US2905607A - Conversion of hydrocarbons in the presence of neutron radiation and a cracking catalyst - Google Patents

Description

Sept. 22, 1959 R. B. LONG ETAL 2,905,607

CONVERSION OF HYDROCARBONS IN THE PRESENCE OF NEUTRON RADIATION AND A CRACKING CATALYST Filed April 8, 1957 HYDROCARBON FEED t F p CRACKING CATALYST :;1

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J PRODUCT Robert B. Long Henry J. Hibshmon Joh P Longwe Inventors Robert W Houston By 55. a M Attorney 2,905,607 Patented Sept. 22, 1959 lice CONVERSION OF HYDROCARBONS IN THE PRES- ENCE on NEurRoN RADIATION AND A CRACKING CATALYST Robert B. Long, Wanamassa, Henry J. Hibshman, Plainfield, and John P. Lo'ngwell, Westfield, N.J., and Robert W. Houston, Swarthmore, Pa., assignors to Esso Research and Engineering Company, a corporation of Delaware Application April 8, 1957, Serial No. 651,420

6 Claims. (Cl. 204-154) This invention relates to the radiolysis of hydrocarbons and more particularly, to the conversion of petroleum hydrocarbons by neutron irradiation in the presence of an acid center hydrocarbon conversion catalyst.

This application is a continuation-in-part of Serial No. 567,098, Preparation of Lubricating Oils by Irradiation, filed February 23, 1956, by the present inventors, and now abandoned and of Serial No. 547,860, Hydrocarbon Conversion Process, filed November 18, 1955, also by thepresent inventors, and now abandoned.

In brief compass, this invention proposes a process wherein hydrocarbons are converted in a reaction zone by neutron irradiation in the presence of an acid center hydrocarbon conversion catalyst, or cracking catalyst, at 'a temperature below 700 P. which is below the temperature range where the catalyst would have any appreciable effect on the reaction in the absence of the radiation. A product of decreased molecular weight is obtained that has an unexpectedly increased amount of branched hydrocarbons, as expressed by the ratio of isomeric pentanes (i-C to normal pentanes (n-C The conversion of feed and yield of desired product is surprisingly good.

or course of the reaction. Such processes as naphtha reforming orhydroforming, gas oil cracking, and residua coking or hydrogenation are well known in the petroleum industry.

It has now been found that by carrying out a hydrocarbon conversion reaction at a relatively low temperature in the presence of an acid type of hydrocarbon conversion catalyst under the influence of radiation comprising neutrons, unexpected results are obtained. The results of this invention are dependent on neutron irradi- Lation, probably because of the propensity of neutrons to favor C- H bond ruptures over C-C bond ruptures,

and other types of radiation do not give equivalent results. Thea lighter liquid products of this invention are especially'useful in or as gasolines. In a preferred embodiment, the C 430 FL boiling range product has an octane number above 90, Research'leaded (3 cc.). By C 'is m'eant'hydrocarbons'having 5 carbon atoms, the lowest boiling of which has a boiling point of 82 F. The

heavierliquid'products are useful in or as lubricants.

, This invention is applicable to a wide range of distillate hydrocarbon feed stocks boiling in a range of about 400 to 1150 F., eq., including distillates derived from 'co'nventional petroleum oils, shale oils, tar'sand oils, asphalts, synthetic oils, and'natural and 'artifical'hydrocarbon gases. It has the g'reatest'use in the conversion of petroleum derived 'oilssuch as whole crudes, distillate fractions therefrom, extracts or concentrates therefrom, and mixtures thereof. As later developed, however, a significant advantage is obtained by irradiating certain select feed stocks. A preferred feed stock is a hydrocarbon oil boiling in the range within the limits of 500 to 900 F. that is predominately composed of material which is not unduly branched and has a low aromatic content, i.e., contains less than 15 wt. percent of condensed rings. By not being unduly branched is meant that little or none of the feed stock contains molecules with a tertiary carbon atom.

This invention isconcerned with use of conventional cracking catalysts of high surface area. The catalyst can basically comprise materials such as silica, alumina, zirconia, titania, magnesia, and mixtures thereof. A preferred catalyst comprises 50 to 97 wt. percent silica and 3 to 50 wt. percent of alumina, with only traces of other elements being included. These catalyst materials can be derived from natural sources or can be manufactured. The materials can be used as bases or distending agents for smaller amounts, i.e., up to 10 wt percent on catalyst, of more active catalytic components. Such catalytic components can comprise elemental metals, metal oxides, sul fides, chlorides, phosphates, chromates, and other salts and mixtures thereof, of such elements as boron, aluminum, zinc, magnesium, chromium, nickel, iron, molybdenum, and mixtures thereof.

The catalyst used preferably has a particle size under about 1000 microns, but may be much larger in size if desired, e.g., to one inch or more diameter pellets can be used. The surface area of the catalyst is in the range of 50 to 600 square meters per gram (m. /gr.), the bulk density is in the range of 0.3 to 1.3 gr./cc., and the pore size is in the range of 20 to 150 A. The catalytic materials used are normally those which, upon neutron bombardment, produce radio-isotopes having short half lives, i.e., less than 10 weeks and preferably less than one Week, or have small neutron capture cross-sections so that very little of the material becomes radioactive. Preferably, the fraction (wt. percent) of any given element used in the catalyst times its capture cross-section, for neutrons having an energy in the range of 0.03 to e.v., is less than one barn.

The catalyst can be used as a suspension in the hydrocarbon reactant, or as a fixed, fluid, or gravitating bed, all of which methods are known in the art. The catalyst, if contaminated, as by carbon deposition, can be regenerated by known methods such as burning, acid treating, chemical reworking, and the like. The catalyst can be regenerated in place or external of the reactor, and either continuously or periodically, as the need arises.

This invention is based in part upon the important finding that hydrocarbon conversion catalysts in an irradiated system display an appreciable effect on selectivity at moderate temperatures, i.e. at temperatures below 700 F. This means that it is now possible to operate at lower temperatures, heretofore unattractive because of the slowness of the reaction rate. This permits the obtainance of reactions and selectivities not previously possible.

This invention is applicable to conversion reactions wherein the reactants are wholly or partly in the gas, liquid or solid phase. It is most advantageously used with liquid phase reactions and the pressure used is, therefore, preferably sufficient to maintain substantially liquid phase conditions.

The process of this invention can most conveniently be carried out, particularly on a commercial scale, by employing a nuclear reactor, and can be carried out either on a batch or a continuous basis. The present process is preferably carried out with some type of agitation or continuous flow to assure good contact between the oil, the ionizing radiation, and the subdivided catalytic solid. To carry out a continuous process, the material to be irradiated can be simply pumped through the pile itself, or through pipes disposed in the pile. In some instances, the hydrocarbon reactant can also serve as a moderator for the nuclear reactor.

The drawing attached to and forming a part of this specification schematically illustrates this invention.

In the drawing, a hydrocarbon material, e.g., a distillate virgin gas oil, is introduced into the process by line 1. A catalyst, e.g., a finely divided silica-alumina cracking catalyst supplied by line 2 from source .3, is mixed with the feed material. The preferred catalyst to oil weight ratio is in the range of 0.1 to 2.0. The resulting mixture is then passed through radiation source 4, e.g., an atomic pile. The preferred feed rate is in the range of 36 to 3600 volumes of feed per hour per volume of catalyst free reactor space (v./hr./v.) to obtain an average linear flow rate of 0.01 to 1.0 ft./sec.

The radiation from the nuclear reactor consists primarily of neutrons and gamma rays. The neutron flux used is preferably above about 10 neutrons/cm. /sec., and the associated gamma ray dosage is preferably above about 10 roentgens per hour (R./hr.). Usually the neutron flux need not be above 10 n/cm. /sec., and the associated gamma dosage need not be above 10 R./hr. The present process is most eifectively carried out employing fast neutrons, i.e. neutrons having an energy above 30 e.v. Preferably, 15 to 75% of the neutrons are fast neutrons. Of the energy absorbed by the hydrocarbon, at least 75% is derived from neutrons. The total dose used will vary somewhat with the feed, conditions, desired product, etc., but is preferably in the range of 0.3 to 3000 B.t.u.s/lb. of feed. Irradiation times necessary to achieve this will usually be in the range of 0.2 to 200 minutes. As indicated previously, to obtain the results of this invention, the conversion temperature is below 700 F., and is usally above F.

Although a suspensoid system is shown in the drawing, i.e., the solids are carried by the hydrocarbon reactant through the reaction zone, the conversion catalyst can exist as a fixed, fluid or gravitating bed within the radiation zone 4. With fluid beds, the pipes containing the reactant and catalyst preferably pass vertically through the pile with upflow of the fluid reactants.

The irradiated material is transferred by line to separation zone 6. The separation zone comprises means for recovering the catalyst such as by distillation, filtration, absorption, and chemical reaction. The recovered catalyst can be directly recycled by line 7 if desired, or can be first treated as by burning, steaming, etc. to remove contaminates and/or improve its properties before being recycled.

The hydrocarbon products are also separated in zone 6. Thus with a gas oil feed, distillation, extraction, or absorption, as with molecular sieves, can be used. If desired, some of the hydrocarbon product can be recycled by line 9.

Separation zone 6 can also include means for removing and/or neutralizing radioactive waste products, if any. Such means can include storage tanks to permit decay of radioactivity, ion exchange apparatus, distillation columns and solvent extraction units. The finished product is removed from the process by line 10.

The conversion of the feed, expressed as material converted out of the feed boiling range is above 10%. The yield on converted feed obtained is surprisingly good, being above 80 wt. percent of normally liquid product, based on a feed boiling in the range of 400 to 1150 F.

'As previously indicated, a Very highly branched product is obtained, the rat-i0 of i=C /n=C being above 1, as determined by mass spectrometer on the C fraction.

The following examples serve to further illustrate this invention.

The air cooled, natural uranium, graphite moderated research reactor of the Brookhaven National Laboratories was used for these tests. This pile was operating at a total power of about 24 megawatts at the time, which gave the following flux distribution at the point where the oils were irradiated:

Slow neutron flux (.03 e.v.) :25 X 10 n/cm. /sec. Fast neutron flux 30 e.v.) =0.7 10 n/ cm. sec. Fast neutron flux 1 m.e.v.)=0.5 X 10 n/ cm. sec. Gamma dosage: 1.7 X 10 R./ hr.

The core of the reactor was approximately a 20 ft. x 20 ft. x20 ft. lattice of graphite with horizontal oneinch diameter aluminum-clad uranium rods spaced evenly throughout the reactor extending from the north to south faces of the core. This core was completely surrounded by 5 ft. of concrete shielding. The sample holes used for irradiation were horizontal 4-inchx 4-inch square holes extending through the 5 ft. concrete shield and into the carbon core for a distance of 10 ft. from the core face. Normal operating temperatures in the experimental hole were from 250 to 400 F.

Three one-quart samples were irradiated at one time by placing them in three 3-inch diameter aluminum containers which were mounted on a horizontal aluminum sled. Vents of aluminum tubing extended from the vapor space of the containers out of the core and through the shielding to a sample receiver system where gases and condensable liquids were metered and collected. The samples were prepared by adding the solids to the container to fill it, evacuating the void space in the container, and sucking the oil into the container with a vacuum. The samples were then purged with purified nitrogen and inserted in the pile during scheduled shutdowns. After irradiation for ten days, they were withdrawn from the pile during the next shutdown.

The catalysts used were:

Alumina (Al).The alumina was prepared in a manner similar to that taught by Kimberlin in U. S. Patent No. 2,636,865. An alumina alcoholate was prepared by dissolving pure aluminum metal in alcohol. A 99.95|%

pure alumina was obtained from this alcoholate by precipitating with water, washing, and drying. The alumina was made in the form of Az-inch diameter granules which were calcined. This catalyst had a surface area of 300 In. /gr. and a pore size of 50 to A.

' Silica-alumina (Si/Al) .-Aluminawasprecipitated from aluminum sulfate solution on previously precipitated silica, by the addition of ammonia. The precipitate was then washed, dried, and calcined for several hours at temperatures up to 1200 F. It contained 13% alumina. It was pulverized and made into the form of x -inch diameter pills. The catalyst had a surface area of about 500 m. gr.

Four oils were treated:

Oil A.-A petroleum virgin paraffinic gas oil having the following inspections: Gravity of 30.7 API, bromine No. of 1.25 centigrams/ gram, 34.4 SSU viscosity at 210 F., viscosity index of 67, and 0.14 wt. percent sulfur content. The distillation characteristics were 5% off at 600 F. and oft at 700 F. at atmospheric pressure.

Oil B.-A petroleum virgin naphthenic gas oil having the following inspections: Gravity of 31.1 API, bromine No. of 2.47 centigrams/ gram, viscosity of 33.0 SSU at 210 F., viscosity index of 77, and 1.5 wt. percent sulfur content. The distillation characteristics were 12.6% off at 600 F. and 98% off at 676 F. at atmospheric pres sure.

Oil C.-A highly aromatic gas oil distilled from the product obtained by cat-alytically cracking a heavy West Texas gas oil. This gas oil contained about 3 wt. percent sulfur and distilled 5% olf at 600 F., and off at 700 F. at atmospheric pressure.

Table I A A 13 0 D Si/Al Si/Al Al Al A1 Si/Al yst/orl ratio 1.0 1. 0 1.0 1.0 1.0 1.0 Days irradiated- 10 10 10 10 10 Conversion to gas, wt. percent- 4. 4 3.0 3. 5 1. 2 7. 6 i-C5/n-C5 in gas 3.0 1. 1 5. 1 0.4 2. 2 Products:

Boiling range 70/430 70/430 70/430 70/430 70/430 70/430 Percent on feed. 5.0 9. 1 0. 3 0. 9 0.8 6. 7 Sulfur, wt. percent. 0.05 0. 40 0.27 Vol. percent aromati 14.8 18. 6 4. 3 10. 9 34.3 4. 0 Vol. percent olefins 12. 3 16. 3 40. 4 44. 5 34. 3 9. 9 Vol. percent saturates. 72. 9 65.1 55. 3 44. 6 31. 4 86. 1 Bromine No 33. 3 6. 8 4. 5 Octane N 0., calculated research leaded (3 cc.).. 9 94 9 7 93 V 95 92 Bolllng range 430/600 430/600 430/600 430/600 430/600 430/540 Percent on feed-.- 7. 1 18. 5 3. 6 7. 5 2. Sulfur, wt. percent 0. 04 0. 56 0. 02 Vol. percent aromatics- 8. 8 13. 6 6. 0 Vol. percent olefins- 34. 6 36. 4 46. 7 Vol. percent saturates.-- 56. 6 50. 0 47. 3 Gravity, API 34. 8 36. 8 37. 8 Bromine No. 27. 2 Aniline pt., F. 156 164 163 Diesel Index- 54 60 62 Boiling range 600/700 000/676 600/676 Percent on feed 43. 7 26. 9 38.8 Sulfur, wt. percent 0.06 0.57 0.03 Gravity, API 31. 8 34.3 Bromine No 0.8

Boiling range 740/900 676+ 700/900 Percent on feed 14. 37. 2 6. 6 Viscosity, SSU 210 F. 49. 52 140. 5 48.86 Pour pt., Viscosity Index 23 50 68 Boiling range 900/1, 030 900/1, 020 Percent on feed 16 14.2 Viscosity, SSU 210 F 93.34 Viscosity Index Pour pt, F -10 Boiling range 1, 030+ 1, 020+ Percent on feed 13. 8 33. 6

This table shows that by use of cracking catalysts in the presence of neutron radiation, a variety of feed stocks have been converted to high octane gasolines, high quality diesel fuels, and lubricants at temperatures where these catalysts have no activity in the absence of radiation. The yield of liquid products is very high, the conversion to gas being only 1.2 to 7.6 wt. percent on feed. The relatively high iso to normal pentane ratio is indicative of highly branched products in the gasoline range which contributes to the high octane.

The Si/Al catalyst gives a higher selectivity to gasoline and diesel fuel than the Al catalyst and produces a more aromatic and less olefinic product. This is indicative of increased hydrogen exchange activity as well as cracking activity for the Si/Al catalysts.

For this reason the use of silica-alumina catalysts in the process of this invention are preferred.

Having described this invention, what is sought to be protected by Letters Patent is succinctly set forth in the following claims.

What is claimed is:

1. An isomerization process comprising exposing a distillate hydrocarbon boiling in a range of 400 to 1150 F. in the presence of a catalyzing amount of an acid center cracking catalyst having a surface area in the range of 50 to 600 m. gr. and a pore size in the range of 20 to 150 A., to radiation comprising neutrons at a neutron flux in the range of 10 to 10 n/cm. /sec. and at a temperature in the range of 0 to 700 F. until 0.3 to 3000 B.t.u.s/lb. of irradiation have been received and the conversion of said distillate hydrocarbon is at least 10 wt. percent, and recovering a liquid product in yields above 80 wt. percent, based on converted feed, said product having an i=C /n=C ratio above 1.

2. The process of claim 1 wherein said acid center cracking catalyst essentially comprises 50 to 97 wt. percent silica and 3 to 50 wt. percent alumina, and the catalyst to oil ratio is in the range of 0.1 to 2.0.

3. The process of claim 1 wherein said product is separated to recover a fraction boiling in the range of about 82-430 F. having a leaded Research octane number above 90.

4. The process of claim 1 wherein said radiation also comprises gamma rays and is obtained from a nuclear reactor, and wherein at least 75% of the radiant energy absorbed by said distillate hydrocarbon is derived from neutrons.

5. An isomerization process comprising exposing a virgin naphthenic gas oil having a gravity of about 31.1 API in the presence of a cracking catalyst consisting essentially of silica and alumina, to a slow neutron flux of about 2.5 10 n/cm. /sec., a fast neutron flux (1 m.e.v.+) of about 0.5)(10 n/cm. /sec., and a gamma dosage of about l.7 l0 R./hr. at a temperature of about 250 to 400 F. and a catalyst to oil ratio of 1/1 for about 10 days, and recovering from the material so irradiated about 9 wt. percent of a product falling in the boiling range of about 70 to 430 F. and having a leaded octane number of about 94.

6. The process of claim 1 wherein said distillate hydrocarbon consists essentially of materials which are not unduly branched and contains less than 15 weight percent of aromatic rings, and boils within the range of 500 to 900 F.

References Cited in the file of this patent UNITED STATES PATENTS 1,627,938 Tingley May 10, 1927 2,350,330 Remy June 6, 1944 2,743,223 McClinton et al Apr. 24, 1956 FOREIGN PATENTS 665,263 Great Britain Jan. 23, 1952 OTHER REFERENCES Charlesby: Proc. Roy. Soc. (London), vol. 222A, pp. 60-74, February 23, 1954.

Mincher: A.E.C., KAPL-731, pp. 1-7, April 2, 1952.

Claims (1)

1. AN ISOMERIZATION PROCESS COMPRISING EXPOSING A DISTILLATE HYDROCARBON BOILING IN A RANGE OF 400* TO 1150* F. IN THE PRESENCE OF A CATALYZING AMOUNT OF AN ACID CENTER CRACKING CATALYST HAVING A SURFACE AREA IN THE RANGE OF 50 TO 600 M.2/GR. AND A PORE SIZE IN THE RANGE OF 20 TO 150 A., TO RADIATING COMPRISING NEUTRONS AT A NEUTRON FLUX IN THE RANGE OF 10**11 TO 10**15N/CM.2/SEC. AND AT A TEMPERATURE IN THE RANGE OF 0* TO 700* F. UNTIL 0.3 TO 3000 B.T.U.''S/LB. OF IRRADIATION HAVE BEEN RECEIVED AND THE CONVERSION OF SAID DISTILLATE HYDROCARBON IS AT LEAST 10 WT PERCENT, AND RECOVERING A LIQUIOD PRODUCT IN YIELDS ABOVE 80 WT. PERCENT, BASED ON CONVERTED FEED, SAID PRODUCT HAVING AN I=C5/N=C5 RATIO ABOVE 1.

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