Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
2000-03-20
2001-07-03
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
Reexamination Certificate
active
06255521
ABSTRACT:
The present invention relates to a process for the preparation of aliphatic alpha,omega-aminonitriles in the presence of a catalyst, and catalysts which are suitable for the hydrogenation.
DE-A 44 468 93 discloses a process for the preparation of aliphatic alpha,omega-aminonitriles by partial hydrogenation of aliphatic alpha,omega-dinitriles at elevated temperatures and superatmospheric pressure in the presence of a solvent and of a catalyst, by using a catalyst which
(a) contains a compound based on a metal selected from the group consisting of nickel, cobalt, iron, ruthenium and rhodium and
(b) contains from 0.01 to 25, preferably from 0.1 to 5, % by weight, based on (a), of a promoter based on a metal selected from the group consisting of palladium, platinum, iridium, osmium, copper, silver, gold, chromium, molybdenum, tungsten, manganese, rhenium, zinc, cadmium, lead, aluminum, tin, phosphorus, arsenic, antimony, bismuth and rare earth metals, and
(c) from 0 to 5, preferably from 0.1 to 3, % by weight, based on (a), of a compound based on an alkali metal or on an alkaline earth metal,
with the proviso that the component (a) is not based on iron or iron and one of the metals selected from the group consisting of cobalt, ruthenium and rhodium if (b) is a promoter based on a metal selected from the group consisting of titanium, magnesium, chromium and molybdenum, and with the further proviso that, if a compound based on only ruthenium or rhodium or ruthenium and rhodium or nickel and rhodium is chosen as component (a), the promoter (b) can if desired be dispensed with.
The disadvantage of this process is the formation of by-products which are very difficult to separate from the alpha,omega-aminonitriles, such as 6-aminocapronitrile or any further useful products, such as adipodinitrile and hexamethylenediamine in the case of 6-aminocapronitrile as the alpha,omega-aminonitrile.
For example, in the hydrogenation of adipodinitrile to 6-aminocapronitrile and hexamethylenediamine, inter alia 1-amino-2-cyanocyclopentene (ICCP), 2-aminomethylcyclopentylamine (AMCPA), 1,2-diaminocyclohexane (DCH) and bishexamethylenetriamine (BHMTA) are formed in varying amounts.
U.S. Pat. No. 3,696,153 discloses that AMCPA and DCH can be separated from hexamethylenediamine only with very great difficulty.
Furthermore, the time-on-stream of the catalysts in this process is not completely satisfactory.
The prior German patent application 196 36 765.4 describes a process similar to that of the present application, except that, in the process described in 196 36 765.4, the 6-aminocapronitrile (ACN) selectivity is dependent on the age (time-on-stream) of the catalysts used, unless the phosphorus in the adipodinitrile (ADN) used is separated off beforehand. However, separating off phosphorus is technically more difficult and it is desirable to bypass this step.
It is an object of the present invention to provide a process for the preparation of aliphatic alpha,omega-aminonitriles by partial hydrogenation of aliphatic alpha,omega-dinitriles in the presence of a catalyst, which process does not have the stated disadvantages and permits the preparation of alpha,omega-aminonitriles with high selectivity in a technically simple and economic manner, gives long times-on-stream with virtually unchanged conversion and still has a high alpha,omega-aminonitrile selectivity.
We have found that this object is achieved by a process for the preparation of aliphatic alpha,omega-aminonitriles by partial hydrogenation of aliphatic alpha,omega-dinitriles in the presence of a catalyst which
(a) contains iron or a compound based on iron or mixtures thereof and
(b) contains from 0.01 to 5% by weight, based on (a), of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of aluminum, silicon, zirconium, titanium and vanadium and
(c) from 0 to 0.5% by weight, based on (a), of a compound based on an alkali metal or on an alkaline earth metal, wherein the alpha,omega-dinitrile used contains 1.0 ppm by weight or more of phosphorus.
We have also found catalysts which are obtainable by the reduction and, if required, subsequent passivation of a magnetite, containing
(a) iron or a compound based on iron or mixtures thereof,
(b) from 0.01 to 5% by weight, based on (a), of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of aluminum, silicon, vanadium, titanium and zirconium, and
(c) from 0 to 0.5% by weight, based on (a), of a compound based on an alkali metal or on an alkaline earth metal,
the catalysts having a BET surface area of from 3 to 10 m
2
/g, a total pore volume of from 0.05 to 0.2 ml/g, an average pore diameter of from 0.03 to 0.1 &mgr;m and a pore volume fraction of from 50 to 70% in the range from 0.01 to 0.1 &mgr;m.
Preferred catalyst precursors are those in which the component (a) contains from 90 to 100, preferably from 92 to 99, % by weight, based on (a), of iron oxides, iron hydroxides, iron oxide hydroxides or mixtures thereof. Examples of suitable precursors of this type are iron -(III)-oxide, iron-(II,III)-oxide, iron-(II)-oxide, iron-(II)-hydroxide, iron-(III)-hydroxide and iron oxide hydroxide, such as FeOOH. It is possible to use synthetic or naturally occurring iron oxides, iron hydroxides or iron oxide hydroxides, such as magnetite, which can ideally be described by Fe
3
O
4
, brown hematite, which can be ideally be described by Fe
2 O
3
H
2
O, or red hematite, which can be ideally be described by Fe
2
O
3
.
Other preferred catalyst precursors are those in which component (b) contains from 0.01 to 5, preferably from 0.1 to 4, in particular from 0.1 to 2, % by weight of a promoter based on 2, 3, 4 or 5 elements selected from the group consisting of aluminum, zirconium, silicon, titanium and vanadium.
Further preferred catalyst precursors are those in which component (c) contains from 0 to 0.5, preferably from 0.02 to 0.2, % by weight of a compound based on an alkali metal or on an alkaline earth metal, preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium and calcium.
The novel catalysts may be unsupported or supported catalysts. Examples of suitable carrier materials are porous oxides, such as alumina, silica, aluminosilicates, lanthanum oxide, titanium dioxide, zirconium dioxide, magnesium oxide and zinc oxide, and zeolites and active carbon and mixtures thereof.
The preparation is carried out as a rule by a procedure in which precursors of component (a), if desired together with precursors of promoters components (b) and, if desired, with precursors of the trace components (c), are precipitated in the presence or absence of carrier materials (depending on which catalyst type is desired) and, if desired, the catalyst precursor thus obtained is processed to give extrudates or pellets, dried and then calcined. Supported catalysts are in general also obtainable by impregnating the carrier with a solution of the components (a), (b) and, if desired, (c), it being possible to add the individual components simultaneously or in succession, or by spraying the components (a), if desired (b) and (c) onto the carrier by methods known per se.
Suitable precursors of components (a) are as a rule readily water-soluble salts of iron, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precursors of components (b) are as a rule readily water-soluble salts of complex salts of the above-mentioned metals and semi-metals, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precursors of components (c) are as a rule readily water-soluble salts of the above-mentioned alkali metals and alkaline earth metals, such as hydroxides, carbonates, nitrates, chlorides, acetates, formates and sulfates, preferably hydroxides and carbonates.
The precipitation is effected in general from aqueous solutions, alternatively by adding precipitating reagents, by changing the pH or by changing the temperature.
The catalyst material thus obtained is usually dried, in gener
Bassler Peter
Bohnsack Andreas
Fischer Rolf
Flick Klemens
Luyken Hermann
BASF - Aktiengesellschaft
Keil & Weinkauf
McKane Joseph K.
Murray Joseph
LandOfFree
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