US2744053A

US2744053A - Hydrocarbon conversion process, including preliminary nitrogen removal by adsorption

Info

Publication number: US2744053A
Application number: US223062A
Authority: US
Inventors: Nicholas L Kay; Grant W Hendricks; Ross A Hanson
Original assignee: Union Oil Company of California
Current assignee: Union Oil Company of California
Priority date: 1951-04-26
Filing date: 1951-04-26
Publication date: 1956-05-01
Anticipated expiration: 1973-05-01

Description

May 1, 1956 N. L. KAY ETAL 1 2,744,053

HYDROCARBON CONVERSION PROCESS, INCLUDING PRELIMINARY NITROGEN REMOVAL BY ADSORPTION 2 Sheets-Sheet 1 Filed April 26, 4.95]

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fizairaa x/meahw arr aw Can 744mm G 5 May 1, 1956 N. L. KAY ETAL HYDROCARBON CONVERSION PROCESS, INCLUDING PRELIMINARY NITROGEN REMOVAL BY ABSORPTION Filed April 26, 1.95] r LI" 0 y %y 0 6% I. w mfl M 0 734 WW 1% 07A W 2 aim area mama 64s United States Patent v *HYDR'OCARBON CONVERSION 1i PROCESS, IN- CLUDING 1 PRELIMINARY :NIT ROGEN :RE-

MOVAL :BY..=ADSQRB']3ION Nicholas L..Kay, .Inglewoo'gl, AGrantYWJHendricks, Bren, and Ross Hanson, iFullerton, Calif., assignors to Union OilCompanyrof California,"-Los'Angeles,--Galif., a corporation of-(lalifornia ---App fit qment .-6,.- ,l;; r a 22 6 6 Claims. (Cl. 196- 28) This process, relates. generally ,toimethods forthe conversion of hydrocarbons. Moregparticula'rly, .thisinven- .tion relates to a. process 'I'for. .the. removal, of..i1itrogen in ,a preliminary .soprtion zone and ,.a subsequent catalytic treating in .a ,conversion.v zone wherein .the efiiciency in the conversionzone.isdmproved as aresultof thenitrogen removal.

. Thepresence .of.nitrogen in. refined hydrocarbon prod- .ucts .is extremely;objectionable. ,These conipounds impart .undesirableodorsto thesproducts, contribute .to increased .formation andn'lacksof .storage stability .in

thecase..of gasoline. ,In...the..case .ofhydrocarbon feed .stocksior..catalytic,;.processes such .as. cracking, .hydrocracking, :isomerization,.desmfurization, hydrogenation, vcIayJreatingand.thelike,,the presence. of nitrogen almost invariably. contrjbutesqto increased. rates of .catalyst foulingat ..a given...conversion .level,,decreased activity, and

to the formation of less desirablezproducts.

. Furthcrmotc,.-.the.dearth Qf thigh; race refining crudes has necessitated. the industrialusezo rginahpetroleum stocks .whichcontain; langeramo ll nts -of .combined nitro- -gen -.than. previously employed stocks. .Educted .shale oils, tan sands.-;oils.:.andthe-l ke'contain stilLhjgher guan- -tities-of-=.- nitrogen, which oils zmust be reckonedwith in future. refining processes.

-. It. has nowebeen foundithat nitrogen-containing compounds oftthe relat-ivelyglower boilinghydrooarbonstocks such as: those-boiling;belowEr800;.'F., arequitemreadily retained'zr-byshighz surface, area catalysts. such ,as, are,-.'e mployed in catalyticucracking processesfor example. ."It'. '.is;- therefore antiqbjectrof athis. inventiomto provide armethod for the removiakof nitrogenxfrom lower .boiling hydrocarbonz-stocksnby sorptione; oniarhigh surface, area catalyst.

- It-isvanother fobject oftthisainvention :to :treat cracking stocks. in: :two zonesawhereinlthe: feedstock is" first contacted in a relatively cold sorption zone to causesorption of nitrogen compounds selectively:on the *catalyst and --wherein the-=nitrogen-depleted-teed smears then processed in arelatively hot conversion zone to cause catalytic cracking of the feedstock.

"*It is another object 'of this invention to treat gasoline stocks -in a-relatively cold sorptiony-zoneto sorb the. nitrogen compounds selectively in' the vapor phase and to I treat the nitrogen-depleted gasoline stock' in a second'catalytic treating conversion zone wherein the 'ificiency in the see- I ond-zone is improved-as a resultof -the nitrogen depletion.

"It is another object- 'ofit his invent-ion to process hydrocarbon stocksboiling below about 800Fhin a nitrogen removal -'zoneand to treatthereafter in a catalytic reaction zone.

Itis another object of 'this invention toimprove :catalyticprocessing operations-by subjecting the feed stocks to a-preliminary nitrogenremoval.

It is another object .of'this'invention to produce low nitrogen gasoline-and in greater quantities'by the cracking --or hydrocrackinguof a relativelyr nitrogen-free feed stock which boil generally in theraugeup tofaboutfi H less. In the method the nitrogen-containing? eledistqck is first subjected to a preliminary sorp't'ion step naf soi-P- lCc wherein the nitrogen has been depleted. ;s orption' on aportion of the catalyst.

Other, objects and advantages of this invention will become apparent to those skilled in' scription thereof proceeds.

Briefly this inventionrelates to anewgme'thod'fprgthe catalytic processing. of hydrocarbon,stocks'yyliich contain appreciable quantitiesofnitrpgen ,ce qnndsann tion zone at a relatively low temperature such h temperature -frorn l0 to 200 'F.' above 'the 9%- ing point of the stock. The non-sorbed portijonofe e stock generally contains lssthan about 2'5%. o the original nitrogen compounds'and often contains I as 10% or less of such compounds. 'Ihe (gendepleted feed stock obtained thereby has been' fou'nd to be generally superior for subsequent catalytic processing in a conversion zone by virtue of the decreased nitrogen content and possibly due to .other factors such as l'omdlil dl of polymers and other gum s, removal of,peroxides;and miscellaneous other catalyst poi s oning andioul ijng ma terials. Thus the nitrogen d e'plete'd s tock give inc reased gasoline yields .on catalytic cragcking and, also yields I a gasoline of superiorlqualityf Furthermo'rmthe catalytic cracking of a low nitregenstock lays down less carb at a given conversion level, gives a'h igher yield of gasol 'e per unit of feed stock converted, and gives a hijg er- W t line to coke ratio which is generally'also desirable.

In the treatment of gasoline, stpcks for the improvement of octane rating, storage stability;desulfurization and the like, past experience has shown that high temperatures such as in the range of 800 to O F. are' par,ticularly desirable for improving these and other characteristics of the gasoline. nhasno been -found that s1ich eral upgrading of the stock isbest-accomplished by 'a preliminary low temperature nitrogen removal step which is followed bya high temperature catalytictreating step. Because of the reversibility 'of the sorption step, =it =is generally desirable that nitrogen-contaminated catalyst be excluded from the high temperature catalytic-treating step. It has been found.that a partially,.c'arboned catalyst from the high temperature catalytic cracking step is active to some extent for theremoval of nitrogen in a lowtemperature sorption step;.and n1ay -in fa'ctrlbe employed for such processes.

Figure 1 shows one modification of the-inventiohgwherein a hot catalyst stream isindirectly exchangediwith the cooler feed stock to produce. a-relatively. cold :catalyst stream and wherein the heated feed*stockniszthen passed through a cold catalyst contacting sorptiomzoneforsrthe removal of nitrogen and thence'throughj a: higher temperature catalytic conversion zone and,.wherein-athefeed stock flows countercurrent-to the catalyst-throughout.

Figure 2 shows anothermodification-of: the;invention wherein the circulating catalyst stream .is split -andi the relatively cold feed stock is contactedqdirectlywith one portion of, thehot catalyst so as to ,cool thecatalysttq the pounds of the relatively heavier metals.

desired sorption temperature for the sorption zone and remove the nitrogen compounds from the vaporized feed stock and wherein the vapors from the sorption zone are then contacted with the second portion of hot catalyst to effect catalytic conversion in the conversion zone.

The hydrocarbon stocks which may be treated by the process of this invention comprise petroleoum distillates, shale oil distillates, hydrogenated coal fractions, tar sand distillates and the like, which boil generally in the range below about 800 F. and which preferably boil below about 700 F. Thus gasolines which boil generally in the range of about 100 to 400 F. and catalytic cracking charge stocks which boil generally in the range of 400 to 700 F. may be processed according to the method of this invention.

In general the nitrogen content of most gasoline stocks is considerably less than that of the corresponding catalytic cracking stocks. Thus gasolines containing between about 0.01% and 0.5% nitrogen by weight or more may be processed and gas oils containing between about 0.1% and 5.0% nitrogen by weight may also be processed.

Catalysts which may be employed for both sorption and catalytic conversion in the method of this invention include the adsorptive oxides such as silica, alumina, zirconia, thoria, magnesia, magnesium hydroxide and the like, or combinations of these oxides either with or without additional metal oxides, sulfides, and like com- It has been found generally that the use of heavier metal oxides and sulfides contributes little to increased sorption if nitrogen compounds and these compounds are not normally employed when they are not necessary in the catalytic treating step.

Catalytic agents which may be employed in the catalysts of this invention, include the oxides, sulfides, or other compounds of heavier metals such as chromium, molybdenum, cobalt, nickel, zinc, iron, lead, beryllium, cadmium, vanadium, manganese, tantalum, tungsten, titanium, platinum, columbium, scandium, thorium, aluminum, uranium, zirconium, tin, copper, etc., or combinations of two or more of such compounds.

Of these catalytic agents those which appear to be most effective and consequently find the greatest usage are the compounds of the heavy metals of atomic No. 22 to 42 including titanium, vanadium, chromium, manganese, iron, cobal, nickel, copper, zinc, yttrium, zirconium, columbium and molybdenum. The oxides of molybdenum, and of cobalt in the presence of molybdenum, have been found to be the preferred catalytic agents for the hydrocracking process of this invention.

The preferred catalyst for the sorption of nitrogen compounds is adsorptive silica and silica containing minor proportions of other oxides such as alumina, magnesia,

and the like. Such silicas may be prepared synthetically by precipitation or co-precipitation or they may be prepared by acid treating or other treatment of naturally occurring clays. Commercially available cracking catalysts are predominantly silica in composition and may be employed for nitrogen sorption. A particularly desirable commercially available cracking clay is acidtreated montmorillonite clay and this has been found to be highly suited to nitrogen removal.

The nitrogen sorption step is generally carried out at pressures near atmospheric and at temperatures relatively close to the boiling range of the stock being treated. In certain cases however the gas oil may be treated at slightly elevated pressures and the gasoline may be treated at pressures up to 100 p. s. i., for example.

The liquid hourly space velocity through the sorption zone will generally be in the range of about 0.2 to volumes of liquid feed per volume of catalyst per hour. The ratio by weight of catalyst to oil depends upon the nitrogen content of the oil and the tempera ure of tion and is generally in the range of about 0.1 to 20 and preferably in the range of about 0.5 to 10.

The catalytic treating zone following the nitrogen removal zone is generally conducted in a conventional range of operating conditions. Thus in the case of crack ing, the temperature is generally in the range of about 800 to i000 F. and at pressures between about atmos' pheric and 100 p. s. i., and the space velocity is generally in the range of about 0.2 to 10 volumes of liquid feedi per volume of catalyst per hour.

In the case of gasoline treating the temperature is: generally in the range of about 750 to 1000 and at. pressures between about atmospheric and 250 p. s. i.- The liquid hourly space velocity is generally in the range: of about 0.2 and 20 volumes of liquid feed per volume of catalyst per hour.

Perhaps this invention can best be understood by reference to the drawings.

Referring now more particularly to Figure 1 feed stock is introduced through line 11 and flows through heat exchanger 12 wherein it is partially heated and/ or vaporized whence it flows through line 13 to heat exchanger 14 wherein it is exchanged with a hot catalyst stream described hereinafter. In the modification shown, the feed stock enters heat exchanger 14 and passes through the shell against the tubes carrying hot catalyst wherein the vaporization of the feed stock and the heating thereof is completed. Vaporized feed stock discharges from heat exchanger 14 through line 15 and is introduced into catalytic reactor 16 through feed stock engaging zone 17.. Feed stock engaging zone 17 comprises a transverse plate mounted within the tubular shell of reactor 16 and the plate is fitted with a series of downcomers 18 which: permit the flow of catalyst downwardly therethrough and the fiow of vapors upwardly therethrough. The extension of downcomers 18 below the transverse plate 19* provide a vapor space immediately below the plate whichmakes up feed engaging zone 17. The vaporized feed stock passes upwardly through the downcomers and enters sorption zone 20 which is filled with downwardly moving catalyst at a temperature which is preferably somewhat above the boiling range of the feed stock. In sorption zone 20 the vaporized feed stock contacts descending catalysts and the catalyst selectively sorbs the nitrogen compounds from the vaporized feed stock. The non-sorbed feed stock which generally makes up about or more of the original volume of feed stock then passes upwardly through a catalyst distributing zone 21 which is formed by a transverse plate 22 and a series of downcomers 23 which are similar to the previously described feed engaging zone 17. The non-sorbed vapors pass upwardly through downcomers 23 into catalytic treating zone or conversion zone 24 which is filled with hot descending catalyst at the desired conversion temperature.

Generally the temperature of catalytic treating zone 24 is maintained F. or more above the temperature of sorption zone 20. This temperature differential is maintained by passing cooled catalyst from previously described exchanger 14 downwardly through line 25 into catalyst mixing zone 21. In mixing zone 21 hot carboned catalyst from catalytic treating zone 24 is mixed with cooled catalyst from exchanger 14 to form a cool catalyst mixture of the desired sorption temperature. It will be apparent also that the total catalyst flow rate through zone 20 will necessarily be substantially greater than through zone 24. This provides a higher effective cata lyst/oil ratio in sorption zone 20 than in conversion zone 24.

In catalytic conversion zone 24 the nitrogen-depleted feed stock is caused to undergo desulfurization, octane rating improvement, storage stability improvement, catalytic cracking, hydrocracking, hydrogenation or the like. The converted hydrocarbons from catalytic treating zone 24 pass upwardly to product disengaging zone 26 and are withdrawn therefront' through line 27. Products in line 27 pass\ through -interchanger-- 28 wand slime/n29 to .7 product storage not shown or fractionation. v- :HOtregeneratedcatalystinseparating VesselQS-is-Withdrawn through line :36 and; is split a to flowathrolugh either valve 37 or valve 38. Valve#38Acontrols..the flowof hot regenerated catalyst through catalyst interchanger 14 wherein the catalyst is cooled to thedesired temperature t'or admission-tothesorption zone. I The "hot regenerated catalyst flow-ing- -throughyalve 37 passes through line 40 at-the'top of reactor 16 and passes into-catalytictreating zone24. The-descending catalyst -'eontacts ascending" hydrocarbon "vapors and efiects the catalytic" conversion thereof. Hot -carbott'ed catalyst :fiom-catalytic-- treating zone -24 descends through cata- -lyst--mixingzone-2I--whereinit is' mix'ed--with colder -.-iireshlynregeneratedcatalystwfron'r exchanger; 14 fiowing throu-ght-line r25. a Ihesmixing ofuthefcolder catalyst and mthe hot carbone'cltcatalyst; produces a/catalystamixturehav- ,.,"Zlhe=co0led ;carboned catalyst isagenerally :about 5 0%--as waict-ivertas tresh uncarboned :catalys-b '-for 1 the sorption of nitrogenceompounds, is ca two volumes Qfi-carbQnedcatalyst are as active as one volume of fresh catalyst.

In 'sorpti'on zone '20'the" mixture of 'carboned and uncarbonedwatalyst icontaining; varying 'ambu'nt's of' nitrogen 'f'compounds in asbrbed' st-ateflows'downwardly and-suc- "'cessively'"'-throu'ghnitrogen-oil disengaging-zone stripoipil g'cstoamtaudAon-sealing steam engagingwzone 46', re-

ing regeneration gas engagin-gszonea ltib lheteatalyst-containing sorbed nitrogen compounds after passing through nitrogen-oilidisengaging zone 45 passes through nitrogeni'ioil stripping" Zone 49. Inmnmgenioitstripping 20116549 ststeam gadmittedthroughfi steam engaging zone tfipasses upwarldlyathroughqtheldesceitding c alyst-and-ldesorbsithe sorbed nitrogen compounds. l mixt-ure d steam-and -nitro'gen-eontainingoil---iswithdrawnrem nitrogen -disengagingtzoneptfitand rflowssthrough .line 5040. cooler 51 and --.s,eparator.-.52. The;-less tden se= oilphaselinfsepa- ;.-,rator-.,52.isremovedoverhead line-53 whence it passes ,to-nitrogen-oilfcontaining storage-triottshownn Condensed isf d-isoharged -frorni the bottom of separator--52. QHeatingtcoils, tnott shown may. be. employed r-instripping ozone 49in placeothsteamjnjection orconcurrentlythere- ;.withtoeausedesorption. p I

The steam-stripped catalystdrom. strippingfzone 49 :1 contains... small -amounts of ,residual. nitrogen compounds l aludf partlylcarbonedcatalyst' Thisunixture passes through sealing zone 54 and regeneration.jgas idisengaging,zone 47 into regeneration zone 55. In regeneration zone 55 oxygen-containing gas introducedain regeneration gas engaging zone 48 passes upwardly through the descending k:atalysta ndtcombust's res-iduat-sonien:nitrogenaempeunds nd misdettaneous carbon; sultuprand nitrogen d'eposits. eifiases fIOIl I- '1i6g@llratlDn zonetSS are withdrawnt from reigenerat-ion gasr' dise'rnga ging zone. :47' ithrough discharge 'el inei56. v

A smaJlnarnount' oftsteam. int*strippingastamaengsiging o'zoneh46it is; permitted to flowedownwardly throngh fsealing zone 54 to prevent upflow of regeneration gas 'whi'ch otherwise would contaminate the upper zones. Hotlregenerated catalyst from regeneration gas engaging zone "48 passes dowhwardlythrough'line whencelit-rpasses into the catalyst conveyance zone. indicatedygenerally 'i-tiby 61. I

ln the particularcatalyst conveyance-shown-liftinggas such i as fluef gas,jsteam,--riitrogen 'or=the' lil-:e is introduced .Hintobl0wert62 through. line 63 whence it passes through va1 ye 64 andenters lifting zone 65. Upwardly moving -I iftingfzone"65 'ntrains catalyse-mu in downv riflineifitl i andj-transpo'rts it "upwardlf-through 'v' ance Zone "61intothe sep-arationtzoner 66 within er'ioib f've'ssel 35. In separation 'zone 66the :ifela- V y{l airge tl'aineterofj the ve'ssel."coniparedi to the diameternt conveyance z'on sl causes 'the"ca't'alyst to set- '10 to-causehydrogenation of the sorbed-nitmgencotnpo'unds from the catalyst.

*R'efe'rring again G FI gUIC I. 1;: hydrog'en'-= is introduced r -th rough IlineflSa andthence' into line- 1 5 when'c '-'with 'thefifeed:=to feed tengaging iz'one 17 whence'rt 15 i up'wardly =':througtr the sorption zone 20= and asatalyuc treating zone 24. Alternatively, or concurrently, the hydrogen passes throughwalve fib into ilinflSc Whence 'it -flows throughtstrippingt zone 49 'wherein: it induces' hy- 'dmgenation of the sorbed nitrogen compounds :to form ingrthe desired sorptiontemperature'in'sorptionl-zone,20. 20E lownboiling nitrogen compounds.and hydrooarbons which are withdrawn through line 50.

-Referring now more particularly to Figure 2 -feedstock :is introduced: through line whence it 'fiows ithrough exchanger 81* wherein it I is' heated and -partial'ly' or com- -25 1rpletelyyaporized whence it passes into feedstock-engaging zone '82-":which is :the "vapor; space existing at 'the :top of reactor- 83.- Inzfeedstocktengaging zone82 zthe-zteed -stock-=- is passed xinto contact with: hott catalyst either :by spraying,-. passing the :vapors into contact therewith or. the

nzg fil' iipni g fillg o and! sy 30 like. The hot catalyst completesxtheivaporization' of the -feedstock:and ma intains theatemperature oi? sorption 'zone -84-at a suitable sorptiontemperature:which is somewhat v above the boiling range ofthe feed-stock. lntsorpt-ion H zone 84 -the nitrogentcompounds ofithe feed stocknaretsez -lectively. sorbed on thecatalystand the non-sorbed vapors fiow concurrently" downwardly with ,-the-cata1yst.

- At the bottom -of sorption -zone84.-the-cata1ystcon- -taini-ngfsorbed nitrogen compoundsds withdrawn lthrough line 85 whence it passes through nitrogenz-oil disengag- Q ing zone 86, strippingzone 87 andsteamtengagingzone 88. Steamis introduced through line 89. into steamen-- t gaging zone 88 and passes upwardlythrough descending catalyst containing sorbed: nitrogen compounds in stripping zone- 87 wherein the nitrogenacornpou nds are .partly m completely removed.=from..the catalystaby stripping. "The stripping steam and-nitrogen oil is .removedirom nitrogen oil disengaging-zone .86 and, passes through-"line 90- to cooler Q91 and thence to separator .92. In separator 92 the condensed lighter oil kphase iswithdrawn from/the .tube through-line 93.and passed ..to nitrogen-rich oil storage. "Condensed steam is withdrawn from the bottom "tofvs'eparator'92 throughline 94.

Vapors from sorption zone 84 pass through vapor'f'disengaging zone which permitstthe downflow of vapors but prevents" the downflowof-c3talyst therethrough. In one modification such disengaging zone-consists of a transverse plate' 101 with aseries ofupwardly projecting tubes which are partially-capped atw the top. Such tubes permit gases to flow downwardly around the cap and '60? thence downwardly through the tubes While preventing a similar flow of catalyst. Vapors frorn disengaging zone 100-.pass into vapor, en-

,, gaging zone 102a'i1d thence into catalyticv treating" zone 7 103. fC'atalytic treating 10 16103 is supplied. with .hot 5 fresh catalyst through line-135 which. heats the vapors to the desired catalytic treating temperature andmaintains catalytic treating zone'103 at the desired reaction temperature.

In'catalytic treating zone 103 conversions such as de- "'70 1 'sulfu'rization,' catalytic cracking, clay treating and the like'are' effected. 'Carboned'eatalys't from'catalytic treating zone .103 and converted hydrocarbon vapors' flow downwardly through'product disengaging 201161 05. vIn 'pro'du'ctdiseng'a'ging zone 105 the converted hydrocarbon 75 vapors are removed from the carboned catalyst a'n'd pa'ss through line 106 to cooler 107, separator 108, whence the product is withdrawn through line 109 and passes to product storage not shown. Carboned catalyst from product disengaging zone 105 passes downwardly through stripping zone 110 and stripping steam engaging zone 111. Stripping steam introduced into stripping steam engaging zone through line 112 passes upwardly through stripping zone 110 and strips residual hydrocarbons from the carboned catalyst and is removed therewith from product disengaging zone 105. Stripped carboned catalyst from steam engaging zone 111 passes downwardly through pressuring means 113 which is a star feeder or other suitable device for conveying solids from a low pressure area to a higher pressure area. Solids discharged from star feeder 113 pass to regeneration zone 114.

Catalyst which has been stripped of sorbed nitrogen compounds and which flows downwardly through steam engaging zone 88 passes through a similar pressuring zone 115 whence it flows through line 116 to regeneration zone 114.

Oxygen containing gas for regeneration flowing through line 117 passes into regeneration gas engaging zone 113 and flows upwardly through regeneration zone 114 wherein it oxidizes carbonaceous deposits on the catalyst and also oxidizes any residual sorbed nitrogen compounds thereon. Spent regeneration gases are collected at the top of the regeneration zone in regeneration gas disengaging zone 119 and are discharged through line 120.

In the method of catalyst conveyance shown in Figure 2 a lift line of the so-called mass flow type is employed. In this particular modification regenerated catalyst from regeneration gas engaging zone 118 passes through line 125 to vessel 126. Steam, flue gas, nitrogen or other lifting gas is introduced into the upper part of vessel 126 through line 127 and exerts a downward pressure on the solids causing them to rise within tube 128 which forms the conveyance line. Conveyance line 128 terminates in a relatively wider diameter vessel 130 and a plate 131 is positioned somewhat above the open upper end of conveyance line 128 and impedes the flow of solids, thereby exerting a back pressure on the solids discharging from line 128. In vessel 130 the lifting gas is disengaged from the catalyst and is withdrawn through line 132 while the separated solids collect in the bottom of vessel 130 and are withdrawn through line 133.

The catalyst flow in line 133 splits with part passing into line 134 and the remainder passing into line 135. Catalyst in line 134 passes into sorption zone 84 wherein a part of the heat content of the catalyst is employed in vaporizing the colder feed stock. The portion of the catalyst flowing through line 135 passes to catalytic treating zone 103.

It is apparent that the regeneration in this type of apparatus is conducted at a higher pressure than is the sorption and catalytic treating. This differential is created by

star feeders

113 and 115 and permits the use of a mass flow-type lift line for conveying the solids. Thus the pressure differential across conveyance line 123 is made possible by the transfer of solids from relatively low pressure zones into high pressure zones. The use of the mass flow lift line in this particular case has the particular advantage in that it permits the regeneration in regeneration zone 114 to be carried out under pressure so as to permit greater rates to regeneration and heat removal of the regenerating catalyst. Furthermore the use of low pressure in the sorption zone permits the use of lower temperatures therein with an improvement in the removal of nitrogen compounds. Thus it is seen that the use of a mass flow lift line offers numerous advantages in the particular process.

Perhaps the process and advantages of this invention can best be understood by reference to the following examples:

8 EXAMPLE 1 One series of experiments was carried out in order to show the adverse effects of nitrogen compounds on catalytic cracking. In the particular series of experiments an East Texas gas oil having the following characteristics was selected for experimentation:

East Texas gas oil- A portion of the foregoing gas oil was blended with quinaldine in an amount suflicient to form a gas oil containing 0.27% nitrogen by weight. Quinaldine has been found to occur in California straight run kerosene (Bailey et al. IACS 52 1239-50 (1950)). The original nitrogenfree gas oil and nitrogen-rich blend were then tested for catalytic cracking under the following conditions:

Temperature, F 850 Pressure, p. s. i. a 15 Liquid hourly space velocity, by volume 3.0 Catalyst to oil ratio by wt 1.5

The following data compare the results of the catalytic cracking and the distribution of nitrogen between the products for the two cracking runs:

Nitrogen Content of Feed Stock, Wt. Percent 0.02 0.27 Product Gasoline, Vol. Percent of Feed 27. 10. 9 Product Gasoline, Nitrogen Content Wt. Percent"-.- 0. 001 0.144 Product Gasoline, Octane Rating (F-2) 76 71 Gas Oil Residue, Nitrogen Content, Wt. Percent 0.003 0. 221 Conversion, Vol. Percent 01 Feed 36.9 16.0

The foregoing data show the deleterious effect of the addition of quinaldine in a number of different ways. The volumetric yield of gasoline per pass is decreased from 27.2 to only 10.9 volume per cent while the gasoline which is obtained has a prohibitively high nitrogen content and is of lower octane rating than is obtained in the absence of nitrogen compounds. Thus it is clear that it is highly desirable to remove nitrogen compounds prior to catalytic cracking of gas oils.

Similar results are obtained where a gas oil is subjected to hydrocracking and the deleterious effects are of somewhat similar magnitude.

EXAMPLE II In another series of experiments the gas oil described in Example I after blending with quinaldine to form a gas oil containing 0.27% nitrogen was subjected to catalytic cracking at a series of temperatures of 750 F. and 950' F. The following results were obtained wherein the reaction conditions were the same as those described in ExamplseoI with the exception that the catalyst to oil ratio was the hydrocarbons is reduced only slightly at higher temperatures and that by operation at lower temperatures such as 750 F. and particularly at higher catalyst to oil ratios as much as of the nitrogen is removed. Other work shows that when the sorption temperature is lowered ominous 9 tastillimorea thatts'till .largeruamountssofum n gt 95- ;s98% maybe-sorbed on thecatalyst. I 1

Initial 462 628.

Maxim m 1725 *"i ln the sorption -step-this-gaseoil was passed over 'a commercial eracking-catalyst ofi "the aeid treatedj-montmorilwltanitetypeat a-eatalyst-to-oihmti$of5 .0 an =a t a' temsmo perature tot 750 F. I-Jnder these"-cciflditions'- 82 "77 *l the nitrogenin-the-feed-stocle-wasretained bywandronly' 7t3%-rem-ained-bathe-unconverted g g ibwhich amounted to -46.5- volume per cent 'of the orijg'inalieharge It is apparent that the nitrogen compounds of actual catalytic cracking stocks are retained in good yield by low temperature sorption.

EXAMPLE IV 9 In another series of experiments a gasoline boiling range 0 stock obtained by catalytic cracking of high nitrogen,

high sulfur gas oils was obtained which had the following characteristics:

The gasoline was passed over a catalyst which had been partially deactivated by commercial usage in a commercial TCC cracking unit so that its activity was 28 compared to a fresh activity of about 39. The following test conditions were employed:

Pressure, p. s. i. a 15 Liquid hourly space velocity 0.5 Catalyst to oil ratio 1.0

The products obtained thereby were fractionated to obtain a C5-330 F. cut and a 330 to 400 F. cut. The corresponding fractions from the untreated feed contained 0.019% nitrogen, 0.25% sulfur and 0.088% nitrogen and 0.37% sulfur by weight respectively. The following data were obtained for the sulfur and nitrogen contents of the series of runs:

Nitrogen content Reaction Temperature, F 600 850 Orr-330 F. out 0.00 0.016 330-400 F. cut 0.029 0.060

Sulfur content Reaction Temperature, F 600 850 C's-330 F. but 0. 28 0.24 330-400 F. cut 0.32 0.26

It is apparent from the foregoing data that high temperatures favor sulfur removal while low temperatures favor nitrogen removal. Other data show that the use of temperatures below 600 F. results in still further imtprovedinitrogeniremovalitIt.istalso apparenmhalz thersulremoval -at the? 600? vtiallyi nil. .Octanezrating s improved- 'at the't8 50 Fareac- --1tiontemperature, r as is: the removal: of gum are comparedato a'-.reactionttemperature of only-*'.600? *-F.

temperature-range insubstan- .{EXAMRLE V in another series' of experiments a large quantity of denitrogenated gasoline is prepared-bythesorption ri'iethd and is then subjected to desulfur'i'zation' at a te'iuperaure of 900 F. at a liquid hourly space 'veloeity '0 L'fl at atmospheric pressure" When the denitrogenate'd gasoline is compared with the raw; gasolinefordesulfurization and octane =r-ating increase' under these conditions; it is found 1720 "that' the resnlts' are considerably-more" favotable in the -case-inwhicli the-nitrogen is -r'e'm'oved by the preliminary adsorption step.

EXAMPLELVI In another-series OfeXperimentsthe catalyst'wa'scokjed by desu1furizing, low nitrogen-gasolin-*and"the*oked catalyst was then tested for nitrogensorptionj activity. It was found that the nitrogen'sorption activity 'jwajspres- "entin' the coked; sample of cata'lyst-to' theextent 'o'f, about stock- 3 50 5 of, that" for the: uncokedi fr eshisamples. Similarly, favorable results were obtained whencatalystfwhichfliad been coked during ttre'cracking of 'a lownitrogengasoil, was tested for sorbing nitrogen compounds from gas oil.

It is thus apparent that in its broad application this invention comprises a two-step method for catalytically treating hydrocarbon stocks of the gasoline and kerosene boiling range wherein the material is subjected to a preliminary removal of nitrogen in a sorption zone and is subsequently subjected to catalytic treatment in a catalytic conversion zone. These steps may be carried out in any suitable catalytic processing method such as moving bed, fluidized bed, fixed bed, slurry type media and the like.

In the sorption step the feed stock is separated into a nitrogen rich oil which is sorbed on the catalyst and a nitrogen-lean oil which is non-sorbed by the catalyst. The nitrogen-lean oil is thereafter subjected to treatment in a conversion zone. The nitrogen-rich oil is removed from the catalyst. The methods for removing the nitrogen compounds from the catalyst which have been described hereinabove include hydrogenation, combustion, and/or desorption as in vacuum or by steam stripping, heating and the like. It is apparent however that other methods such as solvent treatment, acid treatment, stripping with other compounds such as alcohols, acids and the like may be similarly employed.

The foregoing disclosure of this invention is not to be considered as limiting since many variations may be made by those skilled in the art without departing from the spirit or scope of the following claims.

We claim:

1. A process for the catalytic conversion of a mineral oil distillate boiling below about 700 F. and containing between about 0.01% and 5.0% by weight of nitrogen in the form of organic bases, which comprises flowing a compact bed of granular catalyst through a relatively cool sorption zone, then through a regeneration zone wherein said catalyst is subjected to combustion-regeneration and is reheated to at least the temperature of the hereinafter specified conversion zone, dividing the resulting regenerated catalyst into a first stream and a second stream, flowing said first stream through a cooling zone and then into said sorption zone, flowing said second stream through a relatively hot conversion zone and then into said sorption zone, countercurrently contacting said distillate in vapor phase first with the combined catalyst streams in said sorption zone at a temperature between about 10 and 200 F. above the boiling point of said distillate, a pressure between about atmospheric and p. s. i. g., and at a flow rate controlled to provide a catalyst/oil ratio between about 0.1 and 20.0 thereby sorbing a major proportion of said nitrogen bases on said catalyst without effecting any substantial degree of conversion, withdrawing nitrogen-lean distillate from said sorption zone, countercurrently contacting said nitrogen-lean distillate with said second catalyst stream in said conversion zone at a temperature between about 750 and 1000 thereby effecting a substantial conversion of said nitrogen-lean distillate, said sorption zone being maintained at a temperature at least 100 F. lower than said conversion zone, said catalyst comprising a major proportion of at least one adsorptive oxide selected from the group consisting of silica, alumina, and natural clays.

2. A process according to claim 1 wherein said regeneration zone is divided into a first, non-oxidizing desorption zone wherein sorbed nitrogen compounds are removed, and a second oxidizing zone wherein coke and heavy residuals are burned from said catalyst.

3. A process according to claim 1 wherein the weight ratio of catalyst to distillate in said sorption zone is between about 0.5 and 10.0.

4. A process according to claim 1 wherein said mineral oil distillate is a gas oil boiling below about 700 F. and containing between about 0.1% and 5.0% of nitrogen in the form of organic bases, and wherein said contacting temperature in said sorption zone is not more than about 750 F., and said conversion is cracking.

5. A process according to claim 1 wherein said mineral oil distillate is a gasoline fraction boiling below about 400 F. and containing between about 0.01% and 0.5% of nitrogen in the form of organic bases, and said conversion is desulfurization.

6. A process according to claim 1 wherein said mineral oil distillate is a gasoline fraction boiling below about 400 F. and containing between about 0.01% and 0.5% of nitrogen in the form of organic bases, and said c0nversion is reforming to improve the octane rating of said gasoline.

References Cited in the file of this patent UNITED STATES PATENTS 2,042,298 Davis May 26, 1936 2,203,470 Pier et a1. June 4, 1940 2,384,315 Kuhl Sept. 4, 1945 2,414,973 Nelson Jan. 28, 1947 2,432,644 Alther Dec. 16, 1947 2,441,572 Hirschler May 18, 1948 2,507,523 Houdry May 16, 1950 2,528,586 Ford Nov. 7, 1950 2,566,353 Mills Sept. 4, 1951 2,582,415 Claussen Jan. 15, 1952

Claims

1. A PROCESS FOR THE CATALYTIC CONVERSION OF A MINERAL OIL DISTILLATE BOILING BELOW ABOUT 700* F. AND CONTAINING BETWEEN ABOUT 0.01% AND 5.0% BY WEIGHT OF NITROGEN IN THE FORM OF ORGANIC BASES, WHICH COMPRISES FLOWING A COMPACT BED OF GRANULAR CATALYST THROUGH A RELATIVELY COOL SORPTION ZONE, THEN THROUGH A REGENERATION ZONE WHEREIN SAID CATALYST IS SUBJECTED TO COMBUSTION-REGENERATION AND IS REHEATED TO AT LEAST THE TEMPERATURE OF THE HEREINAFTER SPECIFIED CONVERSION ZONE, DIVIDING THE RESULTING REGENERATED CATALYST INTO A FIRST STREAM AND A SECOND STREAM, FLOWING SAID FIRST STREAM THROUGH A COOLING ZONE AND THEN INTO SAID SORPTION ZONE, FLOWING SAID SECOND STREAM THROUGH A RELATIVELY HOT CONVERSION ZONE AND THEN INTO SAID SORPTION ZONE, COUNTERCURRENTLY CONTACTING SAID DISTILLATE IN VAPOR PHASE FIRST WITH THE COMBINED CATALYST STREAMS IN SAID SORPTION ZONE AT A TEMPERATURE BETWEEN ABOUT 10* AND 200* F. ABOVE THE 90% BOILING POINT OF SAID DISTILLATE, A PRESSURE BETWEEN ABOUT ATMOSPHERIC AND 100 P. S. I. G., AND AT A FLOW RATE CONTROLLED TO PROVIDE A CATALYST/OIL RATIO BETWEEN ABOUT 0.1 AND 20.0 THEREBY SORBING A MAJOR PROPORTION OF SAID NITROGEN BASES ON SAID CATALYST WITHOUT EFFECTING ANY SUBSTANTIAL DEGREE OF CONVERSION, WITHDRAWING NITROGEN-LEAN DISTILLATE FROM SAID SORPTION ZONE, COUNTERCURRENTLY CONTACTING SAID NITROGEN-LEAN DISTILLATE WITH SAID SECOND CATALYST STREAM IN SAID CONVERSION ZONE AT A TEMPERATURE BETWEEN ABOUT 750* AND 1000* THEREBY EFFECTING A SUBSTANTIAL CONVERSION OF SAID NITROGEN-LEAN DISTILLATE, SAID SORPTION ZONE BEING MAINTAINED AT A TEMPERATURE AT LEAST 100* F. LOWER THAN SAID CONVERSION ZONE, SAID CATALYST COMPRISING A MAJOR PROPORTION OF AT LEAST ONE ADSORPTIVE OXIDE SELECTED FROM THE GROUP CONSISTING OF SILICA, ALUMINA, AND NATURAL CLAYS.