Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Removing and recycling removed material from an ongoing...
Reexamination Certificate
2000-06-22
2002-10-08
Wu, David W. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Removing and recycling removed material from an ongoing...
C208S262100, C585S525000, C585S521000, C585S520000, C585S504000, C526S133000, C526S131000, C526S348000
Reexamination Certificate
active
06462151
ABSTRACT:
TECHNICAL FIELD
The present invention relates to a method for separating and removing selectively boron trifluoride from a fluid containing boron trifluoride or its complex and a method for recovering the boron trifluoride.
Furthermore, the present invention relates to a method for producing polyolefin using a boron trifluoride complex catalyst, as polymerization catalyst, comprising boron trifluoride and a complexing agent. More particularly, the invention relates to a method in which a polymerization product containing polybutene or olefin oligomer obtained by olefin polymerization is brought into contact with metal fluoride to remove boron trifluoride recovering the complexing agent from the complex catalyst. Furthermore, it relates to a method comprising the steps of heating the produced metal tetrafluoroborate so as to separate metal fluoride and boron trifluoride gas, and reproducing boron trifluoride complex catalyst for reuse from the recovered boron trifluoride and the complexing agent.
BACKGROUND ART
Boron trifluoride and boron trifluoride complex composed of boron trifluoride and a complexing agent (also called as “ligand”) are used widely in industrial fields as catalysts in various chemical reactions such as alkylation, isomerization, polymerization, decomposition and dehydration. These catalysts are used in the form of boron trifluoride alone or in the form of coordination compound containing any of various complexing agents in an appropriate proportion relative to boron trifluoride in accordance with an intended reaction.
After the termination of reaction using boron trifluoride catalyst or its complex catalyst, it is necessary to deactivate the boron trifluoride.
For this purpose, the catalyst is usually neutralized in an aqueous solution of basic substance such as ammonia, caustic soda or lime, then it is washed with water. However, the catalyst treated in such a method cannot be used again. Furthermore, waste liquid containing the used alkali and fluoride as the neutralization product of boron trifluoride, is discarded from the processes of neutralization and washing. In recent years, therefore, it has been demanded to take measures to deal with the problem in environmental pollution. Still further, because boron trifluoride is expensive in itself, its recovering and reusing are advantageous in the viewpoints of economy and environmental protection. Therefore, various kinds of recovering methods have hitherto been proposed.
In the following, a process for producing polybutene and olefin oligomer using boron trifluoride complex will be described.
Polymers having double bond structure of vinylidene groups are especially useful in that they can react with maleic acid or the like at high rate. Therefore, some processes are proposed for introducing much more vinylidene structures into polybutene.
For example, in U.S. Pat. No. 4,152,499, it is disclosed that isobutene is polymerized using, as polymerization catalyst, gaseous boron trifluoride or a boron trifluoride complex catalyst with complexing agent of water or alcohol. In this case, isobutene is polymerized in the temperature range of −50° C. to +30° C., and polyisobutene having a polymerization degree of 10 to 100 is obtained. It is described in this reference that vinylidene double bonds can be introduced into 60 to 90% of terminal positions.
Furthermore, in European Patent No. 0 145 235 A, it is disclosed that polymerization was carried out using a complex catalyst previously prepared from boron trifluoride and C
1
to C
8
alcohols, and vinylidene double bond could be introduced into 70 to 90% of terminal positions of polyisobutene.
As described above, boron trifluoride complex catalysts are often used for producing polybutene such as polyisobutene. For each complex catalyst, specific complexing agent is selected, and its molar coordination number is also specified.
Concerning olefin oligomers, processes for producing olefin oligomer by polymerizing olefins having 6 to 18 carbon atoms are widely known. The olefin oligomer is useful as raw material for lubricating oil such as car engine oil, aircraft hydraulic oil and electrically insulating oil. In recent years especially, olefin oligomers having comparatively low viscosity are considered to be quite useful as a raw material for car engine oil. More particularly, oligomers of linear &agr;-olefin having 10 carbon atoms, i.e., 1-decene, especially oligomers mainly containing trimer of 1-decene have attracted considerable attention.
As the foregoing method for producing oligomers, cationic polymerization processes using a catalyst of Lewis acid such as boron trifluoride is practiced widely. Meanwhile, several attempts have been done widely in order to develop the methods of controlled polymerization and those which are inexpensive and free from environmental pollution.
For example, in Japanese Laid-Open Patent Publication No. H06-287211, it is disclosed that olefin oligomers of comparatively low viscosity can be produced by a method using boron trifluoride catalyst. In this case, however, there is a problem that the controlling of reaction rate of polymerization is difficult. As the countermeasure to this, polymerization method for obtaining olefin oligomers is disclosed, which method uses as polymerization catalyst a boron trifluoride complex catalyst that has boron trifluoride incorporated in a complex.
In the production of olefin oligomers in recent years, boron trifluoride complex catalysts are usually preferred. For each complex catalyst, as in the case of production of polyisobutene, specific complexing agent is selected, and its molar coordination number is also specified.
After the termination of polymerization reaction for polybutene or olefin oligomer as above, boron trifluoride in complex must be removed from the reaction mixture. For this purpose, the reaction mixture is usually neutralized with an aqueous solution of basic substance such as ammonia, caustic soda and lime, then it is washed with water. However, as mentioned above, an environmental problem and other disadvantages are pointed out.
In the following, prior art on the removing and recovering of boron trifluoride used in various kinds of reactions will be described.
For example, methods for separating boron trifluoride complex catalysts from reaction mixtures by heating are proposed. In U.S. Pat. No. 4,263,467 by A. M. Madgavkar, et al., a method is disclosed wherein boron trifluoride is taken out as gas by causing a reaction mixture to move slowly on a floor made of inert metal or ceramics.
In Japanese Laid-Open Patent Publication No. H06-287211, a system using a boron trifluoride complex catalyst is described. It is disclosed that a reaction mixture is heated so as to generate boron trifluoride gas, excess complexing agent is brought into contact with the generated gas to form a new complex, and the complex is recycled to a reactor for reuse.
Further, in Japanese Laid-Open Patent Publication No. H08-333472, the production of &agr;-olefin oligomer is described, wherein boron trifluoride complex catalyst composed of boron trifluoride and reaction accelerator of C
1
to C
8
alkanol is used. In this case, the method comprises a process of thermally decomposing the complex in product fluid to obtain boron trifluoride gas and contacting the gas with a low temperature stream of a-olefin oligomer containing an accelerator, for reuse.
However, in these methods, highly reactive boron trifluoride or its complex is heated in the coexistence of reaction mixture, so that the composition of the reaction mixture may be influenced seriously. In the case of the olefin oligomer containing particularly much &agr;-olefin structure as mentioned above, isomerization or thermal deterioration of olefin is caused by heating it in the coexistence of the complex. As a result, the quality of product deteriorates.
As the other device for recovering boron trifluoride complex catalysts described in U.S. Pat. Nos. 4,454,366 and 4,384,162 by R. F. Vogel, et al., it is disclosed that polyvinyl alcohol is u
Fujimura Koji
Takashima Tsutomu
Tokumoto Yuichi
Choi Ling-Siu
Hollander Law Firm, P.L.C.
Nippon Petrochemicals Company Limited
Wu David W.
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