United States Patent 6,143,939
November 7, 2000
Method of Dehalogenation Using Diamonds
Inventors: Malvina Farcasiu, Roslyn Harbor, N.Y.; Phillip B. Kaufman, Lafayette, La.; Edward P. Ladner, Pittsburgh; Richard R. Anderson, Brownsville, both of Pa.
Abstract:
A method for preparing olefins and halogenated olefins is provided comprising contacting halogenated compounds with diamonds for a sufficient time and at a sufficient temperature to convert the halogenated compounds to olefins and halogenated olefins via elimination reactions.
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a method for producing olefins and halogenated olefins, and more specifically, this invention relates to a method for using diamonds and carbon composite materials containing diamonds to catalyze elimination reactions of halogenated compounds to produce olefins and halogenated olefins.
2. Background of the Invention
Dehalogenation reactions and hydrodehalogenation reactions are combined to produce polyvinyl chloride. Current production capacity for polyvinyl chloride is approximately 9.8 billion pounds annually.
The above-mentioned elimination reaction is typically performed thermally at temperatures ranging from 500.degree. C. and 600.degree. C. However, the use of activated carbons in the reaction mixture has resulted in lowering the temperature requirements to between 300.degree. C. and 400.degree. C. Catalytic cracking on pumice or charcoal impregnated with BaCl.sub.2 or ZnCl.sub.2 also has been utilized. However, these procedures have not been widely adopted due to the limited life of the resulting catalysts.
Other efforts for enhancing the catalytic activity of activated carbon in these reactions include incorporating nitrogen materials into the lattice structure of the carbon. While the industrial applicability of the resulting carbon material is not known, it is likely that the resulting carbon is more expensive than typical activated carbon materials.
A need exists in the art for a method to produce olefins and monohalogenated olefins from dihalogenated aliphatic compounds via elimination reactions that can be performed at temperatures much lower than those required in thermal processes. The method should be economical and also employ a reusable catalyst which does not require any preparation.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a method for dehalogenating and hydrodehalogenating halogenated compounds that overcomes many of the disadvantages of the prior art.
Another object of the present invention is to provide a method for converting alkyl halides to olefins and halogenated olefins. A feature of the invention is the use of diamonds as a catalyst for the elimination reaction. An advantage of the invention is that the reaction can proceed at temperatures much lower than those required for thermal reactions.
Still, another object of the present invention is to provide an economical method for producing vinyl chloride. A feature of the invention is the dehalogenation and hydrodehalogenation of 1,2 allyl halide using diamond catalysts. An advantage of the invention is that the diamond catalyst can be utilized for elimination reactions at temperatures of between 200.degree. C. and 350.degree. C., and preferably between 250.degree. C. and 290.degree. C. as compared to 500.degree. C. to 600.degree. C. currently used in thermal processes.
Briefly, the invention provides for a method for preparing olefins and monohalogenated olefins comprising contacting halogenated compounds with diamonds for a sufficient time and at a sufficient temperature to convert the halogenated compounds to olefins.
Also, provided is a device for producing olefins from halogenated compounds comprising an underlayment defining a chamber; a diamond coating on a surface of the underlayment; means for hermetically sealing the underlayment to an ingress manifold and an egress manifold so as to facilitate fluid flow through the chamber; and means for heating the chamber.
A method for producing vinyl chloride is also provided comprising contacting 1,2 dichloroethane with a diamond catalyst for a sufficient time and at a sufficient temperature to convert the 1,2 dichloroethane to a product in a hydrodechlorination reaction.