US2581163A - Promoting cracking reactions of hydrocarbons by the addition of organic peroxides - Google Patents

Description

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Patented Jan. 1, 1952 'HY-pnooARBoNs BY THE ADDITION or ORGANIC PEROXJDES Richmond T. Bell, Hi

ghland Park, Ill., assignor .to The Pure OilCompany, Chicago, Ill.) a corporation of Ohio N Drawing. Application May 28, 1948,

Serial No. 29,947

23 Q aimer This invention relates to the conversion of hydrocarbons and is particularly directed "to cracking of hydrocarbons in the presence-of a small amount of a promoter Whichdecomposes rapidly under the cracking conditions. More specifically, the invention relates to the employment of certain classes of organic peroxides thermally andshock stable at ordinary tempera, tures'but sufiiciently unstable at-elevated temperatures to decompose rapidly. By incorporation'of such materials with a hydrocarbon in a reaction zone, accelerated and improvedcracking of: the hydrocarbon can be induced.

One of the objects of the invention is to provide a :method' for converting high-boiling hydrocarbons into low-boiling hydrocarbons, which method brings about improved operation .in that.

n -the re ationsh p eac to the o h r o be h einaiter described, in which process the hydro,- carbons to be converted are subjected to. cracking ndition of t me. m er u e ndr e ere admixture with asmel amount-of an organic e oxide The peroxide is pr er b ed ireotl in o th -r c ion o e. either a t e ure ompound o a so t n an r n o ventn case i vo vin the crac in o hy oc rbon iquids he r xide oe e ad ed i solut n or sp n in a or io o t e h d ocarbon iquid tse f- W en h dl n h pe oxide r mote it m o tant th tp ior o en y into the reaotion ome. it h ul not be subi c ed l ot m.- oe s er s which would ind d c osit o ereo 7 'xi housh the p i e m ani ms in o ve in h p lysi of pe oxides u der r ous le ated empe atures-hav not been mo te ebr h de d. consequently. th m hanismhe b eroxid de mp s tion prom te h d o a b con er ons c n be esta i d t eet decree of erta nty, it is be i d probable. or

example, that in general the energized peroxides decompose either by the formation of intermedi: ate free radicals, .such ashydroxyl, alkyl, alkyl 0x0, etc., or primarily to form nascent oxygen, depending on the temperature. These activated fragments and molecules enter reactions to form activated products which release their energy in various reactions and collisions to activate other molecules. The chain reactions initiated in this v/ay involve activation and deactivation by inter: molecular transfer of: energy and, because of the increased formationof chain carriers, the overall rate of hydrocarbon conversion is increased. Reroxides acquire a degree of activation not shared by the entire system, and encourage rapid initiation of reaction chains.

Whatever the exact mechanism may a be, in general peroxides will decompose rapidly and exothermally when suddenly heated, as for example, when injected into a reactor held at cracking temperatures, and the net efiect of their pres ence upon hydrocarbon cracking reactions is'to facilitate scission'of carbon to carbon bonds and produce an increased reaction velocity. It is recognized that many types of peroxides are n ou t ha e a d a ma r 'too stable and unpredictable to be. of practical value. For e am it i kn wn hat h f owfme. pe ides exp e u onhee i s ors o k; oil- 10- triacetone peroxide, diacetyl PQ QXide, diethyl rox e im h l e e ro ide-e hydr n perox cle mery roxi e. h xeio h l ne' p xy d a i hy eth keto e pe o id pht al l e xio rsuoein e o d n $l 9 .i y pe o de,

Man eroxid s u de rd na y ond t ns, however, are guite stable, andarefound within the general class ofhydroperoxides, RQQH s well as wi n the ene a l s oi rox des, ROOR, Where R represents any hydrocarbon ad ca or sub t t d h d ee boo. ra a Th s cl s es of com ound su s ydrocar on hydroperoxides, hydrocarbon peroxides, the hydroperoxides and peroxides of hydroxy derivatives of hydrocarbons, acyl peroxides, per esters, and peracids can be included. Hydrocarbon per; oxides-and. hydroperoxides constitute preferred classes for the purposes of this invention. -Within this class, becaus of generally greater stability under the ordinary conditions of thermal change nd ho vo d in eoliee onen handl n roca on. ad c l conta n at least ou arbon a oms d s conde ds u t ire e. i h y b e ehe o o i c mpounds. a e r erred To ome ext nt the ame r fe n s applicable to substituted hydrocarbon radicals. However, with the substituted radicals, the number of exceptions is somewhat greater because of the unpredictable influence of substituents. Of the classes of peroxidic compounds other than hydrocarbon peroxides and hydroperoxides, the a-hydroxyhydrocarbon hydroperoxides and peroxides, a,a'-dihydroxyhydrocarbon peroxides, and peresters are considered to be especially advantageous for the purposes of this invention. Specific examples of useful peroxides of the foregoing classes are as follows; di-tertiary-alkyl peroxides, such as di-tertiary-butyl peroxide, dit-amyl peroxide, di-t-octyl peroxide, t-butyl pentamethylethyl peroxide, di-triethylmethyl peroxide, di-t-dodecyl peroxide, etc., tertiaryalkyl hydroperoxides such as tertiary-butyl hydroperoxide, t-amyl hydroperoxide, t-octyl hydroperoxide, t-dodecyl hydroperoxide, etc., di-n-propyl peroxide, isopropyl hydroperoxide, di-sec-butyl peroxide, n-hexyl hydroperoxide, naphthene and unsaturated naphthene hydroperoxides and peroxides such as l-methylcyclohexyl-l hydroperoxide, t-butyl l-methylcyclohexyl-l peroxide, 1-methyl-3-methylene cyclopentyl-2 hydroperoxide, 2,3-dimethyl cyclopentenyl-B hydroperoxide, methyl cyclopentenyl-6 peroxide, methyl 1-isopropyl-4-methylcyclohexenyl-3 peroxide, indan hydroperoxide, methyl indan peroxide, etc., terpene peroxides such as ascaridole, limonene hydroperoxide, pinene hydroperoxide, etc., naphthalene peroxides and hydroperoxides such as tetralin hydroperoxide, methyl tetralin peroxide, etc., aromatic peroxides such as l-phenylethyl-l hydroperoxide, p-toluylmethyl hydroperoxide, etc., m-hydroxyhydrocarbon hydroperoxides and peroxides and c,a-dihydroxyhydrocarbon peroxides such as a-hydroxyheptyl hydroperoxide, a-hydroxydodecyl hydroperoxide, c-hYdl'OXYIlOnYl hydroperoxide, hydroxy dicarbethoxymethyl hydroperoxide, a-hydroxyethyl methyl peroxide,

a-hydroxymethyl ethyl peroxide, a-hydroxyethyl ethyl peroxide, a-hydroxyheptyl ethyl peroxide, e,a'-dihydroxydipropyl peroxide, a,a-dihydroxydiheptyl peroxide, a,a-dihydroxydidecyl peroxide, up. -dihydroxydidodecyl peroxide, cm. -dihydroxydiisoamyl peroxide, di-(hydroxy-dicarbethoxymethyl) peroxide, etc., peresters such as t-butyl perbenzoate, t-butyl perstearate, t-butyl perundecylenate, t-butyl diperadipate, t-butyl diperphthalate, t-amyl perbenzoate, dimethyl, diethyl, and diisopropyl perterephthalates, s-methyl perester-t-methyl camphorate, trans-Q-decalyl perbenzoate, etc., acyl peroxides such as dibenzoyl peroxide, diphthalyl peroxide, dicamphoryl peroxide, etc., peracids such as d-camphoric acid peracid, diperoxalic acid, diperbenzoio acid, diperphthalic acid, etc., and various other peroxides, for example peroxides of dioximes and derivatives thereof.

Of the foregoing examples of peroxides, most are relatively easy to prepare and quite safe to handle. Typical among these are tertiary-alkyl peroxides and hydroperoxides, hydroperoxides and peroxides of monocyclic saturated hydrocarbons having five or six carbon atoms in the ring, e-hydroxyalkyl hydroperoxides and peroxides a,a-dihydroxydialkyl peroxides, terpene hydroper'oxides and peroxides, tertiary-alkyl per- 'e'sters, peroxides of the camphoric acid series, and monocyclic aryl acyl peroxides. Ascaridole, a terpene peroxide, is naturally available in crude form as American wormseed oil. One or more of the peroxides can be added to a hydrocarbon charge by either of the methods suggested above,

so that it will be present in the reaction zone where temperature conditions will induce its decomposition, thereby to accelerate the cracking or conversion of the hydrocarbon charge.

' In a few instances, peroxides can be formed by the use of ozone, as, for example, in -thepreparation of terpene peroxides. Ramage (United States Patent 1,585,602, dated May 18, 1946) produced terpene peroxide, Ciel-11302, by blowing ozonized air through eucalyptus oil at C. After removing the peroxide by a current of air, it was further oxidized to the diperoxide, C10H1804, with an excess of ozonized air. The diperoxide is a colorless oil which, when placed in contact with water, liberates active oxygen for a long period of time. Another method for producing terpene peroxides is to contact pinene, turpentine oil and other terpene containing hydrocarbon oils at 80 C. with oxygen in the presence of a heavy metal, such as cobalt, iron, lead, chromium, nickel resinate as catalyst.

Where a stable peroxide, safe to handle, cannot.

be readily prepared and isolated, the formation in situ and immediate use thereof are indicated. In accordance with these principles, those perox-, ides most easily and efiiciently used would be the hydrocarbon peroxides, including those of olefins or diolefins. It is well known that diolefins form peroxides by reaction with oxygen much more readily than olefins. Thus, one practical embodiment of the process using certain safe, relatively stable peroxides as promoters of hydrocarbon cracking reactions would following steps:

Hydrocarbon vapors to be cracked are passedwith oxygen or air through a furnace at the rela-- tively low temperatures of about 50 to about 400 C., or temperatures approaching the lowest temperatures at which cracking of the hydrocarbon to be processed will occur, to produce a maximum concentration of peroxides. Irradiation with ultraviolet light and metallic-catalysts may be employed to increase the yield of peroxides. From this low temperature furnace, the vapors containing peroxides pass into a higher temperature cracking furnace. This procedure involving preliminary formation of peroxides accomplishes two purposes. First, peroxides are formed in the hydrocarbon to be cracked, and, second, the charge becomes desired, naphthenes, unsaturates, highly cracked naphthas, terpenes, naphthalenes, or aromatics, can be added to a charge to facilitate formation of an adequate peroxide concentration therein. Hexane, cyclohexane and cyclohexene absorb oxygen very readily when heated and the formation of peroxides therein reaches a maximum at 330, 340 and 410, respectively (Estradere, Compt. rend., 1933, 196, 674). Tetralin is easily Patent 1,924,786, dated August 29; 1933).

The cracking of the hydrocarbons in the presence of peroxides may be carried out under subatmospheric, atmospheric or superatmosphericpressures at temperatures in ranges from the lowest at which any cracking will occur, to temperatures of approximately 2000 F. The lowest temperature at which cracking will occur is determined by the composition of the hydrocarbon oil and the objective of the hydrocarbon crackingor conversion, together with the amount and i kind of the particular peroxide used to accelerate the reaction, for the thermal cracking threshold involve the preheated If temperatures for various hydrocarbons: are known. When the cracking of a hydrocarbon oil to lowerboiling'liquids'such as gasoline, is carried out, temperatures ranging from approximately 650 to 1200- F. may be used. If the cracking of hydrocarbon oils or gases is for the purpose of producing aromatic hydrocarbons, temperatures of approximately 1000 to 1500 F. may be used. When it is desired to produce butadene hydrocarbon oils, temperatures in the range 015-1300? to 1600 F. give the best yields. Hydrocarbon oils are best crackedi to gaseous hydrocarbons at"tem'peratures from. approximate1yl300 to--'3000 F.. 5 For the injection of the peroxide into the reaction zone, conventional types of thermal cracking apparatus, as well as catalytic cracking apparatus, can be used without any necessity of changing the fundamental operation of the process or redesigning the apparatus, except to make adequate provision for charging the peroxide in the correct amount. Preferably, the amount of peroxide in the reaction zone should be kept in the range from 0.05 to about 3 mol per cent. In-this connection, the peroxide is preferably introduced at successive points in aliquot parts through the reaction zone.

For example, in the practice of the invention, gas-oil is charged to a preheating coil in a thermal cracking operation conducted at a maximum temperature of approximately 900 F., and at a pressure of approximately 500 pounds per square inch. In the preheating coil, the charge is heated to a temperature of approximately 700 F., and passes into the cracking coil into which a solution of a peroxide in a portion of the gas-oil is injected in such amount that the mol ratio of the peroxide to gas-oil undergoing cracking is about 0.001. The yield of gasoline obtained is considerably in excess of that obtained in a similar operation without using any cracking sensitizer.

As a specific modification of the process outlined, a solution of di-t-butyl peroxide in benzene is injected into a reactor, in which gas-oil is undergoing cracking at a temperature of approximately 850 F., in an amount such that the mol ratio of t-butyl peroxide to gas-oil is approximately 0.01. The resultant yield of gasoline is as good as can be obtained at higher temperatures without sensitizers.

Although the specific examples involve cracking of gas-oil, it isto be understood that the invention is applicable to cracking of methane to acetylene, cracking of propane and butanes to ethylene and propylene, and cracking of hydrocarbon oils in general to lower boiling hydrocarbons, as well as to other hydrocarbon conversions, such as polyforming, isomerization, alkylation, dehydrocyclization, hydroforming, and reforming.

It will be seen, therefore, that I have succeeded in providing a way for improving hydrocarbon cracking or conversion processes in that by adding a small amount of peroxide to the hydrocarbon undergoing cracking, reforming, or other conversion, yields of desirable products can be materially increased for any particular set of reaction conditions, or the reaction can be carried out at lower temperatures and/or in less time without suffering any decrease in yield of desirable products.

What is claimed is:

1. The process of cracking hydrocarbon oil to lower-boiling liquid motor fuel hydrocarbons which consists in subjecting said hydrocarbon oil to cracking conditions of time, temperature andipressure in the'presenceofiasmall amount'of atures, saidperoxide being present in amount sufficient to induceamaterial increase in the rate.

of cracking. 1

2. The process of cracking-hydrocarbon oils to hydrocarbons substantially within the gasoline.

boiling range, which consists in subjecting the said oilsto temperaturesof approximately 650- to 1200 F., ina crackingzone in the-presence of.

approximately 0.05.to 3 molper cent of a nonexplosive organic. peroxide,. the amount of said peroxide being sumcient to induce a material in-' crease-inthe rate of'cracking.

3. The process of cracking hydrocarbon oils to hydrocarbons substantially within the gasoline boiling range which consists in subjecting the said oils to temperatures of approximately 650 to 1200 F. in a cracking zone in the presence of approximately 0.05 to 3 mol per cent of an organic peroxide, stable against explosive decomposition under shock and at ambient temperatures, the amount of said peroxide being sumcient to induce a material increase in the rate of cracking.

4. The method in accordance with claim 3 in which the peroxide is a hydroperoxide.

5. The method in accordance with claim 2 in which the peroxide is a peroxide of a hydrocarbon.

6. The method in accordance with claim 2 in which the peroxide is an alkyl peroxide.

7. The method in accordance with claim 2 in which the peroxide is an alkyl peroxide with at least four carbon atoms in the alkyl radical.

8. The method in accordance with claim 2 in which the peroxide is a tertiary-alkyl peroxide.

9. The method in accordance with claim 2 in which the peroxide is a naphthene peroxide.

10. The method in accordance with claim 2 in which the peroxide is a peroxide of a monocyclic naphthene with a ring of 5 to 6 carbon atoms.

11. The method in accordance with claim 2 in which the peroxide is a terpene peroxide.

12. The method in accordance with claim 2 in which the peroxide is an aromatic peroxide.

13. The method in accordance with claim 2 in which the peroxide is a naphthalene peroxide.

14. The method in accordance with claim 2 in which the peroxide is an alkylene peroxide.

15. The method in accordance with claim 2 in which the peroxide is an alkylene peroxide with at least four carbon atoms in the alkylene radical.

16. The method in accordance with claim 2 in which the peroxide is a perester.

1'7. The method in accordance with claim 2 in which the peroxide is a tertiary-alkyl perester of a carboxylic acid, the radical of which carboxylic acid contains at least four carbon atoms.

18. The method in accordance with claim 2 in which the peroxide is a peracid.

19. The method of cracking hydrocarbon oil to lower-boiling liquid motor fuel hydrocarbons which consists in continuously passing a stream of the hydrocarbon oil to be cracked to reaction zone, where it is maintained under cracking conditions of time, temperature and pressure and concurrently subjecting a peroxide-forming material in a separate zone to peroxidation conditions to generate a peroxide in situ which is thermally and shock stable at ordinary temperatures but which decomposes rapidly under cracking conditions, injecting an aliquot portion of said peroxide solution into the reaction zone containing the hydrocarbon in amount sumcient to create a reaction mixture containing sumcient peroxide to induce a material increase in the rate of cracking, and recovering from the reaction zone cracked lower-boiling hydrocarbons.

20. The method in accordance with claim 19 in which the peroxide-forming material is a hydrocarbon.

21. The method in accordance with claim 19 in which the peroxide-forming material is an olefin having at least four carbon atoms.

22. The method in accordance with claim 19 in which the peroxide-forming material is a naphthene.

23. The method in accordance with claim 19 in 5 which the peroxide-forming material is a terpene.

RICHMOND T. BELL.

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

UNITED STATES PATENTS Farkas et a1. June 7, 1949

Claims (1)

1. THE PROCESS OF CRACKING HYDROCARBON OIL TO LOWER-BOILING LIQUID MOTOR FUEL HYDROCARBONS WHICH CONSISTS IN SUBJECTING SAID HYDROCARBON OIL TO CRACKING CONDITIONS OF TIME, TEMPERATURE AND PRESSURE IN THE PRESENCE OF A SMALL AMOUNT OF AN ORGANIC PEROXIDE STABLE AGAINST EXPLOSIVE DECOMPOSITION UNDER SHOCK AND AT AMBIENT TEMPERATURES, SAID PEROIXIDE BEING PRESENT IN AMOUNT SUFFICIENT TO INDUCE A MATERIAL INCREASE IN THE RATE OF CRACKING.