Патент USA US2398846код для вставки
April 23, 1946. - 2,398,846 J. c. MUNDAY MAKING GASOLINE Filed July 6, 1944 ‘ 3 3.5 Odov2 3, duomi 3. ,0! ‘Juan!‘ ’ om mp. VS.8uobaimw w John C. mundaz/ _ Unverzbcr Q. bb .o ‘n e u‘ r 2,398,846 . Patented Apr. 23. 1946 , :UNlTI'ED STATES PATENT‘ OFFICE . John C. Munday, Cranford, ‘N. J., assignor to Standard Oil Development Company, a corpo ration of Delaware Application July 6, 1944, Serial No. 543,626 5 Claims. The present invention relates to an improved process for the production of gasoline and other light hydrocarbons from heavier hydrocarbon oils (or. 196-52) gasoline so as to renderit more suitable for retreatment in a cracking zone. . A secondary object of my invention is to im prove gasoline fractions and the cycle oil in the The catalytic cracking of hydrocarbon oils, absence of a fraction boiling between the gaso , such as gas oil, to form cracked gasoline has now line and the initial feed stock in order to im: become common practice in the petroleum re?n prove the economics of the overall process, in ing industry, While the raw cracked gasoline particular to effect the saving in hydrogen which has, of course, many advantages over the gaso is one of the materials I employ in my process. line produced by the older thermal cracking 10 A third object of the present invention is to methods, nevertheless it has to‘undergo consid improve the quality of both the gasoline and the erable after-treatment and/or re?ning in order cycle oil recovered from a catalytic cracking op ‘ to produce ?nally a satisfactory commercial. eration in a more expeditious and economical product. In general, there are two main consid than has been possible heretofore. erations presented to the re?nery in after-treat 15' ‘manner Other and further objects of the present in ing or handling the material recovered from a vention will appear from the following more de cracking reactor or zone. In the ?rst place, the tailed description and claims. raw product is not 100. per cent gasoline and con In the accompanying drawing, I have shown tains sustantial quantities of unconverted ‘gas oil diagrammatically merely the essential apparatus or heavier ends which, during cracking, have un '20 of a unit in which a preferred modi?cation of dergone some change which makes them less de my invention may be carried into practical effect, sirable for recracking than the original feed f with only so much of the accessory apparatus as stock. Thus the unconverted gas oil commonly is necessary to aii‘ord a clear understanding of called “cycle oil," since it is returned or recy~ the invention. ' cled in whole or in part to the cracking zone, Referring in detail tolthe drawing, a gas oil,‘ acquires as a result of the operation high mo which may be a West Texas crude oil boiling in lecular-weight aromatics containing two or more the range of from 500° F. to 800° F. and having benzene rings in a condensed nucleus. The pres an A. P. I. gravity of about 30, is introduced into ence of these aromatics is detrimental to the op the system through line I, thence heated in a by‘ catalytic cracking. . . eration of cracking, since they decompose during 30 ?red coil 3, or other suitable means, to a tem the cracking or‘recracking to .form unduly large perature of, say, 900° F., whereupon it is With quantities of so-called coke, a carbonaceous de- , posit which forms on. the catalyst. Consequently, 'it is desirable to treat this cycle oil to improve its qualities before it is again- subjected to cracking. } With‘respect to the gasoline itself, particular ly where the object of the process is to produce aviation gasoline, the same invariably contains substantial quantities of normally liquid ole?nic hydrocarbons which .are undesirable particularly when the gasoline is eventually to be blended .with lead tetraethyl, since such an ole?n-con taining gasoline is less responsive to octane num ' drawn through line 5 and discharged into a crack ing vessel l0 containing a catalyst C. The pres sure employed in_ the cracking operation may be atmospheric or thereabouts, for example in the range 0 to 100 lbs. per square inch gauge. The catalyst may be a natural or acid-treated ben tonitic clay, or a synthetic gel of silica and alu- ‘ mina. In the modi?cation of my invention which I have shown to illustrate my invention, the crack ing is carried out in a stationary bed type of cata~ lyst contained in a cylindrical or other suitable - case l0. Since cokeis formed on the catalyst dur ing cracking, ‘it is generally desirable to provide ber improvement by‘the addition of lead tetra 45 more than one catalyst case so that by proper al ethyl than a, saturated material would be. In other words, such a gasoline fraction is said to have a lower lead susceptibility (a technical term in this particular art) having the signi?cance indicated. - ‘ ' The main object of the present invention is to improve the normally liquid cracked portions of . a cracked gasoline and, at the same time, to im prove the so-called cycle oil or that portion of the original feed stock which is not converted to ternation the oil‘?ow can be made continuous even while coke is being removed by periodic burn ing with air. It should be appreciated that I may carry out my process of cracking in any, of the known methods; such as the so-called ?uid cata lyst type of operation where the catalyst in pow dered condition is passed through a so-called de layed settler type of reaction and regeneration zones, in the form of a ?uidized mass of catalyst admixed with reaction and regeneration vapors, a 2 asoaaec or I may use‘ other known types of operation on a suitable spacing agent or carrier such as ~ where the catalyst in the form of grains, granules? lumps. and the like, moves by gravity or forced circulation through a reaction zone and a regen and the like. Very good catalysts for the purpose crackedproduct rather than in a speci?c type of intended are synthetic chromium-aluminum oxide‘gel containing about 35 per cent chromium oxide, and activated aluminum oxide impregnated‘ with 5-20 per cent of molybdenum oxide, The cracking, it will not be necessary to describe in catalysts may be regenerated by passing, air or detail the cracking process. ‘ air diluted with nitrogen or flue gas over the eration zone. However, since the gist of my in vention resides in thesubsequent treatment of the 7 activated aluminum oxide,'bauxite, silica gel, clay, .\ , ‘ Cracked products from the illustration I have 10 catalyst until‘ the coke content is reduced to the desired extent, taking care that high temperature shown are withdrawn ‘from the reactor through does not deactivate the catalyst. The oxidized a line l2 and immediately discharged into a frac catalyst maybe treated with hydrogen before tional distillation zone M where the crude placing it back on stream, if desired. cracked products are fractionated into the fol lowing fractions: First, there is taken overhead 15 The treated materials are withdrawn from hydrogenator 40 through line 80, thence dis through line It that portion of the total product charged into a hydrogen separator 62 from which the hydrogen may be withdrawn through line 55 and recycled to line 50 for further use in the cooler l6 into separator ll; light gases are re moved overhead from the separator through line 20 process. It may be and often is desirable to pass the hydrogen-containing gas in line 50 through It and liquid hydrocarbons, including C4 and a scrubber where it contacts in countercurrent some C3, are removed through line I9 and may ?ow an absorption oil, such as, say, a light naph be utilized in alkylation and polymerization proc tha which scrubs out and/or dissolves light hy esses. A second fraction comprising the CIR-325° F. hydrocarbons is withdrawn through line 22, 25 drocarbons thereby enriching the ra?inate in hydrogen content. The bottoms withdrawn and acycle oil fraction boiling above about 500° from separator 62 through line 10 carrying a F. or 550° F. is withdrawn through line 24, These pressure reducing valve 13 are then discharged two fractions are combined and it is with, respect which includes the lighter fractions up to the C5 hydr0carbons.- This material is passed through into a fractionator 15 from which the now satu to the re?ning of these particular said fractions that my invention is principally concerned. In 30 rated Cs-325°,F. gasoline fraction is withdrawn through line 80 and delivered to storage drum 8!. treating these fractions, I ?rst pass them by means of a pump (not shown) through line 22 and through a heating means, such as ?red coil 30, and thence through line 32 and then into a . The bottoms from fractionator ‘I5 are withdrawn drogen from some source is passed from line 50 inlet line I for further treatment in the cracker i0. The normally gaseous hydrocarbons and pos through line 83, and this material which is the cycle oil previously mentioned, improved as'to hydrogenation reactor 40. Simultaneously, hy-. 35 its cracking properties, is discharged into feed through a suitable heating means 55, which may . sibly some hydrogen which are contained in the be a?red coil,‘ and thence discharged via line 56 crude product withdrawnv from 40 are withdrawn into line 32 where it admixes with the heated hydrocarbons and is discharged with the latter 40 overhead from fractionator 15 through line 90 and these may be disposed of in any convenient into the'hydrogenation reactor 40. The hydro gen employed is preferably that produced in the cracking step, separated from cracked products in separator i1 and passed through line l8 into line 50. . manner. _ ,Of course, it will be understood that the raw gasoline collected in storage 8| may be corrected as to volatility by the additionof suitable blend ing agents thereto, or bythe removal of light ends In the hydrogenation reactor, the desired re sult is to saturate the ole?ns in the (Is-325° F. and of course may be blended with up to 4 cc. of benzene rings in a condensed nucleus, which are about 500° F. or 550° F., and in a preferred opera lead tetraethyl per gallon of gasoline according fraction of the gasoline withdrawn from fraction _ to standard practice. ating column I4, and at the same time to hydro genate the aromatics, particularly the high mo 50 The cycle oil fraction which is subjected to mild hydrogenation has an initial boiling point above lecular weight aromatics having two or more tion has a boiling range similar‘to that of the contained in the heavy bottoms withdrawn from fresh feedstock. If the aviation gasoline fraction, fractionating column 14 through line 24. To ac complish this end, I maintain the following con 55 which is hydrogenated along with the cycle oil, boils up to 325° F. as mentioned above, it will ' ditions in hydrogenator 40: Temperature ____________ __. 600° F. to 800° F. Pressure___-_-____-_.._____. 200 lbs. to 3000 lbs. . - per sq. in. gauge Oil feed rate _____________ _. 1 to 5 v./v./hr. Hydrogen, cu. ft. per barrel feed _________ _. 1000 to 6000 Under the conditions I have set forth in the preceding table, I accomplish the saturation of the ole?ns and at the sametime convert a sub stantial part of the heavy aromatics in the cycle stock by hydrogenation into naphthenes which contain the Ca aromatics, the xylenes and ethyl ‘benzene. In some cases, for example when the capacity of the hydrogenation unit or the amount 60 of hydrogen available is limited, it may be desir able to bypass the C8 aromatic fraction boiling between 265° F. and 325". F. around the hydro genation step, by passing it from fractionator I4 ‘ through line 82 to line 80 and thence to storage If the toluene concentration is high, 65 drum 8|. it may be desirable to bypass the 221° F.-325° F. fraction through line 82. An intermediate fraction boiling between the cycle oil and the aviation gasoline, in example are more suitable as a catalytic cracking stock than the said aromatics for the reasons herein 70 between 325° F. and 550° F., is withdrawn from fractionator l4 and is rejected from the system, before stated’. As to the catalyst, I prefer to use whereas by mild hydrogenation the aviation gas a regenerable catalyst. Included in such a group oline is improved in quality and the cycle oil is , are group VI and VIII metals and metallic oxides, made more amenable toward cracking to high such as nickel or molybdenum oxide or chromium oxide. The catalyst is‘ also preferably supported 75 quality gasoline. Hydrogenation of the interme 9,898,846 3 diate fraction is imdesirable since its quality as a - oil feed, while increasing coke formation from 4.2 motor fuel is degraded by hydrogenation, and its . to only 5.0 weight per cent based on feed. . . value as a cracking stock even after hydrogenation Numerous modifications of my invention fail is far less than that of cycle oil or fresh feed. Re ' ing within'the scope thereof may be made by jection of the intermediate fraction therefore has the eii‘ect of increasing the overall quality of the aviation gasoline produced and of plant capacity, 'those familiar with this art. and also of keeping hydrogen consumption in line with hydrogen production in the cracking step. Hydrogen consumption may also be decreased by bypassing the Ca fraction of the cracked prod ucts around the hydrogenation zone, by passing it from fractionator ll through lines 84 and 80 catalytically cracked gas oil. the improvement which comprises withdrawing ‘the products from a catalytic cracking zone, fractionally distilling the ‘same into ‘a fraction consisting of- C5 hydro into storage drum 8 I . ' What I claim is: ' 4 1. In the re?ning of the total products of a I carbons to those boiling up to about 325° F. and a second fraction comprising the hydrocarbons 1 boiling above about 500° R, combining the segre For example, a Southwest Louisiana wide-cut 15 gated fractions, subjecting the, combined frac gas oil having an A. P. I. gravity of 32°, an aniline tions to a mild catalytic hydrogenation in the point of 1'75, and a boiling range correspondingto presence of added hydrogen wherein the oleiins 5 per cent at 484°, 50 per cent at 622°, and an end are saturated and‘the aromatics in the fraction point of 700° F’. is cracked at 975° F. employing a boiling above about 500° F.‘ are substantially con powdered silica-alumina catalyst in 13:1 catalyst 20 verted to naphthenes, in a hydrogenation zone, to oil weight ratio and a weight-space velocity of withdrawing the hydrogenated products from the ,. 4. On a volume per cent fresh feed basis, there hydrogenation zone, fractionally distilling the hy are obtained 28 per cent aviation gasoline of 7 drogenated products to recover ‘a saturated avia lbs. vapor pressure which has an acid heat of tion gasoline boiling up to 325° F., separately r'e a 141° E, a bromine number of 74, and ‘a boiling 25 coveringa fraction boiling above 500° F., and re range of 110° F. to 332° F., and 26 per cent cycle cycling'the last-named fraction to the cracking oil boiling above 500° F. The intermediate frac tion which has a low octane number (65-70 C. F. ‘ 2. The method of claim 1 in which the hydro R. Motor method) is rejected from the process. genation is carried out in the presence of a re The aviation gasoline is fractionated into a 30 generable catalyst. , ‘ light fraction and a heavier fraction boiling above 3. In the production of high quality aviation 221° F. which contains xylenes and a small gasoline,the steps of catalytically cracking a gas amount of toluene. The heavier fraction is by oil, in a cracking zone, withdrawing the cracked passed around the hydrogenation step. The light products and fractionally distilling the same into ' aviation fraction-and the cycle oil fraction are 35 non-aromatic and aromatic fractions boiling in , combined and are hydrogenated at 730° F., 3000 the aviation gasoline range, and a heavy cycle oil zone. ' ‘lbs. per square inch pressure, 6000 cubic feet of ' hydrogen per barrel, and 1.0 v/v./hr. space velocity, employing tungsten sul?de catalyst. The hydrogenation product is fractionated, the light fraction is combined with the bypassed aro matic fraction, and the heavier hydrogenated fraction is recycled to the cracking step. The combined fractions comprise an aviation gasoline - having an aviation octane number of 96.5 by the AFB-1C method as compared to 92 for the orig inal cracked aviation gasoline, each being tested at '7 lbs. vapor pressure with 4 cc. lead tetraethyl per gallon. > _ - fraction, combining the non-aromatic aviation gasoline fraction with the said heavy cycle oil fraction, subjecting the mixture to a mild cata . lytic hydrogenation, separating the hydrogenated products into an aviation gasoline fraction and a cycle oil fraction, combining the hydrogenated aviation gasoline fraction with said aromatic fraction to form ‘aviation gasoline, and recycling the hydrogenated cycle oil to the catalytic crack ing zone. ‘ ~ _ ‘I 4. The method of claim 3 in which the hydro genation catalyst is of the regenerable type. t ‘ 5. The method of claim 3 in which the heavy, Recycle of the heavy hydrogenated cycle oil to 50 recycle oil boils above about 500° F. ‘ the cracking stepincreases the yield of aviation gasoline from 28 to 37.3 per cent based on gas ’ ‘ Joan c. MUNDAY.