Organic compounds -- part of the class 532-570 series – Organic compounds – Carboxylic acids and salts thereof
Reexamination Certificate
1995-05-31
2002-08-06
Griffin, Steven P. (Department: 1754)
Organic compounds -- part of the class 532-570 series
Organic compounds
Carboxylic acids and salts thereof
C562S531000, C562S535000, C502S220000, C502S312000, C502S318000, C502S321000, C502S353000, C502S345000, C502S313000, C502S315000, C502S316000, C502S324000
Reexamination Certificate
active
06429332
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a catalyst for the production of acrylic acid and a method for the production of acrylic acid by the use of this catalyst. More particularly, it relates to a catalyst for producing acrylic acid by the vapor-phase catalytic oxidation of acrolein or an acrolein-containing gas and to a method for the production of acrylic acid by the vapor-phase catalytic oxidation of acrolein or an acrolein-containing gas in the presence of this catalyst.
2. Description of the Prior Art
Various improved catalysts have been proposed for the efficient production of acrylic acid by the vapor-phase catalytic oxidation reaction of acrolein or an acrolein-containing gas. Most of the catalysts which have been heretofore proposed have molybdenum and vanadium as main components thereof. For example, JP-B-44-12,129 discloses a catalyst comprising molybdenum, vanadium and tungsten, JP-B-49-11,371 a catalyst comprising molybdenum, vanadium, copper, tungsten and chromium, JP-B-50-25,914 a catalyst comprising molybdenum and vanadium, JP-B-52-85,091 a catalyst comprising molybdenum, vanadium, copper and (at least one element selected among antimony and germanium).
These conventional molybdenum-vanadium type catalysts, however, are deficient not only in the yield of acrylic acid in the light of the industrial production but also in the service life of the catalyst because of the rapid decrease of the activity. The development of a catalyst for the production of acrylic acid which excels in activity and stability, and further permits the production of acrylic acid at high yield and stably for a long time has been longed for.
Solid acids whose magnitudes of acid strength (Ho) (hereinafter referred to simply as “acid strength” or occasionally as “Ho”) are not more than −11.93 are generally called as solid super acids as introduced in detail in “SHOKUBAI,” Vol. 31, No. 7 (1989), pp. 512 through 518, for example. According to the literature, the super acid is defined as an acid possessing acidity stronger than that of 100% sulfuric acid (Ho≦−11.93) and is reported to be usable under more moderate conditions than the ordinary acid catalysts in such reactions as decomposition, isomerization, alkylation, polymerization, acylation, dehydration, and dehydrogenation of hydrocarbon which are referred to as acid catalytic reactions. The fact that this super acid, particularly when combined with a molybdenum-vanadium type catalyst, is effective in inducing the vapor-phase catalytic oxidation reaction of acrolein or acrolein-containing gas has not been known at all to the art.
One object of this invention, therefore, is to provide a catalyst for producing acrylic acid at a high yield by the vapor-phase catalytic oxidation reaction of acrolein or acrolein-containing gas.
Another object of this invention is to provide a catalyst for the production of acrylic acid, which permits the production of acrylic acid by the vapor-phase catalytic oxidation reaction of acrolein or acrolein-containing gas stably for a long period.
Still another object of this invention is to provide a catalyst for the production of acrylic acid by the vapor-phase catalytic oxidation reaction of acrolein or acrolein-containing gas, which catalyst excels in terms of catalytic activity and service life and permits stable production of acrylic acid at high productivity for a long time.
Yet another object of this invention is to provide a method for producing acrylic acid efficiently by the use of the catalyst for the production of acrylic acid mentioned above.
SUMMARY OF THE INVENTION
The objects mentioned above are accomplished by a catalyst for producing acrylic acid by the oxidation of acrolein or acrolein-containing gas in a vapor phase with a molecular oxygen-containing gas, which catalyst comprises (A) a composite oxide having molybdenum and vanadium as essential components and adapted for the production of acrylic acid by the vapor-phase catalytic oxidation of acrolein and (B) a solid acid having acid strength (Ho) of not more than −11.93 (Ho≦−11.93). These objects are further accomplished, in the vapor-phase catalytic oxidation reaction for producing acrylic acid by the oxidation of acrolein or acrolein-containing gas in the vapor phase with the molecular oxygen-containing gas, by a method for the production of acrylic acid which effects the reaction in the presence of the catalyst for the production of acrylic acid mentioned above.
The present inventors have learnt that a catalyst composition which combines a molybdenum-vanadium type composite oxide which has been usually known as a catalyst for the production of acrylic acid with a solid acid having acid strength of not more than −11.93 possesses high activity at low temperatures as compared to conventional catalysts and excels in stability as a catalyst. This invention have been perfected on the basis of this knowledge.
Since the catalyst of this invention maintains high activity, it aids in the production of acrylic acid at a high yield.
Since the catalyst of this invention excels in terms of service life and maintains this outstanding quality for a long time, it permits acrylic acid to be produced stably for a long time. Even after a protracted use, this catalyst can continue the reaction for the production of acrylic acid at the same degree of yield as during the initial stage of the reaction without appreciably increasing the reaction temperature.
Since the catalyst of this invention exhibits high activity even at low temperatures, it aids in effecting the reaction at the same degree of yield at reaction temperatures lower than those necessary for the conventional methods.
Since the catalyst of this invention suffers no degradation of catalytic property even under high-load operation conditions aimed at a high productivity, it permits acrylic acid to be produced stably with high operational efficiency for a long time.
By the method of this invention, acrylic acid can be produced efficiently and advantageously on a commercial scale.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Now, this invention will be described in detail below.
Component (A):
As the component (A), any of the well-known composite oxide catalysts which have molybdenum and vanadium as essential components and are used for producing acrylic acid by the vapor-phase catalytic oxidation of acrolein can be used. In these catalysts, those catalysts which are represented by the following general formula (1):
Mo
a
V
b
W
c
Cu
d
X
e
O
g
(wherein Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, X is at least one element selected from the group consisting of Mg, Ca, Sr and Ba, and 0 is oxygen, and a, b, c, d, e, and g are atomic ratios respectively of Mo, V, W, Cu, X, and 0 such that b is a numeral in the range of 2 to 14, c in the range of 0 to 12, d in the range of 0 to 6 excluding 0 (0<d≦6) (0.1 to 6, for example), e in the range of 0 to 3, and g is a numeral to be determined by the oxidized states of the elements when a is fixed at 12), are advantageously used. Particularly, the catalysts which are represented by the following general formula (2):
Mo
a
V
b
W
c
Cu
d
X
e
y
f
O
g
(wherein Mo is molybdenum, V is vanadium, W is tungsten, Cu is copper, X is at least one element selected from the group consisting of Mg, Ca, Sr and Ba, Y is at least one element selected from the group consisting of Ti, Zr, Ce, Cr. Mn, Fe, Co, Ni, Zn, Nb, Sn, Sb, Pb and Bi, and 0 is oxygen, and a, b, c, d, e, f, and g are atomic ratios respectively of Mo, V, W, Cu. X, Y, and 0 such that b is a numeral in the range of 2 to 14, c in the range of 0 to 12, d in the range of 0 to 6 excluding 0 (0<d≦6) (0.1 to 6, for example), e in the range of 0 to 3, f in the range of 0 to 3, and g is a numeral to be determined by the oxidized states of the elements when a is fixed at 12), are advantageously used.
These catalysts are not discriminated on account of their methods of preparation. They may be prepared by any of the well-known methods.
Aoki Yukio
Kawajiri Tatsuya
Tanimoto Michio
Yunoki Hiromi
Griffin Steven P.
Ildebrando Christina
Nippon Shokubai Co. , Ltd.
Selitto Behr & Kim
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