Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
1999-03-10
2001-04-24
Higel, Floyd D. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
C558S452000, C502S031000, C502S074000, C502S103000, C502S177000, C502S252000, C502S245000, C564S492000, C564S511000
Reexamination Certificate
active
06222059
ABSTRACT:
The present invention relates to a process for Preparing aliphatic alpha,omega-amino nitrites in the presence of a catalyst.
DE-A 44 468 93 discloses a process for preparing aliphatic alpha,omega-amino nitrites by partial hydrogenation of aliphatic alpha,omega-dinitriles at elevated temperature and elevated pressure in the presence of a solvent and of a catalyst by using a catalyst which comprises
(a) a compound based on a metal selected from the group consisting of nickel, cobalt, iron, ruthenium and rhodium, and
(b) 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 an alkaline earth metal,
with the proviso that component (a) does not consist on the basis of iron or iron and one of the metals selected from the group consisting of cobalt, ruthenium and rhodium when (b) is a promoter based on a metal selected from the group consisting of titanium, manganese, chromium and molybdenum, and with the further proviso that when 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 be omitted if required.
The disadvantage of this process is the formation of by-products which can be separated only with great difficulty from the alpha,omega-amino nitrites, such as 6-aminocapronitrile or, where appropriate, other required products, such as adiponitrile and hexamethylenediamine in the case of 6-aminocapronitrile as alpha,omega-amino nitrile.
Thus, for example in the case of the hydrogenation of adiponitrile to 6-aminocapronitrile and hexamethylenediamine, there is formation in varying amounts of, inter alia, 1-amino-2-cyanocyclopentene (ICCP), 2-aminomethyl.cyclopentylamine (AMCPA), 1,2-diaminocyclohexane (DCH) and bishexamethylenetriamine (BHMTA). U.S. Pat. No. 3,696,153 discloses that AMCPA and DCH can be separated from hexamethylenediamine only with great difficulty.
Furthermore, the useful life of the catalysts in this process is not entirely satisfactory.
It is an object of the present invention to provide a process for preparing aliphatic alpha,omega-amino nitrites by partial hydrogenation of aliphatic alpha,omega-dinitriles in the presence of a catalyst which does not have said disadvantages and which allows alpha,omega-amino nitriles to be prepared with high selectivity in an industrially straightforward and economic manner.
We have found that this object is achieved by a process for preparing aliphatic alpha,omega-amino nitriles by partial hydrogenation of aliphatic alpha,omega-dinitriles in the presence of a catalyst, wherein the catalyst used for the partial hydrogenation comprises
(a) iron or a compound based on iron or mixtures; thereof and
(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, zirconium, titanium and vanadium and
(c) from 0 to 5% by weight, based on (a), of a compound based on an alkali metal or alkaline earth metal.
Preferred catalyst precursors are those in which component (a) contains from 90 to 100% by weight, 95 to 100% by weight [sic , preferably 92 to 99% by weight, 96 to 99% by weight [sic], and in particular 98 to 99% by weight, based on (a), of iron oxides, iron hydroxides, iron oxyhydroxides or mixtures thereof. Suitable examples thereof are iron(III) oxide, iron(II,III) oxide, iron(II) oxide, iron(II) hydroxide, iron(III) hydroxide or iron oxyhydroxide such as FeOOH. It is possible to use synthetic or natural iron oxides, iron hydroxides or iron oxyhydroxides such as magnetic iron ore (magnetite), which in the ideal case can be described by Fe
3
O
4
, brown iron ore, which in the ideal case can be described by Fe
2
O
3
.H
2
O or red iron ore (hematite), which in the ideal case can be described by Fe
2
O
3
.
Further preferred catalyst precursors are those in which component (b) contains from 0.01 to 5% by weight, preferably 0.5 to 4% by weight, in particular 1 to 3% 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, such as aluminum, silicon and vanadium.
Further preferred catalyst precursors are those in which component (c) contains from 0 to 5% by weight, 0 to 0.5% by weight [sic], preferably 0.05 to 0.4% by weight, 0.1 to 3% by weight [sic], in particular 0.1 to 0.2% by weight, of a compound based on an alkali metal or alkaline earth metal, preferably selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium and calcium.
The catalysts according to the invention can be unsupported or supported catalysts. Examples of suitable carrier materials are porous oxides such as alumina, silica, aluminosilicates, lanthanum oxide, titanium dioxide, zircon dioxide, magnesium oxide, zinc oxide and zeolites, and active carbon or mixtures thereof.
Preparation as a rule takes place by precipitating precursors of component (a) if required together with precursors of the promoter components (b) and, if required, with precursors of the trace components (c) in the presence or absence of carrier materials (depending on which type of catalyst is required), if required processing the resulting catalyst precursor to extrudates or tablets, drying and subsequently calcining. Supported catalysts can in general also be obtained by impregnating the carrier with a solution of components (a), (b) and, if required, (c), it being possible to add the individual components simultaneously or successively, or by spraying components (a), if required (b) and (c), onto the carrier by conventional methods.
Suitable precursors of components (a) are, as a rule, iron salts which are readily soluble in water, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precursors of components (b) are, as a rule, salts or complex salts, which are readily soluble in water, of the abovementioned metals and metalloids, such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precursors of components (c) are, as a rule, salts, which are readily soluble in water, of the abovementioned alkali metals and alkaline earth metals, such as hydroxides, carbonates, nitrates, chlorides, acetates, formates and sulfates, preferably hydroxides and carbonates.
The precipitation generally takes place from aqueous solutions, as selected by adding precipitants, by altering the pH or by changing the temperaure.
The resulting catalyst intermediate is normally dried at from 80 to 150, preferably from 80 to 120, ° C.
The calcination is normally carried out at from 150 to 500, preferably from 200 to 450,° C. in a stream of air or nitrogen.
The catalyst composition resulting after the calcination is generally exposed to a reducing atmosphere (activation), for example by exposing it to a hydrogen atmosphere or a gas mixture containing hydrogen and an inert gas such as nitrogen, at from 200 to 500, preferably from 250 to 400, ° C. for 2 to 24 h. The catalyst loading in this case is preferably 200 1 per 1 of catalyst.
The catalyst is advantageously activated directly in the synthesis reactor because this normally makes an intermediate step which is otherwise necessary, namely passivation of the surface, normally at from 20 to 80, preferably from 25 to 35, ° C. using oxygen
itrogen mixtures such as air, unnecessary. The activation of passivated catalysts is then preferably carried out in the synthesis reactor at from 180 to 500, preferably from 200 to 350,° C. in a hydrogen-containing atmosphere.
The catalysts can be employed as fixed bed catalysts in upflow or downflow procedures or as suspended catalysts.
The s
Ebel Klaus
Fischer Rolf
Flick Klemens
Merger Martin
Voit Guido
BASF - Aktiengesellschaft
Higel Floyd D.
Keil & Weinkauf
Sackey Ebenezer
LandOfFree
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