Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
m e present invention relates to the treatment of
adiponitrile wlth boron phosphate or bentonite and in
particular to a process for reducing the amount o~ basic
impurities in crude adlponitrile in which the crude
adiponitrile is treated with boron phosphate or bentoniteO
One o~ the more important uses o~ ad~ponitrile at
the present time is in the manu~acture of hexamethylene dlamineJ
This diamine may be used as a detergent, as an emulsi~ying
agent, or in particularg as an intermediate in the manufacture
o~ polymersO ~ catalytic hydrogenation reaction is usually
employed to convert adiponitrile to hexamethylene diam~ne~
There are several methods for synthesi~ing adipo~
nitrileO In particular, adiponitrile may be obtained by react- -
ing adipic acid with ammonia in the presence o~ a dehydrating
catalyst, ~or example, by the technigues disclosed ~n UOSO
Patent 23 200,734 of Arnold and Lazier which issued May 14, 1940
and in U.SO Patent 2,273,633 of M~LoA~ ~luchaire which ~ssued
February 17, 19420 Adiponitrile, especially adiponitrile
obtained ~rom adipic acid, contains impurities, some of which
boil at temperatures close to the boiling point of adiponitrileO
2-Cyanocyclopentylideneimine~ hereina~ter sometimes referred
to as CPI, is an example o~ such aM impurity, Close boillng
impurities ~requently cannot be removed e~ficiently in
industrial scale distillation columnsO Impurities in the
adiponitr~le may lead to impuritles in subsequent deriviatives,
in particular in hexamethylene dlamine, that are di~lcult to
removeO Failure to remove these latter impurities may result in
in~erior and variable product properties, especially in polymers
manufactured using such impure hexamethylene diamin2. Techniques
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~or the purif`ication o~ adiponitrile are known in the art~
For example, adiponitrile Zmay be treated with a ~olid acidic
catalyst in the presence o~ water and at a temperature of at
least 140C to remove 2--cyanocyclopZ0ntylideneimine from the
adiponitrileO The solid acidic catalysts may be silica-alumina
catalystsg crystalline aluminosilicates, boron phosphate or
titania-aluminaO Such treatment is described in Canadi~n Patent
912,036 of Bo JD Kershaw which issued October 10, 1972.
Adiponitrile, especially adlponitrile obtained from
the reaction o~ adipic acid with ammonia may also contaln
impurities in the form of cyclic amines, especially N-heterocycllc
: compoundsO Examples of such impurities are 2~methyl-4-amino-5, : -
6-trimethylene pyrimidine, hereinafter sometimes referred to
as MAP, 2-amino~3,4,5,6 bis(trimethylene) pyridine, hereinafter ~ !
sometimes referred to as ABP, and 2~cyclopentyl-4 amino-5,6-tri-
methylene pyrimidine, hereinafter sometimes referred to as VAPo
Such N-heterocyclic compounds may cause process problems in
the hydrogenation of adiponitrile to hexamethglene diamine or
in the subsequent puri~ication of the hexamethylene diamine
It has now been found that basic impurities, especially
N-heterocyclic compounds, may be removed from crude ad~ponitrile
by treating the adiponitrile with boron phosphate or bentonite
at relat~vely low temperatures.
Accordinglyg the present invention provides a process
for reducing the amount o~ basic impurities in crude adiponitrile,
~ said pro¢ess comprising the steps of contacting crude adipo-.
Z nitrile with material selected from the group consisting of
boron phosphate and bentonite, and mixtures thereof3 at a
temperature in the range 20 100Co
In a preferred embodiment o~ the process of the
pre~ent invention the adiponitrile is treated substantially in
the absence of a~moniaO
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In another embodiment the adiponitrile is treated
in the presence o~ water.
In a further embodiment the crude adiponitrile i8
adiponitrile th~t has been manu~actured ~rom adipic acid and
ammonia,
In the process of the present invention the crude
adiponitrlle is treated with a material selected ~rom the
group consisting o~ boron phosphate and bentonite, and
mixtures thereof. In the process the adiponitrile maybe
treated by contacting the adipon~trile and the makerlal in a
continuous process or in a batch process, the ~ormer being
pre~erred. Preferably the adiponitrile is passed through a
~ixed bed of the boron phosphate or bentonite.
Wh~le the adiponitrile treated by the process of
the present invention is described as l'crude adipônitrile" the
adiponitrile being treated is prefera~ly adiponitrile that has
been subjected to partial puri~ication e.g. by distillatlon.
Crude adiponitrile is treated by the process of the
present invention for the removal of basic im~urities, especially
the aforementioned N-heterocyclic compoundsO In particular,
the adiponitrile ~s adiponitrile manuf~ctured ~rom adipic acid
and ammonia. The basic impurities are removed from the
adiponitrile by retention on the boron phosphate or bentonite.
In the process o~ the present invention the adiponitrile is
pre~erably treated substantially in the absence o~ ammonia.
Ammonia may be pre~erentially absorbed on the ~oron phosphate
or bentonlte and such pre~erential absorption might result in
the desorption o~ N-heterocyclic compounds a~sorbed on the
boron p~osphate or bentonite~ The effects of preferential
,
absorption of ammonia depend at least in part on the concentra
tion of ammoni~, as will be understood by those skilled in the
artO Relatlvely high concentrations o~ ammon~a may be used in
the regeneration of ~oron pAosphate and bentoniteg as is
described hereinafter.
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Crude adiponitrile may be treated, according to
the process of the present invention, in the presence or ab~ence
of water. Pre~erably the adiponitrlle ls treated in the presence
of water In a preferred embodiment the adiponitri~e is treated
: in the presence Or both water ~nd a water-soluble acidlc
compound especially phosphoric or acetic acid, If treated ln
the presence o~ water, it is preferred~ for economic reasons
that there are not more than two parts water per one part of
adipon~trile, on a weight basis Preferably, the adlponitrile
contains 1 to 10~ by weight of waterO
The process of the present lnvention may be carried
out at temperatures in the range 20-100C. Treatment may occur
at lower temperatures at low ratesO At higher temperatures,
especially above 140C and in the presence of water, hydrolysis
of 2-cyanocyclopentylideneimine~ which ma~ be present in the
;. crude adiponitrile, may occur. Such hydrol~sis of
2-cyanocyclopentylideneimine is disclosed in the aforementioned
Canadian Patent 912,036O
: The pressure used.in the process of the present
20 inventlon is not critlcalO The pressure will depend primarily .:
on other process variables, for example, the temperature at wh~ch
the process is operatedO
After operating the process for a period of time it
may be desirable or necessary to replace and/or regenerate the
boron phosphate or bentoniteO To regenerate used boron phos-
: phate or bentonite, the boron pho3phate or bentonite may be
heated under an atmosphere of lnert gas, treated with st~am at
high temperatures or treated with a base of hlgher af~inity for
the boron phosphate or bentonite ~ollowed by treatment to remove
~he baseO For example, the boron phosphate or bentonite may be
contacted with an ammonia solution at a temperature of ~rom
ambient to about 70C, separated there~rom and heated to remove
ammoniaO
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Adiponitrile purified by the process de~cribed herein
is partlcularly useful in the manufacture of hexamethylene dlamine
uslng an lron catalyst as i8 disclosed in Canadian patent
application 234 356 o~ B.J. Kers~aw ~iled on the same date as
the present applicationv
The invention is illustrated by the ~ollowing examples:
EXAMPLE I
To 25 ml of a crude adiponltrile manufactured from
adipic acid and ammonla and containing approximately 300 ppm
MAP, 700 ppm ABP and essentially 0% water was added approx-
imately one gram of bentonite~ The mixture was ~tirred ~or 10
minutes at room temperature and then analyzed by gas chromato-
graphyO Approximately 25% of the MAP and 24~ of the ABP had
been removed ~rom the crude adiponitrlle,
EXAMPLE II
2 ml of water was added to the above mixture. The
resultant mixture was st~rred for a further 25 minutes at room
temperature and re-analyzedO Approxim~tely 61~ of the MAP and
51% of the ABP had been removed from the crude adiponitrile.
EXAMPLE III
To 25 ml of a crude adiponitrile manufactured ~rom
adipic acid and ammonia and contalning approximately 1200 ppm
o~ MAP was added 2 ml of water and approximately one gram
of bentonite. The mixture was stirred ~or 10 minutes ~t room
temperature and then analyzed by gas chromatography. Approx~
imately 54% o~ the MAP had been removed ~rom the crude adipo-
nitrile.
0~1 ml of 85% phosphoric acid was added to the abo~e
mlxture. The resu~t~nt mixture was stirred for a further 30 min-
; ~ I
utes at room temper~tureO Analysis showed that 100% o~ the
MAP had ~een removed from the crude adiponitrile.
The bentonite was separated from the treated adipo-
nitrile. me bentonite was placed in a filter and 25 ml of
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3~6 ammonium hydroxide solutlon was slowly pass0d through the
bentonite. At least 50% o~ the MAP on the bentonite p&s~ed
into the ~olution.
EXAMPLE IV
To 25 ml of a crude adiponltrile manufactured from
adipic acid ~nd ammonia and containing approximately 300 ppm
of MAP and ~pproximately 700 ppm o~ ABP was added 2 ml o~ water
and 0.074 g of boron phosphate, The mixture was stlrred ~or
25 mlnutes at room temperature and then analyzed. Approxim-
ately 37~ o~ ~he MAP and 73% o~ the ABP had been removed fromthe crude adiponitrile.
The boron phosphate used above was washed with
dilute ammonium hydroxide at room temperature, Subsequent
analysis showed that this washing almost quantitatively removed
the MAP ~rom the boron phosphate.
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