US2255610A - Process of alkylation with chlorosulphonic acid - Google Patents

Description

Patented Sept. 9, 1941 .raocnss F ALKYLATION WITH 1 CHLOROSULPHONIC acm William E. Bradley, Los Angeles, Calif assignor s to Union Oil Company of California, Los Angeles, Calif., a corporation oi California 1 a I No Drawing. Application May 31, 1938,

Serial No. 211,045

8 Claims.

I The present invention relates to the treatment of hydrocarbons, and more particularly pertains to thesynthesis of parafllnic hydrocarbons of a branched chain type especially suitable for use as automobile and aviation engine fuels or as constituents thereof.

In a more specific sense, the invention comprises or includes a process for the combining of (Cl. 196-40) v v vention resides in providing for an eflicient utiliisoparafilnic hydrocarbons of relatively low molecular weight with oleflnic hydrocarbons, which may be normally gaseous or normally liquid, or both, to produce branched'chain paraflinic hydrocarbons boiling within the gasoline range and possessing high antidetonating characteristics. The invention further resides in the discovery'of a new catalyst particularly suitable for eifecting the chemical combination of the low molecular weight isoparafllns with oleflnic hydrocarbons to produce motor fuels having the desired knock-rating characteristics.

Oil cracking processes which are at present in use as -a means of supplementing the supplyof.

gasoline obtainable by the straight run distilla tion of crude oils, and also for producing materials which have higher knock-rating values than these straight run gasolines, result in the formation of considerable quantities of -by-products. The gaseous fractions produced during these cracking operations contain relatively large percentages of oleflnic hydrocarbons, particularly of It is one of the main the normally gaseous type. objects of the present invention to provide a process for a more eflicient utilization of these and other oleiins or olefin-containing gases. Aside from the oleflnic hydrocarbons produced during the above outlined petroleum cracking operations, olefins also occur or result fromgasmaking processes and may be produced as byproducts in various chemical industries as well as by the simple dehydrogenation of paraillnic hydrocarbons. In general, oleflnic hydrocarbons exhibit a high reactivity in their tendency to polymerize and to form substances of higher molecular weight. 0n the other hand, paramnic hydrocarbona such' as isobutane and isopentane, which normally occur in natural gas or similarly related materials, are usually considered to be,

more or less chemically stable and are incapable of polymerizing. v

It is a further object of the present invention to provide for a moreeiiicient utilization of certain of the isoparaiiinic hydrocarbons and the aforementioned and other oleflnic hydrocarbons to produce highly valuable derivatives there- I from. A still further object of the present inzation of the low boiling'isoparailinic hydrocarbons, namely. isobutane, isopentane and isohexane, and of the normally gaseous oleflnic hydro-. carbons including propylene, the butylenes and the 'pentenes, and of the relatively low boiling normally llquid hydrocarbons, 4 to produce branched chain paraflinic hydrocarbons of high anti-detonating characteristics and boiling substantially within the gasoline range.

' The reaction between one or more oleflnic molecules and one or more isoparafiinic molecules produces one or more branched chain paraflinic molecules. This reaction is termed cl-'- kylation" and the product is herein called an alkymer in order to distinguishit from a "polymer which is the product resulting from the interaction of two or more oleflnic molecules. Theoretically, the reaction between an isoparaffln and an olefin in the presence of. a suitable alkylating catalyst, is of a simple character.

Thus, when an isobutane molecule is chemically combined with a butylene molecule, the resultant product is an octane. Thus:

{CH3)8CH a)= z a)a a a)I sobntane isohutene an octane simple chemical combination of isoparamnic vmolecules with oleflnic moleculesintroduced into the reaction sphere. However, as will be brought out hereinbelow, the term alkylation" as employed in this specification includes not only the simple chemical addition of an olefin to an isoparaflin, but also includes the union between certain specified isoparafilnic molecules and oleflnic molecules formed in situ, as by the depolymerization of relatively larger oleflnic molecules As stated above, oleflns, when subjected to proper reaction temperatures and pressures in the presence 'of suitable catalysts, such as sulphuric acid, etc., tend to polymerize and form unsaturated molecules of higher molecular weight. .Under certain conditions of o oration polymerization will occur in preference t alkylation and the reaction products-willbefound to contain only small percentages of alkymers, the

greater proportion of the oleiins having polymerized in preference to their addition to isoparamnic, hydrocarbons.

It is, therefore, another object of the present invention to provide a process whereinthe 0.1-

'to polymerize instead, of alkylate.

kylation of the isoparafl'ins by olefins will be favored in preference to the polymerization of the olefins introduced into the reaction zone. It is a. further object of the invention to provide a process and a catalyst which will effect the combination of the olefins with the isoparaflinic hydrocarbons to produce branched chain paraffinic hydrocarbons-having high anti-detonating 1 characteristics and boiling substantially within the gasoline range, the products of reaction being essentially free from products of polymerization.

It is a still further object of the present in- 1 vention to provide a process wherein the low boiling isoparaflinic hydrocarbons may be ,combined with normally gaseous and normally liquid olefinic hydrocarbons to produce valuable motor fuel fractions having high anti-detonating characteristics.

It has now been discovered that the above and other objects can be realized by conducting the alkylation reaction in the presence of chlorosulphonic acid. 'It has been further discovered that excellent yields of alkymers boiling within the gasoline range and having the desired antidetonating characteristics may be produced by reacting the low boiling isoparafilnic hydrocare bons such as isobutane, isopentane and-isohexane, with normally gaseous olefinic hydrocarbons, or with normally liquid olefinic hydrocarbons having preferably not more than 12.carbon atoms per molecule, or with both types of olefins, in the presence of chlorosulphonic acid, said alkylation 'reaction being preferably realized at temperain the gasoline range, the resultant material being substantially free from products of polymerization. The invention further resides in realizing the above alkylation reaction at subatmospheric temperatures, the reaction being.

I conducted'in the liquid phase. a

The invention still further resides in conducting the above described alkylation reaction under conditions ,wherein the reacting products are maintained in a state of vigorous agitation. In order to minimize and even prevent the formation of polymerization products, the proportion of isoparamns should be constantly in excess of that theoretically necessary to combine with the olefins introduced into the reaction zone. For this purpose it has been found advantageous to first commingle the isoparafflns with the catalyst,

and then slowly and gradually introduce the olefins into the isoparaflin-catalyst mixture. presence of this excess of isoparamns and the gradual addition of the olefins prevents a local concentration of the olefins in the reaction mixture, such local high'concentration of olefins being undesirable because of the increased tendency The constant vigorous agitation of the mixture during the addition of the olefins likewise aids in preventing The In other words, both the agitation and the pres ence of isoparafiinic molecules in excess, and preferably a large excess of that theoretically necessary to combine with the olefins introduced, increasesthe chances of an immediate or substantially immediate, contact of the olefin with a reactive isoparaiiinic molecule. Simultaneously, and in accordance with the Law of mass action,

the relatively slow addition of the olefins de- I creases their concentration in the reaction zone,

thus also increasing the possibility of the alkylation reaction taking place in preference to polymerization.

The term isoparafiin when used herein, relates to the lower members of this series, and includes isobutane, isopentane and isohexane. The rates of reaction of these low molecular weight isoparafilns, maintaining other conditions equal, are not the same. Thus, it has been discovered that the rate of alkylation when isopentane is employed is considerably slower than that of isobutane, while isohexane is alkylated even at a slower rate than isopentane.

As previously brought out the term olefins relates to both the normally gaseous olefins, such as propylene, the butylenes and the pentenes, and the normally liquid'olefins'. In most instances, it is preferable although not essential, to employ olefinic fractions which do not have more than twelve carbon atoms per molecule.

It is further understood that the reference to isoparafiinic and olefinic hydrocarbons includes the use of these hydrocarbons individually, or in admixture with other hydrocarbons of the same class, or with other hydrocarbons.

The following example serves to show how the catalytic addition of olefinic hydrocarbons to isoparaflinic hydrocarbons may be effected in the presence of chlorosulphonic acid. It is to be understood, however, that the method of application of this new catalytic substance is not limited to the described mode of operation.

In this experimentthe isoparafilnic fraction employed comprised a relatively narrow cut obtained from the stabilization of natural gasoline.

An analysis of this fraction indicated that it con-- "79.3% by volume of isobutane, the residue being normal butane. It is obvious however, that the isoparaffinic fraction to be alkylated according to the present invention may consist of other isoparaffinic hydrocarbons. Thus, as stated, it is possible to alkylate isopentane or isoparafiinic fractions comprising a mixture containing isopentane or isobutane and other isoparaffins.

The specific olefin-containing fraction was derived from petroleum cracking operations and had substantially the following composition:

Y Percent by volume:

' Percent Ethylene 0.2 Ethane 1.5 Propylene 13.4 Propaine 28.3 Isobutylene 18.1 n-butylene 11.1 Isobutane 18.3 n-butane 9.1

In the particular experiment, the reaction was continued for about eight hours at a temperature of between -21? and -29 F., this low temperature being realized by keeping the reaction vessel in a bath containing kerosene and dry-ice. Since these low temperatures were sufequivalent to 128.1%

The procedure employed was as follows: 1750 grams of the'above described isobutane-contain- .ing traction was first commingled with about 1750 grams of chlorosulphonic acid, and approxi-. mately 3185 milliliters of the olefin-containing fraction was then gradually conveyed to the reaction zone, the rate of introduction being about 6.6 milliliters per minute. Since the analysis of this olefin-containing fraction showed that it contained about 42.6% of unsaturate's, the olefin introduction was at the rate oi! about 2.82 milliliters per minute. During the reaction period the mixture was maintaineddn a state of vigorous agitation'by a centrifugal type stirrer moving at the rate of 650 R. P. M. Approximately thirty minutes after all of the'olefinic stock had been added to the reaction chamber, agitation was discontinued and the reactor was maintained at a temperature of '--30 Elm several hours in order to allow phase separation to take place. The acid and hydrocarbon phases were then separately removed from the reactor, and the hydrocarbon phase analyzed to determine the quantity and character of the alkymers produced. I

It was thus found that 1575 grams or 2225 milliliters of stabilized alkymers had been produced, this being equivalent to a yield of 164.2%,

by volume based on the olefin employed. The stabilized alkymer fraction was completely saturated, thus indicating that substantially no polymerization products had been formed during the reaction. The gravity of this alkymer was 68.7 A. P. I. The knock-rating or this fraction, as determined by the A. S. T. M. method, was

88.0. ,The Engler distillation range of the product was as follows: Initial boiling point-115 F., overhead at 160 Ft, 50% overhead at 222 F., 90% overhead at 347 boiling point 418 F. This distillation resulted in a 98.0% recovery without any cracking.

Approximately 78% by volume of this alkymer distilled over at 325' F., the resulting distillate, by volume oi the olefins originally added into the reaction zone, having a knock-rating or 90.0 'and a gravity of 703 A. P. I. The Engler distillation curve of this distillate indicated that it was suitable as an aviation motor fuel. Thus, its initial boiling point was 126 n, 10% overhead at 176 rt, 50% overhead at 202 F., 90% at 256 F., with a maximum distillation temperature of 332 vI".,

29 F. temperature.

is within the scope or this temperatures as low aswhen the run was carried out at the --2l to Also the volume of the desirable products or reactionwere about 50% greater when the reaction was realized at --21 to -29 F. than when carried out at 0 F.

It is to be understood that there is no intention to be limited to the specific low temperatures disclosed hereinabove, the examples being merely indicative of the advantages obtained .by em- Thus, it

ploying sub-atmospheric temperatures.

invention to employ However, in order tomaintain the reaction in the liquid phase, the above the point of solidification of chlorosulphonic acid. Also, although the above described experiments were realized at atmospheric pressures, it is tobe understood that higher or lower pressuresmay be employed especially for the purpose of maintaining the reacting products in a, liquid state at the operating temperature.

The alkylation reaction in the presence of .chlorosulphonic acid and under the conditions described above, should be preferably realized in the absenceof any water in the reaction zone. For this purpose, the reacting hydrocarbons may preferably be dehydrated before their introduction into the sphere of reaction. This may be realized, for example, by conducting the isoparaffins and the I hydrating agents, such as a bed of NaCl, CaCla, NazCOs, or a similar material. Any other method or means of removing water which will F'., and maximum boiling range.

and 99.0% of the fraction was recovered as overhead.

As pointed out above, the-alkylation-oi isoparaifins with olefins in the presence of chlorosulphonic acid as a catalyst should preferably be realized at substantially low temperatures.

To show the advantage of operating at these low temperatures another run was conducted at a temperature of approximately 0 F, In this case, the reactionproduct comprised107% by volume oi th olefins employed, this reaction product containing 8% of products 0! polymerization. The knock-rating oi the product was 87.

A comparison of the above data with that given hereinabove in connection with therun conducted at lower temperatures, indicatesthe advantages oi operating at such lower tempera-- tures. Thus, whereas at least some polymerization occurred during the reaction at 0 IL, the

products of alkylation were completely saturated with olefins, addition or the relatively low molecular weight,

not alter the character of the reacting hydrocarbons can be'employed, and is deemed to be within the scope of the invention.

The above, disclosure is presented primarily in connect on with the alkylation oi isoparaflins emphasis being placed on the simple normally gaseous olefins to the specified isoparafllns. In addition, however, it has been observed that in reacting the described isopar'ailins with normally liquid olefinic hydrocarbons, the reaction product comprised a large proportion of saturated hydrocarbons or branched chain structure boiling substantially within the gasoline Such hydrocarbons evidently could be formed by an initial scission of at least one of the reacting original hydrocarbons into two or more hydrocarbons of lower molecular weight and the subsequent reaction oi these lower molecular weight hydrocarbons to produce branched chain paraillnic hydrocarbon molecules. Alternatively, the above product may be the result of a simple addition of the introduced olefinic molecule to an isoparaifinic molecule in .thereaction zone, followed by a scissionoi the resulting product. This be termed "cracking alkylati'on" in order to distinguish it from the straight or simple addition or an olefin to an isoparaiiin as already described hereinabove. Therefore, the "cracking alkyla- 'tion""reaction may bedescribed as including the molecules having molecular weights less than that which wouldrhc'obtained u the reaction were a of the simph addition type in which one introduced olefinic molecule reacted with one isoparamnic molecule to produce an isoparaflinic alkymer having a molecular weight equal to the sum or the molecular weights or the reacting olefin and isoparamn Therefore, the invention also includes the re F., and even lower.-

temperature should be olefins through or over de-.

type of alkylation might action between fisopara flins and certain of the olefins, in. the presence of chlorosulphonic acid as a catalyst andunder optimum temperature and pressure conditions, to" produce simple alkylation of the isoparaflins by the olefins added, and the cracking alkylation in which, as stated, alkymers are produced which have a lower molecular'weight than would be obtained by a simple addition of an olefin to an isoparaflin. Primarily, this cracking alkylation occurs when the isoparaiiins of the class described are caused to react, in the presence of chlorosulphonic acid, and at the described low temperatures, with the normally liquid olefinic hydrocarbons. The higher molecular weight olefins, and particularly those above dodecenes, however, appear to be unsuitable to react with isoparafiins.

The .chlorosulphonic acid used therein as the alkylating catalyst is an acid having the general formula SO2OHC1. Its molecular .weight is 116.531. It is a substantially colorless,.fuming liquid having a rather piquant odor. The melting point of this acid is approximately -80 C. while its boiling point is variously given as being between about 145- and 158 C. This acid may be prepared, for example, by the direct addition of hydrogen chloride to sulphur trioxide. However,

there are other methods for preparing this acid catalyst. 'For other characteristics of chlorosulphonic acid, as well as for the various methods of its manufacture, reference is made to such authorities as J. W. Mellors treatise entitled A Comprehensive Treatise on Inorganic and Theoretical Chemistry," 1930, vol. X, pages 686-687.

The term gasoline boiling range, as employed herein, refers to the average boiling range of fuels used in ordinary automobile engines. vGenerally speaking, such a gasoline has an initial boiling point of about 100 F., and a maximum or end point of around 425 F. The term atmospheric pressure refers to pressures in the neighborhood of that exerted by acolumn of mercury 760 mm. in height, while "atmospheric temperature""relates to temperatures in the neighborhood of 70 F. to 80 F.

In carrying out the invention, the apparatus -used, as well as the conditions of operation chosen, will be. varied to suit the individual case. The foregoing specification is to be considered e as merely descriptive of the process and catalyst,

and is not to be considered as imposing any undue limitations upon its generally broad scope as covered by the appended claims.

I claim: I v

1. A process for the production of branched chain hydrocarbons boiling within the gasoline chain paraflinic hydrocarbons, which comprises commingling isoparaflinic. hydrocarbons having less than seven carbon atoms per molecule with a catalyst comprising chlorosulphonic acidbetween' the temperatures of 0 F. and F., introducing normally gaseous olefins into said'acidisoparafiin mixture, and withdrawing alkylated branched chain hydrocarbons-from the reaction zone, said last mentioned hydrocarbons being liquid under normal conditions of pressure and temperature. 7

3. In a process according to claim2 wherein the acid-isoparafiin mixture is maintained in a state of agitation, and wherein the olefins are introduced gradually into said violently agitated mixture.

4. A process of forming alkylated branched chain hydrocarbons having high ant -detonating characteristics, and suitable as motor fuel,

which comprises reacting isoparaflinic hydrocarbons having less than seven carbon atoms permolecule with normally liquid olefins having less than thirteen carbon atoms'per molecule, in the presence of a catalyst containing chlorosulphonic acid.

5. In a process according to claim 4 wherein the reaction is realized at sub-atmospheric temperatures- 6. A process of forming alkylated branched chain hydrocarbons boiling substantially within the gasoline range, having high anti-detonating characteristics, and substantially free from polymers boiling within said range, which comprises commingling isoparafiinic hydrocarbons having less than seven carbon atoms per molecule with a (atalyst comprising chlorosulphonic acid,. maintaining said mixture in a state of agitation and at sub-atmospheric temperatures, and introduc 'ing into said isoparaflin catalyst mixture nor mally' liquid olefinie hydrocarbons below about dodecenes, thereby causing a reaction between said olefins and isoparaflins to branched chain saturated hydrocarbons.

boiling point range and having high anti-detonat- I ing characteristics, which comprises reacting isoparafiins having less than seven carbon atoms per molecule with normally gaseous olefins in the presence .of chlorosulphonic acid between the j temperatures of 0 F. and the solidification temperature of chlorosulphonic acid.

2. A process for the production of branched .7. In a process according to claim 6 wherein the reaction is realized at temperatures between about 0 F. and the solidification temperature of chlorosulphonic acid.

8. A process offorming alkylated branched chain hydrocarbons boiling substantially within the gasoline range, having high anti-detonating characteristics and substantially free from polymers within said range which comprises-commingl'ing iso-butane with chlo'rosulphonic acid,

produce said introducing into said isobutanechain alkylated hydro-