Chemistry of inorganic compounds – Oxygen or compound thereof – Metal containing
Reexamination Certificate
2000-12-22
2002-08-06
Sample, David (Department: 1755)
Chemistry of inorganic compounds
Oxygen or compound thereof
Metal containing
C423S598000, C423S600000, C423S606000, C208S134000, C208S135000, C208S136000, C502S305000, C502S311000, C502S312000, C502S317000, C502S353000, C502S354000
Reexamination Certificate
active
06428765
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to a new family of crystalline metal oxide compositions. These compositions contain tantalum, an alkali metal, at least one M metal where M is tungsten or molybdenum, optionally a M′ metal such as vanadium or niobium and optionally a M″ metal such as titanium or tin. This invention also relates to hydrocarbon conversion processes such as dehydrogenation using the composition.
BACKGROUND OF THE INVENTION
Olefins, e.g., propylene or isobutene are used to prepare a number of higher value products such as aldehydes, acids and nitrites. Since the price of the corresponding alkanes, i.e., propane or isobutane is lower than that of the olefins, it would be advantageous to be able to produce the higher value product directly from the alkanes.
Attempts have been made to synthesize novel materials to catalyze the selective oxidation of paraffins. One such catalyst is described in U.S. Pat. No. 5,750,760 where it is disclosed that a multinary composition having the empirical formula:
Mo
a
V
b
Sb
c
X
x
O
n
where X is an element such as Nb, Ta, W etc. can catalyze the oxidation of an alkane with ammonia in the presence of oxygen. Other compositions which have been disclosed in the art include a Mo
4
VO
14
phase by H. Werner et al. in
Catalysis Letters,
44 (1997) 153-63. In
J. Catalysis
52, 116-132 (1978), E. M. Thorsteinson et al., describe a mixed oxide catalyst containing molybdenum and vanadium along with another transition metal such as Ti, Nb, Ta, etc. The authors present activity data and physically characterize the compositions. MoVNb systems have also been described in
Applied Catalysis,
70 129-148 (1991) and Topics in Catalysis 3, 355-364 (1996). U.S. Pat. No. 4,524,236 discloses a composition containing molybdenum, vanadium, niobium, antimony plus at least one metal such as lithium, barium, titanium etc. U.S. Pat. No. 4,339,355 discloses a composition comprising Mo
a
V
b
Nb
c
X
d
, where X is Co, Cr, Cu, Fe, In, Mn and/or Y. It is further disclosed that the compositions have spinel or perovskite structures. In U.S. Pat. No. 4,596,787 a catalyst comprising Mo
a
V
b
Nb
c
Sb
d
X
e
is disclosed, where X includes Li, Sc, Na, Fr, Ta, etc. U.S. Pat. No. 4,250,346 discloses a catalyst with an empirical formula of Mo
a
X
b
Y
c
, where X is Cr, Mn, Nb, Ta, Ti, V and/or W and Y=Bi, Ce, Co, Cu, Fe, K, Mg, Ni, P, Pb, Sb, Si, Sn, Ti and/or U. U.S. Pat. No. 4,892,856 discloses a catalyst having the composition Mo
a
V
b
A
c
B
d
C
e
D
f
O
x
where A is tungsten or niobium, B is Fe, Cu, Bi, Cr, Sb or TI, C is an alkali or alkaline earth metal and D is Si, Al or Ti. U.S. Pat. No. 5,807,531 discloses a multimetaloxide having an empirical formula of Mo
12-a-b-c
V
a
M
1
b
M
2
c
O
x
. However, these materials have a low surface area of 17 m
2
/g or lower. Finally, Ueda et al., in
Chem. Commun.,
1999, 517-518, disclose Mo—V—M—O (M=Al, Fe, Cr and Ti) compositions which are hydrothermally synthesized, and in
Applied Catalysis: General,
2000, 135-143, disclose Mo—V—M—O (M=Al, Sb, Bi, Te) compositions which are hydrothermally synthesized. Although these compositions have a diffraction peak at about 3.9 Å, they do not have applicant's empirical formula (see below).
In contrast to these reports, applicants have synthesized a new family of crystalline oxide compositions based on tantalum, at least one of tungsten and molybdenum, and optionally another metal such as vanadium, niobium, antimony or tellurium. These novel compositions are prepared hydrothermally and are characterized in that they have an x-ray diffraction pattern with at least one peak at a d spacing of about 3.9 Å and a high surface area. These materials show good activity for dehydrogenation of hydrocarbons.
SUMMARY OF THE INVENTION
As stated, this invention relates to a new family of crystalline compositions and processes which use the compositions. Accordingly, one embodiment of the invention is a crystalline metal oxide composition having an empirical formula of:
A
n
TaM
x
M′
y
M″
m
O
p
where A is an alkali metal ion, ammonium ion or mixtures thereof, M is selected from the group consisting of molybdenum, tungsten or mixtures thereof, M′ is vanadium, antimony, tellurium, niobium and mixtures thereof and M″ is selected from the group consisting of tin, titanium, indium, gallium, aluminum, bismuth and mixtures thereof, “n” varies from about 0.1 to about 2, “x” varies from about 0.01 to about 8, “y” varies from zero to about 4, “m” varies from zero to about 0.9 and “p” has a value such that it balances the valence of the combined elements A, Ta, M, M′, M″, the composition characterized in that it has at least one x-ray diffraction peak at a d spacing of about 3.9±0.15 Å.
Yet another embodiment of the invention is a hydrocarbon conversion process comprising contacting a hydrocarbon with a catalyst at hydrocarbon conversion conditions to give a hydroconverted product, the catalyst comprises one of the compositions described above.
These and other embodiments will become clearer after a detailed description of the invention.
DETAILED DESCRIPTION OF THE INVENTION
A new family of crystalline metal oxide compositions has been synthesized and characterized. These compositions contain tantalum, at least one of tungsten and molybdenum, a third metal selected from vanadium niobium, antimony or tellurium and a fourth metal selected from tin, titanium, indium, gallium and mixtures thereof. A cation such as lithium is also present. These crystalline metal oxides are described by the empirical formula:
A
n
TaM
x
M′
y
M″
m
O
p
where “n” varies from about 0.1 to about 2. The value of “x” varies from about 0.01 to about 8, while the value of “y” varies from zero to about 4 and the value of “m” varies from zero to about 0.9. M is molybdenum, tungsten, or mixtures thereof, M′ is selected from the group consisting of vanadium, niobium, antimony, tellurium and mixtures thereof, while M″ is tin, titanium, indium, gallium, aluminum, bismuth, and mixtures thereof. Finally, A is an alkali metal cation, an ammonium cation or mixtures thereof. Examples of the alkali metals which can be used include: lithium, sodium, potassium, rubidium, cesium and mixtures thereof.
These novel crystalline metal oxide compositions are hydrothermally prepared. That is, a reaction mixture is prepared from reactive sources of the desired components along with water and heated at a temperature and for a time sufficient to form the desired product. Reactive sources of the alkali metals include the hydroxide, carbonate, halide, acetate, and sulfate compounds. Niobium reactive sources include niobium pentoxide (Nb
2
O
5
), hydrous niobium oxide, niobium ethoxide, and ammonium niobium oxalate. Molybdenum sources include molybdic acid ((NH
4
)
6
Mo
7
O
24
.4H
2
O), molybdenum trioxide (MoO
3
), sodium molybdate and molybdenum (VI) oxychloride. Tungsten sources include ammonium tungstate, tungsten (VI) oxide, tungsten (VI) chloride, sodium tungstate, and tungstic acid. Vanadium sources include vanadium (V) oxide, vanadium (V) oxychloride, vanadium oxide sulfate, and ammonium vanadate. Tantalum sources include tantalum oxide, hydrous tantalum oxide, tantalum butoxide, tantalum bromide, and tantalum chloride. Tellurium sources include ammonium tellurium oxide, telluric acid, and tellurium oxide. Tin, indium, gallium, aluminum, and bismuth sources include the nitrates and chlorides, while titanium sources include titanium alkoxides, (NH
4
)
2
Ti(OH)
2
(C
3
H
4
O
3
)
2
and TiCl
3
. It should be pointed out that this list is only by way of examples and other reactive sources of individual elements may also be used.
Using the above described reactive sources, a reaction mixture is formed which in terms of molar ratios of the oxides is expressed by the formula:
aA
2
O:TaO
5/2
:bMO
3
:cM′O
5/2
:dM″O
q/2
:eH
2
O
where “a” has a value from about 0.75 to about 4, “b” has a value of about 0.02 to about 10, “c” has a val
Bedard Robert L.
Bogdan Paula L.
King Lisa M.
Koster Susan C.
Molinaro Frank S.
Sample David
Tolomei John G.
UOP LLC
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