US1231123A - Production of chlorinated hydrocarbons. - Google Patents

Description

B. T. BROOKSKL D. F. SMITH. PRODUCTION OF CHLORINATED HYDROCARBONS.

APPLICATION FILED DEC- I0. l9l v- Patented June 26, 1917.

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BENJAMIN T. BROOKS AND DILLON 1:". SMITH, OF PITTSBURGH, PENNSYLVANIA, ASSIGNORS TO GULF REFINING- COMPANY, OF PITTSBURGH, PENNSYLVANIA, A

CORPORATION OF TEXAS.

PRODUCTION OF CHLORINATED HYDROCARBONS.

Specification of Letters Patent.

Patented June 26, 1917.

Application filed December 10, 1915. Serial No. 66,068.

lene series, and particularly to the production of mixtures of dichlorinated hydrocarbons containing dichlor-ethylene and dichlor-propylene from mixtures of ethylene hydrocarbons I containing ethylene and propylene.

Oil gas, when suitably produced, is rich in olefins, particularly in the olefins of the ethylene series. The average oil gas produced, for instance, by Youngs process, may have a composition of about 43% olefins, 16% hydrogen and 30% to 33% saturated hydrocarbons, particularly methane. The

composition will vary with the conditions under which the oil is produced, and the oil gas may accordingly contain increased or decreased amounts of the olefins and saturated hydrocarbons. The'oil gas may, for instance, contain about 33% unsaturated hydrocarbons, about 20% hydrogen and about 45%. saturated hydrocarbons.

The olefins or unsaturated hydrocarbons of oil gas consist principally of ethylene and propylene. other hydrocarbons such as butylene, amylene, benzol, etc., may also be present. The relative proportions of ethylene and propylene, which are the principal unsaturated constituents, will also vary with diflerent oil ases, depending upon the method of production of the oil gas, the material from which produced, etc. For some purposes it is desirable that the gaseous mixture should contain relatively larger amounts of ethylene, while for other purposes larger amounts of propylene may be desirable. The relative amounts of ethylene and propylene can also be varied and to a cer-' Relatively small amounts of.

tain extent regulated by the method of producmg the oil gas.

The present invention relates to the production of dichlorinated hydrocarbons of the ethylene series, and particularly to mixtures of dichlor-ethylene and 'dichlor-propylene, or mixtures consisting principally of these two chlorinated hydrocarbons. by chlorinating the mixture of unsaturated ethylene hydrocarbons obtained from oil gas, after these hydrocarbons have been subjected to a' suitable preliminary treatment.

According to the present invention, the oil gas is first treated to separate the unsaturated hydrocarbons from the saturated hydrocarbons and hydrogen, and also to separate the ethylene and propylene from the other unsaturated hydrocarbons. For the purpose of effecting this preliminary separation of the ethylene and propylene, the oil gas is, with advantage, subjected to a low temperature, such as is obtainable by com bined cooling and compression, or by cooling with or without pressure to sufliciently low temperatures, for example, in an apparatus similar to that used for the production of liquid air. The easily condensible constituents are thereby condensed out while other constituents, particularly hydrogen and methane, remain uncondensed and are thus separated. The condensed gases are then slowly vaporized and the ethylene and propylene are slowly boiled ofi, leaving behind the hydrocarbons of higher boiling point. Those higher boiling hydrocarbons will tend to boil ofl' to some small extent with the ethylene and propylene, but the process can be readily controlled so that the ethylene and propylene will be given off in a relatively pure condition, containing only small into their corresponding dichlorinated derivatives. For this purpose, the gaseous mixtureand chlorin are separately passed into a suitable ,co-solvent, i. e., a solvent for both the chlorinand the unsaturated hydrocarbons; As SllChf co-solvents may be mentioned chloroformfcarbon tetrachlo-rid, carbon-disulfid, tetrachlorethane, and particularly the mixture of'dichlor-inated ethylene hydrocarbons which results from the chlorinating process itself. As such co-solvents may be used any suitable solvent which will take up chlorin without being acted upon and which will also take up the hydrocarbons to be chlorinated. 4 i The co-solvent also acts as'a diluent and as a solvent medium'for the reacting chlorin and hydrocarbons sothat'the chlorination reaction proceeds smoothly and in a manner which can bev readilycontrolled. The cosolvent is furthermore. miscible with the chlorinated hydrocarbons resulting from the reaction so that the addition thereto of these further amounts of the chlorinated hydrocarbons formed is of advantage for the reason that the, body of the co-solvent is thereby increased. As the amount of chlorinated hydrocarbons increases, part of the mixture of such hydrocarbons'with the co-solvent, where the co-solvent is other than the hydrocarbon mixture produced or of the hydroca rbon mixture, where this is used as the cosolvent, can be drawn 01f either in a continuous or in anintermittent manner.

The chlorination reaction results in-the production of considerable heat, although the reaction is not of a violent nature. This heat will be firstltaken up by the body of liquid which forms the co-solvent. .In order that this solution may not become too hot due to self-heating, it may be necessary or advisable to keep the solution cold by suit able cooling coils or cooling jackets. The reaction can, in fact, be carried on smoothly, and in a manner readily controlled, at the ordinary temperature, or at colder temperatures, and at atmospheric pressure. In order to promote theuniformity of distribution of thechlorin solution throughout the body of the co-solvent, suitable mechanical stirrers or agitators may be used, although the gases 7 introduced will themselves tend to keep the solvent more yor lessagitated.

The concentration'of thechlorin' in the co-solvent is maintained by continually passing in further amounts of chlorin in a finely divided condition as through small, practically capillary, apertures. The hydro carbon mixturecan be similarly introduced,

although the chlorin and hydrocarbon should not be introduced at the same place.

Their introduction should be sufficiently separated so that solution will take place before the gases are brought into reacting relation with each other.

During the chlorination, any saturated hydrocarbons such as ethane orpropane will tend to pass through the solution and escape therefrom as vapors, since the saturated hydrocarbons are not acted upon by the chlorin under the conditions of the reaction.

be obtained from any suitable source, and

moist chlorin has been foundto give good .of chlorinated hydrocarbons which have r The chlorin used for the chlorination can I been carried over with. the unchlorinated hydrocarbons.

The escaping gases can be treated in a scrubber, with heavy hydrocarbon oils, for the recovery of the chlorinated hydrocarbons; or they can be subjected to compression for the purpose of liquefying these hydrocarbons.

A suitable apparatus for the practice of the chlorinating reaction of the present invention is indicated, more or less diagrammatically, in the accompanying drawings. The tank '1, which may be of earthenware, or other chlorin-resisting material, is provided with cooling coils 2 and-with inlet 3 and .outlet 4 for the introduction ofthe solvent and the removal of the solvent and 1 top of the reaction vessel, the vapors escape through the pipe 9, eitherthrough the pipe 10 to the scrubber 11, or through the pipe 12 to the compressor 13. The scrubber may be of any suitable construction so that the chlorinated hydrocarbons will be removed therein, as by means ofheavy'hydrocarbons of the chlorinated hydrocarbons." A suitflowing-down through'the scrubber. These chlorinated hydrocarbons carried over with the vapors can be similarly removed by the compressor 13 and thereby separated from any accompanylng gaseous hydrocarbons.

The arrangement of the chlorin and bydrocarbon inlets is such that thechlorin is first absorbed before it is mixed with the hydrocarbon gases, the gas inlets being indi cated as arranged a distance of, for example, 12 or 15 inches above the chlorin inlets, for this purpose.

The use of the mixture of dichlorinated hydrocarbons produced during the reaction, as a co-solvent, is of particular advantage, for the reason that no further separation of the product of the reaction therefrom is necessary, and also for the reason that such a mixture appears of particular advantage as a solvent for the chlorin and for the hydrocarbons, and for the production therefrom of the chlorinated hydrocarbon'mixture itself, which results from their combination. Where a co-solvent other than the chlorinated ethylene hydrocarbons is used, tetrachlorethane presents the advantage of having a boiling point considerably higher than that of the dichlor-ethylene and dichlor-propylene, so that these latter designated hydrocarbons can .be readily separated by distillation.

Attempts have heretofore been made to produce mixtures of dichlorinated ethylene hydrocarbons from oil gas, but such production has, so far as we are aware, been accompanied by the production, at the same time, of other chlorinated derivatives from other unsaturated hydrocarbons and the production of hydrochloric acid from hydrogen, because of the fact that the hydrocarbon mixture chlorinated contained hydrogen and other unsaturated hydrocarbons. Where hydrogen is present, its chlorination, in some cases, takes place with explosive violence. Its chlorination, furthermore, to produce hydrochloric acid, involves a loss and waste of chlorin inasmuch as hydrochloric acid is relatively less desirable and valuable, and can be produced more readily by other processes. Furthermore, when hydrochloric acid is produced, it requires to be separately recovered and its presence appears to be prejusaturated hydrocarbons and from the higher unsaturated hydrocarbons, so that the resulting chlorinated product consists principally of a mixture of ethylene and propylene dichlorids. This product is a valuable product for use as a solvent, and forms an improved Dutch liquid. It can also be used for the production of glycols. of an improved Dutch liquid, it is usually desirable to have the mixture relatively richer in propylene dichlorid. The relative amounts of these hydrocarbons in the mixture chlorinated can be to some extent regulated by regulating the process of producing the oil gas, as already stated.

For the production;

The chlorination of the mixture of ethylene hydrocarbons, consisting principally of ethylene and propylene appears to proceed in a manner equally well or even more advantageously than the chlorination of the individual hydrocarbons, and accordingly, We consider the chlorination of such a mixture to produce a resulting mixture consisting principally of ethylene and propylene dichlorids, as a particularly valuable and important embodiment of our invention. The chlorination of the individual ethylene hydrocarbons can, however, be effected in a similar manner, and similar advantages obtained as with the chlorination of the hydrocarbon mixtures. A

Inasmuch as the ethylene hydrocarbons are themselves unsaturated, the chlorination reaction is a simple addition reaction so that no other products of the reaction are produced. By carrying on the reaction in the cold or at ordinary temperatures and by the use of the co-solvent for promoting the reaction, the reaction proceeds smoothly in an easily regulated manner. No catalysts for promoting or modifying the reaction are necessary, and

none need in practice be used, inasmuch as the reaction proceeds smoothly and in a particularly advantageous manner under the conditions described.

The mixture of dichlorinated hydrocarbons is obtained in a relatively pure condition, as above noted, being relatively free both of hydrochloric acid and of higher chlorinated hydrocarbons. No further purification will usually be necessary where the mixture is to be used for the production of glycols. Where the mixture is to be used as a solvent, it may be necessary or desirable to neutralize any small amounts of hydrochloric acid which may be present, for example, with lime.

Itwill accordingly be seen that by treat ing oil gas in the manner described, a mixture of ethylene hydrocarbons is obtained which can be used directly for the production of a Dutch liquid, of a relatively stable nature, substantially free from objectioning the ethylene and propylene from the hydrogen and saturated and higher unsaturated hydrocarbons, and subjecting the resulting mixture of ethylene and propya co-solvent of both the chlorin and the ethylene hydrocarbons, whereby the chlorination is eflected in a smooth and easily regulated manner.

3. The method of producing a mixture of dichlorinated ethylene hydrocarbons, which comprises passing amixture of ethylene hydrocarbons and chlorin separately into a cosolvent of the chlorin and of the hydrocarbons and thereby effecting the chlorination of the dissolved materials in a smooth and easily regulated manner.

4. The method of producing from oil gas a mixture of dichlorinated ethylene hydrocarbons consisting principally of ethylene and propylene dichlorids, which comprises subjecting the oil gas to a preliminary fractional liquefaction and rectification and thereby separating the ethylene and propylene from the hydrogen and methane and from the higher unsaturated hydrocarbons, whereby a mixture of ethylene and propylene is produced relatively free from hydro gen and other hydrocarbons, and subjecting the resulting gaseous mixture to the action of chlorin by passing the gases and the chlorin separately into a'co-solvent of both the chlorin and the hydrocarbons, which cosolvent contains dichlorinated ethylene hydrocarbons resulting from the reaction, whereby a mixture of dichlorinated ethylene hydrocarbons consisting principally of dichlorinated ethylene and propylene is obtained in a smooth and easily regulated manner.

5. The method of chlorinating ethylene hydrocarbons, which comprises introducing the same and chlorin separately into a body of a co-solvent of both the chlorin and of the ethylene hydrocarbons, which co-solvent is made up of the dichlorinated ethylene hydrocarbons resulting from the reaction, whereby the chlorination is effected in a smooth and easily regulated manner.

6. The method of producing a mixture of dichlorinated ethylene hydrocarbons consisting essentially of dichlorinated ethylene and propylene, which comprises passing a gaseous mixture consisting essentially of ethylene and propylene, and chlorin, separately into a co-solvent of the chlorin and of the hydrocarbons, whichco-solvent is made up of the chlorinated ethylene hydrocarbons produced during the reaction, whereby the chlorination of the mixture of hydrocarbons is effected in a smooth and easily regulated manner.

In testimony whereof we 'affix our signatures.

BENJAMIN T. BROOKS. DILLON F. SMITH.

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