Organic compounds -- part of the class 532-570 series – Organic compounds – Amino nitrogen containing
Reexamination Certificate
2000-08-23
2001-08-21
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Amino nitrogen containing
Reexamination Certificate
active
06278023
ABSTRACT:
The present invention relates to a process for preparing aliphatic alpha, omega-diamines by hydrogenation of aliphatic alpha, omega-dinitriles in the presence of a catalyst, which comprises using a hydrogenation catalyst comprising
(a) iron or a compound based on iron or mixtures thereof,
(b) from 0.001 to 0.3% 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 also
(c) from 0 to 0.3% by weight based on (a) of a compound based on an alkali and/or alkaline earth metal.
The present invention further relates to the use of materials comprising said components (a), (b) and (c) as catalyst in the preparation of aliphatic alpha, omega-diamines by hydrogenation of aliphatic alpha, omega-dinitriles.
Weissermel/Arpe, Industrielle Organische Chemie, Verlag Chemie, third edition, 1988, page 266, discloses hydrogenating adiponitrile in the presence of ammonia under high pressure conditions over iron catalysts to obtain hexamethylenediamine, an important fiber intermediate for the manufacture of nylon-6,6.
Important requirements for optimal iron catalysts include high mechanical strength, a long time on stream, a high space-time yield of hexamethylenediamine coupled with complete adiponitrile and 6-aminocapronitrile conversion, and a high hexamethylene-diamine yield coupled with a very low level of unwanted by-products.
These unwanted by-products are formed in varying amounts, depending on the catalyst, and are difficult to separate from the desired diamine product.
For instance, the hydrogenation of adiponitrile to hexamethylenediamine by-produces varying quantities of, inter alia, 6-aminocapronitrile (ACN), tetrahydroazepine (THA), 1-amino-2-cyanocyclopentene (ICCP), 2-aminomethylcyclopentylamine (AMCPA), 1,2-diaminocyclohexane (DCH) and bishexamethylenetriamine (BHMTA). U.S. Pat. No. 3,696,153 discloses that AMCPA and DCH are very difficult to separate from hexamethylenediamine. Notably large amounts of AMCPA, DCH and THA necessitate a great deal of distillation, which is reflected in considerable capital and energy costs.
U.S. Pat. No. 4,282,381, column 2, Table 1, discloses that the hydrogenation of adiponitrile to hexamethylenediamine in the presence of iron catalysts by-produces inter alia on average from 2400 to 4000 ppm of 1,2-diaminocyclohexane, from 100 to 300 ppm of 2-aminomethylcyclopentylamine, from 200 to 900 ppm of tetrahydroazepine and from 2000 to 5000 ppm of 6-aminocapronitrile.
DE-A-2 429 293 discloses in Example 1 that the hydrogenation of adiponitrile in the presence of five times the weight of ammonia at from 93 to 98° C. (inlet temperature into the reactor) or at from 94 to 104° C. (outlet temperature) over an iron catalyst prepared from magnetite by reduction with hydrogen and doped with aluminum oxide, silicon dioxide, calcium oxide and vanadium pentoxide yields 98.22% of hexamethylenediamine comprising 1900 ppm of 1,2-diaminocyclohexane, and in Example 2 that the hydrogenation of adiponitrile in the presence of five times the weight of ammonia at from 93 to 98° C. (inlet temperature into the reactor) or at from 94 to 104° C. (outlet temperature) over an iron catalyst prepared from Labrador hematite ore (Fe
2
O
3
) by reduction with hydrogen and doped with aluminum oxide, silicon dioxide and calcium oxide yields 98.05% of hexamethylenediamine comprising 3500 ppm of 1,2-diaminocyclohexane.
It is an object of the present invention to provide a process for hydrogenating alpha, omega-dinitriles to alpha, omega-diamines in the presence of a catalyst without the disadvantages mentioned and with the capability of enabling the preparation of alpha, omega-diamines to be carried out with high selectivity in a technically simple and economical manner with a long time on stream of the catalyst.
We have found that this object is achieved by the process defined at the beginning and the use defined at the beginning.
The catalysts in the process of the invention and the use of the invention preferably have a BET surface area of from 3 to 20 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 0.01-0.1 &mgr;m pore volume fraction within the range from 50 to 70%.
The weight %ages in (b) are based on the elements and the weight %ages in (c) on the oxides of the alkali and alkaline earth metals. These percentages are based on component (a).
In preferred catalyst precursors, component (a) comprises from 90 to 100% by weight, preferably from 92 to 99% by weight, based on (a), of iron oxides, iron hydroxides, iron oxyhydroxides or mixtures thereof. Preference is given to using synthesized or naturally occurring iron oxides, iron hydroxides or iron oxyhydroxides, such as limonite, hematite, preferably magnetite, which in the ideal case can be described using the formula Fe
3
O
4
. The atomic ratio of oxygen to iron is preferably within the range from 1.25:1 to 1.45:1, preferably within the range from 1.3:1 to 1.4:1, particularly preferably equal to 1.33:1, i.e., pure magnetite.
If magnetite is synthesized, it is possible to start from very pure metallic iron or from very pure iron(II) compounds and/or iron(III) compounds, to which the doping elements are added subsequently in the form of suitable compounds.
Preference is further given to catalyst precursors in which component (b) comprises from 0.001 to 0.3% by weight, preferably from 0.01 to 0.2% by weight, especially from 0.01 to 0.1% by weight, of a promoter based on 2, 3, 4 or 5, preferably 3, 4 or 5, elements selected from the group consisting of aluminum, zirconium, silicon, titanium and vanadium, especially the combination of aluminum, silicon and titanium.
Preference is further given to catalyst precursors in which component (c) comprises from 0 to 0.3% by weight, preferably from 0.01 to 0.2% by weight, particularly preferably from 0.01 to 0.1% by weight, of a compound based on an alkali or alkaline earth metal selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, magnesium and calcium, preferably calcium and/or magnesium.
The catalysts of the invention can be supported or unsupported catalysts. Examples of possible support materials are porous oxides such as aluminum oxide, silicon dioxide, alumosilicates, lanthanum oxide, titanium dioxide, zirconium dioxide, magnesium oxide, zinc oxide, and zeolites and also activated carbon or mixtures thereof.
Preparation is generally effected by precipitating precursors of component (a) if desired together with precursors of promoter components (b) and if desired with precursors of components (c) in the presence or absence of support materials (depending on which catalyst type is desired), if desired processing the resulting catalyst precursor into extrudates or tablets, drying and then calcining. Supported catalysts are generally also obtainable by saturating the support with a solution of 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), and if desired (b) and (c) onto the support in a conventional manner.
Suitable precursors for components (a) are generally readily water-soluble salts of iron such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precusors for components (b) are generally readily water-soluble salts or complexes of the aforementioned metals and semimetals such as nitrates, chlorides, acetates, formates and sulfates, preferably nitrates.
Suitable precursors for components (c) are generally readily water-soluble salts of the aforementioned alkali metals and alkaline earth metals such as hydroxides, carbonates, nitrates, chlorides, acetates, formates and sulfates, preferably hydroxides and carbonates.
Precipitation is generally effected from aqueous solutions, selectively by adding precipitating reagents, by changing the pH or by changing the temperature.
The catalyst prematerial thus obtained is customarily dried at a temperature gen
Ansmann Andreas
Bassler Peter
Fischer Rolf
Luyken Hermann
Merger Martin
BASF - Aktiengesellschaft
Keil & Weinkauf
McKane Joseph K.
Murray Joseph
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