Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
O.Z.0050/3b9~7
In the preparation of amines by hydrogenation of
nitr;les, eg. hexamethylenediam;ne from adipon;tr;le,
cobalt-containing catalysts are particularly preferably
used because of the;r high selectivity. Such processes
are disclosed in, for example, German Patents 1,072,~72
and 1,259,899. However, the life of the cobalt catalysts
used does not meet industrial requirements~ The catalysts
used have the disadvantage that they disin~egrate during
use, with the result that their mode of action is adversely
aFfected. French Patent 1,407,414 furthermore discloses
that cobalt catalysts obtained by pressing cobalt oxide
with graphite can be used for the hydrogenation of adipo-
dinitrile to hexamethylenediamine. During use, such cata-
lysts rapidly lose their hardness and disin~egrate, withthe result that their life is very restricted~ German
Laid-Open Application DOS 2,654~028 furthermore disclos2s
molded catalyst materials ~hich conta;n meeallic cobalt,
alkali metal oxides, alkaline earth metal ox;des and
graphite. In the hydrogenation of adipodinitrile, however,
these catalysts result in the formation of increased
amounts of cyclic productsl
It is an object of the present invention to provide
molded catalys~ materials ~hich contain cobalt andtor
nickel and possess high activity and a long life~ in par-
ticular great indentation hardness, mechanical strength
and abrasion res;stance.
~ e have found that this object is achieved by a
process for the prepara~ion o~ saturated primary amines
by reacting a nitrile wi~h hydrogen at ele~ated tempera-
tures and under superatmospheric pressure in the presence
of ammonia and a catalyst containing cobalt and/or nickel
and a lubricant~ wherein the molded catalyst material used
has an indentation hardness of > 30û kptcm2 and contains
metallic cobal~ and/or nickel particles, obtained from
cobalt oxide and/or nickel oxide par~icles containing less
--2--
than 0.1~ by weight of alkali metal oxides and alkaline
earth metal oxides by reduction with hydrogen at C 500 C,
and a lubricant.
The invention also provides a process for -the
preparation of a sa-turated primary amine, which comprises
reacting a ni-trile with hydrogen at elevated temperatures
and under superatmospheric pressure in the presence of
ammonia and a molded catalyst material which has an inden-
tation hardness of ~ 300kp/cm and is obtained by
a) reducing cobalt oxide and/or nickel oxide
particles, having less than 0.1~ by weight of alkali metal
oxides and/or alkaline earth metal oxides, to metallic
cobalt and/or nickel particles by treatment wi-th hydrogen,
b) passivating the metallic cobalt and/or nickel
particles by treatment with an inert gas containing molecu-
lar oxygen.
c) pressing the passivated cobalt and/or nickel
particles with a lubricant to give mo:Ldings, and
d) activating the moldings containing passivated
cobalt and/or nickel particles and lubricant by treatment
wi-th hydrogen at from 250 to 500 C.
The novel process has the advantages tha-t the
catalysts used have a long life and still possess superior
properties even after prolonged use and, in particular,
exhibit great indentation hardness, mechanical strength
and abrasion resistance even after prolonged use. Another
advantage of the novel process is that it takes place with
high selectivity, and the amount of by-products which are
difficult to separate off from the useful products is small.
Preferably used starting materials are aliphatic,
cycloaliphatic or aromatic nitriles of not more than 20
carbon atomsO The molecule may contain one or more, eg.
Erom 1 to 4, nitrile groups. Compounds which are suitable
Eor -the hydrogenation are saturated or olefinically unsatu-
'3
. . ~
-2a-
rated nitriles. They may also possess substituents which
are inert under -the reaction conditions, eg. alkyl radicals
which have 1 to 4 carbon atoms and are bonded via ether
bridges, or aromatically bonded halogen atoms. Particularly
preEerred starting materials are alkanenitriles or alkanedi-
nitriles of 3 to 18 carbon atoms. Examples of suitable
nitriles are propionitrile, acetonitrile, acrylonitrile,
benzyl cyanide, benzonitrile, glutarodinitrile, methylgluta-
rodinitrile, adipodinitrile and but-2-ene~ -dinitrile.
The process has become particularly important
industrially for the hydrogenation of adipodinitrile to
hexamethylenediamine.
The reaction is carried out in general under
from 100 to 400, preferably from 200 to 300, bar, advanta-
geously at from 80 to 140C, preferably from 100 to 120C.
The reaction is carried out in the presenceof ammonia. It has proven useful for the volume ratio of
nitrile to ammonia to be from 1:2 to 1:20, preferably from
1:6 to 1:12. It is also possible to replace some of the
,
,~
3~
- 3 - 0.~ 0050/36947
ammonia by recycled crude hydrogenation mix~ure, ~hich
essent;ally cons;sts of the amine being prepared and
ammonia.
According to the invent;on~ the ~olded catalyst
; materials used have an indentation hardness of ~ 300 kp/cn2
and contain m~allic cobalt and nickel particles, obtained
from cobalt oxide andtor nickel ox;de part;cles by reduc-
tion with hydrogen at ~ 500C~ and a lubricant. Advan-
tageously, the metallic cobal~ and/or nickel particles
have a degree of reduction of ` 80X, in particular - 95X.
The degree of reduction is the proport;on, expressed as a
percentage, of available cobalt and/or nickel ~hich are
present in metallic form.
The content of alkali metal oxides and/or ~lkaline
earth metal oxides is less than 0.1X by ~eight.
The molded catalyst materials used furthermore
contain a lubricant, eg an inorganic substance having a
framework strurture, such as talc or graphite. The cata-
lysts advantageously contain the lubricant in an amount
of from 1 to 5% by weight, based on the total ca~alyst
material consisting of activ~ material~ containing
metallic cobalt and/or nickel particles, and lubricant~
Graphite has proven a particularly useful lubricant.
The catalyst materials according to the inven~ion have an
indentation hardness of > 300, in particular from 350 to
1,50û~ kp/cm2.
Preferably, cobalt ox;de and/or nickel oxide par-
ticles having a particle size of frsm 0.1 to 5, in par-
~icular from O~Z to 2, ~m are used. The cobalt oxide and/
or nickel ox;de Dar.icles used as starting materials can
contain further activating additiYes, such as manganese
o%ide, chromium oxide and/or copper ox;de, as ~ell 35
pyrophosphoric and/or polyphc,sphoric acid. The oxide par-
ticles preferably contain fro~ 80 to 99% by ~eight of
nicke~ and/or cobalt in the form of their oxides, and from
O.S to 10X by weight of man~anese, chromium and/or copper
in the form of their oxides, the percentages being
~.3~ ~ 3~
4 -- O.Z.nO50/369~7
calculated as metal. If the catalyst ;s to be modified
with pyrophosphoric or polyphosphoric acid, the oxide
particles constituting the starting material contain from
0.5 to 10X by weight of polyphosphoric and/or pyrophos-
phoric acid. Of course, the resulting active catalyt;cmaterial, withou~ the lubricant, has the corresponding
composition in the ready-prepared catalyst. It is assumed
that copper is present as a metal ;n the ready-prepared
catalyst, ~hereas it is not kno~n in ~hat form manganese
and/or chromium occur in the said catalyst.
The ready-prepared catalysts therefore essen-
tially consist of metallic cobalt and/or nickel parti-
cles, small amounts of cobalt oxide and/or nickel oxide
depending on the degree of reduction~ with or ~ithout
the above additives, and a lubricant.
The novel catalysts are molded, for example in
the form of spheres, tablets or extrudates.
As a rule~ the oxide particles are prepared using
aqueous solutions of cobalt salts and~or nickel salts.
~here astivating ad~itives, such as manganese, chromiu0
and/or copper~ are used comcom;tantly, aqueous solut;ons
of salts of these netals are used in addition. Examp~es
of suitable salts are nitrates, sulfates, chlorides and
salts ~ith lo~er fatty acids~ such as acetic acid. If the
cataLyst is to con~ain pyrophosphoric or polyphosphoric
acid, phosphoric acid ;s concomitantly used, this being
converted to pyrophosphoric or po(yphosphoric acid during
further processing~ The starting solutions are advan-
tageously first combined under acidic conditions~ eg. at
a pH of from 1 to 2. A mixture of the metal oxides,
hydroxides and carbonates, wi~h or ~ithout the acid con-
stituents~ is then precipitated, as a rule, ~ith aqueous
alkali metal hydroxide solution, eg. a 10-25X strength by
weight solution, or aqueous alkali metal carbonate solu~
35 tion, eg. a 5-2S% strength by weight solution. It is
also possible to run the aqueous solutions of the metal
compounds into the alkaline precipitating solution. It
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~ 5 - O.~.D05Q/36947
has proven advantageous to choose the ratio of the acidic
solution to the alkaline precip;tating agent so that the
final pH of the react;on m;xture is from 7~0 to 7.5. The
precipitated oxide, hydroxide and~or carbonate mixture is
S filtered off~ ~ashed free from foreign salts ~ich ~ater~
and dried. The mixture is then converted to the corres-
ponding oxides by heating~ temperatures OT from 250 to
500C generally being sufficient for this purpose. The
material obtained in this manner is then milled, as stated
above, for example to the suitable particle size. Ir; an
advantageous procedure, the oxide material is made into
a paste, for example ~ith ~ater~ and then extruded, and
the resulting moldings are heated aga;n at from 300 to
800C and then milled to the abovementioned particle
size. The content of alkali metal oxides and/or alkaline
earth metal oxides is less than 0.1Z by ~eight.
The particles containing cobalt oxide and/or
n;ckel oxide are reduced uith hydrogen, for example in a
flu;dized bed ;n a rotar~ tubular furnace or, preferablyr
in an agita~ed fixed bed, eg. at from 250 to 500C, in
particular from 300 to 450C~ for example in the course
of from 3 to 3b hours. Advantageously, a dry stream of
hydrogen which is free of signif;cant amounts of ~ater is
used, a relat;vely high hydrogen flow rate being ma;n~
tained. It has proven useful to use hydrogen in a 6û-fold
or greater excess. Reduction is advantageously carried
out until the degree of reduction reaches > 80%, in par
ticular ~ 95%.
The metal particles are then stabilized by passi
3û vation. This procedure comprises coating the metal par-
ticles ~ith an oxide layer by controlled oxidation in order
to eliminate the pyrophoricity due to the large free sur-
face area of the small particles. This is achieved by
treatment ~ith an inert gas containing molecular oxygen,
from 0.1 to 1~0 vol. X of the said oxygen-containing inert
gas advantageously being used for this purpose. Examples
of inert gases are nitrogen and noble gases. It has proven
~f~3~
- 6 - O.Z.0050/36947
particularly advantageous to use a nitrogen/air mixture.
The passivation is achieved by, for example, passing a
nitrogen/air mixture over the metal po~der ~hile exactly
maintaining the temperature at a value, eg. from 65 to
S 75~C, which preferably does no~ exceed 100C, in
particular 80C~ After the pass;vation, the degree of
reduction should be no lower than ~OX, preferably no lo~er
than 90%. The stabilized cobalt and/or nickel particles are
from 0.05 to Z, ;n particular from 0.2 to 1.2~ ~um in size.
The metallic cobalt and/or nickel particles passi-
vated in th;s manner are mixed with an inert lubricant, eg.
an inorganic substance having a frame~ork struc~ure, such
as talc or graphite, in particular graphite. The lubricant
is advantageously used in an amount of from 1 to 5% by
weight, based on the material containing metal particles
and the lubricant. The mixture of passivated cobalt and/or
nickel particles and lubricant is advantageously processed
to give mold-ngsy eg. pressed to tablets~ under a nitrogen
atmosphere. The indentation hardness of the moldings is
ad~antageously ~ 300 kp/cm2~
The moldings obtained in this manner are act;Y3ted
by treatment ~ith a relatively large, eg. 60-fold, excess
of hydrogen in the absence of significant amounts of
~ater, at ~ SOQC9 eg~ from 25û to 500C, in particular
=
fron 300 to 360C, under atmospher;c or superatmospheric
pressure, eg. not mcre than 15~ bar. Advantageously~ the
degree of reduction shoyld reach ~ ~5% in this procedure.
As a result of the activation~ the indentat;on hardness
of the moldings increases~ for example from 300 to bOO-
800 kp/cmZ.
The principle of the method used to produce themolded catalyst materials is ~herefore as follo~s: parti-
cles containing cobalt oxide and/or nickel oxide are first
reduced to metal particles9 these are passivated ~ith an
inert gas containing molecular oxygen in order to elimi-
nate the pyrophoricity, the passivated particles conta;-
n;ng cobalt or n;ckel are pressed ~ith a lubricant to
~ ~3 ~ ~3 7 ~ ~
~ 7 ~ O.Z.0050/36947
give moldings, and the resul~ing moldings are astivat~d
by reduc~ion ~;th hydrogen.
It has proven particularly useful if the ready-
prepared activated nolded catalyst material is again
passivated, as described above, by treatment ~ith an inert
gas conta;ning molecular oxygen, the degree of reduction
not falling belo~ 80%, and then again act;vated~ as des-
cr;bed above, by treatmen~ ~;th hydrogen at ~ 500C, pre-
ferably 300 - 360C, this procedure being carried out
one or more t;mes~ advantageously from 1 to S, ;n part;-
cular from 1 t~ 4, times. The indentation hardness in-
creases ~ith each cycle and reaches 800-1,300 kplcm2.
The molded catalyst materials used according to the
invention possess high mechanical stability, ~hich is
ach;eved by processing the moldings ~ogether with a
lubricant not at the stage of the oxides but only after
the reduction of these to cobalt and/or nickel particles
and subsequent passiv~tîon~ If moldings ~hich have been
prepared from cobalt ox;de and/or nickel oxide part;cl~s
and lubricants and then act;vated are usedD the indenta-
t;on hardness of the moldings decreases, for example from
300 kp~cm2 to ~25 kptcm2, after the degree of re-
duc~ion has reached 95X. As a result, the l;fe of such
catalysts ;s substant;ally shortened.
The hydrogenation of the nitriles can be carried
out batchwise~ but the react;on is advan~ageously effected
by a continuous method, for example by a trickle-bed pro-
cedure over a fixed-bed molded catalyst material~
The amines obtainable by the process of the inven-
tion are useful for the preparation of stabilizers. Hexa-
Methylenediamine, ~hich can be obta;ned by the process of
the invention~ is an important starting mater;al for the
preparation of nylon-6,6.
The Examples ~h;ch follow illustrate the process
accord;ng to the invention.
EXAMPLE 1
4~b80 9 of cobalt nitrate, Co(N03~2 x 6 H20, 261 9
- 8 - O.Z.0050/36947
of manganese ni~rate~ Mn(N03)2 x 6 H20, and ~7 9 of 85X
strength by weight phosphoric acid are dissolved in 10 l
of water, and th;s solut;on is run slo~ly ;nto a st;rred
solution of 1~900 9 of sodium carbonate, Na2C03~ in 10 l
of water. ~hen the addi~ion of metal salt solution is
complete, the pH of the mixture has fallen to 7Ø
After cooling, the precipitate is filtered off under suc-
tion and ~ashed with water until it is free of sodium ;ons.
The filter cake is dried and then heated at 300C untiL
the material is free of carbonate. The oxide mixture is
then made into a paste with sufficien~ ~ater to produce
a kneadable mass, ~hich is extruded. The extrudates are
then heated in a muffle furnace at 450C for 2~ hours,
and the resulting extrudates are milled to give particles
from 0.1 to 1.2 ~m in size.
600 kg of the cobalt oxide-contain;ng particles
prepared in this manner are reduced ~ith 400 m3(S.TOP~)/
h of hydrogen in an agitated fixed bed a~ 400C for
38 hours to g;Ye metallic cobalt having a degree of
reduction of 95%, based on cobalt (stoichiometric excess
of hydrogen: 64). The pyrophoric metal pigment ;s then
coated with a stabilizing oxide layer in a nitro~en/air
m;xture at 60~C, and is thus passivated~ ~he degree of
reduct;on not falling belo~ 90X.
To produce moldings having a diameter of 5 mm and
a height of 4 mm, the passivated pulverulent metal pig-
ment is mixed ~;th 2X by ~eight of graphite, and the mix-
ture ;s tabletted under a nitrogen atmosphere. The inden
tation hardness of the tablets is 300 kp/cm2.
3û In a high pressure vessel~ 350 ml of the moldings
prepared in this manner are treated with a large excess
of hydrogen at 360C and under 150 bar for 24 hours in
order to activate them. The hydrogen is circulated via
a condenser ;n order to separate off the ~ater of reduc-
tion. The resulting molded catalys~ material has a purity
molded catalyst materia~ is ~hen passivated by treatment
~ith a mixture of nitrogen and oxygen containin~ 0.5 vol. %
~ 9 - 0.2.0050/36~47
of the latter, at 60C, the degree of reduc~ion not
falling belo~ 90%. The molded catalyst material is then
again activa~ed with hydrogen at 360C and under 150 bar,
as described above. The resulting moldings have an in-
denta~ion hardness of 950 kp/cm2. After the passivation/activation cycle has been repeated a second time~ the
moldings have an indentation hardness of 1p140 kp/cm2.
When the catalyst has cooled, the reaction vessel
;s charged, by a tr;ckle~bed procedure and under a hydro-
1û gen pressure of 270 bar, ~ith a mixture of 85 l/hour ofad;podinitrile, 255 l/hour of liquid ammonia and 350 l/
hour of hydrogenation mixture, the hydrogen being circu-
lated t4ûO m3(S~T.P.)/h). The temperature of the feed
mixture is 65C a~d that at the reactor exit is 95C~ The
maximum hot spot temperature ~hich results is 100C.
Analysis of the crude hexamethylenediamine by gas chroma-
tography after the ammonia has been evaporated from the
hydrogenation mixture gives 0.02~ by ~eight of hexy~amine,
0~05% by ~eight of azacyclomethane, 0.06X by ~eight of
1~20diaminocyclohexane, 0.003% by ~eight of 2-aminomethyl-
cyclopen~ylanine and 99.8~X by we;gh~ of hexame~hylene-
diamine, as ~ell as an aminocapronitrile content of O.QOlX
by ~eight. The distillation residue~ ~hich predominantly
consists of b;shexamethylened;am;ne, amounts to 0.3% by
~eight. Th~ select;vity ~ith respect to hexamethylene-
diam;ne is calculated as 99.5%. Af~er a time-on stream
of 520 days, the activity and selectivity of the catalyst
are unchanged, w;thout any regenerat;on, and the catalyst
mater;al has an indentation hardness of 900 kp/cm2.
COMPARATIVE EXAMPLE 1
The cobalt oxide prepared as described in Example
1 is m;xed ~ith 2X of graphite, and the mi~ture is pressed
to give tablets ~diameter 5 mm, height 4 mm). The indenta-
tion hardness is brought to 300 kp/cm~, after ~hich the
tabLets are brought to a degree of reduction of ~ 95X ~ith
hydrogen at 360C. As a result of the reduction of the
cobalt oxide, the indentation hardness of the tablets
- 10 - O~Z.0050t36947
decreases sharply to ~ 25 kp/cm2. Con~act ~ith the
lateral surface of the cylinder readily c~uses the
tablets to disintegrate into disks~
In contrast to tablets produced from cobalt oxide
~hich has already been reduced to cobalt, the mechanical
stab;lity of these tablets cannot be impro~ed by repeated
passivation and reduction.
COMPARATIVE EXAMPLE 2
A high pressure vessel having a length of 2 m
and a diameter of 42 mm is charged ~oith 3 1 of a passi-
vated cobalt catalyst prepared as described in Example 1
of German Laid-Open Application DOS Z,~54~028. The cata-
lyst contains 1.5X by we;ght of calcium c,x;de and 2.7X
by ~eight of sodium salts, calculated as sodium oxide.
The catalyst is ac~ivated by heating in a stream of hydro-
gen at 330C.
After cooling, the high pressure vessel is
charged, by a tr;ckle-bed procedure and under a hydrogen
pressure of -270 bar~ ~ith 0.4 l/hour of adipodinitr;le,
1.2 l/hour of liquid ammonia and 4.5 l~hour of crude
hydrogenation m;xture, the temper3ture being kept at
140Co Analysis of the crude hexame~hylenediamine by
gas chromatography after the ammonia has been evaporated
from the hydrogenation mixture yives 99.~9X by ~eight of
25 hexamethylenediamine, 3.06% by ~eight of 1~2-diam;no-
cyclohexane and 0.12X by ~eight of 2-am;nocyclopentyl-
amine.
