Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Inorganic carbon containing
Reexamination Certificate
2001-01-23
2002-05-21
Wood, Elizabeth D. (Department: 1755)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Inorganic carbon containing
C502S200000, C521S174000, C568S613000, C568S616000, C528S421000
Reexamination Certificate
active
06391820
ABSTRACT:
The invention relates to novel double metal cyanide (DMC) catalysts for the preparation of polyether polyols by polyaddition of alkylene oxides to starter compounds containing active hydrogen atoms.
Double metal cyanide (DMC) catalysts for the polyaddition of alkylene oxides to starter compounds containing active hydrogen atoms are known (see, for example, U.S. Pat. No. 3,404,109, U.S. Pat. No. 3,829,505, U.S. Pat. No. 3,941,849 and U.S. Pat. No. 5,158,922). The use of those DMC catalysts for the preparation of polyether polyols brings about in particular a reduction in the proportion of monofunctional polyethers having terminal double bonds, so-called monools, in comparison with the conventional preparation of polyether polyols by means of alkali catalysts, such as alkali hydroxides. The polyether polyols so obtained can be processed to high-quality polyurethanes (e.g. elastomers, foams, coatings). DMC catalysts are usually obtained by reacting an aqueous solution of a metal salt with the aqueous solution of a metal cyanide salt in the presence of an organic complex ligand, for example an ether. In a typical catalyst preparation, for example, aqueous solutions of zinc chloride (in excess) and potassium hexacyanocobaltate are mixed, and dimethoxyethane (glyme) is then added to the suspension formed. After filtration and washing of the catalyst with aqueous glyme solution, an active catalyst of the general formula
Zn
3
[Co(CN)
6
]
2
.x
ZnCl
2
.yH
2
O.z glyme
is obtained (see, for example, EP 700 949).
From JP 4 145 123, U.S. Pat. No. 5,470,813, EP 700 949, EP 743 093, EP 761 708 and WO 97/40086 there are known DMC catalysts which, by the use of tert.-butanol as organic complex ligand (alone or in combination with a polyether (EP 700 949, EP 761 708, WO 97/40086)), further reduce the proportion of monofunctional polyethers having terminal double bonds in the preparation of polyether polyols.
Moreover, the use of those DMC catalysts reduces the induction time in the polyaddition reaction of the alkylene oxides with appropriate starter compounds and increases the catalyst activity.
U.S. Pat. No. 5,714,428 describes DMC catalysts which also contain carbohydrates, such as starch, in addition to tert.-butanol.
The object of the present invention was to make available further improved DMC catalysts for the polyaddition of alkylene oxides to appropriate starter compounds, which catalysts exhibit increased catalyst activity as compared with the catalyst types known hitherto. By shortening the alkoxylation times, this leads to an improvement in the process for preparing polyether polyols in terms of economy. Ideally, as a result of the increased activity, the catalyst can then be used in such low concentrations (25 ppm or less) that the very expensive separation of the catalyst from the product is no longer necessary and the product can be used directly for the preparation of polyurethanes.
Surprisingly, it has now been found that DMC catalysts that contain a glycoside as complex ligand possess greatly increased activity in the preparation of polyether polyols.
Accordingly, the present invention provides a double metal cyanide (DMC) catalyst containing
a) one or more, preferably one, double metal cyanide compound(s),
b) one or more, preferably one, organic complex ligand(s) other than c), and
c) one or more, preferably one, glycoside(s).
The catalyst according to the invention may optionally contain d) water, preferably from 1 to 10 wt. %, and/or e) one or more water-soluble metal salts, preferably from 5 to 25 wt. %, of 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(III), Mo(IV), Mo(VI), Al(III), V(V), V(IV), Sr(II), W(IV), W(VI), Cu(II) and Cr(III). Zn(II), Fe(II), Co(II) and Ni(II) are especially preferred. The substituents X are identical or different, preferably identical, and represent an anion, preferably selected from the group of the halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and 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.
Water-soluble metal salts suitable for the preparation of double metal cyanide compounds a) preferably have the general formula (I) M(X)
n
, wherein M is 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). Zn(II), Fe(II), Co(II) and Ni(II) are especially preferred. The substituents X are identical or different, preferably identical, and represent an anion, preferably selected from the group of the halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and 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(II) chloride, cobalt(II) thiocyanate, nickel(II) chloride and nickel(II) nitrate. Mixtures of various water-soluble metal salts may also be used. Water-soluble metal cyanide salts suitable for the preparation of double metal cyanide compounds a) preferably have the general formula (II) (Y)
a
M′(CN)
b
(A)
c
, wherein M′ is 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). M′ is selected especially from the metals Co(II), Co(III), Fe(II), Fe(III), Cr(III), Ir(III) and Ni(II). The water-soluble metal cyanide salt may contain one or more of those metals. The substituents Y are identical or different, preferably identical, and represent an alkali metal ion or an alkaline earth metal ion. The substituents A are identical or different, preferably identical, and represent an anion selected from the group of the halides, hydroxides, sulfates, carbonates, cyanates, thiocyanates, isocyanates, isothiocyanates, carboxylates, oxalates and nitrates. a as well as b and c are integers, the values for a, b and c being so selected that the metal cyanide salt is electroneutral; 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) 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 as defined in formula (I) and
M′ is as defined in formula (II) and
x, x′, y and z are integers and are so selected that the double metal cyanide compound has electron neutrality.
Preferably,
x=3, x′=1, y=6 and z=2,
M=Zn(II), Fe(II), Co(II) or Ni(II) and
M′=Co(III), Fe(III), Cr(III) or Ir(III).
Examples of suitable double metal halide compounds a) are zinc hexacyanocobaltate(III), zinc hexacyanoiridate(III), zinc hexacyanoferrate(III) and cobalt(II) hexacyanocobaltate(III). Further examples of suitable double metal cyanide compounds will be found in, for example, U.S. Pat. No. 5,158,922 (column 8, lines 29-66). The use of zinc hexacyanocobaltate(III) is especially preferred.
The organic complex ligands b) contained in the DMC catalysts according to the invention are in principle known and are described in detail in the prior art (see, for example, U.S. Pat. No. 5,158,922,especially column 6, lines 9-65, U.S. Pat. No. 3,404,109, U.S. Pat. No. 3,829,505, U.S. Pat. No. 3,941,849, EP 700 949, EP 761 708, JP 4 145 123, U.S. Pat. No. 5,470,813, EP 743 093 and WO 97/4
Gupta Pramod
Hofmann Jörg
Ooms Pieter
Schäfer Walter
Bayer Aktiengesellschaft
Gil Joseph C.
Sloane Carolyn M.
Wood Elizabeth D.
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