Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND_OF THE INVENTION
Catalyst compositions similar to those of the
invention are known, see U. S. 3,567,773 which shows
catalysts containing WVMo. The present invention adds
uranium or thorium to these catalysts and obtains unexpectedly
dasirable catalysts for producing acrylic acid and methacrylic
acidO
The production of acrylic acid by the oxidation
of acrolein and the production of methacrylic acid by the
oxidation of methacrolein are known in the art. With respect
to these processes, the present invention employs the known
art process but substitutes the catalysts of the invention
for the catalysts of the artO
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SUMMARY OF rHE INVENTION
The present in~ention is a catalyst composition
consisting of oxides or oxide complexes that contains
catalytica}ly-s significant amounts of uranium~ thorium or
mixture thereof, tungsten, vanadium and molybdenum plus
optionally one or more of Co, Fe, Ni, Zn, Cu, Mg, Mn, Bi, Ti,
Zr, Sn, P, an alkali metal, an alkaline earth metal,
lanthanum or an element of the lanthanoid series. These
catalysts are especially effective for preparing acrylic
acid from acrolein and the preparation of methacrylic acid
from methacrolein. The catalysts are also highly effective
for oxidation reactions such as the oxida~ion of butadiene
to maleic anhydride and the oxidative esterification of
unsaturated aldehydes to the corresponding unsaturated
ester. The catalysts of the invention are highly reactive I
and are capable of very selectively oxidizing acrolein to ~1
acrylic acid at low temperatures~lth little or no acetic
acid production.
The invention is the catalyst compositionO
The basic invention is a catalyst containing uranium,
thorium or mixture thereof, tungsten, vanadium and molybdenum.
The other possible elements of the catalyst are optionally
included.
As noted above~ ~atalysts very slmilar to the
~li catalysts of the invention are known~ see for example
U~ S. 3~567~773. Moreo~er~ catalysts of the general type
of the catalysts are known and a person of ordinary skill
in the art needs no more than the description of the
elements in the catalyst to prepare catalysts claimed by
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the present invention. Thus, the broad description of the
invention makes the catalysts of the invention available.
Normallyg the catalysts of the invention are
prepared by mixing the catalyst ingredients in the proper
proportions in an aqueous mixture, drying the resulting
aqueous slurry and calcining the product. The ingredients
going into the preparation of the catalysts can be the
oxides, halides, nitrates or other salts of the particular
compound added. If a support is used, the material comprising
the support is usually incorporated into the catalyst along
with the other ingredients. After the catalyst ingredients
have been combined to form an aqueous slurry, the slurry
is evaporated to dryness, and the dried solid obtained is
heated in the presence of air at temperatures between about
200 and 600C. This calcination can take place outside
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of the catalytic reactor or an in situ activation could
be~tilized.
Although there are a number of preparations
that could be used to make desirable catalysts of the
invention, catalysts that contain molybdenum in a partially
reduced state below hexavalent molybdenum are preferred.
The preparation of catalysts of the invention containing
reduced molybdenum is shown in the Specific Embodiments.
The broad composition of the catalyst i5 described
above. With respect to the composition, there are certain
preferred embodiments~ Preferred are those catalysts wherein
more than about 50V/o of the atoms~ exclusive of oxygen and
any support material~ are molybdenum. Also~ wlth respect
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to the broad description, those catalysts having no optional
components or optional components of Fe7 Ni, Co, Zn, Sn,
Mn, Mg, Cu or mixture thereof are preferred.
In terms of a specific empirical formula, the
catalysts of the invention are described by the following
formula:
Aa~ 'b WC Vd Me x
wherein A is Co, Fe, Ni, Zn, Cu, Mg, Mn, si,
Ti, Zr, Sn, P, an alkali metal
an alkaline earth metal, lanthanum,
an element of the lanthanoid series
or mixture thereof; and
D is urani~n, thorium or mixture
thereof;
and wherein a is 0 to about 5;
b~ c and d are about 0.1 to about 10;
~! e is a number of about 6 to about
16; and
x is the number of oxy~gens required
to satisfy the valence requirements
of the other elements present~
Referring to the formula, preferred catalysts are designated
when A is Fe, Ni, Co, Zn, Sn, Mn, Mg, Cu or mixture thereof
and when a is greater than zero. Indlvidual optional elements
represented by A which are preferred are copper and cobalt.
In addition to the active catalytic ingredlents~
the catalysts of the invention may contaln a support material~
- Suitable support materials include silica, alumina, zirconia~
titania~ silicon carbide~ boron phosphate and the like.
A preferred support material is silica.
As noted above~ the catalysts of the invention ~-
are useful in a number of different oxidation reactions.
Preeerred emoDe the~e reactions Ls the produceion Oe
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unsaturated acids from the corresponding unsaturated aldehyde.
In such a process, acrylic acid or methacrylic acid is
produced by reacting acrolein or methacrolein with molecular
oxygen tn the presence of steam at a temperature of about
200 to about 500C. Of special interest is the preparation
of acrylic acid from acrolein because of the extremely
desirable results obtained.
The oxidation of unsaturated aldehydes to obtain
the corresponding acid is well known in the art. Basically,
the invention, with respect to the process~ is the use of
the new cataly~t within the parameters of the known art
process.
The known process in~olves the contacting of the
unsaturated aldehyde with molecular oxygen in the presence -~
of steam at a temperature of about 200 to about 500C.
The ratio of the reactants may vary widely with molar
i ratios of molecular oxygen to aldehyde of about 0.5 to
f about 5 moles normally being employed. Molecular oxygen
is most conveniently added as air. The amount of steam
may vary widely from the small amount generated in the
reaction to 20 or more moles of steam per mole of aldehyde.
In the preerred practice of the invention3 about 1 to about
10 moles of steam are added to the reactant feed.
f The reaction may be conducted in a fixed- or
I fluid-bed re3ctor using atmospheric, superatmospheric or
:f subatmospheric pressure. The apparent contact time may
i~ vary considerably with contact times of a fraction of a
second to 20 ~ecDnds of =ore nDrmally being mployed.
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5~68
Using the catalyst of the invention, very desir~ble
yields of unsaturated acid are obtained at low temperatures
with the production of little or no acetic acid.
SPECIFIC EMBODIMENTS
Comparative Example A and Examples 1-3 ~ Catalyst of invention
compared to the art.
A base catalyst of the invention was prepared and
compared to a catalyst of U. S. 3~567~773~ The catalysts
were prepared as follows: -
Comparative Example A
62% Wl 2V3Mol20 and 38~/o SiO2 This catalyst was
prepared according to Example 6 of U. S. 3~567~773
Examples 1-3
U2~1 2V3Mol20x An aqueous slurry was prepared
in 500 cc~ of distilled waterO The slurry contained 72~0 go
of MoO3~ 36 g. of V205 and 9~19 g. of tungsten metal
powder. The slurry was refluxed for two hours during which
the color of the~slurry changed to blue-black.
Separately~ 35 ~ 3 g ~ of U02(C2H302) 2 .2H20 was
dissolved in water and added to the slurry. The resulting
mixture was refluxed for one hour~ and then evaporated to
a paste material. The paste was dried in an o~ern over
night at 110C. The catalyst was ground and screened to
obtain a 10 to 30 mesh fraction.
The catalysts prepared above were placed in a
reactor conatructed of a 1.0 cm. inslde dlameter stainless
steel tube-having a reaction ~one of 20 cc. The catalyst
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of the invention was activated for two hours~under an air
flow at 400C. The reactor was fed with a mixture of
acrolein/airtsteam in the molar ratio of 1/10/6. The
temperature of the surrounding heating block and the apparent
contact time are given in Table I. The results are also
given in Table I using the following definitions:
Single pass yield = _oles of product recovered x 100
moles of acrolein fed
Conversion = moles of acrolein reacted x 130
moles of acrolein fed
Selectivit m_les of acrylic acid recovered x 100
moles of acrolein reacted :~
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In the same manner as shown by the examples above,
other catalysts of the invention containing thorium instead
of uranium or containing different amounts of uranium or
thorium and different optional elements, such as Fe, Mn,
Ni, Mg and the like, are used to produce acrylic acid.
Moreover, promoted catalysts containing various amounts
of tungsten, vanadium and molybdenum are used.
: Also using the catalysts of the invention, maleic
anhydride, methacrylic acid or acrylates are made by known
oxldation reactlons.
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