US2351154A - Process for treating hydrocarbons - Google Patents

Description

June 13, 1944. w. A. SCHULZE 2,351,154

PROCESS FOR TREATING HYDROCARBONS Filed April 8, '1940 BOLVNOILDVHJ HQLVNOILDVHA CATALYST CHAMBER HOLVNOILDVHJ H25 26 REMOVER HOLVNOILDVHJ UOLVNOILDVHJ CONDENSER CATALYST CHAMBER HOLVNOIJDVHA CHAMBER CATALYST FURNACE HEATER INVENTOR WALTER A. SCHULZE BY I v @mw suppressors. I

Patented June 13, 1944 UNITED STATES PATENT j orF-lcr:

g 2,s5i,1sf4. j k mooassroa Tar-Lanna menaocaanous Walter a. sebum, momma, kla., assignor to Phillips Petroleum Company, a corporation of p ication April ,Srial;No.328,545

Q, f Claims. (Cl; 196-23) The present invention relates toa' process for the production of motorffuel fromcrizdehydmat elevated temperatures for'the production of motor. fuel with improved antiknock characteristics and a high response to lead-alkyl knock Previous investigation has shown that the, oc-

tane number response of motor fuels to; additions-of tetraethyl lead is a variant factor and greatly affected by the sulfur content of said motor fuel. Improvement in the. so-called lead response of gasoline hasbeen obtained by the process of vapor-phase catalytic decomposition 1 of the sulfur compounds, e. 1 g. U. S. Patent 2,016,271 issuedOctoberB;l935.to Schu1zeand Buell. Suoh a process is applicable to the treatment of motor fuel from any source, but the results vary somewhat when said process is ap-p plied to cracked gasolines. Y a a I have now found that greatly improved results may be obtained by a radical alteration of the processing steps used in the manufacture of the gasollnes from the basestocksa This discovery involves several co acting steps which maybe briefly described as follows: (1). acrude oil is heated under pressure and flashed under such conditions that the temperature of the vapors leaving the tower is in the range of 600 to 800' E,

the vaporizable constituents at said temperatures thus being separated from the non-vaporizable material; (2) the aforementioned vapors comprising hydrocarbonsg-in the range of gaso e,

,naphthas and gas ,oils are then passed over a dea the hydrocarbons boiling above thegasoline range 'into lower boiling components. Additional, steps which may be included are the catalytic polymerization of the light unsaturated hydrocarbons, primarily propylene and butylenes, and of finally blending these various components of high antiknock characteristics and low su fur. content into tent of the cracking stocks,the.polymer gaso ine,

also, will be much lower in sulfur contentthan that normally produced in the refinery charging undesulfurized stocks Such an innovation as the series of steps outlined above is particularly advantageous because "it has been found thatthe sulfur compoundsinvolved are less refractory in the naphthas and gas oils prior to cracking, and hence are removed to a greater extent than they wouldbe from the cracked distillates. Also, with propercontrol of desulfurizing conditions, catalyst poisoning may be greatly reduced" and longer operating cycles obtained by treatingthe total vaporizable material described above. v

Several processes are known for the desulfurization-of heavy residual oils, asphalts. tars and coal pastes but such processes involve high pressure hydrogenation and are too expensive for application to the treatment of potential motor fuel stocks My discovery, however, that heavy naphthas and gas oil fractions may be treated'in the is (to provide. a unitary process for producing an improved motor fuel sulfur."

An additional object of the present invention is to provide apro'cess for economically producing a motor fuel with improved anti-knock characteristics and a high response to knock suppressors.

As stated previously, I have-found that the from crude oil containing -maximum reduction in the sulfur content and maximum improvement in. the-lead response of the finished motor fuel-(which in this instance is considered as a blend of the various streams produced from the crude oil) may be obtained by heating the crude. petroleum oil under pressure to temperatures within the range desired for catalytic vapor-phase desulfurization, releasing the pressure on thetheated-oil to allow all the material vaporizable at said temperatures to separate from the non-vaporizable material, and passing thevapors without substantial condensation over, a contact catayst capable of effecting decomposition of the organic sulfur compounds. By operatingin this manner any step-wise fractionation or separation of liquid components of said vapor is avoided with resultant savings in I processing costs. Further, operation ,in this manimproved motor fuels. Due to the low sulfur con- 6! a s t p sible to tain good resultsin desulfurizing the heavier fractions such as gas oil, since, said fractions because of high boiling point and large content of asphaltic and/or waxy bodies are not adaptable to treatment'inthe absence of the light, lower-boiling components.

Passage of the vapors of a crude. petroleum oil at suitable flow rates of 1 to liquid volumes per hour'per volume of catalyst over acontact catalyst at temperatures between 600 and 800 F. and at pressures between zero and 100 pounds per 7 square inch results in the decomposition of a.

substantial proportion of the organic sulfur com-- I pounds into hydrogen sulfide without any substantial decomposition of the hydrocarbon constituents. Due to the absence of unsaturated hydrocarbons, there is no tendency for the hydrosures in the process may range from zero to about 300 pounds, while the fiow rate may be about 0.2 to 3 liquid volumes per hour per volume of catalyst. In such an operation the conversion temperature will depend on the percentage, of lower-boiling constituents which is left in the cracking stock afterlthe separation of straight run gasoline. Thus it is possible to operate with substantially all of the gasoline content of the desulfurized oil being charged to the cracking unit, in which casecracking temperatures may be at the higher part of the indicated range.

' This is possible because of the diluent effect of thelight gasoline which prevents over-conver-.

sion of the heavy ends.

- However, because of the excellent lead response and. the high blending value of the low-sulfur tionatlQnrand-the latter method is preferable since the desulfurized vapors must befractionated prior to subsequent steps of the present invention.

7 Fractionation of the desulfurizedvapors is carried out in asuitable unit by taking the normally gaseous hydrocarbons and the straight run gas- 'oline overhead along wlththe hydrogen sulfide,

and thus separating the hydrocarbon liquids boilingwithin the range of the desired straight run totetraethy'l lead- This-gasoline, after stabilizagasoline from the heavier kerosene, naphtha and as-oil-fractlons. From this overhead fraction there is obtained astraight run gasolineof very low sulfur content and' exceedinglyhigh response tion to remove-the normally gaseous hydrocarbolls and hydrogen sulfide, is of greatvaluein blending with stocks to make leaded motor fuels H on account ofits great lead susceptibility.

The gaseous hydrocarbons from the above-de- "scribed stabilization'may be passed to a vapor recovery plant for the'extraction of C3 and C4- hydrocarbons useful in production of motor fuels by means of thermal polymerization and the like. The heavy naphthaand gas-oil of greatly reduced su1fur c0ntent"is available for thermal or catalytic crackingto produce high octane cracked gasoline of-low sulfur'content. If thermal cracking is employed, the. resulting cracked asollne"will-have a much lower sulfur content and a] higher lead response that would be obtainable by desulfurization ofsaidcracked fuel subsequentto thecracking operation. a

The fourth step of the present invention'contemplates the catalytic conversion'of the desulfurized cracking stock over catalysts capable of supportingcrackingor splitting reactions as an integral part of theprocess.- The benefits of the '.-initial desulfurizlng step are therebyreflected not only in a motor fuel of lower sulfur content which needs no further desiilfurizing treatment excentthe removal of but also inlonger active periods fertile cracking catalyst. v

fihe catalytic cracking step is carried out by heating-the cracking stock to a temperature in the range-orator, wrote-r. and passing the v vapors 'over an adsorbent mineral ore catalyst of the bauxite type said catalyst being hereinafter referred to as a bauxite catalyst,

straight run gasoline, it is preferred to separate naturally occurring gasoline almost completely from the desulfurized stock charged to the crack ing unit. In this case, conversion temperatures are regulatedto prevent over-conversion and coking, with a secondcatalytic or thermal cracking treatment beingperformed on unconverted cracking :stockif desired after. separation of conversionproducts'fromthe initial cracking operation. The adjustmentof'operating temperatures and contact time to suit the feed stock thus is a matter of choice withinwthe scope, of this invention. .-z a H i The stream of vapors leaving the cracking catalyst may be cooled and passed to afractionator whereinthe gasoline vaporszand the normally gaseous hydrocarbons are :taken of! overhead along withany hydrogen sulfideresulting from ithe action of the crackingxcatalyst while the unconverted constituents'ofithe cracking feed stock are withdrawn asbottoms from the fractionator. 'lhis unconvertedmaterial may then be passed over a secondcrackingcatalyst for further conversion to motor fuel. The overhead 1 vapors 'from the first fractionator following the cracking unit may then be fractionated to sepastream from the cracking unit may be freed of rate normally gaseous hydrocarbons and to produce an end-point high-octane cracked'motor fuel which requires no further treatment except possiblyclay treating; g,

Thelight gasesseparated-from .the eilluent hydrogen sulfide, compressed :and passed .to a

- vapor absorption unit for separation into a lightheat inthe' cracking operation;

erfraction containing substantial amounts of hydrogen gas and a heavier fraction containing C: and C4 hydrocarbons; including substantial amounts of unsaturatedCa and C4 hydrocarbons. Said heavier fraction, or the C: and C4 portionof it, lswellsuited to passage over a catalyst for production of catalyticpolymer gasoline which after fractionation may be blended with the cracked gasoline; The lighter fraction containing hydrogen and methane may, if desired, be returned to the stream ofcracking stock, and used as a diluent gas .or source. of endothermal To illustrate one embodiment of this invention, the following example is included. Such an'example,however, must not be construed as limiting the invention since'other modifications within the scope of this invention will be apparent to those skilled in the art. I

' I Example I A'Texas Panhandle-crude oil was heated in a pipe still to a temperature of 800 F. and allowed .Presto flash in a separator wherein the total vaporizable material was removedfrom the residual oil at an average vapor temperature of 750 P.

.The total vapor thus resulting was passed barrels of liquid oil per hour per ton of catalyst.

The treated vapors were then passed to a fractionating unit for separation of hydrogen sulfide,

.normallygaseous hydrocarbons and straight run gasoline with about 360 F. end point. The remaining desulfurized cracking stock was then charged to a heater where the stream was vaporized and the vapors heated to a temperature of 950 F. The heated vapors were passed then to vaporizable material passes without any substantial cooling to a catalyst chamber H for desulfurization. Thetreated vapors then pass to fractionating unit I! wherein straight run gasoline and gaseous hydrocarbons along with hydrogen sulfide formed in l2 are taken overhead. The. overhead vapors are cooled and fractionated in fractionator l4, from which theC; and lighter a chamber wherein an absorbent mineral ore cracking catalyst was maintained at substantially950 F. and about 30. poundspressure. The vapors from the catalytic cracking unit were then cooled and passed to a fractionator where the gasoline hydrocarbons and lighter gases were taken off along with a small amount of hydrogen sulfide resulting from a further decomposition of organic sulfur compounds by the cracking catalyst.

The unconverted cracking stock remained as a residual oil which was then passed to a second catalytic converter for further cracking. The vapors taken overhead from the primary fractionator were cooled and passed to a second fractionator where gaseous hydrocarbons were separated from the gasoline. The gaseous hydrocarbons separated from the cracked gasoline were passed to an absorption unit wherein hydrogen and lighter gases were separated from C3 and C4 hydrocarbons. Said C3 and C4 hydrocarbons containing a large percentage of unsaturates were then passed to a catalytic polymerization unit, and the efiluent from said unit after fractionation produced an additional amount of gasoline of very high blending octane number.

The following comparative results illustrate the superior results obtained'bythis embodiment of the present invention as compared to the conventional refining of the same crude oil to produce successively straight run cracked and polymer gasoline. from the undesulfurized total fraction vaporizable at 800 F.

Old New process process Total material vaporizable 800 F.:

Sulfur; percent.. 0. 25 0. 064 Reduction .do-. 78. 4

do-.. 88. 5 1.4 0.8 pereent 42.8

ur -do.- 0.12 0.045 Reduction .do. 62. 5 A. S. T. M. octane number 77. 5 78.0 TEL to 80 octane cc.. 0. 7 0. 3 Reduction in TEL ..percent. 67. 0 Operating period of cracking catalyst 1 hours... 12 i8 Blend of straight run, 'cracked and polymer gasoline:

S .peroent 0. 075 0. 024 Octane number. 72. 6 72. 0 TEL to 80 octane... cc. 1. 8 1. 0 Reduction in TEL peroent.- 44. 4

The figure illustrates schematically on'e embodiment of the process comprising the present invention. According to this drawing, the crude petroleum oil is fiash distilled in distillation unit In from which the mixture of vapor and liquid pass to a separator ll. From the separator the hydrocarbons and hydrogen sulfide .are taken overhead and separated from the end-point, low a sulfur straight run gasoline. The overhead gas may then pass to a compressor l5 and a fractionator IS in which hydrogen sulfide is removed by fractionation, along with part of the Ca hydror' carbons. The residual C3 and C4 hydrocarbons from thi operation are useful in the manufacture of gasoline by thermal polymerization. If desired, the C3 hydrocarbons may be largely retained by using chemical means for the removal of hydrogen sulfide prior to the gas fractionation step. The residual desulfurized liquid from I! then passes to a heater 20 and thence to a catalyst chamber 2! for conversion of the heavy hydrocarbons to gasoline. The cracked vapors from 2| .pass to afractionator 22 where gasoline and gaseous hydrocarbons are removed along with any decomposed impurities from unconverted cracking stock. The gasoline and gaseous hydrocarbons are fractionated in unit 28 to separate C4 and lighter hydrocarbons from the cracked gasoline. The gaseous hydrocarbons from 23 then may pass to a hydrogen sulfide removal unit 24, a compressor 25, and

. than to a vapor absorption unit 26, where Ca and Ct hydrocarbons are removed, and sent to a catalytic polymerization unit 21 for conversion of unsaturates to polymer gasoline. The efiluent from 21 is then separated by fractionation in unit 28 to remove the unconverted Cs and C4 hydrocarbons which may then pass to thermal poly feed. The hydrogen and lighter hydrocarbons from 26 may be recycled if desired by alternate arrangement to the stream of cracking stock ahead of heater 20 to act as a diluent and source of endothermal heat to the cracking operation.

While the example and the drawing provide specific illustrations for the process of this invention, other modifications will become apparent in the light of the foregoing disclosure, and limitations are applied only according to the appended claims.

I claim:

1. The process for producing motor fuel from crude petroleum oil which comprises fiash distilling said oil at a temperature between 600 and 800? F., separating the total material vaporizable at said temperature from residual oil, passins said total vaporizable material at vapor temperature without substantial cooling at pressures between atmospheric and pounds per square inch and fiow rates between 1 and 10 liquid volumes of raw stock per hour per volume of catalyst, over a bauxite catalyst whereby a substantial proportion of the organic sulfur impurities is decomposed to hydrogen sulfide, fractionating the desulfurized material to separate normally and 300 pounds per square inch to partially con-' vert said heavy fractions by cracking into gasoline hydrocarbons, fractionating the vapors from the cracking catalyst to remove normallyv gaseous hydrocarbons and hydrocarbon vapors comprising a high octane cracked gasoline from unconverted heavy hydrocarbons, then separating the normally gaseous hydrocarbons by subsequent fractionation from the gasoline hydrocarbons, separating the. gaseous hydrocarbons into a lighter and a heavier fraction, and passing said heavier gaseous fraction containing substantial amounts of olefins over a catalyst for the production of polymer gasoline, fractionating the eilluent from the catalytic polymerization operation to obtain thereby additional high octane gasoline and combining said low sulfur, high leadresponse straight run gasoline with said highoctane cracked and polymer gasoline to obtain superior yield of a valuable motor fuel.

2'. The processfor producing motor fuel from crude petroleum oil which comprises flash distilling said oil at a temperature between 600 and 800 R, separating' the total material vaporlzable at said temperatures from residual oil, passing said total vaporizable'material without substantial cooling over a bauxite catalyst at pressures between atmospheric and 100 pounds per square inch, and flow rates between 1 and liquid volumes of feed stock per hour per volume of catalyst, whereby a substantial proportion of the organic sulfur impurities is decomposed to hydrogen sulfide, fractionating the desulfurized material to separate a straight run gasoline, stabilizing said straight run gasoline to remove normally gaseous hydrocarbons and hydrogen sulfide and produce an end-point gasoline of low sulfur content and high lead response; heating the heavy fraction of said desuifurized material substantially denuded of gasoline and passing same over a'bauxite' catalyst at temperatures between 800 and 1050 F. and pressures be-' tween atmospheric and 300 pounds per square inch to partially convert said heavy fraction by cracking into gasoline hydrocarbons, fractionating the vapors from the cracking catalyst to re- ,move vapors comprising a high octane cracked gasoline from unconverted heavy. hydrocanbons,

condensing and'stabilizing said cracked gasoline and combining same with the low-sulfur straight run gasoline to obtain a superior yield of a low sulfur, high lead response motor fuel.

3. The process for producing motor fuel from crude petroleum oilwhich comprises flash disa substantial proportion of the organic milfur impurities are decomposed into'hydrogen sulfide, fractionating the desulfurized material to segregate an end-point low sulfur straight run gaso-' line free,oi' hydrogen sulfide and a low sulfur cracking stock, heating said cracking stock and subjecting the vapors to cracking conditions to partially convert the heavy hydrocarbons into gasoline hydrocarbons, fractionting the vapors from the cracking operation to obtain a high octane low sulfur cracked gasoline and'b'lending said cracked gasoline with said straight run gasoline to producea superior motor fuel.

hydrogen sulfide, cooling and fractionating the desulfurized material to remove light gases and a straight [run gasoline with an end-point of 300 F., heating the residual fraction of said desulfuriz ed material and passing same over a bauxite catalyst at a temperature between 950 and 1050 F., and pressures between atmospheric and pounds per square inch to partially convert said residual fraction into gasoline, cooling and fractionating the vapors from the cracking catalyst to remove vapors comprising a high octane cracked gasoline and a light gas fraction high in hydrogen from unconverted heavy hydrocarbons, stabilizing said cracked gasoline to remove said light gas fraction, passing said light gas fraction to a vapor recovery system to separate Ca and C4 hydrocarbons from the lighter gases containing principally methane and hydrogen, recycling a portion of the methane-hydrogen mixturewith the cracking stock ahead of the heater to supply endothermal heat to the cracking catalyst, and finally combining said high octane cracked gasoline with said low sulfur straight run gasolineto produce a superior motor fuel i 5. The process for producing motor fuel, from crude petroleum comprising passing the crude oil to a heating zone and thence to a flashing zone to separate the vaporized and unvaporized material, the heat supplied to the heating zone being such that the temperature of the vaporized material is between 600 and 800 F., passing the vaporized material without cooling from the flashing zone into contact with a solid adsorbent bauxite catalyst at a pressure between atmospheric and 100 pounds per square inch and a flow rate between one and ten liquid volumes of feed stock per hour per volume of catalyst whereby a substantial proportion of the organic sulfur impurities are decomposed into hydrogen sulfide to yield a desulfurized stock, removing the hydrogen sulflde from the desulfurized stock, and passing desuliurifled stock in contact with a bauxite catalyst at a temperature between 800 and 1050 F. and a pressure between atmospheric and 300 pounds per square inch to partially convert the desulfurized stock into gasoline qontainlng a minimum of refractory cyclic sulfur compounds.

WALTER. A. SCHULZE.

Images