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Nov. 9, 1943. E Nov. 9, 1943. E. w. RIBLETT 2,334,033 PRODUCTION OF ALKYL HALIDES Filed July 50,­ 1940 ÈHÑL W R/BLETÍ.' INVENTOR BY LA Í# »Q ATTORNEY. Patented Nov. 9, 1943 42,334,033 UNITED STATES PATENT OFFICE 2,334,033 _PRODUCTION 0F~ ALKYL HALIDES Earl W. Rîblett, Tenañy, N. J., assignor to Process Management Company, Inc., of Wilmington, Del., a corporation of Delaware Application July 30, 1940, Serial No. 348,598 9 Claims. (Cl. 260-662) This invention relates to improvements in the cycled to the catalytic conversion zone and the production of alkyl halides. More particularly, >remaining minor proportion is recycled to the the invention relates to the reaction of chlorine thermal conversion zone. In dividing this mix or bromine with certain low molecular weight ture for recycling it is advantageous to recycle aliphatic hydrocarbons to effect conversion to the catalytic conversion operation a quantity thereof to the corresponding alkyl halides. Still of the mixture containing ra, volume of hydrogen more particularly, the invention relates to the chloride equal to the volume of chlorine charged improvements in the reaction of chlorine and to the thermal conversion operation. The re methane to produce methyl chloride. maining minor proportion of this mixture may In the improved process of the present inven 10 then be recycled to the thermal conversion zone tion, chlorine (or bromine) is reacted with a low to assist in maintaining in that zone the excess of molecular weight aliphatic hydrocarbon, such as methane which should be maintained in rela methane, in a combination of steps whereby con- ` tion to the quantity of chlorine charged thereto. version of the halogen and hydrocarbon react In accordance with a second modification of ants to alkyl halides is effected under conditions the invention, the conversion products of the of maximum efficiency, In the further explana thermal and catalytic conversion zones are sepa tion of the invention the reactants will be re rately fractionated. In accordance with this ferred to as chlorine and methane but it is to be modification the products of the thermal con understood that reference to these specific re version treatment are fractionated to separate agents is merely for purposes of simplicity. In 20 methyl chloride and all of the remaining mixture stead of chlorine, bromine may be employed, and of unconverted methane and hydrogen chloride low molecular weight aliphatic hydrocarbons is passed 4to the catalytic conversion treatment other than methane may be employed, such as as the charge therefor in admixture with oxygen ethane. ' from an external source. The product from the In accordance with the new process the re 25 catalytic conversion zone is then separately frac action is carried out in two separate zones. In tionated to remove water and methyl chloride one zone, chlorine and an excess of methane and the remaining unconverted methane is re are reacted at a relatively high temperature and cycled in its entirety to the thermal conversion for a relatively short time to eñect thermal con zone. version of the chlorine to methyl chloride and 30 The first modification of the invention de hydrogen chloride. These products are frac scribed-above is preferable in view of the fact tionated to separate the methyl chloride. The that the separate fractionation treatments in the hydrogen chloride and the unconverted methane second modification require more extensive equip are reacted in another conversion zone wherein ment and involve more complicated operations, methane, hydrogen chloride and oxygen are re 35 which render it less desirable from an economic acted in the presence of a suitable catalyst at a point of view­ Furthermore, the presence of hy- v relatively lower temperature and for a substan drogen chloride in the charge to the thermal con tially longer reaction time to eiîect conversion version zone appears to assist the reaction of the hydrogen chloride and a portion of the therein. methane to methyl chloride and water. Uncon 40 The invention will be described in more detail verted methane from this catalytic conversion by a reference to specific modifications which zone may be separated and recycled to the ther are illustrated in the flow diagram shown in the mal conversion zone for reaction with fresh sup accompanying drawing. The specific modifica plies of chlorine. tions illustrated in the drawing will be referred In accordance with one modification of the in 45 to for purposes of illustration, but it is under vention the products of both the thermal and stood that the invention is not limited by refer the catalytic conversion treatments, after re ence to such specific modifications but is capable moval of water produced in the catalytic con 4 of other modifications which may be beyond the version treatment, are fractionated in a single scope of the iiow diagram shown in the drawing. zone to separate the methyl chloride produced in 50 In the drawing the apparatus shown diagram the two conversion zones as the product of the matically includes a thermal conversion zone I process. The remaining mixture of unconverted and a catalytic conversion zone 2. The products methane and hydrogen chloride is then recycled of these conversion zones preferably are frac in part to each of the conversion zones. Pref tionated together in fractionator 3. A fraction erably a major­ proportion of this mixture is re 56 ator 4 or other suitable separating means is pro 2 2,834,033 . - vided for separating water from the product of the entrance of catalytic conversion zone 2, catalytic conversion zone 2. A third fraotionator through line I5, an amount of this mixture of E may be provided in order to effect fractionation reagents which contains a. volume of hydrogen of the products from the thermal conversion zone chloride equal to the volume of chlorine intro 2 in a zone separate from that in which frac duced through line 0. ~ tionation of the products of thermal conversion The portion of the mixture of methane and zone I is carried out. hydrogen chloride to be charged to the catalytic In the operation of the preferred modifica conversion zone 2 is transferred thereto by means tion of the invention. chlorine is introduced into of a pump I8 located in line I5. Oxygen is in thermal conversion zone I through line 6 pro 10 troduced into catalytic conversion zone 2 through vided with a pump 1. Methane is introduced into line I9 provided with pump 20 for reaction with the process through line 8 which connects with methane and hydrogen chloride in zone 2. line 9. In line 9 the methane introduced through In catalytic conversion zone 2 the reactants line 8 is mixed with additional methane, and ac­­ are subjected to the action of a suitable catalyst companying hydrogen chloride, being recycled to 15. at a temperature of 600•1000° F., preferably about thermal conversion zone I. Line 9 is provided 800° F. for a time suflicient to provide a react-ion with a pump I0 by means of which the methane time of the order of 20 to 100 seconds, prefer and accompanying hydrogen chloride are passed ably approximately 50 seconds, for the produc to the entrance of thermal conversion zone I. tion of methyl chloride. Under these conditions In thermal conversion zone I the reactants 20 there is effected almost complete conversion of are subjected to a high temperature in the range the hydrogen chloride largely to methyl chloride of 1000-1800° F. When the object is to produce and water by reaction thereof with oxygen and methyl chloride as the major product a tem methane. , perature of about 1500“ F. and a contact time of Catalysts suitable for use in conversion zone 2 the order of 0.01 second is preferable. It has 25 include a wide variety of mixed metallic oxides been found possible to use a lower temperature and chlorides, preferably on porous supports. and a longer time to eiïect the conversion but Among the metals found suitable are titanium. this has usually resulted in higher yields of sec zirconium, cerium, thorium, copper and silver. ondary, tertiary, and quarternary chlorinated Eflicacious supports are kieselguhr, silica gel, ac products at the expense of a decreased yield of 30 tivated alumina,alumina gel and pumice. From methyl chloride. Carbon tetrachloride or either an economic standpoint, the combinations of of the other two intermediate chlorinated prod cerium and pumice and of copper and pumice ucts may be made the chief product by suitable are preferable and may be made by simply soak selection of time of contact and temperature to ing the pumice in a solution of the metal chlo gether with an increased amount of chlorine rel 35 rides or agitating the pumice with a partially ative to methane. precipitated metallic salt and hydroxide suspen Under the conditions specified, 1500” F. and sion, followed by drying. 0.01 second time of contact, practically complete The reaction products are withdrawn from conversion of the chlorine to methyl chloride and catalytic conversion zone 2 through line 2| and hydrogen chloride is effected. The hot reaction 40 after suitable cooling, for example, by contact products are withdrawn from thermal conversion with the incoming charge in heat exchanger zone I through line II and are cooled, for ex 22, are introduced into fractionator 4 or other ample, by passage through heat exchanger I2 suitable means for effecting separation of water wherein they contact indirectly the incoming from the reaction products. .In fractionator 4 fresh feed to the reaction, and by other suitable ' water is condensed and separated and may be cooling means not shown, to effect condensation withdrawn therefrom through line 23.
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