US3018237A

US3018237A - Radioethylation of paraffin hydrocarbons

Info

Publication number: US3018237A
Application number: US717662A
Authority: US
Inventors: Peter J Lucchesi; Barry L Tarmy
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1958-02-26
Filing date: 1958-02-26
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23

Description

Jan. 23, 1962 P. J. LUCCHESI ETAL 3,018,237

RADIOETHYLATION OF PARAFFIN HYDROCARBONS Filed Feb. 26, 1958 DILUENT PARAFFINIC 3 5 HYDROCARBON FEED RADIATON 4 ALKYLATE PRODUCT 7- K l t SOURCE SEPARATION 6 ETHYLENE By a. Q. M Attorney Inventors UnitedStates Patent (3 3,018,237 RADIOETHYLATION OF PARAFFIN HYDROCARBONS Peter I. Lucchesi, Cranford, and Barry L. Tar-my, Summit, N.J., assignors to Esso Research and Engineering Company, a corporation of Delaware Filed Feb. 26, 1958, Ser. No. 717,662 7 Claims. ((11. 204-154) This invention relates to the radiation conversion of hydrocarbons and more particularly to the production of saturated branched-chain hydrocarbons by the reaction of parafiinic hydrocarbons with ethylene in the presence of high energy ionizing radiation. The products are normally liquid saturated branched-chain hydrocarbons boiling chiefly within the motor fuel boiling range, i.e. 65 to 430 F[ and are extremely useful for upgrading refinery gases and light virgin naphtha to high octane gasoline components.

This application is a continuation-in-part of co-pending applications, Serial Nos. 655,909 and 655,910, both filed Aprl 29, 1957, by the present inventors, and are now abandoned.

In commercial operations petroleum refineries have large quantities of light hydrocarbon mixtures available. However, there recently has sprung up a greater demand for the isoparaflinic hydrocarbons than for the normal paraffinic hydrocarbons, making it necessary to incorporate new facilities in the ordinary refinery in order to obtain increased amounts of the isoparaffins which serve not only as blending agents for the normal parafiins but also as intermediates and reactants in the preparation of normally liquid hydrocarbons which are also useful in motor fuels. Often for such purposes particular alkylation products are necessary.

Generally, the conversion of parafiin-oleiin mixtures has been carried out in the presence of various alkylation catalysts, promoters and activators, and complicated separation and recovery processes have been required to obtain the desired alkylate product. Heretofore, however, it generally has not been possible to successfully alkylate normal parafiinic hydrocarbons by these processes. Apart from troublesome problems caused by introduction of contaminants into the alkylate product, the foregoing operations result in major corrosion in alkylate fractionating column-s, reflux accumulators, in transfer lines, and in charge storage tanks. Further, at temperatures where equilibrium is favored and pressures required are moderate, reaction initiation has been slow. On the other hand at temperatures where initiation of reaction is rapid, equlibrium has been unfavorable and extremely high pressures have been required.

Photochemical initiation of parafiin-olefin reactions also has serious drawbacks. Common resonance lamps suffer from instability and need continued maintenance. Optical heterogeneity, opacity of the particular medium, and the relatively low penetrating power of ultra-violet rays are also problems. Photochemical initiation is possibly only near atmospheric pressure with monomers which absorb in the regions of the spectrum for which intense sources are available and can never be used for processing requiring high-pressure, thick walled reaction vessels.

with parafiins by subjecting a mixture of these hydro-.

carbons to high energy ionizing radiation. Specifically the preferred process of the present invention comprises irradiating a paraffinic hydrocarbon having from 2 to 8 carbon atoms with high energy ionizing radiation, in

the presence of a small amount of ethylene, preferably about from 0.1 to 30 weight percent, based upon the ,total weight of paraifin and ethylene in the feed, until at least about l x 10" kwh. of radiation energy per pound of hydrocarbon feed has been absorbed, and recovering, as a product of the reaction, a higher molecular weight branched-chain homologue with a yield in the range of about from 200 to 10,000 molecules per electron volts absorbed.

In the preferred process, conversion is carried out at a temperature in the range of about 500800 F. at about to 600 p.s.i.g. pressure with a total radiation dose of between about 10* and 10 kwh. per pound of hydrocarbon feed.

While free radical alkylation of isoparafiins with feed olefin has been one of the promising Ways of making branched parafiins for use in high octane fuels, alkylation using normal parafiins has never been achieved by the conventional commercial process. The present invention is of particular importance because it provides a method of converting, to higher molecular Weight branched-chain homologues, normal parafiinic hydrocarbons which have never been in as great demand as the more useful isoparafiinic hydrocarbons. The present discovery is, however, even more surprising in that it has new been found that an important product of the present process is the branched-chain isomer of the normal paraifin reacted. For example, the irradiation of normal butane with high energy ionizing rays in the presence of a small amount of ethylene results in a surprisingly high yield of both isopentane and isobutane. The reaction thus utilizes the less valuable normal parafiins in a novel radiolysis process and yields both alkylate and the corresponding isomeric isoparaffin with product selectivity in the range of about from 40 to 70 wt. percent.

In another specific embodiment of the present invention, isobutan is reacted in admixture with ethylene under the influence of high energy ionizing radiation to produce a high yield of isopentane.

Broadly, any paraffin, that is, any saturated, aliphatic hydrocarbon having two or more carbon atoms can be reacted with ethylene according to the present invention. Particularly the process is applicable for the conversion of parafiinic hydrocarbons having from 2 to 12 carbon atoms. Most intersting are the paraffin-s having from 2 to 8 carbon atoms and mixtures of these. Cyclic paraffins with alkyl or aryl side chains can likewise be converted according to the present process. Mixtures of two or more of these hydrocarbons can also be alkylated.

Various refinery gases such as ethane, propane, C and C cuts from thermal or catalytic cracking units, field butanes which have been subjected to prior isomerization or partial dehydrogenation treatment, and spent gases and liquid products from catalytic polymerization processes are also useful as feed stocks for the present invention. It is only essential that the feed stocks to the process contain at least one paraflinic hydrocarbon and also contain an initial concentration of ethylene, present in an amount between about 0.1 and 30 weight percent, based upon the total weight of paraflin and ethylene in the feed. By the irradiation of the paratfin alone one cannot achieve the novel results of this invention.

Particularly advantageous for the present process is a refinery hydrocarbon feed boiling at a temperature in the range of from about 10 to 200 F. containing at least 75 weight percent of I a parafiin-ethylene mixture wherein the concentration of olefin is equal to that given above, i.e. between about 0.1 and 30 weight percent. Furthermore, the presence of hydrogen is not deleterious to the reaction. Therefore, an unpurified refinery gas stream is suitable for use in the reaction. A particularly useful feed stock for the present process is Arabian virgin naphtha which has a high concentration of C C and C paraflins.

As has already been stated it is desirable to employ a substantial molar excess'of the paratfinic component of the feed stock. Further, according to this invention, e'htylene in amounts in the range of about 0.1 to about 30 weight percent is added to a feed comprising a paratfin and the mixture exposed to high energy ionizing radiation of an intensity and for a duration sufficient to convert at least one weight percent, based on total feed, of the paraffin. Most preferably, from about 0.5 to about 10 weight percent of ethylene is utilized, and the radiolysis of the feed mixture is carried out by exposing it either continuously or batchwise to the radiation. The unconverted constituents can be then returned to the reaction zone in an ordinary recycle process. The surprising feature of the present discovery is that the novel radiolysis process does not result simply in additron of paratfin to olefin but, rather, results in a surprismg amount of disproportionation. For example, for the alkylation" of the butanes with ethylene according to this invention, the paraffin is converted to the next higher branched-chain homologue (one additional carbon atom) and with a product selectivity of at least 30 weight percent based on total product. This is truly a surprising discovery.

Advantageously the process of this invention is carried out in the vapor phase. For the vapor phase conversion in the presence of high energy ionizing radiation, the reaction occurs in the temperature range of 300 to l000 F. at a pressure between about 10 to about 1000 p.s.i.g. Preferably the radiolysis of paraffins and ethylene is carried out at a temperature of between about 500 and 800 F. at a pressure of between about 150 and 600 p.s.i.g.

The radioethylation reaction of the present invention is carried out by exposing the parafiin or parafiin mixture in contact with small amounts of ethylene to high energy ionizing radiation, that is high energy quanta (radiation wave length less than 50 A.), neutrons, and charged and uncharged particles of atomic and sub-atomic nature having energies greater than about 30 electron volts. Types of radiation suitable for the purposes of invention include high energy electro-magnetic radiation such as gamma and X-rays, high velocity electrons as well as beta rays, alpha particles, protons, deuterons, fission fragments and neutrons. These types of radiation can be supplied by-radioactive materials, nuclear machines or by common neutron sources. Fission by-products of processes generating atomic power or fiissionable materials which emit high energy gamma rays also afford a highly desirable and most abundant source of radioactivity suitable for the purposes of the invention. These by-products include those with atomic numbers ranging from 30 to 6 3 and their compounds. They are formed in the course of converting uranium and thorium and other fissionable materials in an atomic reactor.

In one embodiment of the invention, the irradiation with gamma rays and neutrons can be carried out most conveniently, particularly on a commercial scale, by employing an atomic pile, that is, a nuclear reactor. This particular source of radiation can be utilized on either a batch or continuous basis. More specifically, for example, a batch reaction can be carried out simply by irradiating the material in a container. In carrying out a continuous process the material to be irradiated can be pumped through pipes disposed in the atomic pile. Generally, the radiation from an atomic pile will consist primarily of neutrons and gamma rays. The neutron flux existing in these atomic piles generally will be in the range of about 10 to 10 usually about 10 to 10" neutrons per centimeter squared per second and gamma ray dosage will generally be from about 10 to 10 usually about 10 to about 10" roentgens per hour. Conventional moderators can of course be used, such as water, carbon, and hydrocarbons. Radiation fields in the range of 10 to 10 rep./hr. are employed. In some cases the feed stream itself can serve as a moderator. Materials made radioactive by exposure to neutron irradiation such as radioactive cobalt-60, which emits gamma rays, can likewise be used with radiation fields in the range of 0.1 to 10 rep/hr. Suitable sources of high velocity elec-' trons are the beams of electron accelerators such as the Van de Graafi electrostatic accelerator, resonant transformers and linear accelerators. For example, radiation intensities of the order of 4x10 rep/sec. are obtained with electron beams.

In general, however, high velocity electrons, high energy gamma rays, and neutrons are preferred for the purposes of this invention mainly because of the high penetrating power of the rays and the availability and ease of application of these sources of high energy ionizing radiation. By high energy ionizing radiation is meant the ionizing radiation from controlled terrestrial sources of suflicient energy that the dose rate is at least 1X10 kwh. per pound of hydrocarbon reactant per hour, and capable of penetrating through 0.1 millimeter of lead sheet. This excludes radiations such as cosmic and ultraviolet, which are ineffectual for the purposes of this invention.

The radiolysis of a paraffnic hydrocarbon, such as normal butane or isobutane with ethylene to produce a high yield of isopentane, can be carried out utilizing a wide radiation does range. The amount of feed converted in the process of this invention varies in a substantially linear fashion with time at a fixed radiation dose rate over a very wide range. This means that according to the present radiation process the conversion of the reactants varies substantially directly with time for a contsant rate of radiation energy absorbed over a wide concentration of unreacted reactant, for example, from 100-50 weight percent of unreacted reactants. As the total amount of conversion becomes large and the concentration of unreacted reactant becomes increasingly smaller, the rate of conversion naturally falls off. For radioethylation reactions in accordance with the present invention, a wide radiation doserange therefore can be employed. Preferable dosages are from about 10- to about 10 kwh. per pound of reactant.

(l roentgen equals l.06 l0'- kwh./lb.)

A total energy absorption of from about 10- to about between 300 and .1000 F. For example, for the radiolysis of butane-ethylene mixtures, temperatures in the range of between about 600.F. and about 700 F. are employed most advantageously. The optimum operating temperature of course varies somewhat wtih pressure, that is, the higher the pressure, the higher the optimum temperature for high yields. Suitable pressures for conversion range between and about 1000 p.s.i.g. Most advantageously pressures between about 150 and 600 p.s.i.g. are employed according to this invention. Conversion at higher temperatures is less desirable since in creased cracking lowers the yield of alkylate. The lower temperature limit is set by the liquification temperature. The lower pressure limit is set by the amount of undesirable material (cracking) that is obtained. 20 p.s.i.g. will yield reasonable yields. The upper limit on pressure is set by the upper level of conventional pressure equipment.

According to the present invention small amounts of ethylene can be added to a paraflin or to paraifin mixtures and the resultant mixture subjected to high energy ionizing radiation of an intensity and for a duration sufficient to convert a substantial proportion of the mixture to a conversion product. This product containing sub stantial amounts of higher molecular weight branchedchain isomers can be separated from the reaction medium and fractionated within the desired boiling range. The unreacted parafiin can be then returned to the reactor to be further converted to more useful products. Advantageously mixtures of parafiin and ethylene are fed into an atomic reactor in a continuous feed system. Radiation does rate is determined by geometrical considerations and therefore total energy absorption is determined by feed rate. Contact times can vary from a fraction of a minute per pass up to an hour or more. In batch reactions contact time can be from about one-half hour to about 200 hours. In general it is desirable to convert only a portion of the par-aflin-ethylene feed in a single pass through the radiation zone in the continuous system. The product can be recovered outside the reaction zone and the unreacted parafiin returned to the radiation reactor in an ordinary recycle process. In this way the probability that alkylate product will be cracked by continuing the radiation reaction after the product is formed is reduced. Advantageously only about 1 to about 50 percent of the reactant is converted in the radiolysis process and unreacted reactant is returned for further processing following the separation of the desired product.

No special type of apparatus is required for carrying out the novel conversion process of this invention. The

usual alkylation equipment has been found to be entirely satisfactory. However, since the novel process avoids the use of the corrosive catalyst of the prior art it is unnecessary in order to preserve the equipment to construct the apparatus coming in contact with the reactants of the alkylation process out of acid resistant metals.

The novel features which are believed to be characteristic of the invention both as to its organization and method of operation will be understood more clearly and fully from the following description considered in con nection with the accompanying drawing.

Referring to the drawing in detail, it will be seen that the paraifnic hydrocarbon to be converted is admitted to the process by line 1. Ethylene is supplied to line 2 by line 7.

The ethylene component added to the paraflinic feed can be controlled in order to obtain high yields of conversion product. The amount to be added is determined in any convenient manner as by observing the composition, distribution or yield of the products or by monitoring the admixture entering the radiation reaction zone. This can be done by continuous analysis, for example, by continuously measuring the product quality or continuously measuring by spectroscopic techniques the ethylene composition of the feed mixture. Preferably the ethylene content of the mixture is in the range of about 0.5 to about 10 weight percent.

The resultant mixture is then exposed to high energy ionizing radiation in a radiation zone using a conventional radiation source 3. For example, this source can cornprise an atomic pile or nuclear reactor, and the mixture can simply be passed through in suitable conduits. It can flow around or through the core of the reactor and in some cases the hydrocarbon mixture can serve as a moderator. Suitable conditions of pressure and temperature are maintained during the alkylation.

Another suitable source of radiation comprises atomic Waste products obtained from nuclear reactors or atomic piles. This material can be suitably enclosed or concentrated as in an underground storage area and the hydrocarbon mixture can be passed through or around the waste material."

Electron accelerators of the linear type and Van de Graaff generators can be employed as a source of high energy electrons. The electrons are directed through a thin, suitably reinforced window into the hydrocarbon mixture.

The converted material is removed by line 4 and passed into a suitable product separation zone 5. This zone can comprise, for example, a distillation zone, several flash vaporization chambers, a solvent extraction zone, an absorption zone or a combination of any of these.

The desired products are removed from zone 5 by line 6 and preferably but not necessarily the unreacted paraffin and ethylene are recovered and removed by line 2 for recycle to the feed stream as indicated.

Preferably, the product separation zone 5 comprises a molecular sieve having pore openings of about 5 A. It has been known for some time that certain zeolites, both naturally occurring and synthetic and sometimes termed molecular sieves have the property of separating straight-chain from branched-chain hydrocarbon isomers, as Well as from cyclic and aromatic compounds. These zeolites have innumerable pores of uniform size and only molecules small enough to enter the pores can be adsorbed. The pores may vary in diameter from 3 or 4 A. to 15 A. or more, but it is a property of these zeolites or molecular sieves that any particular product has pores of substantially uniform size. The scientific and patent literature contains numerous references to the adsorbing action of the natural and synthetic zeolites. Among the natural zeolites having the sieving property may be men tioned chabazite. A synthetic zeolite with molecular sieve properties is described in US. Patent 2,442,191. Zeolites may vary somewhat in composition but generally contain the elements silicon, aluminum, and oxygen, as well as an alkali metal or an alkali earth metal. The naturally occurring zeolite, analcite, for instance, has the empirical formula NaAlSi o l-i o. A large number of other naturally occurring zeolites having molecular sieve activity, that is the ability to adsorb a straightchain hydrocarbon and exclude or reject the branchedchain isomers and aromatics because of differences in molecular size, are described in an article entitled, Molecular Sieve Action of Solids, appearing in Quarterly Reviews, volume 111, pages 293-320, 1949, published by The Chemical Society (London). Molecular sieves suitable for the present invention comprise sieves having pore openings in the range of from about 4 to 7 A. The molecular sieve heretofore described is arranged in any desired manner in the adsorption zone of separation zone 5. It can, for example, be arranged on trays or packed therein with or without support. A fluid bed of powdered adsorbent can also be used. Conditions maintained in the molecular sieve treatment in adsorption zone 5 are flow rates of about 0.1 to about 5 v./v./hour, temperatures of about 200 to about 350 F. and pressures from atmospheric pressure to several p.s.i.g. With molecular sieves of the indicated size of pores, the normal paraffins contained in the feed are readily adsorbed while the isoparafllns are not, but instead are passed by line 6 to suitable product containers.

- The particular advantage of utilizing a molecular sieve separation zone can be seen by considering, for example, the present conversion process with, for example, normal butane and ethylene. The two major products are isopentane and isobutane. Because the conversion product, namely, isopentane is normally used for upgrading refinery gases and light virgin naphtha to high octane gasoline components, the presence of significant amounts of isobutane is extremely beneficial. Since ethylene may not be used up in the present process, this reaction results mainly in the conversion of low value normal paraffins in high yields to a product consisting essentially of branched-chain parafiins. Unconverted normal paratfinic constituents can be recovered readily by the utilization of molecular sieves and returned by a recycle process to the reactor.

In some instances it is desirable to employ radiation resistant diluents in the alkylation process in order to control the amount of conversion. These are introduced by line 8 into the feed prior to its entering the radiation zone. Gradually any common diluent which is substantially inert to high energy ionizing radiation is suitable for this purpose. For example, highly refined mineral oils such as a white oil advantageously can be employed.

In some instances it may be desirable to employ a combination process whereby the ethylene is produced either by a conventional process such as steam cracking or by high temperature radiation cracking followed by the vapor phase radiolysis reaction between ethylene and paraffin. In this manner, for example, a paraffinic hydrocarbon such as isobutane can be converted to the higher isoparafiinic homologue (one additional carbon atom) by the radiolysis of essentially that paraffinic hydrocarbon alone. However, in this instance a two-step process is necessary. The preliminary step can either be a mild cracking step to produce only the 0.1 weight percent of ethylene essential for the reaction or greater treatment to produce high yields of ethylene which can then be mixed with another paraflinic hydrocarbon stream to the desired ethylene concentration. In the latter embodiment of the present invention it is proposed to combine the two radiation zones. It should be noted that while reaction conditions can be chosen at which ethylene is produced, the addition of ethylene is always required to start the radioethylation reaction if a one step reaction is employed.

To further illustrate the invention the following examples are presented:

PILE IRRADIATION Example 1 I (A) A typkal run in a nuclear reactor:

(1) Oper tin c"dltions Once-through flow equipment. Temp rature, 650 Prcssur 0.5.1.2. 550 Conta t time, minut 2 Radiation energy absorb 3X10 Mat rial balance, weight per 90. 6 Reactor volume, cc 670 (2) Feed composition, weight percent on feed- Ethylene 2. Isobutane 97. 5

I (A) A typical run in a nuclear reactor-Continued Product yields, weight percent on iced Ethylene 2. 5 isobutane 95. 5 Ethylene free dry gas 0. 3 But lIlCS 0. 2 Alkyittv 1. 6

100. 0 (3) Reaction selectivity, weight percent on feed reacted- Dry gas 14 Butencs- 10 Isopsutane 58 Aikyiate, isopentane-iree 18 100 (4) Feed consumption, weight percent Ethylene 0 Isobutane 2.0 (5) Radiation yields, molecules made/100 ev.

Dry gas 1, 000 Butenes 25 Isopeutane W0 Alkylate, isop entan e-Iree 100 1 Includes H2, CH CiH 0 H: and 0 11;.

The composition of the alkylate product (containing 5 or more carbon atoms) is given in Table I:

TABLE I.COHPOSITION OF PRODUCT (\VEIGHT PERCENT) This example clearly shows that radiolysis of isobutaneethylene mixtures in the vapor phase results in the production of isopentane with high selectivity and high radiation yields. The process illustrates disproportionation "alkylation in a novel radiolysis process. The data clearly indicate that higher molecular weight branchedchain homologues can be produced from a paraffin alone by the addition of small amounts of ethylene. and the radiolysis of the mixture at low pressures.

The surprising feature of the present invention is well illustrated by the above example, namely that the radioethylation of isobutane with ethylene under the influence of high energy ionizing radiation results in the production of isopeutane. The reaction is thus a disproportionation process and is markedly different from the conventional thermal alkylation. This is further illustrated by Example 2.

Example 2 tion yield of these three fractions are as follows:

R diation ield (m l 1 Component: reactlng per ton at Gas C -430 F. gasoline 270 Polymer 35 The major product of this reaction is isopentane. The complete yields after comparison of these products with conventional thermal alkylation is presented in the accompanying table. It is seen that the conversion reaction is TABLE II.-.OOMPARISON OF PILE ALKYLATION WITH THERMAL ALKYLATION [Feedz Isobutanc-ethylene mixture] Pile reaction Thermal alkylation Mole percent ethylene Temperature, F. Pressure, p.s.i.g Contact time, minutes Yield, weight percent on feed Component, weight percent on product:

a Parafiius:

Iii-H 2,2-dimethylbutane 2,3-dimethylbutane co 9 s s ps s e 00 2-methylpentane B-methylp entane- Methyl cyclohexane.

Ca naphthene Oleflns:

Cine

8 Aromatics Saturates The above examples show that high energy ionizing radiation can be used to react parafiins with ethylene in the vapor phase at milder conditions than those used in thermal alkylation. While the free radical (thermal) reaction requires 800-950 F. and 4500-6000 p.s.i.g., the radiolysis reaction can take place at 500-800 F. and at 150-60 p.s.i.g. Further, it is seen that the distribution of products from the neutron reaction differs greatly from that obtained thermally.

Example 3 Hydrocarbon mixtures consisting of straight-chain parafiins having about from 2 to 8 carbon atoms, and mixtures thereof have been irradiated in the presence of small amounts of ethylene with high energy ionizing radiation comprising neutrons to produce higher molecular weight branched-chain homologues with radiation yields in the range of about 200 to .1000 molecules per 100 ev. energy absorbed. Pile irradiation at an intensity of approximately 1.06 10- kwh, per pound of hydrocarbon re actant per hour was employed in all experiments reported in this example.

Irradiation temperatures for the various experiments were in the range of about 500 to 800 F. at pressures of about from 150 to 600 p.s.i.g. Feed compositions contained about from 0.5 to 10 mole percent of ethylene based upon total feed. For continuous runs, flow rates were of the order of 1400 cc. (liquid) per hour and contact times of the order of from 1 to 4 minutes. Typical conversion reaction data according to this invention for n-butane-ethylene mixtures at 550 p.s.i. are given in Table III. Conversions of only 2-5 wt. percent were employed in order to better evaluate the product.

1 Product having 5 or more carbon atoms. Ethylene free dry gas.

TABLE IV.PRODUCTS MADE FROM PILE IRRADIA- TION OF n-BUTANE-ETHYLENE AT 550 P.S.I.

Temperature, F.

Weight percent on total product:

0. 5 ll. 5 8. 1 3. 2 1. 1 3. 0 0 3. 2 20 41 40 16.6 9.7 4.0 4.6 14.7 0 1.0 U 0 46 15.5 26 25 2.2 1.0 1.4 4. 7 4.8 4.5 0 3.1 Hexenes 4. 8 0 0 0 Liquid product 1 4. 8 4.0 2.0 0 Total conversion, weight percent; on

feed 1.85 2. 00 7. 03 4. 69 Contact time, min 3.1 2.6 2.7 2.0

1 0 excluding N0 and NO The above example clearly demonstrates the novel and surprising process which has been discovered. These data show that a hydrocarbon mixture consisting of at least one straight-chain paraflin having about from 2 to 8 carbon atoms can be irradiated in the vapor phase with high energy ionizing radiation at temperatures in the range of about from 500 to 800 -F. in the presence of in the range of 0.5 to 10 mole percent of ethylene to produce a conversion product with radiation yields of about from 200 to 1000 molecules per ev. absorbed. It is seen that in the radiolysis of, for example, n-butane-ethylene mixtures, isobutane plus isopentane make up 40-70 wt. percent of the total product. Product selectivity to isopentane was about from 15 to 46 wt. percent. Comparison of isobutane and isopentane yields is given in Table V.

TABLE V Molecules made per 100 ev. lemp., F.

Isobutane Isopcntane The above data show that at critical temperatures ethylene produced in situ from the butane is sufficient to carry the reaction once it has been initiated by the addition of ethylene to the reaction mixture.

The above example shows that light gasoline of high octane can be produced under the influence of high energy ionizing radiation from mixtures of butane and ethylene. Radiation yields of the order of 200l000 molecules of product per 100 ev. can be obtained. The principal products of the reaction are isopentane, C olefins, and other branched light hydrocarbons. The process is particularly useful for upgrading refinery gases and light virgin naphtha to high octane gasoline components.

The radioethylation reaction with propane has been carried out under a variety of conditions. Table VII displays the results of neutron irradiation of propane in the presence of 10 mole percent ethylene at 800 F. The mixture was pumped through the reactor in the manner described above. For a contact time of 1.5 minutes with 'a dose rate of 17 megarep. per hour the yield was 6.2 weight percent on feed. Total radiation yields observed were as high as 3224 molecules made per 100 ev.

TABLE VII I Weight percent (based on feed reacted) Product distribution 150 p.s.i.g. 550 p.s.i.g.

Hydro en 2. 6 2. Mnfl'mnn 3. 7 Ethylene 0 9. 3 Propylene 8. 4 Bntnnns 11.6 Isobutane 79. 5 30. 4 n-Bntane 2.3 1 npnntane 7.1 41. 8 Panfannq 1.2

TABLE VIIL-RADIATION YIELD-43 AND HIGHER PARAFFINS [Molecules made per 100 ev.]

Pressure: 150 p;s.i.g. Pressure: 550 p.s.i.g.

502F. 650F.| 800F. 496F. 601F. 708F.l818F.

Typical pile irradiation conversion reaction data according to this invention for pentane-ethylene mixtures are given in Table IX. Radiation yields as high as 300 molecules per 100 ev. and selectivities up to 25 wt. percent on feed reacted have been obtained.

.TABLE IX Feed: Isopentane-ethylene (20/1 moi ratio) rossure, p.s.l.g.: 550 Contact time, 2-6 minutes Temperature, F 513 524 649 055 791 Conversion, weight percent on feed:

Ethylene-free cracked 0.7 0.3 0. 9 2. l5 l7 0. 6 0. 4 1.6 1. 1 1 2.1 1. 0 0. 2 2. 3 8 0. 1 0. 2 0.1 0. l 0.02 0.2 0 3 0 4 0. 2 0

Total 3. 7 2. 2 4. 2 6. 2 2i Selectivity, weightpercont on feed reacted: Ethylene-fr as 19 14 45 40 81 Ethylene 16 I8 38 18 5 '8. 57 45 5 7 14 C1 Alkylate- 3 9 2 2 0 C. polymer 5 14 10 3 0 Radiation yield, molecules/ ev.:

1 Primarily 2,3 and 3,3 dimethyl pentane.

GAMMA IRRADIATION Example 4 Gamma radioethylation reactions were carried out utilizing a C0 radiation source. The facilities employed were of conventional type and have been fully described by J. F. Black et al., The International Journal of Applied Radiation and Isotopes 1, 256 (1957). To illustrate the present invention, the experimental data for the propane-ethylene system is given in Table X. The conversions were carried out at an intensity of 0.12 megarep/hr., at 55 atm. using 8/1 mole ratios of propane/ethylene. Material balances were better than 96 wt. percent and all radiation yields refer to experiments in which the blank (thermal) contribution was subtracted out if present. One hour batch exposure of the feed at 700 F. resulted in 23 wt. percent conversion of ethylene and a yield of branched chain paraffins (having 4 or more carbon atoms) of 300 wt. percent based on ethylene reacted. Radiation yields (G) in the range of 1000l0,000 have been recorded.

The above example shows that light hydrocarbons can be upgraded to high octane products with high radiation yields by irradiating a mixture consisting essentially of ethylene and a paraffin having from 2 to 8 carbon atoms with high energy ionizing radiation comprising gamma rays.

ELECTRON IRRADIATION A High Voltage Engineering Corporation, model AK-S, 2 mev. Van de Graafi electron accelerator was utilized in a series of radioethylation reactions withdifferent parafiin hydrocarbons. This is a conventional electron accelerator.

Example 5 The electrons were passed into the reaction cell through a 15 mil steel window with intensities in the range of 1 to 40 megarep./hr. Typical data for the radioethylation reaction of the present invention utilizing electrons is presented in Table XI.

TABLE XL-EIJECTRON 'RADIOETHYLATION Ca/Ca= STUDIES AT 150 AND .550 P.S.I.G.

Run No 3 2 5 4 Mole percent 12 12 12. 8 11.4 emp., 650 650 650 650 Pressure, p;s.i. 550 550 150 150 Contacttime, min. 1. 5 1. 5 1.0 1.0 Mrep 19 37. 5 14 30 Conversion, welghtpercent on fee .4 2. 6 3. G l 1. 3 Selectivity, weight percent on feed 35 9 v 0 4 13 1 Polymer 33 50 Material balance percent recovery.-- 94.0 86.2 101.4 97.7 \Veight percent 54+ o,- reacted.-." 161 rss 156 179 Example 6 Comparison of the radioethylation reaction with ordinary radiolysis of pure hydrocarbons.The novel features of the present radioethylation process can be illustrated by comparing the irradiation reactions of parafiinethylene mixtures in accordance with this invention with prior irradiation processes involving pure hydrocarbons. Table )GI illustrates these differences by giving, as an example, the results 'for the radiolysis of the butanes and also the ethylene-butane systems. Similar results for n-pentane and n-pentane-ethylene are recorded in Table XIII.

TABLE XIL-C'OMPARISON OF PILE IRRADIATION OF BUTANES AND BUTANE-ETHYLENE MIXTURES AT 650 F., 550 P.S.I.G. 55

Isobun-Butane/ tane/ Feed Isobuethylene n-Buethylene tane 2.5 tane 4.8

weight mole percent percent Contact time, min 2. 6 2.0 4. 5 2. 7 Conversion, weight percent] min 0.3 2. 3 0. 84 2. 6 Material baL, weight percent; 94 91 92 96 V Molecules made/100 ev:

Ethylene Free Dry Gas. 470 1, 000 720 3, 500 C 20 1, 000 90 1, 013

Ethylene 0 0 75 0 Selectivity, weight percent on feed reacted:

Ethylene free dry gas. 29.1 11.5 29.0 26. 2 Ethyl o 2. 5 6.0 o n-Butane 53. 0 0 0 0 Is0butane. 0 0 39 40 Butenes... 5. 6 10 7. 3 4.6 Isop ane l3. 0 58 16. 4 26 Alkylate isopentane free). 0 18 2. 3 3. 4

TABLE XIIL-YIELDS AND SELECTIVITIES IN PILE RADIO- ALKYLATION OF nCs/Cz' AT 550 P.S.I.G., 400/800 F., 2-3 MIN. CONTACT TIME Temp., F-.. 400 451 492 647 756 Contact time,

min Mol. percent Or. MaterialvaL,

weight percent Conversion,

weightpercent on feed/mil-.. Radiation yields,

molecJlOO ev.:

Cr cracked CH Selectivity,

weight percent on feed reacted:

heptanes 1 Average of 2 experiments.

PRODUCTS FROM FILE IRRADIATION (2.7 MIN.) n-PENTANE AT 550 P.S.I.G. AND 650 R Selectivity, weight per- Product: cent on feed reacted H 0.77 C 7.38 C 2.64 C 26.41 C 15.10 C 46.17 C4:

1 Material balance 94.1 weight percent.

The above example shows that the irradiation with high energy ionizing radiation of a hydrocarbon mixture consisting essentially of a paraifin and ethylene results in the production of a higher molecular weight branched-chain homologue of the parafiin with a radiation yield in the range of about 200 to 1000 molecules per ev. absorbed by the mixture. Little if any alkylate is produced by the radiation of pure parafiins under the same conditions. Comparison of the data in Table XIII shows that ethylene must be initially present to get any alkylation at all.

Example 7 Refinery feed stocks such as light virgin naphtha can be upgraded by exposure to high energy ionizing radiation in the presence of ethylene in accordance with this invention. In this example on Arabian light virgin naphtha (122/ 213 F.) was irradiated in a nuclear pile in the manner already described. The feed composition is given in Table XIV and shows the major components to be nC -nC paraffins. The data obtained are given in Table XV.

TABLE XIV.-COMPOSITION OF ARABIAN 122/213 F.

LVN USED IN PILE RADIOALKYLATION EXPERI- MENTS Gross (FIA) Saturates volume percent 96.4 Olefins do 0.7 Aromatics d 2.9 Composition, weight percent (GLPC):

nc, 0.3 1C5 2.7 RC 7.8 22 DMB 0.2 2 MP, 23 DMB 12.2 3 MP 8.6 nC 35.4 24 DMP, 22 DMP 7.5

u n n 1.18 23 DMP, 33 DMP 7.5 2 MH, 3 MH 5.2 3 EP 2.5 RC7 M CyH 0.9 CqHa 0.6 RON+3 cc 76.0

Mercap an No., mg./ 100 cc.

TABLE XV.-PILE-INDUOED UPGRADING OF ARABIAN VN BY 27 MIN. EXPOSURE AT 500 P.S.I., 6 MOL PERCENT Temperature, F 502 650 800 Conversion, weight persent on feed 19. 4 17.0 29. 4 Setleetivlty, weight percent on feed reacted Dry gas 9. 73 1 3. 85 29. 27 ('3 0. 12 10. 83 20. 47 6.10 15. 26 12. 15 14. 80 12. 26 3. 96 2. 63 5.16 40. 91 32.80 or er 0 (mostly unlden fins) 58. 63 40. 91 82. 80 G, molecules made per 100 ev.:

Dry gas 165 80 850 0 product 240 250 320 Feed cut (122/2l3 F.) inspections:

RON+3 cc. TEL (unirradiated teed=76). 78.1 80.9 Mercaptan number (unirradiated teed= 17.9) 3. 2

1 This number not considered reliable.

The above example shows that a hydrocarbon feed stock containing at least 75 percent by weight of a paraffinethylene mixture can be upgraded in quality. Alkylation yields in-the range. of 240320 were observed. At 800 F. a most significant change was obtained in RON (3 cc.)

TEL which was increased from 76 to 81 with only 29 wt. percent conversion of the feed.

What is claimed is:

l. A hydrocarbon conversion process which comprises subjecting a hydrocarbon mixture consisting essentially ofa paraffin having from 2 to about 8 carbon atoms per molecule and in the range of 0.1 to 30 weight percent of ethylene to a total dosage of high energy ionizing radiation in the range of about 10- to 10 kwh. of radiation energy per pound of said hydrocarbon mixture at a. temperature in the range of about 500 to 800 F. and a pressure in the range of about 150 to 600 p.s.i.g., and recovering a higher molecular weight branched-chain homolog of said paraffin with a radiation yield in the range of about 200 to 10,000 molecules per 100 ev. absorbed by said mixture.

2. A process according to claim 1 wherein said higher molecular weight homologue is recovered with a product selectivity of about from 30 to 70 weight percent.

3. A process for producing isopentane which comprises exposing a mixture of butane and ethyleneat a temperature in the range of about 500 to 800 F. and a pressure in the range of about 150 to 600 p.s.i.g. to high energy ionizing radiation of an intensity and for a duration sufficient to produce isopentane with a yield in the range of about 200 to 1000 molecules per ev. absorbed by said mixture said mixture containing in the range of from 0.1 to 30 weight percent of ethylene.

4. A hydrocarbon conversion process which comprises irradiating with high energy ionizing radiation a refinery hydrocarbon feed at a temperature in the range of about 500 to 800 F. and a pressure in the range of to 600 p.s.i.g. until a total dosage of radiation energy in the range of from 10- to 10 kwh. per pound of said feed has been absorbed, said feed essentially consisting of about 0.1 to 30 weight percent of ethylene and parafiin having from 2 to about 8 carbon atoms per molecule, and recovering a higher molecular weight branched-chain homologue of said parafi'in.

5. A hydrocarbon conversion process which comprises irradiating with high energy ionizing radiation a hydrocarbon mixture, in the vapor phase, at a temperature in the range of about 500 to 800 F. and a pressure in the range of 150 to 600 p.s.i.g. until in the range of 10* to 10 kwh. of radiation energy has been absorbed per pound of said mixture, said mixture consisting of about 0.1 to 30 weight percent of ethylene and a paratfinic component selected from the group consisting of parafiins having from 2 to about 12 carbon atoms per molecule and mixtures thereof, and recovering a converted product with a yield in the range of about 200 to 10,000 molecules per 100 ev. absorbed by said mixture.

6. A hydrocarbon conversion process which comprises continuously passing into a radiation reaction zone a hydrocarbon feed stock containing at least 75 percent by weight of a paraflin-ethylene mixture, said mixture consisting of about 0.1 to 30 weight percent of ethylene and at least one parafiin having from 2 to 8 carbon atoms per molecule, irradiating said feed stock with high energy ionizing radiation at a temperature in the range of about 500 to 800 F. and a pressure in the range of 150 to 600 p.s.i.g. until at least 10- kwh. of radiation energy per pound of feed stock has been absorbed, continuously removing a reaction product from said radiation zone, separating unconverted feed stock from the desired conversion product, recycling said unconverted feed to said reaction zone and continuously feeding a fresh supply of hydrocarbon feed stock to said reaction zone.

7. A process according to claim 6 wherein said unconverted feed stock is separated in a molecular sieve adsorption zone.

References Cited in the file of this patent UNITED STATES PATENTS 2,636,853 Franklin Apr. 28, 1953 2,743,223 McClinton et al Apr. 24, 1956 2,762,768 Cier Sept. 11, 1956 2,872,396 Wilson et al. Feb. 3, 1959 FOREIGN PATENTS 1,148,720 France June 24, 1957 708,901 Great Britain May 12, 1954 OTHER REFERENCES Bourne et al. -Chem. and Ind," pages 1372-76, November 24, 1956.

Collingson et al.: Chemical Reviews) vol. 56, No. 3, pages 47784, June 1956.

Claims

1. A HYDROCARBON CONVERSION PROCESS WHICH COMPRISES SUBJECTING A HYDROCARBON MIXTURE CONSISTING ESSENTIALLY OF A PARAFFIN HAVING FROM 2 TO ABOUT 8 CARBON ATOMS PER MOLECULE AND IN THE RANGE OF 0.1 TO 30 WEIGHT PERCENT OF ETHYLENE TO A TOTAL DOSAGE OF HIGH ENERGY IONIZING RADIATION IN THE RANGE OF ABOUT 10-6 TO 103 KWH. OF RADIATION ENERGY PER POUND OF SAID HYDROCARBON MIXTURE AT A TEMPERATURE IN THE RANGE OF ABOUT 500* TO 800*F. AND A PRESSURE IN THE RANGE OF ABOUT 150 TO 600 P.S.I.G., AND RECOVERING A HIGHER MOLECULAR WEIGHT BRANCHED-CHAIN HOMOLOG OF SAID PARAFFIN WITH A RADIATION YIELD IN THE RANGE OF ABOUT 200 TO 10,000 MOLECULES PER 100 EV. ABSORBED BY SAID MIXTURE.