Transition metal aluminates

Crystalline transition metal aluminate compounds are formed by reacting transition metal compounds with crystalline hydrous alumina, such as gibbsite, bayerite, norstrandite, boehmite and the like. The crystalline hydrous alumina may be unsupported by a solid substrate or may be supported on a solid substrate or within the pores of a solid substrate, such as a macroporous resin.

BACKGROUND OF THE INVENTION 
It has been taught in U.S. Pat. Nos. 4,333,846 and 4,392,980 that 
transition metal aluminates are prepared by reacting transition metal 
compounds with amorphous hydrous alumina, denoted as Al(OH).sub.3. The 
particular transition metal compounds demonstrated are Cu, Zn, Mn, Fe, Co, 
and Ni. These patents are incorporated herein by reference. 
SUMMARY OF THE INVENTION 
Crystalline transition metal aluminates are prepared by reacting alkali 
soluble transition metal compounds with crystalline hydrous alumina. These 
aluminates are useful, e.g., as precursors for spinel-type structures and 
as a catalytic materials. These compounds conform generally to the formula 
MA.sub.a.sup.v Z.sub.b.sup.v.nAl(OH).sub.3.mH.sub.2 O where M is a 
transition metal, n is a value to provide a mole ratio of Al/M in the 
range of about 1/1 to about 1.5/1 and m is zero or more for waters of 
hydration. A and Z represent anions as described below. 
DETAILED DESCRIPTION OF THE INVENTION 
The crystalline hydrous alumina which is to be reacted with a transition 
metal compound may be gibbsite, bayerite, norstrandite, boehmite, or any 
crystalline hydrous alumina which conforms, substantially, to the formula 
Al(OH).sub.3, Al.sub.2 O.sub.3.nH.sub.2 O or AlOOH. Amorphous hydrous 
alumina is excluded from the present inventive concept; the present use of 
crystalline hydrous aluminas provides greater amounts (higher loadings) of 
the transition metal aluminates in the pores of ion exchange resins. 
The transition metal compound is one which is soluble in a basic aqueous 
solution and is represented generally by the formula where MA.sub.a.sup.v 
Z.sub.b.sup.v where M is divalent, A and Z each represent negative valence 
ions or radicals selected from the group comprising hydroxyl, halide, 
inorganic acid, and organic acid, v is a negative valence of 1, 2, 3, or 
more, a and b are each values of from zero to 2, with (va)+(vb) equal to 
2. The "AZ" may represent, e.g., two monovalent ions or radicals; or one 
divalent ion or radical; or two-thirds of a trivalent ion or radical; or 
one-fourth of a quadrivalent ion or radical. 
Examples of monovalent, divalent, and trivalent anions and negative 
radicals contemplated as constituting the "AZ" portion of the aluminate 
compound are, for example: 
halide.sup.- (esp. Cl.sup.-, Br.sup.-, I.sup.-) 
hydroxy.sup.- (OH.sup.-) 
dihydroxyphosphate.sup.- (H.sub.2 PO.sub.4.sup.-) 
sulfate.sup.-- (SO.sub.4.sup.--) 
hydrocarbonic.sup.- (HCO.sub.3.sup.-) 
hydrophosphate.sup.-- (HPO.sub.4.sup.--) 
nitrate.sup.- (NO.sub.3.sup.-) 
chromate.sup.- (HCrO.sub.4.sup.-) 
trichloracetic.sup.- (Cl.sub.3 C-COO.sup.-) 
and other inorganic acid radicals and organic acid radicals of monobasic, 
dibasic, and polybasic carboxylic acids with the valence of 1, 2, or more 
corresponding to the number of carboxyl groups present in the organic acid 
moiety. Examples of quadrivalent polybasic carboxylic acids are 
ethylenediamine tetraacetic acid and pyromellitic acid. Citric acid is an 
example of a tribasic acid. 
The above is not an exhaustive listing, but is believed to be 
representative of the various negative radicals and anions contemplated to 
illustrate those which contain halogens, inorganic salt radicals, oxy 
radicals, and carboxylic radicals. Other radicals and anions will become 
obvious to practitioners of the relevant arts once they learn of the 
present invention. 
The crystalline hydrous alumina and the transition metal compound (M) are 
preferably reacted in a basic (alkaline) aqueous medium at a temperature 
and for a time sufficient to convert an appreciable amount of the 
reactants to crystalline transition metal aluminate represented by the 
formula MA.sub.a.sup.v Z.sub.b.sup.v.nAl(OH).sub.3.mH.sub.2 O where 
A.sub.a.sup.v Z.sub.b.sup.v is as defined above, where n is a value 
sufficient to provide an Al/M ratio of at least about 1/1, preferably at 
least about 1.5/1, most preferably at least about 2/1, and where m 
represents a value for waters of hydration of from zero (when the crystal 
has been dehydrated by heating) to as much as 6 or more, depending on the 
particular MAZ moiety in the crystal and also depending on the 
temperature, pH and conditions of preparation. 
The alkalinity of the aqueous reaction medium may be supplied by using an 
alkali metal hydroxide or an alkaline earth metal hydroxide, but the 
alkaline earth metal cations (being divalent) are more likely to interfere 
with optimum conversion of the transition metal compound, so the alkali 
metal hydroxides are preferred, especially NaOH which is readily and 
abundantly available. 
The amount of the alkaline compound, e.g. NaOH, should be enough to exhibit 
a pH of at least about 8 in the reaction mixture, preferably a pH of at 
least about 9 to about 14, most preferably a pH of about 13. 
The amount of alkaline aqueous solution employed as the reaction medium 
should be at least enough to solubilize the MAZ compound and to slurry the 
hydrous alumina. The aqueous medium is substantially removed by filtration 
or decantation at the end of the reaction period and the remaining 
dampness of the reaction product may be reduced or removed by heating to 
dryness, by evaporation, or by dessication. 
The time and temperature effective in reacting the crystalline hydrous 
alumina with the MAZ compound are interdependant, the time being shortened 
by elevating the temperature. Temperatures up to the boiling point may be 
used. 
It is within the purview of the present invention to use transition metals 
which, under the conditions employed in the present method, will be 
divalent in the aluminate compound formed, especially Cu, Zn, Mn, Fe, Co, 
or Ni, most preferable Co and Ni. 
The crystalline hydrous Al(OH).sub.3, such as gibbsite, bayerite, 
norstrandite, boehmite, and the like with which the transition metal 
compound is reacted may be carried on a substrate or dispersed within the 
pores of a porous solid, including ion exchange resins.

The following examples illustrate embodiments within the purview of the 
present inventive concept but the invention is not limited to the 
particular embodiments illustrated. 
EXAMPLE 1 
About 2 grams of crystalline Al(OH).sub.3, of the gibbsite form, and 7 ml. 
of 50% NaOH solution are mixed with 15 ml. of saturated CoCl.sub.2 
solution. After about 24 hours at 95.degree. C. the reaction product is 
separated from the soluble portions, washed well with water, and dried to 
ambient room conditions. Analysis by x-ray diffraction confirms that 
crystalline CoCl.sub.2.Al(OH).sub.3.mH.sub.2 O is produced. 
EXAMPLE 2 
In substantially the same manner as in Example 1, other forms of 
crystalline hydrous alumina compounds, i.e., bayerite, norstrandite, 
boehmite, Al.sub.2 O.sub.3.nH.sub.2 O and AlOOH, are reacted with Co 
compounds in an alkaline aqueous carrier, at elevated temperature to form 
crystalline cobalt aluminate compounds of the formula CoA.sub.a.sup.v 
Z.sub.b.sup.v.nAl(OH).sub.3.mH.sub.2 O, where AZ represents anions or 
negative-valence radicals in amounts sufficient to substantially satisfy 
the valence requirements of Co, and where n is a value of at least 1. 
EXAMPLE 3 
About 100 cc of DOWEX MWA-1-OH macroporous ion exchange resin (in the base 
form) containing 4.2 mmole Al/cc as crystalline bayerite, Al(OH).sub.3, is 
mixed with a solution 50 gm. CoCl.sub.2.6H.sub.2 O, 84 ml. 30% aq. 
solution of NH.sub.4 OH, 5 ml. of 50% aq. caustic (NaOH), and enough water 
to give a total voume of 250 ml. This mixture is held overnight at 
100.degree. C. in a closed vessel, after which time the resin is washed 
with water and titrated to pH 5.5 with HCl. By analysis it is found that 
the Al(OH).sub.3 is substantially reacted to form 
CoCl.sub.2.Al(OH).sub.3.mH.sub.2 O within the pores of the resin. 
EXAMPLE 4 
In accordance with the procedure of Example 1, but using NiCl.sub.2 instead 
of CoCl.sub.2, crystalline NiCl.sub.2.Al(OH).sub.3.mH.sub.2 O is formed. 
EXAMPLE 5 
About 105 cc of DOWEX MWA-1-OH macroporous ion exchange resin, loaded with 
4.2 moles Al/cc as crystalline bayerite, is added to the following 
solutions: 
64 gms. Ni(NO.sub.3).sub.2.7H.sub.2 O 
88 ml. 30% aq. NH.sub.4 OH 
2 ml. 50% caustic soda 
250 ml. water 
This mixture is heated overnight at 95.degree. C., after which the resin is 
washed with water. X-ray diffraction analysis shows a hexagonal, 
three-layered crystal of NiCl.sub.2.Al(OH).sub.3.mH.sub.2 O within the 
pores of the resin; the X-ray data is: 
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line: 1 2 3 4 
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d (obs): 7.80 3.95 2.70 1.75 
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EXAMPLE 6 
The CoCl.sub.2.Al(OH).sub.3.mH.sub.2 O of Example 1 is used as a cobalt ion 
getter by washing out part of the CoCl.sub.2 which "unloads" the crystal 
and then mixing the unloaded crystal with an aqueous solution containing 
soluble Co values. Thus the crystal becomes reloaded specifically with Co 
salt values, even though the aqueous solution contains other metal ions. 
The same applies to the CoCl.sub.2.Al(OH).sub.3.mH.sub.2 O of Example 3, as 
well as the NiCl.sub.2.Al(OH).sub.3.mH.sub.2 O of Examples 4 and 5, except 
that the Ni crystals of 4 and 5 are specific for getting Ni values from 
aqueous solutions.