Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
2001-09-25
2004-03-23
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C502S312000, C502S311000
Reexamination Certificate
active
06710207
ABSTRACT:
The present invention relates to a method for producing unsaturated carboxylic acids by subjecting a mixture of alkene(s) and alkane(s) to vapor phase catalytic oxidation. More particularly, the present invention relates to a method suitable for producing acrylic acid or methacrylic acid by vapor phase catalytic oxidation of a mixture of propene and propane, or a mixture of isobutene and isobutane, respectively.
The present invention also relates to a method of producing unsaturated nitriles by subjecting alkene(s) or a mixture of alkene(s) and alkane(s) to vapor phase catalytic oxidation in the presence of ammonia. More particularly, the present invention relates to a method suitable for producing acrylonitrile or methacrylonitrile by vapor phase catalytic oxidation, in the presence of ammonia, of propene or a mixture of propene and propane, or isobutene or a mixture of isobutene and isobutane, respectively.
Nitriles, such as acrylonitrile and methacrylonitrile, have been industrially produced as important intermediates for the preparation of fibers, synthetic resins, synthetic rubbers, and the like. The most popular method for producing such nitriles is to subject an olefin such as propene or isobutene to a catalytic reaction with ammonia and oxygen in the presence of a catalyst in a gaseous phase at a high temperature. Known catalysts for conducting this reaction include a Mo—Bi—P—O catalyst, a V—Sb—O catalyst, an Sb—U—V—Ni—O catalyst, a Sb—Sn—O catalyst, a V—Sb—W—P—O catalyst and a catalyst obtained by mechanically mixing a V—Sb—W—O oxide and a Bi—Ce—Mo—W—O oxide. However, in view of the price difference between propane and propene or between isobutane and isobutene, attention has been drawn to the development of a method for producing acrylonitrile or methacrylonitrile by the ammoxidation reaction wherein a lower alkane, such as propane or isobutane, is used as starting material, and it is catalytically reacted with ammonia and oxygen in a gaseous phase in the presence of a catalyst.
In particular, U.S. Pat. No. 5,281,745 discloses a method for producing an unsaturated nitrile comprising subjecting an alkane and ammonia in the gaseous state to catalytic oxidation in the presence of a catalyst which satisfies the conditions:
(1) the mixed metal oxide catalyst is represented by the empirical formula
Mo
a
V
b
Te
c
X
x
O
n
wherein X is at least one element selected from the group consisting of niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron and cerium and, when a=1, b=0.01 to 1.0, c=0.01 to 1.0, x=0.01 to 1.0 and n is a number such that the total valency of the metal elements is satisfied; and
(2) the catalyst has X-ray diffraction peaks at the following angles(±0.3°) of 2&thgr; in its X-ray diffraction pattern: 22.1°, 28.2°, 36.2°, 45.2° and 50.0°.
There is no disclosure, whatsoever, of the use of alkenes in the feed and only a propane feed is cited in the examples.
Similarly, Japanese Laid-Open Patent Application No. 6-228073 discloses a method of nitrile preparation comprising reacting an alkane in a gas phase contact reaction with ammonia in the presence of a mixed metal oxide catalyst of the formula
W
a
V
b
Te
c
X
x
O
n
wherein X represents one or more elements selected from niobium, tantalum, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, indium and cerium and, when a=1, b=0.01 to 1.0, c=0.01 to 1.0, x=0.01 to 1.0 and n is determined by the oxide form of the elements.
There is no disclosure, whatsoever, of the use of alkenes in the feed and only a propane feed is cited in the examples.
The ability to convert alkene(s) or a mixed feed of alkene(s) and alkane(s) to the corresponding unsaturated nitrile with a mixed metal oxide catalyst is believed to be novel in that it could not be anticipated that a mixed metal oxides which ammoxidizes alkanes to the corresponding unsaturated nitrile would necessarily also oxidize alkenes to the same product.
Unsaturated carboxylic acids such as acrylic acid and methacrylic acid are industrially important as starting materials for various synthetic resins, coating materials and plasticizers. Commercially, the current process for acrylic acid manufacture involves a two-step catalytic oxidation reaction starting with a propene feed. In the first stage, propene is converted to acrolein over a modified bismuth molybdate catalyst. In the second stage, acrolein product from the first stage is converted to acrylic acid using a catalyst composed of mainly molybdenum and vanadium oxides. In most cases, the catalyst formulations are proprietary to the catalyst supplier, but, the technology is well established.
It is also known to produce acrylic acid by oxidation of propene in the presence of a mixed metal oxide catalyst.
Japanese Laid-Open Patent Application No. 07-053448 discloses the preparation of acrylic acid by the gas-phase catalytic oxidation of propene in the presence of a mixed metal oxide catalyst of the formula
Mo
a
V
b
Te
c
X
d
O
n
wherein X is at least one element selected from Nb, Ta, W, Ti, Al, Zr, Cr, Mn, Fe, Ru, Co, Rh, Ni, Pd, Pt, Sb, Bi, B, In, Li, Na, K, Rb, Cs and Ce; a=0.25−0.98; b=0.003−0.5; c=0.003−0.5; d=0.003−0.5 and n is determined by the oxidation state of the other elements.
Similarly, Published International Application No. WO 2000/09260 discloses a catalyst for the selective oxidation of propene to acrylic acid and acrolein which comprises a mixed metal oxide of molybdenum, vanadium, lanthanum, palladium, niobium, and copper and/or chromium wherein the metals are present in the ratios given by the formula
Mo
a
V
b
La
c
Pd
d
Nb
e
X
f
wherein X=Cu and/or Cr; a=1; b=0.01 to 0.9; c=greater than zero to 0.22; d=0.0000001 to 0.2; e=0 to 0.2; and f=0 to 0.2.
U.S. Pat. No. 5,994,580 discloses the recycle of by-product propene in a process for producing acrylic acid from propane and oxygen gas through a vapor-phase catalytic oxidation reaction, the process comprising conducting the reaction using as a catalyst a metal oxide containing the metallic elements Mo, V, Sb and A (wherein A is at least one of Nb, Ta, Sn, W, Ti, Ni, Fe, Cr and Co), the metal oxide having been prepared by a process including specific steps (1) and (2). Step (1) comprises reacting V
+5
with Sb
+3
in an aqueous medium at a temperature of 70° C. or more in the presence of Mo
+6
and, during or after the reaction, bubbling either molecular oxygen or a gas containing molecular oxygen into the reaction mixture. Step (2) comprises adding a compound containing the element A as a component thereof to the reaction product obtained in step (1), mixing the ingredients to obtain a homogeneous mixture, and burning the resulting mixture.
Commercial incentives exist for producing acrylic acid using a lower cost propane feed. Therefore, the prior art describes cases wherein a mixed metal oxide catalyst is used to convert propane to acrylic acid in one step.
In particular, U.S. Pat. No. 5,380,933 discloses a method for producing an unsaturated carboxylic acid comprising subjecting an alkane to a vapor phase catalytic oxidation reaction in the presence of a catalyst containing a mixed metal oxide comprising, as essential components, Mo, V, Te, O and X, wherein X is at least one element selected from the group consisting of niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium and cerium; and wherein the proportions of the respective essential components, based on the total amount of the essential components exclusive of oxygen, satisfy the following relationships: 0.25<r(Mo)<0.98, 0.003<r(V)<0.5, 0.003<r(Te)<0.5 and 0.003<r(X)<0.5, wherei
Bogan, Jr. Leonard Edward
Han Scott
Jacobs Bradley Anson
Kaiser Frederick William
Klugherz Peter David
McKane Joseph K.
Rohm and Haas Company
Shameem Golam M M
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