Catalyst based on raney nickel containing iron
United States Patent 3862911
A hydrogenation catalyst, particularly useful for conversion of nitriles to amines, is obtained by treating with base a Raney alloy powder containing: 23 - 43% by weight nickel 0.2 - 1.8% by weight chromium 1.5 - 5% by weight iron The remainder being aluminium.
US Patent References:
Catalysts
Scriabine et al. - March 1950 - 2502348
Process for activating raney alloys and solution useful for such process
Jung et al. - February 1966 - 3235513
METHOD OF ACTIVATING CATALYTIC ALLOYS
Taira et al. - December 1970 - 3544485
/3682709.html
Pouli et al. - August 1972 - 3682709
Catalysts
Scriabine et al. - March 1950 - 2502348
Process for activating raney alloys and solution useful for such process
Jung et al. - February 1966 - 3235513
METHOD OF ACTIVATING CATALYTIC ALLOYS
Taira et al. - December 1970 - 3544485
/3682709.html
Pouli et al. - August 1972 - 3682709
Application Number:
05/314434
Publication Date:
01/28/1975
Filing Date:
12/12/1972
View Patent Images:
Export Citation:
Assignee:
Rhone-Poulenc S.A. (Paris, FR)
Primary Class:
Other Classes:
420/550
International Classes:
B01J25/02; C07C209/48; B01J25/00; C07C209/00; B01J11/22
Field of Search:
252/470,477R,477Q,465,470 75/138
Primary Examiner:
Demers, Arthur P.
Attorney, Agent or Firm:
Stevens, Davis, Miller & Mosher
Claims:
1. A hydrogenation catalyst obtained by treating with a base a powdered Raney alloy consisting essentially of:
2. A catalyst according to claim 1, wherein the base is a solution of an alkali metal hydroxide, the concentration of which is between 10 and 30%
3. A catalyst according to claim 1, wherein the proportion of iron in the
4. A catalyst according to claim 1, wherein the Raney alloy is treated with
5. A catalyst according to claim 1, wherein the Raney alloy has a particle
6. A catalyst according to claim 1, wherein a powdered alloy, of particle size less than 50 microns, is treated with an aqueous solution containing about 30% by weight sodium hydroxide under conditions such that after washing with water and ethanol the residual alloy contains:
2. A catalyst according to claim 1, wherein the base is a solution of an alkali metal hydroxide, the concentration of which is between 10 and 30%
3. A catalyst according to claim 1, wherein the proportion of iron in the
4. A catalyst according to claim 1, wherein the Raney alloy is treated with
5. A catalyst according to claim 1, wherein the Raney alloy has a particle
6. A catalyst according to claim 1, wherein a powdered alloy, of particle size less than 50 microns, is treated with an aqueous solution containing about 30% by weight sodium hydroxide under conditions such that after washing with water and ethanol the residual alloy contains:
Description:
The present invention relates to a hydrogenation catalyst based on a Raney nickel which also contains iron and chromium. This catalyst is particularly valuable for hydrogenating unsaturated groups.
It is known that it is possible to incorporate into Raney alloys various metals which thereafter play the role of promoters for the catalyst. Thus, in French Patent Specification No. 913,997, it has been proposed to incorporate chromium in a proportion ranging from 0.5 to 3.5% relative to the nickel. The resulting catalysts, which can, in addition, contain small proportions of iron if the chromium was introduced in the form of iron/chromium alloys, retain their activity over a very much longer period of time; they can be re-cycled more times and, because of this, they make it possible to hydrogenate a larger amount of product per unit amount of catalyst.
Whether or not the Raney catalysts containing chromium contain small amounts of iron, they nevertheless possess disadvantages in certain applications. In particular, during their use in the hydrogenation of nitriles to amines, it is often observed, when all the reagents are introduced at the start, that the speed of hydrogenation is relatively slow. When the nitrile is injected into the solution of the corresponding amine in the presence of such catalysts and hydrogenated, it is also found that the termination period is long (the termination period is the time interval which separates the end of injection of the nitrile and the end of absorption of hydrogen). Furthermore, it has also been shown that Raney catalysts containing chromium did not prevent the formation of a relatively large amount of by-products.
The present invention provides new hydrogenation catalysts based on Raney nickel, which substantially avoid the above mentioned disadvantages.
The catalysts of the present invention are those prepared by treating an alloy powder with an alkali, the composition of the alloy being, by weight, limits:
NICKEL 22 TO 43%
CHROMIUM 0.2 TO 1.8%
IRON 1.5 TO 5%.
The residue being aluminium. The alloy will also contain conventional impurities and other incidental ingredients. To obtain the more active catalysts, it is preferred to use alloys containing, by weight
30 - 38% OF NICKEL, 0.2 TO 1.8% OF CHROMIUM AND 1.5 TO 4% OF IRON, AND PARTICULARLY 2 TO 4% IRON, THE REMAINDER BEING ALUMINIUM.
Alloys in the powder form can be obtained by crushing and grinding alloy ingots, the latter being prepared by the usual metallurgical techniques, for example, by adding nickel, iron and chromium to molten aluminium, preferably heated to between 900° and 1,000°C. Iron and chromium can be introduced either in the form of pure metals or in the form of their alloys with aluminium. It is possible to use nickel which is obtained either by conventional smelting of nickel from garnierit (nickel magnesium silicate dihydrate) or from nickel-bearing pyrites, or by decomposition of nickel carbonyl.
The addition of nickel to molten aluminium raises the temperature of the molten alloy to a great extent, and the temperature can exceed 1,500°C. After cooling, the alloy is ground and passed through a sieve before being treated with the alkali.
The sieved alloy is in the form of a powder, the particle size of which is normally less than 500 microns. In order to have a catalyst which is as active as possible, a powder of particle size less than 50 microns is preferably used.
The process conditions for treating the powder can be very diverse, it being possible to carry out this treatment using an inorganic or organic base. An alkaline base, and preferably an alkali metal hydroxide e.g. sodium hydroxide in the form of an aqueous solution of concentration 5 - 50%, and preferably 10 - 30% w/v, is generally employed. The treatment is usually carried out at a temperature of 40° - 110°C. It is possible to add the alloy powder to the basic solution, or to pour the basic solution onto the alloy or to pour an aqueous suspension of the alloy into the base. When the alloy and base have been mixed, the reaction is continued until hydrogen ceases to be evolved, this occurs usually within 3 hours. When the evolution of gas has ceased, the resulting catalyst is washed with water, by a continuous or discontinuous method, which optionally may take place under a slight pressure of hydrogen. When the washing with water is finished, the product may optionally be washed with an alcoholic solution, the alcohol usually being ethanol. The resulting catalyst is pyrophoric, and it is necessary to store it out of contact with air, for example under water, or a liquid alcohol or hydrocarbon.
The finished catalysts after treatment with base will normally contain nickel, aluminium, chromium and iron in the following proportions: ratio by weight chromium nickel : 0.5 to 8.5% ratio by weight iron nickel : 3.5 to 23% ratio by weight aluminium nickel : 5 to 16%.
The catalysts in which the ratios Cr/Ni, Fe/Ni and Al/Ni are in the following proportions:
Cr Ni : 0.8 to 6% Fe Ni : 4 to 13.5% Al Ni : 8 to 12%
possess the greatest activity.
The catalysts of the invention can be used for hydrogenating various hydrogenisable organic substances, but they are particularly recommended for hydrogenating mono-functional or poly-functional unsaturated groups of the olefinic type or of the nitrile type. It was found, particularly with regard to the reaction for hydrogenating dinitriles, that the speed of hydrogenation was more rapid and that the termination periods were decreased. Furthermore, the formation of by-products takes place to a lesser extent and the catalysts can be re-cycled more times because of their better resistance to fatigue. These advantages are particularly marked for the hydrogenation of adiponitrile, wherein, in addition, a diamine is obtained which contains fewer unsaturated impurities than those prepared using previous catalysts. Because of this, the polyamide fibres derived from these diamines are less fragile and have less tendency to turn yellow.
The hydrogenation can be carried out optionally in the presence of a solvent such as a lower alkanol e.g. containing up to 4 carbon atoms. It is also possible to activate the Raney catalysts using small proportions of an alkaline agent introduced, for example, in the form of an aqueous solution.
The examples which follow illustrate the invention.
EXAMPLE 1
A. Preparation of the catalyst
448g of aluminium are melted in a graphite crucible and 31g of iron powder, 7g of chromium powder and 214g of compressed nickel (a trade name for billets of cylindrical shape, diameter 30 mm, height 15 mm; these billets are broken up into pieces before use) are added to the aluminium which is heated to 950°C. The mixture is stirred with a graphite rod and it is found that the temperature rises to 1,500°C. The cooled alloy is removed from the mould, cut up into shavings, finely ground and passed through a sieve and 180 g of a powder, the particle size of which is less than 50 microns, are collected. The additional amount to make up 700g represents the portion which is greater than 50 microns and the grinding losses.
This powder has the following composition:
nickel : 33.5% chromium : 0.5% iron : 3% aluminium : 63%.
56g of this powder is then treated with alkali by introducing the powder in small portions into 326 cm 3 of a 30% by weight aqueous solution of sodium hydroxide. When the addition of alloy is complete, the treatment with alkali is continued for 1 hour and the mixture is transferred to a 1,000 cm 3 Erlenmeyer flask. The catalyst is washed successively, by shaking followed by decanting, with:
4 times 235 cm 3 of warm water,
5 times 235 cm 3 of water at 20°C and
twice 150 cm 3 of 95° GL strength ethanol.
The resulting catalyst contains 18.7g Ni, 2.1g Al, 1.7g Fe and 0.28g Cr, that is to say Al/Ni = 11.1% by weight, Fe/Ni = 9.1% by weight and Cr/Ni = 1.5% by weight.
B. Application of the catalyst in the hydrogenation of Adiponitrile
The catalyst described above is introduced into a 3.6 1 autoclave together with 107.5g of 95° GL strength ethanol.
______________________________________ hexamethylenediamine : 187 g, water : 215 cm 3 and a 30% by weight aqueous sodium hydroxide solution : 2.2 cm 3 ______________________________________
After purges with nitrogen and hydrogen, a pressure of 25 bars of hydrogen is established, the autoclave is heated to 75°C and a mixture consisting of:
adiponitrile : 1,250g 95°GL strength ethanol : 962 cm 3 distilled water : 151 cm 3 and a 30% by weight aqueous sodium hydroxide solution : 15.4 cm 3
is injected evenly over the course of 75 minutes.
During the entire injection, the temperature is kept at 75°C. When the injection has ceased, it is found that the termination period is 8 minutes.
C. For comparison purposes, a catalyst was prepared from a Raney alloy containing chromium and iron, with a small content of iron, in the following way:
28g of ferrochromium powder (ferrochromium containing 70% of chromium) and 742g of compressed nickel are added to 734g of molten aluminium which has been heated to 1,000°C. The temperature of the metal mixture rises to 1,800° - 1,900°C as a result of the exothermic nature of the reaction. After cooling, the alloy is removed from the mould, broken up, ground and passed through a sieve. A 672g fraction is obtained, the particle size of which is less than 50 microns and the composition of which is as follows:
Ni : 48.5% Cr : 1% Fe : 0.6% Al : 49.9%.
The additional amount to make up 1,504g consists of the portion greater than 50 microns and grinding losses.
The alkali treatment is carried out by adding 38.6g of alloy of particle size between 0 and 50 microns to 306 cm 3 of an aqueous solution containing 27.7% by weight sodium hydroxide. After the end of the addition of the alloy, the treatment with alkali is continued for 55 minutes and then, after cooling, the catalyst is washed, by shaking followed by decanting, with:
4 times 240 cm 3 of warm water,
4 times 240 cm 3 of water at 20° and
twice 95 cm 3 of 95° GL strength ethanol.
The resulting catalyst contains 18.7g Ni, 0.38g Cr, 0.23g Fe and 1.9g Al, that is to say Cr/Ni = 2%, Fe/Ni = 1.2% and Al/Ni = 10% by weight.
The same experiment of hydrogenating adiponitrile as that described above (same amount of nickel, namely 18.7g) is carried out. It is found that the termination period is 13 minutes.
EXAMPLE 2
Catalysts were prepared according to the method described in Example 1 part A from alloys, the composition of which is given in the following table. The hydrogenation of adiponitrile to hexamethylenediamine is carried out in the same way as that described in Example 1 part B. The termination periods are also given in the table. It should be noted that they are less than those obtained with a catalyst which does not contain iron.
______________________________________ No. of Experiment 3 4 5 ______________________________________ Alloy Ni % by weight 22.4 43 29.4 Cr do. 0.5 0.8 0.3 Fe do. 2.45 2.9 2.7 Al do. 74.65 53.3 67.6 ______________________________________ Catalyst Al/Ni % by Weight 8.4 10.4 9.4 Cr/Ni do. 2.2 1.9 1 Fe/Ni do. 10.9 6.7 9.2 Weight of Ni g 18.7 18.7 18.7 ______________________________________ Hydrogenation termination Period in minutes 8 12 7 ______________________________________
EXAMPLE 3
An alloy is prepared by the general procedure described in Example 1 part A adding 20 g of ferrochromium powder (ferrochromium containing 70% of chromium), 14g of iron powder and 234g of compressed nickel to 430 g of molten aluminium which has been heated to 950°C. 370g of alloy powder of particle size less than 50 microns and the composition of which is as follows:
nickel : 33.2% chromium : 1% iron : 2.7% aluminium : 63.1%
are obtained.
Treatment with alkali and washing is carried out as described in Example 2 by introducing 226 g. of the alloy powder in small amounts into 1,300 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. The resulting catalyst contains: 75 g. Ni and 2.24 g. Cr, giving Cr/Ni = 3% by weight, 6 g. Fe giving Fe/Ni = 8% by weight and 7.2 g. Al giving Al/Ni = 9.7%.
This catalyst is used to carry out a series of hydrogenations by the method described in Example 1 part B. Each series of hydrogenations is carried out on the same bed of catalyst, without re-introducing a new amount of catalyst between each operation.
These experiments were carried out for the purpose of comparing the resistance to fatigue and the selectivity of a catalyst according to the invention and those of a known catalyst, of low iron content, the preparation and the composition of which has been described in Example 1 part C. These properties are measured by the termination periods and by the proportions of residue. The results obtained are listed in the following Table:
______________________________________ Composition of the Composition of the alloy according to alloy used for the invention comparison purposes ______________________________________ nickel 33.2% nickel 48.5% chromium 1% chromium 1% iron 2.7% iron 0.6% aluminium 63.1% aluminium 49.9% ______________________________________ hydrogen- termination propor- termination propor- ation period in tion of period in tion of minutes residue minutes residue % % ______________________________________ 1st < 1 min. -- < 1 min. -- 2nd 1 1.8 1 2.1 3rd 1 1.8 2 2.3 4th 2 2 6 3.5 5th 2.5 2.5 11 3.6 6th 4 2.3 17 5.2 7th 5 3.4 22 5.9 8th 7.5 3.2 9th 9.5 3.7 10th 11.5 4 ______________________________________
It is found that the catalyst produced from the alloy according to the invention has a better resistance to fatigue (10 consecutive hydrogenations with the same catalyst) as well as a better selectivity.
EXAMPLE 4
A. 196 g. of an aluminium/iron alloy (containing 9.9% of iron), 93 g. of an aluminium/chromium alloy (containing 3.5% of chromium) and 93 g. of aluminium are melted in a graphite crucible and 222 g. of compressed nickel are added to the mixture which has been heated to 900°C. 386 g. of alloy powder, of particle size less than 50 microns and the composition of which is as follows:
nickel : 37.1% by weight chromium : 0.45% by weight iron : 2.6% by weight aluminium : 60.8% by weight
are obtained by treatment analogous to that described in Example 1 part A.
101 g. of this powder are then treated with alkali by pouring the powder into a solution prepared by mixing 326 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide and 380 cm 3 of distilled water. The treatment and the washing are analogous to those described in Examples 1 part A and 2. The resulting catalyst contains 37.5 g. of nickel, the proportions of the various metals being as follows: Al/Ni : 13.8%; Fe/Ni : 7% and Cr/Ni : 1.2%.
The catalyst, 127 cm 3 of water, 149 g. of hexamethylenediamine and 5.6 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide are introduced into a 3.6 1. autoclave. After purges with nitrogen and hydrogen, a pressure of 25 bars of hydrogen is established, the autoclave is heated to 75°C. and 1,250 g. of adiponitrile are injected evenly over the course of 75 minutes, whilst keeping the temperature constant. When the injection has ceased, the termination period is 6 minutes. The proportion of residue is 4.6%.
B. For comparison purposes, a catalyst was used which contains a small content of iron and was prepared from the alloy powder described in Example 1, the composition of which is as follows:
nickel : 48.5% chromium : 1% iron : 0.6% aluminium : 49.9%.
The treatment with alkali is carried out by adding 77.2 g. of this alloy of particle size less than 50 microns to 712 cm 3 of an aqueous solution containing 27.7% by weight sodium hydroxide. A catalyst consisting of 37.5 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 10.5%; Cr/Ni : 2% and Fe/Ni : 1.2%, is obtained after the end of treatment, washing and decanting, as described in the previous Examples.
This catalyst is used to hydrogenate adiponitrile by the procedure described in part A of this Example. The termination period is 9.5 minutes. The proportion of residue is 5.6%.
EXAMPLE 5
A. Preparation of the catalyst
462 g. of aluminium are melted in a graphite crucible and 21 g. of iron powder, 3.5 g. of chromium powder and 214 g. of compressed nickel are added to the aluminium which has been heated to 900°C. The mixture is stirred with a graphite rod and it is found that the temperature rises to 1,500°C. The cooled alloy is removed from the mould, cut up into shavings, finely ground and the fraction passing through a 50 microns sieve collected. The additional amount to make up 700 g. represents the portion greater than 50 microns and the grinding losses.
This powder has the following composition:
nickel : 32.5% by weight chromium : 0.23% by weight iron : 2.8% by weight aluminium : 64.5% by weight.
8.3 g. of this powder are then treated with alkali, the powder being introduced in small portions into 48.5 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. Using washing and decanting treatments analogous to those described in the previous Examples, a catalyst is obtained which contains, in 35 g. of ethanol, 2.7 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 9.1% by weight, Fe/Ni : 8.6% and Cr/Ni : 0.7%.
B. Application of the catalyst in the hydrogenation of 1-amino-2-cyano-1-cyclopentene
The catalyst is introduced into a 500 cm 3 autoclave together with 95 g. of 95° GL strength ethanol, 3.7 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide and 54 g. of aminocyanocyclopentene. The autoclave is then placed in a double jacket for circulating water kept at 93°C.; the whole is mounted on a mechanical shaker. After purges with nitrogen and hydrogen, the pressure of hydrogen is kept at between 80 and 90 bars. Zero time is counted from the instant when shaking is started. The end of absorption of hydrogen marks the end of the hydrogenation.
The duration of hydrogenation is 140 minutes.
The hydrogenated product is then distilled and 2-amino-methyl-cyclopentylamine is obtained with a yield of 54%; the proportion of residue is 38%.
By way of comparison, the same experiment of hydrogenating aminocyanocyclopentene is carried out by means of a catalyst of low iron content and prepared as described in Example 4 part B (the amount of catalyst employed corresponds to 2.7 g. of nickel). It is found that the duration of hydrogenation is 370 minutes; the yield of 2-aminomethyl-cyclopentylamine is 47% and the proportion of residue is 47%.
EXAMPLE 6
A. 154 g. of an aluminium/iron alloy (containing 9.9% by weight of iron), 170 g. of an aluminium/chromium alloy (containing 3.5% by weight of chromium) and 71 g. of aluminium are melted in a graphite crucible, and 199 g. of compressed nickel are added to the mixture which has been heated to 900°C. The mixture is stirred with a graphite rod and the alloy converted to a powder as described in Example 1 part A. 370 g. of a powder of particle size less than 50 microns are obtained the composition of which is as follows:
Ni : 33.7% by weight Cr : 0.9% by weight Fe : 2% by weight Al : 63.4% by weight.
12.6 g. of this powder is then treated with alkali by introducing the powder in small portions into 73 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. A catalyst which contains, in 20 g. of ethanol, 4.25 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 11.9%; Cr/Ni : 2.75% and Fe/Ni : 5.95%, is obtained after the washing and decantation treatment described in the previous Examples.
B. Application of the catalyst in the hydrogenation of isophthalodinitrile
The hydrogenation is carried out in the same apparatus as that described in Example 5 and in the same way. 85 g. of isophthalodinitrile, the catalyst, 150 g. of 95° GL strength ethanol and 1.6 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide are introduced into the autoclave. The temperature of the double jacket is kept at 85°C. and the pressure of hydrogen at 40 bars. The duration of hydrogenation is 22 minutes. The yield of 1,3-bis-(aminomethyl)-benzene is 75% and the proportion of residue is 17% by weight.
When the catalyst containing chromium and a small amount of iron as described in Example 4 part B is used, the duration of hydrogenation is 44 minutes, the yield of the diamine is 62% and the proportion of residue is 30%.
It is known that it is possible to incorporate into Raney alloys various metals which thereafter play the role of promoters for the catalyst. Thus, in French Patent Specification No. 913,997, it has been proposed to incorporate chromium in a proportion ranging from 0.5 to 3.5% relative to the nickel. The resulting catalysts, which can, in addition, contain small proportions of iron if the chromium was introduced in the form of iron/chromium alloys, retain their activity over a very much longer period of time; they can be re-cycled more times and, because of this, they make it possible to hydrogenate a larger amount of product per unit amount of catalyst.
Whether or not the Raney catalysts containing chromium contain small amounts of iron, they nevertheless possess disadvantages in certain applications. In particular, during their use in the hydrogenation of nitriles to amines, it is often observed, when all the reagents are introduced at the start, that the speed of hydrogenation is relatively slow. When the nitrile is injected into the solution of the corresponding amine in the presence of such catalysts and hydrogenated, it is also found that the termination period is long (the termination period is the time interval which separates the end of injection of the nitrile and the end of absorption of hydrogen). Furthermore, it has also been shown that Raney catalysts containing chromium did not prevent the formation of a relatively large amount of by-products.
The present invention provides new hydrogenation catalysts based on Raney nickel, which substantially avoid the above mentioned disadvantages.
The catalysts of the present invention are those prepared by treating an alloy powder with an alkali, the composition of the alloy being, by weight, limits:
NICKEL 22 TO 43%
CHROMIUM 0.2 TO 1.8%
IRON 1.5 TO 5%.
The residue being aluminium. The alloy will also contain conventional impurities and other incidental ingredients. To obtain the more active catalysts, it is preferred to use alloys containing, by weight
30 - 38% OF NICKEL, 0.2 TO 1.8% OF CHROMIUM AND 1.5 TO 4% OF IRON, AND PARTICULARLY 2 TO 4% IRON, THE REMAINDER BEING ALUMINIUM.
Alloys in the powder form can be obtained by crushing and grinding alloy ingots, the latter being prepared by the usual metallurgical techniques, for example, by adding nickel, iron and chromium to molten aluminium, preferably heated to between 900° and 1,000°C. Iron and chromium can be introduced either in the form of pure metals or in the form of their alloys with aluminium. It is possible to use nickel which is obtained either by conventional smelting of nickel from garnierit (nickel magnesium silicate dihydrate) or from nickel-bearing pyrites, or by decomposition of nickel carbonyl.
The addition of nickel to molten aluminium raises the temperature of the molten alloy to a great extent, and the temperature can exceed 1,500°C. After cooling, the alloy is ground and passed through a sieve before being treated with the alkali.
The sieved alloy is in the form of a powder, the particle size of which is normally less than 500 microns. In order to have a catalyst which is as active as possible, a powder of particle size less than 50 microns is preferably used.
The process conditions for treating the powder can be very diverse, it being possible to carry out this treatment using an inorganic or organic base. An alkaline base, and preferably an alkali metal hydroxide e.g. sodium hydroxide in the form of an aqueous solution of concentration 5 - 50%, and preferably 10 - 30% w/v, is generally employed. The treatment is usually carried out at a temperature of 40° - 110°C. It is possible to add the alloy powder to the basic solution, or to pour the basic solution onto the alloy or to pour an aqueous suspension of the alloy into the base. When the alloy and base have been mixed, the reaction is continued until hydrogen ceases to be evolved, this occurs usually within 3 hours. When the evolution of gas has ceased, the resulting catalyst is washed with water, by a continuous or discontinuous method, which optionally may take place under a slight pressure of hydrogen. When the washing with water is finished, the product may optionally be washed with an alcoholic solution, the alcohol usually being ethanol. The resulting catalyst is pyrophoric, and it is necessary to store it out of contact with air, for example under water, or a liquid alcohol or hydrocarbon.
The finished catalysts after treatment with base will normally contain nickel, aluminium, chromium and iron in the following proportions: ratio by weight chromium nickel : 0.5 to 8.5% ratio by weight iron nickel : 3.5 to 23% ratio by weight aluminium nickel : 5 to 16%.
The catalysts in which the ratios Cr/Ni, Fe/Ni and Al/Ni are in the following proportions:
Cr Ni : 0.8 to 6% Fe Ni : 4 to 13.5% Al Ni : 8 to 12%
possess the greatest activity.
The catalysts of the invention can be used for hydrogenating various hydrogenisable organic substances, but they are particularly recommended for hydrogenating mono-functional or poly-functional unsaturated groups of the olefinic type or of the nitrile type. It was found, particularly with regard to the reaction for hydrogenating dinitriles, that the speed of hydrogenation was more rapid and that the termination periods were decreased. Furthermore, the formation of by-products takes place to a lesser extent and the catalysts can be re-cycled more times because of their better resistance to fatigue. These advantages are particularly marked for the hydrogenation of adiponitrile, wherein, in addition, a diamine is obtained which contains fewer unsaturated impurities than those prepared using previous catalysts. Because of this, the polyamide fibres derived from these diamines are less fragile and have less tendency to turn yellow.
The hydrogenation can be carried out optionally in the presence of a solvent such as a lower alkanol e.g. containing up to 4 carbon atoms. It is also possible to activate the Raney catalysts using small proportions of an alkaline agent introduced, for example, in the form of an aqueous solution.
The examples which follow illustrate the invention.
EXAMPLE 1
A. Preparation of the catalyst
448g of aluminium are melted in a graphite crucible and 31g of iron powder, 7g of chromium powder and 214g of compressed nickel (a trade name for billets of cylindrical shape, diameter 30 mm, height 15 mm; these billets are broken up into pieces before use) are added to the aluminium which is heated to 950°C. The mixture is stirred with a graphite rod and it is found that the temperature rises to 1,500°C. The cooled alloy is removed from the mould, cut up into shavings, finely ground and passed through a sieve and 180 g of a powder, the particle size of which is less than 50 microns, are collected. The additional amount to make up 700g represents the portion which is greater than 50 microns and the grinding losses.
This powder has the following composition:
nickel : 33.5% chromium : 0.5% iron : 3% aluminium : 63%.
56g of this powder is then treated with alkali by introducing the powder in small portions into 326 cm 3 of a 30% by weight aqueous solution of sodium hydroxide. When the addition of alloy is complete, the treatment with alkali is continued for 1 hour and the mixture is transferred to a 1,000 cm 3 Erlenmeyer flask. The catalyst is washed successively, by shaking followed by decanting, with:
4 times 235 cm 3 of warm water,
5 times 235 cm 3 of water at 20°C and
twice 150 cm 3 of 95° GL strength ethanol.
The resulting catalyst contains 18.7g Ni, 2.1g Al, 1.7g Fe and 0.28g Cr, that is to say Al/Ni = 11.1% by weight, Fe/Ni = 9.1% by weight and Cr/Ni = 1.5% by weight.
B. Application of the catalyst in the hydrogenation of Adiponitrile
The catalyst described above is introduced into a 3.6 1 autoclave together with 107.5g of 95° GL strength ethanol.
______________________________________ hexamethylenediamine : 187 g, water : 215 cm 3 and a 30% by weight aqueous sodium hydroxide solution : 2.2 cm 3 ______________________________________
After purges with nitrogen and hydrogen, a pressure of 25 bars of hydrogen is established, the autoclave is heated to 75°C and a mixture consisting of:
adiponitrile : 1,250g 95°GL strength ethanol : 962 cm 3 distilled water : 151 cm 3 and a 30% by weight aqueous sodium hydroxide solution : 15.4 cm 3
is injected evenly over the course of 75 minutes.
During the entire injection, the temperature is kept at 75°C. When the injection has ceased, it is found that the termination period is 8 minutes.
C. For comparison purposes, a catalyst was prepared from a Raney alloy containing chromium and iron, with a small content of iron, in the following way:
28g of ferrochromium powder (ferrochromium containing 70% of chromium) and 742g of compressed nickel are added to 734g of molten aluminium which has been heated to 1,000°C. The temperature of the metal mixture rises to 1,800° - 1,900°C as a result of the exothermic nature of the reaction. After cooling, the alloy is removed from the mould, broken up, ground and passed through a sieve. A 672g fraction is obtained, the particle size of which is less than 50 microns and the composition of which is as follows:
Ni : 48.5% Cr : 1% Fe : 0.6% Al : 49.9%.
The additional amount to make up 1,504g consists of the portion greater than 50 microns and grinding losses.
The alkali treatment is carried out by adding 38.6g of alloy of particle size between 0 and 50 microns to 306 cm 3 of an aqueous solution containing 27.7% by weight sodium hydroxide. After the end of the addition of the alloy, the treatment with alkali is continued for 55 minutes and then, after cooling, the catalyst is washed, by shaking followed by decanting, with:
4 times 240 cm 3 of warm water,
4 times 240 cm 3 of water at 20° and
twice 95 cm 3 of 95° GL strength ethanol.
The resulting catalyst contains 18.7g Ni, 0.38g Cr, 0.23g Fe and 1.9g Al, that is to say Cr/Ni = 2%, Fe/Ni = 1.2% and Al/Ni = 10% by weight.
The same experiment of hydrogenating adiponitrile as that described above (same amount of nickel, namely 18.7g) is carried out. It is found that the termination period is 13 minutes.
EXAMPLE 2
Catalysts were prepared according to the method described in Example 1 part A from alloys, the composition of which is given in the following table. The hydrogenation of adiponitrile to hexamethylenediamine is carried out in the same way as that described in Example 1 part B. The termination periods are also given in the table. It should be noted that they are less than those obtained with a catalyst which does not contain iron.
______________________________________ No. of Experiment 3 4 5 ______________________________________ Alloy Ni % by weight 22.4 43 29.4 Cr do. 0.5 0.8 0.3 Fe do. 2.45 2.9 2.7 Al do. 74.65 53.3 67.6 ______________________________________ Catalyst Al/Ni % by Weight 8.4 10.4 9.4 Cr/Ni do. 2.2 1.9 1 Fe/Ni do. 10.9 6.7 9.2 Weight of Ni g 18.7 18.7 18.7 ______________________________________ Hydrogenation termination Period in minutes 8 12 7 ______________________________________
EXAMPLE 3
An alloy is prepared by the general procedure described in Example 1 part A adding 20 g of ferrochromium powder (ferrochromium containing 70% of chromium), 14g of iron powder and 234g of compressed nickel to 430 g of molten aluminium which has been heated to 950°C. 370g of alloy powder of particle size less than 50 microns and the composition of which is as follows:
nickel : 33.2% chromium : 1% iron : 2.7% aluminium : 63.1%
are obtained.
Treatment with alkali and washing is carried out as described in Example 2 by introducing 226 g. of the alloy powder in small amounts into 1,300 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. The resulting catalyst contains: 75 g. Ni and 2.24 g. Cr, giving Cr/Ni = 3% by weight, 6 g. Fe giving Fe/Ni = 8% by weight and 7.2 g. Al giving Al/Ni = 9.7%.
This catalyst is used to carry out a series of hydrogenations by the method described in Example 1 part B. Each series of hydrogenations is carried out on the same bed of catalyst, without re-introducing a new amount of catalyst between each operation.
These experiments were carried out for the purpose of comparing the resistance to fatigue and the selectivity of a catalyst according to the invention and those of a known catalyst, of low iron content, the preparation and the composition of which has been described in Example 1 part C. These properties are measured by the termination periods and by the proportions of residue. The results obtained are listed in the following Table:
______________________________________ Composition of the Composition of the alloy according to alloy used for the invention comparison purposes ______________________________________ nickel 33.2% nickel 48.5% chromium 1% chromium 1% iron 2.7% iron 0.6% aluminium 63.1% aluminium 49.9% ______________________________________ hydrogen- termination propor- termination propor- ation period in tion of period in tion of minutes residue minutes residue % % ______________________________________ 1st < 1 min. -- < 1 min. -- 2nd 1 1.8 1 2.1 3rd 1 1.8 2 2.3 4th 2 2 6 3.5 5th 2.5 2.5 11 3.6 6th 4 2.3 17 5.2 7th 5 3.4 22 5.9 8th 7.5 3.2 9th 9.5 3.7 10th 11.5 4 ______________________________________
It is found that the catalyst produced from the alloy according to the invention has a better resistance to fatigue (10 consecutive hydrogenations with the same catalyst) as well as a better selectivity.
EXAMPLE 4
A. 196 g. of an aluminium/iron alloy (containing 9.9% of iron), 93 g. of an aluminium/chromium alloy (containing 3.5% of chromium) and 93 g. of aluminium are melted in a graphite crucible and 222 g. of compressed nickel are added to the mixture which has been heated to 900°C. 386 g. of alloy powder, of particle size less than 50 microns and the composition of which is as follows:
nickel : 37.1% by weight chromium : 0.45% by weight iron : 2.6% by weight aluminium : 60.8% by weight
are obtained by treatment analogous to that described in Example 1 part A.
101 g. of this powder are then treated with alkali by pouring the powder into a solution prepared by mixing 326 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide and 380 cm 3 of distilled water. The treatment and the washing are analogous to those described in Examples 1 part A and 2. The resulting catalyst contains 37.5 g. of nickel, the proportions of the various metals being as follows: Al/Ni : 13.8%; Fe/Ni : 7% and Cr/Ni : 1.2%.
The catalyst, 127 cm 3 of water, 149 g. of hexamethylenediamine and 5.6 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide are introduced into a 3.6 1. autoclave. After purges with nitrogen and hydrogen, a pressure of 25 bars of hydrogen is established, the autoclave is heated to 75°C. and 1,250 g. of adiponitrile are injected evenly over the course of 75 minutes, whilst keeping the temperature constant. When the injection has ceased, the termination period is 6 minutes. The proportion of residue is 4.6%.
B. For comparison purposes, a catalyst was used which contains a small content of iron and was prepared from the alloy powder described in Example 1, the composition of which is as follows:
nickel : 48.5% chromium : 1% iron : 0.6% aluminium : 49.9%.
The treatment with alkali is carried out by adding 77.2 g. of this alloy of particle size less than 50 microns to 712 cm 3 of an aqueous solution containing 27.7% by weight sodium hydroxide. A catalyst consisting of 37.5 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 10.5%; Cr/Ni : 2% and Fe/Ni : 1.2%, is obtained after the end of treatment, washing and decanting, as described in the previous Examples.
This catalyst is used to hydrogenate adiponitrile by the procedure described in part A of this Example. The termination period is 9.5 minutes. The proportion of residue is 5.6%.
EXAMPLE 5
A. Preparation of the catalyst
462 g. of aluminium are melted in a graphite crucible and 21 g. of iron powder, 3.5 g. of chromium powder and 214 g. of compressed nickel are added to the aluminium which has been heated to 900°C. The mixture is stirred with a graphite rod and it is found that the temperature rises to 1,500°C. The cooled alloy is removed from the mould, cut up into shavings, finely ground and the fraction passing through a 50 microns sieve collected. The additional amount to make up 700 g. represents the portion greater than 50 microns and the grinding losses.
This powder has the following composition:
nickel : 32.5% by weight chromium : 0.23% by weight iron : 2.8% by weight aluminium : 64.5% by weight.
8.3 g. of this powder are then treated with alkali, the powder being introduced in small portions into 48.5 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. Using washing and decanting treatments analogous to those described in the previous Examples, a catalyst is obtained which contains, in 35 g. of ethanol, 2.7 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 9.1% by weight, Fe/Ni : 8.6% and Cr/Ni : 0.7%.
B. Application of the catalyst in the hydrogenation of 1-amino-2-cyano-1-cyclopentene
The catalyst is introduced into a 500 cm 3 autoclave together with 95 g. of 95° GL strength ethanol, 3.7 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide and 54 g. of aminocyanocyclopentene. The autoclave is then placed in a double jacket for circulating water kept at 93°C.; the whole is mounted on a mechanical shaker. After purges with nitrogen and hydrogen, the pressure of hydrogen is kept at between 80 and 90 bars. Zero time is counted from the instant when shaking is started. The end of absorption of hydrogen marks the end of the hydrogenation.
The duration of hydrogenation is 140 minutes.
The hydrogenated product is then distilled and 2-amino-methyl-cyclopentylamine is obtained with a yield of 54%; the proportion of residue is 38%.
By way of comparison, the same experiment of hydrogenating aminocyanocyclopentene is carried out by means of a catalyst of low iron content and prepared as described in Example 4 part B (the amount of catalyst employed corresponds to 2.7 g. of nickel). It is found that the duration of hydrogenation is 370 minutes; the yield of 2-aminomethyl-cyclopentylamine is 47% and the proportion of residue is 47%.
EXAMPLE 6
A. 154 g. of an aluminium/iron alloy (containing 9.9% by weight of iron), 170 g. of an aluminium/chromium alloy (containing 3.5% by weight of chromium) and 71 g. of aluminium are melted in a graphite crucible, and 199 g. of compressed nickel are added to the mixture which has been heated to 900°C. The mixture is stirred with a graphite rod and the alloy converted to a powder as described in Example 1 part A. 370 g. of a powder of particle size less than 50 microns are obtained the composition of which is as follows:
Ni : 33.7% by weight Cr : 0.9% by weight Fe : 2% by weight Al : 63.4% by weight.
12.6 g. of this powder is then treated with alkali by introducing the powder in small portions into 73 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide. A catalyst which contains, in 20 g. of ethanol, 4.25 g. of nickel, aluminium, iron and chromium in the following proportions: Al/Ni : 11.9%; Cr/Ni : 2.75% and Fe/Ni : 5.95%, is obtained after the washing and decantation treatment described in the previous Examples.
B. Application of the catalyst in the hydrogenation of isophthalodinitrile
The hydrogenation is carried out in the same apparatus as that described in Example 5 and in the same way. 85 g. of isophthalodinitrile, the catalyst, 150 g. of 95° GL strength ethanol and 1.6 cm 3 of an aqueous solution containing 30% by weight sodium hydroxide are introduced into the autoclave. The temperature of the double jacket is kept at 85°C. and the pressure of hydrogen at 40 bars. The duration of hydrogenation is 22 minutes. The yield of 1,3-bis-(aminomethyl)-benzene is 75% and the proportion of residue is 17% by weight.
When the catalyst containing chromium and a small amount of iron as described in Example 4 part B is used, the duration of hydrogenation is 44 minutes, the yield of the diamine is 62% and the proportion of residue is 30%.