Inorganic anion exchangers and preparation thereof
AssigneeThe Dow Chemical Company
InventorHoward W. Clark
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Abstract
A novel composition including an inorganic mixed metal oxides and partially hydrated oxides exhibiting anion exchange properties and a method of preparing the exchanger composition by coprecipitating hydroxides or hydrated oxides of a pair of metal elements such as aluminum and titanium, drying the mixed metal hydroxides or hydrated oxides, exchanging the anion of the mixed metal hydroxide or hydrated oxide for a nonvolatile anion such as a sulfate anion and calcining the mixed metal hydroxide or hydrated oxide to form a mixed metal oxide or partially hydrated oxide exhibiting anion exchange properties.
Claims35
An anion exchanger material comprising a material exhibiting anion exchange properties at temperatures above about 160.degree. C., said material represented by the formula:
- [M.sub.1-x.sup.a Q.sub.x.sup.a+1 O.sub.y (OH).sub.z ](A.sup.-1).sub.d (A.sup.-2).sub.e (A.sup.-3).sub.f (A.sup.-4).sub.g.nH.sub.2 O
- wherein M is a metal element or elements each with a positive valence of a;
- Q is a metal element or elements each with a positive valence of a+1;
- a is 2, 3, 4, or 5;
- A.sup.-1, A.sup.-2, A.sup.-3, and A.sup.-4 are each one or more exchangeable anions each having a negative valence of 1, 2, 3, or 4, respectively;
- x is 0<x.ltoreq.0.5;
- and n, z, d, e, f, and g are real numbers greater than or equal to zero and satisfy the following:
- y.ltoreq.z
- 2y+z=a
- 0<d+2e+3f+4g+.ltoreq.x
- 0.ltoreq.n.ltoreq.10.
A method comprising providing an inorganic mixed metal hydroxide or hydrated oxide having anion exchange properties, exchanging the anion of the mixed metal hydroxide or hydrated oxide for a nonvolatile anion that does not decompose to gaseous products between about 160.degree. C. and about 800.degree. C. and heating the exchanged mixed metal hydroxide or hydrated oxide to form a mixed metal oxide exhibiting anion exchange properties at above about 160.degree. C.
A method comprising
- (a) coprecipitating in an aqueous medium at a constant pH an inorganic mixed metal hydroxide or hydrated oxide;
- (b) drying the mixed metal hydroxide or hydrated oxide at a temperature of below about 150.degree. C.,
- (c) exchanging the anion of the dried mixed metal hydroxide or hydrated oxide for a nonvolatile anion that does not decompose to gaseous products between about 160.degree. C. and about 800.degree. C., and
- (d) heating the exchanged mixed metal hydroxide or hydrated oxide to form a mixed metal oxide exhibiting anion exchange properties at above about 160.degree. C.
Dependencies are inferred from the claim text.