E.i. Dupont De Nemours and Company

Francisco Jose Freire

Dennie Turin Mah

Vinci Martinez Felix

James Arthur Trainham

John Scott Newman

Clarence Garlan Law, Jr

Kenneth B Keating

Kaye L Motz

Bruce Arthur Kaiser

Eileen G Edwards

Jon Lee Howell

William C Ziegenhain

Douglas John Eames

William H Zimmerman

Craig T Barker

Edward Kaoru Sakata

Edward Joseph Fahy

A process and a system produces isocyanate and converts anhydrous hydrogen chloride, which is a by-product of isocyanate production, to chlorine gas in an electrochemical cell. The chlorine is recycled to the isocyanate process. Any unreacted anhydrous hydrogen chloride may be recycled to the electrochemical cell. By recycling the anhydrous hydrogen chloride and the chlorine, the process and system are able to reduce the cost of producing isocyanate. In addition, this process and system process eliminate or at least substantially minimize the problems associated with disposal of anhydrous hydrogen chloride by turning it into a useful starting material in the isocyanate process.

Production of isocyanate using chlorine recycle

The present invention relates to an electrochemical cell having split fluid and current feed. Specifically, the cathode or anode inlet and outlet fluid may be fed from both, rather than from just one end of the electrolyzer. Alternatively, or additionally, the current may be fed to the anode or cathode side of the cell at one point, but may be removed from the opposite end of cell at two points. By feeding the fluid from both ends of the electrolyzer, the internal shunt current within each manifold is reduced, while the active area in the electrolyzer is increased without increasing the overall area of the current distributors. By removing the current from the electrolyzer at two points rather than just one, the voltage required by the electrolyzer may be reduced by half than if the current were removed at just one point.

Electrochemical cell having split fluid and current feed

The present invention relates to an electrochemical cell, system and process for converting essentially anhydrous hydrogen halide to essentially dry halogen gas. The process of the present invention is useful for converting anhydrous hydrogen halide, in particular, hydrogen chloride, hydrogen fluoride, hydrogen bromide and hydrogen iodide, to a halogen gas, such as chlorine, fluorine, bromine, or iodine. In particular, in the present invention, water is provided to the cation-transporting membrane at the cathode in various ways. The present invention allows for recovery of a released fluid at the cathode-side of the membrane and recycling of the released fluid back to the cathode side of the membrane. In this way, the recovered, released fluid may be recycled to continuously supply water to the membrane, thereby allowing the limiting current density of the cell to be increased and/or controlled.

Membrane hydration in electrochemical conversion of anhydrous hydrogen

Carbonyl halide is produced from carbon monoxide and halogen produced from the electrochemical conversion of anhydrous hydrogen halide. Both the oxidation of anhydrous hydrogen halide and the formation of carbonyl halide are carried out in the anode-compartment of an electrochemical cell. This reduces the equipment and thus the capital investment necessary for carrying out these reactions. Moreover, no catalyst is needed to form halogen and subsequently make carbonyl halide, as in the prior art. In addition, the health hazards associated with making a carbonyl halide, such as phosgene, at high temperatures from chlorinated hydrocarbons with atmospheric oxygen are virtually eliminated. Furthermore, the halogen produced as a result of the oxidation of anhydrous hydrogen halide are dry, thereby eliminating the need for a preheater before the halogen is reacted with carbon monoxide. Thus, with the present invention, carbonyl halide may be produced more easily, more safely and more inexpensively as compared to prior art processes.

Method for and apparatus production of carbonyl halide

A process and a system uses a direct chlorination reactor for producing ethylene dichloride by direct chlorination, without the need for an oxychlorination unit. This ethylene dichloride may be used to make vinyl chloride monomer. In the process for making ethylene dichloride, ethylene and chlorine are both supplied to a direct chlorination reactor. The ethylene reacts with the chlorine to form ethylene dichloride. Chlorine is supplied to the direct chlorination reactor from an electrochemical cell which converts anhydrous hydrogen chloride to dry chlorine gas. This chlorine gas is purified and liquefied to form liquid dry chlorine, and the liquid dry chlorine is recycled to the direct chlorination reactor. The ethylene dichloride may be pyrolyzed to produce vinyl chloride monomer and anhydrous hydrogen chloride.

Production of ethylene dichloride by direct chlorination and production

A process for manufacturing high purity anhydrous hydrogen fluoride (HF) having low levels of oxidizable impurities by electrolytically oxidizing the impurities. Specifically, trivalent arsenic impurity in the anhydrous hydrogen fluoride is oxidized to a non-volatile pentavalent arsenic compound. The resultant solution is distilled to recover high purity anhydrous hydrogen fluoride with low levels of arsenic impurity.

Process for purifying hydrogen fluoride

A process for manufacturing high purity anhydrous hydrogen fluoride (HF) having low levels of oxidizable impurities by electrolytically oxidizing the impurities. Specifically, trivalent arsenic impurity in the anhydrous hydrogen fluoride is oxidized to a non-volatile pentavalent arsenic compound. The resultant mixture is distilled to recover high purity anhydrous hydrogen fluoride with low levels of arsenic impurity.

Growing community of inventors

Wilmington, DE, United States of America

Francisco Jose Freire