Catalysts for oxidation of lower olefins to unsaturated...

Details Catalysts for oxidation of lower olefins to unsaturated... Catalysts for oxidation of lower olefins to unsaturated...

2001-10-19

2003-09-16

Nguyen, Cam N. (Department: 1754)

Organic compounds -- part of the class 532-570 series

Organic compounds

Oxygen containing

C568S479000, C568S480000, C502S306000, C502S307000, C502S308000, C502S309000, C502S311000, C502S312000, C502S313000, C502S314000, C502S315000, C502S316000, C502S317000, C502S322000, C502S248000, C502S249000, C502S262000

Reexamination Certificate

active

06620973

ABSTRACT:

The redox characteristic of a mixed metal oxide catalyst is a key factor in controlling the activity and oxygenation function of the catalyst. These characteristics depend on the type of metal oxide mixed and their concentration. See, “Oxidative Dehydrogenation of Lower Alkane on Vanadium Based Catalysts”, by E. Mamedov and V. Corberan, Applied Catalysis, vol. 217, pages 1-40 (1995). It would be desirable to derive a catalyst composition containing a specific combination of metal elements with suitable properties or characteristics to generate a redox characteristic catalyst having a significant impact on the selectivity and productivity of the oxygenation process. The mixed metal oxide catalysts of the present invention are prepared by an appropriate combination of the metal components, yielding a catalyst with a unique ability to selectively oxidize olefins to alpha-beta unsaturated aldehydes.
SUMMARY OF THE INVENTION
The present invention relates to the selective oxidation of hydrocarbons or olefins in the presence of molecular oxygen to form alpha-beta unsaturated aldehydes. This gas phase reaction is preferably carried out using a mixed metal oxide catalyst at temperatures in the range of 150° C. to 450° C. and at pressures of 1-50 bar. As a result, the method of the present invention achieves relatively high rates of selectivity and productivity.
The catalysts of the present invention are mixed metal oxides of the general formula
Mo
a
Pd
b
Bi
c
Fe
d
X
1
e
X
2
f
X
3
g
O
z
,
wherein:
X
1
is at least one element selected from the group consisting of Co, Ni, V, Pt, and Rh;
X
2
is at least one element selected from the group consisting of Al, Ga, Ge, Mn, Nb, Zn, Ag, P, Si, and W;
X
3
is at least one element selected from the group consisting of K, Mg, Rb, Ca, Sr, Ba, Na, and In;
a is 1;
b is 0<b<0.3, preferably 0.0000001<b<0.2;
c is 0<c<0.9, preferably 0.0001<c<0.5;
d is 0<d<0.9, preferably 0.0001<d<0.5;
e is 0<e<0.9, preferably 0.0001<e<0.5;
f is 0<f<0.9, preferably 0.0001<f<0.9;
g is 0<g<0.3, preferably 0.0000001<g<0.3; and
z is an integer representing the number of oxygen atoms required to satisfy the valency of the remaining components of the formula. The catalysts are preferably produced using the methods disclosed herein.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
One aspect of the invention relates to a catalyst for the production of alpha-beta unsaturated aldehydes from olefins and hydrocarbons. According to one embodiment, the catalyst composition has the formula:
Mo
a
Pd
b
Bi
c
Fe
d
X
1
e
X
2
f
X
3
g
O
z
,
wherein
X
1
is at least one element selected from the group consisting of Co, Ni, V, Pt, and Rh;
X
2
is at least one element selected from the group consisting of Al, Ga, Ge, Mn, Nb, Zn, Ag, P, Si, and W;
X
3
is at least one element selected from the group consisting of K, Mg, Rb, Ca, Sr, Ba, Na, and In;
a is 1;
b is 0≦b<0.3, preferably 0.0000001<b<0.2;
c is 0≦c<0.9, preferably 0.0001<c<0.5;
d is 0≦d<0.9, preferably 0.0001<d<0.5;
e is 0≦e<0.9, preferably 0.0001<e<0.5;
f is 0≦f<0.9, preferably 0.0001<f<0.9;
g is 0≦g<0.3, preferably 0.0000001<g<0.3; and
z is an integer representing the number of oxygen atoms required to satisfy the valency of the remaining components of the formula.
According to a preferred embodiment of the invention, the catalyst composition has the general formula
Mo
a
Pd
b
Bi
c
Fe
d
X
1
e
X
2
f
X
3
g
O
z
,
wherein:
X
1
is at least one element selected from the group consisting of Co, Ni, V, Pt, and Rh;
X
2
is at least one element selected from the group consisting of Al, Ga, Ge, Mn, Nb, Zn, Ag, P, Si, and W;
X
3
is at least one element selected from the group consisting of K, Mg, Rb, Ca, Sr, Ba, Na, and In;
a is 1;
b is 0<b<0.3, preferably 0.0000001<b<0.2;
c is 0<c<0.9, preferably 0.0001<c<0.5;
d is 0<d<0.9, preferably 0.0001<d<0.5;
e is 0<e<0.9, preferably 0.0001<e<0.5;
f is 0<f<0.9, preferably 0.0001<f<0.9;
g is 0<g<0.3, preferably 0.0000001<g<0.3; and
z is an integer representing the number of oxygen atoms required to satisfy the valency of the remaining components of the formula. The catalysts are preferably produced using the methods disclosed herein.
Preferably, the catalyst is prepared from a solution of soluble compounds (salts, complexes, or other compounds) of each of the metals. The solution is preferably an aqueous system having a pH of 1 to 10, and more preferably at a pH of 1 to 7, and the solution is maintained at a temperature of about 30° C. to about 100° C. Water is removed by filtration to complete dryness, at which point the catalyst is dried in an oven at 100° C. to 130° C. for about 4 to about 24 hours. The dried catalyst is calcined by heating to about 250° C. to about 600° C., about 250° C. to about 450° C., in air or oxygen for about one hour to about 16 hours to produce the desired catalyst composition.
The catalyst may be used with or without a support. If desired, suitable supports include alumina, silica, titania, zirconia, zeolites, silicon carbide, molybdenum carbide, molecular sieves, microporous materials, nonporous materials and mixtures thereof. Support material can be pretreated with acids such as HCl, HNO
3
, H
2
SO
4
, per acids or heteroploy acids of phosphorous tungstate or silicotunstate, and alkali bases such as KOH or NaOH. When used on a support, the support usually comprises from about 50 to 95% by weight of the catalyst composition, with the remainder being the catalyst composition.
Preferably, molybdenum is introduced into the solution as an ammonium salt, such as ammonium paramolybdate, or as an organic acid salt of molybdenum. such as acetates, oxalates, mandelates, and glycolates. Some other partially water soluble molybdenum compounds which may be used in the present invention include molybdenum oxides, molybdic acid, and molybdenum chlorides.
Preferably, vanadium, bismuth, iron, cobalt, aluminum, gallium, silicon, germanium, antimony, phosphorous, niobium, potassium, magnesium palladium, tungsten, manganese are introduced as salts or acids, oxides, hydrate oxides, acetates, chlorides, nitrates, oxalates, or tartrates.
The method of the present invention is suitable for oxidation of hydrocarbons and olefins to alpha-beta unsaturated aldehydes. Preferably, the feedstock includes lower branched or straight-chained alkanes or alkenes, having C
2
-C
6
carbon atoms. Further, the inventive catalyst can also be applied for the ammoxidation of C
2
-C
5
. In a preferred embodiment the starting material is propylene and acrolein is produced by the method.
The reaction mixture used in the method of the present invention is generally a gaseous mixture of 0.1 to 99 mol % olefins, such as propylene, 0.1 to 99 mol % molecular oxygen, either as pure oxygen or in the form of air, 0 to 50 mol % water, in the form of steam, and 0 to 90 mol % nitrogen or another inert gas. The gaseous mixture is generally introduced into the reaction zone at a temperature of about 150° C. to about 500° C., preferably from 250° C. to 450° C. The reaction zone generally has a pressure of from 1 to 50 bar, and preferably 1 to 30 bar. The contact time between the reaction mixture and the catalyst is preferably about 0.01 second to 100 seconds, and more preferably 0.1 second to 10 seconds, and the space hourly velocity is about 50 to about 50,000 h
−1
, preferably about 100 to about 20,000 h
−1
, and more preferably from 500 to 10,000 h
−1
.
According to one preferred embodiment, the method comprises contacting a feed mixture comprising 1-50% by volume of olefins, 0.25 to 50% by volume oxygen or a gas capable of providing oxygen, 0-50% by volume steam and 10-80% by volume inert gas at a temperature of 170 to 450° C. at a pressure of 15-500 psi at a space velocity of 500-20,000 hr−1 with the catalyst. Preferably, the method provides a conversion greater than 90%, more preferably great

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