Patented Aug. 17, 1948 2,446,998 UNITED STATES PATENT OFFICE 246,998 PROCESS OF CATALYTICALLY TREATING HYDROCARBONSWTE YOROGEN FLUO. RDE, AND BORON TRFLUOR DEN THE PRESENCE OF BY DROGEN Robert E. Burk, Cleveland eights, Ohio, assignor to The Standard Oil Company, Cleveland, Ohio, corporation of Ohio . . No Drawing. Application November 20, 1943, serial No. 51,106 4. Clains. (C. 260-683.5) 2 This invention relates to the treatment of hy most temperatures and pressures encountered in drocarbons with a liquid catalyst comprising pri hydrocarbon treating processes. However, boron marily hydrogen fluoride and a minor amount trifluoride dissolves to a given extent in liquid of boron trifluoride in the presence of hydrogen. hydrogen fluoride and the amount that dissolves It is an object of the invention to treat hydro 5 depends on the partial pressure of the boron tri carbons to alter their molecular weight and/or fluoride at any given temperature. At higher chemical configuration, using as a catalyst therer partial pressures larger amounts of boron tri for hydrogen fluoride and boron trifluoride, said fluoride are dissolved in hydrogen fluoride. Thus treatment being carried out in the present of the the composition of the catalyst, i. e., the rela hydrogen. O tive proportions of the two flourides, may be re A further object of the invention is the provi garded as a function of the amount of boron tri sion of a process in which products are formed fluoride dissolved in the liquid hydrogen fluoride which have great value as compared with the and therefore as a function of the partial pres starting materials. Sure of the boron trifluoride. Still an additional object of the invention is to The amount of boron trifluoride dissolved in provide a process in which unsaturates can be the hydrogen fluoride, at any given temperature, converted to saturates, although not necessarily may be expressed conveniently in terms of the having the same number of carbon atoms. partial pressure of boron trifluoride. This may A further object of the invention is the pro vary in accordance with the invention from a vision of a process in which the amount of hydro 20 trace up to 550 pounds per square inch. Gen carbon which becomes combined or associated erally about 5 to 300 pounds per square inch will with the catalyst phase is small, thereby avoid be used. However, the amount should under no ig degradation of the stock used as a starting circumstance exceed 50 mol per cent of the raterial in the process. fluorides. With the partial pressures usually The process of the invention is applicable to a 25 used, the amount dissolved does not exceed 15 wide variety of hydrocarbon reactions, among mol per cent. The words “dissolve” and 'solu which may be mentioned isomerizing, such as the tion' are used as generic to both a physical ad isonerization of butane, pentane, and hexane, mixture and any possible reaction product. and other aliphatic hydrocarbons as well as ali If the hydrocarbon reacting ingredients include cyclic hydrocarbons, such as naphthenes, as well 30 an olefin, such as in an alkylation process, or if as aromatics with side chains, etc., to form an olefin is introduced or formed in any of the isomers thereof, or the isomerization of natural above processes as a promoter, the available evi gasoline to improve its knock rating; cracking dence indicates that the hydrogen fluoride-boron hydrocarbons; averaging hydrocarbons in which trifluoride solution, or any reaction product, may lower and higher molecular Weight hydrocarbons 35 form a new compound or chemical complex which are reacted to yield hydrocarbons of intermediate may be an ingredient of the catalyst. molecular weight; alkylating isoparaffins and aro It is inmaterial in accordance with the inven matics; and converting propane to a higher tion whether the catalyst is hydrogen flouride molecular weight hydrocarbon by treatment alone promoted by boron trifluoride or also promoted or in the presence of pentane, 4) by an olefin. Liquid hydrogen fluoride, in which a minor The ingredients comprising the catalyst may be amount of boron trifuoride is dissolved, is an brought together in any order or simultaneously. admirable catalyst for effecting a wide variety Generally it is convenient to feed the two fuo of hydrocarbon reactions, including those men rides to the hydrocarbon reaction zone in admix tioned above as well as many others. In addition ture under the desired boron trifluoride partial to effecting the reactions, the catalyst is desir pressure, although they may be introduced sepa able because of the fact that hydrogen fluoride is rately if desired. If an olefin is to be added as a a liquid at about room temperature and lower promoter, this may be absorbed in the fiuorides, temperatures, and may be kept in the liquid or may be fed to the reaction Zone separately or phase at temperatures and pressure at which 50 along with any hydrocarbon materials being hydrocarbons are conveniently treated. However, treated; it may comprise % to 25 weight per cent because of its relatively low boiling point it may of said hydrocarbons. be removed readily from the hydrocarbons after One of the advantages of the catalyst above the completion of the treating operation. Boron described is the ability to adjust the activity of trifluoride is a gas (boiling point: -50 F.) at 55 the catalyst through control of its composition. 2,446,998 3 4 This may be accomplished by varying the partial hydrogen fluoride (based on the hydrocarbon) in pressure of the boron trifluoride inasmuch as a which boron trifluoride was dissolved in an change in this partial pressure results in a change amount to provide a partial pressure of boron in the amount of boron trifluoride dissolved. If trifluoride of 150 pounds per Square inch. The the partial pressure of the boron trifluoride is in reaction was carried out by mixing the hydrocar creased, by admitting borontrifluoride to the re bon and the catalyst with agitation for a period action zone from a high pressure source of Sup of 60 minutes at a temperature of 90°F., and in ply, the amount dissolved is increased and the the presence of hydrogen to provide a total pres activity of the catalyst is greater. If this partial sure of 1000 pounds per square inch. The fol pressure is decreased, by bleeding boron triflu ) lowing table shows a comparison of the stock oride, the amount dissolved is decreased. When treated and the products obtained: an olefin is present the activity of the catalyst Stock: may be adjusted by varying the amount of the Weight per cent of charge olefin, Normal pentane------92 Another advantage of the catalyst is the fact 5 Amylene------8 that hydrogen fluoride and boron trifluoride may Product: be completely recovered as such at the conclusion Less than butane (propane).------0.2 of the catalytic treating operation if desired, and Isobutane------13.0 can be reused. This is an advantage not attend Normal butane------O.O ant with the use of metal halides. 20 Another advantage of the catalyst is the ability Isopentane------34.8 to carry out the operation in a liquid phase, be Normal pentane------38.5 cause the catalyst and hydrocarbon may be main Above pentane------16.2 tained in a liquid phase at appropriate tempera Lower layer hydrocarbon------0.0 tures and pressures. Since the hydrocarbon and 25 The product from the reaction in the presence the liquid catalyst are relatively insoluble in each of hydrogen appears very favorable in a number other, they separate as two phases at the end of ways. The amount of propane formed is neg of the treating operation, and the bulk of the cat ligible. The yield of isobutane is substantial and alyst can be separated by settling and decanting is particularly significant in view of the fact that or by centrifuging. The catalyst phase is often 3) no normal butane is formed. In view of this fact, referred to as the "lower layer' because it is the isobutane may be readily separated for use in heavier than the hydrocarbon phase. However, alkylation processes. The yield of isopentane is since the catalyst can be placed in a vapor phase desirably large and as this is a valuable product, at temperatures not too high above room temper this aspect of the process is significant. The ature, unless very high pressures are used, the op fraction boiling higher than pentane was a gaSo eration can be carried out with the catalyst in the line of very good quality, the octane number vapor phase, and also one or more of the reacting (A. S. T. M.--4 cc. TEL/gal.) being. 105.5. The ingredients or the final product may be in the conversion of the charge to products other than vapor phase if this is desired. The flexibility of normal pentane, all of value, is 64.2 per cent of the catalyst, and the ability to use it in liquid or the charge, and the unconverted normal pentane vapor phase operations at temperatures and (35.8 per cent) may be recycled for further treat pressures not too high above nor too low below ment. The process may be carried out in the room temperature and atmospheric pressure, is presence of butanes if it is desired to minimize an important advantage. My invention, however, butane formation and the isobutane formed or contemplates primarily an operation in which the part of it may be recycled. catalyst is in the liquid phase as it is in this A similar process of treating pentane without method of operation that the advantages of the amylene, and not utilizing hydrogen, results in invertion become more significant. about 12% hydrocarbons lost in the lower layer. A possible disadvantage of the use of the cat This amount would be greater when amylene is alyst, prior to my invention, is the fact that a used. portion of the hydrocarbon being treated tends The above process may be carried out with nor to form a complex with the catalyst, which hy nial pentane without amylene. However, since drocarbon is retained in the liquid catalyst phase. the presence of unsaturates tends to increase low This condition is particularly noticeable when er layer formation, the illustrative example se an olefin is present or when cracking takes place lected used unsaturates to demonstrate the ad so that olefins are formed. While the catalyst vantages of the invention. Similarly the process may be recovered from the lower layer, there is may be applied to the isomerization of butane, some risk of degrading the hydrocarbon so that it which may be carried out in the presence of bu is of lower value. Also the recovery adds to the tenes, and to the isomerization of hexanes alone processing operations required. As a result, the 30 or in the presence of Ce or lower olefinS. Natural minimizing of lower layer formation is very im gasoline may be treated similarly to increase the portant. branched chain hydrocarbon content. I have discovered that all of the advantages of As illustrative of another embodiment of my using hydrogen fluoride with boron trifluoride as invention, ethylene is treated with the above de a catalyst above enumerated and others inherent scribed catalayst in the presence of hydrogen to therein may be retained, and that the disadvan form ethane. In accordance with this example, tages may be eliminated to a large extent, even hydrogen and ethylene were mixed in the ratio when an olefin is present in the process, if the of 57.4% ethylene. The reactor was charged with reaction is carried out in the presence of added 600 cc. of liquid HF and boron trifluoride in an hydrogen. amount to provide a partial pressure of 150 pounds The following example will further illustrate per square inch. Hydrogen was then introduced the advantages and the results that may be ob into the reactor to provide a partial pressure of tained in accordance with the invention: A C5 500 pounds per square inch. Following this the stock consisting of 92% normal pentane and 8% hydrogen-ethylene mixture was fed into the re amylene was treated with 50 volume per cent s actor at such a rate that a temperature of 90 2,448,998 5 6 . F. was maintained and not exceeded. The total in which primarily isomerizing is accomplished reaction time was 60 minutes. The feeding of by my new process. However, the isobutane pro the hydrogen-ethylene mixture was stopped when duction indicates some cracking and the gasoline the total pressure reached 1000 pounds per square production indicates some alkylating probably at inch. After this the gas in the reactor was bled 5 tributable mostly to the amylene present in the out through caustic scrubbers, and collected. The charge stock, liquid catalyst phase was siphoned off and "Averaging” requires conditions which are suit analyzed for hydrocarbon Content. able for cracking and alkylating, and the catalyst Analysis of the products formed showed 9.5% in general should be powerful, but the tempera of the ethylene charged was in the catalyst phase. O ture should not be too high. There was a relatively large material loss (nearly The temperature, composition of the catalyst, one-half), and 45.5% of the ethylene charged time of contact and other factors are more or was recovered in the gaseous phase; the loss of less interdependent. For example, if a lower 46% is attributable to the technique employed. . temperature is used, a somewhat larger amount of However, of the 45.5% of the gases recovered, catalyst may be present or a somewhat higher 96.7% was ethane; 43% of the ethylene charged partial pressure of boron trifluoride may be pres was recovered as ethane. ent, or both, to obtain the same result as would The conditions under which the process is car be obtained with a higher temperature and a ried out will vary with the reaction it is desired lesser amount of catalyst or a lower partial pres- *** to effect as well as upon the starting materials 20 sure of boron trifluoride. While the range of and the products wanted. In general, the tem temperature, time of contact, amount of catalyst, perature may vary from -30° to 250 F. Gen partial pressure of the boron trifluoride, etc., may erally a range from 32°F. through room tempera be the same for all of the hydrocarbon treating ture to 190° E. is preferred. It is an advantage processes, this does not mean that the same con of the new catalyst that extreme temperatures ditions can be used to effect different processes. in either direction are not needed. For example, mild conditions for isomerizing with The amount of the liquid catalyst used in the out cracking may be obtained at a given high process may vary, depending upon the reaction temperature by using a low partial pressure of and upon other conditions, and may be from 1 to . boron trifluoride. Thus for almost any tempera 300 volume per cent based on the liquid hydro- : ture a given mild or given drastic condition may carbons to be treated. Amounts of the order of be obtained by adjusting other variables, such 5 to 100 volumes per cent are generally used. aS amount of catalyst, time of contact, the boron The hydrogen fluoride and the boron trifluoride trifluoride partial pressure and composition of may be the commercially available grades. It is. reactants. It is an important aspect of the in not necessary to have chemically pure fluorides. vention that in addition to varying temperature, The impurities in the commercial grades includ the amount of catalyst, the time of contact, etc., ing water, which as a general rule are present in which are variables the prior art has usually an amount of not over 1%, do not interfere with available, the catalyst provides a new variable the operation of the catalyst in my process. In through the control of partial pressure of boron view of the economic advantages of using the com 40 trifluoride. mercial grade, this is preferred, and was used in The partial pressure attributable to the pres the following examples. ence of hydrogen, which, in general, will be the The time of contact between the hydrocarbon total pressure less the partial pressure of boron and the catalyst may vary with the temperature, trifluoride and any pressure attributable to the thoroughness of contact between the hydrocarbon hydrocarbons and hydrogen fluoride may vary and the catalyst, and other factors, and depending OVer a Wide range, depending upon the reaction. upon such other factors the time should be se In instances where lower layer formation is not lected to give optimum yields. This will be from a particularly critical problem it will not be nec a few minutes to several hours. With thorough essary to employ as large an amount of hydrogen ness of mixing possible in a commercial embodi as in instances where severe cracking occurs and ment, the time may be reduced materially below lower layer formation is aggravated. Generally that indicated in the examples. Commercial Con a partial pressure of hydrogen within a range of siderations indicate the time necessary should 50 to 2000 pounds per square inch is indicated. be the minimum to permit the reaction to go to When the process is to be applied to cracking the desired extent under the other operating con it is generally preferred to apply it to stocks ditions. Somewhat heavier than that given in the above The amount of borontrifluoride as represented example, such as naphthas and other cracking by its partial pressure has been indicated hereto stocks. The operations may be carried out in fore in describing the composition of the catalyst. the presence of olefins and/or light stocks such The total pressure preferably is sufficient to keep 60 as n- and iso-butanes and pentanes and these the catalyst in the liquid phase at the tempera may be recycled to the reaction zone. Somewhat ture employed, and preferably also to keep hydro more drastic conditions are used when the process carbons liquid at the temperature employed, un is applied to cracking. The advantages of the less the operation is to be in the vapor phase. invention are particularly significant, when ap-: , , In general, milder conditions may be used for plied to cracking. When the process is to be ap isomerizing, and since desirable equilibrium con plied to "averaging,' a low-molecular weight hy ditions in general indicate lower temperatures, the drocarbon, such as butane or pentane and a high mild conditions are obtained preferably by using er molecular weight hydrocarbon, such as kero a lower temperature. Such conditions can also Sene, naphtha or gas oil, are reacted in the pres be obtained by a lower partial pressure of boron ence of the catalyst and in the presence of hy trifluoride. Cracking requires somewhat more drogen to form hydrocarbons of molecular weights drastic conditions and higher temperatures; a intermediate of the molecular weights of the larger amount of catalyst, higher borontrifluoride two reacting materials. An olefin may be pres partial pressures, etc. may be used. ent as a promoter. The unreacted hydrocarbons, The first example may be viewed as a reaction including butane or pentane, or isomers thereof 2,446,998 7 - formed in averaging, may be recycled to the re the hydrocarbon in the same or a different proc action zone, as well as unwanted products formed ess. Since the catalyst will not have become see in the reaction. . riously degraded as a result of forming a complex, In alkylation processes an isoparaffin or an , the process is particularly adapted to a continu aromatic is reacted with an olefin, preferably 5 ous process in which the catalyst is reused. with the isoparaffin or an aromatic in excess. s On the other hand, if the hydrocarbon builds up The catalyst used in accordance with the in in the catalyst phase or the catalyst becomes de vention, namely, liquid hydrocarbon fuoride con activated through continuous use, it may be de taining a minor proportion of boron trifluoride sirable to withdraw a portion or all of the catalyst dissolved therein, may be used in dearomatizing phase. and subject it to a relatively high tempera or desulfurizing processes, and hydrogen may be ture, for example 250 to 600 F. At this tempera used in connection with the same. In accord ture the fluorides are liberated from the catalyst ance with this embodiment of the invention a phase as gases and can be collected and condensed hydrocarbon fraction containing aromatics and/or compressed and returned to the mixing and/or sulfur compounds or both, is treated with zone or stored or otherwise used. The catalyst the catalyst in the liquid phase under mild con may be subjected to this temperature in a con ditions and for a relatively short time, where ventional pot-type still or by means of flash dis upon the principal action is the removal of a tillation. major portion of aromatics and/or sulfur con Alternatively, instead of distilling the fuorides pounds from the hydrocarbon fraction, depend from the catalyst phase, it may be treated with ing upon the composition of the hydrocarbon a material which exerts a solvent action on the fraction being treated. The aromatics and/or fluorides and which is inniscible with the hydro sulfur compounds are retained in the catalyst carbons in the catalyst phase or which forms a phase probably in the form of a loose chemical chemical compound or complex with the fluorides complex with the fluorides, the latter being re and from which the fluorides may be released leasable in accordance with the procedure men later, for example by heating. Such a material tioned hereinafter. may be dihydroxyfluoboric acid. Another alter Auxiliary hydrogenating catalyst may be pres native is to distill off a part or most of the fluo ent in any of the above-described processes. rides from the catalyst phase and remove the rest The processes are adapted either for batch op by extraction with such a material. The hydro eration or for continuous operation. In the case carbons in the upper layer also can be treated of batch operation, the hydrocarbons to be with such a material to extract any fluorides that treated, hydrogen and the fluorides are brought may be dissolved therein. together in any order in a suitable container or Hydrogen may also be used in the treatment of autoclave where they are preferably Subjected to the lower layer catalyst phase even though the agitation and maintained under the desired tem catalytic operation which resulted in the lower perature and pressure conditions for the required layer formation does not involve the use of hy Iength of time. The boron trifluoride and the drogen. In accordance with this modification the hydrogen partial pressures may be maintained lower layer catalyst phase is subjected to hydro during the reaction from high pressure sources of 4) gen which is thought to hydrogenate the hydro these materials. Following the treating opera carbon-fluorides complex and liberate the fluo tion the materials will stratify when permitted rides which would then be carried off by the par to come to a quiescent state, or if desired, forces tial pressure effects. greater than gravity, Such as centrifuging, may It is desirable that the stock to be treated be be used to effect the separation. The lighter or relatively free from aromatics since aromatics upper layer will contain the hydrocarbons, and tend to form a complex with the catalyst, as has the lower layer will comprise the catalyst. If been mentioned heretofore, and this tends to de the pressure is released the hydrogen and the activate the catalyst. If desired, the catalyst, boron trifluoride may be sent to storage for after being used or reused in any of the hydrocar reuse later. If the temperature is higher than bon treating processes, may be used for, de 67 F, the hydrogen fluoride also will be released aromatizing fresh stock in accordance with the and may be condensed or retained in the gaseous description in my Patent No. 2,343,744, dated phase. However, the separation may be made March 7, 1944. w under pressure and all of the ingredients except In view of the above explanation, one skilled in theiremoved hydrocarbon layer may be retained the art will understand how to practice my proc- . in the autoclave. i. i. ess, and while further explanation or theory is In a continuous process the fluorides, hydro not needed, and I do not intend to be limited to carbons and hydrogen are fed through a continu the same, the following may be of assistance in ous type mixer, for example, a three-stage mixer understanding the invention: where they are maintained at the desired ?tem 60 It appears possible that upon subjecting a sat perature and under the appropriate pressures. urated hydrocarbon to the catalyst the following The rate of flow through the mixer may be ad Jreaction may occur: justed so that the hydrocarbons are in contact with the catalyst for the desired length of time as pre- H. they pass through the mixer. The mixture may 65 then be fed through a separator where it is per *Fir: | -- mitted to stratify. The upper hydrocarbon layer may be continuously withdrawn and fractionated F. (1) and the material not converted to the desired where R is hydrogen or a hydrocarbon residue. products or any part thereof may be recycled to 70 The reaction may continue further: the mixer. The lower layer catalyst phase also E H. H. H. H. may be recirculated to the mixer. . . The catalyst, after separation from the hydro B-----H+HP+BFrer-----H+H, carbon at the conclusion of the treating process may be reused for treating a separate amount of 75 " . . . 2,446,998 9 10 The reaction 2 may proceedin this manner to the hydrogen fluoride liquid at the temperature form heavy materials such as tars which inacti employed, whereby at least a part of said olefin vate the catalyst because a large amount of HF's is converted into saturated hydrocarbons along radical becomes tied in the polymerization prod with the production of isomers of said normal ucts and the products themselves are of low value. paraffin, and the amount of hydrocarbons accu In accordance with my invention I envisage mulating in the liquid catalyst is minimized. that the application of hydrogen forces the re 3. A process of catalytically treating hydrocar action (2) to the left, thereby minimizing the bad -bons which comprises subjecting hydrocarbons effects resulting therefrom and permitting the comprising a normal paraffin and an olefin, in modification in molecular structure of the hydro 10 the presence of hydrogen in an amount to provide carbon in the presence of the catalyst without a partial pressure of hydrogen from 50 to 2000 large quantities of the catalyst permanently com pounds per square inch, to the action of 5 to 300 bining with the hydrocarbons. volume percent (based on the hydrocarbons) of a The expression "hydrocarbon fraction' is used liquid catalyst comprising as its essential catalytic herein as generic to a single hydrocarbon or a 5 ingredients liquid hydrogen fluoride in which is mixture of hydrocarbons of the same or different dissolved not over 50 mol percent of boron trifluo number of carbon atoms. The expression 'mod ride (based on the total fluorides) to provide a ify" is used as generic to a change in molecular partial pressure of boron trifluoride of 5 to 550 arrangement and/or a change in the number of pounds per square inch, continuing the reaction carbon atoms, such as isomerizing, cracking, aver 20 at a temperature of -35 to 250 F. under a total aging, etc. pressure to maintain the hydrogen fluoride liquid My invention is capable of many applications at the temperature employed, whereby at least a and embodiments as will be apparent to one part of said olefin is converted into saturated hy skilled in the art in view of the disclosure herein drocarbons along with the modification of the and all are to be included as one within the scope normal paraffin, and the amount of hydrocarbons of my claims. accumulating in the liquid catalyst is minimized. E claim: 4. A process of catalytically treating hydrocar 1. A process of catalytically treating hydrocar bons which comprises subjecting hydrocarbons bons which comprises subjecting a hydrocarbon Comprising a normal paraffin and an olefin to fraction containing a normal paraffin and an ole 30 the action of 5 to 300 volume per cent (based on fin, in the presence of hydrogen in an amount to the hydrocarbons) of a liquid catalyst comprising provide a partial pressure of hydrogen from 50 as its essential catalytic ingredients liquid hydro to 2000 pounds per square inch, to the action of 5 gen fluoride in which is dissolved not over 50 mol to 300 volume percent (based on the hydrocar per cent of boron trifluoride (based on the total bons) of a liquid catalyst comprising as its essen 35 fluorides) to provide a partial pressure of boron tial catalytic ingredients liquid hydrogen fluoride trifluoride of 5 to 550 pounds per square inch, con in which is dissolved not over 50 mol percent of tinuing the reaction at a temperature of -35 to boron trifluoride (based on the total fluorides) to 250 F. under a total pressure to maintain the provide a partial pressure of boron trifluoride of 5. hydrogen fluoride liquid at the temperature em to 550 pounds per square inch, continuing the re ployed, and in the presence of added hydrogen to action at a temperature of -35 to 250°F, under a Convert at least a part of said olefin into a satu total pressure to maintain the hydrogen fluoride rated hydrocarbon along with the modification liquid at the temperature employed, whereby at of the normal paraffin and to minimize appre least a part of said olefin is converted into Satu ciably the amount of hydrocarbons degraded into rated hydrocarbons along with the modification 45 the liquid catalyst phase. of the normal paraffin, and the amount of hydro carbons accumulating in the liquid catalyst is ROBERTE, BURK. ninimized. REFERENCES CEO 2. A process of catalytically isomerizing hydro The following references are of record in the bons which comprises subjecting a hydrocarbon 50 file of this patent: fraction containing a normal paraffin and an ole fin having the same number of carbon atoms as UNITED STATES PATENTS said normal paraffin, in the presence of hydrogen Number Name Date in an amount to provide a partial pressure of hy 2,158,559 Atwell et al.------May 16, 1939 drogen from 50 to 2000 pounds per square inch, 55 2,172,146 Ruthruff ------Sept. 5, 1939 to the action of 5 to 300 volume percent (based on 2,200,090 Evering et al. ------Nov. 5, 1940 the hydrocarbons) of a liquid catalyst comprising 2,265,870 Schuit ------Dec. 9, 1941 as its essential catalytic ingredients liquid hydro 2,266,012 d'Ouville et al.------Dec. 16, 1941 gen fluoride in which is dissolved not over 50 2,271,043 van Peski------Jan. 27, 1942 Inol percent of boron trifluoride (based on the 60 2,318,226 Ipatieff et al.------May 4, 1943 total fluorides) to provide a partial pressure of 2,325,122 Ipatieff et al.------July 27, 1943 boron trifluoride of 5 to 550 pounds per square 2,344,890 Whiteley ------Mar. 21, 1944 inch, continuing the reaction at an isomerizing 2,357,495 termperature under a total pressire to maintain Bloch ------Sept. 5, 1944 ll - 2 Certificate of Correction Patent No. 2,446,998. . - August 17, 1948. . . . . ROBERT E. BURK . - ... It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 1, line 9, for the word present read presence; line 50, for pressure' read pressures; column 5, line 32, for 'volumes' read volume; column 9, line 3, for “HF,' read BF; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office. . Signed and sealed this 16th day of November, A.D. 1948.

EAL

THOMAS F. MURPHY, A8sistant Commissioner of Patents.