US2315144A - Treatment of hydrocarbons - Google Patents

Description

March 30, 1943. WATSON 2,315,144

TREATMENT OF HYDROCARBONS Filed May 11,1939

CHARGE CATALYTIC DEHYDROGENATION ZONE SEPARATION HYDROGEN FRACTION 5 HYDROGEN DESULFURlZATlON ZONE NORMALLY 9 GASEOUS HYDROCARBONS HYDROGEN AND |o HYDROGEN J SULFIDE SEPARATION HYDROCARBONS HEAVIER THAN IGASOLINE GASOLINE v INVENTOR KENNETH M. WATSON ATTORNEY Patented Mar. 30, 1943 TREATMENT OF HYDROCARBONS Kenneth M. Watson, Chicago, 111., assignor to Universal Oil Products Company, Chicago, 111., a corporation of Delaware Application May 11, 1939, Serial No. 272,950 2 Claims. (Cl. 196--24) This invention relates to a process for converting hydrocarbon oils of relatively high sulfur content into valuable hydrocarbon oils of relatively low sulfur content and which, in addition to being substantially sulfur-free, are also substantially olefin-free. The gasoline obtained as a final product or contained in the final product is particularly valuable for blending in aviation fuel because it contains predominantly aromatic and parafiinic hydrocarbons.

More specifically, it is concerned with a process which involves a novel sequence of steps wherein provisions are made for subjecting the hydrocarbon oil to dehydrogenation treatment followed by desulfurization treatment by hydrogenation to produce a product substantially free of sulfur and containing predominantly paraflinic and aromatic hydrocarbons.

Various processes have been proposed for treating hydrocarbon oils of. relatively high sulfur content, a satisfactory one being the hydro refining process. This process involves contacting the hydrocarbon oil with hydrogen in the presence of a suitable catalyzing agent at relatively high temperature and superatmospheric pressure whereby the sulfur, present either in a combined or a free state, is converted to hydrogen sulfide and the hydrocarbon molecule is substantially completely saturated with hydrogen. The process when used alone, however, is relatively expensive to operate, partly because of the high cost of hydrogen and because it reduces the octane number of the finished gasoline produced unless severe operating conditions are employed and, in this case, the yield is materially reduced. In the present invention in order to produce a valuable product substantially free of sulfur, a

dehydrogenation treatment which involves the conversion of parafiins to olefins and/r conversion of naphthenes to aromatics, the former corresponding to the removal of one molecule of hydrogen while the latter corresponds to the removal of three molecules of hydrogen, is combined with the hydro refining treatment which involves the removal of sulfur as hydrogen sulfide bylhydrogenation using the hydrogen produced in the dehydrogenation treatment.

In one specific embodiment the invention comprises subjecting hydrocarbon oil to dehydrogenation treatment to convert a substantial portion thereof into unsaturated compounds without materially altering its boiling range, subjecting the dehydrogenated products, together with the hydrogen produced in the dehydrogenation treatment, to desulfurization treatment by hydrogenation in the presence of a catalytic mass and under selected conditions of temperature, pressure and contact time whereby the sulfur is removed as hydrogen sulfide and whereby only partial hydrogenation is effected so that the resulting treated hydrocarbon oil is predominantly aromatic and paraflinic.

The term dehydrogenation treatment as used throughout the specification and claims refers both to the conversion of parafllnic hydrocarbons into olefinic hydrocarbon and to the conversion of naphthenic hydrocarbons into aromatic hydrocarbons. For example, a parafflnic hydrocarbon, such as normal hexane, may be converted to its corresponding olefinic hydrocarbons by the removal of one molecule of hydrogen, the resulting compound having a single double bond in its structure. This reaction may be accomplished in the presence of the same catalyst and under substantially the same conditions of temperature and pressure as the reaction which involves converting cyclohexane to benzene, which reaction involves the removal of six atoms or three molecules of hydrogen, the resulting compound having three double bonds and retaining its cyclic structure.

The dehydrogenation treatment will ordinarily produce relatively large quantities of olefinic hydrocarbons, the presence of which is undesirable in an aviation gasoline because of the relatively high acid heat test of the gasoline and because of the poor lead susceptibility of the olefinic hydrocarbons. 0n the other hand, gasoline containing predominantly paraffinic and aromatic hydrocarbons, even though the octane number be lower than the oleflnic gasoline unless isomeric compounds are present, has a lower acid heat test and good lead susceptibility. I have found that I can obtain a gasoline product having the properties desirable in an aviation gasoline by subjecting the products of dehydrogenatie to desulfurization treatment under selected temperature and pressure conditions and in the presence of selected catalytic masses whereby the sulfur present, either in the combined or free state, is removed as hydrogen sulfide and the olefinic hydrocarbons are hydrogenated to parafiins, while substantially no hydrogenation of the aromatic hydrocarbons is effected.

Hydrocarbons heavier than gasoline, which may be included in the charging stock to the dehydrogenation treatment, may consist of hydrocarbon oils, such as, for example, cracked or straight-run kerosene or gas-oil fractions, which after desulfurization and hydrogenation are parpounds'orf more per-. squa ,pheric. I

ticularly valuablebecause oftheir saturated character, since the-Diesel fuels derived from said gas-oil fraction-are of relatively high octane number.

-In the accompanying diagrammatic drawing, in orderv to illustrate the process of the invention, without'complicating it with unnecessary details of each specific step, the general practice "of illustratingeach specific step in detail has been departed from and; the flow diagram used 7 instead.

Referring to the accompanying flow diagram, the hydrocarbon oil charging stock,'which may consist of straight-run or cracked or reformed gasoline, cracked or straight-run kerosene,'or

' -.of hydrogen which is used in the desulfurizing treatment, and in subsequent steps of the procline I to zone 8 and,-when desired, fresh hydro- .gen introduced through line I may be commingled with the hydrogenseparated in zone 4 in line 8. The dehydrogenated products are subjected to contoct with a suitable catalyzing agent in zone 8 in the presence of hydrogen to convert the sulfur to hydrogen sulfide and, in

ass conditions are preferably regulated so that the aromatics remain as such in the final product.

. Catalysts which have been found tobe highly" 'efiicient in the-dehydrogenation of parafiinic or.

I 1 enic h drocarbons to unsaturated hydro- Y naphth y tures on the order of 750 to 1000' F. may be emcarbons consist in general of pellets or granules of magnesium oxide composited with a chromate of a metal selected from the group consisting of lead, zinc, magnesium, cadmium, iron, nickel,

cobalt, -copper,' aluminum, and the alkali metals, and/or a metallic oxygen-containing salt selected .from the group consisting of sulfates, nitrates. and acetates of vzinc, copper and aluminum.- Although these catalysts are the preferred catalysts they are not tojbe considered as a limiting-feature, forcatalysts, such as, for examhand columns of groups4=,'5, and 6 in the periodic table, and others known to those skilled in theart may be em loyed within the broad scope of the invention.fl' lemneratures' for exfl ample, from (50 tol4002; l '.,,but preferably from 900 to 110091". may be 'employed'-when utilizing atmospheric or sub-atmospheric to l00 the hydrogen andany normally gaseous hydrorate theEh'ydrog'en" as previously 'ihe cohver's'ioniproductsirom separation zone I, in .'the case"here5j.are through "-'line. I tddesulfutiziztipn treatmentiin zone I.

inch superatmostogether the normaladdition, to effect hydrogenation of the olefinic hydrocarbons to parafilnic hydrocarbons while employingv selected" conditions so that the arcmatics remain unaffected.

Catalysts which may be employed in the desulfurization of hydrocarbon oils consist in general of the oxides of molybdenum, aluminum, chromium, tungsten, and vanadium, the sulfides of molybdenum, calcium, and cobalt, or mixtures of these compounds. In addition such catalysts as metallic nickel or copper, either alone or mixed or as promoters on suitable supports, may be employed. 'The preferred catalysts, however, consist'essentially of the sulfides or oxides of molybdenum, because it has been found that the oxides after prolonged contact with hydrosen sulfide mixtures are converted to the sulfides andrem'ain active for a considerably longer period of time than some of the other catalysts. It is to be understood, however, that the catalysts referred toabove are not intended as a limiting feature for other catalysts capable of promotingthe desired reaction may be employed within the broad-scope of the invention.

. when .using the preferred catalyst, temperaployed with a .superatmospheric pressure rangolineand heavier unused hydrogen and hydroed .through line 3 to separation zonel wherein gen sulfide are directed through line I to separation zone lt. Separation zone It will ordinarily compri'se a fractionating zone wherein hydrocarbons boiling in therange of gasoline and normally gaseous hydrocarbons containing hydrogen sulfide and unused excess hydrogen are separated from the hydrocarbons of a higher average boiling point than that of the gasoline fraction, and condensing and. collecting equipment wherein a fraction consisting predomi-' nantlyv oi.w hydrogensulfide and excess unused hydrogen fromzone l-is separated from'the desired gasoline fraction. The fraction containing hydrogen. sulfide,.,in, the case here illustrated, is directed through line li and may, when desired,

forthfe. f mfivsl of said hydrogen sulflde andthe-nnus'ed hydrogen returned'to zone 8,

:bylwellfijknown:means" not shown. 'A-j gasoline fraetionls directed'through line 12 to cooling .andstorage or 'to fnrther treatment as desired. The heavier hydrocarbon oil fraction, whose average boilingipointg is abovethat of the de -sired"gasoline'fraetion, is directedthrough line.

n is cooling and'storage'or may. when desired,

be. subjected to further separation in a second fractionatingzo'ne, not showmto separate desirable -fltl0lLfSu0h as,for example, kerosene and Diesel fuel.

The following is anexample of-one specific operation of theprocess as it maybe accomplished when using the preferred catalyst and the preferred 1 temperature and pressure conditionsg It is not,' however, intended as a limiting feature, forvarious other catalysts well known to versed in the art may be employed within tbebroad-scope of the invention and the opand aromatic hydrocarbons. The final product erating conditions adjusted to produce the desired result.

The charging stock, a 65 A. P. I. gravity straight-run gasoline of 50 octane number and with a sulfur content of approximately 0.3, was subjected to dehydrogenation treatment in the presence of a catalyst consisting essentially of magnesium oxide admixed with minor proportions of lead chromate and zinc sulfate at a temperature of 932 F. and at substantially atmospheric pressure. The normally liquid conversion products from the dehydrogenation treatment, corresponding to approximately 90% recovery, was subjected to contact with a desulfurization catalyst consisting essentially of molybdenum disulfide (MOSz) at a temperature of approximately 850 F. and under a supe'ratmospheric pressure of approximately 3000 pounds. per square inch in the presence of hydrogen produced in the dehydrogenation treatment. The products from the desulfurization treatment had a sulfur content of approximately 0.03% and contained saturated aliphatic hydrocarbons had an octane rating of approximately 60 (motor method).

I claim as my invention:

1. A process for improving hydrocarbon oil of relatively high sulfur content which comprises subjecting the oil to contact with a dehydrogenating catalyst at dehydrogenating conditions to iorm oleflns and aromatics therein with the simultaneous production of hydrogen, and subjecting the sulfur-containing dehydrogenated hydrocarbons to hydrogenation with hydrogen formed in the dehydrogenating step a 'a temperature of about 750 to 1000 F, and under a pressure of about 750 to 5000 pounds per square inch, thereby converting the sulfur to hydrogen sulfide and effecting substantial saturation of the olefins.

2. The process as defined in claim 1 further characterized in that said hydrocarbon oil comprises gasoline fractions.

KENNETH M. WATSON.

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