Organic compounds -- part of the class 532-570 series – Organic compounds – Nitriles
Reexamination Certificate
2002-04-09
2004-04-20
McKane, Joseph K. (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Nitriles
C502S205000, C502S212000
Reexamination Certificate
active
06723869
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a catalyst suitably used for the production of acrylonitrile by ammoxidation of propylene, a process for producing said catalyst and a process for producing acrylonitrile by using said catalyst.
BACKGROUND ART
With respect to the production of acrylonitrile by ammoxidation of propylene, various catalysts suitably used therefor are disclosed. In JP-B-38-17967, there is disclosed an oxide catalyst containing molybdenum, bismuth and iron, and in JP-B-38-19111, there is disclosed an oxide catalyst containing iron and antimony. After that, studies have been extensively continued to improve these catalysts. For example, in JP-B-51-33888, JP-B-55-56839, JP-B-58-2232, JP-B-61-26419, JP-A-7-47272, JP-A-10-43595, JP-A-4-11805 and the like, there are disclosed one improvement comprising using another component in addition to molybdenum, bismuth and iron, and the other improvement comprising using another component in addition to iron and antimony.
Further, in using these catalysts for the ammoxidation reaction, it is proposed to carry out the reaction while supplying a molybdenum-containing material thereto in the ammoxidation reaction, thereby maintaining the catalyst efficiency. For example, in JP-B-58-57422, there is disclosed a process, wherein a particle formed by supporting a molybdenum-containing material on silica is supplied to a fluidized bed catalyst containing molybdenum, bismuth, iron, cobalt and others, thereby restoring the catalyst efficiency. In DE 3,311,521 C2 and WO 97/33863, there is disclosed a process, wherein molybdenum trioxide or a molybdenum compound capable of converting to said trioxide in a specific amount is supplied to a catalyst similar to that mentioned above. Also with respect to a catalyst containing iron and antimony, there is known a similar proposal, for example, in JP-B-2-56938 and JP-B-2-56939.
These catalysts of the prior arts are effective to improve a yield of acrylonitrile to a certain extent. However, further improvements of these catalysts have been requested. Particularly, these catalysts have not been sufficient in respect to repeatability in the production thereof, their structural stability and long-term stability of the yield of desired products. Also with respect to a catalyst containing iron and antimony, particularly a molybdenum component-enriched catalyst containing a crystal phase of iron antimonate, which is disclosed in JP-A-4-118051, it has been very important to improve those from an industrial point of view and therefore further investigation of these catalysts have been required. In addition, also with respect to the process comprising supplying the molybdenum component to maintain the catalyst efficiency, it is difficult to say that it is always effective. Even if the molybdenum-containing material is supplied, no effect can be observed in the case where a catalyst structure is markedly damaged. Further, even if loss of molybdenum is not so large, no effect can be exhibited in the case where lowering of the catalyst efficiency is mainly caused by change of the catalyst structure. It is finding that the catalyst to be applied itself should be stable and should have no extreme damage on its structure.
It has been desired to find a catalyst, which satisfies requisites such as further improvement of the yield of the desired acrylonitrile, superior long-term stability when used for the ammoxidation reaction, and long-term maintenance of its efficiency by the supply of a molybdenum-containing material. An object of the present invention is to solve these problems and particularly to improve the catalyst composition disclosed in JP-A-4-118051, thereby giving a catalyst more suitably used for the production of acrylonitrile by fluidized bed ammoxidation reaction. Another object of the present invention is also to improve the reaction processes disclosed in JP-B-2-56938 and JP-B-2-56939.
DISCLOSURE OF INVENTION
The present inventors have undertaken extensive studies to solve the above-mentioned problems. As a result, they found that a catalyst containing elements such as iron, antimony, molybdenum, bismuth and potassium etc. and iron antimonate within a limited composition region can exhibit a superior catalyst efficiency, and that the efficiency can be maintained for a longer period of time by carrying out the ammoxidation reaction while appropriately adding a molybdenum-containing material thereto.
The present catalyst composition is capable of giving a high acrylonitrile yield and stable in a catalyst structure. Still, in the case where such a catalyst is used for the ammoxidation reaction without interruption, a decrease of the acrylonitrile yield, which appears mainly due to escaping of the molybdenum component, may be observed. Since the ammoxidation reaction is carried out at a temperature exceeding 400° C., it seems that the escaping of the molybdenum component at the time of reaction is inevitable in this kind of catalyst having a large molybdenum content. In this regard, the acrylonitrile yield was able to be maintained at a higher degree for a longer period of time by continuing the reaction while adding and supplying the molybdenum-containing material. According to the catalyst in accordance with the present invention, which is structurally stable, the yield of desired products can be more sufficiently restored by adding the molybdenum-containing material at the time of the ammoxidation reaction. Moreover, since the addition of the molybdenum-containing material at the time of the ammoxidation reaction can be repeated, the catalyst in accordance with the present invention can be used for a much longer period of time by such a repeated addition of the molybdenum-containing material.
The addition of the molybdenum-containing material may be carried out from an early stage of the reaction. In applying the catalyst to the ammoxidation reaction, it is general that a catalyst surface composition and a catalyst structure are optimized by means of a composition, a preparation method or the like. However, it is difficult to say that the optimization can be always realized. As the case may be, the yield of the desired product increases by addition of the molybdenum-containing material at the start of the reaction. This seems that the optimization of the catalyst surface composition and the structure thereof can be realized also with the aid of the molybdenum-containing material.
With respect to a conventional catalyst, the acrylonitrile yield has been insufficient as mentioned above, and it has been also insufficient to restore the catalyst efficiency even if the molybdenum-containing material is added on the grounds that the yield decreases owing to a long-term use. However, according to the present invention, there is provided a process capable of maintaining a high acrylonitrile yield for a long period of time.
That is, the present invention provides a process for producing acrylonitrile, which comprises using a fluidized bed catalyst of a composition represented by the following empirical formula in the production of acrylonitrile by ammoxidation of propylene. The present invention also provides a process for producing acrylonitrile according said process, wherein the ammoxidation reaction is carried out while supplying a molybdenum-containing material. Further, the present invention provides said fluidized bed catalyst and a process for producing said fluidized bed catalyst.
Fea Sbb Moc Bid Ke Ff Gg Hh Qq Rr Tt Ox (SiO2)y
In the formula, Fe, Sb, Mo, Bi and K are iron, antimony, molybdenum, bismuth and potassium, respectively; F is at least one element selected from the group consisting of magnesium, calcium, strontium, barium, manganese, cobalt, nickel, copper, silver, zinc and cadmium; G is at least one element selected from the group consisting of chromium, aluminum, gallium and indium; H is at least one element selected from the group consisting of yttrium, lanthanum, cerium, praseodymium, neodymium and samarium; Q is at least one element selected from the group consisting o
Miyaki Kenichi
Mori Kunio
Sasaki Yutaka
Watanabe Hirokazu
McKane Joseph K.
Mitsubishi Rayon Co. Ltd.
Oblon & Spivak, McClelland, Maier & Neustadt P.C.
Saeed Kamal
LandOfFree
Method for producing acrylonitrile, catalyst for use therein... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for producing acrylonitrile, catalyst for use therein..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for producing acrylonitrile, catalyst for use therein... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3191441