Organic compounds -- part of the class 532-570 series – Organic compounds – Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
2000-05-31
2002-03-05
Kifle, Bruck (Department: 1624)
Organic compounds -- part of the class 532-570 series
Organic compounds
Unsubstituted hydrocarbyl chain between the ring and the -c-...
Reexamination Certificate
active
06353101
ABSTRACT:
The present invention relates to a process for preparing lactams by cyclizing hydrolysis of amino nitriles with water in the gas phase on metal oxide catalysts.
Lactams are compounds which can be employed in a variety of ways. For example, N-methylpyrrolidone is a versatile solvent and &egr;-caprolactam is an important monomer for polyamide fibers. Caprolactam is prepared industrially by a Beckmann rearrangement of the oxime of cyclohexanone. This reaction results in large amounts of salts, generally sodium sulfate, as byproduct which must be disposed of.
U.S. Pat. No. 2,357,484 discloses a process for preparing amides and lactams from the corresponding nitriles and amines, and the amino nitriles respectively, by gas-phase reaction with water on catalysts with dehydrating properties. Catalysts indicated as usable are, in particular, alumina, silica gel and boric/phosphoric acid.
WO 96/22974 describes a process for preparing lactams by cyclizing hydrolysis of amino nitriles, using alumina catalysts with a specific surface area of ≧10 m
2
/g and a pore volume (of pores with a diameter of more than 500 Å) ≧10 ml/100 g.
U.S. Pat. No. 4,628,085 discloses a process for preparing lactams in the gas phase, where an aliphatic or aromatic amino nitrile and water are brought into contact with a silica-based catalyst with BET surface areas of more than 250 m
2
/g and pore diameters of less than 20 nm in the presence of hydrogen and ammonia.
The use of metal phosphates, especially aluminum, zirconium, niobium and lanthanum phosphates, as catalysts for preparing lactams in the gas phase from amino nitriles and water is described in EP-A 659 741. These catalysts can also be impregnated with basic alkali metal or alkaline earth metal compositions, with cesium, rubidium and potassium being preferred.
EP-A 748 797 discloses a process for preparing lactams from dinitriles, where the dinitrile is hydrogenated to the amino nitrile, and the amino nitrile is converted into the lactam by cyclizing hydrolysis. Disclosed as catalyst for the cyclizing hydrolysis are molecular sieves such as acidic zeolites, silicates and non-zeolite molecular sieves, metal phosphates and metal oxides or mixed oxides, which are, where appropriate, acidic or amphoteric due to treatment with halogens, ammonium halides or acids such as sulfuric acid or hydrohalic acid.
The disadvantage of the described processes is that the selectivity of the catalysts is inadequate in some cases, which on the one hand makes it difficult to isolate the lactams, and on the other hand leads to poisoning of the catalysts by the byproducts which are formed. It is also desirable to increase the activity of the catalysts.
It is an object of the present invention to provide a process for preparing lactams by cyclizing hydrolysis of amino nitriles which affords them with high selectivity and high space-time yield and, moreover, allows a long useful life of the catalyst.
We have found that this object is achieved by reacting the amino nitriles with water on oxides of the metals of groups 3, 4, 5, 13 and/or 14 of the Periodic Table as catalysts which comprise a phosphate, carbonate, silicate, arsenite, arsenate, antimonite, antimonate or nitrate of said metals and, where appropriate, a metal oxide of groups 6, 7, 8, 9 and/or 10.
The present invention therefore relates to a process for preparing lactams by cyclizing hydrolysis of amino nitriles with water in the gas phase on metal oxide catalysts, wherein the catalysts comprise:
at least one oxide or mixed oxide of the metals of groups 3, 4, 5, 13 and/or 14 of the Periodic Table,
one or more oxides or mixed oxides of metals of groups 6, 7, 8, 9 and/or 10,
at least one carbonate, silicate, phosphate, arsenite, arsenate, antimonite, antimonate and/or nitrate and/or when oxides or mixed oxides of metals of groups 6, 7, 8, 9 or 10 are present, a sulfate of the abovementioned metals.
The numbering of the groups of the Periodic Table in this specification is in accordance with the 1985 IUPAC proposal.
Catalysts preferred according to the invention are compounds of the formula I:
MQ
a
(RO
b
)
c
O
d
(I)
in which
M is Zr, Ti, Hf, Sc, Y, La, Ce, V, Nb or Ta, in particular Zr, Ti or Hf, and very especially Zr,
R is P, C, Si, N, As or Sb,
Q is a metal from group 6, 7, 8, 9 or 10,
a is a number from 0 to 10,
b is a number from 0.5 to 5,
c is a number from 0.001 to 0.15, and
d has the magnitude necessary to achieve neutrality of charge.
The catalysts comprise up to five molecules of water per formula unit. If a ≧0.001, R can also be S.
Catalysts which are particularly preferably used are compounds of the formula I in which
R is P or, if a ≧0.001, can also be S,
Q is Mn,
a is 0 to 0.1 and very particularly preferably 0 to 0.03, and
c is 0.001 to 0.1 and very particularly preferably 0.01 to 0.1,
and particularly preferred compounds are those in which R is P and Q is Mn.
The catalyst materials can be employed in any suitable form such as, for example, as powder, as chips or else as shaped articles. Examples of shaped articles which are used are extrudates or beads. For the shaping, a binder can be added, such as, for example, Aerosil, potato starch or celluloses, for example Walocel supplied by Wolff-Walsrode AG, these binders not being present in stated formula I. It is likewise possible for the catalyst materials to be applied to a carrier such as, for example, alumina, silica gel, carbon, silicon carbide or silicon nitride. The catalyst is preferably used in the novel process in the form of chips or shaped articles.
The catalyst bed may be mixed with a component to increase the selectivity in amounts of from 0 to 70% by volume. Examples thereof are silicon dioxide, preferably quartz, silicon nitride and silicon carbide.
The catalysts are prepared in a manner known per se and familiar to the skilled worker. The novel catalysts can be obtained, for example, by contacting at least one oxide and/or hydroxide of a metal of groups 3, 4, 5, 13 and/or 14 of the Periodic Table one or more times with suitable phosphates, sulfates, carbonates, silicates, arsenites, arsenates, antimonites, antimonates or nitrates, and then calcining at elevated temperature. Suitable examples are the corresponding salts of metals of groups 3, 4, 5, 13 and 14 of the Periodic Table, the ammonium salts of oxo acids of these metals and, if desired, the salts of the metals of groups 6 to 10 of the Periodic Table, and phosphoric acid, sulfuric acid or nitric acid and their ammonium salts.
The contacting takes place, for example, by adding a solution of the required phosphate, carbonate, silicate, nitrate, arsenite, arsenate, antimonite, antimonate or sulfate, or of the corresponding free acid, to an aqueous suspension of the metal oxide or hydroxide of groups 3, 4, 5, 13 or 14, of the Periodic Table, and then removing the water. This procedure can be repeated. The required components can be brought into contact all at once or in separate steps with the suspension of the metal oxide. In place of the solutions of the abovementioned salts, it is also possible to employ solutions of different salts of these metals in sulfuric acid, phosphoric acid or nitric acid, which is diluted with water where appropriate, as long as the anion of these salts forms a volatile acid with the mineral acid. Suitable salts are thus also the halides and the acetates as long as these are employed in one of the abovementioned acids or in aqueous solutions of these acids.
The components can moreover be converted into a homogeneous solution from which a crude catalyst composition is obtained, for example by evaporation or by addition of a precipitant, and is then converted into the active form of the catalyst by drying and calcination.
A further possible procedure is to spray a molding of the metal oxide, such as pellets, beads, hemispheres or extrudates, with aqueous solutions of suitable salts or the free acids. This procedure can be repeated several times, as a rule carrying out drying steps between the individual impregnation steps.
In a prefer
Eiermann Matthias
Narbeshuber Thomas
BASF - Aktiengesellschaft
Keil & Weinkauf
Kifle Bruck
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