US2925379A - Hydrocarbon denitrogenation - Google Patents

Description

Feb. 16, 1960 R. N. FLEcK ETAL 2,925,379

HYDROCARBON 'DENITROGENATIQN United StatesfPatent O HYDRocARBoNv DnNrrnocENArroNl i f' Raymond N. Fleck, Whittier, and Carlyle G. '=Wight,r

Fullerton, Calif., assignors to Union Oil Company' of California, Los Angeles, Calif., acorporation of California Y o l Application November 13, 1956, Serial No.1621,674"' Claims. v (Cl. v208,-254) This invention relates to the relining of-hydrocarbons', i particularly those contaminated with normally incidentorganic nitrogen compounds. Such hydrocarbons 4include those which are produced as petroleum, aswellzasp coal tar oilfractions and shale ',oilsamong others. f .r

Many crudeY petroleum streams are produced from the= weight.' 'l Extensive analyses, of thesemtrogen-containin crudos), indicatei that -muclrof the-nitrogenfoccwurs Izinith formmof amines'or these-called nitrogen bases lnclude pyridine,qinnolvnie, and-.the mono, v\.di,j\tri,and

tetra ,alkylatedjderivatives of these Arnaterialsz; :For exi-ky amplethe di, tti, 'adlretfa tlllyltldy quinolinesvandr lal'kylated VpyridinesA commonly occur;,inKDalifonnia kerOfY Seno. distillatesr There is however -considerable Anon-11' bavSicA nitrogen presentein thesematerials. Coaltaroils produced in the coking of coal contain jeXtensive-quan-` titles of `nitrogen bases andthese'areprinipally aromatic amines iand heterocyelionitrogen compounds j-. Shale f oil 'produced by the heating aadrctertligfbf shale rockris'uch aS ,that .whlch vis. found; in-"COlOradQ v'a11'd-le1sewherefjre-f` sembles waxy rcrude but -i ,s,characterized, particularly'in,"

o that it containssuch extensivenquantities oforganicgnigg. trogen'compounds that the nitrogen content runs as high.

as about 2,5% by'weight.

Crude petroleum, coal tar oils, and shale oilsiare cipal or potential sourcesfofliquidlfuels4 and solvents,

The presence of nitrogen compounds inthe fuelrorjsolvent product imparts .aI v ery had odorvtofthese materials.

Theil' PeSeIlQCin the'originaloiljfvery adversely alectsiio hydrocarbon reningtechniquesvbyfwhich the fuels and solvents or lother materials',areproducem They have, f

` for example, a well denedadvers'e eiect onlsuchproca,

l esses as catalytic crackingfetalytic,isomerizatiom y Catalytic rreformin` g", `partielilaarlylgA platinurnvcatalynedi halide promoted reforniingitl, The@nitrogen;compoundsv appear t be adsorbed ongthe catalystaandy selectively devr 5 activate its active cracking centers. In catalytic crack-z fr ing, for example, the gasoline'yieldmaybe reduced as much as by reason of theV presence 'of lsuicient organic nitrogen compounds to give'the feed a nitrogenv s ycontent of about 0.3% by weight, vand reduced'by 75%' when the nitrogen content reaches about0.45'r%`, 'Platirvnum catalyzed reforming and otherreforming processes in general are also` adversely Vaiiected `,by 'the presence of nitrogen compounds in tlie'fee'd.` In avplatinumeatalyzedgasolincreforming system" using a halide promoted platinum catalyst theA nitrogen compounds appear, toreact' with the Catalystvftninglamoaiumihma Which-def f` Thisdactiveffs .the catalystfaail 2,925,379 l Patented el. 15, i960 *ICC 2 lowersV theyield unless-'the halide is continuously replenished. v

Because of these adverse effects, repeated attempts havefb'een made to remove the nitrogen compounds from hydrocarbon feedstiocks in refining processes and from the vproducts produced. For example, acid treating with dilute sulfuric acid forms Water soluble salts withl the basic' nitrogen compounds, i.e. the nitrogen basesY Vor amines;r It is otherwise inelective with respect to the nonbasic nitrogenl compounds. Catalytic hydrogenation iseiectivezto remove most all of -the nitrogen compounds, but in order to reduce their incidence in the hydrogcnated .product to a level'which does not adversely affect a 'platinum catalyzedreformingprocess for gasoline, hydrogenation pressures vof the' order of 5,000 p.s.i.

andihigher are required. Treatment of such materials vvithiullers earth tends to reduce the quantity of nitrol gen compounds, butthis involves'a relatively high liquid` yield loss'throughf'retention of hydrocarbons on the adsorbeutgthe nitrogen*` compounds are. lost through disposal of thelspent'adsorben' and seldom if "ever is thei- H nitrogen analysis reduced sucieiitlyf to'l avoid' r'p'latiniur reforming catalyst poisonin'gf. .f

l"fvThe'"presentrinvehtionfisodirected; to Ya'liighl'yjetiicient l fandzvimproved process, forreinoving.f'aiidv recovering-"the o basic v ds Yfrontcompo petroleum, d1 V compounds:contaminatedwith'nitrogeng if il f f :It asniorespeciic-obiectofthis"invention to denitro-l" genatehydocarbons'.through contact-with a solid- ContactM material 'whichf'fexhibits specieadsorption properties forlnitrogen compounds lin preter'encefto fhydrocarbonsmfthe same." boiling range, gwhichfiprocess lincludesaf-fs'tep 'f'conducted at substantially the `same 'temperature las' the hydrocarbon contact *andg in which fthe v.organic nitrogen compounds arel displaced b'ylandeirchangedV for differentA organic nitrogen'rfcompounds whichsis separable." by` distillation .fromnot'onl'yzthe' displaced nitrogen com- ,Punds butalsol the unadsorbed hydrocarbons. v

' -It fis va more specic object fof this `invention to provide for; hydrocarbon'*denitrogenationithrough contact with a o metallo-alumino silicate adsorbent-'of a specic type to` produce .Va;-;nitrogen'free hydrocarbon, displacement of' the adsorbed nitrogen compounds isothermally by means of 'nitrogen'compounds of diiferent boilingrangegthe distillationu'of the adsorption eliluent' and ofthe ldisplaceand y advantagesfof the presentf invention asthe descrip tion and illustration Avthereofproceed.

Briefly, the present inventionV comprises an improved denitrogenation process for treating hydrocarbon streams derived fromyvirtually any'source Yand which are contaminated with organic nitrogen compounds. The processconsists of apcombination of cyclic contact of 'the' feed stream and a recycled displacement exchangestream 1 with la .granular solid zeolitic metallo alumino silicate contactgrnaterial, more precisely defined Vand described below. Y 'Illeefiluent fluids from these contacts are fractionated-separately'whereby the organic nitrogencompounds are yseparated from the feed streamY and recovered asrafproduct of the processin their .original `form. The

.presentinventiou will be idescribed in connectionfvvith Y Y, j Y, thadatwgwati@ vivareus Shale-Gilirctions whose ates 'and2 other frac-ff o invention-toprovide?an i .ocessifortheidenitrogenation of` -hydroca'rb'onYA nitrogen content is particularly high and which present probably the most diilicult feed streams to denitrogenate completely. The process is equally applicable to the complete denitrogenation of various petroleum andy coal` tar oil hydrocarbon streams containing nitrogenv com; pounds. v

The feed mixture is first passedthroughecontact with a compact bed of the granular solid metallo aluminq silicate which retains the organic nitrogen compounds leaving the hydrocarbon constituents substantially unaffected as an effluent or ranate phase. Instead of heating the spent contact material and attempting to strip it` with a uid such as steam as in then conventional adsorptive fractionation processes, they spent Contact material is then contacted with a recycled displacement exchange stream comprising selected organic nitrogen-compounds whose boiling pointV or boiling range 'is such thatV theyl are readily fractionated as by distillation' from the displaced nitrogen compounds and from the ratinate. During this contact an active displacement exchangetakes`- place in the presence ofzthe contact materialk wherebyv the organic nitrogen compounds present on the contacti material are displaced by andY exchangedfor the re-v cycled organic nitrogen compounds Vwhich are retainedy onl the ,contact material; This displacement exchanger" contact is preferably conducted at :substantially thelsames'; temperature and pressure as thecontactwiththe Yfeed stream. There is 'produced by` this;rdisplacement,,ex-1,:

change ,an extractjor displacement;.exchange elue'ntr streamwhich comprises a mixture vofethe;displaced err-r; ganic nitrogen compounds and part ofthe selected ,disI placementexchange nitrogenycompounds, the'jremainder being retained by the*adsorbent-leavingit saturated with the selected organicqnitrogen compounds which are re-fA cycled in the process. Theextract stream is then fractionated asby distillation to recovertherecycle compoy nent 'from' the organic lnitrogen compounds-displaced..

` fromthe metallo alumino silicate; The material isthenf contacted, repeating-a cyclic` process, with the feedstock -to remove therefromthe organicnitrogen com-'- poundsreferred to above. Duringthis feed contact and continuing-,through the process, a reverse displacement exchangel occurs in whichthe organic nitrogen compounds present in the feedstock-displace and are exchanged Ifor the selected organicv vnitrogen compounds recycled as Ythe displacementexchange stream inV the process and .which is,l present on theY metallo alumino silicate. The raflnatethus vcontainsi the displaced re'- cycled component or components vand is separated there# fromforgrecycle inV the process.`

The recycle stream employed in the process of this'y invention for displacement exchange of the organic nitrogen compounds accumulated from the feedstock on the' metallo alumino silicatemay be a mixture of selected organic nitrogen compounds or a single pure compound f of this type. Further, the selected material ormaterials for recycle may be the same asone which occurs the feedstock or may-be different therefrom. The re circulated material however must have a boiling point or boiling range, or another physical property, relative to that of the feedstock so that it is readily and economically separable from bothv the raffinate and extract streams. in this process both the rafnate and extract streams contain recycled displacement exchange nitrogen compounds, each of these streams is separately frac# tionated, as by distillation preferably, and the displacement exchange components so recovered are recirculated.

This fractionation .producesa substantially nitrogenfree hydrocarbon stream and a substantially hydrocar-' bon-free nitrogen compoundl stream as separate process products. The nitrogen compound stream may be dis-l posed of if necessary, but it constitutes a desirable con-Y centrated stream of organic nitrogen'compounds suitable'f for further purification or as feed materialY to various'v chemical"synthesisfprocessesf well-known to' those" skilled"k 4. in organic chemistry. The nitrogen-free hydrocarbon stream is suitable as feedstock to the various hydrocarbon relining and conversion processes well known to those skilled in those arts and which avoids therefore the catalyst poisoning referred to previously. If the boiling range and chemical constituents of the feed material are properly selected this hydrocarbon stream may constitute` as' such a suitable solvent 'whiclis free of the odor and other problems mentioned.

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 yfor static or moving solids bed Contact. It is used in the form of a dense compact bed of material through which the feed and displacement and exchange recycle streams pass, either in the vapor phase or in the liquid phase. The process may employ the adsorbent in the form of a single static bed of materialin which case the process is only semi-continuous. Preferably a plurality of two or more static beds of adsorbent areemployed with ap-v passes through one or more of' theY other vessels-in the In this case thefeed and product'owsare'continu- Y set; ous, in either thevapor Yor liquid-phase, and either-'sup 'orsd'ownvthrough the solids.1 Whe'nthe granular solidsare suiiicientlyruggedv physicallyfthen the-moving:l solids is .maintained continuously throughiafirst 'contacting orv adsorption zone,V the flow'ofdisplacerrie'ntf'exchangefiluidv isiY maintained continuously th'ough'li a second contacting or displacement exchange'zone; and thegranular adsorbent is recirculated successively-` through*thesetwo zones:`

With the smaller sized meshfranges-#ofadsorbent;` the" material may be uidized inA andV by the uid'strea'rns' contacting it, V althoughv the compactbedmodifications are preferred-since a greater numberi of theoretical and actual contact stages` are more readily-obtainedrjlnsmaller and simpler equipment. ,Y

The present invention `may notV be1 carried outVv withV the commonly availablefsolidV granular adsorbents;v Ithas been found that-particularadsorbents-*which arehiglily f Y eicient andV preferred! in thev hydrocarbon deniti'oge'nation process of thev 'present' invention aretlaenatu'ralY or synthetic zeolitic crystallinepartially dehydrated metallo; alumino silicates. Ihecomposition'fof one"A typical syn- Vthetic zeolite having a pore size of aboutY "13A,` 1s

5Na2O-6Al2O3-15Si02. It may beprepar'edlbyl heating stoichiometric quantities of alumina and silica'andexc'es's' caustic under pressure. The excess is washed out; @therV desired metal ions may then bei introduced by ionA ex'- change; Part of`the sodium in this material can be ion in the `process of thisinvention; the pore'sizefmust'be at" least y7V A. The -metallo. aluminosilicates" having such pore sizes exert preferentialv adsorptiveforces for organic nitrogen compounds in great preference 'to 'the' hydro- Vcarbons of the same boiling range.l

dueto theac'cu'rnulati'oii on themmatrilfoftraces of 1v38; This compriseslightrcokerg present in the feed stream. l Since the .temperature at 2 which the feed contact and the displacement exchange j contact is relatively low, little if vany chemical reaction,"

' ordinarily occurs in contact with thef material. The

accumulated deactivatingmaterialsmay be removed from the metallo alumino silicate by heating" to temperatures" of the order of those customarily 1 jemployed in*v the oxidative regeneration of spent hydrocarbonconversion catalysts and passing a dilute oxygen-containing stream c tions and applications thereof, as well 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:

Figure 1 is a schematic ow diagram of the denitrogenation process of this invention employing a recycled displacement exchange organic nitrogen compound fraction which has a boiling range within the boiling range of the hydrocarbon feed stream to be treated,

Figure 2 illustrates a schematic liow -sheet. of the same process in which the displacementexchange stream has a boilingrange below that of the feed stream, and

vFigure 3 is a schematic flow diagram ofthe process ofV yremoving-it through line '448Mat1 a rate5 controlled by valve Y l 50..l It may be combinedfas desiredwith the oil-free,

invention in which a recirculating'stream; ofthe moving dense solids bed-is shown.r

3 preferred contact material inV `the vformgof. a downwardly purposesrof clarity of illustration; The description of Figure 1 will be conducted yinthe form of a specific example of the process of this inventionvappliedto the denitrogenation of shale oil cokergasoline.4 The material is.l produced lby Yretorting .shale to .yield crude shale oil followed'vby coldng this materialinany .of .the lseveral conventional'wa'ys to produce vla.Coker*distillate, yoffwhichvv the gasoline lfractitmjboiling between about ll20.F.-"and y Y Y cularlyto Figure 1.,V the essen-'Q39V equipment elements offthe processinclude'adsorber cases 10 and" 12. provided 'with' fourwa`y owV control..` valves 14` andr`16 operated .by cycle' ti'meroperator,v 18,* l firs'fand second ,raffinate distillationlcolumns 20 and`22, l

about 400. F. :comprises the-feedstockjinthepresent example. Thenitrogenranalysis `f Ythisrc'orker gasoline is 0.8%by weight. The displacementexchange; stream -em'ployedfjs Y l 240er. y L p 1 y .The VCokergasbline feed is intrtidlrlcfed"throughlin'e'2'8 at a' rate controlled'by valve the :vapor-phase 'at afY .pyridine have a 'positif about temperature'ofaboutF4O3' F.,`.just above'thedew point;

of,` the jfe'edl. Itpassesthrpughrstcontrol valve 14 and f line`32`upwardly through adsorber case r12. lItfcontactsj Ythehsltaticbed ,ofv metallo alumino silicate having pore y dia'nlleters of the order of 10 Alfand in which theorganic nitrogenP compounds are adsprbed. 1nthis particular feedstock there .appears K to fbejfewl nitrogen compounds. with boilingpointsbelowpyridine. The contact material,

A exchange. material.'r p Y Y line 52j and vaporhe'ate 53, Tasses 'through second con# A y y fnwardly through?" 'the'solidrmaterialinicontactingv s l'10.` 'Il'hepurpose of'fheaterfSvisto raise.thegteiri'p;A

ment exchangeavapor if]necessary p omlthlat rof its distillation to approximatelyfthemsam ftenperature as thatat which thefeed contactsthelflOfA metallo alumino silii cate. In f Vadsorber "case, `10

organic vnitrogen, compounds* and of. the displacement exchangepyridine; ,l The pyridine'passes from the bottoni oftr'st columnlnz through line` 40 into second distillation column 22 along` with the heavygasoline boiling above aboutA 240 F. f 'In Vsecond,"'columi 1 22 the p yridine vapor is taken overhead through line 42 fand ythe, nitrogen-free heavy gasoline isj producedrfrom the *bottom thereof through line 44. The 'light and heavy nitrogen-free gasolines may? be produced as 'separate Vstreams in the obvious manner, 'nam'elyfrom the topzof column 20 and the bottom of column 22,*'or ymaybe combined as shown in Figure 1 to produce'affulllrangegasoline which is sent through'line 46y to storage or furtheruproeessing facilities; not shown. The pyridineoverhead from second columnA 22 comprises part vof thedyis'placement exchange stream and this is'returned by means ,subsequently described to treat -the contact material." Since', in this modification pyridine also occurs in the feedstock there is a net' production of pyridine in theprocess which tends to accumul latein the displacement exchange stream. This material may be removed at a ratexequivalent to the rate at which pyridine 1 is fed to the system` in the feed stream' by organic nitrogen compoundsseparated inthe process as described immediatelyljbelow.

Simultaneously withthe aforementioned contact of 'theN feed streamwith the'` 1045i silicate, another-mass of the' from l"that of the; feed strea'mj pas Y g material, withrthef/ Vtream of "..Thisgstr change takes place inwhlcV streamV comprising a mixtuv l Plassd: organic, `ilitrasan. 1.99m Oundstoiv's.

M @and making Nup the "extraer distillati 15p/siepi; The distintition here is entirely. analogous tfthat intheraflinatejdistillationfstep 'ofthe process.'I ".'Ifhcjextract ismdistilledl to remove `roverhead any `organic nitrogen'compounds boilingr'below 240 F. fand.these fmaterials" are removed thregn 'line '60. j The" displacement* exchange pyridine v and' higher Y boiling organic' nitrogen compounds 'are in` troduce'd from the bottom of column'24 throughv line 62V l into Y column 26. The pyridine which boils'about 240 previously treated,v with the pyridine`Y` displacement' ex-v material. now freed of the original organic nitrogen compounds and containing the displaced pyridine, owsthrough line "34 provided with second control valve 1,6 andthrough t line 36 into the rainate distillation equipment. Y

.Thearaiinate distillation equipment consists of irstrand second distillation columns f connectedl to` produce a heartYV cut.. In first, column 20 materials jboiling belowgZiQ F.;

areproducedl overheady as a vaporjwhichows@ through. asoline" free of F. is taken overheadf through line and recirculated through line 64into 'combination with thegpyridine separated from Vthe ratlinate'aspreviously described, which latterl fraction. ows throughflie .66.1 A' The ycombined stream comprises the displaccmentH-exchange recycle l stream introduced 'through line 52 as indicated-above. `V

Optionally the nefproductionof pyridine in the process maybe removed Yfrom the overheady frorncolu'rnn 26.A

through line .68,1at:afratefcontrollediby valve 70. -fIf desired, only a'sufficie'nt 'quantity ofithe pyridineY present.l

in the 'feedto second column 261 lmayfbe taken koverhead so that the total quantity, incombinationwith the `mate Y rial produced overhead from second raflnate distillation column 22 will produce the desired' quantity of pyridine? for displacement exchange.;V Themthe, net;,'pr.QdIIGPQPIrbis.,VL

ith thV pyridine'fisftaken from the system togethe active displacement ex, Y, pyridine accumulates jon the 10"Ay.v-si1icate.inexchangtffor and Qdispl'a'cing thev Y organic-'nitrogen 'compounds'V previously accurnulated.' while v'1t was contractingth through 'l Y through lineA n'y 24 .and 26 higher boilingV organic nitrogen compounds from the bottom of column l260 through line'72.l The v*nitrogen com- A pounds boiling below pyridine owinguthrough line l6tland the Ycompounds boiling above pyridineiand:whichmayfinclude'- some -net productionof` pyridine -flowing through line 72,'may be produced as separatefproduct streams or maybe combined. In rthe latter case thecombinedfree Aorganienitrogen compounds are` produced from the system through line 74 and sent torstorageorf hydrogenated shale oil coker gasoline analyzing 0.222-

weight percent nitrogen ("Kj'eldahl). The displacement exchange stream is pyridine and the denitrogenation gasoline product analyzed less than 0.001 Weight percent nitrogen (Kjeldahl). The denitrogenation eiciency is therefore somewhat above 99.6% Y

Either of the-foregoing processes may be effected with substantially the samel denitrogenation eiciency employ.- ing any of the alkylated pyridines,.such-as-the 2-, 3 and 4-methyl` pyridines boiling respectively at 264 F., 290

Ff, and 289?. vOf course when this substitution is made f appropriate changesin the heart cutting points must be made when .distillng the'eextract and ratinate.

The same', process isrepeatedusingethylene diamine as the exchange strea'mj The13 A. silicate saturated with ethylene diamineiscontacted at atmospheric pressure.

Coker gasoline analyzing 0.961% by Weightnitrogen. The fe'edg'ravity is 47.0 API.. Of 423 volumesof feed introduced', 420 volumes of raffinate including displaced ethylen'e diamine are obtained. This is distilled to heart cut the'ethylene diamine boiling at about 242 F. from the nitrogen-free oil. The silicate saturatedV with nitrogen compounds is then contacted with 71 volumes of ethylene diamine at the same conditions of temperature and pressure to produce -71 volumes of extract. This is also heart ycut to separate the ethylene diamine kfrom the. nitrogen compounds displaced'from the silicate, and the contacts kare continued alternately.4 The-raihnate contains 0.002%A nitrogen by weight.

in the process of'this invention as previously indicated, theprefer'red vcontact material is the' metallo alumino silicate defined above having porediameters of about 13 A. Other similar forms of this silicate are available having smaller pore sizes such as 5 A. material. ThetenacitywithI which vthe 13 A. `-silicat l-adsorb. andgretair.- organic nitrogen` compounds, thevv following.l dataf. are. given. Afmixture of equal volumesfof 95% normal-.f octane having arefractive index of 1.3989. and. otpyridineV` having A refractive` index ofl 1.509 iszpassedin theyapoi.4

phase at a` temperaturevof about 2801 FQ over/the 131A; metallo alumino` silicate. Thev raiiinatey product.has:a. refractiveindexfof1.3992 indicating it is essentially pure-" normalvoctane. TheV raliinate isso completely purified. of pyridine that no odor ofthey latter-compound can be..V detected in the product.

Referring now more particularly to Figure 2,. av somewhat modiedprocess of the present invention is shown-- in which the selected displacement exchange material` employed to remove organic nitrogen compounds from.. the contact material is selectedsoas-to have-aboiling.5^ point orv boiling range which islditferent from thatof the feed material. Inlsuch an instancethe. displacement. exchange material is readily separated as anoverheadpf or as a bottoms product from both the rati'inateand.ex'-y tract` streams. The description of Figure 2 is inthe". form of an ex'ample'ofthe process applied to thedenitrogenation ofa lighty gasoline derived from petroleum.V

- and having, a bilingrange of from' 120 F. to 300 The displacement exchange materialsei'ectedinthis application isl isopfropylamine having a boiling Krangeof...

9i"iam92"y n i In' Figure 2 theV essential components oftheapparatus-" include'adsorber cases 100' and ltlf'providedfwith[foiirn wayV controlvalves 104 'and 1%" operated remotely .by,:. cycle timer` operator 108; era'hna'te' distillation ystill '110,1'.r andextractstillfZI; Again frsimplicityfo'f:illstr tionmost' ofthe conventional Vvalves, pinnp s',`freboilersn denitrogenation 4capacity of this latter contact material is considerably lessthan that ofthe 13 A. material when treating gasoline boiling range hydrocarbons. lowingir data indicate that the capacity is limited to less than 1.5% of thatof the 13 A. materials when denitrogenating gasolines. The same hydrogenated shale oil The fol-.

coker distillate referred to above is contacted with metalloY tially the same as that ofthe feed stream. For pyridine adsorption, the 5 A. material will. adsorb 0;l67 ml'. per. 100 grams wherea'sthekl?, A. material adsorbs 13.3 ml. per 100 grams. Thusvthe 13 A. silicate adsorbent is previded is"displacement" exchange vapor reheater 11'41pro-f' vided for. the'rsarne purpose 'as reh'eater 53' in Figure .1.

The light gasoline" having Fanitiogen'analysis'of O'LlLW by yweiglttt(Kjeldahl) is introduced through line 1I6fat-:f` a rate eontrolled'by valve' 118 and passes upwardly,l in. contact with the 13 A. metallo alumiuosilicate in'ad sorber case 102 in which thenitrogen compounds are exchanged for andf displace the isopropylamine displacev ment' exchange material present on the contact material.Y

l The denitrogenated lightffgasoline together with the di's-A placed isopropylamine'ws' on throughline 1720;V control valve 106, and line. 122"into'ranatefstill- 110'.'` The overhead vapor from'still 110` passing through li'ne 124 consists of the isopropylamine'whose boiling point i'sj "some 30F. below theinitial boiling point ofthe light gas- Ypropylamine vapor at-a temperature -of aboutv 405' Fi:

A displacementexchange takes place in this vesselwhert-i-v by theorganic nitrogen compounds `accumulated duringV f contact ofthe solid materialy with the light' gasoline'in theprevious' stepV of theV cycle, are 'displaced from the" Yadsorbent invexchange with part of the ,isopropylaminein the displacementvexchange recycle stream. The cit-- tract, comprising'amixture of the displaced nitrogen compound'sand the recycle stream, passes through line ferredin the present invention 'since itha's`A substantially."

greater adsorption capacityfor'the organic nitrogen compounds presenti inlthesef'e'ed streamsthan: the 5. A. zeolite.'v

As al furthenexamplefof the' separationof.- nitrogen Ybases from gasoline boiling range materials and of the 128, control valve'104, and lineY 13o intoV extractV still 112.VV In thisV distillation column the isopropylamine-v having aboiling-point of"9l F'. to 92 F; is'taken overheadvthroughline 132 while the higher" boiling'v organic nitrogen compounds originating in the-light gasoline 'feedz and"`ha'vinga boiling range z between'.Y -th'e limits. given:y ahoveffor the: gasoline:feerl'vv arezfrem-oved asta .bottomeir e product through line 134. Anyadditional isopropyl-k essence amine for makeup necessary in the process vintroduced through line 136 controlledv by valve ,13 8.

g The isopropylamine produced overhead fromA stills 110 and 112 is combined in line 140, substantially'at the overhead temperatures of the two columns. material is reheated in heater 114 to about 405 F. and it is used at this temperature for the displacement exchange contact. y

In the foregoing example the isopropylamine maybe substituted with normal propylamine, ethylamine, or methylamine. Methylamine boils at 20 F. and accordingly is suitable for displacement exchange of organic nitrogen compounds occurring in hydrocarbon streams boiling between about 40 F. and 200 F. Monoethylamine boils at about 63 F. and is suitable for displacement exchange of nitrogen compounds contained vin light gasoline boiling between about 80 F. and y250 F. Normal propylamine has a boiling point of 120 F. and is suitable for displacement exchange of nitrogen'compounds in light gasolines boiling between about 140 'F. and 300 F.

As further examples of the application of the progess of this invention as illustrated in Figure 2 above, the following data are given.

- The process of Figure 2 is applied to the denitrogenation of heavy gasoline derived from petroleum, having a boiling range of 300 F. to 400 F., and having a nit'rogencontent of 0.1% by weight. Contacting this kfeed stream in the vapor phase with the 13 A. metallo alumi-Y no silicate produces denitrogenated heavy gasolinehav` ingA a nitrogen content of 0.00 l% by weight; The displacement exchange stream' employed withfthiseed stream, vand with other nitrogencompoundcontaminated hydrocarbon streams boiling between aboutf300 F; and

400 `F."is pyridine. This displacement'exchange ma terial has a normal boiling point ofabout'239 F. and

is Yeasily produced as an'overhead distillate from both'v the denitrogenated heavy gasoline and fromftlefalw kylatedpyridines and similar materials 'separated in admixture therewith as theextract from the process. `In

this application the denitrogenation eniciencyY is about` The process described in connection with Figure 2 is applied to the denitrogenation of the fraction of Coloradoshale oil boiling between about 400 F. and 500 F. The 13 A. metallo alumino silicate is again em.-

' ployed, the contacting temperature for 'both steps of theprocess is about 510 F., 'and 'the displacement exchangemstreamv recycled is 1,1-dimethylhydrazine. rawshaleoil lfraction has va nitrogen content of about togenated shale oil product analyzes 0.002% by weight Y nitrogen. The denitrogenation'eiciency is above 99%.

tlthasbeen found in the application of the process of thisyinvention' to the denitrogenation of hydrocarbon diethylhydrazine, methyl ethylhydrazine, and vthe other" mono ,and dialkylated hydrazines having up to three carbon-'atoms per. alkyl radical maybe substituted as the displacement exchange stream. It has also been found petroleum.oilfractionsgthis is nottoy be construed'as`V a limitation since it is applicableingeneral to any hydroy5() l i7% 'by weight. lThe displacement exchange material has a boiling range of 200 F. to 205 'F., and the dem-' that the aliphaticdiamines such as diaminoethane, .1,2v

and 1,3-diaminopropane Ymay be employed as,thedis` atmosphere inthe/vapor phase with the fractionof shale oil? cokerdistillate normally boiling between 400 Ffand 509 E., "me gravity ofthe feed is 30.2 API @dit hasV The 13 A. silicate saturated Y Ywith'ethylene diamine is contacted at 405` F. and`0.26 Y

ethylene diamine to produce 106.5 volumes of extract. From this is distilled, as bottoms product, 35 volumes of nitrogen oil'having a' gravity of less than ,15 API. The process is continued by repeating Vthese s tepsin alternation. The ethylene diamine so separated from therani ate and extract is recycled in the process as the displace-1 ment exchange stream as indicated previously. A raw shale'oil fraction boiling between ble of displacing'and being displaced by the organic nitrogen compounds in this 500 F. to 600 F. fraction respectively in the displacement exchange and contacting portions of the cycle. A denitrogenated raffinate, freed of the diethylenetriamine by distillation is produced having a nitrogen content of about 0.002% by weight.` YTheY degreeof denitrogenation is 99%.

YThe process of this invention is applied to a heavy gas oil and residual 'fraction of; shale' oil boiling above ,500 "F. The I3 A. metalloalumino silicate adsorbent is employed, the contact. is inthe liquid phase at a temperatureof 525 F., andthe displacement `exchange material' recycled in the Vprocess is triethylenetetrarnine.` This mav terial has a normalboiling range of about 460 F. and in thisf'modiication Aof the-process theidisplacement'exf change is contacted in the vapork phase Vat a'temperaturef: of about 500;F." The feed materialhas a nitrogen contentof aboutV 2.0%, by weight nitrogen and the denitrogenated product contained 0.1% by weight' nitrogen; y

*Although theforegoing examples have servedto illustrate the applicationof this invention to shale oil and carbon mixture vcontaminated with organic nitrogen compounds. In general, the selection of the displacement ein change stream is'determined after a consideration of the boiling range of the feedstock to be denitrogenated. Pri-( marily,the displacement exchange Vstream should have a normalboiling point somewhat below or above the initial boiling point or end point respectively of the hydrocarbon stream to be treated to permit distillation separations 'ofi the extractand rainate streams. At least about 10' F. j

and preferably 25 F. or more is the' preferred dilfereuce. It has been found however that'in rnost cases the preferred V displacement exchange materials have boiling points -below the initial boiling temperature ofthe feedstock. -For feedstocks boiling up to about 300 F. 'the aliphatic primary amines having between about l and .Y

about carbon atoms per molecule are the preferred'dis-Y placement exchange materials. For hydrocarbon ma.

are vthe lower aliphatic diamines and the mono and'disubstitutedk hydrazines whose constituent groups contain from 1 Ato about 3 carbon atoms per group inlthe case of'Y hydrocarbon mixtures boiling in the-range ofifrom about 400 F. to 500-F. Again ethylene diamine can beused.

VFor treatment of hydrocarbon streams Yboiling in the range of from 500 F. to 600 F. the preferred displace'-V ment exchange materials are the aliphatic triamines such as` diethylenetriamine and the line. Formaterialslinclud- Y ing*V the residual Voils boiling. above ,about F.S'tlpg A 500 P. andv 600'F. and having a nitrogen analysis of 2.0% byy weight nitrogen is contacted for about one hour in thev liquid phase with the 13 A. metallo alumino silicate atfa Y temperature of 490 F. The displacement exchange ma-l; terial `employed in this application of the process is di# ethylen'etriamine having a normal boiling point of aboutl 400 F. It is found that this polyamino material is capa- A 11 various tetramines such as triethylenetetramine are preferred ,as the displacement exchange material. Thus for materials boiling above about 500 F., the displacement exchange components are preferably polyamines having up to about 6 carbon atoms per molecule. Because .of the'cyclic reverse Yadsorption steps which `takeplace the process of this invention it is preferredtto fractionate in apreliminary way wide boiling range oils tto'be .dehydrogenated so that fractions boiling approximately between the limits given above can be treated with an adsorbent which in turn is subjected to the displacement exchange step using the preferred displacement exchangey material. Therefore the present invention contemplates such a preliminary fractionation step and the individual treatment of eachfraction according to the principles of the'invention as defined above.

As indicated above, the solid Ygranular contact material used in this denitrogenation process is a zeolitic material comprising a metallo alumino silicate and prepared from natural minerals or synthetically and which has fairly uniformly sized pores of at least 7 A.

Thepreferred 'ow directions for the displacement exchange and the feed streams are indicated in Figures 1 and 2. It has been found that an increased eiciency. of displacement exchange and reverse displacement exchange during the feed contact is obtained when these materials low through the adsorbent bed in the opposite directions. This is not intended to ,exclude the passage o'fthese two streams in theV same direction since thedisplacement exchange still occurs, although` somewhat additional quantities of material are lrequired ,to effectcthe same degree of displacement.

Referring finally to Figure 3, the movingsolids bed modification of the process described inconnection with Figure 2 is shown. In this process adsorption column 150 is provided with a means 152 for removing thesolid contact material from the bottom of column 150 .and

returning it to the top of the same column so asto maintain a downwardly moving dense solids bed in .the column. The nature of thisconveyor depends tosome'extent'upon whether vapor phase or liquid phase contacting is employed within the column but may include bucket elevators, pneumatic solids conveyance such Vas the lwell known gas lift suspension system, the conveyance of these solids as a slow moving dense packedmass, .and others.VV Adsorption column 150 is provided at successively lower levels with first seal gas disengaging zone 154, raiiinate disengaging zone 156, contacting zone 158, feed engaging zone 160, sealing zone 162 including second seal gas disengaging zone 164, extract disengaging zone 166, displacement exchange zone 168, and displacement exchange recycle engaging zone 170. A 13 A. metallo alumino silicate contact material passes downwardly .as a moving bed through these zones in succession.

'The feed stream to be denitrogenated is introduced through line 172 at a rate controlled by valve 174 into engaging zone 168, passes upwardly countercurrent'to the descending solids bed in zone 15,8, and substantially all of the denitrogenated feed stream is removed from zone 156. The raffinate passes through line 176 into raliinate still 178 in which the lower boiling displacement exchange component is taken as an overhead product Yby meansV of line 180. product is produced through line 182 y'as a bottoms projduct.

A small amount of the rainate is allowed torpass upwardly countercurrent to the solids toward first seal gas disenga'ging zone 154; this produces an impure mixture ofthe raflinate together with materials which inevitably arereintroduced'into the system with the recycled solids. Most often this is the fluid which last contacts the solids at the bottom of the column, namely the .displacement exchange recycle stream. Removal of the said 4mixture fomlzone 154 by means of line 184 and pump 186 prevents contamination of theranate andiloss o'f'ran- The denitrogenated hydrocarbon rer 12 ate from the top of the column. This material is re. circulated through line 188 and combined withthetfeed. The nitrogen compound saturated contact material passes downwardly through sealing zone 162 from which* a sealfstream isremoved consisting'of a mixture of .the feed stream introduced `into zone andy the extract stream removed from zone 166. This material is also recycled to `thefeed stream by meansof pump-190.

The contact material is next contacted with the displacement exchange recycle stream in zone 168 to produce the extract comprising .the displacement exchangel component andthe displaced organic nitrogen compounds fromthe adsorbent. The extract ows through line192,v

The processof this invention thus consists of anim-l proveddenitrogenation process for contaminatedhydr carbon mixtures employing the principles of solid adsorption and liuid fractionation in suchaeway so vas tov remove Vorganic `nitrogen compounds from the feed stream and whereby the `ordinary heating and gasstripping orliquid washingsteps customary in -prior adsorptionprocesseshave been completely eliminated. The process of this invention `may be operated under pressure or under vacuum, and the actual operating pressures: are actually determined by the pressure at which the feed,

stream is available and its vboiling range, `and whether the materialbeing contacted Vis desirably in the vapor phase The proper operating pressure can be Vdetermined by those skilled in the art from .knowni or the liquid phase.

physical characteristics of the materials to be separated; namely the bubble point and dew point of complex hydrocarbon mixtures and the known way in which'thesc change with pressure. The operating temperatures employed in the process of thisinvention are also determined by thev physical characteristics of the feed stream land the operating pressure and also whether a vapor phase or af liquid phase contact is desired. n In theV complex gasoline streams the operating temperature is largely determined by the dew point and the bubble point of the stream at a given operating pressure. For example, contacting temperatures above the dew point will obviously be in the vapor phase while operating temperatures below the bubble point will be in the liquid phase. It is within the contemplation of the present invention to treat the lfeed stream at a temperature between its bubble point and its dew point so that mixed phase contacting will be maintained for some special streams. Obviously the Vfeed contact may be in the vapor phase followed by recycle stream contact in the liquid phase, or vice versa, `if desired.

A particular embodiment of the present invention has been hereinabove described in considerable detail by way of illustration. It should be understood that various other modications and adaptations thereo'fmay be made'by those skilled in this particular art without departing-from the'spirit and scope of this invention as set forthY in the carbon mixtureY containing normallyV incidentV organic nitrogen compoundcontaminants vwhich comprises: .(15).

contactingsaid mixture with a lean granular solid ad;

sorbent essentially comprising a partially `dehydrated.- V

Yzctilitic metallo alumino silicate having substantially uni- 13 form pores between about 7 A. and about 13 A. in diameter and having adsorbed thereon a displacement exchange medium essentially vcomprising an organic fnitrogen base, whereby there is formed a rich adsorbent essentially comprising said silicate having adsorbed thereon the organic nitrogen components of said mixture and a raffinate product comprising non-adsorbed 'hydrocarbon components of said mixture and desorbed displacement exchange medium; (2)separating said raflinate product `from said rich adsorbent; (3) contacting said richadsorbent with said displacement exchange medium, whereby said adsorbent is returned to the aforesaid lean state and there is obtained an extract product comprising desorbed organic nitrogen components of said mixture and said displacement exchange medium; (4) separating said extract product from said lean adsorbent; (5) returning the lean adsorbent to step :(1); (6) separately treating lsaid separated ralnate and extract products to separate n 14 change medium essentially comprising an organic base which is separable from said hydrocarbon mixture by distillation, whereby there is formed a rich adsorbent v essentially comprising said silicate having adsorbed thereon the organic nitrogen base components of said hydrocarbon mixture anda rainate product comprising nonadsorbed hydrocarbon` components of said hydrocarbon mixture and desorbed displacement exchange medium; (w27) separating said rainate product from said rich adsorbent;

(3) contacting said rich adsorbent with said displacement exchange medium, whereby said adsorbent is returned -to the aforesaid lean state and there is obtained an extract product comprising desorbed organic nitrogen Vbase components of said hydrocarbon mixture andV said displacement exchange medium; (4) separating said extract product from said lean adsorbent; (5) returning the lean adsorbent to step (1); (6) separately distilling the separated Y raffinate and extract products to separate said displacethe displacement exchangeY medium therefrom; and (7) returning separated displacement exchange medium to step (3'). e 4 v 2.'A process according to claim l whereinsaid displacement exchange medium has a boiling Vpoint such that it is readily distilled from said Ia'inate and said extract products.

' 3. A process according to claim 2 wherein the boiling point of said displacement exchange medium is within the boiling Yrange of'said mixture' and is separated from the extract and the raffinate pnoducts Abyn'n'earis 'oa 4. A process according toclaim 1 in combination with heart-cutting distillation.

the step of periodically raising Vthe" temperaturezof'said metallo alumino silicate and contacting it `Withfagas con aceous materials therefrom. Y l 5. A process according to claim V1 `in combinationwith taining .oxygen thereby burninggffresidualhydrocarhonf the4 steps of owing the hydrocarbon `mixtureincontact with said silicate in a directionV opposite to that` at which the displacement exchange medium is passed iny contact therewith.`

ment exchange medium therefromyand (7) returning Vseparated displacement exchange medium to step (3).

9. A process according to claim 8 wherein said metallo alumino silicate has a pore size of about 10 A. in diameter. V10. A process according to claim 8 wherein said metallo alumino silicate has a composition corresponding substantially to 5Na2O6Al2O315SiO2, and has a pore size of about 13 A. in diameter. e

` 11. A process accordingv to claim 8 wherein said hydrocarbon mixture comprises a light gasoline fraction boiling belowabout'300 F., andf.wherein said displacement ex- 6. A process according to claim lwherein said hydro# carbon mixture and said displacement exchange mediumV are passed` alternately through at least two contacting zones each containing a static bed of said metallo alumino silicate. p v

7. A process according to claim 1 in combination with the step of recirculating said metalloalumino silicate successively through a contacting zone in contact with said hydrocarbon mixture and then throughy a displacement.

exchange zone in contact with they recycledstream of said displacement exchange medium. v Y

8. The cyclic process for denitrogenating `a normally liquid hydrocarbon mixture containing normally incident" organic nitrogen base contaminants which comprises: (1)7' contacting said mixture with a lean granular solid ad-V sorbent essentially comprising a lpartially dehydrated zeolitic metallo alumino silicate having substantially 'iuniform pores between about :7l A. and about 13.A.`fin diameter and having adsorbed thereon adisplacement exchangemedium isa primary alkylamine'containing from "12. `A processlaccordingto'claim 8"whereinr said hydromedium isan alkyl hyd'razine containing from 1 to 2.a1ky1 groups each containing from 1 to 3 carbon atoms.

14. A Vprocess. according to claim 8 wherein said hydro- A carbon mixture boils above about 500 F. and whereinY Y said displacement exchange medium comprises a polyethylenezpolyamine containingvfrom to 4 amino groups.

15. A` process according to claim 8 wherein said hydrocarbon mixture has a boiling range between about 400 F. and about 500 F., and said displacement exchange medium'is a diamino-alkane containing from 2 to 3 carbon atoms and havingthe. amino groups attached to diiferent carbon atoms. v Y

References Cited in the le of this patentA UNITED STATES PATENTS i nitrogen

Claims (1)

1. THE CYCLIC PROCESS FOR DENITROGENATING A HYDROCARBON MIXTURE CONTAINING NORMALLY INCIDENT ORGNAIC NITROGEN COMPOUND CONTAMINANTS WHICH COMPRISES: (1) CONTACTING SAID MIXTURE WITH A LEAN GRANULAR SOLID ADSORBENT ESSENTIALLY COMPRISING A PARTIALLY DEHYDRATED ZEOLITIC METALLO ALUMINO SILICATE HAVING SUBSTANTIALLY UNIFORM PORES BETWEEN AND 7 A. AND ABOUT 13 A. IN DIAMETER AND HAVING ADSORBED THEREON A DISPLACEMENT EXCHANGE MEDIUM ESSENTIALLY COMPRISING AN ORGANIC NITROGEN BASE, WHEREBY THERE IS FORMED A RICH ADSORBENT ESSENTIALLY COMPRISING SAID SILICATE HAVING ADSORBED THEREON THE ORGANIC NITROGEN COMPONENTS OF SAID MIXTURE AND A RAFFINATE PRODUCT COMPRISING NON-ADSORBED HYDROCARBON COMPONENTS OF SAID MIXTURE AND DESORBED DISPLACEMENT EXCHANGE MEDIUM, (2) SEPARATING SAID RAFFINATE PRODUCT FROM SAID RICH ADSORBENT, (3) CONTACTING SAID RICH ADSORBENT WITH SAID DISPLACEMENT EXCHANGE MEDIUM, WHEREBY SAID ADSORBENT IS RETURNED TO THE AFORESAID LEAN STATE AND THERE IS OBTAINED AN EXTRACT PRODUCT COMPRISING DESORBED ORGANIC NITROGEN COMPONENTS OF SAID MIXTURE AND SAID DISPLACEMENT EXCHANGE MEDIUM, (4) SEPARATING SAID EXTREACT PRODUCT FROM SAID LEAN ADSORBENT, (5) RETURNING THE LEAN ADSORBENT TO STEP (1), (6) SEPARATELY TREATING SAID SEPARATED RAFFINATE AND EXTRACT PRODUCTS TO SEPARATE THE DISPLACEMENT EXCHANGE MEDIUM THEREFROM, AND (7) RETURNING SEPARATED DISPLACEMENT EXCHANGE MEDIUM TO STEP (3).

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