GB733896A - Process for the manufacture of ethylene dichloride and other olefin dihalides - Google Patents

Abstract

Ethylene dichloride and other olefin dihalides are manufactured by a method comprising reacting with halogen under superatmospheric pressure a gaseous mixture containing 0.5 to 5 per cent of olefine by volume but constituted predominantly by inert gases together possibly with other gases which are non-reactant with halogen under these conditions and other hydrocarbons. A source of ethylene, for example, may comprise a commercial gas such as refinery waste gas or producer gas, a tail gas from a hydrocarbon catalytic cracking operation or the residual ethylene component found in the tail gases purged from ethylene oxidation systems. When chlorine is used as the halogen it may be introduced into the reaction zone at several points. Preferably the reaction is carried out in the absence of light. The usual chlorinating catalysts may be used if desired. The reaction is accelerated if it is carried out in the presence of iron, preferably in the form of iron reaction vessels or containers. To prevent the formation of trichlorethane when dichlorethane is being prepared a small amount of trichlorethane may be added initially. In the example tail gas containing 2 per cent by volume of ethylene along with ethane, carbon dioxide, oxygen, nitrogen and water is passed through an iron reaction tube at 150 pounds gauge and chlorine is passed into the tube through a series of nozzles; a mixture containing ethylene dichloride is obtained; the gaseous mixture is scrubbed with a lime slurry and then passed through an activated carbon bed which absorbs any chlor-substituted compounds. Alternatively the gases may be passed direct through the carbon bed.