Liquid purification or separation – Processes – Ion exchange or selective sorption
Reexamination Certificate
1999-11-22
2002-04-30
Cintins, Ivars (Department: 1724)
Liquid purification or separation
Processes
Ion exchange or selective sorption
Reexamination Certificate
active
06379557
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a process of preparing and a process of using a non-pillared metal oxide triple layered perovskite, having a surface area of at least 30 m
2
/g and the empirical formula
AB
2
M
3
O
10−x
where A is a monovalent exchangeable cation, B is a divalent or trivalent cation and M is a +2, +3, +4 or +5 valent metal.
BACKGROUND OF THE INVENTION
Various metal oxides are known as catalysts for numerous chemical reactions. One family of such metal oxides are those having the general formula ABO
3
and that have the perovskite structure. Perovskites of course have been known for a number of decades and have been shown to have superconducting, ferromagnetic or ferroelectric properties. In addition to the stoichiometric perovskites, there are oxides that have structures derived from the perovskite structure. One category comprises non-stoichiometric compositions such as ABO
3−x
where the point defects are ordered in a specific manner to produce perovskite superstructures. Examples of these are Ca
2
FeAIO
5
and YBa
2
Cu
3
O
7
. The second category of perovskite-derivative structures are those that contain two-dimensional perovskite layers of composition A
n−1
B
n
O
3n+1
as one of the units building the layered structure. Another series of layered perovskites has the formula A′[A
n−1
B
n
O
3n+1
] where A′ is K, Rb or Cs. One member of this series is Cs Ca
2
Nb
3
O
10
.
The layered perovskite type oxides are interesting because of the potential to carry out chemistry between the layers. References to layered perovskite oxides include:
Chem. Mater.,
6, 907-912 (1994) which discloses an anion-deficient layered perovskite with a formula of ACa
2
Nb
3−x
M
x
O
10−x
; J. Mater. Chem.
3(7), 709-713(1993) which discloses layered oxides having a formula of A
2−x
La
2
Ti
3−x
Nb
x
O
10
; J. Phys. Chem.,
97, 1970-1973 (1993), which discloses a niobate layered perovskite having the formula AL
a
SrNb
2
M
II
O
9
.
All of the above described perovskites are prepared by solid state high temperature reaction and consequently have very low surface areas. In order for these perovskite type oxides to have greater widespread utility, it is important to synthesize layered compositions with large surface areas. There are reports of the synthesis of high surface area oxides with the pyrochlore structure. These are: U.S. Pat. No. 5,015,461 which discloses the synthesis of an oxide having the formula A
2
B
2
O
7
where A is a divalent cation and B is niobium and/or tantalum and has the pyrochlore structure and
Mat. Res. Bull.,
27, 981-988 (1992) disclosing the synthesis of calcium-niobium and tantalum oxides with the pyrochlore structure and high surface area. Finally, U.S. Pat. No. 4,980,333 discloses a layered perovskite containing interspathic polymeric oxides between the layers. These polymeric oxides prop up the layers thereby increasing its surface area.
In contrast to the above art, applicant has synthesized metal oxide triple layered perovskites having a surface area of at least 30 m
2
/g and an empirical formula of:
AB
2
M
3
O
10−x
where A is a monovalent exchangeable cation, B is at least one metal ion having a valence of +2 or +3, M is at least one metal ion having a valence of +2, +3, +4 or +5 and “x” has a value from about 0 to about 1. It is also important to note that unlike U.S. Pat. No. 4,980,333, applicant's perovskites do not contain any pillars or interspathic polymeric oxides between the layers.
SUMMARY OF THE INVENTION
As stated the present invention relates to a process for preparing triple layered perovskites and a process for using them. Accordingly one embodiment of the invention is a process for preparing metal oxide triple layered perovskite having a surface area of at least 30 m
2
/g and an empirical formula of:
AB
2
M
3
O
10−x
where A is a monovalent exchangeable cation, B is at least one metal ion having a valence of +2 or +3, M is at least one metal ion having a valence of +2, +3, +4 or +5 as defined by the equation:
M
3
=M
e
+2
+M
f
+3
+M
g
+4
+M
h
+5
where “e”, “f”, “g” and “h” are the mole fractions of M
+2
, M
+3
, M
+4
and M
+5
respectively, “e” has a value from about 0 to about 1, “f” has a value from about 0 to about 1, “g” has a value from about 0 to about 3, “h” has a value from about 0 to about 3, 3=e+f+g+h and 1≧e+f and “x” has a value from about 0 to about 1, the process comprising forming a reaction mixture containing reactive sources of “A”, “B” and “M” at a pH greater than seven, a temperature and a time sufficient to form the perovskite, the reaction mixture having a composition expressed in terms of mole ratios of oxides of
aA
2
O:bBO
y
:cMO
z
:dH
2
O
where “a” has a value of about 0.2 to about 2, “b” has a value of about 2, “y” has a value of about 1.0 to about 1.5, “c” has a value of about 3, “z” has a value of about 1.67 to about 2.5 and “d” has a value of about 10 to about 500.
Another embodiment of the invention is a process for removing contaminant ions from a stream comprising contacting the stream with a metal oxide triple layered perovskite at exchange conditions for a time sufficient to exchange the contaminant ion for an exchangeable cation on the perovskite, a surface area of at least 30 m
2
/g and an empirical formula of:
AB
2
M
3
O
10−x
where A is a monovalent exchangeable cation, B is at least one metal ion having a valence of +2 or +3, M is at least one metal ion having a valence of +2, +3, +4 or +5 and defined by the equation
M
3
=M
e
+2
+M
f
+3
+M
g
+4
+M
h
+5
where e, f, g and h are the mole fractions of M
+2
, M
+3
, M
+4
and M
+5
respectively, “e” has a value from about 0 to about 1, “f” has a value from about 0 to about 1, “g” has a value from about 0 to about 3, “h” has a value from about 0 to about 3, 3=e+f+g+h and 1≧e+f and “x” has a value from about 0 to about 1.
These and other objects and embodiments of the invention will become more apparent after the following detailed description of the invention.
REFERENCES:
patent: 4980333 (1990-12-01), Landis et al.
patent: 5015461 (1991-05-01), Jacobson et al.
patent: 5667695 (1997-09-01), Bedard et al.
J. Mater.Chem. 3(7), 709-713, Uma, S., Raju, A.R. and Gopalakrishnan, Jr.
J. Phys. Chem. 97, 1970-1973 (1993), Yoshimura, J., Ebina, J., Kondo, J. and Domen, K.
Chem. Mater., 6, 907,912 (1994) S. Uma and J. Gopalakrishnana.
Mat. Res. Bull., 27, 981-988(1992), Lewandowski, J.T. and Pickering, I.J.
Cintins Ivars
Molinaro Frank S.
Tolomei John G.
UOP LLC
LandOfFree
Process for removing contaminant cations from a stream with... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Process for removing contaminant cations from a stream with..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Process for removing contaminant cations from a stream with... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2822732