US2514866A - Catalytic conversion of hydrocarbons - Google Patents

Description

1 5 R. s HOVEY 2,514,

CATALYTIC CONVERSION OF mmnocmons Filed Aug. 27, 1945 PARAFF IN OR CYCLOPARAFFIN CONTACT WITH- CATALYST CONSISTING OF MAJOR PROPORTION OF 'HF AND MINOR PROPORTION OF TiF4 UNDER CONDITIONS EFFECTINQ RECONSTRUCTION OR ISOMERlZATION INVENTOR. R.S. HOVEY ATTORNEYS Patented July 11, 1950 CATALYTIC CONVERSION OF HYDROCAIBONS Bo 8. Howey, Barflenme, 0th., to r l i illipaletnlemnflompanmaeotporaflonot Dehware h memmzamesaamanam scam (creel-m) This invention relates to the conversion of hydrocarbons and especially of open-chain parafflns and cyclo More particularly it relates to the conversion of normal 04 and higher to branched-chainCr and higher paraflins and to the conversion of methyl cyclopentane to cyclohexane. Where normal 04 and higher are employed as the starting material, the principal or sole reaction may be simple isomerization to the corresponding isoparailin'or reactions may take place whereby the normal paraflin feed is converted to isoparamns or lower and higher molecular weight in addition to the corresponding iso For example. normal pentane may be converted to a mixture of iso including substantial or large proportions of isobutane and branchedchain hexane: in addition to isopentane. likewise normal'hexane may be converted to isobutane and isopentane in addition to branchedchain hexanes usually including diisopropyl and methylpentanes. This type of coliversion is termed reconstruction, disproportiona tion or "Isoversion. More the present invention relates to the conversion of hydrocarbons in the presence of a catalyst of a major proportion of substantially anhydrous hydrogen fluoride and a minor proportion of titanium tetrafluoride. V

The conversion of straight-chain or normal to the more valuable branched-chain paraflinsinthepresenceoiacati -lyticbodyis' a well-known reaction One catalyst for these reactions known in the art is anhydrous aluminum chloride. By employing this catalyst per se in contact with a hydrocarbon material such as gas oil in a still operated at 400 F. and above, the hydrocarbon is cracked to produce gasoline boiling-range hydrocarbons of branched-chain 4 character. By employing anhydrous aluminum isomeric are obtained from charge stocks such as normal butane, pentane and the like. e splitting reactions whereby products of diiferent molecular weight from that of the charge are produced may be reduced by conducflngthereactioninthe presence of a catalystmodiflersuch as hydrogen and/or naphthenic hydrocarbons.

It is also well-known that certain cycloparafflns aremore valuable than other cycloparaiiins. For example, cyclohexane has much greater value than methyl cyclopentane, large quantities of which are available from natural gas and gasoline. Accordingly, a simple and economical proces for the less valuable cycloparaillns to the more valuable cycloparaflins is of great significance.

The object of the present invention is provide an improved process for the conyerslon of hydrocarbons. Another object is to provide an improved proces for the isomerization ornormalcrorhigherparaiiinstothemore valuable branched-chain paraflins;

Another object is to provide an improved processforthen ofcsorhigher parto form mixtures of branched-chain parafllns having four and more carbon atoms per molecule. Anotlmr object is to provide a process for the conversion of straight-chain relatively low octane number to the more valuable to l Another oblost is to eiiect the conversion or normal hexane to neohexane and diisopropyl in a simple and feasible manner. Another object is to provide an improved process for isomerizing cy especially those having five and six carbon atoms in the ring. Another object is to provhie an improved process of isomerizing methyl cyclopentaue to cyclohexane. Another object is to provide a new catalyst which is especlally adapted to the foregoing reactions but which may be used in other reactions ifor which it is suitable. Another object is to provide a novel and highly advantageous method of preparing the new catalyst. Another object is to provide a novel method of incorporating the new catalyst into a hydrocarbon participating in the conversion. Many other objects will more fully appear.

The accompanying drawing which is self-explanatory portrays diagrammatically theiiydrocarbon conversion process of the present invention n its more specific aspect wherein the catalyst comprises essentially a major proportion of *hydrofluoric acid and a minor proportion of titanium tetrafiuoride.

In accordance with the present invention a saturated hydrocarbon selected from the group consisting of paraflins and cycloparafiins, especially an isomerizable parafiln or cycloparaflin hydrocarbon having at least four and usually at The process of the present invention is applica i ble to eiTect the isomerization or reconstruction of C4 and heavier paraflins or the isomerization of a cyclopara'fiin having 5 or 6 carbon atoms in the ring. The isomerization of paraffins is usually conducted in such manner that a normal paraifin is converted to a corresponding branched-chain paraflln, although since isomerization is an equilibrium reaction it may be applied to efiect the reverse reaction, namely, conversion of a branched-chain paraflin to the corresponding straight-chain form in the exceptional situation where such a conversion is desired. Likewise, while the process of this. invention is usually employed to convert a less valuable alkyl cyclopentane to a more valuable cyclohexane derivative, particularly methyl cyclopentane to cyclohexane, it may be employed to effect the reverse reaction.

I have discovered a new catalyst comprising essentially a major proportion of anhydrous hydrofluoric acid and a minor proportion of titanium tetrafluoride which is effective in the conversion of straight-chain hydrocarbons to the more valuablebranched-chain hydrocarbons and in the isomerization of cycloparaflins, as for example, the isomerization of methyl cyclopentane to cyclohexane. The proportion of titanium tetrafluoride contained in the catalyst may range from about one up to twenty weight per cent of the hydrogen fluoride and titanium tetrafluoride, or higher, if desired, although usually it will not be desirable to use more than will go into solution in the acid phase under reaction conditions, although solutions may be used, if desired, that contain TiF4 in'vexcess of that held in solution.

The following example will facilitate a more complete understanding of my invention. This example is not, however, to be interpreted to place any limitation on this invention.

Example To a 1.6 liter monel bomb was charged 30 g. of

TiFl, 520 g. of anhydrous hydrogen fluoride, and 520 cc. (approximately 343 g.) of normal hexane, this volume being measured at room temperature. The bomb was shaken for one hour at a temperature of 209 F. The content of the bomb was then removed and the hydrocarbon phase recovered 4 and freed of catalyst. An analysis of the hydrocarbon product yielded the following results:

Component Weight per cent Propane 0.8 Isobutane 9.9 Normal butane 0.7 Isopentane 9.7 Normal pentane 0.6 Neohexane 11.1 Diisopropyl 29 3 2- and 3-methylpentane Normal hexane 20.6 Heavier 17.3

For comparison, the following experiment was carried out:

To a 2880 cc. stainless steel bomb a charge of 995 cc. of normal hexane and 1000 cc. of anhydrous hydrofluoric acid were added. The bomb was agitated for three hours at 291 F. The recovered hydrocarbon consisted of 83.5 weight per cent normal hexane and 16.5 weight per cent of isomeric hexanes.

A comparison of the hydrocarbon product of these two experiments shows the effective promoting action of the titanium tetrafluoride and the superior catalytic properties of this new cata lyst.

Other paraflins, including butane, pentane, heptane, and heavier as well as hexane may be isomerized with this catalyst.

In addition to the isomerization of the parafiin hydrocarbons, this new catalyst is effective in accomplishing the isomerization of naphthenic hydrocarbons. Illustrative of this type of isomerization is the conversion of methyl cyclopentane to cyclohexane;

In carrying out conversions with this catalyst, the preferred conditions of reactions are: contact time, five minutes to three hours; temperature, 70 to 450 F.; pressure, sufiicient to maintain substantially liquid phase; and the catalyst-tohydrocarbon ratio between 4:1 and 1:4, on a volume basis.

In the event that the production of the compounds of higher and lower molecular weight than the charge stock is not desired, the production of these compounds may be inhibited by conducting the reaction in the presence of hydrogen in the proportion of one to twenty atmospheres partial pressure when measured at room temperature, the exact amount depending upon the paraflln treated. Naphthenic hydrocarbons, fOr example, methyrcyclopentane and cyclohexane, or aromatic hydrocarbons in the proportion of one to twenty-five weight per cent of the charge, may also be used to inhibit the splitting reactions when conversion of parafiins is practiced.

Numerous types of apparatus are suitable for carrying out hydrocarbon conversion on commercial scale using this catalyst and are known to those skilled in the art. Mechanically-agitated or jet-agitated contactors may be used, or the hydrocarbon may be dispersed and allowed to rise through a body of the catalyst. Intimate contacting of the catalyst and hydrocarbon is desirable.

Continuous operation may be practiced in the followin manner: The hydrocarbon to be processed is charged to a contactor containing the catalyst. Here 'the catalyst and hydrocarbon are mixed. and an emulsion of catalyst and hydroa liquid, in the desired amount into the catalyst recycle stream or into the hydrocarbon feed stream, in which TiCli is soluble. The Tick reacts when in contact with HF, which is in liquid phase, to form Tim, which goes into solution in the HF as rapidly as it is formed. An alternative method of addition involves placing the previously manufac ured titanium tetrafluoride in a closed vessel and passing the catalyst recycle stream through this vessel to saturate the stream with TiF4. I

It may also be desired to add water in proportions ranging irom a trace (0.01) up to about 0.1 weight per cent in the charge to the reactor we in order to reduce sludge formation.

The conditions best suited to carrying out reactions with this catalyst vary with the particular hydrocarbon or,mixture orhydrocarbons to be processed, but these conditions may readily be determined bytrial.

In use the catalyst gradually loses activity. Such spent or partially spent catalyst may be regenerated in any desired manner, as for example, by distilling oi! HF and other products and recovering TiF4 from the residue by extraction, sublimation or the like.

I claim:

1. A process for the conversion of a saturated hydrocarbon selected from the group consisting' of isomerizable and cycloparafflns having at least 5 carbon atoms in the ring which comprises passing a hydrocarbon from said group substantially free of 'unsaturates into contact with a liquid catalyst comprising essentially a major. proportion of hydrogen fluoride and a minor proportion of titanium tetrafluoride dissolved therein and in which the titanium tetrafluoride is in an amount within the range of from 1 to per cent by weight of said catalyst under reaction conditions so as to eiiect substantial reconstruction of said hydrocarbon.

' 2. The process of claim 1 wherein sludge for-' mation during the reaction is reduced by having water present in proportions ranging from 0.01 to 0.1 weight per cent of the hydrocarbon charge.

3. A process for isomerizing methyl cyclopentane to cyclohexane which comprises-contacting said methyl cyclopentane substantially free of unsaturates with a catalyst consisting of a major proportion of hydrogen fluoride and a minor proportion of titanium tetrafluoride dissolved therein, said titanium tetrafluoride being present in an amount within the range of from 1 to 20 per cent by weight of said catalyst, under conditions such that isomerization of said methyl cyclopentane to cyclohexane is the principal reaction.

4. A process for the conversion of a saturated hydrocarbon selected from the group consisting of isomerizable paraflins and cycloparaflins which 6 of titanium tetrafluoride based on the weight of said catalyst, the volume ratio of said catalyst to said hydrocarbon being within the range of from 4:1 to 1:4, under pressure suflicient tomaintain liquid phase and at a temperature of from 70 to 450 F. for a time of from 5 minutes to three hours so as to eilect conversion of said hydrocarbon to other saturated hydrocarbon.

' 5. A process for the isomerization of a saturated hydrocarbon selected from the group consisting oi-isomerizable paraflins and cycloparaffins which comprises contacting said saturated hydrocarbon in substantial absence of olefins with a catalyst consistingof hydrogen fluoride having dissolved therein from 1 to 20 per cent by weight of titanium tetrafluoride based on the weight of said catalyst, the ratio of said catalyst to said hydrocarbon being within the range of from 4:1 to1:4 by volume, under pressure suflicient to maintain liquid phase and at a temperature of from 70 to 450 F. for a time of from 5 minutes to three hours so as to effect isomerlzation of said saturated hydrocarbon to an isomer as a principal reaction of the process.

6. A process for the reconstruction of a paraflln hydrocarbon having at least four carbon atoms per molecule which comprises contacting said paraiiin hydrocarbon insubstantial absence of oleflnswith a catalyst comprising essentially hydro'gen fluoride having dissolved therein from 1 to 20 per cent by weight of titanium tetrafluoride based on the weight of said catalyst, theratio of said catalyst to said hydrocarbon being within the range or from 4:1 to 1:4 by volume under pressure suflicient to maintain liquid phase and at a temperature of from 70 to 450 F. for a time of from 5 minutes to three hours and thereby eiiecting reconstructionof said paramn hydrocarbon as a principal reaction of the process.

7. A process for the reconstruction of normal hexane which comprises subjecting a reaction mixture consisting of approximately 343 parts by weight of normal hexane, approximately 520 parts by weight of anhydrous hydrogen fluoride and approximately 30 parts by weight of titanium tetrafluoride dissolved therein in a closed vessel in the substantial absence of olefins to a temperature of approximately 209 F. for approximately one hour and thereby effecting reconstruction of said normal hexane to. branched chain hexanes including substantial proportions of each of neohexane and diisopropyl, to isobutane in substantial proportion, to isopentane in substantial proportion and to hydrocarbon heavier than hexane in substantial proportion.

8. A process for the isomerization of an isomerizable paraffin hydrocarbon having at least 4 carbon atoms per molecule which comprises passcomprises contacting said saturated hydrocarbon ing said paraflin hydrocarbon substantially free of oleflns into contact with a liquid catalyst comprising essentially a major proportion of hydrogen fluoride and a minor proportion of titanium tetrafluoride dissolved therein and in which the latter is present in an amount within the range of from 1 to 20 per cent by weight of said catalyst under reaction conditions which efiect substantial isomerlzation of said parafiin hydrocarbon.

9. A process for the isomerization of normal hexane which comprises contacting normal hexane in the substantial absence of oleflns with a liquid catalyst comprising essentially a major proportion of hydrogen fluoride and a minor proportion of titanium tetrafluoride dissolved therein and in which the latter amounts to from 1 to 20 per cent of the catalyst mixture under reaction conditions of time, temperature, and Number pressure regulated so as to effect substantial 2,356,487 isomerization of normal hexane as the principal 2,379,749 reaction of the process. 2,383,627

ROGER S. HOVEY. 5 2,396,331

2,399,765 REFERENCES CITED 2,403,649 The following references are of record in the 2,406,954 file of this patent: 2,421,950 UNITED STATES PATENTS Number Name Date 2,126,284 Rose Aug. 9, 1938 2,257,896 Yarnall Oct. 7, 1941 2,330,079 Owen Sept. 21, 1943 15 Longmans.

Name Date Upham Aug. 22, 1944 Ross et a1. .1 July 3, 1945 Thomas et a1. Aug. 28, 1945 Marschner Mar. 12, 1946 Shoemaker et a1. May 7, 1946 Frey July 9, 1946 Linn Sept. 3, 1946 Linn June 10, 1947 Wachter Dec. 2, 1947 OTHER REFERENCES Melior, Comprehensive Treatise on Inorganic & Theoretical Chemistry, vol. 7, page 67, pub. by

Claims (1)

1. A PROCESS FOR THE CONVERSION OF A SATURATED HYDROCARBON SELECTED FROM THE GROUP CONSISTING OF ISOMERIZABLE PARAFFINS AND CYCLOPARAFFINS HAVING AT LEAST 5 CARBON ATOMS IN THE RING WHICH COMPRISES PASSING A HYDROCARBON FROM SAID GROUP SUBSTANTIALLY FREE OF UNSATURATES INTO CONTACT WITH A LIQUID CATALYST COMPRISING ESSENTIALLY A MAJOR PROPORTION OF HYDROGEN FLUORIDE AND A MINOR PROPORTION OF TITANIUM TETRAFLUORIDE DISSOLVED THEREIN AND IN WHICH THE TITANIUM TETRAFLUORIDE IS IN AN AMOUNT WITHIN THE RANGE OF FROM 1 TO 20 PER CENT BY WEIGHT OF SAID CATALYST UNDER REACTION CONDITIONS SO AS TO EFFECT SUBSTANTIAL RECONSTRUCTION OF SAID HYDROCARBON.

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