Chemistry of hydrocarbon compounds – Unsaturated compound synthesis – By dehydrogenation
Reexamination Certificate
1999-09-17
2001-07-10
Johnson, Jerry D. (Department: 1764)
Chemistry of hydrocarbon compounds
Unsaturated compound synthesis
By dehydrogenation
C585S328000, C585S658000, C562S547000, C562S548000, C562S549000, C560S245000
Reexamination Certificate
active
06258992
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
This invention relates to processes for low temperature catalytic oxidation of lower hydrocarbon feed to carboxylic acids and dehydrogenated product, particularly the conversion of ethane/ethylene to acetic acid or direct oxidation of ethane to vinyl acetate monomer over mixed metal oxide catalysts. The feed includes sulfur containing compound capable of producing oxides of sulfur. The process achieves a high yield of partial oxidation products.
2. Description of the Related Art
Numerous processes are known for catalytic oxidation of ethane to oxygenated or oxy-dehydrogenated products. For example, U.S. Pat. No. 3,970,697, European Patent 627,401, European Patent Application 480,594 and International Application WO 99/13980 describe catalysts and processes for the production of acetic acid from ethane and ethylene. U.S. Pat. Nos. 4,250,346, 4,524,236, 4,568,790, 4,596,787 and 4,899,003 describe catalysts and processes for oxydehydrogenation of ethane to ethylene. U.S. Pat. Nos. 4,370,492, 5,185,308, 4,902,823.and International Application WO 98/05620 describe catalysts and processes for the production of vinyl acetate from ethylene, acetic acid and oxygen. U.S. Pat. No. 4,339,355 describes catalysts and processes for the production of acrylic acid from acrolein. U.S. Pat. No. 4,148,757 describes catalysts for the ammoxidation of olefins to acrylonitrile and for the oxidation of olefins to acrolein and acrylic acid. In order to increase activity and product selectivity , most of the catalytic systems described in these disclosures include the addition of promoting metals to the catalysts rather than any process gas or co-feed as a promoter.
Oxidative dehydrogenation is a well known process for converting saturated or partially saturated organic compounds to corresponding compounds containing a greater degree of unsaturation. Yields of the reaction products are related to the type of the catalyst system and to the process conditions. Oxidative dehydrogenation processes utilizing sulfur oxide are described in U.S. Pat. Nos. 4,188,490 and 3,970,697. The catalysts used in the processes of U.S. Pat. Nos. 4,188,490 and 3,970,697 include palladium and gold on supports such as zinc oxide, alumina and silica; the catalyst is pre-treated with sulfur compound in moist air so that the concentration of sulfur-containing modifier is from about 0.05% to about 25% of the pre-treated, zinc oxide supported pallladium and gold catalyst composition.
In U.S. Pat. Nos. 2,867,677, 2,423,418 and 2,720,550, sulfur dioxide is added in alkane dehydrogenation reactions which are run at very high temperatures above 400° C. to 700° C. where total oxidation products become dominant. Consequently, the yields of the desired product are rather low. Moreover, organic sulfide compounds formed as by products are adsorbed on the surface of the catalysts and hinder the overall reaction.
Accordingly, it would be desirable to provide a low temperature method which can have a significant impact on the productivity of the required products without effecting the integrity of the mixed metal oxide catalysts.
OBJECTS OF THE INVENTION
It is an object of the invention to overcome the above-identified deficiencies.
It is another object of the invention to provide a low temperature catalytic method yielding high productivity of oxygenated product.
It is another object of the invention to provide a low temperature catalytic method yielding high productivity of dehydrogenated products.
It is a further object of the invention to provide an improved catalytic method for the oxidation of lower alkanes to corresponding acids and aldehydes.
It is a further object of the invention to provide an improved catalytic method for the oxidation of alkanes to produce corresponding carboxylic acids , aldehydes and dehydrogenated products, using sulfur-containing compounds having at least two oxygens as promoters.
It is another object of the invention to produce vinyl acetate monomer (VAM) directly through ethane oxidation using sulfur containing compounds as a promoters in the presence of mixed metal oxide catalyst at particular process conditions.
Other objects as well as aspects, features and advantages of the present invention will become apparent from a study of the present specification, including the claims and specific examples.
SUMMARY OF THE INVENTION
The process of the present invention is a low temperature catalytic process for the production of oxygenated/oxydehydrogenated products by vapor phase oxidation of lower hydrocarbons using a small amount of sulfur-containing compounds such as hydrogen sulfide, sulfur dioxide or carbonyl sulfide in the feed. The process is carried out in the presence of multi-component, mixed metal redox catalysts. The invention using sulfur compounds in the feed can also be utilized in oxidation/ammoxidation of propane/propylene and direct production of vinyl acetate monomer from the conversion of ethane to ethylene followed by oxidation of ethylene with acetic acid.
Other objects as well as aspects, features and advantages of the present invention will become apparent from a study of the present specification, including the claims and specific examples.
DESRIPTION OF THE PREFERRED EMBODIMENTS
The invention relates to a low temperature catalytic process, where a reactant feed comprising alkane (C
2
,C
3
,C
4
), oxygen, sulfur-containing compound such as hydrogen sulfide, sulfur dioxide or carbonyl sulfide, and optionally water, is contacted in a vapor phase with a mixed metal oxide catalyst preferably having a composition selected from
(i) A calcined composition of Mo
a
V
b
Nb
c
X
d
, wherein X=P, B, Hf, Te, As, or mixture thereof, and wherein
a is 1 to 5,
b is >0 to 0.1,
c is 0.01 to 0.5, and
d is >0 to 0.1.
The numerical values a, b, c and d represent the relative gram-atom ratios of the elements, Mo, V, Nb and X, respectively, in the catalyst. The elements are preferably present in combination with oxygen in the form of various oxides. This composition is described in U.S. Pat. No. 6,013,597 which is herein incorporated by reference.
(ii) A calcined composition of Mo
a
V
b
Nb
c
Pd
d
, wherein
a is 1 to 5,
b is 0 to 0.5,
c is 0.01 to 0.5, and
d is 0 to 0.045.
The numerical values a, b, c and d represent the relative gram-atoms ratios of the elements, Mo, V, Nb and Pd, respectively, in the catalyst. The elements are preferably present in combination with oxygen in the form of various oxides. This composition is described in U.S. Pat. No. 5,907,056 which is herein incorporated by reference.
(iii) A calcined composition of Mo
a
V
b
La
c
Pd
d
Nb
e
X
f
wherein X=Al, Ga, Ge, Si, (at least one element), and wherein
a is 1,
b is 0.01 to 0.9,
c is 0> to 0.2,
d is 0> to 0.2,
e is 0> to 0.2, and
f is 0> to 0.3.
The numerical values a, b, c, d, e and f represent the relative gram-atom ratios of the elements, Mo, V, La, Pd, Nb and X, respectively, in the catalyst. The elements are preferably present in combination with oxygen in the form of various oxides. This composition is described in U.S. Pat. No. 6,060,421.
(iv) A calcined composition of Mo
a
V
b
Pd
c
La
d
, wherein
a is 1 to 5,
b is 0.01 to 0.9,
c 0> to 0.5, and
d 0> to 0.045.
This composition is described in U.S. Pat. No. 6,087,297 which is herein incorporated by reference.
(v) A calcined composition of Mo
a
V
b
Ga
c
Pd
d
Nb
e
X
f
, wherein X=at least one or more from La, Te Ge, Zn, Si, In, W, Bi, W, Mn, Sb, Sn, Fe, Co, Ni, Re, Rh, Pb, Cu, Au, Ti, Na, K, Rb, Mg, Ca, B, and wherein
a is 1,
b is 0.01 to 0.9,
c is 0> to 0.2,
d is 0> to 0.2,
e is 0> to 0.2, and
f is 0> to 0.5.
The numerical values of a, b, c, d, e and f represent the relative gram-atom ratios of the elements Mo, V, Ga, Pd, Nb and X respectively, in the catalyst. The elements are present in combination with oxygen in the form of various oxides. This composition is described in U.S. Pat. No. 6,114,278 which is herein incorporated by reference.
(vi) A calcined composition of Mo
a
V
b
La
c
P
Karim Khalid
Khan Asad
Johnson Jerry D.
Levin Kramer
Naftalis & Frankel LLP
Saudi Basic Industries Corporation
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