US2422675A - Selective demethylation of saturated hydrocarbons - Google Patents

Description

Patented June 24, 1947 SELECTIVE DEMETHYLATION F SATURATED HYDROCARBONS Vladimir Haensel, Clarendon Hills, and Vladimir N. Ipatieii, Chicago, Ill., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware No Drawing. 'Application'Dec'ember 29, 1945, Serial No. 638,482

Claims.

This invention relates to the treatment with hydrogen in the presence of a hydrogenating catalyst of a saturated hydrocarbon to produce therefrom another saturated hydrocarbon containing at least 1 carbon atom less than those present in the hydro-carbon charged to the process. More specifically, our invention is concerned with a catalytic process fortreating with hydrogen a saturated hydrocarbon containing more than four carbon atoms including an alkyl group of at least 2 carbon atoms, said process being carried out at closely correlated conditions of temperature, hydrogen partial pressure and charging rate so that the principal reaction of the process is the replacement with hydrogen and the scission of methyl groups, in the form of methane, to the exclusion of alkyl groups of more than 1 carbon atom, to decrease the number of carbon atoms of said hydrocarbon by at least 1 carbon atom.

An object of this invention is the demethylation of a saturated hydrocarbon having at least 5 carbon atoms per molecule to produce therefrom a hydrocarbon of lower molecular weight.

Another object of this invention is the demethylation of a paraffinic hydrocarbon containing at least 5 carbon atoms per molecule to produce therefrom a paraflinic hydrocarbon of lower molecular weight.

A further object of this invention is the demethylation of a saturated hydrocarbon havlllg at least 8 carbon atoms per molecule to produce therefrom a hydrocarbon of lower molecular weight.

treatment of a cycloparafiinic hydrocarbon having at least 8 carbon atoms per molecule comprising a ring of 6 carbon atoms and an alkyl side chain of at least 2 carbon atoms to decrease the number of carbon atoms in said alkyl side chain of said hydrocarbon by at least 1 carbon atom by removing only one methyl group from said alkyl side chain, While retaining a portion of said side chain in chemical combination with said ring.

One specific embodiment of the present invention comprises a process for reacting hydrogen with a saturated hydrocarbon containing more than 4 carbon atoms per molecule in the presence of a hydrogenation catalyst comprisinga metal selected from the group consisting of nickel and cobalt to form a hydrocarbon of lower molecular weight.

A further embodiment of the present invention comprises a process for reacting hydrogen with a parafiinic hydrocarbon containin more than 4 carbon atoms per molecule in the presence of a catalyst comprising a 'metal selected from the group consisting ofnickel and cobalt to form a hydrocarbon of lower molecular weight.

Another embodiment of the present invention comprises a process for reacting hydrogen with a saturated hydrocarbon containing more than 4 carbon atoms per molecule including an alkyl group of at least 2 carbon atoms in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt previously reduced at a'temperature of from about 425 to about 650 C.

I-Ieretofore destructive hydrogenation methods have been utilized to produce gasoline from higher boiling oils in the presence of various hydrogenating catalysts. Such methods may be regarded as involving essentially the cracking of the higher boiling oils accompanied by hydrogenation of the products of lower molecular weight to form substantially saturated hydrocarbons boiling within the range of gasoline. The present process differs from the destructive hydrogenation treatments of the prior art, particularly in that it specifically involves the demethylation of a hydrocarbon charging stock under definite and specific conditions of operation necessary to efiect a, high degree of selective demethylation with substantially no accompanying undesired cracking reactions. The present process is a method for converting a saturated hydrocarbon into saturated hydrocarbons of lower molecular weights and desired structures.

By the term selective demethylation we mean the herein-described reaction of a saturated hydrocarbon with hydrogen in the presence of a particular catalyst whereby certain methyl groups are removed in preference to other groups from a hydrocarbon being subjected to said treatment. For example, the parafiinic hydrocarbon, 2,2,3- trimethylpentane, which has the formula:

has 5 methyl groups, 3 of which groups are combined with the quaternary carbon atom, 1 is bound to the tertiary carbon atom, this tertiary atom being adjacent to the quaternary carbon atom, and the fifth methyl group is the terminal portion of the ethyl group'of the 2,2,3-trimethylpentane molecule. The terminal methyl group is combined with the secondary carbon atom of the 2,2,3-trimethylpentane molecule. Accordingly, if any one of the methyl groups attached to the quaternary carbon atom would be removed therefrom by reaction with hydrogen, the products 2,3-dimethylpentane and methane would be formed; whereas the similar splitting of the methyl group from the tertiary carbon atom would result in the formation of 2,2-dimethylpentane and methane. If the fifth methyl group, namely, that which is a part of the ethyl group of the molecule, is removed therefrom, the resultant reaction mixture would contain triptane and methane. Accordingly, if all of the bonds between the different carbon atoms of 2,2,3-trimethylpentane are of equal strength, the probability of forming a dimethylpentane is 4 times that of forming triptane. However, we have found by experimental evidence that the bond between the quaternary and the tertiary carbon atoms is stronger than is the bond between the triptyl group and the terminal methyl group of 2,2,3-trimethylpentane. The experiments gave relatively high yields of triptane but a relatively small yield of dimethylpentanes.

We have found that different hydrocarbons which do not contain quaternary carbon atoms may also be demethylated selectively. Thus isopcntane was demethylatedto relatively high yields of isobutane with relatively low formation of normal pentane. The demethylation of nhexadecane (also known as cetane) which contains only primary and secondary carbon atoms gave a reaction product containing substantial amounts of pentadecane, tetradecane, tridecane, dodecane, etc. We observed that a methyl group that is bouned to a secondary carbon atom of a paraffinic hydrocarbon is the easiest to remove by dem'ethylation, that a methyl group bound to a tertiary carbon atom is less easy to remove, and that a methyl group combined chemically with a quaternary carbon atom is the most diflicult type of methyl group to split off in the form of methane. By way of explanation, a secondary carbon atom is a carbon atom that is combined with 2 other carbon atoms, a tertiary carbon atom is combined with 3 carbon atoms, and a quaternary carbon atom is combined with 4 carbon atoms.

Saturated hydrocarbons which are demethylated by the process of this invention have more than 4 carbon atoms per molecule including an alkyl group containing at least 2 carbon atoms and comprise parafiinic hydrocarbons and cycloparafiinic hydrocarbons, the latter having alkyl groups containing at least 2 carbon atoms. The parafiinic hydrocarbons include both normal and branched chain paraiiins, while the cycloparaf finic or naphthenic hydrocarbons include par ticularly ethyl cyclohex-ane and other alkyl cy clohexanes of higher molecular weight containing at least one alkyl group of 2 or more carbon atoms. I

The paraffinic hydrocarbons treated by the process of this invention comprise the normally liquid paraffins and particularly those containing at least 6 carbon atoms per molecule. The process is applicable to both normal and branched chain parafonic hydrocarbons, When producing triptane, the octane, 2,2,3-trimethylpentane, mentioned above, is a preferred charging stock but this octane is not the only aliphatic hydrocarbon convertible into triptane by our process. Similarly, 2,3,3-trimethylpentane may also be demethylated into triptane, as is also true with certain highly branched nonanes, decanes, and other hydrocarbons containing a triptyl group. By a triptyl group we mean an alkyl group containing a quaternary carbon atom adjacent to a tertiary carbon atom. Thus, a triptyl group contains vicinal tertiary and quaternary carbon atoms. I

The chain structures of parafiinic hydrocarbons containing a triptyl group and convertible into triptaneby demethylation may be indicated by the following formula in which R to R represent alkyl groups or hydrogen atoms, but with at least one of the R to R groups being an alkyl group.

structural formula contains a total of n carbon atoms in the groups R to R inclusive, the demethylation to triptane may be represented by the equation:

Also, demethylation of a cycloparaffinic hydrocarbon having an alkyl group of at least 2 carbon atoms per molecule is illustrated by the following equations showing the demethylation of tertiary butyl-, propyl-, and ethyl-cyclohexanes.

CsH11C(CI-l3)3+H2 CtI-I11CH(CE) 2+CH4 CsHnCI-IzCHa-CHs+H2 CsH11CI-I2-CH3 +CH4 CGH11CH2CH3+I-I2 CsH11CH3+CH4 Catalysts which we prefer for our demethylation process contain at least one of the metals selected from the group consisting of nickel and cobalt. These metals have atomic weights of from about 53 to about 60 and are also active hydrogenating catalysts. Different hydrogenation catalysts comprising these metals or their oxides are utilizable in our process, but they are preferably supported by carriers such as alumina, silica, diatomaceous earth, crushed porcelain, or some other refractory material which has substantially no adverse influence upon the demethylation reaction. 7

A highly active nickel catalyst which we have used in carrying out our process contained ap proximately 66% by weight of total nickel, of diatomaceous earth, and 4% of oxygen, the latter present in nickel oxide. This catalyst was made by-the general steps of suspending diatomaceous earth, also known as kieselguhr, in a dilute aqueous solution of nickel sulfate and then gradually adding thereto an excess of a hot saturated solution of sodium carbonate in water. The mixture of nickel sulfate solution and diatomaceous earth was agitated vigorously while the sodium carbonate solution was introduced thereto to form precipitate which was removed by filtration, and was then washed with water, dried, heated, and reduced with hydrogen.

The resultant nickel-diatomaceous earth catalyst is employed in powdered form when demeth- 6O ylation is effected in batch type treatment or in the fluidized or fluidized fixed bed type of operation. When pelleted or formed catalyst particles are desired, the powdered mixture, preferably before being subjected to reduction with hydrogen or a reducing gas mixture, is mixed with graphite or some other lubricant and formed into pellets by a pilling machine. Other nickel-containing catalysts which may be employed similarly may be prepared to contain proportions of nickel different from those aforementioned.

Cobalt catalysts have also been prepared by essentially the same series of steps as were used in producing nickel-diatomaceous earth catalyst composites. Diatomaceous earth and cobalt nitrate so proportioned as to give essentially the same ratio of cobalt to silica as of nickel to silica in the above-described catalyst, were mixed with water and then treated with an excess of a hot saturated solution of sodium carbonate in water. The mixture of cobalt nitrate solution and diatomaceous earth suspended therein was agitated vigorously while the sodium carbonate solution was added thereto to form a precipitate which was removed by filtration and was then washed with water, dried, and reduced to give an active cobalt-diatomaceous earth catalyst, utilizable in the form of .powder orpellets in essentially the same manner as the nickel-diatomaceous earth catalyst.

Accurate control of the demethylation temperature is sometimes difiicult because of the exothermic nature of the reaction. Calculations show that when one methyl group is removed as methane from one gram mole of hydrocarbon, approximately 12,500 calories of heat are evolved. Since in the hydrogenation of an olefin, the evolution of about 16,900 calories accompanies the hydrogenation of one double bond per mole of hydrocarbon, it is evident that the removal of one methyl group per mole causes the evolution of approximately 75% as much heat of reaction as does the hydrogenation of a mono-olefin. However, if the demethylation reaction is permitted to proceed further until methane is the only product, the heat of reaction becomes l2,500(n1) calories, where n is the number of carbon atoms in each molecule of the original hydrocarbon charged. Thus if an octane is demethylated completely to methane, the heat of reaction is approximately 8'7,500 calories'per mole. This heat of reaction is approximately 5.2 times the heat evolved upon hydrogenation of octene to octane. Therefore, it is apparent that if the catalyst used in demethylation, for example, of octane, is of such an active nature that excessive conversion or complete conversion to methane takes place readily, the catalyst will undergo a very rapid and excessive rise in temperature. As a result of such a high temperature, the catalyst will undergo a loss in demethylating activity. However, if the catalyst is of a less active nature, the demethylation reaction can be controlled and substantially stopped after only one or two methyl groups have been removed from the hydrocarbon charged to the process. In this case the heat of reduction is sufliciently low that it can be dissipated from the reaction zone fast enough so as tomaintain a desired catalyst temperature, and so that relatively high conversions to lower molecular weight hydrocarbons can be attained.

We found that it was preferable to reduce nickel and cobalt catalysts at a temperature of from about 425 to about 650 C. rather than at a lower temperature in order to obtain a demethylation catalyst of such activity that the demethylation reaction could be controlled readily to produce demethylated hydrocarbons containing at least 4 carbon atoms per molecule. After reduction of the catalyst mixture with hydrogen at a temperature of from about 425 to about 650 0., the catalyst was of such activity that the demethylation reaction carried out in its presence could be controlled readily at relatively high conversions per pass, although we prefer to operate at such conditions as to obtain from. about 20 to'about 50% conversion per pass. If the catalyst was reduced only at a temperature below about 425 C., its initial activity was often so high that the exothermic heat arising from demethylation caused an excessive temperature which not only-had a'tende'ncy to spoil the activity of the catalystbut to cause momentary, excessive conversionof the charged hydrocarbon into methane and to generate a high exothermic heat of reaction; that is, to cause the so-called burning of the catalyst. However, when the activity'of the catalyst was modified by the reduction ata temperature of from about 425 to about 650 C., the demethylation reaction could be controlled and could be substantially stopped after only one-or two methyl groups had been removed fromthe hydrocarbon charged to the process. Under these circumstances the heat of reaction was sufiiciently low that it could be dissipated from the reaction zone rapidly enough to maintain a desired catalyst temperature so that relatively high conversions to lower molecular weight hydrocarbons could be attained and so that these conversions could be maintained for relatively long periods of time.

This demethylation process may be carried out using either batch or continuous types of operation. In batch operation, the charged hydrocarbon, hydrogen-containing gas, and catalyst are heated together in an autoclave for a time sufficient to effect demethylation. In the continuous type of treatment, which we prefer, a hydrocarbon and a hydrogen-containing gas are passed through a reactor containing a nickel, cobalt, or nickel and cobalt catalyst and the reaction products are discharged continuously from the reactor at substantially the same rate as that at which the reactants are charged thereto. The products of the demethylation treatment are fractionated by suitable means to separate the desired lower boiling hydrocarbons from the unconverted portion of the hydrocarbon material charged to the process, and said unconverted material is recycled to commingle with the hydrocarbon material charged.

The partial pressure of hydrogen in the re action zone is an important controlling factor in the 'demethylation of a saturated hydrocarbon. Experimental results show that a lowering of the hydrogen partial pressure generally necessitates a lowering in the catalyst temperature in order tdobtaina particular once-through yield of. a desired reaction product such as triptane. However, as the demethylation reaction proceeds in the reaction zone, the partial pressure of hydrogen decreases whereas the partial pressure of methane increasesp If the temperature of the catalyst layer or bed is kept constant throughout, the rate of demethylation increases as the reactants proceed through the catalyst because of the fact that the partial pressure of hydrogen is decreasing continuously and the temperature range required for high conversion is accordingly shifted toward lower temperatures. In order to have better control over the demethylation reaction, it is sometimes advantageous to charge with ,thesaturated hydrocarbon a mixture of hydrogen and methane rather than substantially pure hydrogen. When operating in this manner, a portion of the effluent hydrogen-methane mixture is recycled to the process and commingled with the saturated hydrocarbon fraction and hydrogen-containing gas charged thereto. Since methane is more soluble in the liquid hydrocarbon product thanis hydrogen, the liquid product can be subjected to a depressuring operation in a number of stages and methane is recovered from the last stage or stages. Hydrogen mixed with small amounts of methane is recovered from the first depressuring stage or stages and is suitable 7 for recycling to the process. The removal of some of the methane by such a method prevents an excessive accumulation of methane in the recycle gas. Proper control of the demethylation reaction temperature, that is, of the catalyst temperature, is necessary since otherwise the desired products undergo further demethylation to produce saturated hydrocarbons of still lower molecular weights, the ultimate product being methane.

It is apparent from this discussion that successful demethylation requires a careful correlation of operating conditions including temperature, and hydrogen partial pressure in order to efifect the selective removal of at least one methyl group as the principal reaction of the process. Accordingly, selective demethylation is in contrast with the uncontrolled destructive action whereby the hydrocarbons undergoing reaction are converted almost entirely into methane or, on the other hand, with conventional destructive hydrogenation processes wherein heavy hydrocarbons are split into lower boiling fragments which hydrogenate to form two or more molecules of liquid hydrocarbons.

The process of our invention is carried out by contacting hydrogen or a gas containing a major proportion of hydrogen and a saturated hydrocarbon having more than 4 carbon atoms per molecule with a nickel and/r cobalt catalyst at carefully correlated conditions of temperature and pressure. The catalyst temperatures utilizable in the process are from about 150 to about 385 C. Although the hydrogen partial pressure is preferably above about 3.45 atmospheres absolute, lower pressures may also be employed. Total pressures used in our process are generally not higher than about 200' atmospheres. In the presence of a catalyst containing nickel and/or cobalt, our demethylation process is carried out preferably at a catalyst temperature of from about 230 to about 350 C. a

We have found that the catalyst temperature needed to obtain conversions of up to about 70% by weight of the charged saturated hydrocarbon per pass can be correlated with the hydrogen partial pressure, space velocity, and conversion by plotting against temperature the logarithm of one variable at constant values of the other two variables. The relationship which we have found may be expressed by the equation:

where T is the catalyst temperature in C., Tea is the catalyst reduction temperature in C., In is a factor with a range as indicated hereinafter, and D is expressed by the equation:

In the above equation, P represents the initial absolute partial pressure of hydrogen in atmospheres, SV is the hourly liquid space velocity of hydrocarbons charged to the process ,(expressed as liquid volume of hydrocarbons per hour per unit volume of catalyst space), and C is the conversion of the charged hydrocarbons into lower boiling hydrocarbons in per cent by volume. By the expression, the initial partial pressure of hydrogen, we mean the partial pressure of hydrogen in the total fluids entering the reaction zone.

The two equations referred to above may be combined as follows to express the catalyst temperature necessary for demethylation:

where T=catalyst temperature in C.'; p

Toa=a temperature of from 425 to 650 C. at

which the catalyst was previously reduced;

70:18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres;

2:25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P the initial absolute partial pressure of hydrogen in atmospheres;

(SV) =the hourly liquid space velocity at which the saturated hydrocarbon is charged to contact with the catalyst;

C=the conversion of the charged saturated hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

The is of the above indicated equation was evaluated upon the basis of a large number of experimental results obtained with different nickel and cobalt catalysts which had been reduced in hydrogen at several different temperatures from about 425 to about 650 C. Some of these results so obtained at widely different experimental conditions are shown in Example I. An average of about 20.7 was obtained as the value of k at absolute partial pressures of hydrogen above 3.45 atmospheres when using hydrogen or a mixture of hydrogen and methane as the processing gas, while at absolute partial pressures of hydrogen below 3.45 atmospheres, k had an average value of about 27.9. The catalyst temperature calculated by the above equation and by using the average value of k may not be the optimum temperature for obtaining a particular conversion, but it will be an operative temperature to give the desired demethylation reaction. After this operative temperature is found, it may be necessary to make slight adjustments therein in order to determine the temperature needed for optimum conversion into demethylated hydrocarbons.

The following examples are given to illustrate the process of this invention, although with no intention of limiting unduly its generally broad scope.

EXAMPLE I A nickel-diatomaceous earth catalyst prepared as hereinabove set forth was heated in a stream of hydrogen at the temperatures indicated in Table I for 12 hours and then cooled to room temperature, after which a mixture of nitrogen and air was passed through the reduced catalyst to render it substantially non-pyrophoric. The resultant catalyst was then used as a granular filler in a steel reactor through which hydrogen and a trimethylpentane mixture, the latter consisting of approximately 35% of 2,2,3-trimethylpentane, 10% of 2,3,3-trimethylpentane, and 55% of 2,3,4trimethylpentane, were passed at total absolute pressures of from about 4.4 to about 55.5 atmospheres corresponding to partial hydrogen pressures of from about 3.4 to about 44.4 atmospheres. Results obtained in these runs are shown in Table I together with the value of k calculated from the experimentally determined conversions to lower hydrocarbons observed at the indicated catalyst temperatures, pressures and space ve- TABLE I Ton, Cata- Total Molar ratio of Partialhmhw Hourly Conversion to Run N0 lyst reduc- '1 Catalyst press. processing gas gen pressure liquid lower hydrok tion temp., temp, C atmos. to hydrocaratmos abs space carbons, per

C. abs. bon reactant velocity cent 1 Processing gas was a hydrogen-methane mixture.

EXAMPLE II A cobalt-diatomaceous earth catalyst was prepared inthe same manner as was the nickel-diatomaceous earth catalyst described in Example I with the exception that the cobalt carbonate was decomposed by heating before being formed into pellets. The pelleted cobalt-diatornaceous earth catalyst was reduced by heating in hydrogenat 371 C. for 16 hours and then by continuing the heating in hydrogen at 454 C. for 24 hours; The catalyst was then cooled to about 20 C. and used as a filler in a reactor through which 4.8 molecular proportions of hydrogen and 1 molecular proportion of trimethylpentane were passed at'the conditions shown in Table II. In each of these runs the trimethylpentane mixture was charged at an hourly liquid space velocity of. 2.0. 1

.TABLE II Demethylatzon of trimethylpentane mixture per pass. As shown by the results given in Table III, catalyst temperatures between 264 and 322 C. were employed at pressures of from 7.8 to 35.1 atmospheres absolute using hourly liquid space velocities of neohexane of from 0.5 to 1.46 and varying the molar ratio of processing gas to neohexane between 3.7 and 11.2.

1 Processing gas was a hydrogen-methane mixture. Y

EXAMPLEIVY Demethylation runs were made on several pure trimethylpentanes in the presence of some of the nickel catalyst described in Example [li and utilizing the same operating procedure. Theresults obtainedin theseruns and given in Table ,IV aresimilarto those obtained in Example Ion .a mixture v01E trimethylpentanes.

TABLE 1 Demethylation of several trimethylpentcmes Run No- 19 2c Hydrocarbon charged" 2,2,3-trimethylpentane. f 2,3,3-trimethylpentane T Catalyst reductio 538 '538. y

- into lowerboiling hydrocarbons was 2.4 to 37.2%

Different alkyl cyclohexane hydrocarbons were also demethylated in the presenceof the 'n'iclrel catalyst following 'thelprocedure; of Examples I and v. Results soobtained on ethylcyclohekane and 1gmethyl-4itertiary butylcyclohexane1 are anaaors TABLE V Demethylatzon of alkyl cyclohewane hydrocarbons Run No 21 33 Hydrocarbon charged Ethylcyclol-methyl-4-tert-butylhexane. oyclohexane.

Ten, Catalyst reduction 538 538.

mp., C. '1, Catalyst temp, C 288 280. Pressure, atmos:

Total 14.6 14.6.

Partial of hydrogen, P 12.2 12.2. Molar ratio of processing gas 5.0 5.0.

to hydrocarbon reactant. Hourlyliquid space velocityv 1.5. 1.9. Conversion to lower hydro- 3O 17.

carbons, per cent. Chief dcmethylation product M ethylcyl-methyl-4-iso-propylclohcxane. eycloheranc. k 20.6. 19.9.

EXAMPLE VI Neohexa-ne and some of the trimethylpentane mixture as charged in the runs of Example I were demethylated in the presence of the nickeldiatomaceous earth catalyst at absolute partial pressures of hydrogen below 3.45 atmospheres with the results shown in Table VI.

TABLE VI Demethylation of neohexane and trimethy'lpentunes at partial pressures of hydrogen below 3.45 atmospheres absolute Run N 13 l4 l 1 16 17 Hydrocarbon charged Trimethylpentane Neohexane mixture Ton, catalyst reduction temp, C. 538 538 427 427 538 '1, Catalyst temp, C 273 252 218 221 229 Pressure, atmos:

Totalnn 2. 72 1.02 1.02 1.02 1.02 Partial of hydrogen, P 2. 09 0.78 0.82 O. 73 0.80 Molar ratio of processing gas to hydrocarbon reactant 3. 3 3. 2 4. 0 2. 5 3. 7 Hourly liquid space velocity l. 58 1.67 0.36 0.73 0.53 Conversion to lower hydrocarbons,

per cent 44. 5 27. 5 62 33 48 25.0 28.0 30.2 30. 7 25.6

The demethylation products obtained in run Nos. 13 and 14 were similar to those obtained in Example I. The above indicated run Nos. 15-1 yielded neopentane as the main reaction product.

The nature of thepresent invention and type of results obtained are evident from the specification and examples although neither section should be construed to limit unduly the broad. scope of the invention.

We claim as our invention:

1. A process for demethylating a paraflinic hydrocarbon having at least 5 carbon atoms per molecule to produce therefrom a paraffinic hydrocarbon of lower molecular weight which comprises reacting a paraffinic hydrocarbon having at least 5 carbon atoms per molecule includ- 7 T:0.26[TCR100] +76 logiol (14.7 .P) (SV) C] where T=catalyst temperature in C;.; I Ton a. temperature of from 425 to 650 C. at which the catalyst was previously reduced;

lc=18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres;

lt=25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P=the initial absolute partial pressure of hydrogen in atmospheres;

(S-V) =the hourly liquid space velocity at which the paraffinic hydrocarbon is charged to Contact with the catalyst;

C=the conversion of the charged parafiinic hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon,

2. A process for demethylating ncohexane to produce therefrom neopentane which comprises reacting neohexane with hydrogen in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt at a catalyst temperature of from about 150 C. to about 385 C. and defined by the equation:

T=0.26 [Toe-] +70 logmi (14.7 P) (SV) C] where T=cata1yst temperature in C.;

Tca=a temperature of from 425 to 650 C. at which the catalyst was previously reduced; 7c:18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres; k:25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P:the initial absolute partial pressure of hydrogen in atmospheres;

(SV) :the hourly liquid space velocity at which the neohexane is charged to contact with the catalyst; and

C=the conversion of the charged neohexane into neopentane expressed as per cent by volume of the charged neohexane.

3. A process for demethylating a parafiinic hydrocarbon having at least 8 carbon atoms per molecule to produce therefrom a parafiim'c hydrocarbon having 1 carbon atom less per molecule which comprises reacting a paraffinic hydrocarbon having at least 8 carbon atoms per molecule including in each molecule an alkyl group of at least 2 carbon atoms with hydrogen in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt at a catalyst temperature of from about C. to about 385 C. and defined by the equation:

Where T=catalyst temperature in C.;

Ton=a temperature of from 425 to 650 C. at which the catalyst was previously reduced; Ic=18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres; 7c=25 to 30.7 at an initial absolute partial pres sure of hydrogen below 3.45 atmospheres;

P=the initial absolute partial pressure of hydrogen in atmospheres;

(SV) :the hourly liquid space velocity at which the paraffinic hydrocarbon is charged to contact with the catalyst;

C'=the conversion of the charged paraffinic hydrocarbon into lower boiling paraffinic hydrocarbons expressed as per cent by volume of the charged hydrocarbon;

and thereafter separating demethylated p-arafilnic hydrocarbons formed in the process from unconverted paraffinic hydrocarbon and recycling said unconverted paraifinic hydrocarbon to further treatment with hydrogen in the presence of the catalyst.

4. A process for demethylating a cycloparafiinic T=catalyst temperature in 'C.; V Tca a temperature of from 425 to 650 C. at which the catalyst was previously reduced; k= l8.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres; Ye -1:25 to. 30.7 at an initial absolute partial pres- ,M SUJQOf' hydrogen below 3.45 atmospheres; P=the initial absolute partial pressure of hydroen in atm p S V)'=Lthe "hourly liquid spacevelocity at which thecycloparafiinic hydrocarbon is charged to contact with the catalyst; v

C=the conversion of the charged cycloparaflinic hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

5. A process for producing triptane which comprises reacting a paraflinic hydrocarbon having at least 8 carbon atoms per molecule including a triptyl group with hydrogen in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt at a catalyst temperature of from'about 150 C-. to about 385 "C. and defined by the equation:

T=0.26[TCR-100]+k 1ogm[(14.'7 P) (SV) C] where r Tamas temperature in c.;

ToR=a temperature of i from 425 to 650 C. at

'1 Tkwhich' the catalyst was previously reduced;

lc:18.4,to'23.3 at aninitial absolute partial presijsure of hydrogen above 3.45 atmospheres;

:jk=25' to 30;? "at an'initial absolute-partial pressure of hydrogen below 3.45 atmospheres;

P=the initial absolute partial pressure of hydrogen in atmospheres;

(SV) =the hourly liquid space velocity at which the paraflinic hydrocarbon is charged to contact with the catalyst.

C=the conversion of the charged parafiinic hydrocarbon into lower boiling paraffinic hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

6. A process for producing triptane which comprises reacting hydrogen and a' paraffinic hydrocarbon with a structure indicated by the formula:

in which R represents an alkyl group and R to R inclusive, represent at least one member of the class consisting of an alkyl group and a hydrogen atom, the process being carried out in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt and at a catalyst temperature of from about I4 150C. to about 385 'C. andidefinedby'the equa:

tion: Y

T= 0.26[5 loe-100]+lc log1o[(14.7 R) (SV) 01 where T='catalyst temperature in C.; T Toa=atemperature of from 425 to 650 C. at

which the'catalyst was previously reduced; lc=l8.4 to 23.3 at an initial'absolute partial pressureof hydrogen above 3.45 atmospheres; [c -2513c 30.7 at an initial absolute partial pressure of hydrogen be1ow'345 atmospheres; Pl= the initial absolute partial pressure of hydro; gen. atmosphere sf (SV) '=the hourlyliquid space velocity at which the paraffinic hydrocarbon is charged. to conv tact with the catalyst,

C=the 'o'nvrsion of the charged parafiinic hy- 'd'ro carbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

- 7. A processior ,demethylatin-g a saturated hydrocarbon to produce therefrom a saturated hydrocarbon of lower molecular weight which comprises reacting a'saturated hydrocarbon having at least 5 carbon atoms per molecule including an alkyl group 'o'fatleast "2 carbon atoms with hydrogen in the presence of a catalyst comprising 'a metal selected from thegroup consisting of nickel and cobalt at a catalyst temperatureof from about 150;Cgtoabout 385 C, aind dcfined by the equation:-

where T=catalyst temperaturein-FZCQ f the saturated hydrocarbon is charged to contact with the catalyst; and C=the conversion of the charged saturated hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

8. A process for demethylating a paraflinic hydrocarbon having at least 5 carbon atoms per molecule to produce therefrom a paraffinic hydrocarbon of lower molecular weight which comprises reacting said parafiinic hydrocarbon having at least 5 carbon atoms per molecule with hydrogen in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt at a catalyst temperature of from about 150 C. to about 385 C. and defined by the equation:

T=0.26[Tca-] +Ic 1Og1o[(14.7P) (SV) C] where T=catalyst temperature in C.;

Tca=a temperature from 425 to 650 C. at which the catalyst was previously reduced;

70:1.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres;

ls=25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P=the initial absolute partial pressure of hydrogen in atmospheres;

(SV) =the hourly liquid space velocity at which the paraflihic hydrocarbon is charged to contact with the catalyst; and

C=the conversion of the charged parafiinic hydrocarbon into lower boiling paraifinic hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

9. A process for demethylatin'g a saturated hydrocarbon having at least 8 carbon atoms per molecule to produce therefrom a saturated hydrocarbon of lower molecular weight which comprises reacting a saturated hydrocarbon having at least 8 carbon atoms per molecule including in each molecule an alkyl group of at least 2 carbon atoms with hydrogen in the presence of a catalyst comprising a metal selected from the group consisting of nickel and cobalt at a catalysttemperature of from about 150 C. to about 385 C. and defined by the equation:

T=catalyst temperature in C.;

ToR=a temperature of from 425 to 650 C. at

which the catalyst was previously reduced; 10:18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres;

10:25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P=the initial absolute partial pressure of hydro-- gen in atmospheres;

(SV) =the hourly liquid space velocity at which the saturated hydrocaiibon is charged to contact with the catalyst; and

C=the conversion of the charged saturated hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

10. A process for demethylating a cycloparaffinic hydrocarbon having at least 8 carbon atoms per molecule to produce therefrom a saturated hydrocarbon having 1 carbon atom less per molecule which comprises reacting a cycloparaflinic hydrocarbon having at least 8 carbon atoms per molecule including in each molecule a ring of T=catalyst temperature in C.;

Tea=a temperature of from 425 to 650 C. at which the catalyst was previously reduced; k=18.4 to 23.3 at an initial absolute partial pressure of hydrogen above 3.45 atmospheres; k=25 to 30.7 at an initial absolute partial pressure of hydrogen below 3.45 atmospheres;

P'=the initial absolute partial pressure of hydrogen in atmospheres;

(SV) :the hourly liquid space velocity at which the cycloparaffinic hydrocarbon is charged to contact with the catalyst; and

G=the conversion of the charged cycloparafiinic hydrocarbon into lower boiling saturated hydrocarbons expressed as per cent by volume of the charged hydrocarbon.

VLADIMIR HAENSEL. VLADIMIR N. IPATIEF'F.

REFERENCES CITED The following references are of record in'the file of this patent:

FOREIGN PATENTS Country Date Great Britain Aug. 14, 1924 OTHER REFERENCES Num e