Suspension of multimetal cyanide compounds, their...

Details Suspension of multimetal cyanide compounds, their... Suspension of multimetal cyanide compounds, their...

1999-06-02

2004-10-05

Wood, Elizabeth D. (Department: 1755)

Catalyst, solid sorbent, or support therefor: product or process

Catalyst or precursor therefor

Inorganic carbon containing

C502S200000, C502S161000, C502S162000, C502S168000, C502S159000, C502S172000, C423S364000, C423S367000, C423S371000, C423S384000, C423S414000

Reexamination Certificate

active

06800583

ABSTRACT:

The present invention relates to suspensions of multimetal Cyanide compounds, their preparation and their use.
Polyether alcohols are used in large quantities for producing polyurethanes. They are usually prepared by catalytic addition of lower alkylene oxides, in particular ethylene oxide and propylene oxide, onto H-functional initiator substances. Catalysts used are usually basic metal hydroxides or salts, with potassium hydroxide having the greatest industrial importance.
In the synthesis of polyether alcohols having long chains, as are used, in particular, for producing flexible polyurethane foams, secondary reactions occur as chain growth progresses, leading to faults in the chain structure. These by-products are referred to as unsaturated consituents and adversely affect the properties of the resulting polyurethanes. There has therefore been no lack of attempts in the past to prepare polyether alcohols having a low content of unsaturated constituents. In particular, the alkoxylation catalysts used have been changed in a targeted way in an attempt to achieve this. Thus, EP-A-268 922 proposes using cesium hydroxide as catalyst. Although this does succeed in lowering the content of unsaturated constituents, cesium hydroxide is expensive and disposing of it is problematical.
Furthermore, the use of multimetal cyanide complexes, usually zinc hexacyanometalates, for preparing polyether alcohols having a low content of unsaturated constituents is known. There is a large number of documents in which the preparation of polyether alcohols using multimetal cyanide complexes as catalysts is described. Thus, DD-A-203 735 and DD-A-203 734 describe the preparation of polyetherols using zinc hexacyanocobaltate.
The preparation of the zinc hexacyanometalates is also known. These catalysts are usually prepared by reacting solutions of metal salts such as zinc chloride with solutions of alkali metal or alkaline earth metal cyanometalates such as potassium hexacyanocobaltate. A water-miscible, heteroatom-containing component is generally added to the resulting suspension immediately after the precipitation procedure. This component can also be present in one or both of the starting solutions. This water-miscible, heteroatom-containing component can be, for example, an ether, polyether, alcohol, ketone or a mixture thereof. 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, U.S. Pat. No. 3,427,256, U.S. Pat. No. 3,427,334, U.S. Pat. No. 3,404,109, U.S. 3,829,505, U.S. Pat. No. 3,941,849, EP 283,148, EP 385,619, EP 654,302, EP 659,798, EP 665,254, EP 743,093, EP 755,716, U.S. Pat. No. 4,843,054, U.S. Pat. No. 4,877,906, U.S. Pat. No. 5,158,922, U.S. Pat. No. 5,426,081, U.S. Pat. No. 5,470,813, U.S. Pat. No. 5,482,908, U.S. Pat. No. 5,498,583, U.S. Pat. No. 5,523,386, U.S. Pat. No. 5,525,565, U.S. Pat. No. 5,545,601, JP 7,308,583, JP 6,248,068, JP 4,351,632 and U.S. Pat. No. 5,545,601.
DD-A-148 957 describes the preparation of zinc hexacyanoiridate and its use as catalyst in the preparation of polyether alcohols. Here, hexacyanoiridic acid is used as one starting material. This acid is isolated as a solid and is used in this form.
EP 862 947 describes the preparation of double metal cyanide complexes using hexacyanometalic acids, in particular hexacyanocobaltic acid, or their aqueous solutions as starting material. The double metal cyanides produced as described in EP 862 947 have a high reactivity in respect of the ring-opening polymerization of alkylene oxides.
Although multimetal cyanide catalysts have high polymerization activities, there has been no lack of attempts to achieve a further increase in the catalytic activity of the multimetal cyanide compounds. A major focus of work in this area is directed at multimetal cyanide compounds which are amorphous. The preparation of such multimetal cyanide compounds is disclosed, inter alia, in EP 654,302. However, it has been able to be shown that the activity of these catalysts can be increased further by the incorporation of polymers. Thus, EP 700,949 describes double metal cyanide complexes having an increased reactivity and containing from 5 to 80 percent by weight, based on the catalyst, of polyethers having a molar mass of greater than 500 dalton. WO 97/40,086 describes double metal cyanide catalysts having an increased reactivity and containing from 5 to 80% by weight of polyethers having molar masses of less than 500 dalton. WO 98/16310 discloses double metal cyanides which contain from 2 to 80% by weight of functionalized polymers, but no polyethers. The double metal cyanide catalysts disclosed in EP-A-700,949, WO-A-97/40,086 and WO-A-98/16,310 are generally amorphous. According to WO 98/16,310 (page 2, lines 16-22), the best double metal cyanide catalysts known at present have a low degree of crystallinity. The preferred catalysts are essentially noncrystalline (page 3, lines 10-11).
Multimetal cyanide catalysts are usually used in the form of powder for preparing polyether alcohols. U.S. Pat. Nos. 4,477,589 and 4,472,560 describe suspensions of multimetal cyanide compounds in propoxylated glycerol having contents of multimetal cyanide compound of less than 5% by weight. U.S. Pat. Nos. 5,639,705 and 5,714,639 describe catalysts in the form of pastes which comprise from 10 to 60% by weight of multimetal cyanide compound, from 40 to 90% by weight of an organic complexing agent and from 1 to 20% by weight of water.
It is an object of the present invention to use crystalline multimetal cyanide compounds in a form which gives them a very high catalytic activity.
We have found that this object is achieved by suspending crystalline multimetal cyanide compounds in organic or inorganic liquids and using them as catalysts in this form. It is particularly advantageous for the suspended multimetal cyanide compound to have a platelet-like morphology.
The present invention accordingly provides a catalyst suspension for the ring-opening polymerization of alkylene oxides, comprising
a) at least one multimetal cyanide compound having a crystalline structure and a content of platelet-shaped particles of at least 30% by weight, based on the multimetal cyanide compound, and
b) at least one organic complexing agent
c) water and/or
d) at least one polyether and/or
e) at least one surface-active substance, with the proviso that at least component a) and at least two of the components b) to e) have to be present.
The organic complexing agent b) is selected, in particular, from the group consisting of alcohols, ethers, esters, ketones, aldehydes, carboxylic acids, amides, nitrites, sulfides and mixtures thereof.
As polyethers d), use is made, in particular, of polyether alcohols, preferably hydroxyl-containing polyaddition products of ethylene oxide, propylene oxide, butylene oxide, vinyloxirane, tetrahydrofuran, 1,1,2-trimethylethylene oxide, 1,1,2,2-tetramethylethylene oxide, 2,2-dimethyloxetane, diisobutylene oxide, &agr;-methylstyrene oxide and mixtures thereof.
As surface-active substances e), use is made, in particular, of compounds selected from the group consisting of C
4
-C
60
-alcohol alkoxylates, block copolymers of alkylene oxides of differing hydrophilicity, alkoxylates of fatty acids and fatty acid glycerides, block copolymers of alkylene oxides and polymerizable acids and esters.
The crystalline multimetal cyanide compounds used according to the present invention are preferably prepared by the following method:
a) Addition of an aqueous solution of a water-soluble metal salt of the formula M
1
m
(X)
n
, where M
1
is at least one 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+
, Cd
2+
, Hg
2+
, Pd
2+
, Pt
2+
, V
2+
, Mg
2+
, Ca
2+
, Ba
2+
and mixtures thereof,
X is at least one anion selected from t

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