FR2521131A1 - Hydrogenolysis of carboxylic acid ester to alcohol(s) - using reduced mixt. of copper oxide and zinc oxide as catalyst - Google Patents

Abstract

A carboxylic acid ester is subjected to hydrogenolysis by contacting a vapour phase mixt. of the ester and hydrogen with a catalyst comprising to reduced mixt. of Cu oxide and Zn oxide at 75-300 (180-240) deg.C under an absolute pressure of 0.1-100 kg/sq.cm (9.8-9813kPa), pref. 0.1-50, esp 5-25 kg/sq.cm (9.8-4906, esp. 491-2453 kPa). The ester is pref. of formula R(COOR')n (I) or (R''COO)pR''') (II) (n and p are each 1-5 and the R's are indep. and opt. unsatd. and opt. substd. (a) cyclic hydrocarbon gps. in which one or more C atoms can be replaced by hetero-atoms from N, O and P. Pref. the various R gps. contain 1-12C). The prcess is used for the prodn. of alcohols. The process gives a negligible amt. of by-prods. or heavy prods and takes place under moderate conditions. The required alcohols are formed in high yields. The catalyst is simple and can be prepd. with reproducible activity.

Description

 The present invention relates to the hydrogenolysis of esters of carboxylic acids.

The hydrogenolysis of esters of inic carboxy acids has been the subject of numerous descriptions in the specialized literature. Normally, during such a reaction, the -CO-O- bond of the ester radical is broken, so that the acid part of the ester radical is reduced to alcohol, while the alcohol part is released in the alcohol state. free, in accordance with the following equation
R1COOR2 + 2H2 = R1CH2OH + HOR2 (I) where R1 and R2 each represent an alkyl radical, for example. As indicated on pages 129 and following in Catalytic Hydrogenation in Organic Synthesis "by
M. Freifelden, published by John Wiley and Sons Inc (1978), the catalyst of choice for this reaction is copper chromite with barium as promoter.

Typical reaction conditions are to maintain temperatures on the order of 2500C and pressures in the range of 225 to 250 atmospheres (about 22.81 to about 25.35 MPa). Although a good alcohol yield is often obtained using this hydrogenolysis technique of an ester, the temperature required for the conversion of the ester to alcohol also induces side reactions. For example, the resulting alcohol may undergo further hydrogenolysis and produce a hydrocarbon, or may react with the starting compound and produce an ester of higher molecular weight which is more difficult to hydrogenolyze.

 Besides these side reactions, copper chromite catalysts have other disadvantages for working on an industrial scale. In particular, the use of copper chromite catalysts is dangerous from an ecological point of view and requires the use of special and expensive handling techniques due to the toxicity of chromium. It is furthermore difficult to produce successive batches of copper chromite having reproducible catalytic activity.

U.S. Patent No. 2,079,414 describes a process for the catalytic hydrogenation of esters using catalysts such as fully or partially reduced molten copper oxide which may be supplemented with promoter oxides , such as manganese oxide, zinc oxide, magnesium oxide or chromium oxide. Particularly recommended catalysts are those comprising copper oxide supplemented with promoter chromium oxide, for example copper chromite. As indicated on page 3, right column, lines 57 and following: "For work in the vapor phase, it is preferable to use temperatures in the range from 3000C to 4000C". It is also indicated that "The most conversions favorable alcohols are obtained under the highest pressures which can be reached in the available equipment and at the lowest temperatures compatible with an admissible reaction rate "(page 4, right column, lines 2 and following). The examples describe successive batch reactions and in all cases the absolute pressure is 2,500 psi or more (17250 kPa or more), while the temperature is always 2500C or more and most often exceeds 3000C. A limitation in this process is that methyl esters cannot be used because methanol, which would be a hydrogenation product of a methyl ester, undergoes gas decomposition (see page 5, right column, lines 58 and Similar considerations would appear to prevent the app
Cation of the formic acid ester process because the formic acid part would also be likely to give methanol.

 Other indications for the use of chromites as catalysts for the hydrogenation of esters are given in US Patent No. 2,109,844.

 Example 4 of U.S. Patent No. 3,197,718 describes the preparation of a copper-zinc catalyst which can be used for the liquid phase hydrogenation of oils and fats under pressures of more than 120 kg / cm2 (11,776 kPa) and a temperature of 320 C.

 U.S. Patent No. 2241417 describes the production of higher aliphatic alcohols by liquid phase hydrogenation of glycerides in the presence of copper-containing catalysts at temperatures of 200 to 4000 C at pressures of 60 to 500 atmospheres ( 5844 to 49033 kPa).

 The hydrogenolysis of esters to saturated hydrocarbons by means of catalysts containing as essential constituents a component providing indium or rhodium and a component providing a halogen is described in US Patent No. 4,067,900.

 The catalytic hydrogenolysis of formic esters present in the products of the oxo reaction by means of nickel catalysts is described in German Democratic Republic patent No. 92440 (see Chem. Abs., 124069j, Vol. 78 (1973), page 439 ).

Other references to formate hydrogenation include an article by E. Lederle, Anales Real
Soc. Spanish. Fis. y Quim. (Madrid) 57B, pages 473-5 (1961). Likewise, Federal Republic of Germany Patent No. 902375 describes the production of methanol by hydrogenation of alkyl formates under pressures of 20 to 50 atmospheres (1961 to 4903 kPa) using copper chromite catalysts; and includes a passage suggesting incorporating zinc oxide into the catalyst.

 The catalytic cleavage of esters of formic acid is described in English patent No. 1277077.

According to this proposal, a hydrogenation catalyst containing copper and nickel is used, but it is indicated that the formyl radical is dehydrogenated during the reaction and gives rise to carbon monoxide.

The production of ethyleneglycol by hydrogenolysis is suggested by various references, in particular the United States patent of America No. 4113662 which describes the hydrogenation of esters into alcohols at temperatures of 150 ° C. to 4500 ° C. under manometric pressures of 500 to 10,000 Jp / inch2 (3,450 to 69,000 kPa) using catalysts comprising cobalt, zinc and copper. Examples 4, 5 and 8 describe comparison experiments on a polyglycolide and methyl glycolate with oxides of
Cu-Zn as catalyst at 2500C at a pressure of at least 2800 pounds / inch 2 (19421 kPa), that is to say under conditions in which the ester (polyglycolide or methyl glycolate) is in phase liquid. The patent of
United States of America No. 2305104 describes the hydrogenation of alkyl glycolates using catalysts containing Zn, Cr and Cu to produce ethylene glycol. The hydrogenation in the vapor phase of oxalic esters at temperatures of 150 ° C. to 3000 ° C. for the production of ethylene glycol has been described in US Pat. No. 4,112,145; the method by which a copper chromite or copper zinc chromite catalyst is used and the oxalic ester must have a sulfur content of less than 0.4 ppm.

 It would be interesting to have a process for carrying out the hydrogenolysis of esters with negligible formation of by-products or "heavy products", which can be carried out under moderate conditions.

 It would also be advantageous to have a process for carrying out the hydrogenolysis of form esters and methyl esters without appreciable decomposition of the methanol formed during the reaction.

 It would also be desirable to have a hydrogenolysis process in which a simple catalyst is used which can be prepared with reproducible catalytic activity.

 The present invention therefore aims to provide an improved process for carrying out the hydrogenolysis of esters which can be carried out under moderate conditions.

 It also aims to provide a process for carrying out the hydrogenolysis of formic esters which gives high yields of methanol at high conversions.

 It further aims to provide a process for producing ethanol by conducting the hydrogenolysis of acetic esters with a high yield and with high conversions under moderate conditions.

 It further aims to provide an improved process for the production of ethylene glycol from oxalic esters or from glycolic acid esters by catalytic hydrogenolysis under moderate conditions.

 It also aims to provide new hydrogenolysis pathways leading to diols, such as ethylene glycol, 1,2-propanediol, 1,4butanediol and 1,6-hexanediol, from diesters of 'carboxylic acids or monoesters of hydroxycarboxylic acids.

 It further aims to provide a process for carrying out the hydrogenolysis of methyl esters and formic esters under moderate conditions substantially preventing the decomposition of significant quantities of methanol formed under the maintained reaction conditions.

 It also aims to provide an improved process for the production of 1,4-butanediol by hydrogenolysis of butyrolactone.

 The subject of the invention is a process for carrying out the hydrogenolysis of a carboxylic acid ester, according to which a mixture in the vapor phase containing the ester and hydrogen is brought into contact with a catalyst comprising a reduced mixture of copper and zinc oxide at a temperature in the range of about 750C to about 3000C and at an absolute pressure in the range of about 0.1 kg / cm2 (about 9.8 kPa ) at approximately 100 kg / cm2 (approximately 9813 kPa).

 The ester can be essentially any vaporizable ester. Among the esters which may be mentioned, there are the esters of mono-di- and polycarboxylic acids which may be derived from monoalcohols, diols or polyols.

Examples of suitable esters are those of the general formula
R (COOR ') n as well as those of the general formula
(R "COO) pR"'
In the general formulas above, n and p each represent an integer, preferably from 1 to approximately 5, for example 1, 2 or 3, and R, R ', R "and R"' each represent a hydrocarbon radical optionally substituted saturated or unsaturated cyclic or acyclic, one or more carbon atoms of which may be replaced by heteroatoms, for example nitrogen, oxygen or phosphorus. Examples of possible substituents on the radicals R, R ', R "and R"' are oxygen atoms, as well as hydroxyl and alcohol radicals. Preferably, the radicals R, R ', R "and R"' each have 1 to about 12 carbon atoms.

Normally, the radicals R, R ', R "and R"' are chosen from the radicals alkyl, alkenyl, alkoxyalkyl, hydroxyalkyl, aryl, aralkyl, alkylaryl, alkoxyaryl, hydroxyaryl, cycloalkyl, alkylcycloalkylcycloalkyl, alkyl

These esters can be derived from the following acids
formic acid;
acetic acid;
propionic acid;
n- or iso-butyric acid;
n- or iso-valeric acid
caproic acid;
caprylic acid;
capric acid;
2-ethylhexanoic acid;
glycolic acid;
pyruvic acid;
cyclohexanecarboxylic acid;
benzoic acid;
o-, m- or p-toluic acid;
o-, m- or -methoxybenzoic acid;
napth-2-oic acid;
cinnamic acid;
oxalic acid;
malonic acid;
succinic acid;
glutaric acid;
adipic acid;
maleic acid;
fumaric acid;
acrylic acid;
methacrylic acid;
i- or XLcrotonic acid;
acetylenedicarboxylic acid;
methoxyacetic acid;
phenylacetic acid;
vanllic acid;
terephthalic acid;
o-salicylic acid;
Lactic acid;
citric acid;
t-hydroxybutyric acid;
furoic acid, and so on.

Preferably, the acid has 1 to about 12 carbon atoms.

Suitable monoalcohols, diols or polyols can be chosen from
methanol;
ethanol;
n- or iso-propanol;
n-, iso-, sec- or t-butanol;
pentane-1 or 2-ol;
2-methyl-butane-2, 3 or 4-ol;
hexanols;
heptanols;
octanols (e.g. 2-ethylhexanol);
cetyl alcohol;
lauryl alcohol;
furfuryl alcohol;
ethyleneglycol;
1,2- or 1,3-propylene glycol; 1, 4-butanediol;
1,6-hexanediol;
glycerol;
allyl alcohol;
vinyl alcohol;
phenol;
o-, m- or p-cresol;
benzyl alcohol;
phenylethyl alcohol;
- ethylene glycol monomethyl ether;
ethylene glycol monoethyl ether;
cyclohexanol;
mono-, di- or tri-ethanolamine, and so on.

Preferably, the monohydroxylated alcohol, the diol or polyol has no more than about 12 carbon atoms.

Examples of specific esters are
alkyl formates (for example, methyl, ethyl, n- or iso-propyl and n-, iso-, s- or t-butyl formates);
alkyl acetates (for example, methyl, ethyl, n- or iso-propyl and n-, iso-, s- or t-butyl acetates);
cycloalkyl acetates (for example, cyclohexyl acetate);
alkyl propionates (for example, n-propyl propionate);
alkyl n-butyrates (for example, n-butyl nbutyrate);
alkyl iso-butyrates (for example, iso-butyl iso-butyrate);
alcolyl n-valates (for example, n-amyl valerate);
alkyl iso-valerates (for example, methyl iso-valerate); ;
alkyl caproates (for example, ethyl caproate);
alkyl caprylates (for example, methyl caprylate);
alkyl caprates (for example, ethyl caprate);
alkyl 2-ethylhexanoates (for example, 2-ethylhexyl 2-ethylhexanoate);
vinyl acetate;
allyl acetate;
alkyl alkoxyacetates (for example, methyl methoxyacetate);
alkyl glycolates (for example, methyl and ethyl glycolates);
dialkyl oxalates (for example, dimethyl, diethyl and di-n-butyl oxalates);
dialkyl succinates (for example, dimethyl and diethyl succinates);
dialkyl adipates (for example, dimethyl and diethyl adipates);
ethylene glycol mono- and di-carboxylates (for example, ethylene glycol diformate, ethylene glycol mono and di-acetates, ethylene glycol di-nbutyrate, ethylene glycol oxalate and ethyldneglycol glycolate);
esters formed by a monocarboxylic acid and furfurylic acid (for example, furfuryl acetate);
alkyl esters of aromatic acids (e.g. methyl benzoate, ethyl benzoate, methyl o-toluate, methyl napth-2-oate, methyl phenylacetate and ethyl phenylacetate) ;
phenyl esters of monocarboxylic acids (for example, phenyl acetate);
benzylic esters of monocarboxylic acids (for example, benzyl acetate);
dialkyl maleates (for example, dimethyl maleate and diethyl maleate);
dialkyl fumarates (for example, dimethyl fumarate and diethyl fumarate);
dialkyl esters of acetylene dicarboxylic acid (for example, dimethyl acetylene dicarboxylate);
dialkyl malonates (for example, diethyl malonate);
alkyl glycolates (for example, methyl glycolate and ethyl glycolate);
alkyl lactates (for example, ethyl lactate);
alkyl pyruvates (for example, ethyl pyruvate);
alkyl cyclohexanecarboxylates (for example, methyl cyclohexanecarboxylate);
lactones (for example, gammabutyrolactone); And so on.

 In the process of the invention, the vapor phase mixture to be brought into contact with the catalyst contains, in addition to the ester, hydrogen either alone or as a mixture with other gases (advantageously inert gases a with respect to the ester and the catalyst). Gas mixtures containing hydrogen include inert gases such as nitrogen or carbon monoxide.

 By "gas containing hydrogen" should be understood for the purposes of the invention both substantially pure hydrogen and gas mixtures containing hydrogen.

 The hydrogenolysis process of the invention is carried out at a temperature of from about 750C to about 3000C, but often the preferred temperature can fall in the range of from about 1500C to about 2000C, for example with alkyl formates, it is most often typically around 1800C to around 2300C.

Sometimes a lower range may be preferred, for example with t-butyl formate, the preferred temperature range is from about 1300C to about 1900 C. The absolute total pressure is between about Oal kg / cm2 (approximately 9.8 kPa) and approximately 100 kg / cm2 (approximately 9813 kPa), but preferably it does not exceed approximately 50 kg / cm2 (approximately 4906 kPa), and more advantageously, it is approximately 5 kg / cm2 (approximately 491 kPa) to approximately 25 kg / cm2 (approximately 2453 kPa).

- The mixture of CuO and ZnO, before the reduction, preferably contains approximately 5 to approximately 958 by weight and typically approximately 10 to approximately 70% by weight of
CuO, besides about 95 to about 5% by weight and typically about 90 to about 30% by weight of ZnO. Therefore, the mixture may contain, for example, about 20 to about 40% by weight of CuO and about 60 to about 80% by weight of ZnO. For example, a preferred mixture comprises about 30 to about 36% by weight of
CuO and about 62 to about 68% by weight of ZnO.

Other particularly preferred mixtures include about 65 to about 85% by weight of CuO and about 35 to about 15% by weight of ZnO, for example mixtures comprising about 68 to about 75% by weight of CuO and about 32 to about 25 % by weight of ZnO. The hydrogenolysis catalyst may contain minor amounts of other substances such as carbon, sodium, titanium, zirconium, manganese, silica, diatomaceous earth, kieselguhr and aluminum oxide . These other materials usually do not form more than about 20% by weight to be calculated as oxide (except in the case of carbon). In the case of sodium, it is most favorable not to exceed approximately 0.5% by weight, to be calculated as oxide. Thus other preferred catalysts consist of mixtures comprising approximately 40 to approximately 50% by weight, so much CuO than
ZnO and oa about 20% by weight of alumina. The catalyst is however preferably essentially free from other metals, in particular from metals of the group
VIII of the periodic table, such as Fe, Co, Ni, Ru, Rh,
Pd, Os, Ir and Pt, as well as group VIB metals, such as Cr, Mo and W, in addition to Tc, Ag, Re, Au and Cd, and also other elements with an atomic number of 80 and more , for example Hg and Pb. By "substantially free" it should be understood that the catalyst does not contain more than approximately 0.1% by weight (that is to say not more than approximately 1000 ppm), and preferably not more than about 250 ppm of the element in question. The catalyst can be prepared according to any of the known methods for forming a mixed catalyst of copper oxide and zinc oxide. The catalyst can be prepared by fixing the separate oxides, by coprecipitation of the oxalates, nitrates and acetates, then by calcination. The coprecipitation method is preferred. Generally, the mixture of Cu0 and ZnO is reduced by hydrogen or carbon monoxide at a temperature in the range of about 1600C to about 2500C for a few hours, preferably 8 to 24 hours, before be brought into contact with the vapor phase mixture containing the ester and hydrogen. If the catalyst is supplied in pre-reduced form, the time required for the reduction can be reduced in proportion.

 The mixture of CuO and ZnO is reduced before being used as a catalyst in the hydrogenolysis stage. The hydrogen and / or carbon monoxide are preferably mixed with a dilution gas, such as water vapor, nitrogen or a combustion gas to maintain the temperature of the catalytic bed and for the evacuation of reduction heat.

 The reduction of the mixture of CuO and ZnO is completed when no quantity of hydrogen or carbon monoxide reacts any more, as indicated by the analysis of the gas at the inlet and at the outlet. By means of hydrogen, the complete reduction of the mixture takes place when the total amount of water produced during the reduction is equal to the stoichiometric amount of water which should be produced when a determined amount of copper oxide is reduced in copper.

This value is approximately 0.079 kg of water per kg of catalyst, for a mixture containing 35% by weight of
CuO.

 An inert support material can be incorporated into the composition of the hydrogen genesis catalyst. The catalyst is generally formed into pellets, tablets or other suitable bodies before being used, according to conventional techniques for this purpose.

It is advantageous that the mixture of Cu'O and
ZnO has an internal specific surface of approximately 25 to approximately 50 m2 / g. The internal specific surface can be determined according to the well known BET method.

 The process of the invention is most advantageously carried out in continuous operation, although semi-continuous operation or in successive batches is also applicable. According to the preferred process in continuous operation, an ester or a mixture of esters, a gas containing hydrogen and, optionally, a carrier gas such as nitrogen, can be combined and brought into contact in vapor phase under the desired pressure with the catalyst. The reaction zone is advantageously an oblong tubular reactor into which the catalyst is inserted.

 During the hydrogenolysis process of the invention, the main reaction observed with many esters is that of equation (I) above. Consequently, a monocarboxylic ester in this case gives a mixture of alcohols, one of which is derived from the carboxylic acid part and the other of which is derived from the alcohol part. The esters of dicarboxylic acids and those of polyols give the corresponding diols and polyols. For example, the dialkyl oxalates give ethylene glycol and the corresponding alkanol. However, in certain circumstances, the products include hydrocarbons originating from the carboxylic acid part and / or from the alcohol part. It is to be presumed that the alcohols are formed first, but that they are then rapidly hydrogenated to the corresponding hydrocarbons under the maintained reaction conditions. In normal working conditions, alcohols are the major products when food is formed by alkyl esters of aliphatic acids. However, in the case of esters of aromatic acids, such as benzoic acid, or of aromatic alcohols, such as benzyl alcohol, the major product obtained from the aromatic acid part or from the aromatic alcohol part, depending on the case, is usually the corresponding hydrocarbon.

 In some cases, an alcohol formed as a primary product may undergo a new reaction. For example, the hydrogenolysis of diethyl maleate or diethyl succinate can give 1,4-butanediol to be expected as the primary product, but tetrahydrofuran. In addition, during the hydrolysis of t-butyl acetate, the products observed contain not only t-butanol, but also iso-butene, which is to be presumed to be formed by dehydration of the t-butanol under the maintained reaction conditions.

 The alcohol or alcohols and / or hydrocarbons (if they are liquefiable) produced by the hydrogenolysis reaction can be separated from the hydrogen by condensation and the excess hydrogen can be compressed and recycled to the reaction zone. The crude alcohol or hydrocarbon can be used in this form or can be further purified in a conventional manner, for example by fractional distillation. If desired, the possible unconverted fraction of the ester or mixture of esters can be separated from the reaction product and recycled to the reaction zone and, preferably, mixed with fresh feed gases before d '' enter the reaction zone.

 For the application of the process of the invention, the partial pressure of the ester can vary over a wide range, for example from about 0.05 kg / cm2 (4.9 kPa) if not less to about 10 kg / cm2 (981 kPa) if not more. However, care must be taken to ensure that at all times the temperature of the vapor phase mixture in contact with the catalyst is higher than the dew point of the ester under the maintained pressure conditions.

 The vapor phase mixture preferably contains at least one amount of hydrogen corresponding to the stoichiometric amount of hydrogen required for the hydrogenolysis. Usually, hydrogen is present in excess over the stoichiometric amount. In this case, the excess hydrogen remaining after the product has been isolated can be recycled to the catalytic reaction zone. It is evident from equation (I) above that 2 moles of hydrogen are required for the hydrogenolysis of each carboxylic acid ester radical contained in the ester molecule. If the ester contains a non-aromatic unsaturation (that is to say a double or triple carbon-carbon bond), these unsaturated bonds must also undergo hydrogenation under the maintained hydrogenolysis conditions. Therefore, the stoichiometric amount of hydrogen required to reduce 1 mole of an unsaturated monoester corresponds to 3 or 4 moles of hydrogen, if not more.

 Diesters require 4 moles of hydrogen per mole of diester, if saturated, for their hydrogenolysis, and non-aromatic unsaturated diesters may require 5 moles of hydrogen or more for the hydrogenolysis of 1 mole of diester.

Higher triesters and polyesters require 6 moles of hydrogen or more, depending on the number of ester groups and non-aromatic unsaturated bonds, per mole for hydrogenolysis.

 The hydrogen: ester molar ratio in the vapor phase mixture can vary within a wide range, for example from about 2: 1 to about 100: 1 or more for a monoester or from about 4: 1 to about 100: 1 or more for a diester. This ratio depends, at least to some extent, on the volatility of the ester used, as well as the number of ester groups in the ester to be reduced. Normally, the hydrogen: ester molar ratio is at least about 25: 1.

 Although the process of the invention is generally applicable to esters of carboxylic acids, it usually gives the best results with esters boiling at temperatures not exceeding about 3000C under atmospheric pressure. Although it is possible to use esters with even higher boiling points, the use of esters with higher boiling points limits the partial pressure of the ester which can be maintained in the mixture in vapor phase and , therefore, the rate of hydrogenolysis. When using esters with an extremely high boiling point, the reaction rates are therefore reduced in proportion.

 Some esters can undergo thermal decomposition at temperatures approaching 3000C and possibly at temperatures below their boiling point under atmospheric pressure. When using such esters, the temperature during the hydrogenolysis cannot be raised to the point where there is substantial thermal decomposition of the ester.

 Generally, it is preferable to use esters of monocarboxylic acids, preferably esters of aliphatic monocarboxylic acids formed by aliphatic alcohols having 2 to about 20 carbon atoms, or esters of dicarboxylic acids, preferably diesters of aliphatic dicarboxylic acids having 4 to about 16 carbon atoms.

 According to a particularly preferred aspect, the subject of the invention is a process for the production of ethylene glycol, according to which the hydrogenolysis of an ester of oxalic acid is carried out by bringing a mixture into contact in phase. vapor containing ester and hydrogen with a catalyst comprising a reduced mixture of copper oxide and zinc oxide at a temperature of about 750C up to about 3000C under an absolute pressure of about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa) and the resulting ethylene glycol is collected. During hydrogenolysis of oxalic acid esters, temperatures from about 1800C to about 2400C are preferred and preferred absolute working pressures range from about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa).

 According to another preferred aspect, the invention relates to a process for producing methanol, according to which the hydrogenolysis of an ester of formic acid is carried out by bringing a vapor phase mixture containing the ester into contact. and hydrogen with a catalyst comprising a reduced mixture of copper oxide and zinc oxide at a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0, 1 kg / cm2 (approximately 9.8 kPa) to approximately 100 kg / cm2 (approximately 9813 kPa) and the resulting methanol is collected. During the hydrogenolysis of formic acid esters to methanol, the temperature ranges from preferably from about 1300C to about 2200C, for example from about 1500C to about 1900C, and the absolute pressure preferably ranges from about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa ).

 According to yet another preferred aspect, the invention relates to a process for the production of ethanol, according to which the hydrogenolysis of an ester of acetic acid is carried out by contacting a vapor phase mixture containing 1 ester and hydrogen with a catalyst comprising a reduced mixture of copper oxide and zinc oxide - a temperature in the range of about 750C to about 3000C under absolute pressure in the range of about 0.1 kg / cm2 (approximately 9.8 kPa) to approximately 100 kg / cm2 (approximately 9813 kPa) and the resulting ethanol is collected. During the hydrogenolysis of the esters of acetic acid into ethanol, the temperature s Preferably ranges from about 1800C to about 2400C and the absolute pressure ranges from about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kpa).

 The invention also relates to a process for the production of 1,4-butanediol and / or tetrahydrofuran, according to which the hydrogenolysis of an ester of an acid chosen from maleic acid, fumaric acid is carried out. , acetyldnedicarboxylic acid and succinic acid, by bringing a vapor phase mixture containing the ester and hydrogen into contact with a catalyst comprising a reduced mixture of copper oxide and zinc, at a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa ) and collecting the resulting 1,4-butanediol and / or tetrahydrofuran. When producing l-, 4-butanediol and / or tetrahydrofuran according to such a process, it is preferable that the temperature ranges from about 1800C to about 2400C, while the preferred absolute pressure ranges from about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 to about 3435 kPa).

 The invention also further relates to a process for the production of ethylene glycol, according to which the hydrogenation of a glycolic acid ester is carried out by bringing into contact a vapor phase mixture containing the ester and hydrogen with a catalyst comprising a reduced mixture of copper oxide and zinc oxide, at a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0, 1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa) and the resulting ethylene glycol is collected.

When hydrogenolysis of the esters of glycolic acid to ethyleneglycol, it is preferable to work at a temperature of about 1800C to about 240 "C under absolute pressures of about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (around 3435 kPa).

 The invention also relates to a process for the production of 1,4-butanediol, according to which the hydrogenolysis of butyrolactone is carried out by bringing a vapor phase mixture containing butyrolactone and hydrogen into contact with a catalyst. comprising a reduced mixture of copper oxide and zinc oxide, at a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0.1 kg / cm2 (about 9 , 8 kPa) at about 100 kg / cm2 (about 9813 kPa) and the resulting 1,4-butanediol is collected. When hydrogenolysis of butyrolactone, it is preferable to choose a temperature in the range of about 1800C to about 240CO and an absolute pressure in the range of about 5 kg / cm2 (about 491 kPa) to about 45 kg / cm2 (approximately 4416 kPa). The best yields of 1,4-butanediol are generally achieved in the upper part of the pressure range, for example under an absolute pressure of about 25 kg / cm2 (about 2453 kPa) to about 45 kg / cm2 (about 4416 kPa ).

 In each case, the isolation of the hydrogenolysis products can be carried out in a conventional manner, for example by condensation and then, if desired, by fractional distillation under normal, reduced or high pressure.

 The invention is further illustrated by the following examples.

EXAMPLE 1.
N-butyl butyrate is pumped at a flow rate of 3.8 ml / hour in an electrically heated gas / liquid mixing device in which hydrogen is also admitted at an imposed rate and pressure.

The resulting vapor phase is passed through a thermally insulated pipe heated by electricity in a leading preheating coil! a tubular reactor packed with 146 ml of a powdered catalyst.

Both the tubular reactor and the preheating coil are immersed in a bath of molten salt heated to 1740C. The mixture is passed into the vapor phase leaving the reactor in a water-cooled condenser and the resulting condensate is collected in a water-cooled gas-liquid separator. The absolute pressure of the outgoing gas is adjusted to 10.55 kg / cm2 (1035 kPa). The uncondensed gases are then passed through an expansion valve, the gas flow being monitored downstream of this valve by means of a wet gas meter. A gas flow rate of 46.4 liters / hour is maintained throughout the experiment (measurement under atmospheric pressure).

 The liquid condensate is analyzed by gas chromatography in a 2-meter stainless steel column (external diameter of 6 mm) packed with polyethylene glycol (nominal molecular weight 20,000) on Chromosorb PAW, maintaining a helium current of 30 ml / minute and using a flame ionization detector. This instrument is fitted with a graphic recorder equipped with a peak integrator and is calibrated using a mixture of n-butanol and n-butyl butyrate of known constitution. The condensate appears to contain a mixture of 99.62% by weight of butanol and 0.28% by weight of n-butyl butyrate, which corresponds to a conversion of 99.7% with a selectivity of substantially 100%.

The catalyst used in the present example is introduced into the reactor in the form of a coprecipitated mixture of CuO and ZnO containing 33 + 3% of
CuO and 65 + 3% ZnO, with a particle size of the interval from 1.2 mm to 2.4 mm, having an internal specific surface of approximately 45 m2 / g. This catalyst is prereduced in the reactor with a gas mixture at 5% by volume of H2 in N2 at 2000C for 17 hours, then by means of pure hydrogen at 2000C for 8 hours, the gas flow rate in each being approximately 20 liters / hour (measurement under atmospheric pressure using the wet gas meter), the absolute gas pressure being 10.55 kg / cm2 (1035 kPa). After this prereduction, the catalyst is maintained at all times in an atmosphere containing hydrogen.

EXAMPLE 2.
The process of Example 1 is repeated using ethyl acetate instead of n-butyl butyrate at a flow rate of 7.4 ml / hour, with a hydrogen flow rate of 41.9 liters / hour ( measured at atmospheric pressure using the wet gas meter). During this experiment, the temperature of the salt bath is 1850C and the absolute pressure of the gas at the outlet is 10.55 kg / cm2 (1035 kPa). The liquid condensate appears to contain a minor amount of ethyl acetate, a major amount of ethanol and a trace of n-butanol.

The conversion observed in ethanol is 97.1% and the selectivity in favor of ethanol is approximately 95%.

EXAMPLE 3.
By repeating the process of Example 2 at a salt bath temperature of 2030C with a gas flow rate of 160.4 liters / hour and a liquid feed rate (ethyl acetate) of 34.8 ml / hour , both ethyl acetate and methanol are identified in the liquid condensate, but without the formation of sensitive quantities of n-butanol. The conversion of the ester is 82.6% and the selectivity in favor of ethanol is approximately 100%.

EXAMPLE 4.
The method of Example 1 is applied by means of isopropyl formate which is delivered at the rate of 23.4 ml / hour with a gas flow rate of 35.1 liters / hour (measurement under atmospheric pressure at using the wet gas meter). The temperature of the salt bath is 1850C and the absolute pressure of the gas at the outlet is 10.55 kg / cm2 (1035 kPa). On analysis, the liquid condensate appears to contain as a major constituent, apart from a trace of acetone and nbutanol, methanol and isopropanol. The conversion of the starting ester is substantially 100% and the selectivity in favor of methanol is approximately 99%.

EXAMPLE 5.
The process of Example 1 is repeated using methyl acetate instead of n-butyl butyrate at a flow rate of 75 ml / hour with a hydrogen flow rate of 115.2 liters / hour (measurement under pressure atmospheric). During this experiment, the temperature of the salt bath is 1940C and the absolute pressure of the outlet gas is 9.49 kg / cm2 (935 kPa). The liquid condensate appears to contain 55.7% by weight of methyl acetate, 10.02% by weight of ethyl acetate, 15.248 by weight of ethanol and 18.95% by weight of methanol. The conversion observed in methanol is 52.4 mol%.

EXAMPLE 6.
The process of Example 5 is repeated at a salt bath temperature of 2170C under an absolute outlet gas pressure of 8.86 kg / cm2 (868 kPa) with a gas flow rate of 225 liters / hour and a flow rate 75 ml / hour feed liquid (methyl acetate). The liquid condensate appears to contain 19.318 by weight of methyl acetate, 11.19% by weight of ethyl acetate, 35.64% by weight of ethanol and 31.968 by weight of methanol. The conversion into methanol observed is 72.40 mol%.

EXAMPLE 7.
7 The process of Example 1 is repeated using sec-butyl acetate instead of n-butyl butyrate at a feed rate of 118 ml / hour and a hydrogen rate of 143.9 liters / hour (measurement under atmospheric pressure). During this experiment, the temperature of the salt bath is 2030C and the absolute pressure of the outlet gas is 10.55 kg / cm2 (1035 kPa). The liquid condensate appears to contain 6.08 by weight of ethyl acetate, 20.6% by weight of ethanol, 40.1% by weight of sec-butyl acetate, and 33.3% by weight of sec-butanol. The conversion into ethanol observed is 59.9 mol% and the selectivity in favor of ethanol and sec-butanol is substantially 100%.
EXAMPLE 8.
Di-n-butyl oxalate is pumped at a flow rate of 15.4 ml / hour in a gas / liquid mixing device heated with electricity, also supplied with hydrogen at an imposed flow rate and under pressure, by a heated pipe. has electricity. The resulting vapor mixture is passed through a heat-insulated electrically heated line to a preheating coil before passing through a stainless steel tubular reactor packed with 15 ml of a crushed catalyst. Both the tubular reactor and the preheating coil are immersed in a bath of molten salt. The temperature of the salt bath is adjusted until the temperature of the vapor phase mixture, observed using a thermocouple arranged immediately upstream of the catalytic bed, ie 2400C. The mixture is passed into the vapor phase leaving the reactor in a water-cooled condenser, then in a second refrigerated condenser in which a refrigerant is passed to -150C. The resulting condensate is collected in a gas / refrigerated liquid separator also maintained at -150 C. The absolute pressure of the outlet gas is adjusted to 15.5 kg / cm2 (1518 kPa). The uncondensed gases are then passed through an expansion valve, the gas flow being monitored downstream of this valve using a wet gas meter. A gas flow of 156.6 liters / hour (measured under atmospheric pressure) is maintained throughout the experiment. The liquid space velocity of di-n-butyl oxalate is 1.03 hours.

 The liquid condensate is analyzed by gas chromatography using a 2 meter stainless steel column (external diameter of 6 mm) packed with polyethylene glycol (nominal molecular weight 20,000) on Chromosorb PAW, with a helium flow rate of 30 ml / minute and using a thermal conductivity detector. The instrument is fitted with a graphic recorder equipped with a peak integrator and is calibrated using a mixture of ethanol, n-butanol, ethyl glycolate, n-butyl glycolate, ethylene glycol and di-n-butyl oxalate of known composition. The condensate is found to contain a mixture of 0.60% by weight of ethanol, of 31.37% by weight of n-butanol, of 0, 1% by weight of ethyl glycolate, 0.7% by weight of n-butyl glycolate, 15.88% by weight of ethyleneglycol and 70.15% by weight of n-butyl oxalate, which corresponds to a conversion of 27.5% with a selectivity of 93.0% in favor of ethyleneglycol.

The catalyst used in the present example is introduced into the reactor in the form of a coprecipitated mixture of CuO and ZnO containing 33 + 3% of
CuO and 65 + 3% ZnO and having a particle size of the interval from 1.2 to 2.4 mm and an internal specific surface of approximately 45 m2 / g. This catalyst is prereduced in the reactor by means of a gas mixture at 5% by volume of H2 in N2 at 2000C for 16 hours, then by means of pure hydrogen at 2000C for 16 hours, the gas flow rate being, in each case, approximately 20 liters / hour (measurement under atmospheric pressure) and the absolute pressure of the gas being 15.5 kg / cm2 (1518 kPa). After this pre-reduction stage, the catalyst is maintained at all times in an atmosphere containing hydrogen.

EXAMPLE 9.
The process of Example 8 is repeated using di-n-butyl oxalate at the feed rate of 30.6 ml / hour and with a hydrogen rate of 284 liters / hour (measured under atmospheric pressure ). The liquid condensate is found to contain 0.25% by weight of ethanol, 14.62% by weight of n-butanol, 0.50% by weight of n-butyl glycolate, 10.19% by weight of ethylene glycol and 75.73% by weight of di-nbutyl oxalate. The conversion into ethyleneglycol observed is 21.5% and the selectivity in favor of ethylene glycol is 94.7%.

EXAMPLE 10.
The process of Example 8 is repeated using diethyl succinate at a feed rate of 15.4 ml / hour. The absolute pressure in the reactor is 15.5 kg / cm2 (1518 kPa) and the inlet temperature is 2420C. The gas flow rate is 157.8 liters / hour (measurement under atmospheric pressure). the hourly liquid space velocity is 1.03 hour'l.

Analysis by gas chromatography reveals that the condensate contains
16.96% by weight of methanol
4.40% by weight of tetrahydrofuran
0.8% by weight of n-butanol
66.53% by weight of diethyl succinate.

 This corresponds to a 32.2% conversion of diethyl succinate with a selectivity of 85.0% in favor of tetrahydrofuran and 14.0% in favor of n butanol.

EXAMPLE 11.
The process of Example 8 is repeated using diethyl maleate at a feed rate of 16.9 ml / hour. The absolute pressure in the reactor is 15.1 kg / cm2 (1484 kPa) and the inlet temperature is 2220C. The gas flow rate is 156.6 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.13 hours.

Analysis of the gas chromatography indicates that the condensate contains
2.57% by weight of tetrahydrofuran
8.49% by weight of ethanol
0.4% by weight of n-butanol
14.24% by weight of diethyl succinate
64.08% by weight of diethyl maleate.

 This corresponds to a 22.2% conversion of diethyl maleate to tetrahydrofuran and nbutanol with a selectivity of 87.0% in favor of tetrahydrofuran and 12.7% in favor of n-butanol as well as a conversion of 15.6% diethyl succinate.

EXAMPLE 12.
The process of Example 8 is repeated using cyclohexyl acetate at the feed rate of 17.3 ml / hour. The absolute pressure in the reactor is 15.5 kg / cm2 (1518 kPa) and the inlet temperature is 2290C. The gas flow rate is 157.2 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.15 hours.

Analysis by gas chromatography indicates that the condensate contains
1.14% by weight of cyclohexane
1.36% by weight of ethyl acetate
24.43% by weight of ethanol
52.16% by weight of cyclohexanol
7.86% by weight of cyclohexyl acetate.

 This corresponds to a 92.8% conversion of cyclohexyl acetate.

EXAMPLE 13.
The process of Example 8 is repeated using benzyl acetate at a feed rate of 47.8 ml / hour. The absolute pressure in the reactor is 16.9 kg / cm2 (1656 kPa) and the temperature at i1 inlet is 2350C. The gas flow rate is 466.2 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 3.19 hours 1.

Analysis by gas chromatography indicates that the condensate contains:
0.42% by weight of ethyl acetate
15.80% by weight of ethanol,
31.67% by weight of toluene
1.90% by weight of acetic acid
0.50% by weight of benzyl alcohol
41.33% by weight of benzyl acetate.

 This corresponds to a conversion of 58.7% of the benzyl acetate with a selectivity of 98.5% in favor of toluene.

EXAMPLE 14.
The process of Example 8 is repeated using methyl benzoate at a feed rate of 15.4 ml / hour. The absolute pressure in the reactor is 15.5 kg / cm2 (1518 kPa) and the inlet temperature is 2200C. The gas flow rate is 156.6 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.03 hours.

 The condensate separates into two layers, so that no attempt is made to perform an accurate analysis. However, gas chromatography indicates that the two major products are toluene and methanol. The conversion of methyl benzoate is estimated to have reached around 40% with barely 1% selectivity to benzyl alcohol.

EXAMPLE 15.
The process of Example 8 is repeated using ethyl phenylacetate at a feed rate of 1.7 ml / hour. The absolute pressure in the reactor is 15.5 kg / cm2 (1518 kPa) and the inlet temperature is 2150C. The gas flow rate is 157.8 liters per hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.11 hours.

Analysis by gas chromatography indicates that the condensate contains
12.16% by weight of ethanol
6.94% by weight of ethylbenzene
21.50% by weight of phenylethanol
53.04% by weight of ethyl phenylacetate
This corresponds to a conversion of 46.7% of ethyl phenylacetate with a selectivity of approximately 100% in favor of ethanol, 27.0% in favor of ethylbenzene and 72.9% in favor of phenylethanol.

EXAMPLE 16.
The process of Example 8 is repeated using ethylene glycol diacetate at a feed rate of 16.8 ml / hour. The absolute pressure in the reactor is 28.0 kg / cm2 (2746 kPa) and the inlet temperature is 1970C. The gas flow rate is 240 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.12 hour'l.

Analysis by gas chromatography indicates that the condensate contains
0.63% by weight of ethyl acetate
2.37% by weight of ethanol
10.99% by weight of ethylene glycol monoacetate
85.38% by weight of ethylene glycol diacetate.

 This corresponds to a conversion of 13.0% by weight of the ethylene glycol diacetate with a selectivity of 87.7% in favor of ethanol, 12.2% in favor of ethyl acetate and 100 % in favor of ethylene glycol monoacetate.

EXAMPLE 17.
The process of Example 8 is repeated using ethyl lactate at a feed rate of 15.9 ml / hour. The absolute pressure in the reactor is 16.4 kg / cm2 (1608 kPa) and the inlet temperature is 234 C. The gas flow rate is 156.6 liters / hour (measured under atmospheric pressure). The liquid hourly space velocity is 1.06 hour'l.

Analysis by gas chromatography indicates that the condensate contains
12.62% by weight of ethanol
0.25% by weight of n-propanol
14.41% by weight of i, 2-propanediol
64.49% by weight of ethyl lactate
This corresponds to a 34.7% conversion of ethyl lactate with a selectivity of 97.7% in favor of 1,2-propanediol and 2.3% in favor of npropanol.

EXAMPLE 18.
The process of Example 8 is repeated using dimethyl adipate at a feed rate of 16.7 ml / hour. The absolute pressure in the reactor is 29.5 kg / cm2 (2898 kPa) and the inlet temperature is 2330C. The gas flow rate is 240 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.11 hours.

Analysis by gas chromatography indicates that the condensate contains:
4.92% by weight of methanol
84.29% by weight of dimethyl adipate
6.44% by weight of 1,6-hexanediol.

 The condensate also contains a certain amount of other unidentified compounds.

 This corresponds to a 23.0% conversion of dimethyl adipate with a selectivity of approximately 100% in favor of methanol and approximately 95% in favor of 1,6-hexanediol.

EXAMPLE 19.
The process of Example 8 is repeated using t-butyl acetate at a feed rate of 18.3 ml / hour. The absolute pressure in the reactor is 26.7 kg / cm 2 (2622 kPa) and the inlet temperature is 2000 C. The gas flow rate is 156.6 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.22 hours.

Analysis by gas chromatography indicates that the condensate contains
19.87% by weight of ethanol
3.18% by weight of t-butanol
0.74% by weight of ethyl acetate
65.58% by weight of t-butyl acetate
6.518 by weight of water.

 This corresponds to a 56.5% conversion of t-butyl acetate. Although the selectivity in favor of ethanol and -butanol appears high, an accurate measurement of the selectivity is difficult because a fraction of t-butanol undergoes dehydration to iso-butene which is detected as a product, but not collected .

EXAMPLE 2.0.
The process of Example 8 is repeated using methyl methoxyacetate at a feed rate of 17.3 ml / hour. The absolute pressure in the reactor is 29 kg / cm2 (2850 kPa) and the inlet temperature is 2170C. The gas flow rate is 157.2 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.15 hour'l.

Analysis by gas chromatography indicates that the condensate contains
22,238 by weight of methanol
0.62% by weight of ethanol
46.55% by weight of 2-methoxyethanol
23.23% by weight of methyl methoxyacetate
4.53% by weight of methoxyethyl methoxyacetate
This corresponds to a conversion of 77.6% of methyl methoxyacetate with a selectivity of 2.0% in favor of ethanol, 93.2% in favor of methoxyethanol and 4.6% in favor of methoxyethyl methoxyacetate .

EXAMPLE 21.
The process of Example 8 is repeated using methyl cyclohexanecarboxylate at a feed rate of 16.0 ml / hour. The absolute pressure in the reactor is 14.8 kg / cm2 (1449 kPa) and the inlet temperature is 2170C. The gas flow rate is 156.0 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.07 hours,
Analysis by gas chromatography indicates that the condensate contains:
11.80% by weight of methanol
44.03% by weight of cyclohexylmethanol
42.50% by weight of methyl cyclohexanecarboxylate
This corresponds to a conversion of 57.8% with a selectivity of approximately 100% in favor of methanol and cyclohexanemethanol.

EXAMPLE 22.
The process of Example 8 is repeated using gamma-butyrolactone at a feed rate of 16.2 ml / hour. The absolute pressure in the reactor is 28.8 kg / cm 2 (2829 kPa) and the inlet temperature is 2260 C. The gas flow rate is 156.0 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.08 hour'l.

Analysis by gas chromatography indicates that the condensate contains
12.40% by weight of tetrahydrofuran
1.19% by weight of n-butanol
12.19% by weight of 1,4-butanediol
66.84% by weight of gamma-butyrolactone
This corresponds to a conversion of 47.6% of gamma-butyrolactone with a selectivity of 53.2% in favor of tetrahydrofuran, 41.8% in favor of 1,4butanediol and 5.0% in favor of n-butanol.

EXAMPLE 23.
The process of Example 8 is repeated using gamma-butyrolactone at a feed rate of 16.0 ml / hour. The absolute pressure in the reactor is 15.5 kg / cm2 (1518 kPa) and the inlet temperature is 2150C. The gas flow rate is 450 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.07 hour'l.

Analysis by gas chromatography indicates that the condensate contains
0.02% by weight of tetrahydrofuran
0.03% by weight of n-butanol
9.17% by weight of 1,5-butanediol
90.59% by weight of gamma-butyrolactone
This corresponds to a 9.4% conversion of gamma-butyrolactone with a selectivity of 97.4% in favor of 1,4-butanediol.

EXAMPLE 24.
The process of Example 8 is repeated using gamma-butyrolactone at a feed rate of 15.4 ml / hour. The absolute pressure in the reactor is 28.5 kg / cm2 (2794 kPa) and the inlet temperature is 2170C. The gas flow rate is 450 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.03 hour'l.

Analysis by gas chromatography indicates that the condensate contains
0.04% by weight of tetrahydrofuran
0.04% by weight of n-butanol
15.79% by weight of 1,4-butanediol
83.96% by weight of gamma-butyrolactone.

 This corresponds to a conversion of 16.1% of qamma-butyrolactone with a selectivity of 98.4% in favor of 1,4-butanediol.

EXAMPLE 25.
The process of Example 8 is repeated using t-butyl formate at a feed rate of 64.1 ml / hour. The absolute pressure in the reactor is 14.4 kg / cm2 (1414 kPa) and the inlet temperature is 1700C. The gas flow rate is 155.4 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 4.27 hour'l.

Analysis by gas chromatography indicates that the condensate contains
21.49% by weight of methanol
2.36% by weight of methyl formate
64.50% by weight of t-butanol
0.98% by weight of t-butyl formate
This corresponds to a 99% conversion of t-butyl formate. An accurate measurement of selectivity is not performed. Iso-butene is also detected as a product and is probably formed by dehydration of t-butanol.

EXAMPLE 26.
The process of Example 8 is repeated using phenyl acetate at a feed rate of 17.1 ml / hour. The absolute pressure in the reactor is 29.0 kg / cm2 (2850 kPa) and the inlet temperature is 2220C. The gas flow rate is 156.0 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 1.14 hour'l.

Analysis by gas chromatography indicates that the condensate contains
5.968 by weight of ethanol
6.17% by weight of ethyl acetate
24.69% by weight of phenol
61.44% by weight of phenyl acetate
This corresponds to a conversion of 40.9% of phenyl acetate with a selectivity of approximately 100% in favor of phenol, of 64.9% in favor of ethanol and of 35.1% in favor ethyl acetate.

EXAMPLE 27.
The process of Example 8 is repeated using methyl formate at a feed rate of 60.0 ml / hour. The absolute pressure in the reactor is 8.6 kg / cm2 (842 kPa) and the inlet temperature is 1940C. The gas flow rate is 540 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 4.0 hour'l.

Analysis by gas chromatography indicates that the condensate contains
99.49% by weight of methanol
0.22% by weight of methyl formate
This corresponds to a 99.7% conversion of methyl formate with a selectivity of 99.0% in favor of methanol.

EXAMPLE 28.
The process of Example 8 is repeated using methyl formate at a feed rate of 180 ml / hour. The absolute pressure in the reactor is 8.4 kg / cm2 (828 kPa) and the inlet temperature is 2000C. The gas flow rate is 540 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 12.0 hour'l.

Analysis by gas chromatography indicates that the condensate contains
76.73% by weight of methanol
23.10% by weight of methyl formate
This corresponds to a conversion of 76.9% of the methyl formate with a selectivity of 99.2% in favor of methanol.

EXAMPLE 29.
The process of Example 8 is repeated using a mixture comprising 75 mol% of methyl glycolate and 25 mol% of methanol at a feed rate of 10.0 ml / hour. The absolute pressure in the reactor is 28.1 kg / cm2 (2760 kPa) and the inlet temperature is 2100C. The gas flow rate is 155.4 liters / hour (measurement under atmospheric pressure). The liquid hourly space velocity is 0.67 hour'l.

 Analysis by gas chromatography indicates that the condensate contains a mixture of methanol, methyl glycolate and ethylene glycol.

 The calculations indicate a 13.7% conversion of methyl glycolate with a selectivity of about 98.0% in favor of ethyleneglycol.

EXAMPLE 30.
By applying a process analogous to that of Example 8, but with a volume of catalyst of 50 ml, the hydrogenolysis of ethyl acetate is studied on a crushed catalyst comprising a reduced mixture of 71.5% of CuO and 18.5% of ZnO. With a liquid feed rate of 21.7 ml / hour, corresponding to a space velocity of 0.43 / hour, and a feed mixture containing 5 mole% ethyl acetate in hydrogen, observes that under an absolute pressure of 11.6 kg / cm 2 (1138 kPa) at a temperature of 150 ° C., the conversion is 65.1% with a substantially quantitative formation of ethanol. Under the same pressure and under the same flow conditions 2000C, the conversion observed is 90.6%, also with a substantially quantitative production of ethanol.

EXAMPLE 31.
Example 30 is repeated using as catalyst a reduced mixture of 44.3% CuO, 46.3% ZnO and 9.4% A1203 to observe at 1500C a conversion of 48.9% and at 2000C a conversion of 84.2%, in each case with a substantially quantitative formation of ethanol.

Claims (77)

 1.- Process for carrying out the hydrogenolysis of a carboxylic acid ester, according to which a mixture containing the ester and hydrogen is brought into contact with a hydrogenolysis catalyst at an elevated temperature, characterized in that a vapor phase mixture comprising the ester and hydrogen is contacted with a catalyst comprising a reduced mixture of copper oxide and zinc oxide at a temperature in the range of about 750C to about 3000C under absolute pressure from the range of about 0.1 kg / cm2 (about 9.8 kPa) up to about 100 kg / cm2 (about 9813 kPa).  2.- Method according to claim 1, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2. (about 9.8 kPa) at about 50 kg / cm2 (about 4906 kPa).  3.- A method according to claim 1 or 2, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 25 kg / cm2 (about 2453 kPa).  4.- Method according to any one of claims 1 to 3, characterized in that the temperature is in the range of about 1800C to about 2400C.  5.- Process according to any one of Claims 1 to 4, characterized in that the carboxylic acid ester is chosen from the esters of the general formulas R (COOR '), and  (R "COO) pR" 'where n and p each represent an integer of 1 approximately 5 and R, R', R "and R" 'each represent an optionally substituted saturated or unsaturated cyclic or acyclic hydrocarbon radical, one or several carbon atoms can be replaced by heteroatoms chosen from nitrogen, oxygen and phosphorus atoms.  6.- Method according to claim 5, characterized in that each of the radicals R, R1, Rw and R "'contains 1 to about 12 carbon atoms.  7.- Method according to any one of claims 1 6, characterized in that the ester of carboxylic acid is an ester of formic acid and methanol is a product of hydrogenolysis.  8.- A method according to claim 7, characterized in that the carboxylic acid ester is chosen from methyl formate, isopropyl formate and t-butyl formate.  9.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of acetic acid and ethanol is a product of hydrogenolysis.  10.- Method according to claim 9, characterized in that the carboxylic acid ester is chosen from methyl acetate, ethyl acetate, 5-butyl acetate, t- acetate butyl, phenyl acetate, cyclohexyl acetate and benzyl acetate.  11.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of butyric acid and n-butanol is a product of hydrogenolysis.  12.- Method according to claim 11, characterized in that the carboxylic acid ester is n-butyl butyrate.  13.- Method according to any one of claims 1 6, characterized in that the carboxylic acid ester is an ester of oxalic acid and ethylene glycol is a product of hydrogenolysis.  14.- Method according to claim 13, characterized in that the carboxylic acid ester is di-ntbutyl oxalate.  15.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of a selected acid entte maleic acid, fumaric acid, acetylenedicarboxylic acid and succinic acid and hydrogenolysis gives 1,4-butanediol and / or tetrahydrofuran.  16.- Method according to claim 15, characterized in that the carboxylic acid ester is diethyl succinate or diethyl maleate.  17.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of phenylacetic acid and 2-phenylethanol is a product of hydrogenolysis.  18.- Method according to claim 17, characterized in that the carboxylic acid ester is ethyl phenylacetate.  19.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of lactic acid and 1,2-propanediol is a product of hydrogenolysis.  20.- Method according to claim 19, characterized in that the carboxylic acid ester is ethyl lactate.  21.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of adipic acid and 1,6-hexanediol is a product of hydrogenolysis.  22.- Method according to claim 21, characterized in that the carboxylic acid ester is dimethyl adipate.  23.- Method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is a lactone and a diol is a product of hydrogenolysis.  24.- Method according to claim 23, characterized in that the carboxylic acid ester is gamma-butyrolactone and 1,4-butanediol is a product of hydrogenolysis. .  25.- A method according to any one of claims 1 to 6, characterized in that the carboxylic acid ester is an ester of glycolic acid and ethylene glycol is a product of hydrogenolysis.  26.- Process according to claim 25, characterized in that the carboxylic acid ester is methyl glycolate.  27.- Process according to any one of Claims 1 to 26, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 10 a about 70% by weight of CuO and about 90 to about 30% by weight of ZnO.  28.- Process according to claim 27, characterized in that the mixture comprises approximately 20 to approximately 408 by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  29.- Process according to any one of Claims 1 to 26, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and about 15 to about 35% by weight of ZnO.  30.- Process for the production of ethylene glycol, according to which the hydrogenolysis of an ester of oxalic acid is carried out by bringing a mixture containing the ester and hydrogen into contact with a catalyst d hydrogenation at an elevated temperature, characterized in that a vapor phase mixture comprising the ester and hydrogen is contacted with a catalyst comprising a reduced mixture of copper oxide and zinc oxide has a interval temperature from about 750C to about 3000C under absolute pressure from the interval from about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa) and the resulting ethylene glycol is collected.  31.- A method according to claim 30, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 50 kg / cm2 (about 4906 kPa).  32.- The method of claim 30 or 31, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa).  33.- A method according to any one of claims 30 to 32, characterized in that the temperature is in the range of about 180 OC to about 2400C.  34.- Process according to any one of Claims 30 to 33, characterized in that the carboxylic acid ester is di-n-butyl oxalate.  35.- Process according to any one of Claims 30 to 34, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 30% by weight of ZnO.  36.- Process according to claim 35, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  37.- Process according to any one of Claims 30 to 34, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and about 15 to about 35% by weight of ZnO.  38.- A method of producing methanol, characterized in that a mixture in the vapor phase containing an ester of formic acid and of hydro-engineering is brought into contact with a catalyst comprising a reduced mixture of copper oxide and zinc oxide has a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa) and the resulting methanol is collected.  39.- The method of claim 38, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 50 kg / cm2 (about 4906 kPa).  40.- The method of claim 38 or 39, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3425 kPa).  41.- A method according to any one of claims 38 to 40, characterized in that the temperature is in the range of about 130 OC to about 2200C.  42.- Process according to any one of Claims 38 to 41, characterized in that the ester of formic acid is chosen from methyl formate, isopropyl formate and t-butyl formate.  43.- Process according to any one of Claims 38 to 42, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 30% by weight of ZnO.  44.- Method according to claim 43, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  45.- Process according to any one of Claims 38 to 42, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and about 15 to about 35% by weight of ZnO.  46.- Process for the production of & hanol, characterized in that a mixture in vapor phase containing an ester of acetic acid and hydrogen is contacted with a catalyst comprising a reduced mixture of oxide of copper and zinc oxide at a temperature of 11 range from about 750C to about 3009C under absolute pressure in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa), and the resulting ethanol is collected.  47.- The method of claim 46, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 50 kg / cm2 (about 4906 kPa).  48.- Method according to claim 46 or 47, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa).  49.- A method according to any one of claims 46 to 48, characterized in that the temperature is in the range of about 1800C to about 2400C.  50.- A method according to any one of claims 46 to 49, characterized in that the acetic acid ester is chosen from methyl acetate, ethyl acetate, s-butyl acetate and t-butyl acetate.  51.- Process according to any one of Claims 46 to 50, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide resulting from a mixture comprising, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 309 by weight of ZnO.  52.- Process according to claim 51, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  53.- Process according to any one of Claims 46 to 50, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and approximately 15 to approximately 35% by weight of ZnO.  54.- Process for the production of 1,4-butanediol and / or tetrahydrofuran, characterized in that one puts a mixture in vapor phase containing an ester of an acid chosen between maleic acid, fumaric acid, l acetylenedicarboxylic acid and succinic acid and hydrogen in contact with a catalyst comprising a reduced mixture of copper oxide and zinc oxide at a temperature in the range of about 750C to about 3000C under pressure absolute range from about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa) and the resulting 1,4butanediol and / or tetrahydrofuran are collected.  55.- The method of claim 54, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about -50 kg / cm2 (about 4906 kPa).  56.- The method of claim 54 or 55, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa).  57.- A method according to any one of claims 54 to 56, characterized in that the temperature is in the range of about 1800C to about 2400C.  58.- Process according to any one of Claims 54 to 57, characterized in that the ester is diethyl maleate.  59.- Process according to any one of Claims 54 to 58, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a comprepant mixture, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 30% by weight of ZnO.  60.- Method according to claim 59, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  61.- Process according to any one of Claims 54 to 58, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and about 15 to about 35% by weight of ZnO.  62.- Process for the production of ethylene glycol, characterized in that a vapor phase mixture containing an ester of glycolic acid and hydrogen is contacted with a catalyst comprises a reduced mixture of copper oxide and zinc oxide at a temperature in the range of about 750C to about 3000C under absolute pressure in the range of about 0.1 kg / cm (about 9.8 kPa) to about 100 kg / cm2 (about 9813 kPa), and the resulting ethylene glycol is collected.  63.- A method according to claim 62, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 50 kg / cm2 (about 4906 kPa).  64.- A method according to claim 62 or 63, characterized in that the absolute pressure is in the range from about 5 kg / cm2 (about 491 kPa) to about 35 kg / cm2 (about 3435 kPa).  65.- A method according to any one of claims 62 to 64, characterized in that the temperature is in the range of about 180 OC to about 2400C.  66.- Process according to any one of Claims 62 to 65, characterized in that the ester of glycolic acid is methyl glycolate.  67.- Process according to any one of Claims 62 to 66, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 30% by weight of ZnO.  68.- Method according to claim 67, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  69.- Process according to any one of Claims 62 to 66, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide obtained from a mixture comprising, before reduction, approximately 65 to approximately 85% by weight of CuO and approximately 15 to approximately 35% by weight of ZnO.  70.- Process for the production of 1,4-butanediol, characterized in that a vapor phase mixture containing butyrolactone and hydrogen is brought into contact with a catalyst comprising a reduced mixture of copper oxide and, zinc oxide at a temperature in the range of about 750C to about 3000C under an absolute pressure in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 100 kg / cm2 ( about 9813 kPa), and the resulting 1,4-butanediol is collected.  71.- A method according to claim 70, characterized in that the absolute pressure is in the range of about 0.1 kg / cm2 (about 9.8 kPa) to about 50 kg / cm2 (about 4906 kPa).  72.- The method of claim 70 or 71, characterized in that the absolute pressure is in the range of about 5 kg / cm2 (about 491 kPa) to about 45 kg / cm2 (about 4416 kPa).  73.- A method according to any one of claims 70 to 72, characterized in that the temperature is in the range of about 1800C to about 2400C.  74.- Process according to any one of Claims 70 to 73, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide resulting from a mixture comprising, before reduction, approximately 10 to approximately 70% by weight of CuO and approximately 90 to approximately 30% by weight of ZnO.  75.- Process according to claim 74, characterized in that the mixture comprises approximately 20 to approximately 40% by weight of CuO and approximately 60 to approximately 80% by weight of ZnO.  76.- Process according to any one of Claims 70 to 73, characterized in that the catalyst comprises a reduced mixture of copper oxide and zinc oxide resulting from a mixture comprising, before reduction, in approximately 65 a about 85% by weight of CuO and about 15 to about 35% by weight of ZnO.  77.- Product obtained by a process according to any one of claims 1 to 76.