Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Organic compound containing
Reexamination Certificate
2000-09-09
2002-03-26
Barts, Samuel (Department: 1621)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Organic compound containing
C502S104000, C502S152000, C502S153000, C502S159000, C502S172000, C502S175000, C502S183000, C502S200000, C568S620000, C568S621000, C568S679000, C568S613000
Reexamination Certificate
active
06362126
ABSTRACT:
The present invention relates to double-metal cyanide catalysts, to their preparation, and to their use for preparing polyether alcohols having a low content of unsaturated compounds.
Polyether alcohols are important starting materials in the preparation of polyurethanes. They are usually prepared by the catalyst addition reaction of lower alkylene oxides, in particular ethylene oxide and propylene oxide, onto H-functional initiator substances. The catalysts used are usually basic metal hydroxides or salts, with potassium hydroxide having the greatest practical importance.
In the preparation of polyether alcohols having long chains, as are used, in particular, for producing flexible polyurethane foams, advancing chain growth is associated with secondary reactions, which lead to byproducts. These byproducts are referred to as unsaturated constituents. They are monofunctional regarding their OH functionality and lead to impairment of the properties of the resulting polyurethanes. There has therefore been no lack of attempts to prepare polyether alcohols having a low content of unsaturated constituents. Thus, EP-A 268 922 proposes using cesium hydroxide as catalyst. Although this can significantly lower the content of unsaturated constituents, cesium hydroxide is expensive and presents a disposal problem.
It is furthermore known to use multimetal cyanide compounds, in particular zinc hexacyanometallates, as catalysts. A large number of documents describe the preparation of such compounds. For example, DD-A-203 734 and DD-A-203 735 describe the preparation of polyether alcohols using zinc hexacyanocobaltate.
The preparation of the zinc hexacyanometallates is also known. It is usually carried out by reacting solutions of metal salts, mostly zinc chloride, with solutions of alkali metal or alkaline earth metal cyanometallates, such as potassium hexacyanocobaltate. In general, the precipitation procedure is immediately followed by addition of a water-miscible component containing one or more heteroatoms to the resultant precipitation suspension. This component can also be present beforehand in one or both starting solutions. This water-miscible, heteroatom-containing component can preferably be an ether, polyether, alcohol, ketone or a mixture of at least two of said compounds. Such processes are described, for example, in U.S. Pat. No. 3,278,457, U.S. Pat. No. 3,278,458, U.S. Pat. No. 3,278,459 and U.S. Pat. No. 3,427,256.
DD-A-148 957 describes the preparation of zinc hexacyanoiridate and its use as a catalyst in the preparation of polyether alcohols. One starting material used here in place of the corresponding salt is hexacyanoiridic acid. The double-metal cyanide compounds prepared by means of acid usually have higher activity than those prepared by means of hexacyanometallate salts.
At present, polyether alcohols are prepared in batch processes. In these, the catalyst is suspended in the initiator. When the reaction is complete, the catalyst must be separated from the final product. It would be cheaper to carry out the reaction using a preformed catalyst which can be removed simply from the final product after the reaction or, if desired, immobilized in a fixed bed, so that work-up of the polyether alcohol requires negligible effort. U.S. Pat. No. 5,525,565, U.S. Pat. No. 5,523,386, U.S. Pat. No. 5,489,583, U.S. Pat. No. 5,426,081 and EP-A-659 798 disclose foam-supported double-metal cyanide catalysts. However, the inadequate mechanical strength of the foam means that these are not very suitable as fixed-bed catalysts.
It is an object of the present invention to provide double-metal cyanide catalysts which are simple to separate from the polyetherol and, if desired, allow the polyether alcohol synthesis to be carried out continuously.
We have found that this object is achieved by applying double-metal cyanide complexes to solid supports or incorporating them in solid supports or by shaping the double-metal cyanide complexes to give moldings.
Accordingly, the present invention provides double-metal cyanide catalysts of the formula
M
1
a
[M
2
(CN)
b
(A)
c
]
d
.fM
1
g
X
n
.h(H
2
O).eL, where
M
1
is a metal ion selected from the group consisting of Zn
2+
, Fe
2+
, Co
3+
, Ni
2+
, Mn
2+
, Co
2+
, Sn
2+
, Pb
2+
, Fe
3+
, Mo
4+
, Mo
6+
, Al
3+
, V
4+
, V
5+
, Sr
2+
, W
4+
, W
6+
, Cr
2+
, Cr
3+
and Cd
2+
, preferably Zn
2+
, Fe
2+
, Ni
2+
, Mn
2+
, Co
2+
and Cr
2+
, particularly preferably Zn
2+
,
M
2
is a metal ion selected from the group consisting of Fe
2+
, Fe
3+
, Co
3+
, Cr
3+
, Mn
2+
, Mn
3+
, Rh
3+
, Ru
2+
, Ru
3+
, V
4+
, V
5+
, Co
2+
, Ir
3+
and Cr
2+
, preferably Co
3+
, Fe
3+
, Fe
2+
, Rh
3+
and Ir
3+
, particularly preferably Co
3+
, Rh
3+
, Ir
3+
and Fe
3+
, where M
2
can be identical to or different from M
1
,
A is an anion selected from the group consisting of halide, hydroxide, sulfate, carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate and nitrate,
X is an anion selected from the group consisting of halide, hydroxide, sulfate, carbonate, cyanide, thiocyanate, isocyanate, cyanate, carboxylate, oxalate and nitrate,
L is at least one water-miscible organic ligand selected from the group consisting of alcohols, aldehydes, ketones, ethers, polyethers, esters, ureas, amides, nitriles and sulfides,
a, b, c, d, g and n are selected so as to make the compound electrically neutral,
e denotes the coordination number of the ligand,
e and f denote fractions or integers greater than or equal to zero,
h denotes a fraction or integer greater than or equal to zero,
which have been applied to solid, unfoamed supports or incorporated therein or have been shaped to give moldings.
The supports according to the invention are macroscopic moldings, as are usual and known as catalyst supports, for example extrudates, grit, tablets, meshes, packing elements, fabrics, fibers, balls and the interior walls of reactors. The macroscopic moldings can consist of inorganic and/or organic materials. Examples of inorganic materials are oxides, carbides, nitrides and inert metals. Examples of carbides are transition-metal carbides, such as tungsten carbide, silicon carbide and boron carbide. Examples of suitable nitrides are boron nitride, silicon nitride and aluminum nitride. Suitable inert metals are metals or metal alloys which are inert in the reaction medium used in the double-metal cyanide synthesis and in the polyether alcohol synthesis. Examples thereof are steels, aluminum, noble metals, nickel, stainless steels, titanium, tantalum and Kanthal. Oxides which can be used are metal oxides which are inert under said reaction conditions, in particular those of metals from groups IIA to IVA and IB to VIIIb, and oxidic compounds containing elements from groups IA to VIIA and/or metals from groups Ib to VIIIb.
The novel catalysts can be prepared by applying the double-metal cyanide complexes to the surface of the shaped supports or by mixing double-metal cyanide complexes with unshaped support material and then shaping the mixture. It is also possible to shape pulverulent double-metal cyanide complexes to give unsupported catalysts.
The double-metal cyanide complexes can be prepared by conventional processes.
The process of the present invention is divided into the following process steps:
a) reaction of an aqueous solution of a water-soluble metal salt of the formula M
1
m
(X)
n
, where M
1
is a metal ion selected from the group consisting of Zn
2+
, Fe
2+
, Co
3+
, Ni
2+
, Mn
2+
, Co
2+
, Sn
2+
, Pb
2+
, Fe
3+
, Mo
4+
, Mo
6+
, Al
3+
, V
5+
, Sr
2+
, W
4+
, W
6+
, Cu
2+
, Cr
2+
, Cr
3+
and Cd
2+
,
X is an anion selected from the group consisting of halide, hydroxide, sulfate, carbonate, cyanide, thiocyanate, isoc
Grosch Georg Heinrich
Junge Dieter
Kammel Ulrich
Larbig Harald
Lorenz Reinhard
Barts Samuel
BASF - Aktiengesellschaft
Borrego Ferrando A.
Prize Elvis O.
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