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. The wa of methyl chloride from hydrogen chloride and ter withdrawn through line 23 may be treated in unreacted methane. Line. I I connects with frac a separator, not shown, to extract methyl chlo tionator 3 whereby the cooled reaction products ride which may be dissolved therein. The re are introduced into fractionator 3 to effect sub 50 maining mixture of methyl chloride and uncon stantially complete separation therein of methyl verted methane is then withdrawn from the up chloride from hydrogen chloride and unconverted per portion of fractionator 4 through line I4 and methane. The methyl chloride is collected in transferred to fractionator 3 for fractionation liquid form in the lower portion of fractionator therein, as described above. > 3 and may be Withdrawn therefrom through line 55 In accordance with another modification of I3. Additional quantities of methyl chloride and the invention, a separate fractionator 5 may be unconverted methane are introduced into frac provided for treatment of the products from the tionator 3 through line I4 from a source to be catalytic conversion zone 2. According to this described below. The material introduced into modification all or substantially all of the mix fractionator 3 through line I4 is fractionated 60 along with the material introduced through line ture of methyl chloride and unconverted meth II and the combined methyl chloride product ane withdrawn from fractionator 4 through line from both sources is withdrawn` through line I8. I4 is diverted through line 24 and transferred The mixture of unconverted methane and hy thereby to fractionator 5. In fractionator 5 con drogen chloride is withdrawn overhead from 65 ditions of fractionation similar to those obtaining fractionator 3 through lineA I5 which connects in fractionator 3 are maintained whereby methyl with the entrance of catalytic conversion zone chloride is separated as a condensate and with 2. Line I5 connects also with line 9. By suit drawn through line 25. Unconverted methane able manipulation of valve I6 in line I5 and valve is separated as a gas and withdrawn overhead I'I in line 9 the mixture of hydrogen chloride and 70 from fractionator 5 through line 26. Line 26 methane withdrawn from fractionator 3 through connects with line 9 whereby the methane from line I5 may be apportioned as desired between fractionator 5 may be recycled directly to ther thermal conversion zone I and catalytic conver mal conversion zone I. ‘ In accordance with this sion zone 2. As stated above, preferably this modiñcation, valve I'I preferably would be closed apportionment should be controlled to send to 75 and valve 21 in line I4 would be employed to 2,834,083 3 restrict or prevent the transfer of material from of other alkyl chlorides and alkyl bromides and fractlonator 4 directly to fractlonator 3. it is capable of other modifications involving re Preferably the quantities of reagents charged action conditions particularly adapted for the to the conversion zones should be regulated to treatment of other reagents. provide for a preponderance of methane to the I claim: other reagents. Advantageously the proportions 1. A process for the production of alkyl halides of reagents charged to thermal conversion zone l which comprises heating a halogen selected from should be regulated to produce therein a molec the group consisting of chlorine and bromine, in ular ratio of methane to chlorine which is ap the presence of an excess of low-boiling paraflln proximately 5:1. Advantageously also the mo 10 hydrocarbons, to effect thermal conversion of lecular ratio of methane to hydrogen chloride in said halogen to alkyl halides and hydrogen conversion zone 2 may be maintained at approxi halide, fractionating the products of said thermal mately 4:1. conversion operation to separate the alkyl halides A distinct advantage has also been found in contained therein from hydrogen halide and having some hydrogen chloride in the thermal 15 unconverted'low-boiling parañin hydrocarbons, conversion zone I in accordance with the pre contacting at least a portion of said hydrogen ferred modification. The presence of the hy halide and said unconverted low-boiling paraffin drogen chloride seems to eiîect a speeding up of hydrocarbons with oxygen in the presence of a the reaction and at the same time (possibly as a catalyst at elevated temperature to effect con consequence) favors the selective production of 20 version of said hydrogen halide to alkyl halides methyl chloride at the expense of reduced yields and water, fractionating the products of said cat of the more highly chlorinated methanes. Other alytic conversion operation to separate therefrom gases, particularly hydrogen, have shown a simi water and alkyl halides, and recycling uncon lar effect. verted low-boiling paraffin hydrocarbons con Fractionators 3, 4 and 5 may be provided with 25 tained in the products of said catalytic conver suitable cooling means 28, 29 and 30, respectively, sion operation to said thermal conversion opera in the upper portions thereof to maintain the de tion. sired iractionating conditions. 2. A process for the production of alkyl halides An illustration of the operation of the inven which comprises heating a halogen, selected from tionin accordance with the preferred modification 30 the group consisting of chlorine and bromide, in for the production of methyl chloride from chlo the presence of an excess of low-boiling parafûn rine and methane is indicated in the following hydrocarbons, to effect thermal conversion of table, which is based 0n the treatment of said halogen to alkyl halides and hydrogen 1,000,000 cubic feet of methane per day. Under halide, separately subjecting a mixture of said optimum conditions conversion of about 90% 0f 35 hydrogen halide and low-boiling paraffin hydro the methane and chlorine is possible. This il carbons to contact with oxygen in the presence lustration therefore provides for the production of a. catalyst at elevated temperature to effect of approximately 127,000 pounds of methyl chlo conversidn of said hydrogen halide to alkyl ride per day. However, in the table the quan halides and water, fractionating the products tities of materials flowing to and from various 40 of said thermal conversion operation and said parts of the process are based on 100% recovery catalytic conversion operation to separate there of the chlorine reacted as methyl chloride, small from alkyl halides, water, and a mixture of hy losses and the production of higher chlorinated drogen halide and unconverted low-boiling paraf methanes and higher chlorinated hydrocarbons ñn hydrocarbons, recycling a major proportion being ignored to simplify presentation of the sub of said mixture to said catalytic conversion op ject matter. In the table the figures represent eration, and recycling the remaining minor por cubic feet per second and the composition of the tion of said mixture to said thermal conversion materials entering and leaving each phase of the operation. _ process is indicated. 3. A process 1n accordance with claim 2 where Table

Entering Leaving

om Cn o: HC1 omo] H20 om HC1 emol H10

'Freshfeed (1inese,s,19)._-__ 11.57 M9 2.89 zone 1 ______29. 92 5. 79 4.34 23914 10.13 5.79 ______zone 2 23.14 2. e9 a 79 17. as 5. 79 a 79 Fractionator 3 ______. 40. 50 10. 13 11. 57 40. 50 10. 13 ...... -_ Fmnonmr 4 17. 3c s. 79 5.79 17. as 5.79

In each conversion zone the heat available at in the said mixture of hydrogen halide and un heat exchanger l2 and heat exchanger 22, and converted low-boiling paraffin hydrocarbons is the heat of reaction are more than sufficient to charged- to said catalytic conversion zone in an provide the heat necessary to heat the gas. The 65 amount whereby the molecules of hydrogen halide amount of external heat necessary to maintain charged to said catalytic conversion operation the process is, therefore, quite small. equal the molecules of halogen charged to said The improved process as described above pro thermal conversion operation. vides an eilicient and economic method of effect 4. A process for the production of methyl chlo ing the conversion of low molecular aliphatic hy 70 ride which comprises heating. chlorine in the pres drocarbons such as methane to alkyl chloride or ence of an excess of methane to eiîect thermal alkyl bromide. The foregoing illustration refers conversion of said chlorine to methyl chloride and speciñcally to the production of methyl chloride. hydrogen chloride, separately contacting hydro It should be understood, however, that the inven gen chloride and methane with oxygen in the tion is capable of application to the production 75 presence of a catalyst at elevated temperature to 4 2,334,033 eñect conversion of said hydrogen chloride to mon zone to separate therefrom water, methyl methyl chloride and water, iractionating the chloride and a mixture oi hydrogen chloride and products of said conversion operations to separate unconverted methane, recycling to the catalytic therefrom methyl chloride, water and a mix conversion operation as the charge therefor a ture of hydrogen chloride and unconverted 5 portion of said mixture of hydrogen chloride and methane, recycling a major proportion of said methane containing a volume or hydrogen chlo mixture oi' hydrogen chloride and methane ride equal to the volume of chlorine charged to the to said catalytic, conversion operation as the thermal conversion operation, and recycling the charge therefor, and recycling the remain remaining portion of said mixture of hydrogen ing minor proportion of said mixture to said 10 chloride and methane to the thermal conversion thermal conversion operation as a portion of thc operation. _ charge therefor. 9. A process for the production of alkyl halides 5. A process in accordance with claim 4 where which comprises heating a halogen from the in the molecular ratio of methane to chlorine group ,consisting of chlorine and bromlne in the charged to said thermal conversion operation is 15 presence oi an excess oi low-boiling paraflln hy approximately 5 to 1. drocarbons to eû‘ect thermal conversion of said 6. A process in accordance with claim 4 where halogen to alkyl halides and hydrogen halide, in the molecular ratio of methane to hydrogen simultaneously in a separate zone contacting hy chloride charged to the catalytic conversion op drogen halide produced in said thermal conver eration is approximately 4 to 1. 20 sion operation and unconverted low-boiling par 7. A process in accordance .with claim 4 where ailin hydrocarbons with oxygen in the presence in the thermal conversion operation is effected at of a catalyst at elevated temperature to eñîect approximately 1500*’ F. and a relatively short re conversion of the said hydrogen halide to alkyl action time,'and the catalytic conversion opera-A halides and water, fractionating the products of tion is effected at approximately 800° F. `with a 25 said conversion operations to separate water and relatively long reaction time. alkyl halides from hydrogen halide and uncon 8. A process for the production of methyl chlo verted low-boiling parailin hydrocarbons, pass ride which comprises heating chlorine in the ing hydrogen halide thus ­separated and at least a presence of an excess of methane to effect thermal portion of the unconverted low-boiling paramn conversion of said chlorine to methyl chloride 30 hydrocarbons thus separated to the catalytic con and hydrogen chloride, separately contacting hy version reaction as the charge therefor, and re drogen chloride and methane with oxygen in the cycling the remaining unconverted low-boiling presence of a catalyst at elevated temperature to parañin hydrocarbons to the thermal conversion eiïect conversion of said hydrogen chloride to operation. methyl chloride and water, fractionating the 35 EARL W. RIBLE'I'I'. products of said conversion operations in a com CERTIFICATE, oF CORRECTION. Patent No. 2,55Lho55. November 9, 19145. ` EARL w. 'RIBLETT.

It is hereby certified that error appears in the printed specification of the ábove _numbered patent requiring correction as fellows: Page 5, se'c ond cclumn, line 50, claim 2, for "bromidelread --bromine--g and that the said Letters Patent should be `read with this correction therein that the 'same may Confo'nn to the record of the esse in the Patent Office. signed and sealed. this man ¿ay Cf January, A. D. 19h14.

_ Henry Van Arsdale, (Seal) v Acting­ Commissioner >of Patents.