Organic compounds -- part of the class 532-570 series – Organic compounds – Oxygen containing
Reexamination Certificate
1998-12-04
2001-06-26
Padmanabhan, Sreeni (Department: 1621)
Organic compounds -- part of the class 532-570 series
Organic compounds
Oxygen containing
C568S469900, C562S532000, C562S535000, C562S549000, C502S244000, C502S312000
Reexamination Certificate
active
06252122
ABSTRACT:
The present invention relates to a novel process for the industrial heterogeneously catalyzed gas-phase oxidation of propane to acrolein in an oxidation reactor which is fed with a gas mixture comprising, apart from propane and molecular oxygen as oxidant, at most one diluent gas which is essentially inert under the conditions of the heterogeneously catalyzed gas-phase oxidation.
Acrolein is an important intermediate, for example for the preparation of glutaraldehyde, methionine, folic acid and acrylic acid.
It has long been known that acrolein can be produced industrially by heterogeneously catalyzed gas-phase oxidation of propylene with molecular oxygen over catalysts present in the solid state (cf., for example, DE-A 19 62 431, DE-A 29 43 707, DE-C 1 205 502, EP-A 257 565, EP-A 253 409, U.S. Pat. No. 2,941,007 etc.).
A disadvantage of this procedure is that propylene is a relatively expensive starting material.
EP-A 117 146 discloses the production of acrolein from propane by first partially dehydrogenating propane in the absence of oxygen over suitable catalysts and subsequently converting the propylene present in the resulting product mixture, without prior separation, into acrolein by the abovementioned heterogeneously catalyzed gas-phase oxidation. A disadvantage of this procedure is the necessity for a separate dehydrogenation stage.
It is now generally known that acrolein can be produced directly by heterogeneously catalyzed gas-phase oxidation of propane with molecular oxygen (cf., for example, U.S. Pat. No. 4,472,314; Wm. Curtis Conner Jr. und Stuart Soled, “Propane Oxidation over Mixed Metal Oxides”, pp. 1224-38 in Stud. Surf. Sci. Catal., 7 (1981); U.S. Pat. No. 4,302,610; J. Barrault and L. Magaud, “Selective oxidation of propane in the presence of bismuth-based catalysts”, pp. 305-14 in Stud. Surf. Sci. Catal. 81 (1994); Ikuya Matsuura and Naomasa Kimura, “Oxidation and ammoxidation of propane over tetragonal type M
5+
OPO
4
catalysts”, pp. 271-79 in Stud. Surf. Sci. Catal. 82 45 (1994); Wu Tong-Hao et.al. in Journal of Natural Gas Chemistry, 1 (1994) pp. 53-60; JP-A 6-199 731; Kim, Y. C. et al., Applied Catalysis, 70 (1991), pp. 175-87; Kim, Y. C. et al., Chemistry Letters, 4 (1989) pp. 531-34; JP-A-2-83348; Takita Y. et al., Chemistry Letters, 10 (1989) pp. 1733-36; Kim, Y. C. et al., J. Chem. Soc., Chem. Commun. (1989) pp. 652-53; Kim, Y. C. et al., Catalytic Science and Technology, Vol. 1, Kodanska Ltd. (1991) pp. 439-40; Takita Y. et al., Catalysis Today, 13 (1992) pp. 673-78; Y. Moro-oka, Stud. Surf. Sci. Catal. 75c (1993) pp. 1983-86; U.S. Pat. No. 4,260,822, GB-1340891 and U.S. Pat. No. 3,293,290). The catalysts to be used for this purpose are oxide compositions present in the solid state. The catalytically active oxide composition can contain, in addition to oxygen, only one other element or more than one other element (multimetal oxide compositions). Catalytically active oxide compositions are particularly frequently ones comprising more than one metallic element, in particular transition metal. These multielement oxide compositions are usually not simple physical mixtures of oxides of the elemental constituents, but heterogeneous mixtures of complex polycompounds of these elements.
Catalysts which have been found to be particularly suitable for the gas-phase catalytic oxidation of propane to acrolein are multimetal oxide compositions of the general formula I
MO
a
Bi
b
P
c
X
1
d
X
2
e
X
3
f
X
4
g
O
h
(I),
where
X
1
=
V
,
Nb
,
Ta
,
Cr
,
W
,
Ga
,
Ce
and
/
or
La
,
X
2
=
Li
,
Na
,
K
,
Rb
,
Cs
,
Cu
,
Ag
,
Au
,
Pd
and
/
or
Pt
,
X
3
=
Sn
,
Pb
,
Sb
,
Bi
,
Te
,
Fe
,
Co
and
/
or
Ni
,
X
4
=
Si
,
Al
,
Ti
and
/
or
Zr
,
a
=
0
-
2
,
d
=
0
-
2
,
}
with
the
proviso
that
the
sum
of
a
and
d
is
at
least
0.20
;
b
=
0
-
1.5
,
c
=
0
-
10
,
}
with
the
proviso
that
the
sum
of
b
and
c
is
at
least
0.1
;
e
=
0
-
0.5
,
f
=
0
-
0.5
,
g
=
0
-
20
and
h
=
a
number
different
from
zero
which
is
determined
by
the
valence
and
frequency
of
the
elements
different
from
oxygen
in
I
.
Owing to the fact that propane reacts more sluggishly than does propylene, the heterogeneously catalyzed gas-phase oxidation of propane to acrolein is carried out at a comparatively high temperature, typically at from 350 to 650° C. Since the gas-phase partial oxidation of the propane proceeds exothermically, it is advantageous to carry it out industrially in, for example, fluidized catalyst bed reactors or in multitube fixed-bed reactors in which a heat transfer medium (eg. salt bath or metal melt) is passed through the space surrounding the tubes. The working pressure (absolute pressure) in this industrial heterogeneously catalyzed gas-phase partial oxidation of propane can be below 1 atm, at 1 atm or above 1 atm. It is generally from 1 to 2 atm, but can 10 also be up to 10 atm. The target reaction occurs during the residence time of the reaction mixture in the catalyst charge through which it is passed.
In the industrial heterogeneously catalyzed gas-phase partial oxidation of propane with molecular oxygen there is particular interest, on the one hand, in a high space-time yield of the desired target compound acrolein. Owing to the fact that propane reacts more sluggishly than does propylene, it has therefore often been recommended in the prior art that the gas-phase catalytic partial oxidation of propane, unlike the gas-phase catalytic partial oxidation of propylene, be carried out using a reaction gas starting mixture containing an excess of propane over the other reactant, the molecular oxygen. On the other hand, this partial oxidation of propane has a pronounced exothermic character because of which it is recommended in the prior art, in respect of the industrial gas-phase catalytic oxidative reaction of propane to give acrolein, that either an upper limit be placed on the proportion by volume of propane in the reaction gas starting mixture or the reactants be diluted with a gas which is essentially inert under the conditions of the gas-phase catalytic partial oxidation of propane. A diluent gas which is essentially inert under the conditions of the heterogeneously catalyzed gas-phase partial oxidation is normally considered to be a diluent gas whose constituents remain unaltered, taking each constituent individually, to the extent of at least 97 mol % under the conditions of the heterogeneously catalyzed gas-phase partial oxidation. Examples of such inert diluent gases recommended in the prior art for the industrial gas-phase catalytic partial oxidation of propane are N
2
, CO
2
, CO, noble gases and water vapor. A particularly important advantageous effect of the concomitant use of an inert diluent gas is seen in the prior art as being that, at a prescribed oxygen to propane ratio, the addition of an inert diluent gas reduces the explosive tendency of the gas mixture, ie. the addition of an inert diluent gas increases the energy input required for a self-prop
Proll Theo
Schildberg Hans-Peter
Tenten Andreas
BASF - Aktiengesellschaft
Oblon, Spivak, McClelland, Maier & Neustadt PC
Padmanabhan Sreeni
LandOfFree
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