CA1159435A

CA1159435A - Catalyst for the synthesis of alcohol mixtures containing methanol and higher alcohols

Info

Publication number: CA1159435A
Application number: CA000370852A
Authority: CA
Inventors: Carl E. Hofstadt; Karl Kochloefl; Ortwin Bock
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-02-14
Filing date: 1981-02-13
Publication date: 1983-12-27
Also published as: ES499117A0; FI810460L; NO810102L; ZA81981B; AU6729981A; ES8201038A1; JPH0450059B2; JPS577256A; EP0034338B1; EP0034338A2; DK63381A; ATE2051T1; DE3160017D1; EP0034338A3; DE3005551A1

Abstract

ABSTRACT OF THE DISCLOSURE
A process for the synthesis of an alcohol mixture, including methanol and higher alcohols of fuel quality involves passing a synthesis gas mixture of carbon oxides and hydrogen at a temperature of about 250-400°C and a pressure in the range of from about 80-150 bar over a special catalyst. The catalyst consists of the oxides of copper and zinc in intimate association with each other and a promotional amount of a compound selected from the group consisting of chromium, cerium, lanthanum, manganese, thorium and alkali metals. The catalyst can be made by coprecipitation of two or more of the constituents from a solution of soluble salts to produce an insoluble precipitate, followed by calcination of the insoluble salts to the oxides at temperatures in the range of 350 to 450°C. Alternately, the catalytically active oxides can be obtained by the thermal decomposition of soluble salts from ammine complexed to produce intimately associated oxides. The catalytically active oxides are tableted and can be further impregnated in one or more steps by one or more of the promoting metal oxides. The alcohols produced by this process can be used for fuel or can be mixed with gasoline. Due to the higher alcohols the gasoline and alcohol mixture does not undergo phase separation in the presence of small amounts of water. It is also possible to separate the various alcohols by fractionationand use them as starting material for chemical intermediates.

Description

This invention relates to catalysts and their use in the synthesis of alcohol mixcures containing methanol and hlgher a]cohols.
The synthesis of aliphatic alcohols from synthesis gases or, respectively, from carbon monoxide and hydrogen is known. Depending on the type of catalyst and on the reaction conditions used, these processes are referred to a Synol, Oxyl, and Isobutyl Oil Synthesis.
In the Synol synthesis alkalized iron-melt catalysts have mainly been used, wilich are obtained by modification of catalysts originally developed for the Fischer-Tropsch synthesis. The process conditions used were temperatures of 190-200 C., pressures of 18-25 bar, and space velocities of 100 - 200 liters per hour and liter of catalyst, at a H2/CO ratio of l in the fresh gas (DE-PS 933,388). The liquid reaction products contain about 42 wt.% aliphatic alcohols having a boiling point of 40 - 420C., the balance being other oxygen compounds, such as esters, aldehydes, detones and carboxylic acids, as well as hydrocarbons.
The Oxyl synthesis (DE-PS 902 851, DE-PS 897 698 and 923 127) was carried out at temperatures of 180 - 220 C., pressures oE 10 - 30 bar, space velocities of 100 - 300 liters synthesis gas per hour and liter of catalyst, the H2/CO ratio in the fresh gas being 1.2 to 2:1. Iron precipitation catalysts promoted with cerium or vanadium were used. In addition to abo~t 55 wt.%
aliphatic alcohol, the liquid reaction products contained other oxygen-containing compounds as well as hydrocarbons. Mainly C2 to C18 alcohols were formed, the percentage decreasing with increasing number of carbons.
In addition, modified iron catalysts with potassium, chromium, manganese and barium as activators were used, which led to an increased percentage of oxygen-containing compounds (DE-PS 937 706, 959 911 and 967 944).
These two syntheses having the disadvantage that the selectivity of the formation of aliphatic alcohols is rather low, and separation from the other ' re~ction products constitutes a complicated and expensive process.
The Iso~utv:l 0;1 syntllesis was carrled out pre~erably with alkali-promotecl zinc oxidc ancl chromium oxide catalysts at temperatures of 400 - 450 C.
and pressures of ~50 - 350 bar. Besldcs methanol (about 50 wt.%), isobutanol predominated in the reaction products (about ll - 14 wt.%), the balance being hlgher aliphatic a]cohols, other oxygen-containing compounds and water.
About 1950, the Synol, Oxyl, and Isobutyl Oil syntheses were replaced by more economical methods for the production of alcohols through the newly developed Oxo synthesis and, respectively, the hydration of olefins. Later iron-, copper-, boron- and potassium-containing catalysts were developed (United States Patents 124 908, 243 606 and 386 899), which were used for the synthesis of aliphatic alcohols from CO and H2 (~2/CO ratio lO) at temperatures of 160 - 225C., pressures of 100 - 300 bar and space velocities of 2000 liters synthesis gas per hour and liter of catalyst. At a conversion of 14 mol.% the content of oxygen-containing compounds was about 60 - 90 wt.7" the percentage of primary aliphatic alcohols rising up to 80% depending on the type of catalystused and the reaction conditions applied.
Although in this synthesis the yield of aliphatic alcohols is high, the process has disadvantages similar to the ones already described. Oxygen-containing compounds are formed having a boiling point range up to 450C., inwhich C2 to C18 alcohols are represented.
As the production of aliphatic alcohols via the Oxo synthesis or the hydration of olefins depends directly on petroleum as the raw material and in view of the worsening raw material situation in recent years, new ways are being sought which are intended to help alleviate the dependence of the petro-chemical industry on petroleum impor~s.
The present invention makes available catalysts which permit the synthesis of alcohol mixtures containing methanol and higher alcohols from synthesls gas or from carbon monoxide and hydrogen, the composition of the product alcohols belng llmited mainly to Cl to C4 alcohols, and the percentage of the indlvidual alcohols being controllable by the selection of the catalyst composition and of the reac~lon conditions. In addition, by means of these catalysts the carbon monoxide conversion can take place under relatively mild reaction conditions (temperatures to 400C. and pressures to 150 bar). It has been found that copper- and zinc-containing catalysts and also optionally containing aluminum, which previously were used only for low-pressure methanol synthesis, are suitable as starting catalysts for the preparation of catalysts according to the present invention.
Thus the invention provides a catalyst for the synthesis of an alcohol mixture comprising methanol and higher alcohols which comprises a ma~or portlon by weight of the oxides of copper and zinc in intimate associa-tlon with each other; a promotional amount of a promoting compound of potassium and optionally of a compound selected from the group consisting of chromium, cerium, lanthanum, manganese, and thorium, or mixtures thereof.
The oxides of copper and zinc may be derived for example through (a) coprecipitation of insoluble salts from an aqueous solution of the soluble salts of chromium and zinc; filtration of the insoluble salts; and calcination of the insoluble salts to convert the salts to their oxides. In an alternative method, the oxides of copper and zinc may be derived from (b~ the formation of an ammine complex containing ions of copper and zinc, decomposition of the ammine complex to form heat decomposable salts of copper and zinc; and con-version of the heat decomposable salts of copper and zinc to their oxides.
A thermal stabilizing metal oxide is optionally included in intimate association with the oxides of copper and zinc as, for example, aluminum oxide which may be incorporated by for instance coprecipitation of an insoluble salt thereof from the aqueous solution containing the soluble salts of chromium and zinc as well as of the metal in the first of the afore-mentioned methods of preparation of the oxides or by suspension of a hydrated metal oxide gel in~o the ammine complex formed in the second of the afore-mentioned methods followed by decomposition of the ammine complex onto the gel and calcination.
The promoter compounds are of potassium and of the group of chromium, cerlum, lanthanum, manganese, thorium and other alkali metals or mixtures thereof, and may be added at any production stage, for example by coprecipitation with the oxides or impregnation of the oxides with solutions of the promoter compounds followed by calcination, or impregnation after calcination with further calcination following.
Calcination is suitable carried out at a temperature of 350-450 C.
in the aforementioned methods.
For method (a) the alksli metal compounds when used need not be added separately. Frequently the alkali cations of an alkaline medium used for the coprecipitation, contained in the precipitate, are sufficient.
Compounds of potassium are essential to the efficency of this catalyst. Other alkali metal compounds such as rubidium or cerium may be added.
The precipitates or preproducts obtained according to both process variations can be compacted to shapes, e.g. pellets, tablets and extrusions, before impregnatlon with the promoter compounds or alkali metal compounds or alternati~vely thereafter, i.e. immediately before the calcining, with the optional addition of lubricants, such as graphite. For example, cylindrical tablets of a diameter and a length of 3-5 mm can be prepared.
The composition of the starting catalysts may vary within wide limits. A preferred embodiment of the invention is characterized in that the starting catalyst contains about 18 to 45 wt.%, preferably about 25-to 40 wt.%
copper oxide; about 24 to 50 wt.%, preferably about 30 to 45 wt.% zinc oxide;

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about S to 25 wt.%, preferably about 10 to 18 wt.% aluminum oxide, and about 0.03 to 3~4 wt.%, preferably about 1.7 to 2.5 wt.% potassium (calculated as K20), copper and zinc being present in an atomlc ratio of about 0.4 to 1.9.
The promoter compounds are usually present in total quantities of about 3 - 18 wt,% (calculated as oxides). The oxides may be present in various valences.
In a preferred embodiment~ the catalysts according to the invention can be obtained either (a) a precipitate is obtained from a solution of water-soluble salts, in particular the nitrates, of the principal components and the promoter elements, by addition of alkali metal carbonate, in particular potassium carbonate, at about 50 to 80 C., preferably at about 60 to 70 C., this precipitate being separated, washed and dried; or (b) the oxide mixture obtained by thermal decomposition of a copper-zinc-amminocarbonate solution in the presence of suspended aluminum oxide is impregnated vith salts~ preferably nitrates, of the promoter elements; and the product obtained according to (a) or (b) is calcined at about 350 to 450C., preferably at about 380 to 400 C.
In variant (a) as water-soluble salts of the principal components and of the promoter elements, besides the nitrates, other salts for example the chlorides and sulfates are suitable. In these cases, however, the washing of the precipitates must be done more thoroughly. Also the acetates are well suited, as acetate residues can be totally removed during calcination. The precipitation is usually carried out to a pH value of 6 - 8, preferably 6.8 - 7,2. The precipitate can be separated from the aqueous medium in the usual manner, e.g. by filtering. The washing can be effected on the filter or by slurrying the precipitate with deionized water.
According to a modification of variant (b), the oxide mixture can be obtained by mechanical mixing of the individual oxides of the principal components Also, similar to variant (a), the oxides of the principal _ .

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components can be precipitated ~ointly, whereupon the product oxide mixture is impregnated with the salts of the promoter elements.
~ e potasslum compound, can also be applied by a re-impregnation of the startlng catalysts already impregnated with promoter compounds and optionally precalcined. The catalysts thus impregnated are sub~ected to a re-calcination~ Thereafter the potassium content (calculated as K20) is preferably 0.03 - 3.4 wt.%, in particular about 1.7 - 2.5 wt.%.
As potassium compounds in all impregnations preferably potassium hydroxide, potassium carbonate, potassium hydrogen carbonate, potassium acetate, potassium chromate or dichromate or respectively mixtures thereof are used. The preferred compound is potassium carbonate. The use of potassium chromate or dichromate has the advantage that the promoter element chromium and the potassium can both be introduced in the form of a single compound.
The re-lmpregnation is usually followed by a re-calcination at about 350 - 450 C., preferably at about 380 - 400 C.
The catalyst ls normally activated by subjecting it to a reducing after-treatment. This ls preferably carrled out by first reducing lt using an inert gas such as nitrogen containing a small amount of hydrogen. Normally the nitrogen contains initially about 2.0 vol.% hydrogen. Then the hydrogen proportion is gradually increased, until finally the reduction is carried out with pure hydrogen. The reduction takes place generally at atmospheric pressure, and simultaneously wlth the increase in the proportion of hydrogen in the reducing gas, the temperature is gradually increased from about 145, preferably from 170, to 350C. Activation at a space velocity of about 1000 to 2000 liters reduction gas per hour and liter of catalyst is customary.
Under these conditions the reduction generally takes 16 - 18 hours.
The present invention also includes the use of the aforementioned catalysts in the synthesis of alcohol mixtures containing methanol and higher alcollols. rhuS thc inv~nt:ion provides a process ~or the synthesis of an alcohol mixture comprising meLIIa~ol alld higher alcolloLs which comprise.s the steps of:
passing a synthesis gas mix~:ure oE carbon oxides and hydrogen at a temperature in the range of about 250 to 400C. and at a pressure in the range of from about 80 to lS0 bar over a catalyst comprising a major portion hy weight of the oxides of copper and zlnc in intimate association with each other and a promotional amount of a promoting compound selected from the group consisting of chromium, cerium, lanthanum, manganese, thorium and an alkali metal.
Preferably the synthesis is carried out at about 350C. and at a pressure of about 100 bar. In a preferred embodiment the space-temperature velocity is 1000 to 10000, most preferably about 3000 liters per hour and liter of catalyst, with a process gas which contains about 25 to 30 vol.%, preferably about 27 vol.% C0; about 0 to 8 vol.% N2; about 0 to 5 vol.% C02;
about 0 to 5 vol.% CH4; balance H2.
The reaction products are cooled to about 10 - 15 C. to condense the liquid products, whereupon the components of the gaseous and liquid products are measured and analyzed separately by gas chromatographically.
It was found that when using catalysts which contained only copper and zinc or respectively copper, zinc and aluminum, only 1 - 2 or respectively 1 - 4 wt.% higher alcohols were obtained as liquid reaction products besides 90 - 94 wt.% methanol. By the introduction of 0.03 - 3.4 wt.% potassium into the copper-, zinc- and aluminum-containing catalysts, the percentage of higher alcohols rose to about 8 - 15 wt.%, while the yield of liquid reaction products decreased on the whole. Further it was noted that the intial activity of such catalysts having a copper-zinc atomic ratio of 2 - 3 : 1 clearly decreased aftera running time of 200 hours. The preferred catalysts of the invention having a copper-zinc atomic ratio of 0.4 - 1.9 had longer lives.
Doping with chromium as chromium (III) oxide in an amount of 2 -10 wt.~ led not only Lo an increascd proportion of lligher aliphatic alcohols in Lhe liquid reaction products (20 - 30 wt.%), but also to a further improvement in catalyst liFe. In the C2 to C5 alcohol fraction, propanols and butanols predominated) in particular propanol-l.
The effects of cerium and lanthanum as prollloters were similar to those of chromium. Both elements led to higher y:ields of liquid reaction products, with preferential formation of isobutanol.
The comblned promotion with chromium and thorium (5 - 10% Cr2O3, 5 - 10% ThO2) resulted not only in higher yields of liquid products, but also in larger quantities of propanols and butanols, in particular isobutanol.
The action of chromium and manganese in combination (3 - 5% Cr203, 5 - 10% MnO) resulted in highly preferential formation of ethanol and propanols, in particular ethanol.
The results achieved with the catalysts of the invention show that by controlled promotion (chromium-manganese or chromium-thorium) an alcohol mixture can be obtained which contains, i~ addition to methanol, higher aliphatic alcohols, either preferably ethanol and propanol-l or isobutanol (2-methyl-propanol-l) and propanol-l.
It is advantageous moveover that with the use of these catalysts mainly Cl to C6 alcohols are formed and the quantity of undesired hydrocarbons is less than 5%.
An alcohol mixture consisting of methanol and higher aliphatic alcohols, in particular propanols and butanols, can be used as fuel alone or blended with gasoline for the operation of Otto engines. If mixed with gasoline, no phase separation will occur due to the presence of the higher alcohols if accidentally a small amount of water~gets into the gasoline.
Moreover, the alcohol mixture obtained with the aid of the catalysts of the invention constitutes a raw material source for the chemical industry.

Afte{ separation of thF~ methanol by distillation and further fractionation of the higher aliphatic a~cohols, additional fractions can be obtained, and it is possible to use the C2 and C3 alcohols for ~he production of ethylene and propylene and the C4 a:Lcohols for the produccion of solvents and plasticizers.
If processing of the higher aliphatic alcohols is For the production of olefins, it is advisable to use chromiu~ and manganese-doped catalysts particularly.
The invention is explained in a non-limiting manner by the following examples.
Example 1 In 9000 ml of a copper amminocarbonate solution containing 4.11 g Cu/100 ml, 8.8 g NH3/100 ml and 7.4 g CO2/100 ml, were dissolved 355 g zinc oxide with agitation, adding 177 g A1203. With continued agitation and replace-ment of evaporated water, the suspension was thermally decomposed by boiling until a sample gave a colorless filtrate. The precipitate was filtered and the resulting filter cake was calcined in a thin layer at 400C. for 4 hours. The product obtained was mixed with 2% of its weight of natural graphite and compacted to cylindrical tablets of 3 mm diameter and 3 mm in length.
150 g of the product tablets were immersed at room temperature for 20 minutes in an aqueous solution of 96.5 g K2CO3 in 200 ml water and then dried for 2 hours at 120C. and calcined for 3 hours at 400C. Table I shows the chemical composition and the BET surface of the catalyst designated 0.
In a tubular reactor heated with a liquid medium (tube diameter 18 mm, tube length 1000 mm) 30 ml of catalyst 0 were activated with a gas consisting of 1.2 vol.% H2, balance N2, for 40 hours at 145 - 450 C. The temperature rise between 145 - 250C. was about 2 C./hour; after reaching 250 C., the catalyst was treated with pure hydrogen for 5 hours, and during this time the temperature was raised to 350C. Then synthesis gas having a composition of _ g _ 29.5 vol.

C2 1.5 "
C~14 1.4 "

N2 5.0 "
H2 balance was supplied to the reactor, a pressure of 100 bar and a space velocity of 2600 litersof gas per hour and liter of catalyst being adjusted. The results of this test and the composition of the reaction products are summarized in Tables II
and III.
Example 2 The thermal decomposition of a copper amminocarbonate solution and the filtering and calcining were carried out as described in Example l. The product obtained was admixed with a solution of l90 g Cr(N03)3.9H20 in 200 ml deionized water and then calcined for 3 hours at 400C. The oxides were then mixed with 2% of their weight of natural graphite and compacted to cylindrical tablets of 3 mm diameter of 3 mm length.
150 g of these tablets were then immersed in K2C03 solution, dried and calcined as described in Example l.
The chemical composition and the BET surface of the catalyst designated 1 are shown in Table I. The activation of catalyst 1 and the reaction with synthesis gas were carried out as in Example l. The results of this test and the composition of the reaction products are shown in Tables II and III.
Example 3 The thermal decomposition of a copper amminocarbonate solution and the filtration and calcining were carried out as described in Example l. The product was processed as described in Example 2; but instead of chromium(III)-nitrate solution an aqueous solution of 97.4 g cerium(IlI)-nitrate hexahydrate in 200 ml water was added. 150 g of the product tablets were immersed in K2C03 solution, dried ancl c~l.c.ined as described in Example l.
rhe chemiccll compositioll and the BIT surface of tllis catalyst designated

2 are given in Table :t. The activatioll o~ catalyst 2 with hydrogen and the reaction with syntll~is gas were carried out as in Example 1. The results oE this test and the composition of the reaction products are shown in Tables Il and III.
Example 4 The thermal decomposition of a copper amminocarbonate solution and the filtering and calcining were carried out as described in Example 1. The product obtained was processed as described in Example 2; however, instead of chromium(III)-nitrate solution, an aqueous solution of 97.8 g lanthanum nitrate hexahydrate was added. 150 g of the tablets thus obtained were immersedin K2CO3 solution, dried, and calcined, as described in Example 1.
The chemical composition and the BET surface of this catalyst designated

3 are shown in Table I. The activation of catalyst 3 with hydrogen and the reaction with synthesis gas were carried out as in Example 1. The results of this test and the composition of the reaction products are shown in Tables II and III.
Example 5 The thermal decomposition of a copper amminocarbonate solution and the filtering and calcining were carried out as described in Example 1. The product obtained was processed as described in Example 1.
150 g of the tablets thus obtained were immersed for 20 minutes at room temperature in an aqueous solution of 209.5 g K2Cr2O7 in 200 ml water and then dried for 2 hours at 120C. and calcined for 3 hours at 400C. The chemical composition and the BET su~fact of this catalyst designated 4 are shown in Table I.
The activation of catalyst 4 with hydrogen and the reaction with synthesis gas were carried out according to Example 1. The results of this test and the composition of the reaction products are shown in Tables II and III.
_ample 6 600 g K2CO3 were dissolved in 2 liters of deionized water and heated to 60 - 80 C. 285.2 g Cu(NO3)2.3H20, 188.2 g Zn(NO3)2, 131-6 g Cr(N03)3.9H2o, 52.3 ~ Th(NO3)4.4H20 and 276 g Al(N03)3.9H2O were dissolved in 2 liters deionized water and slowly added into the K2CO3 solution with stirring; the temperature was maintained at 60 - 80C. After mixing with the nitrate solution, the pH was adjusted to 6.8 - 7.0 by addition of a small quantity of aqueous K2C03 solution, whereupon stirring was continued for another 30 minutes. Then the precipitate was filtered, and the filter cake was washed until nitrate-free by repeated slurrying with 2 liters of deionized water each time (ring analysis). The washed filter cake was dried for 15 hours at 120C. and calcined for 3 hours at 400 C. The calcined product was mixed with 2% of its weight of natural graphite and compacted to cylindrical tablets 3 mm in diameter and 3 mm long. Onto 150 g of the tablets thus obtained, a solution of 8.4 g K2C03 dissolved in 30 ml H2O, was sprayed;
this was followed by drying at 120 C. for 2 hours and calcining at 400C.

for 3 hours.
The chemical composition and the BET surface of the catalyst marked 5 are given in Table I.
The activation of catalyst 5 with hydrogen and the reaction with synthesis gas were carried out as in Example 1. The results of this test and the composition of the reaction products are shown in Tables II and III.
Example 7 560 g K2C03 were dissolved in 2 liters deionized water and precipitated and processed with a solution of 285.2 g Cu(NO3)2.3H2O, 217.6 g Zn(N03)2, ~L3L~
3)2 2 ~ 65-8 ~ Cr(N()3)3.9ll20 and 276 g ~l(No ) 9H O in 2 liters deioni~ed ~ater, as dcscribcd in Example 6.
Onto 150 g of t:he product tablets wns sprayed a solution of 8.4 g K2C03 dissolved in 30 ml water; this was followed by drying for 2 hours at 120C. and calcining for 3 hours at 400 ('.
The chemical composition and the 13ET surface of this catalyst designated 6 are SilOWIl in Table 1.
The activation of catalyst 6 with hydrogen and the reaction with synthesis gas were carried out as in Example l. The results of this test and the composition of the reaction products are shown in Tables Il and III.

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Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for the synthesis of an alcohol mixture comprising methanol and higher alcohols which comprises the steps of:
A. passing a synthesis gas mixture of carbon oxides and hydrogen at a temperature in the range of about 250°C to 400 C and at a pressure in the range of from about 80 to 150 bar over a catalyst comprising:
B. a major portion by weight of the oxides of copper and zinc in intimate association with each other,

1. said oxides of copper and zinc being present in an atomic ratio of between 0.4:1 and 1.9:1;
C. a minor proportion by weight of a thermal stabilizing metal oxide in intimate association with the oxides of copper and zinc;
D. a promotional amount of one or more compounds selected from the group consisting of chromium, cerium, lanthanum, manganese and thorium; and E. a promoting compound of potassium in a weight concentration of from 0.03-3.4%.

2. A process, as defined in Claim 1, in which the oxides of copper and zinc are derived through:
A. coprecipitation of insoluble salts from an aqueous solution of insoluble salts; and B. calcination of said insoluble salts to convert said salts to their oxides.

3. A process, as defined in Claim 1, in which the oxides of copper and zinc are derived by the decomposition of an ammine complex containing copper and zinc to heat decomposable salts of copper and zinc, followed by conversion of said salts to their oxides.

4. A process, as defined in Claim 1, in which said catalyst contains additionally aluminum oxide as the thermal stabilizing oxide.

5. A process, as defined in Claim 4, in which the copper oxide is present in a concentration of about 18 to 45 wt.%, zinc oxide is present in a concentration of about 24 to 50 wt.%, and said aluminum oxide is present in a concentration of about 5 to 25 wt.%.

6. A process, according to Claim 1, in which the total promoter compounds are present in quantities of about 1 to 25 wt.%, calculated as the oxide.

7. A process, as defined in Claim 2, in which a thermal stabilizing metal oxide is incorporated into the catalyst by coprecipitation of an insoluble salt from an aqueous solution containing a soluble salt of said thermal stabilizing metal oxide.

8. A process, as defined in Claim 3, in which the thermal stabilizing metal oxide is a hydrated aluminum oxide gel and is incorporated into said catalyst by suspension of said gel in said ammine complex and in which the decomposition of said ammine complex is onto said gel.

9. A process, as defined in Claim 1, in which the oxides of copper, zinc and the thermal stabilizing metal have been derived by calcination of heat decomposable salts, and in which:

A. the calcination temperature was in the range of 350°C to 450°C;
B. the oxides were thereafter formed into shaped catalysts; and C. said shaped catalysts were dipped into a solution of a soluble promoting compound and thereafter were again calcined at a temperature of 350°C to 450°C.

10. A process, as defined in Claim 9, in which the impregnated and calcined shaped catalysts were reimpregnated with a soluble salt of potassium and were thereafter calcined at a temperature in the range of from 350°C to 450°C.

11. A process, as defined in Claim 1, in which the synthesis gas is passed over the catalyst at a space velocity of about 1,000 to 10,000 volumes per hour of catalyst and in which the process gas contains about 20 to 30 volume percent of carbon monoxide, 0 to 20 percent inert gases and 80 to 50 percent hydrogen.

12. A process, as defined in Claim 1, for the synthesis of methanol and higher alcohols:
A. the improvement of increasing the concentration of propanols and butanols and particularly the concentration of propanol-1 in the C2 to C5 fraction which comprises:
B. passing the said synthesis gas mixture over a catalyst comprising the oxides of copper and zinc as defined in Claim 1 and in which the promoting compound constitutes the oxides of chromium.

13. A process, as defined in Claim 1, for the synthesis of methanol and higher alcohols:
A. the improvement of increasing the concentration of ethanol in the C2 to C5 fraction which comprises:

B. passing said synthesis gas over a catalyst comprising the oxides of copper and zinc as defined in Claim 1 and in which the promoting compounds comprise the oxides of chromium and manganese.

14. A catalyst for the synthesis of an alcohol mixture comprising methanol and higher alcohols which comprises:
A. a major portion by weight of the oxides of copper and zinc in intimate association with each other, 1. said oxides of copper and zinc being present in an atomic ratio of between 0.4:1 and 1.9:1;
B. a minor proportion by weight of a thermal stabilizing metal oxide in intimate association which the oxides of copper and zinc;
C. a promotional amount of one or more compounds selected from the group consisting of chromium, cerium, lanthanum, manganese and thorium; and D. a promoting compound of potassium in a weight concentration of from 0.03-3.4%.

15. A catalyst, as defined in Claim 14, in which the oxides of copper and zinc are derived through:
A. coprecipitation of insoluble salts from an aqueous solution of the insoluble salts of chromium and zinc;
B. filtration of the insoluble salts;
C. calcination of said insoluble salts at a temperature in the range of from 350°C to 450°C to convert said salts to their oxides.

16. A catalyst, as defined in Claim 14 in which the oxides of copper and zinc are derived by the formation of an ammine complex containing ions of copper and zinc, followed by:

A. decomposition of said ammine complex to form heat decomposable salts of copper and zinc;
B. calcination of said heat decomposable salts of copper and zinc to their oxides at a temperature in the range of from about 350°C to 450°C.

17. A catalyst as defined in Claim 14 in which said thermal stabilizing metal oxide is aluminum oxide, which is present in a weight concentration of from about 5-25%.

18. A catalyst, as defined in Claim 14 in which the thermal stabilizing metal oxide is incorporated into the catalyst by coprecipitation of an insoluble salt from an aqueous solution containing a soluble salt of said thermal stabilizing metal oxide, mixed with soluble salts of copper and zinc.

19. A catalyst, as defined in Claim 14 in which said thermal stabilizing metal oxide is a hydrated aluminum oxide gel, and which is incorporated into said catalyst by suspension of said gel in said ammine complex, followed by decomposition of said ammine complex onto said gel.

20. A catalyst, as defined in Claim 14 in which:
A. the oxides of copper and zinc are formed into shaped catalysts;
B. said shaped catalysts are thereafter calcined; and C. said calcined catalysts are thereafter dipped in an aqueous solution of a potassium salt, and thereafter calcined at a temperature of 350°C to 450°C.

21. A catalyst, as defined in Claim 14 in which the impregnated and calcined shaped catalyst are reimpregnated with a soluble salt of potassium and the catalysts are thereafter calcined at a temperature in the range of from 350°C to 450°C.

22. A catalyst, as defined in Claim 14 in which:
A. the oxides of copper and zinc are formed into shaped catalysts and calcined;
B. said shaped catalysts are dipped into an aqueous solution of a salt of one of the promoting metals;
C. said dipped catalysts are thereafter dried and calcined;
D. said impregnated and calcined shaped catalysts are reimpregnated with a soluble salt of potassium; and E. the catalysts are thereafter calcined at a temperature in the range of from 350°C to 450°C.

23. A catalyst as defined in claim 14, 20 or 22 wherein the total amount of promoter compounds is 1 to 25 wt.%, calculated as the oxide.