US2925380A - Separation of organic nitrogen compounds from admixture with hydrocarbons - Google Patents

Description

Feb. 16, 1960 SEPARATION OF ORGANIC NITROGEN COMPOUNDS FROM Filed Nov. 26, 1956 R. N. FLECK ETAL 2,925,380

ADMIXTURE WITH HYDROCARBONS 2 Sheets-Sheet l 477dl/ViK Feb. 16, 1960 FLECK EI'AL 7 2,925,380 I I SEPARATION OF ORGANIC NITROGEN COMPOUNDS FROM I ADMIXTURE WITH HYDRQCARBONS Filed Nov. 26, 1956 2 Sheets-Sheet 2 .5126- 4. I y zzzyzz-l wa-x/r,

2 ,925,380 SEPARATION or oRGANic mnwcrn' ycoM- rouigms FROM'ADMIXTUREiWITH'HYDROCAR- 'BON I I "droc arbon feed-stocks in refining processes and ifromthe I products produced- 'For example, acid treating with dilute Raymond N. Fleck, whi t' tierii and Carlyle G. Wight,

Fullerton, Calif.,"ass ignors to Union Oil Company of California, Los Angeles,TCalif., a corporation of California o I Application November 26, 1956, Serial :No. 624,238

17Clainis. (C1. 208%154) 1 This invention relates to the r efi'ningof hydrocarbons,

particularly those contaminated with organic nitrogen compounds. Such hydrocarbons include those which are produced as petroleum, such as 'coal tar oil fractions and shale oils among others. 7 1 d Y 3' Many crude petroleum streams iajre found to con t'a in in addition to the principal hydrocarbon constituen tsTcon- -siderable quantities of organic nitrogen omponnds. In some cases the incidence of these nitrogen c'ornpounds is sufficient that the nitrogen content r unsas by weight. California crude oils in cases average 0.5 byweight of nitrogen. MeXic an' and Venezuelan crudes have nitrogen contents about 0.2%

to about 0.35% by weight. Extensive analyses of these.

sulfuric acidforms water solublesaltswith the basic nitrogen compounds, i.e. the nitrogenbases, or the amines.

It-is other-wise ineffective, with respect to the nonbasic nitrogen compounds; Catalytic hydrogenation is effective 'to remove ,most all of the nitrogen compounds, but, in

order to reduce their incidenee inithe hydrogenateud prod- .uct to a level which does not -adversely ette'cta'platinutn catalyzed reformingprocess (for gasoline,v hydrogenation pressures of the order of 5,000 psi. and higher; are re-' quired. Treatmentpf such-materials with fullers earth e o educ tha ant y p nitrp en ssamp nds-rbut thisinvolves a relatively high liquidyieldploss through retention: of hydrocarbons onqtheadsorbent and fthe n n F II PQU ld a e s through; d p a 9 f athe spent adsorbent. Furthenflit is seldomvifever possible in this' wayto reduce the"nitroge n; contamination suifi- :ciently to avoid platinum catalyst poisoning-p The present invention is directedito, a highly etiicient and improved process for 'remoyingf-all, and recovering mostof the basic and'nonbasicnitrogen compounds from petrolenm, coal tar, 'andshale'oil crudes,*dis tillatesvand 3 La er a qns, i M

-It'is -';a primary lobj ect of this inyention toproyide an improved process for the denitrogen'ation of hydro nitrogen-containing crudes indicate that much of thenitro I gen occurs in the form of aminesor the so -calle d'hitro-- gen bases. These include pyridine, quinolirie, and the .inono, di, tri, and tetra alkylated .derivativesofthese materials. For example California kerosenefldistillate the di, tri, and tetra alkylated quinolin'es and. certain: polyalkylated pyridines are .found. There is however considerable nonbasic nitrogen present in these materials; Coal tar oils produced in the coking of coal contain extensive quantities of nitrogen bases and "these are principally aromatic amines and heterocyclic nitrogen compounds. Shale oil produced by the heating'aridfrtorting of shale rock, such as that which is found in Colorado of organic nitrogen compounds that the nitrogen content runs as high as about 2.5 %by weight. o v o 7 Crude petroleum, coal tar ,oils,[aiid shale "oils are principal or potential sources of liquid fuels and solvents.

The presence of nitrogen compounds intheffuel or Solvent product imparts a very bad odor'to these materials. Their presence in the original oil very adverselyaffects 1 hydrocarbon refining techniques by which the fuels" and solvents or other materials are produced. They have-for example, a Well defined adverse effect onsuch processes as catalytic cracking, catalytic isomerization,and catalytic reforming, particularly Kplatinu'm catalyzed reforming.

The nitrogen compounds appear toj'lpe adsorbedon'the.

catalyst .and selectively deactivate its "active cracking carbons whichare contaminated with organic nitrogen ra r d' It is a more specific objectof .this invention to process f hydrocarbon streams contaminated with organic nitrogen compounds by distilling the feed to produce a plu- 'e tvf i f ac ion nt t a a pe s li contact aterial with the feed fractions ill a sequence Qto; produce i r n q n s, o i in P e e b v 1. wl ed Y' th. n tr e mpbu r m. a re edf a an, and distilling each etfluent' to separate the nitrogen comand elsewhere, resembles warty crude but characterized I particularly in that it contains such extensive quantities.

pounds from the.hydrocarbons of difierent boiling range.

I It is 'a specific object toprovide 'a process according to the foregoing object in whichthe feed isdistilled into two portions which alternately contact the contact ma- It'is a furtherobjectjto providelin such alprocess for distilling thefeedfraction into a plurality of more than two fractions, and in which thesolid contact material is contacted with these'fractionsin a sequence of increasing average boiling point. I I

provide in such 'a .process for It is another object. to

. thedi stil lation of such feed streams intoa plurality of fractions and-contacting the even numbered fractions with :one massjof contact material while contacting the odd numbere'difractions with a-separate'mass of contact ma- 'terial, each of the contacts being in a sequence ot'increasingaverage boiling point. by y I V M It is also ;an object to include in the foregoing process 7 7 the l s tep of regenerating the contact material and ;freeing it of heavy. organie nitrogen compounds bycombustion centers. In catalytic cracking, for example," the gasoline yield may be reduced as much as 50% throughthe presence of sufiicientorganic nitrogen compounds to give the feed a nitrogen content of about 0.3% by weight and reduced by 75% when the nitrogen content reaches about 0.45%. Platinum catalyzed reforming and other reforming processes in general are also advers'ely'efiected by nitrogen compounds in the feed. With halide promoted platinum catalysts the nitrogen 'corn'pourids appear to react with the catalyst forming ammonium halides which deposit in the apparatus. This 'deactivates the catalyst and lowers the yield unless the halideiisreplenishedconadverse e'fiects, repeated attempts have,

tinousuly. Because of the been'made'tb rentereins nitrb encampounds frdnihy l g a granular solid contact fa specific order. ,refractionation are muchmore readily freed of 'th''iorthereof in {the presence. of an oxygen-containing gas," Otherobjects and advantages of thepresent invention will become apparent to thoseskilled in-the art as the description and illustration thereof proceed. H

afieflythe'present inven' ian comprises an improved denitrogenation process for treating one or. more hydro carbon streams derived from virtually any saure and whreh'arefcontainiriated with 1 organic nitrogen compounds. fI-he process consists offa combination of frac-, .ItiOriation andsolids-fluidcontact steps. In the latter step material is'contacted in sequence th a 1 1 trogenate.

- are substantially unadsorbed. spent contact material and stripping it with a fluid such as steam or other material, the spent solids in this process ganic nitrogen-compounds present therein. The granular solid contacting step employs a solid zeolitic metallo alumino silicate contact material, more precisely defined and described below, which has an extremely high affinity 1 for nitrogen compounds of the type occurring in hydrocarbon streams. In combination with this contacting step the process utilizes a plurality of individual hydrocarbon streams or a perliminary fractionation step in which a single wide boiling range feed stream is divided into a plurality of fractions of relatively narrow boiling range. These individual streams are passed through contactfwith the solid material in a sequence. The individual effiuents from the solid contact step are again fractionated to separate nitrogen compounds originating in one of the feed streams from hydrocarbons originating in anotherof the feed streams, which fraction had a different average boiling point oris otherwise readily separable from the first stream. :The nitrogen compounds after treatment with the solid material are thus readily dlstillablefrom the hydrocarbons present in that particular efiiuent.

The present invention will be described in connection with the denitrogenation of various petroleum and shale oil fractions. In the case of the shale oil fractions, the nitrogen analysis is ordinarily very high and they present some of the most difficult hydrocarbon streams to deni- The process is however also applicable to other hydrocarbon streams similarly contaminated including those derived from petroleum, coal and other are next contacted with the higher boiling feed fraction.

-The nitrogen compounds present therein efiect an extremely active and rapid displacement exchange with the lower boiling nitrogen compounds on the spent solid material and which originated in the lower boiling feed fraction. The higher boiling organic nitrogen compounds thus accumulate on the solids while the lower boiling nitrogen compounds are liberated in the displace- This second efiiuent stream comprises ment exchange. the higher boiling hydrocarbons in admixture with the displaced lower boiling nitrogen compounds. These are readily distillable in most cases from one another.

The thus treated contact material, now saturated with the higher boiling organic nitrogen compounds, is again contacted at approximately the same temperature with the lower boiling fractions of the feed stream. A reverse displacement exchange is effected in which the lower boiling nitrogen compounds displace the higher boiling nitrogen compounds present on the solids. This produces a first efiiuent stream comprising the lower boiling hydrocarbons, which are unaffected by the solids, and the higher boiling nitrogen compounds displaced from the solids. This efliuent is also readily distillable to separate the lower boiling from the higher boiling materials.

The aforementioned, distillations are effected separately and each produces anoverhead and a bottoms product.

In the case of the first efiluent stream the overhead product comprises the lower boiling hydrocarbons substantially free of nitrogen compounds while the bottoms fraction comprises the high boiling nitrogen compounds substantially free of hydrocarbons. In the distillation of the second .efiluent stream, the overhead product comprises the lower boiling nitrogen compounds and the bottoms product comprises the higher boiling hydrocarbons.

' placement and exchange recycle streams pass, either in It is within the contemplation of this invention as applied to fairly wide boiling range feedstocks to subdivide the feed material into a plurality of more than two fractions and to contact fractions the specific granular solid contact material herein preferred in a sequence whereby similar displacement exchange phenomena occur to produce a plurality of effluents which are distilled as previously indicated. The sequence preferred is that of increasing average boiling point. If desired, the solid contact material may be regenerated by oxidation after the contact with the highest boiling feed fraction in order that the heaviest and most ditficultly removable nitrogen compounds may be removed. Such a regeneration is also applicable to the process in which only two feed fractions are employed in order to regenerate the granular solids periodically. Even in the case of a relatively narrow boiling range feed material, particularly one which has a relatively high average boiling point, a single contact with the preferred solids to remove the nitrogen compounds from the hydrocarbons is effectively followed by a regeneration with an oxygen-containing gas to burn oif the nitrogen compounds.

The contact material employed in the process of this invention is a solid granular adsorbent having a mesh size range between about 2 and mesh or finer and preferably between about 4 and about 30 mesh in static and moving bed contacts. It is used in the form of a dense compact bed of material through which the feed and disthe vapor phase or in the liquid phase. The process may employ 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 are employed with appropriate remotely operable valving so that the feed stream is passed through one or more of the adsorbers in a set while the exchange displacement stream passes through one or more of the other adsorbers in the set. In this case the feed and product flows are continuous, in either the vapor or liquid phase, and either up or down through the adsorbent. When the granular material is sufficiently rugged physically the moving solids bed-modification may be employed in which flow of feed is maintained continuously through an adsorption zone, the flow of displacement exchange fluid is maintained continuously through a desorption zone, and the granular adsorbent is recirculated successively through these two zones. With the smaller sized mesh ranges of adsorbent, the material may be fluidized in and by the fluid streams contacting it, although 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 most of the commonly available solid granular adsorbents. It has been found that the particular solid materials Which are more efiicient the hydrocarbon denitrogenation process of the present invention are the natural or synthetic crystalline partially dehydrated metallo alumino silicates. These materials must have pore sizes exceeding a minimum of 7 A. in diameter in order for the nitrogen compounds to be preferentially separated from the hydrocarbons. The average composition of one typical synthetic zeolite having a pore size of about 13 A. is 5Na O-6Al O -15SiO It may be prepared by heating stoichiometric quantities'of alumina and silica and excess caustic under pressure. The excess is washed out and if desired 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 l50-300 C. to introduce other metal ions.

The synthetic crystalline partially dehydrated metallo alumino silicate zeolitic adsorbents are presently available items of commerce marketedby Linde Air Products Comthereby displacing the lower boiling nitrogen compounds previously accumulated, and a second efliuent is produced consisting of the 300 F. to 400 F. boiling range hydrocarbons and the 120 F. to- 300 F. boiling range nitrogen compounds displaced from the adsorbent.

second efliuent flows on through line 46, valve 18, and line 48 into second effluent still 24. The overhead prod- .uct produced through line 50 from this still comprises the 120 F. to 300 F. boiling range nitrogen compounds and the bottoms product produced through line 52 comprises the 300 F. to 400 F. boiling range hydrocar ,bons. In Figure l the two streams flowing through lines 42 and 50 and containing the lightand heavy nitrogen compounds are shown as being combined to produce a single nitrogen compound rich stream flowing through line 54 to production or storage facilities not shown. If desired however, these two streams may be produced separately. The same is true of the combined hydrocarbon streams shown produced through line 56.

In the process of the foregoing example, the contacting temperature employed in zones 12 and 14 is vabout 410 F. so that each stream is in the vapor phase. With wider boiling range materials such as those boiling between about 600 F. to 700 F. and higher, this constant adsorption temperature characterizing the process of this invention may be effected at temperatures below the normal boiling point of the highest fractions by passing these streams at reduced pressures in contact with the adsorbent. For example, a wide boiling range shale oil coker distillate boiling between about 120 F. and 600 F. is readily processed according to the process of this invention-at about 403 F. The feed stream is distilled into three fractions. The first fraction boils between about 120 F. and 400 F. and is contacted with a 13 A. adsorbent at 403 F. in the vapor phase under normal atmospheric pressure. The second fraction boils between about 400 F. and 500 F. and is contacted in the vapor phase at the same temperature at an absolute pressure of 0.285 atmosphere. The third fraction boiling between about 500 F. and 600 F. is contacted at this same temperature at a pressure of 0.047 atmosphere.

Referring now more particularly to Figure 2, a modificationof the process shown in Figure 1 is illustrated employing the same feed still 10, first effluent still 22, second eflluent still 24, but in which the static beds of 13 A. adsorbent employed in vessels 12 and 14 have been replaced with a recirculated downwardly moving bed of the same material maintained incontacting column 60. The feed stream is again introduced'through line 26 and valve 28 into feed still which produces a light overhead distillate fraction through line 30 and a heavier bottoms product through line 32. The first effluent is again passed through line 38 into first efliuent still 22 and produces the light hydrocarbon fraction through line 40 and heavy nitrogen compounds through line 42. 1 The second efiluent stream' is again passed through line 48 into second effluent still 24 which produces the light nitrogen compounds as an overhead product through line 50 and the heavy hydrocarbons as a bottoms product through line 52.

The modification here lies in contacting column 60- in which the 13 A. granular solid adsorbent is recirculated through column 60 by means of any form of suitable conveyor 62. The solid material is introduced at the top of the column 60, and is removed from the bottom of the column after passing downwardly successively through first seal stream disengaging zone 64, first eflluent disengaging zone 66, first contacting zone 68, first light feed engaging zone 70, second sealing zone 72 including second sealing gas engaging zone 74, secondefiuentdisengaging zone 76, second contacting zone 78 and second feed fraction engaging zone 80. r s

g The first feed fraction flows through line 30 upwardly through first contacting zone 68 in which the light nitrogen compounds are retained by and the heavynitrogen This compounds are displaced from the 13 A. adsorbent into admixture with the unaffected light hydrocarbons to produce the first effluent flowing through line 38. The solids now saturated with light nitrogen compounds move downwardly into and through second contacting zone 78. Here they are contacted by the heavy or second feed fraction. The heavy nitrogen compounds preferentially displace and are exchanged for the light nitrogen compounds, thereby-producing the second eflluent comprising a mixture of the heavy hydrocarbons unaffected by the solids and the displaced light nitrogen compounds. These two streams are distilled individually as in the process illustrated in Figure l. The solid adsorbent removed from the bottom of the column is saturated with heavy nitrogen compounds. Such saturated adsorbent is .deliveredinto first contacting zone 68 inwhich the'heavy nitrogen compounds are displaced in exchange for the light nitrogen compounds in the first or light feed fraction. 1

In order to prevent contamination of the first and second effluent streams, a first seal stream is removed from disengaging zone 64 and pumped by means 82 through line 84 and valve 86 into first feed fraction engaging zone 70. Similarly a second seal stream is pumped by means 88 from second disengaging zone 74 through line 90 into this same engaging zone.

Referring now more particularly to Figure 3, a somewhat more complex modification of the present invention is shown in which a relatively wide boiling range feed stream of hydrocarbons contaminated with organic nitrogen compounds is introduced through line at a rate controlled by valve 102 into feed still 104. Herein the wide boiling range hydrocarbons are distilled into a plurality of four fractions. The first and lowest boiling rangefraction is produced as an overhead distillate through line 106. The second or next higher boiling fraction is passed through line 103 into first side stripper in which components desired in the overhead fraction are stripped therefrom and returned in the vapor phase to column 104 through line 112. The thus stripped next heavier feed fraction is removed from-stripper 112 through line 114. The third or next to the highest boiling feed fraction is prepared from a stream flowing through line 116 from column 106 into second side stripper 118. Here components desired in the, third feed fraction are freed from components desired in the fourth or highest boiling feed fractionin second side stripper 118. The heaviest components so separated are returned to column 106 through line 120 while the third feed fraction is produced through line 122. The fourth feed fraction is removed from the bottom of still 106 through line 124.

These four feed fractions may, if desired, be processed in the manner of Figure 1 modified to the extent that four static solids contacting vessels are provided through each of which the four feed streams are passed in a sequence of increasingaverage boiling point. After contact of each 13 A. adsorbent bed with the fourth feed fraction, the heaviest nitrogen compounds retained are burned off through contact with an oxygen-containing gas at temperatures of the order of 700 F. to 1200 F.

In the modification shown'in Figure 3 however, this same sequence of solids-feed fraction contact is effected employing a single contacting vessel through whichthe 11.3 A. adsorbent is recirculated and passed downwardly as amoving bed. Contacting column 126 is provided with solids conveyor 127 which removes the granular adsorbent from the bottom of the column and reintr o duces it at the top. The column is provided at successively lower levels with first contacting zone 128, second contacting zone130, third contacting zone 132, fourth contacting zone 140, and solids regeneration zone 142. Through regeneration zone 142 is recirculated a gas stream comprising essentially flue gas by means of blower144... Thisgas is passed through cooler, 146 ,to

- ingj-gassuchasair introduced through line 150. ,The net: production of line gas is vented through line 152. g

' -zi':The.-first feed fraction passes upwardly couritercurrent up areas-mo of regenerationwand sis 115- 7 phase; Ethe "seal fluid isfapp'ropriat'ely a liquidfwhich i 's' alsoyinertand-gwhich is readily separable from the,

to the downwardly moving regenerated ,solidsain first contactingzone 128. The,..lightest or first fraction nitrofsecond" feed fraction passes upwardly through second contacting zone 130.: The secondffiraction nitro- .gcn compounds are adsorbed displacingthe first fraction-nitrogen compounds into admixture'withlthezsecond fraction hydrocarbons forming the secondefiluent stream in: second effiuent still. 158 to producethezfirst fraction nitrogen compounds through line .160 as an :overhead distillate and the second fraction hydrocarbons as 'abot- ,toms'product through line 162. 1 The"third-= feedf fraction introduced through line 122 passes.'upwardly'jcountercurrent;to .the moving solids bedzin thirdzonelSZ. The third fraction nitogren com pounds in this fraction displacethe" second fraction .nitrosecond feedfraction. This eflluent is produced through line; 162 and is introduced into ,third efiluent still '164.

The. second fractionnitrogen. compounds are produced as .genl compounds are ads-orbedleaving the firstfra'ction' hydrocarbons This stream is produced substantially nitrogen-free as a first effiuent-stream-through line 154;

thessuperiaeent:'and siibjacent zones between which lit I introduced? 'Whenthe' contact'is' conducted in the liquid 1', The spent granular adsorbent flowing from the bottom I ofcfourthzcontactingzone 1'40 passes into solids regene'r "atiori" zone .l 42 wherein the heaviest nitrogen compounds areiburne'dl-from .the solid material. The regenerated solid's rarez retumed. as described for repassage through column 126. With.;a feed'rnaterial comprising a shale j oil coker distillate analyzing about 0.22% by weight niremoved through line 156. This material; is distilled-1 I ingzadsorbent comprises themetallo alumino" silicate having 13 A. pores. The first effiuentproduced directly from: i the top of column: 126 comprises a light gasolineanattogen boilingbetween-about 120 F. and 500 R, the four .-feed'sfractions have boiling ranges respectively of .mmuzor Filo 250 F.,2'50 ,F. to 325 F., 325 F. to

40min, 'andi'400rF. to 500 F. The downwardly mow lyzingiflabout 0.002% nitrogen. The bottoms product's 'from-eachoftheithree'eflluent distillation columns comprise-1 the successively higher hydrocarbon con'stituentsof,

, the; feed fractions and these analyze respectively 0.004;

0.'005 and'0;007 nitrogen.

:If .des'ired,-'ia-.10..A. adsorbent can be substituted for j. the 13. xAgused inttheabovecxample. In certain cases itisfdes'irableto'enhance the difierence between the boiling range of-EthenitrOg en compounds derived from one ain't-overhead fraction therefrom through: lirie 166, and

as:-a.-.-bottoms product-.through'line-168.. 1

the-third fraction hydrocarbon constituents. are produced .,=-:Thei' heaviest or fourth. feed fraction: introduce throughline124:passes upwardly countercurrent to the downwardlymo'ving' solids; bed" in :fourth. contacting 'zone-a140.-- The nitrogen compounds. from -the fourth feed .ifraction: arerretained :by the. adsorbent and reflective ly displace the' nitrogenwcdmpounds' therefrom-which originated?- in.-.the' ;thir'd feed: fraction. :uThe: fourth efilu ent fiowing'ythrough linezl70icornprises thehydrocarbons lfrom thexfourth feed. fraction in sadinixture :with the nitrogen compounds froin the third'feed fraction: This ,r'naterriabis-distilled in :fourth etfluentrstill 172- producing thentl iirdr feed: fraction: nitrogen. compounds as an over head-ndistillate" through line. 174"and. :the" fourth feed line v v the 'foun individual hydrocarbon fractions .may 'be produced separately if desired. They may be ccombined as indieatedrin-Figure: 3 infwhich ease =thefnitrogen corn-T pounds zfrom-iall zhutsthe fourthsfeedr'fraction are? sent 140; bCIWCGIl' the individual contactingjzones in column ffraction-hydrocarbons as a bottoms. t'p'rloduct through" feed fraction and the boiling range .of thehydrocarbon stream. in WhiCh these materials are mixed when they arerrecovered .fromithei solid contact material; For ex I ain'ple, .in the'proess ofFigure 3; the nitrogen compounds 'whoselboilingi points lie betweenl20 FJand 250 F. are pr'odu'ced;.in*the'second 'efliuent' with hydrocarbons boil ingtbetween' 2509B: and'325 -F. In some cases nitrogen "compounds".boilingslightly belovv250 F. are diflicultly separable-from hydrocarbons boiling @slightly above 250 R Thiszproblem depends upon'th'eiincidenceof various typesxiofj-nitrogen "compounds and .theirnormal boiling points; -When *such distillation..problems occur, it is de-' .sirable,to 'provide a *gap or substantial difference between boiling-ranges of fractions contacting the solids'in SH CCESSlOH'EEIIdTthB'PIQCCSS described in connection with Figure 4' provides an effective solution.

.In' Eigure' 4,' 'foilr'zfeed fractions are prepared in a manner identical; to that described in connection with Figure13and are fed to thesystem, The lines through whichihcorresponding feed frrictiofnsf-aie introduced are indicated with the same numbers asthose' in "Figure'3e Specifically; the first or lowest boiling feed fraction is 'introduced through line? 106,;-thesecond or next heavier p I -.-fIn-t his modification; there-is provided a first contactinggcolumn 200 provided with separate. solids inlet 202 and .asecondycontacting column 204 With'solids inlet 206;- Again thegranular adsorbent'moves downwardly 126;r.and1at the :bottom "of regeneration "zone 142. These 4 engaginggazones are essentially 1' identical and :.indicated K numeral; 1823afol1owed- :bY'a'n appropriate yletter. dis-1 io hy m n continguishing one from.-thej other;v -A seal-fluid 'inlet line columns 202iand 204,

prise; methane ethane,- propane, mixtures thereof, natural" gas carbon dioxide, nitrogen; carbon-monoxide, hydro-i genitand the-dike. The :operatingqpressures of'the vari mlfixeontacting'zzonesearei controlled in conventional -waysa fraction is.-;introduced through linev 114, the third or next '-tof the"heavi'est' feedfraction is introduced through-line d the. fourthgor heaviestieed fraction flows as .a m oving.; bed through each contacting column, is d -respectively through lines 208 and 210,.and is combined for regeneration in regeneration zone 232.

Thepsfitrfiffonjregenerationemployed in this modifica tionei sl -identical to :thatshown and described in Figure 3.

A- suitableconveyor 214 for the regenerated solids is V provided 'tqlrfiiurn these solids to the top of each of ,In thisrnoification, two downward streams of ad-" sorbent are used. The sequence of feed mixture con v 'ture is substantiallybelow"the initial boiling point of the next rnixtu-re. For rnra'rnpler alternate feed fractions, in. Figure. 4, are passed successively,intocontact with the comprises a seriesin which the end point of one mi);-

downw moving.v bedkof absorbent in first contacting b r main s iee fifmba rn melr;

the even numbered ones, are similarly'passediinto" contact-with the adsorbent in second'column 204. If desired, three streams of adsorbent may be used and in this case the first stream of adsorbent contacts the first and fourth fractions, the second stream contacts the second and fifth fractions, and the third stream contacts the third and sixth fractions. Proportionally more fractions may be used if desired. More than three streams of adsorbent may be used, although ordinarily the two shown in Figure 4 and hereinafter described are suflicient toobtain ready efliuent fractionation.

In this manner the displacementexchange between the organic nitrogen compounds in a given feed fraction involves displacement of the nitrogen compounds originating in a feed fraction boiling considerably lower, the degree depending upon the individual system. 'In' this way there isa very substantial boiling point difference between the highest boiling nitrogen compound displaced from the solid material and the lowest boiling nitrogen compound which displaces it. For example,-with two adsorbent streams and alternate fraction contact, nitrogen compounds displaced from the adsorbent and having normal boiling points in the range of from 200 F. to 250 F. are displaced by nitrogen compounds whose normal boiling points lie for example between 300 F.'and 350 F. Thus the distillation separation between the 200 F. to 250 F. nitrogen compounds from the 300 F. to 350 F. boiling point hydrocarbons in a given effiuent stream is facilitated. 1

First contacting column'200 is provided with first con tacting zone 213 and third contacting zone 215. Second contacting column 204 is provided with second contact-"1;

ing zone 218 and fourth contacting zone 220. It is to be understood that in the event the feed stream isdistilled into more than four fractions such as for example 6, 8, 10, etc., proportionately increased numbers of contacting zones are provided in the'first and second contacting columns, that is, 3, 4, or 5 contacting zones each. If three contacting columns are used, the first, fourth, and seventh are introduced into. the first column, the second, fifth, and eighth'pass into the. second column, etc. Against, suitable seal fluids are introduced above and below each individual contacting zone to prevent interfiow of fluids therebetween.

In first contacting column 200 the downwardly moving metallo alumino silicate adsorbents first contacts the first feed fraction boiling between 120 F. and 250 F. producing a first effiuent flowing through line 222 and comprising only the hydrocarbon constituents boiling'between 120 F. and 250 F. The adsorbent containing the first fraction nitrogen compounds is then contacted in third contacting zone 216 with the third feed fraction, namely that boiling between 325 F. and 400 F. The 325 F. to 400 F. hydrocarbon effluent containing the displaced 120 F. to 250 F. nitrogen compounds is removed through line 224 and is distilled in still 226. The dis: tiilation is exceedingly easy since the highest boiling nitrogen compound boils at or below 250 F. and the lowest boiling hydrocarbon compound boils at or above 325 F. The nitrogen compounds are produced as an overhead distillate through line 228 and the hydrocarbon ing through line 114 and the fourth feed fraction flowing.

through line 124 The second feedfraction, freed of its nitrogen compounds on the regenerated adsorbent, flows through line 232 as a product of the process. The second fraction nitrogen compounds with normal boiling points between 250 F. and 325 F. are carried by the adsorbout downwardly intoifourth contacting mezzo where they-are removed from the adsorbent in displacement exchange for and by the fourth fraction nitrogen compounds boiling between 400 F. and 500 F; These nitrogen compounds are ultimately carried with the adsorbent into the regenerator and burned. The displaced 250 F. to 325 F. nitrogen compounds" and the 400 F. to 500 F. hydrocarbon eflluent flow from fourth contacting-zone220 through line 234into still 236. Here again the displaced nitrogen compounds boil well below the hydrocarbon fraction and are produced as an overhead prodnot through line 238 while the hydrocarbon fraction is produced as a bottoms product through line 240. The two nitrogen compound streams may be produced separately or in'combination as shown in Figure -4 through line 242. The same is true of the four individual hydrocarbon streams which may be produced in admixture with each other, if desired, through line 244. T

In the present process for hydrocarbon denitrogenation with the specific zeolitic metallo alumino silicate adbsorbents having pore diameters of 7 A. or greater, it has been found that the organic nitrogen compounds'are very strongly retained by the solid granular adsorbent even at temperatures as high as about 850 F. It is therefore not always necessary-that the contact pressure be reduced in thecase of hydrocarbon fractions boiling in the higher temperature ranges. The zeolitic adsorbent can be contacted at a temperature of 850 F. with gasoline derived from raw shale oil in the vapor phase and subf stantially all of the nitrogen compounds are successfully removed. The spent solid material is then contacted with a recirculated stream of flue gas containing small controlled amounts of air whereby the nitrogen compounds are burned atternpera'tures of the order-of 950 F; and the activity of the adsorbentis restored. The nitrogen compounds, whether they are basic or nonbasic,-are removed through treatment by the process of this invention to an extent of 99.5%. A substantially complete removal of all nitrogen compounds is thus realized.

In the processes described and illustrated in connection with Figures 3 and 4, the heaviest organic nitrogen compounds in a given series are lost by combustion when the; spent contact material is regenerated. The material which is lost includes the nitrogen compounds present in the highest boiling feed fraction which is processed 'in agivencontacting column. In Figure 3 the nitrogen compounds in the fourth feed fraction are thus lost while in Figure 4 the nitrogen compounds in the second and fourth feed fractions are lost. This procedure is probably the most practical method of operating in those instances where the hydrocarbon fraction of-the efiluent is the most important. If the nitrogen compounds are to be used in the'preparation of solvents, synthetic chemicals; and the like and are thus worth saving, a further modification of the contacting systems shown in Figures 1 and 2 may be employed. In those systems the granular adsorbent is first contactedwith one feed fraction, then with a higher boiling fraction and then with the-first feed fraction to produce two 'efiluents which are separately distilled or otherwise fractionated to produce separate hydrocarbon and nitrogen compound streams. It is within the contemplation of this invention to fractionate wide boiling range feed materials into a plurality of more than two fractions as indicated in Figures 3 and 4, to contact a static or moving bed of the herein definedadsorbw ent in sequence with these fractions. The sequence employed is one-of an increasing average boiling'pointas indicatedin the process described in Figure'3, but instead of regenertaing by combustion, the spent adsorbent after contact with the heaviest feed fraction is again contacted by one or more of the intermediate fractions having lower average boiling points to produce additional effluents which "are separately distilled. Finally the thus treated adsorbent is again contacted with the lightest feed fraction, and the process is repeated.- In this 'situa" given operating pressure.

enumeration thennitrogen: compounds;iaretflostzqthrough the number o'fifeedsfstreamsii zEach :efiluent is sepazlflfily distilled :to; [produce the. nitrogen; compounds -.as overhead products in the case of those effluents produced byrcontaeting. the adsorbenta'with. aheavieri feed vfraction tha lgit hadi1;contacted;aimmeditaelyr;-.:b.efore, rand. as. a

b toms: product'linir the; casei of 1 those-fiefiluents produced by contacting the adsorbent. withaateed fraction of lower M nage boilin-g oine than th immediately; previous Ec'ontha tn hfiu:adsorbentpmayibe contacted =with--fthe various feeds c'a'ms andawith :the; regeneration .gase's while suspended or fluidizeditaccoi'din'gi-t thefvvelliknovvn prinl- Although distillationpisrd scribed;-asytheiprocedurekfor separating the light and heavy co'nstituents'from .the vari-v lghzthmprevioilstdescmptionshas involvedthe use of the granular solid adsorbent thelformofstaticibeds and: downwardly moving beds, Jib-should; be understood a for produeingthe various feed;fractions in the first instance, it should "be"'understoodlthat other fraction methods mavbesubstituted, e5g.,:solve'nt: extraction, cryfstallizationsazeotropie .disti11ation,-.=steanr strippihgfafid other fractionation procedures; depending u on Ttl'ieknature' of the hydrocarbons and tlie nitrogen compounds contaminating the'sa'm'e:

:e'rherpmcess ofathisaiiivention rthus consists tofs anri'r n-i ppgruedadeinitr'ogenationvprocessi fonncontaminatedzhydro-i washing steps customary in prior adsorptionprocesses have been completely eliminated. The process of this invention may be operated under pressure or under vaccarbon mixtures employing the principles'of solid ads drp tion and fiuid'fractionation in such a way so as to remove organic nitrogen compounds from the feed stream and whereby the ordinary heating and gas stripping or liquid uum, and the, actual operating pressuresare actually determined by the pressure at which the 'feed' stream is,"

available and its boiling range, and whether the material being treated is desirably in the vapor phase or the liquid phase. The proper operating pressure can be determined aitregen-rree ing the no f seejond mi x 25 Y egaarsgaeo Ithedorganicsrnitrogenacornpo o s'aid nrinturesawhiclrprocess.comprises: (=1): contacting thezfir'stfobsaidunixtures with: a solid-partially? dehydrated z'eolitiermetallo aalumino. silicate adsorbent having-1 stantia'llyiuniformpores Iofat ileastabout: 7: A. :in. diameter and havingT (adsorbed thereon the organic nitrogen com-, pounds inciden'tntoetheisecond of said mixtures, whereby the -said ladsorbed' organic. nitrog'e'rr compounds incident to said second mixture: are. replaced: by the organic nitrogen compounds-containediin' said first: mixture and there is produced 'first efliuent comprising non-adsorbed hydro.- carbon om onents'of said first mixture audthedisplaced 2-) 'separatingitheorganic nitrogen compounds I dro'carbon product;- (3;). contacting'said ixture :with tlie adsorbent having adsorbeillther'e.- orga- 1 nitrogen'compounds incideritqto said. first iiiiiiturei-whe'rby he said ad sorlined organic nitrogen coma "saidfirs'tmixture are replacedlbythe.

'inpounds contained in said" second d t ere is produced a second eflluent; eompris= 'd'sorbed hydrocarbon" components of :said and the} displaced organic: nitrogen com? at gen-eonipbundsfrom said second efiluentito produc rid (-5-) c'eutinuing-tue alternate" contacting :of: said adso'b t with said first and second hydrocarbon i 2? A "s"- 'actrding t6- clainr l -wherein the said;

' first and second hydrocarbon mixtures are obtained by the fractionation of a single feed stream of relatively wide boilingrange into a relatively low-boiling fraction and a relatively high-boiling fraction..

3. A process according to claim 1 wherein, in steps (2) and (4) the said separations are effected bydistillation.

4. A process according to claim 1 wherein the amounts of said first and second hydrocarbon mixtures employed in steps (1) and (3) are so proportioned relative to each i other that the time required to replace the adsorbed nitro-.

by those skilled in the art from known physical vcharacteristics of the materials to be separated, vnamely, the

bubble-point and dew point'ofthe' hydrocarbon feed stream and the known way in which these change with pressure. The operating temperatures employed in the process of this invention are also determined by the} physical characteristics of the feed streamand-the operating pressure, and also whether a vapor phase or a liquid phase operation is desired. In the complex gasoline streams the'operating temperature is largely determined by the dew point and the bubble point, of the stream a'ta' I For; example, operating 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.

'cient to burn hydrocarbonaceous residues therefrom.

6. A process-according toclaim l'wherein the said adsorbent is maintained in the "form of a fixed compact bed,,and said contacting steps are. carried out bypassing contemplation of the present invention to adsorbthe feed stream at a temperature between its bubble point and its dew point so that mixed phase contacting will be main- .tained for some special streams. Obviouslythe feed contact maybein the vaporpbase followed by recycle stream contact in the liquid phase, .or'vice versa, if desired.

A particular embodiment of the present invention has i been hereinabove described in considerable detail byway It should be understood that various of illustration. other modifications and adaptations thereof may made bythose skilled in this particular art without departing from-the spirit and scope ofthis invention as set ,forth' a in the appended claims. v a

i We claim: a

9. Aprocess according to claim 2 wherein the said." fractionation is so controlled that the amounts of said.

1. A process for denitrogenating. two hydrocarbon mixtures, each'of which contains normally incident organic nitrogen compounds, the organic nitrogen compounds contained in the first of said mixtures being difierent from said first and second hydrocarbon mixtures therethrough in opposite directions.

7'. Aprocess according to claim 1 wherein stepsy(1) and (3) are efiiected in first and second contacting zones,

respectively, and said adsorbent is circulated continuously and successively therethrough'.

8. A process according to claim 1 wherein the diameter of the pores of said adsorbent is between about 7 A. and

about 13A.

low-boiling and said high-boiling fractions are such that the time'required to replace the adsorbed nitrogen compounds in step (1) issubstantially equal to the time required to replace the adsorbed nitrogen compounds in step (3). v

10. A process according to claim 4 wherein said amounts of said first and second hydrocarbon mixturesemployedin steps (1).and (3) are controlled by varying the individual rates at which said mixtures are contacted with the adsorbent in said steps (1) and (3).

Y '11. Aprocess for denitrogenating a. plurality of hyvdrocarbonnrixtures comprising a mixture of lowest boil-' range, a mixture of highest boiling range, and at trogenjcompounds' incident: to said second said first mixture; ('4) separating the second 'substantially nitrogen f'ree "hydrocarbon leastcne mixture of intermediateboiling range, each of said mixtures being contaminated with normally incident organic nitrogen compounds, which process comprises: (1) contacting the said mixture of lowest boiling range with a solid partially dehydrated zeolitic metallo alumino silicate adsorbent having substantially uniform pores of at least about 7 A. in diameter, whereby there is obtained a lowest boiling effluent containing the nonadsorbed hydrocarbon components of said lowest boiling mixture and any nitrogen compounds previously adv sorbed on said adsorbent; (2) thereafter contacting the adsorbent with the mixture of next highest boiling range, whereby there is obtained anintermediate boiling effluent comprising the non-adsorbed hydrocarbon components of said mixture of next highest boiling range and organic nitrogen compounds adsorbed in the preceding contacting step; (3). repeating step (2) until all of said mixtures of intermediate boiling range-have been contacted with said adsorbent; (4) contacting the adsorbent with said mixture of highest boiling range, whereby there isobtained a highest boiling efiiuent comprising the non-adsorbed hydrocarbon components of said highest boiling effluent and'organic nitrogen compounds adsorbed in the preceding contacting step; 7 (5) regenerating the adsorbent after said contacting with, said highest boiling fraction; and (6) separating .the organic nitrogen compounds from each of said effluents to produce hydro: carbon mixtures of substantially reduced nitrogen content.

12. A process according to claim 11 wherein, in step (5), said adsorbent is regenerated by contacting it with [:16 an oxygen-containinggas at a temperature sufificientto burn hydrocarbonaceous residues therefrom. 13. A process according to claim ll'wherein the" diameter of the pores of said adsorbent is between about 7A. and about 13 A. I I

14. A process-according to claim=11 wherein thesaid plurality of hydrocarbon'mixtures is obtained by the fractional distillation of a single hydrocarbon mixture of relatively wide boiling range. al

15. A process according to claim 11 wherein each' of said contacting steps is effected in a separate contacting zone, and said adsorbent is circulated continuously and successively therethrough. I? 16. A process according to claim 11 wherein, in step (5), the said adsorbent is regenerated by contacting it with at least one of said mixtures having a boiling range below that of said highest boiling mixture. a 17. A process accordingto claim 11 wherein 'the pore diameter of said adsorbent is about 13 A. 1

"References Cited in the file of this patent UNITED STATES PATENTS 2,606,143 Smith et al. Aug. 5, 1952 2,763,603 Skinner ..Y Sept. 18, 1956 2,779,718

Claims (1)

1. A PROCESS FOR DENITROGENATING TWO HYDROCARBON MIXTURES, EACH OF WHICH CONTAINS NORMALLY INCIDENT ORGANIC NITROGEN COMPOUNDS, THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN THE FIRST OF SAID MIXTURES BEING DIFFERENT FROM THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN THE SECOND OF SAID MIXTURES, WHICH PROCESS COMPRISES: (1) CONTACTING THE FIRST OF SAID MIXTURES WITH A SOLID PARTIALLY DEHYDRATED ZEOLITIC METALLO ALUMINO SILICATE ADSORBENT HAVING SUBSTANTIALLY UNIFROM PORES OF AT LEAST ABOUT 7 A. IN DIAMETER AND HAVING ADSORBED THEREON THE ORGANIC NITROGEN COMPOUNDS INCIDENT TO THE SECOND OF SAID MIXTURES, WHEREBY THE SAID ADSORBED ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID SECOND MIXTURE ARE REPLACED BY THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID FIRST MIXTURE AND THERE IS PRODUCED A FIRST EFFLUENT COMPRISING NON-ADSORBED HYDROCARBON COMPONENTS OF SAID FIRST MIXTURE AND THE DISPLACED ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID SECOND MIXTURE, (2) SEPARATING THE ORGANIC NITROGEN COMPOUNDS FROM SAID FIRST EFFLUENT TO PRODUCE A FIRST SUBSTANTIALLY NITROGEN-FREE HYDROCARBON PRODUCT, (3) CONTACTING SAID SECOND MIXTURE WITH THE ADSORBENT HAVING ADSORBED THEREON THE ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID FIRST MIXTURE, WHEREBY THE SAID ADSORBED ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID FIRST MIXTURE ARE REPLACED BY THE ORGANIC NITROGEN COMPOUNDS CONTAINED IN SAID SECOND MIXTURE AND THEREIS PRODUCED A SECOND EFFLUENT COMPRISING THE NON-ADSORBED HYDROCARBON COMPONENTS OF SAID SECOND MIXTURE AND THE DISPLACED ORGANIC NITROGEN COMPOUNDS INCIDENT TO SAID FIRST MIXTURE, (4) SEPARATING THE ORGANIC NITROGEN COMPOUNDS FROM SAID SECOND EFFLUENT TO PRODUCE A SECOND SUBSTANTIALLY NITROGEN-FREE HYDROCARBON PRODUCT, AND (5) CONTINUING THE ALTERNATE CONTACTING OF SAID ADSORBENT WITH SAID FIRST AND SECOND HYDROCARBON MIXTURE.

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