Crystalline double metal cyanide catalysts for producing...

Details Crystalline double metal cyanide catalysts for producing... Crystalline double metal cyanide catalysts for producing...

2000-04-05

2001-11-27

Keys, Rosalynd (Department: 1621)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S618000, C568S620000, C568S623000, C568S624000, C568S625000, C502S152000, C502S159000, C502S162000, C502S167000, C502S175000

Reexamination Certificate

active

06323375

ABSTRACT:

The present invention relates to highly active, substantially crystalline double metal cyanide (DMC) catalysts for the production of polyether polyols by polyaddition of alkaline oxides to starter compounds containing active hydrogen atoms.
Double metal cyanide (DMC) catalysts for the polyaddition of alkaline oxides to starter compounds containing active hydrogen atoms are known (see for example U.S. Pat. Nos. 3,404,109, 3,829,505, 3,941,849, and 5,158,922). The use of these DMC catalysts for producing polyether polyols achieves in particular a reduction in the proportion of monofunctional polyethers with terminal double bonds, so-called monools, compared to the conventional production of polyether polyols by means of alkali metal catalysts such as alkali metal hydroxides. The resultant polyether polyols may be processed into high-grade polyurethanes (for example elastomers, foams, coatings). DMC catalysts are normally obtained by reacting an aqueous solution of a metal salt with the aqueous solution of a metal cyanide salt in the presence of a low molecular weight complex ligand, for example an ether. In a typical catalyst preparation aqueous solutions of for example zinc chloride (in excess) and potassium hexacyanocobaltate are mixed and then dimethoxyethane (glyme) is added to the resultant suspension. After filtering and washing the catalyst with aqueous glyme solution an active catalyst of the general formula
Zn
3
[Co(CN)
6
]
2
.x
ZnCl
2
.y
H
2
O.
z
Glyme
is obtained (see for example EP 700 949).
From EP 700 949, WO 97/40086 and WO 98/16310 improved DMC catalysts are known that contain, in addition to the double metal cyanide compound and the organic complex ligand, also a polyether (EP 700 949, WO 97/40086) or a functionalised polymer and/or a water-soluble metal salt derived therefrom (WO 98/16310).
The improved DMC catalysts have an extremely high activity and enable polyether polyols to be produced at very low catalyst concentrations (20-25 ppm; see Table 1 in WO 98/16310).
The improved DMC catalysts described in EP 700 949, WO 97/40086 and WO 98/16310 are predominantly non-crystalline (i.e. amorphous). A decisive factor for the very high activity of these DMC catalysts is that the formation of highly crystalline forms of the catalyst is suppressed during the preparation (see p.11, lines 20-28 in WO 98/16310). As a result the X-ray diffraction diagram of the catalyst powder is characterised by the absence of sharp lines, characteristic of highly crystalline zinc hexacyanocobaltate, at for example 5.07, 3.56, 2.54 and 2.28 Å (see p.4 lines 25-26 in EP 700 949, p.8, lines 5-8 in WO 97/40086 and p.8, lines 26-29 in WO 98/16310). The X-ray diffraction diagrams of these catalysts on the other hand exhibit a single, relatively sharp peak at about 3.7-3.8 Å and two further, broader signals at about 4.7-4.9 Å and 5.8-6.2 Å (see p.4, lines 22-24 and Table 2 in EP 700 949, p.8, lines 1-5 in WO 97/40086 and p.10, lines 7-16 and
FIG. 1
in WO 98/16310).
The object of the present invention was accordingly to provide improved DMC catalysts for the polyaddition of alkaline oxides to suitable starter compounds that have a significantly improved catalytic activity compared to the types of catalyst known hitherto. This leads, by reducing the reaction times of the polyether polyol production, to an improved economy of the process. Ideally the catalyst may as a result of its improved activity then be used in such low concentrations (20 ppm or less) that an otherwise very costly catalyst separation is no longer necessary, and the product can be used directly for polyurethane applications.
It has now surprisingly found that DMC catalysts that contain a double metal cyanide compound, an organic complex ligand and a functionalised polymer have a greatly increased activity in the production of polyether polyols if the DMC catalyst is substantially crystalline.
The present invention accordingly provides a highly active double metal cyanide (DMC) catalyst containing
a) one or more, preferably one, double metal cyanide compound,
b) one or more, preferably one, organic complex ligand different from c), and
c) one or more, preferably one, functionalised polymer,
the catalyst being substantially crystalline.
The catalyst according to the invention may optionally contain d) water, preferably 1 to 10 wt. % and/or e) one or more water-soluble metal salts, preferably 5 to 25 wt. % of the formula (I)M(X)
n
from the preparation of the double metal cyanide compounds a).
In formula (I) M is selected from the metals Zn (II), Fe II), Ni (II), Mn (II), Co (II), Sn (II), Pb (II), Fe (HI), Mo (IV), Mo (VI), Al (III), V (V), V (IV), Sr (II), W (IV), W (VI), Cu (II), and Cr (III). Particularly preferred are Zn (II), Fe (II), Co (II) and Ni (II). X are identical or different, preferably identical, and denote an anion, preferably selected from the group comprising halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, caroxylates, oxalates or nitrates. The value of n is 1, 2 or 3.
The double metal cyanide compounds a) contained in the catalysts according to the invention are the reaction products of water-soluble metal salts and water-soluble metal cyanide salts.
For the preparation of double metal cyanide compounds a) suitable water-soluble metal salts preferably have the general formula (I) M(X)
n
, M being selected from the metals Zn (II) Fe II), Ni (II), Mn (II), Co (II), Sn (II), Pb (II), Fe (III), Mo (IV), Mo (VI), Al (III), V (V), V (IV), Sr (II), W (IV), W (VI), Cu (II), and Cr (III). Particularly preferred are Zn (II), Fe (II), Co (II) and Ni (II). X are identical or different, preferably identical, and denote an anion, preferably selected from the group comprising halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, caroxylates, oxalates or nitrates. The value of n is 1, 2 or 3.
Examples of suitable water-soluble metal salts are zinc chloride, zinc bromide, zinc acetate, zinc acetylacetonate, zinc benzoate, zinc nitrate, iron (II) sulfate, iron (II) bromide, iron (II) chloride, cobalt (I) chloride, cobalt (II) thiocyanate, nickel (II) chloride and nickel (II) nitrate. Mixtures of different water-soluble metal salts may also be used.
Suitable water-soluble metal cyanide salts for the preparation of double metal cyanide compounds a) preferably have the general formula (II)(Y)
a
M′(CN)
b
(A)
c
, M′ being selected from the metals Fe(II), Fe(III), Co(II), Co(III), Cr(II), Cr(III), Mn(II), Mn(III), Ir(III), Ni(II), Rh(III), Ru(II), V(IV) and V(V). Particularly preferably M′ is selected from the metals Co(II), Co(III), Fe(II), Fe(III), Cr(II), Ir(III) and Ni(II). The water-soluble metal cyanide salt may contain one or more of these metals. Y are identical or different, preferably identical, and denote an alkali metal ion or an alkaline earth metal ion. A are identical or different, preferably identical, and denote an anion selected from the group comprising halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates or nitrates. a as well as b and c are integers, the values of a, b and c being chosen so as to ensure electrical neutrality of the metal cyanide salt; a is preferably 1, 2, 3 or 4; b is preferably 4, 5 or 6; c preferably has the value 0. Examples of suitable water-soluble metal cyanide salts are potassium hexacyanocobaltate (III), potassium hexacyanoferrate (II), potassium hexacyanoferrate (III), calcium hexacyanocobaltate (III) and lithium hexacyanocobaltate (III).
Preferred double metal cyanide compounds a) that are contained in the catalysts according to the invention are compounds of the general formula (III)
M
x
[M′
x
, (CN)
y
]
z
,
wherein M is defined as in Formula (I) and M′ is defined as in Formula (II), and x, x′, y and z are integers and are chosen so as to ensure the electrical neutrality of the double metal cyanide compound.
Preferably
x=3, x′&equa

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