Note: Descriptions are shown in the official language in which they were submitted.
~ ~ 7 ~ 5
CRYSTALLINE LITHIUM ALUMINATES
It is known, e.g., from U.S. Patents 4,116,858
(Lee and Bauman, September 26, 1978) and 4,154,311 (Lee
and Bauman, June 26, 1979) that an ion-exchange resin may
be saturated with aqueous AlCl3 solution and that reaction
with NH40H converts the AlCl3 in situ to Al(OH)3. This
so-formed amorphous Al(OH)3 is then reacted with LiX,
where X is halide, at elevated temperature to form crys-
talline LiX-2Al(OH)3 which is useful in selectively recov-
ering Li+ values from aqueous solutions, e.g., Li-contain-
ing brines.
It is also known, e.g., from U.S. Patents
4,116,856 (Lee and Bauman, September 26, 1978) and
4,221,767 (Lee and Bauman, September 9, 1980) that
improvments in the above discussed formation o crys-
talline LiX-2Al(OH)3 are found by reacting amorphous
Al(OH)3 or crystalline hydrous alumina (e.g., nordstran-
dite, bayerite, gibbsite or mixtures of these) with LioH
; to form LiOH-2Al(OH)3 which is then reacted with LiX to
form the crystalline LiX-2Al(OH)3, where X is halide.
L~J
29,261-F -1-
.
I ~ 7~S4~
Various forms of alumina, Al2O3, are known,
some of which occur as natural minerals, some of which
are hydrated and some of which are crystalline. The
Handbook of Chemistry shows the following:
Crystalline
Name Form M.P.C
aluminum oxide, Al2O3 hex. col. 2050
~~Al2O3, corundum trig;col.cr,n 2015
y-Al2O3, r-alumina wh.micro.cr.,n tr.to alpha
Al2O3 3H2O, gibbsite, monocl.,wh.cr. tr.to
(hydrargillite) A12O3 H20
(Boehmite)
Al2O3 3H2O, bayerite wh.micro.cr. tr.to
Al23 H20
(Boehmite)
aluminum oxide, amor.wh.pwd. -xH2O,tr.to
A123 XH2 y-Al2o3
Nordstrandite is a crystalline hydrous alumina,
as are gibbsite and bayerite.
The present process differs from the above
previous lithium aluminate preparations in that AlCl3
is used only once, to provide amorphous Al(OH)3 in a
substrate such as a macroporous ion-exchange resin.
Further loading of ~l into the substrate pores is accom-
plished by crystallizing the alumina in the pores and
growing the crystals in an alkaline aluminate solution.
The present invention is a process for growing
crystalline hydrous alumina within the pores of a porous
~:
29,261-F -2-
,
,
~ ~ 7 ~
substrate, characterized by providing a seed of crystal-
line hydrous alumina in said pores by the ln situ precipi-
tation of a water-soluble aluminum compound, thereby form-
ing amorphous hydrous alumina; converting the so-formed
amorphous hydrous alumina to crystalline hydrous alumina by
heating; and adding to the seed-bearing substrate an aqueous
solution of an alkaline aluminate, thereby providing alumi-
num oxide values which grow additional quantities of crys-
talline hydrous alumina on the crystalline hydrous alumina
seeds.
The so-formed crystalline hydrous alumina may
then be converted to LiX-2Al(OH)3 nH20 by reaction with a
lithium salt, where X is an anion or negative valence salt
radical. Depending on the type of crystalline hydrous
alumina formed, the crystalline unit cells may be of the
2-layer or 3-layer variety.
A~ used herein, the expressions "2-layer" and
"3-layer" refer to the number of layers bounded on both
sides by the aluminate layers into which the subject Li
compounds are intercalated. The following graphic illus-
trations will aid in describing the 2-layer and 3-layer
systems:
2-layer 3-layer
_ Li salt ~ Li salt
C
o nAl(OHj~ C nAl(OH~
Ll salt o Ll salt
~ , ~ i _ =~
29,261-F -3-
~ ~7~5
It will be realized that the crystals of
lithium aluminates are normally present as aggregates
or stacks of a plurality of unit cells rather than each
unit cell standing as a separate physical entity.
2-Layer LiX 2Al(OH)3 nH20 is formed from
gibbsite and a lithium salt (LiX) other than LioH~ The
lithium salt concentration must be high (at least about
12-15 percent of LiCl, for example) and the temperature
must be high, preferably close to the boiling point of
the LiX solution. LioH tends to solubiliz.e the gibbsite
and when it reprecipitates it forms 3-layer unit cells.
3-Layer LiX-2Al(OH)3-nH2O is formed from hydrous
alumina and LioH whi~h forms crystalline LiOH 2Al(OH)3 nH2O,
which can then be neutralized with an acid to form crystal-
line LiX 2Al(OH)3 nH2O, where X is the anion of the acidor of the lithium salt.
The porous substrate into which the crystal-
line hydrous alumina is loaded may be an inert material,
such as an inorganic or organic material. For certain
uses and reasons, the substrate is preferably a macro-
porous resin such as an ion-exchange resin as taught in
U.S. Patents 4,116,858 and 4,116,856, both previously
identified. Examples of the macroporous resins that
can be employed are the strong acid and weak base types
of macroporous resins.
once the substrate is loaded to satisfaction
with the crystalline hydrous alumina, the composite is
then ready for reaction with LiX, where X is a monova-
lent anion, such as OH , Cl , Br , I , RCOO or OCl , or
29,261-F -4-
i ~ 796~ ~
may be divalent or trivalent, such as SO4 , PO4 or
R(C00)2
The alkaline aluminate solution, e.g.,
NaAlO2-xNaOH, may be prepared, e.g., by dissolving com-
mercial grade sodium aluminate, NaAlO2, in water or maybe prepared, e.g., by reacting Al(OH)3 with concentrated
NaOH. Commercially available solutions of sodium alumi-
nate can be used. When reacting crystalline Al(OH)3 with
concentrated NaOH it is preferred that the NaOH be of 50
percent concentration or higher, at a temperature at
which the NaOH is a li~uid. After the NaAlO2xNaOH is
prepared, it is diluted during its use in the present
invention. When preparing the aluminate solution, it is
also preferred that there be about 1.0 to 1.5 mole of
NaOH per mole of Al(OH)3, since too much caustic tends
to solubilize the crystalline hydrous alumina seed which
is provided in the porous substrate to serve as precipi-
tation sites for additional growth of crystalline hydrous
alumina. The alkaline material may be KOH, but it is more
costly.
In preparing a porous substrate having "seeds"
of crystalline Al(OH)3 within the small pores, it is not
generally possible or practical to insert appreciable
amounts of non-soluble crystals into the pores. There-
fore, the seeds are best implanted by providing aluminumsolution in the pores and then precipitating hydrous alu-
mina ln situ within the pores. To accomplish this one
may use a soluble Al salt, e.g., AlC13, and then alkalize
the A1 to insoluble Al(OH)3. This freshly formed Al(OH)3,
being amorphous, is then treated in one of various ways
to cause the Al(OH)3 to crystallize.
29,261-F -5-
6 4 ~
When the substrate is a weak base anion-
-exchange resin in its basic form, the preferred proce-
dure for incorporating Al(OH)3 seeds therein is to add
an a~ueous solution of AlC13 to where the amount of Cl
is about e~uivalent to the base capacity. After about
1 hour at room temperature (or somewhat shorter times
if the mixture is warmed to not more than about 60C),
most, if not all, of the Al values have been converted
to Al(OH)3. This is followed by washing out excess
AlCl3, titrating to the resin-OH capacity with NaOH and
washing again to substantially remove remaining chlorides.
When the substrate is any other porous struc-
ture (other exchange resins, polymers or inorganic inert
materials), it is recommended that the seeds be implanted
lS within the pores by using soluble Al (such as AlCl3) which
is precipitated ln situ using NH40H to form Al(OH)3 in the
pores. Excess AlCl3, or Al(OH)3 formed outside the pores,
is easily washed away.
once the seed of Al(OH)3 is implanted in the
pores of the substrate it may be conveniently crystallized
as nordstrandite, bayerite or gibbsite, e.g., as follows:
1. To obtain nordstrandite use a soluble amine,
e.g., ethylenediamine (about 20 percent concentration) at
about 50C overnight, then wash out the amine.
2. To obtain bayerite use NH3 (about 1-30
percent in H20) at reflux temperature for 1-16 hours or
more, then wash out excess NH40H.
29,261-F -6-
~ ~ 7~645
.
3. To obtain gibbsite use aqueous NaOH in an
amount of about 0.1-0.5 mole of NaOH per mole of Al(OH)3,
boil for about 0.5 hour or more, and wash with H2O. Sodi-
um aluminate may be used instead of the NaOH.
Any of the above-described seeds of crystal-
line Al(OH)3 may be used as growth sites for producing
additional crystalline Al(OH)3 by treatment with alka-
line aluminate solution. If this additional treatment
is done at less than about 50C, the newly-precipitated
crystalline Al(OH)3 is principally nordstrandite and/or
bayerite; if done at greater than about 50C it is prin-
cipally gibbsite. There is a tendency for the seed crys-
tal to promote formation of additional Al(OH)3 having the
same crystal structure as the seed.
The NaAlO2 xNaOH, once formed, and having a
NaOH/Al(OH)3 ratio generally in the range of about l.O-
-1.5, is then preferably used as a diluted aqueous solu-
tion of about 5-30 percent concentration by weight as
the precursor for the additional Al(OH)3 growth on the
seed. The NaAlO2 xNaOH solution is mixed with the seed-
-containing porous substrate. As the aluminum oxide in
the sodium aluminate becomes crystallized to Al(OH)3,
the pH increases. Addition of more amorphous aluminum
hydroxide lowers the pH by reforming additional sodium
aluminate and solubilizes the amorphous alumina which
then crystallizes out of the sodium aluminate and pro-
duces further growth of the seeded crystalline Al(OH)3
which is, again, indicated by a rise in the pH. The
step of adding NaAlO2 xNaOH, or of adding amorphous alu-
mina to reform NaAlO2 xNaOH, may be repeated one or more
29,261-F -7-
~ 3 ~'~6~ `
times until the relative speed of pH change is slowed,
indicating that the pores are substantially filled with
crystalline Al(OH)3 and any additional formation of crys-
talline Al(OH)3 is likely to take place outside the pores.
If additional pre-formed NaAlO2 xNaOH is added as a source
of additional crystalline Al(OH)3, it should be preceded
by an amount of acid (preferably HCl) to neutralize the
caustic already present from a previous addition of sodium
aluminate. This prevents the caustic from building to a
concentration which would resolubilize the desired crys-
talline Al(OH)3.
Another technique for causing additional pre-
cipitation of hydrous alumina onto the seed, is to add
the alkaline aluminate in an amount sufficient to supply
all, or even an excess, of the aluminate values expected
to be precipitated. Then by slow or incremental addition
of an acid, e.g., HCl, the alkaline metal is converted to
alkali metal salt (e.g., NaCl), thus decreasing the ratio
of alkali metal hydroxide in the alkaline aluminate,
thereby causing precipitation of the aluminate and caus-
ing the seed to add to this additional aluminate.
It can be seen, then, that by reacting amor-
phous aluminum hydroxide to form sodium aluminate, the
amorphous aluminum hydroxide is solubilized. The solu-
bilized amorphous aluminum hydroxide, in the presenceof the crystalline Al(OH)3 seed, precipitates out as
crystalline Al(OH)3 and the seed increases in size.
The reaction of LiX (i.e., a lithium salt or
lithium compound) with the crystalline hydrous alumina
is performed using an aqueous solution of the LiX and
29,261-F -8-
~ ~ . 364 ~ `
employing, preferably, an elevated temperature. It is
best if the LiX is a concentrated solution and the tem-
perature is at or near the boiling point. Weak solutions
of LiX and/or lower temperatures of reaction are less
effective in obtaining a high degree of the desired inter-
calation in a reasonable length of time.
The term "intercalation" is used to indicate
that the reaction of the LiX with the crystalline hydrous
alumina hydroxide creates LiX 2Al(OH)3 nH2O crystals
wherein the LiX moiety lies between layers of the hydrous
alumina hydroxide and causes an expansion of the hydrous
alumina crystal lattice. The LiX can be substantially
leached out, but so long as a significant percentage of
it remains, e.g., about 50 percent of the possible amount,
the crystal lattice remains expanded and the amount of
intercalated LiX can be replenished until the lattice is
again loaded with LiX.
The advantages of the present method and of
using NaAlO2 xNaOH as the source of hydrous alumina to
build crystalline Al(OH)3 in the substrate are:
1. crystalline Al(OH)3 (such as gibbsite,
bayerite, nordstrandite and mixtures of these) can, by
being combined with NaOH, be used and the substrate sub-
stantially loaded with the crystalline material, using
fewer steps than are shown in U.S. Patents 4,116,856
and 4,116,858 (both previously identified);
c
2. because it is not necessary to dry the
substrate ~such as an ion-exchange resin) after the first
29,261-F -9_
i ~ 7~S
loading step, osmotic shock is substantially decreased
and substrate breakage or decrepitation is substantially
avoided;
i 3. because the composite is neutralized
only once, aluminum loss due to neutralization problems
is minimized;
4. one may selectively prepare 2-layer lith-
ium aluminates or 3-layer lithium aluminates; and
5. having the hydrous alumina present in the
porous substrate as crystalline Al(OH)3 rather than amor-
phous Al(OH)3 is beneficial in providing optimum loading
of LiX, thereby forming crystalline Li~-2Al(OH)3 nH20 in
a more consistent and expeditious manner.
Example 1
(a) Lithium Aluminate from Gibbsite
A macroporous strong acid ion-exchange resin
(525 ml) containing 10 percent divinylbenzene is stirred
into an equal volume of 29 percent aqueous AlCl3 solution.
The resin is filtered so that the excess AlCl3 solution
is removed from the resin. The resin is dried to free-
-flowing resin with dry N2 and then stirred into 600 ml
of aqueous 30 percent NH3 solution. The mixture is
washed. The resin is contacted with an ex`cess of brine
to convert RSO3NH4 to RSO3Na and then filtered to remove
all of the solution from the beads. The resin is then
added to 456 g of H2O and 230 g of NaAlO2 ~NaOH solution
29,261-F -10-
4~
(from gibbsite and 50 percent NaOH). The mixture is
stirred and heated to 75C-80C for one hour. The tem-
perature is reduced to 70C and five 25-g additions of
amorphous Al~OH)3 are added at 10-minute intervals.
After the last addition, the heat and stirrer are turned
off and the resin mixture is allowed to set overnight.
The final aluminum content of the washed resin is approx-
imately 3.92 mmoles of Al/ml of resin. X-ray diffraction
analysis shows very crystalline gibbsite is present in
the resin.
(b) Conversion to 2-Layer Lithium Aluminate
The resin is refluxed in 30 percent aqueous
LiCl solution for at least 4 hours. The resin now con-
tains 2-layer LiCl 2Al(OH)3 nH2O.
(c) Preparation of 3-Layer LiCl 2Al(OH)3 nH O in a
porous substrate via gibbsite 2
The same resin employed in (a) (110 ml) and
containing gibbsite, prepared as described above, is
heated with 110 ml of an aqueous solution containing
8.31 g of LiCl and 3.52 g of LioH-H2o. The resulting
slurry is stirred at a temperature of 75C. lN NaOH
(75 ml) are added and the resin is heated for another
~ hour. The resin is placed in a 95C oven for 12 hours.
; X-ray analyses of samples taken periodically show a
decrease in the amount of gibbsite with a corresponding
increase in the amount of LiCl-2Al(OH)3 nH2O.
29,261-F -11-
~ ~ J 36~5
The resin is then washed and neutralized with
HCl in a solution containing NH4Cl and LiCl. Neutraliza-
tion to a pH of 5.6 (at room temperature) requires about
220 milliequivalents of HCl. The LiCl LioH gibbsite reac-
tion will also take place at 25C.
(d)
The same resin employed in (a) and (c) above
(225 ml) and containing gibbsite (3.7 mmoles of Al/ml of
resin) is placed in a stainless steel beaker with 275 ml
of H2O and 35 g of LioH-H2o and the mixture heated to
80C. X-ray analysis shows that all of the gibbsite is
converted to 3-layer LiOH-2Al(OH)3-nH20 in about 30 min-
utes. The resin is neutrali~ed with HCl. This reaction
also occurs at room temperature but at a much slower
rate.
Example 2
(a) Preparation of 3-Layer LiCl-2Al(OH)3-nH2O in
a Porous Substrate via Bayerite
A macroporous weak base ion-exchange resin
;20 (500 ml) in the chloride form is poured into an equal vol-
ume of saturated aqueous AlCl3 solution. The slurry is
; stirred without heating for 40 minutes. The resin is fil-
tered by suction until all of the excess AlC13 solution
is removed from the resin and the resin is stirred into
500 ml of 30 percent NH3 in H20 at room temperature. An
exotherm from 25C to 30C is observed. The resin is
stirred for a total of 20 minutes. The ammonia solution
is poured off of the resin and the resin is allowed to
set for 16 hours at room temperature. X-ray analysis of
29, 261-F -12-
) 6 ~ ~
the resin shows that bayerite has formed in the resin.
There is still a large amount of amorphous Al(OH)3 pres-
ent. Aluminum analysis indicates that the resin contains
0.7 mmoIe of Al/ml of resin at this point.
The resin is washed thoroughly so that the
filtrate is clear. Even a small amount of crystalline
Al(OH)3 in the solution phase cannot be tolerated.
The resin and 230 ml of deionized water are
stirred and heated to 45C and 173 g of freshly prepared
NaAlO2 xNaOH is added to the slurry. This mixture is
reacted for 1 hour. From x-ray data it can be seen that
the amorphous Al(OH)3 content of the resin is decreased.
Four 216-g additions of amorphous Al(OH~3
are added at 15-minute intervals. After the last addi-
tion, the resin is allowed to stand for 16 hours. X-ray
analysis of the product shows only well crystallized
bayerite.
(b)
The resin described above (210 ml) is neutra-
lized with 240 milliequivalents of HCl. The resin is
then heated at 110C-115C in 250 ml of 30 percent LiCl
solution for 1.5 to 3 hours. Very crystalline 3-layer
LiCl 2Al(OH)3 nH2O is the product. No further neutrali-
zation is necessary.
~ayerite in porous resin can also be converted
to 3-layer lithium aluminate by reaction with LioH or a
mixture of LiCl and LioH.
29,261-F -13-
3 ~ ,'()6~S
Example 3 - Growth of Nordstrandite in a Porous Sub-
strate
The same resin employed in Example 2 (500
ml) is poured into an equal volume of aqueous 25 percent
AlC13 solution and the mixture is stirred for 30-40 min-
utes. The resin is then filtered to remove the excess
AlC13 and stirred into 30 percent NH40H solution. The
resin is stirred for 30 minutes and washed thoroughly
with H20. The resin is successively treated with NH40H
and H20 until substantially all of the Cl is removed.
The resin is washed with deionized water to remove all
traces of NH40H.
The resin is then placed in a polyethylene
bottle with an egual volume of 12 percent ethylenedia-
mine and heated at 50C for 16 hours. X-ray shows the
presence of nordstrandite.
The resin is then contacted with an e~ual vol-
ume of deionized water and 230 g of fresh NaA102-~NaOH for
one hour. Five 25-g additions of amorphous Al(OH)3 are
then added at 15-minute intervals. The resulting product
is nordstrandite in the pores of the resin.
Exam~le 4 - The Modified Method for High Loading of
Crystalline Hydrous Alumina
To 3000 ml of the same resin employed in Exam-
ples 2 and 3 except that it was in the OH' form, was addedwater to a total of 3750 ml was stirred as 147 g of anhy-
drous AlC13 were added. Stirring was continued for one
29,261-F -14-
7 ~ 6 ~ 5
hour as the pH slowly rose to 5. The slurry was ~ell
washed with deionized water until the effluent was almost
colorless. The washed resin was reslurried with 40 ml of
30 percent NH3 and 155 ml of 50 percent NaOH to a pH of
10.5. The resin was then washed on a filter.
A sample of 197 ml of the resin so prepared was
slurried in H2O with 5.22 g of NaAlO2 nNaOH (NaAlO2 xNaOH
is a solution of sodium aluminate made by dissolving 1960 g
of gibbsite in 2100 ml of 50 percent NaOH at 100C). The
final volume of resin was 192 ml.
The resin was transferred to a one-liter
beaker and 299 g of NaAlO2 xNaOH was added plus water
to a total volume of 540 ml. By means of a pump, 36
percent HCl was metered into the stirred slurry at a
rate of 1 ml/minute. The temperature rose to a maximum
of 40C and it was maintained at 30C-40C during the
course of the HCl addition. The pH decreased from 14
to 12.8. The pump was controlled by the pH, and near
the end of the HCl addition, was essentially in an on-off
mode as the pH fluctuated. After 164 ml of 35 percent
HCl had been added the slurry was well washed to yield
230 ml of resin which contained 4.63 mmoles of Al/cc of
resin. The Al was present as bayerite as determined by
x-ray.
Example 5
The same resin employed in Examples 2 and 3
(200 ml) was treated at room temperature with a large
excess of aqueous 25.5 percent AlCl3. The resin is
sucked dry on a filter funnel and dumped into 200 ml of
29,261-F -15-
~ 5
30 percent aqueous ammonia and stirred for 15 minutes.
The resin is rinsed briefly with water and allowed to
stand overnight at room temperature. It was titrated
to stable 10.1 pH with 74 ml of N/1 NaOH. The resin
was then washed until chloride free to give a settled
volume of 166 ml and was added to water to a total vol-
ume of 260 ml. A sodium aluminate solution (4.4 g)
(1960 g of gibbsite dissolved in 2100 ml of 50 percent
NaOH at 100C) was added. After one hour of stirring
at room temperature an additional 70 g of sodium alumi-
nate solution was added. After an additional 45 minutes
of stirring at 30C-35C, the pH had risen to 13.6. Dur-
ing the next hour four equal additions of amorphous
Al(OH)3 (100 g ~ 1 mole Al) of 9 g each were made. The
pH held at 13.5-13.6. The supernatant solution was fil-
tered and returned to the resin pot with a pH increase
to 13.9. Two more 9-g additions of amorphous Al(OH)3
were made during the next hour and then two more 9-g
additions in the next 45 minutes. The washed resin,
with a settled volume of 203 ml, showed an aluminum
content of 4.5 mmoles/ml.
29,261-F -16-
