US2925375A - Hydrocarbon refining and conversion process including removal of organic nitrogen compounds with azeolite - Google Patents

Description

Feb. 11s, 1960 R. N. FLECK ETAL HYDROGARBON REFINING AND CONVERSION PROCESS INCLUDING REMOVAL OF ORGANIC NITROGEN- COMPOUNDS WITH AZEOLITE Filed NOV. 26, 1956 'Raymond N. Fleck, Whittier,

'p.s.i. and above.

HYDROCARBON REFINING AND CONvRsIoN PROCESS INCLUDING `REMOVAL OF ORGANIC C and lCarlyle G. Wight, Fullerton, Calif., assignors to Union. OilA Company of fornia. v f

Application November Z6, 1956, SerialNo. 624,387 14 Claims. (Cl. 2 084-89) California, Los AngelesCalf., a corpora This. invention relates to thek refining and conversion of hydrocarbons andV particularly to ran improveclprocessv for relining gasoline `boiling range materials kof low antiknock rating and conversion ofsuch 'materials by catalytic rening'and dehydroaromatization to 'produce increased quantitiesV of high antiknock rating fuels sult-` able for use as premiumautomotive and aviationffuels.l

Modern premium -automotive Vand aviation gasoline fuels are used in very high compression engines where ordinarily an antiknock rating of 98 to l0() is` the minimum tolerable value.' Thesexfuels'fare frequently a blend of alkylate, being a mixture of a highly, branched C7 toCg paraiiin hydrocarbons, together with anl aromatic blending stock forming the fuel tov which isadded the usual few milliliters"of'tetraethyllead T heiaromatic' blendingk stock is nearly alwaysA produced by' dehydro-V genation of naphthene vhydrocarbons. The naphthenesV often; are produced by paraflin dehydrocyclizationjreactions' and a catalyst which increases therate offre-vv .l

action is nearly-always employed.'V Such processes and the products Which are tion of Caliy produced thereby, arefknown to` Y y'I'heffpresent'invention is Ydrectedltoi animprovedV process of the type-discussed aboveforthe desullurizaft l i 2,925,375 Pfefed'febf1611?@ P ice.

tion, denitrogenation,-andjaromatizationr of gasolinel in'- which a substantially complete removal fof hydrocarbon'derivatives of nitrogen is obtainedwithoutvthe neces sity'ofthese extremely high superatmosphericpressures. *l

It is ay primary object' therefor of this inventionto providean improved `process for the retining andconversion of gasoline.

j combined proces'slfor-.the-catalytic desulfurization andlf derutrogenation of low grade gasoline ystreams followed"v Itis a further objectof this invention to provide 'a by the catalytic reforming ofy the thus, treated material* including an intermediate step which' completelyremoves residual yquantities of hydrocarbon compounds of nitro-If t gen f rom the feedstock to 'the reformingstep. t

.it isa lspecific object vof this invention to VprovideQin-Y' thepdesulfurization Aand reforming process referredlstof above, an intermediate?adsorptivel treatment of thefeed? stock tothe reforming zone with a particular'solid"con' 'V tact material so as to effect a substantially complete elimi-l Y nation of residual hydrocarbon compounds ofnitrogen'.v

- f .Brieflyv the -presentinventioncomprises an `improvedl `^combination process forl the-.production of high quality e Other objects and advantages of the present'invention will become more apparent to those skilled'in the art as the description and illustration thereofproceed.A f

premium or aviation grade gasoline 4fuels having high anti-` knockatings from hy'r'ocarbon 'naphthas heavily c`on-- tar'ninated with hydrcrx'ca'rbo'njderivativesY of sulfur and`` nitrogen. The ct'irnbinationy process includes three essential steps; namely a catalyticdesulfurization and de-' nitrogenation step in whichK hydrogen isconsumed in the"- reaction,I an adsorptivef-stepinfvvhich residual hydrocarifA be detrimentally aifected by the presence of hydrocarbonv derivatives of sulfur and nitrogen in the., feedstock and therefore frequently the raw hydrocarbonk feed; issubjectedfto a catalytic desulfurization and -denitrogenation treatment to minimize these problems f Considerable quantities off` `such premium:fuelslarev presently being produced vfromV low grade gasoline boiling range naphthas byiirst'catalytically desulfurizingfthe feedstock in the presence ofhydrogen.' This'r removes substantially all of the hydrocarbon derivativesof-sulfur and the major portion ofthe. hydrocarbon drivativesY of nitrogen.

of vhigh antiknock rating. This degreeiof'des'ulfurization is obtained using a cobalt molybdate catalyst and-atcon ditionshereinafter more fully' described.v It-:has been found however that although most 'of thenitrogen comu pounds are removed, a significant residual yquantitygre-V mainsY which still hasan adverse elfect uponthesubse-` quent catalytic dehydroaromatization step, commonly referred to as reforming. The adverse results are most pronounced when ,thel reforming catalyst` comprises a platinum catalyst, particularly a,v halide (commonly iluoride or chloride, or both);,promotedJplatinum'reforming catalyst supported on' an alumina `base and in which alkyl halides are added kto the;L feed to maintainjthek cat-v alyst activity. 1 The` nitrogen compounds appear toy-re,-

act with thecatalyst 4or with thealkyl halides 'o1-both to vprecipitate ammonium halide, inrthesystem.y -This causes lmechanical'diiicultiesgand can cause catalyst deactivation.'V f

p .It has beendetermined thatA theseresidualjfquantities l .2. v of hydrocarbon derivatives of nitrogencamberemoved onlyby raising the desulfurization .pressure to extremely high values, namely Yof theforder of 5,000 Vto 15,000 Such operatingfpressuresfin' thede- .comercial basis sulfuri'zration Vof, hydrocarbonsVv onv fa The thus treated -material,is then lcatalytically dehyroaromatized toproduce the aromaticblending'stock bon compounds of` nitrogen'a'r'e removed, and' a` catalytic f reforming or dehydroaromatization step in which hydro-- gen is produced: v y i Inf the rst step'the gasoline boiling vrauge'- feedstocky is contacted in the presence of hydrogen vvith a de`-` sulfurization and denitrogenation catalyst wherebysubstantially all off-the hydrocarbon" derivativesof sulfur? and the great .majority of thel hydrocarbon derivatives 'of nitro# -gen are-decomposed fcatalytcally. fl'heproducts of? l these ,reactions `are`hydrogenated fragments "of Vthe sul-if fur or nitrogen compounds togetherwith` ammonia, and hydrogen sullide.A The resulting substantallysulfur-free i gasoline is then lcooled-from -the desulfurizati'on tem-4 perature substantially toits dew point.

'are arme `present'timeatremqpraefica11y impossible;V

In the second process'step, the'thusl cooled stream `is then contacted with. agranular isolidfzeolitic metallo alumino silicate activated .by partial dehydration: and

which-has pores rope'n to adsorption Whichare atleast' 7 A. in diameter, and which'preferably areo lthe order:

of-r7 A. to l3fA.rin'diameter, orlmore... These materials exert extremely high ypreferential adsorptiveiforc'es for: the minor amountvof residualhydrocarbon `.derivatives of `nitrogen present'in thedesulfurizatinzfeliiuent vapori even inthe presence of'hydrocarbo'rlsofuthe fs'ame boil-r.

ing range. The 'eluent' from thisl adsorption-'step is substantially free of rhydrocarbon'.derivatives of nitrogen;

or if any traces remain theylarecof ,such-minor Jmagni' f; tude tha'tuthey exert no measurable adverse "effect: upon the subsequent catalytic 'reforming stepf L ln the third step of the process the adsorption efuent containing substantially-,no :hydrocarbon derivatives of sulfur and nitrogenis rehe'atedfto chydrocarbon reforming cyclizationof. parain; hydrocarbons., 'Die eflluentr from the catalytic reforming step -is cooled and partially condensed and the gas rich in hydrogen produced during the reforming step is Vre'circulated to; the-desulfurization and denitrog'enation step-together with` freshY feed. This hydrogen isconsumed in the desulfurization and denitrogen- `ation reactions. The ,recycle hydrogen stream maybe purified if `desiredto remove accumula-tions of hydrogen sulfide,l ammonia, water vapor,l low molecular weight hydrocarbons, and the like. Y

In the first or catalytic desulfurization and denitrogenation step of this process it is preferred to employ a'cobalt molybdate'catalyst supported on a silica stabilized activated alumina carrier. The cobalt molybdate catalyst may analyze between about 7% and 22% by weight of totalf cobaltl oxide and molybdenum trioxide. The molecularratio of cobalt oxide to molybdenum trioxide is in .the range from about 0.2 to about 5.0 mols per mol. One preferred form-oft cobalt molybdate catalyst analyzes'Y about 3% by weight cobalt oxide and 9% .by weight molybdenum trioxide. The total cobalt and molybdenum oxide analysis in this catalyst is 12% and the molecular ratio is 0.64. Proper temperaturesA for effectingthe desulfurization and denitrogenation lie between about 575 F. and-about 900 F., preferred operating temperatures lying between about 700 F. and 850 P. The operating pressure may be varied widely between about 50 and 5,000 p.s.i.g-. and is preferably operated between about 300 and 1,000 p.s.i.g` ata value which is substantially the same or slightly higher than the operating pressure used in the catalytic reforming step. The liquid hourly space velocity measured in liquid volumes of feed per volume of catalyst per hour may be varied between about 0.1 andV about 10, but preferably is in the range of from 1.5 to 6.5. A hydrogen recycle gas analyzing between about 35% byvolume and about 95% by volume of hydrogen is recirculated through the catalytic desulfurization zone at a rate of about 50l and 10,000 s.c.f:/b. (standard cubic feet par barrel) of feed. Preferred hydrogen to feed ratios lie between about 1,000 and about 5,000 s.c.f./ b. In the preferred operating con` ditions indicated `above a low grade sulfur and nitrogen contaminated gasoline can be trcatedto produce an effluentgasoline having a substantially zero sulfur analysis and analyzing of the Vorder of 100 to 300 parts per milliono-f nitrogen, from a feed gasoline analyzing about 0.55% by weight of sulfur andl about 0.27% by weight of nitrogen.

In the second or intermediate step of the process of this invention, .the desulfurized, andpartially denitrogenated gasoline effluent produced from the catalytic desulfurization and denitrogenation step is passed through contact with-a static or movingbed, or auidized body, of a natural or syntheticy zeolitic metallo alumino silicate having pores of at least 7 A. so as to remove residual traces of hydrocarbon derivatives o-f nitrogen. This contact'is effected at substantially the same pressure. as those employed in the desulfurization and reforming -steps and at a temperature which is just above the dew point of the mixture of gasoline and hydrogen recycle gas. With lower ratios of hydrogen recycle gas, or where the recycle gas is separated prior to this step, this temperature approaches about 400 F. With higher recycle gas ratios -this temperature may drop as low as about 275 F. Temperaturesl as high as the desulfuriz-ation temperature may be employedy if desired although the adsorptive capacity of the specific adsorbent hereinafter defined is somewhat reduced.

It has been found :that the specific zeolitic adsorbent employed in the present invention may not be substituted with the other known granular solid -adsorbents such as silica gel, activated aluminum oxide, activated charcoal, and the like. At these operating temperatures the adsorption capacity of these materials is reduced to subs tantially zero, and there appears to be no particular affinity for nitrogen compound adsorption. With the preferred adsorbeng however, it is found that the very high selective adsorption capacity `for hydrocarbon derivatives of nitrogen is substantially unaffected at these temperatures.

The adsorbent employed in the process of this invention is a solid granular material having a mesh size range between about 2 and 100 mesh or smaller and 'preferably' between about 4 and about 30 mesh for static or moving solids bed contact. It is used in the form of a dense compact bed of material through which the desulfurization effluent stream passes in the vapor phase. The process may employY the adsorbent in the form of a single static bed of material in which case the process is only semicontinuous. Preferably a plurality of two or more static beds of adsorbent is employed with appropriate remotely operable valving so that the feed stream is passed through one or more of the contacting vessels in a set while the regeneration gas stream passes through one or more of the otherY Vessels in the set. In this case, the feed and product flows -are continuous; In another modification, a moving solids bedmay be employed. Here the ilow of feed ismaintained continuously through a rst contacting or adsorption zone, and the ow of regeneration gas is maintained continuously through a second contacting or regeneration zone. The granular adsorbent is recirculated successively through these two zones. With the smaller sized mesh ranges of adsorbent, eg. with powdered solids, the material may be uidized in and by the fluid streams contacting it. The compact bed modifications are preferred since a greater number of theoretical and actual contact stages are more readily obtained in smaller and simpler equipment.

The present invention may not be carried out with the commonly available solid granular adsorbents as indicated above. It has been 'found that particular adsorbents vwhich are highly ecient and preferred in the adsorptive denitrogenation step of the present invention are the natural or synthetic crystalline partially dehydrated metallo alumino silicates. The composition of one typical synthetic zeolite having `a pore size of about 13 A. is SNaZO sizes of 10 A. .They may be prepared by heating stoichiometric quantities of alumina and silica and excess caustic under pressure. The excess is washed out. Other desired metal ions may then be introduced by ion exchange. Part of the sodium in this material can be ion exchanged with concentrated salt solutions at superatmospheric pressure and temperatures of -300 C;

to introduce other metal ions. Certain naturally occurring minerals, such as chabazite, analcite, gmelinite, and the like, can be heated to dehydrate the molecule partially and obtain a-nactivated zeolitic adsorbent similar in adsorption properties to the manufactured materials. These natural andsynthetic materials are all zeolites and their sodium and calcium derivativesare very stable solids whichapparently have poresv available for adsorption which are quite uniform in size. Other derivatives have diiferentsized pores The 10 A. and 13 A. metallo alumino silicate, and others with pore diameters above 7 A. exert preferential adsorptive forces for hydrocarbonnitrogen compounds in great preference to the hydrocarbons of the same boiling range.

In the process of this invention Vthe solid contact material utilized for the adsorptive denitrogenation of the desulfurization eilluent appears to be deactivated only very slowly. Ultimately fin a long continued process the material may require regeneration due to the accumulation on the material of traces of very high molecular weight hydrocarbonaceous materials present in the feed stream. Since the temperature at which the feed contact occurs'is approximately 400 F. and thus is relatively low, little if any chemical'reaction ordinarily occurs in contact with the material. The accumulated deactivating A Another composition has pore customarily employed inthe oxidativev regeneration ,ofv

. generation may also be eEected by stripping with steam followed by contact at this temperature with anA anhydrous gas.

In the third or catalytic reforming step of the process of this invention the desulfurizedy and denitrogenated gasoline is passed in the vapor phase through a reforming catalyst which may be molybdenum trioxide, chromium oxide, cobalt molybdate, or the noble metals. An excellent catalyst is one containing between about 0.01 and about by weight of platinum and preferably between about 0.1 and 0.5% by weight of platinum. The catalyst is promoted by inclusion of a minor amount of a halide such as chloride or fluoride Vor both in the alumina carrier. With any of the known reforming catalysts the processing conditions may be as follows: The liquid hourly space velocity in this step may be varied between about 0.1 and 10, but preferably is about 1.0. A recycle gas containing hydrogen is also maintained iiowing through the catalytic reforming zone. The quantity of such recycle gas ranges yfrom about 50 to 10,000,

but preferably is between about 1,000 and 5,000 s.c.f./bf

The operating pressure may be between about-5 and about 500 p.s.i.g., and a pressure of about 300 p.s.i.g. is preferred. Suitable temperatures may be between yabout 800 F. and about 1050 F. Under the preferred operating conditions of the reforming step a reformed gasoline is produced substantially free of sulfur and nitrogen and which has an antiknock rating of theorder of IOO-I-(F-l-i-B ml. TEL).

The process of this vinvention and the various modifications and applications thereof, aswell as several forms of the apparatus, in which the process may be effected, will be more readily understood by reference to the accompanying drawings in which: Y

Figure 1 is a schematic flow diagram of the process of this invention for refining and conversion of low grade gasolines, and

Figure 2 is a modification ofthe flow `from the desulfurization to the adsorption steps. n f l TABLE I Process feedstock n l Boiling range, F. ,.120--440 Gravity, API 46.8 Sulfur, Wt. percent 1.21 Nitrogen, ppm. 260 Knock ratings:

F-l clear 63.5

F-.1+3 ml. TEL 71.0

The feed gasoline is introduced through line 22 at a rate of 5,000 barrels a day controlled by valve 24 and is heated and vaporized in vaporizer 26 to a temperature of about 750 F. Heater 26 is provided with fuel through line 28 controlled by Valve 30 at a rate which is lvaried by means of temperature controller r32m response to the temperature of -vapor passing, yfrom furnace .26 through line 34 into catalytic refining zone 10. If desired, all or a portion of the hydrogen-containing'recycle gas may be combined with the `feed by passing it through line 36 controlled by valve 38 into the inlet to furnace 26, or it, may be ,immerse tareas# .line 4.9 .at a at? laflfielled by valve 42 through `hydrogen preheater 44 into adrn-ixturel with the heated Iand vaporized -feed owing through line'.

34. The total hydrogen recycle rate is 10,000 M s.c.f. per day, or about 2,000 s.c.f./b. v

The combined naphtha vapor and hydrogen recycle Vgas mixture passes at a pressure of about 500 p.s.i.g..'and at a temperature of 750 F. through catalytic refining zone 10. This zone contains a static bed of cobaltmolybdate catalyst analyzing 3% cobalt oxide and 9% molybdenum trioxide ona silica stabilized alumina carrier. The liquid hourly space velocity is about 4.0. During this contact under these conditions better vthan 99.5% of the hydrocarbon `derivatives of sulfur in the feedstock is .convertedV to hydrogenk sulfide and hydrogenated hydrocarbon fragments. 'About 96.3% of the hydrocarbon derivatives of nitrogen are removed. The inspection of the product isI given below in Table II.

This effluent from the catalytic refining zone 10 passes through line 46 into heat exchanger 48 in which the effluent is partially cooled and heat is recovered in re v heating other process streams such as the feed to -thev catalytic reforming zone. The partially cooled eiiuent flows through line 50 through cooler 52 through which sufficient coolant is passed by means of line 54 in order to c ool the efliuent further to a temperature 'just above` its dew point. This control is effected by means of teniperature'controller 56 and valve 58. The sulfur-free and` substantially nitrogen-free efiiuent then iiowsthrough line 60, four-way control valve 62, and line 64 into and through first adsorber 12. Here vis maintained astatic bed of metallo alumino silicateadsorbent of 13 A. pore size. passing through adsorber 12 is between about'S and10`A Volumes of liquidhydro'oarbonv per volume of'adsorbent per hour.v During this contactv all residual y.traces ofk hydrocarbon derivatives of nitrogen present inthe stream are removed by the adsorbent, and the nitrogen and sul# fur-free efiiuent continues through line 66,k four-way controll valve 68, and is sent through means" subsequently described to the catalytic reforming zone. If desired, the modification in Figure 2 may be used. Here the desulfurization efliuent is condensed lin cooler 47, passed Vto Aseparator 49 in which the noncondensed recycle and other gases are separated from the condensate through line 51. The condensate is revaporized and heated to a temperature somewhat above its'end'or-dew point in vaporizer 53 and passed through contact with the adsorbent in zone Thegas thus by-passes the adsorption step through line 55, and is introduced into the adsorption effluent for passage through the catalytic reforming zone. This brings the nitrogen compound 'coniy centration to a maximum and increases the amount thereof which can be adsorbed on the zeolitic silicate. If desired, the gas may be purified in treating zone 57 to raise the hydrogen concentration by'removal of ammonia, hydrogen. sulfide, andA light hydrocarbon gases through line 59.

The 13 A. silicate adsorbent present in lsecond adsorber 14 is` shown being regenerated at temperatures rang.'- `ing between about900? F. and about 1100. F. by ciriculating therethrough a stream of flue gaswin which is mixed between about 0.1% and abouty 10%1by volume of oxygen. By this means the residuali adsorbeduhydrocarlbon derivatives o f 'nitrogenpresenton:thefadsorlg'epg .91:9

The liquid hourly space velocity of the' stream` foiningcombustion products which are removedfrfom the system.A Flue gas passes by means of recycle blower 70 at a rate controlled by valve 72 through regeneration cooler 74 in which the exothermic heat of combustion is dissipated. The cooled gas, at a temperature of about 750 F., continues through line 76, is mixed with air introduced throuh line 78 at a rate controlled by valve 80 forming a fresh regeneration gas. This gas passes through four-way control valve 68 and line 82 through secondary adsorber 14 in which the nitrogen cornpounds are burned and the adsorbent is regenerated.v Hot flue gases at a temperature of about 1050 F. are discharged through liine 84 and pass through four-way control valve 62ffor division into two streams. One stream is recirculated as stated by means of blower 70 and the otherA stream is vented to the atmosphere through a stack by means of line 86 at a rate controlled by valve y88.

Four-way control valves 62 and 68 are operated remotely by means of cycle timer operator 90. This operator serves to reverse the settings of valves 62 and 68 periodically thereby alternating the contact of the 13 A. silicate `adsorbent therein with the refining zone efuent and the regeneration gas as described.

The composition of the eiuent from the adsorption zone fand the feedstock to the catalytic reforming zone is given in Table III. The gravity, knock rating, and boiling range are substantially the same as noted in Table II.

TABLE III Rejning zone feedstock Sulfur, wt. percent 0.0005 Nitrogen, p.p.m 0.5

The adsorption euent flows therefrom through line 92 through exchanger 94 through line 96 into reforming zone preheater 98. If desired, an added quantity of recycle hydrogen may be introduced through line 100 at a rate controlled by valve 102. By means of exchanger 94 and vapor reheater 98 the nitrogen-free hydrocarbon and hydrogen stream is reheated to reforming temperatures of the order of 910 F. This is controlled by means of valve 104 in fuel line 106 which is actuated by temperature controller 108. The reheated hydrocarbon and hydrogen stream flows through line 110 successively through first reforming zone 16, intermediate reheating zone 112, second reforming zone 18 and is discharged therefrom through line 114 through product cooler and condenser 116 into recycle gas-liquid product separator 20. First reforming zone 16 is maintained at an average reaction temperature of about 910 F. The etliuent therefrom is cooled by means of endothermic dehydroaromatization reactions to a temperature of about 890 F. Interheater 112 reheats this effluent to about 915 F. for reaction in second catalytic reforming zone 18. The effluent from this zone is similarly cooled from this reaction temperature by these endothermic reactions zand is removed therefrom at a temperature of about 900 F.

In separator 20 the reformed liquid product is removed through line 118 at a rate of about 4365 barrels per day controlled by valve 120 and liquid level controller 122. It is sent to production or further processing facilities not shown by means 4of line 124. The properties of this product are listed below in Table IV.

TABLE -IV Liquid product properties Boiling range, F. 124-4214 Gravity, API 43.7 Sulfur, wt. percent 0.00 Nitrogen, p.p.m. 0.2 Knock rating (F-l-t-3 ml. TEL) 101 A hydrogen-containing recycle gas is removed from the upper portion of separatorlflV lthrough line 126. The gas analyzes yapproximately 75% hydrogen and also coniainslightA hydrocarbon gases together with water vapor,

ainioi'a, a'dhydrg'e suldeif these have norbee'uv removed'immediately after the desulfurization step. De# pending upon the quantity of hydrogen and sulfur com-.l

- operation and in this instance such makeup hydrogen is added through line 128 in the reverse direction.

The remaining quantity of gas ows through line 134 into recycle gas compressor 136 and from there through gas purification zone 138 in which hydrogen sulde and ammonia, if not previously removed, are removed from the recycle gas. This is done in order to maintain the hydrogen concentration as high as possible in the recycle gas. Any of the many well 'known ways for removing ammonia and hydrogen sulfide from hydrogen and hydrocarbonLcontaining gases may be used. For example, the ammonia may be removed by washing with water or with dilute acids, hydrogen sulfide may be removed by washing with oil or water, or with monoethanolamine or diethanolamine, or the like. If desired, all or a portion of these contaminants may be removed. If desired, all or a portion of the hydrogen contaminants may also be removed. This may be done in any of the well known manners such as by oil absorption, adsorption on a solid adsorbent, low temperature distillation, and the like. The recycle gas is then passed through line for recirculation in the process.

In order to illustrate in the foregoing process the effect of allowing the residual 10 ppm. of hydrocarbon compounds of nitrogen to remain in the feedrto the catalytic reforming zone, the efuent from' the catalytic refming zone 10 was by-passed around the adsorption zones 12 and 14 and sent directly to the catalytic reforming zone. Operating conditions were otherwise identical to those given in the foregoing example. The' reformed product had the following properties:

TABLE v Product analysis Bening range, F. 124424 Gravity, API 43.7 Sulfur, wt. percent 0.0005 Nitrogen, p.p.m 5.0 Knock rating (F-l-l-3 ml. TEL) 92 Ammonium halide deposits in the system under these conditions and deactivatesthe catalyst.

It is apparent that the removal of this relatively minor amount of hydrocarbon derivatives of nitrogen has eiected a substantial improvement in the quality of the liquid product raising the knock rating about 9 points.

Although the process of this invention has been described above in detail by reference to a preliminary catalytic desulfurization and denitrogenation step and a subsequent catalytic dehydroaromatization step, thek present invention is applicable in the treatment of hydrocarbon feedstocks to treat for complete nitrogen removal in the feedstock to such other catalytic conversions and rening processes which are adversely affected by the presence of such materials. For example, the catalytic reforming step described above may be substituted with a catalyticv isomerization step, a catalytic cracking step,` or thevlike. In each of these catalytic conversion processes the feed-stock is very desirably pretreated for the removal of hydrocarbon derivatives" of sulfur. This is acpressures will remove catalytically all of these nitrogenousL materials in the catalytic reforming and accordinglythe intermediate adsorptionstep using the zeolitic adsorbents, with pores of 7 A. and over is used. In each of thesev f Y 'cases the quantity and quality of the etiluent from the subsequent conversion zone is markedly irriproved by the removal of all of these contaminants. t

Al particular embodiment of the present invention has been hereinabove described in considerable detail by way `of illustration. It should be'tunderstood that various lother 'modifications and adaptations thereof may be made'bythose skilled in this particular art without de-` partingfrom the spirit and scope of this invention as set v Y forthinthe'appended claims. f 1* We claim: y a n s 1. In aprocess wherein'a normally liquid'lhydrocari 0.11 and10.0 volumesk yof liquid feed per Vvolume of cat- Aa first hydrocarbon etiiuent substantially free of organic `sulfur compounds but `containing small amounts oforganic nitrogen compoundspassing said irst effluent in the alyst per hour, and hydrogen recycle rates between about -A50 s.c.f."and` 10,000 s'.`c.f./b. fof hydrocarbon,to produce vapor phase through an adsorption zone in contact with Aa partially dehydrated zeolitic metallo alumino silicate adsorbent having pores of substantially uniform diameter ofgat least 7 A.` to produce a second hydrocarbon efuk. ent substantially free .organic nitrogen compounds; y passing said second-hydrocarbon efliuent through a rebon mixture which Yis contaminated with normally incident organic sulfur and organic nitrogen compounds of subst'an` tially the same boiling range is `(l) subjected to a catalytic desulfurization treatment in a` desulfurization zone to produce a hydrocarbon effluent which is substantially/,free

oforganic sulfur compounds but'contains small amounts i version zoneto -produce a .process productof improved qualities, said catalytic conversion ,treatment being one which'is adversely aiected by the presenceV of said'small amounts .of organic nitrogen compounds, the yirriproveof organic nitrogen compounds, and (2) said effluent is subjected to a catalytic.` conversionl treatment ini aconi ment which consists inY contacting said"r effluent inthevapor phase with a partially dehydrated zeolitic metallo alumino silicate having pores of substantially.r uniform to subjecting said efuent to rsaid catalyticcon'version treatment. Y 2. A process according to claim 1 wherein the-said catalytic conversion treatment comprises catalyticfdehydroaromatization. ,y Y

3. A process according to claim 1 whereinthe said zeolitic" silicate has a composition corresponding substantially to 5Na2O6Al2O315SiO2 and has poresofsubstantially uniform diameter of about 13 A.

4. A process according to lalm 2 1n combinationwith the Asteps of cooling and partially condensingrthe said eiiiuent; separating the non-condensed gasesffromtthe condensate; revaporizing the condensate; introducing the diameter greater than 7 A. in an adsorptionzone prior forming zone in the presence of hydrogen and a dehyf n droaromatizationv catalyst while controlling the reforming V15 conditions therein at temperatures between about 800 F. and about 1050 F., pressures between about 5 and about V500"p.s.i.g., liquid'hourly space velocities between about 0.1 and about 10.0 volumes of liquid hydrocarbon per volume of catalyst per hour, and hydrogen recycle 20 rates between about'SOfand about 10,000 s.c.f./b. of

feed; cooling and .partially 'rcondensing the efliuent fromsaid reforming zone; rseparating the" 'condensate' gasoline l fas y*the process lproduct from the nonocondensedp gases; and recirculating at least part of said gas to said desulkfurization zone.

8. A process according to( claim.7 wherein said desulfurization catalyst comprises cobalt molybdate and contains between` about 7%k and 22% by weight total f cobalt oxide andmolybdenum trioxide, and in which the Y y moleculary ratioof cobalt oxide to molybdenum trioxide y is between about-0.2 and 510 mols per mol.

9. A process according to claim 7 wherein said dei hydroaromatization zcatalyts comprises between V0.01 and 10.0% by weight of a ynoble metal promoted by a halide. 10. A process according to claim 7 in combination with the step of periodically regenerating said metallo alumino silicate by contacting it with an oxygen-containing j gas to burnk adsorbed organic nitrogen compounds therefrom. f

11. A process yaccording toclaim 7 yin combination f `with" the steps of cooling and vpartially condensing said 'rs't hydrocarbon effluent; separating the condensate from the noncondensed gases; revaporizing said condensate revaporized condensate substantially free of Vnon-condensible components into contact with Isaid zeolitic sili'- cate, and combining the non-condensed gases with the effluent from said adsorption zone for introduction into said conversion zone. l Y

5. A process according to claim 1 in combinationtwith the' step of passing a hydrogen-containing gas with said v hydrocarbon mixture through said desulfurization,l adsorp.- l tion, and conversion zones, separating said gas from thef-` upgraded process product, rand recirculating at least partV for upgrading hydrocarbon mixturesv boil-Y ing in the gasoline range and contaminated with normally j and introducing it into said adsorption zone;` and passing said noncondensed gases intomixture with s aid'second hydrocarbon eiliuent for introduction therewith into said reforming zone.

12. A process according to'claim 11 in combination with the stepof raising the hydrogen concentrationl in saidfnoncondensed gases by removal `therefrom of gases other than hydrogen.

` 13. A process according to claim 7 Ain combination with r.the step Aof controlling the temperature of the fluids passing through said adsorption zone at values slightly vabove the dew point thereof.

14. A process according to claim 7. wherein said zeolitic silicate has a composition corresponding substantially incident organic sulfur and nitrogen'compounds which comprises'passing said mixture through a desulfurization zone in the presence of hydrogen and a vdesulfurization catalystwhile controlling thedesulfurization conditionsy therein at temperatures between about 575 F. and about 900 F., pressures between about 50 p.s.i.g. and about 5000 p.s.i.g., liquid hourly space velocities betweenabout y to 5Na2O'6Al2O3-15Si02 and has pores of substantially uniform diameter of aboutv13 A. v

References Cited in the le of thispatent UNITED STATES PATENTS l 2,717,230 y Murrayetal Sept. 6, 2,758,064 Haensel Aug. 7, 1956 2,763,603 Skinner Sept.' 18, 1956 2,882,244 Milton Apr. '14,

OTHER REFERENCES Linde:` Physical Properties kof Molecular Sieves,

-Form 9947'A, Union Carbide Bulletin.

' "Selective Adsorption with Zeolites, Chemicalfffand Engineering News, volume 32, Nov. 29, 1954, page 3786.

Claims (1)

1. IN A PROCESS WHEREIN A NORMALLY LIQUID HYROCARBON MIXTURE WHICH IS CONTAMINATED WITH NORMALLY INCIDENT ORGANIC SULFUR AND ORGANIC NITROGEN COMPOUNDS OF SUBSTANTIALLY THE SAME BOILING RANGE IS (1) SUBJECTED TO A CATALYTIC DESULFURIZATION TREATMENT IN A DESULFURIZATION ZONE TO PRODUCE A HYDROCARBON EFFLUENT WHICH IS SUBSTANTIALLY FREE OF ORGANIC SULFUR COMPOUNDS BUT CONTAINS SMALL AMOUNT OF ORGANIC NITROGEN COMPOUNDS, AND (2) SAID EFFLUENT IS SUBJECTED TO A CATALYTIC CONVERSION TREATMENT IN A CONVERSION ZONE TO PRODUCE A PROCESS PRODUCT OF IMPROVED QUALITIES, SAID CATALYTIC CONVERSION TREATMENT BEING ONE WHICH IS ADVERSELY AFFECTED BY THE PRESENCE OF SAID SMALL AMOUNT OF ORGANIC NITROGEN COMPOUNDS, THE IMPROVEMENT WHICH CONSISTS IN CONTACTING SAID EFFLUENT IN THE VAPOR PHASE A PARTIALLY DEHYDRATED ZEOLITIC METALLO ALUMINO SILICATE HAVING PORES OF SUBSTANTIALLY UNIFORM DIAMETER GREATER THAN 7 A. IN AN ADSORPTION ZONE PRIOR

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