Patent GB-744078-A (GB)
Title: Improvements in or relating to utilization of an acetylene and ethylene mixture
IPC: C07C17/08
Filed: 1953-06-10
Abstract: Ethyl chloride and acetylene are obtained by passing a mixture of acetylene and ethylene through a reaction zone with hydrogen chloride in contact with a zinc salt hydrochlorination catalyst at 140-200 DEG , preferably 150-175 DEG , C., recovering ethyl chloride from the reaction products, and separating a residual gas stream enriched in acetylene.  A small amount of vinyl chloride is also obtained. Specified catalysts are zinc acetate and zinc chloride impregnated active carbon.  The feed-stock may be obtained by cracking relatively saturated light hydrocarbons at about 1100-1600 DEG , preferably about 1200-1350 DEG , C., and preferably acetylene and ethylene are present in equimolar quantities. Contact times do not normally exceed 25 seconds and preferably do not exceed about 15 seconds.  Specified hydrocarbon charge stocks are natural gas, casinghead and natural gasoline and naphtha fractions, a relatively pure ethane fraction being preferred. Steam or other inert gases may be present during cracking. Propylene may be present during the reacting, being converted to the chloride or removed before reaction by absorption in sulphuric acid.  Residual gas may be recycled or treated in a further hydrochlorination stage.  Advantageously the reaction is only partially completed and acetylene selectively converted to a derivative thereof in a subsequent reaction in which ethylene is not reactive.  By this means a residual gas may be obtained which is in the required relative proportions of ethylene and acetylene for recycling with fresh feed, c.f. Specification 744,079. Contact times mentioned for hydrochlorination are 20-100, preferably 50-70, seconds.  In the acetylene consuming stage, vinyl chloride may be made by passing the residual gas mixture with excess hydrogen chloride at about 175-220 DEG  C. over activated carbon containing mercuric chloride with contact times of 20-25 seconds; vinyl acetate may be made by treatment with acetic acid in the vapour phase with a zinc or cadmium catalyst, e.g. zinc acetate at about 175-225 DEG  C., c.f. Specification 744,077, or if the ethylene is less than about 10 per cent reaction may be effected in liquid phase; trans-dichloroethylene may be made by passing the residual gas with some hydrogen through a solution containing cuprous, cupric and ammonium chloride in aqueous hydrochloric acid, c.f. Specification 744,081, the resulting dichloride may be converted to vinylidene chloride and tri, tetra-, penta- and perchloroethylene; acrylonitrile may be made by treatment with hydrogen cyanide in the presence of a catalyst containing sodium, potassium and cuprous chlorides suitably only about 0.1-0.2 mols. of cyanide being introduced per mol. of acetylene and the proportion of cuprous chloride in the catalyst mixture being about 40-50 parts by weight per part of cyanide, if the acetylene content is low vapour phase conversion is preferred, e.g. at about 400-700 DEG  C. over barium oxide on carbon; acetylenic alcohols and vinyl ethers may be made by absorbing the gas in a suspension of potassium hydroxide in an inert solvent, e.g. xylene, c.f. Specification 744,082, addition of aldehyde or ketene producing the carbinol, e.g. acetone and acetaldehyde respectively yield 2-methyl-3-butyn-2-ol and 3-butyn-2-ol, whilst addition of alcohols leads to vinyl ethers, e.g. n-butanol forms vinyl n-butyl ether; butynediol-1,4 is made by passing the gas at about 75 p.s.i.g. with aqueous 15 per cent formaldehyde at about 100-120 DEG  C. over copper acetylide-coated silica, small quantities of propargyl alcohol also being obtained; vinyl ethers are made by passing the gas into an alcohol containing a small amount of the corresponding sodium alcoholate at 120-200 DEG , preferably about 180 DEG  C. (except with methanol, when reaction is effected at 120 DEG  C.) under pressure sufficient to ensure a liquid-phase reaction; and styrene is obtained by passing the gas, containing only a small proportion of ethylene, together with benzene, e.g. 5-20 mols. of benzene per mol. of acetylene, at 100-600 p.s.i. and about 350-500 DEG  C. over calcined mixed hydrogels of silica and alumina.  In examples, an acetylene-ethylene mixture is treated in the presence of zinc chloride-impregnated active carbon to yield ethyl chloride and a residual acetylene-ethylene mixture, the acetylene of which is converted in (1) to vinyl chloride; (2) and (3) to dichloroethylene; and (4) vinyl acetate by methods outlined above.  An illustration of a suitable lay-out of apparatus is also provided.ALSO:The following catalyst compositions are described:-Mercuric oxide, boron trifluoride and hydrogen fluoride are dissolved in acetic acid for use in the conversion of acetylene into vinyl acetate; a mixture of potassium, sodium and cuprous chlorides is used for the conversion of acetylene and hydrogen cyanide into acrylonitrile; granular activated carbon is immersed in an aqueous solution of zinc chloride, drained and dried in nitrogen at 150 DEG C. the treatment being repeated and the product used in the conversion of ethylene in acetylene-ethylene mixtures into ethyl chloride; an aqueous hydrochloric acid solution of cuprous, cupric and ammonium chlorides is used in the conversion of acetylene into dichloroethylene; and active carbon saturated with zinc acetate solution is dried in nitrogen at 180 DEG C. and additional nitrogen passed over after passing through acetic acid at 80 DEG C. to give a catalyst used in the preparation of vinyl acetate from acetylene and acetic acid.  Specifications 744,077, 744,079, 744,081 and 744,082 [all in Group IV(b)] are referred