Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2000-09-29
2002-11-26
Silverman, Stanley S. (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S311000, C502S321000, C502S353000
Reexamination Certificate
active
06486091
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to methods of making improved ammoxidation catalysts for the production of unsaturated nitriles from their corresponding olefins.
2. Description of Related Art
Several publications are referenced in this application. The references describe the state of the art to which this invention pertains and are hereby incorporated by reference.
It is known in the art that the bismuth-molybdenum system plays a role in electron donor/acceptor mechanisms for selective oxidation and ammoxidation. Therefore different mechanisms have been proposed based on this property [Delmon et al. (New Development in Selective Oxidation by Heterogeneous Catalysis, Vol. 72, 1992, p. 399-413) and Encyclopedia of Chemical Technology (Kirk-Othmer, Vol. 1, 4th edition, page 358)]. In these mechanisms, molybdenum was shown to be responsible for oxygen and nitrogen uptake and insertion into the substrate, while bismuth plays the role of H-abstraction of the methyl group in the &bgr; position. Therefore, bismuth and molybdenum should be present on the catalyst surface and adjacent in order to form the suitable active phase for this reaction. It should be noted that the deficiency of bismuth on the catalyst surface leads to the total oxidation reaction of the substrate.
It is also well known that antimony plays the role of a donor and thus could improve the selectivity of the catalyst. Antimony can also play an additional role of isolating the vanadium active centers which are highly active towards the oxidation reaction. This leads to minimizing the total oxidation reaction and directs the reaction towards the desired product.
Many catalysts have been disclosed for the foregoing reactions. One such catalyst is described in U.S. Pat. No. 4,062,885, where BiMoSbV systems were used as active elements. The catalyst was used for the preparation of phthalonitrile by the ammoxidation of ortho-xylene. The use of such catalysts for oxidation or ammoxidation reactions involving unsaturated aliphatic hydrocarbons is not mentioned.
U.S. Pat. No. 4,040,978 relates to a catalyst for ammoxidation reactions containing bismuth molybdate mixed with other elements.
U.S. Pat. No. 4,405,498 relates to a catalyst for oxidation and ammoxidation reactions containing BiMoVSb with additional elements selected from groups IA, IIA, IVA, VA, VIA, IB, IVB and VIIB of the periodic Table of the Elements. Elements from group VB of the periodic table are not disclosed in this patent.
U.S. Pat. No. 4,600,541 relates to a catalyst comprising FeBiMo and promoters such as Pd, Pt, Os and Ir.
More recently, European Patent Publication No. 0 475 351 A1 relates to a catalyst containing KFeSbMo which could be promoted by Nb and W. The best yield was achieved with a catalyst of the formula Fe
10
Sb
10
Mo
9
Bi
2
K
0.6
Ni
5.5
W
0.3
B
0.75
P
0.75
(SiO
2
)
70
.
European Patent Publication No. 0 573 713 B1 relates to a catalyst comprising MoBiFeCoNiCr promoted with at least three other promoters selected from alkali metals, alkaline earth metals, rare earth metals, Nb, Tl and As, with Fe, Co, Ni and Cr as essential catalyst components.
U.S. Pat. No. 5,688,739 relates to a multi-component catalyst. The base of this catalyst is bismuth molybdenum. Germanium was added as an essential element. The use of niobium was not disclosed in this patent.
None of the prior art references discloses or suggests catalysts which provide high performance for the selective production of unsaturated nitrites from their corresponding olefins. Accordingly, it would be desirable to produce an improved catalyst for use in the selective production of unsaturated nitrites from their corresponding olefins.
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 useful, improved catalyst for the production of nitrites from their corresponding olefins, particularly for the production of acrylonitrile from propylene.
It is a further object of the invention to provide a process for making an improved catalyst for the production of acrylonitrile at high yields by vapor phase catalytic ammoxidation of propylene in a fluidized or fixed bed reactor.
The foregoing and other objects and advantages of the invention will be set forth in or apparent from the following description.
SUMMARY OF THE INVENTION
The present invention relates to an improved catalyst for the production of unsaturated nitrites from their corresponding olefins and methods of making and using the same. More specifically, the invention relates to improved methods of making such catalysts and the resultant improved catalysts.
Preferably, the catalyst has the following empirical formula set forth below:
Bi
a
MO
b
V
c
Sb
d
Nb
e
A
f
B
g
O
x
, wherein
A=one or more elements selected from groups VB (e.g. V, Nb, Ta), VIB (e.g. Cr, Mo, W), VIIB (e.g. Mn, Tc, Re) or VIII (e.g. Fe, Co, Ni) of the periodic table;
B=at least one alkali promoter selected from groups IA (e.g., Li, Na, K) or IIA (e.g., Mg, Ca) of the periodic table;
a=0.01 to 12;
b=0.01 to 12;
c=0.01 to 2;
d=0.01 to10;
e=0.01 to 1;
f=0 to 2, preferably from 0.01 to 1;
g=0 to 1, preferably from 0.001 to 0.5; and
x=the number of oxygen atoms required to satisfy the valency requirements of the elements present.
The numerical values of a, b, c, d, e, f, g, and x represent the relative gram-atom ratios of the elements, respectively, in the catalyst, where x is a number required to satisfy the valence requirements of the other elements. The elements are present in combination with oxygen, preferably in the form of various oxides.
The invention also relates to an improved selective low temperature catalytic process for the production of nitrites from their corresponding olefins, particularly for the production of acrylonitrile from propylene.
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.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
One aspect of the invention relates to methods for preparing catalysts for the production of unsaturated nitrites.
One embodiment of the invention relates to a method for preparing a catalyst for olefin ammoxidation, said catalyst containing bismuth, molybdenum, vanadium, antimony, and niobium, comprising the steps of:
(a) preparing a vanadium antimonate phase by heating a slurry of vanadium oxide and antimony oxide thereby forming a vanadium-antimony paste and subsequently drying the paste and calcining to form said vanadium antimonate phase;
(b) preparing a niobium-molybdenum solution;
(c) preparing bismuth, niobium, and molybdenum mixed oxide hydrates at room temperature and without heat treating said mixed oxide hydrates;
(d) combining said vanadium antimonate phase, said mixed oxide hydrates and a support thereby forming a catalyst precursor mixture;
(e) stirring the catalyst precursor mixture for a period of time sufficient to form a catalyst precursor paste; and
(f) drying said catalyst precursor paste to form a dried catalyst precursor material and calcining said dried catalyst precursor material to form said catalyst.
Preferably, the catalyst has the following empirical formula:
Bi
a
Mo
b
V
c
Sb
d
Nb
e
A
f
B
g
O
x
, wherein:
A=one or more elements selected from the group consisting of groups VB, VIB, VIIB, and VIII of the periodic table;
B=at least one alkali promoter selected from the group consisting of groups IA and IIA of the periodic table;
a=0.01 to 12;
b=0.01 to 12;
c=0.01 to 2;
d=0.01 to 10;
e=0.01to 1;
f=0 to 2, preferably from 0.01 to 1;
g=0 to 1, preferably from 0.001 to 0.5; and
x=the number of oxygen atoms required to satisfy the valency requirements of the elements present.
Preferably, the vanadium oxide is V
2
O
5
and/or the antimony oxide is Sb
2
O
3
.
Preferably,
Abdulwahed Mazhar
El-Yahyaoui Khalid
Ildebrando Christina
Kramer Levin Naftalis & Frankel LLP
Saudi Basic Industries Corporation
Silverman Stanley S.
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