claims 1 to 4, wherein the support  has an area of 50 to 500 m2 / g and a pore volume of 0.8 to  1.1 cm3 / g. 7 - Process according to one of claims 1 to 6, wherein the support  is alumina. 8 - Process according to one of claims 1 to 7, wherein the pres  is 10 to 100 bars and the temperature is 150 to 3000C. 9 - Process according to one of claims 1 to 7, wherein the pres  is 30 to 80 bars and the temperature is 180 to 2500C. 10 - Process according to one of claims 1 to 9, wherein the rap  Hydrogen / ester molar port is from 2: 1 to 10: 1.