US2355961A - Conversion of hydrocarbons - Google Patents

Description

Aug. 15,1944.

G. EGLOFF ETAL CONVERSION OF HYDROGARBONS Filed Jan. 27, 1941 lllIK INVENTOR GUSTAV EGLOFF MASLI KOMAREWSKY TTORNEY treatment.

Patented Aug. 15, 1944 UNITED STATE s v PATENT. OFFICE CONVERSION OF HYDROCABBONS Gustav Eglofl and Vasili Komarewsky, Chicago,

111., assignors to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application January 27, 1941, Serial No. 376,030

4 Claims. (Cl. 196-54) This invention is concerned with the conversion of relatively heavy fractions of petroleum, such as the gas oil fractions, into substantial yields of gasoline of both a high antiknock and a saturated character.

The invention is more specifically concerned with the treatment of heavy fractions of petroleum' with a metal halide catalyst in a combination of steps involving a primary cracking treat ment followed by an isomerization treatment of the cracked gasoline which comprises essentially a reforming operation without the occurrence of saturated gasolineof relatively high antiknock value which comprises continuously treating said heavy fractions with aluminum chloride and hydrogen'ehloride to produce substantial yields of gasoline boiling range products, fractionatin conversion products to produce gases, gasoline,

intermediate insufficiently converted refluxes and residual material, recovering said gases and said residual material, returning said insufllciently converted refluxes to further conversion, subiecting said gasoline to further treatment with aluminum chloride and hydrogen chloride to imundesirable amounts of decomposition" reactions resulting in losses of gas and heavy carbonaceous residues.

It is recognized as being known in the art to use metal halides as catalysts in cracking heavy distillate fractions of etroleum to produce gasoline boiling range materials therefrom. In genin the formation of varying yields of'hydrocarbons having both monoand di-oleilnlc unsaturation. The gasoline boiling range from these types of operations frequently require special supplementary treatments to render the gasoline marketable in ,respect to color and gum formation and stability in respect to antiknock value on storage in refineries in contact with air.

Such supplementary treatments include treat: ment with sulfuric and other acids, hydrogenation, inhibitors and many other methods of While the gasoiines produced by aluminum chloride cracking, as typical of processes employing various catalytically active metal halides, are essentially saturated, we have found that benefits are obtained if the gasoline primarly produced is subjected to further treatment ,with metal halides having an isomerizing action on the hydrocarbons in the primary gasolines. The magnitude of these effects will be developed later in the present description in connection with the examples introduced. g

In one specific embodiment thepresent invention comprises a process for converting relatively heavy hydrocarbon fractions containing substantially no gasoline into substantial yields of prove the antiknock value thereof, fractionating the products from the gasoline treatment to produce gas, isomerized gasoline and residual materials'consisting of fractions amenable to further conversion and partly spent aluminum chloride, separately recovering said gas and said isomerized gasoline and returning said residual material to the primarytconversion zone.

The essential steps of the present process will be developed in connection with the attached drawing which shows by the use of conventional figures in side elevation an arrangement of interconnected units by which the process may be carried out. The drawing is not made to any absolute or relative scale and is merely used to illustrate the general type of flow which-characterizes the process of the present'invention.

Referring to the drawing, a hydrocarbon charging stock such as a petroleum gas oil fraction or naphtha is introduced to the plant through a line I containing a valve 2 to a charging pump 3 which discharges into line 4 containing a valve I and thence through a heating element I 8 disposedto receive heat from a furnace l1. The necessary amounts of substantially anhydrous aluminum chloride may be introduced in the form of a slurry in a substantially unreactive hydrocarbon fraction by way of line 8 containing a'valve I to charging pump 8 which discharges through line 9 containing a valve I ll into line 4. The hydrogen chloride essential for the conversion reactions is introduced through. line I l containing a valve ii to charging pump or compressor l3 which discharges through line It containing 'a valve I! to line l.- Line 4 also receives primary cracked refluxes'from line 3i and secondary refluxes from line 15 along with artly spent catalysts.

The proportions of hydrocarbons, aluminum{ 4 chloride and hydrogen chloride are selected to produce optimum eyeball results, but in general, the amounts of aluminum chloride will be less than 10% of the weight of the oil, and the amounts of hydrogen chloride will -be of the order of from 1 to 5% of the weight of the oil. While the hydrogen chloride is thus evidently. in minor amounts its presence is nevertheless essential to the conversion reactions.

During the passage of the mixture of oil, aluminum chloride and hydrogen chloride through.

heating element l6 it is brought to some temperature in the approximate range of about 300- fect the desired separations. Line 26 containing a valve 21 is provided for withdrawing spent catalyst and the process is preferably operated so that the residual material retains sufiicient fiuidity to permit continuous withdrawal and recovery of the active catalyst or other decomposition products.

The vapors from lower section 2| pass through line 22 containing a valve 23 to theupper portion of the fractionating column which is preferably operated so that mixed gases containing lessthan four carbon atoms per molecule are withdrawn through line 24 containing a valve 25 while butanes are withdrawn through line 33 containing a valve 34 and the pentane fraction through line 35 containing a valve 36. Th refiuxes amenable to further catalytic conversion may be withdrawn through line 26 containing a valve 29 to recycling pump 30 which discharges through line 3| containing a valve 32 back to charging line 4.

In accordance'with the present invention, a gasoline fraction, say one boiling between the approximate range of IOU-400 F. is removed as I a side-cut through line 31 containing a valve 38 to a pump 39 which discharges through a line 40 containing a valve 4| through a secondary heating element 52 disposed to receive heat from a forming step are from about 125 to about 500 F.,.and pressure may beemployed if desired to increase the capacity of the unit although apparently pressure has very little independent affect. Rates of flow will also required adjust- -ment.to'give the propertime of contact for efiecting optimum treatment.

The products from heating element 52 pass through lin 54 containing a valve 55 to a final fractionator 56 adapted to segregate fixed gases, gasoline boiling range fractions and heavy recycled materials. Line 51 containing a valve 58 permits the'withdrawal of fixed gases which can be further fractionated if desired to separate hydrogen chloride for recycling "to either step of the process, although means for accomplishing I these ends are not shown in the drawing. Gasoline boilingrange. materialsof improved ,antiknock value ar withdrawn through line 59 containing a valve 50 and passed through condenser SI and thence to line 62 containing a valve 63 to receiver 64 which is'shown provided rials will usually consist of a small amount ofheavy reflux containing partly spent suspended aluminum chloride. Since when operations are properly conducted there is a minimum of side reactions in th second step of the process the aluminum chloride slurry withdrawn through line 69 will still have potency in effecting the primary cracking reactions. Pump H discharges into line 12 containing valves 13 and 14 and having branch line 15 containing a valve I6 for recycling reflux to line 4. Valve 14 may be used to intermittently or continuously-purge a certain amount of the spent catalyst if found desirable or necessary.

furnace 53. In a manner analogous to the prie mary conversion step, aluminum chloride either in a finely divided condition as such or on a support may be introduced as a relatively concentrated slurry by way of line 41 containing a valve 48 to pump "which discharges through a line containing a valve 5| into line 40. Requisite amounts of hydrogen chloride essential for the succeeding isomerization treatment may be introduced through line 42 containing a valve 43 to feed pump or compressor 44 which discharges through line 45 containing a valve 46 into line 40.

The conditions necessary for further isomerizing the hydrocarbons in the primary gasoline to raise the over-all antiknock value thereof will again .vary with such factors as the type of oil originally charged to the plant, the degree of conversion and the susceptibility of the individual hydrocarbons to isomerizing treatment so that only broad ranges orconditions can be laid down. While itis probable that isomerization reactions predominate in the secondary reforming step of the process, it is probable thatother reactions tak place to addto the overall reforming affect. These reactions may involve carbon to carbon splitting, dehydrogenation, particularly of naphthenes, and various types of alkylation and hydrogen transfer reactions.- The range of temperatures most commonly employed in the re-' The following example is introduced as illustrative of the results normally obtainable in the operation of the present process although not with the intention of limiting the invention in exact correspondence with the data presented.-

.A.Mid-Continent gas oil fraction was subjected to treatment, the cracking step being conducted at a temperature of 575 F. in the presence of about 10% ,by weight of finely divided granular and substantially anhydrous aluminum chloride and about 5% by weight of hydrogen chloride. In this stage of the process there was produced 46% of gasoline by volume of the oil charged, this gasoline having an octane number of 69 by the motor method of testing. This gasoline fraction was further treated with 6% byweight of granuhydrocarbon fraction containing substantially no gasoline into substantial yields of saturatedgasoline of relatively high antiknock value which comprises cracking said heavy fraction in the presence of aluminum chloride and hydrogen chloride in a primary conversion zone to produce substantial yields of gasoline boiling range products, fractionating conversion products to produce gases, gasoline, intermediate insufficiently converted refiuxes and residual material, recovering said gases and said residual material, returning said insufiiciently converted refiuxes to further conversion, subjecting said gasoline to further treatment with aluminum chloride and hydrogen chloride to improve the antiknock value thereof,- fractionating the products from the gasoline treatment to produce gas, isomerized gasoline and residual material consisting of hydrocarbon fractions amenable to further cracking and partly spent aluminum chloride, separately recovering i said gas and said isomerized gasoline and returning said residual material to the primary conversion zone.

2. -A process for converting a relatively heavy hydrocarbon fraction containing substantially no gasoline into substantial yields of saturated gasoline of relatively high antiknock value vwhich comprises cracking said heavy fraction at temperaturespf from about 300 to about 700 F. under a pressure of from 50 to about 400 pounds per square inch in the presence of aluminum chloride and hydrogen chloride in a primary conversion zone to produce substantial yields of gasoline boiling range products, fractionating conversion products to produce gases, gasoline, intermediate insufliciently converted refluxes and residual material, recovering said gases and said residual material, returning said insufllciently 'converted refluxes to further conversion, subjecting said gasolineto further treatment at a temperature of from about 125 to about 500 F. with aluminum chloride and hydrogen chloride to improve the antiknock 'value thereof, fractionating the products from the gasoline treatment to produce gas, isomerized gasoline and residual materials consisting of hydrocarbon fractions amenable to further cracking and partly spent aluminum chloride, separately recovering said gas and said isomerized gasoline and returning said residual material to the primary conversion zone.

3. A continuous process for convertinga relatlvely heavy hydrocarbon fraction containing substantially no gasoline into substantial yields of saturated gasoline of relatively high antiknock value which comprises cracking said heavy fraction at a temperature of from about 300 to about 700 F. under a pressure of from about 50 to about 400 pounds per square inch in the presence of aluminum chloride in an amount of less than 10% by weight of said hydrocarbon fraction and hydrogen chloride in an amount of from about 1 to 5% by weight of said hydrocarbon fraction in a primary conversion zone to produce substantial yields of gasoline boiling range products, fractionating conversion products to produce gases, gasoline, intermediate insufliciently converted refluxes and residual material, recovering said gases and said residual material, returning said insufiiciently converted refiuxes to further conversion, subjecting said gasoline to further treatment at a temperature of from about 125 to about 500 F. with aluminum chloride in an amount of less than 10% by weight of said hydrocarbon fraction and hydrogen chloride in an amount of from about 1 to 5% by weight of said hydrocarbon fraction to improve the antiknock value thereof, fractionating the products from the gasoline treatment to produce gas, isomerized gasoline and residual materials consisting of hydrocarbon fractions amenable to further cracking partly and spent aluminum chloride,'separately recovering said gas and said isomerized gasoline and returning said residual material to the primary conversion zone.

4. A conversion process which comprises cracking hydrocarbon oil heavier than gasoline in the presence of aluminum chloride, fractionating the resultant products to separate gasoline fractions therefrom, subjecting gasoline fractions thus separated to further treatment with aluminum cholride'under reforming conditions to improve the anti-knock value thereof, separating the reformed gasoline fractions from residual material comprising partly spent aluminum chloride and hydrocarbons amenable to cracking, and supplying at least a portion of said residual material to the aforesaid cracking step.

- GUSTAV EGLOFF.

VASILI KOMAREWSKY.

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